CN109964384B - Battery charging system with regulating loop - Google Patents

Abstract

A charging system (100, 200) for a battery (140) of an electronic device is described. The charging system (100, 200) includes an adapter (110) configured to obtain a converted current at a converted voltage (121) from a power source. Furthermore, the charging system (100, 200) includes a battery charger (130) configured to charge the battery (140) of the electronic device with the battery current at the battery voltage (141) by using the switching current at the switching voltage (121) ). Additionally, the charging system (100, 200) includes a power transfer device configured to transfer a converted current at the converted voltage (121) to the battery charger (130). Additionally, the charging system (100, 200) includes a communication device configured to transmit feedback information indicative of battery voltage and/or battery current from the battery charger (130) to the adapter (110). The adapter (110) is configured to set the switching voltage (121) and/or the switching current according to the feedback information.

Description

Battery charging system with regulation loop

technical field

This document relates to systems and methods for charging batteries in an energy-efficient manner.

Background technique

High voltage (HV) battery chargers with input voltage V _in in the range of 20V typically utilize inductor-based power converters, achieving conversion efficiencies in the range of about 90%. This relative inefficiency is due to the fact that the efficiency of the inductive buck power converter is optimal for an output voltage V _out that is only slightly lower than the input voltage V _in (ie, when the conversion ratio V _out /V _in is about 1).

The battery or output voltage is typically V _out = 3.6V (ie <4.2V) and the input voltage _Vin (also referred to herein as the switching voltage) from the external power source can be as high as 20V. As a result, the conversion ratio V _in /V _out is relatively high and the power conversion efficiency is generally reduced. Switching frequency is a parameter that affects the efficiency of an inductive buck converter, where the efficiency of a power converter generally increases as the switching frequency decreases. On the other hand, reasonable current ripple at relatively low switching frequencies typically requires inductors with relatively high inductance. Inductor size generally increases with inductance. Therefore, the use of inductors with relatively high inductance is generally incompatible with modern portable electronic devices such as thin tablet PCs or smartphones. Consequently, battery chargers for portable electronic devices typically use relatively low inductance coils, triggering relatively high switching frequencies, thereby limiting the maximum achievable conversion efficiency of the battery charger's power converter.

This document solves the technical problem of providing an energy-efficient and compact system for charging batteries of electronic devices.

The independent claims solve this technical problem. Furthermore, improvements are described in the dependent claims.

Contents of the invention

According to one aspect, a charging system for an electronic device battery is described. The charging system includes an adapter configured to obtain power at the converted voltage from the power source. In particular, the adapter can be configured to take the switching current at the switching voltage. For example, the power supply may provide AC power at an AC voltage such as 110V or 230V with an AC frequency of 60 Hz or 50 Hz. On the other hand, the converted voltage is usually a DC voltage (eg, in the range of 10V) and the converted current is usually a DC current. As such, the adapter may include an AC/DC converter for deriving power at a DC converted voltage from AC power provided by the power source. The adapter may comprise a wall plug adapter, ie the adapter may comprise a power plug for connecting the adapter to a wall socket, such as a mains wall socket.

Furthermore, the charging system comprises a battery charger configured to charge the battery of the electronic device with the battery current at the battery voltage by using the power at the switching voltage, in particular using the switching current at the switching voltage. Thus, the battery current at the battery voltage is provided at the output of the battery charger. The battery current may be regulated to a (possibly predetermined) target battery current (such as to a constant target battery current or a target battery current following a predetermined charging profile; the target battery current may for example depend on temperature and/or on the history of the battery to be charged and/or depending on previous charging behavior). Regulation of the battery current can be performed by a current regulator within the battery charger or a current regulator within the power adapter. A battery charger may be implemented as part of an electronic device. Typically, adapters and battery chargers are implemented as separate physical units, especially separate integrated circuits (ICs).

The charging system also includes a power transfer device configured to transfer power at the switching voltage (ie, switching current at the switching voltage) to the battery charger. In particular, the power transfer means may comprise a charging cable, in particular a USB (Universal Serial Bus) charging cable, which transfers power in a conductive manner. Alternatively or additionally, the power transfer device may comprise a wireless power transfer unit (eg as part of an adapter) configured to generate an electromagnetic charging field by using power at the switching voltage, ie switching current at the switching voltage. To this end, the wireless power transfer unit may include a transfer coil. Additionally, the power transfer device may include a wireless power receiving unit (eg as part of a battery charger) configured to harvest power at the switching voltage (ie switching current at the switching voltage) from the electromagnetic charging field. To this end, the wireless power transfer unit may include a receiving coil.

Power transfer devices typically exhibit voltage drop and/or power dissipation. Therefore, the switching voltage and/or switching current (ie, switching power) at the input of the battery charger is generally lower than the switching voltage and/or switching current (ie, switching power) at the output of the power adapter. The voltage drop and/or power consumption of the power delivery device can be predicted (eg, by system design) and/or can be transmitted as feedback information from the battery charger to the power adapter. In this way, the power adapter may take into account the voltage drop and/or power consumption of the power transfer device when setting (in particular when adjusting) the switching voltage and/or the switching current. It should be noted that any voltage drop in the power transmission means (eg lines) is usually automatically compensated when the switching current is adjusted within the power adapter. On the other hand, the maximum voltage drop at the power transmission device may be taken into account when configuring or setting the upper limit of the switching voltage. In particular, the switching current can be adjusted such that the switching voltage does not exceed a predetermined maximum switching voltage. The predetermined maximum switching voltage may depend on the voltage drop at the power transfer device.

