JPWO2020022003A1 - Electronic control device - Google Patents

Abstract

Provided is an electronic control device capable of reducing the current supplied from the battery while the engine is stopped. In the engine operating state, the switching element (SW1) and the switching element (SW3) are turned on, the switching element (SW2) and the switching element (SW4) are turned off, and the battery (1) and the load (6) are passed through the DCDC converter (5). ) Is directly connected, the battery voltage (Vbat) of the battery (1) is applied to the load (6), and in the engine stopped state, the switching element (SW1) and the switching element (SW2) are turned on, the switching element (SW3), The state in which the switching element (SW4) is turned off, the state in which the switching element (SW1) and the switching element (SW2) are turned off, and the state in which the switching element (SW3) and the switching element (SW4) are turned on are alternately repeated, and the DCDC converter (5) ), The voltage generated based on the charge pump operation is applied to the load (6).

Description

The present invention relates to an electronic control unit (Electronic Control Unit: hereinafter referred to as an ECU).

In the automobile industry, electronic control of vehicles is progressing in order to respond to stricter environmental and exhaust regulations, and the number of control devices installed in vehicles is also increasing. By the way, in the specifications required for the ECU, there is a function that the operation must be continued even when the engine is stopped. For example, a backup function using RAM (Random access memory), a wakeup function using CAN (Control Area Network) communication, and a timer counter function can be mentioned.

These electric powers are supplied from the in-vehicle battery, but the battery cannot be charged while the engine is stopped. Therefore, if the total current consumption is large, there is a concern that a vehicle starting failure may occur due to a dead battery. In order to prevent such an event, it is required to reduce the battery current consumption when the engine is stopped.

Generally, a circuit configuration is used in which a DCDC converter is mounted between the battery and the internal load of the ECU to reduce current consumption. In the engine operating state, a current of several hundred mA can flow, but in the engine stopped state, the DCDC converter driving element is intermittently operated to reduce the current consumption.

In the case of such a circuit configuration, the voltage ripple request does not change between the engine stopped state and the operating state, and even if the intermittent operation is used, the obtained frequency reduction effect is reduced. Further, in order to pass a current of several hundred mA, for example, a semiconductor element having a large size such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) must be used, which requires a large drive current.

According to the technique described in Patent Document 1, by combining the series regulator circuit and the charge pump circuit, even if the power supply fluctuates, the power efficiency is optimized at low cost. In the technique described in Patent Document 1, when the input voltage is lower than the load allowable voltage, the MOSFET used for the series regulator control is turned on to supply power only by the conduction loss, and the input voltage is higher than the load allowable voltage. If it is too high, operate it as a series regulator. The charge pump circuit is used to generate the gate drive voltage of the MOSFET in any state.

Japanese Unexamined Patent Publication No. 2003-108243

However, in the technique described in Patent Document 1, the power efficiency can be optimized even if the power supply fluctuates, but there is no idea such as lowering the current consumption of the battery while the engine is stopped.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electronic control device capable of reducing the current supplied from the battery while the engine is stopped.

In order to achieve the above object, the electronic control device according to the first aspect includes a DCDC converter provided between the power supply terminal and the load, and the DCDC converter does not perform switching operation in the engine operating state and the load is not operated. A voltage is applied to the load, and when the engine is stopped, a voltage is applied to the load based on the switching operation.

According to the present invention, it is possible to provide an electronic control device capable of reducing the current supplied from the battery while the engine is stopped.

FIG. 1 is a block diagram showing a configuration of an electronic control device according to the first embodiment. FIG. 2 is a block diagram showing the configuration of the DCDC converter of FIG. FIG. 3 is a diagram showing a waveform at the time of switching between the battery connection and the switching operation of the DCDC converter of FIG. FIG. 4 is a diagram showing a waveform during the switching operation of the DCDC converter of FIG. FIG. 5 is a block diagram showing a configuration of a DCDC converter applied to the electronic control device according to the second embodiment. FIG. 6 is a diagram showing a waveform at the time of switching between the regulator operation and the switching operation of the DCDC converter of FIG. FIG. 7 is a block diagram showing a configuration of an electronic control device according to a third embodiment.

The embodiment will be described with reference to the drawings. It should be noted that the embodiments described below do not limit the invention according to the claims, and all of the elements and combinations thereof described in the embodiments are indispensable for the means for solving the invention. Not necessarily.

