Drive device, short-circuit detection method, and computer program

Abstract

In the drive device, a first connection circuit (A), a second connection circuit (B), and a third connection circuit (C1) are connected between an input terminal (20a) and an output terminal (20b), respectively. A first motor (11) is connected between a connection node between a first input switch (60) and a first output switch (61) of the first connection circuit (A) and a connection node between a third input switch (K1) and a third intermediate switch (M1) of the third connection circuit (C1). A second motor (12) is connected between a connection node between a second input switch (70) and a second output switch (71) of the second connection circuit (B) and a connection node between the third intermediate switch (M1) and a third output switch (N1) of the third connection circuit (C1).

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a drive device, a short-circuit detection method, and a computer program.

[0002] This application claims priority based on Japanese Application No. 2019-200125 filed on November 1, 2019, the entire content of which is incorporated herein by reference. BACKGROUND

[0003] In Patent Literature 1, a drive device for a vehicle that drives a plurality of motors is disclosed. The drive device rotates rotors of first and second motors. The rotation direction of the rotor of each of the first and second motors is different depending on the direction of the current flowing therethrough. In the drive device described in Patent Literature 1, a first circuit, a second circuit, and a third circuit are connected between the positive and negative electrodes of a direct-current power supply. In each of the first circuit, the second circuit, and the third circuit, two switches are connected in series.

[0004] The first motor is connected between a connection node between the two switches possessed by the first circuit and a connection node between the two switches possessed by the third circuit. The second motor is connected between a connection node between the two switches possessed by the second circuit and a connection node between the two switches possessed by the third circuit.

[0005] In a case where the switch on the positive electrode side of the first circuit and the switch on the negative electrode side of the third circuit are on, a first-direction current flows through the first motor, and the first motor rotates in the forward direction. In a case where the switch on the negative electrode side of the first circuit and the switch on the positive electrode side of the third circuit are on, a second-direction current flows through the first motor, and the first motor rotates in the reverse direction. Similarly, in a case where the switch on the negative electrode side of the second circuit and the switch on the positive electrode side of the third circuit are on, a first-direction current flows through the second motor, and the second motor rotates in the forward direction. In a case where the switch on the positive electrode side of the second circuit and the switch on the negative electrode side of the third circuit are on, a second-direction current flows through the second motor, and the second motor rotates in the reverse direction.

[0006] PRIOR ART DOCUMENTS

[0007] PATENT LITERATURE

[0008] Patent Literature 1: Japanese Patent Application Publication No. 2015-51718 SUMMARY

[0009] The driving device of one embodiment of the present disclosure is a driving device that drives first and second motors whose rotational directions differ depending on the direction of current flowing therethrough, and includes first, second, and third connection circuits each connected between an input terminal of an input current and an output terminal of an output current, in the first connection circuit, two first switches are connected in series, in the second connection circuit, two second switches are connected in series, in the third connection circuit, three third switches are connected in series, the first motor is connected between a first connection node between the two first switches and a connection node between two third switches on the output terminal side, and the second motor is connected between a second connection node between the two second switches and a connection node between two third switches on the input terminal side.

[0010] In the short-circuit detection method of one embodiment of the present disclosure, a computer performs the following steps: switching a circuit switch of a driving device between on and off, the driving device including two first switches, two second switches, three third switches, a series circuit in which a first resistor, a second resistor, and the circuit switch are connected in series and to which a constant voltage is applied, and driving first and second motors whose rotational directions differ depending on the direction of current flowing therethrough; acquiring voltage information indicating a node voltage of a resistance connection node between the first resistor and the second resistor; and detecting a short circuit of one of the two first switches, the two second switches, and the three third switches, on the basis of the acquired voltage information, the driving device further including first, second, and third connection circuits each connected between an input terminal of an input current and an output terminal of an output current, in the first connection circuit, the two first switches are connected in series, in the second connection circuit, the two second switches are connected in series, in the third connection circuit, the three third switches are connected in series, the first motor is connected between a first connection node between the two first switches and a connection node between two third switches on the output terminal side, the second motor is connected between a second connection node between the two second switches and a connection node between two third switches on the input terminal side, and the resistance connection node is connected to the first connection node.

[0011] A computer program of one embodiment of the present disclosure is for causing a computer to execute the steps of switching a circuit switch of a drive device to on or off, the drive device including two first switches, two second switches, three third switches, and a series circuit in which a first resistor, a second resistor, and the circuit switch are connected in series and to which a constant voltage is applied, the drive device driving a first motor and a second motor whose rotational directions differ depending on the direction of current flowing therethrough; acquiring voltage information indicating a node voltage of a node at which the first resistor and the second resistor are connected in series; and detecting a short circuit of one of the two first switches, the two second switches, and the three third switches based on the acquired voltage information, the drive device further including a first connection circuit, a second connection circuit, and a third connection circuit that are connected between an input terminal to which an input current is input and an output terminal from which an output current is output, in the first connection circuit, the two first switches are connected in series, in the second connection circuit, the two second switches are connected in series, in the third connection circuit, the three third switches are connected in series, the first motor is connected between a first connection node between the two first switches and a connection node between the two third switches on the output terminal side, the second motor is connected between a second connection node between the two second switches and a connection node between the two third switches on the input terminal side, and the node at which the first resistor and the second resistor are connected in series is connected to the first connection node. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 FIG. 1 is a block diagram illustrating a main part structure of a power supply system in Embodiment 1.

[0013] Figure 2 FIG. 2 is a circuit diagram for explaining a structure of a switching circuit.

[0014] Figure 3 FIG. 3 is a chart illustrating a driving method of a first motor and a second motor.

[0015] Figure 4 FIG. 4 is a chart illustrating PWM switching for the first motor and the second motor.

[0016] Figure 5 FIG. 5 is a block diagram illustrating a main part structure of a microcomputer.

[0017] Figure 6 FIG. 6 is a chart illustrating a sequence of short circuit detection processing.

[0018] Figure 7 FIG. 7 is a flowchart illustrating a sequence of normal driving processing.

[0019] Figure 8 FIG. 8 is a flowchart illustrating a sequence of first part driving processing.

[0020] Figure 9 is a flowchart showing the order of the second partial drive processing.

[0021] Figure 10 is a flowchart showing the order of the third partial drive processing.

[0022] Figure 11 is a flowchart showing the order of the third partial drive processing in Embodiment 2.

[0023] Figure 12 is a circuit diagram for explaining the structure of the switching circuit in Embodiment 3.

[0024] Figure 13 is a chart showing the order of the short-circuit detection processing.

[0025] Figure 14 is a circuit diagram for explaining the structure of the switching circuit in Embodiment 4.

[0026] Figure 15 is a circuit diagram of a series circuit in Embodiment 5.

[0027] Figure 16 is a chart showing the order of the short-circuit detection processing. DETAILED DESCRIPTION

[0028] [Problem to be Solved by the Disclosure]

[0029] As described in Patent Literature 1, in the conventional drive device in which a plurality of switches are provided, the two switches of the third circuit are switched to be turned on or off in the case where both the first motor and the second motor are operated, in the case where only the first motor is operated, and in the case where only the second motor is operated. Therefore, regarding the two switches of the third circuit, the frequency of switching is high, and the possibility of a short circuit occurring in each of the two switches of the third circuit is high.

[0030] In the case where both ends of one of the two switches of the third circuit are short-circuited, the current that can flow to the first motor and the second motor is limited to one of the currents in the first direction and the second direction. Therefore, in the case where both ends of one of the two switches of the third circuit are short-circuited, the first motor and the second motor do not function as motors that can rotate in the forward direction and the reverse direction.

[0031] Therefore, the object is to provide a short-circuit detection method and a computer program for a drive device and a switch provided in a drive device that can cause at least one motor to rotate in the forward direction and the reverse direction even in the case where both ends of one of a plurality of switches of a series circuit connected to two motors are short-circuited.

[0032] [Effects of the Disclosure]

[0033] The driving device according to the present disclosure enables at least one motor to rotate forward and reverse even when a short circuit occurs across one of the switches in the third connection circuit.

[0034] The short circuit detection method and computer program according to the present disclosure detect a short circuit of a switch included in a driving device.

[0035] [Explanation of Embodiments of the Present Disclosure]

[0036] First, an embodiment of the present disclosure will be explained. At least a part of the embodiment described below can be arbitrarily combined.

[0037] (1) A driving device of one embodiment of the present disclosure is a driving device that drives first and second motors whose rotation directions differ depending on the direction of current flowing therethrough, and includes first, second, and third connection circuits connected between an input terminal to which an input current is supplied and an output terminal from which an output current is supplied, two first switches connected in series in the first connection circuit, two second switches connected in series in the second connection circuit, three third switches connected in series in the third connection circuit, the first motor connected between a first connection node between the two first switches and a connection node between two third switches on the output terminal side, and the second motor connected between a second connection node between the two second switches and a connection node between two third switches on the input terminal side.

[0038] (2) A driving device of one embodiment of the present disclosure includes a series circuit in which a first resistor, a second resistor, and a circuit switch are connected in series, a resistance connection node between the first and second resistors is connected to the first connection node, and a constant voltage is applied, and a processing portion that performs processing, which switches the circuit switch to be on or off, acquires voltage information indicating a node voltage of the resistance connection node, and detects a short circuit of one of the two first switches, the two second switches, and the three third switches on the basis of the acquired voltage information.

[0039] (3) In a driving device of one embodiment of the present disclosure, the resistance connection node is a connection node on the downstream side of the circuit switch, the processing portion performs processing that instructs switching of the two first switches, the two second switches, and the three third switches to be off, and acquires the voltage information in the case where the circuit switch is off, and detects a short circuit of a first switch on the input terminal side on the basis of the acquired voltage information.

[0040] (4) In the driving device of one embodiment of the present disclosure, the resistance connection node is a connection node on the downstream side of the circuit switch, and the processing portion performs processing of instructing switching of the two first switches, the two second switches, and the three third switches to be off, and acquiring the voltage information in a case where the circuit switch is on, and detecting a short circuit of the first switch on the output side or the third switch on the output side on the basis of the acquired voltage information.

[0041] (5) In the driving device of one embodiment of the present disclosure, the resistance connection node is a connection node on the downstream side of the circuit switch, and the processing portion performs processing of instructing switching of the two first switches, the two second switches, the third switch on the input side, and the third switch on the output side to be off, instructing switching of the third switch connected between the third switch on the input side and the third switch on the output side to be on, and acquiring the voltage information in a case where the circuit switch is off, and detecting a short circuit of the second switch on the input side or the third switch on the input side on the basis of the acquired voltage information.

[0042] (6) In the driving device of one embodiment of the present disclosure, the resistance connection node is a connection node on the downstream side of the circuit switch, and the processing portion performs processing of instructing switching of the two first switches, the two second switches, the third switch on the input side, and the third switch on the output side to be off, instructing switching of the third switch connected between the third switch on the input side and the third switch on the output side to be on, and acquiring the voltage information in a case where the circuit switch is on, and detecting a short circuit of the second switch on the output side on the basis of the acquired voltage information.

[0043] (7) In the driving device of one embodiment of the present disclosure, the resistance connection node is a connection node on the downstream side of the circuit switch, and the processing portion performs processing of instructing switching of one or both of the second switch on the input side and the third switch on the input side to be on, instructing switching of the remaining switches of the two first switches, the two second switches, and the three third switches to be off, and acquiring the voltage information in a case where the circuit switch is off, and detecting a short circuit of the third switch connected between the third switch on the input side and the third switch on the output side on the basis of the acquired voltage information.

[0044] (8) In the driving device of one embodiment of the present disclosure, the processing portion performs processing of driving only the second motor by instructing switching of the two second switches and the three third switches to on or off, respectively, in a case where a short circuit of the output-side first switch or the output-side third switch is detected.

[0045] (9) In the driving device of one embodiment of the present disclosure, the processing portion performs processing of driving only the first motor by instructing switching of the two first switches and the three third switches to on or off, respectively, in a case where a short circuit of one of the two second switches and the input-side third switch is detected.

[0046] (10) In the driving device of one embodiment of the present disclosure, the processing portion performs processing of determining whether to drive the first motor in a case where a short circuit of the third switch connected between the input-side third switch and the output-side third switch is detected, and driving the second motor in a case where it is determined not to drive the first motor.

[0047] (11) In the driving device of one embodiment of the present disclosure, the processing portion performs processing of determining whether to drive the second motor in a case where a short circuit of the third switch connected between the input-side third switch and the output-side third switch is detected, and driving the first motor in a case where it is determined not to drive the second motor.

[0048] (12) In the driving device of one embodiment of the present disclosure, the number of the third connection circuits is two or more, the first motor is connected between a connection node between the two first switches and an output-side connection node between the two output-side third switches related to one of the plurality of third connection circuits, the second motor is connected between a connection node between the two second switches and an input-side connection node between the two input-side third switches related to a third connection circuit different from the third connection circuit to which the first motor is connected among the plurality of third connection circuits, a third motor whose rotational direction is different depending on the direction of current flowing therethrough is connected between an input-side connection node of one of the two third connection circuits and an output-side connection node of the other of the two third connection circuits, and the number of motors connected to the input-side connection node and the output-side connection node of each of the third connection circuits is one.

