control device

Abstract

A control device is provided. In step S110, the control circuit (30) turns on the semiconductor switches (SW1, SW4) continuously. In step S170, the control circuit (30) turns on the semiconductor switches (SW2, SW3). The control circuit (30) calculates a temperature rise amplitude (ΔTa) that is generated in association with the control processing of step 110, based on the current (Ia). The control circuit (30) calculates a temperature rise amplitude (ΔTb) that is generated in association with the execution of the control processing of step S170, based on the current (Ib). The control circuit (30) calculates the temperature of the electric wire (60a, 60b) taking into account the temperature rise amplitude (ΔTa) and the temperature rise amplitude (ΔTb). The control circuit (30) turns off the semiconductor switches (SW1 to SW4) when it is determined based on the temperature of the electric wire (60a, 60b) that an overcurrent is flowing in the electric wire (60a, 60b).

Description

Technical Field

[0001] This disclosure relates to control devices. Background Technology

[0002] Conventional solutions for overcurrent protection circuits include a semiconductor switch and control device positioned between the positive and negative terminals of a power supply (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 and the negative electrode of the semiconductor switch.

[0003] When the semiconductor switch is turned on, the load current flows from the positive terminal of the power supply through the semiconductor switch and the electrical load to the negative terminal 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 an overcurrent is flowing in the wire connecting the semiconductor switch and the electrical load. If an overcurrent is detected in the wire, the control device turns off the semiconductor switch. Thus, overcurrent protection is performed on each semiconductor switch to suppress overcurrent flowing in the wire and protect the wire from overcurrent effects.

[0004] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2013-85443 Summary of the Invention

[0005] Referring to the overcurrent protection circuit described above, the inventors have investigated overcurrent protection for wires connected to an electrical load in an H-bridge circuit comprising 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] Furthermore, hereinafter, the terminal commonly connecting the first semiconductor switch and the second semiconductor switch is designated as the first common connection terminal, and the terminal commonly connecting the third semiconductor switch and the fourth semiconductor switch is designated 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 disconnects the second and third semiconductor switches and connects 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] Therefore, the DC motor rotates its output shaft forward based on the first current. On the other hand, when the control circuit opens the first and fourth semiconductor switches and opens the third and second semiconductor switches, the 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. Therefore, the DC motor rotates its output shaft in reverse based on the second current.

[0008] When the DC motor rotates forward, the control circuit calculates the temperature of the wire based on a first current. The control circuit determines whether an overcurrent is flowing through the wire by checking if the wire temperature exceeds a threshold. When an overcurrent is detected in the wire during forward rotation of the DC motor, the control circuit disconnects the first, second, third, and fourth semiconductor switches. This suppresses overcurrent in the wire during forward rotation of the DC motor.

[0009] When the DC motor reverses, the control circuit calculates the temperature of the wire based on the second current. The control circuit determines whether an overcurrent is flowing through the wire by checking if the wire temperature is above a threshold. When the control circuit determines that an overcurrent is flowing through the wire during DC motor reversal, it disconnects the first, second, third, and fourth semiconductor switches. Therefore, overcurrent in the wire is suppressed during DC motor reversal.

[0010] When the DC motor rotates forward, the wires generate heat based on a first current. When the DC motor rotates in reverse, the wires generate heat based on a second current. Therefore, for example, the control circuit calculates the wire temperature independently when the DC motor rotates forward and in reverse. Thus, the control circuit calculates the wire temperature in a way that the heat generated from the wires when the DC motor rotates forward and the heat generated from the wires when the DC motor rotates in reverse are not added together. Consequently, the control circuit calculates a temperature lower than the actual temperature of the wires. Therefore, the control circuit cannot accurately calculate the wire temperature.

[0011] In view of the above, the purpose of this disclosure is to provide a control device for accurately calculating the temperature of a wire.

[0012] According to one aspect of this disclosure, a control device includes: an H-bridge circuit, wherein a first switch is disposed between a high-potential section having a predetermined potential and a low-potential section having a potential lower than the high-potential section; a second switch is disposed between the first switch and the low-potential section; a third switch is disposed between the high-potential section and the low-potential section; and a fourth switch is disposed between the third switch and the low-potential section; a wire, wherein a terminal commonly connecting the first switch and the second switch is designated as a first common connection terminal, and a terminal commonly connecting the third switch and the fourth switch is designated as a second common connection terminal, and the wire is connected in series with an electrical load between the first common connection terminal and the second common connection terminal; and a first control unit, which connects the first switch to the second common connection terminal. A switch and a fourth switch are configured to allow a first current to flow from a high potential section through the first switch, the electrical load, and the fourth switch to a low potential section; a second control unit is configured to connect a second switch and a third switch to allow a second current to flow from a high potential section through the third switch, the electrical load, and the second switch to a low potential section; a first rise amplitude calculation unit is configured to calculate, based on the first current, the rise amplitude of the wire temperature that increases with the execution of the first control unit, i.e., a first temperature rise amplitude; a second rise amplitude calculation unit is configured to calculate, based on the second current, the rise amplitude of the wire temperature that increases with the execution of the second control unit, i.e., a second temperature rise amplitude; and a wire temperature calculation unit is configured to calculate the wire temperature taking into account both the first and second temperature rise amplitudes.

[0013] Therefore, according to one aspect of this disclosure, the temperature of the wire can be calculated accurately. Furthermore, the parenthesized reference numerals used to indicate the correspondence between these constituent elements and the specific constituent elements described in the embodiments described later are an example. Attached Figure Description

[0014] Figure 1 This is a block diagram illustrating the circuit structure of the vehicle motor control device according to the first embodiment of this disclosure.

[0015] Figure 2 It means Figure 1 A flowchart detailing the motor control processing performed by the control circuit in the first embodiment.

[0016] Figure 3 This is a circuit diagram showing the circuit structure of the H-bridge circuit of the vehicle motor control device in the second embodiment of this disclosure.

[0017] Figure 4 It means Figure 3 The circuit diagram showing the connection relationship between the H-bridge circuit, current detection unit, temperature detection unit, and control circuit of the vehicle motor control device in the second embodiment. Detailed Implementation

[0018] Hereinafter, embodiments of the present disclosure will be described based on the accompanying drawings. Furthermore, in each of the following embodiments, for the sake of simplicity, the same reference numerals will be used to label the same or equivalent parts in the drawings.

[0019] (First Implementation) Figure 1 , Figure 2 This first embodiment of a vehicle motor control device 1, which applies the control device of the present disclosure, is shown. Figure 1 As shown, the vehicle motor control device 1 of this embodiment includes semiconductor switches SW1, SW2, SW3, and SW4, current detection units 20a and 20b, a temperature detection unit 21a, and a control circuit 30. Semiconductor switch SW1 is a first switch disposed between the positive electrode 10 of the DC power supply and semiconductor switch SW2. The positive electrode 10 is a high-potential section in the DC power supply having a predetermined positive potential.

[0020] The negative electrode 11 is a low-potential section in the DC power supply having a lower potential than the positive electrode 10. Semiconductor switch SW2 is a second switch disposed between semiconductor switch SW1 and the negative electrode 11. Furthermore, semiconductor switch SW3 is a third switch disposed between the positive electrode 10 and semiconductor switch SW4. Semiconductor switch SW4 is a fourth switch disposed between semiconductor switch SW3 and the negative electrode 11.

[0021] 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.

[0022] The control terminals of semiconductor switches SW1, SW2, SW3, and SW4 are respectively connected to the control circuit 30. As described later, semiconductor switches SW1, SW2, SW3, and SW4 constitute an H-bridge circuit 50 for controlling the DC motor 2a. As semiconductor switches SW1, SW2, SW3, and SW4 in this embodiment, various semiconductor elements such as metal oxide film semiconductor field-effect transistors, insulated gate bipolar transistors, and bipolar transistors are used.

[0023] Furthermore, for ease of explanation, the terminals commonly connected to semiconductor switches SW1 and SW2 are designated as common connection terminal 40, and the terminals commonly connected to semiconductor switches SW3 and SW4 are designated 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 respectively provided as input / output terminals of the vehicle motor control device 1. Input / output terminal 51 is positioned between common connection terminal 40 (i.e., the first common connection terminal) and the positive electrode of DC motor 2a. Input / output terminal 52 is positioned between common connection terminal 41 (i.e., the second common connection terminal) and the negative electrode of DC motor 2a. Wire 60a is a wire connecting input / output terminal 51 to the positive electrode of DC motor 2a.

