Rotary electric machine apparatus

Abstract

To maintain output while preventing demagnetization caused by overheat of a permanent magnet in a case where a temperature of the permanent magnet rises.SOLUTION: A rotary electric machine apparatus comprises: a rotary electric machine which includes a stator in which a coil is provided and a rotor in which a permanent magnet is provided; a power conversion circuit which is connected to a DC power source and supplies a current via a switching element; a temperature detector which detects a temperature of the permanent magnet; and a control device which calculates a target q-axis current and a target d-axis current and controls the switching element of the power conversion circuit. In the rotary electric machine apparatus, the control device changes the target d-axis current in a negative direction and decreases an absolute value of the target q-axis current in a case where a temperature of the permanent magnet which is detected by the temperature detector is higher than a predetermined magnet temperature threshold, thereby maintaining output of the rotary electric machine.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a rotating electrical machine device. [Background technology]

[0002] Rotating electric machines are a general term for electric motors and generators, and electric motors that generate electricity through regenerative operation are widely used as rotating electric machines. Rotating electric machines are driven by a combination of a rotor with permanent magnets and a stator with coils, and demagnetization due to overheating of the permanent magnets can be a problem.

[0003] In rotating electrical machines such as three-phase AC motors and three-phase AC generators, when losses are concentrated in the stator to which the permanent magnets are attached due to the current flowing through the coils, the permanent magnets overheat, which can lead to thermal demagnetization of the permanent magnets and irreversible demagnetization, which can degrade the performance of the rotating electrical machine.

[0004] In order to prevent demagnetization of permanent magnets due to overheating, a motor control device technology has been disclosed that calculates the d-axis current command value and q-axis current command value of a vector-controlled rotating electric machine, and performs control by determining the d-axis current command value that minimizes the temperature rise of the permanent magnets (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-102671 Summary of the Invention [Problem to be solved by the invention]

[0006] The technology described in Patent Document 1 proposes a motor control device that controls an electric motor by determining a d-axis current command value that minimizes the temperature rise of the permanent magnet. However, because minimizing the temperature rise of the permanent magnet is prioritized, there is a risk that the torque of the electric motor will decrease and the output will decrease.

[0007] The present disclosure discloses a technique related to a rotating electric machine device for solving the above-mentioned problems. The object of the present disclosure is to provide a rotating electric machine device that includes a rotating electric machine configured by combining a rotor having permanent magnets and a stator having coils, and that can maintain output while preventing demagnetization due to overheating of the permanent magnets when the temperature of the permanent magnets rises. [Means for solving the problem]

[0008] A rotating electric machine device according to the present disclosure includes: A rotating electric machine having a stator provided with windings and a rotor provided with permanent magnets; a power conversion circuit connected to a DC power supply and supplying current to a winding of the rotating electrical machine via a switching element; a temperature detector for detecting the temperature of a permanent magnet of a rotating electric machine; and A rotating electrical machine device including a control device that calculates a target d-axis current and a target q-axis current and controls a switching element of a power conversion circuit based on the target d-axis current and the target q-axis current, When the temperature of the permanent magnet detected by the temperature detector is higher than a predetermined magnet temperature threshold, the control device changes the target d-axis current in the negative direction and reduces the absolute value of the target q-axis current to maintain the output of the rotating electric machine. [Effects of the Invention]

[0009] According to the rotating electric machine control device of the present disclosure, a rotating electric machine device can be obtained that includes a rotating electric machine configured by combining a rotor having permanent magnets and a stator having coils, and that can maintain output while preventing demagnetization due to overheating of the permanent magnets when the temperature of the permanent magnets rises.As a result, a rotating electric machine device that can improve reliability and maintain output performance can be obtained. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a configuration diagram of a rotary electric machine device according to a first embodiment. [Figure 2]1 is a hardware configuration diagram of a control device for a rotary electric machine device according to a first embodiment. [Figure 3] 1 is a functional block diagram of a control device for a rotary electric machine according to a first embodiment. [Figure 4] 3 is a functional block diagram of an operating point adjustment unit of the control device for the rotary electric machine device according to the first embodiment. FIG. [Figure 5] 5 is a diagram showing rotor loss, d-axis current, and q-axis current of the rotary electric machine device according to the first embodiment. FIG. [Figure 6] 5 is a diagram showing the loss of the rotor of the rotary electric machine device according to the first embodiment and the transition of the operating point. FIG. [Figure 7] 4 is a time chart showing the magnet temperature of the rotor of the rotary electric machine device according to the first embodiment. [Figure 8] FIG. 10 is a functional block diagram of a control device for a rotary electric machine device according to a second embodiment. [Figure 9] FIG. 10 is a functional block diagram of an output suppression unit of a control device for a rotary electric machine device according to a second embodiment. [Figure 10] 10 is a diagram showing the loss of the rotor of the rotary electric machine device according to the second embodiment and the transition of the operating point. FIG. [Figure 11] 10 is a time chart showing the magnet temperature of the rotor of the rotary electric machine device according to the second embodiment. [Figure 12] FIG. 11 is a functional block diagram of a control device for a rotary electric machine device according to a third embodiment. [Figure 13] FIG. 11 is a functional block diagram of an operating point adjuster of a control device for a rotary electric machine device according to a third embodiment. [Figure 14] FIG. 11 is a functional block diagram of an output suppression unit of a control device for a rotary electric machine device according to a third embodiment. [Figure 15] 10 is a diagram showing the loss of the rotor of the rotary electric machine device according to the third embodiment and the transition of the operating point. FIG. [Figure 16] 10 is a time chart showing the magnet temperature of the rotor of the rotary electric machine device and the switching element temperature of the control device according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] <Rotating electric machines and power conversion circuits> The power conversion circuit that drives a rotating electric machine is also called an inverter. The inverter, which is equipped with semiconductor switching elements, transmits power from a power source to a rotating electric machine that has permanent magnets. The inverter converts the voltage and current forms and transmits them so that the rotating electric machine can be driven with the desired torque or rotation speed. A control device that controls the semiconductor switching elements equipped in the inverter outputs ON / OFF signals to convert the inverter's voltage and current forms into the desired forms.

[0012] Generally, an inverter control device controls the flow of current (e.g., three-phase AC current) at appropriate timing and magnitude to the winding coils of a rotating electric machine based on the position of the rotor of the rotating electric machine having permanent magnets.One control method is to define the d-axis as the same direction as the magnetic flux of the permanent magnet of the rotating electric machine having permanent magnets, and the q-axis as the direction perpendicular to the d-axis, i.e., the direction perpendicular to the magnetic flux of the permanent magnets, and calculate the d-axis current and q-axis current based on the three-phase AC current and the position of the rotor of the rotating machine, and control the magnitude and timing of the current flow.

[0013] At a certain rotation speed, there are an infinite number of combinations of d-axis current and q-axis current that correspond to the desired torque. When controlling an electric motor, it is generally controlled so that the absolute value of the current output by the inverter is minimized and maximum torque is obtained. For example, an interior permanent magnet synchronous motor is controlled at the operating point of the combination of d-axis current and q-axis current that minimizes the amplitude of the three-phase AC current and maximizes the sum of the magnet torque and reluctance torque.

[0014] By passing a d-axis current in the opposite direction to the magnetic flux direction of the permanent magnet, i.e., in a direction that weakens the magnetic flux of the permanent magnet, it is possible to generate reluctance torque in the rotational direction of the rotating machine. The magnitude of the d-axis current that generates magnetic flux in this reverse direction is generally defined as a negative value. In this disclosure, expressions similar to "increasing the absolute value of the d-axis current" are explained to mean increasing the d-axis current in the negative direction.

[0015] <Losses in rotating electrical machines> The winding coils provided in the rotating electric machine, the semiconductor switching elements provided in the inverter, and the smoothing capacitors provided between the power supply and the inverter to smooth the power supply voltage, etc., experience increased losses and temperature rises when the three-phase AC current output by the inverter increases or due to the influence of the power factor, etc.

[0016] On the other hand, the stator and rotor cores of rotating electrical machines are more strongly affected by the magnitude of the ripple in the current output by the inverter (for example, switching ripple in the current generated by switching, ripple due to superimposition of harmonics caused by square wave drive, etc.) than by the magnitude of the three-phase AC current. This is because an increase in the amount of ripple increases the rate of change of the magnetic flux generated by the winding coils of the rotating machine, and in turn the magnetic flux passing through the iron core, resulting in increased iron loss in the motor.

[0017] <Demagnetization of permanent magnets> This loss occurs when an increase in the q-axis current advances the magnetic saturation of the stator core of the rotating machine, reducing the inductance of the winding coil, increasing the amount of ripple, and increasing the iron loss of the motor. It is also known that the permanent magnets in rotating electric machines can become irreversibly demagnetized when they reach an overheating state, i.e., once they reach their Curie temperature, their magnetic force does not return to normal. To prevent this demagnetization due to overheating, measures are taken to lower the magnet temperature before it overheats.

[0018] For example, one method to lower the magnet temperature is to switch to a mode that reduces the output torque, i.e., power saving mode. This method reduces the magnitude of the three-phase current, including the q-axis current, thereby reducing the losses generated in each device and lowering the temperature.

[0019] However, because switching to power save mode reduces output torque, for example, if the powertrain of an electric vehicle switches to power save mode, problems may arise, such as the vehicle being unable to climb uphill or slowing down in the middle of an intersection. This could also cause problems in other product applications, so switching to power save mode should be avoided whenever possible.

