control device

Abstract

Proper overcurrent protection should be implemented for power lines 60a and 60b. [Solution] In step S110, the control circuit 30 continuously turns on semiconductor switches SW1 and SW4. In step S170, the control circuit 30 turns on semiconductor switches SW2 and SW3. The control circuit 30 calculates the temperature rise ΔTa resulting from the control process in step 110 based on the current Ia. The control circuit 30 calculates the temperature rise ΔTb resulting from the execution of the control process in step S170 based on the current Ib. The control circuit 30 calculates the temperature of wires 60a and 60b taking into account the temperature rise ΔTa and the temperature rise ΔTb. When the control circuit 30 determines that an overcurrent is flowing through wires 60a and 60b based on the temperature of wires 60a and 60b, it turns off semiconductor switches SW1 to SW4.

Description

[Technical Field]

[0001] This disclosure relates to a control device. [Background technology]

[0002] Conventionally, overcurrent protection circuits have been proposed that include a semiconductor switch positioned between the positive electrode and negative terminal of a power supply, and a control device (see, for example, Patent Document 1). The input terminal of the semiconductor switch is connected to the positive electrode. The output terminal of the semiconductor switch is connected to an electrical load. The electrical load is positioned between the output terminal of the semiconductor switch and the negative electrode.

[0003] When a semiconductor switch is turned on, a load current flows from the positive electrode of the power supply through the semiconductor switch and the electrical load to the negative electrode of the power supply. This allows power to be supplied from the power supply to the electrical load. Based on the load current flowing through the semiconductor switch, the control device determines whether or not an overcurrent is flowing through the wires connecting the semiconductor switch and the electrical load. If the control device determines that an overcurrent is flowing through the wires, it turns off the semiconductor switch. This performs overcurrent protection for each semiconductor switch, suppressing the flow of overcurrent through the wires and protecting them from overcurrent. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2013-85443 [Overview of the project] [Problems that the invention aims to solve]

[0005] The inventors, with reference to the above-described overcurrent protection circuit, investigated how to implement overcurrent protection for a wire connected to an electrical load in an H-bridge circuit consisting of a first semiconductor switch, a second semiconductor switch, a third semiconductor switch, and a fourth semiconductor switch. The first semiconductor switch is positioned between the positive electrode of the power supply and the second semiconductor switch. The second semiconductor switch is positioned between the first semiconductor switch and the negative electrode. The third semiconductor switch is positioned between the positive electrode of the power supply and the fourth semiconductor switch. The fourth semiconductor switch is positioned between the third semiconductor switch and the negative electrode.

[0006] Hereafter, the terminal to which the first semiconductor switch and the second semiconductor switch are commonly connected will be referred to as the first common connection terminal, and the terminal to which the third semiconductor switch and the fourth semiconductor switch are commonly connected will be referred to as the second common connection terminal. A DC motor is connected between the first common connection terminal and the second common connection terminal via a wire. When the control circuit turns off the second and third semiconductor switches and turns on the first and fourth semiconductor switches, a first current flows from the positive electrode of the power supply through the first semiconductor switch, the DC motor, and the fourth semiconductor switch to the negative electrode.

[0007] As a result, the DC motor rotates its output shaft in the forward direction based on the first current. On the other hand, when the control circuit turns off the first and fourth semiconductor switches and turns on the third and second semiconductor switches, a second current flows from the positive electrode of the power supply through the third semiconductor switch, the DC motor, and the second semiconductor switch to the negative electrode. As a result, the DC motor rotates its output shaft in the reverse direction based on the second current.

[0008] The control circuit calculates the temperature of the wire based on the first current when the DC motor is rotating in the forward direction. The control circuit determines whether or not an overcurrent is flowing through the wire by determining whether or not the wire temperature is above a threshold. When the control circuit determines that an overcurrent is flowing through the wire when the DC motor is rotating in the forward direction, it turns off the first semiconductor switch, the second semiconductor switch, the third semiconductor switch, and the fourth semiconductor switch. This prevents an overcurrent from flowing through the wire when the DC motor is rotating in the forward direction.

[0009] The control circuit calculates the temperature of the wire based on the second current when the DC motor is rotating in reverse. The control circuit determines whether or not an overcurrent is flowing through the wire by checking whether or not the wire temperature is above a threshold. When the control circuit determines that an overcurrent is flowing through the wire when the DC motor is rotating in reverse, it turns off the first semiconductor switch, the second semiconductor switch, the third semiconductor switch, and the fourth semiconductor switch. This prevents an overcurrent from flowing through the wire when the DC motor is rotating in reverse.

[0010] When a DC motor rotates forward, the wire generates heat based on the first current. When a DC motor rotates backward, the wire generates heat based on the second current. Therefore, for example, the control circuit calculates the wire temperature independently for forward rotation and backward rotation of the DC motor. As a result, the amount of heat generated from the wire during forward rotation and the amount of heat generated during backward rotation are not added together, and the control circuit calculates the wire temperature without adding them together. Consequently, the control circuit calculates a temperature lower than the actual temperature of the wire. Therefore, the control circuit cannot correctly calculate the temperature of the wire.

[0011] In view of the above points, this disclosure aims to provide a control device that correctly calculates the temperature of an electric wire. [Means for solving the problem]

[0012] According to one aspect of this disclosure, the control device is A first switch (SW1) is disposed between a high potential part (10) having a predetermined potential and a low potential part (11) having a potential lower than that of the high potential part. A second switch (SW2) is disposed between the first switch and the low potential part. A third switch (SW3) is disposed between the high potential part and the low potential part. A fourth switch (SW4) is disposed between the third switch and the low potential part. An H-bridge circuit (50) is provided. When a terminal to which the first switch and the second switch are commonly connected is defined as a first common connection terminal (40), and a terminal to which the third switch and the fourth switch are commonly connected is defined as a second common connection terminal (41), wires (60a, 60b) connected in series with an electrical load (2) are provided between the first common connection terminal and the second common connection terminal. The first control unit (S110) turns on the first switch and the fourth switch so that a first current flows from the high potential part through the first switch, the electrical load, and the fourth switch to the low potential part. The second control unit (S170) turns on the second switch and the third switch so that a second current flows from the high potential part through the third switch, the electrical load, and the second switch to the low potential part. The first rise width calculation unit (S130) calculates a first temperature rise width, which is the temperature rise width of the wire that has risen with the execution of the first control unit, based on the first current. The second rise width calculation unit (S130) calculates a second temperature rise width, which is the temperature rise width of the wire that has risen with the execution of the second control unit, based on the second current. It includes a wire temperature calculation unit (S130) that calculates the temperature of the wire taking into account the first temperature rise width and the second temperature rise width.

[0013] Therefore, according to one aspect of the present disclosure, the temperature of the wire can be correctly calculated. The reference numerals in parentheses attached to each component etc. show an example of the correspondence relationship between the component etc. and the specific components etc. described in the embodiments described later.

Brief Description of Drawings

[0014] [Figure 1]It is a block diagram showing an electrical circuit configuration of a vehicle motor control device in a first embodiment of the present disclosure. [Figure 2] It is a flowchart showing details of motor control processing executed by a control circuit in the first embodiment of FIG. 1. [Figure 3] It is an electrical circuit diagram showing an electrical circuit configuration of an H-bridge circuit of a vehicle motor control device in a second embodiment of the present disclosure. [Figure 4] It is an electrical circuit diagram showing a connection relationship of an H-bridge circuit, a current detection unit, a temperature detection unit, and a control circuit of a vehicle motor control device in the second embodiment of FIG. 3. Mode for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present disclosure will be described based on the drawings. In each of the following embodiments, parts that are the same or equivalent to each other are denoted by the same reference numerals in the drawings to simplify the description.

[0016] (First Embodiment) FIGS. 1 and 2 show a first embodiment of a vehicle motor control device 1 to which the control device of the present disclosure is applied. As shown in FIG. 1, the vehicle motor control device 1 of the present embodiment includes semiconductor switches SW1, SW2, SW3, SW4, current detection units 20a, 20b, temperature detection units 21a, and a control circuit 30. The semiconductor switch SW1 is a first switch disposed between the positive electrode 10 of the DC power supply and the semiconductor switch SW2. The positive electrode 10 is a high potential part having a predetermined positive potential in the DC power supply.

[0017] The negative electrode 11 is a low potential part having a potential lower than that of the positive electrode 10 in the DC power supply. The semiconductor switch SW2 is a second switch disposed between the semiconductor switch SW1 and the negative electrode 11. Further, the semiconductor switch SW3 is a third switch disposed between the positive electrode 10 and the semiconductor switch SW4. The semiconductor switch SW4 is a fourth switch disposed between the semiconductor switch SW3 and the negative electrode 11.

[0018] The input terminal of semiconductor switch SW1 is connected to the positive electrode 10. The output terminal of semiconductor switch SW1 is connected to the input terminal of semiconductor switch SW2. The output terminal of semiconductor switch SW2 is connected to the negative electrode 11. The input terminal of semiconductor switch SW3 is connected to the positive electrode 10. The output terminal of semiconductor switch SW3 is connected to the input terminal of semiconductor switch SW4. The output terminal of semiconductor switch SW4 is connected to the negative electrode 11.

[0019] The control terminals of the semiconductor switches SW1, SW2, SW3, and SW4 are each connected to the control circuit 30. As will be described later, the semiconductor switches SW1, SW2, SW3, and SW4 constitute an H-bridge circuit 50 for controlling the DC motor 2a. In this embodiment, various semiconductor elements such as metal-oxide-semiconductor field-effect transistors, insulated-gate bipolar transistors, and bipolar transistors can be used as the semiconductor switches SW1, SW2, SW3, and SW4.