[0024] Additionally, wire 60b connects the negative electrode of DC motor 2a to input / output terminal 52. For example, automotive wiring harnesses such as AVSS and CIVUS can be used as wires 60a and 60b. DC motor 2a is an electrical load that rotates its output shaft by being powered by a DC power supply. For example, DC motor 2a can be used as a door lock motor to drive a car's door lock mechanism, a wiper motor to drive a car's windshield wiper, or a washer motor to spray cleaning fluid.

[0025] As described below, the current detection unit 20a is a detection element used to detect the first current, i.e., current ia, flowing between the positive electrode 10 and the negative electrode 11 of the wires 60a and 60b when the semiconductor switches SW1 and SW4 are turned on. As the current detection unit 20a in this embodiment, a detection element (e.g., a differential amplifier circuit) is used to amplify and output the voltage between the input and output terminals of the semiconductor switch SW1, i.e., the inter-terminal voltage. The inter-terminal voltage is used to calculate the current ia flowing through the wires 60a and 60b as the current flowing between the input and output terminals of the semiconductor switch SW1.

[0026] As described below, the current detection unit 20b is a detection element used to detect the second current, i.e., current ib, flowing between the positive electrode 10 and the negative electrode 11 when the semiconductor switches SW2 and SW3 are turned on. As the current detection unit 20b in this embodiment, for example, a detection element (e.g., a differential amplifier circuit) is used to amplify and output the voltage between the input and output terminals of the semiconductor switch SW3, i.e., the inter-terminal voltage.

[0027] The inter-terminal voltage is used to calculate the current ib flowing through wires 60a and 60b as the current flowing between the input and output terminals of the semiconductor switch SW3. The temperature detection unit 21a is used to detect the ambient temperature of wires 60a and 60b. As the temperature detection unit 21a in this embodiment, various temperature detection units such as temperature detection diodes and thermistors can be used.

[0028] The control circuit 30 is a microcomputer equipped with a CPU, RAM, ROM, non-volatile rewritable memory, analog-to-digital converter, etc. Furthermore, when powered by a power source, the control circuit 30 executes a computer program recorded in a ROM or non-volatile rewritable memory, which is a non-removable physical recording medium. The control circuit 30 executes in conjunction with the execution of the computer program. Figure 2 The diagram shows various control processes, including motor control processing.

[0029] As described below, the motor control process controls the DC motor 2a and performs wire protection to suppress overcurrent flowing through wires 60a and 60b based on the currents ia and ib. Figure 2 This is a flowchart illustrating the detailed motor control processing in control circuit 30. Various constants used to calculate the temperatures of wires 60a and 60b are recorded along with the computer program in ROM and non-volatile rewritable memory. An analog-to-digital converter converts the output voltages of current detection units 20a and 20b and the output voltage of temperature detection unit 21a into digital data.

[0030] Next, refer to Figure 1 , Figure 2 The operation of the vehicle motor control device 1 of this embodiment will be explained.

[0031] First, the temperature detection unit 21a outputs an output voltage indicating the ambient temperature of wires 60a and 60b to the control circuit 30. The current detection unit 20a outputs an output voltage indicating the voltage between the terminals of semiconductor switch SW1 to the control circuit 30. The current detection unit 20b outputs an output voltage indicating the voltage between the terminals of semiconductor switch SW2 to the control circuit 30. The analog-to-digital converter of the control circuit 30 repeatedly converts the output voltages of the current detection unit 20a, current detection unit 20b, and temperature detection unit 21a into digital data.

[0032] Furthermore, for ease of explanation, the digital data representing the output voltage of the temperature detection unit 21a will be designated as temperature data. The digital data representing the output voltage of the current detection unit 20a will be designated as forward rotation voltage data. The digital data representing the output voltage of the current detection unit 20b will be designated as reverse rotation voltage data. The temperature data represents the ambient temperature of the wires 60a and 60b. The forward rotation voltage data represents the voltage between the terminals of the semiconductor switch SW1 when the DC motor 2a rotates forward. The reverse rotation voltage data represents the voltage between the terminals of the semiconductor switch SW3 when the DC motor 2a rotates in reverse.

[0033] In addition, the control circuit 30 is in accordance with Figure 2 The flowchart shows the start of motor control processing. Motor control processing is repeatedly executed by control circuit 30. First, in step S100, control circuit 30 determines whether it has received a forward rotation command from the electronic control device to make DC motor 2a rotate forward. At this time, if control circuit 30 determines that it has received a forward rotation command from the electronic control device, it determines "yes".

[0034] Subsequently, in step S110, the control circuit 30, acting as the first control unit, continues to keep semiconductor switches SW1 and SW4 on while semiconductor switches SW2 and SW3 are off. Therefore, current ia flows from the positive electrode 10 of the DC power supply through semiconductor switch SW1, input / output terminal 51, wire 60a, DC motor 2a, wire 60b, input / output terminal 52, and semiconductor switch SW4 to the negative electrode 11. Consequently, the DC motor 2a rotates its output shaft forward using the power supplied from the DC power supply.

[0035] At this time, wires 60a and 60b heat up due to the current ia. Therefore, the temperature of wires 60a and 60b rises above their initial temperature T0. Next, in step S120, the control circuit 30 calculates the current ia [A] by dividing the voltage between the terminals of semiconductor switch SW1 by the on-resistance of semiconductor switch SW1 based on the forward rotation voltage data. The current ia is used as the first current flowing through the conductors of wires 60a and 60b when the DC motor 2a rotates forward. The on-resistance is the resistance value between the input and output terminals of semiconductor switch SW1 when semiconductor switch SW1 is in the on state. The on-resistance is pre-recorded in ROM or non-volatile rewritable memory.

[0036] 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 above. Temperature T1 is the temperature calculated during the temperature calculation process in step S130, which is executed for the first time after the start of the motor control process. Hereinafter, the temperatures of wires 60a and 60b will also be referred to as wire temperatures. Specifically, the control circuit 30, acting as a first rise amplitude calculation unit, substitutes the current ia, constants r, R, C, and time T into the formula in mathematical equation 1 to calculate the temperature rise amplitude ΔTa.

[0037] [Mathematical Expression 1] Formula 1 is a mathematical expression used to calculate the temperature rise ΔTa of wires 60a and 60b when semiconductor switches SW1 and SW4 are turned on. The temperature rise ΔTa is the rate of temperature increase of the wires during the period when semiconductor switches SW1 and SW4 are continuously turned on (i.e., the first temperature rise). The constant r is the resistance value [Ω] of the conductors of wires 60a and 60b. The constant R is the thermal resistance [°C / W] of the conductors of wires 60a and 60b.

[0038] Additionally, constant C represents the thermal capacity of the conductors in wires 60a and 60b. The unit of thermal capacity is [J / ℃] or [W·sec / ℃]. Time T is the period during which semiconductor switches SW1 and SW4 remain on while semiconductor switches SW2 and SW3 are off. Furthermore, constants r, R, and C are pre-recorded in ROM or non-volatile rewritable memory. Moreover, since constant r corresponds to the characteristic change caused by temperature, a value obtained by correcting the value recorded in ROM or non-volatile rewritable memory based on ambient temperature, etc., can be used as constant r.

[0039] In addition, in step S130 above, the control circuit 30 calculates the ambient temperature of wires 60a and 60b based on temperature data, and sets the ambient temperature of wires 60a and 60b as the initial temperature T0 of wires 60a and 60b. Furthermore, as shown in mathematical formula 2, the control circuit 30 adds the temperature rise ΔTa to the initial temperature T0 of wires 60a and 60b to calculate the temperature T1 of wires 60a and 60b.

[0040] [Mathematical Expression 2] Thus, the control circuit 30 calculates the temperature T1 of wires 60a and 60b using formulas 1 and 2. If an overcurrent flows through wires 60a and 60b, the temperature T1 of wires 60a and 60b is abnormally high. Therefore, in step S140, the control circuit 30, acting as a first current determination unit, determines whether the temperature T1 of wires 60a and 60b is above a threshold, thereby determining whether an overcurrent has flowed through wires 60a and 60b.

