Inverter device and motor drive device for mobile body

Abstract

Fast discharge of a smoothing capacitor (18) is executed via a first resistor (34) of a resistive series circuit (32). Regular discharge of the smoothing capacitor (18) is executed via the first resistor (34), a second resistor (36), a third resistor (38), and a fourth resistor (40) of the resistive series circuit (32). A divisional voltage that can be used for inspection of the operation of first and second discharge control switching elements (48, 50) is input into a control circuit (70) via a wire (42) that branches from the connection line between the third resistor (38) and the fourth resistor (40) of the resistive series circuit (32). In this manner, the resistive series circuit (32) is used commonly in order to execute the fast discharge, execute the regular discharge, and acquire the divisional voltage.

Description

Inverter device and motor drive device for mobile object CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Patent Application No. 2024-118813 filed in Japan on July 24, 2024, the contents of which are incorporated by reference in their entirety.

[0002] The present disclosure relates to an inverter device for driving a motor mounted on a moving body and a motor drive device for a moving body.

[0003] For example, Patent Document 1 discloses an inverter device that can quickly discharge a smoothing capacitor (filter capacitor) provided in the inverter device when an accident or abnormality such as a vehicle collision occurs.

[0004] In the inverter device of Patent Document 1, when it becomes necessary to quickly discharge the smoothing capacitor while the motor is rotating, the discharge switch is turned on and the smoothing capacitor is rapidly discharged via a first discharge resistor connected in series with the discharge switch.When rapid discharge is not necessary, such as when the vehicle is normally stopped, the smoothing capacitor is normally discharged via a second discharge resistor connected in parallel to the smoothing capacitor and having a resistance value higher than that of the first discharge resistor.

[0005] Japanese Patent Application Laid-Open No. 2022-181191

[0006] As described above, the inverter device of Patent Document 1 has a first discharge resistor for rapid discharge and a second discharge resistor for normal discharge, which are each provided independently. Furthermore, when attempting to verify the operation of the discharge switch to confirm that the discharge switch is operating normally, it may be necessary to connect a voltage-dividing resistor in parallel with the discharge switch to detect the voltage applied to the discharge switch. This increases the number of resistors, which can lead to problems such as the need for a large space for installing the resistors.

[0007] The present disclosure has been made in consideration of the above points, and aims to provide an inverter device and a motor drive device for a mobile object that enable normal discharge and rapid discharge of a smoothing capacitor, and further enable verification of the operation of a discharge control switching element while reducing the number of resistors.

[0008] In order to achieve the above object, the inverter device according to the present disclosure is an inverter device for driving a motor mounted on a mobile body, and is configured to include: an inverter circuit having a plurality of switching elements; a smoothing capacitor connected in parallel to the inverter circuit; a resistor series circuit connected in parallel to the smoothing capacitor and having at least a first resistor, a second resistor, and a third resistor connected in series in this order from the high-voltage line to the low-voltage line for normal discharge of the smoothing capacitor; a discharge control switching element provided on a wiring branching from the connection line between the first resistor and the second resistor and reaching the low-voltage line, and capable of performing rapid discharge of the smoothing capacitor via the first resistor; a control unit controlling the on / off of the discharge control switching element; and a divided voltage input unit that divides the voltage applied to the resistor series circuit when the smoothing capacitor is discharged and inputs the divided voltage from the connection line between the second resistor and the third resistor to the control unit.

[0009] a resistor series circuit connected in parallel to the smoothing capacitor, the resistor series circuit including at least a first resistor, a second resistor, and a third resistor connected in series in this order from the high-voltage line to the low-voltage line for normal discharge of the smoothing capacitor; a discharge control switching element provided on a wiring branching from the connection line between the first resistor and the second resistor and reaching the low-voltage line, the discharge control switching element being capable of rapid discharge of the smoothing capacitor via the first resistor; a control unit controlling the on / off of the multiple switching elements of the inverter circuit and the discharge control switching element; and a divided voltage input unit which, when discharging the smoothing capacitor, divides the voltage applied to the resistor series circuit and inputs the divided voltage to the control unit from the connection line between the second resistor and the third resistor.

[0010] In the inverter device and mobile motor drive device according to the present disclosure, rapid discharge of the smoothing capacitor is performed via the first resistor of the resistor series circuit. Normal discharge of the smoothing capacitor is performed via the first, second, and third resistors of the resistor series circuit. A divided voltage that can be used to check whether the discharge control switching element is operating normally, i.e., to verify operation, is input to the controller from a connection line between the second and third resistors of the resistor series circuit.

[0011] In this way, in the inverter device and the mobile motor drive device according to the present disclosure, the resistor series circuit is shared for performing rapid discharge, normal discharge, and obtaining the divided voltage, thereby enabling normal discharge and rapid discharge of the smoothing capacitor, and further enabling verification of the operation of the discharge control switching element, while reducing the number of resistors.

