drive device

Abstract

The drive device (20) is a drive device that drives the first switching element (11). The drive device (20) is provided with a protection switch (40). The protection switch (40) is provided between the first terminal and the third terminal of the first switching element (11), and becomes an open state when the voltage of the third terminal is equal to or higher than a second threshold value, and becomes a closed state when the voltage of the third terminal is lower than the second threshold value. When the protection switch (40) is in the closed state, the potential difference between the first terminal and the third terminal is lower than a first threshold value.

Description

Technical Field

[0001] This disclosure relates to a drive device. Background Technology

[0002] Patent Document 1 discloses an example of a drive element protection circuit. In the drive element protection circuit disclosed in Patent Document 1, if the power supply voltage drops below a low-voltage protection value, a low duty cycle signal is output from the drive circuit for a predetermined monitoring period. Through this operation, the drive element protection circuit prevents excessive current from flowing to the drive transistor even if a short-circuit fault occurs at motor 10.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2014-232948 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] exist Figure 5 In the example shown, at the first terminal of the switching element 104 (in Figure 5 In the example, the gate terminal) and the third terminal (in Figure 5 In the example, a circuit is in an ON state when the potential difference at the source terminal is above a threshold, and in an OFF state when it is below a threshold. In such a circuit, if the potential difference at the third terminal (at...) Figure 5 In the example where the switching element 104 is switched to the ON state while the conductive path on the source terminal side is grounded, there is a risk of excessive current flowing into the switching element 104 immediately after switching to the ON state. To protect the circuit from such overcurrent, such as... Figure 5 As shown, a detection circuit is provided to detect the voltage and current of the conductive path where the switching element 104 is located. If the detection circuit detects an abnormal voltage (e.g., a low voltage state below a threshold voltage) or overcurrent, a countermeasure is considered whereby the control unit 108 disconnects the switching element 104. However, such a countermeasure requires that the switching element 104 be disconnected based on the detection of current and voltage.

[0008] One of the objectives of this disclosure is to provide a technique for a drive device that can more easily protect a switching element in the event of a grounding fault in a conductive path where the switching element is located.

[0009] Technical solutions for solving the problem

[0010] As one aspect of this disclosure, a driving device drives a switching element in a circuit. The circuit includes the switching element having a first terminal, a second terminal, and a third terminal. The switching element is in an ON state when the potential difference between the first terminal and the third terminal is greater than or equal to a first threshold, and in an OFF state when the potential difference between the first terminal and the third terminal is less than the first threshold. The driving device also includes a protection switch disposed between the first terminal and the third terminal. The protection switch is in an OFF state when the voltage at the third terminal is greater than or equal to a second threshold, and in an ON state when the voltage at the third terminal is less than the second threshold. When the protection switch is in an ON state, the potential difference between the first terminal and the third terminal is less than the first threshold.

[0011] Invention Effects

[0012] The technology disclosed herein more simply enables a drive device that can quickly switch a switching element to an open state when the voltage on one side of a conductive path equipped with a switching element drops significantly. Attached Figure Description

[0013] Figure 1 This is a simplified example of a circuit diagram of an onboard system having the drive device of the first embodiment.

[0014] Figure 2 It is shown in Figure 1 A circuit diagram of an example obtained by embodying the drive unit in an onboard system.

[0015] Figure 3 It is shown Figure 2 The timing diagram shows the relationship between the drive signal, the source voltage of the switching element (SW1), the state of the protection switch (SW3), and the state of the switching element (SW1) in the vehicle system under normal conditions.

[0016] Figure 4 It is shown Figure 2 The timing diagram shows the relationship between the drive signal, the source voltage of the switching element (SW1), the state of the protection switch (SW3), and the state of the switching element (SW1) in the vehicle system under abnormal conditions.

[0017] Figure 5 This is a simplified example of a circuit diagram of an onboard system with a comparative drive unit. Detailed Implementation

[0018] The following are examples of embodiments of this disclosure. Furthermore, the features [1] to [6] described below can be combined arbitrarily without contradiction.

[0019] [1] A driving device drives a switching element in a circuit, the circuit including the switching element having a first terminal, a second terminal and a third terminal, wherein the switching element is in an on state when the potential difference between the first terminal and the third terminal is greater than or equal to a first threshold, and the switching element is in an off state when the potential difference between the first terminal and the third terminal is less than the first threshold, the driving device including a protection switch disposed between the first terminal and the third terminal, wherein the protection switch is in an off state when the voltage of the third terminal is greater than or equal to a second threshold, and the protection switch is in an on state when the voltage of the third terminal is less than the second threshold, wherein when the protection switch is in an on state, the potential difference between the first terminal and the third terminal is less than the first threshold.

