KR101379393B1 - Power supply apparatus for isg - Google Patents

Abstract

The present invention discloses a power supply apparatus for ISG. The power supply apparatus enables rapid conversion using an FET between a bypass mode which supplies a power source directly from an input terminal to an output terminal and a converter mode which boosts the power source inputted from the input terminal and supplies the power source to the output terminal. Also, the power supply apparatus solves increase in costs, EMC problems, and abnormal behavior due to noise occurrence by minimizing addition of hardware constitution compared to a method of using a comparing device of a prior art through controlling on/off of the FET using a transistor. Additionally, when an N-channel FET is used as a switching element in accordance with the present invention, a cover of the power supply apparatus can be made by plastic injection because heat generation can be decreased relatively as an internal resistance of an FET element is lower than that of a prior art using a P-channel FET. Therefore, fuel efficiency of a vehicle can be improved by decreasing a total weight. [Reference numerals] (220) DC/DC converter [+7V ->+12V]; (232) Voltage stepping-up unit; (AA) ISG signal

Description

Power supply apparatus for ISG

The present invention relates to a power supply, and more particularly to a power supply for Idle Stop and Go (ISG).

ISG (Idle Stop and Go) applied to a vehicle is an automotive system that stops the engine at the time of waiting for a signal and stops the vehicle, and enables the engine to be started again when the vehicle is started to increase fuel economy and efficiency. However, when the engine is running, a voltage drop occurs due to the influence of the motor starting motor, and there is a problem that the electrical device of the vehicle mounted on the vehicle is affected by the voltage drop, and thus an improvement is required.

Some embodiments of the power supply device for the ISG to solve this problem is disclosed in Korean Patent No. 10-1099933. By using a relay switch, the bypass mode (in which the battery power is supplied directly to the vehicle when the engine is running) and the converter mode (the voltage drop in the vehicle caused by the starting motor when the vehicle is restarted when the engine is turned off) are prevented. Bypass operating in bypass mode and converter mode using DC / DC converter and diode for ISG with bypass circuit operated in DC / DC converter to boost voltage to provide constant voltage to vehicle). A DC / DC converter for an ISG with a circuit is disclosed.

However, in the case of using a relay switch, a time delay occurs to turn on / off a physical switch, and in the case of using a diode, there is a problem in that a difference between an input voltage and an output voltage occurs due to a voltage drop of the diode itself. .

In order to solve this problem, Korean Patent No. 10-1099933 discloses a DC / DC converter for an ISG having a bypass circuit operated by using a P-Channel FET and a comparator. 1 is a view showing the configuration of Korean Patent No. 10-1099933.

Referring to FIG. 1, in Korean Patent No. 10-1099933, the comparator 105 performs a function of comparing the input voltage 103 and the output voltage 111 of the DC-DC converter 109, and the comparator 105. When the (+) reference 115 value of) is increased, the inverted LOW output value 113 is applied to the gate and the source of the P-Channel FETs Q1 and 101. When the LOW output value 113 is applied to the FET 101, the P-Channel FETs Q1 and 101 have a higher potential than the gate, so that the drain and the source become conductive, and operate in the bypass mode.

On the contrary, when the input voltage 103 and the output voltage 111 are compared, and the value of the negative reference 117 of the comparator 105 becomes high, the inverted HIGH output value 113 becomes the P-Channel FET (Q1,101). Is applied to the gate and the source. In this case, the P-Channel FET (Q1, 101) is operated in the converter mode because the gate and the source are in the coin state and the current is cut off.

However, in the case of the prior art shown in Fig. 1, the P-Channel FET is controlled by adding a comparator to the entire circuit, thereby malfunctioning due to external unexpected noise, which is a problem when adding a hardware configuration. This is likely to occur and adversely affect EMC performance when adding patterns to the PCB to add hardware configuration.

In addition, in the case of adding a comparator, there is a problem in that the possibility of quality problems caused by an increase in parts cost and an increase in the number of parts is increased.

In addition, since the P-Channel FET applied in FIG. 1 has a higher internal resistance R _DS (on) value than the N-Channel FET, the heat loss is relatively higher than that of the N-Channel FET. Thus, the prior art to increase the efficiency by making the cover of the ISG power supply device to the chassis excellent in the conductivity, in order to improve the efficiency reduction due to heat loss, there is a problem of lowering the vehicle fuel economy due to the weight increase.

