Rotating electric machine drive device, rotating electric machine system, and rotating electric machine drive method

Abstract

An object is to estimate the magnet temperature without requiring the installation of a voltage sensor or current change, and to efficiently drive and control a rotating electric machine. 【Solution means】In the control unit 4, a three-phase to two-phase conversion unit 48 that converts the current flowing through the winding 51c into the dq axes of the rotating coordinate system to calculate the actual d-axis current i d and the actual q-axis current i q , a current command generation unit 43 that generates a command d-axis current i rq * and a command q-axis current i d * from the torque command T q * and the rotational speed command N, a magnet temperature calculation unit 41 that calculates the magnet temperature φ d from the actual d-axis current i q and the actual q-axis current i d * and the command d-axis current i q * and the command q-axis current i mag , and a demagnetization determination unit 42 that determines the presence or absence of demagnetization from the actual d-axis current i d and the actual q-axis current i q and the magnet temperature φ mag are provided, and the control of the power converter 2 is configured to be adjusted according to the determination result of the demagnetization determination unit 42.

Description

[Technical Field]

[0001] This disclosure relates to a rotating electric machine drive device, a rotating electric machine system, and a rotating electric machine drive method. [Background technology]

[0002] In the drive control of rotating electric machines, a technique for estimating and controlling the temperature of the permanent magnets that form the magnetic poles is generally known. However, since the permanent magnets are contained within the rotor, it is difficult to measure their temperature by installing temperature sensors on them.

[0003] Therefore, a technique has been proposed to estimate the temperature of a permanent magnet from physical quantities other than temperature by measuring the phase current and line voltage of a rotating electric machine and calculating the magnetic flux of the permanent magnet using the phase current, line voltage, and inductance (see, for example, Patent Document 1). Alternatively, a technique has been proposed to calculate the magnetic flux of the permanent magnet by changing the target current and determining the d-axis linked magnetic flux before and after the current change, and then estimating the temperature according to the calculated magnetic flux of the permanent magnet (see, for example, Patent Document 2). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2019-129663 (paragraphs 0023-0038, Figures 1-4) [Patent Document 2] Japanese Patent Publication No. 2021-16226 (paragraphs 0017-0049, Figures 1-4) [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, estimating temperature from line voltage requires a voltage sensor to measure the line voltage, which increases costs. Furthermore, estimating temperature from magnetic flux before and after a current change requires a current change, making it impossible to estimate temperature in the absence of a current change, and eddy current losses increase with current changes.

[0006] This disclosure provides a technology to solve the above-mentioned problems, aiming to estimate magnet temperature without requiring the installation of a voltage sensor or current changes, and to efficiently drive and control a rotating electric machine. [Means for solving the problem]

[0007] The rotating electric machine drive device of the present disclosure is characterized by comprising: a power converter that converts power input from a power source and outputs phase power to the three-phase stator windings; a three-phase to two-phase conversion unit that converts the current flowing through the three-phase stator windings into the dq axis of a rotating coordinate system and calculates actual d-axis current and actual q-axis current; a current command generation unit that generates command d-axis current and command q-axis current for setting the phase power from a torque command and a rotation speed command; a magnet temperature calculation unit that calculates the temperature of the permanent magnet from the actual d-axis current, the actual q-axis current, the command d-axis current and the command q-axis current; and a demagnetization determination unit that determines whether or not the permanent magnet has been demagnetized from the actual d-axis current, the actual q-axis current and the calculated temperature of the permanent magnet, and a control unit that adjusts the control of the power converter according to the determination result of the demagnetization determination unit.

[0008] The rotating electric machine driving method of the present disclosure is a method for driving and controlling a rotating electric machine comprising a stator provided with three-phase stator windings and a rotor whose magnetic poles are formed by permanent magnets, by converting power input from a power source into phase power to the three-phase stator windings, and is characterized by including: a current command generation step of generating a command d-axis current and a command q-axis current for setting the phase power from a torque command and a rotational speed command; a three-phase to two-phase conversion step of converting the current flowing through the three-phase stator windings into the dq axes of a rotating coordinate system and calculating the actual d-axis current and the actual q-axis current; a magnet temperature calculation step of calculating the temperature of the permanent magnet from the actual d-axis current, the actual q-axis current, the command d-axis current and the command q-axis current; a demagnetization determination step of determining whether or not the permanent magnet has been demagnetized from the actual d-axis current, the actual q-axis current and the calculated temperature of the permanent magnet; and a step of adjusting the conversion to phase power according to the determination result in the demagnetization determination step. [Effects of the Invention]

[0009] According to the rotating electric machine drive device or rotating electric machine drive method of this disclosure, the magnet temperature is estimated from the d-axis current and the q-axis current, so the rotating electric machine can be efficiently driven and controlled without the need to install a voltage sensor or change the current. [Brief explanation of the drawing]

[0010] [Figure 1] This is a block diagram showing the configuration of a rotating electric machine system comprising a rotating electric machine drive device according to Embodiment 1 and a rotating electric machine driven by it. [Figure 2] This is a cross-sectional view perpendicular to the axis of the rotating electric machine that constitutes the rotating electric machine system according to Embodiment 1. [Figure 3] This block diagram shows a modified example of Embodiment 1, comprising a rotating electric machine drive device that uses an AC power supply as input, and a rotating electric machine system equipped with a rotating electric machine. [Figure 4] This is a block diagram showing the configuration of the control unit of the rotating electric machine drive device according to Embodiment 1. [Figure 5]This is a flowchart showing the operation of a rotating electric machine drive device or a rotating electric machine drive method according to Embodiment 1. [Figure 6] This is a block diagram showing the hardware configuration of the control unit constituting the rotating electric machine drive device according to Embodiment 1. [Figure 7] Figures 7A and 7B are schematic diagrams showing the d-axis inductance map and the q-axis inductance map, respectively, for use in calculations in the rotating electric motor drive device or rotating electric motor drive method according to Embodiment 1, for the d-axis current and q-axis current at the temperature of a certain permanent magnet. [Figure 8] This is a schematic diagram showing a map of the d-axis magnetic flux with respect to the d-axis current and q-axis current at a certain temperature of a permanent magnet, for use in calculations in a rotating electric machine drive device or rotating electric machine drive method according to Embodiment 1. [Figure 9] This is a schematic diagram in tabular form showing the relationship between magnetic flux and magnetic temperature, for use in calculations in the rotating electric machine drive device or rotating electric machine drive method according to Embodiment 1. [Figure 10] This is a cross-sectional view perpendicular to the axis of another type of rotating electric machine that constitutes the rotating electric machine system according to Embodiment 1. [Figure 11] This is an enlarged, perpendicular cross-sectional view of the permanent magnet portion of the rotor in another type of rotating electric machine that constitutes the rotating electric machine system according to Embodiment 1. [Figure 12] This is a schematic diagram in graph form showing the characteristics of the permanent magnet used in the rotating electric machine that constitutes the rotating electric machine system according to Embodiment 1. [Figure 13] This is a schematic diagram showing a map of demagnetization rates for d-axis current and q-axis current at different magnet temperatures, for use in calculations in the rotating electric machine drive device or rotating electric machine drive method according to Embodiment 1. [Figure 14] This is a tabular diagram showing the relationship between magnet temperature and demagnetization current threshold, for use in calculations in the rotating electric machine drive device or rotating electric machine drive method according to Embodiment 1. [Figure 15]This is a schematic diagram showing the time-dependent changes in the commanded d-axis current and commanded q-axis current when demagnetization is detected in the rotating electric machine drive device or rotating electric machine drive method according to Embodiment 1. [Figure 16] This is a schematic diagram showing the relationship between the first and second threshold values ​​of the demagnetization rate used in the rotating electric machine drive device or rotating electric machine drive method according to Embodiment 1. [Figure 17] This flowchart shows the operation control in accordance with the demagnetization determination result in a rotating electric machine drive device or rotating electric machine drive method according to Embodiment 1. [Modes for carrying out the invention]