[0041] At this point, in the next step S140, the control circuit 30 determines "no" because the temperature T1 of wires 60a and 60b is less than the threshold value, which is considered as no current flowing through wires 60a and 60b. Then, when the control circuit 30 receives a reversal command from the electronic control device to reverse the DC motor 2a, it determines "no" in step S100 and "yes" in step S160. Subsequently, in step S170, the control circuit 30, acting as a second control unit, disconnects semiconductor switches SW1 and SW4 and keeps semiconductor switches SW2 and SW3 continuously connected.

[0042] Therefore, current ib flows from the positive electrode 10 of the DC power supply 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. Subsequently, the DC motor 2a reverses its output shaft using the power supplied from the DC power supply. At this time, wires 60a and 60b heat up due to current ib. Therefore, the temperature of wires 60a and 60b is higher than their temperature T1.

[0043] Next, in step S180, the control circuit 30 calculates the current ib [A] by dividing the inter-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 a second current flowing through the conductors of wires 60a and 60b when the DC motor 2a reverses. Furthermore, the on-resistance is the resistance value between the input and output terminals of the semiconductor switch SW3 when it is in the on state. The on-resistance is pre-recorded in ROM or non-volatile rewritable memory.

[0044] Next, in step S130, the control circuit 30 calculates the temperature T2 of wires 60a and 60b based on the current ib calculated in step S180 above. 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 rise amplitude calculation unit, substitutes the current ib, constants r, R, C, and time T into the formula in mathematical equation 3 to calculate the temperature rise amplitude ΔTb (i.e., the second temperature rise amplitude).

[0045] [Mathematical Expression 3] Formula 3 is a mathematical expression used to calculate the temperature rise ΔTb of wires 60a and 60b when semiconductor switches SW3 and SW2 are turned on. The temperature rise ΔTb is the increase in wire temperature during the period when semiconductor switches SW3 and SW2 are continuously turned on. Time T is the period during which semiconductor switches SW3 and SW2 are continuously turned on. Furthermore, in step S130 above, the control circuit 30, as shown in Formula 4, adds the temperature T1 of wires 60a and 60b to the temperature rise ΔTb to calculate the temperature T2 of wires 60a and 60b.

[0046] [Mathematical Expression 4] Thus, the control circuit 30 uses formulas 3 and 4 to calculate the temperature T2 of wires 60a and 60b. Subsequently, in step S140, if the temperature T2 of wires 60a and 60b is less than the threshold, the control circuit 30 considers that no current has flowed through wires 60a and 60b and determines "no".

[0047] Subsequently, upon receiving a stop command from the electronic control device to stop the DC motor 2a, the control circuit 30 determines "No" in step S100 and "No" again in step S160. Then, in step S190, the control circuit 30, acting as a third control unit, continuously disconnects the semiconductor switches SW1, SW2, SW3, and SW4. Therefore, the current 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 is stopped. Consequently, the DC motor 2a is stopped from receiving power from the DC power supply, and thus the output shaft stops.

[0048] At this time, wires 60a and 60b dissipate heat to their surroundings. Consequently, the temperature of wires 60a and 60b decreases compared to temperature T2 and approaches the temperature of their surroundings. Therefore, in step S200, the control circuit 30 calculates the current i flowing through wires 60a and 60b in order to calculate the temperature of wires 60a and 60b. For example, similarly to step S120 above, the control circuit 30 divides the voltage between the terminals of the semiconductor switch SW1 by the on-resistance of the semiconductor switch SW1 to calculate the current i. At this time, the output voltage of each of the current detection units 20a and 20b becomes zero [V]. Therefore, the current i flowing through the conductors of wires 60a and 60b becomes zero [A].

[0049] 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 their 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 the motor control process. 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 substitutes the ambient temperature Ts, current i, constant r, constant R, constant C, and time T into the equation in mathematical formula 5 to calculate the temperature T3 of wires 60a and 60b.

[0050] The current i, constant r, constant R, and constant C are as described above. Time T is the period during which semiconductor switches SW1, SW2, SW3, and SW4 are continuously open. As described above, the current i is zero. Therefore, the temperature T3 of wires 60a and 60b becomes the same as the ambient temperature Ts of wires 60a and 60b.

[0051] [Mathematical Expression 5] Next, in step S140, if the temperature T3 of wires 60a and 60b is less than the threshold, the control circuit 30 considers that no current has flowed through wires 60a and 60b and determines "No". Afterwards, whenever the control circuit 30 determines "No" in step S140 because the temperature of wires 60a and 60b is less than 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.

[0052] Then, in the nth step S100, the control circuit 30 determines "No" upon receiving a stop command from the electronic control device, and determines "No" again in step S160. n is an integer greater than or equal to 4. Subsequently, in the next step S170, the control circuit 30 disconnects the semiconductor switches SW1, SW2, SW3, and SW4 respectively. Therefore, the current flowing between the positive electrode 10 and the negative electrode 11 of the DC power supply, and in the DC motor 2a and the wires 60a and 60b, stops.

[0053] Subsequently, DC motor 2a stops its output shaft. At this time, wires 60a and 60b dissipate heat to their surroundings. Therefore, the temperature of wires 60a and 60b is higher than the temperature of wires 60a and 60b by T. n-1 It decreases and approaches the surrounding temperature Ts. Here, temperature T n-1 The temperature of wires 60a and 60b is calculated by the control circuit 30 in step 130 during the (n-1)th execution.

[0054] Next, in step S200, the control circuit 30 calculates zero [A] as the current i flowing through wires 60a and 60b in the same manner as described above. Then, in step S130, the control circuit 30 calculates the ambient temperature Ts of 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 calculate the temperature T of wires 60a and 60b. n .

[0055] Temperature T of wires 60a and 60b n The temperature becomes the same as the ambient temperature Ts of wires 60a and 60b. Therefore, it is possible to calculate the temperature T of wires 60a and 60b, taking into account the heat dissipation from the conductors of wires 60a and 60b to their surroundings. n .

[0056] [Mathematical Expression 6] Subsequently, in step S140, the control circuit 30 controls the temperature T of the wires 60a and 60b. n If the current is less than the threshold, it is considered that no current has flowed through wires 60a and 60b and is judged as "no".

[0057] Next, in step S100 (the (n+1)th step), the control circuit 30 determines "yes" upon receiving a forward rotation command from the electronic control device. Subsequently, in step S110, the control circuit 30 keeps semiconductor switches SW1 and SW4 continuously on while semiconductor switches SW2 and SW3 are off. Therefore, current ia flows from the positive electrode 10 of the DC power supply through semiconductor switch SW1, input / output terminal 51, wire 60a, DC motor 2a, wire 60b, and input / output terminal 52 to the negative electrode 11. Consequently, the DC motor 2a rotates its output shaft forward using the power supplied from the DC power supply. Consequently, wires 60a and 60b heat up due to the current ia. At this time, the temperature of wires 60a and 60b becomes higher than the temperature T of wires 60a and 60b. n high.

[0058] Next, in step S120, the control circuit 30 calculates the current ia based on the forward voltage data. Then, in step S130, the control circuit 30 calculates the temperature T of wires 60a and 60b based on the current ia calculated in step S120. n+1 Temperature T n+1 The temperature is calculated in step S130, which is executed for the (n+1)th time after the start of the motor control process. Specifically, the control circuit 30 substitutes the current ia, constant r, R, C, and time T into the formula in mathematical equation 7 to calculate the temperature rise ΔT. n+1 .

[0059] [Mathematical Expression 7] Equation 7 is used to calculate the temperature rise ΔT of wires 60a and 60b when semiconductor switches SW1 and SW4 are turned on. n+1 The mathematical formula for the temperature rise ΔT. n+1 This refers to the temperature rise of the wires during the period when semiconductor switches SW1 and SW4 are continuously on. Time T is the period during which semiconductor switches SW1 and SW4 are continuously on in step S110. Furthermore, in step S130 above, the control circuit 30, as shown in equation 8, controls the temperature rise ΔT. n+1 Temperature T of wires 60a and 60b n The temperatures T of wires 60a and 60b are calculated by adding them together. n+1 .