The problem to be solved by the present invention is to provide a power supply device for ISG that can reduce the weight of the product to improve the vehicle fuel economy and efficiency.

In addition, another problem to be solved by the present invention is to provide a power supply device for ISG which can be switched between the bypass mode and the converter mode without adding a complicated hardware configuration.

An ISG power supply device according to a preferred embodiment of the present invention for solving the above problems is provided between the input terminal and the output terminal, and is turned on or off in accordance with a switching control signal input from a second switching unit. A first switching unit electrically connecting or disconnecting the output terminal; The second switching unit receiving a mode control signal instructing to turn on or off the first switching unit from a DC / DC converter and outputting the switching control signal corresponding to the mode control signal to the first switching unit; And a mode control signal provided in parallel with the first switching unit between the input terminal and the output terminal to instruct the second switching unit to turn on or off the first switching unit according to the voltage level of the input terminal. And the DC / DC converter for boosting power of an input terminal to provide an output terminal when the first switching unit is off.

In addition, the first switching unit may be implemented as a field effect transistor (FET).

In addition, the source of the FET may be connected to the input terminal, the drain of the FET may be connected to the output terminal.

The second switching unit may include a transistor connected to a gate of the FET, an emitter grounded, and controlling a voltage applied to the gate according to the mode control signal input to the base from the DC / DC converter. It may include.

The first switching unit may be implemented as a P-channel FET, and the second switching unit may further include a booster configured to boost the power supplied from the vehicle to a predetermined voltage and output the voltage to the collector of the transistor.

The second switching unit may further include a resistor having one end connected to the booster and the other end connected to the collector to drop the voltage output from the booster to output the voltage to the collector.

In addition, the second switching unit, the first emitter is grounded, the collector is connected to the base of the second transistor, and receives a mode control signal from the DC / DC converter to turn on or turn off the second transistor transistor; And a constant voltage is applied to the emitter, the collector is connected to the gate of the FET, the base is connected to the collector of the first transistor, and turned on or off according to the current applied from the first transistor to the base. It may include a second transistor for outputting a switching control signal to the gate of the FET.

In addition, the first switching unit may be implemented as a P-channel FET, the second switching unit may further include a boosting unit for boosting the power supplied from the vehicle to a constant voltage to output to the emitter of the second transistor.

The semiconductor device may further include a resistor connected between the collector of the second transistor and the ground.

The DC / DC converter may output the mode control signal to the second switching unit to turn off the first switching unit when the voltage level of the power input from the input terminal is lower than the voltage level required at the output terminal. Can be.

The DC / DC converter may output the mode control signal to the second switching unit to turn off the first switching unit when an ISG signal indicating that the engine motor of the vehicle is started is input from the ISG system.

The DC / DC converter may output the mode control signal to the second switching unit to turn on the first switching unit when the voltage level of the power input from the input terminal is restored to the voltage level required at the output terminal. Can be.

The present invention can quickly switch between a bypass mode for directly supplying power from an input terminal to an output terminal and a converter mode for boosting power input from the input terminal to supply power to the output terminal.

In addition, the present invention solves the problem of increased cost, EMC problem and malfunction due to noise by minimizing the addition of a hardware configuration by using a transistor to control the on / off of the FET by using a conventional comparator.

In addition, when the N-channel FET is used as the switching element of the present invention, since the internal resistance of the FET element is smaller than that of the conventional technique using the P-channel FET, heat generation can be relatively reduced, so that the cover of the power supply unit is made of plastic injection. It is possible to manufacture, and accordingly, it is possible to improve the vehicle fuel economy by reducing the weight.

1 is a view showing an example of a power supply device for an ISG according to the prior art.
2 is a diagram illustrating an example of a power supply device for an ISG according to a first preferred embodiment of the present invention.
3 is a diagram illustrating an example of a power supply device for an ISG according to a second preferred embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

2 is a diagram illustrating an example of a power supply device for an ISG according to a first preferred embodiment of the present invention.

Referring to FIG. 2, the ISG power supply apparatus of the present invention includes a first switching unit 210, a second switching unit 230, and a DC / DC converter 220.