[0020] Another way to reduce the magnitude of current ripple and therefore motor iron loss is to increase the carrier frequency. Increasing the carrier frequency reduces the amount of harmonic current ripple, which in turn reduces motor iron loss.

[0021] This method requires the implementation of a high-speed calculator (e.g., a microcomputer with high calculation speed) in the inverter control device to increase the carrier frequency, which increases costs. Also, since the ratio of dead time to prevent short circuits in the upper and lower arms of the inverter increases relative to the switching period, which is the inverse of the carrier frequency, the maximum ON time per period of the inverter's switching elements decreases, resulting in a reduction in the inverter's output range.

[0022] Furthermore, as a means for lowering the magnet temperature by reducing the motor iron loss, a means has been disclosed (described in Patent Document 1) for selecting an operating point that minimizes the temperature rise of the magnet from among the operating points of the d-axis current and q-axis current that output the desired torque. However, with this means, priority is given to minimizing the temperature rise of the permanent magnet, which can result in a decrease in the torque of the motor and a decrease in output.

[0023] A rotating electric machine according to the present disclosure will be described below with reference to the drawings according to preferred embodiments. In the description of the drawings, the same or corresponding parts are designated by the same reference numerals, and duplicated explanations will be omitted. Each embodiment illustrates an example in which the present disclosure is applied to a rotating electric machine equipped with a three-phase inverter having U-phase, V-phase, and W-phase that drives an interior permanent magnet synchronous motor.

[0024] 1. First Embodiment Fig. 1 is a configuration diagram of a rotating electric machine device 100 according to a first embodiment of the present disclosure. As shown in Fig. 1, the rotating electric machine device 100 includes a rotating electric machine 1, a power supply unit 2, a power conversion circuit 3, a cooler 4, a rotation angle sensor 5, a rotating electric machine temperature sensor 6, a switching element temperature sensor 7, and a control device 9. The rotating electric machine device 100 receives a supply of power from a DC power supply 21 and a control command from an external command generator 8. The rotating electric machine device 100 may include the DC power supply 21 and the command generator 8 as components.

[0025] The rotating electric machine 1 is controlled according to a PWM (Pulse Width Modulation) method. The rotating electric machine 1 is, for example, an in-vehicle electric motor or generator. Note that the in-vehicle electric motor referred to here specifically refers to a motor used in a drive motor for driving a vehicle, an electric fan, an oil pump, a water pump, an electric power steering device for assisting the steering operation of the vehicle, and the like. Furthermore, the rotating electric machine 1 is not limited to an in-vehicle rotating electric machine, and may be a rotating electric machine other than an in-vehicle rotating electric machine.

[0026] The following describes an example in which the rotating electric machine 1 is a three-phase brushless electric motor having a rotor and a stator. The rotor is a disk-shaped or cylindrical member with permanent magnets attached to its surface and magnetic poles. The stator accommodates the rotor inside so that they can rotate relative to each other. The stator has protrusions that protrude radially inward at preset angles, and U-phase coil 11, V-phase coil 12, and W-phase coil 13 are wound around these protrusions.

[0027] The DC power supply 21 is a drive source for the rotating electric machine device 100 and is connected to the power supply unit 2. The DC power supply 21 is also called a battery, and supplies DC power to the power conversion circuit 3 to drive the rotating electric machine 1. The power supply unit 2 is provided with a smoothing capacitor 22 and a choke coil 23.

[0028] Smoothing capacitor 22 and choke coil 23 are disposed between DC power supply 21 and inverter unit 31, which will be described later, and form a power filter. This configuration reduces noise transmitted from other devices sharing DC power supply 21 to inverter unit 31, and also reduces noise transmitted from inverter unit 31 to other devices sharing DC power supply 21. Smoothing capacitor 22 stores electric charge to assist in the supply of power to switching elements 311 to 316 and also suppress noise components such as surge currents. Furthermore, voltage Vbat of DC power supply 21 and voltage Vcon of smoothing capacitor 22 may be detected by control device 9 (Vbat is not shown).

[0029] The power conversion circuit 3 converts DC power supplied from the power supply unit 2 into AC power and outputs the converted AC power to the rotating electric machine 1. As a specific configuration example of the power conversion circuit 3, the power conversion circuit 3 has an inverter unit 31, a current detector 32, an amplifier circuit 33, a drive circuit 34, a switching element temperature sensor 7, and a capacitor temperature sensor 24.

[0030] Inverter unit 31 has a plurality of half-bridge circuits connected in parallel, each having switching elements 311 to 316 on an upper arm and a lower arm. Switching elements 311 to 316 are controlled to switch on and off in accordance with a PWM signal, thereby converting DC power output from power supply unit 2 into AC power and outputting the converted AC power to rotating electric machine 1.

[0031] FIG. 1 illustrates an example in which the inverter unit 31 is configured with three half-bridge circuits. The inverter unit 31 includes switching elements 311 to 316. The inverter unit 31 is a three-phase inverter in which six switching elements 311 to 316 are bridge-connected to switch the energization of the U-phase coil 11, the V-phase coil 12, and the W-phase coil 13, respectively. The switching elements 311 to 316 may be MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), which are a type of field effect transistor, or may be other transistors different from MOSFETs or IGBTs (Insulated Gate Bipolar Transistors). Note that, hereinafter, the switching elements 311 to 316 will be referred to as SW311 to 316.

[0032] The drains of the three SW311 to 313 are connected to the positive side of the DC power supply 21. The sources of SW311 to 313 are connected to the drains of SW314 to 316, respectively. The sources of SW314 to 316 are connected to the negative side of the DC power supply 21.

[0033] The connection point connecting the pair of SW311 and SW314 is connected to one end of the U-phase coil 11. The connection point connecting the pair of SW312 and SW315 is connected to one end of the V-phase coil 12. The connection point connecting the pair of SW313 and SW316 is connected to one end of the W-phase coil 13.

[0034] In the following description, the switching elements SW311 to SW313 arranged on the high potential side are referred to as "upper SW" or "H_SW," and the switching elements SW314 to SW316 arranged on the low potential side are referred to as "lower SW" or "L_SW." In the present first embodiment, for ease of understanding, the potential on the low potential side is set to 0V.

[0035] The current detector 32 has a U-phase current detector 321, a V-phase current detector 322, and a W-phase current detector 323. The U-phase current detector 321, the V-phase current detector 322, and the W-phase current detector 323 are configured using, for example, shunt resistors. Note that hereinafter, the U-phase current detector 321, the V-phase current detector 322, and the W-phase current detector 323 will be referred to as current detectors 321 to 323 as appropriate.

[0036] The U-phase current detection unit 321 detects the U-phase current Iu as the current flowing through the U-phase coil 11. The V-phase current detection unit 322 detects the V-phase current Iv as the current flowing through the V-phase coil 12. The W-phase current detection unit 323 detects the W-phase current Iw as the current flowing through the W-phase coil 13. The detection values ​​detected by the current detection units 321 to 323 are input to the control device 9 via an amplifier circuit 33. The amplifier circuit 33 is intended to enable the detection values ​​detected by the current detection units 321 to 323 to be taken in as appropriate values ​​that can be processed within the control device 9.

[0037] The drive circuit 34 transmits a signal input from the control device 9 to SW314 to 316 of the inverter unit 31. The drive circuit 34 has a function of switching on and off each of the SW314 to 316 based on a PWM signal input from the control device 9.

[0038] The cooler 4 cools the smoothing capacitor 22, the choke coil 23, and the power conversion circuit 3. The cooler 4 may be, for example, a water-cooled cooler. Specifically, the water-cooled cooler and an electric motor such as a water pump are connected by a hose, and a cooling medium such as water, oil, or LLC flows from the electric motor to the water-cooled cooler. The cooler 4 is not limited to a water-cooled cooler, and may be an air-cooled cooler or the like. The DC power supply 21 may also be cooled by the cooler.

[0039] The rotation angle sensor 5 is attached to the rotating electric machine 1 and detects position information indicating the rotor position of the rotating electric machine 1, specifically, the rotation angle θm of the rotor (θm is not shown). The rotation angle sensor 5 is configured using, for example, a resolver. The rotation angle sensor 5 is configured to convert the detected rotation angle θm into an electrical angle θe based on the number of pole pairs of the permanent magnet of the rotating electric machine 1. The rotation angle θm and the electrical angle θe are acquired by the control device 9.

[0040] The rotating electric machine temperature sensor 6 detects the temperature of the rotating electric machine 1. The rotating electric machine temperature sensor 6 includes a permanent magnet temperature sensor 25 that detects the temperature of a permanent magnet provided in the motor, and a coil temperature sensor 26 that detects the temperatures of the U-phase coil 11, V-phase coil 12, and W-phase coil 13, each of which is configured using a thermistor or the like. The permanent magnet temperature sensor detection value temp_mag and the coil temperature sensor detection value temp_coil of the rotating electric machine 1 are acquired by the control device 9. (The coil temperature sensor detection value temp_coil is not shown.)

[0041] If a temperature sensor cannot be directly attached to the permanent magnet provided in the rotating electric machine 1, the temperature of the permanent magnet may be estimated from the temperature of another part. For example, the control device 9 may indirectly estimate the temperature of the permanent magnet based on the value temp_coil detected by the coil temperature sensor, the operating conditions of the inverter, etc.

