KR20190110998A - Apparatus and method for protection of bi-directional dc-dc converter - Google Patents

Abstract

Disclosed are a protection device for a bidirectional DC-DC converter and a method therefor. According to the present invention, the protection device for a bidirectional DC-DC converter comprises: a power conversion unit having a plurality of switches to perform voltage conversion bidirectionally between a low voltage battery and a high voltage battery; and a control unit detecting a current value flowing through the power conversion unit to determine whether overcurrent occurs through comparison with a reference current value, and turning off all switches of the power conversion unit since it is determined that the overcurrent occurs when the detected current value is equal to or greater than the reference current value. The power conversion unit includes: a protection switch unit for blocking the flow of current when the overcurrent occurs; and a protection circuit unit for stopping, when the overcurrent occurs, the operation of the power conversion unit by turning off the protection switch unit when all the switches of the power conversion unit are not turned off. Therefore, stability can be increased.

Description

Protection device and method of bidirectional DC-DC converter {APPARATUS AND METHOD FOR PROTECTION OF BI-DIRECTIONAL DC-DC CONVERTER}

The present invention relates to a protection device and method of a bidirectional DC-DC converter, and more particularly, to protect a bidirectional DC-DC converter operating in hardware by applying a secondary protection circuit to an input / output terminal of a bidirectional DC-DC converter. An apparatus and method are provided.

In general, a power system of a vehicle is a system for supplying electric power for operating electronic components, safety components, or various accessories in a vehicle, and in general, operates electronic components in the vehicle by supplying a DC voltage. Conventionally, a 12V power system has been used as a power system of a vehicle, but recently, a 48V power system has been widely used to increase energy capacity and improve power efficiency by using high power electronic components.

However, when the 48V power system is applied, there is a problem that all electronic components of the vehicle, which were operated at the conventional 12V voltage, need to be replaced for 48V. As a result, the parts with low power consumption operate at 12V voltage as before, and the parts with high power consumption such as electric steering system or air conditioning system operate at 48V voltage, thus enabling efficient use of power. . 12V-48V power conversion system is usually used bi-directional DC-DC converter, bi-directional DC-DC converter is a multi-phase structure to accommodate high capacity, fast response of power conversion, and share the current to improve efficiency It is used. In addition, the bidirectional DC-DC converter has an interleaved structure, distributing the current in each phase to reduce the stress on the device. In other words, the bidirectional DC-DC converter is installed between 12V and 48V batteries and converts power through boost and step operations.

On the other hand, the bi-directional DC-DC converter can perform power conversion by switching the power conversion unit including a micro controller unit (MCU), and turns off the switching operation when an abnormal operation such as over current is detected by detecting a current value in the MCU. It can be controlled and stopped. However, a malfunction in the MCU itself can lead to a problem that can't detect overcurrent and cause a fatal error that causes the converter to fail.

Background art of the present invention is the Republic of Korea Patent Publication No. 0774673 (2007.11.08.) "The transformer heat radiation structure of the DC / DC converter".

According to an aspect of the present invention, the present invention was devised to improve the above problems, by applying a secondary protection circuit to the input and output terminals of the bi-directional DC-DC converter to turn off the switching operation in hardware when an error occurs It is an object of the present invention to provide a protection device and method for a bidirectional DC-DC converter (Turn OFF).

According to an aspect of the present invention, there is provided a protection device of a bidirectional DC-DC converter, including: a power converter configured to perform voltage conversion in both directions between a low voltage battery and a high voltage battery having a plurality of switches; And sensing the current value flowing through the power converter to determine whether an overcurrent occurs through comparison with a reference current value, and if the detected current value is greater than or equal to the reference current value, determines that overcurrent has occurred. It includes; a control unit for turning off (Turn Off), wherein the power conversion unit, a protection switch unit for blocking the flow of current when an overcurrent occurs; And a protection circuit unit configured to stop the operation of the power conversion unit by turning off the protection switch unit when all the switches of the power conversion unit are not turned off when the overcurrent occurs.

In the present invention, the protection circuit unit, the signal amplifier for amplifying the voltage of the current measuring unit for measuring the current of the power conversion unit; A comparator for comparing an output voltage of the signal amplifier and a preset reference voltage; A latch circuit unit configured to output an output signal for changing an enable signal of a power supply IC according to a comparison result of the comparator; And a protection switch driver for turning on or off the protection switch by using a power source of the power supply IC.