One end of the first switching unit 210 is connected to the input terminal, and the other end is connected to the output terminal, and the input power is connected to the output terminal as it is connected to the output terminal according to the switching control signal input from the second switching unit 220. In the connected bypass mode, the input terminal is electrically separated from the output terminal, and the output terminal operates in the converter mode in which power is supplied from the DC / DC converter 220. In the preferred embodiment of the present invention, the first switching unit is implemented by the FET, and in particular, the n-channel FET is implemented, but any configuration capable of switching the input terminal and the output terminal is not limited thereto.

The second switching unit 230 generates a switching control signal according to the mode control signal input from the DC / DC converter 220 and outputs the switching control signal to the first switching unit, thereby controlling the switching operation of the first switching unit.

One end of the DC / DC converter 220 is connected to the input terminal and the other end is connected to the output terminal, and the mode control signal is transmitted to the second switching unit 230 according to the voltage level of the input terminal or the ISG signal input from the vehicle's ISG system. By controlling the on / off of the first switching unit 210 by outputting the control unit to operate in the bypass mode or the converter mode.

The DC / DC converter 220 monitors the voltage level of the input terminal in the bypass mode, so that the power supply can operate in the converter mode when the voltage level of the input terminal is lower than the reference level required at the output terminal. The control unit 230 controls the first switching unit 210 to be turned off to operate in the converter mode, and boosts the input power in the converter mode to provide it to the output terminal. Thereafter, when the voltage level of the input power source is restored to the reference voltage level required at the output terminal, the second power supply unit bypasses the second switching unit 230 by turning on the first switching unit 210 again. Control to operate in mode.

In this case, according to an embodiment, the DC / DC converter 220 may be configured to switch from the bypass mode to the converter mode according to the ISG signal input from the ISG system of the vehicle.

The second switching unit 230 of the present invention may include a boosting unit 232, a bipolar transistor 236 (hereinafter, abbreviated as “transistor”) and a resistor 234. The switching unit 210 is implemented as a FET, the second switching unit 230 is a case in which the booster 232, the bipolar transistor 236 (hereinafter referred to as "transistor") and the resistor 234 For example, the configuration and operation of the power supply device for the ISG according to the first preferred embodiment of the present invention will be described.

First, the ISG power supply apparatus according to the first preferred embodiment of the present invention operates in a bypass mode and a converter mode. In the bypass mode, the input power is equal to the power required at the output stage while the vehicle is running or the vehicle is stopped. It is an operation mode that transfers the input power to the output power as it is while indicating the voltage level (e.g., 12V). In converter mode, the voltage level of the input power is temporarily lowered than the voltage level required at the output stage (e.g., 7V) at the start of the engine motor. In this case, the input voltage is boosted (eg, boosted from 7V to 12V) through the DC / DC converter 220 to be output.

The DC / DC converter 220 has one side connected to the input terminal B + IN, one side connected to the output terminal B + OUT, and one side connected to the base of the transistor 236.

In the bypass mode, the DC / DC converter 220 turns off the transistor 236 so that the voltage output from the booster 232 is applied to the gate of the FET 210 to turn on the FET 210. In addition, the DC / DC converter 220 outputs a mode control signal to the base of the transistor 236 when the engine start motor is activated to detect that the voltage at the input terminal is lower than the voltage required at the output terminal. By turning on, the gate of the FET 210 is controlled to be grounded, and at the same time, the input voltage (for example, 7V) is boosted and output to a voltage (for example, 12V) required at the output terminal.

The booster 232 boosts the voltage supplied from the outside and outputs the voltage to the resistor R1 234. The booster 232 may be implemented using a diode and a capacitor, and may receive a 12V voltage and output a constant voltage (eg, 22V). However, when the first switching unit 210 is implemented as a P- Channel FET, the booster 232 may be omitted since the gate of the FET is turned on only when the voltage is lower than that of the source side.

One end of the resistor 234 is connected to the booster 232, and the other end is connected to the collector of the transistor 236 and the gate of the FET 210. In the bypass mode in which the transistor 236 is not turned on, the resistor 234 drops the voltage output from the booster 232 to output the gate of the FET 210 to turn on the FET 210. In converter mode, where transistor 236 is turned on, resistor 234 prevents boost 232 from being directly connected to ground.

Meanwhile, the base of the transistor 236 is connected to the DC / DC converter 220 to receive a mode control signal from the DC / DC converter 220, the emitter of the transistor 236 is grounded, and the collector is the FET 210. Is connected to the gate and the resistor 234.