Additionally, the charging system includes a communication device configured to transmit feedback information indicative of battery voltage and/or battery current from the battery charger to the adapter. In particular, this feedback information to be provided at the output of the battery charger charging the battery may be indicative of a target battery voltage and/or a target battery current. The target battery voltage and/or the target battery current may be determined by a control unit of the battery charger (eg from information about the battery state of charge SOC).

The battery charger may include a transmit communication module configured to transmit feedback information over the communication channel. Additionally, the adapter may include a receiver communication module configured to receive feedback information via the communication channel. The communication channel may include electrical conductors of the charging line for conducting power or switching current at switching voltage from the adapter to the battery charger. Alternatively or additionally, the communication channel may comprise a radio frequency link, such as a Bluetooth link, a WLAN link, a UMTS link and/or an LTE link.

The adapter is configured to set (in particular regulate) the switching voltage and/or the switching current according to the feedback information. In particular, the adapter can be configured to set (in particular regulate) the switching voltage or the switching current. As a result, power may be provided to the battery charger such that efficiency of the battery charger is increased (eg, maximized) and/or power consumption of the battery charger is reduced (eg, minimized). Thus, an energy efficient (and possibly size efficient) charging system may be provided.

In particular, the adapter may be configured to set (e.g. regulate) the switching voltage such that a battery current applied within the battery charger charges the battery (in particular a (varying) battery current at a (constant) target battery voltage. ) The voltage conversion ratio (V _in /V _out , ie the ratio of the input voltage of the power converter of the battery charger to the output voltage of the power converter) of the battery current charging the battery) is an integer n equal to or greater than 1. Therefore, the output voltage is n times smaller than the input voltage. The voltage conversion ratio may also be referred to as a reduced conversion ratio in which the output voltage of the power converter is n times smaller than the input voltage of the power converter.

Alternatively or additionally, the adapter may be configured to set (e.g. regulate) the switching current so that the battery current applied within the battery charger charges the battery with the battery current at the battery voltage (in particular at the (constant) battery voltage at the (varying) battery voltage. The current conversion ratio (I _out /I _in , ie the ratio of the output current of the power converter of the battery charger to the input current of the power converter) of the target battery current to charge the battery) is an integer n equal to or greater than 1. Therefore, the output current is n times higher than the input current. As a result thereof, efficacy can be further improved. The current conversion ratio may also be referred to as a boost conversion ratio in which the output current of the power converter is n times higher than the input current of the power converter.

The battery charger may include a current regulator configured to use the power at the converted voltage to regulate the battery current to charge the battery. Alternatively or additionally, the power adapter may include a current regulator for indirectly regulating the battery current through regulation of the commutated current at the output of the power adapter.

The battery charger may comprise a control unit configured to select a charging strategy for charging the battery and configured to control a current regulator at the battery charger and/or the power adapter based on the selected charging strategy. For example, the charging strategy can define the target battery current as a function of battery SOC. For example, charging strategies may be designed to increase (eg, maximize) battery life and/or battery charge cycle count. The control unit may be configured to determine (information about) the SOC of the battery. Furthermore, the control unit may be configured to determine the target battery current based on (information about) the SOC (and typically based on a predetermined charging strategy). The target battery current may be used by a current regulator to regulate the battery current to the target battery current. This may require setting the battery voltage to a certain value such that the battery current corresponds to the target battery current. By providing feedback information to the adapter indicative of a desired battery voltage and/or indicative of a target battery current, the adapter can modify the switching voltage and/or switching current as outlined in this document, thereby increasing the power efficiency of the charging system.

In other words, the battery charger may comprise a control unit configured to determine the target battery current. The current regulator (at the battery charger and/or the power adapter) may be configured to derive the battery voltage according to the target battery current, in particular such that the battery current at the output of the battery charger corresponds to the target battery current. Therefore, battery voltage may vary over time. Therefore, feedback information of changes can be provided to the adapter.

Current regulators may include battery switches and/or low dropout (LDO) regulators. Additionally, the current regulator may exhibit a regulator voltage drop V _rdrop . The adapter (in particular the adapter's voltage regulator) can be configured to switch the voltage according to the regulator voltage drop V _rdrop setting, thereby further improving the power efficiency of the charging system. Minimizing V _rdrop is especially beneficial for efficiency when the battery switch is closed (that is, when the LDO is operating in bypass mode). Whenever the LDO is plugged into dropout voltage from regulation, power dissipation increases and efficiency decreases. In this way, it may be beneficial to transfer the task of regulating the battery current to the adapter, which may be configured to provide the (regulated) switching current according to the desired battery current, ie according to the target battery current. In other words, it may be beneficial to move the current regulator from the battery charger to the power adapter. For this reason, battery chargers do not include current and/or voltage regulators.

The battery charger may include a power converter configured and/or operable to perform down conversion of the converted voltage (at the battery charger input) at a down conversion ratio n, where n is an integer greater than or equal to one. In a similar manner, the power converter may be configured and/or operated to perform boost switching of the switching current (at the battery charger input) at a boost switching ratio n, where n is an integer greater than or equal to one. Power converters with this feature can exhibit particularly high conversion efficiencies. This is especially true for power converters comprising or corresponding to capacitive power converters. The adapter can be configured to set (in particular regulate) the switching voltage and/or the switching current (at the adapter output) according to the step-down or boost-turn ratio n. Therefore, the power efficiency of the charging system can be further improved.

