Control method and control device

Abstract

When determining that a change amount (resistance value change amount)of a resistance value (field winding resistance value) of a field winding of a winding field type rotary electric machine with respect to a predetermined reference field winding resistance value is larger than a reference change amount, a control device according to the present embodiment adjusts an armature winding current value, which is a value of a current flowing through an armature winding of the winding field type rotary electric machine, by using the resistance value change amount.

Description

Control Method and Control Device

[0001] The present invention relates to a control method and a control device.

[0002] Conventionally, various attempts have been made regarding the control of a wound-field type rotating electrical machine including an armature winding and a field winding. For example, Patent Document 1 cited below proposes a field winding type AC rotating electrical machine device that stops the power generation output to the DC power supply side at an early timing in response to the possibility of an abnormal increase in the DC voltage regardless of the presence or absence of excessive voltage generation when the field current cannot be normally controlled.

[0003] Japanese Patent Application Laid-Open No. 2007-189773

[0004] The above-mentioned conventional technology detects the case where the field current cannot be normally controlled as an abnormality in the field circuit, and at the time of detecting the field circuit abnormality, regardless of the presence or absence of excessive voltage generation, either all of the upper arm elements of all phases of the bridge circuit or all of the lower arm elements of all phases are made conductive. Therefore, when the wound-field type rotating electrical machine according to the above-mentioned conventional technology is used as a drive motor of a vehicle, the vehicle will stop when the field current cannot be normally controlled, such as when an inter-turn short circuit occurs in the field winding.

[0005] On one aspect, the present invention has been made in view of such circumstances, and an object thereof is to provide a control method and a control device that suppress the possibility of an electric vehicle stopping even when an inter-turn short circuit occurs in the field winding of a wound-field type rotating electrical machine that constitutes a drive motor mounted as a running drive source in the electric vehicle.

[0006] To solve the above-mentioned problems, a control method according to one aspect of the present invention is a control method for a wound-field rotating electric machine that constitutes a drive motor mounted as a driving source for an electric vehicle. In a control method according to one aspect of the present invention, the processor performs the following steps with respect to the field winding of the wound-field rotating electric machine: estimating the field winding resistance value from a detected field winding current value and a detected field winding voltage value; calculating a resistance change amount that indicates the amount of change of the field winding resistance value estimated in the step of estimating the field winding resistance value with respect to a predetermined reference field winding resistance value; determining whether the resistance change amount calculated in the step of calculating the resistance change amount is greater than a predetermined reference change amount; and, if it is determined in the step of determining whether the resistance change amount is greater than the reference change amount that the resistance change amount is greater than the reference change amount, adjusting the armature winding current value, which is the value of the current that flows through the armature winding of the wound-field rotating electric machine, using the resistance change amount calculated in the step of calculating the resistance change amount.

[0007] According to the present invention, it is possible to provide a control method and control device that suppress the possibility of an electric vehicle stopping even if an interlayer short circuit occurs in the field winding of a wound-field type rotating electric machine that constitutes a drive motor mounted as a driving source for an electric vehicle.

[0008] This is a block diagram showing an example of the schematic configuration of a vehicle equipped with a control device according to the embodiment. Figure 1 illustrates a field winding, comparing an example of a state without inter-layer short circuits with an example of a state with inter-layer short circuits. A schematic example of the hardware configuration of the control device according to the embodiment is shown. A schematic example of the software configuration of the control device according to the embodiment is shown. An example of the processing procedure of the control device according to the embodiment is shown.

[0009] Hereinafter, an embodiment relating to one aspect of the present invention (hereinafter also referred to as "this embodiment") will be described based on the drawings. However, this embodiment described below is merely illustrative in all respects of the present invention. Needless to say, various improvements and modifications can be made without departing from the scope of the present invention. In other words, in carrying out the present invention, specific configurations according to the embodiment may be appropriately adopted. Although the data appearing in this embodiment is described in natural language, more specifically, it is specified in pseudo-language, commands, parameters, machine code, etc., that can be recognized by a computer.

[0010] §1 Application Example Figure 1 is a block diagram showing the schematic configuration of a vehicle VH equipped with a control device (control device 10) according to this embodiment. The vehicle VH is an example of an "electric vehicle (EV)" of the present invention, such as an electric vehicle or a hybrid vehicle. In the example shown in Figure 1, the vehicle VH includes a control device 10, a wound-field rotating electric machine 20, a power supply 30, an inverter 40, a converter 50, and a higher-level ECU (Electronic Control Unit) 60. In the vehicle VH, the control device 10 is communicated with at least the inverter 40, the converter 50, and the higher-level ECU 60, and is communicated with, for example, a CAN (Controller Area Network) or other in-vehicle LAN. Through such connections, the control device 10 can send and receive information with each of the inverter 40, the converter 50, and the higher-level ECU 60.

[0011] The wound-field rotating electric machine 20 is an example of the "wound-field rotating electric machine" of the present invention and constitutes a drive motor mounted on a vehicle VH as a driving source. A wound-field rotating electric machine is an electric motor or generator having an armature winding and a field winding. The wound-field rotating electric machine 20 according to this embodiment is, for example, a wound-field three-phase AC synchronous motor (EESM, Electrically Excited synchronous machine) and comprises a stator having an armature winding 21 (stator winding) and a rotor having a field winding 22 (rotor winding). In the example shown in Figure 1, the wound-field rotating electric machine 20 is provided with three phases of armature windings 21(u), 21(v), and 21(w) for U-phase, V-phase, and W-phase. In this embodiment, when there is no need to distinguish between the armature windings 21(u), 21(v), and 21(w), they may simply be referred to as "armature winding 21".

[0012] The power supply 30 outputs a DC voltage to the inverter 40 and the converter 50. The power supply 30 may be a secondary battery such as a stacked lithium-ion battery, or any device that outputs a DC voltage, such as a DC-DC converter, diode rectifier, or PWM rectifier. The power supply 30 supplies power to drive the wound-field rotating electric machine 20.

[0013] The inverter 40 has multiple switching elements and performs power conversion between the power supply 30 and the armature winding 21. For example, for each phase of the wound-field rotating electric machine 20, the inverter 40 has a series circuit in which a high-potential switching element connected to the high-potential side of the power supply 30 and a low-potential switching element connected to the low-potential side of the power supply 30 are connected in series. The connection point of the two switching elements in each series circuit is connected to the armature winding 21 of the corresponding phase. For example, three sets of series circuits are provided corresponding to the armature winding 21 of each of the three phases. For example, the inverter 40 converts the voltage of the power supply 30 (power supply voltage) into three-phase AC voltages V(u), V(v), and V(w) by driving the switching elements based on a drive signal generated by the control device 10, and supplies them to the wound-field rotating electric machine 20 (especially the armature winding 21). In this embodiment, the control device 10 transmits an armature current command value CAC to the inverter 40, which instructs the inverter 40 to set an armature winding current value ACV, which is the value of the current that the inverter 40 should supply to the armature windings 21 (for example, the armature windings 21 of each phase). Based on the armature current command value CAC received from the control device 10, the inverter 40 supplies a current of the armature winding current value ACV to the armature windings 21 (for example, the armature windings 21 of each phase).

[0014] The converter 50 has a switching element and performs power conversion between the power supply 30 and the field winding 22. In this embodiment, the converter 50 is a half-bridge circuit with a series circuit in which a high-potential switching element connected to the high-potential side of the power supply 30 and a low-potential switching element connected to the low-potential side of the power supply 30 are connected in series. The connection point between the high-potential switching element and the low-potential switching element is connected to one end of the field winding 22, and the low-potential side of the power supply 30 is connected to the other end of the field winding 22. The converter 50 may be a full-bridge circuit with two sets of series circuits, or it may be a chopper circuit with one switching element.

[0015] The higher-level ECU 60 outputs a target output command value, which is the target output of the wound-field type rotating electric machine 20, based on, for example, the accelerator opening angle. In this embodiment, the target torque command value CTT is output as the target output command value. In the example shown in Figure 1, the higher-level ECU 60 outputs the target torque command value CTT to the control device 10.