[0020] The drive device described above [1] has the function of protecting a circuit that can be switched on by inputting a voltage signal with a potential difference of more than a first threshold between the first terminal and the third terminal to the first terminal. In the event of an abnormal change such as the voltage of the conductive path on the third terminal side falling below a second threshold, the drive device can forcibly and quickly set the protection switch to the on state and forcibly and quickly set the switching element to the off state. Therefore, this drive device can more easily realize a structure that can quickly switch the switching element to the off state when the voltage on one side of the conductive path where the switching element is located drops significantly.

[0021] [2] The driving device of [1] described above has the following features. The driving device of [2] includes a signal output section that outputs a high-level signal with a predetermined voltage and a signal line disposed between the signal output section and the first terminal. Further, the driving device of [2] includes a first resistor section disposed on the signal line, a second resistor section different from the first resistor section, and an element section disposed between the first resistor section and the second resistor section. One end of the element section is electrically connected between the first resistor section and the first terminal at the signal line. The other end of the element section is electrically connected to the third terminal. One end of the second resistor section is electrically connected to the third terminal. The other end of the second resistor section is electrically connected to a reference conductive circuit. When the signal output section outputs the high-level signal, current flows from the signal output section to the reference conductive circuit via the first resistor section, the element section, and the second resistor section. The third terminal becomes a voltage of the second threshold or higher, and due to the voltage drop generated at the element section, the potential difference between the first terminal and the third terminal becomes a first threshold or higher.

[0022] In the drive device described in [2] above, a high-level signal is output from the signal output unit as a condition, and current flows from the signal output unit to the reference conductive circuit via the first resistor unit, the element unit, and the second resistor unit. Then, due to the voltage drop generated at the element unit, the potential difference between the first terminal and the third terminal becomes a first threshold or higher. In this structure, when a high-level signal is output from the signal output unit, and when current flows appropriately to the element unit, the switching element can be turned on appropriately. Furthermore, when a high-level signal is output from the signal output unit, as long as a certain amount of current flows to the second resistor unit, the voltage of the third terminal can be increased relative to the reference conductive circuit, and the voltage can be stably set to a level above the second threshold. The drive device can, while setting this operation as a basic operation, forcibly switch the protection switch to the on state in the event of an abnormal change such as the voltage of the conductive circuit connected to the third terminal falling below the second threshold.

[0023] [3] The driving device of [2] described above has the following features. The driving device of [3] includes a switching unit that switches the first terminal and the third terminal to a short-circuit state and a de-circuit state in which the short-circuit state is de-circuited. When the switching unit switches to the short-circuit state while the signal output unit outputs the high-level signal, the switching element becomes open. When the signal output unit outputs the high-level signal, the switching element becomes closed as long as the switching unit maintains the de-circuit state.

[0024] When the drive device described above [3] outputs the high-level signal from the signal output section, the switching section can switch the switching element to an on state and an off state.

[0025] [4] The drive device described in any one of [1] to [3] above has the following features: The switching element is disposed between the first conductive path and the second conductive path. The second terminal is electrically connected to the first conductive path. The third terminal is electrically connected to the second conductive path. A first power supply unit is disposed on the first conductive path side. A second power supply unit is disposed on the second conductive path side. The structure allows current to flow between the first power supply unit and the second power supply unit when at least the switching element is in an ON state. A normal state is when the voltage of the third terminal is above the second threshold when the first power supply unit and the second power supply unit are connected. An abnormal state is when the voltage of the third terminal is below the second threshold when the first power supply unit and the second power supply unit are connected.

[0026] The drive device described above [4] can be applied to a circuit where the switching element is located between the first power supply unit and the second power supply unit. Then, in the normal state, when there is conduction between the first power supply unit and the second power supply unit, the protection switch is maintained in the open state; in the abnormal state, when there is conduction between the first power supply unit and the second power supply unit, the protection switch is maintained in the closed state. That is, when an appropriate voltage based on the output of the power supply unit is applied to the third terminal, the drive device can maintain the protection switch in the open state, preventing the switching element from performing a forced disconnection operation based on the protection switch. On the other hand, when an appropriate voltage based on the output of the power supply unit is not applied to the third terminal due to grounding or the like, the drive device can maintain the protection switch in the closed state, forcibly and stably setting the switching element to the open state.

[0027] [5] The drive device described in [4] above has the following features. The drive device of [5] includes a second switching element connected in series with the switching element between the first power supply unit and the second power supply unit. The second conductive path has one conductive path connected to the third terminal and the second switching element on one side of the second switching element, and another conductive path connected to the other side of the second switching element. One end of the protection switch is electrically connected to the first terminal, and the other end of the protection switch is electrically connected to the conductive path. Energization between the first power supply unit and the second power supply unit is permitted when both the switching element and the second switching element are in the ON state. When both the switching element and the second switching element are in the OFF state, the energization between the first power supply unit and the second power supply unit is cut off. When both the switching element and the second switching element are in the ON state, in the normal state, the voltage of the third terminal is above the second threshold. When both the switching element and the second switching element are in the ON state, in the abnormal state, the voltage of the third terminal is below the second threshold.