A power converter may exhibit a converter voltage drop V _cdrop . The adapter may be configured to convert voltage and/or convert current (at the adapter output) according to the converter voltage drop V _cdrop setting (in particular regulation), thereby further improving the power efficiency of the charging system.

As mentioned above, the adapter may include a voltage regulator configured to adjust the conversion voltage based on feedback information, in particular based on the target battery voltage. Specifically, the converted voltage V _in can be adjusted to correspond to V _in =nx(V _bat +V _cdrop )+V _rdrop , where V _bat is the desired battery voltage (ie, the target battery voltage), and V _cdrop is the power of the battery charger The voltage drop at the converter, V _rdrop is the voltage drop at the power transfer device. Alternatively or additionally, the converted voltage may be set or adjusted such that the (target) battery voltage is obtainable from the converted voltage by the battery charger (only) using a buck conversion with a reduced conversion ratio n, where n is equal to or greater than 1 integer.

The adapter may be configured to limit the maximum switching current based on the current rating of the battery charger, power converter, power conversion path (such as a charging cable or wireless power transfer device), or based on the maximum battery current.

Furthermore, the adapter can be configured to provide (in particular regulate) a constant switching current, a corresponding switching voltage is also set. The switching voltage can be limited to a maximum level, which can be taken from the input voltage rating of the battery charger, or can be determined by multiplying the maximum battery voltage (plus the voltage drop in the power converter) by the switching ratio n. This configuration may allow removal of the battery charger (especially the current regulator at the battery charger) and its losses.

In this way, the adapter can be configured to set (e.g. regulate) the conversion current based on feedback information (in particular based on the target battery current), so that the battery voltage can be supplied by the battery charger by (only) using a buck converter with a reduced conversion ratio n Obtained from the converted voltage, where n is an integer equal to or greater than 1 (such that the converter's output voltage is n times smaller than the converter's input voltage), and/or makes the (target) battery current available by (only) using a converter with a boost The current boost converter is derived by the battery charger from the converted current by a ratio n, where n is an integer equal to or greater than 1 (such that the output current of the converter is n times higher than the input current of the converter). To this end, the adapter can also include a current regulator. For this reason, the battery charger can be made without a current regulator, thereby further increasing the efficiency of the battery charger. In particular, the energy path within the battery charger (for deriving power for charging the battery at the battery charger output from power at the battery charger input) may only include power converters with integer conversion ratios.

The adapter can be configured to regulate the switching voltage so that the switching current does not exceed a predetermined maximum switching current. Or the adapter may be configured to regulate the switching current so that the switching voltage does not exceed a predetermined maximum switching voltage. The maximum switching current and/or the maximum switching voltage may be fixed. Or the maximum switching current and/or the maximum switching voltage can be set by the battery charger through communication. In particular, the feedback information may indicate a maximum switching current and/or a maximum switching voltage.

According to a further aspect, an adapter for a charging system for charging an electronic device battery is described. The adapter includes a receiver communication module configured to receive feedback information indicative of the battery voltage and/or battery current used to charge the battery (in particular the feedback information may indicate the battery voltage provided at the output of the battery charger for charging the battery). target battery voltage and/or target battery current). The battery voltage may be used by a current regulator of a corresponding battery charger to set the battery current according to a predetermined target battery current. The battery voltage may be varied over time to provide a battery current that is set (eg, regulated) according to a predetermined target battery current (eg, a constant target battery current). Alternatively or additionally, regulation of the battery current may be performed by the adapter.

Additionally, the adapter includes a voltage regulator and/or a current regulator configured to obtain power at the switching voltage (eg, switching current) from the power source based on feedback information. In particular, the switching voltage may be obtained from a battery voltage set for charging the battery (ie from a target battery voltage). Alternatively or additionally, the switching current may be derived from the battery current used to charge the battery (ie from the target battery current). In view of the fact that battery voltage and/or battery current may vary over time, the transition voltage and/or battery current may correspondingly vary over time. In addition, the adapter includes a power transfer interface (such as a suitable plug or socket) for supplying power (such as switching current) at a transfer voltage to a battery charger for charging the battery via power transfer means (such as via a charging cable) ).

In a preferred example, the adapter includes a receiver communication module configured to receive feedback information indicative of a target battery voltage and/or a target battery current for charging the battery. The target battery voltage and/or the target battery current may be set by a control unit of a corresponding battery charger of the electronic device. For example, a (usually constant) target battery current can be set by the control unit until the battery reaches a predetermined state of charge SOC (eg 90%). After reaching a predetermined SOC, a (usually constant) target battery voltage may be set by the control unit in order to complete charging of the battery (eg to substantially 100% SOC).

Additionally, the adapter may include a voltage regulator and/or a current regulator configured to obtain the switching current at the switching voltage from a power source (eg, from a mains supply) based on feedback information. In particular, the voltage regulator may adjust the conversion voltage according to the target battery voltage (eg when the control unit of the battery charger sets a constant target battery voltage in order to request constant voltage charging). Alternatively or additionally, the current regulator may regulate the switching current according to the target battery current (eg when the control unit of the battery charger sets a constant target battery current in order to request constant current charging).

