DE102018129315A1 - Switching arrangement with adjustable capacity - Google Patents

Abstract

A switching arrangement (400) is described, which comprises a first subcircuit, with a first capacitance (401), which has a first capacitance value, and with a first switching element (402), which has a first one arranged parallel to the first switching element (402) Has diode (403). The switching arrangement (400) also comprises a control unit (216, 226) which is set up to determine a target capacitance value. Furthermore, the control unit (216, 226) is set up to open the first switching element (402) for an off time period during a sequence of periods of an alternating voltage, the off time period depending on the target capacitance value.

Description

The invention relates to a switching arrangement and a method for setting the capacitance value of a capacitance, in particular for an inductive charging system.

Vehicles with an electric drive typically have an electrical energy store in which electrical energy for operating an electrical drive machine of the vehicle can be stored. The vehicle's energy storage device can be charged with electrical energy from a power supply network. For this purpose, the energy store is coupled to the power supply network in order to transfer the electrical energy from the power supply network into the energy store of the vehicle. The coupling can be wired (via a charging cable) and / or wireless (using an inductive coupling between a charging station and the vehicle).

One approach to the automatic, wireless, inductive charging of the energy store of the vehicle is that electrical energy is transmitted to the energy store from the floor to the underbody of the vehicle via magnetic induction via the underbody clearance. This is exemplified in 1 shown. In particular shows 1 a vehicle 100 with an energy storage 103 for electrical energy. The vehicle 100 includes a secondary coil 121 in the vehicle underbody, with the secondary coil 121 via a rectifier with the energy store 103 connected is. The rectifier is part of a secondary electronics 123 . The secondary coil 121 and the secondary electronics 123 are typically via at least one (AC) line 122 electrically connected to each other and together form a so-called "Wireless Power Transfer" (WPT) vehicle unit 120 or secondary unit 120 .

The secondary coil 121 the secondary unit 120 can over a primary coil 111 be positioned with the primary coil 111 for example on the floor of a garage. The primary coil 111 is typically part of a so-called WPT floor unit 110 or primary unit 110 . The primary coil 111 is via an (AC) line 112 with primary electronics 113 and further connected to a power supply. The primary electronics 113 may include a frequency generator or inverter that has an AC (Alternating Current) current in the primary coil 111 the WPT floor unit 110 generated, whereby an alternating magnetic field (in particular a magnetic charging field) is generated. The alternating magnetic field can have an alternating field frequency from a predefined frequency range. The alternating field frequency of the alternating electromagnetic field can be in the range of 80-90 kHz (in particular at a nominal operating frequency of 85 kHz).

With sufficient magnetic coupling between the primary coil 111 the primary unit 110 and secondary coil 121 the secondary unit 120 (ie with a sufficiently high degree of coupling) via the underbody clearance 130 the magnetic alternating field creates a corresponding voltage and thus also a current in the secondary coil 121 induced. The induced current in the secondary coil 121 the secondary unit 120 is by the rectifier of the secondary electronics 123 rectified and in energy storage 103 saved. This means that electrical energy can be transferred wirelessly from a power supply to an energy store 103 of the vehicle 100 be transmitted. The charging process can be done in the vehicle 100 through a charging control unit of the secondary electronics 123 to be controlled. The charging control device can be set up for this purpose, for example wirelessly (for example via WLAN) with the primary unit 110 to communicate.

To bridge a relatively large underbody clearance 130 resonant inductive coupling systems are typically used. The primary unit 110 has a primary resonant circuit for this purpose, which is the primary coil 111 includes. Furthermore, the secondary unit points 120 a secondary resonant circuit on the secondary coil 121 includes. The resonance frequency of the resonant circuits typically depends on the transmission parameters of the inductive coupling system, which in turn depends on the spatial offset between the primary coil 111 and the secondary coil 121 depend. Furthermore, the voltage of the energy store to be charged can 103 have an influence on the transmission parameters. Consequently, the resonance frequencies of the resonant circuits of the primary unit 111 and the secondary unit 121 depending on the specific charging situation during a charging process, differ substantially from one another and / or from the alternating field frequency or the nominal operating frequency, as a result of which the efficiency and / or the transmission performance of a charging process can be impaired.

The primary and / or the secondary resonant circuit can each have an adjustable capacitance in order to match the resonance frequencies of the two resonant circuits to one another depending on the specific charging situation.

The present document deals with the technical problem of providing a flexibly adjustable capacity in a cost-effective manner, in particular for an inductive charging system.

The task is solved in each case by the independent claims. Advantageous embodiments are described, inter alia, in the dependent claims. It is pointed out that additional features of a claim dependent on an independent claim without the features of the independent claim or only in combination with a subset of the features of the independent claim can form a separate invention that is independent of the combination of all features of the independent claim can be made the subject of an independent claim, a divisional application or a late application. This applies in the same way to the technical teachings described in the description, which can form an invention that is independent of the features of the independent claims.

According to one aspect, a circuit arrangement or a circuit or a circuit or a device is described. The switching arrangement comprises a first subcircuit with a first capacitance (for example a first capacitor) which has a first capacitance value and (in particular exactly) with a first switching element (for example a first transistor) which has a first diode arranged in parallel with the first switching element . The first subcircuit can in particular be a series circuit with the first capacitance and the first switching element. The first switching element can e.g. (Exactly) a MOS (metal oxide semiconductor) transistor. The first diode can be a body diode of the MOS transistor. The series connection of the first capacitance and the first switching element can be arranged in parallel to a (relatively low-ohmic) current diversion path, which is set up to receive a current when the first switching element is open (and no current flow via the first diode is permitted).