[0020] For the sake of explanation, the terminal to which semiconductor switches SW1 and SW2 are commonly connected will be referred to as common connection terminal 40, and the terminal to which semiconductor switches SW3 and SW4 are commonly connected will be referred to as common connection terminal 41. Common connection terminals 40 and 41 are connected via input / output terminal 51, wire 60a, DC motor 2a, wire 60b, and input / output terminal 52. Input / output terminals 51 and 52 are input / output terminals provided on the vehicle motor control device 1, respectively. Input / output terminal 51 is located between common connection terminal 40 (i.e., the first common connection terminal) and the positive electrode of the DC motor 2a. Input / output terminal 52 is located between common connection terminal 41 (i.e., the second common connection terminal) and the negative electrode of the DC motor 2a. Wire 60a is a wire that connects input / output terminal 51 to the positive electrode of the DC motor 2a.

[0021] Furthermore, the electric wire 60b is an electric wire that connects the negative electrode of the DC motor 2a to the input / output terminal 52. For the electric wires 60a and 60b, for example, automotive electric wires such as AVSS and CIVUS can be used. The DC motor 2a is an electrical load that receives power from a DC power source and rotates its output shaft. The DC motor 2a can be used, for example, as a door lock motor that drives the door lock mechanism of an automobile, a wiper motor that drives the wipers of an automobile, or a washer motor that sprays washer fluid.

[0022] As will be described later, the current detection unit 20a is a detection element for detecting the current ia, which is the first current flowing through the wires 60a and 60b between the positive electrode 10 and the negative electrode 11, when the semiconductor switches SW1 and SW4 are turned ON. In this embodiment, the current detection unit 20a is, for example, a detection element (for example, a differential amplifier circuit) that amplifies and outputs the terminal voltage, which is the voltage between the input terminal and the output terminal of the semiconductor switch SW1. The terminal voltage is used to calculate the current flowing between the input terminal and the output terminal of the semiconductor switch SW1 as the current ia flowing through the wires 60a and 60b.

[0023] As will be described later, the current detection unit 20b is a detection element for detecting the current ib, which is the second current flowing through the wires 60a and 60b between the positive electrode 10 and the negative electrode 11, when the semiconductor switches SW2 and SW3 are turned ON. In this embodiment, the current detection unit 20b is, for example, a detection element (for example, a differential amplifier circuit) that amplifies and outputs the terminal voltage, which is the voltage between the input terminal and the output terminal of the semiconductor switch SW3.

[0024] The terminal voltage is used to calculate the current ib flowing through the wires 60a and 60b, which is the current flowing between the input and output terminals of the semiconductor switch SW3. The temperature detection unit 21a is a temperature detection unit for detecting the ambient temperature of the wires 60a and 60b. In this embodiment, various temperature detection units such as temperature detection diodes and thermistors can be used as the temperature detection unit 21a.

[0025] The control circuit 30 is a microcomputer equipped with a CPU, RAM, ROM, non-volatile rewritable memory, analog-to-digital converter, etc. Furthermore, when power is supplied from the power supply unit, the control circuit 30 executes a computer program recorded in the ROM or non-volatile rewritable memory, which are non-transitional physical recording media. In addition, the control circuit 30 performs various control processes, such as the motor control process shown in Figure 2, in conjunction with the execution of the computer program.

[0026] As described later, the motor control process controls the DC motor 2a while performing wire protection to prevent overcurrent from flowing through the wires 60a and 60b based on currents ia and ib. Figure 2 is a flowchart detailing the motor control process in the control circuit 30. The ROM and non-volatile rewritable memory store various constants for calculating the temperatures of the wires 60a and 60b along with the computer program. The analog-to-digital converter converts the output voltages of the current detection units 20a and 20b, and the output voltage of the temperature detection unit 21a, into digital data, respectively.

[0027] Next, the operation of the vehicle motor control device 1 of this embodiment will be described with reference to Figures 1 and 2.

[0028] First, the temperature detection unit 21a outputs an output voltage to the control circuit 30 that indicates the ambient temperature of the electric wires 60a and 60b. The current detection unit 20a outputs an output voltage to the control circuit 30 that indicates the terminal voltage of the semiconductor switch SW1. The current detection unit 20b outputs an output voltage to the control circuit 30 that indicates the terminal voltage of the semiconductor switch SW2. The analog-to-digital converter in the control circuit 30 repeatedly converts the output voltages of the current detection unit 20a, the current detection unit 20b, and the temperature detection unit 21a into digital data.

[0029] For the sake of explanation, the digital data representing the output voltage of the temperature detection unit 21a will be referred to as temperature data. The digital data representing the output voltage of the current detection unit 20a will be referred to as forward rotation voltage data. The digital data representing the output voltage of the current detection unit 20b will be referred to as reverse rotation voltage data. The temperature data is digital data representing the ambient temperature of the wires 60a and 60b. The forward rotation voltage data is digital data representing the terminal voltage of the semiconductor switch SW1 when the DC motor 2a is rotating in the forward direction. The reverse rotation voltage data is digital data representing the terminal voltage of the semiconductor switch SW3 when the DC motor 2a is rotating in the reverse direction.

[0030] Furthermore, the control circuit 30 starts executing the motor control process according to the flowchart in Figure 2. The motor control process is repeatedly executed by the control circuit 30. First, in step S100, the control circuit 30 determines whether or not it has received a forward rotation command from the electronic control unit to rotate the DC motor 2a in the forward direction. At this time, if the control circuit 30 determines that it has received a forward rotation command from the electronic control unit, it determines YES.

[0031] Accordingly, in step S110, the control circuit 30, as the first control unit, keeps semiconductor switches SW1 and SW4 ON while semiconductor switches SW2 and SW3 are OFF. As a result, current ia flows from the positive electrode 10 of the DC power supply to the negative electrode 11 through semiconductor switch SW1, input / output terminal 51, wire 60a, DC motor 2a, wire 60b, input / output terminal 52, and semiconductor switch SW4. Consequently, the DC motor 2a rotates its output shaft in the forward direction using the power supplied from the DC power supply.

[0032] At this time, the wires 60a and 60b generate heat based on the current ia. As a result, the temperature of the wires 60a and 60b rises above the initial temperature T0 of the wires 60a and 60b. Next, in step S120, the control circuit 30 calculates the current ia [A] by dividing the terminal voltage of the semiconductor switch SW1 by the on-resistance of the semiconductor switch SW1, based on the forward rotation voltage data. The current ia is used as the first current flowing through the conductors of the wires 60a and 60b when the DC motor 2a is rotating in the forward direction. The on-resistance is the resistance value between the input terminal and output terminal of the semiconductor switch SW1 when the semiconductor switch SW1 is turned on. The on-resistance is pre-recorded in ROM or non-volatile rewritable memory.

[0033] Next, in step S130, the control circuit 30, acting as a wire temperature calculation unit, calculates the temperature T1 of wires 60a and 60b based on the current ia and temperature data calculated in step S120. Temperature T1 is the temperature calculated in the temperature calculation process of step S130, which is executed for the first time after the motor control process has started. Hereinafter, the temperature of wires 60a and 60b will also be referred to as the wire temperature. Specifically, the control circuit 30, acting as a first rise amount calculation unit, calculates the temperature rise amount ΔTa by substituting the current ia, constants r, R, C, and time T into equation 1.

[0034]

number

[0035] Furthermore, constant C is the heat capacity of the conductors of wires 60a and 60b. The unit of heat capacity is [J / °C] or [W·sec / °C]. Time T is the period during which semiconductor switches SW1 and SW4 remain continuously ON while semiconductor switches SW2 and SW3 are OFF. In addition, constants r, R, and C are pre-recorded in ROM or non-volatile rewritable memory. Moreover, to accommodate temperature-dependent characteristic changes, the value of constant r may be corrected based on ambient temperature, etc., from the value recorded in ROM or non-volatile rewritable memory and used as constant r.

[0036] In addition to the above, in step S130, the control circuit 30 calculates the ambient temperature of the wires 60a and 60b based on the temperature data and sets this ambient temperature of the wires 60a and 60b as the initial temperature T0 of the wires 60a and 60b. Furthermore, as shown in equation 2, the control circuit 30 calculates the temperature T1 of the wires 60a and 60b by adding the temperature rise ΔTa and the initial temperature T0 of the wires 60a and 60b.

[0037]

number

[0038] At this point, in the next step S140, the control circuit 30 determines NO if the temperature T1 of the wires 60a and 60b is below the threshold, indicating that no overcurrent is flowing through the wires 60a and 60b. Subsequently, when the control circuit 30 receives a reverse command from the electronic control device to reverse the DC motor 2a, it determines NO in step S100 and YES in step S160. Accordingly, in step S170, the control circuit 30, as the second control unit, turns off semiconductor switches SW1 and SW4 and keeps semiconductor switches SW2 and SW3 on.

[0039] Therefore, a current ib flows from the positive electrode 10 of the DC power supply through the semiconductor switch SW3, input / output terminal 52, wire 60b, DC motor 2a, wire 60a, input / output terminal 51, and semiconductor switch SW2 to the negative electrode 11. Consequently, the DC motor 2a reverses its output shaft with the power supplied from the DC power supply. At this time, wires 60a and 60b generate heat based on the current ib. Therefore, the temperature of wires 60a and 60b rises above the temperature T1 of wires 60a and 60b.

