Drive device

Abstract

The drive device (10) drives the motor (12) as a load. In a first current path of the current flowing through the motor (12), a first upstream switch (20u) is arranged on the upstream side of the motor (12), and a first downstream switch (20d) is arranged on the downstream side of the motor (12). In a second current path of the current flowing through the motor (12), a second upstream switch (21u) is arranged on the upstream side of the motor (12), and a second downstream switch (21d) is arranged on the downstream side of the motor (12). The direction of the current flowing through the motor (12) when the current flows through the first current path is different from the direction of the current flowing through the motor (12) when the current flows through the second current path. The first upstream drive circuit (24u) stops the flow of current via the first upstream switch (20u) when the current flowing through the first upstream switch (20u) reaches a current threshold or more.

Description

Technical Field

[0001] The present disclosure relates to a drive device.

[0002] This application claims the benefit of priority based on Japanese Application No. 2019-158596 filed on August 30, 2019, and all the contents described in the Japanese Application are incorporated herein by reference. Background Art

[0003] Patent document 1 discloses a vehicle drive device for driving an electric motor that rotates in forward and reverse directions. In the drive device, in a first current path of current flowing from a DC power supply through the electric motor, a first upstream switch is arranged on the upstream side of the electric motor, and a first downstream switch is arranged on the downstream side of the electric motor. Furthermore, in a second current path of current flowing from a DC power supply through the electric motor, a second upstream switch is arranged on the upstream side of the electric motor, and a second downstream switch is arranged on the downstream side of the electric motor. The direction of the current flowing through the electric motor when the current flows through the first current path is different from the direction of the current flowing through the electric motor when the current flows through the second current path.

[0004] The first upstream switch and the first downstream switch are switched on, and the second upstream switch and the second downstream switch are switched off. As a result, the current flows through the first current path, and the motor rotates in the forward direction. The first upstream switch and the first downstream switch are switched off, and the second upstream switch and the second downstream switch are switched on. As a result, the current flows through the second current path, and the motor rotates in the reverse direction.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2009-213234 Summary of the invention

[0008] A driving device involved in one embodiment of the present disclosure drives a load, wherein the device comprises: a first upstream switch, which is arranged on the upstream side of the load in a first current path of the current flowing through the load; a first downstream switch, which is arranged on the downstream side of the load in the first current path; a second upstream switch, which is arranged on the upstream side of the load in a second current path of the current flowing through the load; a second downstream switch, which is arranged on the downstream side of the load in the second current path; a current detection circuit, which detects the current flowing through the first upstream switch; and a stop circuit, which stops the flow of current through the first upstream switch when the current detected by the current detection circuit reaches a current threshold value or more, and the direction of the current flowing through the load when the current flows through the first current path is different from the direction of the current flowing through the load when the current flows through the second current path. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a block diagram showing a main part configuration of a power supply system in the first embodiment.

[0010] Figure 2 This is a block diagram showing the main structure of a microcomputer.

[0011] Figure 3 : is a flowchart showing the procedure of the motor driving process.

[0012] Figure 4 : is a flowchart showing the procedure of the motor driving process.

[0013] Figure 5 This is a flowchart showing the procedure of the motor stop process.

[0014] Figure 6 This is a timing chart showing the operation of the drive device when no failure occurs.

[0015] Figure 7 : is a timing chart showing the operation of the driving device when both ends of the first upstream switch are short-circuited.

[0016] Figure 8 : is a timing chart showing the operation of the driving device when both ends of the first downstream switch are short-circuited.

[0017] Fig. 9 : is a flowchart showing the procedure of the open circuit diagnosis process.

[0018] Fig.10 1 is a flowchart showing the procedure of the open circuit diagnosis process in the second embodiment.

[0019] Fig.111 is a timing chart showing the operation of the driving device when the first downstream switch is open.

[0020] Fig.12 : is a timing chart showing the operation of the driving device when the second upstream switch is open.

[0021] Fig.13 This is a block diagram showing a main part configuration of a power supply system in the third embodiment.

[0022] Fig.14 This is a block diagram showing the main structure of a microcomputer.

[0023] Fig.15 : is a flowchart showing the procedure of the open circuit diagnosis process.

[0024] Fig.16 This is a block diagram showing a main part configuration of a power supply system in a fourth embodiment.

[0025] Fig.17 is a circuit diagram of the first upstream driver circuit.

[0026] Fig.18 This is a block diagram showing a main part configuration of a power supply system in the fifth embodiment.

[0027] Fig.19 : is a flowchart showing the procedure of the motor driving process.

[0028] Fig. 20 This is a block diagram showing a main part configuration of a first current detection circuit in a sixth embodiment. DETAILED DESCRIPTION

[0029] [Problems to be Solved by the Present Disclosure]

[0030] In the conventional drive device described in Patent Document 1, when the first upstream switch and the second downstream switch are turned on, the DC power supply is short-circuited and a large current flows. If a large current continues to flow for a long time, various problems may occur.

[0031] As one of the structures for switching the first upstream switch, the first downstream switch, the second upstream switch, and the second downstream switch configured as in Patent Document 1 to on or off, a structure in which four drive circuits respectively switch the first upstream switch, the first downstream switch, the second upstream switch, and the second downstream switch to on or off is considered. In this structure, a microcomputer (hereinafter referred to as a microcomputer) instructs each drive circuit to switch on or off. In this case, since the microcomputer performs various processes, the timing at which the microcomputer instructs each drive circuit to switch on or off may be delayed from an appropriate timing.

[0032] In this case, the timing of switching to on or off is delayed from the appropriate timing for each of the first upstream switch, the first downstream switch, the second upstream switch, and the second downstream switch. As a result, there is a possibility that the first upstream switch and the second downstream switch are erroneously switched to on, and a large current may flow for a long time.

[0033] Therefore, an object of the present invention is to provide a driving device in which a large current does not flow for a long time even when an erroneous switching occurs.

[0034] [Effects of the present disclosure]

[0035] According to the present disclosure, even when erroneous switching occurs, a large current does not flow for a long time.

[0036] [Description of Embodiments of the Present Disclosure]

[0037] First, the embodiments of the present disclosure will be described by way of examples. At least a part of the embodiments described below may be arbitrarily combined.

[0038] (1) A driving device according to one embodiment of the present invention drives a load, wherein the device comprises: a first upstream switch, which is arranged on the upstream side of the load in a first current path of the current flowing through the load; a first downstream switch, which is arranged on the downstream side of the load in the first current path; a second upstream switch, which is arranged on the upstream side of the load in a second current path of the current flowing through the load; a second downstream switch, which is arranged on the downstream side of the load in the second current path; a current detection circuit, which detects the current flowing through the first upstream switch; and a stop circuit, which stops the flow of current through the first upstream switch when the current detected by the current detection circuit reaches or exceeds a current threshold, wherein the direction of the current flowing through the load when the current flows through the first current path is different from the direction of the current flowing through the load when the current flows through the second current path.

[0039] In the above-mentioned one embodiment, when the first upstream switch and the second downstream switch are switched on by mistake, a large current flows through the first upstream switch. At this time, since the current flowing through the first upstream switch exceeds the current threshold, the flow of the current through the first upstream switch is immediately stopped. Therefore, a large current does not flow through the first upstream switch for a long time.

[0040] (2) A driving device according to one embodiment of the present disclosure includes: a second current detection circuit for detecting a current flowing through the second upstream switch; and a second stop circuit for stopping the flow of current through the second upstream switch when the current detected by the second current detection circuit reaches or exceeds a second current threshold.

[0041] In the above-mentioned one embodiment, when the second upstream switch and the first downstream switch are switched on by mistake, a large current flows through the second upstream switch. At this time, since the current flowing through the second upstream switch exceeds the second current threshold, the flow of the current through the second upstream switch is immediately stopped. Therefore, a large current does not flow through the second upstream switch for a long time.

[0042] (3) In the drive device according to one aspect of the present disclosure, the stop circuit and the second stop circuit respectively switch the first upstream switch and the second upstream switch to off.

[0043] In the above-described aspect, the flow of current through the first upstream switch or the second upstream switch is stopped by switching the first upstream switch or the second upstream switch to off.

[0044] (4) A driving device according to one embodiment of the present invention comprises: a series circuit, in which a first resistor, a second resistor, and a circuit switch are connected in series, wherein a connection node between the first resistor and the second resistor is connected to a connection node between the load, a first downstream switch, and a second upstream switch, and a constant voltage is applied to the series circuit; a voltage detection circuit, in which a voltage is detected, in which a voltage at the connection node between the first resistor and the second resistor is detected; and a processing unit, in which a processing is performed, wherein the processing unit performs the following processing: switching the circuit switch to on or off, and detecting a fault in a circuit driving the load based on a voltage detected by the voltage detection circuit in an off indication state in which the first upstream switch, the first downstream switch, the second upstream switch, and the second downstream switch are switched to off.

[0045] In one of the above-mentioned embodiments, when the first upstream switch, the first downstream switch, the second upstream switch, and the second downstream switch are disconnected, when the circuit switch is turned on, the voltage detection circuit detects the voltage divided by the first resistor and the second resistor. When the first upstream switch, the first downstream switch, the second upstream switch, and the second downstream switch are disconnected, when the circuit switch is disconnected, the voltage detection circuit detects 0V or a constant voltage applied to the series circuit. When the voltage detected by the voltage detection circuit in the disconnection indication state indicating the switching of the first upstream switch, the first downstream switch, the second upstream switch, and the second downstream switch to disconnect is an abnormal voltage, a fault in the circuit driving the load is detected.

[0046] (5) In a driving device involved in one embodiment of the present disclosure, the circuit switch is configured on the upstream side of the first resistor or the second resistor, and the connection node connected to the voltage detection circuit is located on the downstream side of the circuit switch, and the processing unit performs the following processing: switching the circuit switch to off, and detecting a fault in the circuit driving the load when the voltage detected by the voltage detection circuit in the off indication state is above a specified voltage, and the specified voltage is higher than 0V.

[0047] In one embodiment described above, when the first upstream switch, the first downstream switch, the second upstream switch, and the second downstream switch are disconnected, when the circuit switch is disconnected, the voltage detection circuit detects 0 V. When the voltage detected by the voltage detection circuit is greater than a predetermined voltage when the circuit switch is disconnected in the disconnection indication state, a fault in the circuit driving the load is detected.

[0048] (6) In a driving device involved in one embodiment of the present invention, the processing unit performs the following processing: switching the circuit switch to on, and detecting a fault in the circuit driving the load when the voltage detected by the voltage detection circuit in the off indication state is less than a second specified voltage, wherein the second specified voltage is less than a voltage obtained by dividing the constant voltage by the first resistor and the second resistor.

[0049] In one of the above-mentioned modes, as described above, when the first upstream switch, the first downstream switch, the second upstream switch, and the second downstream switch are disconnected, when the circuit switch is turned on, the voltage detection circuit detects the voltage divided by the first resistor and the second resistor. Therefore, the voltage detected by the voltage detection circuit is usually above the second specified voltage. When the voltage detected by the voltage detection circuit is less than the second specified voltage when the circuit switch is turned on in the disconnection indication state, a fault in the circuit driving the load is detected.

[0050] (7) In a driving device involved in one embodiment of the present disclosure, the processing unit performs the following processing: detecting a fault in the circuit driving the load based on a voltage detected by the voltage detection circuit when the circuit switch is disconnected in a state where the first upstream switch and the first downstream switch are instructed to switch to on and the second upstream switch and the second downstream switch are instructed to switch to off, or when the circuit switch is disconnected in a state where the second upstream switch and the second downstream switch are instructed to switch to on and the first upstream switch and the first downstream switch are instructed to switch to off.

[0051] In one embodiment described above, when the circuit switch is off in a state where the first upstream switch and the first downstream switch are on and the second upstream switch and the second downstream switch are off, the voltage detection circuit detects a low voltage. Therefore, when the circuit switch is off in a state where the first upstream switch and the first downstream switch are instructed to switch on and the second upstream switch and the second downstream switch are instructed to switch off, if the voltage detected by the voltage detection circuit is high, a fault in the circuit driving the load is detected.