[0028] The drive device described above [5] can be applied to a circuit that switches between a first power supply unit and a second power supply unit in an energized state and an off state by switching the on and off states of a switching element and a second switching element. In the normal state, when both the switching element and the second switching element are in the on state, the first power supply unit and the second power supply unit are energized, and the voltage at the third terminal is above the second threshold. That is, in the normal state, when both switching elements are in the on state, it is possible to maintain the energized state between the two power supply units without performing a forced disconnection operation based on the protection switch. On the other hand, when an abnormal state occurs when both switching elements are in the on state, the protection switch can be immediately set to the on state. Therefore, even if the two power supply units are energized until just before the abnormal state occurs, the switching elements can be immediately switched to a forced disconnection state.

[0029] [6] The drive device described in any one of [2] to [5] above has the following features: The element is a Zener diode, the anode of the Zener diode is electrically connected to the third terminal, and the cathode of the Zener diode is electrically connected to the first terminal. When the high-level signal is output from the signal output unit, the Zener diode breaks down, and the potential difference between the first terminal and the third terminal remains above the first threshold value.

[0030] When the drive device described above [6] outputs a high-level signal from the signal output unit without performing the operation of forcibly short-circuiting the first terminal and the third terminal, current flows from the signal output unit to the reference conductive circuit via the first resistor, the Zener diode, and the second resistor. Then, due to the voltage drop generated at the Zener diode, the potential difference between the first terminal and the third terminal remains above the first threshold, and the switching element can be stably maintained in the on state. Then, under normal conditions, since current flows to the reference conductive circuit via the second resistor, the third terminal maintains a voltage higher than that of the reference conductive circuit, and the voltage of the third terminal can be stably maintained above the second threshold.

[0031] <First Implementation>

[0032] 1. Overview of in-vehicle systems

[0033] The following description relates to an in-vehicle system 100, which is an example of a system that uses the drive device according to the first embodiment. Figure 1 The vehicle system 100 shown is configured as a vehicle power system having multiple power sources (first power source 91 and second power source 92).

[0034] Figure 1The vehicle system 100 shown is a system comprising a first power supply unit 91, a second power supply unit 92, a load 94, a first conductive circuit 81, a second conductive circuit 82, and a relay device 1.

[0035] The load 94 can be any electrical component that can receive power through the second conductive circuit 82. The load 94 can be various vehicle-mounted electrical components such as actuators and motors.

[0036] The first power supply unit 91 is configured as a first energy storage unit that outputs a first output voltage (e.g., 12V). The second power supply unit 92 is configured as a second energy storage unit that outputs a second output voltage (e.g., 12V). The first output voltage and the second output voltage may be the same or different. The first power supply unit 91 and the second power supply unit 92 may be configured as known energy storage units such as lead-acid batteries, lithium-ion batteries, and capacitors such as double-layer capacitors. The first power supply unit 91 and the second power supply unit 92 may be configured as energy storage units of the same type or as different types.

[0037] The first conductive path 81 is a conductive path electrically connected to the high-potential side terminal of the first power supply unit 91. The first conductive path 81 is connected between the drain terminal of the switching element 11 and the first power supply unit 91. A first output voltage is applied to the first conductive path 81 based on the power supply from the first power supply unit 91.

[0038] The second conductive path 82 is a conductive path electrically connected to the high-potential side terminal of the second power supply unit 92. A second output voltage is applied to the second conductive path 82 based on the power supply from the second power supply unit 92. The second conductive path 82 includes conductive paths 82A and 82B. Conductive path 82A is an example of one conductive path. Conductive path 82A is connected between the source terminal (third terminal) of the first switching element 11 and the source terminal of the second switching element 12 on one side of the second switching element 12. Conductive path 82B is an example of another conductive path. Conductive path 82B is connected between the drain terminal of the second switching element 12 and the second power supply unit 92 on the other side of the second switching element 12.

[0039] The relay device 1 includes a first switching element 11, a second switching element 12, and a drive device 20. The relay device 1 is a device that switches between an on state and an off state between a first power supply unit 91 and a second power supply unit 92.