[0040] Next, in step S180, the control circuit 30 calculates the current ib [A] by dividing the terminal voltage of the semiconductor switch SW3 by the on-resistance of the semiconductor switch SW3, based on the reverse voltage data. Here, the current ib is used as the second current flowing through the conductors of the wires 60a and 60b when the DC motor 2a is rotating in reverse. The on-resistance is the resistance value between the input terminal and output terminal of the semiconductor switch SW3 when it is turned on. The on-resistance is pre-recorded in ROM or non-volatile rewritable memory.

[0041] Next, in step S130, the control circuit 30 calculates the temperature T2 of the wires 60a and 60b based on the current ib calculated in step S180. The temperature T2 is the temperature calculated in the temperature calculation process of step S130, which is executed for the second time after the start of the motor control process. Specifically, the control circuit 30, as a second temperature rise calculation unit, calculates the temperature rise ΔTb (i.e., the second temperature rise) by substituting the current ib, constants r, R, C, and time T into equation 3.

[0042]

number

[0043]

number

[0044] Subsequently, when the control circuit 30 receives a stop command from the electronic control unit to stop the DC motor 2a, it determines NO in step S100 and again in step S160. Accordingly, in step S190, the control circuit 30, as the third control unit, continuously turns off the semiconductor switches SW1, SW2, SW3, and SW4, respectively. As a result, the flow of current between the positive electrode 10 and negative electrode 11 of the DC power supply through the DC motor 2a and the wires 60a and 60b is stopped. Consequently, the output shaft of the DC motor 2a is stopped because the power supply from the DC power supply is stopped.

[0045] At this time, the wires 60a and 60b dissipate heat into their surroundings. Consequently, the temperature of the wires 60a and 60b decreases below temperature T2 and approaches the ambient temperature. Next, in step S200, the control circuit 30 calculates the current i flowing through the wires 60a and 60b in order to calculate the temperature of the wires 60a and 60b. For example, the control circuit 30 calculates the current i by dividing the terminal voltage of the semiconductor switch SW1 by the on-resistance of the semiconductor switch SW1, similar to step S120 above. At this time, the output voltages of the current detection units 20a and 20b become zero [V]. Therefore, the current i flowing through the conductors of the wires 60a and 60b becomes zero [A].

[0046] Next, in step S130, the control circuit 30 calculates the temperature T3 of wires 60a and 60b based on the temperature data, taking into account the heat dissipation from the conductors of wires 60a and 60b to the surroundings. Temperature T3 is the temperature calculated in the temperature calculation process of step S130, which is executed for the third time after the start of motor control processing. Specifically, the control circuit 30 calculates the ambient temperature Ts of wires 60a and 60b based on the temperature data. In addition, the control circuit 30 calculates the temperature T3 of wires 60a and 60b by substituting the ambient temperature Ts, current i, constant r, constant R, constant C, and time T into equation 5.

[0047] The current i, constants r, R, and C are as described above. Time T is the period during which semiconductor switches SW1, SW2, SW3, and SW4 are continuously turned off. The current i is zero, as described above. Therefore, the temperature T3 of wires 60a and 60b is the same as the ambient temperature Ts of wires 60a and 60b.

number

[0048] Next, in step S140, the control circuit 30 determines NO if the temperature T3 of the wires 60a and 60b is below the threshold, indicating that no overcurrent is flowing through the wires 60a and 60b. Subsequently, as long as the control circuit 30 determines NO in step S140 because the temperature of the wires 60a and 60b is below the threshold, it executes one of the forward rotation process in step S110, the reverse rotation process in step S170, or the stop process in step S190.

[0049] Subsequently, in the nth step S100, the control circuit 30, upon receiving a stop command from the electronic control unit, determines NO, and also determines NO in step S160. n is an integer greater than or equal to 4. Accordingly, in the next step S170, the control circuit 30 turns off the semiconductor switches SW1, SW2, SW3, and SW4, respectively. As a result, the flow of current between the positive electrode 10 and the negative electrode 11 of the DC power supply to the DC motor 2a and the wires 60a and 60b is stopped.

[0050] Consequently, the DC motor 2a stops its output shaft. At this time, the wires 60a and 60b dissipate heat into their surroundings. Therefore, the temperature of the wires 60a and 60b is T n-1 It will decrease further and approach the ambient temperature Ts. Here, temperature T n-1 This is the temperature of the wires 60a and 60b calculated by the control circuit 30 in step 130, which was executed for the (n-1)th time.

[0051] Next, in step S200, the control circuit 30 calculates zero [A] as the current i flowing through the wires 60a and 60b, as described above. Next, in step S130, the control circuit 30 calculates the ambient temperature Ts of the wires 60a and 60b based on the temperature data, and substitutes this ambient temperature Ts, current i, constant r, constant R, constant C, and time T into equation 6 to obtain the temperature T of the wires 60a and 60b. n Calculate.

[0052] Temperature T of electric wires 60a and 60b n This results in the same temperature Ts as the ambient temperature Ts of wires 60a and 60b. This allows us to take into account the heat dissipation from the conductors of wires 60a and 60b to the surroundings and adjust the temperature T of wires 60a and 60b accordingly. n It is possible to calculate this.

number

[0053] Next, in the (n+1)th step S100, when the control circuit 30 receives a forward rotation command from the electronic control unit, it determines that it is YES. Accordingly, in step S110, the control circuit 30 keeps semiconductor switches SW1 and SW4 ON while semiconductor switches SW2 and SW3 are OFF. As a result, a current ia flows from the positive electrode 10 of the DC power supply to the negative electrode 11 through semiconductor switch SW1, input / output terminal 51, wire 60a, DC motor 2a, wire 60b, and input / output terminal 52. Consequently, the DC motor 2a rotates its output shaft in the forward direction using the power supplied from the DC power supply. As a result, wires 60a and 60b generate heat based on the current ia. At this time, the temperature of wires 60a and 60b is T n It will be higher than that.

[0054] Next, in step S120, the control circuit 30 calculates the current ia based on the forward voltage data. Next, in step S130, the control circuit 30 calculates the temperature T of the electric wires 60a and 60b based on the current ia calculated in step S120 above. n+1 is calculated. The temperature T n+1 is the temperature calculated in the temperature calculation process of step S130 executed for the (n + 1)-th time after the start of execution of the motor control process. Specifically, the control circuit 30 substitutes the current ia, the constants r, R, C, and the time T into Equation 7 to calculate the temperature rise ΔT n+1 .

[0055]

Equation

[0056]

Equation

[0057] Accordingly, in step S170, the control circuit 30 turns off semiconductor switches SW1 and SW4 and turns on semiconductor switches SW2 and SW3. As a result, current ib flows from the positive electrode 10 through semiconductor switch SW3, input / output terminal 52, wire 60b, DC motor 2a, wire 60a, input / output terminal 51, and semiconductor switch SW2 to the negative electrode 11. Consequently, the DC motor 2a reverses its output shaft with power supplied from the DC power supply.

[0058] Next, in step S180, the control circuit 30 calculates the current ib based on the reverse voltage data. Then, in step S130, the control circuit 30 calculates the temperature T of the wires 60a and 60b based on the current ib. n+2 Calculate this temperature T. n+2 This is the temperature calculated in the temperature calculation process of step S130, which is executed for the (n+2)th time after the start of motor control processing. Specifically, the control circuit 30 substitutes the current ib, constant r, constant R, constant C, and time T into equation 9 to calculate the temperature rise ΔT. n+2 Calculate.

[0059]

number

[0060]

number

[0061] According to the embodiment described above, the vehicle motor control device 1 includes an H-bridge circuit 50 equipped with semiconductor switches SW1, SW2, SW3, and SW4, as well as electric wires 60a and 60b, and a control circuit 30. The semiconductor switch SW1 is positioned between the positive electrode 10 of the DC power supply and the semiconductor switch SW2. The semiconductor switch SW2 is positioned between the semiconductor switch SW1 and the negative electrode 11. The semiconductor switch SW3 is positioned between the positive electrode 10 and the semiconductor switch SW4. The semiconductor switch SW4 is positioned between the semiconductor switch SW3 and the negative electrode 11.

[0062] The electric wires 60a and 60b are connected in series with the DC motor 2a between common connection terminals 40 and 41. Common connection terminal 40 is the first common connection terminal to which semiconductor switches SW1 and SW2 are commonly connected. Common connection terminal 41 is the second common connection terminal to which semiconductor switches SW3 and SW4 are commonly connected. In step S110, the control circuit 30 turns on semiconductor switches SW1 and SW4 while turning off semiconductor switches SW2 and SW3. As a result, a current ia flows from the positive electrode 10 through semiconductor switch SW1, input / output terminal 51, electric wire 60a, DC motor 2a, electric wire 60b, input / output terminal 52, and semiconductor switch SW4 to the negative electrode 11.

[0063] In step S170, the control circuit 30 turns on semiconductor switches SW2 and SW3 while semiconductor switches SW1 and SW4 are turned off. As a result, a current ib flows from the positive electrode 10 through semiconductor switch SW3, input / output terminal 52, wire 60b, DC motor 2a, wire 60a, input / output terminal 51, and semiconductor switch SW2 to the negative electrode 11. In step S130, the control circuit 30 calculates the temperature rise ΔTa, which is the amount of temperature rise in wires 60a and 60b that occurred as a result of the control processing in step 110, based on the current ia. In step S130, the control circuit 30 calculates the temperature rise ΔTb, which is the amount of temperature rise in wires 60a and 60b that occurred as a result of the control processing in step S170, based on the current ib.