[0060] [Mathematical Expression 8] Next, in step S140, the control circuit 30 controls the temperature T of the wires 60a and 60b. n+1 If the current is less than the threshold, it is considered that no current has flowed through the wires 60a and 60b and is determined as "No". Then, when the control circuit 30 receives a reversal command from the electronic control device, it determines as "No" in step S100 at the (n+2)th time and as "Yes" in step S160.

[0061] Subsequently, in step S170, the control circuit 30 disconnects semiconductor switches SW1 and SW4 and connects semiconductor switches SW2 and SW3. Therefore, 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 using power supplied from the DC power source.

[0062] 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 wires 60a and 60b based on the current ib. n+2 The temperature T n+2 The temperature is calculated in step S130, which is executed for the (n+2)th time after the start of the motor control process. Specifically, the control circuit 30 substitutes the current ib, constant r, constant R, constant C, and time T into the formula in mathematical equation 9 to calculate the temperature rise ΔT. n+2 .

[0063] [Mathematical Expression 9] Equation 9 is used to calculate the temperature rise ΔT of wires 60a and 60b when semiconductor switches SW3 and SW2 are turned on. n+2 The mathematical formula for the temperature rise ΔT. n+2 This refers to the increase in wire temperature during the period when semiconductor switches SW3 and SW2 are continuously on. Furthermore, time T is the period during which semiconductor switches SW3 and SW2 are continuously on. In addition, in step S130 above, the control circuit 30, as shown in equation 10, sets the temperature T... n+1 and the temperature rise ΔT n+2 Add them together and calculate the temperature T of wires 60a and 60b. n+2 .

[0064] [Mathematical Expression 10] Next, in step S140, the control circuit 30 controls the temperature T of the wires 60a and 60b. n+2 When the current exceeds the threshold, it is considered that an overcurrent is flowing through wires 60a and 60b, and the condition is determined to be "yes". Subsequently, in step S150, as the first stop control unit, semiconductor switches SW1, SW2, SW3, and SW4 are turned off. As a result, the overcurrent flowing between the positive electrode 10 and the negative electrode 11 through wires 60a and 60b can be stopped.

[0065] According to the embodiment described above, the vehicle motor control device 1 includes an H-bridge circuit 50 with semiconductor switches SW1, SW2, SW3, and SW4, wires 60a and 60b, and a control circuit 30. Semiconductor switch SW1 is disposed between the positive electrode 10 of the DC power supply and semiconductor switch SW2. Semiconductor switch SW2 is disposed between semiconductor switch SW1 and the negative electrode 11. Semiconductor switch SW3 is disposed between the positive electrode 10 and semiconductor switch SW4. Semiconductor switch SW4 is disposed between semiconductor switch SW3 and the negative electrode 11.

[0066] Wires 60a and 60b are connected in series with DC motor 2a between common connection terminals 40 and 41. Common connection terminal 40 is the first common connection terminal commonly connected to semiconductor switches SW1 and SW2. Common connection terminal 41 is the second common connection terminal commonly connected to semiconductor switches SW3 and SW4. In step S110, the control circuit 30 keeps semiconductor switches SW1 and SW4 continuously connected while semiconductor switches SW2 and SW3 are turned off. As a result, current ia flows from the positive electrode 10 through semiconductor switch SW1, input / output terminal 51, wire 60a, DC motor 2a, wire 60b, input / output terminal 52, and semiconductor switch SW4 to the negative electrode 11.

[0067] In step S170, the control circuit 30 turns on semiconductor switches SW2 and SW3 while semiconductor switches SW1 and SW4 are off. 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. In step S130, the control circuit 30 calculates the temperature rise ΔTa of wires 60a and 60b, which has increased due to the control processing in step 110, based on the current ia. In step S130, the control circuit 30 calculates the temperature rise ΔTb of wires 60a and 60b, which has increased due to the execution of the control processing in step S170, based on the current ib.

[0068] In step S130, the control circuit 30 calculates the temperatures of wires 60a and 60b, taking into account the temperature rise amplitudes ΔTa and ΔTb. For example, in step S130, the control circuit 30 adds the temperature rise amplitudes ΔTa and ΔTb to calculate the temperatures of wires 60a and 60b. 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 in reverse. Therefore, the temperatures of wires 60a and 60b can be calculated accurately. According to this embodiment with such a configuration, the following (α) and (β) effects can be obtained.

[0069] (α) Upon receiving a stop command from the electronic control device for the DC motor 2a, the control circuit 30 disconnects semiconductor switches SW1, SW2, SW3, and SW4 in step S190. This stops the flow of current between the positive electrode 10 and the negative electrode 11 through the DC motor 2a and wires 60a and 60b. In step S130, the control circuit 30 calculates the temperatures of wires 60a and 60b during the control processing of step S190, taking into account the heat dissipation from the wires 60a and 60b to their surroundings. Therefore, the temperatures of wires 60a and 60b when the DC motor 2a stops can be calculated more accurately.

[0070] (β) In step S150, the control circuit 30 determines whether the temperatures of wires 60a and 60b calculated in the temperature calculation process of step S130 are above a threshold, and thereby determines whether an overcurrent flows through wires 60a and 60b. If the control circuit 30 determines in step S150 that an overcurrent is flowing through wires 60a and 60b, it disconnects semiconductor switches SW1, SW2, SW3, and SW4 to stop the overcurrent from flowing through wires 60a and 60b. Therefore, overcurrent protection for wires 60a and 60b can be appropriately implemented.

[0071] (Second Implementation) In the first embodiment described above, a vehicle motor control device for controlling a DC motor 2a was explained. However, instead, refer to... Figure 3 , Figure 4 This second embodiment describes a vehicle motor control device for controlling DC motors 2a, 2b, and 2c. Figure 3 This is a diagram showing the circuit structure of the vehicle motor control device 50A according to this embodiment. Figure 4 This is a circuit diagram showing the connection relationship of circuit 50A, current detection units 20x, 20y, 20z, temperature detection units 21a, 21b, 21c, and control circuit 30 in a vehicle motor control device.

[0072] like Figure 3 As shown, the vehicle motor control device includes a circuit 50A and wires 60a, 60b, 61a, 61b, 62a, and 62b, replacing the H-bridge circuit 50. Circuit 50A includes half-bridge circuits 53A, 53B, and 53C. (As shown...) Figure 4 As shown, the vehicle motor control device includes current detection units 20x, 20y, 20z, temperature detection units 21a, 21b, 21c, and a control circuit 30.

[0073] 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 at the negative electrode 11. Half-bridge circuit 53B, together with half-bridge circuit 53A, forms 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 at the negative electrode 11.

[0074] The half-bridge circuit 53C includes semiconductor switches SW5 and SW6. Semiconductor switch SW5 is the fifth switch, with its input terminal 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 at the negative electrode 11. Hereinafter, for ease of explanation, the terminal commonly connected to semiconductor switches SW1 and SW2 will be designated as common connection terminal 40, the terminal commonly connected to semiconductor switches SW3 and SW4 will be designated as common connection terminal 41, and the terminal commonly connected to semiconductor switches SW5 and SW6 will be designated as common connection terminal 42.

[0075] Wires 60a and 60b and a DC motor 2a are connected in series between common connection terminals 40 and 41. Wire 60a is disposed between common connection terminal 40 and the positive electrode of DC motor 2a. Wire 60b is disposed between the negative electrode of DC motor 2a and common connection terminal 41. Wires (i.e., second wires) 61a and 61b and DC motor 2b are connected in series between common connection terminal 41 and common connection terminal (i.e., third common connection terminal) 42.

[0076] A wire 61a is disposed between the common connection terminal 41 and the positive electrode of the DC motor 2b. A wire 61b is disposed between the negative electrode of the DC motor 2b and the common connection terminal 42. Wires 62a and 62b and the DC motor 2c are connected in series between the common connection terminals 42 and 40. A wire 62a is disposed between the common connection terminal 42 and the positive electrode of the DC motor 2c. A wire 62b is disposed between the negative electrode of the DC motor 2c and the common connection terminal 40.