[0049] (13) In a short-circuit detection method of one embodiment of the present disclosure, a computer executes the steps of switching a circuit switch of a drive device between on and off, the drive device including two first switches, two second switches, three third switches, and a series circuit in which a first resistor, a second resistor, and the circuit switch are connected in series and to which a constant voltage is applied, the drive device driving a first motor and a second motor whose rotational directions differ depending on the direction of current flowing therethrough, acquiring voltage information indicating the voltage of a node between the first resistor and the second resistor, and detecting a short circuit in one of the two first switches, the two second switches, and the three third switches on the basis of the acquired voltage information, the drive device further including a first connection circuit, a second connection circuit, and a third connection circuit each connected between an input terminal to which an input current is input and an output terminal from which an output current is output, in the first connection circuit, the two first switches are connected in series, in the second connection circuit, the two second switches are connected in series, in the third connection circuit, the three third switches are connected in series, the first motor is connected between a first connection node between the two first switches and a connection node between the two third switches on the output terminal side, the second motor is connected between a second connection node between the two second switches and a connection node between the two third switches on the input terminal side, and the node between the first resistor and the second resistor is connected to the first connection node.

[0050] (14) A computer program of one embodiment of the present disclosure causes a computer to execute the steps of switching a circuit switch of a drive device between on and off, the drive device including two first switches, two second switches, three third switches, and a series circuit in which a first resistor, a second resistor, and the circuit switch are connected in series and to which a constant voltage is applied, the drive device driving a first motor and a second motor whose rotational directions differ depending on the direction of current flowing therethrough, acquiring voltage information indicating the voltage of a node between the first resistor and the second resistor, and detecting a short circuit in one of the two first switches, the two second switches, and the three third switches on the basis of the acquired voltage information, the drive device further including a first connection circuit, a second connection circuit, and a third connection circuit each connected between an input terminal to which an input current is input and an output terminal from which an output current is output, in the first connection circuit, the two first switches are connected in series, in the second connection circuit, the two second switches are connected in series, in the third connection circuit, the three third switches are connected in series, the first motor is connected between a first connection node between the two first switches and a connection node between the two third switches on the output terminal side, the second motor is connected between a second connection node between the two second switches and a connection node between the two third switches on the input terminal side, and the node between the first resistor and the second resistor is connected to the first connection node.

[0051] In the drive device of one embodiment described above, one end of the first motor is connected to a first connection node between the two first switches. One end of the second motor is connected to a connection node between the two second switches. As for the motor connected between the connection node between the normal two switches and the connection node between the normal other two switches, both the forward and reverse rotations can be achieved. Even when both ends of one of the three third switches are short-circuited, the other end of the first motor or the second motor is connected to a connection node between the remaining two third switches. Thus, even when both ends of one of the third switches included in the third connection circuit connected to the first motor and the second motor are short-circuited, the first motor or the second motor can be rotated forward and reverse.

[0052] In the drive device, the short-circuit detection method, and the computer program of one embodiment described above, the resistance connection node is, for example, a connection node on the downstream side of the circuit switch. When the two first switches, the two second switches, the third switch on the input side, and the third switch on the output side are off, the node voltage of the resistance connection node is a divided voltage obtained by dividing a constant voltage with the first resistor and the second resistor when the circuit switch is on. In the same case, the node voltage is zero V when the circuit switch is off. When the node voltage is different from the assumed voltage, the processing portion detects a short circuit of one of the two first switches, the two second switches, and the three third switches.

[0053] In the drive device of one embodiment described above, for example, a direct current voltage is applied to the input and the output, the direct current voltage is higher than a constant voltage, the voltage threshold value is higher than zero V and lower than a divided voltage. It is assumed that the number of switches in which a short circuit occurs is one. When the two first switches, the two second switches, and the three third switches are off, the node voltage is zero V, which is lower than the voltage threshold value when the circuit switch is off. When both ends of the first switch on the input side are short-circuited, the node voltage is the direct current voltage, which is higher than the voltage threshold value. Thus, in the case where the node voltage is higher than the voltage threshold value, a short circuit of the first switch on the input side is detected.

[0054] In the drive device of one embodiment, a direct-current voltage is applied as described above, and a voltage threshold value is set. It is assumed that the number of switches in which a short circuit occurs is one, and the resistance value of the resistance on the upstream side of the first resistor and the second resistor is sufficiently larger than the resistance component value of the first motor. In the case where the two first switches, the two second switches, and the three third switches are turned off, the node voltage is a divided voltage when the circuit switch is turned on, and is higher than the voltage threshold value. In the case where a short circuit occurs in the two first switches or the two second switches, the node voltage is substantially zero V, and is lower than the voltage threshold value. Thus, a short circuit of the two first switches or the two second switches is detected in the case where the node voltage is lower than the voltage threshold value.

[0055] In the drive device of one embodiment, a direct-current voltage is applied as described above, and a voltage threshold value is set. It is assumed that the number of switches in which a short circuit occurs is one, and the resistance value of the resistance on the downstream side of the first resistor and the second resistor is sufficiently larger than the resistance component value of the first motor and the second motor, and no short circuit occurs in the two first switches and the output-side third switch. These short circuits are detected by the above-described method, for example. Hereinafter, the third switch connected between the input-side third switch and the output-side third switch is referred to as a third intermediate switch.

[0056] In the case where the two first switches, the two second switches, the input-side third switch, and the output-side third switch are turned off and the third intermediate switch is turned on, the node voltage is zero V when the circuit switch is turned off, and is lower than the voltage threshold value. In the case where a short circuit occurs in the input-side second switch or the input-side third switch, the node voltage is substantially the direct-current voltage, and is higher than the voltage threshold value. Thus, a short circuit of the input-side second switch or the input-side third switch is detected in the case where the node voltage is higher than the voltage threshold value.

[0057] In the drive device of one embodiment, a direct-current voltage is applied as described above, and a voltage threshold value is set. It is assumed that the number of switches in which a short circuit occurs is one, and the resistance value of the resistance on the upstream side of the first resistor and the second resistor is sufficiently larger than the resistance component value of the first motor and the second motor, and no short circuit occurs in the two first switches, the input-side second switch, and the three third switches. These short circuits are detected by the above-described method, for example. In the case where the two first switches, the two second switches, the input-side third switch, and the output-side third switch are turned off and the third intermediate switch is turned on, the node voltage is a divided voltage when the circuit switch is turned on, and is higher than the voltage threshold value. In the case where a short circuit occurs in the output-side second switch, the node voltage is substantially zero V, and is lower than the voltage threshold value. Thus, a short circuit of the output-side second switch is detected in the case where the node voltage is lower than the voltage threshold value.

[0058] In the drive device of one embodiment described above, for example, as described above, the direct-current voltage is applied, and the voltage threshold value is set. It is assumed that the number of switches in which short-circuit occurs is one, and the resistance value of the resistance on the downstream side between the first resistor and the second resistor is sufficiently larger than the resistance component value of the first motor and the second motor. Further, it is assumed that short-circuit does not occur in the two first switches, the two second switches, the third switch on the input side, and the third switch on the output side. The short-circuit is detected by the above-described method, for example.

[0059] When the input-side second switch and one or both of the input-side third switches are on and the other switches are off in the case where short-circuit occurs in the two first switches, the two second switches, and the three third switches, the node voltage is zero V, which is lower than the voltage threshold value, at the time when the circuit is off. In the case where short-circuit occurs in both ends of the third intermediate switch, the node voltage is substantially the direct-current voltage, which is higher than the voltage threshold value. Thus, in the case where the node voltage is higher than the voltage threshold value, short-circuit of the third intermediate switch is detected.

[0060] In the drive device of one embodiment described above, in the case where short-circuit occurs in both ends of the first switch on the output side or the third switch on the output side, the rotational direction of the first motor is limited to one of the forward direction and the reverse direction, and thus only the second motor is driven.

[0061] In the drive device of one embodiment described above, in the case where short-circuit occurs in both ends of one of the two second switches and the third switch on the input side, the rotational direction of the second motor is limited to one of the forward direction and the reverse direction, and thus only the first motor is driven.

[0062] In the drive device of one embodiment described above, in the case where short-circuit occurs in both ends of the third intermediate switch, when one of the first motor and the second motor rotates, the rotational direction of the other motor is limited to one of the forward direction and the reverse direction. In the case where the first motor is driven, the second motor is not driven. Only in the case where the first motor is not driven, the second motor is driven.

[0063] In the drive device of one embodiment described above, in the case where short-circuit occurs in both ends of the third intermediate switch, when one of the first motor and the second motor rotates, the rotational direction of the other motor is limited to one of the forward direction and the reverse direction. In the case where the second motor is driven, the first motor is not driven. Only in the case where the second motor is not driven, the first motor is driven.

[0064] In the driving device of one embodiment described above, one end of the first motor is connected to a first connection node between the two first switches. One end of the second motor is connected to a connection node between the two second switches. The other end of the first motor or the second motor is connected to a connection node between normal two third switches even in the case where both ends of one third switch included in the third connection circuit are short-circuited. At least one motor among the first motor, the second motor, and the third motor can be caused to rotate forward and reverse even in the case where both ends of one third switch included in the third connection circuit connected to two motors among the first motor, the second motor, and the third motor are short-circuited.

[0065] [Details of Embodiments of the Present Disclosure]

[0066] Next, specific examples of a power supply system according to embodiments of the present disclosure will be described with reference to the accompanying drawings. Note that the present disclosure is not limited to these examples, and is represented by the claims, and is intended to include all modifications within the meaning and scope equivalent to those of the claims.

[0067] (Embodiment 1)

[0068] <Structure of Power Supply System>

[0069] Figure 1 is a block diagram illustrating a main part of the power supply system 1 in Embodiment 1. The power supply system 1 is appropriately mounted on a vehicle, and includes a driving device 10, a first motor 11, a second motor 12, and a direct-current power supply U. The direct-current power supply U is, for example, a storage battery. The driving device 10 is connected to one end and the other end of the first motor 11, and connected to one end and the other end of the second motor 12. The driving device 10 is further connected to a positive electrode of the direct-current power supply U. The driving device 10 and a negative electrode of the direct-current power supply U are grounded.

[0070] The first motor 11 and the second motor 12 each perform rotation of a rearview mirror, adjustment of an angle of a backrest of a seat, or opening and closing of a window, which is set at a place of a vehicle body. In the case where current flows through the first motor 11, the first motor 11 rotates. The rotation of the first motor 11 means that a rod-shaped rotor included in the first motor 11 rotates around an axis. In the case where a direction of the current flowing through the first motor 11 is a first direction, specifically, a downward direction of Figure 1 , the first motor 11 rotates forward. In the case where a direction of the current flowing through the first motor 11 is a second direction, specifically, an upward direction of Figure 1 , the first motor 11 rotates reverse. In the case where supply of the current to the first motor 11 is stopped, the first motor 11 stops rotating.

[0071] The second motor 12 is constructed similarly to the first motor 11. Therefore, in a case where the direction of the current flowing through the second motor 12 is the first direction, the second motor 12 rotates in the forward direction. In a case where the direction of the current flowing through the second motor 12 is the second direction, the second motor 12 rotates in the reverse direction. In a case where the supply of the current to the second motor 12 is stopped, the second motor 12 stops rotating.

[0072] With respect to the first motor 11 and the second motor 12, respectively, the forward direction is clockwise or counterclockwise. In a case where the forward direction is clockwise, the reverse direction is counterclockwise. In a case where the forward direction is counterclockwise, the reverse direction is clockwise. The forward direction of the first motor and the second motor can be the same or different from each other.

[0073] The drive device 10 drives the first motor 11 and the second motor 12. The drive device 10 supplies the current of the first direction to the first motor 11 or the second motor 12 in a case where the first motor 11 or the second motor 12 is caused to rotate in the forward direction. The drive device 10 supplies the current of the second direction to the first motor 11 or the second motor 12 in a case where the first motor 11 or the second motor 12 is caused to rotate in the reverse direction. The current supplied to the first motor 11 and the second motor 12 is output from a direct current power source U. The drive device 10 stops the supply of the current from the direct current power source U to the first motor 11 or the second motor 12 in a case where the operation of the first motor 11 or the second motor 12 is stopped.

[0074] A drive signal indicating the drive of one or both of the first motor 11 and the second motor 12 is input to the drive device 10. The drive signal indicates the drive motor in which the drive is performed among the first motor 11 and the second motor 12 and the direction of rotation of the drive motor. The direction of rotation is the forward direction or the reverse direction. A stop signal indicating the stop of the operation of the first motor 11 and the second motor 12 is input to the drive device 10.

[0075] In a case where the drive signal is input to the drive device 10, the drive device 10 drives one or both of the first motor 11 and the second motor 12 in accordance with the content of the input drive signal. For example, the drive device 10 causes the first motor 11 and the second motor 12 to rotate in the forward direction in a case where the drive signal indicating the rotation of the first motor 11 and the second motor 12 in the forward direction is input.

[0076] In a case where the stop signal is input to the drive device 10, the drive device 10 stops the operation of the first motor 11 and the second motor 12.