[0042] The switching element temperature sensor 7 detects the temperatures of SW311 to SW316. Specifically, for example, the detected value temp_Tj of the switching element temperature sensor 7 may be obtained by indirectly measuring the temperatures of SW311 to SW316 using temperature sensors installed near SW311 to SW316. The detected values ​​of the temperature sensors are acquired by the control device 9.

[0043] The command generator 8 is a device that generates control commands for controlling the rotating electric machine 1 and outputs the control commands to the control device 9. Specifically, for example, when the rotating electric machine 1 is used as a drive source for a vehicle such as an electric vehicle, the command generator 8 outputs a control command corresponding to the depression angle of an accelerator pedal operated by a driver of the vehicle. The control commands output by the command generator 8 are periodically transmitted to the control device 9 via communication.

[0044] The control command for controlling the rotary electric machine 1 may be, for example, a torque command, a current command, or a voltage command. In the first embodiment, a case where a torque command Tq* is used as the control command is exemplified. The control command is also referred to as an output command value.

[0045] The control device 9 periodically controls the entire electric motor drive system, and may be realized by, for example, a microcomputer configured to execute a program stored in a memory.

[0046] <Control device hardware configuration> 2 is a hardware configuration diagram of the control device 9 of the rotating electric machine device 100 according to the first embodiment. In this embodiment, the control device 9 is a control device that controls the rotating electric machine device 100. Each function of the control device 9 is realized by a processing circuit provided in the control device 9. Specifically, the control device 9 includes, as processing circuits, an arithmetic processing device 900 (computer) such as a CPU (Central Processing Unit), a storage device 901 that exchanges data with the arithmetic processing device 900, an input circuit 902 that inputs external signals to the arithmetic processing device 900, and an output circuit 903 that outputs signals from the arithmetic processing device 900 to the outside.

[0047] The arithmetic processing device 900 may include an ASIC (Application Specific Integrated Circuit), an IC (Integrated Circuit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), various logic circuits, various signal processing circuits, etc. Furthermore, the arithmetic processing device 900 may include a plurality of the same or different types of devices, each performing a different process. The storage device 901 may include a RAM (Random Access Memory) configured to be able to read and write data from the arithmetic processing device 900, a ROM (Read Only Memory) configured to be able to read data from the arithmetic processing device 900, etc. The input circuit 902 includes a rotation angle sensor 5, a rotating electrical machine temperature sensor 6, a switching element temperature sensor 7, a command generator 8, and an amplifier circuit 33, and is connected to various sensors and switches. The input circuit 902 includes interface circuits such as an AD converter and an input circuit that inputs output signals from these sensors and switches to the arithmetic processing device 900. The output circuit 903 includes a drive circuit 34, to which electrical loads such as switching elements and actuators are connected, and is equipped with interface circuits such as drive circuits and communication circuits that convert and output output signals from the arithmetic processing device 900 to these electrical loads.

[0048] Each function of the control device 9 is realized by the arithmetic processing device 900 executing software (programs) stored in a storage device 901 such as a ROM, and working in cooperation with other hardware of the control device 9 such as the storage device 901, an input circuit 902, and an output circuit 903. Setting data such as thresholds and judgment values ​​used by the control device 9 is stored in the storage device 901 such as a ROM as part of the software (programs).

[0049] Each function installed inside the control device 9 may be configured as a software module, or each function installed inside the control device 9 may be configured as a combination of software and hardware.

[0050] <Controller function block> 3 is a functional block diagram showing the signal processing process of the control device 9 of the rotating electrical machine device 100 according to embodiment 1. As shown in FIG. 3, the control device 9 has a rotation speed calculation unit 91, a torque / current command conversion unit 92, an operating point adjustment unit 93, a three-phase to two-phase conversion unit 94, a voltage command generation unit 95, a two-phase to three-phase conversion unit 96, a duty conversion unit 97, and a PWM signal generation unit 98.

[0051] The rotation speed calculation unit 91 integrates the rotation angle θm acquired from the rotation angle sensor 5 and converts it into the rotation speed N of the rotating electrical machine 1. The rotation speed calculation unit 91 outputs the rotation speed N to the torque / current command conversion unit 92.

[0052] The torque / current command conversion unit 92 calculates an MTPA control d-axis current command Id*_mtpa from the rotation speed N of the rotating electric machine 1 and the torque command Tq* acquired from the rotation speed calculation unit 91. Specifically, for example, the torque / current command conversion unit 92 is configured to convert these values ​​into the MTPA control d-axis current command Id*_mtpa by using a torque / current command conversion table with the rotation speed N of the rotating electric machine 1 and the torque command Tq* as axes. In this embodiment, the torque / current command conversion table is generated so that the amplitude of the three-phase current is minimized, that is, the MTPA control d-axis current command Id*_mtpa is calculated when maximum torque control is applied, but this is not limitative. The torque / current command conversion unit 92 may also be configured to calculate the MTPA control d-axis current command Id*_mtpa without using the torque / current command conversion table.

[0053] The operating point adjuster 93 calculates whether it is necessary to lower the permanent magnet temperature from the MTPA control d-axis current command Id*_mtpa, the permanent magnet temperature sensor detection value temp_mag acquired from the rotating electric machine temperature sensor 6, the torque command Tq*, and the rotation speed N of the rotating electric machine 1, and adjusts the MTPA control d-axis current command Id*_mtpa using the calculation result.The operating point adjuster 93 also calculates the d-axis current command Id* and the q-axis current command Iq* using the calculation result.

[0054] The d-axis current command Id* and the q-axis current command Iq* are also referred to as a target d-axis current and a target q-axis current. The operating point adjuster 93 will be described in more detail later.

[0055] The three-phase to two-phase conversion unit 94 acquires the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw, i.e., the three-phase currents Iu, Iv, and Iw, from the current detection units 321 to 323. The three-phase to two-phase conversion unit 94 calculates the d-axis current detection value Id and the q-axis current detection value Iq from the three-phase currents Iu, Iv, and Iw and the electrical angle θe acquired from the rotation angle sensor 5.

[0056] The voltage command generation unit 95 calculates a d-axis voltage command Vd* and a q-axis voltage command Vq* by performing current feedback calculations from the d-axis current command Id*, the q-axis current command Iq*, and the d-axis current detection value Id and the q-axis current detection value Iq. Specifically, for example, the voltage command generation unit 95 is configured to calculate the d-axis voltage command Vd* and the q-axis voltage command Vq* so that a current deviation ΔId, which is the deviation between the d-axis current command Id* and the d-axis current detection value Id, and a current deviation ΔIq, which is the deviation between the q-axis current command Iq* and the q-axis current detection value Iq, converge to 0 (ΔId and ΔIq are not shown).

[0057] The two-phase to three-phase conversion unit 96 calculates three-phase voltage commands Vu*, Vv*, and Vw* from the d-axis voltage command Vd* and q-axis voltage command Vq* obtained from the voltage command generation unit 95 and the electrical angle θe obtained from the rotation angle sensor 5. The three-phase voltage commands Vu*, Vv*, and Vw* are preferably set to be equal to or lower than the DC power supply voltage input to the inverter unit 31, i.e., the voltage Vcon of the smoothing capacitor 22.

[0058] The duty conversion unit 97 acquires the three-phase voltage commands Vu*, Vv*, Vw* from the two-phase to three-phase conversion unit 96. Then, it generates duty commands Du, Dv, Dw for each phase from the three-phase voltage commands Vu*, Vv*, Vw* and the voltage Vcon of the smoothing capacitor 22. In this way, the duty conversion unit 97 generates duty commands corresponding to the optimal correction control commands and outputs the duty commands.

[0059] The PWM signal generation unit 98 generates PWM signals for controlling the on / off switching of each of the switches SW311 to SW316 based on the duty commands Du, Dv, and Dw for each phase acquired from the duty conversion unit 97. Specifically, for example, the PWM signal generation unit 98 generates the PWM signals by comparing the duty commands Du, Dv, and Dw for each phase with a carrier wave. The PWM signal generation unit 98 is configured to generate the PWM signals by employing, for example, a triangular wave comparison method in which an isosceles triangle-shaped triangular wave having equal rising and falling speeds serves as the carrier, or a sawtooth wave comparison method.

[0060] In Figure 3, the PWM signals generated by the PWM signal generating unit 98 are represented as follows: the signal for the upper SW of the U phase is represented as UH_SW, the signal for the lower SW of the U phase is represented as UL_SW, the signal for the upper SW of the V phase is represented as VH_SW, the signal for the lower SW of the V phase is represented as VL_SW, the signal for the upper SW of the W phase is represented as WH_SW, and the signal for the lower SW of the W phase is represented as WL_SW.

[0061] <Operating point adjustment section> 4 is a functional block diagram showing the signal processing process of the operating point adjuster 93 of the control device 9 of the rotating electrical machine device 100 according to Embodiment 1. The operating point adjuster 93 is made up of a differential temperature calculator 931, a magnet temperature controller 932, an Id* limiter 933, and an Iq* calculator 934.