[0016] The control device 10 is an example of the "control device" of the present invention, and is a control device that controls a wound-field type rotating electric machine 20, for example, a motor ECU that controls the drive motor of a vehicle VH. The control device 10 outputs a current command value for the wound-field type rotating electric machine 20 from the target torque command value CTT output from the higher-level ECU 60. In this embodiment, the control device 10 determines the armature winding current value ACV, which is the value of the current to flow through the armature winding 21, based on the target torque command value CTT and whether or not an interlayer short circuit occurs in the wound-field type rotating electric machine 20 (particularly the field winding 22). The control device 10 then transmits (outputs) an armature current command value CAC, which instructs the determined armature winding current value ACV, to the inverter 40.

[0017] In addition to the control device 10, wound-field rotating electric machine 20, power supply 30, inverter 40, converter 50, and higher-level ECU 60 illustrated in Figure 1, the vehicle VH is equipped with a field current sensor and a field voltage sensor (not shown).

[0018] The field current sensor is a current detection circuit that detects the field winding current, which is the current flowing through the field winding 22. For example, the field current sensor may be provided on the wire connecting the field winding 22 and the converter 50. However, the installation location of the field current sensor is not particularly limited, and the field current sensor may be provided at another location where the field winding current can be detected. For example, the field current sensor may be provided on one terminal of the field winding 22 to detect the field winding current. The output signal of the field current sensor (i.e., a signal indicating the detected value DFC of the field winding current) is input to the control device 10. The field current sensor can be implemented by a current sensor such as a Hall element or a shunt resistor.

[0019] The field voltage sensor is a voltage detection circuit that detects the field winding voltage, which is the voltage applied to the field winding 22. For example, the field voltage sensor may be provided in the converter 50 and detect the voltage between the terminals of the field winding 22. However, the installation location of the field voltage sensor is not particularly limited, and the field voltage sensor may be provided at any other location where the field winding voltage can be detected. The output signal of the field voltage sensor (i.e., a signal indicating the detected value DFV of the field winding voltage) is input to the control device 10.

[0020] Vehicle VH may further include a temperature sensor for detecting the temperature of the field winding 22. Such a temperature sensor may be provided near the wound-field rotating electric machine 20 (especially the field winding 22), or on a refrigerant path through which a refrigerant that cools the wound-field rotating electric machine 20 (especially the field winding 22) flows. Such a temperature sensor may detect the temperature of the wound-field rotating electric machine 20 (e.g., the temperature inside the motor) as the temperature of the field winding 22, or it may detect the temperature of the refrigerant as the temperature of the field winding 22. The temperature sensor may be implemented by, for example, a thermistor.

[0021] (Regarding interlayer short circuits in field windings) Interlayer insulation is provided between the conductors that make up the field winding 22, sandwiching the conductors and insulating them from each other, preventing short-circuit current from flowing between them. However, due to factors such as deterioration or damage to the interlayer insulation, a short circuit between conductors called an interlayer short (layer short, rare short) may occur. In the example shown in Figure 2(B), the insulation of the conductors that make up the field winding 22 is damaged at the insulation damage portion (A) and the insulation damage portion (B), and the insulation between the conductors that make up the field winding 22 is destroyed, causing an interlayer short circuit in the field winding 22. When an interlayer short circuit occurs, current flows by taking a shortcut through the short-circuited area (for example, the part where the insulation is damaged), and in the example shown in Figure 2(B), the current flows by taking a shortcut from the insulation damage portion (A) to the insulation damage portion (B). Therefore, in Figure 2(B), no current (field current) flows through the area indicated by the dotted line, and consequently, the resistance of the field winding 22 decreases. In other words, when an interlayer short circuit occurs, the effective number of turns of the field winding 22 decreases, leading to a decrease in the generated magnetic field and other performance degradation of the wound-field rotating electric machine 20, as well as a decrease in the resistance of the field winding 22.

[0022] (Overview of the control device according to this embodiment) As described above, during operation of the wound-field rotating electric machine 20, current (field winding current) flows through the field winding 22 of the rotor. However, if an interlayer short circuit occurs in the field winding 22, the magnetic field will decrease by the amount by which the number of effective turns decreases (i.e., by the amount of the short circuit). As a result, the wound-field rotating electric machine 20 will be unable to generate the desired motor torque, that is, it will be unable to output the target torque TT corresponding to the target torque command value CTT.

[0023] Therefore, when an interlayer short circuit occurs in the field winding 22 of the wound-field rotating electric machine 20, the control device 10 adjusts the armature winding current value ACV, which is the value of the current flowing through the armature winding 21 of the wound-field rotating electric machine 20, thereby suppressing the effects of a decrease in the magnetic field generated in the field winding 22. When an interlayer short circuit occurs in the field winding 22, the control device 10 increases the armature winding current value ACV, for example, thereby increasing the magnetic field generated in the armature winding 21 and suppressing the effects of a decrease in the magnetic field generated in the field winding 22.

[0024] In this embodiment, the control device 10 first estimates the resistance value of the field winding 22 (field winding resistance value FR). For example, during the operation of the wound-field rotating electric machine 20, the control device 10 estimates the field winding resistance value FR from the detected field winding current DFC and the detected field winding voltage DFV. The control device 10 calculates the resistance change amount AC, which indicates the amount of change (rate of change) of the estimated field winding resistance value FR relative to a predetermined reference field winding resistance value 127. The control device 10 may calculate the resistance change amount AC considering the effect of temperature (for example, the temperature of the field winding 22) on the field winding resistance value FR. The control device 10 determines whether an interlayer short circuit has occurred in the field winding 22 by comparing the calculated resistance change amount AC with a predetermined reference change amount RAC. In this embodiment, the control device 10 determines that an interlayer short circuit has occurred in the field winding 22 if the resistance change amount AC is greater than the reference change amount RAC.

[0025] If the control device 10 determines that an interlayer short circuit has occurred in the field winding 22, it adjusts the armature winding current value ACV, which is the value of the current flowing through the armature winding 21, in order to suppress the effect of the decrease in the magnetic field generated in the field winding 22 caused by the interlayer short circuit. In this embodiment, the control device 10 adjusts the armature winding current value ACV using the resistance change amount AC. For example, the control device 10 adjusts the target torque TT (target torque TT before adjustment) indicated by the target torque command value CTT received from the higher-level ECU 60 using the resistance change amount AC to calculate the adjusted target torque TT. The control device 10 then determines the armature winding current value ACV, which is the value of the current flowing through the armature winding 21, in order to achieve the adjusted target torque TT, as the adjusted armature winding current value ACV adjusted using the resistance change amount AC. In this embodiment, the armature winding current value ACV required to achieve the target torque TT before adjustment is also referred to as the "armature winding current value ACV before adjustment," in contrast to the armature winding current value ACV required to achieve the adjusted target torque TT. The control device 10 generates an armature current command value CAC, which controls the inverter 40 so that the value of the current that the inverter 40 flows through the armature winding 21 becomes the "armature winding current value ACV after adjustment." The control device 10 outputs the generated armature current command value CAC to the inverter 40, thereby flowing a current of the "armature winding current value ACV after adjustment" through the armature winding 21 (for example, the armature winding 21 of each phase).

[0026] Here, the armature current command value CAC corresponding to the adjusted armature winding current value ACV is also referred to as the "adjusted armature current command value CAC" in relation to the armature current command value CAC corresponding to the armature winding current value ACV before adjustment (the armature current command value CAC before adjustment). The adjusted armature current command value CAC is the armature current command value CAC that achieves the adjusted target torque TT, and the armature current command value CAC before adjustment is the armature current command value CAC that achieves the target torque TT before adjustment. Therefore, "adjustment of the armature winding current value ACV using the resistance change amount AC" can be rephrased as "adjustment of the armature current command value CAC using the resistance change amount AC." In other words, it can be understood that "when the control device 10 determines that an interlayer short circuit has occurred in the field winding 22 using the resistance change amount AC, it adjusts the armature current command value CAC using the resistance change amount AC." The control device 10 outputs an adjusted armature current command value CAC, which is adjusted using the resistance change amount AC, to the inverter 40, thereby allowing a current of "adjusted armature winding current value ACV" to flow through the armature windings 21 (for example, the armature windings 21 of each phase).