[0077] The current detection unit 20x is used to detect the current ix flowing through the wires 60a and 60b. As the current detection unit 20x in this embodiment, for example, a detection element is used to detect the voltage between the input and output terminals of either semiconductor switch SW1 or semiconductor switch SW3, i.e., the inter-terminal voltage. The current ix is ​​the current flowing through the wires 60a and 60b between the common connection terminals 40 and 41.

[0078] The current detection unit 20y is used to detect the current iy flowing through the wires 61a and 61b. As the current detection unit 20y in this embodiment, for example, a detection element is used to detect the voltage between the input and output terminals of either semiconductor switch SW3 or semiconductor switch SW5, i.e., the inter-terminal voltage. The current iy is the current flowing through the wires 61a and 61b between the common connection terminals 41 and 42.

[0079] The current detection unit 20z is used to detect the current iz flowing through the wires 62a and 62b. As the current detection unit 20z in this embodiment, for example, a detection element is used to detect the voltage between the input and output terminals of either semiconductor switch SW5 or semiconductor switch SW1, i.e., the inter-terminal voltage. The current iz is the current flowing through the wires 62a and 62b between the common connection terminals 42 and 40. Furthermore, the current detection units 20x, 20y, and 20z are each composed of the same detection element as the current detection unit 20a in the first embodiment described above.

[0080] Furthermore, temperature detection unit 21a is a temperature sensor that detects the ambient temperature of wires 60a and 60b. Temperature detection unit 21b is a temperature sensor that detects the ambient temperature of wires 61a and 61b. Temperature detection unit 21c is a temperature sensor that detects the ambient temperature of wires 62a and 62b. Temperature detection units 21a, 21b, and 21c are each composed of the same temperature sensor as temperature detection unit 21a in the first embodiment described above.

[0081] The control circuit 30 is a microcomputer equipped with a CPU, RAM, ROM, non-volatile rewritable memory, analog-to-digital converter, etc. When powered by a power source, the control circuit 30 executes a computer program recorded in a ROM or non-volatile rewritable memory, which is a non-removable physical recording medium. The control circuit 30 executes in conjunction with the execution of the computer program. Figure 2 Motor control processing and other control processes.

[0082] The motor control processing controls DC motors 2a, 2b, and 2c, and performs wire protection based on currents ix, iy, and iz to suppress overcurrent flowing through wires 60a, 60b, 61a, 61b, 62a, and 62b. Various constants used to calculate the temperatures of wires 60a, 60b, 61a, 61b, 62a, and 62b are recorded along with the computer program in ROM and non-volatile rewritable memory. An analog-to-digital converter converts the output voltages of current sensing units 20x, 20y, and 20z, and the output voltages of temperature sensing units 21a, 21b, and 21c, into digital signals.

[0083] Next, refer to Figure 2 The operation of the vehicle motor control device 1 according to this embodiment will be explained. The control circuit 30 of this embodiment operates according to each DC motor... Figure 2 The flowchart repeatedly executes motor control processing. First, temperature detection unit 21a outputs an output voltage indicating the ambient temperature of wires 60a and 60b to control circuit 30. Temperature detection unit 21b outputs an output voltage indicating the ambient temperature of wires 61a and 61b to control circuit 30. Temperature detection unit 21c outputs an output voltage indicating the ambient temperature of wires 62a and 62b to control circuit 30.

[0084] Current detection unit 20x outputs an output voltage representing the inter-terminal voltage of semiconductor switch SW1 and an output voltage representing the inter-terminal voltage of semiconductor switch SW3 to control circuit 30. Current detection unit 20y outputs an output voltage representing the inter-terminal voltage of semiconductor switch SW3 and an output voltage representing the inter-terminal voltage of semiconductor switch SW5 to control circuit 30. Current detection unit 20z outputs an output voltage representing the inter-terminal voltage of semiconductor switch SW5 and an output voltage representing the inter-terminal voltage of semiconductor switch SW1 to control circuit 30.

[0085] The analog-to-digital converter in control circuit 30 repeatedly converts the output voltages of current detection units 20x, 20y, 20z and temperature detection units 21a, 21b, 21c into digital data. For ease of explanation, the digital data representing the output voltage of temperature detection unit 21a will be designated as the first temperature data. The first temperature data represents the ambient temperature of wires 60a and 60b. The digital data representing the output voltage of temperature detection unit 21b will be designated as the second temperature data. The second temperature data represents the ambient temperature of wires 61a and 61b. The digital data representing the output voltage of temperature detection unit 21c will be designated as the third temperature data. The third temperature data represents the ambient temperature of wires 62a and 62b.

[0086] The digital data representing the output voltage of the current detection unit 20x when semiconductor switches SW1 and SW4 are turned on is set as the first forward rotation voltage data. The first forward rotation voltage data is the digital data representing the voltage between the terminals of semiconductor switch SW1 when the DC motor 2a is rotating forward. The digital data representing the output voltage of the current detection unit 20y when semiconductor switches SW3 and SW6 are turned on is set as the second forward rotation voltage data.

[0087] The second forward rotation voltage data is digital data representing the voltage between the terminals of semiconductor switch SW3 when DC motor 2b rotates forward. The digital data representing the output voltage of current detection unit 20z when semiconductor switches SW5 and SW2 are turned on is set as the third forward rotation voltage data. The third forward rotation voltage data is digital data representing the voltage between the terminals of semiconductor switch SW5 when DC motor 2c rotates forward.

[0088] The digital data representing the output voltage of the current detection unit 20x when semiconductor switches SW3 and SW2 are turned on is set as the first reverse voltage data. The first reverse voltage data is the digital data representing the voltage between the terminals of semiconductor switch SW3 when the DC motor 2a is reversed. The digital data representing the output voltage of the current detection unit 20y when semiconductor switches SW5 and SW4 are turned on is set as the second reverse voltage data.

[0089] The second reverse voltage data is digital data representing the voltage between the terminals of semiconductor switch SW5 when the DC motor 2b reverses. The digital data representing the output voltage of the current detection unit 20z when semiconductor switches SW1 and SW6 are turned on is set as the third reverse voltage data. The third reverse voltage data is digital data representing the voltage between the terminals of semiconductor switch SW1 when the DC motor 2c reverses. 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 steps S100 to S200 in the same manner as in the first embodiment described above.

[0090] At this time, in step S110, while semiconductor switches SW2, SW3, SW5, and SW6 are open, control circuit 30 keeps semiconductor switches SW1 and SW4 continuously open. As a result, current ix flows from the positive electrode 10 through semiconductor switch SW1, wire 60a, DC motor 2a, wire 60b, and semiconductor switch SW4 to the negative electrode 11. In step S120, control circuit 30 calculates current ix [A] based on the first forward voltage data, similar to the current ia described above. In step S130, 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.

[0091] In step S170, while semiconductor switches SW1, SW4, SW5, and SW6 are turned off, the control circuit 30 keeps semiconductor switches SW2 and SW3 continuously turned on. As a result, 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 calculates the current ix [A] based on the first reverse voltage data, similar to the calculation of 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.

[0092] In step S190, the control circuit 30 continuously disconnects semiconductor switches SW1, SW2, SW3, SW4, SW5, and SW6. Therefore, current stops flowing between the positive and negative electrodes 11 of the DC power supply through the DC motor 2a and wires 60a and 60b. Next, in step S200, the control circuit 30 calculates the current i flowing through wires 60a and 60b (e.g., zero) to calculate the temperature of wires 60a and 60b. Furthermore, in step S130, the control circuit 30 calculates the temperature of wires 60a and 60b based on the current i calculated in step S200 and the first temperature data.

[0093] Therefore, the control circuit 30 determines whether an overcurrent flows through the wires 60a and 60b by judging whether the calculated temperatures of the wires 60a and 60b are above a threshold. When the control circuit 30 determines that an overcurrent has flowed in the wires 60a and 60b, it disconnects the semiconductor switches SW1, SW2, SW3, SW4, SW5, and SW6 to stop the overcurrent from flowing in the wires 60a and 60b.

[0094] 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 it has received a forward rotation command from the electronic control device to make the DC motor 2b rotate forward. In step S110, the control circuit 30, acting as the fourth control unit, turns on the semiconductor switches SW3 and SW6 while the semiconductor switches SW1, SW2, SW4, and SW5 are turned off.