The FET 210 has a gate connected to the resistor 234 and the collector of the transistor 236, and a source connected to an input terminal and a drain connected to an output terminal, respectively. Thus, by connecting the source and the drain to the input terminal and the output terminal, respectively, the parasitic diode is disposed in the forward direction from the input terminal to the output terminal, thereby preventing the power supply from flowing back from the output terminal to the input terminal.

Referring to FIG. 2, the operation of the power supply device for the ISG according to the first embodiment of the present invention will be described. The transistor 236 is in an OFF state while the vehicle is being driven and stopped. Power is input through the resistor 234 to the gate of the FET 210 so that the FET 210 is in the ON state. However, as described above, when the FET 210 is a P-Channel FET, the booster 232 is omitted, and the power supplied from the vehicle is directly supplied to the resistor 234.

On the other hand, when the vehicle starts and the engine motor starts after the vehicle stops according to the operation of the ISG system, the input voltage drops momentarily, and the DC / DC converter 220 detects that the input voltage is lower than the voltage required at the output terminal. In order to operate in the converter mode, a mode control signal is output to the base of the transistor 236 to turn the transistor 236 on. Accordingly, the gate of the FET 210 is grounded so that the FET 210 is turned on. Turn OFF to cut off the direct power supply from input to output.

On the other hand, the DC / DC converter 220 boosts the voltage of the power input from the input terminal to the voltage level required at the output terminal immediately after outputting the mode control signal to the base and outputs the voltage (eg, 7V-> 12V). It is continuously powered by 12V.

Thereafter, when the engine is started, the input voltage is restored to the voltage level required at the output stage again, and the DC / DC converter 220 detects that the voltage at the input stage is restored and returns to the bypass mode to return to the bypass mode. The transistor 236 is turned off by stopping the mode control signal outputted to the base of the control panel. Then, the power output from the booster 232 is provided to the gate of the FET 210 through the resistor 234 again, the FET 210 is turned on again, and the power input from the input terminal is directly supplied to the output terminal again. It is operated in pass mode.

Thereafter, when the vehicle is stopped again and the engine is started again, the process proceeds from the bypass mode to the converter mode through the above-described process.

Meanwhile, in the above-described first embodiment, an example in which the DC / DC converter 220 switches between the bypass mode and the converter mode by measuring the voltage level at the input terminal is described. The signal may be converted to the converter mode from the bypass mode, and then the voltage level of the input terminal may be measured to switch from the converter mode to the bypass mode.

Specifically, the ISG system turns off the engine when the vehicle stops (e.g., when the brakes of the vehicle are activated), and starts the engine when the vehicle moves (e.g., when the user releases the brakes). Generates and outputs the DC / DC converter 220 to the DC / DC converter 220. When the ISG signal is input, the DC / DC converter 220 immediately outputs a mode control signal to the base of the transistor 236 to turn on the transistor 236. The FET 210 is turned off and operated in the converter mode by boosting the power input from the input terminal and outputting the power to the output terminal. After that, when the voltage level of the power source input from the input terminal reaches the voltage level required by the output terminal, the transistor 236 is turned off and the FET ( Turn on 210 to proceed in bypass mode.

3 is a diagram illustrating an example of a power supply device for an ISG according to a second preferred embodiment of the present invention. The power supply device for the ISG according to the second preferred embodiment of the present invention operates in the bypass mode and the converter mode like the first embodiment.

Referring to FIG. 3, a power supply device for an ISG according to a second exemplary embodiment of the present invention includes a first switching unit 210, a second switching unit 240 , and a DC / DC converter 220. The functions of these components are the same as those of the first switching unit 210, the second switching unit 230, and the DC / DC converter 220 of the first embodiment.

In the second preferred embodiment of the present invention, the second switching unit 240 includes two BJTs (the first transistor 244 and the second transistor 246), the resistors 248 ( ,) and the booster 242 ( The first switching unit is implemented using a P-channel FET, which can be omitted), and thus, a configuration and an operation of the second embodiment will be described below.

 As described above, in the second preferred embodiment of the present invention, the first switching unit 210 is implemented using a P-channel or N-channel FET, and the second switching unit 240 is a booster unit 242, And a first transistor 244, a second transistor 246, a resistor 248, and a DC / DC converter 220.