In the present invention, when the output voltage of the signal amplifier is greater than or equal to the reference voltage as a result of the comparison of the comparator, the latch operation occurs in the latch circuit portion so that the enable signal of the power supply IC is low. It features.

In the present invention, when the enable signal of the power supply IC is low, the power supply of the power supply IC is cut off, so that the protection switch unit driver to turn off the protection switch unit.

In the present invention, the latch circuit portion, it characterized in that it comprises a D-FlipFlop (FlipFlop) circuit.

In the present invention, the control unit, the state of the low voltage battery and the high voltage battery, and based on the state of the low voltage battery and the high voltage battery in the buck (Buck) mode and high voltage in the low voltage battery for stepping down from the high voltage battery to the low voltage battery In order to perform a boost mode for boosting the battery, the plurality of switches of the power converter may be turned on or off, respectively, so that the voltages of the low voltage batteries and the high voltage batteries reach a target voltage. .

According to another aspect of the present invention, there is provided a method of protecting a bidirectional DC-DC converter, the power converter including a plurality of switches to perform voltage conversion in both directions between a low voltage battery and a high voltage battery; Detecting, by the controller, a current value flowing through the power converter to determine whether an overcurrent occurs through comparison with a reference current value; If the current value sensed by the controller is equal to or greater than a reference current value, determining that overcurrent has occurred and turning off all switches of the power converter; And stopping the operation of the power conversion unit by turning off the protection circuit unit included in the power conversion unit to block the flow of current when all the switches of the power conversion unit are not turned off when an overcurrent occurs. It characterized in that it comprises a step.

The present invention includes a step of amplifying a voltage of the current measuring unit for measuring the current by the signal amplifier for the power converter; A comparator comparing the output voltage of the signal amplifier with a preset reference voltage; Outputting an output signal of a latch circuit unit to enable an enable signal of a power supply IC according to a comparison result of the comparator; And turning on or off the protection switch unit by using a protection switch driver using a power source of the power supply IC.

In the step of turning off the protective switch of the present invention, the protective circuit unit, when the output voltage of the signal amplifier is greater than the reference voltage as a result of the comparison of the comparator latch operation occurs in the latch circuit portion to enable the power supply IC Characterized in that the signal is low (Low).

In the step of turning off the protection switch unit of the present invention, when the enable signal of the power supply IC is low, the power supply of the power supply IC is cut off so that the protection switch driver to turn the protection switch unit To be turned off.

The present invention includes the steps of the controller to determine the state of the low voltage battery and high voltage battery; And the control unit performs a buck mode for stepping down from a high voltage battery to a low voltage battery and a boost mode for stepping up from a low voltage battery to a high voltage battery based on the states of the low voltage battery and the high voltage battery. And turning on or off the plurality of switches of the power converter, respectively, so that voltages of the low voltage batteries and the high voltage batteries reach a target voltage.

An apparatus and method for protecting a bidirectional DC-DC converter according to an embodiment of the present invention applies a secondary protection circuit to an input / output terminal of a bidirectional DC-DC converter to turn off a switching operation in hardware when an error occurs. As a result, the switching operation can be turned off even when a malfunction occurs in software and the primary protection fails, thereby improving stability.

1 is a view schematically showing a protection device of a bidirectional DC-DC converter according to an embodiment of the present invention.
2 is a view showing a protection circuit in the protection device of the bidirectional DC-DC converter according to an embodiment of the present invention.
3 is a flowchart illustrating a protection method of a bidirectional DC-DC converter according to an embodiment of the present invention.

Hereinafter, a protection apparatus and a method of a bidirectional DC-DC converter according to an embodiment of the present invention will be described with reference to the accompanying drawings. In this process, the thickness of the lines or the size of the components shown in the drawings may be exaggerated for clarity and convenience of description.

In addition, terms to be described below are terms defined in consideration of functions in the present invention, which may vary according to the intention or convention of a user or an operator. Therefore, the definitions of these terms should be made based on the contents throughout the specification.

1 is a view schematically illustrating a protection device of a bidirectional DC-DC converter according to an embodiment of the present invention, and FIG. 2 is a protection circuit part of a protection device of a bidirectional DC-DC converter according to an embodiment of the present invention. As a drawing, a protection device of a bidirectional DC-DC converter will be described with reference to the following.