In addition, the switching arrangement comprises a control unit (e.g. with a microprocessor), which is set up to determine a target capacitance value. In particular, a target capacitance value can be determined that is to be provided by the switching arrangement. The target capacity value is typically less than or equal to the first capacity value. The target capacity value can e.g. depend on a target resonance frequency of an electrical resonant circuit in which the switching arrangement is used as a capacitive unit. In other words, the switching arrangement can be used to set the resonance frequency of an electrical resonant circuit. Alternatively or additionally, the switching arrangement can be used for a flexible increase in the voltage.

The control unit is also set up to open the first switching element for an off time period during a sequence of periods of an AC voltage. The first switching element can be opened for each off-period in each period of the sequence of periods. The opening of the first switching element can take place during a half-wave of the AC voltage, in which the first diode can be or is at least temporarily in a blocking state. The AC voltage can be applied to the first subcircuit. The AC voltage can have a first (e.g. a positive) half-wave and a second (e.g. a negative) half-wave in each period. The first diode can be arranged such that the first diode is at least temporarily in the blocking state in the first half-wave and at least temporarily in a conductive state in the second half-wave. The control unit can then be set up to open the first switching element on each of the first half-waves of the sequence of periods for the off-period. In contrast, the first switching element can be closed for the rest of the time of a period (and thus allow current to flow through the first capacitance).

The off time can be set flexibly. In particular, the off period can be between zero and the period T a period can be set to adjust the capacitance value of the switching arrangement. In particular, the off time period can be set as a function of the target capacity value.

Closing the first switching element can cause the current to flow through the first capacitance (e.g. a first capacitor) and thereby cause a voltage drop across the first capacitance. The voltage drop can then lead to an offset of the voltage at the first switching element. In particular, the voltage (e.g. the drain-source voltage) at the first switching element in this case can correspond to the AC voltage which has a specific offset. The offset can have the consequence that the first diode of the first switching element is only temporarily in the conductive state during the second half-wave of the AC voltage. In particular, by increasing the voltage drop across the first capacitance, the period of the second half-wave in which the first diode is in the conductive state can be shortened. The voltage drop across the first capacitance can be increased by extending the off time period.

The first diode can be configured to prevent current flow in a first direction (and thus be in the blocking state) and in a second direction (and thus be in the conductive state). The control unit can be set up to determine a first time period in a period in which a current in the first Direction would flow through the first switching element if the first switching element were closed (but cannot flow if the first switching element is open since the first direction corresponds to the blocking direction of the first diode). The first time period can include the first half-wave of the AC voltage. The first time period can be determined for each period of the sequence of periods (for example based on current information relating to the current through the first switching element and / or based on voltage information relating to the voltage at the first switching element).

The first switching element can then be opened within the respective first period of the sequence of periods for the off period. In this way, the capacitance value of the switching arrangement can be set in a precise manner. The off-period can be varied between 0 and the period of a period.

The first subcircuit can be designed in such a way that the first period is extended when the off period is extended. Alternatively or in addition, the first subcircuit can be designed in such a way that the first time period is shortened if the off time period is shortened. The change in the temporal length of the first period can be brought about by the voltage drop across the first capacitance (and the consequent offset to the drain-source voltage of the first switching element), the amount of the voltage drop being able to be changed by the off time period . The first subcircuit can furthermore be designed such that the first period extends over at least half a period of a period (e.g. over the first half-wave of the alternating current) (e.g. if the off period is zero).

For example, the voltage drop across the first capacitance can correspond to the AC voltage if the off-time period is zero and the first switching element is thus continuously closed. In this case, the first capacitance contributes the entire first capacitance value to the capacitance value of the switching arrangement. In this case, the first period can correspond to half the period.

On the other hand, the off period can be the period. In this case, a voltage drop builds up at the first capacitance, which e.g. corresponds to the peak value of the AC voltage. This voltage drop acts as an offset to the drain-source voltage at the first switching element and thus extends the first time period (the first time period may possibly correspond to the entire period in this case).

For off periods between zero and the period, the length of the first period between half the period and the entire period can (continuously) be changed.

The control unit can be set up to detect a point in time within a period at which the closing of the first switching element does not cause a sudden change in a voltage across the first capacitance. For example, a point in time can be determined at which the current value of the AC voltage corresponds to the voltage drop across the first capacitance. The first switching element can then be reliably closed at the detected point in time.

The switching arrangement makes it possible to flexibly change the capacitance value in an efficient manner (e.g. by using a single MOS transistor). In particular, the first subcircuit can be designed such that a current flow through the first subcircuit in a conductive direction of the first diode cannot be prevented. Furthermore, the first subcircuit can be designed such that the first subcircuit has no further switching element arranged in series with the first switching element (in particular no further second MOS transistor arranged anti-serially with the MOS transistor of the first switching element). Nevertheless, the switching arrangement described enables a flexible setting of the capacitance value in a wide range of values (in particular between zero and the first capacitance value of the first capacitance).

