WO2020022003A1

WO2020022003A1 - Electronic control device

Info

Publication number: WO2020022003A1
Application number: PCT/JP2019/026409
Authority: WO
Inventors: 泰志杉山; 純之荒田; 隆介佐原; 祐輔山本; 駿太戸松
Original assignee: 日立オートモティブシステムズ株式会社
Priority date: 2018-07-25
Filing date: 2019-07-03
Publication date: 2020-01-30
Also published as: JPWO2020022003A1

Abstract

Provided is an electronic control device capable of reducing the current supplied from a battery while an engine is stopped. While the engine is in operation, a switching element (SW1) and a switching element (SW3) are turned on, a switching element (SW2) and a switching element (SW4) are turned off, a battery (1) and a load (6) are directly connected via a DC-DC converter (5), and the battery voltage (Vbat) of the battery (1) is applied to the load (6). While the engine is in a stopped state, the state in which the switching element (SW1) and the switching element (SW2) are on and the switching element (SW3) and the switching element (SW4) are off and the state in which the switching element (SW1) and the switching element (SW2) are off and the switching element (SW3) and the switching element (SW4) are on are alternately repeated, and the voltage generated on the basis of the charge pump operation of the DC-DC converter (5) is applied to the load (6).

Description

Electronic control unit

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

In the automotive industry, electronic control of vehicles is progressing to respond to stricter environmental and emission regulations, and the number of control devices mounted on 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 a RAM (Random Access Memory), a wake-up function using CAN (Controller Area Network) communication, and a timer counter function can be given.

These powers are supplied from the on-board battery, but the battery cannot be charged while the engine is stopped. For this reason, if the sum of the consumed currents is large, there is a concern that a vehicle starting malfunction due to a dead battery may occur. In order to prevent such an event, it is required to reduce the current consumption of the battery when the engine is stopped.

Generally, a circuit configuration is used in which a DCDC converter is mounted between a battery and an internal load of an 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 operated intermittently to reduce current consumption.

In the case of such a circuit configuration, the voltage ripple requirement does not change between the engine stopped state and the operating state, and the obtained frequency reduction effect is reduced even if the intermittent operation is used. In order to pass a current of several hundred mA, a large-sized semiconductor element such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) must be used, and a large driving current is required.

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

JP 2003-108243 A

However, with the technology described in Patent Document 1, power efficiency can be optimized even when power supply fluctuations occur, but there was no idea of reducing the current consumption of the battery while the engine was 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 a current supplied from a battery while an engine is stopped.

To achieve the above object, an electronic control device according to a first aspect includes a DCDC converter provided between a power supply terminal and a load, and the DCDC converter does not perform a switching operation in an engine operating state and does not perform the switching operation. And when the engine is stopped, a voltage is applied to the load based on a 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 illustrating a configuration of the electronic control device according to the first embodiment. FIG. 2 is a block diagram showing a configuration of the DCDC converter of FIG. FIG. 3 is a diagram showing waveforms 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 waveforms during the switching operation of the DCDC converter of FIG. FIG. 5 is a block diagram illustrating a configuration of a DCDC converter applied to the electronic control device according to the second embodiment. FIG. 6 is a diagram showing waveforms 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 illustrating a configuration of an electronic control device according to the 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 the elements and combinations thereof described in the embodiments are essential for solving the invention. Not necessarily.

FIG. 1 is a block diagram illustrating a configuration of the electronic control device according to the first embodiment.
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 engine operating state, 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.

(4) The ECU 2 electronically controls on-vehicle devices of the vehicle. The on-vehicle device is, for example, a power device, a steering device, a braking device, or a transmission. An engine or an electric motor can be used as a vehicle power unit. The vehicle-mounted 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 controls the drive of the DCDC converter 5. The DCDC converter 5 applies a voltage to the load 6 without performing a 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 engine operating state, the DCDC converter 5 applies the battery voltage Vbat to the load 6.

駆動 The driving frequency of the switching operation when the engine is stopped is 300 Hz or less. Particularly preferably, the driving frequency of the switching operation when the engine is stopped 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 stop state than in the engine operation 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 driving 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 may be an external load of the ECU 2. FIG. 1 shows an example in which the load 6 includes a communication wake-up unit 7,

series regulators

8, 10, a RAM backup power supply 9, and a timer 11.

(4) The communication wake-up 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, 3.3V. The series regulator 8 lowers the battery voltage Vbat to the operation guarantee voltage of the RAM backup power supply 9. The series regulator 10 lowers the battery voltage Vbat to the operation guarantee 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 when the engine is stopped. For this reason, even when the battery 1 cannot be charged while the engine is stopped, it is possible to prevent the occurrence of a trouble in starting the vehicle due to the dead battery. Further, the DCDC converter 5 can reduce the loss and noise accompanying the switching operation by applying the voltage to the load 6 without performing the switching operation in the engine operating state.

