KR20150089659A - Power Supply and Its Charging Voltage Compensation Method - Google Patents

Abstract

The present invention relates to a power supply device provided in a vehicle head unit, wherein an output connector of a vehicle head unit and an input connector of an external device are electrically connected through a cable, and the power supply device A power supply unit for outputting the power supply voltage to an output connector of the head unit and a voltage detecting unit for detecting a voltage appearing at an input connector of the external apparatus to compensate for a voltage drop of a voltage appearing at an output connector of the vehicle head unit by the cable do.

Description

[0001] DESCRIPTION [0002] Power supply and its charging voltage compensation method [

The present invention relates to an apparatus and method for supplying power to an external device by connecting a vehicle head unit and an external device, and more particularly to a device for supplying a charging voltage to an external device connected through a universal serial bus (USB) It is about the method.

The universal serial bus (USB) port of the vehicle's standard AVN (Audio Video Navigation) system electrically connects the vehicle head unit and the external device with the vehicle USB cable and the user's USB cable.

An external device electrically connected to the vehicle head unit receives the USB operation power supply (VBUS? 5 ± 0.25V) from the vehicle head unit to perform operation and charging.

1 is a view showing an embodiment in which a power source unit of a vehicle head unit according to the related art is connected to an external device. Conventionally, when designing a USB operation power source for a vehicle power source, 5V is supplied from a head unit, and a fast charging and a general charging function of an external device are implemented through a USB cable for a vehicle.

Table 1 is a table listing USB operation power and current values for operation and charging of external devices.

USB VBUS MIN
4.75V
USB VBUS MAX
5.25V
USB 2.0 Maximum Allowable Current
500mA
USB 3.0 Maximum allowable current
900mA
USB VBUS Fast Charge Max Current
2100mA

The voltage of the DC-DC converter output voltage (A point voltage) shown in FIG. 1 can be calculated as below.

, (R1=100KΩ,R2=100KΩ)DC-DC converter part output voltage =

, (R1 = 100KΩ, R2 = 100KΩ)

= (1 + 100K? / 100K?) 2.5V = 5V

(Ignoring the effect of the process control block pattern from the DC-DC converter output to the head unit USB connector)

When IPAD is charged at high speed with an external device, current of 2100 mA flows in the USB cable of the vehicle as shown in Table 1. Accordingly, the voltage of the actual USB power supply port (point B) from the previously calculated DC-DC converter output voltage (5V) can be calculated as follows.

B point voltage = A point voltage - (cable resistance) * Maximum charge current

          = 5 - (0.0842 * 2) * 2.1 = 4.6472 V

(At this time, the voltage at the B point: the actual USB power supply port voltage, the A point voltage: the output voltage of the DC-DC converter)

As can be seen from the calculation process described above, the USB minimum voltage specification of 4.75 V can not be satisfied due to the voltage drop of the cable due to the maximum charging current (2.1 A) in the case of fast charging.

When designing the USB operation power supply of the vehicle head unit in consideration of the voltage drop problem at the time of high-speed charging, it is possible to output 5.2V which is close to the maximum value of the USB operation power supply specification.

However, when the high-speed charging is performed, the minimum specification (4.72V) of the USB operating voltage can be satisfied at the time of fast charging of the external device when the corresponding design is taken considering the voltage drop problem. However, Which may exceed 5.25V.

For example, since the operating current of the USB device is 5 mA, the voltage at the B point is calculated to be 5.2 V. As shown in Table 1, the USB operation maximum specification is 5.25 V, and therefore, a margin of about 50 mV is generated relative to the maximum specification. In this case, there is a possibility that the maximum specification is dissatisfied when the resistance deviation and the output deviation of the DC-DC converter portion are considered due to the margin shortage.

If the maximum specification of the operating voltage is exceeded, if the USB device (for example, a USB memory stick) is connected and operated, it may cause a problem in the multimedia function implemented through the USB connection in the AVN system.

That is, conventionally, there is a problem that the operating power can not be satisfied due to the impedance of the cable and the voltage drop of the cable caused by the high-speed charging current during high-speed charging through the vehicle head unit.

When AVN system is developed, the output voltage value of the head unit of the vehicle is continuously tuned according to the type and length of the cable and the deviation of the system when the operation power is supplied by the corresponding design that can compensate the voltage drop at the high- Have problems.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an apparatus and method for actively controlling a voltage drop that may occur in a system for supporting high-speed charging through a USB cable for a vehicle.

It is another object of the present invention to provide a power supply device for detecting a voltage appearing at an input connector of an external device and compensating for a voltage dropped by a USB cable for a vehicle, and a charging voltage compensation method thereof.

The objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

There is provided a power supply device for supplying a power supply voltage to an external device through a cable, the power supply device electrically connecting an output connector of a vehicle head unit and an input connector of an external device, according to an aspect of the present invention, A voltage compensating unit for detecting a voltage appearing at an input connector of the external device and compensating for a voltage drop of a voltage appearing at an output connector of the vehicle head unit by the cable, .

The voltage compensating unit compares a voltage appearing at an input connector of the external device with a reference voltage to output a compensation signal when a voltage appearing at an input connector of the external device is less than the reference voltage, And the switching unit switches the voltage compensating unit and the power supply unit according to the switching signal.

The voltage compensating unit includes a comparator for comparing a voltage appearing at an input connector of the external device with a reference voltage, a switching unit for switching according to a comparison result of the comparing unit, a first resistor connected in series with the switching unit, A second resistor connected in parallel with the first resistor, and a third resistor connected between the output of the power source and the second resistor.

The power supply unit includes a parallel terminal formed by parallel connection of the first and second resistors, a feedback terminal fed back with the power supply voltage divided by the third resistor, and a feedback terminal connected to the output terminal of the head unit Lt; RTI ID = 0.0 > DC-DC < / RTI >

The reference voltage is adjusted to a value existing between the voltage specifications of the power supply unit and is an input value of the comparison unit input terminal.

A charging voltage compensation method in a case where an output connector of a vehicle head unit and an input connector of an external device are electrically connected through a cable according to another aspect of the present invention is characterized in that a power supply voltage inputted to the vehicle head unit is supplied to an output Detecting a voltage appearing at an input connector of the external device; compensating a voltage drop of a voltage appearing at an output connector of the head unit according to a voltage appearing at an input connector of the external device detected; .

The step of detecting the voltage appearing at the input connector of the external device compares the voltage appearing at the input connector of the external device with the reference voltage and outputs a compensation signal when the voltage appearing at the input connector of the external device is smaller than the reference voltage.

The step of compensating for the voltage drop of the voltage appearing at the output connector of the vehicle head unit includes comparing the voltage appearing at the input connector of the external device with a reference voltage,

Forming a parallel connection of the resistors when an activation signal is output according to the comparison result,

And a power supply voltage is distributed according to a parallel connection of the resistor formed to receive the feedback.

 As described above, according to the present invention, it is possible to compensate for the USB operating voltage drop by the USB cable for vehicles.

In addition, the present invention provides the advantage of improving the design efficiency of the charging device by actively controlling the drop and rise of the USB operating voltage.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing an embodiment in which a vehicle power source unit and an external device according to the related art are connected.
2 is a schematic configuration diagram of a power supply apparatus according to an embodiment of the present invention;
3 is a specific circuit diagram of a power supply device according to an embodiment of the present invention.
4 is a flowchart illustrating a voltage compensation process according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. And is intended to enable a person skilled in the art to readily understand the scope of the invention, and the invention is defined by the claims. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. It is noted that " comprises, " or "comprising," as used herein, means the presence or absence of one or more other components, steps, operations, and / Do not exclude the addition.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to designate the same or similar components throughout the drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

2 is a schematic configuration diagram of a power supply apparatus according to an embodiment of the present invention.

 The power supply device 200 provided in the vehicle head unit 100 according to an embodiment of the present invention is configured such that when the output connector 30 of the vehicle head unit and the input connector 40 of the external device are electrically connected through the cable 150 And supplies the power supply voltage to the external device 300 through the cable 150.

Here, the external device 300 may include a mobile communication terminal, a digital broadcasting terminal, an MP3 (Mega Audio Layer-3), a player, a portable multimedia player (PMP), a digital camera, a navigation terminal, An information communication device such as a personal digital assistant (PDA), a smart phone, an International Mobile Telecommunication 2000 (IMT-2000) terminal, a Wideband Code Division Multiple Access (WCDMA) terminal, a universal mobile telecommunication service (UTMS) Multimedia devices.

2, the power supply 200 includes a power supply unit 210 and a voltage compensation unit 220. The power supply unit 210 includes a power supply unit 210 and a voltage compensation unit 220. [ The power supply unit 210 outputs the power supply voltage to the output connector 30 of the head unit 100. The voltage compensating unit 220 detects the voltage appearing at the input connector of the external device and compensates the voltage drop of the voltage appearing at the output connector 30 of the vehicle head unit by the cable 150. [

Specifically, when the voltage appearing at the input connector 40 of the external device is lower than the reference voltage (4.75 V) of the head unit 100 due to the impedance component of the cable 150, the voltage compensating unit 220 outputs the parallel resistance And the voltage VFB input to the power supply unit 210 is distributed by the formed parallel resistors.

The voltage output from the power supply unit 210 is varied due to the input voltage VFB divided by the parallel resistor so that the voltage appearing at the output connector 30 of the head unit is raised, The voltage is compensated.