[0062] The temperature difference calculation unit 931 acquires the permanent magnet temperature sensor detection value temp_mag from the rotating electric machine temperature sensor 6, and calculates the magnet temperature difference delta_temp by subtracting a pre-calculated magnet temperature threshold from the permanent magnet temperature sensor detection value temp_mag. The magnet temperature threshold is set lower than the demagnetization temperature to provide a temperature margin so that the actual temperature of the permanent magnet does not reach the demagnetization temperature. The temperature margin can be calculated in advance by temperature analysis, taking into account, for example, the heat capacity of the permanent magnets provided in the rotating electric machine 1 and the temperature overshoot that occurs due to the response performance of the temperature feedback control of the magnet temperature control unit 932.

[0063] When the magnet temperature difference delta_temp calculated by the differential temperature calculation unit 931 is a positive value, that is, when the permanent magnet temperature sensor detection value temp_mag is higher than the magnet temperature threshold, the magnet temperature control unit 932 performs PI control to make the magnet temperature difference delta_temp equal to or less than 0. If the calculation result of the PI control is equal to or less than 0, the calculation result is output as the d-axis current adjustment value delta_Id, and if the calculation result is a positive value, the calculation result is replaced with 0 and output.

[0064] Even if the calculation result of PI control is a positive value, if it is output as is as the d-axis current adjustment value delta_Id, the MTPA control d-axis current command Id*_mtpa in the next process will be adjusted to be larger, which will actually increase the magnet temperature. Also, even though there is no need to lower the magnet temperature, the operating point of MTPA control will be deviated from, resulting in poor efficiency of the inverter and motor.

[0065] The gains of P control and I control can increase the responsiveness of the magnet temperature control unit 932 and reduce the temperature margin that determines the magnet temperature threshold, but since there is a possibility that the control may oscillate, adjustments must be made to suit the application through analysis, etc. In this example, the results of adjusting the gains so that the control converges without oscillation are shown as an example.

[0066] Furthermore, if the integral value stored in I control is greater than 0, it is replaced with 0. This is because if a positive integral value is not replaced with 0, even if a negative value is input to the I controller, I control will not function until the positive integral value decreases to 0 or a negative value, and the designed response performance will not be achieved.

[0067] The Id* limiting unit 933 receives the torque command Tq*, the rotation speed N of the rotating electric machine 1, the permanent magnet temperature sensor detection value temp_mag, and the adjusted d-axis current command Id*_calib which is the sum of the MTPA control d-axis current command Id*_mtpa and the d-axis current adjustment value delta_Id, and then outputs the d-axis current command Id*.

[0068] The d-axis current command Id* is calculated by comparing the adjusted d-axis current command Id*_calib with the d-axis current id_max with the largest absolute value on the negative side that is allowed for rated output among the combinations of d-axis current and q-axis current that can output the torque command Tq* when the rotating electric machine 1 is at a rotation speed N, and the demagnetization prevention d-axis current threshold id_lmt with the largest absolute value on the negative side of the d-axis current that does not cause demagnetization due to an external magnetic field.The value with the smaller absolute value on the negative side is then selected.

[0069] Of the combinations of the d-axis current and the q-axis current, the d-axis current id_max with the largest absolute value on the negative side is calculated using a maximum d-axis current table with the rotation speed of the rotating electric machine 1 and the output torque as axes. This table can be calculated in advance from the performance of the rotating electric machine 1, the DC power supply 21, and the power conversion circuit 3. Note that, although the calculation is performed using a table in this embodiment, this is not limited to this.

[0070] Similarly, the demagnetization prevention d-axis current threshold id_lmt, which is the maximum absolute value of the negative d-axis current that does not cause demagnetization, is calculated using a maximum d-axis current table that does not cause demagnetization in response to changes in permanent magnet temperature. This table can be calculated in advance based on the performance of the permanent magnets of the rotating electric machine 1. Note that, although the calculation is performed using a table in this embodiment, this is not limited to this.

[0071] The Iq* calculation unit 934 receives the torque command Tq*, the rotation speed N of the rotating electric machine 1, and the d-axis current command Id* as inputs to calculate the q-axis current command Iq*. The q-axis current command Iq* is calculated using a q-axis current table with the torque, rotation speed, and d-axis current of the rotating electric machine 1 as axes. This table can be calculated in advance from the performance of the rotating electric machine 1 and the DC power supply 21. Note that, although the calculation is performed using a table in this embodiment, this is not limited to this.

[0072] From here, the processing from the differential temperature calculation unit 931 to the Iq* calculation unit 934 will be explained in chronological order with reference to Figures 5 to 7. First, how to read the loss contour diagram (contour map) shown in Figure 5 will be explained.

[0073] <Loss contour diagram> FIG. 5 is a diagram showing rotor loss, d-axis current, and q-axis current of the rotating electric machine device 100 according to the first embodiment. FIG. 5 shows a contour diagram of loss occurring in the rotor of the rotating electric machine 1, which is a combination of eddy current loss, hysteresis loss, and the like. This loss contour diagram has the d-axis current on the horizontal axis and the q-axis current on the vertical axis, with the origin O at the bottom right of the diagram, and focuses on the second quadrant. Higher losses are indicated by darker shading, and lower losses are indicated by lighter shading. As mentioned above, the diagram shows that loss increases by increasing the q-axis current, but is hardly affected by the d-axis current.

[0074] Furthermore, the locus of the combination of d-axis current and q-axis current that can output a certain torque at any rotation speed is called the constant torque curve tq_cnst_curve, and is depicted by the dashed line in Figure 5. The dashed line shown here is the locus of the combination of d-axis current and q-axis current that can output the torque command Tq*.

[0075] Additionally, combinations of d-axis and q-axis currents that do not exceed the rated value of the three-phase AC current are depicted with dashed lines (maximum rated current curve iuvw_max in the diagram). Note that in order to emphasize visibility, only the range in which the trend of the loss contour diagram can be seen is shown, so small current ranges (near the origin O) and areas where only one side of the d-axis or q-axis current is large are omitted.

[0076] Additionally, the maximum value of the d-axis current that will not cause demagnetization due to an external magnetic field at a certain magnet temperature is shown as the demagnetization prevention d-axis current threshold id_lmt, drawn by a dashed line. If this threshold is exceeded, in other words, if an operating point to the left of the dashed line is selected, the permanent magnet will be demagnetized.

[0077] The intersection of the constant torque curve tq_cnst_curve and the maximum rated current curve iuvw_max, which represents a combination of d-axis and q-axis currents that does not exceed the rated value of the three-phase AC current, represents the d-axis or q-axis current that the inverter can output. The intersection in the lower left of the figure represents the maximum negative value of the d-axis current. The intersection in the upper right of the figure represents the maximum value of the q-axis current. The maximum negative d-axis current id_max at this time is depicted by a two-dot chain line. Note that, although this line is omitted from Figure 5 onwards, the smaller absolute value of the demagnetization prevention d-axis current threshold id_lmt and the maximum negative d-axis current id_max (the right side in the figure) represents the d-axis current limit value, and a large negative d-axis current is limited to prevent it from exceeding this limit. This process is performed by the Id* limiting unit 933.

[0078] Furthermore, the MTPA control d-axis current command Id*_mtpa calculated by the torque / current command conversion unit 92 and the MTPA control q-axis current command Iq*_mtpa that can be uniquely determined from the MTPA control d-axis current command Id*_mtpa are depicted as point P. Point P exists on the constant torque curve. The square root of the sum of the squares of the d-axis current and the q-axis current at point P is the length of the arrow in the figure. Point P may be selected as the point where the length of this arrow is minimum.

[0079] <Operating point transition> Fig. 6 is a diagram showing the transition of rotor loss and operating point of the rotating electrical machine device 100 according to embodiment 1. Fig. 6 shows the result of determining that the permanent magnet temperature sensor detection value temp_mag has exceeded the magnet temperature threshold, and then changing the d-axis current in the negative direction on the constant torque curve and decreasing the q-axis current so as not to change the output torque from point P in order to lower the magnet temperature.

[0080] <Changes in magnet temperature> 7 is a time chart showing the magnet temperature of the rotor of the rotating electrical machine device 100 according to the first embodiment. The temperature waveform is shown over time. While the actual temperature will be a transient waveform such as a first-order lag response, it is depicted as a simplified straight line.

[0081] FIG. 7 shows a scene in which the operating point transitions from an initial operating point where the torque command Tq* is lower than point P to point P, and the permanent magnet temperature sensor detected value temp_mag gradually increases. The time when the operating point transitions to point P is indicated on the horizontal axis as "P." Similarly, alphanumeric characters indicating the operating point will be indicated on the horizontal axis from here onwards, but their explanation will be omitted.

[0082] The permanent magnet temperature sensor detection value temp_mag, which gradually rises after transitioning to point P, eventually reaches the magnet temperature threshold. Up to this point, the outputs of the differential temperature calculation unit 931 and magnet temperature control unit 932 are 0, and the d-axis current command Id* and the q-axis current command are the MTPA control d-axis current command Id*_mtpa and the MTPA control q-axis current command Iq*_mtpa.

[0083] After the permanent magnet temperature sensor detection value temp_mag exceeds the magnet temperature threshold, the differential temperature calculation unit 931 begins outputting negative values. In an attempt to make the output of the differential temperature calculation unit 931 zero, the PI controller of the magnet temperature control unit 932 operates, increasing the MTPA control d-axis current command Id*_mtpa and calculating the adjusted d-axis current command Id*_calib. The Id* limiting unit compares the adjusted d-axis current command Id*_calib with the maximum value of the negative d-axis current mentioned above, and outputs the smaller value in the negative direction as the d-axis current command Id*. The Iq* calculation unit 934 calculates the intersection of the d-axis current command Id* and the constant torque curve, and outputs it as the q-axis current command Iq*.