FIG. 1 is a block diagram showing a configuration of an electronic control device according to the first embodiment.
In FIG. 1, the ECU 2 includes a power supply terminal 3, an IC control power supply 4, a DCDC converter 5, and a load 6.

The power supply terminal 3 is connected to the battery 1. In the operating state of the engine, the battery voltage Vbat of the battery 1 is, for example, 12V. The DCDC converter 5 is connected between the power supply terminal 3 and the load 6. At this time, the input side of the DCDC converter 5 is connected to the power supply terminal 3 and the IC control power supply 4, and the output side of the DCDC converter 5 is connected to the load 6.

The ECU 2 electronically controls the in-vehicle device of the vehicle. The in-vehicle device is, for example, a power device, a steering device, a braking device, or a transmission device. An engine or an electric motor can be used as the power unit of the vehicle. The in-vehicle device may be a headlight, a power window, a door lock, an electric seat, an instrument panel, or the like.

The IC control power supply 4 detects the battery voltage Vbat of the battery 1 and drives and controls the DCDC converter 5. The DCDC converter 5 applies a voltage to the load 6 without switching operation in the engine operating state, and applies a voltage to the load 6 based on the switching operation in the engine stopped state. For example, in the operating state of the engine, the DCDC converter 5 applies the battery voltage Vbat to the load 6.

The drive frequency of the switching operation in the engine stopped state is 300 Hz or less. Particularly preferably, the drive frequency of the switching operation in the engine stopped state is in the range of 100 to 300 Hz. Further, the output voltage Vout of the DCDC converter has a higher ripple in the engine stopped state than in the engine operating state. At this time, the ripple of the output voltage Vout in the engine stopped state is in the range of 1 to 2V. The ripple frequency of the output voltage Vout is equal to the drive frequency of the switching operation. As the DCDC converter 5, a step-down charge pump can be used.

The type and form of the load 6 are not specified. The load 6 may be an internal load of the ECU 2 or an external load of the ECU 2. FIG. 1 shows an example in which the load 6 includes a communication wakeup unit 7, a series regulator 8, 10, a RAM backup power supply 9, and a timer 11.

The communication wakeup unit 7 activates a communication function such as CAN. The RAM backup power supply 9 backs up the RAM power supply. The RAM backup power supply 9 operates at, for example, 5V. The timer 11 measures the engine stop time. The timer 11 operates at, for example, 3.3 V. The series regulator 8 lowers the battery voltage Vbat to the guaranteed operation voltage of the RAM backup power supply 9. The series regulator 10 lowers the battery voltage Vbat to the operation guaranteed voltage of the timer 11.

Here, the DCDC converter 5 can reduce the current Ibat supplied from the battery 1 while the engine is stopped by applying a voltage to the load 6 based on the switching operation in the engine stopped state. Therefore, even when the battery 1 cannot be charged while the engine is stopped, it is possible to prevent the occurrence of a vehicle starting problem due to the battery running out. Further, the DCDC converter 5 can reduce the loss and noise associated with the switching operation by applying a voltage to the load 6 without performing the switching operation in the engine operating state.

FIG. 2 is a block diagram showing the configuration of the DCDC converter of FIG.
In FIG. 2, the DCDC converter 5 includes terminals N1 to N4, switching elements SW1 to SW4, a charge pump control unit 12, and a voltage detection circuit 13. MOSFETs or bipolar transistors can be used as the switching elements SW1 to SW4. The switching elements SW1 to SW4 may be IGBTs (Insulated Gate Bipolar Transistors).

The charge pump control unit 12 switches between the operation of applying the battery voltage Vbat to the load 6 and the switching operation of the switching elements SW1 to SW4 based on the ignition key signal Sigma and the detection value of the voltage detection circuit 13. In the switching operation of the switching elements SW1 to SW4, the switching elements SW1 to SW4 are switched on and off based on the threshold value Vth. The voltage detection circuit 13 detects the output voltage Vout of the DCDC converter 5. The voltage detection circuit 13 can use a comparator that only detects a low threshold of the output voltage Vout.

The switching element SW1 is connected to the terminal N1. The switching element SW3 is connected to the switching element SW1. The switching element SW2 is connected to the switching element SW3. The switching element SW4 is connected to the switching element SW2.

The connection points of the switching elements SW1 and SW3 are connected to the terminal N2. The connection points of the switching elements SW2 and SW4 are connected to the terminal N3. The connection points of the switching elements SW2 and SW3 are connected to the terminal N4. A capacitor C1 is connected between terminals N2 and N3. A capacitor C2 and a load 6 are connected to the terminal N4. The capacitors C1 and C2 can be externally attached to the DCDC converter 5.