[0052] When the circuit switch is off in a state where the second upstream switch and the second downstream switch are on and the first upstream switch and the first downstream switch are off, the voltage detection circuit detects a high voltage. Therefore, when the circuit switch is off in a state where the second upstream switch and the second downstream switch are instructed to switch on and the first upstream switch and the first downstream switch are instructed to switch off, if the voltage detected by the voltage detection circuit is low, a fault in the circuit driving the load is detected.

[0053] (8) A driving device according to one embodiment of the present disclosure includes a processing unit that performs processing, and the processing unit performs the following processing: when the current detected by the current detection circuit is less than a specified current in a state indicating that the first upstream switch and the first downstream switch are switched to be turned on, a fault in the circuit driving the load is detected.

[0054] In the above-described aspect, when the current flowing through the first current path is small despite the instruction to switch the first upstream switch and the first downstream switch to on, a failure of the circuit driving the load is detected.

[0055] (9) A driving device according to one embodiment of the present invention includes a processing unit for performing processing, wherein the load is a motor, and the processing unit performs the following processing: while instructing the first upstream switch and the first downstream switch to switch to on, or instructing the second upstream switch and the second downstream switch to switch to on, obtaining rotation information related to the rotation of the motor, determining whether the load is rotating based on the obtained rotation information, and detecting a fault in a circuit driving the load when it is determined that the load is not rotating.

[0056] In one of the above-mentioned embodiments, when the first upstream switch and the first downstream switch are turned on, or the second upstream switch and the second downstream switch are turned on, the motor rotates. When the motor does not rotate despite the instruction to switch the first upstream switch and the first downstream switch to turn on, or the instruction to switch the second upstream switch and the second downstream switch to turn on, a fault in the circuit driving the load is detected.

[0057] [Details of the embodiments of the present disclosure]

[0058] Hereinafter, a specific example of the power supply system involved in the embodiment of the present disclosure will be described with reference to the accompanying drawings. In addition, the present invention is not limited to these examples, but is shown by the scope of the invention claims, and is intended to include all changes within the meaning and scope equivalent to the scope of the invention claims.

[0059] (Implementation Method 1)

[0060] <Power supply system configuration>

[0061] Figure 1 1 is a block diagram showing a main part structure of a power supply system 1 in Embodiment 1. The power supply system 1 is preferably mounted on a vehicle and includes a drive device 10, a battery 11, and a motor 12. The positive electrode of the battery 11 and both ends of the motor 12 are connected to the drive device 10, respectively. The negative electrodes of the drive device 10 and the battery 11 are grounded.

[0062] The drive device 10 controls the supply of power from the battery 11 to the motor 12, and controls the direction of the current flowing through the motor 12. When power is supplied to the motor 12, the motor 12 rotates. The rotation of the motor 12 specifically means the rotation of the rotor of the motor 12. The motor 12 opens and closes the window of the vehicle, for example. The drive device 10 drives the motor 12. The motor 12 is one of the loads driven by the drive device 10.

[0063] The drive device 10 supplies power to the motor 12 and controls the direction of the current flowing through the motor 12 to a first current direction, for example, Figure 1 At this time, the motor 12 rotates in the positive direction, for example, the window is opened. The drive device 10 supplies power to the motor 12 and controls the direction of the current flowing through the motor 12 to the second current direction, for example, Figure 1 At this time, the motor 12 rotates in the reverse direction, for example, the window is closed. The drive device 10 stops supplying power to the motor 12. As a result, the motor 12 stops operating.

[0064] <Structure of the driving device 10>

[0065] The driving device 10 includes a first upstream switch 20u, a first downstream switch 20d, a second upstream switch 21u, a second downstream switch 21d, shunt resistors 22a, 22b, a load resistor 23, a first upstream drive circuit 24u, a first downstream drive circuit 24d, a second upstream drive circuit 25u, a second downstream drive circuit 25d, a first current detection circuit 26a, a second current detection circuit 26b, a microcomputer 27, a diagnosis switch 28, diagnosis resistors 29, 30, and a voltage detection circuit 31. The first upstream switch 20u, the first downstream switch 20d, the second upstream switch 21u, and the second downstream switch 21d are N-channel FETs (Field Effect Transistors).

[0066] The drain of the first upstream switch 20u is connected to the positive electrode of the battery 11. The source of the first upstream switch 20u is connected to one end of the shunt resistor 22a. The other end of the shunt resistor 22a is connected to the motor 12 and one end of the load resistor 23. The other ends of the motor 12 and the load resistor 23 are connected to the drain of the first downstream switch 20d. The source of the first downstream switch 20d is grounded.

[0067] The gates of the first upstream switch 20u and the first downstream switch 20d are connected to the first upstream drive circuit 24u and the first downstream drive circuit 24d. Both ends of the shunt resistor 22a are connected to the first current detection circuit 26a. The first current detection circuit 26a is connected to the first upstream drive circuit 24u and the microcomputer 27. The first upstream drive circuit 24u and the first downstream drive circuit 24d are also connected to the microcomputer 27.

[0068] Similarly, the drain of the second upstream switch 21u is connected to the positive electrode of the battery 11. The source of the second upstream switch 21u is connected to one end of the shunt resistor 22b. The other end of the shunt resistor 22b is connected to the other end of the motor 12 and the load resistor 23. One end of the motor 12 and the load resistor 23 is connected to the drain of the second downstream switch 21d. The source of the second downstream switch 21d is grounded.

[0069] The gates of the second upstream switch 21u and the second downstream switch 21d are connected to the second upstream drive circuit 25u and the second downstream drive circuit 25d. The two ends of the shunt resistor 22b are connected to the second current detection circuit 26b. The second current detection circuit 26b is connected to the second upstream drive circuit 25u and the microcomputer 27. The second upstream drive circuit 25u and the second downstream drive circuit 25d are also connected to the microcomputer 27.

[0070] A constant voltage Vcc is applied to one end of the diagnostic switch 28. The other end of the diagnostic switch 28 is connected to one end of a diagnostic resistor 29. The other end of the diagnostic resistor 29 is connected to one end of a diagnostic resistor 30. The other end of the diagnostic resistor 30 is grounded.

[0071] As described above, the diagnostic switch 28 and the diagnostic resistors 29 and 30 are connected in series, and the diagnostic switch 28 and the diagnostic resistors 29 and 30 form a series circuit. A constant voltage Vcc is applied to the series circuit. The diagnostic switch 28 and the diagnostic resistors 29 and 30 function as a circuit switch, a first resistor, and a second resistor, respectively.

[0072] The connection node between the diagnostic resistors 29 and 30 is connected to the other end of the motor 12 and the load resistor 23 and the voltage detection circuit 31. Therefore, the connection node between the diagnostic resistors 29 and 30 is connected to the connection node between the motor 12, the load resistor 23, the first downstream switch 20d and the second upstream switch 21u. The voltage detection circuit 31 is also connected to the microcomputer 27.

[0073] The first upstream switch 20u, the first downstream switch 20d, the second upstream switch 21u, and the second downstream switch 21d are respectively turned on when the voltage of the gate based on the potential of the source is greater than a certain value. At this time, the current can flow through the drain and the source. The first upstream switch 20u, the first downstream switch 20d, the second upstream switch 21u, and the second downstream switch 21d are respectively turned off when the voltage of the gate based on the potential of the source is less than a certain value. At this time, the current does not flow through the drain and the source.

[0074] The microcomputer 27 outputs an on instruction to instruct switching to on and an off instruction to instruct switching to off to the first upstream driver circuit 24u, the first downstream driver circuit 24d, the second upstream driver circuit 25u, and the second downstream driver circuit 25d, respectively.

[0075] When an on instruction is input, the first upstream drive circuit 24u increases the gate voltage of the first upstream switch 20u based on the ground potential. As a result, in the first upstream switch 20u, the gate voltage based on the source potential increases to a voltage greater than a certain value, and the first upstream switch 20u is switched on. When an off instruction is input, the first upstream drive circuit 24u decreases the gate voltage of the first upstream switch 20u based on the ground potential. As a result, in the first upstream switch 20u, the gate voltage based on the source potential decreases to a voltage less than a certain value, and the first upstream switch 20u is switched off. As described above, the first upstream drive circuit 24u switches the first upstream switch 20u on or off according to the instruction input from the microcomputer 27.

[0076] The first downstream drive circuit 24d, the second upstream drive circuit 25u and the second downstream drive circuit 25d respectively switch the first downstream switch 20d, the second upstream switch 21u and the second downstream switch 21d on or off in accordance with instructions input from the microcomputer 27, similarly to the first upstream drive circuit 24u.

[0077] When the first upstream drive circuit 24u and the first downstream drive circuit 24d switch the first upstream switch 20u and the first downstream switch 20d to be turned on while the second upstream switch 21u and the second downstream switch 21d are turned off, the current flows from the positive electrode of the battery 11 through the first upstream switch 20u and the shunt resistor 22a in sequence, and then is input to the motor 12 and one end of the load resistor 23. The current output from the other end of the motor 12 and the load resistor 23 flows through the first downstream switch 20d and returns to the negative electrode of the battery 11. At this time, the current flows in the motor 12 in the first current direction. As a result, power is supplied to the motor 12, and the motor 12 rotates in the positive direction.

[0078] As described above, when the first upstream switch 20u and the first downstream switch 20d are turned on, current flows through the shunt resistor 22a. The first current detection circuit 26a detects the current flowing through the shunt resistor 22a, that is, the first current flowing through the first upstream switch 20u. The first current detection circuit 26a outputs first current information indicating the detected first current to the first upstream drive circuit 24u and the microcomputer 27. The first current information is, for example, a voltage proportional to the first current. The first current information output by the first current detection circuit 26a is an analog value.

[0079] During the period when the first current represented by the first current information input from the first current detection circuit 26a to the first upstream drive circuit 24u is less than the first current threshold, the first upstream drive circuit 24u switches the first upstream switch 20u to on or off according to the instruction input from the microcomputer 27. When the first current represented by the first current information input from the first current detection circuit 26a to the first upstream drive circuit 24u reaches or exceeds the first current threshold, the first upstream drive circuit 24u switches the first upstream switch 20u to off regardless of the instruction input from the microcomputer 27, and maintains the first upstream switch 20u to off. As a result, the flow of current through the first upstream switch 20u is stopped. The first upstream drive circuit 24u functions as a stop circuit. The first current threshold is greater than the current flowing through the shunt resistor 22a when the first upstream switch 20u and the first downstream switch 20d are on and the second upstream switch 21u and the second downstream switch 21d are off.

[0080] The path of the current that flows from the positive electrode of the battery 11 through the first upstream switch 20u, the shunt resistor 22a, the motor 12, and the first downstream switch 20d in sequence corresponds to the first current path. In the first current path, the first upstream switch 20u is arranged on the upstream side of the motor 12, and the first downstream switch 20d is arranged on the downstream side of the motor 12.

[0081] When the second upstream drive circuit 25u and the second downstream drive circuit 25d switch the second upstream switch 21u and the second downstream switch 21d to be turned on while the first upstream switch 20u and the first downstream switch 20d are turned off, the current flows from the positive electrode of the battery 11 through the second upstream switch 21u and the shunt resistor 22b in sequence, and then is input to the other end of the motor 12 and the load resistor 23. The current output from one end of the motor 12 and the load resistor 23 flows through the second downstream switch 21d and returns to the negative electrode of the battery 11. At this time, the current flows in the second current direction in the motor 12. As a result, power is supplied to the motor 12, and the motor 12 rotates in the reverse direction.

[0082] As described above, when the second upstream switch 21u and the second downstream switch 21d are turned on, current flows through the shunt resistor 22b. The second current detection circuit 26b detects the current flowing through the shunt resistor 22b, that is, the second current flowing through the second upstream switch 21u. The second current detection circuit 26b outputs second current information indicating the detected second current to the second upstream drive circuit 25u and the microcomputer 27. The second current information is, for example, a voltage proportional to the current flowing through the shunt resistor 22b. The second current information output by the second current detection circuit 26b is an analog value.

[0083] During the period when the current represented by the second current information input from the second current detection circuit 26b to the second upstream drive circuit 25u is less than the second current threshold, the second upstream drive circuit 25u switches the second upstream switch 21u to on or off according to the instruction input from the microcomputer 27. When the second current represented by the second current information input from the second current detection circuit 26b to the second upstream drive circuit 25u reaches or exceeds the second current threshold, the second upstream drive circuit 25u switches the second upstream switch 21u to off regardless of the instruction input from the microcomputer 27, and maintains the second upstream switch 21u to off. Thus, the flow of current through the second upstream switch 21u is stopped. The second upstream drive circuit 25u functions as a second stop circuit. The second current threshold is greater than the current flowing through the shunt resistor 22b when the second upstream switch 21u and the second downstream switch 21d are on and the first upstream switch 20u and the first downstream switch 20d are off.