[0012] The reference numbers in parentheses in the claims merely indicate an example of the correspondence with specific configurations in the embodiments described below, in order to facilitate understanding of the present disclosure, and are not intended to limit the scope of the present disclosure in any way.

[0013] Furthermore, the technical features of the present disclosure other than those described above will become apparent from the following description of the embodiments and the accompanying drawings.

[0014] Fig. 1 is a configuration diagram showing an example of the configuration of an inverter device and a mobile motor drive device including the inverter device according to an embodiment. Fig. 2 is a diagram for explaining a discharge path when normal discharge of a smoothing capacitor is performed. Fig. 3 is a diagram for explaining a discharge path when rapid discharge of a smoothing capacitor is performed. Fig. 4 is a table showing the presence or absence of rapid discharge and the magnitude of the divided voltage input to the control circuit according to the on / off of first and second discharge control switching elements. Fig. 5 is a configuration diagram showing an example of the configuration of an inverter device and a mobile motor drive device including the inverter device according to a modified example.

[0015] Hereinafter, embodiments of an inverter device and a motor drive device including an inverter device according to the present disclosure will be described with reference to the drawings. However, the present disclosure is not limited to the following embodiments, and various modifications described below are also included within the technical scope of the present disclosure. Furthermore, in addition to the following, various modifications can be implemented without departing from the spirit of the present disclosure. The embodiments and various modifications can be appropriately combined within the scope of no technical contradiction. In the following description, identical or similar components may be assigned the same reference numerals across multiple drawings, and their description may be omitted. Furthermore, when only a portion of a component is mentioned, the description provided elsewhere may apply to the other components.

[0016] First Embodiment FIG. 1 is a diagram showing an example of the configuration of an inverter device 10 according to this embodiment, and a motor drive device 100 for a moving object that includes the inverter device 10 and a motor (motor generator) 60.

[0017] The mobile body motor drive device 100 according to this embodiment is applied to, for example, a mobile body that uses a motor generator 60 as a drive source. Examples of mobile bodies include electric vehicles such as battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs), electric flying objects such as drones and electric vertical take-off and landing (eVTOL) aircraft, ships, construction machinery, and agricultural machinery. Below, an example will be described in which the mobile body motor drive device is applied to an electric vehicle as a vehicle motor drive device.

[0018] As shown in FIG. 1, the vehicle motor drive device 100 includes a DC power supply 12, an inverter device 10, a motor generator 60, and the like.

[0019] The DC power supply 12 is a DC power supply configured with a rechargeable secondary battery. The secondary battery is, for example, a lithium-ion battery, a nickel-metal hydride battery, or the like. The motor generator 60 is a three-phase AC rotating electric machine. The motor generator 60 functions as a drive source for the vehicle, i.e., an electric motor. The motor generator 60 also functions as a generator during regeneration. The inverter device 10 converts power from DC to three-phase AC and from three-phase AC to DC between the DC power supply 12 and the motor generator 60.

[0020] Although not shown, the vehicle motor drive device 100 may include a converter. The converter is a DC-DC conversion circuit configured to be able to convert a DC voltage into a DC voltage of a different value. The converter may be provided between the DC power supply 12 and the smoothing capacitor 18. The converter may be configured, for example, by a reactor and a switching element. By providing the converter, the smoothing capacitor 18 can be charged to a DC voltage higher than the DC voltage of the DC power supply 12. The converter can also step down the high-voltage DC voltage that has been regenerated and converted to DC and provide it to the DC power supply 12.

[0021] As shown in FIG. 1 , the inverter device 10 includes a smoothing capacitor 18 , an inverter circuit 20 , and a discharge circuit 30 .

[0022] The smoothing capacitor 18 smoothes the DC voltage supplied from the DC power supply 12. The positive electrode of the smoothing capacitor 18 is connected to the high-voltage line 14, which is a power supply line on the high potential side. The negative electrode of the smoothing capacitor 18 is connected to the low-voltage line 16, which is a power supply line on the low potential side. The high-voltage line 14 is connected to the positive electrode of the DC power supply 12, and the low-voltage line 16 is connected to the negative electrode of the DC power supply 12. In this way, the smoothing capacitor 18 is connected in parallel to the DC power supply 12.

[0023] A relay switch (not shown) is provided between the DC power supply 12 and the smoothing capacitor 18. The relay switch is closed, for example, when the main switch of the electric vehicle is turned on. This allows the smoothing capacitor 18 to be charged by the DC voltage of the DC power supply 12. On the other hand, the relay switch is opened when the main switch of the electric vehicle is turned off, or when an accident such as a vehicle collision or a vehicle abnormality occurs. This allows the smoothing capacitor 18 to be discharged by the discharge circuit 30.