When the ignition key is turned on, the ignition key signal Sigma becomes high level and the engine is in operation. At this time, the charge pump control unit 12 turns on the switching elements SW1 and SW3 and turns off the switching elements SW2 and SW4. In this case, the battery 1 of FIG. 1 and the load 6 are directly connected via the DCDC converter 5, and the battery voltage Vbat of the battery 1 is applied to the load 6. At this time, a current path L1 of terminal N1 → switching element SW1 → switching element SW3 → terminal N4 is formed in the DCDC converter 5. In this case, since the switching elements SW1 to SW4 do not perform the switching operation, the loss and noise associated with the switching operation can be reduced.

When the ignition key is turned off, the ignition key signal Sigma becomes low level and the engine is stopped. At this time, the charge pump control unit 12 alternately alternates between a state in which the switching elements SW1 and SW2 are turned on and the switching elements SW3 and SW4 are turned off and a state in which the switching elements SW1 and SW2 are turned off and the switching elements SW3 and SW4 are turned on. repeat. In this case, the voltage generated based on the charge pump operation of the DCDC converter 5 is applied to the load 6. At this time, the current path L2 of terminal N1 → switching element SW1 → terminal N2 → capacitor C1 → terminal N3 → switching element SW2 → terminal N4 and switching element SW4 → terminal N3 → capacitor C1 → terminal N2 → switching element SW3 → terminal N4 The current path L3 is alternately formed in the DCDC converter 5. As a result, the current Ibat supplied from the battery 1 in FIG. 1 can be reduced, and even when the battery 1 cannot be charged while the engine is stopped, it is possible to prevent the occurrence of a vehicle starting problem due to the dead battery. Can be done.

One of the forms of the DCDC converter is a switching regulator using an inductor, but a large inductance value is required to reduce the current ripple, which causes an increase in cost. On the other hand, in the present embodiment, a circuit using a charge pump, which is one of the forms of the DCDC converter 5 suitable for applications with a small output current, can be used, and cost reduction can be achieved.

The switching elements SW1 to SW4 can have a sufficiently high on-resistance that the power consumption does not exceed the permissible loss in the engine operating state and the switching operation failure due to the voltage drop does not occur in the engine stopped state. For example, when the assumed load current is 200 to 300 μA, the on-resistance of the switching elements SW1 to SW4 can be set within the range of 100 to 300Ω. As a result, the size of a semiconductor switch such as a MOSFET used for the switching elements SW1 to SW4 can be reduced, and the current required for gate driving can be reduced.

FIG. 3 is a diagram showing a waveform at the time of switching between the battery connection and the switching operation of the DCDC converter of FIG.
In FIG. 3, in the engine operating state when the ignition key signal Sigma is at a high level, the current consumption of the load 6 is large, so that there is a concern that loss and noise may increase as the operating frequency of the charge pump control unit 12 increases. Therefore, the charge pump control unit 12 connects the battery 1 and the load 6 by turning on the switching elements SW1 and SW3 and turning off the switching elements SW2 and SW4. At this time, the output voltage Vout of the DCDC converter 5 becomes substantially equal to the battery voltage Vbat. Specifically, the output voltage Vout of the DCDC converter 5 is a value obtained by subtracting the voltage drop due to the on-resistance of the switching elements SW1 and SW3 from the battery voltage Vbat. In the engine operating state, the battery voltage Vbat is equal to the battery voltage Vful at the time of full charge.

When the ignition key signal Sign is at a low level and the engine is stopped, the DCDC converter 5 is switched to reduce the current consumption of the battery 1. At this time, the output voltage Vout of the DCDC converter 5 becomes the voltage Vsw in which the battery voltage Vbat is lowered by the operation of the step-down charge pump of the DCDC converter 5. Ripple LP due to the step-down charge pump operation of the DCDC converter 5 is generated at the output voltage Vout of the DCDC converter 5.

Further, in the engine stopped state, the battery current Ibat alternately repeats the output current Iop and the offset current Iof. The offset current If is the current supplied to the IC control power supply 4 of FIG. Therefore, assuming that the battery current Ibat in the engine operating state is Idc, the current supplied from the battery 1 to the load 6 is reduced by Idc-Iop in the engine stopped state as compared with the engine operating state.