[0040] The first switching element 11 is an example of a switching element. The first switching element 11 can function as a first FET. The first switching element 11 is configured as a first MOSFET (Metal Oxide Semiconductor Field Effect Transistor). Figure 1 In this example, the first switching element 11 is configured as an N-channel MOSFET having a gate terminal, a drain terminal, and a source terminal. The gate terminal of the first switching element 11 corresponds to an example of a first terminal. The drain terminal of the first switching element 11 corresponds to an example of a second terminal. The source terminal of the first switching element 11 corresponds to an example of a third terminal. The first switching element 11 is in an ON state when the potential difference between the gate terminal and the drain terminal is above a first threshold, and in an OFF state when the potential difference between the gate terminal and the drain terminal is below the first threshold. Furthermore, the first switching element 11 is also simply referred to as switching element 11.

[0041] A first switching element 11 is disposed between a first conductive path 81 and a second conductive path 82. A signal line 51B, constituting the signal line 51 described later, is electrically connected to the gate terminal of the first switching element 11. The drain terminal of the first switching element 11 is electrically connected to the first conductive path 81. A voltage corresponding to the output voltage of the first power supply unit 91 is applied to the drain terminal of the first switching element 11. A conductive path 82A, which forms part of the second conductive path 82, is electrically connected to the source terminal of the first switching element 11. At the source terminal of the first switching element 11, one end of the element part 24 (Zener diode) is electrically connected, and one end of the second resistor part 32 is also electrically connected. The anode of the body diode of the first switching element 11 is electrically connected to the source terminal and to conductive path 82A, and the cathode is electrically connected to the drain terminal and to the first conductive path 81. Thus, relative to the first switching element 11, the first power supply unit 91 is disposed on the first conductive path 81 side, and the second power supply unit 92 is disposed on the second conductive path 82 side. In this structure, when the first switching element 11 is in the ON state, the current flows from the first power supply section 91 to the second power supply section 92. When the first switching element 11 is in the OFF state, the current does not flow from the first power supply section 91 to the second power supply section 92.

[0042] The second switching element 12 can function as a second FET. The second switching element 12 is configured as a second MOSFET. Figure 1In this example, the second switching element 12 is configured as an N-channel MOSFET having a gate terminal, a drain terminal, and a source terminal. An on signal and an off signal from the drive circuit are input to the gate terminal of the second switching element 12. The drive circuit can be a part or all of the control unit 28, or it can be configured as a circuit different from the control unit 28. The second switching element 12 is in an on state when an on signal (a signal with a predetermined high-level voltage) is provided to its gate terminal from the drive circuit, and in an off state when an off signal (e.g., a signal with a predetermined low-level voltage) is provided to its gate terminal.

[0043] The second switching element 12 is connected in series with the first switching element 11 between the first conductive path 81 and the second conductive path 82. The drain terminal of the second switching element 12 is electrically connected to conductive path 82B, which forms part of the second conductive path 82. At the drain terminal of the second switching element 12, a voltage corresponding to the output voltage is applied by the second power supply unit 92. At the source terminal of the second switching element 12, the source terminal of the first switching element 11 is electrically connected, and one end of the element part 24 and one end of the second resistor part 32 are also electrically connected. The anode of the body diode of the second switching element 12 is electrically connected to the source terminal and to conductive path 82A, and the cathode is electrically connected to the drain terminal and to conductive path 82B.

[0044] Thus, the body diodes of the first switching element 11 and the second switching element 12 are configured in opposite directions. In this structure, current flows from the second power supply section 92 to the first power supply section 91 when the second switching element 12 is in the ON state, and current does not flow from the second power supply section 92 to the first power supply section 91 when the second switching element 12 is in the OFF state. More specifically, the relay device 1 allows bidirectional energization between the first power supply section 91 and the second power supply section 92 when both the first switching element 11 and the second switching element 12 are in the ON state. When both the first switching element 11 and the second switching element 12 are in the OFF state, bidirectional energization between the first power supply section 91 and the second power supply section 92 is interrupted.

[0045] 2. Details of the drive unit

[0046] The drive device 20 is a drive device for driving the first switching element 11. The drive device 20 mainly includes a signal line 51, a first resistor section 31, a second resistor section 32, an element section 24, a switch 26, a protection switch 40, a boost circuit 22, etc.

[0047] The boost circuit 22 is an example of a signal output section. The boost circuit 22 boosts the input voltage, which is based on the power input from the first power supply unit 91 via diode 62, and outputs a high-level signal (e.g., a 24V signal) that is higher than the input voltage. The high-level signal output by the boost circuit 22 is, for example, greater than the output voltage of the first power supply unit 91 and greater than the output voltage of the second power supply unit 92. The boost circuit 22 can be any known circuit capable of boosting the input voltage to generate an output voltage higher than the input voltage. Furthermore, a capacitor 64 is connected between the input line disposed between the cathode of diode 62 and the boost circuit 22 and ground.