The voltage regulator can be configured to adjust the conversion voltage based on feedback information (in particular based on the target battery voltage), by (only) using the electronics (or battery charger) to reduce the buck conversion with a conversion ratio n, where n is equal to or greater than An integer of 1 such that the battery voltage used to charge the battery (at the output of the battery charger) is regulated to the target battery voltage. In particular, the switching voltage may be adjusted to a target switching voltage corresponding to n times the target battery voltage (plus possible voltage drops at the power converter of the power transfer device and/or battery charger).

The current regulator can be configured to regulate the switching current based on feedback information (in particular based on the target charging current), by (only) using the electronics (or battery charger) to boost the switching current by a switching ratio n, where n is equal to or greater than An integer of 1 such that the battery current used to charge the battery (at the output of the battery charger) is regulated to the target battery current. In particular, the commutation current can be adjusted to a target commutation current corresponding to 1/n times the target battery current (plus the current that may be consumed in the battery charger).

In addition, the adapter includes a power transfer interface for providing the switching current at the switching voltage to the battery charger charging the battery by means of power transfer.

According to another aspect, a battery charger for charging a battery of an electronic device is described. The battery charger includes a power receiving interface (such as a suitable plug or socket) for receiving power (such as a switching current) at a switching voltage through the power transmission means (such as via a charging cable). Additionally, the battery charger may include a current regulator configured to regulate battery current to charge the battery by using power at the converted voltage. Provides battery current at battery voltage. In particular, the current regulator may be configured to set the voltage at the output of the current regulator such that the battery is charged with the (eg constant) battery current. Battery voltage can vary over time. In particular, battery voltage may vary with the state of charge (SOC) of the battery.

The battery charger may comprise a transmission communication module configured to transmit feedback information indicative of a (target) battery voltage and/or a (target) battery current over a communication channel. For this reason, the corresponding adapter can use the feedback information to provide power at a switching voltage, where the switching voltage can depend on the feedback information (in particular on the (target ) battery voltage and/or (target) battery current).

In a preferred example, the battery charger includes a power receiving interface for receiving the switching current at the switching voltage through the power transmission means. Furthermore, the battery charger may comprise a control unit configured to determine a target battery current and/or a target battery voltage for charging the battery. In particular, the control unit may be configured to determine information about the SOC of the battery. Based on the information about the SOC, the control unit may then determine a target battery current and/or a target battery voltage for charging the battery. Information about the battery SOC may include the (idle) battery voltage (ie, the voltage drop at the battery when the battery is neither charging nor discharging). Typically, the (idle) battery voltage increases as the battery SOC increases, providing an accurate indication of SOC.

The battery can be charged to a predetermined (idle) battery voltage and/or a predetermined SOC with a constant target battery current. In turn, the battery can be charged with a constant target battery voltage. In this way, the control unit may determine a target battery current for charging the battery during the first phase of the charging cycle. Furthermore, the control unit may determine a target battery voltage for charging the battery during the second phase of the charging cycle. The moment of switching from the first phase to the second phase may depend on information about the battery SOC. The moment of switching from the first phase to the second phase may be indicated in the feedback information.

Additionally, the battery charger may include a power converter (eg, a capacitive power converter). The power converter may be configured or operated to perform step-down conversion of the converted voltage (at the input of the battery charger) at a reduced conversion ratio n, where n is greater than or equal to 1, to provide a battery voltage for charging the battery integers (in particular n=2). In other words, the power converter can be arranged to perform down conversion of the converted voltage by reducing the conversion ratio n so that the battery voltage used to charge the battery corresponds to 1/n of the converted voltage (removing the Voltage drop).

Alternatively or additionally, the power converter may be configured or operable to perform current boost conversion of the converted current (at the input of the battery charger) at a boost conversion ratio n to provide the battery current for charging the battery, wherein n is an integer greater than or equal to 1. In other words, the power converter may be arranged to perform current boost conversion of the conversion current at a boost conversion ratio n such that the battery current used to charge the battery corresponds to n times the conversion current. Typically, a power converter performs (roughly) buck conversion and (precise) current boost conversion. The use of integer conversion ratios allows for energy saving and space saving within the battery charger.

In a preferred example, the battery charger does not include a voltage regulator (for regulating the battery voltage to a target battery voltage) and/or a current regulator (for regulating the battery current to a target battery current). Instead, the battery charger includes a transmit communication module configured to transmit feedback information indicative of a target battery voltage and/or a target battery current over a communication channel.

The feedback information may be received by a corresponding power adapter configured to adjust the switching voltage according to the target battery voltage and/or configured to adjust the switching current according to the target battery current. In particular, during the constant current charging phase, the power adapter can be configured to regulate the switching current (at the output of the power adapter) so that the battery charger can convert from the switching current (at input to the battery charger) to obtain a (constant) target charge current. During the constant voltage charging phase, the power adapter can be configured to regulate the converted voltage (at the output of the power adapter) such that the battery charger can convert from the converted voltage (at the battery charger input) to obtain a (constant) target charging voltage.

Feedback information may be provided (only) when the target battery current and/or target battery voltage changes. In this way, the transmission of feedback information from the battery charger to the adapter can be triggered by the control unit of the battery charger. As an example, if it is determined at the battery charger (eg, by the control unit) that the target battery current and/or target battery voltage for charging the battery will vary, feedback information may be provided to the adapter, wherein the feedback information indicates the requested target Changes in battery current and/or target battery voltage. In this way, the (whole) charging cycle of the battery can be controlled by the battery charger (in particular the control unit) using selectively transmitted feedback information.