[0011] Embodiment 1. Figures 1 to 17 illustrate the operation and configuration of a rotating electric machine system, including a rotating electric machine driven by a rotating electric machine, according to Embodiment 1, and a method for driving a rotating electric machine. Figure 1 is a block diagram showing the configuration of a rotating electric machine system comprising a rotating electric machine drive device operating on DC power input and a rotating electric machine driven by it. Figure 2 is a cross-sectional view perpendicular to the axes of the stator and rotor, which are the main components of a surface magnet type synchronous rotating electric machine that constitutes the rotating electric machine system. Figure 3 is a modified example, a block diagram showing the configuration of a rotating electric machine system comprising a rotating electric machine drive device operating on AC power input and a rotating electric machine. Figure 4 is a block diagram showing the configuration of the control unit of the rotating electric machine drive device.

[0012] Figure 5 is a flowchart illustrating the operation of the rotating electric drive device and the method of driving the rotating electric drive device, and Figure 6 is a block diagram showing the hardware configuration of the control unit that constitutes the rotating electric drive device.

[0013] Furthermore, Figures 7A to 79 show data used in calculations for a rotating electric machine drive device or rotating electric machine drive method. Figure 7A is a schematic tabular diagram showing a map of d-axis inductance for d-axis current and q-axis current at a given temperature of a permanent magnet, Figure 7B is a schematic diagram showing a map of q-axis inductance for d-axis current and q-axis current at a given temperature of a permanent magnet, Figure 8 is a schematic diagram showing a map of d-axis magnetic flux for d-axis current and q-axis current at a given temperature of a permanent magnet, and Figure 9 is a schematic tabular diagram showing the relationship between magnet magnetic flux and magnet temperature.

[0014] Furthermore, Figure 10 is a cross-sectional view perpendicular to the axis of the stator and rotor, which are the main components of an embedded magnet type synchronous rotating electric machine that constitutes a rotating electric machine system, and Figure 11 is an enlarged cross-sectional view of the permanent magnet portion of the rotor shown in Figure 10.

[0015] Figure 12 is a schematic graph plotting the characteristics of permanent magnets used in a rotating electric machine that constitutes a rotating electric machine system, with the horizontal axis representing the magnetic field and the vertical axis representing the magnetic flux density. Figure 13 is a schematic diagram showing the demagnetization rate with respect to the d-axis current and q-axis current for each magnet temperature, which have been stored for use in calculations. Figure 14 is a tabular diagram showing the relationship between magnet temperature and the demagnetization current threshold, which have been stored for use in calculations.

[0016] Figure 15 is a schematic graph showing the time-dependent changes in the commanded d-axis current and commanded q-axis current when demagnetization is detected, with the horizontal axis representing time and the vertical axis representing current. Figure 16 is a schematic diagram showing the relationship between the first and second threshold values ​​of the demagnetization rate used to determine whether or not demagnetization has occurred. Figure 17 is a flowchart illustrating the operation of a rotating electric machine drive device, or a method of driving a rotating electric machine, by explaining the operation control according to the demagnetization rate.

[0017] Before describing the details of the rotating electric machine drive device and rotating electric machine drive method of this disclosure, the general configuration of the rotating electric machine drive device and rotating electric machine system will be described. As shown in Figure 1, the rotating electric machine drive device 1 converts the input power from a power source such as a DC power supply 70 into power suitable for driving the rotating electric machine 5 and controls the driving of the rotating electric machine 5.

[0018] Therefore, the rotating electric machine drive unit 1 includes a power converter 2 that converts input power into AC power of a desired frequency, and a control unit 4 that controls the operation of the power converter 2. The rotating electric machine drive unit 1 and the rotating electric machine 5 constitute a rotating electric machine system. The power converter 2 is connected to the DC power supply 70 via DC buses 25a and 25b through a power switch 80, and exchanges drive power and regenerative power with the DC power supply 70. The power converter 2 is also connected to the rotating electric machine 5 via an AC bus 24, and exchanges drive power and regenerative power with the rotating electric machine 5.

[0019] As shown in Figure 2, the rotating electric machine 5 comprises a stator 51 equipped with windings 51c and a rotor 52, which is a rotating body, as well as a rotation angle sensor 5s for detecting the rotation angle of the rotor 52. The rotor 52 is also equipped with permanent magnets 52m for forming magnetic poles. In the figure, the rotating electric machine 5 is shown as a surface-permanent magnet synchronous rotating electric machine in which the permanent magnets 52m are attached to the outer circumferential surface 52fo of the rotor 52, but it is not limited to this.

[0020] For example, an Interior Permanent Magnet Synchronous Machine (see Figure 10) may be used, in which the permanent magnet 52m, described later, is embedded inside the outer circumferential surface 52fo of the rotor 52. The rotation angle sensor 5s detects the rotor rotation angle of the electric machine 5 using a resolver, encoder, magnetic sensor, etc. The rotor rotation angle detected by the rotation angle sensor 5s is output to the control unit 4.

[0021] The power converter 2 includes a capacitor 21 connected to DC buses 25a and 25b on the power input side, a power conversion circuit 22 having a plurality of switching elements 221 to 226 to convert DC power to AC power, and a rotating electric machine current detection unit 23 that detects the current of the rotating electric machine 5 flowing through the AC bus 24.

[0022] The power conversion circuit 22 is an inverter with six switching elements 221 to 226 connected in a full bridge configuration. Switching elements 221 and 222, switching elements 223 and 224, and switching elements 225 and 226 are connected in series with each other and in parallel with the DC power supply 70. The midpoints of switching elements 221 and 222 are connected to the U-phase input of the rotating electric machine 5, the midpoints of switching elements 223 and 224 are connected to the V-phase input, and the midpoints of switching elements 225 and 226 are connected to the W-phase input.

[0023] Here, the switching elements 221, 223, and 225 connected to the DC bus 25a are referred to as the upper switching elements, and the switching elements 222, 224, and 226 connected to the DC bus 25b are referred to as the lower switching elements. The switching elements are not limited to MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) as shown in the figure, but other switching elements such as IGBTs (Insulated Gate Bipolar Transistors) can also be used.

[0024] Furthermore, each MOSFET used as a switching element is provided with a Free Wheeling Diode (FWD) in parallel, with the forward direction being from the negative terminal side to the positive terminal side of the DC power supply 70, that is, from the lower stage side to the upper stage side.