[0095] Therefore, the current iy (i.e., the third current) flows from the positive electrode 10 through the semiconductor switch SW3, wire 61a, DC motor 2b, wire 61b, and semiconductor switch SW6 to the negative electrode 11. In step S120, the control circuit 30 calculates the current iy [A] based on the second forward voltage data, similar to the current ia described above. In step S130, the control circuit 30 calculates the temperatures of wires 61a and 61b based on the current iy calculated in step S120 and the second temperature data.

[0096] In step S170, the control circuit 30, acting as the fifth control unit, keeps semiconductor switches SW4 and SW5 continuously on while semiconductor switches SW1, SW2, SW3, and SW6 are off. As a result, current iy flows from the positive electrode 10 through semiconductor switch SW5, wire 61b, DC motor 2b, wire 61a, and semiconductor switch SW4 to the negative electrode 11. In step S180, the control circuit 30 calculates the current iy [A] based on the second reverse voltage data, similar to the calculation of 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.

[0097] In step S190, the control circuit 30 disconnects the semiconductor switches SW1, SW2, SW3, SW4, SW5, and SW6. In step S200, the control circuit 30 calculates the current i flowing through wires 61a and 61b when the semiconductor switches SW1, SW2, SW3, SW4, SW5, and SW6 are disconnected (e.g., zero). Next, in step S130, the temperatures of wires 61a and 61b are calculated based on the current i calculated in step S200 and the second temperature data.

[0098] Therefore, the control circuit 30 determines whether an overcurrent flows through the wires 62a and 62b by judging whether the calculated temperatures of the wires 62a and 62b are above a threshold. When the control circuit 30 determines that an overcurrent has flowed in the wires 62a and 62b, it opens the semiconductor switches SW1, SW2, SW3, SW4, SW5, and SW6 to stop the overcurrent from flowing in the wires 62a and 62b.

[0099] 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 it has received a forward rotation command from the electronic control device to make the DC motor 2c rotate forward. In step S110, the control circuit 30 turns on the semiconductor switches SW2 and SW5 while the semiconductor switches SW1, SW3, SW4, and SW6 are turned off.

[0100] Therefore, 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 calculates the current iz [A] based on the third forward 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.

[0101] In step S170, while semiconductor switches SW2, SW3, SW4, and SW5 are turned off, the control circuit 30 keeps semiconductor switches SW1 and SW6 continuously turned on. As a result, current iz flows from the positive electrode 10 through semiconductor switch SW1, wire 62b, DC motor 2c, wire 62a, and semiconductor switch SW6 to the negative electrode 11. In step S180, the control circuit 30 calculates the current iz [A] based on the third reverse voltage data, similar to the calculation of current ib.

[0102] In step S130, the control circuit 30 calculates the temperatures of wires 62a and 62b based on the current iz calculated in step S180 and the third temperature data. Additionally, in step S190, the control circuit 30 disconnects semiconductor switches SW1, SW2, SW3, SW4, SW5, and SW6. In step S200, the control circuit 30 calculates the current i flowing through wires 62a and 62b when semiconductor switches SW1, SW2, SW3, SW4, SW5, and SW6 are disconnected (e.g., zero). Next, in step S130, the temperatures of wires 62a and 62b are calculated based on the current i calculated in step S200 and the third temperature data.

[0103] Therefore, the control circuit 30 determines whether an overcurrent flows through the wires 62a and 62b by judging whether the calculated temperatures of the wires 62a and 62b are above a threshold. When the control circuit 30 determines that an overcurrent has flowed in the wires 62a and 62b and deems it "yes", it opens the semiconductor switches SW1, SW2, SW3, SW4, SW5, and SW6 to stop the overcurrent from flowing in the wires 62a and 62b.

[0104] 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 disconnects semiconductor switches SW2, SW3, SW5, and SW6, and connects semiconductor switches SW1 and SW4. As a result, current Ix flows from the positive electrode 10 through semiconductor switch SW1, wire 60a, DC motor 2a (i.e., the first electrical load), wire 60b, and semiconductor switch SW4 to the negative electrode 11. 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 of wires 60a and 60b (i.e., the first wire) that has increased due to the execution of the control processing in step S110, based on the current Ix.

[0105] In step S170, the control circuit 30 disconnects semiconductor switches SW1, SW4, SW5, and SW6, and connects semiconductor switches SW2 and SW3. As a result, 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.

[0106] In step S130, control circuit 30 calculates the temperature rise magnitude ΔTb of wires 60a and 60b, which increases as the control processing in step S170 is executed, based on the current Ix. Therefore, as a first wire temperature calculation unit, control circuit 30 calculates the temperatures of wires 60a and 60b, taking into account both the heating of wires 60a and 60b when the DC motor 2a rotates forward and when the DC motor 2a rotates in reverse. Thus, the temperatures of wires 60a and 60b can be calculated accurately.

[0107] Upon receiving a stop command from the electronic control device for the DC motor 2a, the control circuit 30 disconnects semiconductor switches SW1, SW2, SW3, SW4, SW5, and SW6 in step S190. This stops the flow of current from the positive electrode 10 through wires 60a, the DC motor 2a, and wires 60b to the negative electrode 11. In step S130, the control circuit 30 calculates the temperatures of wires 60a and 60b during the control processing of step S190, taking into account the heat dissipation from the wires 60a and 60b to their surroundings. Therefore, the temperatures of wires 60a and 60b when the DC motor 2a stops can be calculated more accurately.

[0108] The control circuit 30 performs motor control processing on the DC motor 2b. In step S110, the control circuit 30 disconnects semiconductor switches SW1, SW2, SW4, and SW6, and connects semiconductor switches SW3 and SW6. As a result, 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.

[0109] In step S120, the control circuit 30 detects the current Iy flowing through wires 61a and 61b. In step S130, the control circuit 30, acting as a third rise amplitude calculation unit, calculates the temperature rise amplitude ΔTa based on the current Iy (i.e., the fourth current). The temperature rise amplitude ΔTa is the temperature rise amplitude (i.e., the third temperature rise amplitude) of the wires 61a and 61b that has increased due to the execution of the control processing in step S110.

[0110] In step S170, the control circuit 30 disconnects semiconductor switches SW1, SW2, SW3, and SW6, and connects semiconductor switches SW4 and SW5. As a result, current Iy flows from the positive electrode 10 through semiconductor switch SW5, wire 61b, DC motor 2b (i.e., the second electrical load), wire 61a, and semiconductor switch SW4 to the negative electrode 11. In step S180, the control circuit 30 detects the current Iy flowing through wires 61a and 61b.

[0111] In step S130, the control circuit 30, acting as a fourth temperature rise calculation unit, calculates the temperature rise magnitude ΔTb based on the current Iy (i.e., the fifth current). The temperature rise magnitude ΔTb is the temperature rise magnitude (i.e., the fourth temperature rise magnitude) of the wires 61a and 61b that increases as the control processing in step S170 is executed. Therefore, the control circuit 30, acting as a second wire temperature calculation unit, calculates the temperatures of the wires 61a and 61b, taking into account the heating of the wires 61a and 61b when the DC motor 2a rotates forward and when the DC motor 2b rotates in reverse. Therefore, the temperatures of the wires 61a and 61b can be calculated accurately.

[0112] Upon receiving a stop command from the electronic control device, the control circuit 30, as the sixth control unit, disconnects semiconductor switches SW1, SW2, SW3, SW4, SW5, and SW6 in step S190. This stops the flow of current from the positive electrode 10 through the DC motor 2b and wires 61a and 61b to the negative electrode 11. In step S130, the control circuit 30 calculates the temperature of wires 61a and 61b, which dissipates heat to their surroundings during the control processing in step S190. Therefore, the temperature of wires 61a and 61b when the DC motor 2b stops can be calculated more accurately.

[0113] Control circuit 30 performs motor control processing on DC motor 2c. In step S110, control circuit 30 disconnects semiconductor switches SW2, SW3, SW4, and SW5, and connects semiconductor switches SW5 and SW2. As a result, 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, control circuit 30 detects the current Iz flowing through wires 62a and 62b. In step S130, control circuit 30 calculates the temperature rise ΔTa of wires 62a and 62b, which has increased due to the execution of the control processing in step S110, based on the current Iz.