[0024] The inverter circuit 20 is a DC-AC conversion circuit. The inverter circuit 20 converts a DC voltage into a three-phase AC voltage in accordance with switching control (on / off control) by a control circuit 70 (described later) and outputs the converted voltage as a drive signal to the motor generator 60. This causes the motor generator 60 to rotate and drive so as to generate a predetermined torque. Furthermore, during regenerative braking of the vehicle, the inverter circuit 20 converts the three-phase AC voltage generated by the motor generator 60 in response to rotational force from the wheels into a DC voltage and outputs the DC voltage to the high-voltage line 14. In this way, the inverter circuit 20 performs bidirectional power conversion between the DC power source 12 and the motor generator 60.

[0025] The inverter circuit 20 includes upper and lower arm circuits 26U, 26V, and 26W for three phases. Each of the upper and lower arm circuits 26U, 26V, and 26W includes an upper arm 26H and a lower arm 26L. The upper arm 26H and the lower arm 26L are connected in series between the high-voltage line 14 and the low-voltage line 16, with the upper arm 26H on the high-voltage line 14 side. Hereinafter, the upper arm 26H and the lower arm 26L may be simply referred to as arms 26H and 26L.

[0026] The connection points between the upper arm 26H and the lower arm 26L of each of the upper and lower arm circuits 26U, 26V, 26W, i.e., the midpoints of each of the upper and lower arm circuits 26U, 26V, 26W, are connected to corresponding phase windings 60a, 60b, 60c of the motor generator 60 via output lines 55a, 55b, 55c. More specifically, of the upper and lower arm circuits 26U, 26V, 26W, the upper and lower arm circuit 26U corresponding to the U phase of the motor generator 60 is connected to the U phase winding 60a via output line 55a. The upper and lower arm circuit 26V corresponding to the V phase of the motor generator 60 is connected to the V phase winding 60b via output line 55b. The upper and lower arm circuit 26W corresponding to the W phase of the motor generator 60 is connected to the W phase winding 60c via output line 55c.

[0027] The inverter circuit 20 has six arms 26H, 26L. Each arm 26H, 26L has a switching element. The number of switching elements constituting each arm 26H, 26L is not particularly limited and may be one or more. When there are more than one switching element, the multiple switching elements connected in parallel with each other are turned on and off at the same timing by a common gate drive signal.

[0028] 1 is an n-channel MOSFET 22. MOSFET is an abbreviation for Metal Oxide Semiconductor Field Effect Transistor. In the upper arm 26H, the drain of the MOSFET 22 is connected to the high-voltage line 14. In the lower arm 26L, the source of the MOSFET 22 is connected to the low-voltage line 16. The source of the MOSFET 22 in the upper arm 26H and the drain of the MOSFET 22 in the lower arm 26L are connected to each other.

[0029] In each arm 26H, 26L, a freewheeling diode 24 is connected in antiparallel to the MOSFET 22. That is, the anode of the diode 24 is connected to the source of the corresponding MOSFET 22, and the cathode is connected to the drain. The diode 24 may be a parasitic diode (body diode) of the MOSFET 22, or may be an external diode.

[0030] The switching element is not limited to the MOSFET 22. For example, an IGBT (Insulated Gate Bipolar Transistor) may be used as the switching element. Even when an IGBT is used, a freewheeling diode is connected in antiparallel.

[0031] The inverter device 10 according to this embodiment includes a discharge circuit 30 that discharges the smoothing capacitor 18. When the motor generator 60 is driven by the vehicle motor drive device 100 or when the motor generator 60 is performing regeneration, the smoothing capacitor 18 is charged to a high voltage. Therefore, in order to prevent electric shock or other equipment failures, for example, when the vehicle is stopped and the main switch is turned off, and the motor generator 60 is no longer being driven or performing regeneration, it is necessary to discharge the smoothing capacitor 18. Furthermore, in the event of an accident such as a vehicle collision or a vehicle abnormality, it is necessary to discharge the smoothing capacitor 18 as quickly as possible so that measures can be taken immediately to address the vehicle accident or abnormality.

[0032] The discharge circuit 30 of this embodiment is configured to be able to perform normal discharge when the vehicle is normally stopped and rapid discharge in an emergency such as an accident. The configuration of the discharge circuit 30 of this embodiment will be described in detail below with reference to Fig. 1. During discharge by the discharge circuit 30, the relay switch between the DC power supply 12 and the smoothing capacitor 18 is turned off.

[0033] The discharge circuit 30 of this embodiment has a resistor series circuit 32 including a first resistor 34, a second resistor 36, a third resistor 38, and a fourth resistor 40. The first resistor 34, the second resistor 36, the third resistor 38, and the fourth resistor 40 are connected in series in this order from the high-voltage line 14 toward the low-voltage line 16. Note that the "first resistor" in the claims of the present disclosure corresponds to the first resistor 34, the "second resistor" corresponds to the second resistor 36 and the third resistor 38, and the "third resistor" corresponds to the fourth resistor 40. Furthermore, the second resistor 36 corresponds to a first group of second resistors, and the third resistor 38 corresponds to a second group of second resistors.