[0077] <Structure of the drive device 10>

[0078] The drive device 10 has a switching circuit 20, a microcomputer (hereinafter referred to as a micro) 21, a series circuit 22, and a voltage detection circuit 23. The series circuit 22 has a circuit switch 30, a first resistor 31, and a second resistor 32. In the series circuit 22, the circuit switch 30, the first resistor 31, and the second resistor 32 are connected in series. A constant voltage Vc with reference to a ground potential is applied to one end of the circuit switch 30. One end of the first resistor 31 is connected to the other end of the circuit switch 30. The other end of the first resistor 31 is connected to one end of the second resistor 32. The other end of the second resistor 32 is grounded.

[0079] Hereinafter, a voltage of a positive electrode of a direct current power supply U with reference to a ground potential is described as a power supply voltage, and a connection node between the first resistor 31 and the second resistor 32 is described as a resistor connection node. The constant voltage Vc is lower than the power supply voltage, and is generated by, for example, a voltage regulator that steps down the power supply voltage.

[0080] The switching circuit 20 is connected to the positive electrode of the direct current power supply U, one end and the other end of the first motor 11, and one end and the other end of the second motor 12. The switching circuit 20 is further connected to the micro 21 and the resistor connection node of the series circuit 22. The resistor connection node is further connected to the voltage detection circuit 23. The voltage detection circuit 23 is further connected to the micro 21.

[0081] The switching circuit 20 has a plurality of switches. The micro 21 instructs switching to be on or off with respect to the plurality of switches, respectively. The plurality of switches are switched to be on or off in accordance with the instruction of the micro 21, respectively. Thereby, the switching circuit 20 supplies a current of a first direction or a second direction to the first motor 11 and the second motor 12, respectively, and stops supply of the current to the first motor 11 and the second motor 12, respectively.

[0082] Hereinafter, a voltage of the resistor connection node with reference to a ground potential is described as a node voltage. The voltage detection circuit 23 detects the node voltage. The voltage detection circuit 23 outputs analog voltage information indicating the detected node voltage to the micro 21. The analog voltage information is, for example, a voltage obtained by dividing the node voltage.

[0083] The micro 21 switches the circuit switch 30 to be on or off. The micro 21 detects a short circuit of a switch of the switching circuit 20 based on voltage information input when the circuit switch 30 is on or off. The short circuit of the switch means that the switch is fixed to be on and the switch cannot be switched to be off.

[0084] <Structure of the Switching Circuit 20>

[0085] Figure 2is a circuit diagram for explaining the structure of the switching circuit 20. The switching circuit 20 has an input terminal 20a and an output terminal 20b. The input terminal 20a is connected to the positive electrode of the direct current power supply U. The output terminal 20b is grounded. Current is input from the positive electrode of the direct current power supply U to the input terminal 20a. Current is output from the output terminal 20b.

[0086] The switching circuit 20 has, in addition to the input terminal 20a and the output terminal 20b, a driving circuit 40, 41, 50, 51, D, E, F, a current detecting circuit 42, 52, G, a first connection circuit A, a second connection circuit B, and a third connection circuit C1. The first connection circuit A has a first input switch 60 and a first output switch 61. The second connection circuit B has a second input switch 70 and a second output switch 71. The third connection circuit C1 has a third input switch K1, a third intermediate switch M1, and a third output switch N1. The first input switch 60, the first output switch 61, the second input switch 70, the second output switch 71, the third input switch K1, the third intermediate switch M1, and the third output switch N1 are FETs (Field Effect Transistors) of N channel type, respectively.

[0087] In the first connection circuit A, the first input switch 60 and the first output switch 61 are connected in series. Specifically, the source of the first input switch 60 is connected to the drain of the first output switch 61. The first input switch 60 and the first output switch 61 function as first switches, respectively. In the second connection circuit B, the second input switch 70 and the second output switch 71 are connected in series. Specifically, the source of the second input switch 70 is connected to the drain of the second output switch 71. The second input switch 70 and the second output switch 71 function as second switches, respectively.

[0088] Hereinafter, a connection node between the first input switch 60 and the first output switch 61 is described as a first connection node. Further, a connection node between the second input switch 70 and the second output switch 71 is described as a second connection node.

[0089] In the third connection circuit C1, the third input switch K1, the third intermediate switch M1, and the third output switch N1 are connected in series. Specifically, the source of the third input switch K1 is connected to the drain of the third intermediate switch M1. The source of the third intermediate switch M1 is connected to the drain of the third output switch. The third input switch K1, the third intermediate switch M1, and the third output switch N1 function as a third switch.

[0090] The drain of the first input switch 60, the second input switch 70, and the third input switch K1 is connected to the input terminal 20a. The source of the first output switch 61, the second output switch 71, and the third output switch N1 is connected to the output terminal 20b. Therefore, the first connection circuit A, the second connection circuit B, and the third connection circuit C1 are connected between the input terminal 20a and the output terminal 20b, respectively.

[0091] The first motor 11 is connected between the first connection node and a connection node between the third input switch K1 and the third intermediate switch M1. The second motor 12 is connected between the second connection node and a connection node between the third intermediate switch M1 and the third output switch N1. The first connection node is further connected to the resistance connection node of the series circuit 22.

[0092] The first input switch 60, the first output switch 61, the second input switch 70, the second output switch 71, the third input switch K1, the third intermediate switch M1, and the third output switch N1 are connected to the drive circuits 40, 41, 50, 51, D, E, F, respectively. The drive circuits 40, 41, 50, 51, D, E, F are further connected to the microcomputer 21. The drive circuits 40, 50, D are connected to the current detection circuits 42, 52, G, respectively. The current detection circuits 42, 52, G are further connected to the microcomputer 21.

[0093] In the first input switch 60, in a case where the voltage of the gate with the potential of the source as a reference is equal to or higher than a reference voltage, the resistance value between the drain and the source is sufficiently small. At this time, the first input switch 60 is on, and a current can flow through the drain and the source. In the first input switch 60, in a case where the voltage of the gate with the potential of the source as a reference is lower than the reference voltage, the resistance value between the drain and the source is sufficiently large. At this time, the first input switch 60 is off, and a current does not flow through the drain and the source.

[0094] The first output switch 61, the second input switch 70, the second output switch 71, the third input switch K1, the third intermediate switch M1, and the third output switch N1 function in the same manner as the first input switch 60. The reference voltage of each of the first input switch 60, the first output switch 61, the second input switch 70, the second output switch 71, the third input switch K1, the third intermediate switch M1, and the third output switch N1 can be different from the reference voltage of the other switches.

[0095] The drive circuits 40, 41, 50, 51, D, E, F respectively switch the first input switch 60, the first output switch 61, the second input switch 70, the second output switch 71, the third input switch K1, the third intermediate switch M1, and the third output switch N1 to be on or off. The drive circuit 40, in a case where the first input switch 60 is switched to be on, causes the voltage of the gate of the first input switch 60 with reference to the ground potential to rise. Thereby, in the first input switch 60, the voltage of the gate with reference to the potential of the source becomes above the reference voltage, and the first input switch 60 is switched to be on. The drive circuit 40, in a case where the first input switch 60 is switched to be off, causes the voltage of the gate of the first input switch 60 with reference to the ground potential to fall. Thereby, in the first input switch 60, the voltage of the gate with reference to the potential of the source becomes below the reference voltage, and the first input switch 60 is switched to be off.

[0096] The drive circuits 41, 50, 51, D, E, F respectively switch the first output switch 61, the second input switch 70, the second output switch 71, the third input switch K1, the third intermediate switch M1, and the third output switch N1 to be on or off, similarly to the drive circuit 40.

[0097] The current detection circuit 42 is configured, for example, using a current mirror circuit, and detects the current flowing via the first input switch 60. The current detection circuit 42 outputs analog current information indicating the detected current to the microcomputer 21 and the drive circuit 40. The current information is, for example, a voltage proportional to the current flowing via the first input switch 60.

[0098] The current detection circuits 52, G respectively detect the current flowing via the second input switch 70 and the third input switch K1, similarly to the current detection circuit 42. The current detection circuit 52 outputs analog current information indicating the detected current to the microcomputer 21 and the drive circuit 50. The current detection circuit G outputs analog current information indicating the detected current to the microcomputer 21 and the drive circuit D.

[0099] A high-level voltage indicating switching to be on or a low-level voltage indicating switching to be off is respectively input from the microcomputer 21 to the drive circuits 40, 41, 50, 51, D, E, F. Hereinafter, the voltage input to the drive circuit which switches the switch to be on or off is described as an input voltage.

[0100] The drive circuit 40 switches the first input switch 60 to ON when the input voltage is switched to the high-level voltage in the case where the current indicated by the input current information is lower than the current threshold value. The drive circuit 40 switches the first input switch 60 to OFF when the input voltage is switched to the low-level voltage in the same case. The drive circuit 40 switches the first input switch 60 to OFF regardless of the input voltage in the case where the current indicated by the input current information becomes the current threshold value or more. Thereafter, the drive circuit 40 maintains the first input switch 60 OFF regardless of the current indicated by the input current information.

[0101] The drive circuits 50, D switch the second input switch 70 and the third input switch K1 to ON or OFF in the same manner as the drive circuit 40.

[0102] The drive circuits 41, 51, E, F switch the first output switch 61, the second output switch 71, the third intermediate switch Ml, and the third output switch Nl to ON in the case where the input voltage is switched to the high-level voltage. The drive circuits 41, 51, E, F switch the first output switch 61, the second output switch 71, the third intermediate switch Ml, and the third output switch Nl to OFF in the case where the input voltage is switched to the low-level voltage.

[0103] The microcomputer 21 switches the input voltages of the drive circuits 40, 41, 50, 51, D, E, F to the high-level voltage or the low-level voltage, respectively. Thus, the microcomputer 21 switches the first input switch 60, the first output switch 61, the second input switch 70, the second output switch 71, the third input switch K1, the third intermediate switch Ml, and the third output switch Nl to ON or OFF, respectively, to drive the first motor 11 and the second motor 12. As for the first motor 11 and the second motor 12, the current in the first direction is the right direction, and the current in the second direction is the left direction. Figure 2 Figure 2

[0104] <First Motor 11 and Second Motor 12 Driving Method>

[0105] Figure 3 Fig. 7 is a chart showing the driving method of the first motor 11 and the second motor 12. The "-" written in the column of the first motor 11 and the second motor 12 indicates the stop of the operation. The "-" written in the columns of the first input switch 60, the first output switch 61, the second input switch 70, the second output switch 71, the third input switch K1, the third intermediate switch Ml, and the third output switch Nl indicates OFF.

[0106] ​​In the case of forward rotation of the first motor 11, the first input switch 60 and the third output switch N1 are switched on, and the remaining switches possessed by the switching circuit 20 are switched off. Thereby, a current of the first direction flows through the first motor 11. In the case of reverse rotation of the first motor 11, the first output switch 61, the third input switch K1, and the third intermediate switch M1 are switched on, and the remaining switches possessed by the switching circuit 20 are switched off. Thereby, a current of the second direction flows through the first motor 11.

[0107] In the case of forward rotation of the second motor 12, the third input switch K1 and the second output switch 71 are switched on, and the remaining switches possessed by the switching circuit 20 are switched off. Thereby, a current of the first direction flows through the second motor 12. In the case of reverse rotation of the second motor 12, the third intermediate switch M1, the third output switch N1, and the second input switch 70 are switched on, and the remaining switches possessed by the switching circuit 20 are switched off. Thereby, a current of the second direction flows through the second motor 12.

[0108] In the case of forward rotation of the first motor 11 and the second motor 12, the first input switch 60, the third input switch K1, the third output switch N1, and the second output switch 71 are switched on, and the remaining switches possessed by the switching circuit 20 are switched off. Thereby, a current of the first direction flows through the first motor 11 and the second motor 12.

[0109] In the case of forward and reverse rotation of the first motor 11 and the second motor 12, respectively, the first input switch 60, the third intermediate switch M1, the third output switch N1, and the second input switch 70 are switched on, and the remaining switches possessed by the switching circuit 20 are switched off. Thereby, a current of the first direction flows through the first motor 11, and a current of the second direction flows through the second motor 12.

[0110] In the case of reverse and forward rotation of the first motor 11 and the second motor 12, respectively, the first output switch 61, the third input switch K1, the third intermediate switch M1, and the second output switch 71 are switched on, and the remaining switches possessed by the switching circuit 20 are switched off. Thereby, a current of the second direction flows through the first motor 11, and a current of the first direction flows through the second motor 12.

[0111] In the case of reverse rotation of the first motor 11 and the second motor 12, the first output switch 61, the third intermediate switch M1, and the second input switch 70 are switched on, and the remaining switches possessed by the switching circuit 20 are switched off. Thereby, a current of the second direction flows through the first motor 11 and the second motor 12.

[0112] <Adjustment of the rotation speed of the first motor 11 and the second motor 12>

[0113] The rotational speed of each of the first motor 11 and the second motor 12 is proportional to the average value of the current supplied to the first motor 11 and the second motor 12. Therefore, with respect to at least one switch of the switching circuit 20, PWM (Pulse Width Modulation) control is performed, so that the rotational speed of the first motor 11 and the second motor 12 can be adjusted. Hereinafter, the switch that is the object of the PWM control will be described as a PWM switch.