The switching arrangement can have a second capacitance (as a bypass current path) which is arranged in parallel with the first subcircuit, the second capacitance having a second capacitance value. The control unit can be set up, the off time period between 0 and the entire period T to vary or adjust a period in order to vary or adjust the capacitance value of the switching arrangement between the second capacitance value and the sum of the first and second capacitance value. Thus, a capacitance value from a relatively wide range of values can be set efficiently.

As an alternative or in addition, the switching arrangement can comprise a second subcircuit (in particular a second series circuit), the second subcircuit comprising a second capacitance which has a second capacitance value and (in particular exactly) a second switching element (for example a second MOS transistor) which comprises one has a second diode arranged in parallel with the second switching element. The first subcircuit and the second subcircuit can be arranged parallel to one another be (and thus each form a bypass current path for the other subcircuit).

The first diode can be arranged such that the first diode blocks in each case on a first half-wave of the AC voltage, while the second diode can be arranged in such a way that the second diode blocks in each case on a second half-wave of the AC voltage. In other words, the first diode and the second diode can be designed to block a current flow in opposite directions. Consequently, the first and second switching elements can be opened in different half-waves or periods of a period in order to prevent the current flow through the respective capacitance.

In particular, the control unit can be set up to open the first switching element for a first off-period in a respective period of a period (e.g. in each period of a sequence of periods). Furthermore, the control unit can be set up to open the second switching element for a second off-time period in each case of a period of a period (e.g. in each period of a sequence of periods). The periods in which the first switching element is opened can be complementary with respect to the respective period to the periods in which the second switching element is opened.

The first off period and the second off period can be set depending on the target capacity value. In particular, the control unit can be set up, the first and the second off period each between 0 and the period T to vary or set a period in order to vary or set a capacitance value of the switching arrangement between zero and the sum of the first and second capacitance values. Thus, a capacitance value from a relatively wide range of values can be set efficiently.

By setting the respective off time period, a voltage drop can be brought about at the first or the second capacitance. The proportion of the capacitance value that a capacitance contributes to the capacitance value of the switching arrangement can decrease with an increasing voltage drop in the respective capacitance. The voltage drop typically increases with decreasing off-time. Thus, the capacitance value of the switching arrangement can be set in a precise manner by setting the respective off time period.

The control unit can be set up to close the first switching element when the current begins to flow through the first diode (e.g. after a voltage zero across the first switching element). As an alternative or in addition, the control unit can be set up to place an off period in which the first switching element (for the off period) is open at the end or at the beginning of a half-wave of the AC voltage. Furthermore, the control unit can be set up to determine current information in relation to the current through the first switching element and / or voltage information in relation to the voltage at the first switching element. The first switching element can then be opened in a precise manner depending on the current information and / or the voltage information. This enables particularly reliable operation of the switching arrangement.

According to a further aspect, an inductive charging system is described which comprises a primary unit which is set up to generate a magnetic charging field. Furthermore, the inductive charging system comprises a secondary unit, which is set up to generate a charging current for charging an electrical energy store on the basis of the magnetic charging field. The primary unit and / or the secondary unit can comprise a switching arrangement described in this document.

The primary unit and / or the secondary unit can each comprise an electrical resonant circuit, wherein the electrical resonant circuit of the primary and / or secondary unit can each comprise a switching arrangement described in this document in order to provide a capacitance with an adjustable capacitance value (and thereby thereby the resonance frequency of the respective one To change the resonant circuit).

Furthermore, a primary unit and a secondary unit for an inductive charging system are described in this document, each comprising at least one of the switching arrangements described in this document.

The secondary unit can include a rectifier and a voltage boost circuit for boosting the output voltage of the rectifier for charging an energy store. The voltage boost circuit may include a circuit arrangement described in this document to change the amount of boost in the rectifier output voltage. In this way, the quality and speed of charging processes can be increased in an efficient manner.

According to a further aspect, a rectifier circuit is described (for example as part of a secondary unit of an inductive charging system). The rectifier circuit comprises a bridge rectifier that is set up Generate a rectified current and / or a rectified output voltage on the basis of an AC voltage present at input bridge points at the output bridge points of the bridge rectifier.

The rectifier circuit further comprises a first capacitor (directly) coupled to a first output junction of the two output jumper points of the bridge rectifier and a second capacitor (directly) to a second output junction of the two output jumper points of the bridge rectifier is coupled. Furthermore, the rectifier circuit comprises (in particular exactly) a first switching element (e.g. (exactly) a first MOS transistor) which has a first diode arranged in parallel with the first switching element. The first switching element can be (directly) coupled to a first input bridge point of the two input bridge points.

The first switching element can be configured to switch the first capacitor between the first input junction point and the first output junction point (so that a current flowing between the first input junction point and the first output junction point) only through the first switching element and the first Capacitor flows) or to decouple from the first input bridge point. Furthermore, the first switching element can be set up to switch the second capacitor between the first input bridge point and the second output bridge point (so that a current flowing between the first input bridge point and the second output bridge point only via the first switching element and the second capacitor flows) or to decouple from the first input bridge point.