[0034] The resistance value R1 of the first resistor 34 is set to the lowest resistance value among the first resistors 34 to the fourth resistors 40. For example, the resistance value R1 of the first resistor 34 is set to a value less than 1 kΩ. The resistance value R2 of the second resistor 36 is set to a relatively high resistance value among the first resistors 34 to the fourth resistors 40. For example, the resistance value R2 of the second resistor 36 is set to a value equal to or greater than the resistance value R3 of the third resistor 38, that is, 600 kΩ or greater. Like the second resistor 36, the resistance value R3 of the third resistor 38 is set to a relatively high resistance value among the first resistors 34 to the fourth resistors 40. For example, the resistance value R3 of the third resistor 38 is set to a value equal to or less than the resistance value R2 of the second resistor 36, that is, 600 kΩ or less. The resistance value R4 of the fourth resistor 40 is set to a relatively low resistance value among the first resistors 34 to the fourth resistors 40. For example, the resistance value R4 of the fourth resistor 40 is set to a value of approximately 1 kΩ or more and less than 2 kΩ.

[0035] The first resistor 34 and the second resistor 36 are preferably installed outside the substrate on which the control circuit 70 is mounted. The temperature of the first resistor 34 becomes high during rapid discharge, and the temperature of the second resistor 36 becomes relatively high during normal discharge because it has the highest resistance value R2 among the first resistor 34 to the fourth resistor 40. By installing the first resistor 34 and the second resistor 36 outside the substrate, heat dissipation can be more easily ensured. Alternatively, cement resistors with excellent heat resistance may be used as the first resistor 34 and the second resistor 36.

[0036] The third resistor 38 and the fourth resistor 40 can suppress temperature rise during normal discharge and other operations compared to the first resistor 34 and the second resistor 36, and therefore may be installed on the substrate on which the control circuit 70 is mounted. When the third resistor 38 and the fourth resistor 40 are installed on the substrate, they may be configured as chip resistors. In FIG. 1 , the range indicated by the dashed-dotted line 72 shows an example of the range that can be mounted on the substrate on which the control circuit 70 is mounted. Furthermore, the resistance value R4 of the fourth resistor 40 is set to a value that is sufficiently smaller than the resistance value R3 of the third resistor 38. Therefore, the divided voltage applied to the fourth resistor 40 can be a low voltage that can be input to the control circuit 70.

[0037] Each of the first resistor 34 to the fourth resistor 40 may be formed by a single resistor element, or may be formed by a group of a plurality of resistor elements connected in series.

[0038] In the discharge circuit 30 of this embodiment, an amplifier 44 is provided on a wiring 42 that branches off from the connection line connecting the third resistor 38 and the fourth resistor 40 and reaches the control circuit 70. Therefore, when the smoothing capacitor 18 is discharged, a divided voltage obtained by dividing the voltage applied to the resistor series circuit 32 by the fourth resistor 40 and the other resistors is input to the control circuit 70 via the wiring 42 and the amplifier 44. The wiring 42 and the amplifier 44 correspond to the divided voltage input unit of the present disclosure. Note that the amplifier 44 may be omitted.

[0039] The discharge circuit 30 of this embodiment also has a discharge control switching element 46 provided on a wiring that branches off from the connection line between the first resistor 34 and the second resistor 36 and reaches the low-voltage line 16. The discharge control switching element 46 includes a first discharge control switching element 48 and a second discharge control switching element 50. The first discharge control switching element 48 and the second discharge control switching element 50 are connected in series on the wiring that branches off from the connection line between the first resistor 34 and the second resistor 36 and reaches the low-voltage line 16. The first discharge control switching element 48 and the second discharge control switching element 50 can be configured, for example, by MOSFETs.

[0040] In the discharge circuit 30 of this embodiment, the connection line connecting the first discharge control switching element 48 and the second discharge control switching element 50 and the connection line connecting the second resistor 36 and the third resistor 38 are connected by a connecting line 52.

[0041] The control circuit 70 controls the on / off of the multiple switching elements 22 of the inverter circuit 20 and the first and second discharge control switching elements 48, 50. The control circuit 70 corresponds to the control unit of the present disclosure. The control circuit 70 includes drive circuits for the multiple switching elements 22 of the inverter circuit 20 and the first and second discharge control switching elements 48, 50. The multiple switching elements 22 of the inverter circuit 20 and the first and second discharge control switching elements 48, 50 are turned on or off by drive voltages output from the drive circuits in response to drive commands from the control circuit 70.