[0114] The PWM control is control in which the switching of the switch to on and off is alternately repeated. The switching of the switch to on or off is periodically performed. By adjusting the ratio of the period in which the switch is on in one cycle, that is, the duty ratio, the average value of the current flowing through the first motor 11 or the second motor 12 is adjusted. The greater the duty ratio, the greater the average value of the current.

[0115] Figure 4 is a graph showing the PWM switch for the first motor 11 and the second motor 12. As shown in Figure 4 In the case where the first motor 11 is caused to rotate forward, PWM control is performed with respect to the first input switch 60 or the third output switch N1. In the case where the first motor 11 is caused to rotate in reverse, PWM control is performed with respect to the first output switch 61, the third input switch K1, or the third intermediate switch M1.

[0116] In the case where the second motor 12 is caused to rotate forward, PWM control is performed with respect to the second output switch 71 or the third input switch K1. In the case where the second motor 12 is caused to rotate in reverse, PWM control is performed with respect to the second input switch 70, the third intermediate switch M1, or the third output switch N1.

[0117] In the case where the first motor 11 and the second motor 12 are caused to rotate forward, PWM control is performed with respect to the first input switch 60 or the third output switch N1, so that the rotational speed of the first motor 11 is adjusted. PWM control is performed with respect to the second output switch 71 or the third input switch K1, so that the rotational speed of the second motor 12 is adjusted.

[0118] In the case where the first motor 11 and the second motor 12 are caused to rotate forward and in reverse, respectively, PWM control is performed with respect to the first input switch 60 or the third output switch N1, so that the rotational speed of the first motor 11 is adjusted. PWM control is performed with respect to the second input switch 70, the third intermediate switch M1, or the third output switch N1, so that the rotational speed of the second motor 12 is adjusted. Here, in the case where PWM control is performed with respect to the third output switch N1, the current supplied to the first motor 11 and the second motor 12 is adjusted, and the rotational speed of the first motor 11 and the second motor 12 is adjusted.

[0119] In the case where the first motor 11 and the second motor 12 are caused to rotate in the reverse and forward directions, respectively, PWM control is performed with respect to the first output switch 61, the third input switch Kl, or the third intermediate switch Ml, so as to adjust the rotational speed of the first motor 11. PWM control is performed with respect to the second output switch 71 or the third input switch Kl, so as to adjust the rotational speed of the second motor 12. Here, in the case where PWM control is performed with respect to the third input switch Kl, the current supplied to the first motor 11 and the second motor 12 is adjusted, and the rotational speeds of the first motor 11 and the second motor 12 are adjusted.

[0120] In the case where the first motor 11 and the second motor 12 are caused to rotate in the reverse direction, PWM control is performed with respect to the first output switch 61, the second input switch 70, or the third intermediate switch Ml, so as to adjust the rotational speeds of the first motor 11 and the second motor 12.

[0121] In the case where the first motor 11 and the second motor 12 are caused to rotate in the reverse direction, the first output switch 61, the second input switch 70, and the third intermediate switch Ml are switched to be turned on, and the first motor 11 and the second motor 12 are connected in series. In other cases, one end and the other end are connected to the input terminal 20a and the output terminal 20b, respectively, with respect to the first motor 11 and the second motor 12, respectively. Therefore, the current flowing through the first motor 11 in the case where the first motor 11 and the second motor 12 are caused to rotate in the reverse direction is smaller than the current flowing through the first motor 11 in other cases. The current flowing through the second motor 12 in the case where the first motor 11 and the second motor 12 are caused to rotate in the reverse direction is smaller than the current flowing through the second motor 12 in other cases.

[0122] Therefore, the duty ratio of the PWM control in the case where the first motor 11 and the second motor 12 are caused to rotate in the reverse direction is set to a value larger than the duty ratio of the PWM control in the case where only the first motor 11 or only the second motor 12 is caused to rotate. Thus, it is possible to adjust the rotational speeds of the first motor 11 and the second motor 12 in the case where the first motor 11 and the second motor 12 are caused to rotate in the reverse direction to the same speeds as the rotational speeds of the first motor 11 and the second motor 12 in other cases.

[0123] The microcomputer 21 outputs a PWM signal that alternately repeats switching to a high-level voltage and a low-level voltage to a drive circuit that drives the PWM switch. Thus, PWM control is performed. The switching to the high-level voltage or the low-level voltage is performed periodically by the PWM signal. The proportion of the period in which the high-level voltage is occupied in one cycle corresponds to the duty ratio of the PWM control.

[0124] Generally, regarding the drive circuit that switches the switch to on or off based on the input voltage and current information, the period from switching the input voltage to the high level voltage or the low level voltage to performing the switching of the switch to on or off is long. Therefore, the PWM switch is preferably a switch that is switched to on or off by the drive circuit based on only the input voltage, i.e., the first output switch 61, the second output switch 71, the third intermediate switch Ml, or the third output switch Nl.

[0125] <Structure of microcomputer 21>

[0126] Figure 5 is a block diagram showing the main part structure of the microcomputer 21. The microcomputer 21 has an output section 80, A / D conversion sections 81, 82, a switching section 83, input sections 84, 85, 86, a storage section 87, and a control section 88. The output section 80, the A / D conversion sections 81, 82, the switching section 83, the input sections 84, the storage section 87, and the control section 88 are connected to an internal bus 89. The output section 80 is further connected to the drive circuits 40, 41, 50, 51, D, E, F of the switching circuit 20, respectively.

[0127] The A / D conversion section 81 is further connected to the input section 85. The input section 85 is further connected to the current detection circuits 42, 52, G of the switching circuit 20, respectively. The A / D conversion section 82 is further connected to the input section 86. The input section 86 is further connected to the voltage detection circuit 23.

[0128] The output section 80 switches the input voltage of the drive circuits 40, 41, 50, 51, D, E, F to the high level voltage or the low level voltage in accordance with the instruction of the control section 88. Further, the output section 80 outputs the PWM signal to the drive circuits 40, 41, 50, 51, D, E, F in accordance with the instruction of the control section 88. The duty ratio of the PWM signal output to the drive circuits 40, 41, 50, 51, D, E, F is set respectively. The control section 88 can also change these duty ratios.

[0129] The current detection circuits 42, 52, G output the analog current information to the input section 85, respectively. The input section 85 outputs the input analog current information to the A / D conversion section 81 in a case where the analog current information is input from the current detection circuits 42, 52, G. The A / D conversion section 81 converts the analog current information input from the input section 85 into the digital current information.

[0130] The control section 88 acquires the digital current information converted by the A / D conversion section 81. In a case where the control section 88 acquires the current information output from one of the current detection circuits 42, 52, G from the A / D conversion section 81, the current indicated by the acquired current information substantially coincides with the current detected at the time of acquisition.

[0131] The switching section 83 switches the circuit switch 30 of the series circuit 22 to be on or off in accordance with an instruction of the control section 88.

[0132] The voltage detection circuit 23 outputs analog voltage information indicating the node voltage to the input section 86. The input section 86 outputs the input analog voltage information to the A / D conversion section 82 in a case where the analog voltage information is input. The A / D conversion section 82 converts the analog voltage information input from the input section 86 into digital voltage information. The control section 88 acquires the digital voltage information from the A / D conversion section 82. The node voltage indicated by the voltage information acquired by the control section 88 substantially coincides with the node voltage detected by the voltage detection circuit 23 at the time of acquisition.

[0133] A drive signal and a stop signal are input to the input section 84. The input section 84 notifies the control section 88 of the content of the input drive signal, that is, the motor to be driven and the rotation direction of the motor to be driven in a case where the drive signal is input. The input section 84 notifies the control section 88 of the input of the stop signal in a case where the stop signal is input.

[0134] The storage section 87 is a nonvolatile memory. A computer program P is stored in the storage section 87. The control section 88 has a processing element such as a CPU (Central Processing Unit) that executes processing, and functions as a processing section. The processing element of the control section 88 executes the short-circuit detection processing, the normal drive processing, the first partial drive processing, the second partial drive processing, and the third partial drive processing by executing the computer program P.

[0135] The short-circuit detection processing is processing of detecting a short circuit of the switches possessed by the switching circuit 20. The normal drive processing is processing of driving one or both of the first motor 11 and the second motor 12, and is executed in a case where all the switches possessed by the switching circuit 20 are normal. The first partial drive processing is processing of driving only the first motor 11, and is executed in a case where both ends of the first output switch 61 or the third output switch N1 are short-circuited. The second partial drive processing is processing of driving only the second motor 12, and is executed in a case where both ends of the second input switch 70, the second output switch 71, or the third input switch K1 are short-circuited. The third partial drive processing is processing of driving the first motor 11 or the second motor 12, and is executed in a case where both ends of the third intermediate switch M1 are short-circuited.

[0136] Further, the computer program P can also be stored in the storage medium H in a manner readable by the processing element of the control section 88. In this case, the computer program P read out from the storage medium H by a readout device not shown is stored in the storage section 87. The storage medium H is an optical disk, a flexible disk, a magnetic disk, a magneto-optical disk, or a semiconductor memory, etc. The optical disk is a CD (Compact Disc) -ROM (Read Only Memory), a DVD (Digital Versatile Disc) -ROM, or a BD (Blu-ray (registered trademark) Disc), etc. The magnetic disk is, for example, a hard disk. Further, the computer program P can also be downloaded from an external device not shown connected to a communication network not shown, and stored in the storage section 87.

[0137] The number of processing elements possessed by the control section 88 can also be two or more. In this case, the plurality of processing elements can also execute the short-circuit detection processing, the normal drive processing, the first partial drive processing, the second partial drive processing, and the third partial drive processing in parallel, respectively.

[0138] <Short-circuit detection processing>

[0139] Figure 6 is a chart showing the order of the short-circuit detection processing. The control section 88 executes the short-circuit detection processing in the case where the first motor 11 and the second motor 12 are stopped from operating. The short-circuit detection condition is a condition considered to have occurred a short circuit. The short-circuit switch is a switch having both ends short-circuited. The prohibited motor is a motor prohibited from being driven.

[0140] In the storage section 87, a constant voltage threshold is stored in advance. The voltage threshold exceeds zero V, and is a voltage divided voltage or less obtained by dividing the constant voltage Vc by the first resistor 31 and the second resistor 32. Further, it is assumed that in the switches possessed by the switching circuit 20, i.e., the first input switch 60, the first output switch 61, the second input switch 70, the second output switch 71, the third input switch K1, the third intermediate switch M1, and the third output switch N1, two or more switches do not have both ends short-circuited.

[0141] The resistance values ​​of the first resistor 31 and the second resistor 32 are each sufficiently greater than the resistance component value of the first motor 11 and sufficiently greater than the resistance component value of the second motor 12. Furthermore, the control unit 88 instructs the output unit 80 to switch the switches in the switching circuit 20 to either on or off. According to the instruction of the control unit 88, the output unit 80 switches the voltages output to the drive circuits 40, 41, 50, 51, D, E, and F to either a high-level voltage or a low-level voltage. As described above, the drive circuits 40, 41, 50, 51, D, E, and F switch the first input switch 60, the first output switch 61, the second input switch 70, the second output switch 71, the third input switch K1, the third intermediate switch M1, and the third output switch N1 to either on or off based on the input voltage.

[0142] The control unit 88 first executes sequence 1. In sequence 1, the control unit 88 instructs the output unit 80 to switch all switches in the switching circuit 20 to open. Further, the control unit 88 instructs the switching unit 83 to switch the circuit switch 30 of the series circuit 22 to open. In this state, the control unit 88 obtains voltage information representing the node voltage of the resistive connection node from the A / D conversion unit 82.

[0143] Here, with all switches in the switching circuit 20 functioning normally, the node voltage is zero V, below the voltage threshold. When the first input switch 60 is short-circuited, the node voltage is substantially the same as the DC power supply voltage U, which is above the voltage threshold. Therefore, if the node voltage indicated by the acquired voltage information is above the voltage threshold, the control unit 88 detects a short circuit in the first input switch 60. Upon detecting a short circuit in the first input switch 60, the control unit 88 disables the driving of the first motor 11 and the second motor 12, ending the short circuit detection process.

[0144] When the two ends of the first input switch 60 are short-circuited, the second direction ( Figure 2 The current in the left direction cannot flow through the first motor 11. Furthermore, when the second input switch 70, the third intermediate switch M1, and the third output switch N1 are switched on to supply current in the second direction to the second motor 12, the current in the first direction (left direction) cannot flow through the first motor 11. Figure 2 A current (in the right direction) is supplied to the first motor 11, which rotates in the forward direction. Therefore, the driving of the first motor 11 and the second motor 12 is disabled.

[0145] If no short circuit is detected in the first input switch 60, the control unit 88 executes sequence 2. In sequence 2, while instructing the output unit 80 to switch all switches of the switching circuit 20 to open, the control unit 88 instructs the switching unit 83 to switch the circuit switch 30 to close. In this state, the control unit 88 obtains voltage information from the A / D conversion unit 82.