3 is a specific circuit diagram of a power supply device according to an embodiment of the present invention. Hereinafter, the operation of the power supply apparatus will be described in detail with reference to FIG.

3, the power supply unit 210 includes a PWM (Pulse Width Modulation) controller 211, an inverter 212, a power supply output 10, a feedback terminal 20, An input element 213 and a comparison element 214. [

When the input voltage Vin is applied to the power supply unit 210, the PWM controller 211 transmits the switching signal to the inverter 212 through the pulse width modulation.

The inverter 212 is switched on / off by the pulse width modulation signal output from the PWM controller 211. The input voltage Vin is transmitted to the output connector 30 of the head unit through the power supply output terminal 10 by the switching operation of the inverter 211. [

The input voltage Vin transmitted to the output connector 30 of the head unit is electrically connected to the vehicle USB cable 150 and transmitted to the external device 300 through the input connector 40 of the external device.

At this time, a voltage drop occurs due to the current required for fast charging, normal charging and functioning of the external device and the impedance of the USB cable 150 for the vehicle.

The voltage compensating unit 220 detects a voltage appearing at the input connector 40 of the external device and compensates for the voltage drop of the voltage appearing at the output connector 30 of the vehicle head unit by the cable 150. To this end, the voltage compensating unit 220 includes a comparator 221, a switching unit 222, a first resistor, a second resistor, a third resistor, and one or more reference resistors.

The comparing unit 221 compares the voltage appearing at the input connector 40 of the external device with the reference voltage and outputs a logic value High when the voltage appearing at the input connector 40 of the external device is smaller than the reference voltage do. Here, the reference voltage is a value existing between the voltage specifications of the power supply unit 210 and can be adjusted by connecting the reference resistors.

In one embodiment, the reference voltage may be set to 4.75 V, which is the minimum specification of the power supply 210, and the voltage of the input connector 40 of the external device may be connected to the non-inverting input of the comparator 221.

In one embodiment, when the voltage appearing at the input connector 40 of the external device becomes lower than the reference voltage (4.75 V) due to the resistance (impedance) component of the cable, the comparator 221 outputs a high signal (Logic 1) .

The switching unit 222 is switched according to the logic value obtained from the comparing unit 221 and connects the voltage compensating unit 220 and the power supply unit 210. Specifically, the switching unit 222 is turned on by the output signal received from the comparator 221 to connect the first resistor R1 and the second resistor R2 in parallel.

The parallel resistor formed by the parallel connection of the first resistor R1 and the second resistor R2 and the power supply voltage distributed by the third resistor are input to the feedback terminal 20. [

That is, when the voltage appearing at the external device input connector 40 is smaller than the reference voltage, the first resistor R1 and the second resistor R2 are connected in parallel to form a parallel resistor, (VFB) input to the control unit (20).

As can be seen from the circuit shown in FIG. 3, the voltage input to the feedback terminal 20 by the resistance value variable can be calculated as shown in Equation (1).

[Equation 1]

When a parallel resistor is formed, the voltage distributed by the resistor is input to the feedback terminal 20. The feedback terminal 20 is connected to the input terminal of the comparison element 214.

The comparison element 214 compares the feedback voltage distributed by the parallel resistor with the reference voltage output from the voltage input element 213 and outputs the comparison result. The comparison result becomes an input signal to the PWM controller 211, and controls the inverter 212.

That is, when the distributed feedback voltage is input to the power supply unit 210 due to the parallel connection of the resistors, the input signal of the PWM controller 211 changes, and the pulse width modulation of the PWM controller 211 by the input signal causes the inverter 212 are switched and the power supply voltage output to the power supply output terminal 10 is changed. As a result, the voltage appearing at the output connector 30 of the head unit 100 is raised to compensate for the voltage appearing at the external device input connector 40.

A charging voltage compensation method in a case where an output connector of a vehicle head unit and an input connector of an external device are electrically connected through a cable according to another aspect of the present invention is characterized in that a power supply voltage input to the vehicle head unit is connected to an output connector Comparing the voltage appearing at the input connector of the external device with the reference voltage, and compensating for the voltage drop of the voltage appearing at the output connector of the head unit according to the voltage appearing at the input connector of the external device detected according to the comparison result .

4 is a flowchart illustrating a voltage compensation process according to an embodiment of the present invention. Hereinafter, the charging voltage compensation method and the circuit operation process will be described in more detail with reference to FIG. 3 and FIG.

First, the output connector 30 of the vehicle head unit and the input connector 40 of the external device are electrically connected through the USB cable 150 for the vehicle (S410).

Here, the vehicle USB cable 150 is in accordance with the connection standard of the peripheral device developed by major vehicle companies for interconnection between the vehicle head unit 100 and the external device 300. The USB for the vehicle automatically recognizes when an external device 300 such as a smart device, MP3, or the like is connected.