In addition, the rectifier circuit comprises a control unit which is set up to determine a target voltage value of the output voltage between the output junction points (e.g. as a charging voltage for an energy store). Furthermore, the control unit can be set up during a sequence of periods of the AC voltage, the first switching element in each case at a half-wave of the AC voltage or in a period of a period in which or in which the first diode is in a blocking state, for one Open time period, the time period depending on the target voltage value. In other words, by setting the off period, the target voltage value can be set. The value of the output voltage of a rectifier circuit can thus be set in an efficient manner (in particular by using a single transistor).

The rectifier circuit may include a third capacitor (directly) coupled to the first output bridge point of the bridge rectifier and a fourth capacitor (directly) coupled to the second output bridge point of the bridge rectifier. Furthermore, the rectifier circuit can comprise a second switching element (e.g. a second MOS transistor) which has a second diode (e.g. a body diode) arranged in parallel with the second switching element.

In other words, the rectifier circuit can comprise a plurality of modules of pairs of capacitors arranged one behind the other, which are arranged (directly) between the first output junction point and the second output junction point and which, via the center point between the two capacitors, each have a (precise) input Switching element (directly) can be coupled to or decoupled from the first input junction point.

As already explained above, the AC voltage typically comprises a first half-wave and a second half-wave in one period. The first diode (of the first switching element) can be arranged in such a way that the first diode blocks on a first half-wave of the AC voltage. Furthermore, the second diode (of the second switching element) can be arranged such that the second diode blocks on a second half-wave of the AC voltage. In other words, the first diode and the second diode can be blocking in opposite directions.

Analogously to the first switching element, the second switching element can be set up to switch the third capacitor (directly) between the first input junction point and the first output junction point (if the second switching element is closed and / or the second diode is conductive) or to decouple from the first input bridge point (when the second switching element is open and the second diode is blocking). Furthermore, the second switching element can be set up to switch the fourth capacitor (directly) between the first input junction point and the second output junction point (when the second switching element is closed and / or the second diode is conductive) or from the first Decouple the input bridge point (when the second switching element is open and the second diode is blocking).

The control unit can be set up to switch the first switching element for a first off-time period in each case at a first half-wave of the AC voltage or in a first period of a period to open (typically repeated for each period of a sequence of periods of AC voltage). Furthermore, the control unit can be set up to open the second switching element for a second off-period in a second half-wave or in a second period of a period (typically repeated for each period of a sequence of periods of the AC voltage). The first off time period and the second off time period can be set as a function of the target voltage value. In particular, the first and second off time periods can be set such that the output voltage between the output junction points has the target voltage value.

By using several modules of pairs of capacitors arranged one behind the other, the current load for the individual capacitors and switching elements can be reduced. Furthermore, the ripple of the output voltage can be reduced. In addition, the capacitance value of the individual capacitors can be reduced.

According to a further aspect, a method for setting a capacitance value of a switching arrangement is described, the switching arrangement comprising a first subcircuit with a first capacitance, which has a first capacitance value, and with a first switching element, which has a first diode arranged in parallel with the first switching element, includes. The method comprises determining a target capacitance value of the switching arrangement. In addition, during a sequence of periods of an alternating voltage, the method comprises repeatedly opening the first switching element (in each period) in a period in which the first diode is in a blocking state for an off period, the off period depends on the target capacity value.

According to a further aspect, a road motor vehicle (in particular a passenger car or a truck or a bus or a motorcycle) is described which comprises the switching arrangement described in this document.

According to a further aspect, a software (SW) program is described. The SW program can be set up to be executed on a processor (e.g. on a control device of a vehicle) and thereby to carry out the method described in this document.

According to a further aspect, a storage medium is described. The storage medium can comprise a software program which is set up to be executed on a processor and thereby to carry out the method described in this document.

It should be noted that the methods, devices and systems described in this document can be used both alone and in combination with other methods, devices and systems described in this document. Furthermore, any aspect of the methods, devices and systems described in this document can be combined with one another in a variety of ways. In particular, the features of the claims can be combined with one another in a variety of ways.

• 1 beispielhafte Komponenten eines induktiven Ladesystems zum Laden des Energiespeichers eines Fahrzeugs;
• 2 ein beispielhaftes resonantes induktives Ladesystem;
• 3 eine beispielhafte Gleichrichterschaltung;
• 4a eine beispielhafte Schaltanordnung für eine einstellbare Kapazität;
• 4b und 4c beispielhafte Ströme und Spannungen an einer einstellbaren Kapazität;
• 5a eine weitere beispielhafte Schaltanordnung für eine einstellbare Kapazität;
• 5b beispielhafte Ströme und Spannungen an einer einstellbaren Kapazität;
• 6a, 6b beispielhafte Schaltungen zur Anhebung einer Spannung; und
• 7 ein Ablaufdiagramm eines beispielhaften Verfahrens zur Einstellung des Kapazitätswertes einer Schaltanordnung mit einer einstellbaren Kapazität.

The invention is described in more detail below with the aid of exemplary embodiments. Show

• 1 exemplary components of an inductive charging system for charging the energy store of a vehicle;
• 2nd an exemplary resonant inductive charging system;
• 3rd an exemplary rectifier circuit;
• 4a an exemplary switching arrangement for an adjustable capacitance;
• 4b and 4c exemplary currents and voltages on an adjustable capacitance;
• 5a another exemplary switching arrangement for an adjustable capacitance;
• 5b exemplary currents and voltages on an adjustable capacitance;
• 6a , 6b exemplary voltage boost circuits; and
• 7 a flow chart of an exemplary method for setting the capacitance value of a switching arrangement with an adjustable capacitance.

