Motor control device and semiconductor unit

Abstract

To provide a motor control device that is prevented from being unable to drive a motor even when a failure occurs in an inverter that controls a battery or a motor current.SOLUTION: A motor control device includes a plurality of semiconductor units including a semiconductor device for driving a motor and a battery for supplying a direct-current power to the semiconductor device. Each of the semiconductor devices of the semiconductor units is electrically connected to the motor in parallel.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a motor control device, and more particularly to a motor control device with improved fault tolerance. [Background technology]

[0002] An inverter that uses a battery as a power source to drive a motor receives DC power from a battery pack consisting of multiple battery cells connected together and a battery consisting of multiple battery packs connected together, converts it into AC power, and supplies the AC power to the motor.

[0003] In today's battery-powered electric vehicles, inverters are used not only to supply current from the battery to the motor, but also to control the charging of the battery with regenerative current from the motor, as disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-283678 Summary of the Invention [Problem to be solved by the invention]

[0005] Conventionally, if a malfunction occurs in the inverter that controls the motor current, it becomes impossible to control the charging and discharging of the motor. For example, in an electric vehicle known as a battery EV (battery electric vehicle), if a malfunction occurs in the inverter, it may become impossible to drive at all, or if regenerative braking is in operation, braking may become less effective.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a motor control device that prevents the motor from becoming unable to be driven even if a malfunction occurs in the battery or the inverter that controls the motor current. [Means for solving the problem]

[0007] A motor control device according to the present disclosure comprises a plurality of semiconductor units each having a semiconductor device that drives a motor and a battery that supplies DC power to the semiconductor device, wherein the semiconductor device of each of the plurality of semiconductor units is electrically connected in parallel to the motor, and each of the plurality of semiconductor units has a control device that controls the semiconductor device, the semiconductor device being an inverter circuit, and the semiconductor device having a voltage sensor that measures the output voltage of the battery, the control device controlling switching elements that constitute the inverter circuit based on the output voltage of the battery measured by the voltage sensor, the control device comparing the output voltage of the battery with a reference voltage input from a higher-level control device, and when the output voltage of the battery is higher than the reference voltage, controlling the switching elements to increase the amount of discharge from the battery. [Effects of the Invention]

[0008] According to the motor control device of the present disclosure, the semiconductor devices of the multiple semiconductor units are electrically connected in parallel to the motor, so that even if a malfunction occurs in the battery or semiconductor device of one of the semiconductor units, it is possible to prevent the motor from becoming unable to be driven, thereby improving fault tolerance. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating a configuration of a motor control device according to a first embodiment. [Figure 2] FIG. 10 is a perspective view showing the configuration of a battery pack of a semiconductor unit according to a second embodiment. [Figure 3] FIG. 10 is a perspective view showing the configuration of a semiconductor unit according to a second embodiment. [Figure 4] 10 is a diagram showing the internal configuration of an inverter unit that constitutes a semiconductor unit according to a second embodiment. FIG. [Figure 5]FIG. 10 is a diagram illustrating the configuration of a motor control device according to a third embodiment. [Figure 6] 10 is a flowchart showing the autonomous control of a unit ECU in the motor control device of the third embodiment. [Figure 7] FIG. 2 is a perspective view showing a schematic configuration of a semiconductor unit mounted on an electric vehicle. [Figure 8] FIG. 10 is a diagram illustrating the configuration of a motor control device according to a fifth embodiment. [Figure 9] FIG. 13 is a cross-sectional view showing the configuration of a semiconductor unit according to a sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] <First Embodiment> Figure 1 is a diagram showing the configuration of a motor control device 100 according to a first embodiment. As shown in Figure 1, the motor control device 100 includes a battery pack BP made up of a combination of multiple battery cells BC, and three semiconductor units UN each having an inverter circuit IV, which is a semiconductor device that receives DC power from the battery pack BP, and the three semiconductor units UN drive one motor MT. Note that in reality, the battery pack BP would have many more battery cells BC, and multiple battery packs BP would be connected in parallel to form a battery; however, for ease of illustration and explanation, the battery is assumed to be made up of one battery pack BP made up of five battery cells BC.

[0011] In the semiconductor unit UN, IGBTs (insulated gate bipolar transistors) 7a and 10a are connected in series, IGBTs 7b and 10b are connected in series, and IGBTs 7c and 10c are connected in series between a main power supply line connected to a P terminal PT on the high potential side connected to the positive electrode of the battery pack BP and a main power supply line connected to an N terminal NT on the low potential side connected to the negative electrode of the battery pack BP. A smoothing capacitor SC is connected in parallel to the battery pack BP.

