Electronic control device

Abstract

To suppress erroneous operation.SOLUTION: An electronic control device includes: a first switching element 21; a second switching element 22; and control sections 51, 52, 61, 62, 71, 72, 81, 82 controlling on-states and off-states of the first switching element 21 and the second switching element 22 and maintaining, at a prescribed voltage, a voltage between a first terminal D1 and a control terminal G1 at the first switching element 21 and a voltage between a first terminal D2 and a control terminal G2 at the second switching element 22. The control sections 51, 52, 61, 62, 71, 72, 81, 82, even when one switching element of the first switching element 21 and the second switching element 22 is an on-state and the other switching element is an off-state, increase a brake voltage of the other switching element's braking higher than a surge voltage generated at one switching element's off-state.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an electronic control device having a plurality of switching elements.

Background Art

[0002] Conventionally, for example, Patent Document 1 has proposed an electronic control device including a plurality of switching elements for controlling the current flowing through a load. Specifically, in this electronic control device, each switching element is connected to a common node. Then, each switching element is configured to be switched between an on state in which current flows and an off state in which current is interrupted by inputting a predetermined drive signal. Each switching element is formed of, for example, a MOSFET (abbreviation for Metal Oxide Semiconductor Field Effect Transistor).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In such an electronic control device, for example, when two switching elements are provided, one switching element may be in the on state and the other switching element may be in the off state. And in such an electronic control device, when one switching element in the on state transitions to the off state, a surge voltage is generated if the other switching element is in the off state. In this case, in such an electronic control device, there is a possibility that a malfunction may occur in which the other switching element unexpectedly transitions to the on state due to the surge voltage.

[0005] In view of the above points, an object of the present invention is to provide an electronic control device capable of suppressing malfunction.

Means for Solving the Problems

[0006] Claim 1 for achieving the above object and 6 In a first aspect, an electronic control device in which a first switching element (21) and a second switching element (22) for controlling the current flowing through loads (11, 12, 13) are connected via a common node (N), having a first terminal (D1), a second terminal (S1), and a control terminal (G1) for controlling the current flowing between the first terminal and the second terminal, the first switching element in which the on state in which current flows and the off state in which current is interrupted are controlled by the voltage applied to the control terminal, a second terminal (D2), a second terminal (S2), and a control terminal (G2) for controlling the current flowing between the first terminal and the second terminal, the second switching element in which the on state in which current flows and the off state in which current is interrupted are controlled by the voltage applied to the control terminal, and a control unit (51, 52, 61, 62, 71, 72, 81, 82) for controlling the on state and the off state of the first switching element and the second switching element and maintaining the voltage between the first terminal and the control terminal of the first switching element and the voltage between the first terminal and the control terminal of the second switching element at a predetermined voltage. clamped to a predetermined voltage , Furthermore and. And, In claim 1 When one of the first switching element and the second switching element is in the on state and the other is in the off state (one on state), the control unit the voltage between the first terminal and the control terminal of the other switching element is becomes higher than the surge voltage generated when one of the switching elements becomes the off state clamped to the regulated voltage . Claim 6 is When one of the first switching element and the second switching element is in the on state and the other is in the off state (one on state), the control unit when one switching element is turned off, the voltage between the first terminal and the control terminal of one switching element is clamped to a regulated voltage at which the surge voltage generated is lower than the voltage between the first terminal and the control terminal of the other switching element .

[0007] According to this, when one of the first switching element or the second switching element is in the on state and the other is in the off state, the voltage at which the other switching element breaks is made higher than the surge voltage generated when one switching element turns off. For this reason, it is possible to suppress the occurrence of a malfunction in which the other switching element turns on due to the surge voltage generated when one switching element is turned off.

[0008] Note that the reference numerals in parentheses attached to each component etc. show an example of the correspondence relationship between the component etc. and the specific components etc. described in the embodiments described later.

Brief Description of the Drawings

[0009]

Figure 1

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Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are identical or equivalent to each other will be denoted by the same reference numerals and described together.

[0011] (First Embodiment) The electronic control unit of the first embodiment will be described with reference to the drawings. Note that the electronic control unit of this embodiment is preferably mounted on a vehicle such as an automobile and applied as a device for driving various vehicle-mounted electronic devices.

[0012] As shown in FIG. 1, the electronic control unit of this embodiment controls the currents flowing through the first load 11 and the second load 12, and includes a first switching element 21 and a second switching element 22. The electronic control unit also includes a first main control unit 51, a second main control unit 52, a first sub-control unit 61, a second sub-control unit 62, a first drive circuit 71, a second drive circuit 72, a first break voltage control circuit 81, a second break voltage control circuit 82, etc. And these are appropriately connected by wiring or the like. Although not particularly shown in the drawings, the wiring has an inductance component. Also, hereinafter, the first break voltage control circuit 81 will be simply referred to as the first control circuit 81, and the second break voltage control circuit 82 will be simply referred to as the second control circuit 82.

[0013] The first switching element 21 and the second switching element 22 are composed of, for example, n-channel MOSFETs, and have a three-terminal element configuration including gate electrodes G1 and G2 serving as control terminals, drain electrodes D1 and D2 through which output current flows, and source electrodes S1 and S2. When a voltage higher than the source electrodes S1 and S2 is applied to the drain electrodes D1 and D2 and a voltage equal to or higher than a predetermined threshold voltage is applied to the gate electrodes G1 and G2, the first switching element 21 and the second switching element 22 enter an on state in which current flows. Also, when a voltage lower than the predetermined threshold voltage is applied to the gate electrodes G1 and G2, the first switching element 21 and the second switching element 22 enter an off state in which current is blocked. In the present embodiment, the drain electrodes D1 and D2 correspond to the first terminal, and the source electrodes S1 and S2 correspond to the second terminal.

[0014] Specifically, as will be described later, the first switching element 21 of the present embodiment enters an on state when an H signal as the first drive signal SK1 is output from the first slave control unit 61, and enters an off state when an L signal as the first drive signal SK1 is output from the first slave control unit 61. Similarly, the second switching element 22 enters an on state when an H signal as the second drive signal SK2 is output from the second slave control unit 62, and enters an off state when an L signal as the second drive signal SK2 is output from the second slave control unit 62.

[0015] Note that the first switching element 21 and the second switching element 22 may be composed of an IGBT (abbreviation for Insulated Gate Bipolar Transistor) or the like instead of a MOSFET. When the first switching element 21 and the second switching element 22 are composed of IGBTs, the collector electrode corresponds to the first terminal, and the emitter electrode corresponds to the second terminal.

[0016] The first switching element 21 and the second switching element 22 have their respective drain electrodes D1 and D2 connected to a common node N. And for the first switching element 21, its source electrode S1 is connected to the first load 11. For the second switching element 22, its source electrode S2 is connected to the second load 12. Also, the common node N is connected to the power supply 30. That is, the first switching element 21 and the first load 11 are connected in series with respect to the power supply 30, and the second switching element 22 and the second load 12 are connected in series with respect to the power supply 30.

[0017] Also, in this embodiment, the first switching element 21 and the second switching element 22 are provided with a first diode element 41 and a second diode element 42. The first diode element 41 and the second diode element 42 are arranged such that their cathodes are connected to the drain electrodes D1 and D2 respectively, and their anodes are connected to the source electrodes S1 and S2 respectively. Note that the first diode element 41 may be formed on the semiconductor substrate constituting the first switching element 21, or may be provided as a separate member. Similarly, the second diode element 42 may be formed on the semiconductor substrate constituting the second switching element 22, or may be provided as a separate member.

[0018] The first load 11 and the second load 12 are constituted by, for example, a predetermined circuit element, a resistor having a predetermined resistance value, or the like.

[0019] The first main control unit 51 is constituted by a microcomputer or the like including a CPU and a storage unit such as a ROM, a RAM, and a non-volatile RAM, and is connected to the first sub-control unit 61. Similarly, the second main control unit 52 is constituted by a microcomputer or the like and is connected to the second sub-control unit 62. And the first main control unit 51 and the second main control unit 52 are capable of communicating with each other.