[0084] The path of the current that flows from the positive electrode of the battery 11 through the second upstream switch 21u, the shunt resistor 22b, the motor 12, and the second downstream switch 21d in sequence corresponds to the second current path. In the second current path, the second upstream switch 21u is arranged on the upstream side of the motor 12, and the second downstream switch 21d is arranged on the downstream side of the motor 12. When the current flows through the first current path, the direction of the current flowing through the motor 12 is the first current direction. When the current flows through the second current path, the direction of the current flowing through the motor 12 is the second current direction, which is different from the first current direction.

[0085] The microcomputer 27 switches the diagnostic switch 28 on or off. When the diagnostic switch 28 is on, current flows through the diagnostic switch 28 and the diagnostic resistors 29 and 30 in sequence. Therefore, the diagnostic switch 28 is arranged on the upstream side of the diagnostic resistors 29 and 30, and the connection node to which the voltage detection circuit 31 is connected is located on the downstream side of the diagnostic switch 28. The diagnostic resistors 29 and 30 divide the constant voltage Vcc. The voltage detection circuit 31 detects the voltage of the connection node between the diagnostic resistors 29 and 30 based on the ground potential, and outputs voltage information representing the detected detection voltage to the microcomputer 27. The voltage information is, for example, a voltage proportional to the detection voltage detected by the voltage detection circuit 31. The voltage information output by the voltage detection circuit 31 is an analog value.

[0086] The microcomputer 27 receives input of a forward rotation signal for instructing the motor 12 to rotate in the forward direction, a reverse rotation signal for instructing the motor 12 to rotate in the reverse direction, and a stop signal for instructing the motor 12 to stop its operation.

[0087] When a forward rotation signal is input to the microcomputer 27, the microcomputer 27 outputs an on instruction to the first upstream drive circuit 24u and the first downstream drive circuit 24d. As a result, the first upstream drive circuit 24u and the first downstream drive circuit 24d respectively switch the first upstream switch 20u and the first downstream switch 20d to on. As a result, the current in the first current direction flows through the motor 12, and the motor 12 rotates in the forward direction.

[0088] When the reverse signal is input to the microcomputer 27, the microcomputer 27 outputs an on instruction to the second upstream drive circuit 25u and the second downstream drive circuit 25d. As a result, the second upstream drive circuit 25u and the second downstream drive circuit 25d respectively switch the second upstream switch 21u and the second downstream switch 21d to on. As a result, the current in the second current direction flows through the motor 12, and the motor 12 rotates in the reverse direction.

[0089] When a stop signal is input to the microcomputer 27, the microcomputer 27 outputs a disconnection instruction to the first upstream drive circuit 24u and the second upstream drive circuit 25u. As a result, the first upstream drive circuit 24u and the second upstream drive circuit 25u respectively switch the first upstream switch 20u and the second upstream switch 21u to be disconnected. As a result, the power supply to the motor 12 is stopped, and the operation of the motor 12 stops.

[0090] After outputting a disconnection instruction to the first upstream drive circuit 24u and the second upstream drive circuit 25u, the microcomputer 27 outputs a connection instruction to the first downstream drive circuit 24d and the second downstream drive circuit 25d. As a result, the first downstream drive circuit 24d and the second downstream drive circuit 25d respectively switch the first downstream switch 20d and the second downstream switch 21d to be connected when the first upstream switch 20u and the second upstream switch 21u are in the disconnected state. The motor 12 has an inductor. While the motor 12 is operating, a current flows through the inductor in the motor 12, and energy is stored in the inductor.

[0091] While the first upstream switch 20u and the second upstream switch 21u are off and the first downstream switch 20d and the second downstream switch 21d are on, current flows from the inductor of the motor 12 through the first downstream switch 20d and the second downstream switch 21d. Therefore, the inductor releases stored energy.

[0092] After a certain period of time has passed since the microcomputer 27 outputted the on instruction to the first downstream drive circuit 24d and the second downstream drive circuit 25d, the microcomputer 27 outputs the off instruction to the first downstream drive circuit 24d and the second downstream drive circuit 25d. Thus, when the first upstream switch 20u and the second upstream switch 21u are in the off state, the first downstream drive circuit 24d and the second downstream drive circuit 25d respectively switch the first downstream switch 20d and the second downstream switch 21d to be off.

[0093] The microcomputer 27 detects a fault in the circuit of the drive motor 12 based on the first current information, the second current information, and the voltage information input from the first current detection circuit 26a, the second current detection circuit 26b, and the voltage detection circuit 31. When the microcomputer 27 detects a fault, it outputs a fault signal indicating the fault in the circuit of the drive motor 12. Thus, the fault is notified.

[0094] <Structure of Microcomputer 27>

[0095] Figure 22 is a block diagram showing a main part structure of the microcomputer 27. The microcomputer 27 includes output units 40u, 40d, 41u, 41d, a switching unit 42, a signal output unit 43, A / D converters 44a, 44b, 45, an input unit 46, 47a, 47b, 48, a storage unit 49, and a control unit 50. The output units 40u, 40d, 41u, 41d, the switching unit 42, the signal output unit 43, the A / D converters 44a, 44b, 45, the input unit 46, the storage unit 49, and the control unit 50 are connected to an internal bus 51.

[0096] The output units 40u, 40d, 41u, and 41d are also connected to the first upstream drive circuit 24u, the first downstream drive circuit 24d, the second upstream drive circuit 25u, and the second downstream drive circuit 25d, respectively. The A / D converters 44a, 44b, and 45 are also connected to the input units 47a, 47b, and 48, respectively. The input units 47a, 47b, and 48 are also connected to the first current detection circuit 26a, the second current detection circuit 26b, and the voltage detection circuit 31, respectively.

[0097] The output units 40u, 40d, 41u, and 41d respectively output an on instruction or an off instruction to the first upstream drive circuit 24u, the first downstream drive circuit 24d, the second upstream drive circuit 25u, and the second downstream drive circuit 25d according to the instruction of the control unit 50. The switching unit 42 switches the diagnostic switch 28 on or off according to the instruction of the control unit 50. The signal output unit 43 outputs a fault signal according to the instruction of the control unit 50.

[0098] The analog first current information is input from the first current detection circuit 26a to the input unit 47a. The input unit 47a outputs the analog first current information input from the first current detection circuit 26a to the A / D conversion unit 44a. The A / D conversion unit 44a converts the analog first current information input from the input unit 47a into digital first current information. The control unit 50 obtains the digital first current information from the A / D conversion unit 44a. The first current represented by the first current information obtained by the control unit 50 is substantially consistent with the first current detected by the first current detection circuit 26a at the time of acquisition.

[0099] Similarly, analog second current information is input from the second current detection circuit 26b to the input unit 47b. The input unit 47b outputs the analog second current information input from the second current detection circuit 26b to the A / D conversion unit 44b. The A / D conversion unit 44b converts the analog second current information input from the input unit 47b into digital second current information. The control unit 50 obtains the digital second current information from the A / D conversion unit 44b. The second current represented by the second current information obtained by the control unit 50 is substantially consistent with the second current detected by the second current detection circuit 26b at the time of acquisition.

[0100] The analog voltage information is input from the voltage detection circuit 31 to the input unit 48. The input unit 48 outputs the analog voltage information input from the voltage detection circuit 31 to the A / D conversion unit 45. The A / D conversion unit 45 converts the analog voltage information input from the input unit 48 into digital voltage information. The detection voltage represented by the voltage information acquired by the control unit 50 is substantially consistent with the detection voltage detected by the voltage detection circuit 31 at the acquisition time point.

[0101] The forward rotation signal, the reverse rotation signal, and the stop signal are input to the input unit 46. When a signal is input to the input unit 46, the input unit 46 notifies the control unit 50 of the input signal.

[0102] The storage unit 49 is a nonvolatile memory. The storage unit 49 stores a computer program P. The control unit 50 has a processing element for executing processing, such as a CPU (Central Processing Unit). The processing element of the control unit 50 executes the motor drive processing, the motor stop processing, and the open circuit detection processing by executing the computer program P. The control unit 50 functions as a processing unit.

[0103] The motor drive process is a process for driving the motor 12. The motor stop process is a process for stopping the operation of the motor 12. The open circuit detection process is a process for detecting an open circuit in the circuit for driving the motor 12.

[0104] The number of processing elements included in the control unit 50 may be two or more. In this case, the plurality of processing elements may cooperate to execute the motor driving process, the motor stopping process, and the open circuit detection process.

[0105] In addition, the computer program P may be provided to the microcomputer 27 using a non-temporary storage medium E storing the computer program P in a readable manner. The storage medium E is, for example, a portable storage such as a CD (Compact Disc)-ROM (Read Only Memory), a USB (Universal Serial Bus) memory, an SD (Secure Digital) card, a micro SD card, or a Compact Flash (registered trademark). In this case, the control unit 50 may read the computer program P from the storage medium E using a reading device not shown, and install the read computer program P in the storage unit 49. Furthermore, in the case where the microcomputer 27 is provided with a communication unit for communicating with an external device, the computer program P may be provided to the microcomputer 27 by communication via the communication unit. In this case, the control unit 50 may obtain the computer program P through the communication unit, and install the obtained computer program P in the storage unit 49.

[0106] The value of the flag is stored in the storage unit 49. The value of the flag is 0 or 1. The control unit 50 changes the value of the flag to 0 or 1. The value of the flag being 0 means a disconnection indication state in which a disconnection indication is output to the first upstream drive circuit 24u, the first downstream drive circuit 24d, the second upstream drive circuit 25u, and the second downstream drive circuit 25d. Therefore, when the drive device 10 is normal, when the value of the flag is 0, the motor 12 stops operating.

[0107] The value of the flag is 1, which means that an on-indication state is output to the first upstream drive circuit 24u and the first downstream drive circuit 24d, or an on-indication state is output to the second upstream drive circuit 25u and the second downstream drive circuit 25d. Therefore, when the drive device 10 is normal, when the value of the flag is 1, the motor 12 rotates in the forward direction or the reverse direction.

[0108] <Motor drive processing>

[0109] Figure 3 and Figure 4 4 is a flowchart showing the process of the motor drive process. When the forward rotation signal or the reverse rotation signal is input to the input unit 46, the control unit 50 executes the motor drive process. The motor drive process is executed when the diagnostic switch 28 is turned off. In the motor drive process, the control unit 50 first determines whether the value of the flag is 0 (step S1).

[0110] When the control unit 50 determines that the value of the flag is not 0, that is, the value of the flag is 1 (S1: No), the control unit 50 instructs the output units 40u and 41u to output a disconnection instruction to the first upstream drive circuit 24u and the second upstream drive circuit 25u (step S2). When the drive device 10 is normal, by executing step S2, the first upstream drive circuit 24u and the second upstream drive circuit 25u respectively switch the first upstream switch 20u and the second upstream switch 21u to disconnect, and the motor 12 stops operating.

[0111] Next, the control unit 50 instructs the output units 40d and 41d to output an on instruction to the first downstream drive circuit 24d and the second downstream drive circuit 25d (step S3). When the drive device 10 is normal, by executing step S3, the first downstream drive circuit 24d and the second downstream drive circuit 25d respectively switch the first downstream switch 20d and the second downstream switch 21d to on. As a result, the inductor of the motor 12 releases energy.

[0112] Next, the control unit 50 determines whether a predetermined period has passed since the execution of step S3 (step S4). The microcomputer 27 may also have a timer. In this case, the control unit 50 starts the timer after executing step S3. In step S4, the control unit 50 determines whether a certain period has passed based on whether the time measured by the timer is longer than the certain period. If the control unit 50 determines that the certain period has not passed (S4: No), the control unit 50 executes step S4 again and waits until the certain period has passed. The certain period is preferably longer than the period during which the inductor releases all the stored energy.