[0012] The connection node between IGBT7a and IGBT10a is a U-phase output, the connection node between IGBT7b and IGBT10b is a V-phase output, and the connection node between IGBT7c and IGBT10c is a W-phase output, forming a three-phase AC inverter.

[0013] In addition, diodes 8a and 9a are connected in anti-parallel to IGBT7a and IGBT10a, respectively, diodes 8b and 9b are connected in anti-parallel to IGBT7b and IGBT10b, respectively, and diodes 8c and 9c are connected in anti-parallel to IGBT7c and IGBT10c, respectively.

[0014] The U-phase output, V-phase output, and W-phase output of each semiconductor unit UN are connected to the U-phase input, V-phase input, and W-phase input of the motor MT, respectively, and the motor MT is configured with three semiconductor units UN connected in parallel.

[0015] By adopting such a configuration, even if a malfunction occurs in the battery pack BP or the inverter circuit IV and the function of one of the semiconductor units UN is reduced, the other semiconductor units UN can compensate, allowing the motor to continue operating without stopping its function. In particular, when used in an electric vehicle, the function of the motor MT does not stop, making it possible to move the vehicle to a safe location. Note that while FIG. 1 shows a configuration in which one motor MT is driven by three semiconductor units UN, the above-mentioned effects can be achieved by using two or more semiconductor units UN.

[0016] 1, when one motor MT is driven by three semiconductor units UN, if the maximum drive current of the motor MT is 600 A, each inverter circuit IV can have a maximum output current of 200 A. This allows the inverter circuit IV and battery pack BP to be miniaturized, and each semiconductor unit UN can be made smaller.

[0017] <Embodiment 2> Fig. 2 is a perspective view showing the configuration of the battery pack BP of the semiconductor unit UN of the motor control device 100 shown in Fig. 1. As shown in Fig. 2, the battery pack BP is configured such that a plurality of battery cells BC are stacked, and each battery cell BC has a positive electrode PE and a negative electrode NE protruding from one side of the cell.

[0018] In the battery pack BP shown in Fig. 2, the negative electrode NE of the top battery cell BC is connected to the positive electrode PE of the next battery cell BC by a connection plate CB, and thereafter the negative electrode NE of the top battery cell BC is connected to the positive electrode PE of the bottom battery cell BC by a connection plate CB, so that the top battery cell BC and the bottom battery cell BC are electrically connected in series. Note that in Fig. 2, the positive electrode PE of the top battery cell BC and the negative electrode NE of the bottom battery cell BC are not connected to anything, but this will be explained later.

[0019] A stack of multiple battery cells BC is housed in a resin case RC and configured as a single package.

[0020] FIG. 3 shows a semiconductor unit UN in which an inverter unit IVU, a smoothing capacitor SC, and a unit ECU (Electronic Control Unit) 20 that is a control device for the inverter unit IVU are mounted in the battery pack BP shown in FIG.

[0021] 3, the semiconductor unit UN is mounted on the upper surface of the battery pack BP with an inverter unit IVU incorporating an inverter circuit IV, a smoothing capacitor SC, and a unit ECU 20, and capacitor terminals T1 and T2 protrude from the side of the smoothing capacitor SC. Capacitor terminal T1 is connected to the positive electrode PE of the uppermost battery cell BC by a connection plate CB1, and capacitor terminal T2 is connected to the negative electrode NE of the lowermost battery cell BC by a connection plate CB2.

[0022] The capacitor terminals T1 and T2 also protrude from the side surface of the smoothing capacitor SC on the inverter unit IVU side, and are connected to the P-terminal PT (FIG. 1) and N-terminal NT (FIG. 1) in the inverter unit IVU, respectively.

[0023] A U-phase output terminal UT, a V-phase output terminal VT, and a W-phase output terminal WT protrude from the side surface of the inverter unit IVU opposite to the smoothing capacitor SC side.

[0024] The unit ECU 20 includes a control circuit that controls the inverter circuit IV, and the inverter unit IVU, smoothing capacitor SC, and unit ECU 20 are housed in a resin case RC1 to form a single package, and are in close contact with the battery pack BP.