FIG. 2 is a block diagram showing a configuration of the DCDC converter of 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. As the switching elements SW1 to SW4, MOSFETs or bipolar transistors can be used. 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 Sig and the detection value of the voltage detection circuit 13. In the switching operation of the switching elements SW1 to SW4, each of the switching elements SW1 to SW4 is switched on and off based on the threshold value Vth. Voltage detection circuit 13 detects output voltage Vout of DCDC converter 5. The voltage detection circuit 13 can use a comparator that detects only the low threshold of the output voltage Vout.

(4) 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.

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

(4) When the ignition key is turned on, the ignition key signal Sig goes high, and the engine operates. 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 the terminal N1, the switching element SW1, the switching element SW3, and the 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, it is possible to reduce the loss and noise accompanying the switching operation.

(4) When the ignition key is turned off, the ignition key signal Sig goes low and the engine stops. At this time, the charge pump control unit 12 alternately turns on the switching elements SW1 and SW2 and turns off the switching elements SW3 and SW4, and turns on the switching elements SW1 and SW2 and turns on the switching elements SW3 and SW4. repeat. In this case, the voltage generated based on the charge pump operation of DCDC converter 5 is applied to load 6. At this time, a 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 And the current path L3 is alternately formed in the DCDC converter 5. Thus, the current Ibat supplied from the battery 1 in FIG. 1 can be reduced, and even if the battery 1 cannot be charged while the engine is stopped, it is possible to prevent the occurrence of a trouble in starting the vehicle due to a dead battery. Can be.

スイッチング One type of DC-DC converter is a switching regulator using an inductor. However, a large inductance value is required in order to reduce current ripple, resulting in 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 having a small output current, can be used, and cost can be reduced.

(4) The switching elements SW1 to SW4 can have a sufficiently high on-resistance that the power consumption does not exceed the allowable 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 in 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 drive can be reduced.

FIG. 3 is a diagram showing waveforms 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 Sig is at the high level, the current consumption of the load 6 is large, and there is a concern that the loss and noise increase with the increase in the operating frequency of the charge pump control unit 12. For this reason, 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 has 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 Vfull at the time of full charge.

(4) When the ignition key signal Sig is at the low level and the engine is stopped, the DCDC converter 5 performs a switching operation 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 obtained by lowering the battery voltage Vbat by the step-down charge pump operation of the DCDC converter 5. A ripple LP due to the step-down charge pump operation of the DCDC converter 5 occurs in the output voltage Vout of the DCDC converter 5.

(5) In the engine stop state, the battery current Ibat alternates between the output current Iop and the offset current Iof. The offset current Iof is a current supplied to the IC control power supply 4 in 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 in the engine stopped state is smaller by Idc-Iop than in the engine operating state.

When the engine stop state continues for a long time, the battery voltage Vbat falls below the minimum voltage Vbl required for the switching operation of the DCDC converter 5 due to the total leak 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 a mode in which the standby of the load 6 is continued. In this case, an alarm signal can be transmitted to inform the user that the battery voltage Vbat has significantly deteriorated.

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

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

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

When the switching elements SW1 and SW2 in FIG. 2 are turned on and the switching elements SW3 and SW4 are turned off, the battery 1 in 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 capacitor C1 charges the capacitor C2 by turning off the switching elements SW1 and SW2 and turning on the switching elements SW3 and SW4. I do.
Hereinafter, the charge pump control unit 12 can keep the output voltage Vout constant by repeating this control. However, a ripple LP occurs in 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 Vripple of the output voltage Vout can be calculated by Expression (1).

Vripple = (Cout × Vout + Cin × (Vbat−Vout)) /
(Cin + Cout) (1)

{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 equation (2).

f = ((Cin + Cout) × Iout) / Vripple (2)

(4) Although the value changes depending on conditions such as the capacitances 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 Vripple also has a large value of about 1 V. However, for example, in the case of a CAN transceiver IC having a wake-up function, there is no problem because the function is originally connected to the battery voltage.

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 switching operation at a low frequency of 300 Hz or less.

{On the other hand, when the drive frequency of the switching operation is reduced, the ripple voltage Vripple increases. In order to operate the ECU 2 stably in the engine operating state, it is necessary to suppress the ripple voltage Vripple to several tens mV or less. In order to set the ripple voltage Vripple to several tens of mV, it is necessary to set the driving frequency of the switching operation within a 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 performing the switching operation. This allows the DCDC converter 5 to keep the ripple voltage Vripple low without driving the high frequency of 300 to 400 kHz in the engine operating state.

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

FIG. 5 is a block diagram illustrating a configuration of a DCDC converter applied to the electronic control device according to the second embodiment.
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. Converter internal control section 14 includes charge pump control section 12A and regulator control section 12B.

(4) The charge pump control unit 12A performs switching operation of the switching elements SW1 to SW4 based on the ignition key signal Sig and the detection value of the voltage detection circuit 13. In the switching operation of the switching elements SW1 to SW4, each of the switching elements SW1 to SW4 is switched on and off based on the threshold value Vth.