When the engine is stopped for a long period of time, the battery voltage Vbat becomes equal to or less than the minimum voltage Vbl required for the switching operation of the DCDC converter 5 due to the total leakage current of the load 6 connected to the battery 1. At this time, the charge pump control unit 12 connects the battery 1 and the load 6 by turning on the switching elements SW1 and SW3 and turning off the switching elements SW2 and SW4, and shifts to the mode in which the standby of the load 6 is continued. In this case, it is also possible to send an alarm signal to inform the user that the battery voltage Vbat has deteriorated significantly.

As described above, according to the first embodiment described above, not only the battery current Ibat in the engine stopped state is reduced by the switching operation of the DCDC converter 5, but also a small-sized MOSFET is used in the low voltage threshold detection comparator. By controlling, the drive current and the control current can be reduced, and the battery current Ibat can be further reduced.

The size of the MOSFET is set to a value at which the voltage drop does not fall below the guaranteed voltage of the load 6 even if the battery current Ibat in the engine operating state flows. Specifically, when the load current in the engine operating state is 5 mA and the guaranteed voltage of the load 6 is 4.5 V, the on-resistance of the MOSFETs that can operate even if the battery voltage Vbat drops to 6 V is 300 Ω in series. Therefore, the MOSFET size is set so that the on-resistance has a maximum of 300Ω. The MOSFET size varies depending on the usage conditions, but it is sufficient that the drive current is sufficiently smaller than the load current. Further, by switching the drive of the DCDC converter 5 according to the vehicle state, it is possible to continue supplying electric power to the load 6.

FIG. 4 is a diagram showing a waveform during the switching operation of the DCDC converter of FIG.
In FIG. 4, the switching elements SW1 to SW4 are switched by detecting a low voltage of the output voltage Vout in order to suppress the current consumption required for controlling the charge pump. Let Vth be the threshold value for low voltage detection.

When the switching elements SW1 and SW2 of FIG. 2 are turned on and the switching elements SW3 and SW4 are turned off, the battery 1 of FIG. 1 charges the capacitors C1 and C2. When the load 6 draws current from the capacitors C1 and C2 and the output voltage Vout reaches the threshold value Vth, the switching elements SW1 and SW2 are turned off and the switching elements SW3 and SW4 are turned on, so that the capacitor C1 charges the capacitor C2. To do.
Hereinafter, the charge pump control unit 12 can keep the output voltage Vout constant by repeating this control. However, ripple LP is generated at the output voltage Vout.

When the output voltage of the DCDC converter 5 is Vout, the output current is Iout, the capacitance of the capacitor C1 is Cin, and the capacitance of the capacitor C2 is Cout, the ripple voltage ripple of the output voltage Vout can be calculated by the equation (1).

Ripple = (Cout x Vout + Cin x (Vbat-Vout)) /
(Cin + Cout) ・ ・ ・ (1)

Further, assuming that the charging time of the capacitor C2 is so small that it can be ignored, the ripple frequency f of the output voltage Vout can be calculated by the equation (2).

f = ((Cin + Cout) x Iout) / Ripple ... (2)

Although the value changes depending on the conditions such as the capacitance of the capacitors C1 and C2 and the output current Iout, the ripple frequency f calculated from the equation (2) in the ECU 2 is a very small value of about several hundred Hz. At this time, the ripple voltage Ripple also becomes a large value of about 1 V, but for example, in the case of a CAN transceiver IC having a wake-up function, since it is originally a function of connecting to the battery voltage, it does not matter.

Here, as can be seen from the equation (2), the output current Iout of the DCDC converter 5 can be reduced by reducing the ripple frequency f. Therefore, the DCDC converter 5 can reduce the output current Iout of the DCDC converter 5 by driving the DCDC converter 5 at a low frequency with the driving frequency of the switching operation set to 300 Hz or less.

On the other hand, when the drive frequency of the switching operation is reduced, the ripple voltage Ripple becomes large. In order to operate the ECU 2 stably in the engine operating state, it is necessary to suppress the ripple voltage Ripple to several tens of mV or less. In order to set the ripple voltage Ripple to several tens of mV, it is necessary to set the drive frequency of the switching operation within the range of 300 to 400 kHz.

On the other hand, in the engine operating state of the present embodiment, the DCDC converter 5 applies the battery voltage Vdat to the load 6 without switching operation. As a result, the DCDC converter 5 can suppress the ripple voltage Ripple to a low level without driving the DCDC converter 5 at a high frequency of 300 to 400 kHz in the engine operating state.