[0020] Note that being able to communicate here may mean that wired communication is possible between the first main control unit 51 and the second main control unit 52, or that wireless communication is possible between the first main control unit 51 and the second main control unit 52. Also, in this embodiment, an example in which the first main control unit 51 and the second main control unit 52 are configured by separate members will be described. However, the first main control unit 51 and the second main control unit 52 may be configured by a common single main control unit, and the main control unit may be connected to the first sub-control unit 61 and the second sub-control unit 62.

[0021] The first main control unit 51 and the second main control unit 52 realize various control operations by the CPU reading a program from the ROM or the non-volatile RAM and executing it. Note that various types of data (for example, initial values, look-up tables, maps, etc.) used during the execution of the program are stored in advance in the ROM or the non-volatile RAM. Also, the storage medium such as the ROM is a non-transitory physical storage medium. The CPU is an abbreviation for Central Processing Unit, the ROM is an abbreviation for Read Only Memory, and the RAM is an abbreviation for Random Access Memory.

[0022] The first main control unit 51 of this embodiment outputs a first drive instruction SA1 to the first sub-control unit 61. Similarly, the second main control unit 52 outputs a second drive instruction SA2 to the second sub-control unit 62. Note that the first drive instruction SA1 and the second drive instruction SA2 are signals of an H signal or an L signal, and the H signal and the L signal are switched by a predetermined timing or a switching command from an external circuit.

[0023] The first sub-control unit 61 is configured by a microcomputer or the like and is connected to the first main control unit 51, the first drive circuit 71, and the first control circuit 81. Similarly, the second sub-control unit 62 is configured by a microcomputer or the like and is connected to the second main control unit 52, the second drive circuit 72, the second control circuit 82, etc. And the first sub-control unit 61 and the second sub-control unit 62 are capable of communicating with each other and can grasp the on state and the off state of the first switching element 21 and the second switching element 22.

[0024] In addition, in this embodiment, an example in which the first slave control unit 61 and the second slave control unit 62 are configured as separate members will be described, but the first slave control unit 61 and the second slave control unit 62 may be configured by a common single slave control unit. Furthermore, the first main control unit 51, the second main control unit 52, the first slave control unit 61, and the second slave control unit 62 may all be configured by a microcomputer or the like integrated into one.

[0025] Then, the first slave control unit 61 outputs a first drive signal SK1 to the first drive circuit 71. Specifically, when an L signal as the first drive instruction SA1 is input from the first main control unit 51, the first slave control unit 61 outputs an L signal as the first drive signal SK1 to the first drive circuit 71. When an H signal as the first drive instruction SA1 is input from the first main control unit 51, the first slave control unit 61 outputs an H signal as the first drive signal SK1 to the first drive circuit 71.

[0026] Also, the first slave control unit 61 outputs a first control signal SB1 to the first control circuit 81. Specifically, when an H signal as the first drive instruction SA1 is input from the first main control unit 51, the first slave control unit 61 outputs an H signal as the first control signal SB1. Also, when the first drive instruction SA1 from the first main control unit 51 has just switched from an H signal to an L signal and the second switching element 22 is in the on state, the first slave control unit 61 outputs an H signal as the first control signal SB1 over the first delay period ta1. When an L signal as the first drive instruction SA1 is input from the first main control unit 51 and the second switching element 22 is in the on state, and during a period different from the first delay period ta1, the first slave control unit 61 outputs an L signal as the first control signal SB1. When an L signal as the first drive instruction SA1 is input from the first main control unit 51 and the second switching element 22 is in the off state, the first slave control unit 61 outputs an H signal as the first control signal SB1. Note that the first delay period ta1 will be described later.

[0027] Similar to the first slave control unit 61, the second slave control unit 62 outputs a second drive signal SK2 to the second drive circuit 72. Specifically, when an L signal as the second drive instruction SA2 is input from the second master control unit 52, the second slave control unit 62 outputs an L signal as the second drive signal SK2 to the second drive circuit 72. When an L signal as the second drive instruction SA2 is input from the second master control unit 52, the second slave control unit 62 outputs an H signal as the second drive signal SK2 to the second drive circuit 72.

[0028] Also, the second slave control unit 62 outputs a second control signal SB2 to the second control circuit 82. Specifically, when an H signal as the second drive instruction SA2 is input from the second master control unit 52, the second slave control unit 62 outputs an H signal as the second control signal SB2. Also, when the second drive instruction SA2 from the second master control unit 52 has just switched from an H signal to an L signal and the first switching element 21 is in the on state, the second slave control unit 62 outputs an H signal as the second control signal SB2 over the second delay period ta2. When an L signal is input as the second drive instruction SA2 from the second master control unit 52 and the first switching element 21 is in the on state, and during a period different from the second delay period ta2, the second slave control unit 62 outputs an L signal as the second control signal SB2. When an L signal is input as the second drive instruction SA2 from the second master control unit 52 and the first switching element 21 is in the off state, the second slave control unit 62 outputs an H signal as the second control signal SB2. The second delay period ta2 will be described later.

[0029] The first drive circuit 71 has a general configuration in the gate drive circuit and is connected to the gate electrode G1. Then, based on the first drive signal SK1 input from the first slave control unit 61, the first drive circuit 71 applies an appropriate gate drive voltage to the gate electrode G1 according to the gate capacitance and output current of the first switching element 21. Specifically, when an H signal is input as the first drive signal SK1 from the first slave control unit 61, the first drive circuit 71 applies a gate drive voltage that turns on the first switching element 21 to the gate electrode G1. Also, when an L signal is input as the first drive signal SK1 from the first slave control unit 61, the first drive circuit 71 applies a gate drive voltage that turns off the first switching element 21 to the gate electrode G1.

[0030] Similarly, the second drive circuit 72 applies an appropriate gate drive voltage to the gate electrode G2 of the second switching element 22 based on the second drive signal SK2 input from the second slave control unit 62. Specifically, when an H signal is input as the second drive signal SK2 from the second slave control unit 62, the second drive circuit 72 applies a gate drive voltage that turns on the second switching element 22 to the gate electrode G2. Also, when an L signal is input as the second drive signal SK2 from the second slave control unit 62, the second drive circuit 72 applies a gate drive voltage that turns off the second switching element 22 to the gate electrode G2.

[0031] Note that the first switching element 21 and the second switching element 22 are composed of MOSFETs, and there is a transition period until the current is completely cut off when switching from the on state to the off state. The first delay period ta1 when switching the first control signal SB1 in the first slave control unit 61 from the H signal to the L signal is set to be equal to or longer than the transition period of the first switching element 21. Similarly, the second delay period ta2 when switching the second control signal SB2 in the second slave control unit 62 from the H signal to the L signal is set to be equal to or longer than the transition period of the second switching element 22. The first delay period ta1 and the second delay period ta2 in this embodiment are values that are derived in advance by experiments or the like, or are defined by the characteristics of the first switching element 21 or the second switching element 22.

[0032] The first control circuit 81 is disposed between the drain electrode D1 and the gate electrode G1 of the first switching element 21. Then, based on the first control signal SB1 from the first slave control unit 61, the first control circuit 81 clamps the voltage VGD1 between the gate and the drain of the first switching element 21 to the first arbitrary voltage or the first adjusted voltage. Similarly, the second control circuit 82 is disposed between the drain electrode D2 and the gate electrode G2 of the second switching element 22. Then, based on the second control signal SB2 from the second slave control unit 62, the second control circuit 82 clamps the voltage VGD2 between the gate and the drain of the second switching element 22 to the second arbitrary voltage or the second adjusted voltage. In this embodiment, the first adjusted voltage is set to be higher than the first arbitrary voltage, and the second adjusted voltage is set to be higher than the second arbitrary voltage.

[0033] Hereinafter, the voltage between the gate and the drain of the first switching element 21 will also be simply referred to as the voltage VGD1 of the first switching element 21. Also, the voltage between the gate and the drain of the second switching element 22 will also be simply referred to as the voltage VGD2 of the second switching element 22. And although not particularly limited, the first control circuit 81 is configured as shown in FIG. 2, for example. The configuration of the second control circuit 82 is the same.