[0048] Signal line 51 is disposed between boost circuit 22 and gate terminal of switching element 11. The conductive path in signal line 51 connecting the first resistor section 31 and boost circuit 22 is signal line 51A. The conductive path in signal line 51 connecting the first resistor section 31 and gate terminal of switching element 11 is signal line 51B.

[0049] The first resistor section 31 is a resistor located in the middle of the signal line 51. One end of the first resistor section 31 is electrically connected to the boost circuit 22. The other end of the first resistor section 31 is electrically connected to one end of the switch 26, one end of the element section 24, one end of the protection switch 40, and the gate terminal of the switching element 11.

[0050] Component 24 is a component disposed between the first resistor 31 and the second resistor 32. One end of component 24 is electrically connected between the first resistor 31 at signal line 51 and the gate terminal of the switching element 11. The other end of component 24 is electrically connected to the source terminal of the switching element 11. Figure 1 In this example, element 24 is a Zener diode, the anode of which is electrically connected to the source terminal of switching element 11, and the cathode of which is electrically connected to the gate terminal of switching element 11. The Zener diode constituting element 24 breaks down when a voltage higher than a constant value is applied to signal line 51B than to conductive path 82A, thus maintaining a constant voltage between signal line 51B and conductive path 82A.

[0051] The second resistor 32 is a different resistor from the first resistor 31. One end of the second resistor 32 is electrically connected to the source terminal of the switching element 11. The other end of the second resistor 32 is electrically connected to a reference conductive circuit. The reference conductive circuit is a conductive circuit maintained at a constant low voltage. Figure 1 The example is land. In Figure 1 In the structure, the first resistor section 31, the element section 24, and the second resistor section 32 are connected in series between the boost circuit 22 and ground.

[0052] Switch 26 is located between signal line 51B and conductive path 82A. Switch 26 switches the connection between signal line 51B and conductive path 82A to a state where the connection is energized via switch 26 (specifically, a short circuit state) and a state where the connection is de-energized via switch 26 (specifically, a short circuit state). Switch 26 can be constructed from either a semiconductor switch or a mechanical relay.

[0053] The control unit 28 is a control device that alternately outputs an on signal to turn on the switch 26 and an off signal to turn off the switch 26. The control unit 28 functions as a drive circuit to drive the switch 26. The control unit 28 can be composed of an information processing device such as a microcomputer, or other hardware circuits.

[0054] When a signal is provided from the control unit 28, switch 26 becomes ON, short-circuiting signal line 51B and conductive path 82A. When a signal is provided from the control unit 28, switch 26 becomes OFF, releasing the short circuit between signal line 51B and conductive path 82A. When switch 26 is ON, current is allowed to flow through switch 26 from signal line 51B to conductive path 82A; when switch 26 is OFF, current does not flow through switch 26. The control unit 28 and switch 26 are an example of a switching unit, switching the gate terminal and source terminal of switching element 11 to a short-circuit state and a de-circuit state. By switching switch 26 to ON, the control unit 28 and switch 26 short-circuit the gate terminal and source terminal of switching element 11, setting them to the same potential, and setting the potential difference between these gate terminals and source terminals to be lower than a first threshold. On the other hand, by switching switch 26 OFF, the control unit 28 and switch 26 release the aforementioned short-circuit state.

[0055] A protection switch 40 is disposed between the gate terminal and the source terminal of the switching element 11. The protection switch 40 is in an open state when the voltage (ground-based voltage) at the source terminal of the switching element 11 is above a second threshold, and in an on state when it is below the second threshold. One end of the protection switch 40 is electrically connected to the gate terminal of the switching element 11. The other end of the protection switch 40 is electrically connected to conductive path 82A (a conductive path). The protection switch 40 is configured to set the potential difference between the gate terminal and the source terminal of the switching element 11 below a first threshold when it is in the on state.

[0056] As long as the protective switch 40 has the above-mentioned functions, it can adopt various structures. The representative example described below is the configuration of the protective switch 40 and its surrounding circuit. Figure 2 The structure shown.

[0057] exist Figure 2In the drive device 20 shown, the protection switch 40 is configured as a normally closed semiconductor switch. Specifically, the protection switch 40 can be configured as a depletion-type MOSFET, a junction FET, or the like. Figure 2 In this example, resistors 42 and 44 are connected in series between conductive path 82A and ground. The voltage obtained by dividing the voltage between conductive path 82A and ground according to the voltage division ratio of resistors 42 and 44 is input to the gate of protection switch 40. In this structure, the higher the voltage of conductive path 82A, the higher the voltage input to the gate of protection switch 40. Furthermore, when the voltage of conductive path 82A relative to ground is above the second threshold, protection switch 40 remains in the open state; when the voltage of conductive path 82A relative to ground is below the second threshold, protection switch 40 remains in the closed state.