As shown in FIG. 1, a protection device of a bidirectional DC-DC converter according to an embodiment of the present invention may perform voltage conversion in both directions between a low voltage battery (eg, 12V) and a high voltage battery (eg, 48V). It may include a power converter 200 and a control unit 100 for controlling the power converter 200.

In addition, the bi-directional DC-DC converter according to an embodiment of the present invention is composed of an interleaved structure (interleaved) structure can distribute the current in each phase to reduce the stress applied to the device.

Referring to FIG. 1, the circuit configuration of the power converter 200 in the bidirectional DC-DC converter according to the present embodiment will be described in detail. The power converter 200 includes a first switch SW1 and a second switch ( SW2), the inductor (L), the protection circuit portion (I), LV protection switch unit 20 and HV protection switch unit 21, and may also include the first switch (SW1) and the second switch (SW2) It may include a switch driver (SW DRV) for turning on / off.

The first switch SW1 is connected to the HV protective switch unit 21 and one terminal thereof. The second switch SW2 is connected between the other terminal of the first switch SW1 and ground. In addition, although not shown in the drawing, the HV protective switch unit 21 may be connected to a high voltage battery (not shown) via the BUSBAR. The inductor L is connected to a connection node of the first switch SW1 and the second switch SW2 and one terminal thereof. And the other terminal of the inductor (L) is connected to the current measuring unit 24 for measuring the large current flowing in the power converter 200, the current measuring unit 24 is the LV protection switch unit 20 and one terminal thereof Is connected. In addition, although not shown in the drawing, the LV protective switch unit 20 may be connected to a low voltage battery (not shown) via the BUSBAR. The first switch SW1, the second switch SW2, the LV protection switch 20, and the HV protection switch 21 may be configured as a field effect transistor (FET), but are not limited thereto. A switch can be employed.

On the other hand, referring to Figure 1, the above-described circuit configuration can be configured by connecting a plurality of in parallel according to the capacity of the bidirectional DC-DC converter, each circuit configuration is LV protective switch unit 20 and HV protective switch Although illustrated as being integrally connected to the unit 21, the LV protective switch unit 20 and the HV protective switch unit 21 may be provided in each circuit configuration.

Based on the above-described circuit configuration, the controller 100 includes a power supply unit 11, a voltage sensing unit 12, a microcontroller unit 13, a communication unit 14, and a current sensing unit 15. At least one of the switch SW1, the second switch SW2, the LV protective switch 20, and the HV protective switch 21 may be turned on or turned off. At this time, the control unit 100 controls switching of the first switch SW1, the second switch SW2, the LV protective switch unit 20, and the HV protective switch unit 21 through the MCU 13 or the PWM IC ( It can be controlled by PWM control including Pulse Width Modulation Integrated Circuit.

Meanwhile, in the present embodiment, the controller 100 may mean integrated control means including components necessary for the MCU 13 to control the protection device of the bidirectional DC-DC converter as a whole.

The power supply unit 11 is an electric energy source for supplying power to the control unit 100.

The voltage sensing unit 12 detects the voltages of the low voltage battery and the high voltage battery and transmits them to the MCU 13, through which the MCU 13 can determine the states of the low voltage battery and the high voltage battery.

The communication unit 13 controls signals of the MCU 13 to the first switch SW1, the second switch SW2, the LV protective switch unit 20 and the HV protective switch unit 21 and other control elements. Send it. The communication unit 13 may transmit a control signal through a controller area network (CAN) method, a 1 wire method, or a 2 wire method, but the communication method of the communication unit described above is merely an example and is not limited thereto.

The current detector 15 detects a current flowing in the power converter 200 and transmits the current to the MCU 13. Through this, the MCU 13 can identify an error such as an overcurrent occurrence. At this time, the current sensing unit 15 and the current measuring unit 24 to be described later may be configured in the same way.

That is, the MCU 13 may determine the states of the low voltage battery and the high voltage battery through the voltage sensing unit 12 and perform bidirectional power conversion based on the states of the low voltage battery and the high voltage battery. More specifically, the MCU 13 may perform a buck mode for stepping down from a high voltage battery to a low voltage battery, and may perform a boost mode for boosting the voltage from the low voltage battery to the high voltage battery. . In this case, the MCU 13 may turn on or turn off each of the plurality of switches of the power converter 200 so that the voltages of the low voltage batteries and the high voltage batteries reach the target voltages. On the other hand, since a technique for performing a power conversion by performing the buck-boost mode between the low voltage battery and the high voltage battery is a known technique, a detailed method will be omitted. In addition, since the present embodiment discloses a protection device for a bidirectional DC-DC converter, a circuit configuration for performing the buck-boost mode is schematically shown.