[0027] As explained above, the control device 10 determines whether an interlayer short circuit has occurred in the field winding 22 based on the change in the resistance value of the field winding 22 (field winding resistance value FR) (resistance change amount AC). If it determines that an interlayer short circuit has occurred in the field winding 22, the control device 10 adjusts the armature winding current value ACV, which is the value of the current that flows through the armature winding 21, using the resistance change amount AC. In other words, even if an interlayer short circuit occurs in the field winding 22, the armature winding 21 will receive the "adjusted armature winding current value ACV" adjusted using the resistance change amount AC, and the wound-field rotating electric machine 20 will not stop. Therefore, the control device 10 can suppress the possibility that the vehicle VH will stop (for example, the vehicle VH will stop unintentionally or unexpectedly by the occupants) even if an interlayer short circuit occurs in the field winding 22 of the wound-field rotating electric machine 20, which constitutes the drive motor mounted on the vehicle VH as a driving source.

[0028] In particular, when an inter-layer short circuit occurs in the field winding 22, the control device 10 increases the magnetic field generated in the armature winding 21, thereby suppressing the effect of the decrease in the magnetic field generated in the field winding 22 caused by the inter-layer short circuit, and thus avoiding and suppressing a decrease in the output of the wound-field type rotating electric machine 20. As described above, when an inter-layer short circuit occurs in the field winding 22, the magnetic field generated in the field winding 22 decreases by the amount by which the number of effective turns decreases (i.e., by the amount of the shortcut), and the resistance value of the field winding 22 (field winding resistance value FR) also decreases. In other words, the decrease in the field winding resistance value FR due to the inter-layer short circuit and the decrease in the magnetic field generated in the field winding 22 caused by the inter-layer short circuit correspond to each other. Furthermore, the resistance value change amount AC, which shows the amount of change in the field winding resistance value FR relative to the reference field winding resistance value 127, also corresponds to the decrease in the magnetic field generated in the field winding 22 caused by the inter-layer short circuit. Therefore, when an interlayer short circuit occurs in the field winding 22, the control device 10 increases the magnetic field generated in the armature winding 21 based on the change in resistance AC corresponding to the decrease in the magnetic field generated in the field winding 22, thereby suppressing the effect of the decrease in the magnetic field generated in the field winding 22 caused by the interlayer short circuit.

[0029] Specifically, in this embodiment, the control device 10 increases the magnetic field generated in the armature winding 21 by adjusting (increasing) the armature winding current ACV using the resistance change AC, thereby suppressing the effect of the decrease in the magnetic field generated in the field winding 22 caused by interlayer short circuits. For example, the control device 10 adjusts the target torque TT before adjustment, indicated by the target torque command value CTT, using the resistance change AC, and calculates the target torque TT after adjustment. The control device 10 then determines the armature winding current ACV that can achieve the target torque TT after adjustment as the armature winding current ACV after adjustment. The control device 10 generates an armature current command value CAC corresponding to the armature winding current ACV after adjustment, and outputs the generated armature current command value CAC to the inverter 40, thereby flowing the current of the armature winding ACV after adjustment through the armature winding 21. The control device 10 can increase the magnetic field generated in the armature winding 21 to compensate for the reduced magnetic field generated in the field winding 22 by adjusting the armature winding current ACV using the resistance change AC corresponding to the decrease in the magnetic field generated in the field winding 22. The control device 10, whose outline has been described above, will now be explained in detail with reference to Figures 3 to 5.

[0030] §2 Configuration Example [Hardware Configuration] Figure 3 schematically shows an example of the hardware configuration of the control device 10 according to this embodiment. As shown in Figure 3, the control device 10 according to this embodiment is a computer in which a control unit 11, a storage unit 12, a communication interface 13, an external interface 14, an input device 15, an output device 16, and a drive 17 are electrically connected. In Figure 3, the communication interface and the external interface are referred to as "communication I / F" and "external I / F" respectively.

[0031] The control unit 11 includes a hardware processor such as a CPU (Central Processing Unit), RAM (Random Access Memory), and ROM (Read Only Memory), and is configured to perform information processing based on a program and various data. The CPU is an example of a processor resource. The storage unit 12 is an example of a memory resource and is composed of, for example, a hard disk drive or a solid-state drive. In this embodiment, the storage unit 12 stores various information such as a control program 121, a reference armature winding current value 123, resistance value-temperature information 125, a reference field winding resistance value 127, and reference change amount information 129.

[0032] The control program 121 is a program that causes the control device 10 to execute the information processing (Figure 5) described later, which controls the armature winding current value ACV, which is the value of the current that flows through the armature winding 21 of the wound-field type rotating electric machine 20. The control program 121 includes a series of instructions for said information processing.

[0033] The reference armature winding current value 123 is a value that the control unit 11 refers to when making a determination about the armature winding current value ACV before adjustment. In other words, the reference armature winding current value 123 is a value that the control unit 11 refers to when making a determination about the armature winding current value ACV required to achieve the target torque TT (target torque TT before adjustment) indicated by the target torque command value CTT received from the higher-level ECU 60. Details of the determination made by the control unit 11 about the armature winding current value ACV before adjustment will be described later.

[0034] The resistance-temperature information 125 shows the relationship between the resistance value of the field winding 22 (field winding resistance value FR) and the temperature of the field winding 22. The resistivity of the field winding 22 is determined by the material of the conductors that make up the field winding 22, but it changes with the temperature of the field winding 22 (the conductors that make up the field winding 22), and generally, the resistivity increases as the temperature rises. Therefore, the control unit 11 can use the resistance-temperature information 125 and the temperature of the field winding 22 to examine the change in the field winding resistance value FR while removing the influence of the temperature of the field winding 22.

[0035] The reference field winding resistance value 127 is a value that the control unit 11 refers to when calculating the resistance change amount AC. The reference field winding resistance value 127 is, for example, the initial resistance value of the field winding 22, and one example is the resistance value of the field winding 22 at the time of factory shipment of vehicle VH.

[0036] The reference change amount information 129 indicates the reference change amount RAC that the control unit 11 refers to when making a determination regarding the resistance change amount AC, which indicates the amount of change in the field winding resistance value FR relative to the reference field winding resistance value 127. In this embodiment, the reference change amount information 129 indicates a first reference change amount RAC1 and a second reference change amount RAC2 that is larger than the first reference change amount RAC1 as the reference change amount RAC. Details of the determination made by the control unit 11 regarding the resistance change amount AC will be described later.

[0037] The communication interface 13 is, for example, a wired LAN (Local Area Network) module, a wireless LAN module, etc., and is an interface for performing wired or wireless communication over a network. As described above, the communication interface 13 may also be an interface for performing communication over a CAN or other in-vehicle LAN. The control device 10 may use this communication interface 13 to perform data communication over a network with other information processing devices. The external interface 14 is, for example, a USB (Universal Serial Bus) port, a dedicated port, etc., and is an interface for connecting to external devices. The type and number of external interfaces 14 may be appropriately selected according to the type and number of external devices to be connected. The control device 10 is connected to, for example, an inverter 40, a converter 50, a higher-level ECU 60, a field current sensor, a field voltage sensor, and a temperature sensor, etc., via at least one of the communication interface 13 and the external interface 14.

[0038] The input device 15 is a device for inputting data, such as a mouse or keyboard. The output device 16 is a device for outputting data, such as a display or speaker. Users or other operators can operate the control device 10 by using the input device 15 and the output device 16.