[0058] 3. Operation of the drive unit

[0059] First, the operation under normal conditions, where no grounding occurs at conductive path 82B, load 94, etc., will be explained. Furthermore, in this specification, the normal state is when the voltage at the source terminal of switching element 11 is above the second threshold when conduction occurs between the first power supply section 91 and the second power supply section 92. That is, in the normal state, when both the first switching element 11 and the second switching element 12 are on, the voltage at the source terminal of switching element 11 is above the second threshold. The abnormal state is when the voltage at the source terminal of switching element 11 is below the second threshold when conduction occurs between the first power supply section 91 and the second power supply section 92. That is, in the abnormal state, when both the first switching element 11 and the second switching element 12 are on, the voltage at the source terminal of switching element 11 is below the second threshold.

[0060] exist Figure 3 The diagram illustrates the relationship between the drive signal, the source voltage of the switching element (SW1), the state of the protection switch (SW3), and the state of the switching element (SW1) under the aforementioned normal conditions. Figure 3 , Figure 4 In this context, an active drive signal means switch 26 is off, and a deactivated drive signal means switch 26 is on. Figure 2 In the drive device 20 shown, when the first switching element 11 is turned on, the control unit 28 outputs a disconnect signal (as an activation signal for the drive signal) for the switch 26. When the first switching element 11 is turned off, the control unit 28 outputs a turn-on signal (as a deactivation signal for the drive signal) for the switch 26. Figure 3As shown, when the control unit 28 outputs an on signal for switch 26 (an inactive signal that serves as a drive signal), that is, when switching to a short-circuit state (on state of switch 26), the first switching element 11 becomes off. At this time, if the second switching element 12 is off, the voltage at the source terminal of the first switching element 11 remains below the second threshold Vth, and the protection switch 40 (SW3) remains on.

[0061] If, under normal conditions, the control unit 28 outputs an open signal for the switch 26 (as an activation signal for the drive signal), then, when the boost circuit 22 outputs a high-level signal, current flows from the boost circuit 22 to ground via the first resistor unit 31, the element unit 24, and the second resistor unit 32. Figure 3 As shown, if current flows from the boost circuit 22 through the first resistor section 31, the element section 24, and the second resistor section 32 to ground, the voltage of the conductive path 82A and the voltage of the source terminal of the switching element 11 become a second threshold Vth or higher. In this state, the protection switch 40 (SW3) remains in the open state. Then, with current flowing in this way, the element section 24 clamps the gate terminal and the source terminal of the switching element 11 at a predetermined voltage above the first threshold, and the switching element 11 remains in the closed state. Thus, under normal conditions, when the boost circuit 22 outputs a high-level signal, the first switching element 11 remains in the closed state as a condition that the control section 28 and the switch 26 (switching section) remain in the deactivated state (the open state of switch 26).

[0062] Furthermore, under the aforementioned normal state, when current flows from the boost circuit 22 through the first resistor section 31, the element section 24, and the second resistor section 32 to ground, the voltage of the conductive path 82A is, for example, greater than the voltage of the conductive path 82B, and greater than the output voltage of the second power supply section 92.

[0063] exist Figure 4 The diagram illustrates the relationship between the drive signal, the source voltage of the switching element (SW1), the state of the protection switch (SW3), and the state of the switching element (SW1) during the aforementioned abnormal state. Figure 4 In the case where the control unit 28 outputs an on signal for the switch 26 (an inactive signal that serves as a drive signal), that is, when the switch is switched to a short-circuit state (the on state of the switch 26), the first switching element 11 (SW1) remains in the off state.

[0064] In the aforementioned abnormal state, when the control unit 28 outputs a disconnect signal for switch 26 (as an activation signal for the drive signal), even if the boost circuit 22 outputs a high-level signal, the voltages of conductive paths 82A and 82B are set to near 0V due to grounding at load 94. That is, the voltage of conductive path 82A and the voltage of the source terminal of switching element 11 remain below the second threshold Vth, and the protection switch 40 (SW3) remains in the ON state. Therefore, after the control unit 28 outputs a disconnect signal for switch 26 (as an activation signal for the drive signal), the protection switch 40 (SW3) also remains in the ON state, and the switching element 11 also remains in the OFF state.

[0065] 4. Examples of effects

[0066] The following description relates to an example of the effect of the first embodiment. The drive device 20 has the function of protecting a circuit that can turn on the first switching element 11 by inputting a voltage signal to the gate terminal where the potential difference between the gate terminal (first terminal) and the source terminal (third terminal) of the first switching element 11 is greater than or equal to a first threshold. In the event of an abnormal change such as the conductivity 82A on the source terminal side of the first switching element 11 falling below a second threshold, the drive device 20 can forcibly and quickly set the protection switch 40 to the on state and forcibly and quickly set the first switching element 11 to the off state. Therefore, the drive device 20 can more easily implement a structure that can quickly switch the first switching element 11 to the off state when a significant drop in voltage occurs on the side of the conductivity path where the first switching element 11 is located.