[0025] This allows for a smaller installation space than when the battery and inverter circuit are installed separately. In other words, in a conventional electric vehicle, for example, if the motor's maximum drive current is 600 A, a battery with a capacity of 600 A and an inverter circuit with a rated output of 600 A are installed separately, and the inverter circuit is installed near the motor. This requires a large space for the inverter circuit above the motor. Recently, vehicles with motors installed on the axles have been developed, making it difficult to provide a large space for the inverter circuit above the motor. However, when driving one motor using three semiconductor units UN as shown in Figure 3, by arranging the three semiconductor units UN on the vehicle chassis, a large space for the inverter circuit above the motor is no longer required, thereby reducing the installation space. This allows for a crush zone in the event of an accident, space under the hood, and luggage space to be secured.

[0026] Fig. 4 is a diagram showing the internal configuration of the inverter unit IVU shown in Fig. 3. As shown in Fig. 4, the inverter unit IVU includes a voltage sensor VS connected between the P-terminal PT and the N-terminal NT, a current sensor CS inserted in the main power supply line connected to the P-terminal PT, and a temperature sensor TS provided near, for example, the IGBT 10c.

[0027] The detection outputs of the voltage sensor VS, the current sensor CS, and the temperature sensor TS are input to the unit ECU 20.

[0028] The voltage sensor VS detects the voltage that is the output voltage of the battery pack BP and the input voltage of the inverter circuit IV, and the unit ECU 20 detects the state of charge of the battery pack BP based on the detected voltage and controls the main current of the inverter circuit IV.

[0029] By providing the voltage sensor VS, a battery controller (not shown) provided in the unit ECU 20 can prevent overcharging of the battery. Furthermore, a cell controller provided for each battery cell BC can discharge the battery starting from the most charged cell, thereby enabling uniform consumption of the battery. Furthermore, by preferentially increasing the charging current for cells with low charge levels during charging, charging time can be shortened. The charge and discharge control of the battery pack BP can be performed using known techniques, such as those disclosed in Japanese Patent Application Laid-Open No. 2000-299939.

[0030] Furthermore, by providing the temperature sensor TS, the unit ECU 20 estimates the temperature of the battery pack BP from the difference between the operating temperature of the IGBT detected by the temperature sensor TS and the heat generation amount predicted from the power loss of the IGBT.The unit ECU 20 then controls the main current of the inverter circuit IV based on the estimated temperature, thereby performing appropriate charge / discharge control according to the battery temperature.Furthermore, since there is no need to provide a temperature sensor in the battery pack BP, the battery pack BP can be made smaller and its manufacturing costs can be reduced.

[0031] For example, when the battery pack BP and the inverter unit IVU are in close contact with each other, the temperature change of the IGBT can be calculated as Rth × LW from the thermal resistance Rth (℃ / W) of the IGBT chip and the power loss LW (W) of the IGBT, and the temperature of the battery pack BP can be expressed as T-Rth × LW using the detected IGBT temperature T (℃).

[0032] By implementing such charge / discharge control, it is possible to prevent overheating of each battery pack and overloading at low temperatures with low charge / discharge capacity, suppress deterioration of the battery pack, and prevent the vehicle from stopping due to battery failure in an electric vehicle. Note that, although an example of estimating the temperature of the battery pack BP from the temperature during operation of the IGBT has been described above, charge / discharge control based on the temperature detection of the battery pack can use known techniques such as those disclosed in Japanese Patent Laid-Open Publication No. 2000-299939.

[0033] 4 is shown as a sensor independent of the IGBT, such as a thermistor, but a temperature sensing diode with its cathode connected to the emitter of the IGBT and its anode connected to a temperature sensing terminal can also be used. In this case, the temperature sensing terminal is connected to a current detection circuit provided in the unit ECU 20, and the temperature of the IGBT is calculated from the detected current.

[0034] <Third Embodiment> FIG. 5 is a diagram showing a configuration in which three inverter units IVU shown in FIG. 4 are electrically connected in parallel to a motor (not shown), and each unit ECU 20 is connected to a motor ECU 30 which is a higher-level control device.

[0035] The motor ECU 30 (hereinafter sometimes referred to as "MCU") controls the on-off times (duty) of the switching elements so as to achieve the targets of motor control and battery charge / discharge control. That is, the MCU inputs the duty and reference voltage to each unit ECU 20.

[0036] The unit ECU 20, to which the duty and the reference voltage are input, compares the voltage of the battery pack BP detected by the voltage sensor VS with the reference voltage, and if the actual voltage of the battery pack BP is higher than the reference voltage, for example, if the duty is to control discharging, i.e., to turn on the switching element, the unit ECU 20 changes the duty to lengthen the on-time to discharge more.If the duty is to control charging, the unit ECU 20 changes the duty to shorten the on-time to lengthen the charging path via the diode element.