[0034] For example, the first control circuit 81 is configured to include a plurality of Zener diodes 811 and 812 connected between the gate and drain of the first switching element 21, a diode 813, a switch 814, and the like. The plurality of Zener diodes 811 and 812 are connected in series such that the cathodes are connected to the drain electrode D1. In the present embodiment, the first Zener diode 811 and the second Zener diode 812 are arranged in series. The diode 813 is arranged such that the cathode is connected to the gate electrode G1 so as to be able to limit the current flowing from the gate electrode G1 to the drain electrode D1.

[0035] The switch 814 is composed of a MOSFET, an IGBT, or the like. In the present embodiment, the switch 814 is arranged to be connected to the cathode and anode of the first Zener diode 811.

[0036] When the Zener voltages of the first Zener diode 811 and the second Zener diode 812 are Vz and the forward voltage of the diode 813 is Vf, such a first control circuit 81 clamps the voltage VGD1 of the first switching element 21 as follows. That is, when the switch 814 is in the on state, the voltage VGD1 of the first switching element 21 is clamped to Vz + Vf. When the switch 814 is in the off state, the voltage VGD1 of the first switching element 21 is clamped to 2Vz + Vf, which is higher than Vz + Vf. That is, in such a first control circuit 81, by controlling the on and off states of the switch 814, the voltage VGD1 of the first switching element 21 is clamped to two different voltages. And in this first control circuit 81, when the switch 814 is turned on, the voltage VGD1 of the first switching element 21 is clamped to a first arbitrary voltage, and when the switch 814 is turned off, the voltage VGD1 of the first switching element 21 is clamped to a first adjusted voltage higher than the first arbitrary voltage.

[0037] In the above description, an example in which two Zener diodes, i.e., a first Zener diode 811 and a second Zener diode 812, are provided has been described. However, the number of Zener diodes can be appropriately changed according to the voltage to be clamped. Similarly, the location where the switch 814 is disposed can also be appropriately changed according to the voltage to be clamped. Further, the second control circuit 82 has the same configuration as the first control circuit 81 as described above.

[0038] Here, hereinafter, the break voltage (i.e., the voltage between the drain and the source) at which the first switching element 21 breaks is defined as a break voltage VBD1. Further, the voltage between the gate and the source of the first switching element 21 is defined as a voltage VGS1, and hereinafter, it is simply also referred to as the voltage VGS1 of the first switching element 21. Similarly, the break voltage (i.e., the voltage between the drain and the source) at which the second switching element 22 breaks is defined as a break voltage VBD2. Further, the voltage between the gate and the source of the second switching element 22 is defined as a voltage VGS2, and hereinafter, it is simply also referred to as the voltage VGS2 of the second switching element 22.

[0039] When the first control circuit 81 of the present embodiment receives the L signal as the first control signal SB1 from the first slave control unit 61, it clamps the voltage VGD1 of the first switching element 21 to the first adjustment voltage. In this case, when the voltage of the power supply 30 is VB, the first adjustment voltage is set to be equal to or higher than VB + VBD2 because the breakdown voltage of the second switching element 22 is VBD2. That is, although the specific value of the first adjustment voltage will be described later, even if a surge voltage is generated when the second switching element 22 is turned off from the on state when the first switching element 21 is in the off state, the voltage VGS1 of the first switching element 21 is adjusted to be 0. In other words, in the present embodiment, by increasing the breakdown voltage VBD1, even if a surge voltage is generated by turning off the second switching element 22, the voltage VGD1 of the first switching element 21 is clamped at the first adjustment voltage at which the first switching element 21 does not turn on. When the first control circuit 81 is configured as described above, the number of Zener diodes 811 and 812, the location of the switch 814, etc. are adjusted so that the voltage VGD1 of the first switching element 21 becomes equal to or higher than VB + VBD2 when the switch 814 is turned off.

[0040] Similarly, when an L signal as the second control signal SB2 is input from the second slave control unit 62 to the second control circuit 82, the second control circuit 82 clamps the voltage VGD2 of the second switching element 22 to a second regulated voltage. In this case, assuming that the voltage of the power supply 30 is VB, since the breakdown voltage of the first switching element 21 is VBD1, the second regulated voltage is set to be VB + VBD1 or higher. That is, specifically as will be described later, even if a surge voltage is generated when the first switching element 21 is turned off from the on state when the second switching element 22 is in the off state, the voltage VGS2 of the second switching element 22 is adjusted to be 0. In other words, in the present embodiment, by increasing the breakdown voltage VBD2, even if a surge voltage is generated by turning off the first switching element 21, the voltage VGD2 of the second switching element 22 is clamped at a second regulated voltage at which the second switching element 22 does not turn on. When the second control circuit 82 is configured as described above, the number of Zener diodes 811, 812 and the location of the switch 814 are adjusted so that the voltage VGD2 of the second switching element 22 becomes VB + VBD2 or higher when the switch 814 is turned off.

[0041] Further, when an H signal as the first control signal SB1 is input from the first slave control unit 61 to the first control circuit 81, the first control circuit 81 clamps the voltage VGD1 of the first switching element 21 to a first arbitrary voltage. Similarly, when an H signal as the second control signal SB2 is input from the second slave control unit 62 to the second control circuit 82, the second control circuit 82 clamps the voltage VGD2 of the second switching element 22 to a second arbitrary voltage.

[0042] The above is the configuration of the electronic control device in the present embodiment. In the present embodiment, the first main control unit 51, the second main control unit 52, the first slave control unit 61, the second slave control unit 62, the first drive circuit 71, the second drive circuit 72, the first control circuit 81, the second control circuit 82, etc. correspond to the control unit. And the first main control unit 51, the second main control unit 52, the first slave control unit 61, the second slave control unit 62, the first drive circuit 71, the second drive circuit 72, the first control circuit 81, the second control circuit 82, etc. may be integrated.

[0043] Next, the operation of the electronic control device of the present embodiment will be described with reference to FIG. 3. Hereinafter, an example will be described in which, after the second switching element 22 is turned off, the first switching element 21 is turned off, starting from the case where the first switching element 21 and the second switching element 22 are in the on state. Hereinafter, the surge voltage generated when the first switching element 21 is turned off is denoted as VSRG, the voltage of the power supply 30 is denoted as VB, and the breakdown voltage of the first switching element 21 is denoted as VBD1. In this case, the maximum value of the surge voltage VSRG is VB + VBD1. Also, here, the case where the first switching element 21 is in the on state when the second switching element 22 is in the off state corresponds to one of the on states.

[0044] First, before time point T1, since the first drive instruction SA1 and the second drive instruction SA2 are H signals, the first drive signal SK1 and the second drive signal SK2 are H signals. Then, the first switching element 21 and the second switching element 22 are in the on state in which current flows. Also, the first control signal SB1 and the second control signal SB2 are also H signals, the voltage VGD1 of the first switching element 21 is clamped to the first arbitrary voltage, and the voltage VGD2 of the second switching element 22 is clamped to the second arbitrary voltage.

[0045] Then, when the second drive instruction SA2 becomes an L signal and the second drive signal SK2 becomes an L signal at time point T1, the second switching element 22 transitions from the on state to the off state. In this case, the second switching element 22 enters a transition period during which current flows for a predetermined period even when the second drive signal SK2 becomes an L signal. Then, since the second switching element 22 transitions to the off state while the first switching element 21 is in the on state, the second control unit 62 switches the second control signal SB2 from an H signal to an L signal at time point T2 after the elapse of the second delay period ta2. As a result, the second control circuit 82 clamps the voltage VGD2 of the second switching element 22 to the second adjustment voltage. That is, the second control circuit 82 clamps the voltage VGD2 of the second switching element 22 to a value equal to or greater than the maximum value of the surge voltage that may occur when the first switching element 21 is turned off.

[0046] Note that no surge voltage is generated even when the second switching element 22 is transitioned from the on state to the off state while the first switching element 21 is in the on state. For this reason, the first control signal SB1 remains an H signal as it is, and the voltage VGD1 of the first switching element 21 is also clamped to the first arbitrary voltage as it is.