[0039] The drive 17 is, for example, a CD drive, a DVD drive, etc., and is a drive device for reading various information such as programs stored in the storage medium 91. The storage medium 91 is a medium that stores information such as programs by electrical, magnetic, optical, mechanical, or chemical means so that computers and other devices, machines, etc., can read the stored information such as programs. At least one of the above-mentioned control program 121, reference armature winding current value 123, resistance value-temperature information 125, reference field winding resistance value 127, and reference change amount information 129 may be stored in the storage medium 91. The control device 10 may acquire at least one of the control program 121, reference armature winding current value 123, resistance value-temperature information 125, reference field winding resistance value 127, and reference change amount information 129 from this storage medium 91. In Figure 3, a disk-type storage medium such as a CD or DVD is shown as an example of the storage medium 91. However, the type of storage medium 91 is not limited to disk type; it may be other types. Examples of storage media other than disk type include semiconductor memory such as flash memory. The type of drive 17 may be arbitrarily selected according to the type of storage medium 91.

[0040] Regarding the specific hardware configuration of the control device 10, components can be omitted, replaced, and added as appropriate depending on the embodiment. For example, the processor resources may include multiple hardware processors. The hardware processors may consist of a microprocessor, FPGA (field-programmable gate array), DSP (digital signal processor), etc. The storage unit 12 may consist of RAM and ROM included in the control unit 11. At least one of the communication interface 13, external interface 14, input device 15, output device 16, and drive 17 may be omitted. The control device 10 may consist of multiple computers. In this case, the hardware configuration of each computer may or may not be the same. Furthermore, the control device 10 may be an information processing device designed specifically for the services provided, as well as a general-purpose server device, PC (Personal Computer), etc.

[0041] [Software Configuration] Figure 4 schematically illustrates an example of the software configuration of the control device 10 according to this embodiment. The control unit 11 of the control device 10 loads the control program 121 stored in the memory unit 12 into the RAM. The control unit 11 then uses the CPU to interpret and execute the instructions contained in the control program 121 loaded into the RAM, thereby controlling each component. As shown in Figure 4, the control device 10 according to this embodiment operates as a computer equipped with the following software modules: target torque acquisition unit 110, armature winding current value calculation unit 130, armature winding current value determination unit 140, resistance value estimation unit 150, change amount calculation unit 160, change amount determination unit 170, armature winding current value adjustment unit 180, armature current command value generation unit 181, and output unit 190. In other words, in this embodiment, each software module of the control device 10 is implemented by the control unit 11 (CPU).

[0042] The target torque acquisition unit 110 acquires a target output command value indicating the target output of the wound-field type rotating electric machine 20. In the present embodiment, the target torque acquisition unit 110 acquires a target torque command value CTT indicating the target torque TT (the target torque TT before adjustment) of the wound-field type rotating electric machine 20 from the upper ECU 60.

[0043] The armature winding current value calculation unit 130 calculates an armature winding current value ACV (the armature winding current value ACV before adjustment), which is the value of the current flowing through the armature winding 21 of the wound-field type rotating electric machine 20, from the target output indicated by the target output command value acquired by the target torque acquisition unit 110. In the present embodiment, the armature winding current value calculation unit 130 calculates the armature winding current value ACV before adjustment from the target torque TT indicated by the target torque command value CTT. In other words, the armature winding current value calculation unit 130 calculates the armature winding current value ACV before adjustment, assuming that the torque output by the wound-field type rotating electric machine 20 is the "target torque TT before adjustment".

[0044] The armature winding current value determination unit 140 determines whether the armature winding current value ACV (the armature winding current value ACV before adjustment) calculated by the armature winding current value calculation unit 130 is smaller than a predetermined reference armature winding current value 123. For example, the armature winding current value determination unit 140 acquires the reference armature winding current value 123 by referring to the storage unit 12. Then, the armature winding current value determination unit 140 may determine whether the armature winding current value ACV before adjustment is smaller than the reference armature winding current value 123 by comparing the acquired reference armature winding current value 123 with the armature winding current value ACV calculated by the armature winding current value calculation unit 130. The armature winding current value determination unit 140 notifies the armature winding current value adjustment unit 180 of the result of the above determination.

[0045] The resistance estimation unit 150 estimates the resistance value of the field winding 22 (field winding resistance value FR). In this embodiment, the resistance estimation unit 150 estimates the field winding resistance value FR each time the vehicle VH is started (at least one of the power supply and ignition is turned on) while the wound-field type rotating electric machine 20 is in operation. For example, the resistance estimation unit 150 obtains the detected field winding current DFC from the field current sensor and the detected field winding voltage DFV from the field voltage sensor. The resistance estimation unit 150 estimates the field winding resistance value FR from the obtained detected field winding current DFC and field winding voltage DFV. For example, the resistance estimation unit 150 estimates the field winding resistance value FR by dividing the detected value DFV by the detected value DFC.

[0046] The change amount calculation unit 160 calculates a resistance change amount AC, which indicates the change in the field winding resistance value FR estimated by the resistance value estimation unit 150 relative to the reference field winding resistance value 127. For example, the change amount calculation unit 160 obtains the reference field winding resistance value 127 by referring to the storage unit 12. Then, the change amount calculation unit 160 may calculate the resistance change amount AC by dividing the field winding resistance value FR estimated by the resistance value estimation unit 150 by the obtained reference field winding resistance value 127. However, the method of calculating the resistance change amount AC is not limited to this, and for example, the change amount calculation unit 160 may calculate the resistance change amount AC as the difference between the reference field winding resistance value 127 and the field winding resistance value FR. The change amount calculation unit 160 notifies the change amount determination unit 170 of the calculated resistance change amount AC.

[0047] Here, the coils (armature winding 21, field winding 22) of the wound-field rotating electric machine 20 generate heat when current flows through them, and furthermore, the structure is prone to heat buildup, which exacerbates the heat generation. Also, as mentioned above, the resistance value of the conductor coil has the characteristic of changing with temperature. In other words, in the wound-field rotating electric machine 20 during operation, even when no abnormalities such as inter-layer short circuits occur, the resistance value of the field winding 22 (field winding resistance value FR) changes depending on the temperature of the field winding 22. For example, the higher the temperature of the field winding 22, the higher the field winding resistance value FR becomes. Therefore, if only the field winding resistance value FR is monitored, it is difficult to distinguish whether the change in the field winding resistance value FR is due to temperature change or inter-layer short circuit. Therefore, the change amount calculation unit 160 may calculate the resistance value change amount AC considering the temperature of the field winding 22. The change amount calculation unit 160 can accurately calculate the resistance change amount AC by considering the temperature of the field winding 22, thereby eliminating the effect of the temperature of the field winding 22 on the field winding resistance value FR. In other words, the change amount calculation unit 160 can accurately calculate the resistance change amount AC by considering the temperature of the field winding 22, thereby eliminating the change in the field winding resistance value FR caused by temperature changes. In the example shown in Figure 4, the change amount calculation unit 160 includes a resistance adjustment unit 161.

[0048] The resistance value adjustment unit 161 adjusts the field winding resistance value FR estimated by the resistance value estimation unit 150 using the temperature of the field winding 22. For example, the resistance value adjustment unit 161 refers to the storage unit 12 to obtain the resistance value - temperature information 125, and also obtains the temperature of the field winding 22 (information indicating such temperature) from the temperature sensor. Then, the resistance value adjustment unit 161 determines the adjustment amount for the field winding resistance value FR from the obtained resistance value - temperature information 125 and the temperature of the field winding 22, and adjusts the field winding resistance value FR using the determined adjustment amount, thereby obtaining the adjusted field winding resistance value FR. The adjusted field winding resistance value FR may be understood as "the resistance value of the field winding 22 with the influence from the temperature of the field winding 22 removed". The change amount calculation unit 160 may calculate a resistance value change amount AC indicating the change amount with respect to the reference field winding resistance value 127 for the adjusted field winding resistance value FR adjusted using the temperature of the field winding 22 by the resistance value adjustment unit 161. That is, the change amount calculation unit 160 may calculate the resistance value change amount AC in consideration of the temperature of the field winding 22. For example, the change amount calculation unit 160 may calculate the resistance value change amount AC for the adjusted field winding resistance value FR by dividing the adjusted field winding resistance value FR by the reference field winding resistance value 127.