First, the DC / DC converter 220 has one side connected to the input terminal B + IN, one side connected to the output terminal B + OUT, and one side connected to the base of the first transistor 244.

In the bypass mode, the DC / DC converter 220 sends a mode control signal to the first transistor 244 such that the voltage output from the booster 242 is applied to the gate of the FET 210 so that the FET 210 is turned on. Is output to turn on the first transistor 244. When the first transistor 244 is turned on, the second transistor 246 is turned on in conjunction.

In addition, the DC / DC converter 220 stops outputting the mode control signal to the base of the first transistor 244 when the engine start motor is activated to detect that the voltage at the input terminal is lower than the voltage required at the output terminal. Turn off the FET 210 by turning off the first transistor 244 and the second transistor 246 in turn, and simultaneously boost the input voltage (eg, 7V) to the voltage (eg, 12V) required at the output terminal. By outputting, it switches to the converter mode and operates.

The booster 242 boosts the voltage supplied from the outside and outputs the voltage to the second transistor 246. The booster 242 may be implemented using a diode and a capacitor, and may receive a 12V voltage and output a 22V voltage. In addition, as described above, when the first switching unit 210 is implemented as a P-channel FET, the boosting unit 242 may be omitted.

The resistor 248 is grounded at one end and connected to the collector of the second transistor 246 and the gate of the FET 210. In the bypass mode in which the second transistor 246 is in the ON state, the resistor 248 blocks the boost 242 from being immediately grounded and allows a constant voltage to be applied to the gate of the FET 210.

Meanwhile, the base of the first transistor 244 is connected to the DC / DC converter 220 to receive a mode control signal from the DC / DC converter 220, the emitter of the first transistor 244 is grounded, and the collector Is connected to the base of the second transistor 246.

The base of the second transistor 246 is connected to the collector of the first transistor 244, the emitter is connected to the booster 242, and the collector is connected to the resistor 248 and the gate of the FET 210.

The first transistor 244 and the second transistor 246 are turned on at the same time in the bypass mode to turn on the FET 210, and at the same time in the converter mode to turn off the FET 210.

The FET 210 has a gate connected to the resistor 248 and the collector of the second transistor 246, the source of which is connected to the input terminal and the drain of the output terminal, respectively. Thus, by connecting the source and the drain to the input terminal and the output terminal, respectively, the parasitic diode is disposed in the forward direction from the input terminal to the output terminal, thereby preventing the power supply from flowing back from the output terminal to the input terminal.

Referring to FIG. 3, the operation of the power supply device for the ISG according to the second embodiment of the present invention will be described. A mode control signal is transmitted from the DC / DC converter 220 to the first transistor 244 during driving and stopping of the vehicle. Is continuously output so that the first transistor 244 and the second transistor 246 are in the ON state, and the power output from the booster 242 is input to the FET 210 gate so that the FET 210 is in the ON state. have.

On the other hand, when the vehicle starts and the engine motor starts after the vehicle stops according to the operation of the ISG system, the input voltage drops momentarily, and the DC / DC converter 220 detects that the input voltage is lower than the voltage required at the output terminal. In order to operate in the converter mode, the output of the mode control signal to the base of the first transistor 244 is stopped to turn off the first transistor 244 and the second transistor 246 in turn. The FET 210 is turned off to cut off the direct power supply from the input stage to the output stage.

On the other hand, immediately after the output of the mode control signal, the DC / DC converter 220 boosts the voltage of the power input from the input terminal to the voltage level required at the output terminal (for example, 7V-> 12V) and outputs the output terminal. It is continuously powered by 12V.

Thereafter, when the engine is started, the input voltage is restored to the voltage level required by the application stage, and the DC / DC converter 220 detects that the voltage at the input terminal is restored and proceeds to the bypass mode again. The mode control signal is output to the base of the transistor 244 to sequentially turn on the first transistor 244 and the second transistor 246.

Then, the power output from the booster 242 is supplied to the gate of the FET 210 again, the FET 210 is turned on again, and the power input from the input terminal is directly supplied to the output terminal again to operate in the bypass mode.

Thereafter, when the vehicle is stopped again and the engine is started again, the process proceeds from the bypass mode to the converter mode through the above-described process.