[0113] When the control unit 50 determines that a certain period has passed (S4: Yes), the output units 40d and 41d output disconnection instructions to the first downstream drive circuit 24d and the second downstream drive circuit 25d (step S5). When the timer is timing, the control unit 50 stops the timer after executing step S5. When the drive device 10 is normal, by executing step S5, when the first upstream switch 20u and the second upstream switch 21u are in the disconnected state, the first downstream drive circuit 24d and the second downstream drive circuit 25d respectively switch the first downstream switch 20d and the second downstream switch 21d to disconnect. When step S5 is executed, the state of the microcomputer 27 becomes a disconnection instruction state in which a disconnection instruction is output to the first upstream drive circuit 24u, the first downstream drive circuit 24d, the second upstream drive circuit 25u and the second downstream drive circuit 25d.

[0114] When the value of the flag is 1, when the forward rotation signal or the reverse rotation signal is input to the input unit 46, the motor drive process is executed, and the control unit 50 changes the direction of rotation of the motor 12. As described above, in the motor drive process, when the direction of rotation of the motor 12 is changed, that is, when the value of the flag is 1, steps S2 to S5 are executed, and a period during which the first upstream switch 20u, the first downstream switch 20d, the second upstream switch 21u, and the second downstream switch 21d are turned off is set. In this way, the first upstream switch 20u and the second downstream switch 21d are prevented from being turned on, or the second upstream switch 21u and the first downstream switch 20d are prevented from being turned on.

[0115] When the control unit 50 determines that the value of the flag is 0 (S1: Yes), or after executing step S5, the control unit 50 obtains voltage information from the A / D conversion unit 45 (step S6). As described above, the voltage information indicates the detection voltage detected by the voltage detection circuit 31. When the drive device 10 is normal, at the time of executing step S6, the current does not flow through the diagnostic resistor 30. Therefore, the detection voltage indicated by the voltage information obtained by the control unit 50 in step S6 is 0V.

[0116] The resistance value of the diagnostic resistor 30 is sufficiently larger than the resistance values ​​of the shunt resistors 22a, 22b and the load resistor 23. It is assumed that both ends of the first upstream switch 20u or the second upstream switch 21u are short-circuited, or the resistance value between the drain and the source of the first upstream switch 20u or the second upstream switch 21u is fixed to a value that is neither too high nor too low, or the connection node between the first upstream switch 20u and the first downstream switch 20d or the connection node between the second upstream switch 21u and the second downstream switch 21d is in contact with the drain of the first upstream switch 20u.

[0117] In this case, at the time point of executing step S6, the detection voltage detected by the voltage detection circuit 31 is substantially consistent with the voltage between the two ends of the battery 11 (hereinafter referred to as the battery voltage). A fault in which the resistance value between the drain and the source is fixed to a value that is neither too high nor too low is called a half-connection. When the first upstream switch 20u and the second upstream switch 21u are half-connected, the resistance value between the drain and the source of each of the first upstream switch 20u and the second upstream switch 21u is sufficiently smaller than the resistance value of the diagnostic resistor 30. A fault in which the connection node between the first upstream switch 20u and the first downstream switch 20d, or the connection node between the second upstream switch 21u and the second downstream switch 21d contacts the drain of the first upstream switch 20u is called a power supply short circuit.

[0118] The storage unit 49 stores a voltage threshold value to be compared with the detection voltage in advance. The voltage threshold value is a constant value and is higher than 0V. In addition, the voltage threshold value is less than the voltage obtained by dividing the constant voltage Vcc by the diagnostic resistors 29 and 30. The constant voltage Vcc is generated by reducing the battery voltage and is therefore lower than the battery voltage. Therefore, the voltage threshold value is lower than the battery voltage.

[0119] The control unit 50 determines whether the detection voltage indicated by the voltage information obtained in step S6 is greater than the voltage threshold (step S7). The detection voltage being greater than the voltage threshold means that a fault has occurred in the circuit driving the motor 12. The control unit 50 detects a fault in the circuit driving the motor 12 by executing step S7. When the control unit 50 determines that the detection voltage is greater than the voltage threshold (S7: Yes), it is deemed that a fault has been detected, and the signal output unit 43 is instructed to output a fault signal (step S8), and the motor drive process is terminated. The voltage threshold functions as a specified voltage.

[0120] When the control unit 50 determines that the detection voltage is lower than the voltage threshold ( S7 : NO), it instructs the switching unit 42 to switch the diagnosis switch 28 on (step S9 ), and acquires the voltage information from the A / D converter 45 (step S10 ).

[0121] When the drive device 10 is normal, at the time of executing step S10, the diagnostic resistors 29 and 30 are dividing the constant voltage Vcc. Therefore, the detection voltage represented by the voltage information obtained in step S10 is the voltage divided by the diagnostic resistors 29 and 30. For example, when the resistance values ​​of the diagnostic resistors 29 and 30 are the same, the detection voltage is (constant voltage Vcc) / 2.

[0122] As described above, the voltage threshold is equal to or lower than the voltage obtained by dividing the constant voltage Vcc by the diagnostic resistors 29 and 30. Therefore, when the drive device 10 is normal, the detection voltage indicated by the voltage information acquired by the control unit 50 in step S10 is equal to or higher than the voltage threshold.

[0123] Assume that both ends of the first downstream switch 20d or the second downstream switch 21d are short-circuited, or the first downstream switch 20d or the second downstream switch 21d is half-on, or the connection node between the first upstream switch 20u and the first downstream switch 20d or the connection node between the second upstream switch 21u and the second downstream switch 21d is grounded. When the first downstream switch 20d and the second downstream switch 21d are half-on, the resistance value between the drain and the source of each of the first downstream switch 20d and the second downstream switch 21d is sufficiently smaller than the resistance value of the diagnosis resistor 30. A fault in which the connection node between the first upstream switch 20u and the first downstream switch 20d or the connection node between the second upstream switch 21u and the second downstream switch 21d is grounded is a so-called ground short.

[0124] When both ends of the first downstream switch 20d or the second downstream switch 21d are short-circuited, or the first downstream switch 20d or the second downstream switch 21d is half-connected, or a ground short circuit occurs, at the time point of executing step S10, the detection voltage detected by the voltage detection circuit 31 is a value close to 0V, which is less than the voltage threshold.

[0125] The control unit 50 determines whether the detection voltage represented by the voltage information obtained in step S10 is less than the voltage threshold (step S11). The detection voltage being less than the voltage threshold means that a fault has occurred in the circuit driving the motor 12. The control unit 50 detects the fault in the circuit driving the motor 12 by executing step S11. When the control unit 50 determines that the detection voltage is less than the voltage threshold (S11: Yes), the switching unit 42 switches the diagnostic switch 28 to off (step S12), and deems that a fault has been detected, and instructs the signal output unit 43 to output a fault signal (step S13). After executing step S13, the control unit 50 ends the motor drive process. The voltage threshold also functions as a second specified voltage.

[0126] When the control unit 50 determines that the detection voltage is above the voltage threshold (S11: No), the switching unit 42 switches the diagnostic switch 28 to off (step S14), and determines whether the signal input to the input unit 46 is a forward rotation signal (step S15). When the control unit 50 determines that the signal is a forward rotation signal (S15: Yes), the output unit 40u and 40d are instructed to output a connection instruction to the first upstream drive circuit 24u and the first downstream drive circuit 24d (step S16). When the drive device 10 is normal, when step S16 is executed, the first upstream switch 20u and the first downstream switch 20d are switched to on. As a result, the current in the first current direction flows through the motor 12, and the motor 12 rotates in the forward direction.

[0127] In addition, in step S16, the control unit 50 may also make the other of the output units 40u and 40d alternately and repeatedly output an on-indication and an off-indication while fixing the output of one of the output units 40u and 40d to an on-indication. In this case, the switching between on and off is alternately performed in one of the first upstream switch 20u and the first downstream switch 20d to realize PWM (Pulse Width Modulation) control. Since the first upstream drive circuit 24u has a function of switching the first upstream switch 20u to off based on the first current detected by the first current detection circuit 26a, the time until the on-indication or the off-indication is input to the first upstream drive circuit 24u and the first upstream drive circuit 24u switches the first upstream switch 20u to on or off is relatively long. Therefore, it is preferred that the control unit 50 realizes PWM control by making the output unit 40d alternately and repeatedly output an on-indication and an off-indication.

[0128] When the control unit 50 determines that the signal is not a forward rotation signal, that is, the signal is a reverse rotation signal (S15: No), the control unit 50 instructs the output units 41u and 41d to output a turn-on instruction to the second upstream drive circuit 25u and the second downstream drive circuit 25d (step S17). When the drive device 10 is normal, when step S17 is executed, the second upstream switch 21u and the second downstream switch 21d are switched on. As a result, the current in the second current direction flows through the motor 12, and the motor 12 rotates in the reverse direction.

[0129] In addition, in step S17, the control unit 50 may also make the other of the output units 41u and 41d alternately and repeatedly output an on-indication and an off-indication while fixing the output of one of the output units 41u and 41d to an on-indication. In this case, the switching between on and off is alternately performed in one of the second upstream switch 21u and the second downstream switch 21d to realize PWM control. Since the second upstream drive circuit 25u has a function of switching the second upstream switch 21u to off based on the second current detected by the second current detection circuit 26b, the time until the on-indication or the off-indication is input to the second upstream drive circuit 25u and the second upstream drive circuit 25u switches the second upstream switch 21u to on or off is relatively long. Therefore, it is preferred that the control unit 50 realizes PWM control by making the output unit 41d alternately and repeatedly output an on-indication and an off-indication.

[0130] After executing one of steps S16 and S17, the control unit 50 changes the value of the flag to 1 (step S18) and ends the motor drive process. When the value of the flag is 1 at the time of executing step S18, the control unit 50 omits the execution of step S18. The drive process ends when the diagnosis switch 28 is turned off.

[0131] <Motor stop processing>

[0132] Figure 5 4 is a flowchart showing the process of the motor stop process. The control unit 50 performs the motor stop process when the stop signal is input to the input unit 46. In the motor stop process, the control unit 50 sequentially performs steps S21 to S24. Steps S21 to S24 of the motor stop process are respectively the same as steps S2 to S5 of the motor drive process. Therefore, detailed descriptions of steps S21 to S24 are omitted.

[0133] When the control unit 50 executes steps S21 to S24 in a normal state of the drive device 10, first, the first upstream switch 20u and the second upstream switch 21u are switched off, and the operation of the motor 12 stops. Then, the first downstream switch 20d and the second downstream switch 21d are kept on for a certain period of time, and the energy stored in the inductor of the motor 12 is released. After the certain period of time, the second upstream switch 21u and the second downstream switch 21d are switched off while the first upstream switch 20u and the second upstream switch 21u are in the off state.

[0134] After executing step S24, the control unit 50 changes the value of the flag to 0 (step S25) and ends the motor stop process. The motor stop process starts when the diagnosis switch 28 is turned off and ends when the diagnosis switch 28 is kept turned off.

[0135] <Operation of the driving device 10>

[0136] Figure 6 is a timing chart showing the operation of the drive device 10 when no failure occurs. Figure 6 4 shows the transition of the instructions of the first upstream driver circuit 24u, the first downstream driver circuit 24d, the second upstream driver circuit 25u and the second downstream driver circuit 25d output by the output units 40u, 40d, 41u and 41d. Figure 6 2 also shows the transition of the state of the diagnosis switch 28 and the transition of the detection voltage detected by the voltage detection circuit 31. Vth represents a voltage threshold.

[0137] Assume that in the state where the value of the flag is 0, that is, in the state where the disconnection indication is output to the first upstream drive circuit 24u, the first downstream drive circuit 24d, the second upstream drive circuit 25u, and the second downstream drive circuit 25d, the forward rotation signal is input to the input unit 46 of the microcomputer 27. When the forward rotation signal or the reverse rotation signal is input to the input unit 46, the control unit 50 of the microcomputer 27 performs the motor drive process. In the state where the diagnostic switch is disconnected, the detection voltage is 0V, which is less than the voltage threshold Vth. Therefore, the control unit 50 diagnoses that there is no short circuit at both ends of the first upstream switch 20u or the second upstream switch 21u, half connection of the first upstream switch 20u or the second upstream switch 21u, or a power supply short circuit, and the circuit driving the motor 12 is normal.