[0025] The rotating electric machine current detection unit 23 detects the current flowing through the AC bus 24 and converts the current into a voltage to output the rotating electric machine current information to the control unit 4. The figure shows a configuration in which the current is detected by a shunt resistor, but this is not the only option, and a current sensor using a magnetic sensor such as a Hall element may also be used.

[0026] The power switch 80 controls the power transfer between the DC power supply 70 and the power converter 2. When the voltage of the DC power supply 70 exceeds a set value during regenerative operation of the rotating electric machine 5, the power switch 80 is controlled by a higher-level system to open, thereby disconnecting the DC power supply 70 from the power converter 2. Alternatively, if the voltage of the DC power supply 70 falls below a set value due to a decrease in the State of Charge (SOC), or if the current flowing through the DC power supply 70 exceeds a set value, the power switch 80 is controlled by a higher-level system to open, thereby disconnecting the DC power supply 70 from the power converter 2. The power switch 80 may also be configured to be controlled by a control unit 4 (as a higher-level system).

[0027] As shown in Figure 3, a single-phase AC power supply 90 may be used as the power source. In this case, a reactor 27 and a rectifier diode 26 are added to the power converter 2. The reactor 27 corrects the power factor, the rectifier diode 26 performs full-wave rectification, and the AC is converted to DC by smoothing with the capacitor 21. In addition to diodes, MOSFETs and IGBTs may also be used for rectification.

[0028] The control unit 4 includes a magnet temperature calculation unit 41 that calculates the magnet temperature and a demagnetization determination unit 42 that determines whether or not demagnetization has occurred based on the calculated magnet temperature. The magnet temperature calculation unit 41 calculates the magnet temperature based on the current value detected by the rotating electric current detection unit 23 and the rotation angle information from the rotation angle sensor 5s, and the demagnetization determination unit 42 determines demagnetization based on the calculated magnet temperature and controls the switching element.

[0029] The configuration and operation of the control unit 4 will be explained in more detail. In addition to the magnet temperature calculation unit 41 and demagnetization determination unit 42 described above, the control unit 4 includes a current command generation unit 43, a voltage command generation unit 44, a voltage control unit 45, a PWM signal generation unit 46 (Pulse Width Modulation), a voltage calculation unit 47, a three-phase to two-phase conversion unit 48, and a carrier frequency selection unit 49, as shown in Figure 4. The magnet temperature calculation unit 41 is provided with an inductance calculation unit 411, a magnet magnetic flux calculation unit 412, and a magnet magnetic flux to magnet temperature conversion unit 413.

[0030] The current command generation unit 43 generates a command d-axis current i rq * and a command q-axis current i d * based on the torque command T q * and the rotational speed command N (step S100). The d-axis indicates the direction in which the magnetic flux of the permanent magnet 52m provided in the rotor 52 of the rotating electrical machine 5 is generated, and the q-axis represents an axis that is electrically orthogonal to the d-axis. For the generation of the command d-axis current i d * and the command q-axis current i q * , data of a plurality of current command maps for the torque command T rq * and the rotational speed command N may be measured in advance by actual measurement or simulation, stored, and used. The generated command d-axis current i d * and the command q-axis current i q * are output to the voltage command generation unit 44, the inductance calculation unit 411, and the magnet flux calculation unit 412.

[0031] The inductance calculation unit 411 calculates the d-axis inductance L d * and the q-axis inductance L q * in the rotating coordinate system based on the input command d-axis current i d and the command q-axis current i q (step S110). The calculated d-axis inductance L d and the q-axis inductance L q are output to the voltage command generation unit 44, the voltage calculation unit 47, and the magnet flux calculation unit 412.

[0032] The voltage command generation unit 44 takes the command d-axis current i d * and the command q-axis current i q * and the d-axis inductance L d and the q-axis inductance L q as inputs, and a command d-axis voltage vd * and command q-axis voltage v q * Calculate (step S120). Command d-axis voltage v d * and command q-axis voltage v q * ω is the rotational angular velocity, R is the phase resistance of the rotating electric machine 5, and φ is the magnetic flux of a single permanent magnet 52m at a given temperature. mag * Using this, it can be calculated using equations (1) and (2). The rotational angular velocity ω can be derived from equation (3) using the rotational speed command N and the number of pole pairs p of the rotating electric machine.

[0033] v d * = -ωL q i q * + Ri d * (1) v q * = ω(L d i d * + φ mag * ) + Ri q * (2) ω = N(2πp / 60) (3)

[0034] Command d-axis voltage v d * and command q-axis voltage v q * The command d-axis current i d * and command q-axis current i q * Alternatively, the system may have map data for that and perform calculations by referring to it.

[0035] The three-phase to two-phase conversion unit 48 performs a three-phase to two-phase coordinate transformation based on the U-phase current iu, V-phase current iv, W-phase current iw input from the rotating electric current detection unit 23, and the electrical angle θe input from the rotation angle sensor 5s. This three-phase to two-phase coordinate transformation converts the U-phase current iu, V-phase current iv, and W-phase current iw into the actual d-axis current i dand the actual q-axis current i q is converted (step S130).

[0036] The magnet flux calculating unit 412 uses the actual d-axis current i d and the actual q-axis current i q , the commanded d-axis current i d * and the commanded q-axis current i q * , and the d-axis inductance L d and the q-axis inductance L q as inputs to calculate the magnet flux φ mag (step S140). Then, the calculated magnet flux φ mag is output to the magnet flux-magnet temperature conversion unit 413 and the voltage calculation unit 47.

[0037] The voltage calculation unit 47 receives as inputs the d-axis inductance L d and the q-axis inductance L q calculated by the inductance calculation unit 411, the actual d-axis current i d and the actual q-axis current i q calculated by the three-phase to two-phase conversion unit 48, and the magnet flux φ mag calculated by the magnet flux calculating unit 412. The actual d-axis voltage v d and the actual q-axis voltage v q are calculated from the received inputs (step S150). The actual d-axis voltage v d and the actual q-axis voltage v q can be calculated by equations (4) and (5) using the rotational angular velocity ω, the phase resistance R of the rotating electrical machine, and the magnet flux φ mag .

[0038] v d = -ωL q i q + Ri d (4) v q = ω(L d i d + φ mag ) + Ri q (5)

[0039] ​d * and the command q-axis voltage v q * , and the actual d-axis voltage v from the voltage calculation unit 47 d and the actual q-axis voltage v q are input. The voltage control unit 45 calculates the d-axis voltage deviation between the command d-axis voltage v d * and the actual d-axis voltage v d , and the q-axis voltage deviation between the command q-axis voltage v q * and the actual q-axis voltage v q (step S160). Proportional-integral control operations are performed on the respective voltage deviations, and the command three-phase voltages v u * , v v * , v w * in the stationary coordinate system are output to the PWM signal generation unit 46.

[0040] In FIG. 4, the voltage control unit 45 calculates the d-axis voltage deviation between the command d-axis voltage v d * and the actual d-axis voltage v d , and the q-axis voltage deviation between the command q-axis voltage v q * and the actual q-axis voltage v q . However, the command d-axis voltage v d * and the command q-axis voltage v q * from the voltage command generation unit 44 may be directly converted into the command three-phase voltages v u * , v v * , v w * in the stationary coordinate system and output to the PWM signal generation unit 46.