[0064] In step S130, the control circuit 30 calculates the temperatures of wires 60a and 60b, taking into account the temperature rise ΔTa and ΔTb. For example, in step S130, the control circuit 30 calculates the temperatures of wires 60a and 60b by adding the temperature rise ΔTa and ΔTb. Therefore, it is possible to calculate the temperatures of wires 60a and 60b, taking into account the heat generated by wires 60a and 60b when the DC motor 2a rotates forward and when the DC motor 2a rotates backward. As a result, the temperatures of wires 60a and 60b can be calculated correctly. With this configuration, the following effects (α) and (β) can be obtained.

[0065] (α) When the control circuit 30 receives a stop command for the DC motor 2a from the electronic control unit, in step S190, it turns off the semiconductor switches SW1, SW2, SW3, and SW4. This stops the flow of current between the positive electrode 10 and the negative electrode 11 through the DC motor 2a and the wires 60a and 60b. In step S130, the control circuit 30 calculates the temperature of the wires 60a and 60b, taking into account the heat dissipation from the wires 60a and 60b to the surroundings during the execution of the control process in step S190. Therefore, the temperature of the wires 60a and 60b when the DC motor 2a is stopped can be calculated more accurately.

[0066] (β) In step S150, the control circuit 30 determines whether or not an overcurrent is flowing through the wires 60a and 60b by determining whether or not the temperatures of the wires 60a and 60b calculated in the temperature calculation process in step S130 are above a threshold. When the control circuit 30 determines in step S150 that an overcurrent is flowing through the wires 60a and 60b, it turns off the semiconductor switches SW1, SW2, SW3, and SW4 to stop the overcurrent from flowing through the wires 60a and 60b. This ensures that overcurrent protection for the wires 60a and 60b is properly implemented.

[0067] (Second Embodiment) In the first embodiment described above, a vehicle motor control device for controlling one DC motor 2a was described. However, instead, this second embodiment of a vehicle motor control device for controlling DC motors 2a, 2b, and 2c will be described with reference to Figures 3 and 4. Figure 3 is a diagram showing the electrical circuit configuration of circuit 50A of the vehicle motor control device of this embodiment. Figure 4 is an electrical circuit diagram showing the connection relationships of circuit 50A, current detection units 20x, 20y, 20z, temperature detection units 21a, 21b, 21c, and control circuit 30 of the vehicle motor control device.

[0068] As shown in Figure 3, the vehicle motor control device includes a circuit 50A that replaces the H-bridge circuit 50, and electric wires 60a, 60b, 61a, 61b, 62a, and 62b. Circuit 50A includes half-bridge circuits 53A, 53B, and 53C. As shown in Figure 4, the vehicle motor control device is equipped with current detection units 20x, 20y, and 20z, temperature detection units 21a, 21b, and 21c, and a control circuit 30.

[0069] Half-bridge circuit 53A includes semiconductor switches SW1 and SW2. The input terminal of semiconductor switch SW1 is connected to the positive electrode 10. The output terminal of semiconductor switch SW1 is connected to the input terminal of semiconductor switch SW2. The output terminal of semiconductor switch SW2 is located on the negative electrode 11. Half-bridge circuit 53B, together with half-bridge circuit 53A, constitutes H-bridge circuit 50. Half-bridge circuit 53B includes semiconductor switches SW3 and SW4. The input terminal of semiconductor switch SW3 is connected to the positive electrode 10. The output terminal of semiconductor switch SW3 is connected to the input terminal of semiconductor switch SW4. The output terminal of semiconductor switch SW4 is located on the negative electrode 11.

[0070] The half-bridge circuit 53C includes semiconductor switches SW5 and SW6. Semiconductor switch SW5 is the fifth switch, and its input terminal is connected to the positive electrode 10. The output terminal of semiconductor switch SW5 is connected to the input terminal of semiconductor switch SW6. The output terminal of semiconductor switch SW6 (i.e., the sixth switch) is located on the negative electrode 11. For the sake of explanation, the terminal to which semiconductor switches SW1 and SW2 are commonly connected will be referred to as the common connection terminal 40, the terminal to which semiconductor switches SW3 and SW4 are commonly connected will be referred to as the common connection terminal 41, and the terminal to which semiconductor switches SW5 and SW6 are commonly connected will be referred to as the common connection terminal 42.

[0071] Between common connection terminals 40 and 41, electric wires 60a and 60b and a DC motor 2a are connected in series. Electric wire 60a is placed between common connection terminal 40 and the positive electrode of the DC motor 2a. Electric wire 60b is placed between the negative electrode of the DC motor 2a and common connection terminal 41. Between common connection terminal 41 and common connection terminal (i.e., third common connection terminal) 42, electric wires (i.e., second electric wires) 61a and 61b and a DC motor 2b are connected in series.

[0072] A wire 61a is placed between the common connection terminal 41 and the positive electrode of the DC motor 2b. A wire 61b is placed between the negative electrode of the DC motor 2b and the common connection terminal 42. Wires 62a, 62b, and the DC motor 2c are connected in series between the common connection terminals 42 and 40. A wire 62a is placed between the common connection terminal 42 and the positive electrode of the DC motor 2c. A wire 62b is placed between the negative electrode of the DC motor 2c and the common connection terminal 40.

[0073] The current detection unit 20x is used to detect the current ix flowing through the wires 60a and 60b. In this embodiment, the current detection unit 20x is, for example, a detection element that detects the terminal voltage, which is the voltage between the input terminal and the output terminal of either semiconductor switch SW1 or semiconductor switch SW3. The current ix is ​​the current flowing through the wires 60a and 60b between the common connection terminals 40 and 41.

[0074] The current detection unit 20y is used to detect the current iy flowing through the wires 61a and 61b. In this embodiment, the current detection unit 20y is, for example, a detection element that detects the terminal voltage, which is the voltage between the input terminal and the output terminal of one of the semiconductor switches SW3 and SW5. The current iy is the current flowing through the wires 61a and 61b between the common connection terminals 41 and 42.

[0075] The current detection unit 20z is used to detect the current iz flowing through the wires 62a and 62b. In this embodiment, the current detection unit 20z is, for example, a detection element that detects the terminal voltage, which is the voltage between the input terminal and output terminal of either semiconductor switch SW5 or semiconductor switch SW1. The current iz is the current flowing through the wires 62a and 62b between the common connection terminals 42 and 40. The current detection units 20x, 20y, and 20z are each composed of detection elements similar to those of the current detection unit 20a in the first embodiment described above.

[0076] Furthermore, the temperature detection unit 21a is a temperature sensor that detects the ambient temperature of the electric wires 60a and 60b. The temperature detection unit 21b is a temperature sensor that detects the ambient temperature of the electric wires 61a and 61b. The temperature detection unit 21c is a temperature sensor that detects the ambient temperature of the electric wires 62a and 62b. Each of the temperature detection units 21a, 21b, and 21c is composed of a temperature sensor similar to the temperature detection unit 21a in the first embodiment described above.

[0077] The control circuit 30 is a microcomputer equipped with a CPU, RAM, ROM, non-volatile rewritable memory, analog-to-digital converter, etc. When power is supplied from the power supply unit, the control circuit 30 executes a computer program recorded in the ROM or non-volatile rewritable memory, which are non-transitional physical recording media. Along with the execution of the computer program, the control circuit 30 performs various control processes, such as the motor control process shown in Figure 2.

[0078] The motor control process controls the DC motors 2a, 2b, and 2c while performing wire protection to prevent overcurrent from flowing through the wires 60a, 60b, 61a, 61b, 62a, and 62b based on currents ix, iy, and iz. The ROM and non-volatile rewritable memory store various constants for calculating the temperatures of the wires 60a, 60b, 61a, 61b, 62a, and 62b, along with the computer program. The analog-to-digital converter converts the output voltages of the current detection units 20x, 20y, and 20z, and the output voltages of the temperature detection units 21a, 21b, and 21c, respectively, into digital signals.

[0079] Next, the operation of the vehicle motor control device 1 of this embodiment will be described with reference to Figure 2. The control circuit 30 of this embodiment repeatedly executes motor control processing for each DC motor according to the flowchart in Figure 2. First, the temperature detection unit 21a outputs an output voltage to the control circuit 30 indicating the ambient temperature of the wires 60a and 60b. The temperature detection unit 21b outputs an output voltage to the control circuit 30 indicating the ambient temperature of the wires 61a and 61b. The temperature detection unit 21c outputs an output voltage to the control circuit 30 indicating the ambient temperature of the wires 62a and 62b.

[0080] The current detection unit 20x outputs an output voltage indicating the terminal voltage of semiconductor switch SW1 and an output voltage indicating the terminal voltage of semiconductor switch SW3 to the control circuit 30. The current detection unit 20y outputs an output voltage indicating the terminal voltage of semiconductor switch SW3 and an output voltage indicating the terminal voltage of semiconductor switch SW5 to the control circuit 30. The current detection unit 20z outputs an output voltage indicating the terminal voltage of semiconductor switch SW5 and an output voltage indicating the terminal voltage of semiconductor switch SW1 to the control circuit 30.

[0081] The analog-to-digital converter of the control circuit 30 repeatedly converts the output voltages of the current detection units 20x, 20y, and 20z, and the temperature detection units 21a, 21b, and 21c, respectively, into digital data. For the sake of explanation, the digital data representing the output voltage of the temperature detection unit 21a will be referred to as the first temperature data. The first temperature data is digital data representing the ambient temperature of the wires 60a and 60b. The digital data representing the output voltage of the temperature detection unit 21b will be referred to as the second temperature data. The second temperature data is digital data representing the ambient temperature of the wires 61a and 61b. The digital data representing the output voltage of the temperature detection unit 21c will be referred to as the third temperature data. The third temperature data is digital data representing the ambient temperature of the wires 62a and 62b.