[0138] Next, the control unit 50 instructs the switching unit 42 to switch on the diagnostic switch 28. When the circuit of the drive motor 12 is not faulty, when the diagnostic switch 28 is switched on, the detection voltage rises to the voltage divided by the diagnostic resistors 29 and 30, and reaches or exceeds the voltage threshold Vth. When the diagnostic switch 28 is on, the detection voltage is or exceeds the voltage threshold Vth. Therefore, the control unit 50 diagnoses that there is no fault such as a short circuit at both ends of the first downstream switch 20d or the second downstream switch 21d, a half connection of the first downstream switch 20d or the second downstream switch 21d, or a ground short circuit, and the circuit of the drive motor 12 is normal.

[0139] When the control unit 50 diagnoses that the circuit driving the motor 12 is normal, the control unit 50 instructs the switching unit 42 to switch the diagnostic switch 28 to off, and instructs the output units 40u and 40d to output an on instruction to the first upstream drive circuit 24u and the first downstream drive circuit 24d. As a result, the first upstream drive circuit 24u and the first downstream drive circuit 24d switch the first upstream switch 20u and the first downstream switch 20d to on. As a result, power is supplied to the motor 12, and the motor 12 rotates in the forward direction. After instructing the output units 40u and 40d to output the on instruction, the control unit 50 ends the motor driving process.

[0140] When the reverse signal is input to the input unit 46 of the microcomputer 27 in the state where the value of the flag is 0, the control unit 50 performs the same processing as the processing performed when the forward signal is input to the input unit 46 of the microcomputer 27 in the state where the value of the flag is 0. After the control unit 50 instructs the switching unit 42 to switch the diagnostic switch 28 to OFF, the output units 41u and 41d are instructed to output an ON instruction to the second upstream drive circuit 25u and the second downstream drive circuit 25d. As a result, the second upstream drive circuit 25u and the second downstream drive circuit 25d switch the second upstream switch 21u and the second downstream switch 21d to ON. As a result, power is supplied to the motor 12, and the motor 12 rotates in the reverse direction. After the control unit 50 instructs the output units 41u and 41d to output the ON instruction, the motor drive processing ends.

[0141] Figure 7 2 is a timing chart showing the operation of the drive device 10 when both ends of the first upstream switch 20u are short-circuited. Figure 6 Similarly, changes in the instructions of the first upstream driver circuit 24u, the first downstream driver circuit 24d, the second upstream driver circuit 25u, and the second downstream driver circuit 25d, changes in the state of the diagnostic switch 28, and changes in the detection voltage detected by the voltage detection circuit 31 are shown.

[0142] Assume that both ends of the first upstream switch 20u are short-circuited when the value of the flag is 0. In this case, the detection voltage rises to a voltage substantially consistent with the battery voltage and reaches above the voltage threshold Vth. When a forward signal or a reverse signal is input to the input unit 46, the control unit 50 performs the motor drive process. In the motor drive process, diagnosis is performed when the value of the flag is 0 and the diagnostic switch 28 is disconnected. Here, since the detection voltage is above the voltage threshold Vth, the control unit 50 detects faults such as a short circuit at both ends of the first upstream switch 20u or the second upstream switch 21u, a half connection of the first downstream switch 20d or the second downstream switch 21d, or a power supply short circuit. In this case, the control unit 50 ends the motor drive process while maintaining the instructions output by the output units 40u, 40d, 41u, and 41d as disconnected instructions.

[0143] When a fault such as a short circuit at both ends of the second upstream switch 21u, half-connection of the first downstream switch 20d or the second downstream switch 21d, or a power supply short circuit occurs while the value of the flag is 0, the control unit 50 performs the same processing as that performed when the two ends of the first upstream switch 20u are short-circuited while the value of the flag is 0.

[0144] Figure 8 2 is a timing chart showing the operation of the drive device 10 when both ends of the first downstream switch 20d are short-circuited. Figure 6Similarly, changes in the instructions of the first upstream driver circuit 24u, the first downstream driver circuit 24d, the second upstream driver circuit 25u, and the second downstream driver circuit 25d, changes in the state of the diagnostic switch 28, and changes in the detection voltage detected by the voltage detection circuit 31 are shown.

[0145] It is assumed that both ends of the first downstream switch 20d are short-circuited when the value of the flag is 0. In this case, the detection voltage is maintained at 0V. When the forward signal or the reverse signal is input to the input unit 46, the control unit 50 performs the motor drive process. In the motor drive process, the diagnosis is performed when the value of the flag is 0 and the diagnostic switch 28 is disconnected. Here, since the detection voltage is less than the voltage threshold Vth, the control unit 50 diagnoses that there is no short circuit at both ends of the first upstream switch 20u or the second upstream switch 21u, half connection of the first downstream switch 20d or the second downstream switch 21d, or power supply short circuit, and the circuit driving the motor 12 is normal.

[0146] Next, the control unit 50 instructs the switching unit 42 to switch the diagnostic switch 28 to ON. Here, since both ends of the first downstream switch 20d are short-circuited, the detection voltage is maintained at 0V and does not reach or exceed the voltage threshold Vth. Therefore, the control unit 50 detects a fault such as a short circuit at both ends of the first downstream switch 20d or the second downstream switch 21d, a half-connection of the first downstream switch 20d or the second downstream switch 21d, or a ground short circuit. In this case, the control unit 50 instructs the switching unit 42 to switch the diagnostic switch 28 to OFF while maintaining the instructions output by the output units 40u, 40d, 41u, and 41d as OFF instructions, and ends the motor drive process.

[0147] When a fault such as a short circuit at both ends of the second downstream switch 21d, half-connection of the first downstream switch 20d or the second downstream switch 21d, or a ground short circuit occurs while the value of the flag is 0, the control unit 50 performs the same processing as that performed when the two ends of the first downstream switch 20d are short-circuited while the value of the flag is 0.

[0148] As described in the description of the motor drive processing, when the value of the flag is 1, when a forward signal or a reverse signal is input to the input unit 46, the control unit 50 performs diagnosis and detects a fault in the disconnection indication state in which a disconnection indication is output to the first upstream drive circuit 24u, the first downstream drive circuit 24d, the second upstream drive circuit 25u and the second downstream drive circuit 25d.

[0149] <Open Circuit Detection Processing>

[0150] Fig. 9is a flowchart showing the process of the open circuit detection process. The control unit 50 periodically performs the open circuit detection process when the value of the flag is 1. When the drive device 10 is normal, when the value of the flag is 1, the current flows through the motor 12 in the first current direction or the second current direction, and the motor 12 rotates in the forward direction or the reverse direction.

[0151] In the open circuit detection process, the control unit 50 first determines whether the direction of the current flowing through the motor 12 is the first current direction (step S31) under the assumption that the drive device 10 is normal. In step S31, the control unit 50 determines that the direction is the first current direction when the output units 40u and 40d output a connection instruction to the first upstream drive circuit 24u and the first downstream drive circuit 24d, respectively, and the output units 41u and 41d output a disconnection instruction to the second upstream drive circuit 25u and the second downstream drive circuit 25d. The control unit 50 determines that the direction is not the first current direction when the output units 41u and 41d output a connection instruction to the second upstream drive circuit 25u and the second downstream drive circuit 25d, respectively, and the output units 40u and 40d output a disconnection instruction to the first upstream drive circuit 24u and the first downstream drive circuit 24d, respectively.

[0152] When the control unit 50 determines that the direction is the first current direction (S31: Yes), the control unit 50 obtains the first current information from the first current detection circuit 26a (step S32). The storage unit 49 stores a reference current in advance. The reference current is a constant value and is greater than 0A. In addition, the reference current is less than the first current flowing through the motor 12 when the first upstream switch 20u and the first downstream switch 20d are turned on and the second upstream switch 21u and the second downstream switch 21d are turned off when the drive device 10 is normal. Moreover, the reference current is less than the second current flowing through the motor 12 when the second upstream switch 21u and the second downstream switch 21d are turned on and the first upstream switch 20u and the second downstream switch 21d are turned off when the drive device 10 is normal.

[0153] Therefore, when the driving device 10 is normal, at the time point of executing step S32, the first current is greater than the reference current. When the first upstream switch 20u or the first downstream switch 20d is open, since the current does not flow through the shunt resistor 22a, the first current detected by the first current detection circuit 26a is 0A, which is less than the reference current. The opening of each of the first upstream switch 20u, the first downstream switch 20d, the second upstream switch 21u, and the second downstream switch 21d means the opening between the drain and the source.

[0154] The control unit 50 determines whether the first current indicated by the first current information obtained in step S32 is less than the reference current (step S33). The first current being less than the reference current means that a fault has occurred in the circuit driving the motor 12. The control unit 50 detects a fault in the circuit driving the motor 12 by executing step S33. The reference current functions as a prescribed current.

[0155] When the control unit 50 determines that the direction is not the first current direction, that is, the direction is the second current direction (S31: No), the second current information is obtained from the second current detection circuit 26b (step S34). When the drive device 10 is normal, at the time point of executing step S34, the second current is greater than the reference current. When the second upstream switch 21u and the second downstream switch 21d are open, the current does not flow through the shunt resistor 22b, so the second current detected by the second current detection circuit 26b is 0A, which is less than the reference current.

[0156] The control unit 50 determines whether the second current represented by the second current information obtained in step S34 is less than the reference current (step S35). The second current being less than the reference current means that a fault has occurred in the circuit driving the motor 12. The control unit 50 detects a fault in the circuit driving the motor 12 by executing step S35. In addition, the reference currents used in steps S33 and S35 may also be different values ​​from each other.

[0157] When the control unit 50 determines that the first current is less than the reference current (S33: Yes), or when the control unit 50 determines that the second current is less than the reference current (S35: Yes), it is considered that a fault in the circuit of the drive motor 12 is detected, and the instructing output units 40u, 40d, 41u, 41d output disconnection instructions to all the drive circuits, i.e., the first upstream drive circuit 24u, the first downstream drive circuit 24d, the second upstream drive circuit 25u, and the second downstream drive circuit 25d (step S36). Then, the control unit 50 instructs the signal output unit 43 to output a fault signal (step S37), changes the value of the flag to 0 (step S38), and ends the open circuit detection process.

[0158] When the control unit 50 determines that the first current is equal to or greater than the reference current ( S33 : No) or determines that the second current is equal to or greater than the reference current ( S35 : No), it considers that no failure in the circuit of the drive motor 12 is detected and ends the open circuit detection process.

[0159] <Effects of the driving device 10, etc.>

[0160] When the first upstream switch 20u and the second downstream switch 21d are switched on by mistake, a large current flows through the first upstream switch 20u. At this time, since the first current detected by the first current detection circuit 26a exceeds the first current threshold, the first upstream drive circuit 24u immediately switches the first upstream switch 20u off and stops the flow of current through the first upstream switch 20u. Therefore, a large current does not flow through the first upstream switch 20u for a long time.

[0161] Similarly, when the second upstream switch 21u and the first downstream switch 20d are switched on by mistake, a large current flows through the second upstream switch 21u. At this time, since the second current detected by the second current detection circuit 26b exceeds the second current threshold, the second upstream drive circuit 25u immediately switches the second upstream switch 21u off and stops the flow of current through the second upstream switch 21u. Therefore, a large current does not flow through the second upstream switch 21u for a long time.

[0162] In addition, the diagnosis switch 28 may be disposed between the diagnosis resistors 29 and 30. In this case, the voltage detection circuit 31 detects the voltage of the connection node between the diagnosis switch 28 and the diagnosis resistor 30 with reference to the ground potential.

[0163] (Implementation Method 2)

[0164] In the open circuit detection process of Embodiment 1, the open circuit of the first upstream switch 20u, the first downstream switch 20d, the second upstream switch 21u, or the second downstream switch 21d is detected based on the first current detected by the first current detection circuit 26a or the second current detected by the second current detection circuit 26b. However, the detection of the open circuit is not limited to the detection based on the first current or the second current.

[0165] Hereinafter, the differences between Embodiment 2 and Embodiment 1 will be described. Since the configuration other than the configuration described below is common to Embodiment 1, the same reference numerals as those in Embodiment 1 are given to the common configuration parts to omit the description thereof.

[0166] <Open Circuit Detection Processing>

[0167] When the drive device 10 according to the second embodiment is compared with the drive device 10 according to the first embodiment, the open circuit detection process is different.