[0041] The magnet flux-magnet temperature conversion unit 413 calculates the magnet temperature T mag using the magnet flux φ calculated by the magnet flux calculation unit 412 (details will be described later) (step S170). mag

[0042] The demagnetization determination unit 42 is the actual d-axis current i dand actual q-axis current i q , and the magnet temperature T derived by the magnet flux magnet temperature conversion unit 413 mag The demagnetization rate is calculated using the input and compared with a threshold (first threshold) to determine whether or not demagnetization has occurred (details will be described later) (step S200). The signal indicating whether or not demagnetization has occurred, which shows the determination result, is the magnet temperature T mag Along with this, the current command generation unit 43 and the carrier frequency selection unit 49 are output.

[0043] If the current command generation unit 43 receives a signal indicating no demagnetization has occurred based on the demagnetization determination, it performs normal control. If it receives a signal indicating that demagnetization has occurred, it commands the d-axis current i d * and command q-axis current i q * The driving conditions of the rotating electric machine 5 are adjusted so that the value is controlled to be 0 (step S300).

[0044] Furthermore, the carrier frequency selection unit 49, under normal control conditions, uses the torque command T rq * The carrier frequency fc is selected based on the rotational speed command N. The carrier frequency fc is stored as a map of torque and rotational speed, and the torque command T rq * The carrier frequency can be selected based on the rotational speed command N. In the demagnetization determination unit 42, even if it is determined that no demagnetization has occurred, if the demagnetization rate exceeds the second threshold (see Figure 16) described later, the carrier frequency fc is selected to be greater than the carrier frequency referenced in the map.

[0045] The demagnetization rate is defined as the rate of decrease of the fundamental wave component of the induced voltage. When the demagnetization rate exceeds the second threshold, the carrier frequency fc is selected to be raised to the threshold of the carrier frequency of the power converter 2. For example, the threshold of the carrier frequency of the power converter 2 can be set to about 10 kHz from the thermal limit of the switching element. By increasing the carrier frequency fc, the current harmonics caused by the carriers are reduced, which reduces the eddy currents generated in the permanent magnet 52m and suppresses the rise in magnet temperature. Therefore, by increasing the carrier frequency fc, it is possible to drive the rotating electric machine 5 continuously.

[0046] The PWM signal generation unit 46 receives a command for the three-phase voltage v from the voltage control unit 45. u * , v v * , v w * The carrier frequency fc from the carrier frequency selection unit 49 and the DC bus voltage V pn Based on this, the on / off control signals for each switching element of the power conversion circuit 22 are calculated. In calculating the on / off control signals, the command three-phase voltage v u * , v v * , v w * The triangular wave carrier is compared using a comparator to calculate the on / off state of the switching element. After the calculation, an on / off control signal U is sent to the power conversion circuit 22. H , U L , V H , V L , W H , W L Outputs.

[0047] The switching elements 221 to 226 of the power conversion circuit 22 are controlled by an on / off control signal U from the control unit 4. H , U L , V H , V L , W H , W LThe device switches on and off, converts DC power to AC power, and supplies it to the rotating electric machine 5. When the rotating electric machine 5 is in a regenerative state, the generated regenerative power is supplied to the DC power supply 70 for charging the DC power supply 70.

[0048] As described above, the rotating electric machine drive device 1 or rotating electric machine drive method of this disclosure, as shown in Figures 1 and 3 to 5, does not require the installation of a voltage sensor for measuring the line voltage or any current change, making it possible to easily estimate the magnet temperature. Since a voltage sensor is not required, costs can be reduced. Furthermore, since no current change is required, eddy currents associated with current changes are not generated, making it possible to achieve highly efficient driving of the rotating electric machine 5.

[0049] The simplified magnet temperature estimation requires less computation, resulting in reduced memory capacity. Furthermore, by determining whether demagnetization has occurred in the demagnetization determination unit 42 and inputting the determination result (a signal indicating it) to the current command generation unit 43, it is possible to protect the permanent magnet 52m from demagnetization. Demagnetization protection based on magnet temperature and current also has the effect of increasing the output of the rotating electric machine 5 by increasing the current up to the demagnetization limit.

[0050] Furthermore, the part that performs calculations, such as the control unit 4, can be configured by a single hardware unit 400, which includes a processor 401 and a storage device 402, as shown in Figure 6. Although not shown, the storage device 402 includes a volatile storage device such as random access memory and a non-volatile auxiliary storage device such as flash memory. Alternatively, a hard disk may be provided as an auxiliary storage device instead of flash memory. The processor 401 executes the program input from the storage device 402. In this case, the program is input from the auxiliary storage device to the processor 401 via the volatile storage device. The processor 401 may also output data such as calculation results to the volatile storage device of the storage device 402, or it may save the data to the auxiliary storage device via the volatile storage device.

[0051] Next, we will explain specific examples of how to reduce computational processing or memory usage. As shown in Figure 7A, the temperature T of a certain (constant) permanent magnet 52m mag * In this case, the actual d-axis current i d and actual q-axis current i q In contrast, the d-axis inductance L d Mapping (actual d-axis current i d and actual q-axis current i q d-axis inductance L d An inductance map can be created. Similarly, as shown in Figure 7B, a certain temperature T mag * In this case, the actual d-axis current i d and actual q-axis current i q For comparison, the q-axis inductance L q It is possible to map them.

[0052] Therefore, for example, the inductance map is stored in the memory device 402. Then, in step S110, by referring to the inductance map, the inductance calculation unit 411 calculates the input command d-axis current i d * and command q-axis current i q * Therefore, d-axis inductance L d and q-axis inductance L q This can be derived.

[0053] Furthermore, since the inductance map holds discrete inductance data for each current, the inductance between discrete currents is calculated by interpolation. The inductance map can be generated by performing an electromagnetic field analysis in advance, varying the d-axis current and q-axis current. Since inductance changes significantly depending on the degree of magnetic saturation of iron, it is possible to calculate accurate inductance by calculating it from the inductance maps shown in Figures 7A and 7B. Therefore, it becomes possible to estimate the magnet temperature with high accuracy.

[0054] Alternatively, in the inductance calculation unit 411, the d-axis inductance L d and q-axis inductance L q This can be determined by estimation. The inductance depends on whether or not magnetic saturation occurs in the iron; if magnetic saturation occurs, the iron can be considered to have the same permeability as air. On the other hand, if magnetic saturation does not occur, the d-axis magnetic path and the q-axis magnetic path can be considered to be dominated by the air gap between the stator 51 and the rotor 52.

[0055] If magnetic saturation occurs, iron is considered to have the same permeability as air, and the d-axis inductance L is calculated accordingly. d and q-axis inductance L q The d-axis inductance L is derived, and if magnet saturation does not occur, the d-axis inductance L is calculated by considering only the permeability of the air gap between the stator 51 and rotor 52. d and q-axis inductance L q We just need to derive this. In reality, magnetic saturation occurs locally and gradually spreads, so from the start of magnetic saturation until complete magnetic saturation, we can create an approximate formula by considering the d-axis inductance and q-axis inductance as depending on the d-axis current and q-axis current.