The MCU 13 may detect a current flowing through the power converter 200 through the current detector 15, and generate an overcurrent by comparing the detected current value with a reference current value preset for overcurrent detection. It can be determined. At this time, the MCU 13 may determine that an overcurrent has occurred if the detected current value is greater than or equal to the reference current value, and when it is determined that the overcurrent has occurred, turn off all the switches of the power converter 200. The converter can be stopped.

However, when a malfunction occurs in the MCU 13 itself, the converter operation is not stopped because all the switches are not turned off even when an overcurrent occurs. This can result in a fatal error in which the converter fails. In addition, in the case of the 12V-48V bidirectional converter as in this embodiment, the detection of overcurrent is more important because the current range is large depending on the capacity.

Therefore, in the present embodiment, the protection circuit unit I is provided so that the secondary protection can be performed in hardware even when the MCU 13 itself malfunctions.

That is, the power conversion unit 200 includes an LV protection switch unit 20 and an HV protection switch unit 21 to block the flow of current when an overcurrent occurs, and when the overcurrent occurs, all the switches of the power conversion unit When not turned off, that is, when the switching control is not performed due to a malfunction of the MCU 13, the operation of the power converter 20 is caused by turning off the LV protective switch 20 and the HV protective switch 21. The protection circuit part I which stops is included.

The protection circuit unit I may include a current measuring unit 24, a signal amplifier 25, a comparator 26, a latch circuit unit 27, a power supply IC 28, and a protection switch unit driver 29. In this case, in the present embodiment, the protection switch driver 29 is included in the protection circuit unit I, but may be included in the LV protection switch unit 20 and the HV protection switch unit 21, respectively.

The current measuring unit 24 measures a large current flowing through the power converter 200 and may be configured as a shunt resistor.

The signal amplifier 25 may have an input terminal connected to the current measuring unit 24 and an output terminal connected to the comparator 26 to amplify a voltage input from the current measuring unit 24 and output the amplified voltage to the comparator 26. .

The comparator 26 may compare the output voltage of the signal amplifier 25 with a preset reference voltage. That is, the comparator 26 may use the reference voltage, which is the output of the reference voltage generator (not shown), as the positive terminal input, and use the output voltage of the signal amplifier 25 as the negative terminal input. The comparator 26 may compare the reference voltage with the output voltage of the signal amplifier 25 and output a signal for the comparison result to the latch circuit 27.

At this time, the comparator 26 may output a Hi signal when the reference voltage is higher than the output voltage of the signal amplifier 25, and when the reference voltage is lower than the output voltage of the signal amplifier 25. It can output a low signal.

The latch circuit unit 27 may be configured to output an output signal for changing an enable signal of the power supply IC 28 according to a comparison result of the comparator 26.

In this case, a NOT gate may be provided between the comparator 26 and the latch circuit unit 27. That is, a value opposite to the signal output from the comparator 26 is output.

Therefore, as a result of the comparison in the comparator 26, when the reference voltage is higher than the output voltage of the signal amplifier 25, a low signal is input to the latch circuit section 27, and the reference voltage is output of the signal amplifier 25. When the voltage is lower than the voltage, a high signal may be input to the latch circuit unit 27.

On the other hand, the latch circuit unit 27 may include a D-FlipFlop circuit. The D-flip-flop circuit operates according to the clock signal CLK and outputs a control signal input to the D stage synchronized with the clock signal although not shown in the drawing for the control signal input to the D stage.

Therefore, the latch circuit unit 27 may cause the switching element to be turned on when the high signal is input, so that the enable signal of the power supply IC 28 is low, and when the low signal is input, the switching element is turned. By turning it off, the enable signal of the power supply IC 28 can be made high.

The power supply IC 28 receives power from the battery and outputs power. When the enable signal is low, the power supply IC 28 may be cut off.

The protection switch driver 29 turns on or off the LV protection switch 20 and the HV protection switch 21 using the power of the power supply IC 28. That is, when the power source IC 28 is cut off, the protection switch driver 29 turns off the LV protection switch 20 and the HV protection switch 21 to operate the power converter 200. Can be stopped.