[0084] By repeating this process, the operating point gradually shifts and the temperature drops. Eventually, the permanent magnet temperature sensor detection value temp_mag and the magnet temperature threshold value match. The operating point at this point is point Q.

[0085] The temperature does not drop immediately when it reaches the magnet temperature threshold value because, as mentioned above, an overshoot occurs due to the influence of the heat capacity of the permanent magnets provided in the rotating electric machine 1 and the response performance of the temperature feedback control of the magnet temperature control unit 932.

[0086] As described above, the rotating electric machine device according to the first embodiment determines that the permanent magnet temperature sensor detection value temp_mag has exceeded the magnet temperature threshold, and changes the target d-axis current in the negative direction so as not to change the output torque, thereby decreasing the target q-axis current (decreasing the absolute value of the target q-axis current). This makes it possible to maintain output while preventing demagnetization due to overheating of the permanent magnet. Therefore, it is possible to obtain a rotating electric machine device 100 that improves reliability and can maintain output performance.

[0087] This eliminates the need to add large amounts of rare earth element additives such as terbium and dysprosium in order to increase the demagnetization temperature of the permanent magnet, thereby reducing costs.

[0088] Furthermore, in the rotating electric machine device according to the first embodiment, when the permanent magnet temperature sensor detected value temp_mag exceeds the magnet temperature threshold, feedback control can be performed to make the permanent magnet temperature sensor detected value coincide with the magnet temperature threshold by changing the target d-axis current in the negative direction on the constant torque curve and decreasing the target q-axis current (decreasing the absolute value of the target q-axis current). This makes it possible to appropriately control the operating point of the rotating electric machine while preventing demagnetization due to overheating of the permanent magnet, and to efficiently control the rotating electric machine without unnecessarily lowering the temperature of the permanent magnet.

[0089] Furthermore, the rotating electrical machine device according to the first embodiment determines that the permanent magnet temperature sensor detection value temp_mag has exceeded the magnet temperature threshold, and then changes the target d-axis current in the negative direction on the constant torque curve so as not to change the output torque, thereby decreasing the target q-axis current (decreasing the absolute value of the target q-axis current). This makes it possible to maintain the desired output while preventing demagnetization due to overheating of the permanent magnet.

[0090] Furthermore, in the rotating electrical machine according to the first embodiment, the target d-axis current and the target q-axis current can be changed within the range of the maximum rated current curve iuvw_max for a combination of the d-axis current and the q-axis current that does not exceed the rated value of the three-phase AC current, thereby improving the reliability of the rotating electrical machine.

[0091] Furthermore, in the rotating electrical machine according to the first embodiment, the target d-axis current can be changed within a range equal to or greater than the negative demagnetization prevention d-axis current threshold id_lmt (the absolute value of the d-axis current is equal to or less than the absolute value of the demagnetization prevention d-axis current threshold id_lmt), thereby making it possible to reliably prevent the permanent magnet from being demagnetized.

[0092] Furthermore, in the rotating electric machine device according to the first embodiment, the demagnetization prevention d-axis current threshold id_lmt can be changed in response to changes in the permanent magnet temperature. This allows the d-axis current at which demagnetization of the permanent magnet occurs to be appropriately determined, making it possible to reliably prevent demagnetization of the permanent magnet while avoiding excessive current limitation, thereby enabling efficient control of the rotating electric machine.

[0093] <For generators> Although the above description deals with the case where the rotating electric machine 1 operates as a motor, it can also be considered when it operates as a generator. In this case, the q-axis current will exhibit a negative value. In a loss contour diagram with the d-axis current on the horizontal axis and the q-axis current on the vertical axis, the operating point for a generator is in the third quadrant.

[0094] The diagrams corresponding to Figures 5 and 6 for the generator are obtained by folding Figures 5 and 6 downwards on the horizontal axis (axisymmetric). In this case, the only difference is that the sign of the q-axis current becomes negative, and the relationship between the absolute values ​​of the d-axis current and q-axis current remains the same as above. Therefore, when it is determined that the permanent magnet temperature sensor detection value temp_mag has exceeded the magnet temperature threshold, the target d-axis current is changed in the negative direction on the constant torque curve without changing the output torque, and the operating point is shifted to reduce the absolute value of the negative target q-axis current.

[0095] 2. Second Embodiment Fig. 8 is a functional block diagram showing the signal processing process of the control device 9 of the rotary electric machine device 100 according to the second embodiment. The second embodiment differs from the functional block diagram of Fig. 3 according to the first embodiment in that an output suppression unit 99 is added. Note that in the second embodiment, explanation of the same points as in the first embodiment will be omitted, and the explanation will focus on the points that are different from the first embodiment.

[0096] Assume a situation where the transition of the operating point on the constant torque curve alone is not enough to prevent the demagnetization temperature from being reached, and output suppression is unavoidable. Next, a rotating electrical machine device 100 that can minimize output suppression as much as possible will be described.

[0097] <Output suppression unit> The output suppression unit 99 receives the torque command Tq*, the previous value Id*_pre of the d-axis current command, and the permanent magnet temperature sensor detected value temp_mag as inputs, and outputs a post-suppression torque command Tq*_ctl. Based on the previous value Id*_pre of the d-axis current command and the permanent magnet temperature sensor detected value temp_mag, it determines whether to suppress the torque, and determines the amount of reduction based on the determination result, the torque command Tq*, and the permanent magnet temperature sensor detected value temp_mag to calculate the post-suppression torque command Tq*_ctl.

[0098] In the first embodiment, the torque command Tq* is input to the torque / current command conversion unit 92 and the operating point adjustment unit 93. In contrast to this, in the second embodiment, the post-suppression torque command Tq*_ctl output by the output suppression unit 99 is input.

[0099] 9 is a functional block diagram showing the signal processing process of the output suppression unit 99 of the control device 9 of the rotating electrical machine device 100 according to the second embodiment. The diagram shows details of the output suppression unit 99, which is added to the first embodiment. The output suppression unit 99 is made up of a maximum id operating point determination unit 991 and an output suppression unit 992 based on magnet temperature.

[0100] The maximum id operating point determination unit 991 determines whether to permit torque suppression based on the previous value Id*_pre of the d-axis current command and the permanent magnet temperature sensor detection value temp_mag. If torque suppression is permitted, 1 is output as the magnet temperature output suppression permission signal tmag_psave, and if torque suppression is not permitted, 0 is output.

[0101] Specifically, the demagnetization prevention d-axis current threshold id_lmt, which is the maximum d-axis current that does not cause demagnetization, is calculated from the permanent magnet temperature sensor detection value temp_mag. This is compared with the previous d-axis current command value Id*_pre, and if they match for a predetermined waiting time, a decision is made to allow torque suppression.

[0102] The previous value Id*_pre of the d-axis current command is the previous value of the d-axis current command Id* output by the operating point adjuster 93. The previous value refers to the value one cycle before in the periodic processing executed by the controller.

[0103] Furthermore, since the previous value does not exist only at the first time of the periodic processing, it is advisable to disable the determination only at the first time, or to set the initial value of the previous value Id*_pre of the d-axis current command to be larger than the maximum d-axis current value, i.e., not to allow torque suppression.

[0104] The predetermined waiting time refers to the waiting time from when the operating point is transitioned until the temperature stabilizes (hereinafter referred to as the magnet temperature settling time), and can be determined from the thermal resistance, heat capacity, etc. of the rotating electric machine 1. For example, it can be found by creating a 3D model of the rotating electric machine 1 and performing a temperature analysis using thermal analysis software, etc., but is not limited to this.

[0105] The magnet temperature-based output suppression unit 992 receives the magnet temperature-based output suppression permission signal tmag_psave, the permanent magnet temperature sensor detection value temp_mag, and the torque command Tq*, and calculates a post-suppression torque command Tq*_ctl from these.

[0106] Specifically, when the magnet temperature output suppression permission signal tmag_psave is 1, i.e., when output suppression is permitted, the difference between the permanent magnet temperature sensor detection value temp_mag and a predetermined demagnetization temperature threshold is calculated, and a torque suppression rate proportional to the magnitude of this difference is calculated. In other words, PI control is performed to make the difference zero. Note that the gains of the P control and I control must be adjusted to suit the application through analysis, etc., just like the magnet temperature control unit 932. In this example, the result of adjusting the gains so that they converge without oscillation is shown.

[0107] Note that magnet temperature output suppression unit 992 controls the temperature to follow the demagnetization temperature threshold, but instead of the demagnetization temperature threshold, a new threshold may be set separately to be used by magnet temperature output suppression unit 992. In this case, the threshold may be set so that the demagnetization temperature is not reached, taking into account overshoot such as a response delay of the PI control of magnet temperature output suppression unit 992, just like the demagnetization temperature threshold.