[0056] Furthermore, as shown in Figure 8, the temperature T of a certain permanent magnet mag * Actual d-axis current i d and actual q-axis current i q For the d-axis magnetic flux φ d Mapping (actual d-axis current i d and actual q-axis current i q φ of the d-axis magnetic flux relative to d It is also possible to create a magnetic flux map. For example, the magnetic flux map is saved in the storage device 402. Then, in step S140, by referring to the saved magnetic flux map, the magnet magnetic flux calculation unit 412 commands the d-axis current i d * and command q-axis current i q * The d-axis magnetic flux φ calculated based on this d * and d-axis inductance, and actual d-axis current id The magnetic flux of a magnet can be derived based on this.

[0057] The d-axis magnetic flux map can be generated by performing an analysis in advance in which the d-axis current and q-axis current are varied in an electromagnetic field analysis. In this disclosure, the temperature T of a certain permanent magnet 52m is used. mag * Inductance and magnetic flux φ in mag * It is necessary to maintain the d-axis magnetic flux φ. d,ex is the q-axis voltage v q,ex Phase resistance R of a rotating electric machine ex , q-axis current i q,ex , rotational angular velocity ω ex Using this, we can approximate it as shown in equation (6).

[0058]

number

[0059] In the rotating electric machine 5, the phase resistance R ex Voltage drop R ex i q,ex The term is the q-axis voltage v q,ex Since it is much smaller than, it can be approximated as shown in equation (6). Equation (6) shows that even if the command current and the actual current are different, the command q-axis voltage v q * This demonstrates that it is possible to obtain the d-axis magnetic flux as commanded. That is, the temperature T of a certain permanent magnet mag * When the command current created in is input, the actual magnet temperature T mag Although the actual current obtained from the rotating electric machine current detection unit 23 differs from the commanded current, the expected d-axis magnetic flux is obtained because the commanded q-axis voltage is input. Actual magnet temperature T mag Magnetic flux φ in a magnet mag is the d-axis magnetic flux φ d * d-axis inductance L d Actual d-axis current i d It can be calculated from equation (7) using this method. φ mag = φ d * - L d i d (7)

[0060] Equation (7) shows that the d-axis magnetic flux is obtained as expected by the commanded q-axis voltage, and therefore the L component of the magnetic flux due to the actual d-axis current is calculated from the d-axis magnetic flux. d i d By subtracting the actual magnet temperature T, mag Magnetic flux φ in a magnet mag This shows that the magnetic flux φ can be obtained using the current. Equation (7) uses the current to obtain the magnetic flux φ mag It is calculated, but converted to voltage and magnetic flux φ mag You may calculate this.

[0061] Furthermore, the magnet flux calculation unit 412 calculates a certain temperature T mag * Magnetic flux φ in a magnet mag * And, command d-axis current i d * and command q-axis current i q * The inductance calculated based on and the actual d-axis current i d Based on the magnetic flux φ mag It is also possible to calculate the actual magnet temperature T. mag Magnetic flux φ in a magnet mag This is the d-axis inductance L d , command d-axis current i d * , a certain temperature T mag * Magnetic flux φ in a magnet mag * Actual d-axis current i d It can be calculated from equation (8) using this. φ mag = L d i d * + φ mag * -L d i d (8)

[0062] By using equation (8), even without maintaining a map of the d-axis magnetic flux, the actual magnet temperature T can be calculated. mag Magnetic flux φ in a magnet mag The following can be calculated. Note that in equation (8), the magnetic flux φ of the magnet is calculated using the electric current. mag It is calculated, but converted to voltage and magnetic flux φ mag You may calculate this.

[0063] Furthermore, as shown in Figure 9, the magnetic flux φ mag and magnet temperature T mag It is also possible to create a relationship map showing the relationship between the two. For example, if the relationship map is saved in the storage device 402, in step S170, the magnet flux magnet temperature conversion unit 413 can refer to the relationship map to calculate the magnet flux φ mag From the magnetic temperature T mag This can be estimated. The relationship map can be created in advance by performing an analysis with varying magnet temperatures in electromagnetic field analysis and calculating the magnetic flux at each magnet temperature.

[0064] In the case of a surface-magnet type synchronous rotating electric machine, as explained in Figure 2, in which permanent magnets 52m are attached to the outer circumferential surface 52fo of the rotor 52, there is no effect of leakage flux at the ends of the magnets, so the magnetic flux φ mag It changes in proportion to the magnet temperature Tmag. Therefore, the magnet temperature T mag Magnetic flux φ in a magnet mag This is a certain temperature T mag * Magnetic flux φ in a magnet mag * And using the proportionality constant α, it can be calculated using equation (9). φ mag = φ mag * {1 + α(T mag - T mag * )} (9)

[0065] The proportionality constant α is, for example, -0.0012 for neodymium sintered magnets and -0.0018 for ferrite magnets. Equation (9) is given by the magnet temperature T. magBy rearranging the terms, we obtain equation (10).

[0066]

number

[0067] Therefore, in the magnet flux magnet temperature conversion unit 413, the magnet temperature T in the case of a surface magnet type synchronous rotating electric machine mag This can be calculated using a formula. By performing calculations using a formula, the magnet temperature T can be calculated more simply than when using a map. mag This allows us to calculate the reduction in memory capacity.

[0068] On the other hand, in the embedded magnet type synchronous rotating electric machine shown in Figure 10, the permanent magnet 52m is embedded inside the rotor 52 (inside the outer circumferential surface 52fo and closer to the outer circumferential surface 52fo than to the axis center). As shown in Figure 11, an enlarged view of the vicinity of the outer circumferential surface 52fo in which the permanent magnet 52m is embedded, leakage flux is generated at the magnet ends (circumferential ends) in the case of the embedded magnet type synchronous rotating electric machine.

[0069] Let W be the magnet width (in the circumferential direction), and a be the bridge width (in the radial direction) between the rotor surface (outer surface 52fo) and the air gap 52s into which the permanent magnet 52m is inserted. In the case of embedded magnet type synchronous rotating electric machines, leakage flux is generated at the magnet ends, so the magnetic flux corresponding to the magnet width W cannot be used as the magnet flux. Therefore, a conversion formula between magnet flux and magnet temperature that takes leakage flux into account is required.

[0070] As shown in Figure 12, a schematic diagram illustrating the properties of a permanent magnet, a permanent magnet operates at a magnetic flux density Be lower than the residual magnetic flux density Br. The magnetic flux density Be can be calculated from the intersection with the permeance line, and the slope of the permeance line can be calculated from the magnet shape and magnetic path. The magnetic flux density Be is calculated at a certain (constant) temperature T mag *This is the value at [a specific point in time]. If the saturation magnetic flux density of the iron used in the rotor 52 is Bs, the magnetic flux at the ends of the magnets is used to magnetically saturate the bridge section, so it is necessary to calculate the magnetic flux of the magnets by subtracting the amount of the magnet width used to magnetically saturate. The residual magnetic flux density Br of a permanent magnet is, for example, 1.2 to 1.4 T for a neodymium sintered magnet and 0.3 to 0.4 T for a ferrite magnet. The saturation magnetic flux density Bs of iron is, for example, 2 T for an electrical steel sheet.