[0037] By controlling in this way, the control state can be changed independently for each inverter circuit IV, and even if a problem occurs in any of the semiconductor units UN, it is possible to deal with the problem for each semiconductor unit UN.

[0038] Fig. 6 is a flowchart showing the autonomous control of the unit ECU 20 by the motor ECU 30. As shown in Fig. 6, the motor ECU 30 sets a target current to be input to the motor (step S1), and thereafter continuously checks whether there is a difference between the target current and the actual current fed back from the unit ECU 20 (step S2).

[0039] In step S2, if there is a difference between the target current and the actual current (if Yes), a control duty for compensating for the difference is output to each unit ECU 20. If the target current and the actual current match, a control duty for specifying the target current is output, and the process of setting the target current in step S1 is repeated.

[0040] The unit ECU 20 receives the control duty and the reference voltage from the MCU (step S11), compares the voltage of the battery pack BP with the reference voltage (step S12), and if the voltage of the battery pack BP is higher than the reference voltage (Yes), proceeds to step S13, and if it is lower than the reference voltage (No), proceeds to step S14.

[0041] In step S13, the control duty is increased by a predetermined value to lengthen the ON time in order to increase the amount of discharge from the battery pack BP, and the process proceeds to step S17, which prevents the voltage of the battery pack BP from becoming too high.

[0042] In step S14, the voltage of the battery pack BP is compared with the reference voltage, and if the voltage of the battery pack BP is lower than the reference voltage (Yes), the process proceeds to step S15, and if it is the reference voltage (No), the process proceeds to step S16.

[0043] In step S15, the control duty is subtracted by a predetermined value so as to shorten the ON time in order to reduce the amount of discharge from the battery pack BP, and the process proceeds to step S17.

[0044] In step S16, the control duty designated by the MCU is set, and the process proceeds to step S17.

[0045] In step S17, a control duty is applied to each switching element of the inverter circuit IV to control it.

[0046] As a result of the control duty being changed by the unit ECU 20, the actual current flowing through the motor approaches the target current, and the charge / discharge control of the battery is also performed appropriately. The actual current flowing through the motor is detected by a current sensor (not shown) and fed back to the motor ECU 30.

[0047] The above-described control flow is based on the voltage of the battery pack BP detected by the voltage sensor VS, but similar control is also possible using an estimated value of the temperature of the battery pack BP based on the temperature of the switching element, i.e., the IGBT, detected by the temperature sensor TS.

[0048] Furthermore, while the above control flow shows an example of changing the control duty of the switching elements, it is also possible to increase or decrease the power loss of the switching elements by changing the drive frequency, i.e., the switching speed, of the switching elements. That is, the power loss of the switching elements is reduced by lowering the drive frequency and increased by raising the drive frequency. Instead of lengthening the on-time of the switching elements, the drive frequency of the switching elements is increased to increase the power loss and control the battery pack BP to discharge more. This prevents the voltage of the battery pack BP from becoming too high.

[0049] In addition, if the battery pack BP and the inverter unit IVU have a common cooling mechanism, it is also possible to control the cooling capacity of the cooling mechanism, for example, switching the refrigerant flow path or switching the refrigerant flow rate, based on the temperature of the IGBT and an estimated value of the temperature of the battery pack BP based on that temperature.

[0050] <Fourth Embodiment> FIG. 7 is a perspective view showing a schematic configuration when the semiconductor unit UN shown in FIG. 3 is mounted on an electric vehicle, in which three semiconductor units UN are mounted on a chassis CC, and U-phase wiring UL, V-phase wiring VL, and W-phase wiring WL from the three semiconductor units UN are connected to a motor MT mounted on an axle FAX of the front wheels FW.

[0051] By mounting the three semiconductor units UN on the chassis CC in this way, there is no need to provide space for the inverter circuit, which requires a large volume, above the motor MT. This makes it possible to secure a crush zone in the event of an accident, space under the hood, and space for luggage.

[0052] In Figure 7, the motor MT is shown mounted on the axle FAX of the front wheels FW, but it can also be mounted on the axle RAX of the rear wheels RW, or on both the axle FAX of the front wheels FW and the axle RAX of the rear wheels RW. This makes it compatible with rear-wheel drive and four-wheel drive vehicles. It is also possible to use an in-wheel motor, where the motor is built into the wheel (in-wheel). In this case, the crush zone in the event of an accident, the space under the hood, and the luggage loading space can be further expanded.