In the first embodiment, the DCDC converter 5 is switched and operated in the engine stopped state, and the battery 1 and the load 6 are directly connected via the DCDC converter 4 in the engine operating state. On the other hand, regarding the wake-up function, which is one of the loads 6, there is an example in which the standby state is performed with a 5V power supply instead of the battery power supply 1 in order to reduce the current consumption. In this case, since the direct connection between the battery 1 and the load 6 of the first embodiment cannot be used, the switching elements SW1 and SW3 of the DCDC converter 5 are used as the series regulator in the second embodiment.

FIG. 5 is a block diagram showing a configuration of a DCDC converter applied to the electronic control device according to the second embodiment.
In FIG. 5, the DCDC converter 15 includes a converter internal control unit 14 instead of the charge pump control unit 12 of the DCDC converter 5 of FIG. The converter internal control unit 14 includes a charge pump control unit 12A and a regulator control unit 12B.

The charge pump control unit 12A switches the switching elements SW1 to SW4 based on the ignition key signal Sigma and the detection value of the voltage detection circuit 13. In the switching operation of the switching elements SW1 to SW4, the switching elements SW1 to SW4 are switched on and off based on the threshold value Vth.

The regulator control unit 12B operates the switching elements SW1 and SW3 as a series regulator based on the ignition key signal Sigma and the detection value of the voltage detection circuit 13. In the series regulator operation of the switching elements SW1 and SW3, the semiconductor switch used for the switching elements SW1 and SW3 is half-on. Half-on is a state in which the channel of the semiconductor switch is maintained at an intermediate potential between on and off.

In the engine operating state, the regulator control unit 12B operates the DCDC converter 15 as a series regulator by half-oning the switching elements SW1 and SW3 and turning off the switching elements SW2 and SW4. In the series regulator operation, the regulator control unit 12B may turn on the switching element SW1 and half-on the switching element SW3, or half-on the switching element SW1 and turn on the switching element SW3.

In this case, the battery 1 and the load 6 of FIG. 1 are connected via the switching elements SW1 and SW3, and a voltage obtained by subtracting the voltage drop due to the switching elements SW1 and SW3 from the battery voltage Vbat of the battery 1 is applied to the load 6. .. At this time, a current path L1 of terminal N1 → switching element SW1 → switching element SW3 → terminal N4 is formed in the DCDC converter 15.

When the engine is stopped, the charge pump control unit 12A operates in the same manner as the charge pump control unit 12 of FIG.

Here, regardless of whether the ignition key is on or off, it is possible to always operate the DCDC converter 15 to supply a 5V voltage to the load 6, but in order to reduce the power consumption of the control circuit, the DCDC converter 5 is used. Since it is controlled by low voltage detection of the output voltage Vout, a large ripple voltage is generated. The battery voltage Vbat is not constant in vehicle operation, and in particular, when a large voltage fluctuation such as a dump surge occurs, the ripple voltage Ripple of the output voltage Vout increases to 16 V or more from the equation (2), and the load 6 May cause element destruction. By adding the regulator control unit 12B and diverting the circuit of the DCDC converter 5, the cost of the DCDC converter 15 can be reduced. If the ignition key is off, the vehicle is stopped and no power fluctuations occur.

FIG. 6 is a diagram showing a waveform at the time of switching between the regulator operation and the switching operation of the DCDC converter of FIG.
In FIG. 6, in the engine operating state when the ignition key signal Sigma is at a high level, there is no demand for reducing the battery current consumption due to the alternator drive, and the voltage fluctuation of the battery 1 is large. Therefore, the regulator control unit 12B controls the switching elements SW1 and SW3 as a series regulator to supply electric power to the load 6. At this time, the output voltage Vout of the DCDC converter 5 is set to the regulator voltage Vreg. The regulator voltage Vreg can be set to the guaranteed operation voltage of the load 6. The battery current Ibat in the engine operating state is the sum of the offset current If supplied to the IC control power supply 4 of FIG. 1 and the current supplied to the load 6 when the regulator of the DCDC converter 5 is operating.

When the ignition key signal Sign is at a low level and the engine is stopped, the DCDC converter 5 is switched to reduce the current consumption of the battery 1.

When the engine is stopped for a long period of time, the battery voltage Vbat becomes equal to or less than the minimum voltage Vbl required for the switching operation of the DCDC converter 5 due to the total leakage current of the load 6 connected to the battery 1. At this time, the regulator control unit 12B controls the switching elements SW1 and SW3 as a series regulator, connects the battery 1 and the load 6 via the switching elements SW1 and SW3, and shifts to a mode in which the standby of the load 6 is continued. In this case, it is also possible to send an alarm signal to inform the user that the battery voltage Vbat has deteriorated significantly.