[0042] The control circuit 70 generates drive commands for the multiple switching elements 22 of the inverter circuit 20 based on, for example, a torque request input from a host ECU (not shown) and detection signals detected by various sensors. The various sensors include, for example, a current sensor, a rotation angle sensor, and a voltage sensor. The current sensor detects the phase currents flowing through the windings 60a, 60b, and 60c of each phase of the motor-generator 60. The rotation angle sensor detects the rotation angle of the rotor of the motor-generator 60. The voltage sensor detects the voltage across the smoothing capacitor 18. The control circuit 70 may also detect the voltage across the smoothing capacitor 18 from the divided voltage input via the wiring 42. The control circuit 70 outputs, for example, a PWM signal as the drive command. The control circuit 70 may be configured, for example, by a computer having a processor and a memory.

[0043] Furthermore, the control circuit 70 generates drive commands for the first and second discharge control switching elements 48, 50. Drive voltages corresponding to the generated drive commands are applied via the drive circuit to the first and second discharge control switching elements 48, 50. Below, we will explain how the control circuit 70 controls the discharge circuit 30 by turning on and off the first and second discharge control switching elements 48, 50.

[0044] First, when performing normal discharge of the smoothing capacitor 18, the control circuit 70 turns off both the first and second discharge control switching elements 48, 50. As a result, as shown by the dotted line 19a in FIG. 2, the smoothing capacitor 18 discharges through the first resistor 34 to the fourth resistor 40 of the resistor series circuit 32. As described above, the resistor series circuit 32 includes the second resistor 36 and the third resistor 38, which have relatively high resistance values. Therefore, although it takes some time for the discharge to complete, the current value during normal discharge can be suppressed. This suppresses the temperature rise of the first resistor 34 to the fourth resistor 40 during normal discharge.

[0045] When normal discharge of the smoothing capacitor 18 is performed via the resistor series circuit 32, the control circuit 70 monitors the divided voltage input via the wiring 42 and the amplifier 44. This allows the control circuit 70 to determine whether normal discharge of the smoothing capacitor 18 is being performed normally. In other words, by monitoring the divided voltage, the control circuit 70 can detect the occurrence of a situation in which normal discharge cannot be performed normally, for example, due to a break in any of the resistors. If the control circuit 70 detects that normal discharge cannot be performed normally, it takes action such as issuing a warning to the user.

[0046] More specifically, when the first and second discharge control switching elements 48, 50 are both turned off and normal discharge is being performed normally, the control circuit 70 receives a divided voltage obtained by dividing the voltage between the first resistor 34 to the third resistor 38 and the fourth resistor 40. Therefore, the control circuit 70 can determine whether normal discharge of the smoothing capacitor 18 is being performed normally based on whether the input divided voltage corresponds to the divided voltage obtained by dividing the voltage between the first resistor 34 to the third resistor 38 and the fourth resistor 40. When normal discharge is being performed normally, the divided voltage is expressed as VH×R4 / (R1+R2+R3+R4), as shown in the table of FIG. 4 , where VH is the voltage of the smoothing capacitor 18, R1 is the resistance value of the first resistor 34, R2 is the resistance value of the second resistor 36, R3 is the resistance value of the third resistor 38, and R4 is the resistance value of the fourth resistor 40.

[0047] Furthermore, when rapid discharge of the smoothing capacitor 18 is performed, the control circuit 70 turns on both the first and second discharge control switching elements 48, 50. As a result, as shown by the dotted line 19b in Fig. 3, the smoothing capacitor 18 discharges via the first resistor 34 of the resistor series circuit 32 and the first and second discharge control switching elements 48, 50. The first resistor 34 has the lowest resistance value R1 among the first resistor 34 to the fourth resistor 40 of the resistor series circuit 32. Therefore, a large current flows during rapid discharge, and the discharge of the smoothing capacitor 18 can be completed quickly.

[0048] When the smoothing capacitor 18 is rapidly discharged via the first resistor 34, the control circuit 70 monitors the divided voltage input via the line 42 and the amplifier 44 to determine whether the rapid discharge of the smoothing capacitor 18 is occurring normally. When the rapid discharge is occurring normally, the divided voltage is Vds × R4 / (R3 + R4), as shown in the table of FIG. 4 , where Vds is the drain-source voltage when the second discharge control switching element 50 is on. Therefore, the control circuit 70 can determine whether the rapid discharge of the smoothing capacitor 18 is occurring normally based on whether the input divided voltage corresponds to Vds × R4 / (R3 + R4).

[0049] Furthermore, the control circuit 70 sequentially turns on the first discharge control switching element 48 and the second discharge control switching element 50 one by one to confirm in advance whether the first discharge control switching element 48 and the second discharge control switching element 50 operate normally, i.e., to verify their operation. The control circuit 70 preferably verifies the operation of the first discharge control switching element 48 and the second discharge control switching element 50, for example, when the electric vehicle starts traveling (corresponding to when the moving object starts moving) and / or when the electric vehicle stops traveling (corresponding to when the moving object stops moving). In this way, the control circuit 70 can verify the operation of the first and second discharge control switching elements 48, 50 before the electric vehicle starts traveling and / or in preparation for the next traveling.