[0049] By calculating the resistance value change amount AC for the adjusted field winding resistance value FR adjusted using the temperature of the field winding 22, the change amount calculation unit 160 can calculate the resistance value change amount AC with the influence of "the change in the field winding resistance value FR due to temperature change" removed. In other words, by calculating the resistance value change amount AC for the adjusted field winding resistance value FR adjusted using the temperature of the field winding 22, the change amount calculation unit 160 can calculate the resistance value change amount AC that reflects only "the change in the field winding resistance value FR due to inter - turn short - circuit". And by using the resistance value change amount AC calculated for the adjusted field winding resistance value FR, the control device 10 can remove the influence of the temperature of the field winding 22 and accurately determine whether an inter - turn short - circuit has occurred in the field winding 22.

[0050] The change amount determination unit 170 determines whether the resistance change amount AC calculated by the change amount calculation unit 160 is greater than the reference change amount RAC. The resistance change amount AC calculated by the change amount calculation unit 160 may be the resistance change amount AC calculated for "the (pre-adjustment) field winding resistance value FR, which is estimated by dividing the detected field winding voltage DFV by the detected field winding current DFC." The resistance change amount AC calculated by the change amount calculation unit 160 may be the resistance change amount AC calculated for "the adjusted field winding resistance value FR, which is adjusted using the temperature of the field winding 22." For example, the change amount determination unit 170 may refer to the storage unit 12 to obtain reference change amount information 129. Then, the change amount determination unit 170 may determine whether the resistance change amount AC is greater than the reference change amount RAC by comparing the reference change amount RAC indicated by the obtained reference change amount information 129 with the resistance change amount AC calculated by the change amount calculation unit 160. In the example shown in Figure 4, the change amount determination unit 170 includes a first determination unit 171 and a second determination unit 173.

[0051] The first determination unit 171 determines whether the resistance change amount AC is greater than the first reference change amount RAC1, for example by comparing the first reference change amount RAC1 indicated by the reference change amount information 129 with the resistance change amount AC calculated by the change amount calculation unit 160. The second determination unit 173 determines whether the resistance change amount AC is greater than the second reference change amount RAC2, for example by comparing the second reference change amount RAC2 indicated by the reference change amount information 129 with the resistance change amount AC calculated by the change amount calculation unit 160. The change amount determination unit 170 (first determination unit 171 and second determination unit 173) notifies the armature winding current value adjustment unit 180 and output unit 190 of the results of the above determinations.

[0052] The first reference change RAC1 is, for example, an index for determining whether or not an interlayer short circuit has occurred in the field winding 22. The second reference change RAC2, which is larger than the first reference change RAC1, is, for example, an index indicating whether the effect of the decrease in the magnetic field generated in the field winding 22 due to the interlayer short circuit can be suppressed by increasing the magnetic field generated in the armature winding 21. The second reference change RAC2 may also be an index indicating whether the effect of the decrease in the magnetic field generated in the field winding 22 due to the interlayer short circuit can be suppressed by adjusting (increasing) the armature winding current value ACV. In other words, the second reference change RAC2 may also be an index indicating whether or not the occupants, such as the driver of the vehicle VH, should be urged to stop the vehicle VH.

[0053] If the change amount determination unit 170 determines that "the resistance change amount AC is greater than the reference change amount RAC (especially the first reference change amount RAC1)", the armature winding current value adjustment unit 180 adjusts the armature winding current value ACV before adjustment using the resistance change amount AC. For example, the armature winding current value adjustment unit 180 adjusts the (pre-adjustment) armature winding current value ACV calculated by the armature winding current value calculation unit 130 using the resistance change amount AC calculated by the change amount calculation unit 160 to generate the armature winding current value ACV after adjustment. The armature winding current value adjustment unit 180 notifies the armature current command value generation unit 181 of the generated "adjusted armature winding current value ACV".

[0054] In this embodiment, the armature winding current value adjustment unit 180 first adjusts the "target torque TT before adjustment," indicated by the target torque command value CTT acquired by the target torque acquisition unit 110, using the resistance change amount AC, and calculates the "target torque TT after adjustment." For example, the armature winding current value adjustment unit 180 calculates the target torque TT after adjustment by multiplying the target torque TT before adjustment by the reciprocal of the resistance change amount AC. Then, the armature winding current value adjustment unit 180 determines the armature winding current value ACV that can achieve the target torque TT after adjustment as the "armature winding current value ACV after adjustment." However, the method of adjusting the armature winding current value ACV using the resistance change amount AC is not limited to the example described above. The armature winding current value adjustment unit 180 should be able to adjust the armature winding current value ACV using a resistance change amount AC corresponding to the decrease in the magnetic field generated in the field winding 22, so as to suppress the effect of the decrease in the magnetic field generated in the field winding 22 caused by the interlayer short circuit. The armature winding current value adjustment unit 180 should be able to increase the magnetic field generated in the armature winding 21 to compensate for the decrease in the magnetic field generated in the field winding 22, so as to avoid and suppress the decrease in the output torque of the wound-field type rotating electric machine 20 caused by the interlayer short circuit. For example, the armature winding current value adjustment unit 180 may use a resistance change amount AC to specify the amount of increase in the magnetic field generated in the armature winding 21 that can compensate for the decrease in the magnetic field generated in the field winding 22. Furthermore, the armature winding current value adjustment unit 180 may calculate the armature winding current value ACV that can achieve the specified increase as "the adjusted armature winding current value ACV adjusted using the resistance change amount AC".

[0055] If the change amount determination unit 170 determines that "the resistance change amount AC is less than or equal to the first reference change amount RAC1", the armature winding current value adjustment unit 180 does not adjust (change) the armature winding current value ACV (before adjustment) calculated by the armature winding current value calculation unit 130. If the resistance change amount AC is less than or equal to the first reference change amount RAC1, it is considered that no interlayer short circuit has occurred in the field winding 22, so the armature winding current value adjustment unit 180 does not adjust the armature winding current value ACV (before adjustment) calculated by the armature winding current value calculation unit 130.

[0056] Furthermore, if the armature winding current value determination unit 140 determines that "the armature winding current value ACV before adjustment is smaller than the reference armature winding current value 123", the armature winding current value adjustment unit 180 will not adjust the armature winding current value ACV before adjustment. If the armature winding current value determination unit 140 determines that "the armature winding current value ACV before adjustment is smaller than the reference armature winding current value 123", the armature winding current value adjustment unit 180 will not adjust the armature winding current value ACV before adjustment, even if the change amount determination unit 170 determines that "the resistance change amount AC is larger than the reference change amount RAC (especially the first reference change amount RAC1)". For example, the armature winding current value adjustment unit 180 adjusts the armature winding current value ACV before adjustment using the resistance change amount AC only if the armature winding current value determination unit 140 determines that "the armature winding current value ACV before adjustment is equal to or greater than the reference armature winding current value 123", and the change amount determination unit 170 determines that "the resistance change amount AC is greater than the reference change amount RAC (especially the first reference change amount RAC1)".

[0057] Here, if the armature winding current value ACV calculated by the armature winding current value calculation unit 130 from the (pre-adjustment) target torque TT is smaller than the reference armature winding current value 123, then the pre-adjustment target torque TT should also be "sufficiently small (not significantly large)." And, if the "target torque TT is sufficiently small," then it is considered that situations that place a high load on the vehicle VH, such as suddenly stopping or accelerating the vehicle VH for emergency avoidance, have not occurred. Therefore, if the pre-adjustment target torque TT is sufficiently small, even if an interlayer short circuit occurs in the field winding 22 and the "magnetic field generated in the field winding 22" decreases, there is little need to increase the "magnetic field generated in the armature winding 21" to avoid or suppress a decrease in the output of the wound-field type rotating electric machine 20. In other words, when the target torque TT before adjustment is sufficiently small, specifically when the armature winding current ACV before adjustment is smaller than the reference armature winding current 123, even if an interlayer short circuit occurs in the field winding 22, there is little need to adjust the armature winding current ACV before adjustment using the resistance change AC.