In the first and second embodiments described above, the configuration in which the output of the DCDC converter 5 is connected to the internal load has been described, but the output of the DCDC converter 5 is connected to the external load to reduce the current consumption of the entire vehicle. You may try to plan.

FIG. 7 is a block diagram showing a configuration of an electronic control device according to a third embodiment.
In FIG. 7, the output terminal 16 is added to the ECU 2 of FIG. 2 in the ECU 2A. The output terminal 16 is connected to the output of the DCDC converter 5. Further, the output terminal 16 is connected to the ECUs 2B and 2C. The ECUs 2B and 2C can omit the IC control power supply and the DCDC converter. At this time, power can be supplied to the ECUs 2B and 2C from the DCDC converter 6 of the ECU 2A.

In the first and second embodiments described above, the control current of the DCDC converter 5 can be reduced, but when the ratio of the offset current to the output current is large, the current consumption reduction effect becomes small. By supplying power to the ECUs 2B and 2C outside the ECU 2A from the DCDC converter 5, the ratio of the offset current to the output current can be reduced, and the battery current consumption can be reduced at low cost.

The embodiments and various variations described above are merely examples, and the present invention is not limited to these contents as long as the features of the invention are not impaired.

1 battery, 2 ECU, 3 power supply terminal, 4 IC control power supply, 5 DCDC converter, 6 load, 7 communication wakeup section, 8, 10 series regulator, 9 RAM backup power supply, 11 timer

Claims (15)

Equipped with a DCDC converter provided between the power supply terminal and the load
The DCDC converter is an electronic control device that applies a voltage to the load without switching operation in the engine operating state, and applies a voltage to the load based on the switching operation in the engine stopped state. The electronic control device according to claim 1, wherein the drive frequency of the switching operation is 300 Hz or less. The electronic control device according to claim 1, wherein the DCDC converter applies a battery voltage to the load in the operating state of the engine. The electronic control device according to claim 1, wherein the DCDC converter is a step-down charge pump. The switching element included in the step-down charge pump has an on-resistance in which the power consumption does not exceed the permissible loss in the engine operating state and the switching operation failure due to the voltage drop does not occur in the engine stopped state. Electronic control device The electronic control device according to claim 4, wherein the step-down charge pump applies the battery voltage to the load when the battery voltage drops below a threshold value in the engine stopped state. The electronic control device according to claim 1, wherein the DCDC converter applies a battery voltage dropped based on a series regulator operation to the load in the engine operating state. The electronic control device according to claim 7, wherein the DCDC converter is operated by the series regulator by half-oning the semiconductor switch included in the DCDC converter. The electronic control device according to claim 8, wherein the semiconductor switch is a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) or a bipolar transistor. The electronic control device according to claim 1, wherein the output of the DCDC converter is connected to another electronic control device. The electronic control device according to claim 1, wherein the output voltage of the DCDC converter has a higher ripple in the engine stopped state than in the engine operating state. The electronic control device according to claim 11, wherein the ripple of the output voltage in the engine stopped state is in the range of 1 to 2 V. The DCDC converter
With the first switching element
With the second switching element
With the third switching element
Equipped with a fourth switching element
The first switching element is connected to the power supply terminal and
The third switching element is connected to the first switching element, and the third switching element is connected to the first switching element.
The second switching element is connected to the third switching element, and the second switching element is connected to the third switching element.
The fourth switching element is connected to the second switching element, and the fourth switching element is connected to the second switching element.
A first capacitor is connected between the connection point between the first switching element and the third switching element and the connection point between the second switching element and the fourth switching element.
The electronic control device according to claim 1, wherein a second capacitor and the load are connected to a connection point between the second switching element and the third switching element. The DCDC converter
In the engine operating state,
The first state in which the first switching element and the third switching element are turned on and the second switching element and the fourth switching element are turned off is continued.
In the engine stopped state,
A second state in which the first switching element and the second switching element are turned on and the third switching element and the fourth switching element are turned off, and the first switching element and the second switching element are turned off, the third. The electronic control device according to claim 13, wherein the switching element and the third state in which the fourth switching element is turned on are alternately repeated. The electronic control device according to claim 14, wherein the DCDC converter switches from the third state to the second state when the output voltage of the DCDC converter drops below a threshold value.

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