[0050] When the control circuit 70 turns on the first discharge control switching element 48 and turns off the second discharge control switching element 50, the smoothing capacitor 18 is discharged primarily through the first resistor 34, the first discharge control switching element 48, the third resistor 38, and the fourth resistor 40. In this case, the discharge path includes the third resistor 38, which has a relatively high resistance value, so the current value during discharge can be kept small. The divided voltage at this time is expressed as VH×R4 / (R1+R3+R4), as shown in the table of FIG. 4 . Therefore, the control circuit 70 can determine whether the first discharge control switching element 48 is operating normally based on whether a divided voltage equivalent to VH×R4 / (R1+R3+R4) is input via the wiring 42 and the amplifier 44.

[0051] When the control circuit 70 turns off the first discharge control switching element 48 and turns on the second discharge control switching element 50, the smoothing capacitor 18 is discharged primarily through the first resistor 34, the second resistor 36, and the second discharge control switching element 50. In this case, the discharge path also includes the second resistor 36, which has a relatively high resistance value, so the current value during discharge can be kept small. The divided voltage at this time is Vds × R4 / (R3 + R4), as shown in the table of FIG. 4 . Therefore, the control circuit 70 can determine whether the second discharge control switching element 50 is operating normally based on whether a divided voltage equivalent to Vds × R4 / (R3 + R4) is input via the wiring 42 and the amplifier 44.

[0052] As described above, according to the discharge circuit 30 of this embodiment, the control circuit 70 turns on one by one the first discharge control switching element 48 and the second discharge control switching element 50. When the control circuit 70 turns on either the first discharge control switching element 48 or the second discharge control switching element 50, it can determine, based on the divided voltage input from the wiring 42, whether the first discharge control switching element 48 or the second discharge control switching element 50 that has been turned on is operating normally.

[0053] As described above, the discharge circuit 30 of this embodiment uses the first discharge control switching element 48 and the second discharge control switching element 50 connected in series as the discharge control switching element 46. Furthermore, the connection line connecting the first discharge control switching element 48 and the second discharge control switching element 50 and the connection line connecting the second resistor 36 and the third resistor 38 are connected by the connecting line 52. Therefore, by the control circuit 70 turning on the first discharge control switching element 48 and the second discharge control switching element 50 one by one, it is possible to discharge a small current from the smoothing capacitor 18. Therefore, it is possible to verify the operation of the first discharge control switching element 48 and the second discharge control switching element 50 without causing an excessive temperature rise in the first resistor 34 to the fourth resistor 40 in the resistor series circuit 32.

[0054] Furthermore, in the discharge circuit 30 of this embodiment, the first discharge control switching element 48 and the second discharge control switching element 50 are connected in series. Therefore, even if an ON failure occurs in either one of the discharge control switching elements 48, 50, rapid discharge of the smoothing capacitor 18 due to the ON failure can be prevented.

[0055] As described above, in the inverter device 10 and vehicle motor drive device 100 according to this embodiment, rapid discharge of the smoothing capacitor 18 is performed via the first resistor 34 of the resistor series circuit 32. Normal discharge of the smoothing capacitor 18 is performed via the first resistor 34, the second resistor 36, the third resistor 38, and the fourth resistor 40 of the resistor series circuit 32. The divided voltage that can be used to verify the operation of the first and second discharge control switching elements 48, 50 is input to the control circuit 70 via the wiring 42 that branches off from the connection line between the third resistor 38 and the fourth resistor 40 of the resistor series circuit 32.

[0056] In this way, in the inverter device 10 and vehicle motor drive device 100 according to this embodiment, the resistor series circuit 32 is shared for performing rapid discharge, normal discharge, and obtaining the divided voltage. This makes it possible to perform normal discharge and rapid discharge of the smoothing capacitor 18, and further enables verification of the operation of the first and second discharge control switching elements 48, 50, while reducing the number of resistors.

[0057] (Variations) Although preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and can be implemented in various modifications within the scope of the gist of the present disclosure.

[0058] For example, the discharge circuit 30A may be configured as shown in Fig. 5. In the discharge circuit 30A shown in Fig. 5, the third resistor 38, the second discharge control switching element 50, and the connecting wire 52 are omitted from the discharge circuit 30 shown in Fig. 1.

[0059] 5, normal discharge of the smoothing capacitor 18 is performed via the first resistor 34, the second resistor 36, and the fourth resistor 40 of the resistor series circuit 32. At this time, the control circuit 70 can determine whether normal discharge is being performed normally by monitoring whether the divided voltage input via the wiring 42 is a divided voltage equivalent to VH×R4 / (R1+R2+R4).