[0082] The digital data representing the output voltage of the current detection unit 20x when semiconductor switches SW1 and SW4 are turned on is defined as the first forward rotation voltage data. The first forward rotation voltage data is digital data representing the terminal voltage of semiconductor switch SW1 when the DC motor 2a is rotating in the forward direction. The digital data representing the output voltage of the current detection unit 20y when semiconductor switches SW3 and SW6 are turned on is defined as the second forward rotation voltage data.

[0083] The second forward rotation voltage data is digital data showing the terminal voltage of semiconductor switch SW3 when DC motor 2b is rotating in the forward direction. The third forward rotation voltage data is digital data showing the output voltage of current detection unit 20z when semiconductor switches SW5 and SW2 are turned on. The third forward rotation voltage data is digital data showing the terminal voltage of semiconductor switch SW5 when DC motor 2c is rotating in the forward direction.

[0084] The digital data representing the output voltage of the current detection unit 20x when semiconductor switches SW3 and SW2 are turned on is defined as the first reverse voltage data. The first reverse voltage data is digital data representing the terminal voltage of semiconductor switch SW3 when the DC motor 2a is rotating in reverse. The digital data representing the output voltage of the current detection unit 20y when semiconductor switches SW5 and SW4 are turned on is defined as the second reverse voltage data.

[0085] The second reverse voltage data is digital data showing the terminal voltage of semiconductor switch SW5 when DC motor 2b is rotating in reverse. The third reverse voltage data is digital data showing the output voltage of current detection unit 20z when semiconductor switches SW1 and SW6 are turned on. The third reverse voltage data is digital data showing the terminal voltage of semiconductor switch SW1 when DC motor 2c is rotating in reverse. First, the control circuit 30 performs motor control processing on the DC motor 2a. In this case, the control circuit 30 performs the control processing in steps S100 to S200, similar to the first embodiment described above.

[0086] At this time, in step S110, the control circuit 30 turns on semiconductor switches SW1 and SW4 while turning off semiconductor switches SW2, SW3, SW5 and SW6. As a result, current ix flows from the positive electrode 10 to the negative electrode 11 through semiconductor switch SW1, wire 60a, DC motor 2a, wire 60b, and semiconductor switch SW4. In step S120, the control circuit 30 calculates current ix [A] based on the first positive voltage data, similar to current ia above. In step S130, the control circuit 30 calculates the temperatures of wires 60a and 60b based on the current ix calculated in step S120 and the first temperature data.

[0087] In step S170, the control circuit 30 turns on semiconductor switches SW2 and SW3 while turning off semiconductor switches SW1, SW4, SW5, and SW6. As a result, current ix flows from the positive electrode 10 to the negative electrode 11 through semiconductor switch SW3, wire 60b, DC motor 2a, wire 60a, and semiconductor switch SW2. In step S180, the control circuit 30 calculates current ix [A] based on the first reverse voltage data, similar to current ib. Furthermore, in step S130, the control circuit 30 calculates the temperatures of wires 60a and 60b based on the current ix calculated in step S180 and the first temperature data.

[0088] In step S190, the control circuit 30 successively turns off the semiconductor switches SW1, SW2, SW3, SW4, SW5, and SW6, respectively. Thus, current is stopped from flowing between the positive electrode 10 and the negative electrode 11 of the DC power supply through the DC motor 2a and the wires 60a and 60b. Next, in step S200, the control circuit 30 calculates the current i (e.g., zero) flowing through the wires 60a and 60b in order to calculate the temperature of the wires 60a and 60b. Furthermore, in step S130, the control circuit 30 calculates the temperature of the wires 60a and 60b based on the current i calculated in step S200 and the first temperature data.

[0089] Therefore, the control circuit 30 determines whether or not an overcurrent is flowing through the wires 60a and 60b by determining whether or not the temperatures of the wires 60a and 60b calculated in this way are above a threshold. When the control circuit 30 determines that an overcurrent is flowing through the wires 60a and 60b and the result is YES, it turns off the semiconductor switches SW1, SW2, SW3, SW4, SW5, and SW6 to stop the overcurrent from flowing through the wires 60a and 60b.

[0090] The control circuit 30 performs motor control processing on the DC motor 2b. In this case, in step S100, the control circuit 30 determines whether or not it has received a forward rotation command from the electronic control unit to rotate the DC motor 2b in the forward direction. In step S110, the control circuit 30, as the fourth control unit, turns on semiconductor switches SW3 and SW6 while semiconductor switches SW1, SW2, SW4 and SW5 are turned off.

[0091] As a result, a current iy (i.e., the third current) flows from the positive electrode 10 to the negative electrode 11 through the semiconductor switch SW3, the wire 61a, the DC motor 2b, the wire 61b, and the semiconductor switch SW6. In step S120, the control circuit 30 calculates the current iy [A] based on the second positive voltage data, similar to the current ia mentioned above. In step S130, the control circuit 30 calculates the temperatures of the wires 61a and 61b based on the current iy calculated in step S120 and the second temperature data.

[0092] In step S170, the control circuit 30, acting as the fifth control unit, turns on semiconductor switches SW4 and SW5 while keeping semiconductor switches SW1, SW2, SW3, and SW6 off. As a result, current iy flows from the positive electrode 10 to the negative electrode 11 through semiconductor switch SW5, wire 61b, DC motor 2b, wire 61a, and semiconductor switch SW4. In step S180, the control circuit 30 calculates current iy [A] based on the second reverse voltage data, similar to current ib. In step S180, the control circuit 30 calculates the temperatures of wires 61a and 61b based on the current iy calculated in step S170 and the second temperature data.

[0093] In step S190, the control circuit 30 turns off the semiconductor switches SW1, SW2, SW3, SW4, SW5, and SW6. In step S200, the control circuit 30 calculates the current i (for example, zero) that flows through the wires 61a and 61b when the semiconductor switches SW1, SW2, SW3, SW4, SW5, and SW6 are turned off. Next, in step S130, the temperature of the wires 61a and 61b is calculated based on the current i calculated in step S200 and the second temperature data.

[0094] Therefore, the control circuit 30 determines whether or not an overcurrent is flowing through the wires 62a and 62b by determining whether or not the temperature of the wires 62a and 62b calculated in this way is above a threshold. When the control circuit 30 determines that an overcurrent is flowing through the wires 62a and 62b and determines that it is YES, it turns off the semiconductor switches SW1, SW2, SW3, SW4, SW5, and SW6 to stop the overcurrent from flowing through the wires 62a and 62b.

[0095] The control circuit 30 performs motor control processing on the DC motor 2c. In this case, in step S100, the control circuit 30 determines whether or not it has received a forward rotation command from the electronic control unit to rotate the DC motor 2c in the forward direction. In step S110, the control circuit 30 turns on semiconductor switches SW2 and SW5 with semiconductor switches SW1, SW3, SW4 and SW6 turned off.

[0096] As a result, current iz flows from the positive electrode 10 through the semiconductor switch SW5, wire 62a, DC motor 2c, wire 62b, and semiconductor switch SW2 to the negative electrode 11. In step S120, the control circuit 30 calculates the current iz[A] based on the third positive voltage data, similar to the current ia described above. In step S130, the control circuit 30 calculates the temperatures of wires 62a and 62b based on the current iz calculated in step S120 and the third temperature data.

[0097] In step S170, the control circuit 30 turns on semiconductor switches SW1 and SW6 while keeping semiconductor switches SW2, SW3, SW4, and SW5 off. As a result, current iz flows from the positive electrode 10 to the negative electrode 11 through semiconductor switch SW1, wire 62b, DC motor 2c, wire 62a, and semiconductor switch SW6. In step S180, the control circuit 30 calculates the current iz[A] based on the third reverse voltage data, similar to the current ib described above.

[0098] In step S130, the control circuit 30 calculates the temperature of wires 62a and 62b based on the current iz calculated in step S180 and the third temperature data. In step S190, the control circuit 30 turns off the semiconductor switches SW1, SW2, SW3, SW4, SW5, and SW6. In step S200, the control circuit 30 calculates the current i (for example, zero) flowing through wires 62a and 62b when the semiconductor switches SW1, SW2, SW3, SW4, SW5, and SW6 are turned off. Next, in step S130, the temperature of wires 62a and 62b is calculated based on the current i calculated in step S200 and the third temperature data.

[0099] Therefore, the control circuit 30 determines whether or not an overcurrent is flowing through the wires 62a and 62b by determining whether or not the temperature of the wires 62a and 62b calculated in this way is above a threshold. When the control circuit 30 determines that an overcurrent is flowing through the wires 62a and 62b and determines that it is YES, it turns off the semiconductor switches SW1, SW2, SW3, SW4, SW5, and SW6 to stop the overcurrent from flowing through the wires 62a and 62b.

[0100] According to the embodiment described above, the control circuit 30 performs motor control processing on the DC motor 2a. In step S110, the control circuit 30 turns off semiconductor switches SW2, SW3, SW5, and SW6, and turns on semiconductor switches SW1 and SW4. As a result, a current Ix flows from the positive electrode 10 to the negative electrode 11 through semiconductor switch SW1, wire 60a, DC motor 2a (i.e., the first electrical load), wire 60b, and semiconductor switch SW4. In step S120, the control circuit 30 detects the current Ix flowing through wires 60a and 60b. In step S130, the control circuit 30 calculates the temperature rise ΔTa, which is the temperature rise of wires 60a and 60b (i.e., the first wire) that has risen due to the execution of the control processing in step S110, based on the current Ix.