[0047] Thereafter, when the first drive instruction SA1 becomes an L signal and the first drive signal SK1 becomes an L signal at time point T3, the first switching element 21 transitions from the on state to the off state. At this time, at time point T4, a surge voltage VSRG is generated due to the transition of the first switching element 21 to the off state, and the voltage of the common node N is raised to the surge voltage. That is, the surge voltage VSRG is applied to the drain electrode D2 of the second switching element 22. However, in this embodiment, the voltage VGD2 of the second switching element 22 is clamped by the second adjustment voltage that is equal to or higher than the surge voltage. For this reason, it is suppressed that the second switching element 22 is turned on by the surge voltage VSRG.

[0048] Note that at time T3, the first drive instruction SA1 becomes an L signal and the first drive signal SK1 becomes an L signal. However, since the second switching element is in the off state, the first control signal SB1 remains an H signal as it is.

[0049] The above is the operation of the electronic control device in this embodiment. Although not particularly shown, the case where, after the first switching element 21 and the second switching element 22 are in the on state, the second switching element 22 is turned off after the first switching element 21 is turned off is the same. That is, in such a case, after the first switching element 21 is turned off, the voltage VGD1 of the first switching element 21 is clamped to the first adjustment voltage, thereby suppressing the first switching element 21 from being turned on by the surge voltage.

[0050] Also, in the above, the example where the second switching element 22 is turned off and then the first switching element 21 is turned off has been described starting from the case where the first switching element 21 and the second switching element 22 are in the on state. However, this is just one example. For example, the first switching element 21 and the second switching element 22 may be alternately switched between the on state and the off state.

[0051] According to the present embodiment described above, when one of the first switching element 21 or the second switching element 22 is in the on state and the other is in the off state, the voltage at which the other switching element breaks is made higher than the surge voltage generated when the one switching element becomes the off state. For this reason, it is possible to suppress the malfunction that the other switching element is turned on due to the surge voltage generated when one switching element is turned off.

[0052] (1) In this embodiment, the voltage VGD between the gates of the other switching element is made higher than the surge voltage VSRG. Therefore, it is possible to suppress the occurrence of a malfunction in which the other switching element turns on due to the surge voltage generated when one switching element is turned off.

[0053] (2) In this embodiment, when clamping the voltage VGD between the gates of the other switching element to the adjustment voltage, it is performed after a predetermined delay period has elapsed from the time when the other switching element transitions from the on state to the off state. For this reason, it is suppressed that the voltage VGD between the gates is clamped to the adjustment voltage while current is flowing through the other switching element. Thereby, it is possible to suppress the destruction of the other switching element and to suppress the fluctuation of the surge voltage VSRG.

[0054] (Second Embodiment) The second embodiment will be described. This embodiment is different from the first embodiment in that the breakdown voltage VBD1 of the first switching element 21 and the breakdown voltage VBD2 of the second switching element 22 are made lower. Since the other aspects are the same as those of the first embodiment, the description thereof will be omitted here.

[0055] First, in the above first embodiment, the configuration for suppressing the first switching element 21 from turning on when the second switching element 22 transitions from the on state to the off state by increasing the breakdown voltage VBD1 of the first switching element 21 has been described. Also, the configuration for suppressing the second switching element 22 from turning on when the first switching element 21 transitions from the on state to the off state by increasing the breakdown voltage VBD2 of the second switching element 22 has been described.

[0056] However, in order to suppress the first switching element 21 from turning on when the second switching element 22 transitions from the on state to the off state, the breakdown voltage VBD2 of the second switching element 22 may be lowered. Similarly, in order to suppress the second switching element 22 from turning on when the first switching element 21 transitions from the on state to the off state, the breakdown voltage VBD1 of the first switching element 21 may be lowered. That is, the generated surge voltage VSRG may be lowered. Hereinafter, the configuration of the present embodiment will be described.

[0057] The basic configuration of the electronic control device according to the present embodiment is the same as that of the first embodiment described above. However, the first adjustment voltage clamped by the first control circuit 81 and the second adjustment voltage clamped by the second control circuit 82 are changed.

[0058] First, a case where the first switching element 21 transitions from the on state to the off state when the second switching element 22 is in the off state will be described. The breakdown voltage VBD1 of the first switching element 21 is represented by the sum of the voltage VGD1 and the voltage VGS1 of the first switching element. And the voltage VGS1 of the first switching element 21 is determined by the threshold voltage Vt1 of the first switching element 21 required to flow a breakdown current. For this reason, when the first switching element 21 transitions from the on state to the off state, the voltage VGD1 of the first switching element 21 is controlled to be equal to or lower than VGD2 - VB - Vt1, so that the second switching element 22 can be suppressed from turning on. For this reason, the first adjustment voltage of the present embodiment is set to be equal to or lower than VGD2 - VB - Vt1.

[0059] Similarly, a case where the second switching element 22 transitions from the on state to the off state when the first switching element 21 is in the off state will be described. The breakdown voltage VBD2 of the second switching element 22 is represented by the sum of the voltage VGD2 and the voltage VGS2 of the second switching element. And the voltage VGS2 of the second switching element 22 is determined by the threshold voltage Vt2 of the second switching element 22 required to flow a breakdown current. For this reason, when the second switching element 22 transitions from the on state to the off state, the voltage VGD2 of the second switching element 22 is controlled to be equal to or lower than VGD1 - VB - Vt2, whereby it is possible to suppress the first switching element 21 from entering the on state. That is, the second adjustment voltage in the present embodiment is set to be equal to or lower than VGD1 - VB - Vt2.

[0060] Also, in the first slave control unit 61 of the present embodiment, an H signal as the first drive instruction SA1 is input from the first master control unit 51. When the first switching element 21 enters the off state after the second switching element 22 enters the off state, the first slave control unit 61 outputs an H signal as the first control signal SB1. The first slave control unit 61 outputs an L signal as the first control signal SB1 when an H signal as the first drive instruction SA1 is input from the first master control unit 51 and the first switching element 21 enters the off state before the second switching element 22. The first slave control unit 61 outputs an L signal as the first control signal SB1 when an L signal as the first drive instruction SA1 is input from the first master control unit 51.

[0061] Also, in the second slave control unit 62, when an H signal as the second drive instruction SA2 is input from the second master control unit 52 and the second switching element 22 enters the off state after the first switching element 21 enters the off state, the second slave control unit 62 outputs an H signal as the second control signal SB2. The second slave control unit 62 outputs an L signal as the second control signal SB2 when an H signal as the second drive instruction SA2 is input from the second master control unit 52 and the first switching element 21 enters the off state before the second switching element 22. The second slave control unit 62 outputs an L signal as the second control signal SB2 when an L signal as the second drive instruction SA2 is input from the second master control unit 52.

[0062] Next, the operation of the electronic control device according to this embodiment will be described with reference to FIG. 4. Hereinafter, an example will be described in which, after the second switching element 22 is turned off, the first switching element 21 is turned off, starting from the case where the first switching element 21 and the second switching element 22 are in the on state. Note that the maximum value of the surge voltage VSRG generated when the first switching element 21 is turned off is represented by VB + VBD1, where VBD1 = VGD1 + Vt1.

[0063] First, before time point T1, the first switching element 21 and the second switching element 22 are in the on state in which current flows. Also, the voltage VGD1 of the first switching element 21 is clamped to the first adjustment voltage, and the voltage VGD2 of the second switching element 22 is clamped to the second arbitrary voltage. Note that the first adjustment voltage is set to be equal to or lower than VGD2 - VB - Vt1 as described above.

[0064] Then, at time point T1, the second switching element 22 starts to transition to the off state, and at time point T2 when the second delay period ta2 has elapsed, the second switching element 22 becomes the off state. Hereinafter, the voltage VGD2 of the second switching element 22 after time point T2 will be described as VGD2, but VGD2 here may be the second arbitrary voltage or another voltage.