[0108] <Operating point transition> FIG. 10 is a diagram illustrating the transition of the rotor loss and operating point of the rotating electrical machine device 100 according to the second embodiment. It is determined that the magnet temperature threshold has been exceeded during operation at the operating point of point P. Then, in order to lower the magnet temperature, the constant torque curve is transitioned from point P to point Q1 so that the q-axis current is reduced and the d-axis current is increased to the negative side, without changing the output torque from point P. Although the operating point has transitioned to point Q1, the permanent magnet temperature sensor detection value temp_mag does not become equal to or less than the magnet temperature threshold. In this state, the magnet temperature settling time elapses, and output suppression is performed. As a result, the constant torque curve transitions (in FIG. 10, tq_cnst_curve moves from the dashed line to the solid line). As the constant torque curve transitions, the operating point gradually transitions to point Q, where the permanent magnet temperature sensor detection value temp_mag matches the magnet temperature threshold.

[0109] <Changes in magnet temperature> 11 is a time chart showing the magnet temperature of the rotor of the rotating electrical machine device 100 according to embodiment 2. The actual temperature has a transient waveform such as a first-order lag response, but is simply illustrated as a straight line.

[0110] First, as in the first embodiment, the operating point transitions from an initial operating point where the torque command Tq* is lower than point P to point P, and the permanent magnet temperature sensor detection value temp_mag gradually increases and eventually reaches the magnet temperature threshold. After the permanent magnet temperature sensor detection value temp_mag exceeds the magnet temperature threshold, the operating point transitions to point Q1, which is the maximum value on the negative side of the d-axis current, in order to lower the temperature.

[0111] Although the operating point has transitioned to point Q1, the permanent magnet temperature sensor detection value temp_mag continues to exceed the magnet temperature threshold. Since the magnet temperature settling time has elapsed without the operating point changing since the transition to point Q1 (the period from point Q1 to point Q2 in the diagram), the maximum id operating point determination unit 991 sets the magnet temperature output suppression permission signal tmag_psave to 1 for the first time and outputs it. The magnet temperature output suppression unit 992 receives permission to suppress torque and executes predetermined processing to output a post-suppression torque command Tq*_ctl, which is the torque command Tq* that has been reduced.

[0112] By repeating this process, the post-suppression torque command Tq*_ctl and the operating point gradually transition, and eventually the permanent magnet temperature sensor detection value temp_mag and the magnet temperature threshold value match. The operating point at this point is point Q.

[0113] In the above, in the second embodiment, an aspect in which an output suppression unit 99 is added to the configuration of the first embodiment has been described. The control device 9 calculates a target d-axis current and a target q-axis current based on an output command value. When the permanent magnet temperature sensor detection value temp_mag detected by the permanent magnet temperature sensor 25 is higher than the magnet temperature threshold and the target d-axis current becomes smaller (the absolute value becomes larger) than a predetermined negative demagnetization prevention d-axis current threshold id_lmt, the control device 9 reduces the output command value so that the target d-axis current does not become smaller than the negative demagnetization prevention d-axis current threshold id_lmt. This makes it possible to realize a rotating electrical machine device 100 that can minimize output suppression as much as possible even in situations where the demagnetization temperature cannot be prevented from being reached by simply moving the operating point on the constant torque curve, and output suppression is unavoidable.

[0114] Furthermore, the control device 9 calculates a target d-axis current and a target q-axis current based on the output command value, and reduces the output command value if the permanent magnet temperature sensor detection value temp_mag detected by the permanent magnet temperature sensor 25 remains higher than the magnet temperature threshold for a predetermined waiting time after the target d-axis current has changed to the demagnetization prevention d-axis current threshold id_lmt. By providing a waiting time that can be determined based on the thermal resistance, heat capacity, etc. of the rotating electric machine 1, it is possible to prevent the output command value from being reduced unnecessarily, thereby realizing a rotating electric machine device 100 that can minimize output suppression as much as possible.

[0115] These features make it possible to maintain output while exerting an even greater demagnetization suppression effect than in the previous embodiment 1. This eliminates the need to add large amounts of rare earth element additives such as terbium and dysprosium in order to raise the demagnetization temperature of the permanent magnet, thereby reducing costs.

[0116] 3. Embodiment 3 In the third embodiment, a situation is assumed in which output suppression is forced by other components due to an operating point transition in the configuration of the second embodiment. A rotating electrical machine device 100 that effectively coordinates countermeasures against demagnetization of permanent magnets with output suppression by other components will be described. Note that in the third embodiment, explanations of the same points as in the first and second embodiments will be omitted, and the explanation will focus on the points that are different.

[0117] <Controller function block> Fig. 12 is a functional block diagram showing the signal processing process of the control device 9 of the rotating electrical machine device 100 according to the third embodiment. In the third embodiment, an operating point adjusting unit 93a and an output suppressing unit 99a are modified from the functional block diagram of Fig. 8 according to the second embodiment.

[0118] <Operating point adjustment section> 13 is a functional block diagram showing the signal processing process of the operating point adjuster 93a of the control device 9 of the rotary electric machine device 100 according to the third embodiment. The processing of the Id* limiter 933 is changed from that of the first and second embodiments.

[0119] In addition to the components of the previous embodiment, the Id* limiting unit 933a additionally receives an output suppression permission signal Tj_psave based on the switching element temperature from the output suppressing unit 99a, and calculates the d-axis current command Id*.

[0120] Specifically, whether or not to execute the function described in the previous embodiment is determined based on the state of the signal Tj_psave permitting output reduction due to switching element temperature. The signal Tj_psave permitting output reduction due to switching element temperature is a signal that can distinguish between three states. One is a state in which output reduction due to switching element temperature is not being performed, defined as 0. The other is a state in which output reduction due to switching element temperature is being performed, and the detected value temp_Tj of the switching element temperature sensor 7 is greater than the switching element temperature threshold, defined as 1. The other is a state in which output reduction due to switching element temperature is being performed, and the detected value temp_Tj of the switching element temperature sensor 7 is equal to or less than the switching element temperature threshold, defined as 2. In this case, when the signal Tj_psave permitting output reduction due to switching element temperature is 0 or 2, the function described in the previous embodiment is executed. When the signal Tj_psave permitting output reduction due to switching element temperature is 1, the system operates to continue outputting the previous value of the d-axis current command Id*.

[0121] <Output suppression unit> 14 is a functional block diagram showing the signal processing process of the output suppression unit of the control device 9 of the rotating electrical machine device 100 according to embodiment 3. Compared to embodiment 2, the processing of the output suppression unit 992 based on magnet temperature is changed, and an output suppression unit 993 based on switching element temperature and a minimum value determination unit 994 are added.

[0122] In addition to the above embodiment, the magnet temperature-based output suppression unit 992a additionally receives an output suppression permission signal Tj_psave based on switching element temperature from a switching element temperature-based output suppression unit 993. Then, it calculates a suppression torque command Tq*_mag based on magnet temperature.

[0123] Specifically, the calculation method of the suppression torque command Tq*_mag based on the magnet temperature is changed based on the state of the switching element temperature-based output suppression permission signal Tj_psave. When the switching element temperature-based output suppression permission signal Tj_psave is 0 according to the definitions described above, the function described in the previous embodiment is executed.

[0124] When the signal Tj_psave allowing output suppression due to switching element temperature is 1, a torque command Tq* is output as a suppression torque command Tq*_mag due to magnet temperature. In addition, the current amount at this time, for example the square root of the sum of the squares of the d-axis current and q-axis current, is calculated and continuously updated. The final value of the d-axis current command calculated when the signal Tj_psave allowing output suppression due to switching element temperature changes from 0 to 1 is stored, and the d-axis current command is fixed so that it does not exceed this value.

[0125] When the switching element temperature output suppression permission signal Tj_psave is 2, the next d-axis current value is determined by correcting the previous d-axis current command value Id*_pre based on the difference between the permanent magnet temperature sensor detection value temp_mag and the magnet temperature threshold. When the switching element temperature output suppression permission signal Tj_psave is 1, the torque that can be output with the next d-axis current can be output as the magnet temperature suppression torque command Tq*_mag so that the final value of the calculated current amount is not changed. For example, the output torque can be calculated by calculating the q-axis current value from the final value of the current amount calculated earlier and the next d-axis current value. Note that if the permanent magnet temperature sensor detection value temp_mag exceeds the magnet temperature threshold, the previous d-axis current command value Id*_pre is corrected in the negative direction, i.e., so that the magnet temperature decreases. PI control is preferred as the correction method. The next d-axis current value is also limited by the demagnetization prevention d-axis current threshold id_lmt, which is the maximum d-axis current value that does not cause demagnetization due to an external magnetic field.

[0126] The output suppression unit 993 based on switching element temperature receives the torque command Tq* and the detected value temp_Tj of the switching element temperature sensor 7, and calculates the output suppression permission signal Tj_psave based on switching element temperature and the post-suppression torque command Tq*_chip based on switching element temperature.

[0127] As mentioned above, the output suppression permission signal Tj_psave due to switching element temperature is a signal that can identify the output suppression state due to switching element temperature as 0, 1, or 2, and the state can be determined by comparing the detection value temp_Tj of the switching element temperature sensor 7 with a predetermined switching element temperature threshold value.

[0128] In addition, similar to the PI controller of the output suppression unit 992a based on magnet temperature, the torque command Tq*_chip after suppression based on switching element temperature is calculated by PI control of the torque command Tq* and the difference between the detected value temp_Tj of the switching element temperature sensor 7 and a predetermined switching element temperature threshold.

[0129] A minimum value determination unit 994 selects the smaller of the suppression torque command Tq*_mag based on the magnet temperature and the post-suppression torque command Tq*_chip based on the switching element temperature, and outputs it as the post-suppression torque command Tq*ctl.