[0101] In step S170, the control circuit 30 turns off semiconductor switches SW1, SW4, SW5, and SW6, and turns on semiconductor switches SW2 and SW3. As a result, a current Ix flows from the positive electrode 10 through semiconductor switch SW3, wire 60b, DC motor 2a, wire 60a, and semiconductor switch SW2 to the negative electrode 11. In step S180, the control circuit 30 detects the current Ix flowing through wires 60a and 60b.

[0102] In step S130, the control circuit 30 calculates the temperature rise ΔTb, which is the amount of temperature rise in the wires 60a and 60b that occurred as a result of the control process in step S170, based on the current Ix. Therefore, the control circuit 30, as the first wire temperature calculation unit, calculates the temperature of the wires 60a and 60b, taking into account the heat generated by the wires 60a and 60b when the DC motor 2a rotates forward and the heat generated by the wires 60a and 60b when the DC motor 2a rotates backward. As a result, the temperature of the wires 60a and 60b can be calculated correctly.

[0103] When the control circuit 30 receives a stop command for the DC motor 2a from the electronic control unit, in step S190, it turns off the semiconductor switches SW1, SW2, SW3, SW4, SW5, and SW6. This stops the flow of current from the positive electrode 10 through the wire 60a, the DC motor 2a, and the wire 60b to the negative electrode 11. In step S130, the control circuit 30 calculates the temperature of the wires 60a and 60b, taking into account the heat dissipation from the wires 60a and 60b to the surroundings during the execution of the control process in step S190. Therefore, the temperature of the wires 60a and 60b when the DC motor 2a is stopped can be calculated more accurately.

[0104] The control circuit 30 performs motor control processing on the DC motor 2b. In step S110, the control circuit 30 turns off semiconductor switches SW1, SW2, SW4, and SW6, and turns on semiconductor switches SW3 and SW6. As a result, a current Iy flows from the positive electrode 10 through semiconductor switch SW3, wire 61a, DC motor 2b, wire 61b, and semiconductor switch SW6 to the negative electrode 11.

[0105] In step S120, the control circuit 30 detects the current Iy flowing through the wires 61a and 61b. In step S130, the control circuit 30, acting as a third temperature rise calculation unit, calculates the temperature rise ΔTa based on the current Iy (i.e., the fourth current). The temperature rise ΔTa is the temperature rise (i.e., the third temperature rise) which is the temperature rise of the wires 61a and 61b that occurred as a result of the control processing in step S110.

[0106] In step S170, the control circuit 30 turns off semiconductor switches SW1, SW2, SW3, and SW6, and turns on semiconductor switches SW4 and SW5. As a result, a current Iy flows from the positive electrode 10 to the negative electrode 11 through semiconductor switch SW5, wire 61b, DC motor 2b (i.e., the second electrical load), wire 61a, and semiconductor switch SW4. In step S180, the control circuit 30 detects the current Iy flowing through wires 61a and 61b.

[0107] In step S130, the control circuit 30, acting as a fourth temperature rise calculation unit, calculates the temperature rise ΔTb based on the current Iy (i.e., the fifth current). The temperature rise ΔTb is the temperature rise of the wires 61a and 61b that occurred as a result of the control processing in step S170 (i.e., the fourth temperature rise). Therefore, the control circuit 30, acting as a second wire temperature calculation unit, calculates the temperature of the wires 61a and 61b, taking into account the heat generated by the wires 61a and 61b when the DC motor 2a rotates forward and the heat generated by the wires 61a and 61b when the DC motor 2b rotates backward. As a result, the temperature of the wires 61a and 61b can be calculated correctly.

[0108] When the control circuit 30 receives a stop command for the DC motor 2b from the electronic control unit, as the sixth control unit, in step S190, it turns off the semiconductor switches SW1, SW2, SW3, SW4, SW5, and SW6. This stops the flow of current from the positive electrode 10 to the negative electrode 11 through the DC motor 2b and the wires 61a, 61b. In step S130, the control circuit 30 calculates the temperature of the wires 61a, 61b, taking into account the heat dissipation from the wires 61a, 61b to the surroundings during the execution of the control process in step S190. Therefore, the temperature of the wires 61a, 61b when the DC motor 2b is stopped can be calculated more accurately.

[0109] The control circuit 30 executes motor control processing on the DC motor 2c. In step S110, the control circuit 30 turns off semiconductor switches SW2, SW3, SW4, and SW5, and turns on semiconductor switches SW5 and SW2. As a result, a current Iz flows from the positive electrode 10 through semiconductor switch SW5, wire 62a, DC motor 2c, wire 62b, and semiconductor switch SW2 to the negative electrode 11. In step S120, the control circuit 30 detects the current Iz flowing through wires 62a and 62b. In step S130, the control circuit 30 calculates the temperature rise ΔTa, which is the amount of temperature rise in wires 62a and 62b that occurred as a result of the control processing in step S110, based on the current Iz.

[0110] In step S170, the control circuit 30 turns off semiconductor switches SW1, SW2, SW3, and SW6, and turns on semiconductor switches SW1 and SW6. As a result, a current Iz flows from the positive electrode 10 to the negative electrode 11 through semiconductor switch SW1, wire 62b, DC motor 2b, wire 62a, and semiconductor switch SW6. In step S180, the control circuit 30 detects the current Iz flowing through wires 62a and 62b.

[0111] In step S130, the control circuit 30 calculates the temperature rise ΔTb, which is the amount of temperature rise in wires 62a and 62b that occurred as a result of the control process in step S170, based on the current Iz. Therefore, it is possible to calculate the temperature of wires 62a and 62b, taking into account the heat generated by wires 62a and 62b when the DC motor 2c is rotating forward and when the DC motor 2c is rotating backward. As a result, the temperature of wires 62a and 62b can be calculated correctly.

[0112] When the control circuit 30 receives a stop command for the DC motor 2c from the electronic control unit, in step S190, it turns off the semiconductor switches SW1, SW2, SW3, SW4, SW5, and SW6. This stops the flow of current from the positive electrode 10 to the negative electrode 11 through the DC motor 2c and the wires 62a and 62b. In step S130, the control circuit 30 calculates the temperature of the wires 62a and 62b, taking into account the heat dissipation from the wires 62a and 62b to the surroundings during the execution of the control process in step S190. Therefore, the temperature of the wires 62a and 62b when the DC motor 2c is stopped can be calculated more accurately.

[0113] In step S140, the control circuit 30, acting as a first current determination unit and a second current determination unit, determines for each DC motor whether the temperature of the wire is above a threshold, thereby determining whether an overcurrent is flowing through the wire. Therefore, when the control circuit 30, acting as a first stop control unit and a second stop control unit, determines that an overcurrent is flowing through the wire for each DC motor, it controls the semiconductor switches SW1, SW2, SW3, SW4, SW5, and SW6. This prevents overcurrent from flowing through the wires 60a, 60b, 61a, 61b, 62a, and 62b for each DC motor. Thus, overcurrent protection for the wires 60a, 60b, 61a, 61b, 62a, and 62b can be appropriately implemented for each DC motor.

[0114] (Other embodiments) (1) In the first embodiment described above, an example was given in which a DC motor 2a is used as the electrical load. However, instead of this, a light source device such as a hot cathode tube or a cold cathode tube, or a single-phase AC motor may be used as the electrical load. Similarly, in the second embodiment described above, a light source device such as a hot cathode tube or a cold cathode tube, or a single-phase AC motor may be used as the electrical load instead of the DC motors 2a, 2b, and 2c.

[0115] (2) In the first embodiment described above, an example was given in which the terminal voltage of the semiconductor switch SW1 detected by the current detection unit 20a was divided by the on-resistance of the semiconductor switch SW1 to calculate the current ia flowing through the wires 60a and 60b. However, instead of this, the following (a)(b)(c) may be used. (a) The current detection unit 20a detects the terminal voltage between the input and output terminals of the semiconductor switch SW4. The control circuit 30 calculates the current ia by dividing the terminal voltage of the semiconductor switch SW4 by the on-resistance of the semiconductor switch SW4.

[0116] (b) A resistive element, which is a shunt resistor through which a current ia flows, is connected in series with the wires 60a and 60b between the positive electrode 10 and the negative electrode 11, and is used as the current detection unit 20a. When the semiconductor switches SW1 and SW4 are turned on, the current detection unit 20a calculates the terminal voltage, which is the voltage between one terminal and the other terminal of the resistive element. The control circuit 30 calculates the current ia by dividing the terminal voltage of the resistive element by the resistance value of the resistive element.

[0117] (c) A transistor that forms a current mirror circuit together with the semiconductor switch SW1 is used as the current detection unit 20a. The control terminal of the transistor is connected to the control terminal of the semiconductor switch SW1. The input terminal of the transistor is connected to the positive electrode 10 of the DC power supply. The output terminal of the transistor is connected to the negative electrode 11. A detection current, which is a current proportional to the current ia, flows through the input and output terminals of the transistor. The control circuit 30 will detect the detection current instead of the current ia. Alternatively, a transistor that forms a current mirror circuit together with the semiconductor switch SW4 may be used as the current detection unit 20a. A detection current, which is a current proportional to the current ia, flows through the input and output terminals of the transistor.

[0118] (3) In the second embodiment described above, the current ix flowing through the wires 60a and 60b may be calculated not only by dividing the terminal voltage of the semiconductor switch SW1 detected by the current detection unit 20x by the on-resistance of the semiconductor switch SW1, but also as follows: (d)(e)(f). (d) The current detection unit 20x detects the terminal voltage of the semiconductor switch SW4. The control circuit 30 calculates the current ia by dividing the terminal voltage of the semiconductor switch SW4 by the on-resistance of the semiconductor switch SW4.