[0065] Thereafter, when the first switching element 21 transitions from the on state to the off state at time point T3, at time point T4, the voltage of the common node N is pulled up to the surge voltage VSRG. That is, the surge voltage VSRG is applied to the drain electrode D2 of the second switching element 22. Note that the maximum value of the surge voltage VSRG in this embodiment is VB + VBD1. However, in this embodiment, the voltage VGD1 of the first switching element 21 is clamped by the first adjustment voltage. Therefore, the second switching element 22 is suppressed from being turned on by the surge voltage VSRG.

[0066] According to the present embodiment described above, when one of the first switching element 21 or the second switching element 22 is in the on state and the other is in the off state, the voltage at which the other switching element breaks is made higher than the surge voltage generated when one switching element becomes the off state. For this reason, the same effects as those of the first embodiment can be obtained.

[0067] (1) In this embodiment, the voltage VGD between the gate and the gate-drain of one switching element is clamped to an adjustment voltage at which the surge voltage VSRG is lower than the voltage VGD between the gate and the drain of the other switching element. For this reason, it is possible to suppress the occurrence of malfunction in which the other switching element becomes the on state due to the surge voltage generated when one switching element is turned off.

[0068] (Third Embodiment) The third embodiment will be described. This embodiment includes a first voltage detection circuit and a second voltage detection circuit with respect to the first embodiment. Since the rest is the same as the first embodiment, the description is omitted here.

[0069] In the electronic control device of this embodiment, as shown in FIG. 5, a first voltage detection circuit 91 and a second voltage detection circuit 92 are provided. The first voltage detection circuit 91 is disposed between the gate electrode G1 and the source electrode S1 of the first switching element 21, detects the voltage VGS1, and outputs a first voltage detection signal DV1 to the first slave control unit 61. The second voltage detection circuit 92 is disposed between the gate electrode G2 and the source electrode S2 of the second switching element 22, detects the voltage VGS2, and outputs a second voltage detection signal DV2 to the second slave control unit 62.

[0070] Hereinafter, in the first switching element 21, the on-threshold voltage of the voltage VGS1 at which the current starts to flow is defined as Vton1, and the off-threshold voltage of the voltage VGS1 at which the current is almost cut off is defined as Vtoff1. Also, in the second switching element 22, the on-threshold voltage of the voltage VGS2 at which the current starts to flow is defined as Vton2, and the off-threshold voltage of the voltage VGS2 at which the current is almost cut off is defined as Vtoff2. In this embodiment, the off-threshold voltage Vtoff1 is made lower than the on-threshold voltage Vton1, and the off-threshold voltage Vtoff2 is made lower than the on-threshold voltage Vton2. Also, the off-threshold voltages Vtoff1 and Vtoff2 are set to values considering noise and the like.

[0071] Then, when the voltage VGS1 changes from less than the on-threshold voltage Vton1 to Vton1 or more, the first voltage detection circuit 91 outputs an H signal as the first voltage detection signal DV1. Also, when the voltage VGS1 changes from Vton1 or more to less than or equal to the off-threshold voltage Vtoff1, the first voltage detection circuit 91 outputs an L signal as the first voltage detection signal DV1.

[0072] Similarly, when the voltage VGS2 changes from less than the on-threshold voltage Vton2 to Vton2 or more, the second voltage detection circuit 92 outputs an H signal as the second voltage detection signal DV2. Also, when the voltage VGS2 changes from Vton2 or more to less than or equal to the off-threshold voltage Vtoff2, the first voltage detection circuit 91 outputs an L signal as the second voltage detection signal DV2.

[0073] When the second switching element 22 is in the on state and the first switching element 21 is in the off state, the first slave control unit 61 of the present embodiment outputs an L signal as the first control signal SB1 when the input first voltage detection signal DV1 switches from an H signal to an L signal. That is, when the second switching element 22 is in the on state and the first switching element 21 is in the off state, the first slave control unit 61 clamps the voltage VGD1 of the first switching element 21 to the first adjustment voltage when the input first voltage detection signal DV1 switches from an H signal to an L signal. In other words, in the present embodiment, the first delay period Ta1 is adjusted by the first voltage detection signal DV1 from the first voltage detection circuit 91.

[0074] Similarly, when the first switching element 21 is in the on state and the second switching element 22 is in the off state, the second slave control unit 62 outputs an L signal as the second control signal SB2 when the input second voltage detection signal DV2 switches from an H signal to an L signal. That is, when the first switching element 21 is in the on state and the second switching element 22 is in the off state, the second slave control unit 62 clamps the voltage VGD2 of the second switching element 22 to the second adjustment voltage when the input second voltage detection signal DV2 switches from an H signal to an L signal. In other words, in the present embodiment, the second delay period Ta2 is adjusted by the second voltage detection signal DV2 from the second voltage detection circuit 92.

[0075] The above is the configuration of the electronic control device in the present embodiment. Next, the operation of the electronic control device of the present embodiment will be described with reference to FIG. 6. Hereinafter, an example will be described in which the second switching element 22 is turned off and then the first switching element 21 is turned off when the first switching element 21 and the second switching element 22 are in the on state.

[0076] First, before time point T1, the first switching element 21 and the second switching element 22 are in the on state in which current flows.

[0077] Then, when the second drive instruction SA2 becomes an L signal and the second drive signal SK2 becomes an L signal at time point T1, the second switching element 22 transitions from the on state to the off state. In this case, the voltage VGS2 of the second switching element 22 gradually decreases from time point T1. Then, the second voltage detection signal DV2 switches from an H signal to an L signal at time point T2 when the voltage VGS2 becomes equal to or lower than the off threshold voltage Vtoff2. Therefore, the second slave control unit 62 switches the second control signal SB2 from an H signal to an L signal at time point T2 based on the second voltage detection signal DV2. That is, in this embodiment, the second delay period ta2 is determined by the voltage VGS2.

[0078] After that, similar to the first embodiment, the first switching element 21 is turned off while the voltage VGD2 of the second switching element 22 is clamped to the second adjustment voltage.

[0079] Although not particularly shown, the same applies when the second switching element 22 is turned off after the first switching element 21 is turned off, starting from the case where the first switching element 21 and the second switching element 22 are in the on state. That is, in such a case, after the first switching element 21 is turned off, the first delay period ta1 is determined by the voltage VGS1.

[0080] According to the embodiment described above, when one of the first switching element 21 and the second switching element 22 is in the on state and the other is in the off state, the voltage at which the other switching element breaks is made higher than the surge voltage generated when one switching element is turned off. Therefore, the same effect as the first embodiment can be obtained.

[0081] (1) In this embodiment, since the first delay period ta1 is determined by the voltage VGS1, the first delay period ta1 can be set to a value corresponding to the state of the first switching element 21. Therefore, the timing for clamping the voltage VGD1 to the first adjustment voltage can be controlled with high precision, and furthermore, malfunction of the first switching element 21 can be suppressed.

[0082] Similarly, since the second delay period ta2 is determined by the voltage VGS2, the second delay period ta2 can be set to a value corresponding to the state of the second switching element 22. Therefore, the timing for clamping the voltage VGD2 to the second adjustment voltage can be controlled with high precision, and furthermore, malfunction of the second switching element 22 can be suppressed.

[0083] (Fourth Embodiment) The fourth embodiment will be described. This embodiment is provided with a first current detection circuit and a second current detection circuit, in addition to the first embodiment. Since other aspects are the same as those of the first embodiment, the description thereof will be omitted here.

[0084] In the electronic control device of this embodiment, as shown in FIG. 7, a first current detector 101 and a second current detector 102, and a first current detection circuit 111 and a second current detection circuit 112 are provided.

[0085] The first current detector 101 is disposed between the source electrode S1 of the first switching element 21 and the first load 11. The first current detection circuit 111 is connected to both ends of the first current detector 101, detects the current flowing through the first current detector 101 (that is, the first switching element 21), and outputs a first current detection signal DI1 to the first slave control unit 61. The second current detector 102 is disposed between the source electrode S2 of the second switching element 22 and the second load 12. The second current detection circuit 112 is connected to both ends of the second current detector 102, detects the current flowing through the second current detector 102 (that is, the second switching element 22), and outputs a second current detection signal DI2 to the second slave control unit 62.