[0060] 5, the rapid discharge of the smoothing capacitor 18 is performed via the first resistor 34 and the first discharge control switching element 48. At this time, the control circuit 70 can determine whether the rapid discharge is being performed normally by monitoring whether the divided voltage input via the line 42 is a divided voltage equivalent to Vds×R4 / (R2+R4).

[0061] 5, the operation of the first discharge control switching element 48 can be verified by turning on the first discharge control switching element 48 for an extremely short time. In this case, if the first discharge control switching element 48 is normally turned on, the magnitude of the divided voltage input to the control circuit 70 will be the same as in the case of rapid discharge.

[0062] In the above-described embodiment, an example has been described in which the control circuit 70 controls the on / off of the multiple switching elements 22 of the inverter circuit 20 and the discharge control switching element 46. However, the control circuit that controls the on / off of the multiple switching elements 22 of the inverter circuit 20 and the control circuit that controls the on / off of the discharge control switching element 46 may be provided separately.

[0063] Furthermore, for example, the control circuit 70 and the method described herein may be implemented by a special-purpose computer comprising a processor programmed to execute one or more functions embodied in a computer program. The control circuit 70 and the method described herein may also be implemented using dedicated hardware logic circuits. The control circuit 70 and the method described herein may also be implemented by one or more special-purpose computers configured by combining a processor executing a computer program with one or more hardware logic circuits. The processor may be any computing core, such as a CPU, MPU, GPU, or DFP (Data Flow Processor). Some or all of the functions of the processor may be implemented by hardware. For example, some or all of the functions of the processor may be implemented using a system-on-chip (SoC), an integrated circuit (IC), or a field-programmable gate array (FPGA).

[0064] (Disclosure of Technical Ideas) Finally, this specification discloses the following technical ideas and combinations thereof. The combinations of the following technical ideas apply not only to the inverter device 10 but also to the mobile motor drive device 100 that includes the inverter device 10.

[0065] (Technical Idea 1) An inverter device (10) for driving a motor (60) mounted on a moving body, comprising: an inverter circuit (20) having a plurality of switching elements (22); a smoothing capacitor (18) connected in parallel to the inverter circuit; a resistor series circuit (32) connected in parallel to the smoothing capacitor, the resistor series circuit (32) including at least a first resistor (34), a second resistor (36, 38), and a third resistor (40) connected in series in the order of the first resistor, the second resistor, and the third resistor from a high voltage line (14) to a low voltage line (16) for normal discharge of the smoothing capacitor; a discharge control switching element (46) provided on a wiring branching from a connection line between the first resistor and the second resistor and reaching the low voltage line, the discharge control switching element being capable of rapid discharge of the smoothing capacitor via the first resistor; and a control unit (70) for controlling the on / off of the discharge control switching element. and a divided voltage input unit (42, 44) that inputs a divided voltage obtained by dividing the voltage applied to the resistor series circuit when the smoothing capacitor is discharged to the control unit from a connection line between the second resistor and the third resistor.

[0066] (Technical Idea 2) The inverter device according to Technical Idea 1, wherein the control unit determines whether normal discharging of the smoothing capacitor is being performed normally by monitoring the divided voltage input from the divided voltage input unit when normal discharging of the smoothing capacitor is being performed via the resistor series circuit.

[0067] (Technical Idea 3) The inverter device according to Technical Idea 1 or 2, wherein the discharge control switching element (46) includes a first discharge control switching element (48) and a second discharge control switching element (50), and the first discharge control switching element and the second discharge control switching element are connected in series to the wiring.

[0068] (Technical Idea 4) The inverter device according to Technical Idea 3, wherein the second resistors (36, 38) are divided into a first group (36) and a second group (38), a connection line connecting the first discharge control switching element and the second discharge control switching element is connected to a connection line between the first group and the second group of the second resistors, and the control unit turns on the first discharge control switching element and the second discharge control switching element one by one, and when either the first discharge control switching element or the second discharge control switching element is turned on, determines whether the first discharge control switching element and the second discharge control switching element operate normally based on the divided voltage input from the divided voltage input unit.

[0069] (Technical Idea 5) The inverter device described in Technical Idea 4, wherein the control unit determines whether the first discharge control switching element and the second discharge control switching element are operating normally when the moving body starts to move and / or when the moving body ends to move.

[0070] (Technical Idea 6) An inverter device according to Technical Idea 4 or 5, wherein the resistance value of the first group on the first resistor side of the second resistor is equal to or greater than the resistance value of the second group on the third resistor side of the second resistor.

[0071] (Technical Idea 7) An inverter device described in any one of Technical Ideas 4 to 6, wherein the first group on the first resistor side of the second resistor is installed outside the substrate on which the control unit is mounted, and the second group on the third resistor side of the second resistor is mounted on the substrate on which the control unit is mounted.