[0119] (e) A resistive element, which is a shunt resistor through which a current ix flows, is connected in series with the wires 60a and 60b between the positive electrode 10 and the negative electrode 11, and is used as the current detection unit 20x. When the semiconductor switches SW1 and SW4 are turned on, the current detection unit 20x calculates the terminal voltage, which is the voltage between one terminal and the other terminal of the resistive element. The control circuit 30 calculates the current ix by dividing the terminal voltage of the resistive element by the resistance value of the resistive element.

[0120] (f) A transistor that forms a current mirror circuit together with the semiconductor switch SW1 is used as the current detection unit 20x. The control terminal of the transistor is connected to the control terminal of the semiconductor switch SW1. The input terminal of the transistor is connected to the positive electrode 10 of the DC power supply. The output terminal of the transistor is connected to the negative electrode 11. A detection current, which is proportional to the current ix, flows through the input and output terminals of the transistor. The control circuit 30 detects the detection current instead of the current ix.

[0121] Alternatively, a transistor that forms a current mirror circuit together with the semiconductor switch SW4 may be used as the current detection unit 20a. A detection current, which is proportional to the current ix, flows through the input and output terminals of the transistor. In the second embodiment as well, the current iy flowing through the wires 61a and 61b may be calculated in the same manner as in (d), (e), and (f) above. In the second embodiment as well, the current iz flowing through the wires 62a and 62b may be calculated in the same manner as in (d), (e), and (f) above.

[0122] (4) In the first embodiment described above, an example was given in which the current ib flowing through the wires 60a and 60b was calculated by dividing the terminal voltage of the semiconductor switch SW3 detected by the current detection unit 20b by the on-resistance of the semiconductor switch SW3. However, instead of this, the following (g)(h)(i) may be used. (g) The current detection unit 20b detects the terminal voltage between the input terminal and output terminal of the semiconductor switch SW2. The control circuit 30 calculates the current ib by dividing the terminal voltage of the semiconductor switch SW2 by the on-resistance of the semiconductor switch SW2.

[0123] (h) A resistive element, which is a shunt resistor through which a current ib flows, is used as the current detection unit 20b, connected in series with the wires 60a and 60b between the positive electrode 10 and the negative electrode 11. The current detection unit 20b detects the terminal voltage between one terminal and the other terminal of the resistive element when the semiconductor switches SW3 and SW2 are turned on. The control circuit 30 calculates the current ib by dividing the terminal voltage of the resistive element by the resistance value of the resistive element.

[0124] (i) A transistor that forms a current mirror circuit together with the semiconductor switch SW3 is used as the current detection unit 20b. The control terminal of the transistor is connected to the control terminal of the semiconductor switch SW3. The input terminal of the transistor is connected to the positive electrode 10 of the DC power supply. The output terminal of the transistor is connected to the negative electrode 11. A detection current, which is proportional to the current ib, flows through the input and output terminals of the transistor. The control circuit 30 will detect the detection current instead of the current ib. Alternatively, a transistor that forms a current mirror circuit together with the semiconductor switch SW2 may be used as the current detection unit 20b. A detection current, which is proportional to the current ib, flows through the input and output terminals of the transistor. The control circuit 30 will detect the detection current instead of the current ib.

[0125] (5) In the second embodiment described above, the current ib flowing through the wires 61a and 61b is not limited to the case in which the terminal voltage of the semiconductor switch SW3 detected by the current detection unit 20x is divided by the on-resistance of the semiconductor switch SW3, but may also be done as follows (j)(k)(l). (j) The current detection unit 20x detects the terminal voltage between the input and output terminals of the semiconductor switch SW2. The control circuit 30 calculates the current ix by dividing the terminal voltage of the semiconductor switch SW2 by the on-resistance of the semiconductor switch SW2.

[0126] (k) A resistive element, which is a shunt resistor through which a current ix flows, is used as the current detection unit 20x, connected in series with the wires 60a and 60b between the positive electrode 10 and the negative electrode 11. When the semiconductor switches SW3 and SW2 are turned on, the current detection unit 20x detects the terminal voltage between one terminal and the other terminal of the resistive element. The control circuit 30 calculates the current ix by dividing the terminal voltage of the resistive element by the resistance value of the resistive element.

[0127] (l) A transistor that forms a current mirror circuit together with the semiconductor switch SW3 is used as the current detection unit 20b. The control terminal of the transistor is connected to the control terminal of the semiconductor switch SW3. The input terminal of the transistor is connected to the positive electrode 10 of the DC power supply. The output terminal of the transistor is connected to the negative electrode 11. A detection current, which is proportional to the current ix, flows through the input and output terminals of the transistor.

[0128] The control circuit 30 will detect a detection current instead of the current ix. Alternatively, a transistor that forms a current mirror circuit together with the semiconductor switch SW2 may be used as the current detection unit 20x. A detection current, which is proportional to the current ix, flows through the input and output terminals of the transistor. The control circuit 30 will detect the detection current instead of the current ix. In the second embodiment described above, the current iy flowing through the wires 61a and 61b may also be calculated in the same manner as (j), (k), and (l) described above. In the second embodiment described above, the current iz flowing through the wires 62a and 62b may also be calculated in the same manner as (j), (k), and (l) described above.

[0129] (4) In the first embodiment described above, the semiconductor switches SW1, SW2, SW3, and SW4 were described in an example in which they are composed of semiconductor switches alone. However, instead, semiconductor switches with a current detection function that incorporates a current detection unit 20a or a current detection unit 20b may be used as semiconductor switches SW1, SW2, SW3, and SW4. Similarly, in the second embodiment described above, semiconductor switches with a current detection function that incorporates a current detection unit 20a or a current detection unit 20b may be used as semiconductor switches SW1, SW2, SW3, SW4, SW5, and SW6.

[0130] (5) In the second embodiment described above, an example was described in which three DC motors 2a, 2b, and 2c were controlled by circuit 50A. However, instead, two DC motors may be controlled by circuit 50A. Alternatively, four or more DC motors may be controlled by circuit 50A. (6) In the first and second embodiments described above, examples of applying the control device of the present disclosure to an automobile have been explained. However, instead, the control device of the present disclosure may be applied to various industrial equipment other than automobiles.

[0131] (7) In the first and second embodiments described above, an example was given in which the ambient temperature of the electric wires 60a and 60b was calculated using the value detected by the temperature detection unit 21a. However, instead, a predetermined temperature may be used as the ambient temperature of the electric wires 60a and 60b. Similarly, in the second embodiment described above, an example was given in which the ambient temperature of the electric wires 61a and 61b was calculated using the value detected by the temperature detection unit 21b. However, instead, a predetermined temperature may be used as the ambient temperature of the electric wires 61a and 61b.

[0132] Alternatively, the detected value of the temperature detection unit 21a may be used as the ambient temperature of the electric wires 61a and 61b. In the second embodiment described above, an example was given in which the ambient temperature of the electric wires 62a and 62b was calculated using the detected value of the temperature detection unit 21c. However, instead, a predetermined temperature may be used as the ambient temperature of the electric wires 62a and 62b. Alternatively, the detected value of the temperature detection unit 21a may be used as the ambient temperature of the electric wires 62a and 62b.

[0133] (8) In the first and second embodiments described above, the control circuit 30 calculated the current i in step S200 by dividing the terminal voltage of the semiconductor switch SW1 by the on-resistance of the semiconductor switch SW1. However, the control circuit 30 may also calculate the current i by dividing the terminal voltage of the semiconductor switch SW2 by the on-resistance of the semiconductor switch SW2.

[0134] The control circuit 30 may calculate the current i by dividing the terminal voltage of the semiconductor switch SW3 by the on-resistance of the semiconductor switch SW3. The control circuit 30 may also calculate the current i by dividing the terminal voltage of the semiconductor switch SW4 by the on-resistance of the semiconductor switch SW4. (9) In the second embodiment described above, an example was given in which a vehicle motor control device was configured using half-bridge circuits 53A, 53B, and 53C. However, instead, a vehicle motor control device may be configured using four or more half-bridge circuits.

[0135] (10) This disclosure is not limited to the embodiments described above, and can be modified as appropriate within the scope of the claims. Furthermore, the embodiments described above are not unrelated to each other and can be combined as appropriate, except in cases where the combination is clearly impossible. In addition, it goes without saying that the elements constituting the embodiments in each embodiment are not necessarily essential, except in cases where they are explicitly stated to be particularly essential or where they are clearly considered essential in principle. Furthermore, in each embodiment, if numerical values ​​such as the number, numerical values, quantities, or ranges of the components of the embodiment are mentioned, they are not limited to those specific numbers, except in cases where they are explicitly stated to be particularly essential or where they are clearly limited to a specific number in principle.