[0086] Specifically, if the current flowing through the first switching element 21 is equal to or greater than the threshold current Ith1, the first current detection circuit 111 outputs an H signal; if the current flowing through the first switching element 21 is less than the threshold current Ith1, the first current detection circuit 111 outputs an L signal. Similarly, if the current flowing through the second switching element 22 is equal to or greater than the threshold current Ith2, the second current detection circuit 112 outputs an H signal; if the current flowing through the second switching element 22 is less than the threshold current Ith2, the second current detection circuit 112 outputs an L signal. Note that the threshold currents Ith1 and Ith2 are set based on the minimum currents flowing through the first and second switching elements 21 and 22 in consideration of noise and the like.

[0087] When the second switching element 22 is in the on state and the first switching element 21 is in the off state, if the input first current detection signal DI1 switches from an H signal to an L signal, the first slave control unit 61 of the present embodiment outputs an L signal as the first control signal SB1. That is, when the second switching element 22 is in the on state and the first switching element 21 is in the off state, if the input first current detection signal DI1 switches from an H signal to an L signal, the first slave control unit 61 clamps the voltage VGD1 of the first switching element 21 to the first adjustment voltage. In other words, in the present embodiment, the first delay period Ta1 is adjusted by the first current detection signal DI1 from the first current detection circuit 111.

[0088] When the first switching element 21 is in the on state and the second switching element 22 is in the off state, if the input second current detection signal DI2 switches from an H signal to an L signal, the second slave control unit 62 of the present embodiment outputs an L signal as the second control signal SB2. That is, when the first switching element 21 is in the on state and the second switching element 22 is in the off state, if the input second current detection signal DI2 switches from an H signal to an L signal, the second slave control unit 62 clamps the voltage VGD2 of the second switching element 22 to the second adjustment voltage. In other words, in the present embodiment, the second delay period Ta2 is adjusted by the second current detection signal DI2 from the second current detection circuit 112.

[0089] The above is the configuration of the electronic control device in the present embodiment. Next, the operation of the electronic control device of the present embodiment will be described with reference to FIG. 8. Hereinafter, an example will be described in which, after the second switching element 22 is turned off, the first switching element 21 is turned off when the first switching element 21 and the second switching element 22 are in the on state.

[0090] First, before time point T1, the first switching element 21 and the second switching element 22 are in the on state in which current flows.

[0091] Then, when the second drive instruction SA2 becomes an L signal and the second drive signal SK2 becomes an L signal at time point T1, the second switching element 22 transitions from the on state to the off state. In this case, the current flowing through the second switching element 22 gradually decreases from time point T1. Then, the second current detection signal DI2 switches from the H signal to the L signal at time point T2 when the current flowing through the second switching element 22 becomes equal to or less than the threshold current Ith2. Therefore, the second slave control unit 62 switches the second control signal SB2 from the H signal to the L signal at time point T2 based on the second current detection signal DI2. That is, in the present embodiment, the second delay period ta2 is determined by the current flowing through the second switching element 22.

[0092] Thereafter, in the same manner as in the first embodiment, the first switching element 21 is turned off while the voltage VGD2 of the second switching element 22 is clamped to the second adjustment voltage.

[0093] Although not particularly shown, the same applies to the case where, after the first switching element 21 is turned off, the second switching element 22 is turned off when the first switching element 21 and the second switching element 22 are in the on state. That is, in such a case, after the first switching element 21 is turned off, the first delay period ta1 is determined by the current flowing through the first switching element 21.

[0094] According to the present embodiment described above, when one of the first switching element 21 or the second switching element 22 is in the on state and the other is in the off state, the voltage at which the other switching element breaks down is made higher than the surge voltage generated when one of the switching elements is turned off. Therefore, the same effects as those of the first embodiment can be obtained.

[0095] (1) In this embodiment, since the first delay period ta1 is determined by the current flowing through the first switching element 21, the first delay period ta1 can be set to a value corresponding to the state of the first switching element 21. Therefore, the timing for clamping the voltage VGD1 to the first adjustment voltage can be controlled with high precision, and furthermore, malfunction of the first switching element 21 can be suppressed.

[0096] Similarly, since the second delay period ta2 is determined by the current flowing through the second switching element 22, the second delay period ta2 can be set to a value corresponding to the state of the second switching element 22. Therefore, the timing for clamping the voltage VGD2 to the second adjustment voltage can be controlled with high precision, and furthermore, malfunction of the second switching element 22 can be suppressed.

[0097] (Fifth Embodiment) The fifth embodiment will be described. This embodiment is different from the first embodiment in that after changing to the adjustment voltage, it is changed to an arbitrary voltage. Regarding the rest, since it is the same as the first embodiment, the description is omitted here.

[0098] The electronic control device of this embodiment has the same configuration as that of the first embodiment. When the first switching element 21 and the second switching element 22 are in the on state, and then the first switching element 21 is turned off after the second switching element 22 is turned off, the following is done in this embodiment.

[0099] That is, as shown in FIG. 9, at time T2, after the voltage VGD2 of the second switching element 22 is clamped to the second adjustment voltage, at time T5 after a predetermined period has elapsed from time T4, the voltage VGD2 of the second switching element 22 is clamped to the second arbitrary voltage. Here, the predetermined period is set to be equal to or longer than the period during which the voltage of the common node N sufficiently decreases after being pulled up by the surge voltage VSRG generated at time T4.

[0100] Although not particularly shown, the same applies when the second switching element 22 is turned off after the first switching element 21 is turned off starting from the case where the first switching element 21 and the second switching element 22 are in the on state. That is, in such a case, after the first switching element 21 is turned off and the voltage VGD1 is clamped to the first adjustment voltage, the voltage VGD1 is clamped to the first arbitrary voltage after a predetermined period has elapsed from time T4.

[0101] Then, the first slave control unit 61 outputs the first control signal SB1 so that the voltage VGD1 of the first switching element 21 is changed as described above. Similarly, the second slave control unit 62 outputs the second control signal SB2 so that the voltage VGD2 of the second switching element 22 is changed as described above.

[0102] According to the present embodiment described above, when one of the first switching element 21 and the second switching element 22 is in the on state and the other is in the off state, the voltage at which the other switching element breaks is made higher than the surge voltage generated when one of the switching elements is turned off. Therefore, the same effect as that of the first embodiment can be obtained.

[0103] (1) In this embodiment, after clamping the voltage VGD1 of the first switching element 21 to the first adjustment voltage, it is clamped to the first arbitrary voltage after a predetermined period has elapsed. Similarly, after clamping the voltage VGD2 of the second switching element 22 to the second adjustment voltage, it is clamped to the second arbitrary voltage after a predetermined period has elapsed. Therefore, compared with the case where the voltage VGD1 of the first switching element 21 remains clamped to the first adjustment voltage or the voltage VGD2 of the second switching element 22 remains clamped to the second adjustment voltage, the resistance to positive surges applied from the outside can be increased.

[0104] (Sixth Embodiment) The sixth embodiment will be described. In this embodiment, compared with the first embodiment, the source electrode S1 of the first switching element 21 and the source electrode S2 of the second switching element 22 are connected to a common load via a common node N. Since the other aspects are the same as those of the first embodiment, the description thereof is omitted here.

[0105] As shown in FIG. 10, in the electronic control device of this embodiment, the source electrode S1 of the first switching element 21 and the source electrode S2 of the second switching element 22 are connected to the load 13 via the common node N. That is, in the electronic control device of this embodiment, the first switching element 21 and the second switching element 22 are connected to the common load 13. The drain electrode D1 of the first switching element 21 is connected to the first power supply 31. The drain electrode D2 of the second switching element 22 is connected to the second power supply 32. In this embodiment, a load 14 is also connected between the first power supply 31 and the first switching element 21.

[0106] In this embodiment, the first adjustment voltage of the first control circuit 81 is changed, and the second adjustment voltage of the second control circuit 82 is also changed. Hereinafter, the first adjustment voltage and the second adjustment voltage of this embodiment will be described. In this embodiment, the voltage of the first power supply 31 is described as the voltage VB1, and the voltage of the second power supply 32 is described as the voltage VB2.