[0058] Furthermore, if the armature winding current value ACV before adjustment is adjusted using the resistance change amount AC, the current flowing through the armature winding 21 increases, making the wound-field type rotating electric machine 20 (especially the armature winding 21) more prone to overheating, and thus increasing the thermal load on the wound-field type rotating electric machine 20.

[0059] Therefore, if the control device 10 determines that the armature winding current value ACV before adjustment is smaller than the reference armature winding current value 123, the control device 10 does not perform "adjustment using resistance change amount AC" for the armature winding current value ACV before adjustment. In other words, if the target torque TT before adjustment is smaller than a predetermined value (a predetermined torque value corresponding to the reference armature winding current value 123), the control device 10 does not perform "adjustment using resistance change amount AC" for the armature winding current value ACV before adjustment. To put it another way, if the armature current command value CAC before adjustment is smaller than a predetermined value (a predetermined current command value corresponding to the reference armature winding current value 123), the control device 10 does not perform "adjustment using resistance change amount AC" for the armature winding current value ACV before adjustment. Through this control, the control device 10 can avoid the situation of "adjusting the armature winding current value ACV to increase the thermal load of the wound-field type rotating electric machine 20" when there is little need to avoid or suppress the output reduction of the wound-field type rotating electric machine 20 caused by an interlayer short circuit of the field winding 22.

[0060] The armature current command value generation unit 181 generates an armature current command value CAC that corresponds to the armature winding current value ACV before adjustment or the armature winding current value ACV after adjustment. In this embodiment, the armature current command value generation unit 181 generates an armature current command value CAC that corresponds to the armature winding current value ACV notified by the armature winding current value adjustment unit 180. For example, if the resistance change amount AC is greater than the reference change amount RAC (especially the first reference change amount RAC1), the armature current command value generation unit 181 generates an armature current command value CAC that corresponds to the "adjusted armature winding current value ACV" notified by the armature winding current value adjustment unit 180. If the resistance change AC is less than or equal to the reference change RAC, the armature current command value generation unit 181 generates an armature current command value CAC corresponding to the "armature winding current value ACV before adjustment" notified by the armature winding current value adjustment unit 180. If the armature winding current value ACV before adjustment is less than the reference armature winding current value 123, the armature current command value generation unit 181 generates an armature current command value CAC corresponding to the "armature winding current value ACV before adjustment" notified by the armature winding current value adjustment unit 180.

[0061] The armature current command value generation unit 181 then outputs the generated armature current command value CAC to the inverter 40, thereby supplying a current of either the "armature winding current value ACV before adjustment" or the "armature winding current value ACV after adjustment" to the armature windings 21 (for example, the armature windings 21 of each phase).

[0062] The armature current command value CAC corresponding to the armature winding current value ACV before adjustment may be referred to as the "armature current command value CAC before adjustment." The armature current command value CAC before adjustment is the armature current command value CAC required to achieve the target torque TT indicated by the target torque command value CTT (target torque TT before adjustment). Similarly, the armature current command value CAC corresponding to the armature winding current value ACV after adjustment may be referred to as the "armature current command value CAC after adjustment." The armature current command value CAC after adjustment is the armature current command value CAC obtained by adjusting the armature current command value CAC before adjustment using the resistance change amount AC. Specifically, the armature current command value CAC after adjustment is the armature current command value CAC required to achieve the "target torque TT after adjustment, which is obtained by adjusting the target torque TT before adjustment using the resistance change amount AC." Therefore, it may be understood that "when the control device 10 determines that an interlayer short circuit has occurred in the field winding 22, it adjusts the armature current command value CAC using the resistance change amount AC." If no interlayer short circuit has occurred in the field winding 22, the armature current command value generation unit 181 may generate an armature current command value CAC before adjustment, which controls the inverter 40 so that "the value of the current that the inverter 40 flows through the armature winding 21 becomes "the armature winding current value ACV before adjustment." If an interlayer short circuit has occurred in the field winding 22, the armature current command value generation unit 181 may generate an armature current command value CAC after adjustment, which controls the inverter 40 so that "the value of the current that the inverter 40 flows through the armature winding 21 becomes "the armature winding current value ACV after adjustment."

[0063] If the change amount determination unit 170 determines that "the resistance change amount AC is greater than the first reference change amount RAC1", the output unit 190 outputs a first warning signal WS1 indicating that an interlayer short circuit has occurred in the field winding 22. Furthermore, if the change amount determination unit 170 determines that "the resistance change amount AC is greater than the second reference change amount RAC2", the output unit 190 outputs a second warning signal WS2 prompting the vehicle VH to be stopped.

[0064] As described above, the first reference change amount RAC1 is an indicator for determining, for example, whether or not an inter-layer short circuit has occurred in the field winding 22. The second reference change amount RAC2 is an indicator for showing, for example, whether the effect of the decrease in the magnetic field generated in the field winding 22 due to the inter-layer short circuit can be suppressed by increasing the magnetic field generated in the armature winding 21 (in other words, by adjusting the armature winding current value ACV). Therefore, if the resistance change amount AC is greater than the first reference change amount RAC1, the control device 10 determines that an inter-layer short circuit has occurred in the field winding 22 and performs the following processing. That is, the control device 10 suppresses the effect of the decrease in the magnetic field generated in the field winding 22 by adjusting the armature winding current value ACV, operates the wound-field type rotating electric machine 20, and outputs the first warning signal WS1 to notify and warn the occupants of the vehicle VH of the occurrence of an inter-layer short circuit. The control device 10 may output a first warning signal WS1 to prompt the occupants of the vehicle VH to repair the field winding 22, etc. Also, if the resistance change amount AC is greater than the second reference change amount RAC2, the control device 10 determines that "the effect of the decrease in the magnetic field generated in the field winding 22 due to the interlayer short circuit cannot be suppressed by the increase in the magnetic field generated in the armature winding 21." Therefore, the control device 10 prompts the occupants of the vehicle VH to stop the vehicle VH, for example, by prompting them to stop the vehicle VH immediately. The control device 10 distinguishes between the first warning signal WS1, which notifies of the occurrence of an interlayer short circuit (which does not require stopping the vehicle VH), and the second warning signal WS2, which guides the occupants to stop the vehicle VH. The control device 10 can avoid situations in which the vehicle VH suddenly becomes inoperable (for example, a situation in which the vehicle VH stops unintentionally or unexpectedly by the occupants) by issuing warnings in stages from the first warning signal WS1 to the second warning signal WS2.

[0065] §3 Operation Example Figure 5 is a flowchart showing an example of the processing procedure of the control device 10 according to this embodiment. The processing procedure described below is an example of the processing procedure of the control method CM which "controls the armature winding current value ACV, which is the value of the current flowing through the armature winding 21 of the wound-field type rotating electric machine 20". However, the processing procedure described below is merely an example, and each step may be changed as much as possible. Furthermore, steps in the processing procedure described below can be omitted, replaced, and added as appropriate, depending on the embodiment.

[0066] (Step S110) In step S110, the control unit 11 operates as a target torque acquisition unit 110 and acquires the target torque command value CTT. For example, the control unit 11 acquires the target torque command value CTT, which indicates the target torque TT (target torque TT before adjustment), from the higher-level ECU 60.

[0067] (Step S120) In step S120, the control unit 11 operates as an armature winding current value calculation unit 130 and calculates the armature winding current value ACV (armature winding current value ACV before adjustment) from the target torque indicated by the target torque command value CTT acquired in step S110.