That is, when the signal amplifier 25 amplifies the voltage input from the current measuring unit 24 and outputs it to the comparator 26, the comparator 26 compares the output voltage of the signal amplifier 25 with the reference voltage. When the over current occurs, the reference voltage is lower than the output voltage of the signal amplifier 25. Therefore, the low signal is output from the comparator 26, and the high signal is input to the latch circuit section 27 through the NOT gate. At this time, the latch circuit unit 27 inputs a high signal to the clock terminal and outputs a high signal, and the switching element is turned on so that most of the current flows to the ground, so that the enable signal of the power supply IC 28 becomes low. That is, the power of the power supply IC 28 is cut off, the operation of the power converter 200 is stopped, and the converter can be protected by preventing a failure due to overcurrent.

Accordingly, when the output voltage of the signal amplifier 25 is greater than or equal to the reference voltage as a result of the comparison of the comparator 26, the protection circuit unit I generates a latch operation in the latch circuit unit 27, thereby enabling the enable signal of the power supply IC 28. Make it low. In addition, when the enable signal of the power supply IC 28 becomes low when the enable circuit of the protection circuit unit I is low, the power supply of the power supply IC 28 is cut off, and the protection switch unit driver 29 causes the LV protection switch unit 20 and the HV. The protection switch unit 21 is turned off.

3 is a flowchart illustrating a protection method of the bidirectional DC-DC converter according to an embodiment of the present invention. Referring to this, a protection method of the bidirectional DC-DC converter will be described below.

As shown in FIG. 3, in the protection method of the bidirectional DC-DC converter according to an embodiment of the present invention, the controller 100 first checks a battery state (S10).

That is, the controller 100 may receive the voltage detection values of the low voltage battery and the high voltage battery from the voltage detector 12 to determine the state of the low voltage battery and the high voltage battery.

Next, the control unit 100 turns on the protective switch units 20 and 21 (S20).

In this case, the protection switch units 20 and 21 may include the LV protection switch unit 20 on the low voltage battery side and the HV protection switch unit 21 on the high voltage battery side.

The controller 100 drives the power converter 200 by turning on or off a plurality of switches of the power converter 200 based on the battery state determined in step S10 (S30).

That is, the controller 100 may determine the state of the high voltage battery and the low voltage battery to perform a buck mode for stepping down from the high voltage battery to the low voltage battery, and boost (for boosting the voltage from the low voltage battery to the high voltage battery). Boost mode may be performed, and at least one of the first switch SW1 and the second switch SW2 may be turned on.

In this case, when at least one of the first switch SW1 and the second switch SW2 is not turned on, the controller 100 may determine that power conversion between the high voltage battery and the low voltage battery is not necessary and terminate the control.

In operation S20, when at least one of the first switch SW1 and the second switch SW2 is turned on, the controller 100 determines whether an error such as an overcurrent occurs.

The controller 100 may receive the current sensing value from the current sensing unit 15 to determine the occurrence of overcurrent.

In step S40, when no error occurs, the controller 100 determines whether the voltage of the high voltage battery or the low voltage battery reaches the target voltage as a result of performing the buck mode or the boost mode (S50).

If the target voltage has not been reached in step S50, the process returns to step S40 until the target voltage is reached to determine whether an error occurs, and power conversion of the buck mode or the boost mode can be continued.

Meanwhile, in operation S40, when an error occurs, the operation of the protection circuit unit I varies according to whether all the switches of the power converter 200 are turned off and stopped.

That is, when the driving of the power converter 200 is stopped in step S60 may be terminated.

However, when all the switches are not turned off even when the overcurrent occurs (when the driving of the power converter 200 is not stopped), the overcurrent is detected in hardware through the protection circuit unit I (S70), and the LV protection switch. The secondary 20 and the HV protective switch 21 are turned off to perform secondary protection (S80).

That is, when a malfunction occurs in the controller 100 itself, the converter operation is not stopped because all the switches are not turned off even when an overcurrent occurs. Accordingly, in the present exemplary embodiment, the protection circuit unit I is provided so that the secondary protection can be performed in hardware even when the control unit 100 itself malfunctions.

The protection circuit unit I may include a current measuring unit 24, a signal amplifier 25, a comparator 26, a latch circuit unit 27, a power supply IC 28, and a protection switch unit driver 29. have.