As the battery SOC increases, it may appear that the adapter may need to significantly increase the switching voltage in order to adjust the switching current to the target battery current. In order to protect components at the power adapter and/or battery charger, the power adapter, in particular the current regulator, may be configured to regulate the switching current such that the switching voltage does not exceed a predetermined maximum switching voltage. In a similar manner, adjusting the switching voltage according to the target battery voltage may result in excessive switching current. The adapter, in particular the voltage regulator, may be configured to regulate the switching voltage such that the switching current does not exceed a predetermined maximum diverted current.

In another example, the adapter and battery charger may be configured to provide a closed regulation loop for regulating the battery voltage and/or battery current at the output of the battery charger by using a voltage regulator and/or a current regulator at the adapter . To this end, feedback information may be repeatedly or periodically (eg, at 1 Hz, 10 Hz, 100 Hz or higher frequency) provided from the battery charger to the adapter. The (periodic) feedback information may then be indicative of the (actual) battery voltage and/or the (actual) battery current at the output of the battery charger. The battery charger may comprise means for measuring the (actual) battery voltage and/or the (actual) battery current at the output of the battery charger.

The voltage regulator and/or current regulator at the adapter can use the feedback information to adjust the switched voltage and/or diverted current so that the (actual) battery voltage and/or (actual) battery current at the output of the battery charger is regulated to the target battery voltage and/or target battery current. In particular, a closed-loop voltage regulator can be provided at the adapter, which sets the transition voltage (at the adapter output) according to the (actual) battery voltage, in particular according to the deviation of the (actual) battery voltage from the target battery voltage, so that Provides closed-loop voltage regulation of the battery voltage. Alternatively or additionally, a closed-loop current regulator can be provided at the adapter, which sets the switching current (at the adapter output) according to the (actual) battery current, and in particular according to the deviation of the (actual) battery current from the target battery current , thereby providing closed-loop current regulation of the battery current. The quality of battery voltage and/or battery current regulation can be further improved (at the expense of periodic or repeated transmission of feedback information) by providing closed-loop regulation through the adapter and battery charger.

According to another aspect, a method of charging a battery of an electronic device using an adapter and a battery charger is described. The adapter and battery charger are independent of each other. The method includes using an adapter to obtain power at a diverted voltage (eg, diverted current) from a power source. Additionally, the method includes transferring power at the switched voltage (eg, switched current) from the adapter to the battery charger. Additionally, the method includes charging a battery of the electronic device with a battery current at a battery voltage, wherein the battery current is derived from power (eg, a switching current) at a switching voltage using a battery charger. The method also includes transmitting feedback information indicative of the battery voltage and/or battery current from the battery charger to the adapter, wherein the switching voltage and/or switching current are set (in particular regulated) by the adapter based on the feedback information. The feedback information may in particular be indicative of a target battery voltage and/or a target battery current for battery charging provided at the output of the battery charger. In this way, the switching voltage and/or the switching current at the output of the adapter can be adjusted according to the target battery voltage and/or the target battery current.

It should be noted that the methods and systems, including the preferred embodiments outlined in this document, can be used alone or in combination with other methods and systems disclosed in this document. Furthermore, the features outlined in the context of the system also apply to the corresponding method. Furthermore, all aspects of the methods and systems outlined in this document can be combined in any combination. In particular, the features of the claims can be combined with one another in any desired manner.

In this document, the terms "coupled" or "coupled" mean that elements are in electrical communication with each other, whether directly connected, such as by wires, or in some other way.

Description of drawings

The invention is explained in an exemplary manner below with reference to the accompanying drawings, in which:

Figure 1 shows a block diagram of an example system for charging a battery;

Figure 2 shows a block diagram of another example system for charging a battery;

Figure 3 shows a flow diagram of an example method for charging a battery; and

4 shows a block diagram of another example system for charging a battery.

Detailed ways

As stated above, this document addresses the technical problem of charging batteries of electronic devices in a power and space efficient manner. In particular, in order to reduce power consumption within electronic equipment, it is desirable to increase the efficiency of charging systems, especially power converters included in battery chargers of the charging systems, to 95% or higher.

FIG. 1 shows a block diagram of an example charging system 100 including a wall plug adapter 110 , a charging cable 120 (eg, a USB cable) and a battery charger 130 . Typically, a battery charger 130 is incorporated into an electronic device, such as a smartphone or a tablet computer, to charge a battery 140 of the electronic device. The adapter 110 includes an AC/DC regulator 111 (in particular a voltage regulator) configured to generate a DC (direct current) converted voltage 121 from an AC (alternating current) source voltage, such as an AC mains voltage of 110V, 220V or 240V. The DC converted voltage 121 is provided to the power converter 131 of the battery charger 130 via the charging line 120, wherein the power converter 131 is configured to convert the converted voltage 121 into a system voltage 135, wherein the system voltage 135 generally corresponds to the voltage used to power the battery 140 The charged battery voltage V _bat 141 is added to the dropped voltage V _cdrop at the charging unit 133 .

The charging unit 133 (or current regulator) may be configured to provide a predetermined battery current to the battery 140 at a (typically varying) battery voltage 141 for charging the battery 140 . To this end, the charging unit 133 may include a battery switch and/or a battery regulator (such as a low dropout LDO regulator), as well as a current sensing device for sensing the battery current. The charging unit 133 can be controlled by the control unit 134 . Specifically, the charging unit 133 may be controlled such that a battery current according to a (predetermined) target battery current may be supplied.