[0053] <Fifth Embodiment> Fig. 8 is a diagram showing the configuration of a motor control device 100A according to embodiment 5. In Fig. 8, the same components as those in the motor control device 100 described using Fig. 1 are given the same reference numerals, and duplicated explanations will be omitted.

[0054] 8, the motor control device 100A is configured such that a relay switch SW is inserted in U-phase wiring UL, V-phase wiring VL, and W-phase wiring WL that respectively connect the U-phase output, V-phase output, and W-phase output of the semiconductor unit UN to the U-phase input, V-phase input, and W-phase input of the motor MT. The relay switch SW can be a semiconductor switching element or a mechanical switch.

[0055] By adopting such a configuration, if a malfunction occurs in the battery pack BP or inverter circuit IV of any of the semiconductor units UN, the relay switch SW connected to that semiconductor unit UN can be cut off (opened), making it possible to drive the motor MT with the remaining semiconductor units UN, thereby configuring a system with improved fault tolerance.

[0056] Even if a malfunction occurs in one of the semiconductor units UN, the relay switch SW connected to that semiconductor unit UN may not be shut off. That is, as described in the first embodiment, if the maximum drive current of the motor MT is 600 A, each inverter circuit IV can output a maximum current of 200 A. If a malfunction occurs in one of the inverter circuits IV, causing it to output only a maximum current of 100 A, the semiconductor unit UN having that inverter circuit IV is not shut off by the relay switch SW and is used as a semiconductor unit UN that outputs 100 A. This prevents the vehicle from reaching its maximum speed, but allows it to maintain a speed that does not interfere with normal driving. Each semiconductor unit UN is configured to be able to output the maximum drive voltage for the motor MT. Therefore, even if two semiconductor units UN malfunction, the motor MT can be driven by only the remaining semiconductor unit UN, allowing the vehicle to run.

[0057] Furthermore, the number of semiconductor units UN is not limited to three; from the viewpoint of obtaining a fault-tolerant system, a minimum of two is sufficient, and by using three or more units, the maximum output current per unit can be further reduced, resulting in a more robust fault-tolerant system.

[0058] The level at which the output current must drop before the relay switch SW is shut off can be preset in the motor ECU, and the relay switch SW can be controlled at the discretion of the motor ECU.

[0059] <Sixth Embodiment> The semiconductor unit UN shown in Figure 3 has a configuration in which an inverter unit IVU and a smoothing capacitor SC are mounted on a battery pack BP, and the battery pack BP, inverter unit IVU, and smoothing capacitor SC are each provided separately and combined, but it is also possible to provide the battery, inverter, and smoothing capacitor as an integrated unit.

[0060] 9 is a cross-sectional view showing the configuration of a semiconductor unit 10 according to a sixth embodiment. The semiconductor unit 10 includes a semiconductor device 12. The semiconductor device 12 is an IGBT having an emitter formed on its upper surface and a collector formed on its lower surface. A first electrode 16 is electrically connected to the upper surface of the semiconductor device 12 via solder 14. The first electrode 16 functions as an emitter electrode.

[0061] A first internal electrode 18 is electrically connected to the underside of the semiconductor device 12. The first internal electrode 18 has a plurality of first comb-tooth portions 18a and a first connecting portion 18b connecting the plurality of first comb-tooth portions 18a. The comb-tooth portions of the plurality of first comb-tooth portions 18a extend in parallel with each other. One comb tooth of the plurality of first comb-tooth portions is in surface contact with the underside of the semiconductor device 12.

[0062] The second electrode 17 is electrically connected to the first internal electrode 18. The second electrode 17 functions as a collector electrode. A second internal electrode 22 is formed in a position facing the first internal electrode 18. The second internal electrode 22 has a plurality of second comb teeth 22a and a second connecting portion 22b connecting the plurality of second comb teeth 22a. The comb teeth of the plurality of second comb teeth 22a extend parallel to each other. The plurality of second comb teeth 22a do not contact the plurality of first comb teeth 18a but are inserted between the plurality of first comb teeth 18a. In other words, the plurality of first comb teeth 18a and the plurality of second comb teeth 22a are arranged to mesh with each other without contacting each other.

[0063] The gap between the upper first comb teeth 18a and the upper second comb teeth 22a, which are on the semiconductor device 12 side, of the plurality of first comb teeth 18a and the plurality of second comb teeth 22a, is filled with a dielectric 24. The dielectric 24 is made of ceramic. This forms a capacitor having the dielectric 24, the first comb teeth 18a, and the second comb teeth 22a, with the first comb teeth 18a and the second comb teeth 22a as electrodes. The dielectric 24 has a recess 24a.