[0114] In step S170, the control circuit 30 disconnects semiconductor switches SW1, SW2, SW3, and SW6, and connects semiconductor switches SW1 and SW6. As a result, current Iz flows from the positive electrode 10 through semiconductor switch SW1, wire 62b, DC motor 2b, wire 62a, and semiconductor switch SW6 to the negative electrode 11. In step S180, the control circuit 30 detects the current Iz flowing through wires 62a and 62b.

[0115] In step S130, control circuit 30 calculates the temperature rise magnitude ΔTb of wires 62a and 62b, which increases with the execution of control processing in step S170, based on the current Iz. Therefore, it can calculate the temperatures of wires 62a and 62b, taking into account the heating of wires 62a and 62b when the DC motor 2c rotates forward and when the DC motor 2c rotates in reverse. Thus, the temperatures of wires 62a and 62b can be calculated accurately.

[0116] Upon receiving a stop command from the electronic control device for the DC motor 2c, the control circuit 30 disconnects semiconductor switches SW1, SW2, SW3, SW4, SW5, and SW6 in step S190. This stops the flow of current from the positive electrode 10 through the DC motor 2c and wires 62a and 62b to the negative electrode 11. In step S130, the control circuit 30 calculates the temperatures of wires 62a and 62b during the execution of the control processing in step S190, taking into account the heat dissipation from the wires 62a and 62b to their surroundings. Therefore, the temperatures of wires 62a and 62b when the DC motor 2c stops can be calculated more accurately.

[0117] In step S140, control circuit 30 functions as a first current determination unit and a second current determination unit. It determines whether the temperature of the wire is above a threshold for each DC motor, thereby determining whether an overcurrent is flowing through the wire. Therefore, control circuit 30 also functions as a first stop control unit and a second stop control unit. When it is determined that an overcurrent is flowing through the wire for each DC motor, control semiconductor switches SW1, SW2, SW3, SW4, SW5, and SW6. This prevents overcurrent from flowing through wires 60a, 60b, 61a, 61b, 62a, and 62b for each DC motor. Therefore, overcurrent protection for wires 60a, 60b, 61a, 61b, 62a, and 62b can be appropriately performed for each DC motor.

[0118] (Other implementation methods) (1) In the first embodiment described above, an example of using a DC motor 2a as an electrical load was given. However, instead, a light source device such as a hot cathode tube or a cold cathode tube, or a single-phase AC motor may also be used as an 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 an electrical load instead of DC motors 2a, 2b, and 2c.

[0119] (2) In the first embodiment described above, an example was given in which the voltage between the terminals 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, it may be done instead, as in (a)(b)(c) below.

[0120] (a) The current detection unit 20a detects the inter-terminal voltage between the input and output terminals of the semiconductor switch SW4. The control circuit 30 calculates the current ia by dividing the inter-terminal voltage of the semiconductor switch SW4 by the on-resistance of the semiconductor switch SW4.

[0121] (b) A resistive element, which serves as a shunt resistor and carries a current ia, is connected in series between the positive electrode 10 and the negative electrode 11 relative to wires 60a and 60b. The current detection unit 20a calculates the voltage between one terminal and the other terminal of the resistive element, i.e., the inter-terminal voltage, when semiconductor switches SW1 and SW4 are turned on. The control circuit 30 calculates the current ia by dividing the inter-terminal voltage of the resistive element by the resistance value of the resistive element.

[0122] (c) A transistor forming a current mirror circuit with semiconductor switch SW1 is used as the current detection unit 20a. The control terminal of the transistor is connected to the control terminal of 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 proportional to the current ia flows through the input and output terminals of the transistor. The control circuit 30 detects the detection current instead of the current ia. Alternatively, a transistor forming a current mirror circuit with semiconductor switch SW4 may be used as the current detection unit 20a. A detection current proportional to the current ia flows through the input and output terminals of the transistor.

[0123] (3) In the second embodiment described above, it is not limited to dividing the voltage between the terminals of the semiconductor switch SW1 detected by the current detection unit 20x by the on-resistance of the semiconductor switch SW1 to calculate the current ix flowing through the wires 60a and 60b, but can also be as described in (d)(e)(f) below.

[0124] (d) The current detection unit 20x detects the voltage between the terminals of the semiconductor switch SW4. The control circuit 30 calculates the current ia by dividing the voltage between the terminals of the semiconductor switch SW4 by the on-resistance of the semiconductor switch SW4.

[0125] (e) A resistive element, which serves as a shunt resistor and carries a current ix, is connected in series between the positive electrode 10 and the negative electrode 11 relative to wires 60a and 60b. This current detection unit 20x calculates the voltage between one terminal and the other terminal of the resistive element, i.e., the inter-terminal voltage, when semiconductor switches SW1 and SW4 are turned on. The control circuit 30 calculates the current ix by dividing the inter-terminal voltage of the resistive element by the resistance value of the resistive element.

[0126] (f) A transistor forming a current mirror circuit with the semiconductor switch SW1 is used as a 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 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.

[0127] Alternatively, the transistor that forms a current mirror circuit together with the semiconductor switch SW4 can be used as the current detection unit 20a. A detection current proportional to the current ix flows through the input and output terminals of the transistor. Furthermore, in the second embodiment described above, the current iy flowing through wires 61a and 61b can be calculated in the same manner as in (d), (e), and (f) described above. In the second embodiment described above, the current iz flowing through wires 62a and 62b can also be calculated in the same manner as in (d), (e), and (f) described above.

[0128] (4) In the first embodiment described above, an example was given in which the voltage between the terminals of the semiconductor switch SW3 detected by the current detection unit 20b was divided by the on-resistance of the semiconductor switch SW3 to calculate the current ib flowing through the wires 60a and 60b. However, it is also possible to do so as in (g)(h)(i) below.

[0129] (g) The current detection unit 20b detects the inter-terminal voltage between the input and output terminals of the semiconductor switch SW2. The control circuit 30 calculates the current ib by dividing the inter-terminal voltage of the semiconductor switch SW2 by the on-resistance of the semiconductor switch SW2.

[0130] (h) A resistive element, which serves as a shunt resistor and carries a current ib, is connected in series between the positive electrode 10 and the negative electrode 11 relative to wires 60a and 60b. The current detection unit 20b detects the voltage between one terminal and the other terminal of the resistive element when semiconductor switches SW3 and SW2 are turned on. The control circuit 30 calculates the current ib by dividing the voltage between the terminals of the resistive element by the resistance value of the resistive element.

[0131] (i) A transistor forming a current mirror circuit with semiconductor switch SW3 is used as the current detection unit 20b. The control terminal of the transistor is connected to the control terminal of 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 proportional to the current ib flows through the input and output terminals of the transistor. The control circuit 30 detects the detection current instead of the current ib. Alternatively, a transistor forming a current mirror circuit with semiconductor switch SW2 can also be used as the current detection unit 20b. A detection current proportional to the current ib flows through the input and output terminals of the transistor. The control circuit 30 detects the detection current instead of the current ib.

[0132] (5) In the second embodiment described above, it is not limited to the case where the voltage between the terminals of the semiconductor switch SW3 detected by the current detection unit 20x is divided by the on-resistance of the semiconductor switch SW3 to calculate the current ib flowing through the wires 61a and 61b, but can also be as follows (j)(k)(l).

[0133] (j) The current detection unit 20x detects the inter-terminal voltage between the input and output terminals of the semiconductor switch SW2. The control circuit 30 calculates the current ix by dividing the inter-terminal voltage of the semiconductor switch SW2 by the on-resistance of the semiconductor switch SW2.

[0134] (k) A resistive element, which serves as a shunt resistor and carries a current ix, is connected in series between the positive electrode 10 and the negative electrode 11 relative to wires 60a and 60b. The current detection unit 20x detects the voltage between one terminal and the other terminal of the resistive element when semiconductor switches SW3 and SW2 are turned on. The control circuit 30 calculates the current ix by dividing the voltage between the terminals of the resistive element by the resistance value of the resistive element.

[0135] (l) A transistor, which together with the semiconductor switch SW3 forms a current mirror circuit, 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.