Furthermore, charging system 100 includes communication means enabling battery charger 130 to communicate with adapter 110 . In particular, the communication means enables the battery charger 130 to provide feedback information to the adapter 110 . Additionally, the adapter 110 may be configured to adjust the operation of the AC/DC regulator 111 based on the feedback information. The communication means includes a communication module 132 within the battery charger 130 and a corresponding communication module 112 within the adapter 110 . The feedback information can be transmitted from the communication module 132 of the battery charger 130 to the communication module 112 of the adapter 110 via the charging cable 120 (eg, via the communication wire 122 of the charging cable 120 ). The feedback information may be provided by the control unit 134 of the battery charger 130 . The feedback information may indicate or correspond to the battery voltage 141 used by the charging unit 133 to charge the battery 140 .

By using two-way communication between battery charger 130 and adapter 110, adapter 110 can inform battery charger 130 of its capabilities (eg, maximum voltage and/or current) during initial negotiation. The adapter 110 may also send an acknowledgment of commands received from the battery charger 130 or flag a communication error (eg, an invalid command).

As noted above, the goal of this document is to increase (eg, maximize) the efficiency of the battery charger 130 . To this end, the switching voltage 121 (also referred to as the input voltage of the battery charger 130) can be set to exactly n times the battery voltage _Vbat 141 plus the drop voltage _Vcdrop on the charging unit 133 and possibly plus the voltage in the power converter 131 some voltage drop V _pdrop . This can be achieved by adjusting the voltage at the output of the AC/DC regulator 111 according to the desired battery voltage V _bat 141 . As shown in FIG. 1 , communication from the battery charger 130 to the adapter 110 may be accomplished through wall plug communication using the charging cable 120 . In particular, the battery voltage 141 and/or the required switching voltage 121 can be sent to the adapter 110 as feedback information. The AC/DC regulator 111 may then be operated such that the desired converted voltage 121 is provided to the input of the battery charger 130 .

The power converter 131 may include a capacitive power converter. Furthermore, the power converter 131 may be configured to provide an integer reduced conversion ratio n in an energy-efficient manner, as is the case when a properly designed capacitive power converter is used. As a result of providing input voltage 141 to power converter 131 with n times the desired battery voltage 141 (typically plus the voltage drop at power converter 131 and/or charging unit 133 ), power converter 131 can operate at a maximum Operate at the optimum operating point for conversion efficiency.

It should be noted that communication between battery charger 130 and adapter 110 is not limited to communication via wire 120 (eg, via a USB wire). As shown in the charging system 200 of FIG. 2 , wireless communication 222 with the wall plug adapter 110 is performed using an appropriate wireless communication module 232 , 212 . Example wireless communication schemes are Bluetooth, wireless LAN, UMTS, LTE, and the like.

Furthermore, it should be noted that charging system 200 may be configured to perform wireless power transfer 221 using wireless power transmitter 211 at adapter 110 and corresponding wireless power receiver 231 at battery charger 130 . Wireless power transfer 221 typically uses inductors for power transfer. An example of inductive power transfer is the Qi standard.

It should be noted that for the case of n=1, the power converter 131 can be bypassed and/or removed, thereby further improving the power efficiency of the charging system 100 , 200 .

In this way, an integrated capacitive converter 131 may be used within the battery charger 130 to divide the input voltage 121 . A capacitive converter 131 can be used in conjunction with a regulation loop to dynamically control the input voltage 121 precisely to nx(V _bat +V _cdrop ). Alternatively or additionally, a capacitive converter 131 may be used to control a constant current to be supplied to the battery 140 . As long as the conversion ratio Vin/V _out of the converter 131 is an integer ratio, the capacitive converter 131 can obtain high efficiency. A typical implementation might be a 2:1 capacitive converter. No regulation may be used within the capacitive converter 131 , providing optimum efficiency for the capacitive converter 131 .

Another advantage of the capacitive converter 131 compared to inductor-based power converters is that capacitors have 10-1000 times higher energy density than inductors. Thus, despite the relatively low switching frequency of capacitive converter 131 , the energy storage elements used within capacitive converter 131 may also be ultra-small.

The charging systems 100 , 200 of FIGS. 1 and 2 utilize the AC/DC regulator 111 of the adapter 110 to regulate the system voltage 135 at the input of the charging unit 133 . To this end, feedback information indicative of the battery voltage V _bat 141 is provided to the adapter 110 using communication means. In particular, (closed loop) communication between the integrated circuit (IC) of the battery charger 103 within the electronic device and the IC of the regulator 111 within the external power supply 110 (ie within the adapter 110 ) may be provided.

By changing the conversion voltage, the loop can be "closed" at the AC/DC regulator 111 . It should be noted that higher voltages can also trigger higher currents, which results in increased voltage drops in the system 100 current feeding components. Therefore, the switching voltage at the input of the battery charger 130 may be increased by much less than the switching voltage indicated to the AC/DC regulator 111 . This current provided by the system 100 can be considered to be a closed loop in the case of a constant current configuration. However, the configured current may not always be supplied to the battery charger 130 at the maximum switching voltage.