[0130] <Operating point transition> 15 is a diagram showing rotor loss and transition of the operating point of the rotating electrical machine device 100 according to embodiment 3. The transition of the operating point when the processing of embodiment 3 is executed will be described with reference to FIGS.

[0131] When it is determined that the magnet temperature threshold has been exceeded, in order to lower the magnet temperature, the q-axis current is reduced on the constant torque curve without changing the output torque from point P, and the d-axis current is changed to the negative side, causing a transition from point P to point Q1. The operating point has transitioned to point Q1, but the magnet temperature settling time, which is a predetermined waiting time, has elapsed without the permanent magnet temperature sensor detection value temp_mag becoming equal to or lower than the magnet temperature threshold, and output suppression is executed, causing the constant torque curve to transition (in Figure 15, tq_cnst_curve transitions from the dashed line to the solid line). As the constant torque curve transitions, the operating point transitions to Q2. Thereafter, it gradually transitions to point Q, where the permanent magnet temperature sensor detection value temp_mag and the magnet temperature threshold match.

[0132] <Changes in magnet temperature and switching element temperature> 16 is a time chart showing the magnet temperature of the rotor of the rotating electrical machine device 100 according to the third embodiment and the switching element temperature of the control device 9. The temperature waveform is shown in chronological order. While the actual temperature waveform will be a transient waveform such as a first-order lag response, it is depicted as a simplified straight line.

[0133] First, the operating point transitions from an initial operating point where the torque command Tq* is lower than point P to point P, and the permanent magnet temperature sensor detection value temp_mag gradually increases. At the same time, the detection value temp_Tj of the switching element temperature sensor 7 also increases. These events are shown in the upper and lower parts of FIG.

[0134] The permanent magnet temperature sensor detection value temp_mag gradually rises after transitioning to point P and eventually reaches the magnet temperature threshold. This moment is represented as point P1 in FIG. 16. After passing point P1, the operating point adjustment unit 93a transitions the operating point so that the d-axis current increases and the q-axis current decreases. Point P1 indicates the same operating point as point P in FIG. 15.

[0135] At this time, as the operating point transitions, the amplitude of the three-phase AC current gradually increases, and the detected value temp_Tj of the switching element temperature sensor 7 gradually rises. Eventually, the detected value temp_Tj of the switching element temperature sensor 7 reaches the switching element temperature threshold value.

[0136] When the detection value temp_Tj of the switching element temperature sensor 7 reaches the switching element temperature threshold, the output suppression unit 993 changes the switching element temperature output suppression permission signal Tj_psave from 0 to 1. It also starts calculating the square root of the sum of the squares of the d-axis current and the q-axis current as the current amount. The operating point at this time is point Q1 in the diagram. When point Q1 is reached, the PI controller of the switching element temperature output suppression unit 993 suppresses the output torque so that the detection value temp_Tj of the switching element temperature sensor 7 matches the switching element temperature threshold.

[0137] The minimum value determination unit 994 outputs the suppressed torque command Tq*_chip based on the switching element temperature, which is the suppressed torque. Note that the suppressed torque command Tq*_mag based on the magnet temperature outputs the torque command Tq*.

[0138] Because the switching element temperature-based output reduction permission signal Tj_psave is 1, the Id* limiting unit 933a continues to output the final value when the switching element temperature-based output reduction permission signal Tj_psave was 0, i.e., the previous value of the d-axis current command Id*, and keeps the permanent magnet temperature sensor detected value temp_mag constant.Then, the q-axis current command Iq* is reduced to reduce the output.

[0139] The PI controller of the switching element temperature output suppression unit 993 causes the detection value temp_Tj of the switching element temperature sensor 7 to match the switching element temperature threshold. At this moment, the output suppression unit 993 changes the switching element temperature output suppression permission signal Tj_psave from 1 to 2. The operating point at this time is point Q2 in the diagram.

[0140] When the signal Tj_psave allowing output suppression due to switching element temperature becomes 2, the amount of current calculated when the signal Tj_psave allowing output suppression due to switching element temperature was 1 is not changed, and the torque that can be output is calculated from the d-axis current obtained by correcting the previous value Id*_pre of the d-axis current command so that the permanent magnet temperature sensor detection value temp_mag matches the magnet temperature threshold, and this is output as the suppression torque command Tq*_mag due to magnet temperature.

[0141] By repeating this process, the operating point gradually shifts, the temperature drops, and eventually the permanent magnet temperature sensor detection value temp_mag and the magnet temperature threshold value match. The operating point at this point is point Q.

[0142] At point Q2, the magnet temperature threshold is lower than the permanent magnet temperature sensor detection value temp_mag, so this embodiment 3 has been described as lowering the temperature, but if the magnet temperature threshold is high, the temperature may be increased.

[0143] In the above, the d-axis current command Id* is stored at the time when the output reduction permission signal Tj_psave due to switching element temperature changes from 0 to 1 (i.e., when the temperature of the switching element exceeds the switching element temperature threshold). Then, the control has been described in which the d-axis current command Id* is fixed to this value while the output reduction permission signal Tj_psave is 1.

[0144] Here, instead of the d-axis current command Id* at the time when the output reduction permission signal Tj_psave based on switching element temperature changes from 0 to 1 (i.e., when the temperature of the switching element exceeds the switching element temperature threshold), the value of the square root of the sum of the squares of the currents in the d-axis and q-axis directions may be stored. Then, the d-axis current command Id* and the command q-axis current Iq* may be calculated so that the output is limited within a range where the value of the square root of the sum of the squares of the currents in the d-axis and q-axis directions is equal to or less than the stored value while the output reduction permission signal Tj_psave is 1. This is advantageous because it allows both the temperature of the permanent magnets and the temperature of the switching elements to be reduced in a balanced manner.

[0145] Although an example of using the output torque suppression unit based on the semiconductor switching element temperature has been described, this is not a limitation. Component temperature sensors that detect the temperatures of other components, such as capacitor temperature sensor 24 that detects the temperature of smoothing capacitor 22, and coil temperature sensor 26 that detects the temperatures of U-phase coil 11, V-phase coil 12, and W-phase coil 13, may also be provided.

[0146] An output torque suppression unit may be provided that suppresses the output torque when the temperature detected by the component temperature sensor is higher than a predetermined component temperature threshold. In this case, the output torque suppression control may be the same as the control for the switching element temperature.

[0147] As described above, the third embodiment includes the switching element temperature sensor 7 that detects the temperatures of the switching elements 311 to 316 of the power conversion circuit 3, and the control device 9 calculates the target d-axis current and the target q-axis current based on the output command value, and reduces the output command value when the detected value temp_Tj detected by the switching element temperature sensor 7 is higher than a predetermined switching element temperature threshold. This makes it possible to realize a rotating electric machine device 100 in which the temperature of the permanent magnets does not reach a temperature at which irreversible demagnetization occurs and in which the temperatures of components other than the permanent magnets do not rise excessively.

[0148] Furthermore, the control device 9 stores the value of the target d-axis current when the detected value temp_Tj detected by the switching element temperature sensor 7 exceeds the switching element temperature threshold, and fixes the target d-axis current to the stored value while the detected value temp_Tj detected by the switching element temperature sensor 7 is greater than the switching element temperature threshold. This prevents the target d-axis current from accidentally changing in the negative direction (increasing its absolute value) and approaching or exceeding the d-axis current threshold id_lmt for preventing demagnetization of the permanent magnet. This prevents the temperature of the permanent magnet from reaching a temperature at which irreversible demagnetization occurs, and realizes a rotating electrical machine 100 that does not excessively increase the temperatures of components other than the permanent magnet.

[0149] Furthermore, the control device 9 stores the square root of the sum of the squares of the target d-axis current value and the target q-axis current value when the detected value temp_Tj detected by the switching element temperature sensor 7 exceeds the switching element temperature threshold, and while the detected value temp_Tj detected by the switching element temperature sensor 7 is greater than the switching element temperature threshold, the control device 9 changes the target d-axis current and the target q-axis current within a range where the square root of the sum of the squares of the target d-axis current value and the target q-axis current value is equal to or less than the stored square root. This makes it possible to reduce both the temperature of the permanent magnets and the temperature of the switching elements in a balanced manner.

[0150] The control device 9 is also provided with component temperature sensors that detect the temperatures of other components, such as a capacitor temperature sensor 24 that detects the temperature of the smoothing capacitor 22 of the power conversion circuit 3, or a coil temperature sensor 26 that detects the temperature of the coils 11 to 13 of the rotating electric machine 1, and calculates the target d-axis current and the target q-axis current based on the output command value, and reduces the output command value if the component temperature detected by the component temperature detector is higher than a predetermined component temperature threshold. This makes it possible to realize a rotating electric machine device 100 that, by effectively using a component output torque suppression unit, prevents the temperature of the permanent magnets from reaching a temperature at which irreversible demagnetization occurs and prevents the temperatures of components other than the permanent magnets from excessively rising.

[0151] The switching elements of the inverter unit 31 may be made of any semiconductor element, for example, a wide bandgap semiconductor, such as silicon carbide (SiC) or gallium nitride (GaN).