[0136] Control circuit 30 detects the current instead of current ix. Alternatively, a transistor that forms a current mirror circuit together with semiconductor switch SW2 may be used as current detection unit 20x. A detection current proportional to current ix flows through the input and output terminals of the transistor. Control circuit 30 detects the current instead of current ix. Furthermore, in the second embodiment described above, the current iy flowing through wires 61a and 61b can be calculated in the same manner as described in (j)(k)(l). In the second embodiment described above, the current iz flowing through wires 62a and 62b can also be calculated in the same manner as described in (j)(k)(l).

[0137] (4) In the first embodiment described above, examples of semiconductor switches SW1, SW2, SW3, and SW4 composed of individual semiconductor switch units were described. However, instead of semiconductor switches SW1, SW2, SW3, and SW4, semiconductor switches with built-in current detection units 20a or 20b can also be used. Similarly, in the second embodiment described above, semiconductor switches SW1, SW2, SW3, SW4, SW5, and SW6 can also be semiconductor switches with built-in current detection units 20a or 20b.

[0138] (5) In the second embodiment described above, an example of controlling three DC motors 2a, 2b, and 2c via circuit 50A was given. However, it is also possible to control two DC motors via circuit 50A instead. Alternatively, it is also possible to control four or more DC motors via circuit 50A.

[0139] (6) In the first and second embodiments described above, examples of applying the control device of this disclosure to automobiles have been described. However, the control device of this disclosure may also be applied to various industrial equipment other than automobiles.

[0140] (7) In the first and second embodiments described above, examples of calculating the ambient temperature of wires 60a and 60b based on the detection value of temperature detection unit 21a were explained. However, alternatively, a predetermined temperature may be used as the ambient temperature of wires 60a and 60b. Similarly, in the second embodiment described above, an example of calculating the ambient temperature of wires 61a and 61b based on the detection value of temperature detection unit 21b was explained. However, alternatively, a predetermined temperature may be used as the ambient temperature of wires 61a and 61b.

[0141] Alternatively, the detection value of temperature detection unit 21a can be used as the ambient temperature of wires 61a and 61b. In the second embodiment described above, an example of calculating the ambient temperature of wires 62a and 62b based on the detection value of temperature detection unit 21c was given. However, a predetermined temperature can also be used instead as the ambient temperature of wires 62a and 62b. Furthermore, the detection value of temperature detection unit 21a can also be used as the ambient temperature of wires 62a and 62b.

[0142] (8) In the first and second embodiments described above, an example was given in which the control circuit 30 calculates the current i by dividing the voltage between the terminals of the semiconductor switch SW1 by the on-resistance of the semiconductor switch SW1 in step S200. However, the control circuit 30 may also calculate the current i by dividing the voltage between the terminals of the semiconductor switch SW2 by the on-resistance of the semiconductor switch SW2.

[0143] The control circuit 30 can also calculate the current i by dividing the voltage between the terminals of semiconductor switch SW3 by the on-resistance of semiconductor switch SW3. The control circuit 30 can also calculate the current i by dividing the voltage between the terminals of semiconductor switch SW4 by the on-resistance of semiconductor switch SW4.

[0144] (9) In the second embodiment described above, an example of a vehicle motor control device composed of half-bridge circuits 53A, 53B, and 53C was explained. However, the vehicle motor control device may also be composed of four or more half-bridge circuits instead.

[0145] (10) Furthermore, this disclosure is not limited to the above-described embodiments, and can be appropriately modified within the scope described in the claims. Additionally, the above-described embodiments are not mutually exclusive and can be appropriately combined except in cases where they are clearly incompatible. Furthermore, in the above-described embodiments, the elements constituting the embodiments are not essential except where they are specifically stated to be necessary or where they are clearly considered necessary in principle. Furthermore, in the above-described embodiments, when referring to the number, value, quantity, range, etc., of the constituent elements of the embodiments, the quantity is not limited to that specific number except where it is specifically stated to be necessary or where it is clearly limited to a specific quantity in principle.

Claims

1. A control device, characterized in that, have: An H-bridge circuit has a first switch disposed between a high-potential section having a predetermined potential and a low-potential section having a potential lower than the high-potential section, a second switch disposed between the first switch and the low-potential section, a third switch disposed between the high-potential section and the low-potential section, and a fourth switch disposed between the third switch and the low-potential section. In the case where the terminal that commonly connects the first switch and the second switch is designated as the first common connection terminal, and the terminal that commonly connects the third switch and the fourth switch is designated as the second common connection terminal, the wire and the electrical load are connected in series between the first common connection terminal and the second common connection terminal. A first control unit turns on the first switch and the fourth switch to allow a first current to flow from the high potential section through the first switch, the electrical load, and the fourth switch to the low potential section. The second control unit turns on the second switch and the third switch so that the second current flows from the high potential section through the third switch, the electrical load, and the second switch to the low potential section. The first rise amplitude calculation unit calculates the rise amplitude of the temperature of the wire that has risen along with the execution of the first control unit, i.e., the first temperature rise amplitude, based on the first current. The second rise amplitude calculation unit calculates the rise amplitude of the temperature of the wire that has risen due to the execution of the second control unit, i.e., the second temperature rise amplitude, based on the second current. as well as The wire temperature calculation unit calculates the temperature of the wire taking into account both the first temperature rise and the second temperature rise.

2. The control device according to claim 1, characterized in that, The wire temperature calculation unit calculates the wire temperature by adding the first temperature rise rate and the second temperature rise rate.

3. The control device according to claim 1 or 2, characterized in that, When the first control unit is executed, the wire temperature calculation unit calculates the temperature of the wire based on the first temperature rise rate. When the second control unit is executed, the wire temperature calculation unit calculates the temperature of the wire based on the second temperature rise rate.

4. The control device according to claim 1 or 2, characterized in that, The device includes a third control unit that controls the first switch, the second switch, the third switch, and the fourth switch to stop the current flowing from the high potential portion through the electrical load and the wire to the low potential portion. 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. The control device according to claim 1 or 2, characterized in that, have: The current determination unit determines whether an overcurrent flows through the wire by determining whether the temperature of the wire calculated by the wire temperature calculation unit is above a threshold. as well as When the current determination unit determines that an overcurrent is flowing in the wire, the stop control unit controls the first switch, the second switch, the third switch, and the fourth switch respectively to stop the overcurrent from flowing in the wire.

6. The control device according to claim 5, characterized in that, have: A half-bridge circuit, wherein a fifth switch is disposed between the high potential section and the low potential section, and a sixth switch is disposed between the fifth switch and the low potential section; In the case where the electrical load is designated as the first electrical load, the wire is designated as the first wire, and the terminal commonly connected to the fifth switch and the sixth switch is designated as the third common connection terminal, the second wire and the second electrical load are connected in series between the second common connection terminal and the third common connection terminal. The fourth control unit connects the third switch and the sixth switch to allow a third current to flow from the high potential section through the third switch, the second electrical load, and the sixth switch to the low potential section. The fifth control unit connects the fourth switch and the fifth switch to allow the fourth current to flow from the high potential section through the fifth switch, the second electrical load, and the fourth switch to the low potential section. The third rise amplitude calculation unit calculates the rise amplitude of the temperature of the second wire, which increases with the execution of the fourth control unit, based on the third current. The fourth rise amplitude calculation unit calculates the rise amplitude of the temperature of the second wire, which has risen due to the execution of the fifth control unit, based on the fourth current. as well as When the wire temperature calculation unit is set as the first wire temperature calculation unit, the second wire temperature calculation unit calculates the temperature of the second wire taking into account the third temperature rise and the fourth temperature rise.

7. The control device according to claim 6, characterized in that, The device includes a sixth control unit that controls the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch to stop the current flowing from the high-potential portion to the low-potential portion through the second electrical load. 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. The control device according to claim 7, characterized in that, have: The second current determination unit, when the current determination unit is set as the first current determination unit, determines whether an overcurrent flows in the second wire by determining whether the temperature of the second wire calculated by the second wire temperature calculation unit is above a threshold. as well as When the second stop control unit is configured as the first stop control unit, and the second current determination unit determines that an overcurrent is flowing in the second wire, the second stop control unit 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 in the second wire.

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