As stated at the beginning, the present document deals with the provision of a cost-efficient capacity with a flexibly adjustable capacity value. Such an adjustable capacity can e.g. can be used as part of an inductive charging system.

ergibt. Die Wechselfeld-Frequenz f₀ des Wechselstroms und des durch die Primärspule 111 generierten Magnetfelds 230 ist bevorzugt nahe an der Resonanzfrequenz f_R, um einen möglichst hohen Primärstrom durch die Primärspule 111 zu erzeugen (durch eine Resonanz). Ein hoher Primärstrom ist typischerweise erforderlich, da der Kopplungsfaktor k zwischen Primärspule 111 und Sekundärspule 121 aufgrund des relativ großen Luftspaltes 130 relativ klein ist, z.B. k~0.1. Der Primärschwingkreis 210 kann weiter ein oder mehrere Sensoren 215 (z.B. einen Temperatursensor) zur Überwachung des Primärschwingkreises 210 aufweisen. Des Weiteren kann die Primärelektronik 113 eine Steuereinheit 216 zur Anpassung der Wechselfeld-Frequenz und/oder zur Steuerung des Wechselrichters 213 aufweisen. 2nd shows a circuit diagram of an exemplary inductive charging system 200 with a WPT floor unit 110 (as an example of a primary unit) and a WPT vehicle unit 120 (as an example of a secondary unit). The primary unit 110 includes as part of primary electronics 113 a power factor correction filter 217 and an inverter 213 , with the inverter 213 is set up, an alternating current from a direct current (for example at a direct voltage of approx. 400V, 500V or more) to generate with a charging field or alternating field frequency. The primary unit also includes 110 the primary coil 111 and a primary capacitor 212 . In addition, in 2nd an example of a filter 214 the primary electronics 113 shown. The primary unit 110 thus comprises a parallel and / or a serial resonant circuit 210 (also referred to here as the primary resonant circuit), whose resonance frequency f _{R is} derived from the total capacitance or the effective capacitance C (in particular the capacitance of the primary capacitor 212 ) and the total inductance or the effective inductance L (in particular the inductance of the primary coil 111 ) approximated as $f_R=\frac{1}{\mathrm{2nd}\pi \sqrt{L\mathrm{C.}}}$

results. The alternating field frequency f ₀ of AC and through the primary coil 111 generated magnetic field 230 is preferably close to the resonance frequency f _R in order to have the highest possible primary current through the primary coil 111 to generate (through a resonance). A high primary current is typically required because of the coupling factor k between primary coil 111 and secondary coil 121 due to the relatively large air gap 130 is relatively small, for example k ~ 0.1. The primary resonant circuit 210 can continue one or more sensors 215 (eg a temperature sensor) for monitoring the primary resonant circuit 210 exhibit. Furthermore, the primary electronics 113 a control unit 216 to adjust the alternating field frequency and / or to control the inverter 213 exhibit.

The secondary unit comprises in an analogous manner 120 a (parallel and / or serial) resonant circuit 220 (also referred to here as a secondary resonant circuit) that comes from the secondary coil 121 and a secondary capacitor 222 is formed. The resonance frequency of this secondary resonant circuit 220 is preferred to the resonance frequency of the primary resonant circuit 210 the primary unit 110 adjusted to achieve the best possible energy transfer. The secondary resonant circuit 220 can continue one or more sensors 225 (eg a temperature sensor) to monitor the secondary resonant circuit 220 exhibit. In addition, in 2nd a compensation network (e.g. with a filter capacitor) 224 , a rectifier 223 and a control unit 226 of secondary electronics 123 shown.

The inductive charging system 200 has capacitors or capacitors at different points, which can be made adjustable, if necessary, around the charging system 200 adapt to different charging situations. For example, the primary resonant circuit, the secondary resonant circuit, the filter 214 and / or the rectifier 223 have adjustable capacities.

3rd shows an exemplary rectifier 223 with a voltage doubler switch. The rectifier 223 is in the in 3rd shown example as a bridge rectifier 301 with two entrance bridging points 311 , 312 and two exit bridging points 321 , 322 educated. At the entrance bridge points 311 , 312 lie the secondary voltage 362 with the secondary current 352 at, and at the exit bridge points 321 , 322 become the charging current 353 with the charging voltage 363 provided.

The voltage doubler circuit comprises a first capacitor 341 that is between a first exit bridge point 321 and a first entrance bridge point 311 is arranged, and a second capacitor 342 that is between the first entrance bridge point 311 and a second exit bridge point 322 is arranged. The voltage doubling occurs when the in 3rd switching element shown 302 the connection point between the first capacitor 341 and the second capacitor 342 with the first entrance bridge point 311 couples. On the other hand, the voltage doubling can be deactivated in that the connection point between the capacitors 341 , 342 from the first entrance bridge point 311 is decoupled.