[0107] Specifically, in such an electronic control device, when the second switching element 22 is in the off state, if the first switching element 21 is switched from the on state to the off state, the surge voltage VSRG generated at the common node N becomes VB1 - VBD1. And the voltage VDS2 applied across the drain - source of the second switching element 22 becomes VB2 - (VB1 - VBD2). Therefore, the second adjustment voltage in this embodiment is set to a voltage equal to or higher than VB2 - (VB1 - VBD2). That is, in this embodiment, by increasing the breakdown voltage VBD2, even if a surge voltage is generated by turning off the first switching element 21, the second switching element 22 can be suppressed from turning on.

[0108] Also, when the first switching element 21 is in the off state, if the second switching element 22 is switched from the on state to the off state, the surge voltage VSRG generated at the common node N becomes VB2 - VBD2. And the voltage VDS1 applied across the drain - source of the first switching element 21 becomes VB1 - (VB2 - VBD1). Therefore, the first adjustment voltage in this embodiment is set to a voltage equal to or higher than VB1 - (VB2 - VBD1). That is, in this embodiment, by increasing the breakdown voltage VBD1, even if a surge voltage is generated by turning off the second switching element 22, the first switching element 21 can be suppressed from turning on.

[0109] Note that the voltage VB1 and the voltage VB2 may change depending on the operating environment. For this reason, it is preferable that the first adjustment voltage and the second adjustment voltage are set based on the assumed maximum voltage.

[0110] According to the present embodiment described above, when one of the first switching element 21 or the second switching element 22 is in the on state and the other is in the off state, the voltage at which the other switching element breaks is made higher than the surge voltage generated when one switching element is turned off. For this reason, the same effects as those of the first embodiment can be obtained.

[0111] (Modification of the Sixth Embodiment) In the sixth embodiment described above, a plurality of additional switching elements may be provided. For example, as shown in FIG. 11, a third switching element 23 may be provided between the first switching element 21 and the common node N, and a fourth switching element 24 may be provided between the second switching element 22 and the common node N. That is, the first switching element 21 may be connected to the common node N via the third switching element 23, and the second switching element 22 may be connected to the common node N via the fourth switching element 24. Then, a third diode element 43 may be arranged in parallel with the third switching element 23, and a fourth diode element 44 may be arranged in the same manner as the fourth switching element 24. Note that the third switching element 23 and the fourth switching element 24 have the same configuration as the first switching element 21 and the second switching element 22. The third switching element 23 is arranged such that the source electrode S3 is connected to the source electrode S1 of the first switching element 21 and the drain electrode D3 is connected to the common node N. The fourth switching element 24 is arranged such that the source electrode S4 is connected to the source electrode S2 of the second switching element 22 and the drain electrode D4 is connected to the common node N.

[0112] Further, a third drive circuit 73 and a third break voltage control circuit (hereinafter also simply referred to as the third control circuit) 83 may be provided so as to be connected to the third switching element 23 and the first slave control unit 61. Further, a fourth drive circuit 74 and a fourth break voltage control circuit (hereinafter also simply referred to as the fourth control circuit) 84 may be provided so as to be connected to the fourth switching element 24 and the second slave control unit 62. Note that the third drive circuit 73 and the fourth drive circuit 74 have the same configuration as the first drive circuit 71 and the second drive circuit 72, and are connected to the gate electrodes G3 and G4 of the third switching element 23 and the fourth switching element 24. The third control circuit 83 and the fourth control circuit 84 have the same configuration as the first control circuit 81 and the second control circuit 82.

[0113] Then, in such an electronic control device, the first main control unit 51 outputs a first drive instruction SA1 and a third drive instruction SA3 to the first slave control unit 61, and the second main control unit 52 outputs a second drive instruction SA2 and a fourth drive instruction SA4 to the second slave control unit 62. The first slave control unit 61 outputs a third drive signal SK3 and a third control signal SB3 based on the third drive instruction SA3. The second slave control unit 62 outputs a fourth drive signal SK4 and a fourth control signal SB4 based on the fourth drive instruction SA4. Then, the electronic control device is controlled such that, for example, the first switching element 21 and the third switching element 23 are switched between an on state and an off state at the same timing, and the second switching element 22 and the fourth switching element 24 are switched between an on state and an off state at the same timing.

[0114] (Seventh Embodiment) The seventh embodiment will be described. In this embodiment, the first adjustment voltage and the second adjustment voltage are changed with respect to the sixth embodiment. Since other aspects are the same as those of the sixth embodiment, the description thereof will be omitted here.

[0115] In the sixth embodiment described above, a configuration has been described in which, by increasing the breakdown voltage VBD1 of the first switching element 21, the first switching element 21 is prevented from turning on when the second switching element 22 transitions from the on state to the off state. Further, a configuration has been described in which, by increasing the breakdown voltage VBD2 of the second switching element 22, the second switching element 22 is prevented from turning on when the first switching element 21 transitions from the on state to the off state.

[0116] However, similar to the second embodiment described above, in order to prevent the second switching element 22 from turning on when the first switching element 21 transitions from the on state to the off state, the breakdown voltage VBD1 of the first switching element 21 may be decreased. Similarly, in order to prevent the first switching element 21 from turning on when the second switching element 22 transitions from the on state to the off state, the breakdown voltage VBD2 of the second switching element 22 may be decreased.

[0117] Specifically, when the first switching element 21 is to be transitioned from the on state to the off state while the second switching element 22 is in the off state, the breakdown voltage VBD1 may be adjusted so as to satisfy VBD1 ≤ the second adjustment voltage - VB2 + VB1. That is, the second adjustment voltage may be set to be equal to or higher than VBD1 + VB2 - VB1.

[0118] Similarly, when the second switching element 22 is to be transitioned from the on state to the off state while the first switching element 21 is in the off state, the breakdown voltage VBD2 may be adjusted so as to satisfy VBD2 ≤ the first adjustment voltage - VB1 + VB2. That is, the first adjustment voltage may be set to be equal to or higher than VBD1 + VB2 - VB1.

[0119] According to the present embodiment described above, when one of the first switching element 21 or the second switching element 22 is in the on state and the other is in the off state, the voltage at which the other switching element breaks is made higher than the surge voltage generated when one of the switching elements becomes the off state. Therefore, the same effects as those of the first embodiment can be obtained.

[0120] (Eighth Embodiment) The eighth embodiment will be described. This embodiment is obtained by adding a first power supply voltage detection circuit and a second power supply voltage detection circuit to the sixth embodiment. Since the rest is the same as that of the sixth embodiment, the description thereof will be omitted here.

[0121] As shown in FIG. 12, the electronic control device of the present embodiment includes a first power supply voltage detection circuit 121 and a second power supply voltage detection circuit 122. The first power supply voltage detection circuit 121 is connected between the first power supply 31 and the first switching element 21, detects the voltage of the first power supply 31, and outputs a first power supply voltage detection signal DB1 to the first slave control unit 61 and the second slave control unit 62. The second power supply voltage detection circuit 122 is connected between the second power supply 32 and the second switching element 22, and outputs a second power supply voltage detection signal DB2 to the first slave control unit 61 and the second slave control unit 62.

[0122] Note that the first slave control unit 61 and the second slave control unit 62 are configured to be communicable. Therefore, the first power supply voltage detection circuit 121 may output the first power supply voltage detection signal DB1 only to the first slave control unit 61, for example. Then, the first slave control unit 61 may transmit the first power supply voltage detection signal DB1 to the second slave control unit 62 by communication. Similarly, the second power supply voltage detection circuit 122 may output the second power supply voltage detection signal DB2 only to the second slave control unit 62, for example. Then, the second slave control unit 62 may transmit the second power supply voltage detection signal DB2 to the first slave control unit 61 by communication.

[0123] Since the first regulated voltage of the first control circuit 81 of the present embodiment is a value defined by VB1 and VB2, the first regulated voltage is set based on the first power supply voltage detection signal DB1 and the second power supply voltage detection signal DB2. Similarly, since the second regulated voltage of the second control circuit 82 is a value defined by VB1 and VB2, the second regulated voltage is set based on the first power supply voltage detection signal DB1 and the second power supply voltage detection signal DB2.