[0152] As mentioned above, an inverter unit with switching elements made of wide bandgap semiconductors has the advantages of being highly heat-resistant, low-loss, and capable of high-frequency operation, compared to inverter units with switching elements made of Si. Therefore, by using wide bandgap semiconductors for the switching elements of the inverter unit, it is possible to achieve a rotating electric machine 100 that can reduce the temperature of the permanent magnets more effectively by reducing heat generation with low loss and providing high heat resistance, thereby making it possible to appropriately increase the d-axis current and decrease the q-axis current over a wider operating range.

[0153] Although various exemplary embodiments and examples are described in this disclosure, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are contemplated within the scope of the technology disclosed in this disclosure specification. For example, this includes cases where at least one component is modified, added, or omitted, or where at least one component is extracted and combined with components of another embodiment.

[0154] Various aspects of the present disclosure are summarized below as appendices.

[0155] (Appendix 1) A rotating electric machine having a stator provided with windings and a rotor provided with permanent magnets; a power conversion circuit connected to a DC power supply and supplying current to the windings of the rotating electric machine via a switching element; a temperature detector for detecting the temperature of the permanent magnet of the rotating electric machine; and a control device that calculates a target d-axis current and a target q-axis current, and controls switching elements of the power conversion circuit based on the target d-axis current and the target q-axis current, The control device changes the target d-axis current in a negative direction and reduces the absolute value of the target q-axis current to maintain the output of the rotating electric machine when the temperature of the permanent magnet detected by the temperature detector is higher than a predetermined magnet temperature threshold. (Appendix 2) The rotating electric machine device according to Appendix 1, wherein when the temperature of the permanent magnet detected by the temperature detector becomes higher than the magnet temperature threshold, the control device changes the target d-axis current in a negative direction and reduces the absolute value of the target q-axis current so that the temperature of the permanent magnet coincides with the magnet temperature threshold. (Appendix 3) The rotating electric machine device according to Appendix 1, wherein the control device changes the target d-axis current in a negative direction on a constant torque curve when the temperature of the permanent magnet detected by the temperature detector is higher than the magnet temperature threshold value, and reduces the absolute value of the target q-axis current to maintain the output of the rotating electric machine. (Appendix 4) 2. The rotating electric machine according to claim 1, wherein the control device changes the target d-axis current and the target q-axis current within a range of a maximum rated current curve set in a coordinate system of the d-axis current and the q-axis current. (Appendix 5) 2. The rotating electrical machine according to claim 1, wherein the control device changes the target d-axis current within a range equal to or greater than a predetermined negative demagnetization prevention d-axis current threshold. (Appendix 6) 6. The rotating electric machine according to claim 5, wherein the control device changes the demagnetization prevention d-axis current threshold in accordance with the temperature of the permanent magnet detected by the temperature detector. (Appendix 7) The rotating electric machine device of Appendix 1, wherein the control device calculates the target d-axis current and the target q-axis current based on an output command value, and when the temperature of the permanent magnet detected by the temperature detector is higher than the magnet temperature threshold and the target d-axis current becomes smaller than a predetermined negative demagnetization prevention d-axis current threshold, reduces the output command value so that the target d-axis current does not become smaller than the negative demagnetization prevention d-axis current threshold. (Appendix 8) The rotating electric machine device according to Appendix 5, wherein the control device calculates the target d-axis current and the target q-axis current based on an output command value, and reduces the output command value if, after the target d-axis current changes to the demagnetization prevention d-axis current threshold, the temperature of the permanent magnet detected by the temperature detector remains higher than the magnet temperature threshold for a predetermined waiting time. (Appendix 9) a switching element temperature detector for detecting the temperature of the switching element of the power conversion circuit; The rotating electric machine device according to claim 1, wherein the control device calculates the target d-axis current and the target q-axis current based on an output command value, and reduces the output command value when the temperature of the switching element detected by the switching element temperature detector is higher than a predetermined switching element temperature threshold value. (Appendix 10) 10. The rotating electric machine device according to claim 9, wherein the control device stores the value of the target d-axis current when the temperature of the switching element detected by the switching element temperature detector exceeds the switching element temperature threshold, and fixes the target d-axis current to the stored value during a period in which the temperature of the switching element is greater than the switching element temperature threshold. (Appendix 11) The rotating electric machine device according to Appendix 9, wherein the control device stores the square root of the sum of the squares of the target d-axis current value and the target q-axis current value when the temperature of the switching element detected by the switching element temperature detector exceeds the switching element temperature threshold, and changes the target d-axis current and the target q-axis current so that the square root of the sum of the squares of the target d-axis current value and the target q-axis current value is equal to or less than the stored square root during a period when the temperature of the switching element is greater than the switching element temperature threshold. (Appendix 12) a component temperature detector for detecting a component temperature, which is a temperature of a capacitor in the power conversion circuit or a temperature of a coil of the rotating electric machine; 12. The rotating electric machine device according to any one of appendixes 1 to 11, wherein the control device calculates the target d-axis current and the target q-axis current based on an output command value, and reduces the output command value when the component temperature detected by the component temperature detector is higher than a predetermined component temperature threshold value. [Explanation of symbols]

[0156] 1 rotating electric machine, 3 power conversion circuit, 5 rotation angle sensor, 7 switching element temperature sensor, 9 control device, 11 U-phase coil, 12 V-phase coil, 13 W-phase coil, 21 DC power supply, 22 smoothing capacitor, 24 capacitor temperature sensor, 25 permanent magnet temperature sensor, 26 coil temperature sensor, 100 rotating electric machine device, 311, 312, 313, 314, 315, 316 switching element

Claims

1. A rotating electric machine having a stator provided with windings and a rotor provided with permanent magnets; a power conversion circuit connected to a DC power supply and supplying current to the windings of the rotating electric machine via a switching element; a temperature detector for detecting the temperature of the permanent magnet of the rotating electric machine; and a control device that calculates a target d-axis current and a target q-axis current, and controls switching elements of the power conversion circuit based on the target d-axis current and the target q-axis current, The control device changes the target d-axis current in a negative direction when the temperature of the permanent magnet detected by the temperature detector is higher than a predetermined magnet temperature threshold, and reduces the absolute value of the target q-axis current to maintain the output of the rotating electric machine.

2. 2. The rotating electric machine device according to claim 1, wherein when the temperature of the permanent magnet detected by the temperature detector becomes higher than the magnet temperature threshold, the control device changes the target d-axis current in a negative direction and reduces the absolute value of the target q-axis current so that the temperature of the permanent magnet matches the magnet temperature threshold.

3. 2. The rotating electric machine device according to claim 1, wherein when the temperature of the permanent magnet detected by the temperature detector is higher than the magnet temperature threshold, the control device changes the target d-axis current in a negative direction on a constant torque curve and reduces the absolute value of the target q-axis current to maintain the output of the rotating electric machine.

4. 2. The rotating electrical machine according to claim 1, wherein the control device changes the target d-axis current and the target q-axis current within a range of a maximum rated current curve set in a coordinate system of d-axis current and q-axis current.

5. The rotating electrical machine according to claim 1 , wherein the control device changes the target d-axis current within a range equal to or greater than a predetermined negative demagnetization prevention d-axis current threshold value.

6. The rotating electrical machine according to claim 5 , wherein the control device changes the demagnetization prevention d-axis current threshold value in accordance with the temperature of the permanent magnet detected by the temperature detector.

7. 2. The rotating electric machine device according to claim 1, wherein the control device calculates the target d-axis current and the target q-axis current based on an output command value, and when the temperature of the permanent magnet detected by the temperature detector is higher than the magnet temperature threshold and the target d-axis current becomes smaller than a predetermined negative demagnetization prevention d-axis current threshold, the control device reduces the output command value so that the target d-axis current does not become smaller than the negative demagnetization prevention d-axis current threshold.

8. 6. The rotating electric machine device according to claim 5, wherein the control device calculates the target d-axis current and the target q-axis current based on an output command value, and reduces the output command value if, after the target d-axis current changes to the demagnetization prevention d-axis current threshold, the temperature of the permanent magnet detected by the temperature detector remains higher than the magnet temperature threshold for a predetermined waiting time.

9. a switching element temperature detector for detecting the temperature of the switching element of the power conversion circuit; 2. The rotating electric machine device according to claim 1, wherein the control device calculates the target d-axis current and the target q-axis current based on an output command value, and reduces the output command value when the temperature of the switching element detected by the switching element temperature detector is higher than a predetermined switching element temperature threshold value.

10. 10. The rotating electric machine device according to claim 9, wherein the control device stores the value of the target d-axis current when the temperature of the switching element detected by the switching element temperature detector exceeds the switching element temperature threshold, and fixes the target d-axis current to the stored value during a period in which the temperature of the switching element is greater than the switching element temperature threshold.

11. 10. The rotating electric machine device according to claim 9, wherein the control device stores the square root of the sum of the squares of the target d-axis current value and the target q-axis current value when the temperature of the switching element detected by the switching element temperature detector exceeds the switching element temperature threshold, and changes the target d-axis current and the target q-axis current so that the square root of the sum of the squares of the target d-axis current value and the target q-axis current value is equal to or less than the stored square root during a period when the temperature of the switching element is greater than the switching element temperature threshold.

12. a component temperature detector for detecting a component temperature, which is a temperature of a capacitor in the power conversion circuit or a temperature of a coil of the rotating electric machine; 12. The rotating electric machine device according to claim 1, wherein the control device calculates the target d-axis current and the target q-axis current based on an output command value, and reduces the output command value when the component temperature detected by the component temperature detector is higher than a predetermined component temperature threshold value.

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