[0146] Here, in a case where all the switches possessed by the switching circuit 20 are normal, the node voltage is the divided voltage, which is above the voltage threshold. In a case where either the first output switch 61 or the third output switch Nl is short-circuited, the node voltage is substantially zero V, which is below the voltage threshold. Therefore, the control section 88 detects the short-circuit of either the first output switch 61 or the third output switch Nl in a case where the node voltage indicated by the voltage information acquired is below the voltage threshold. The control section 88 prohibits the drive of the first motor 11 in a case where the short-circuit of either the first output switch 61 or the third output switch Nl is detected, and ends the short-circuit detection process.

[0147] In a case where either the first output switch 61 or the third output switch Nl is short-circuited, the current of either the first direction or the second direction cannot be supplied to the first motor 11, so the drive of the first motor 11 is prohibited.

[0148] In a case where all the switches possessed by the switching circuit 20 are off, when the circuit switch 30 is on, the current flows through the circuit switch 30, the first resistor 31, and the second resistor 32 in this order. Therefore, the resistance connection node between the first resistor 31 and the second resistor 32 is the connection node on the downstream side of the circuit switch 30.

[0149] Further, the circuit switch 30 can also be connected between the first resistor 31 and the second resistor 32. In this case, a constant voltage Vc is applied to one end of the first resistor 31, and the resistance connection node is the connection node between the circuit switch 30 and the second resistor 32.

[0150] The control section 88 executes order 3 in a case where the short-circuit of either the first output switch 61 or the third output switch Nl is not detected in order 2. In order 3, the control section 88 instructs the output section 80 to perform switching to on only for the third intermediate switch Ml among the switches possessed by the switching circuit 20. Since the switching to on is instructed only for the third intermediate switch Ml, as for the switches other than the third intermediate switch Ml among the switches possessed by the switching circuit 20, the switching to off is instructed. Further, the control section 88 instructs the switching section 83 to switch the circuit switch 30 to off. In this state, the control section 88 acquires voltage information from the A / D conversion section 82.

[0151] Here, in a case where all the switches possessed by the switching circuit 20 are normal, the node voltage is zero V, which is lower than the voltage threshold. In a case where either the second input switch 70 or the third input switch K1 is short-circuited, the node voltage is substantially identical to the power supply voltage of the direct-current power supply U, which is higher than the voltage threshold. Therefore, the control section 88 detects the short-circuit of either the second input switch 70 or the third input switch K1 in a case where the node voltage indicated by the voltage information acquired is higher than the voltage threshold. The control section 88 prohibits the driving of the second motor 12 in a case where the short-circuit of either the second input switch 70 or the third input switch K1 is detected, and ends the short-circuit detection processing.

[0152] In a case where either the second input switch 70 or the third input switch K1 is short-circuited, the current in the second direction or the first direction cannot be supplied to the second motor 12, so the driving of the second motor 12 is prohibited.

[0153] The control section 88 executes order 4 in a case where the short-circuit of either the second input switch 70 or the third input switch K1 is not detected. In order 4, the control section 88 instructs the switching section 83 to switch the circuit switch 30 to be on in a state where the output section 80 performs only the switching of the third intermediate switch M1 to be on among the switches possessed by the switching circuit 20. In this state, the control section 88 acquires the voltage information from the A / D conversion section 82.

[0154] Here, in a case where all the switches possessed by the switching circuit 20 are normal, the node voltage is the divided voltage, which is higher than the voltage threshold. In a case where the second output switch 71 is short-circuited, the node voltage is substantially zero V, which is lower than the voltage threshold. Therefore, the control section 88 detects the short-circuit of the second output switch 71 in a case where the node voltage indicated by the voltage information acquired is lower than the voltage threshold. The control section 88 prohibits the driving of the second motor 12 in a case where the short-circuit of the second output switch 71 is detected, and ends the short-circuit detection processing.

[0155] In a case where the second output switch 71 is short-circuited, the current in the second direction cannot be supplied to the second motor 12, so the driving of the second motor 12 is prohibited.

[0156] The control section 88 executes order 5 in a case where the short-circuit of the second output switch 71 is not detected. In order 5, the control section 88 instructs the output section 80 to perform only the switching of the third input switch K1 to be on. Since the switching to be on is instructed only to the third input switch K1, among the switches possessed by the switching circuit 20, the switching to be off is instructed with respect to the switches other than the third input switch K1. Further, the control section 88 instructs the switching section 83 to switch the circuit switch 30 to be off. In this state, the control section 88 acquires the voltage information from the A / D conversion section 82.

[0157] Here, in a case where all the switches possessed by the switching circuit 20 are normal, the node voltage is zero V, which is lower than the voltage threshold. In a case where both ends of the third intermediate switch Ml are short-circuited, the node voltage is substantially identical to the power supply voltage of the direct-current power supply U, which is higher than the voltage threshold. The control section 88 detects the short-circuit of the third intermediate switch Ml in a case where the node voltage indicated by the voltage information acquired is higher than the voltage threshold, and prohibits the driving of the first motor 11 or the second motor 12.

[0158] In a case where both ends of the third intermediate switch Ml are short-circuited, the current in the first direction or the second direction cannot be supplied to both the first motor 11 and the second motor 12. In a case where one of the first motor 11 or the second motor 12 rotates, the rotational direction of the other motor is limited to one of the forward direction and the reverse direction. The prohibition of the driving of the first motor 11 or the second motor 12 means that the driving of the other motor is prohibited in a case where one of the first motor 11 and the second motor 12 is driven.

[0159] The control section 88 ends the short-circuit detection processing after executing the sequence 5. The control section 88 executes the normal driving processing, the first partial driving processing, the second partial driving processing, or the third partial driving processing after executing the short-circuit detection processing.

[0160] Further, in the sequence 5, the control section 88 can also replace the instruction to the output section 80 to switch only the third input switch Kl to ON with an instruction to the output section 80 to switch only the second input switch 70 to ON, or an instruction to the output section 80 to switch both the third input switch Kl and the second input switch 70 to ON.

[0161] <Normal driving processing>

[0162] Figure 7 Fig. 16 is a flowchart showing the sequence of the normal driving processing. The control section 88 executes the normal driving processing when the driving signal is input to the input section 84 in a case where all the switches possessed by the switching circuit 20 are normal. In the normal driving processing, the control section 88 first causes the switching circuit 20 to drive one or both of the first motor 11 and the second motor 12 in accordance with the content of the driving signal input to the input section 84 (step Sl).

[0163] Specifically, the control section 88 instructs the output section 80 to switch the switches possessed by the switching circuit 20 to ON or OFF, respectively. The output section 80 switches the switches possessed by the switching circuit 20 to ON or OFF, respectively, in accordance with the content of the driving signal input to the input section 84. The output section 80 outputs a PWM signal to the driving circuit that switches the PWM switch to ON or OFF, and performs PWM control with respect to the PWM switch.

[0164] In a case where the drive signal input to the input section 84 indicates the first motor 11 as the drive motor and indicates the forward direction as the rotation direction of the first motor 11, as shown in FIG. 8, the output section 80 switches the first input switch 60 and the third output switch N1 to ON and switches the other switches to OFF. Thereby, the current of the first direction is supplied to the first motor 11. Further, the output section 80 outputs the PWM signal to one of the drive circuits 40, F. Thereby, the PWM control is performed with respect to the first input switch 60 or the third output switch N1, and the rotation speed of the first motor 11 is adjusted. Figure 3

[0165] The control section 88, after executing the step S1, determines whether or not the drive signal is input to the input section 84 (step S2). The control section 88, in a case where it is determined that the drive signal is not input (S2: No), determines whether or not the stop signal is input to the input section 84 (step S3). The control section 88, in a case where it is determined that the stop signal is not input (S3: No), executes the step S2 again and stands by until the drive signal or the stop signal is input to the input section 84.

[0166] The control section 88, in a case where it is determined that the drive signal is input (S2: Yes), instructs the output section 80 to switch all of the input switches, that is, the first input switch 60, the second input switch 70, and the third input switch K1 to OFF (step S4). Thereby, the supply of the current to the first motor 11 and the second motor 12 is stopped, and the first motor 11 and the second motor 12 stop operating.

[0167] The control section 88, after executing the step S4, instructs the output section 80 to switch the third intermediate switch M1 and all of the output switches to ON (step S5). All of the output switches are the first output switch 61, the second output switch 71, and the third output switch N1. In a case where one or both of the first motor 11 and the second motor 12 are driven, the current is supplied to the first motor 11 or the second motor 12, and the energy is accumulated in the coil of the first motor 11 or the second motor 12. In a case where the third intermediate switch M1 and all of the output switches are ON, the coil of the first motor 11 or the second motor 12 outputs the current, and the energy is discharged.

[0168] The control section 88, after executing the step S5, executes the step S1, and causes the switching circuit 20 to drive one or both of the first motor 11 and the second motor 12 in accordance with the content of the new drive signal input to the input section 84.

[0169] ​The control section 88, in the case where it is determined that the stop signal is input (S3: YES), instructs the output section 80 to switch all the input switches to OFF, as in step S4 (step S6). Thus, the first motor 11 and the second motor 12 stop operating. The control section 88, after executing step S6, instructs the output section 80 to switch the third intermediate switch Ml and all the output switches to ON, as in step S5 (step S7). Thus, the coil of the first motor 11 or the second motor 12 discharges energy.

[0170] The control section 88, after executing step S7, instructs the output section 80 to switch all the switches possessed by the switching circuit 20 to OFF (step S8), and ends the normal drive processing.

[0171] <First Partial Drive Processing>

[0172] Figure 8 is a flowchart showing the order of the first partial drive processing. The control section 88 executes the first partial drive processing when the drive signal is input to the input section 84 in the case where the prohibited motor is the second motor 12. In the first partial drive processing, the control section 88 first determines whether or not to drive the first motor 11 based on the drive signal input to the input section 84 (step Sll). In step Sll, the control section 88 determines to drive the first motor 11 in the case where the first motor 11 is included in the drive motor indicated by the drive signal. The control section 88 determines not to drive the first motor 11 in the case where the drive signal indicates only the second motor 12 as the drive motor.

[0173] The control section 88, in the case where it is determined to drive the first motor 11 (Sll: YES), drives the first motor 11 in accordance with the content of the drive signal input to the input section 84 (step S12). Specifically, the control section 88 drives the first motor 11 by instructing the output section 80 to switch the first input switch 60, the first output switch 61, the third input switch Kl, the third intermediate switch Ml, and the third output switch Nl to ON or OFF, respectively. The control section 88 instructs the output section 80 to output the PWM signal to the drive circuit that switches the PWM switch to ON or OFF. Thus, PWM control is performed with respect to the PWM switch. Since the drive of the second motor 12 is prohibited, the second motor 12 is not driven in the first partial drive processing.

[0174] In the case where the drive signal input to the input section 84 indicates the forward direction as the rotation direction of the first motor 11, as in Figure 3As shown, the output section 80 switches the first input switch 60 and the third output switch N1 to be on, and switches the other switches to be off. Thereby, the current of the first direction is supplied to the first motor 11. Further, the output section 80 outputs the PWM signal to one of the drive circuit 40, F. Thereby, the PWM control is performed with respect to the first input switch 60 or the third output switch N1, and the rotation speed of the first motor 11 is adjusted. As the PWM switch, the switch different from the short-circuit switch is selected.

[0175] The control section 88, after executing the step S12, determines whether or not the drive signal or the stop signal is input to the input section 84 (step S13). The control section 88, in a case where it is determined that the drive signal or the stop signal is not input to the input section 84 (S13: No), executes the step S13 again, and stands by until the drive signal or the stop signal is input to the input section 84.

[0176] The control section 88, in a case where it is determined that the drive signal or the stop signal is input (S13: Yes), instructs the output section 80 to switch the first input switch 60, the third input switch K1, and the third intermediate switch M1 to be off (step S14). Thereby, the supply of the current to the first motor 11 is stopped, and the first motor 11 stops operating. At the time when the step S14 is executed, the both ends of the third input switch K1 can be short-circuited. In this case, the output section 80 cannot switch the third input switch K1 to be off. However, since the third intermediate switch M1 is switched to be off, the first motor 11 stops operating.

[0177] The control section 88, after executing the step S14, instructs the output section 80 to switch the first output switch 61 and the third output switch N1 to be on (step S15). Thereby, the coil of the first motor 11 discharges the energy. The control section 88, after executing the step S15, determines whether or not the input signal input to the input section 84 is the drive signal (step S16). The control section 88, in a case where it is determined that the input signal is the drive signal (S16: Yes), executes the step S11. When the first motor 11 is included in the drive motor indicated by the drive signal newly input to the input section 84, the switch circuit 20 drives the first motor 11 in accordance with the content of the newly input drive signal.

[0178] The control section 88, in a case where it is determined that the first motor 11 is not driven (S11: No), or in a case where it is determined that the input signal is not the drive signal (S16: No), instructs the output section 80 to switch all the switches possessed by the switch circuit 20 to be off (step S17), and ends the first partial drive processing. In a case where the step S17 is executed, the other switches than the short-circuit switch among the switches possessed by the switch circuit 20 are switched to be off.