The secondary unit 120 includes a control unit 226 that is set up the switching element 302 to control the voltage increase through the capacitors 341 , 342 to activate or deactivate. In particular, the control unit 370 be set up, information relating to the state of charge of the energy store 103 to determine. For this purpose, for example, the energy store 103 from the secondary unit 120 be decoupled to the rest voltage of the energy storage 103 to determine and / or to measure the voltage during the charging process. The quiescent voltage and / or the charging voltage of the energy store 103 typically show the state of charge (SOC) of the energy storage device 103 at. The switching element 302 can then be controlled depending on the open circuit voltage. Alternatively or in addition, the charging current 353 or the secondary current 352 and / or the charging voltage 363 or the secondary voltage 362 be determined. The switching element 302 can then depend on the charging current 353 or the secondary current 352 and / or the charging voltage 363 or the secondary voltage 362 can be controlled. At least one of the in 3rd shown capacities 341 , 342 can (in combination with the switching element 302 ) can be designed as an adjustable capacitance to enable a flexible voltage increase.

4a shows an exemplary first capacitance 401 with a first capacity value C _s , in the Row with a switching element 402 is arranged, the switching element 402 a parallel diode 403 (eg a Bode diode) that causes the switching element 402 can only be blocked in one direction. The series connection from the first capacitance 401 and the switching element 402 is parallel to a second capacitance 407 with a second capacity value C _p arranged. Furthermore, the in 4a Switching arrangement shown an AC voltage source 404 and an inductor 405 . Furthermore, the switching arrangement comprises a measuring unit 406 , which is set up, measured values in relation to the current through the switching element 402 and / or in relation to the voltage on the switching element 402 capture.

As in 4b is represented by the voltage source 404 a (sinusoidal) AC voltage U at the series connection or at the second capacitance 407 causes. The switching element 402 is operated such that the switching element 402 in a period with the period duration T is opened for the off period with the off period toff to allow a current to flow through the switching element 402 to prevent. As stated above, the switching element 402 a parallel diode 403 on, which blocks in a first (eg positive) half-wave and which is conductive in a second (eg negative) half-wave of a period. The off period with the off period toff is then in the first half-wave, and preferably at the end of the first half-wave.

The control unit 226 can be set up the switching element 402 to be controlled such that the switching element 402 is open for the off time period toff (for example as a function of the measured current I through the switching element 402 and / or depending on the measured voltage U _DS on the switching element 402 ). In particular, the switching element 402 be closed or remain closed at the beginning of a first half-wave (see 4c , right side) when there is a reversal of the current I through the switching element 402 he follows. Furthermore, the switching element 402 after an on-period ton be opened to the current I through the switching element 402 to prevent. In addition, the switching element 402 be closed at time T / 2 or remain closed to the voltage drop across the diode 403 (please refer 4c , left side).

4b shows the course of the current I through the switching element 402 in a period with the period duration T . Furthermore shows 4b the course of the tension U _DS (ie the drain-source voltage) across the switching element 402 during a period. The off time period toff can be between 0 and T to be changed. The off time toff can be used to close the switching element 402 also become larger than T / 2 (around the switching element 402 close for more than T / 2), since the first capacitance increases with increasing off-time toff 401 with the first capacity value C _S has an increasing DC voltage component and thus the positive half-wave of the drain-source voltage U _DS over the switching element 402 may take longer than T / 2. With the switching element permanently open 402 is the tension U _DS always positive. In this case, there is no current flow through the first capacitance 401 instead of. As a result, the capacity of the in 4a Switching arrangement shown between the second capacitance value C _p (for toff = T ) and the sum of the capacitance values C _p + C _s (for toff = 0). It can thus be used efficiently (when using only a single switching element 402 , in particular only a single MOSFET (metal oxide semiconductor field effect transistor)) can be provided with an adjustable capacitance.

5a shows a switching arrangement with a first capacitance 401 with the first capacitance value C and a second capacitance 407 with the second capacity value C2 . Both capacities 401 , 407 are in series with each (exactly) one switching element 402 , 502 arranged, the diode 403 of the first switching element 402 one to the diode 503 of the second switching element 502 has opposite orientation. The AC voltage is applied to both series connections U at.

5b shows the current Is through the first capacitance 401 and the voltage Us at the first capacitance 401 (above), as well as the current I _S2 through the second capacity 407 and the tension U _S2 at the second capacity 407 (below). The first switching element 402 can be opened in the first (eg positive) half-wave, and the second switching element 407 can be opened in the second (eg negative) half-wave of a period (each for an individually selectable off-period toff). The capacitance value of the switching arrangement can thus be varied or set between 0 (both off periods t _off = T) and C + C2 (both off periods t _off = 0). A relatively extensive variation of the capacitance value is thus made possible, the required current capability of the switching elements 402 , 502 is reduced (in particular halved) and the resulting current has a relatively low harmonic component (due to the distribution over two capacities 401 , 407 ).

The in the 4a and 5a switching arrangements shown 400 can in a charging system 200 be used, for example, to set capacities 212 , 222 To be provided in the primary and / or in the secondary resonant circuit. Alternatively or in addition, an adjustable capacity can be set in a rectifier 223 be used to increase the voltage (see 6a) .

As related to 3rd can set out by closing the switching element 302 the voltage U _DC 363 be doubled since both the first capacity 341 (in the first, positive, half wave) as well as the second capacitance 342 (in the second, negative, half-wave) according to the peak value of the AC voltage 362 to be charged. On the other hand, by opening the switching element 302 causes the entire series connection from the two capacitors 341 , 342 according to the peak value of the AC voltage 362 is charged (and thus there is no voltage doubling, or a voltage increase in the range between 1 and 2).