[0136] (Perspective of this disclosure) The above disclosure can be understood from the following perspectives, for example. [First point of view] An H-bridge circuit (50) is provided, in which a first switch (SW1) is positioned between a high-potential section (10) having a predetermined potential and a low-potential section (11) having a lower potential than the high-potential section, a second switch (SW2) is positioned between the first switch and the low-potential section, a third switch (SW3) is positioned between the high-potential section and the low-potential section, and a fourth switch (SW4) is positioned between the third switch and the low-potential section. When the terminal to which the first switch and the second switch are commonly connected is designated as the first common connection terminal (40), and the terminal to which the third switch and the fourth switch are commonly connected is designated as the second common connection terminal (41), a wire (60a, 60b) is connected in series with an electrical load (2a) between the first common connection terminal and the second common connection terminal, A first control unit (S110) turns on the first switch and the fourth switch so that a first current flows from the high-potential section through the first switch, the electrical load, and the fourth switch to the low-potential section, A second control unit (S170) turns on the second switch and the third switch so that a second current flows from the high-potential section through the third switch, the electrical load, and the second switch to the low-potential section, A first temperature rise calculation unit (S130) calculates a first temperature rise, which is the amount of temperature rise in the electric wire that occurs as a result of the execution of the first control unit, based on the first current, A second temperature rise calculation unit (S130) calculates a second temperature rise, which is the rise in temperature of the electric wire caused by the execution of the second control unit, based on the second current, A wire temperature calculation unit (S130) calculates the temperature of the wire taking into account the first temperature rise and the second temperature rise, A control device equipped with the following features. [Second perspective] The control device according to the first viewpoint, wherein the wire temperature calculation unit calculates the temperature of the wire by adding the first temperature rise and the second temperature rise. [Third perspective] When the first control unit is running, the wire temperature calculation unit calculates the temperature of the wire based on the first temperature rise range. The control device according to the first or second aspect, wherein, when the second control unit is being executed, the wire temperature calculation unit calculates the temperature of the wire based on the second temperature rise range. [Fourth perspective] The system includes a third control unit (S190) that controls the first switch, the second switch, the third switch, and the fourth switch, respectively, to stop current from flowing from the high-potential section through the electrical load and the wires to the low-potential section. The control device according to any one of the first to third aspects, wherein the wire temperature calculation unit calculates the temperature of the wire, taking into account the heat dissipation from the wire to its surroundings during the execution of the third control unit. [Fifth perspective] A current determination unit (S140) determines whether or not an overcurrent is flowing through the wire by determining whether or not the temperature of the wire calculated by the wire temperature calculation unit is above a threshold, When the current determination unit determines that an overcurrent is flowing through the wire, a stop control unit (S150) controls the first switch, the second switch, the third switch, and the fourth switch, respectively, to stop the flow of the overcurrent through the wire. A control device according to any one of the first to fourth aspects, comprising the above. [Sixth perspective] A half-bridge circuit (53C) is provided, in which a fifth switch (SW5) is positioned between the high-potential section and the low-potential section, and a sixth switch (SW6) is positioned between the fifth switch and the low-potential section. When the aforementioned electrical load is designated as the first electrical load, the aforementioned wire as the first wire, and the terminal to which the fifth switch and the sixth switch are commonly connected is designated as the third common connection terminal (42), a second wire (61a, 61b) is connected in series with the second electrical load (2b) between the second common connection terminal and the third common connection terminal, A fourth control unit (S110) turns on the third switch and the sixth switch so that a third current flows from the high-potential section to the low-potential section through the third switch, the second electrical load, and the sixth switch, A fifth control unit (S170) turns on the fourth switch and the fifth switch so that a fourth current flows from the high-potential section through the fifth switch, the second electrical load, and the fourth switch to the low-potential section, A third temperature rise calculation unit (S130) calculates a third temperature rise, which is the amount of temperature rise in the second wire that occurs as a result of the execution of the fourth control unit, based on the third current, A fourth temperature rise calculation unit (S130) calculates a fourth temperature rise, which is the temperature rise of the second wire that increased as a result of the execution of the fifth control unit, based on the fourth current, When the wire temperature calculation unit is designated as the first wire temperature calculation unit, a second wire temperature calculation unit (S130) calculates the temperature of the second wire taking into account the third temperature rise range and the fourth temperature rise range, The control device according to the fifth aspect, comprising: [Seventh perspective] The system includes a sixth control unit (S190) that controls the first switch, second switch, third switch, fourth switch, fifth switch, and sixth switch to stop current from flowing from the high-potential section through the second electrical load to the low-potential section, The control device according to the sixth aspect, wherein the second wire temperature calculation unit calculates the temperature of the wire, taking into account the heat dissipation from the wire to its surroundings during the execution of the sixth control unit. [Perspective 8] When the current determination unit is designated as the first current determination unit, the second current determination unit (S140) determines whether or not an overcurrent is flowing through the second wire by determining whether or not the temperature of the second wire calculated by the second wire temperature calculation unit is above a threshold, When the stop control unit is designated as the first stop control unit, the second current determination unit determines that an overcurrent is flowing through the second wire, and the second stop control unit (S150) controls the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch respectively to stop the overcurrent from flowing through the second wire. The control device according to the seventh aspect, comprising: [Explanation of symbols]

[0137] 1. Vehicle motor control device SW1 Semiconductor Switch SW2 Semiconductor Switch SW3 Semiconductor Switch SW4 Semiconductor Switch 20a Current detection unit 20b Current detection unit 21a Temperature detection unit 30 Control circuits 50 H-bridge circuit

Claims

1. An H-bridge circuit (50) is provided, in which a first switch (SW1) is positioned between a high-potential section (10) having a predetermined potential and a low-potential section (11) having a lower potential than the high-potential section, a second switch (SW2) is positioned between the first switch and the low-potential section, a third switch (SW3) is positioned between the high-potential section and the low-potential section, and a fourth switch (SW4) is positioned between the third switch and the low-potential section. When the terminal to which the first switch and the second switch are commonly connected is designated as the first common connection terminal (40), and the terminal to which the third switch and the fourth switch are commonly connected is designated as the second common connection terminal (41), a wire (60a, 60b) is connected in series with the electrical load (2a) between the first common connection terminal and the second common connection terminal, A first control unit (S110) turns on the first switch and the fourth switch so that a first current flows from the high-potential section through the first switch, the electrical load, and the fourth switch to the low-potential section, A second control unit (S170) turns on the second switch and the third switch so that a second current flows from the high-potential section through the third switch, the electrical load, and the second switch to the low-potential section, A first temperature rise calculation unit (S130) calculates a first temperature rise, which is the amount of temperature rise in the electric wire that occurs as a result of the execution of the first control unit, based on the first current, A second temperature rise calculation unit (S130) calculates a second temperature rise, which is the rise in temperature of the electric wire caused by the execution of the second control unit, based on the second current, A wire temperature calculation unit (S130) calculates the temperature of the wire taking into account the first temperature rise range and the second temperature rise range, A control device equipped with the following features.

2. The control device according to claim 1, wherein the wire temperature calculation unit calculates the temperature of the wire by adding the first temperature rise and the second temperature rise.

3. When the first control unit is running, the wire temperature calculation unit calculates the temperature of the wire based on the first temperature rise range. The control device according to claim 1 or 2, wherein, when the second control unit is being executed, the wire temperature calculation unit calculates the temperature of the wire based on the second temperature rise range.

4. The system includes a third control unit (S190) that controls the first switch, the second switch, the third switch, and the fourth switch, respectively, to stop current from flowing from the high-potential section through the electrical load and the wires to the low-potential section. The control device according to claim 1 or 2, wherein the wire temperature calculation unit calculates the temperature of the wire, taking into account the heat dissipation from the wire to its surroundings during the execution of the third control unit.

5. A current determination unit (S140) determines whether or not an overcurrent is flowing through the wire by determining whether or not the temperature of the wire calculated by the wire temperature calculation unit is above a threshold, When the current determination unit determines that an overcurrent is flowing through the wire, a stop control unit (S150) controls the first switch, the second switch, the third switch, and the fourth switch, respectively, to stop the flow of the overcurrent through the wire. The control device according to claim 1 or 2, comprising:

6. A half-bridge circuit (53C) is provided, in which a fifth switch (SW5) is positioned between the high-potential section and the low-potential section, and a sixth switch (SW6) is positioned between the fifth switch and the low-potential section. When the aforementioned electrical load is designated as the first electrical load, the aforementioned wire as the first wire, and the terminal to which the fifth switch and the sixth switch are commonly connected is designated as the third common connection terminal (42), a second wire (61a, 61b) is connected in series with the second electrical load (2b) between the second common connection terminal and the third common connection terminal, A fourth control unit (S110) turns on the third switch and the sixth switch so that a third current flows from the high-potential section to the low-potential section through the third switch, the second electrical load, and the sixth switch, A fifth control unit (S170) turns on the fourth switch and the fifth switch so that a fourth current flows from the high-potential section through the fifth switch, the second electrical load, and the fourth switch to the low-potential section, A third temperature rise calculation unit (S130) calculates a third temperature rise, which is the amount of temperature rise in the second wire that occurs as a result of the execution of the fourth control unit, based on the third current, A fourth temperature rise calculation unit (S130) calculates a fourth temperature rise, which is the amount of temperature rise in the second wire that occurs as a result of the execution of the fifth control unit, based on the fourth current, When the wire temperature calculation unit is designated as the first wire temperature calculation unit, a second wire temperature calculation unit (S130) calculates the temperature of the second wire taking into account the third temperature rise range and the fourth temperature rise range, The control device according to claim 5, comprising:

7. The system includes a sixth control unit (S190) that controls the first switch, second switch, third switch, fourth switch, fifth switch, and sixth switch to stop current from flowing from the high-potential section through the second electrical load to the low-potential section, The control device according to claim 6, wherein the second wire temperature calculation unit calculates the temperature of the wire, taking into account the heat dissipation from the wire to its surroundings during the execution of the sixth control unit.

8. When the current determination unit is designated as the first current determination unit, the second current determination unit (S140) determines whether or not an overcurrent is flowing through the second wire by determining whether or not the temperature of the second wire calculated by the second wire temperature calculation unit is above a threshold, When the stop control unit is designated as the first stop control unit, the second current determination unit determines that an overcurrent is flowing through the second wire, and the second stop control unit (S150) controls the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch respectively to stop the overcurrent from flowing through the second wire. The control device according to claim 7, comprising:

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