[0179] <Second partial drive processing>

[0180] Figure 9 is a flowchart showing the order of the second partial drive processing. The control section 88 executes the second partial drive processing when the drive signal is input to the input section 84 in the case where the motor to be inhibited is the first motor 11. In the second partial drive processing, the control section 88 first determines whether or not to drive the second motor 12 based on the drive signal input to the input section 84 (step S21). In step S21, the control section 88 determines to drive the second motor 12 when the second motor 12 is included in the drive motor indicated by the drive signal. The control section 88 determines not to drive the second motor 12 when the drive signal indicates only the first motor 11 as the drive motor.

[0181] The control section 88 drives the second motor 12 in accordance with the content of the drive signal input to the input section 84 when it is determined to drive the second motor 12 (S21: "Yes") (step S22). Specifically, the control section 88 instructs the output section 80 to switch the second input switch 70, the second output switch 71, the third input switch Kl, the third intermediate switch Ml, and the third output switch Nl to be turned on or off, respectively, thereby driving the second motor 12. The control section 88 instructs the output section 80 to output the PWM signal to the drive circuit that switches the PWM switch to be turned on or off. Thus, PWM control is performed with respect to the PWM switch. Since the drive of the first motor 11 is inhibited, the first motor 11 is not driven in the second partial drive processing.

[0182] When the drive signal input to the input section 84 indicates the forward direction as the rotation direction of the second motor 12, as shown in Figure 3 , the output section 80 switches the third input switch Kl and the second output switch 71 to be turned on and switches the other switches to be turned off. Thus, the current of the first direction is supplied to the second motor 12. Further, the output section 80 outputs the PWM signal to one of the drive circuits D, 51. Thus, PWM control is performed with respect to the third input switch Kl or the second output switch 71, and the rotation speed of the second motor 12 is adjusted. As the PWM switch, a switch different from the short-circuit switch is selected.

[0183] The control section 88 determines whether or not the drive signal or the stop signal is input to the input section 84 after step S22 is executed (step S23). The control section 88 executes step S23 again and stands by until the drive signal or the stop signal is input to the input section 84 when it is determined that the drive signal or the stop signal is not input to the input section 84 (S23: "No").

[0184] The control section 88 instructs the output section 80 to switch the second input switch 70 and the third input switch K1 to OFF (step S24) in a case where it is determined that the drive signal or the stop signal has been input (S23: YES). Thereby, the supply of the current to the second motor 12 is stopped, and the second motor 12 stops operating.

[0185] The control section 88 instructs the output section 80 to switch the second output switch 71, the third intermediate switch M1, and the third output switch N1 to ON after step S24 is executed (step S25). Thereby, the coil of the second motor 12 discharges energy. At the time when step S25 is executed, the both ends of the third output switch N1 can be short-circuited. In this case, since the third output switch N1 is short-circuited, the coil of the second motor 12 also discharges energy.

[0186] The control section 88 determines whether the input signal input to the input section 84 is the drive signal after step S25 is executed (step S26). The control section 88 executes step S21 in a case where it is determined that the input signal is the drive signal (S26: YES). When the second motor 12 is included in the drive motor indicated by the drive signal newly input to the input section 84, the switch circuit 20 drives the second motor 12 in accordance with the content of the newly input drive signal.

[0187] The control section 88 instructs the output section 80 to switch all the switches possessed by the switch circuit 20 to OFF (step S27) in a case where it is determined that the second motor 12 is not driven (S21: NO), or in a case where it is determined that the input signal is not the drive signal (S26: NO), and ends the second partial drive processing. In a case where step S27 is executed, the switches other than the short-circuit switch among the switches possessed by the switch circuit 20 are switched to OFF.

[0188] <Third Partial Drive Processing>

[0189] Figure 10 is a flowchart showing the order of the third partial drive processing. The control section 88 executes the third partial drive processing when the drive signal is input to the input section 84 in a case where the motor to be inhibited is the first motor 11 or the second motor 12, that is, in a case where the short-circuit of the third intermediate switch M1 is detected. In the third partial drive processing, the control section 88 first determines whether the first motor 11 is driven on the basis of the drive signal input to the input section 84 as in step S11 of the first partial drive processing (step S31).

[0190] When the control section 88 determines that the first motor 11 is to be driven (S31: YES), it drives the first motor 11 in accordance with the content of the drive signal input to the input section 84, as in step S12 of the first partial drive processing (step S32). When the control section 88 determines that the first motor 11 is not to be driven (S31: NO), it drives the second motor 12 in accordance with the content of the drive signal input to the input section 84, as in step S22 of the second partial drive processing (step S33).

[0191] After executing one of steps S32 and S33, the control section 88 determines whether a drive signal has been input to the input section 84 (step S34). When the control section 88 determines that no drive signal has been input (S34: NO), it determines whether a stop signal has been input to the input section 84 (step S35). When the control section 88 determines that no stop signal has been input (S35: NO), it executes step S34 again and waits until a drive signal or a stop signal is input to the input section 84.

[0192] When the control section 88 determines that a drive signal has been input (S34: YES), it instructs the output section 80 to switch all the input switches to OFF (step S36). As a result, the supply of current to the first motor 11 and the second motor 12 is stopped, and the first motor 11 and the second motor 12 stop operating.

[0193] After executing step S36, the control section 88 instructs the output section 80 to switch all the output switches to ON (step S37). When all the output switches are ON, the coil of the first motor 11 or the second motor 12 outputs current, discharging energy, because both ends of the third intermediate switch Ml are short-circuited.

[0194] After executing step S37, the control section 88 executes step S31 again, determines whether the first motor 11 is to be driven in accordance with the content of a new drive signal input to the input section 84. Thereafter, the first motor 11 or the second motor 12 is driven in accordance with the content of the newly input drive signal.

[0195] When the control section 88 determines that a stop signal has been input (S35: YES), it instructs the output section 80 to switch all the input switches to OFF, as in step S36 (step S38). As a result, the first motor 11 and the second motor 12 stop operating. After executing step S38, the control section 88 instructs the output section 80 to switch all the output switches to ON, as in step S37 (step S39). As a result, the coil of the first motor 11 or the second motor 12 discharges energy.

[0196] The control section 88 instructs the output section 80 to switch all the switches possessed by the switching circuit 20 to be off after the step S39 is executed (step S40), and ends the third partial driving process. In the case where the step S39 is executed, the switches possessed by the switching circuit 20 other than the short-circuit switch are switched to be off.

[0197] As described above, in the case where both ends of the third intermediate switch Ml are short-circuited, the control section 88 does not drive the second motor 12 in the case where the first motor 11 is driven. The control section 88 drives the second motor 12 in the case where the first motor 11 is not driven. The control section 88 gives priority to the driving of the first motor 11.

[0198] <Effects and Modification of the Driving Device 10>

[0199] In the case where the one end and the other end of the first motor 11 are connected to the connection nodes between the normal 2 switches, respectively, the driving device 10 can rotate the first motor 11 in the forward direction and in the reverse direction. Similarly, in the case where the one end and the other end of the second motor 12 are connected to the connection nodes between the normal 2 switches, respectively, the driving device 10 can rotate the second motor 12 in the forward direction and in the reverse direction. Even in the case where both ends of one of the 3 switches possessed by the third connection circuit Cl are short-circuited, the one end of the first motor 11 or the second motor 12 is connected to the connection node between the remaining 2 switches possessed by the third connection circuit Cl. Therefore, even in the case where both ends of one of the 3 switches possessed by the third connection circuit Cl are short-circuited, the first motor 11 or the second motor 12 can be rotated in the forward direction and in the reverse direction.

[0200] The control section 88 can also detect a failure or an abnormality of the switching circuit 20 on the basis of the current flowing through the first input switch 60, the second input switch 70, and the third input switch Kl during the driving of the first motor 11 or the second motor 12.

[0201] (Embodiment 2)

[0202] In Embodiment 1, in the case where both ends of the third intermediate switch Ml are short-circuited, the control section 88 gives priority to the driving of the first motor 11. However, the motor to which priority is given is not limited to the first motor 11.

[0203] Hereinafter, with respect to Embodiment 2, the points different from Embodiment 1 will be described. The structures other than the structure described later are common to Embodiment 1. Therefore, the same reference numerals as those of Embodiment 1 are added to the structure sections common to Embodiment 1, and the description thereof is omitted.

[0204] <Third Partial Driving Process>

[0205] Figure 11is a flowchart showing the order of the third partial drive processing in Embodiment 2. The control section 88 executes the third partial drive processing when the drive signal is input to the input section 84 in the case where the motor is the first motor 11 or the second motor 12, that is, in the case where the short circuit of the third intermediate switch Ml is detected. Most of the third partial drive processing in Embodiment 2 is the same as the third partial drive processing in Embodiment 1. Therefore, the detailed description of the parts common to the third partial drive processing, that is, steps S32 to S40 is omitted in the third partial drive processing in Embodiment 2.

[0206] In the third partial drive processing, the control section 88 first determines whether or not to drive the second motor 12 based on the drive signal input to the input section 84 as in step S21 of the second partial drive processing (step S51). The control section 88 executes step S32 in the case where it is determined not to drive the second motor 12 (S51: No). The control section 88 executes step S33 in the case where it is determined to drive the second motor 12 (S51: Yes). The control section 88 executes step S51 again after step S37 is executed, and determines whether or not to drive the second motor 12 in accordance with the content of the drive signal newly input to the input section 84. Thereafter, the first motor 11 or the second motor 12 is driven in accordance with the content of the drive signal newly input.

[0207] As described above, in the case where the both ends of the third intermediate switch Ml are short-circuited, the control section 88 does not drive the first motor 11 in the case where the second motor 12 is driven. The control section 88 drives the first motor 11 in the case where the second motor 12 is not driven. The control section 88 gives priority to the drive of the second motor 12.

[0208] <Effects of the Drive Device 10>

[0209] The drive device 10 in Embodiment 2 also functions to exert effects other than the effect obtained by giving priority to the drive of the first motor 11 in the third partial drive processing among the effects of the drive device 10 in Embodiment 1.

[0210] (Embodiment 3)

[0211] In Embodiment 1, the number of motors driven by the drive device 10 is two. However, the number of motors driven by the drive device 10 can be three or more.

[0212] Hereinafter, the difference from Embodiment 1 will be described with respect to Embodiment 3. The structures other than the structure described later are common to Embodiment 1. Therefore, the same reference numerals are added to the structure sections common to Embodiment 1, and the detailed description thereof is omitted.

[0213] <Structure of the Switching Circuit 20>

[0214] Figure 12 is a circuit diagram for explaining the structure of the switching circuit 20 in Embodiment 3. The power supply system 1 in Embodiment 3 is provided with the driving device 10, the first motor 11, the second motor 12, the third motor 13, and the direct-current power supply U. The driving device 10 in Embodiment 3 drives the first motor 11, the second motor 12, and the third motor 13. The switching circuit 20 in Embodiment 3 is connected to one end and the other end of the third motor 13 in addition to the first motor 11 and the second motor 12. The third motor 13 is configured similarly to the first motor 11 or the second motor 12. In a case where current in the right direction of the first direction (the direction of the arrow of the drawing) flows through the third motor 13, the third motor 13 rotates in the forward direction similarly to the first motor 11 or the second motor 12. In a case where current in the left direction of the second direction (the direction opposite to the direction of the arrow of the drawing) flows through the third motor 13, the third motor 13 rotates in the reverse direction similarly to the first motor 11 or the second motor 12. In a case where the supply of current to the third motor 13 is stopped, the third motor 13 stops rotating. The forward direction can be either one of the clockwise direction and the counterclockwise direction. Figure 12 Figure 12

[0215] The switching circuit 20 in Embodiment 3 has all the structural parts that the switching circuit 20 in Embodiment 1 has. The switching circuit 20 in Embodiment 3 further has a third connection circuit C2. Between the input terminal 20a and the output terminal 20b, the first connection circuit A, the second connection circuit B, the third connection circuit C1, and the third connection circuit C2 are connected respectively.

[0216] The third connection circuit C2 has a third input switch K2, a third intermediate switch M2, and a third output switch N2. They are FETs of the N-channel type. In the third connection circuit C2, the third input switch K2, the third intermediate switch M2, and the third output switch N2 are connected in series. Specifically, the source of the third input switch K2 is connected to the drain of the third intermediate switch M2. The source of the third intermediate switch M2 is connected to the drain of the third output switch N2.

[0217] The drain of the third input switch K2 is connected to the input terminal 20a. The source of the third output switch N2 is connected to the output terminal 20b. The first motor 11 is connected similarly to Embodiment 1. The second motor 12 is connected between the connection node of the second connection circuit B and the connection node between the third input switch K2 and the third intermediate switch M2. The third motor 13 is connected between the connection node between the third input switch K1 and the third intermediate switch M1 and the connection node between the third intermediate switch M2 and the third output switch N2.

[0218] ​​The third input switch K2, the third intermediate switch M2, and the third output switch N2 function in the same manner as the first input switch 60. The reference voltages of the first input switch 60, the first output switch 61, the second input switch 70, the second output switch 71, the third input switch K1, K2, the third intermediate switch M1, M2, and the third output switch N1, N2 can be different from the reference voltages of the other switches.