[0064] The gap between the lower first comb teeth 18a and the lower second comb teeth 22a, which are on the opposite side from the semiconductor device 12, is filled with a solid electrolyte 25. The solid electrolyte 25 is made of ceramic oxide. This forms a battery that includes the solid electrolyte 25, the first comb teeth 18a, and the plurality of second comb teeth 22a, and uses the first comb teeth 18a and the second comb teeth 22a as electrodes.

[0065] The second internal electrode 22 is electrically connected to the lower surface of the first electrode 16. Specifically, one comb tooth of the plurality of second comb tooth portions 22a is electrically connected to the lower surface of the first electrode 16 via solder 26. A resin 30 is formed to cover the semiconductor device 12, the first internal electrode 18, and the second internal electrode 22, and to expose a part of the first electrode 16, a part of the second electrode 17, and a part of the lower dielectric 24 to the outside. The resin 30 is formed by a transfer molding method. The recess 24a mentioned above is formed in a portion that contacts the resin 30, and therefore the recess 24a is filled with the resin 30.

[0066] The semiconductor unit 10 shown in FIG. 9 has a configuration in which a capacitor is formed above a battery, and the battery and capacitor are connected in parallel to the semiconductor device 12.

[0067] Although not shown, the semiconductor device 12 may have a configuration of, for example, a one-phase inverter circuit in which diodes 8a and 9a are connected in anti-parallel to IGBT 7a and IGBT 10a connected in series in the inverter circuit IV shown in FIG. 1, and the semiconductor unit 10 may have a configuration in which a one-phase inverter circuit, a battery, and a capacitor are connected in parallel.

[0068] Three one-phase inverter circuits can be connected in parallel to form the three-phase inverter circuit IV shown in FIG.

[0069] As shown in Figure 9, a configuration in which the capacitor is integrally formed on top of the battery makes it possible to handle sudden charging. That is, since the charging current causes the voltage to rise due to the relationship of resistance x current due to internal resistance, if an excessive current is suddenly passed through a high-resistance part, an overvoltage will occur. Therefore, when charging, the capacitor with low internal resistance, which also serves as a smoothing capacitor, is charged first, and this current is then passed to the battery, making it possible to handle large currents.

[0070] It should be noted that, within the scope of the present disclosure, the embodiments can be freely combined, modified, or omitted as appropriate.

Claims

1. A semiconductor device that drives a motor; a battery for supplying DC power to the semiconductor device; the semiconductor devices of the plurality of semiconductor units are electrically connected in parallel to the motor; Each of the plurality of semiconductor units has a control device that controls the semiconductor device, The semiconductor device is an inverter circuit, the semiconductor device has a voltage sensor for measuring an output voltage of the battery; The control device includes: Controlling a switching element constituting the inverter circuit based on the output voltage of the battery measured by the voltage sensor; The control device includes: A motor control device that compares a reference voltage input from a higher-level control device with the output voltage of the battery, and controls the switching element to increase the amount of discharge from the battery if the output voltage of the battery is higher than the reference voltage.

2. The control device includes:

2. The motor control device according to claim 1, wherein when the output voltage of the battery is higher than the reference voltage, the on-time of the switching element is lengthened to increase the amount of discharge from the battery.

3. The control device includes:

2. The motor control device according to claim 1, wherein when the output voltage of the battery is higher than the reference voltage, the drive frequency of the switching element is increased to increase power loss and thereby increase the amount of discharge from the battery.

4. A semiconductor device; a first electrode electrically connected to an upper surface of the semiconductor device; a first internal electrode having a plurality of first comb teeth and a first connecting portion connecting the plurality of first comb teeth, the first internal electrode being electrically connected to a lower surface of the semiconductor device; A second electrode electrically connected to the first internal electrode; a second internal electrode including a plurality of second comb tooth portions that are not in contact with the plurality of first comb tooth portions but are inserted between the plurality of first comb tooth portions and a second connecting portion that connects the plurality of second comb tooth portions, the second internal electrode being electrically connected to a lower surface of the first electrode; a dielectric material embedded between an upper first comb tooth portion and an upper second comb tooth portion, which are on the semiconductor device side, of the plurality of first comb tooth portions and the plurality of second comb tooth portions; a solid electrolyte embedded between a lower first comb tooth portion and a lower second comb tooth portion, which are on the opposite side to the semiconductor device, of the plurality of first comb tooth portions and the plurality of second comb tooth portions.

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