[0067] Regarding the drive device 20, under the condition of outputting a high-level signal from the boost circuit 22 (signal output section), current flows from the boost circuit 22 (signal output section) through the first resistor section 31, the element section 24, and the second resistor section 32 to ground (reference conductive path). Then, due to the voltage drop generated at the element section 24, the potential difference between the gate terminal and the source terminal of the first switching element 11 becomes a first threshold or higher. In this structure, when a high-level signal is output from the boost circuit 22, the first switching element 11 can be properly switched on as long as an appropriate current flows to the element section 24. Furthermore, when the drive device 20 outputs a high-level signal from the boost circuit 22, as long as no abnormal changes (such as grounding) occur at the conductive path 82 connected to the source terminal (third terminal) of the first switching element 11, the voltage at the source terminal of the first switching element 11 can be set to a certain high voltage (a voltage higher than the second threshold). Therefore, when no abnormal voltage drop (such as grounding) occurs at the conductive path 82 connected to the source terminal of the first switching element 11, the protection switch 40 can be stably maintained in the open state. On the other hand, if an abnormal change occurs where the source terminal of the first switching element 11 falls below the second threshold (such as grounding at the conductive path 82), the drive device 20 can forcibly switch the protection switch to the closed state, thereby suppressing excessive current flow to the first switching element 11.

[0068] When the boost circuit 22 (signal output unit) outputs a high-level signal, the drive device 20 can switch the first switching element 11 to an on state and an off state by the control unit 28 and the switch 26 (switching unit).

[0069] The drive device 20 can be applied to a circuit where the first switching element 11 is located between the first power supply section 91 and the second power supply section 92. Furthermore, in a normal state, when the first power supply section 91 and the second power supply section 92 are connected, the protection switch 40 can be maintained in an open state; in an abnormal state, when the first power supply section 91 and the second power supply section 92 are connected, the protection switch 40 can be maintained in an on state. That is, when the first power supply section 91 and the second power supply section 92 are connected, the drive device 20 maintains the protection switch 40 in an open state by applying an appropriate voltage based on the output of the power supply section to the source terminal (third terminal) of the first switching element 11. In this case, the drive device 20 does not force the first switching element 11 to disconnect based on the protection switch 40. On the other hand, when the first power supply section 91 and the second power supply section 92 are connected, the drive device 20 maintains the protection switch 40 in an on state by not applying an appropriate voltage based on the output of the power supply section to the third terminal due to grounding or the like. In this case, the drive device 20 can force and stably set the first switching element 11 to the off state.

[0070] The drive device 20 can be applied to a circuit that switches between an on-state and an off-state between a first power supply unit 91 and a second power supply unit 92 by switching the first switching element 11 and the second switching element 12 on and off. In this circuit, when both the first switching element 11 and the second switching element 12 are on, in the normal state, the first power supply unit 91 and the second power supply unit 92 are energized, and the voltage at the source terminal (third terminal) is above a second threshold. That is, when both switching elements are on, in the normal state, while maintaining the energization between the two power supplies, the first switching element 11 is not forcibly disconnected based on the protection switch 40. On the other hand, when an abnormal state occurs when both switching elements are on, the protection switch 40 can be immediately switched on. Therefore, even if the two power supplies are energized until an abnormal state occurs, the switching element 11 can be immediately switched to a forcibly disconnected state.

[0071] When the drive device 20 outputs a high-level signal from the boost circuit 22 (signal output section) without performing an operation to forcibly short-circuit the gate terminal (first terminal) and source terminal (third terminal) of the first switching element 11, current flows to the element section 24. In this case, the current flows from the boost circuit 22 (signal output section) to ground (reference conductive path) via the first resistor section 31, the element section 24 (Zener diode), and the second resistor section 32. Then, due to the voltage drop generated at the element section 24 (Zener diode), the potential difference between the gate terminal and the source terminal of the first switching element 11 is maintained at or above a first threshold, and the switching element 11 can be stably maintained in the on state. Then, in the normal state, the current flows to ground via the second resistor section 32, thereby maintaining the source terminal of the first switching element 11 at a voltage higher than ground, and easily maintaining it stably at or above the second threshold.

[0072] <Other Implementation Methods>

[0073] This disclosure is not limited to the embodiments described above and the accompanying drawings. For example, the features of the embodiments described above or later can be combined in all possible ways without contradiction. Furthermore, features of any party in the embodiments described above or later can be omitted unless explicitly stated as essential. Further, the above embodiments can also be modified as follows.