[0071] In the case of a recessed magnet type synchronous rotating electric machine, the magnet temperature T mag Magnetic flux φ in a magnet mag This can be calculated using equation (11). Equation (11) is used with magnetic temperature T mag By rearranging the equation, we obtain equation (12), and by using the coefficients β and γ, we can obtain equation (13).

[0072]

number

[0073] Therefore, in the magnet flux magnet temperature conversion unit 413, even in the case of an embedded magnet type synchronous rotating electric machine, the magnet temperature T can be calculated using the formula. mag It is possible to calculate the magnet temperature T using the formula. mag This allows us to calculate the reduction in memory capacity.

[0074] As shown in Figure 13, demagnetization maps (demagnetization rate maps) for d-axis current and q-axis current can be generated for each magnet temperature. The demagnetization rate is defined as the rate of decrease of the fundamental wave component of the induced voltage. Alternatively, the demagnetization rate may be defined as the rate of decrease of the RMS value of the induced voltage. In this case, the demagnetization rate is the rate of decrease when comparing the induced voltage in the no-load state before current application with the induced voltage in the no-load state after current is applied at high temperature.

[0075] For example, the demagnetization rate can be calculated by measuring the induced voltage under no load at 20°C, applying a specified current at 180°C, and then measuring the induced voltage under no load again when the temperature returns to 20°C. In this case, the temperature when the specified current is applied is shown in Figure 13 as T. mag This means that the demagnetization rate map for each magnet temperature, as shown in Figure 13, can be created by performing electromagnetic field analysis and stored, for example, in the memory device 402.

[0076] Therefore, in step S200, the demagnetization determination unit 42 determines the magnet temperature T calculated by the magnet temperature calculation unit. mag and the actual d-axis current i calculated by the three-phase to two-phase conversion unit 48 d and actual q-axis current i q The demagnetization rate is estimated by taking the input and referring to the stored demagnetization rate map. Then, it is determined whether or not demagnetization has occurred based on whether or not the estimated demagnetization rate exceeds a predetermined threshold (first threshold).

[0077] As shown in the schematic diagram in Figure 14, it is also possible to store in advance the relationship between magnet temperature and the demagnetization current threshold. Here, the demagnetization current threshold is defined as the minimum effective value of the current that reaches the first threshold for each magnet temperature. Demagnetization occurs depending on both the d-axis current and the q-axis current, but the d-axis current is dominant in causing demagnetization. Therefore, the demagnetization current threshold can be calculated as the effective value obtained when the d-axis current that reaches a predetermined first threshold when only the d-axis current is applied at each magnet temperature is converted to a phase current. The relationship between magnet temperature and the demagnetization current threshold, as shown in Figure 14, can be determined in advance by performing electromagnetic field analysis and stored as temperature threshold relationship data.

[0078] Then, the demagnetization determination unit 42 refers to temperature threshold relationship data where the demagnetization rate for each magnet temperature is the first threshold, and the effective value of the phase current is the magnet temperature T calculated by the magnet temperature calculation unit 41. magThe presence or absence of demagnetization is determined by whether or not the corresponding demagnetization current threshold is exceeded. By using temperature threshold relationship data, demagnetization can be easily determined by comparing it with a demagnetization rate map for the d-axis current and q-axis current at each magnet temperature, resulting in a reduction in memory capacity.

[0079] The details of the demagnetization determination and drive control adjustment (steps S200 to S300) will be explained. If the demagnetization determination unit 42 determines in step S200 that demagnetization is present, then in step S300, as shown in Figure 15, the current command generation unit 43 generates a command d-axis current i d * and command q-axis current i q * The command d-axis current i is ramped down to 0. If demagnetization is detected, it will be considered an abnormal condition and the system will be controlled to stop operation. However, if the command d-axis current i is suddenly reduced d * and command q-axis current i q * Lowering the ramps would cause sudden braking; however, by lowering the ramps as shown in Figure 15, the train can be stopped smoothly.

[0080] Here, we will explain the case where, in addition to the first threshold, a second threshold lower than the first threshold is set for the demagnetization rate, as shown in Figure 16, referring to the flowchart in Figure 17. In this case as well, if the demagnetization rate exceeds the first threshold ("Yes" in step S210), as described above, it is determined that demagnetization has occurred, and the command d-axis current i d * and command q-axis current i q * Reduce the ramp down to 0 (step S310).

[0081] On the other hand, if the first threshold is not exceeded but the second threshold is exceeded (No in step S210 → Yes in step S220), demagnetization is not determined, but the demagnetization rate is greater than a certain value greater than 0, and it is determined that demagnetization has begun to occur. If the second threshold is exceeded even if it is below the first threshold, the demagnetization is negligible and does not pose a problem for the operation of the rotating electric machine 5. However, if the magnet temperature rises further, it may exceed the first threshold, so in this disclosure, if the demagnetization rate exceeds the second threshold, the carrier frequency selection unit 49 increases the carrier frequency fc (step S320).

[0082] The carrier frequency fc is selected to raise it to the threshold carrier frequency of power converter 2. For example, the threshold carrier frequency of power converter 2 can be set to about 10 kHz from the thermal limit of the switching element. By increasing the carrier frequency fc, the current harmonics caused by the carriers are reduced, so the eddy currents generated in the permanent magnet 52m can be reduced, and the magnet temperature T mag This can suppress the rise.

[0083] Therefore, increasing the carrier frequency fc can enable the continuous driving of the rotating electric machine 5. The first threshold for demagnetization is set to, for example, 3%, and the second threshold to, for example, 0.3%. The rotating electric machine 5 has a torque variation of about 3% due to variations in materials and tolerances, so the torque has a margin of about 3%. Therefore, the first threshold can be set to indicate that demagnetization is occurring when the demagnetization rate exceeds 3%. The second threshold needs to be selected to indicate when demagnetization begins, and should be set to about one-tenth of the first threshold.

[0084] Then, if the demagnetization rate is less than the second threshold (No in step S220), normal control is performed (continues) (step S330). This type of control makes it possible to use up the current up to the demagnetization limit at each magnet temperature, resulting in an improvement in the output of the rotating electric machine 5.

[0085] Here, if silicon carbide (SiC) semiconductor switching elements are applied to the switching elements 221-226 that constitute the power conversion circuit 22, it becomes possible to set the carrier frequency threshold higher than when silicon-based elements are used. In other words, when the demagnetization rate reaches the second threshold, the carrier frequency fc can be made larger, and the magnet temperature T mag This makes it possible to suppress the rise.

[0086] The magnet temperature T calculated by the rotating electric drive device 1 or rotating electric drive method of this disclosure mag This represents the magnet temperature of the permanent magnet 52m from a macroscopic perspective, but by combining it with a thermal circuit network, it is possible to calculate the localized magnet temperature. By combining it with a thermal circuit network, it becomes possible to calculate the magnet temperature with higher accuracy, making it possible to use the current to its limit against demagnetization, and thus improving the output of the rotating electric machine 5.