The signal amplifier 25 may amplify the voltage input from the current measuring unit 24 and output the amplified voltage to the comparator 26. The comparator 26 may output an output voltage of the signal amplifier 25 and a preset reference voltage. Can be compared. The comparator 26 may compare the reference voltage with the output voltage of the signal amplifier 25 and output a signal for the comparison result to the latch circuit 27.

At this time, the comparator 26 may output a Hi signal when the reference voltage is higher than the output voltage of the signal amplifier 25, and when the reference voltage is lower than the output voltage of the signal amplifier 25. A low signal may be output. When an overcurrent occurs, a low signal is output because the reference voltage is lower than the output voltage of the signal amplifier 25.

The latch circuit unit 27 is configured to output an output signal for changing the enable signal of the power supply IC 28 according to the comparison result of the comparator 26. That is, when the low signal is output from the comparator 26 and the high signal is input to the latch circuit unit 27 through the NOT gate, the switching element is turned on to enable the enable signal of the power supply IC 28 to be low. That is, the power of the power supply IC 28 is cut off, the operation of the power converter 200 is stopped, and the converter can be protected by preventing a failure due to overcurrent.

Accordingly, when the output voltage of the signal amplifier 25 is greater than or equal to the reference voltage as a result of the comparison of the comparator 26, the protection circuit unit I generates a latch operation in the latch circuit unit 27, thereby enabling the enable signal of the power supply IC 28. Make it low. In addition, when the enable signal of the power supply IC 28 becomes low when the enable circuit of the protection circuit unit I is low, the power supply of the power supply IC 28 is cut off, and the protection switch unit driver 29 causes the LV protection switch unit 20 and the HV. The protection switch unit 21 is turned off.

As described above, the protection device and method of the bidirectional DC-DC converter according to an embodiment of the present invention by applying a secondary protection circuit to the input and output terminals of the bidirectional DC-DC converter to turn on the switching operation in hardware when an error occurs By turning off (Turn OFF), it is possible to turn off the switching operation even when a malfunction occurs in software and the primary protection fails, thereby improving stability.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and those skilled in the art to which the art belongs can make various modifications and other equivalent embodiments therefrom. I will understand.

Therefore, the true technical protection scope of the present invention will be defined by the claims below.

100: control unit 11: power unit
12: voltage detection unit 13: MCU
14: communication unit 15: current detection unit
200: power conversion unit 20: LV protective switch unit
21: HV protective switch unit 24: current measuring unit
25: signal amplifier 26: comparator
27: latch circuit portion 28: power supply IC
29: protective switch driver I: protective circuit
SW1: first switch SW2: second switch
SW DRV: first switch and second switch driver

Claims (1)

A power conversion unit including a plurality of switches to perform voltage conversion in both directions between the low voltage battery and the high voltage battery; And
Detects whether an overcurrent occurs by comparing the current value flowing through the power converter with a reference current value, and determines that an overcurrent has occurred when the detected current value is greater than or equal to the reference current value. Control unit for turning off (Turn Off); including,
The power converter,
A protection switch unit for blocking the flow of current when an overcurrent occurs; And
And a protection circuit unit configured to stop the operation of the power conversion unit by turning off the protection switch unit when all switches including the protection switch unit of the power conversion unit are not turned off when the overcurrent occurs.
The protection circuit unit,
A signal amplifier for amplifying the voltage of the current measuring unit measuring the current of the power converter;
A comparator for comparing an output voltage of the signal amplifier and a preset reference voltage;
A latch circuit unit configured to output an output signal for changing an enable signal of a power supply IC according to a comparison result of the comparator; And
And a protection switch unit driver for turning on or off the protection switch unit by using a power source of the power supply IC.
The circuit configuration of the power converter is an interleaved structure formed by connecting a plurality of in parallel according to the capacity of the bidirectional DC-DC converter,
The protection circuit unit,
As a result of comparing the comparator, when the output voltage of the signal amplifier is equal to or greater than the reference voltage, the latch operation occurs in the latch circuit to make the enable signal of the power supply IC low.
The control unit,
Understand the condition of the low voltage battery and the high voltage battery, and based on the state of the low voltage battery and the high voltage battery Buck mode for stepping down from the high voltage battery to the low voltage battery and boost for boosting the low voltage battery to the high voltage battery ( A plurality of switches of the power conversion unit to turn on or off to perform the Boost mode to protect the bidirectional DC-DC converter, characterized in that the voltage of each of the low voltage battery and high voltage battery to reach the target voltage .

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