[0168] Fig.10: is a flowchart showing the process of the open circuit detection processing in the second embodiment. The control unit 50 periodically performs the open circuit detection processing when the value of the flag is 1, similarly to the first embodiment. As described in the description of the first embodiment, the control unit 50 changes the value of the flag to 1 when the diagnostic switch 28 is in the off state. During the period when the value of the flag is 1, except for the short diagnosis period performed when the forward signal or the reverse signal is input to the input unit 46, the control unit 50 does not instruct the switching unit 42 to switch the diagnostic switch 28 to on, and the diagnostic switch 28 is maintained in the off state. The open circuit detection processing is performed when the diagnostic switch 28 is in the off state.

[0169] Part of the open circuit detection process in Embodiment 2 is the same as that in Embodiment 1. Therefore, in the open circuit detection process in Embodiment 2, detailed description of the common parts with the open circuit detection process in Embodiment 1, namely, steps S31 and S36 to S38 is omitted.

[0170] In the open circuit detection process, the control unit 50 first obtains voltage information from the A / D conversion unit 45 (step S41). As described in the description of the first embodiment, the voltage information indicates the detection voltage detected by the voltage detection circuit 31. After executing step S41, the control unit 50 executes step S31. In step S31, as described in the description of the first embodiment, the control unit 50 determines whether the direction of the current flowing through the motor 12 is the first current direction, assuming that the drive device 10 is normal.

[0171] When the control unit 50 determines that the direction is the first current direction (S31: Yes), it determines whether the detection voltage represented by the voltage information obtained in step S41 is above the voltage threshold (step S42). When the drive device 10 is normal, when the direction is the first current direction, since the first downstream switch 20d is turned on, the detection voltage detected by the voltage detection circuit 31 is 0V, which is less than the voltage threshold. When the first downstream switch 20d is open, since the first upstream switch 20u is turned on, the detection voltage detected by the voltage detection circuit 31 is substantially consistent with the battery voltage and is above the voltage threshold. The control unit 50 detects a fault in the circuit of the drive motor 12 by executing step S42.

[0172] When the control unit 50 determines that the direction is not the first current direction, that is, the direction is the second current direction (S31: No), it determines whether the detection voltage represented by the voltage information obtained in step S41 is less than the voltage threshold value (step S43). When the drive device 10 is normal, when the direction is the second current direction, since the second upstream switch 21u is turned on, the detection voltage detected by the voltage detection circuit 31 is substantially consistent with the battery voltage and is above the voltage threshold value. When the second upstream switch 21u is open, since the second downstream switch 21d is turned on, the detection voltage detected by the voltage detection circuit 31 is consistent with 0V and is less than the voltage threshold value. The control unit 50 detects a fault in the circuit of the drive motor 12 by executing step S43.

[0173] When the control unit 50 determines that the detection voltage is greater than the voltage threshold (S42: Yes), or when the detection voltage is less than the voltage threshold (S43: Yes), it is considered that a fault in the circuit of the drive motor 12 is detected, and steps S36 to S38 are sequentially executed to terminate the open circuit detection process. When the control unit 50 determines that the detection voltage is less than the voltage threshold (S42: No), or when the detection voltage is greater than the voltage threshold (S43: No), it is considered that no fault in the circuit of the drive motor 12 is detected, and the open circuit detection process is terminated.

[0174] <Operation of the driving device 10>

[0175] Fig.11 is a timing chart showing the operation of the drive device 10 when the first downstream switch is open. Fig.11 Zhongyu Figure 6 Similarly, changes in the instructions of the first upstream driver circuit 24u, the first downstream driver circuit 24d, the second upstream driver circuit 25u, and the second downstream driver circuit 25d, changes in the state of the diagnostic switch 28, and changes in the detection voltage detected by the voltage detection circuit 31 are shown.

[0176] As described above, the control unit 50 periodically performs the open circuit detection process when the value of the flag is 1. The state where the value of the flag is 1 means a state where an on instruction is output to the first upstream drive circuit 24u and the first downstream drive circuit 24d, and an off instruction is output to the second upstream drive circuit 25u and the second downstream drive circuit 25d, or a state where an off instruction is output to the first upstream drive circuit 24u and the first downstream drive circuit 24d, and an on instruction is output to the second upstream drive circuit 25u and the second downstream drive circuit 25d.

[0177] exist Fig.11, a state where an on instruction is output to the first upstream drive circuit 24u and the first downstream drive circuit 24d, and an off instruction is output to the second upstream drive circuit 25u and the second downstream drive circuit 25d is shown. When the drive device 10 is normal, the current flows in the first current direction in the motor 12, and the detection voltage is 0V, which is less than the voltage threshold value Vth. Therefore, when the detection voltage is less than the voltage threshold value Vth, in the open circuit detection process, the control unit 50 determines that the drive device 10 is normal.

[0178] When the first downstream switch 20d is open, the first upstream switch 20u is turned on, so the detection voltage detected by the voltage detection circuit 31 reaches or exceeds the voltage threshold value Vth. At this time, the detection voltage is substantially consistent with the battery voltage. When the detection voltage is or exceeds the voltage threshold value Vth, the control unit 50 detects a fault in the circuit of the drive motor 12 during the open circuit detection process.

[0179] As described above, in the open circuit detection process, when the control unit 50 detects a fault in the circuit of the drive motor 12, the control unit 50 instructs the output units 40u, 40d, 41u, and 41d to output a disconnection instruction to all the drive circuits. As a result, the first upstream drive circuit 24u and the first downstream drive circuit 24d respectively switch the first upstream switch 20u and the first downstream switch 20d to be disconnected. As a result, the detection voltage is reduced to 0V.

[0180] Fig.12 2 is a timing chart showing the operation of the drive device 10 when the second upstream switch 21u is open. Fig.12 Zhongyu Figure 6 Similarly, changes in the instructions of the first upstream driver circuit 24u, the first downstream driver circuit 24d, the second upstream driver circuit 25u, and the second downstream driver circuit 25d, changes in the state of the diagnostic switch 28, and changes in the detection voltage detected by the voltage detection circuit 31 are shown.

[0181] exist Fig.12 , a state in which a disconnection instruction is output to the first upstream drive circuit 24u and the first downstream drive circuit 24d, and a connection instruction is output to the second upstream drive circuit 25u and the second downstream drive circuit 25d is shown. When the drive device 10 is normal, the current flows in the second current direction in the motor 12, and the detection voltage substantially coincides with the battery voltage and is greater than the voltage threshold Vth. Therefore, when the detection voltage is greater than the voltage threshold Vth, the control unit 50 determines that the drive device 10 is normal in the open circuit detection process.

[0182] When the second upstream switch 21u is open, since the second downstream switch 21d is turned on, the detection voltage detected by the voltage detection circuit 31 is less than the voltage threshold value Vth. At this time, the detection voltage is consistent with 0 V. When the detection voltage is less than the voltage threshold value Vth, the control unit 50 detects a fault in the circuit of the drive motor 12 during the open circuit detection process.

[0183] As described above, in the open circuit detection process, the control unit 50 instructs the output units 40u, 40d, 41u, and 41d to output disconnection instructions to all the drive circuits when a fault in the circuit of the drive motor 12 is detected. As a result, the first upstream drive circuit 24u and the first downstream drive circuit 24d respectively switch the first upstream switch 20u and the first downstream switch 20d to be disconnected.

[0184] As described above, in the drive device 10 of the second embodiment, the control unit 50 detects a fault in the circuit of the drive motor 12, specifically, an open circuit of the first downstream switch 20d and the second upstream switch 21u, based on the detection voltage detected by the voltage detection circuit 31. The drive device 10 of the second embodiment also achieves the effects achieved by the drive device 10 of the first embodiment, other than the effects achieved by detecting an open circuit using the first current and the second current detected by the first current detection circuit 26a and the second current detection circuit 26b.

[0185] Furthermore, the control unit 50 of the drive device 10 in the first embodiment may execute both the open circuit detection process using the first current and the second current and the open circuit detection process using the detection voltage.

[0186] (Implementation 3)

[0187] In the open circuit detection process of the first embodiment, the open circuit of the first upstream switch 20u, the first downstream switch 20d, the second upstream switch 21u, or the second downstream switch 21d is detected based on the first current or the second current. In the open circuit detection process of the second embodiment, the open circuit of the first downstream switch 20d and the second upstream switch 21u is detected based on the detection voltage. The open circuit detection is not limited to the detection based on the first current, the second current, or the detection voltage.

[0188] Hereinafter, the differences between Embodiment 3 and Embodiment 1 will be described. Since the configuration other than the configuration described below is the same as that of Embodiment 1, the same reference numerals as those of Embodiment 1 are given to the configuration parts common to Embodiment 1, and the description thereof will be omitted.

[0189] <Structure of Power Supply System 1>

[0190] Fig.131 is a block diagram showing a main part configuration of a power supply system 1 in Embodiment 3. In Embodiment 3, the motor 12 includes a Hall sensor 12s. The Hall sensor 12s is connected to a microcomputer 27.

[0191] As described in the description of Embodiment 1, the rotation of the motor 12 means the rotation of the rotor. In the motor 12, the cylindrical rotor rotates around the axis. The rotor is composed of, for example, a permanent magnet. In this case, in the rotor, N poles and S poles are alternately arranged along the circumferential direction. The Hall sensor 12s is arranged in a manner opposite to the circumferential surface of the rotor. The Hall sensor 12s outputs a voltage corresponding to the intensity of the magnetic field passing through itself as a sensor voltage. The sensor voltage output by the Hall sensor 12s is an analog value. Therefore, when the magnetic pole of the rotor opposite to the Hall sensor 12s switches from the N pole to the S pole or from the S pole to the N pole, the sensor voltage changes greatly. The regular change of the sensor voltage indicates the rotation of the motor 12. The stable sensor voltage indicates that the motor 12 is not rotating. The Hall sensor 12s outputs the sensor voltage as rotation information related to the rotation of the motor 12 to the microcomputer 27.

[0192] <Structure of Microcomputer 27>

[0193] Fig.14 2 is a block diagram showing the main structure of the microcomputer 27. The microcomputer 27 in the third embodiment has an A / D conversion unit 52 and an input unit 53 in addition to the components of the microcomputer 27 in the first embodiment. The A / D conversion unit 52 is connected to the internal bus 51 and the input unit 53. The input unit 53 is connected to the Hall sensor 12s.

[0194] The Hall sensor 12s outputs an analog sensor voltage to the input unit 53. When the sensor voltage is input from the Hall sensor 12s, the input unit 53 outputs the input analog sensor voltage to the A / D converter 52. The A / D converter 52 converts the analog sensor voltage input from the input unit 53 into a digital sensor voltage. The control unit 50 obtains the digital sensor voltage from the A / D converter 52. The sensor voltage obtained by the control unit 50 is substantially consistent with the sensor voltage detected by the Hall sensor 12s at the time of acquisition.

[0195] <Open Circuit Detection Processing>

[0196] Fig.15is a flowchart showing the process of open circuit detection processing. The control unit 50 periodically performs the open circuit detection processing when the value of the flag is 1, similarly to the first embodiment. As described in the description of the first embodiment, when the value of the flag is 1, the output units 40u, 40d output a connection instruction to the first upstream drive circuit 24u and the first downstream drive circuit 24d, or the output units 41u, 41d output a connection instruction to the second upstream drive circuit 25u and the second downstream drive circuit 25d. Therefore, when the drive device 10 is normal, when the value of the flag is 1, the motor 12 rotates in the forward direction or the reverse direction.

[0197] Part of the open circuit detection process in Embodiment 3 is the same as that in Embodiment 1. Therefore, in the open circuit detection process in Embodiment 3, detailed description of the common parts with the open circuit detection process in Embodiment 1, namely, steps S36 to S38 is omitted.

[0198] In the open circuit detection process, the control unit 50 first obtains a plurality of sensor voltages from the A / D converter 52 in time series (step S51). Next, the control unit 50 determines whether the motor 12 is rotating based on the plurality of sensor voltages obtained in step S51 (step S52). In step S52, as described above, when the sensor voltages change regularly, the control unit 50 determines that the motor 12 is rotating. When the sensor voltages are stable, the control unit 50 determines that the motor 12 is not rotating.

[0199] When the first upstream switch 20u or the first downstream switch 20d is open, the motor 12 does not rotate in the forward direction. When the second upstream switch 21u or the second downstream switch 21d is open, the motor 12 does not rotate in the reverse direction. The control unit 50 detects a fault in the circuit driving the motor 12 by executing step S52.