This in 6a shown (single or sole) switching element 302 has a parallel diode 403 on that causes the switching element 302 is bridged at least temporarily in the second (negative) half-wave, so that the second capacitance 342 is charged. On the other hand, the switching element 302 are opened at least temporarily in the first (positive) half-wave (for the off-duration toff). As a result, the first capacity is only partially charged 341 up to a partial tension. The partial voltage can be between 0V (at toff = T) and the peak value of the AC voltage 362 (at toff = 0) can be varied or set. Consequently, the voltage boost can be between one factor 1 and a factor 2nd can be varied or adjusted.

6b shows the use of a (sole) first switching element 302 with a first diode 403 and a (sole) second switching element 502 with a second diode 503 , as well as first and second capacities 341 , 342 and third and fourth capacities 621 , 642 . The first diode 403 and the second diode 503 are aligned opposite to each other. The capacity values of the capacities 341 , 342 , 641 , 642 can each be half the size of the capacity values of the capacities 341 , 342 out 6a . The first switching element 302 can be opened at least temporarily in the first half-wave and the second switching element 502 can be opened at least temporarily in the second half-wave. By using such a switching arrangement, the ripple (or the harmonic component) can be reduced in the rectification and / or voltage increase.

7 shows a flow diagram of an exemplary method 700 for setting a capacitance value of a switching arrangement 400 . The switching arrangement includes 400 at least a first subcircuit with a first capacitance 401 , which has a first capacitance value, and with a first switching element 402 which is a parallel to the first switching element 402 arranged first diode 403 having. The first capacity 401 and the first switching element 402 can be arranged in series with one another so that the first subcircuit forms a series circuit. The first switching element 402 can be a MOS transistor with an internal body diode 403 be. The first subcircuit can be exactly one switching element 402 (eg exactly one MOS transistor).

The procedure 700 includes identifying 701 a target capacitance value of the switching arrangement 400 . The target capacity value can range up to the first capacity value of the first capacity 401 lie. The target capacitance value can be determined, for example, as a function of a target resonant frequency of an electrical resonant circuit.

The procedure also includes 700 during a sequence of periods of an AC voltage, the repeated opening 702 of the first switching element 402 in a period of the respective period in which the first diode 403 is in a locked state for an off period. In other words, the first switching element 402 can be opened repeatedly in a first period of the individual periods of the sequence of periods, each for an off-period. The first time period can include the first half-wave of the AC voltage. Furthermore, the first period typically extends with a decreasing value of the off period (due to an increasing voltage drop across the first capacitance) 401 ).

The off period may depend on the target capacity value. In particular, the off time period can be set to a specific target capacitance value of the switching arrangement 400 to effect. In this way, a flexibly adjustable capacitance can be provided efficiently (by using a single switching element, for example a single MOS transistor).

The present invention is not restricted to the exemplary embodiments shown. In particular, it should be noted that the description and the figures are only intended to illustrate the principle of the proposed methods, devices and systems.

Claims (18)