When the external device 300 is connected to the vehicle head unit, the power source unit 210 outputs the power source voltage Vin input to the vehicle head unit to the output connector 30 of the vehicle head unit.

The comparator 221 compares the voltage appearing on the input connector 40 of the external device with the reference voltage (S420), and outputs a compensation signal or a normal signal according to the comparison result (S430). More specifically, the comparator 221 outputs a logical value 1 when the voltage appearing at the input connector 40 of the external device is smaller than the reference voltage.

When the activation signal is output, the first resistor R1 and the switching unit are connected in series, the first resistor R1 and the second resistor R2 are connected in parallel, and the first resistor R1 and the second resistor R2 are connected in parallel. A parallel resistor is formed according to the parallel connection of Equation (2) (S440).

&Quot; (2) "

The power supply voltage is distributed by the parallel resistor formed according to the parallel connection. Specifically, the power supply voltage is distributed to the feedback terminal 20 by the parallel resistor R1 // R2 and the third resistor R3 formed according to the parallel connection of the first resistor R1 and the second resistor R2 (S450).

As shown in FIG. 3, since the parallel resistor R1 / R2 and the third resistor R3 are connected in series, the divided power voltage can be obtained by Equation (1).

The distributed power source voltage is input to the feedback terminal 20, and the voltage drop appearing in the output connector 30 of the vehicle head unit is compensated using the fed power source voltage (S460).

That is, when the feedback voltage is divided by the parallel connection of the resistors, the power supply voltage output from the power supply unit 210 is actively varied to increase the voltage appearing on the output connector 30 of the head unit 100, The voltage appearing in the capacitor 40 is compensated.

As described above, according to the present invention, it is possible to compensate for the USB operating voltage drop by the USB cable 150 for a vehicle.

In addition, the present invention provides the advantage of improving the design efficiency of the charging device by actively controlling the drop and rise of the USB operating voltage.

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

Claims (8)

A power supply device for electrically connecting an output connector of a vehicle head unit and an input connector of an external device, the power supply device supplying a power supply voltage to the external device via a cable,
A power supply for outputting the power supply voltage to an output connector of the head unit; And
A voltage compensating unit for detecting a voltage appearing at an input connector of the external device and compensating for a voltage drop of a voltage appearing at an output connector of the vehicle head unit by the cable,
≪ / RTI >
The apparatus of claim 1, wherein the voltage compensating unit
A comparator comparing the voltage appearing at the input connector of the external device with a reference voltage and outputting a compensation signal when the voltage appearing at the input connector of the external device is smaller than the reference voltage; And
A switching unit that is switched according to the compensation signal and connects the voltage compensating unit and the power supply unit,
≪ / RTI >
The apparatus of claim 1, wherein the voltage compensating unit comprises:
Comparing the voltage appearing at the input connector of the external device with a reference voltage
A comparator;
A switching unit which is switched by a comparison result of the comparison unit;
A first resistor connected in series with the switching unit;
And a second resistor connected in parallel with the first resistor according to a switching operation of the switching unit
A second resistor;
And a third resistor connected between the output terminal of the power supply unit and the second resistor
Including
Power supply.
The power supply unit according to claim 3,
A feedback terminal for receiving a power supply voltage divided by a parallel resistor formed according to the parallel connection of the first and second resistors and the third resistor; And
A controller for compensating for a voltage drop of a voltage appearing at an output connector of the head unit using the feedback power supply voltage,
Including
Power supply. 3. The method of claim 2,
The power supply unit is adjusted to a value existing between the voltage specifications of the power supply unit,
Which is an input value of the comparator input terminal
Power supply.
A charging voltage compensation method in a case where an output connector of a vehicle head unit and an input connector of an external device are electrically connected through a cable,
Outputting a power supply voltage input to the vehicle head unit to an output connector of the vehicle head unit;
Detecting a voltage appearing at an input connector of the external device;
Compensating a voltage drop of a voltage appearing at an output connector of the head unit according to a voltage appearing at an input connector of the external device detected
/ RTI >
7. The method of claim 6, wherein detecting the voltage appearing at the input connector of the external device
Comparing the voltage appearing at the input connector of the external device with a reference voltage and outputting a compensation signal when the voltage appearing at the input connector of the external device is smaller than the reference voltage
/ RTI >
7. The method of claim 6, wherein compensating for a voltage drop of a voltage appearing at an output connector of the vehicle head unit
Comparing a voltage appearing at an input connector of the external device with a reference voltage;
Forming a parallel connection of the resistors when the activation signal is output according to the comparison result;
Receiving a power supply voltage according to a parallel connection of the resistor;
/ RTI >

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