[0200] When the control unit 50 determines that the motor 12 is not rotating (S52: No), it is considered that a fault in the circuit driving the motor 12 is detected, and steps S36 to S38 are performed in sequence to terminate the open circuit detection process. When the control unit 50 determines that the motor 12 is rotating (S52: Yes), it is considered that a fault in the circuit driving the motor 12 is not detected, and the open circuit detection process is terminated.

[0201] As described above, in the drive device 10 of the third embodiment, the control unit 50 detects a fault in the circuit of the drive motor 12 based on the sensor voltage, specifically, an open circuit of the first upstream switch 20u, the first downstream switch 20d, the second upstream switch 21u, or the second downstream switch 21d. The drive device 10 of the third embodiment also achieves an effect other than the effect obtained by detecting the open circuit using the first current and the second current among the effects achieved by the drive device 10 of the first embodiment.

[0202] In addition, the control unit 50 of the drive device 10 in the first embodiment may also perform one or both of the open circuit detection process using the detection voltage and the open circuit detection process using the sensor voltage in addition to the open circuit detection process using the first current and the second current. The control unit 50 of the drive device 10 in the second embodiment may also perform the open circuit detection process using the sensor voltage in addition to the open circuit detection process using the detection voltage.

[0203] (Implementation 4)

[0204] In Embodiment 1, the first upstream switch 20u and the second upstream switch 21u are semiconductor switches. However, the first upstream switch 20u and the second upstream switch 21u are not limited to semiconductor switches.

[0205] Hereinafter, Embodiment 4 will be described with respect to points different from Embodiment 1. Since the configuration other than the configuration described below is common to Embodiment 1, the same reference numerals as those in Embodiment 1 are given to the common configuration parts to omit the description thereof.

[0206] <Structure of the driving device 10>

[0207] Fig.16 1 is a block diagram showing the main structure of the power supply system 1 in the fourth embodiment. When the power supply system 1 of the fourth embodiment is compared with the power supply system 1 of the first embodiment, the structure of the drive device 10 is different. In the fourth embodiment, the first upstream switch 20u and the second upstream switch 21u of the drive device 10 are relay contacts. The first upstream switch 20u and the second upstream switch 21u respectively have an input terminal, an output terminal, and a rod-shaped conductor whose end is connected to the input terminal in a rotatable manner. The conductor is applied with a force in a direction away from the output terminal, for example, by a spring. When the conductor is away from the output terminal, the first upstream switch 20u and the second upstream switch 21u are disconnected. When the conductor is in contact with the output terminal, the first upstream switch 20u and the second upstream switch 21u are connected.

[0208] The input terminals of the first upstream switch 20u and the second upstream switch 21u are connected to the positive electrode of the battery 11. The output terminals of the first upstream switch 20u and the second upstream switch 21u are connected to one end of the shunt resistors 22a and 22b. The first upstream drive circuit 24u and the second upstream drive circuit 25u are connected to the input terminals of the first upstream switch 20u and the second upstream switch 21u, respectively, and are grounded. The first upstream drive circuit 24u and the second upstream drive circuit 25u respectively switch the first upstream switch 20u and the second upstream switch 21u to on or off in the same manner as in Embodiment 1.

[0209] <Structure of the First Upstream Driving Circuit 24u>

[0210] Fig.17 : is a circuit diagram of the first upstream drive circuit 24u. The first upstream drive circuit 24u has an inductor 60, a current limiting resistor 61, a drive switch 62, an AND circuit 63 and a latch circuit 64. The drive switch 62 is an NPN type bipolar transistor. One end of the inductor 60 is connected to the input terminal of the first upstream switch 20u. The other end of the inductor 60 is connected to one end of the current limiting resistor 61. The other end of the current limiting resistor 61 is connected to the collector of the drive switch 62. The emitter of the drive switch 62 is grounded. The base of the drive switch 62 is connected to the output end of the AND circuit 63. One input end of the AND circuit 63 is connected to the output end of the latch circuit 64. The input end of the latch circuit 64 is connected to the first current detection circuit 26a.

[0211] The AND circuit 63 outputs a high-level voltage or a low-level voltage to the base of the drive switch 62. When the AND circuit 63 outputs a high-level voltage, the drive switch 62 is turned on, and current can flow through the collector and emitter of the drive switch 62. When the AND circuit 63 outputs a low-level voltage, the drive switch 62 is turned off.

[0212] When the drive switch 62 is switched on, the current flows from the positive electrode of the battery 11 through the inductor 60, the current limiting resistor 61, and the drive switch 62 in sequence. As a result, the inductor 60 acts as a magnet, attracting the conductor of the first upstream switch 20u, so that the conductor contacts the output terminal of the first upstream switch 20u. As a result, the first upstream switch 20u is switched on. When the drive switch 62 is switched off, the flow of current through the inductor 60 stops, and the inductor 60 stops functioning as a magnet. As a result, in the first upstream switch 20u, the conductor is separated from the output terminal, and the first upstream switch 20u is switched off.

[0213] The output unit 40u outputs a high-level voltage as an on-indication and outputs a low-level voltage as an off-indication. The first current information is input from the first current detection circuit 26a to the latch circuit 64. The latch circuit 64 continues to output a high-level voltage during a period in which the first current represented by the first current information input from the first current detection circuit 26a is less than the first current threshold. When the first current represented by the first current information input from the first current detection circuit 26a reaches or exceeds the first current threshold, the latch circuit 64 switches the high-level voltage output to the AND circuit 63 to a low-level voltage output. Thereafter, the latch circuit 64 continues to output a low-level voltage regardless of the first current information input from the first current detection circuit 26a.

[0214] The AND circuit 63 outputs the voltage input from the output section 40u from the output terminal to the base of the drive switch 62 while the latch circuit 64 continues to output the high-level voltage. Therefore, when the output section 40u outputs an on instruction, the drive switch 62 is on and the first upstream switch 20u is on. When the output section 40u outputs an off instruction, the drive switch 62 is off and the first upstream switch 20u is off.

[0215] When the voltage output by the latch circuit 64 is switched from a high level voltage to a low level voltage, the AND circuit 63 switches the voltage output to the drive switch 62 to a low level voltage regardless of the voltage output by the output unit 40u. As a result, the drive switch 62 is switched off, and the first upstream switch 20u is switched off. While the latch circuit 64 outputs a low level voltage, the first upstream switch 20u is maintained off.

[0216] The second upstream drive circuit 25u is configured similarly to the first upstream drive circuit 24u. In the description of the first upstream drive circuit 24u, the first upstream switch 20u, the first current detection circuit 26a, the output unit 40u, and the first current threshold correspond to the second upstream switch 21u, the second current detection circuit 26b, the output unit 41u, and the second current threshold, respectively. The output unit 41u outputs a high-level voltage as an on-indication and a low-level voltage as an off-indication.

[0217] The driving device 10 of the fourth embodiment also achieves the same effects as the driving device 10 of the first embodiment.

[0218] In the first to third embodiments, the first upstream switch 20u, the first upstream drive circuit 24u, the second upstream switch 21u, and the second upstream drive circuit 25u may be configured similarly to the fourth embodiment.

[0219] (Implementation method 5)

[0220] In the first embodiment, the diagnostic switch 28 is arranged upstream of at least one of the diagnostic resistors 29 and 30 . However, the arrangement of the diagnostic switch 28 is not limited to the arrangement upstream of at least one of the diagnostic resistors 29 and 30 .

[0221] Hereinafter, Embodiment 5 will be described with respect to points different from Embodiment 1. Since the configuration other than the configuration described below is common to Embodiment 1, the same reference numerals as those in Embodiment 1 are given to the common configuration parts to omit the description thereof.

[0222] <Structure of the driving device 10>

[0223] Fig.18 1 is a block diagram showing the main structure of the power supply system 1 in Embodiment 5. When the power supply system 1 in Embodiment 5 is compared with the power supply system 1 in Embodiment 1, the structure of the drive device 10 is different. In the drive device 10 in Embodiment 5, a constant voltage Vcc is applied to one end of the diagnostic resistor 29. The other end of the diagnostic resistor 30 is connected to one end of the diagnostic switch 28. The other end of the diagnostic switch 28 is grounded.

[0224] Assume that the first upstream switch 20u, the first downstream switch 20d, the second upstream switch 21u, and the second downstream switch 21d are turned off. When the drive device 10 is normal, when the diagnostic switch 28 is turned off, the voltage detection circuit 31 detects a constant voltage Vcc. In the event of a short circuit at both ends of the first downstream switch 20d or the second downstream switch 21d, a half-connection of the first downstream switch 20d or the second downstream switch 21d, or a ground short circuit, when the diagnostic switch 28 is turned off, the voltage detection circuit 31 detects a value close to 0V.

[0225] When the drive device 10 is normal, when the diagnostic switch 28 is turned on, the voltage detection circuit 31 detects a voltage obtained by dividing the constant voltage Vcc by the diagnostic resistors 29 and 30. In the event of a short circuit at both ends of the first upstream switch 20u or the second upstream switch 21u, half-connection of the first upstream switch 20u or the second upstream switch 21u, or a power supply short circuit, when the diagnostic switch 28 is turned on, the voltage detected by the voltage detection circuit 31 is substantially consistent with the battery voltage.

[0226] In the fifth embodiment, the voltage threshold is set to a voltage higher than the voltage obtained by dividing the constant voltage Vcc by the diagnosis resistors 29 and 30 and equal to or lower than the constant voltage Vcc.

[0227] The constant voltage Vcc is greater than the voltage threshold, and a value close to 0 V is less than the voltage threshold. Therefore, when the diagnostic switch 28 is off, the control unit 50 can detect faults such as a short circuit at both ends of the first downstream switch 20d or the second downstream switch 21d, a half-connection of the first downstream switch 20d or the second downstream switch 21d, or a ground short circuit.

[0228] The voltage obtained by dividing the constant voltage Vcc by the diagnostic resistors 29 and 30 is less than the voltage threshold, and the battery voltage is greater than the voltage threshold. Therefore, when the diagnostic switch 28 is turned on, the control unit 50 can detect a short circuit at both ends of the first upstream switch 20u or the second upstream switch 21u, a half-connection of the first upstream switch 20u or the second upstream switch 21u, or a power supply short circuit.

[0229] <Motor drive processing>

[0230] Fig.19 2 is a flowchart showing the procedure of the motor driving process. As in the first embodiment, when the forward rotation signal or the reverse rotation signal is input to the input unit 46, the control unit 50 executes the motor driving process.

[0231] Part of the motor driving process in the fifth embodiment is the same as that in the first embodiment. Therefore, detailed description of the parts of the motor driving process in the fifth embodiment that are common to the motor driving process in the first embodiment, namely steps S1 to S6, S8 to S10, and S12 to S18, will be omitted.

[0232] After executing step S6, the control unit 50 determines whether the detection voltage represented by the voltage information obtained in step S6 is less than the voltage threshold (step S61). The detection voltage being less than the voltage threshold means that a fault such as a short circuit at both ends of the first downstream switch 20d or the second downstream switch 21d, half-connection of the first downstream switch 20d or the second downstream switch 21d, or a ground short circuit has occurred. The control unit 50 detects a fault in the circuit of the drive motor 12 by executing step S61. When the control unit 50 determines that the detection voltage is less than the voltage threshold (S61: Yes), it is deemed that a fault is detected and step S8 is executed. When the control unit 50 determines that the detection voltage is greater than the voltage threshold (S61: No), step S9 is executed.

[0233] After executing step S10, the control unit 50 determines whether the detection voltage represented by the voltage information obtained in step S10 is above the voltage threshold (step S62). The detection voltage being above the voltage threshold means that a fault such as a short circuit at both ends of the first upstream switch 20u or the second upstream switch 21u, half-connection of the first upstream switch 20u or the first upstream switch 20u, or a short circuit to the power supply has occurred. The control unit 50 detects a fault in the circuit driving the motor 12 by executing step S62. When the control unit 50 determines that the detection voltage is above the voltage threshold (S62: Yes), it is deemed that a fault is detected and step S12 is executed. When the control unit 50 determines that the detection voltage is less than the voltage threshold (S62: No), step S14 is executed.

[0234] The driving device 10 of the fifth embodiment also achieves the same effects as the driving device 10 of the first embodiment.