Meanwhile, in the above-described second embodiment, an example in which the DC / DC converter 220 switches between the bypass mode and the converter mode by measuring the voltage level of the input terminal has been described, but as in the first embodiment, the DC / DC converter 220 ) May receive the ISG signal from the ISG system, switch from the bypass mode to the converter mode, and then switch from the converter mode to the bypass mode by measuring the voltage level of the input terminal.

Specifically, the ISG system turns off the engine when the vehicle stops (e.g., when the brakes of the vehicle are activated), and starts the engine when the vehicle moves (e.g., when the user releases the brakes). Is generated and output to the DC / DC converter 220, and the DC / DC converter 220 immediately stops outputting the mode control signal to the base of the first transistor 244 when the ISG signal is input. 244 and second transistor 246 are turned off in turn, thereby turning off FET 210. Simultaneously with this operation, the DC / DC converter 220 operates in the converter mode by boosting the power input from the input terminal and outputting it to the output terminal. Thereafter, when the voltage level of the power source input from the input terminal reaches the voltage level required by the output terminal, the first transistor 244 is output by outputting a mode control signal to the base of the first transistor 244 in the same manner as described above. The second transistor 246 and the FET 210 are sequentially turned on to bypass the bypass mode.

The present invention has been described with reference to the preferred embodiments. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

210 : FET 220 : DC / DC converter
230 : second switching unit 240 : second switching unit
244 : first transistor 246 : second transistor
234, 248 : resistance

Claims (12)

A first switching unit disposed between an input terminal and an output terminal, the first switching unit being turned on or off according to a switching control signal input from a second switching unit to electrically connect or disconnect the input terminal and the output terminal;
The second switching unit receiving a mode control signal instructing to turn on or off the first switching unit from a DC / DC converter and outputting the switching control signal corresponding to the mode control signal to the first switching unit; And
Between the input terminal and the output terminal, provided in parallel with the first switching unit, outputting the mode control signal to the second switching unit instructing to turn on or off the first switching unit according to the voltage level of the input terminal; And the DC / DC converter for boosting power of an input terminal to provide an output terminal when the first switching unit is turned off. The method of claim 1,
The first switching unit is a power supply for the ISG, characterized in that implemented by a field effect transistor (FET). 3. The method of claim 2,
And a source of the FET is connected to the input terminal and a drain of the FET is connected to the output terminal. The method of claim 2, wherein the second switching unit
And a collector connected to the gate of the FET, the emitter being grounded, and a transistor for adjusting the voltage applied to the gate in accordance with the mode control signal input from the DC / DC converter to the base. Power supply. 5. The method of claim 4,
The first switching unit is implemented with a P-channel FET,
The second switching unit further includes a booster for boosting the power supplied from the vehicle to a constant voltage and outputting the voltage to the collector of the transistor. The method of claim 5, wherein the second switching unit
One end is connected to the boosting unit, the other end is connected to the collector, the power supply for the ISG further comprises a resistance to drop the voltage output from the boosting unit to output to the collector.
The method of claim 2, wherein the second switching unit
A first transistor having an emitter grounded, a collector connected to a base of a second transistor, and receiving a mode control signal from the DC / DC converter to turn on or turn off the second transistor; And
A constant voltage is applied to the emitter, a collector is connected to the gate of the FET, a base is connected to the collector of the first transistor, and the FET is turned on or off depending on the current applied from the first transistor to the base. And a second transistor for outputting a switching control signal to a gate of the ISG. The method of claim 7, wherein
The first switching unit is implemented with a P-channel FET,
The second switching unit further includes a booster for boosting the power supplied from the vehicle to a constant voltage and outputting the output to the emitter of the second transistor. The method of claim 8,
And a resistor coupled between the collector of the second transistor and ground. The method of claim 1, wherein the DC / DC converter
And when the voltage level of the power input from the input terminal is lower than the voltage level required by the output terminal, outputting the mode control signal to the second switching unit to turn off the first switching unit. . The method of claim 1, wherein the DC / DC converter
And when the ISG signal indicating that the engine motor of the vehicle is started is input from the ISG system, outputting the mode control signal to the second switching unit to turn off the first switching unit. The method of claim 10 or 11, wherein the DC / DC converter
And when the voltage level of the power input from the input terminal is restored to the voltage level required by the output terminal, outputting the mode control signal to the second switching unit to turn on the first switching unit. .

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