[0074] In the above embodiment, the drive device 20 does not include switching elements 11 and 12, but the drive device 20 may also include switching elements 11 and 12. That is, the relay device 1 as a whole may also correspond to the drive device.

[0075] In the above embodiment, the first switching element 11 and the second switching element 12 are composed of MOSFETs, but this is not a limitation. The first switching element and the second switching element may also be, for example, an N-channel IGBT (Insulated Gate Bipolar Transistor). In this case, the gate terminal of the IGBT constituting the first switching element corresponds to the first terminal, the collector terminal corresponds to the second terminal, and the emitter terminal corresponds to the third terminal.

[0076] In the above embodiment, a Zener diode is exemplified as the component section 24, but the component section may also be composed of resistors or other components.

[0077] Furthermore, it should be considered that the embodiments disclosed herein are exemplary in all respects and not restrictive. The scope of the invention is not limited to the embodiments disclosed herein, and is intended to include all modifications within the scope expressed by the claims or their equivalents.

[0078] Explanation of reference numerals in the attached figures

[0079] 11: First switching element (switching element)

[0080] 12: Second switching element

[0081] 20: Drive unit

[0082] 22: Boost circuit (signal output section)

[0083] 24: Components Department

[0084] 26: Switch (transfer unit)

[0085] 28: Control Unit (Switching Unit)

[0086] 31: First Resistor Section

[0087] 32: Second resistor section

[0088] 40: Protective switch

[0089] 51: Signal line

[0090] 51A: Signal line

[0091] 51B: Signal line

[0092] 81: First conductive path

[0093] 82: Second conductive path

[0094] 82A: Conductive circuit (one conductive circuit)

[0095] 82B: Conductive path (another conductive path)

[0096] 91: First Power Supply Section

[0097] 92: Second power supply section.

Claims

1. A drive device for driving a switching element in a circuit that supplies power from a power source to an electrical component as a load, the circuit comprising the switching element having a first terminal, a second terminal, and a third terminal, wherein the switching element is in an ON state when the potential difference between the first terminal and the third terminal is greater than or equal to a first threshold, and the switching element is in an OFF state when the potential difference between the first terminal and the third terminal is less than the first threshold. The drive device is equipped with a protection switch. The protection switch is located between the first terminal and the third terminal. When the voltage at the third terminal is above a second threshold, the protection switch is in an open state; when the voltage at the third terminal is below the second threshold, the protection switch is in an closed state. When the protection switch is in the ON state, the potential difference between the first terminal and the third terminal is lower than the first threshold. The drive device also includes: The signal output section outputs a high-level signal with a predetermined voltage. A signal line is disposed between the signal output section and the first terminal; A first resistor section is provided on the signal line; The second resistive section is different from the first resistive section; and The component section is disposed between the first resistor section and the second resistor section. One end of the component is electrically connected between the first resistor and the first terminal in the signal line. The other end of the component is electrically connected to the third terminal. One end of the second resistor is electrically connected to the third terminal. The other end of the second resistor is electrically connected to the reference conductive circuit. When the signal output section outputs a high-level signal, current flows from the signal output section to the reference conductive circuit via the first resistor section, the element section, and the second resistor section. The third terminal becomes a voltage above the second threshold, and due to the voltage drop generated at the element section, the potential difference between the first terminal and the third terminal becomes above the first threshold.

2. The driving device according to claim 1, wherein, The drive device includes a switching unit that switches the first terminal and the third terminal to a short-circuit state and a de-circuit state in which the short-circuit state is released. When the switching unit switches to the short-circuit state while the signal output unit outputs the high-level signal, the switching element becomes open. When the signal output section outputs the high-level signal, and the switching section maintains the deactivated state, current flows from the signal output section to the reference conductive circuit via the first resistor section, the element section, and the second resistor section. The third terminal becomes a voltage above the second threshold, and due to the voltage drop generated at the element section, the potential difference between the first terminal and the third terminal becomes above the first threshold, and the switching element becomes an ON state.

3. The driving device according to claim 1 or 2, wherein, The switching element is disposed between the first conductive path and the second conductive path. The second terminal is electrically connected to the first conductive path. The third terminal is electrically connected to the second conductive path. A first power supply unit is provided on the first conductive path side. A second power supply unit is provided on the second conductive path side. The drive device is a structure in which current flows between the first power supply unit and the second power supply unit, provided that at least the switching element is in an ON state. When the first power supply unit and the second power supply unit are connected, the state in which the voltage of the third terminal is above the second threshold is a normal state. When the first power supply unit and the second power supply unit are connected, the state in which the voltage of the third terminal is lower than the second threshold is an abnormal state.

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