[0235] In the fifth embodiment, the diagnostic switch 28 may be connected between the diagnostic resistors 29 and 30. In this case, the voltage detection circuit 31 detects the voltage of the connection node between the diagnostic switch 28 and the diagnostic resistor 29 with reference to the ground potential.

[0236] In addition, in the fifth embodiment, the first upstream switch 20u, the first upstream drive circuit 24u, the second upstream switch 21u, and the second upstream drive circuit 25u may also be configured in the same manner as in the fourth embodiment. In addition, the control unit 50 of the drive device 10 in the fifth embodiment may also perform the open circuit detection process of the third embodiment using the sensor voltage in addition to the open circuit detection process using the first current and the second current. Furthermore, the control unit 50 of the drive device 10 in the fifth embodiment may also perform the open circuit detection process of the third embodiment using the sensor voltage instead of the open circuit detection process using the first current and the second current.

[0237] (Implementation 6)

[0238] In Embodiment 1, the first current detection circuit 26a and the second current detection circuit 26b detect current using the shunt resistors 22a and 22b, respectively. However, the configuration of each of the first current detection circuit 26a and the second current detection circuit 26b is not limited to the configuration using the shunt resistor 22a or the shunt resistor 22b.

[0239] Hereinafter, Embodiment 6 will be described with respect to points different from Embodiment 1. Since the configuration other than the configuration described below is common to Embodiment 1, the same reference numerals as those in Embodiment 1 are given to the common configuration parts to omit the description thereof.

[0240] Fig. 201 is a block diagram showing the main part structure of the first current detection circuit 26a in Embodiment 6. In Embodiment 6, the first current detection circuit 26a has a current output unit 70 and a circuit resistor 71. The current output unit 70 is connected to the source of the first upstream switch 20u, the motor 12, and one end of the load resistor 23. The current output unit 70 is also connected to one end of the circuit resistor 71. The other end of the circuit resistor 71 is grounded. The connection node between the current output unit 70 and the circuit resistor 71 is connected to the first upstream drive circuit 24u and the microcomputer 27.

[0241] When the first upstream drive circuit 24u and the first downstream drive circuit 24d switch the first upstream switch 20u and the first downstream switch 20d to be turned on, the first current flows through the first upstream switch 20u. The first current flows through the first upstream switch 20u and the current output unit 70 in sequence, and is output from the current output unit 70 to the motor 12 side. At this time, the current flows in the motor 12 in the first current direction. As a result, power is supplied to the motor 12, and the motor 12 rotates in the positive direction. The path of the current that flows from the positive electrode of the battery 11 through the first upstream switch 20u, the current output unit 70, the motor 12, and the first downstream switch 20d in sequence is equivalent to the first current path.

[0242] The current output unit 70 has, for example, a current mirror circuit, and outputs a current of a predetermined fraction, for example, 1 / 1000, of the first current output to the motor 12 side to the circuit resistor 71. The resistance value of the circuit resistor 71 is constant. The voltage between the two ends of the circuit resistor 71 is proportional to the first current. The first current is calculated by dividing the product of the predetermined fraction and the voltage between the two ends of the circuit resistor 71 by the resistance value of the circuit resistor 71. The voltage between the two ends of the circuit resistor 71 is output to the first upstream drive circuit 24u and the microcomputer 27 as the first current information indicating the first current detected by the first current detection circuit 26a.

[0243] In Embodiment 6, the second current detection circuit 26b is configured similarly to the first current detection circuit 26a. In this case, in the second current detection circuit 26b, the current output unit 70 is connected to the source of the second upstream switch 21u, the motor 12, and the other end of the load resistor 23. The connection node between the current output unit 70 and the circuit resistor 71 is connected to the second upstream drive circuit 25u and the microcomputer 27.

[0244] When the second upstream drive circuit 25u and the second downstream drive circuit 25d switch the second upstream switch 21u and the second downstream switch 21d to be turned on, the second current flows through the second upstream switch 21u. The second current flows through the second upstream switch 21u and the current output unit 70 in sequence, and is output from the current output unit 70 to the motor 12 side. At this time, the current flows in the motor 12 in the second current direction. As a result, power is supplied to the motor 12, and the motor 12 rotates in the reverse direction. The path of the current that flows from the positive electrode of the battery 11 through the second upstream switch 21u, the current output unit 70, the motor 12, and the second downstream switch 21d in sequence is equivalent to the second current path.

[0245] In the second current detection circuit 26b, the voltage across the circuit resistor 71 is proportional to the second current. The voltage across the circuit resistor 71 is output to the second upstream drive circuit 25u and the microcomputer 27 as second current information indicating the second current detected by the second current detection circuit 26b.

[0246] The driving device 10 according to the sixth embodiment configured as described above also achieves the same effects as achieved by the driving device 10 according to the first embodiment.

[0247] In the second to fifth embodiments, the first current detection circuit 26 a and the second current detection circuit 26 b may each have a configuration including a current output unit 70 and a circuit resistor 71 similarly to the sixth embodiment.

[0248] In addition, in embodiments 1 to 3, 5, and 6, the first upstream switch 20u and the second upstream switch 21u only need to function as switches, and are not limited to N-channel FETs or relay contacts, but may be P-channel FETs or IGBTs (Insulated Gate Bipolar Transistors). In addition, in embodiments 1 to 6, the first downstream switch 20d and the second downstream switch 21d only need to function as switches, and are not limited to N-channel FETs, but may be relay contacts, IGBTs, or P-channel FETs. However, the switch used for PWM control is preferably a semiconductor switch.

[0249] In embodiments 1 to 5, the structure in which the first current detection circuit 26a and the second current detection circuit 26b detect current respectively is not limited to the structure using shunt resistors 22a and 22b, or the structure having a current output unit 70 and a circuit resistor 71, and may be a structure using a current sensor, for example.

[0250] Moreover, in embodiments 1 to 6, the first downstream drive circuit 24d may also have a function of switching to off when the current flowing through the first downstream switch 20d reaches or exceeds the first current threshold value, similarly to the first upstream drive circuit 24u. Similarly, the second downstream drive circuit 25d may also have a function of switching to off when the current flowing through the second downstream switch 21d reaches or exceeds the second current threshold value, similarly to the second upstream drive circuit 25u.

[0251] In the first to sixth embodiments, when the resistance value between the two ends of the motor 12 is sufficiently smaller than the resistance value of the diagnostic resistor 30, the load resistor 23 may be removed from the drive device 10. Furthermore, in the first to sixth embodiments, the load driven by the drive device 10 is not limited to the motor 12, and may be any electrical device that switches the direction of application of a DC voltage.

[0252] The disclosed embodiments 1 to 6 should be considered to be illustrative in all aspects and not restrictive. The scope of the present invention is not the above meaning, but is represented by the scope of the invention claims, and is intended to include all changes within the meaning and scope equivalent to the scope of the invention claims.

[0253] Description of symbols

[0254] 1. Power supply system;

[0255] 10. Driving device;

[0256] 11. Battery;

[0257] 12 Electric motor;

[0258] 12s Hall sensor;

[0259] 16 steps;

[0260] 20u first upstream switch;

[0261] 20d first downstream switch;

[0262] 21u second upstream switch;

[0263] 21d second downstream switch;

[0264] 22a, 22b shunt resistor;

[0265] 23 load resistance;

[0266] 24u first upstream drive circuit (stop circuit);

[0267] 24d a first downstream driving circuit;

[0268] 25u second upstream drive circuit (second stop circuit);

[0269] 25d a second downstream driving circuit;

[0270] 26a a first current detection circuit;

[0271] 26b a second current detection circuit;

[0272] 27 Microcomputer;

[0273] 28 diagnostic switch (circuit switch);

[0274] 29 Diagnostic resistor (first resistor);

[0275] 30 diagnostic resistor (second resistor);

[0276] 31 voltage detection circuit;

[0277] 40d, 40u, 41d, 41u output unit;

[0278] 42 Switching Department;

[0279] 43 signal output unit;

[0280] 44a, 44b, 45, 52 A / D conversion unit;

[0281] 46, 47a, 47b, 48, 53 input;

[0282] 49 Storage Department;

[0283] 50 control unit (processing unit);

[0284] 51 internal bus;

[0285] 60 Inductor;

[0286] 61 current limiting resistor;

[0287] 62 drive switch;

[0288] 63 AND circuit;

[0289] 64 Latch circuit;

[0290] 70 current output unit;

[0291] 71 Circuit resistance;

[0292] E. Storage medium;

[0293] P Computer program;

[0294] Vcc constant voltage;

[0295] Vth voltage threshold.

Claims

1. A driving device for driving a load, wherein: have: a first upstream switch, arranged on an upstream side of the load in a first current path of the current flowing through the load; a first downstream switch, disposed in the first current path and on a downstream side of the load; a second upstream switch, arranged on an upstream side of the load in a second current path of the current flowing through the load; a second downstream switch, disposed in the second current path and on a downstream side of the load; a current detection circuit, detecting a current flowing through the first upstream switch; and a stop circuit that stops the flow of current through the first upstream switch when the current detected by the current detection circuit reaches or exceeds a current threshold, The direction of the current flowing through the load when the current flows through the first current path is different from the direction of the current flowing through the load when the current flows through the second current path. The driving device comprises: A series circuit, wherein a first resistor, a second resistor and a circuit switch are connected in series, a connection node between the first resistor and the second resistor is connected to a connection node between the load, the first downstream switch and the second upstream switch, and a constant voltage is applied to the series circuit; a voltage detection circuit for detecting a voltage at a connection node between the first resistor and the second resistor; and Processing department, executes processing, The processing unit performs the following processing: Switching the circuit switch on or off, A failure of a circuit driving the load is detected based on a voltage detected by the voltage detection circuit in an OFF instruction state instructing switching of the first upstream switch, the first downstream switch, the second upstream switch, and the second downstream switch to OFF.

2. The driving device according to claim 1, wherein: The driving device comprises: a second current detection circuit, detecting a current flowing through the second upstream switch; and The second stop circuit stops the flow of current through the second upstream switch when the current detected by the second current detection circuit reaches or exceeds a second current threshold.

3. The driving device according to claim 2, wherein: The stop circuit and the second stop circuit respectively switch the first upstream switch and the second upstream switch to be off.

4. The driving device according to any one of claims 1 to 3, wherein: The circuit switch is arranged on the upstream side of the first resistor or the second resistor, The connection node to which the voltage detection circuit is connected is located on the downstream side of the circuit switch, The processing unit performs the following processing: Switch the circuit switch to off, When the voltage detected by the voltage detection circuit is equal to or higher than a predetermined voltage in the disconnection instruction state, a failure of the circuit driving the load is detected, The prescribed voltage is higher than 0V.

5. The driving device according to any one of claims 1 to 3, wherein: The processing unit performs the following processing: Switching the circuit switch to on, When the voltage detected by the voltage detection circuit is lower than the second predetermined voltage in the disconnection instruction state, a failure of the circuit driving the load is detected, The second predetermined voltage is equal to or lower than a voltage obtained by dividing the constant voltage by the first resistor and the second resistor.

6. The driving device according to any one of claims 1 to 3, wherein: The processing unit performs the following processing: A fault in the circuit driving the load is detected based on a voltage detected by the voltage detection circuit when the circuit switch is disconnected in a state indicating that the first upstream switch and the first downstream switch are switched to be turned on and the second upstream switch and the second downstream switch are switched to be turned off, or when the circuit switch is disconnected in a state indicating that the second upstream switch and the second downstream switch are switched to be turned on and the first upstream switch and the first downstream switch are switched to be turned off.

7. The driving device according to any one of claims 1 to 3, wherein: The driving device includes a processing unit that performs processing. The processing unit performs the following processing: When the current detected by the current detection circuit is smaller than a predetermined current in a state where the first upstream switch and the first downstream switch are instructed to switch on, a failure of the circuit driving the load is detected.

8. The driving device according to any one of claims 1 to 3, wherein: The driving device includes a processing unit that performs processing. The load is a motor, The processing unit performs the following processing: acquiring rotation information related to the rotation of the motor in a state where the first upstream switch and the first downstream switch are instructed to switch on, or the second upstream switch and the second downstream switch are instructed to switch on, determining whether the load is rotating based on the acquired rotation information, If it is determined that the load is not rotating, a failure of a circuit driving the load is detected.

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