[0068] (Step S130) In step S130, the control unit 11 operates as an armature winding current value determination unit 140 and determines whether the armature winding current value ACV calculated in step S120 is less than the reference armature winding current value 123. The control unit 11 may, for example, obtain the reference armature winding current value 123 by referring to the storage unit 12, and perform the above determination by comparing the obtained reference armature winding current value 123 with the armature winding current value ACV calculated in step S120. If it is determined that the armature winding current value ACV (before adjustment) is less than the reference armature winding current value 123 (Yes in step S130), the control unit 11 proceeds to step S140. If it is determined that the armature winding current value ACV (before adjustment) is greater than or equal to the reference armature winding current value 123 (No in step S130), the control unit 11 proceeds to step S150.

[0069] (Step S140) In step S140, the control unit 11 operates as an armature current command value generation unit 181 and outputs an armature current command value CAC corresponding to the armature winding current value ACV (armature winding current value ACV before adjustment) calculated in step S120. In other words, if the armature winding current value ACV before adjustment is smaller than the reference armature winding current value 123, the control unit 11 does not execute the process in step S210, regardless of the result of the determination in step S190 described later. Specifically, if the armature winding current value ACV before adjustment is smaller than the reference armature winding current value 123, the control unit 11 does not execute the "adjustment of the armature winding current value ACV using the resistance change amount AC" in step S210, even if it determines in step S190 that "the resistance change amount AC is larger than the reference change amount RAC (especially the first reference change amount RAC1)". If the armature winding current value ACV before adjustment is less than the reference armature winding current value 123, the control unit 11 outputs the armature current command value CAC before adjustment, which corresponds to the armature winding current value ACV before adjustment, to the inverter 40.

[0070] (Step S150) In step S150, the control unit 11 operates as a resistance value estimation unit 150 and acquires the detected field winding current DFC and the detected field winding voltage DFV. For example, the control unit 11 acquires the detected field winding current DFC from the field current sensor and the detected field winding voltage DFV from the field voltage sensor.

[0071] (Step S160) In step S160, the control unit 11 operates as a resistance value estimation unit 150 and estimates the field winding resistance value FR from the detected field winding current DFC and the detected field winding voltage DFV obtained in step S150. For example, the control unit 11 estimates the field winding resistance value FR by dividing the detected value DFV by the detected value DFC.

[0072] (Step S170) In step S170, the control unit 11 operates as a change amount calculation unit 160 (particularly a resistance value adjustment unit 161) and adjusts the field winding resistance value FR estimated in step S160 using the temperature of the field winding 22. For example, the control unit 11 obtains resistance value-temperature information 125 by referring to the storage unit 12, and also obtains the temperature of the field winding 22 (information indicating the temperature of the field winding 22) from the temperature sensor. Then, the control unit 11 may determine an adjustment amount for the field winding resistance value FR from the obtained resistance value-temperature information 125 and the temperature of the field winding 22, and obtain the adjusted field winding resistance value FR by adjusting the field winding resistance value FR using the determined adjustment amount. Note that in the control method CM, it is not essential for the control unit 11 to execute the process in step S170.

[0073] (Step S180) In step S180, the control unit 11 operates as a change amount calculation unit 160 and calculates the change amount (resistance change amount AC) of the field winding resistance value FR with respect to the reference field winding resistance value 127. For example, the control unit 11 calculates the change amount (resistance change amount AC) with respect to the reference field winding resistance value 127 for the adjusted field winding resistance value FR adjusted in step S170 using the temperature of the field winding 22. For example, the control unit 11 may obtain the reference field winding resistance value 127 by referring to the storage unit 12, and calculate the resistance change amount AC by dividing the adjusted field winding resistance value FR adjusted in step S170 by the obtained reference field winding resistance value 127. Here, as described above, it is not essential for the control unit 11 to execute the process in step S170 in the control method CM. If the control unit 11 does not perform the processing in step S170, in step S180 the control unit 11 may calculate a resistance change AC, which represents the amount of change in the field winding resistance value FR estimated in step S160 relative to the reference field winding resistance value 127.

[0074] (Step S190) In step S190, the control unit 11 operates as a change amount determination unit 170 and determines whether the resistance change amount AC calculated in step S180 is greater than the reference change amount RAC (especially the first reference change amount RAC1). The control unit 11 may, for example, refer to the storage unit 12 to obtain reference change amount information 129, and perform the above determination by comparing the first reference change amount RAC1 indicated by the obtained reference change amount information 129 with the resistance change amount AC calculated in step S180. If it is determined that the resistance change amount AC is greater than the first reference change amount RAC1 (Yes in step S190), the control unit 11 proceeds to step S210. If it is determined that the resistance change amount AC is less than or equal to the first reference change amount RAC1 (No in step S190), the control unit 11 proceeds to step S140.

[0075] (Step S210) In step S210, the control unit 11 operates as an armature winding current value adjustment unit 180 and adjusts the armature winding current value ACV (armature winding current value ACV before adjustment) calculated in step S120 using the resistance change amount AC calculated in step S180. For example, the control unit 11 first adjusts the "target torque TT before adjustment" indicated by the target torque command value CTT acquired in step S110 using the resistance change amount AC to calculate the "target torque TT after adjustment". Then, the control unit 11 determines the armature winding current value ACV that can achieve the "target torque TT after adjustment" as the "armature winding current value ACV after adjustment".

[0076] (Step S220) In step S220, the control unit 11 operates as an armature current command value generation unit 181 and outputs an armature current command value CAC that corresponds to the adjusted armature winding current value ACV adjusted in step S210 using the resistance change amount AC. For example, the control unit 11 generates an adjusted armature current command value CAC that controls the inverter 40 so that the value of the current that the inverter 40 flows through the armature winding 21 becomes the "adjusted armature winding current value ACV". Then, the control unit 11 outputs the generated adjusted armature current command value CAC to the inverter 40, thereby flowing a current of the "adjusted armature winding current value ACV" through the armature winding 21 (for example, the armature winding 21 of each phase).

[0077] (Step S230) In step S230, the control unit 11 operates as an output unit 190 and outputs a first warning signal WS1. As described above, the first warning signal WS1 indicates that an interlayer short circuit has occurred in the field winding 22, prompting, for example, the occupants of the vehicle VH to repair the field winding 22.

[0078] The control unit 11 may further determine whether the resistance change amount AC calculated in step S180 is greater than the second reference change amount RAC2. The control unit 11 may, for example, obtain reference change amount information 129 by referring to the storage unit 12, and perform the above determination by comparing the second reference change amount RAC2 indicated by the obtained reference change amount information 129 with the resistance change amount AC calculated in step S180. If the control unit 11 determines that the resistance change amount AC is greater than the second reference change amount RAC2, it may output a second warning signal WS2 prompting the vehicle VH to stop.

[0079] [Features] As described above, the control device 10 according to this embodiment is a control device for a wound-field type rotating electric machine 20 that constitutes a drive motor mounted on a vehicle VH (electric vehicle) as a driving source. The control device 10 includes a resistance value estimation unit 150, a change amount calculation unit 160, a change amount determination unit 170, and an armature winding current value adjustment unit 180. The resistance value estimation unit 150 estimates the field winding resistance value FR of the field winding 22 of the wound-field type rotating electric machine 20 from the detected field winding current value DFC and the detected field winding voltage value DFV. The change amount calculation unit 160 calculates a resistance value change amount AC, which indicates the change amount relative to a predetermined reference field winding resistance value 127, for the field winding resistance value FR estimated by the resistance value estimation unit 150. The change amount determination unit 170 determines whether the resistance change amount AC calculated by the change amount calculation unit 160 is greater than a predetermined reference change amount RAC (especially the first reference change amount RAC1). If the change amount determination unit 170 determines that "the resistance change amount AC is greater than the first reference change amount RAC1", the armature winding current value adjustment unit 180 adjusts the armature winding current value ACV, which is the value of the current that flows through the armature winding 21 of the wound-field type rotating electric machine 20, using the resistance change amount AC calculated by the change amount calculation unit 160.