Switching arrangement (400), comprising - a first subcircuit with a first capacitance (401), which has a first capacitance value, and with a first switching element (402), which has a first diode (403) arranged in parallel with the first switching element (402) ) having; and - a control unit (216, 226), which is set up - to determine a target capacity value; and - during a sequence of periods of an alternating voltage, the first switching element (402) in each case open for an off-period; where the off time period depends on the target capacity value. Switching arrangement (400) according to Claim 1 , wherein - the first diode (403) is set up to prevent current flow in a first direction and to enable it in a second direction; and - the control unit (216, 226) is set up - to determine a first time period in a period in which a current would flow in the first direction through the first switching element (402) if the first switching element (402) were closed; and - open the first switching element (402) within the first period for the off period. Switching arrangement (400) according to Claim 2 , wherein - the first subcircuit is designed such that the first period is extended when the off period is extended; and / or - the first subcircuit is designed such that the first time period is shortened if the off time period is shortened; and / or - the first subcircuit is designed such that the first period extends over at least half of a period of a period. Switching arrangement (400) according to one of the Claims 2 to 3rd , wherein the control unit (216, 226) is set up to - detect a point in time within a period at which the closing of the first switching element (402) does not cause a sudden change in a voltage across the first capacitance (401); and - close the first switching element (402) at the detected time. Switching arrangement (400) according to one of the preceding claims, wherein - a period has a period duration; and - The control unit (216, 226) is set up to change the off period between 0 and the period in order to change a capacitance value of the switching arrangement (400). Switching arrangement (400) according to one of the preceding claims, wherein - The first subcircuit is designed such that a current flow through the first subcircuit in a conductive direction of the first diode (403) cannot be prevented; and or - The first subcircuit has no further switching element arranged in series with the first switching element (402). Switching arrangement (400) according to one of the preceding claims, wherein - The switching arrangement (400) has a second capacitance (407) which is arranged in parallel with the first subcircuit; - The second capacitance (407) has a second capacitance value; and - The control unit (216, 226) is set up to vary the off time period between 0 and a period in order to vary a capacitance value of the switching arrangement (400) between the second capacitance value and the sum of the first and second capacitance value. Switching arrangement (400) according to one of the preceding claims, wherein - The switching arrangement (400) has a second subcircuit with a second capacitance (407), which has a second capacitance value, and with a second switching element (502), which has a second diode (503) arranged in parallel with the second switching element (502); - The first sub-circuit and the second sub-circuit are arranged in parallel to each other; - The first diode (403) and the second diode (503) are arranged such that a current flow in the opposite direction is blocked by the first diode (403) and by the second diode (503); and - The control unit (216, 226) is set up, - open the first switching element (402) for a first off time period; and - open the second switching element (502) for a second off time period; wherein the first off period and the second off period depend on the target capacity value. Switching arrangement (400) according to Claim 8 , wherein the control unit (216, 226) is configured to vary the first and the second off duration between 0 and a period in order to vary a capacitance value of the switching arrangement (400) between zero and the sum of the first and second capacitance values. Switching arrangement (400) according to one of the preceding claims, wherein the control unit (216, 226) is set up, - close the first switching element (402) when a current begins to flow through the first diode (403); and or - to put an off period in which the first switching element (402) is open at one end or at the beginning of a half-wave of the AC voltage; and or - Determine current information relating to a current through the first switching element (402) and / or voltage information relating to a voltage at the first switching element (402), and the first switching element (402) as a function of the current information and / or the voltage information to open. An inductive charging system (200) comprising - a primary unit (110) configured to generate a magnetic charging field (230); - a secondary unit (120) which is set up to generate a charging current (353) for charging an electrical energy store (103) based on the magnetic charging field (230); wherein the primary unit (110) and / or the secondary unit (120) comprises a switching arrangement (400) according to one of the preceding claims. Inductive charging system (200) according to Claim 11 , wherein - the primary unit (110) and / or the secondary unit (120) each comprise an electrical resonant circuit; and - the electrical resonant circuit is a switching arrangement (400) according to one of the Claims 1 to 10th to provide a capacity with an adjustable capacity value. Inductive charging system (200) according to one of the Claims 11 to 12 , wherein - the secondary unit (120) comprises a rectifier (301) and a voltage boost circuit (302, 341, 342) for raising an output voltage of the rectifier (301) for charging the energy store (103); and - the voltage boost circuit (302, 341, 342) a switching arrangement (400) according to one of the Claims 1 to 10th to change a degree of raising the output voltage of the rectifier (301). Primary unit (110) for an inductive charging system (200), wherein - the primary unit (110) is set up to generate a magnetic charging field (230) for inductive charging; and - the primary unit (110) a switching arrangement (400) according to one of the Claims 1 to 10th includes. Secondary unit (120) for an inductive charging system (200), the secondary unit (120) being set up to generate a charging current (353) for charging an electrical energy store (103) based on a magnetic charging field (230); and - the secondary unit (120) has a switching arrangement (400) according to one of the Claims 1 to 10th includes. Rectifier circuit (223) which comprises - A bridge rectifier (301), which is set up to generate a rectified current (353) based on an AC voltage present at input bridge points (311, 312) at output bridge points (321, 322) of the bridge rectifier (301); - A first capacitor (341), which is coupled to a first output bridge point (321) of the bridge rectifier (301), and a second capacitor (342), which is coupled to a second output bridge point (322) of the bridge rectifier (301) is; a first switching element (302) which has a first diode (403) arranged in parallel with the first switching element (302) and which is set up, - to switch the first capacitor (341) between a first input bridge point (311) and the first output bridge point (321) or to decouple it from the first input bridge point (311); and - to switch the second capacitor (342) between the first input bridge point (311) and the second output bridge point (322) or to decouple it from the first input bridge point (311); and - a control unit (216, 226) which is set up - determine a target voltage value of an output voltage between the output bridging points (321, 322); and - During a sequence of periods of the alternating voltage, the first switching element (302) is opened for a period of the alternating voltage for an off time period; where the off time period depends on the target voltage value. Rectifier circuit (223) according to Claim 16 , wherein - the rectifier circuit (223) comprises a third capacitor (641) which is coupled to the first output bridge point (321) of the bridge rectifier (301) and comprises a fourth capacitor (342) which is connected to the second output bridge point (322) of the bridge rectifier (301) is coupled; - The rectifier circuit (223) comprises a second switching element (502) which has a second diode (503) arranged in parallel with the second switching element (502); - The first diode (403) and the second diode (503) are arranged such that the first diode (403) and the second diode (503) block currents in opposite directions to each other; - The second switching element (502) is set up - To switch the third capacitor (641) between the first input bridge point (311) and the first output bridge point (321) or to decouple it from the first input bridge point (311) ; and - to switch the fourth capacitor (642) between the first input bridge point (311) and the second output bridge point (322) or to decouple it from the first input bridge point (311); and - the control unit (216, 226) is set up to - open the first switching element (302) for a first off-period in a period; and - open the second switching element (502) for a second off period in a period; being the first Off time and the second off time depend on the target voltage value. Method (700) for setting a capacitance value of a switching arrangement (400), the switching arrangement (400) comprising a first subcircuit with a first capacitance (401) that has a first capacitance value and with a first switching element (402) that is connected in parallel comprises the first switching element (402) arranged first diode (403); the method comprising (700) - determining (701) a target capacitance value of the switching arrangement (400); and - During a sequence of periods of an AC voltage, repeated opening (702) of the first switching element (402) each for an off time period; where the off time period depends on the target capacity value.

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