(4) The regulator control unit 12B causes the switching elements SW1 and SW3 to operate as a series regulator based on the ignition key signal Sig and the detection value of the voltage detection circuit 13. In the series regulator operation of the switching elements SW1 and SW3, the semiconductor switches used for the switching elements SW1 and SW3 are turned on half. 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 causes the DCDC converter 15 to operate as a series regulator by half-turning on 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, turn on the switching element SW3 half-on, or turn on the switching element SW1 and turn on the switching element SW3.

In this case, the battery 1 of FIG. 1 and the load 6 are connected via the switching elements SW1 and SW3, and a voltage obtained by subtracting the voltage drop by 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 the terminal N1, the switching element SW1, the switching element SW3, and the terminal N4 is formed in the DCDC converter 15.

In the engine stop state, the charge pump control unit 12A operates in the same manner as the charge pump control unit 12 in FIG.

Here, irrespective of whether the ignition key is on or off, the DCDC converter 15 can always be operated to supply a 5 V voltage to the load 6, but the DCDC converter 5 is required to reduce the power consumption of the control circuit. , The output voltage Vout is controlled by detecting a low voltage, so that a large ripple voltage is generated. The battery voltage Vbat is not constant during the operation of the vehicle. In particular, when a large voltage fluctuation such as a dump surge occurs, from equation (2), the ripple voltage Vripple of the output voltage Vout increases to 16 V or more, and the load 6 This may cause device 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 turned off, the vehicle is at a stop, and no power fluctuation occurs.

FIG. 6 is a diagram showing waveforms 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 Sig is at the high level, there is no request for reduction of the battery current consumption with the alternator driving, and the voltage fluctuation of the battery 1 is large. For this reason, the regulator control unit 12B controls the switching elements SW1 and SW3 as a series regulator and supplies 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 operation guarantee voltage of the load 6. The battery current Ibat in the engine operating state is the sum of the offset current Iof supplied to the IC control power supply 4 in FIG. 1 and the current supplied to the load 6 when the DCDC converter 5 operates the regulator.

(4) When the ignition key signal Sig is at the low level and the engine is stopped, the DCDC converter 5 performs a switching operation to reduce the current consumption of the battery 1.

When the engine stop state continues for a long time, the battery voltage Vbat falls below the minimum voltage Vbl required for the switching operation of the DCDC converter 5 due to the total leak 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 to 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, an alarm signal can be transmitted to inform the user that the battery voltage Vbat has significantly deteriorated.

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

FIG. 7 is a block diagram illustrating a configuration of an electronic control device according to the third embodiment.
7, the ECU 2A has an output terminal 16 added to the ECU 2 of FIG. The output terminal 16 is connected to the output of the DCDC converter 5. 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. However, when the ratio of the offset current to the output current is large, the effect of reducing the current consumption is reduced. By supplying power from the DCDC converter 5 to the

ECUs

2B and 2C outside the ECU 2A, the ratio of the offset current to the output current can be reduced, and the battery can be reduced in current consumption at low cost.

The embodiments and various modifications 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 terminal, 4 IC control power, 5 DCDC converter, 6 load, 7 communication wake-up unit, 8, 10 series regulator, 9 RAM backup power, 11 timer

Claims

A DCDC converter provided between the power supply terminal and the load;
An electronic control device, wherein the DCDC converter applies a voltage to the load without performing a switching operation in an engine operating state, and applies a voltage to the load based on the switching operation in an engine stopped state.
The electronic control device according to claim 1, wherein the driving 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 engine operating state.
The electronic control device according to claim 1, wherein the DCDC converter is a step-down charge pump.
5. The switching element according to claim 4, wherein the switching element included in the step-down charge pump has an on-resistance such that power consumption does not exceed an allowable loss in the engine operating state and a switching operation failure due to a voltage drop does not occur in the engine stopped state. 6. Electronic control unit
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.
8. The electronic control device according to claim 7, wherein the DCDC converter operates as the series regulator by half-turning on a semiconductor switch included in the DCDC converter.
9. The electronic control device according to claim 8, wherein the semiconductor switch is a MOSFET (Metal Oxide Semiconductor 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.
2. The electronic control device according to claim 1, wherein the output voltage of the DCDC converter is higher 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 a range of 1 to 2V.
The DCDC converter comprises:
A first switching element;
A second switching element;
A third switching element;
A fourth switching element,
The first switching element is connected to the power terminal,
The third switching element is connected to the first switching element;
The second switching element is connected to the third switching element;
The fourth switching element is connected to the second switching element;
A first capacitor is connected between a connection point between the first switching element and the third switching element and a 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 comprises:
In the engine operating state,
A 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,
In the engine stopped state,
A second state in which the first switching element and the second switching element are turned on, the third switching element and the fourth switching element are turned off, and a state in which the first switching element and the second switching element are turned off; 14. The electronic control device according to claim 13, wherein a switching element and a 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 falls below a threshold value.