Communication can be done through charging line 120 , where several techniques can be used such as VBUS signaling, D+/D- signaling, and/or communication through the Type C connector of line 120 . Alternatively or additionally, communication between the charger IC and the regulator IC within the wall plug adapter 110 may be accomplished by a wireless connection. A typical application is wireless charging. Communication with the power transmitter (ie, with the adapter 110 ) may be accomplished by load modulation and/or a wireless RF (radio frequency) link (Bluetooth, etc.), such as specified by the Rezence ^™ wireless charging standard.

The charging systems 100 , 200 of FIGS. 1 and 2 allow power conversion at high efficiency, even with conversion ratios V _in /V _out =2, 3, 4 . . . . Accordingly, the switching voltage 121 can be increased to enable the transfer of increased power with the same power line 120 (wires/connectors) within the battery charger 130 with high efficiency (eg, 95%) and low power consumption (eg, 50% reduction). In this way, the charging system 100, 200 enables energy efficient high voltage (HV) battery charging.

As mentioned above, the power converter 131 can be removed from the battery charger 130 with the conversion ratio V _in /V _out =1. Thus, the converted voltage 121 is provided directly to the charging unit 133 which may be configured to provide a regulated battery current for charging the battery 140 . In this case, the converted voltage 121 is set by the regulator 111 of the adapter 110 to the battery voltage 141 plus the voltage drop across the charging unit 133 . Power consumption and space requirements of the battery charger 120 can thus be further reduced.

FIG. 3 shows a flowchart of an example method 300 for charging the battery 140 of an electronic device. The battery 140 may include one or more battery cells arranged in series and/or parallel. For example, battery cells may be implemented using Lithium Ion (LiIon) technology. Electronic devices may include portable electronic devices such as smartphones or tablets. Method 300 may be implemented using adapter 110 and battery charger 130 , where adapter 110 and battery charger 130 are generally independent of each other.

Method 300 includes obtaining 301 power at a converted voltage 121 from a power source, such as from a mains supply, using adapter 110 . The converted voltage 121 is a DC voltage, where the power supply can provide AC power at an AC voltage. Method 300 also includes transmitting 302 power at converted voltage 121 from adapter 110 to battery charger 130 (eg, using a conductive charging cord or using wireless power transfer technology).

Additionally, method 300 includes charging 303 battery 140 of electronic device with battery current at battery voltage 141 , wherein the battery current is typically derived from power at converted voltage 121 using battery charger 130 . In particular, a regulated battery current (eg, regulated to a constant target battery current) may be provided for charging the battery 140 . To this end, the battery charger 130 may include a current regulator 133 . To this end, the battery charger 130 may include a current regulator 133 (also referred to herein as a charging unit).

Method 300 may also include transmitting feedback information 304 from battery charger 130 to adapter 110 indicative of battery voltage 141 . The switching voltage 121 can then be set by the adapter 110 based on this feedback information. Specifically, the conversion voltage 121 can be adjusted according to the feedback information. For example, conversion voltage 121 may be set (eg, adjusted) such that the buck conversion required to be performed at battery charger 130 to obtain battery voltage 141 is an integer n equal to or greater than one. Specifically, a deviation between the target reduction conversion ratio n and the actual reduction conversion ratio can be determined. Switching voltage 121 may be set (eg, adjusted) to reduce (eg, minimize) the magnitude of the deviation. Therefore, power efficiency for charging the battery can be improved.

As shown in Figure 3, the process of transmitting 304 feedback information and obtaining 301 the power at the converted voltage 121 based on the feedback information may be repeated in an iterative manner. In particular, a (continuous) control loop can be realized.

FIG. 4 shows an example system including a power adapter 110 , a battery charger 130 and a battery 140 to be charged. In the example shown, the power adapter 110 includes an AC/DC rectifier 410 and a DC/DC power converter 411 (together forming the AC/DC power converter 111), wherein the power converter 411 is configured to set (in particular regulate) The converted voltage 121 and/or the converted current provided via the power transfer device 120 . The power transfer device 120 may include a USB cable (especially a Type C USB cable (for example, for 3A switching current)). Furthermore, the power adapter 110 may include one or more control units 412 , 413 for controlling the power converter 411 .

The battery charger 130 includes a DC/DC power converter 131 (operated at a voltage step-down or current step-up conversion ratio n (eg, n=2)). The battery charger 130 also includes a control unit 134 that may be configured to determine a target battery current and/or a target battery voltage. In addition, the battery charger 130 may include a current monitor 431 configured to sense a battery current charging the battery 140 . In addition, the battery charger 130 may include a measurement unit 432 configured to sense information about the SOC of the battery 140 . Additionally, the battery charger 130 may include an overvoltage protection circuit 433 . The feedback information may be provided by the UTP (eg, D+ and/or D−) port of the USB line 120 .

It should be noted that the description and drawings merely illustrate the principles of the proposed method and system. Those skilled in the art will be able to implement various arrangements which, although not explicitly described or shown herein, embody the principles of the invention, which are all within the spirit and scope of the invention. Furthermore, all examples and embodiments outlined in this document are primarily intended for explanatory purposes only to help the reader understand the principles of the proposed methods and systems. Moreover, all statements herein presented of principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass equivalents thereof.