[0080] The control method CM according to this embodiment is a control method for a wound-field type rotating electric machine 20 that constitutes a drive motor mounted on a vehicle VH as a driving source. The control method CM causes a processor (for example, the control unit 11 of the control device 10) to execute steps S160, S180, S190, and S210 as illustrated in Figure 5. In step S160, the processor estimates the field winding resistance value FR of the field winding 22 of the wound-field type rotating electric machine 20 from the detected field winding current value DFC and the detected field winding voltage value DFV. In step S180, the processor calculates a resistance change amount AC, which indicates the amount of change relative to a predetermined reference field winding resistance value 127, for the field winding resistance value FR estimated in step S160. In step S190, the processor determines whether the resistance change amount AC calculated in step S180 is greater than a predetermined reference change amount RAC (especially the first reference change amount RAC1). If it determines that the resistance change amount AC is greater than the first reference change amount RAC1 (Yes in step S190), the control unit 11 proceeds to step S210. In step S210, the processor adjusts the armature winding current value ACV, which is the value of the current flowing through the armature winding 21 of the wound-field type rotating electric machine 20, using the resistance change amount AC calculated in step S180.

[0081] The control device 10 (control method CM) determines whether an interlayer short circuit has occurred in the field winding 22 based on the change in the resistance value of the field winding 22 (field winding resistance value FR) (resistance change amount AC). If it determines that an interlayer short circuit has occurred in the field winding 22, the control device 10 (control method CM) adjusts the armature winding current value ACV, which is the value of the current that flows through the armature winding 21, using the resistance change amount AC. In other words, even if an interlayer short circuit occurs in the field winding 22, the armature winding 21 receives the "adjusted armature winding current value ACV" adjusted using the resistance change amount AC, and the wound-field rotating electric machine 20 does not stop. Therefore, the control device 10 (control method CM) can suppress the possibility that the vehicle VH will stop (for example, the vehicle VH will stop unintentionally or unexpectedly by the occupants) even if an interlayer short circuit occurs in the field winding 22 of the wound-field type rotating electric machine 20 that constitutes the drive motor mounted on the vehicle VH as a driving source.

[0082] §4 Modifications While embodiments of the present invention have been described in detail above, the descriptions above are merely illustrative of the present invention in all respects. It goes without saying that various improvements or modifications can be made without departing from the scope of the present invention. For example, the following modifications are possible. In the following, the same reference numerals are used for components similar to those in the above embodiments, and explanations of similar points are omitted as appropriate. The following modifications can be combined as appropriate.

[0083] In the above embodiment, an example was described in which the control device 10, inverter 40, converter 50, and higher-level ECU 60 are each implemented as separate devices. However, the configuration of the control device 10 according to this embodiment is not limited to this example and may be appropriately determined depending on the embodiment. For example, the control device 10 may be implemented as an integrated device with at least one of the inverter 40, converter 50, and higher-level ECU 60. For example, the control device 10 may be configured integrally with the inverter 40. If such a control device 10 determines that an interlayer short circuit has occurred in the field winding 22 from the change in the field winding resistance value FR (resistance change amount AC), it may adjust the armature winding current value ACV using the resistance change amount AC. In other words, for a control device according to one aspect of the present invention, it is not essential to adjust the armature winding current value ACV via an inverter, or to put it another way, it is not essential to adjust the armature current command value CAC using the resistance change amount AC.

[0084] A control device according to one aspect of the present invention can determine whether an interlayer short circuit has occurred in the field winding 22 from the resistance change amount AC, and if it is determined that an interlayer short circuit has occurred, it is sufficient to adjust the value of the current flowing through the armature winding 21 (armature winding current value ACV) using the resistance change amount AC. However, as described above, a control device according to one aspect of the present invention may also adjust the armature current command value CAC using the resistance change amount AC, and then adjust the armature winding current value ACV by outputting the adjusted armature current command value CAC to the inverter.

[0085] 10...Control device, 11...Control unit (processor), 20...Wound-field rotating electric machine, 21...Armature winding, 22...Field winding, 123...Reference armature winding current value, 127...Reference field winding resistance value, 150...Resistance value estimation unit, 160...Change amount calculation unit, 170...Change amount determination unit, 180...Armature winding current value adjustment unit, AC...Resistance value change amount, ACV...Armature winding current value, CM...Control method, DFC...Detected value of field winding current, DFV...Detected value of field winding voltage, FR...Field winding resistance value, RAC...Reference change amount, RAC1...First reference change amount, RAC2...Second reference change amount, VH...Vehicle (electric vehicle), WS1...First warning signal, WS2...Second warning signal

Claims

1. A control method for a wound-field rotating electric motor that constitutes a drive motor mounted as a driving source for an electric vehicle, the control method comprising: a processor estimating the field winding resistance value of the field winding of the wound-field rotating electric motor from a detected field winding current value and a detected field winding voltage value; a step of calculating a resistance change amount that indicates the amount of change of the field winding resistance value estimated in the step of estimating the field winding resistance value with respect to a predetermined reference field winding resistance value; a step of determining whether the resistance change amount calculated in the step of calculating the resistance change amount is greater than a predetermined reference change amount; and, if the step of determining whether the resistance change amount is greater than the reference change amount determines that the resistance change amount is greater than the reference change amount, the step of adjusting the armature winding current value, which is the value of the current flowing through the armature winding of the wound-field rotating electric motor, using the resistance change amount calculated in the step of calculating the resistance change amount.

2. The control method according to claim 1, wherein, before performing the step of adjusting the armature winding current value using the resistance change amount, the processor performs the step of determining whether the armature winding current value before adjustment using the resistance change amount is smaller than a predetermined reference armature winding current value, and if it determines that the armature winding current value before adjustment using the resistance change amount is smaller than the reference armature winding current value, the processor does not perform the step of adjusting the armature winding current value using the resistance change amount, even if it determines in the step of determining whether the resistance change amount is larger than the reference change amount that the resistance change amount is larger than the reference change amount.

3. The control method according to claim 1 or 2, wherein the processor further performs the step of acquiring temperature information indicating the temperature of the field winding, and the processor calculates the change in resistance in the step of calculating the change in resistance, taking into consideration the temperature of the field winding acquired in the step of acquiring the temperature information.

4. The control method according to claim 1 or 2, wherein the reference change amount is a first reference change amount, and in the step of determining whether the resistance change amount is greater than the reference change amount, the processor determines that the resistance change amount is greater than the first reference change amount, and in addition to the step of adjusting the armature winding current value using the resistance change amount, it outputs a first warning signal indicating that an interlayer short circuit has occurred in the field winding, and the processor further performs the step of determining whether the resistance change amount is greater than a predetermined second reference change amount which is greater than the first reference change amount, and in the step of determining whether the resistance change amount is greater than the second reference change amount, if it determines that the resistance change amount is greater than the second reference change amount, it outputs a second warning signal prompting the electric vehicle to be stopped.

5. A control device for a wound-field rotating electric motor that constitutes a drive motor mounted on an electric vehicle as a driving source, comprising: a resistance value estimation unit that estimates the field winding resistance value of the field winding of the wound-field rotating electric motor from a detected value of the field winding current and a detected value of the field winding voltage; a change amount calculation unit that calculates a change amount of the field winding resistance value estimated by the resistance value estimation unit, showing the change amount relative to a predetermined reference field winding resistance value; a change amount determination unit that determines whether the change amount of the resistance value calculated by the change amount calculation unit is greater than a predetermined reference change amount; and an armature winding current value adjustment unit that, when the change amount determination unit determines that the change amount of the resistance value is greater than the reference change amount, adjusts the armature winding current value, which is the value of the current that flows through the armature winding of the wound-field rotating electric motor, using the change amount of the resistance value calculated by the change amount calculation unit.

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