[0219] The switching circuit 20 in Embodiment 3 further has 3 drive circuits connected to the gates of the third input switch K2, the third intermediate switch M2, and the third output switch N2, and a current detection circuit that detects the current flowing through the third input switch K2. In Figure 12 In Embodiment 3, the drive circuits and the current detection circuit are omitted from the drawing.

[0220] The 3 drive circuits are connected to the output section 80 of the microcomputer 21 in the same manner as the drive circuits D, E, F. The drive circuit connected to the third input switch K2 is connected to the current detection circuit that detects the current flowing through the third input switch K2. The connection node between the drive circuit and the current detection circuit is connected to the input section 85 of the microcomputer 21. The current detection circuit outputs analog current information representing the detected current to the drive circuit connected to the third input switch K2 and the input section 85 of the microcomputer 21 in the same manner as the current detection circuit G. The 3 drive circuits switch the third input switch K2, the third intermediate switch M2, and the third output switch N2 to be on or off in the same manner as the drive circuits D, E, F, respectively.

[0221] The current detection circuit that detects the current flowing through the third input switch K2 outputs analog current information to the input section 85. The input section 85, in the case where analog current information is input from the current detection circuit, outputs the input analog current information to the A / D conversion section 81. The A / D conversion section 81 converts the analog current information input from the input section 85 into digital current information. The control section 88 acquires the digital current information obtained by the conversion of the A / D conversion section 81. In the case where the control section 88 acquires the current information output from the current detection circuit from the A / D conversion section 81, the current represented by the acquired current information substantially coincides with the current detected at the time of acquisition.

[0222] The resistance values of the first resistor 31 and the second resistor 32 are each sufficiently larger than the resistance component value of the third motor 13. In addition, the control section 88 instructs the output section 80 to switch the on or off of the switches of the switching circuit 20, respectively, in the same manner as in Embodiment 1. The output section 80 switches the voltage output to the three drive circuits connected to the third input switch K2, the third intermediate switch M2, and the third output switch N2, respectively, to the high-level voltage or the low-level voltage in accordance with the instruction of the control section 88. The three drive circuits switch the third input switch K2, the third intermediate switch M2, and the third output switch N2 to the on or off based on the input voltage, respectively.

[0223] <Short circuit detection processing>

[0224] Figure 13 is a chart showing the order of the short circuit detection processing. The control section 88 executes the short circuit detection processing in the case where the first motor 11, the second motor 12, and the third motor 13 are stopped from operating, in the same manner as in Embodiment 1.

[0225] The control section 88 first executes order 1. In order 1, the control section 88 instructs the output section 80 to switch the on or off of all the switches of the switching circuit 20 to the off, and, in the state where the circuit switch 30 is off, acquires voltage information indicating the node voltage of the resistance connection node. The control section 88 detects the short circuit of the first input switch 60 in the case where the node voltage indicated by the acquired voltage information is equal to or higher than the voltage threshold value. The control section 88 prohibits the drive of the first motor 11 and the third motor 13 in the case where the short circuit of the first input switch 60 is detected, and ends the short circuit detection processing.

[0226] The control section 88 executes order 2 in the case where the short circuit of the first input switch 60 is not detected. In order 2, the control section 88 instructs the output section 80 to switch the on or off of all the switches of the switching circuit 20 to the off, and, in the state where the circuit switch 30 is on, acquires voltage information. The control section 88 detects the short circuit of the first output switch 61 or the third output switch N1 in the case where the node voltage indicated by the acquired voltage information is lower than the voltage threshold value. The control section 88 prohibits the drive of the first motor 11 in the case where the short circuit of the first output switch 61 or the third output switch N1 is detected, and ends the short circuit detection processing.

[0227] The control section 88 executes order 3 in a case where a short circuit of the first output switch 61 or the third output switch Nl is not detected. In order 3, the control section 88 instructs the output section 80 to perform switching of only the third intermediate switch Ml to ON among the switches possessed by the switch circuit 20, and acquires voltage information from the A / D conversion section 82 in a state where the circuit switch 30 is off. The control section 88 detects a short circuit of the third input switch Kl in a case where the node voltage indicated by the acquired voltage information is equal to or higher than the voltage threshold value. The control section 88 prohibits driving of the second motor 12 and the third motor 13 in a case where a short circuit of the third input switch Kl is detected, and ends the short circuit detection processing.

[0228] The control section 88 executes order 4 in a case where a short circuit of the third input switch Kl is not detected. In order 4, the control section 88 instructs the output section 80 to perform switching of only the third intermediate switch Ml to ON among the switches possessed by the switch circuit 20, and acquires voltage information from the A / D conversion section 82 in a state where the circuit switch 30 is on. The control section 88 detects a short circuit of the third output switch N2 in a case where the node voltage indicated by the acquired voltage information is lower than the voltage threshold value. The control section 88 prohibits driving of the third motor 13 in a case where a short circuit of the third output switch N2 is detected, and ends the short circuit detection processing.

[0229] The control section 88 executes order 5 in a case where a short circuit of the third output switch N2 is not detected. In order 5, the control section 88 instructs the output section 80 to perform switching of only the third input switch Kl to ON, and acquires voltage information from the A / D conversion section 82 in a state where the circuit switch 30 is off. The control section 88 detects a short circuit of the third intermediate switch Ml in a case where the node voltage indicated by the acquired voltage information is equal to or higher than the voltage threshold value, and prohibits driving of the first motor 11 or the third motor 13.

[0230] Further, in order 5, the control section 88 can instead of instructing the output section 80 to perform switching of only the third input switch Kl to ON, instruct the output section 80 to perform switching of only the third input switch K2 to ON, or instruct the output section 80 to perform switching of both the third input switches Kl, K2 to ON.

[0231] The control section 88 executes order 6 in a case where a short circuit of the third input switch K2 is not detected. In order 6, the control section 88 instructs the output section 80 to perform switching of only the third input switch K2 to ON among the switches possessed by the switching circuit 20, and to acquire voltage information from the A / D conversion section 82 in a state where the circuit switch 30 is OFF. The control section 88 detects a short circuit of the second input switch 70 in a case where the node voltage indicated by the acquired voltage information is equal to or higher than the voltage threshold value. The control section 88 prohibits driving of the second motor 12 in a case where a short circuit of the second input switch 70 is detected, and ends the short circuit detection processing.

[0232] The control section 88 executes order 7 in a case where a short circuit of the second input switch 70 or the third input switch K2 is not detected. In order 7, the control section 88 instructs the output section 80 to perform switching of only the third input switch K2 to ON among the switches possessed by the switching circuit 20, and to acquire voltage information from the A / D conversion section 82 in a state where the circuit switch 30 is ON. The control section 88 detects a short circuit of the second output switch 71 in a case where the node voltage indicated by the acquired voltage information is lower than the voltage threshold value. The control section 88 prohibits driving of the second motor 12 in a case where a short circuit of the second output switch 71 is detected, and ends the short circuit detection processing.

[0233] The control section 88 executes order 8 in a case where a short circuit of the second output switch 71 is not detected. In order 8, the control section 88 instructs the output section 80 to perform switching of only the third input switch K2 to ON, and to acquire voltage information from the A / D conversion section 82 in a state where the circuit switch 30 is OFF. The control section 88 detects a short circuit of the third input switch K2 in a case where the node voltage indicated by the acquired voltage information is equal to or higher than the voltage threshold value, and prohibits driving of the second motor 12 or the third motor 13.

[0234] Further, in order 8, the control section 88 can instead instruct the output section 80 to perform switching of the second input switch 70 to ON, or to perform switching of both the second input switch 70 and the third input switch K2 to ON, instead of instructing the output section 80 to perform switching of the third input switch K2 to ON.

[0235] <Drive Processing>

[0236] In Embodiment 3, the control section 88 also performs various drive processes by executing the computer program P. In these drive processes, as in Embodiment 1 or Embodiment 2, the control section 88 does not drive the prohibited motor, and drives at least one of the first motor 11, the second motor 12, and the third motor 13 in a manner to satisfy the content indicated by the drive signal as much as possible. In the case where the prohibited motor is the first motor 11 or the third motor 13, or in the case where the prohibited motor is the second motor 12 or the third motor 13, the drive of the motor on one side is given priority, as in the third partial drive process of Embodiment 1 or Embodiment 2.

[0237] The duty ratio of the PWM control in the case where the first motor 11, the second motor 12, and the third motor 13 are caused to rotate in the reverse direction is set to a value larger than the duty ratio of the PWM control in the case where only the first motor 11, only the second motor 12, or only the third motor 13 is caused to rotate.

[0238] <Effects of the Drive Device 10>

[0239] Even in the case where both ends of one of the six switches possessed by the third connection circuit C1, C2 are short-circuited, one end of the first motor 11 or the second motor 12 is connected to the connection node between the normal two switches. Therefore, even in the case where both ends of one of the six switches possessed by the third connection circuit C1, C2 are short-circuited, the first motor 11 or the second motor 12 can be caused to rotate in the forward direction and the reverse direction. The drive device 10 in Embodiment 3 likewise functions as the drive device 10 in Embodiment 1 or Embodiment 2.

[0240] (Embodiment 4)

[0241] In Embodiment 3, the number of motors driven by the drive device 10 is three. However, the number of motors driven by the drive device 10 can also be four or more.

[0242] Hereinafter, regarding Embodiment 4, the points of difference from Embodiment 3 will be described. The structures other than the structure described later are common to Embodiment 3. Therefore, the same reference numerals are added to the structure sections common to Embodiment 3, and the description thereof will be omitted.

[0243] <Structure of the Switching Circuit 20>

[0244] Figure 14is a circuit diagram for explaining the structure of the switching circuit 20 in Embodiment 4. The power supply system 1 in Embodiment 4 is provided with the driving device 10, the first motor 11, the second motor 12, a plurality of third motors 13, and the direct-current power supply U. The driving device 10 in Embodiment 4 drives the plurality of third motors 13 in addition to the first motor 11 and the second motor 12. The switching circuit 20 in Embodiment 3 is connected to one end and the other end of each of the plurality of third motors 13 in addition to the first motor 11 and the second motor 12.

[0245] The switching circuit 20 has the first connection circuit A, the second connection circuit B, and a plurality of third connection circuits C1, C2,..., Ci (i: an integer of 2 or more). In the third connection circuit Cj (j = 1, 2,..., i), the third input switch Kj, the third intermediate switch Mj, and the third output switch Nj are connected in series. The third input switch Kj, the third intermediate switch Mj, and the third output switch Nj are each an N-channel type FET. The first motor 11 is connected between the first connection circuit A and the third connection circuit C1 as in Embodiment 3. The second motor 12 is connected between the second connection node of the second connection circuit B and the connection node between the third input switch Ki and the third intermediate switch Mi.

[0246] The third motor 13 is connected between the third connection circuits Cx, Cx+1 (x = 1, 2,..., i-1) as in Embodiment 3. Therefore, in each of the plurality of third connection circuits Cj, the number of motors connected to the connection node between the third input switch Kj and the third intermediate switch Mj is one, and the number of motors connected to the connection node between the third intermediate switch Mj and the third output switch Nj is also one. Each switch of the switching circuit 20 is switched to be on or off by the driving circuit as in Embodiment 3. The microcomputer 21 switches each of all the switches of the switching circuit 20 to be on or off as in Embodiment 3.

[0247] <Short-circuit detection processing>

[0248] Even if the driving device 10 is configured as described above, the control section 88 of the microcomputer 21 can detect short-circuit of all the switches of the switching circuit 20 by sequentially switching the third intermediate switches of the third connection circuits C1, C2,..., Ci to be on as in Embodiment 3.

[0249] <Driving processing>

[0250] In Embodiment 4, the control section 88 also performs various drive processes by executing the computer program P. In these drive processes, as in Embodiment 3, the control section 88 does not drive the prohibition motor, and drives at least one of the first motor 11, the second motor 12, and the plurality of third motors 13 in a manner to satisfy the content indicated by the drive signal as much as possible. In the case where the prohibition motor is one of the two motors, for example, the first motor 11 or the third motor 13, as in the third partial drive process of Embodiment 1 or Embodiment 2, the drive of the motor on one side is given priority.

[0251] The duty ratio of the PWM control in the case where the first motor 11, the second motor 12, and all of the third motors 13 are caused to rotate in the reverse direction is set to a value larger than the duty ratio of the PWM control in the case where only the first motor 11, only the second motor 12, or only one third motor 13 is caused to rotate.

[0252] <Effects of the Drive Device 10>

[0253] Even in the case where both ends of one of the switches possessed by the third connection circuit Cl, C2,..., Ci are short-circuited, one end of the first motor 11 or the second motor 12 is connected to the connection node between the normal two switches. Therefore, even in the case where both ends of one of the switches possessed by the third connection circuit Cl, C2,..., Ci are short-circuited, the first motor 11 or the second motor 12 can be caused to rotate in the forward direction and the reverse direction. The drive device 10 in Embodiment 4 likewise functions as the drive device 10 in Embodiment 3.

[0254] (Embodiment 5)

[0255] In Embodiment 1, in the series circuit 22, the resistance connection node is located on the downstream side of the circuit switch 30. However, the resistance connection node can also be on the upstream side of the circuit switch 30.