[0072] (Technical Idea 8) An inverter device described in any one of Technical Ideas 1 to 7, wherein the resistance value of the first resistor is set smaller than the resistance value of the second resistor, and when the discharge control switching element is turned on, rapid discharge is performed from the smoothing capacitor via the first resistor and the discharge control switching element.

[0073] (Technical Concept 9) The inverter device according to Technical Concept 8, wherein the first resistor is disposed outside a substrate on which the control unit is mounted.

[0074] (Technical Idea 10) An inverter device according to any one of Technical Ideas 1 to 9, wherein the third resistor is set to a resistance value smaller than that of the second resistor, and the third resistor is mounted on a substrate on which the control unit is mounted.

Claims

1. An inverter device (10) for driving a motor (60) mounted on a moving body, comprising: an inverter circuit (20) having a plurality of switching elements (22); a smoothing capacitor (18) connected in parallel to the inverter circuit; a resistor series circuit (32) connected in parallel to the smoothing capacitor, in which at least a first resistor (34), a second resistor (36, 38), and a third resistor (40) are connected in series from a high-voltage line (14) to a low-voltage line (16) in the order of the first resistor, the second resistor, and the third resistor, for normal discharge of the smoothing capacitor; a discharge control switching element (46) provided on a wiring branching from a connection line between the first resistor and the second resistor and reaching the low-voltage line, and capable of rapid discharge of the smoothing capacitor via the first resistor; and a control unit (70) for controlling the on / off of the discharge control switching element. and a divided voltage input unit (42, 44) that inputs a divided voltage obtained by dividing the voltage applied to the resistor series circuit when the smoothing capacitor is discharged to the control unit from a connection line between the second resistor and the third resistor.

2. The inverter device of claim 1, wherein the control unit determines whether normal discharge of the smoothing capacitor is being performed normally by monitoring the divided voltage input from the divided voltage input unit when normal discharge of the smoothing capacitor is being performed via the resistor series circuit.

3. The inverter device according to claim 1, wherein the discharge control switching element (46) includes a first discharge control switching element (48) and a second discharge control switching element (50), and the first discharge control switching element and the second discharge control switching element are connected in series to the wiring.

4. The inverter device according to claim 3, wherein the second resistors (36, 38) are divided into a first group (36) and a second group (38), a connection line connecting the first discharge control switching element and the second discharge control switching element is connected to a connection line between the first group and the second group of the second resistors, and the control unit turns on the first discharge control switching element and the second discharge control switching element one by one, and when either the first discharge control switching element or the second discharge control switching element is turned on, determines whether the first discharge control switching element and the second discharge control switching element operate normally based on the divided voltage input from the divided voltage input unit.

5. The inverter device according to claim 4, wherein the control unit determines whether the first discharge control switching element and the second discharge control switching element are operating normally when the moving body starts to move and / or when the moving body stops moving.

6. An inverter device according to claim 4 or 5, wherein the resistance value of the first group on the first resistor side of the second resistor is equal to or greater than the resistance value of the second group on the third resistor side of the second resistor.

7. An inverter device as described in claim 4 or 5, wherein the first group of the second resistors on the first resistor side are installed outside the board on which the control unit is mounted, and the second group of the second resistors on the third resistor side are mounted on the board on which the control unit is mounted.

8. An inverter device as described in any one of claims 1 to 5, wherein the resistance value of the first resistor is set smaller than the resistance value of the second resistor, and when the discharge control switching element is turned on, rapid discharge is performed from the smoothing capacitor via the first resistor and the discharge control switching element.

9. The inverter device according to claim 8, wherein the first resistor is installed outside a substrate on which the control unit is mounted.

10. An inverter device according to any one of claims 1 to 5, wherein the third resistor is set to have a resistance value smaller than that of the second resistor, and the third resistor is mounted on a substrate on which the control unit is mounted.

11. A motor (60) mounted on a mobile object; an inverter circuit (20) having a plurality of switching elements (22) for generating a drive signal for the motor; a smoothing capacitor (18) connected in parallel to the inverter circuit; a resistor series circuit (32) connected in parallel to the smoothing capacitor and including at least a first resistor (34), a second resistor (36, 38), and a third resistor (40) connected in series in the order of the first resistor, the second resistor, and the third resistor from a high-voltage line (14) to a low-voltage line (16) for normal discharge of the smoothing capacitor; a discharge control switching element (46) provided on a wiring branching from a connection line between the first resistor and the second resistor and reaching the low-voltage line, the discharge control switching element being capable of rapid discharge of the smoothing capacitor via the first resistor; and a control unit (70) for controlling the on / off of the plurality of switching elements of the inverter circuit and the discharge control switching element. a divided voltage input unit (42, 44) that divides the voltage applied to the resistor series circuit when the smoothing capacitor is discharged and inputs the divided voltage to the control unit from a connection line between the second resistor and the third resistor.

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