[0124] According to the present embodiment described above, when one of the first switching element 21 or the second switching element 22 is in the on state and the other is in the off state, the voltage at which the other switching element breaks is made higher than the surge voltage generated when the one switching element becomes in the off state. Therefore, the same effect as that of the first embodiment can be obtained.

[0125] (1) In the present embodiment, the voltage VB1 of the first power supply 31 and the voltage VB2 of the second power supply 32 are detected, and the first regulated voltage and the second regulated voltage are adjusted based on the detected results. Therefore, the first regulated voltage and the second regulated voltage can be set to optimum values. Note that the present embodiment is applicable to the above-described embodiments.

[0126] (Other embodiments) Although the present disclosure has been described in accordance with the embodiments, it is understood that the present disclosure is not limited to the embodiments and structures. The present disclosure includes various modifications and modifications within the equivalent scope. In addition, various combinations and forms, and further other combinations and forms including only one element, more than one element, or less than one element thereof, fall within the scope and spirit of the present disclosure.

[0127] For example, in each of the above embodiments, the configurations of the first control circuit 81 and the second control circuit 82 can be changed as appropriate. For example, as shown in FIG. 13, the first control circuit 81 may include one Zener diode 811, a diode 813, and a switch 814, and these may be arranged in the order of the switch 814, the first Zener diode 811, and the diode 813 from the drain electrode D1 side. According to this, when the switch 814 is in the off state, the voltage VGD1 of the first switching element 21 is clamped to the avalanche voltage of the first switching element 21. When the switch 814 is in the on state, the voltage VGD1 of the first switching element 21 is clamped to Vz + Vf.

[0128] Also, in each of the above embodiments, the instructions, signals, etc. output by the first main control unit 51, the second main control unit 52, the first sub-control unit 61, and the second sub-control unit 62 are not particularly limited. That is, as long as the on and off states of the first and second switching elements 21 and 22, the voltages VGD1 and VGD2, etc. are adjusted as described above, the switching between the H signal and the L signal in the output instructions and signals can be changed as appropriate.

[0129] And the above embodiments can be combined as appropriate. For example, the second embodiment may be combined with the third to fifth and eighth embodiments to suppress malfunction by lowering the breakdown voltages DVB1 and DVB2. The third embodiment may be combined with the fifth to eighth embodiments so that the first and second delay periods ta1 and ta2 are defined by the voltages VGS1 and VGS2. The fourth embodiment may be combined with the fifth to eighth embodiments so that the first and second delay periods ta1 and ta2 are defined by the currents flowing through the first and second switching elements 21 and 22. The sixth and seventh embodiments may be combined with the eighth embodiment so that the source electrode S1 of the first switching element 21 and the source electrode S2 of the second switching element 22 are connected to the common node N. And combinations of combinations of the embodiments may be further combined.

[0130] The control unit and its method described in the present disclosure may be implemented by a dedicated computer provided by configuring a processor and a memory programmed to execute one or more functions embodied by a computer program. Alternatively, the control unit and its method described in the present disclosure may be implemented by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Or, the control unit and its method described in the present disclosure may be implemented by one or more dedicated computers configured by a combination of a processor programmed to execute one or more functions and a memory and a processor configured by one or more hardware logic circuits. Also, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions executable by a computer.

Explanation of Signs

[0131] 11, 12, 13 Load 21 First switching element 22 Second switching element 51 First main control unit 52 Second main control unit 61 First sub-control unit 62 Second sub-control unit 71 First drive circuit 72 Second drive circuit 81 First break voltage control circuit 82 Second break voltage control circuit N Common node G1, G2 Gate electrode S1, S2 Source electrode D1, D2 Drain electrode

Claims

1. An electronic control device in which a first switching element (21) and a second switching element (22) for controlling current flowing through loads (11, 12, 13) are connected via a common node (N), a first terminal (D1), a second terminal (S1), and a control terminal (G1) for controlling current flowing between the first terminal and the second terminal, and the on state in which current flows due to the voltage applied to the control terminal and the off state in which the current is cut off are controlled, the first switching element; a first terminal (D2), a second terminal (S2), and a control terminal (G2) for controlling current flowing between the first terminal and the second terminal, and the on state in which current flows due to the voltage applied to the control terminal and the off state in which the current is cut off are controlled, the second switching element; a control unit (51, 52, 61, 62, 71, 72, 81, 82) that controls the on state and off state of the first switching element and the second switching element, clamps the voltage between the first terminal and the control terminal in the first switching element to a predetermined voltage, and further clamps the voltage between the first terminal and the control terminal in the second switching element to a predetermined voltage; wherein when one of the first switching element and the second switching element is in the on state and the other is in the off state in the one-on state, the control unit clamps the voltage between the first terminal and the control terminal in the other switching element to an adjustment voltage that is higher than the surge voltage generated when the one switching element becomes the off state. An electronic control device.

2. The electronic control device according to claim 1, wherein when the control unit clamps the other switching element to the adjustment voltage, the control unit clamps the other switching element to the adjustment voltage after a predetermined delay period has elapsed from the time when the other switching element starts to transition from the on state to the off state.

3. A first voltage detection circuit (91) that detects the voltage between the second terminal and the control terminal in the first switching element and outputs a first voltage detection signal (DV1) to the control unit; A second voltage detection circuit (92) that detects a voltage between the second terminal and the control terminal in the second switching element and outputs a second voltage detection signal (DV2) to the control unit. Based on the first voltage detection signal or the second voltage detection signal, the control unit determines a period from the time when the other switching element starts to transition from the on state to the off state until the voltage between the second terminal and the control terminal in the other switching element becomes equal to or lower than a predetermined off threshold voltage as the delay period. The electronic control device according to claim 2.

4. A first current detection circuit (111) that detects a current flowing through the first switching element and outputs a first current detection signal (DI1) to the control unit. A second current detection circuit (112) that detects a current flowing through the second switching element and outputs a second current detection signal (DI2) to the control unit. Based on the first current detection signal or the second current detection signal, the control unit determines a period from the time when the other switching element starts to transition from the on state to the off state until the current flowing through the other switching element becomes equal to or lower than a predetermined threshold current as the delay period. The electronic control device according to claim 2.

5. When the control unit clamps the other switching element to the adjustment voltage, after a predetermined period has elapsed, the control unit changes the voltage between the first terminal and the control terminal in the other switching element to an arbitrary voltage different from the adjustment voltage. The electronic control device according to any one of claims 1 to 4.

6. An electronic control device in which a first switching element (21) and a second switching element (22) that control currents flowing through loads (11, 12, 13) are connected via a common node (N). A first terminal (D1), a second terminal (S1), and a control terminal (G1) for controlling a current flowing between the first terminal and the second terminal, wherein an on state in which a current flows and an off state in which the current is interrupted are controlled by a voltage applied to the control terminal. The first switching element. A first terminal (D2), a second terminal (S2), and a control terminal (G2) for controlling a current flowing between the first terminal and the second terminal, wherein an on state in which a current flows and an off state in which the current is interrupted are controlled by a voltage applied to the control terminal. The second switching element. A control unit (51, 52, 61, 62, 71, 72, 81, 82) that controls the on-state and off-state of the first switching element and the second switching element, clamps the voltage between the first terminal and the control terminal in the first switching element to a predetermined voltage, and further clamps the voltage between the first terminal and the control terminal in the second switching element to a predetermined voltage. When one of the first switching element and the second switching element is in the on-state and the other switching element is in the off-state, the control unit clamps the voltage between the first terminal and the control terminal in the one switching element to an adjustment voltage at which the surge voltage generated when the one switching element turns off is lower than the voltage between the first terminal and the control terminal in the other switching element. An electronic control device. **Claim 7** A power supply voltage detection circuit (121, 122) for detecting the voltage of a power supply (30, 31, 32) connected to at least one of the first switching element and the second switching element. The electronic control device according to any one of claims 1 to 6, wherein the control unit adjusts the adjustment voltage based on the result detected by the power supply voltage detection circuit.

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