[0256] Hereinafter, regarding Embodiment 5, the points of difference from Embodiment 1 will be described. The structures other than the structure described later are common to Embodiment 1. Therefore, the same reference numerals as in Embodiment 1 are added to the structure sections common to Embodiment 1, and the description thereof will be omitted.

[0257] <Structure of the Series Circuit 22>

[0258] Figure 15 is a circuit diagram of the series circuit 22 in Embodiment 5. As Figure 15 indicated, a constant voltage Vc is applied to one end of the first resistance 31. The other end of the first resistance 31 is connected to one end of the second resistance 32. The other end of the second resistance 32 is connected to one end of the circuit switch 30, and the other end of the circuit switch 30 is grounded.

[0259] When the circuit switch 30 is on, the current flows through the first resistor 31, the second resistor 32, and the circuit switch 30 in this order when all the switches of the switching circuit 20 are off. The resistance connection node between the first resistor 31 and the second resistor 32 is located on the upstream side of the circuit switch 30.

[0260] Further, the circuit switch 30 can also be connected between the first resistor 31 and the second resistor 32. In this case, the resistance connection node is the connection node between the circuit switch 30 and the first resistor 31.

[0261] <Short-circuit detection processing>

[0262] Figure 16 is a chart showing the order of the short-circuit detection processing. The control section 88 of the microcomputer 21 performs the short-circuit detection processing similarly to Embodiment 1. In Embodiment 5, the voltage threshold value exceeds the divided voltage obtained by dividing the constant voltage Vc by the first resistor 31 and the second resistor 32, and is below the constant voltage Vc. As described in the explanation of Embodiment 1, the constant voltage Vc is lower than the power supply voltage of the direct-current power supply U.

[0263] In the case of comparing the short-circuit detection processing in Embodiment 5 with the short-circuit detection processing in Embodiment 1 shown in Figure 6 The timing at which the circuit switch 30 is switched on or off is different. In Embodiment 5, the control section 88 instructs the switching section 83 to switch the circuit switch 30 on in the order 1, 3, 5, and to switch the circuit switch 30 off in the order 2, 4.

[0264] In the case where all the switches of the switching circuit 20 are off and the circuit switch 30 is on, the node voltage is the divided voltage, which is lower than the voltage threshold value. Here, in the case where the both ends of the first input switch 60 are short-circuited, the node voltage is substantially identical to the power supply voltage, which is above the voltage threshold value. Therefore, in the order 1, the control section 88 detects the short-circuit of the first input switch 60 in the case where the node voltage is above the voltage threshold value. In the order 3, 5, the control section 88 detects the short-circuit similarly to the order 1.

[0265] In the case where all the switches of the switching circuit 20 are off and the circuit switch 30 is off, the node voltage is the constant voltage Vc, which is above the voltage threshold value. Here, in the case where the both ends of the first input switch 60 or the third output switch N1 are short-circuited, the node voltage is substantially identical to zero V, which is lower than the voltage threshold value. Therefore, in the order 2, the control section 88 detects the short-circuit of the first input switch 60 or the third output switch N1 in the case where the node voltage is below the voltage threshold value. In the order 4, the control section 88 detects the short-circuit similarly to the order 2.

[0266] <Effects and supplementary explanation of the drive device 10>

[0267] The drive device 10 in Embodiment 5 similarly functions as the drive device 10 in Embodiment 1.

[0268] In Embodiment 5, the control section 88 can also execute the third partial drive processing similarly to Embodiment 2. The series circuit 22 in Embodiments 3 and 4 can also be configured similarly to the series circuit 22 in Embodiment 5. The short-circuit detection processing in Embodiments 3 and 4 is executed similarly to Embodiment 5.

[0269] <Modification Example>

[0270] In Embodiments 1 to 5, in a case where the resistance component value of the first motor 11, the second motor 12, or the third motor 13 is not sufficiently smaller than the resistance values of the first resistor 31 and the second resistor 32, a resistor having a small resistance value can be connected in parallel to the first motor 11, the second motor 12, or the third motor 13. Thereby, the control section 88 can appropriately execute the short-circuit detection processing.

[0271] In Embodiments 1 to 5, the method of detecting a short circuit is not limited to the method based on the node voltage, and can be, for example, a method based on a current. In each order of the short-circuit detection processing, a failure of a switch through which a current flows is detected in a case where the current flows through the switch indicating a disconnection switch. In this configuration, the current flowing through all the output switches needs to be detected respectively. In addition, the switches of the switching circuit 20 are not limited to the N-channel type FET, and can be, for example, a P-channel type FET, a bipolar transistor, or a relay contact.

[0272] It should be understood that the disclosed Embodiments 1 to 5 are exemplary in all aspects and are not limiting. The scope of the present application is not represented by the above description but by the claims, and is intended to include all modifications within the meaning and range equivalent to the claims.

[0273] Explanation of Reference Numerals

[0274] 1 power supply system

[0275] 10 drive device

[0276] 11 first motor

[0277] 12 second motor

[0278] 13 third motor

[0279] 20 switching circuit

[0280] 20a input terminal

[0281] 20b output terminal

[0282] 21 microcomputer

[0283] 22 series circuit

[0284] 23 voltage detection circuit

[0285] 30 circuit switch

[0286] 31 first resistor

[0287] 32 second resistor

[0288] 40, 41, 50, 51, D, E, F drive circuit

[0289] 42, 52, G current detection circuit

[0290] 60 first input switch (first switch)

[0291] 61 first output switch (first switch)

[0292] 70 second input switch (second switch)

[0293] 71 second output switch (second switch)

[0294] 80 output section

[0295] 81, 82 A / D conversion section

[0296] 83 switching section

[0297] 84, 85, 86 input section

[0298] 87 storage section

[0299] 88 control section (processing section)

[0300] 89 internal bus

[0301] A first connection circuit

[0302] B second connection circuit

[0303] C1, C2,..., Ci third connection circuit

[0304] H storage medium

[0305] K1, K2 third input switch (third switch)

[0306] M1, M2 third intermediate switch (third switch)

[0307] N1, N2 third output switch (third switch)

[0308] P computer program

[0309] U DC power supply.

Claims

1. A driving device for driving a first motor and a second motor whose rotational direction differs depending on the direction of the current flowing through them. The driving device includes a first connection circuit, a second connection circuit, and a third connection circuit respectively connected between the input terminal of the input current and the output terminal of the output current. In the first connection circuit, two first switches are connected in series. In the second connection circuit, two second switches are connected in series. In the third connection circuit, three third switches are connected in series. The first motor is connected between the first connection node between the two first switches and the connection node between the two third switches on the output side. The second motor is connected between the second connection node between the two second switches and the connection node between the two third switches on the input side.

2. The driving device according to claim 1, comprising: In a series circuit, a first resistor, a second resistor, and a circuit switch are connected in series. The resistor connection node between the first and second resistors is connected to the first connection node and is subject to a constant voltage. Processing Department, Execute Processing The processing unit performs the following processing: Switch the circuit switch to on or off. Obtain voltage information representing the node voltage of the resistor connection node. Based on the obtained voltage information, a short circuit is detected in one of the two first switches, the two second switches, and the three third switches.

3. The driving device according to claim 2, wherein, The resistor connection node is the downstream connection node of the circuit switch. The processing unit performs the following processing: The circuit instructs the two first switches, the two second switches, and the three third switches to switch to open mode, and obtains the voltage information when the circuit switches are open. Based on the obtained voltage information, a short circuit in the first switch on the input side is detected.

4. The driving device according to claim 2, wherein, The resistor connection node is the downstream connection node of the circuit switch. The processing unit performs the following processing: The system instructs the two first switches, the two second switches, and the three third switches to switch to the open position, and obtains the voltage information when the circuit switches are on. Based on the obtained voltage information, a short circuit is detected in the first switch on the output side or the third switch on the output side.

5. The driving device according to claim 2, wherein, The resistor connection node is the downstream connection node of the circuit switch. The processing unit performs the following processing: The circuit indicates that the two first switches, the two second switches, the third switch on the input side, and the third switch on the output side are switched to open; it also indicates that the third switch connected between the third switch on the input side and the third switch on the output side is switched to open; and it acquires the voltage information when the circuit switches are open. Based on the obtained voltage information, a short circuit is detected in the second switch or the third switch on the input side.

6. The driving device according to claim 2, wherein, The resistor connection node is the downstream connection node of the circuit switch. The processing unit performs the following processing: The circuit indicates that the two first switches, the two second switches, the third switch on the input side, and the third switch on the output side are switched to open; it also indicates that the third switch connected between the third switch on the input side and the third switch on the output side is switched to open; and it acquires the voltage information when the circuit switches are closed. Based on the obtained voltage information, a short circuit in the second switch on the output side is detected.

7. The driving device according to claim 2, wherein, The resistor connection node is the downstream connection node of the circuit switch. The processing unit performs the following processing: The circuit indicates whether one or both of the second and third switches on the input side are to be switched on, and indicates whether the remaining switches among the two first switches, the two second switches, and the three third switches are to be switched off. Furthermore, the circuit obtains the voltage information when the circuit switches are off. Based on the obtained voltage information, a short circuit is detected between the third switch connected to the input terminal and the third switch connected to the output terminal.

8. The driving device according to claim 4, wherein, The processing unit performs the following processing: when a short circuit is detected in the first switch or the third switch on the output side, it drives only the second motor by instructing the two second switches and the three third switches to switch on or off respectively.

9. The driving device according to claim 5, wherein, The processing unit performs the following processing: when a short circuit is detected in the second switch on the input terminal side, it drives only the first motor by instructing the two first switches and the three third switches to switch on or off respectively; when a short circuit is detected in the third switch on the input terminal side, it drives only the first motor by instructing the remaining switches among the two first switches and the three third switches to switch on or off respectively.

10. The driving device according to claim 6, wherein, The processing unit performs the following processing: when a short circuit is detected in the second switch on the output side, it drives only the first motor by instructing the two first switches and the three third switches to switch on or off respectively.

11. The driving device according to claim 7, wherein, The processing unit performs the following processing: If a short circuit is detected between the third switch connected to the input terminal and the third switch connected to the output terminal, it is determined whether to drive the first motor. If it is determined that the first motor will not be driven, the second motor will be driven.

12. The driving device according to claim 7, wherein, The processing unit performs the following processing: If a short circuit is detected between the third switch connected to the input terminal and the third switch connected to the output terminal, it is determined whether to drive the second motor. If it is determined that the second motor will not be driven, the first motor will be driven.

13. The driving device according to claim 1, wherein, The number of the third connection circuits is two or more. The first motor is connected between the connection node between the two first switches and the output-side connection node between the two third switches on the output side of one of the plurality of third connection circuits. The second motor is connected to the connection node between the two second switches and the input-side connection node between the two third switches on the input side of the plurality of third connection circuits, which are different from the third connection circuit connected to the first motor. The third motor, whose rotation direction varies depending on the direction of the current flowing through it, is connected between the input-side connection node of one of the two third connection circuits and the output-side connection node of the other of the two third connection circuits. The number of motors connected to the input-side connection nodes and output-side connection nodes of each third connection circuit is 1.

14. A short-circuit detection method that causes a computer to perform the following steps: The circuit switch of the drive device is switched to be on or off. The drive device has two first switches, two second switches, three third switches, and a series circuit that connects the first resistor, the second resistor, and the circuit switch in series and applies a constant voltage. The drive device drives a first motor and a second motor whose rotation direction is different depending on the direction of the current flowing through them. Obtain voltage information representing the node voltage at the resistor connection node between the first resistor and the second resistor; and Based on the obtained voltage information, a short circuit is detected in one of the two first switches, the two second switches, and the three third switches. The driving device also includes a first connection circuit, a second connection circuit, and a third connection circuit respectively connected between the input terminal of the input current and the output terminal of the output current. In the first connection circuit, the two first switches are connected in series. In the second connection circuit, the two second switches are connected in series. In the third connection circuit, the three third switches are connected in series. The first motor is connected between the first connection node between the two first switches and the connection node between the two third switches on the output side. The second motor is connected between the second connection node between the two second switches and the connection node between the two third switches on the input side. The resistor connection node is connected to the first connection node.

15. A computer program product comprising a computer program for causing a computer to perform the following steps: The circuit switch of the drive device is switched to be on or off. The drive device has two first switches, two second switches, three third switches, and a series circuit that connects the first resistor, the second resistor, and the circuit switch in series and applies a constant voltage. The drive device drives a first motor and a second motor whose rotation direction is different depending on the direction of the current flowing through them. Obtain voltage information representing the node voltage at the resistor connection node between the first resistor and the second resistor; and Based on the obtained voltage information, a short circuit is detected in one of the two first switches, the two second switches, and the three third switches. The driving device also includes a first connection circuit, a second connection circuit, and a third connection circuit respectively connected between the input terminal of the input current and the output terminal of the output current. In the first connection circuit, the two first switches are connected in series. In the second connection circuit, the two second switches are connected in series. In the third connection circuit, the three third switches are connected in series. The first motor is connected between the first connection node between the two first switches and the connection node between the two third switches on the output side. The second motor is connected between the second connection node between the two second switches and the connection node between the two third switches on the input side. The resistor connection node is connected to the first connection node.

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