[0087] While this disclosure describes exemplary embodiments, the various features, aspects, and functions described in the embodiments are not limited to the application of any particular embodiment, but can be applied individually or in various combinations to the embodiments. Therefore, countless variations not illustrated are conceivable within the scope of the technology disclosed in this specification. These include, for example, modifications, additions, or omissions of at least one component.

[0088] As described above, the rotating electric machine drive device 1 of this disclosure drives a rotating electric machine 5, which is composed of a stator 51 provided with three-phase stator windings (windings 51c) and a rotor 52 whose magnetic poles are formed by permanent magnets 52m. This is achieved by a power converter 2 that converts power input from a power source (DC power supply 70, single-phase AC power supply 90) and outputs phase power to the three-phase stator windings (windings 51c), and converts the current flowing through the three-phase stator windings (windings 51c) into the dq axis of the rotating coordinate system to obtain the actual d-axis current i d and actual q-axis current i q A three-phase to two-phase conversion unit 48 calculates the torque command T rq *And a command to set the phase power from the rotation speed command N, i of the d axis current d * and command q-axis current i q * A current command generation unit 43 generates the current command i, and the actual d-axis current i d and actual q-axis current i q and command d-axis current i d * and command q-axis current i q * A magnet temperature calculation unit 41 calculates the temperature of the permanent magnet 52m from the actual d-axis current i d and actual q-axis current i q A demagnetization determination unit 42 is provided to determine whether or not the permanent magnet 52m has been demagnetized based on the temperature of the permanent magnet 52m calculated, and a control unit 4 is provided to adjust the control of the power converter 2 according to the determination result of the demagnetization determination unit 42. This configuration eliminates the need to install a voltage sensor for measuring the line voltage and to change the current solely for measurement, and allows for the determination of the magnet temperature T mag This allows for the estimation of the rotational electric machine 5, enabling efficient drive and control.

[0089] In particular, the magnet temperature calculation unit 41 receives the command d-axis current i d * and command q-axis current i q * Based on the d-axis inductance L d and q-axis inductance L q The inductance calculation unit 411 calculates the actual d-axis current i d and actual q-axis current i q and command d-axis current i d * and command q-axis current i q * and d-axis inductance L d and q-axis inductance L q From a permanent magnet at 52m, the magnetic flux φ mag A magnetic flux calculation unit 412 calculates the magnetic flux φ mag From the temperature of the permanent magnet at 52m (magnet temperature T) mag If a magnet flux magnet temperature conversion unit 413 that calculates the magnet temperature T is provided, then the magnet temperature T can be calculated without excessively increasing the calculation processing or memory capacity. magIt is possible to estimate this.

[0090] At this time, the inductance calculation unit 411 calculates the d-axis inductance L for the d-axis current and q-axis current when the temperature of the permanent magnet 52m is constant. d and q-axis inductance L q Refer to the inductance map showing the relationship, d-axis inductance L d and q-axis inductance L q By calculating it in this way, the calculation process is simplified.

[0091] Here, the magnetic flux calculation unit 412 calculates the magnetic flux φ in the d-axis direction for the d-axis current and q-axis current when the temperature of the permanent magnet 52m is constant. d Refer to the magnetic flux map showing the relationship, and the magnetic flux φ of the magnet in the d-axis direction. d The calculation process can be further simplified by calculating it in this way.

[0092] At that time, the magnet flux calculation unit 412 calculates the magnet flux as φ mag , the magnetic flux of the magnet in the d-axis direction is φ d * , d-axis inductance L d , the actual d-axis current i d Therefore, using equation (7), the magnetic flux φ mag By calculating this in a specific way, memory capacity can be saved.

[0093] Alternatively, the magnetic flux calculation unit 412 calculates the magnetic flux φ of the permanent magnet 52m when the temperature of the permanent magnet 52m is at a certain temperature. mag * and command d-axis current i d * And, d-axis inductance L d And the actual d-axis current i d From, the magnetic flux φ mag Even if we calculate it in this way, the calculation process will be simplified.

[0094] At that time, the magnet flux calculation unit 412 calculates the magnet flux as φ mag , d-axis inductance L d , the actual d-axis current i dThe magnetic flux of a permanent magnet at a temperature of 52m is φ mag * Therefore, using equation (8), the magnetic flux φ mag By calculating this in a specific way, memory capacity can be saved.

[0095] The magnet temperature calculation unit 41 contains the magnetic flux φ mag and magnet temperature T mag The calculation process can be simplified by providing a magnet flux-to-magnet temperature conversion unit 413 that calculates the temperature of the permanent magnet 52m by referring to a map showing the relationship between the two.

[0096] Here, if the rotating electric machine 5 is a surface magnet type synchronous rotating electric machine, the temperature of the permanent magnet 52m is T mag The permanent magnet has a temperature of 52m, which is temperature T mag * In this case, the magnetic flux of the magnet is φ mag * If the proportionality constant is α, the magnetic flux-to-temperature conversion unit 413 can save memory capacity by calculating the temperature of the permanent magnet 52m using equation (10).

[0097] Alternatively, if the rotating electric machine 5 is an embedded magnet type synchronous rotating electric machine, the temperature of the permanent magnet 52m is T mag The permanent magnet has a temperature of 52m, which is temperature T mag * In this case, the magnetic flux of the magnet is φ mag * Let α, β, and γ be the proportionality constants, W be the magnet width of the permanent magnet 52m, a be the bridge width between the outer surface 52fo of the rotor 52 and the air gap 52s in which the permanent magnet 52m is inserted, and T be the temperature of the permanent magnet 52m. mag The permanent magnet has a temperature of 52m, which is temperature T mag * If we let Be be the magnetic flux density of the magnet in this case, and Bs be the saturation magnetic flux density of the iron constituting the core of the rotor 52, then the magnetic flux-to-temperature conversion unit 413 can save memory capacity even if it calculates the temperature of the permanent magnet 52m using equation (13).

[0098] Furthermore, the demagnetization determination unit 42 determines the demagnetization rate, which is defined as the rate of decrease of the fundamental wave component of the induced voltage for the d-axis current and the q-axis current, and the magnet temperature T. mag By referring to a demagnetization rate map that shows the relationship between the two values, the demagnetization rate of the 52m permanent magnet can be calculated, and the presence or absence of demagnetization can be easily determined by whether or not the calculated demagnetization rate exceeds a threshold (first threshold).

[0099] Alternatively, the demagnetization determination unit 42 defines the demagnetization rate as the rate of decrease of the fundamental wave component of the induced voltage, and the magnet temperature T mag Refer to the map showing the relationship between the demagnetization current threshold at which the demagnetization rate for each axis reaches a predetermined value, and the actual d-axis current i d and actual q-axis current i q However, demagnetization can be easily determined by determining whether or not the demagnetization has occurred based on whether or not the calculated demagnetization current threshold corresponding to the temperature of the 52m permanent magnet has been exceeded.

[0100] Furthermore, when the current command generation unit 43 receives a signal from the demagnetization determination unit 42 indicating that demagnetization has occurred, it generates a command d-axis current i d * and command q-axis current i q * By setting the indicator to zero, the vehicle can be brought to a smooth stop without sudden braking.