Claims (11)

1. Charging system (100, 200) for a battery (140) of an electronic device, wherein the charging system (100, 200) comprises,

an adapter (110) configured to obtain a converted current at a converted voltage (121) from a power source;

a battery charger (130) configured to charge a battery (140) of an electronic device with a battery current at a battery voltage (141) using the conversion current at the conversion voltage (121), wherein the battery charger has an input to receive the conversion current at the conversion voltage (121) and an output to provide the battery current at the battery voltage (141), wherein the battery charger comprises a capacitive power converter (131) applying a buck conversion with a buck conversion ratio n, where n is an integer greater than 1, or the battery charger comprises a capacitive power converter (131) applying a current boost conversion with a boost conversion ratio n, where n is an integer greater than 1;

a power transfer device configured to transfer the converted current at the converted voltage (121) to the battery charger (130); and

a communication device configured to repeatedly transmit feedback information indicative of the battery voltage (141) and/or the battery current from the battery charger (130) to the adapter (110);

wherein the adapter (110) is configured to set the switching voltage (121) and/or the switching current in dependence on the feedback information;

wherein the adapter (110) comprises a voltage regulator (111) configured to regulate the switching voltage (121) in accordance with the repeatedly transmitted feedback information such that the battery voltage (141) at the output of the battery charger (130) matches a target battery voltage and/or the adapter (110) comprises a current regulator (133) configured to regulate the switching current in accordance with the repeatedly transmitted feedback information such that the battery current provided by the battery charger (130) matches a target battery current for charging the battery (140).

2. The charging system (100, 200) of claim 1, wherein

The adapter (110) and the battery charger (130) are implemented within separate integrated circuits; and/or

The battery charger (130) is implemented as part of the electronic device.

3. A charging system (100, 200) as claimed in any preceding claim, wherein

The battery charger (130) comprises a control unit (134) configured to determine the target battery current and/or the target battery voltage to charge the battery (140); and

the feedback information indicates the target battery voltage and/or the target battery current.

4. The charging system (100, 200) of claim 1 or 2, wherein

The capacitive power converter (131) is configured to perform a down-conversion of the converted voltage (121) with a down-conversion ratio n; and/or

Performing a current step-up conversion of the converted current at a step-up conversion ratio n.

5. The charging system (100, 200) of claim 4, wherein

The capacitive power converter (131) exhibits a converter voltage drop; and

the adapter (110) is configured to set the conversion voltage (121) and/or the conversion current also in dependence of the converter voltage drop.

6. A charging system (100, 200) as claimed in claim 1 or 2, wherein the power transfer means comprises

The charging wire (120) is a USB charging wire; and/or

A wireless power transfer unit configured to generate an electromagnetic charging field by using the converted current at the converted voltage (121); and

a wireless power receiving unit configured to obtain power at the converted voltage (121) from the electromagnetic charging field.

7. The charging system (100, 200) of claim 1 or 2, wherein

The battery charger (130) comprises a transmission communication module (132) configured to transmit the feedback information over a communication channel; and

the adapter (110) comprises a receiving communication module (112) configured to receive the feedback information over the communication channel.

8. The charging system (100, 200) of claim 7, wherein the communication channel comprises

An electrical lead (122) of a charging wire (120) to conduct the converted current at the converted voltage (121) from the adapter (110) to the battery charger (130); and/or

A wireless power transmission unit; and/or

A radio frequency link.

9. The charging system (100, 200) of claim 1 or 2, wherein the adapter is configured to

Adjusting the switching voltage such that the switching current does not exceed a predetermined maximum switching current; or

The switching current is adjusted such that the switching voltage does not exceed a predetermined maximum switching voltage.

10. A battery charger (130) for charging a battery (140) of an electronic device, the battery charger (130) providing at its output a battery current at a battery voltage (141) for charging the battery (140); wherein the battery charger (130) comprises

A power receiving interface for receiving a converted current at a converted voltage (121) from the power adaptor (110) via the power transfer device (120);

a control unit (134) configured to determine a target battery current and/or a target battery voltage for charging the battery (140);

a capacitive power converter (131) configured to

Performing a step-down conversion of the converted voltage (121) at a step-down conversion ratio n to provide the battery voltage for charging the battery (140), wherein n is an integer greater than 1; and/or

Performing a current boost conversion of the conversion current at a boost conversion ratio n to provide the battery current for charging the battery (140), where n is an integer greater than 1; and

a transmission communication module (132) configured to repeatedly transmit feedback information indicative of the battery voltage and/or the battery current over a communication channel.

11. A method (300) of charging a battery (140) of an electronic device using an adapter (110) and a battery charger (130), wherein the adapter (110) and the battery charger (130) are independent of each other; the method (300) comprises

-obtaining (301) a switching current at a switching voltage (121) from a power supply using the adapter (110);

transferring (302) the converted current at the converted voltage (121) from the adapter (110) to an input of the battery charger (130), wherein the battery charger comprises a capacitive power converter;

charging (303) a battery (140) of the electronic device with a battery current at a battery voltage (141) provided at an output of the battery charger (130), wherein the battery current is derived from the switching current at the switching voltage (121) by using the battery charger (130), which performs a step-down conversion with a step-down conversion ratio of n, where n is an integer greater than 1, or a step-up conversion with a step-up conversion ratio of n, where n is an integer greater than 1; and

repeatedly transmitting (304) feedback information indicative of the battery voltage (141) and/or the battery current from the battery charger (130) to the adapter (110); wherein the switching voltage (121) and/or switching current is set by the adapter (110) in dependence on the feedback information;

-adjusting the converted voltage (121) in accordance with the repeatedly transmitted feedback information such that the battery voltage (141) matches a target battery voltage; and/or adjusting the switching current according to repeatedly transmitted feedback information to match the battery current with a target battery current for charging the battery (140).

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