[0101] The control unit 4 receives the torque command T rq * A carrier frequency selection unit 49 is provided to select a carrier frequency fc to drive the power converter 2 from the rotation speed command N. The carrier frequency selection unit 49 is configured to increase the carrier frequency fc when it receives a signal from the demagnetization determination unit 42 indicating that the demagnetization rate of the permanent magnet 52m is lower than a threshold (first threshold) for determining demagnetization, and also exceeds a second threshold (first threshold) which is lower than the first threshold. This configuration suppresses the rise in magnet temperature and enables continuous operation.

[0102] Furthermore, the rotating electric machine system of this disclosure, by including the rotating electric machine 5 and the aforementioned rotating electric machine drive device 1 that drives the rotating electric machine 5, enables highly efficient operation.

[0103] Furthermore, according to the rotating electric machine driving method of this disclosure, a rotating electric machine 5 is composed of a stator 51 provided with three-phase stator windings (windings 51c) and a rotor 52 whose magnetic poles are formed by permanent magnets 52m. The method involves converting power input from a power source (DC power source 70, single-phase AC power source 90) into phase power to the three-phase stator windings (windings 51c), and driving and controlling the rotating electric machine 5, wherein the torque command T rq * And a command to set the phase power from the rotation speed command N, i of the d axis current d * and command q-axis current i q * The current command generation step (step S100) generates the current flowing through the three-phase stator winding (winding 51c) and converts it into the dq axis of the rotating coordinate system to generate the actual d-axis current i d and actual q-axis current i q A three-phase to two-phase conversion step (step S130) calculates the actual d-axis current i d and actual q-axis current i q and command d-axis current i d * and command q-axis current i q * The magnet temperature calculation step (step S170) calculates the temperature of the permanent magnet 52m from the actual d-axis current i d and actual q-axis current i q The system is configured to include a demagnetization determination step (steps S200-S220) that determines whether or not the permanent magnet 52m has been demagnetized based on the calculated temperature of the permanent magnet 52m, and a step (steps S300-330) that adjusts the conversion to phase power according to the determination result in the demagnetization determination step. Therefore, it does not require the installation of a voltage sensor for measuring the line voltage or a current change solely for measurement, and the magnet temperature T mag This allows for the estimation of the rotational electric machine 5, enabling efficient drive and control.

[0104] In particular, the command d-axis current i d * and command q-axis current i q * Based on the d-axis inductance L d and q-axis inductance L qThe inductance calculation step (step S110) calculates the actual d-axis current i d and actual q-axis current i q and command d-axis current i d * and command q-axis current i q * and d-axis inductance L d and q-axis inductance L q From a permanent magnet at 52m, the magnetic flux φ mag The process includes a magnet flux calculation step (step S140) which calculates the magnet flux φ, and a magnet temperature calculation step (S170) which calculates the magnet flux φ mag From the temperature of the permanent magnet at 52m (magnet temperature T) mag By calculating the magnet temperature T without excessively increasing the processing power or memory capacity, mag It is possible to estimate this.

[0105] The various aspects of this disclosure are summarized below as an appendix.

[0106] (Note 1) A power converter is provided to drive a rotating electric machine consisting of a stator equipped with three-phase stator windings and a rotor whose magnetic poles are formed by permanent magnets, by converting the power input from a power source and outputting phase power to the three-phase stator windings, and The power converter is provided with a three-phase to two-phase conversion unit that converts the current flowing through the three-phase stator winding into the dq axis of a rotating coordinate system and calculates the actual d-axis current and the actual q-axis current; a current command generation unit that generates a command d-axis current and a command q-axis current for setting the phase power from a torque command and a rotational speed command; a magnet temperature calculation unit that calculates the temperature of the permanent magnet from the actual d-axis current, the actual q-axis current, the command d-axis current and the command q-axis current; and a demagnetization determination unit that determines whether or not the permanent magnet has been demagnetized from the actual d-axis current, the actual q-axis current and the calculated temperature of the permanent magnet, and a control unit that adjusts the control of the power converter according to the determination result of the demagnetization determination unit. A rotating electric drive device characterized by being equipped with the following features.

[0107] (Note 2) The rotating electric machine drive device according to Appendix 1, characterized in that the magnet temperature calculation unit is provided with an inductance calculation unit that calculates the d-axis inductance and q-axis inductance based on the commanded d-axis current and the commanded q-axis current; a magnet flux calculation unit that calculates the magnetic flux of the permanent magnet from the actual d-axis current, the actual q-axis current, the commanded d-axis current, the commanded q-axis current, the d-axis inductance and the q-axis inductance; and a magnet flux-to-temperature conversion unit that calculates the temperature of the permanent magnet from the magnetic flux.

[0108] (Note 3) The rotating electric machine drive device according to Appendix 2, characterized in that the inductance calculation unit calculates the d-axis inductance and the q-axis inductance by referring to an inductance map showing the relationship between the d-axis inductance and the q-axis inductance with respect to the d-axis current and q-axis current when the temperature of the permanent magnet is constant.

[0109] (Note 4) The rotating electric machine drive device according to Appendix 3, characterized in that the magnetic flux calculation unit calculates the magnetic flux in the d-axis direction by referring to a magnetic flux map showing the relationship between the magnetic flux in the d-axis direction and the d-axis current when the temperature of the permanent magnet is constant.

[0110] (Note 5) The magnetic flux calculation unit calculates the magnetic flux of the magnet as φ mag , the magnetic flux of the magnet in the d-axis direction is φ d * , the d-axis inductance is L d , the actual d-axis current i d Accordingly, the rotating electric machine drive device according to Appendix 4 is characterized by calculating the magnetic flux of the magnet using equation (7).

[0111] (Note 6) The rotating electric machine drive device according to Appendix 3, characterized in that the magnetic flux calculation unit calculates the magnetic flux from the magnetic flux of the permanent magnet when the permanent magnet is at a certain temperature, the commanded d-axis current, the d-axis inductance, and the actual d-axis current.

[0112] (Appendix 7) The magnet magnetic flux calculation unit calculates the magnet magnetic flux as φ mag , the d-axis inductance as L d , the actual d-axis current as i d , and when the temperature of the permanent magnet is at a certain temperature, the magnet magnetic flux as φ mag * Then, the rotating electrical machine drive device according to Appendix 6 is characterized by calculating the magnet magnetic flux using Equation (8).

[0113] (Appendix 8) The magnet temperature calculation unit is provided with a magnet magnetic flux-magnet temperature conversion unit that refers to a map showing the relationship between the magnet magnetic flux and the magnet temperature and calculates the temperature of the permanent magnet, and is characterized by the rotating electrical machine drive device according to any one of Appendices 2 to 7.

[0114] (Appendix 9) When the rotating electrical machine is a surface magnet type synchronous rotating electrical machine,[[]] the temperature of the permanent magnet is T mag , and when the temperature of the permanent magnet is at a certain temperature T mag * and the magnet magnetic flux at this time is φ mag * , and when the proportionality coefficient is α,[[]] the magnet magnetic flux-magnet temperature conversion unit calculates the temperature of the permanent magnet using Equation (10), and is characterized by the rotating electrical machine drive device according to any one of Appendices 2 to 8.

[0115] (Appendix 10) When the rotating electrical machine is an embedded magnet type synchronous rotating electrical machine,[[]] the temperature of the permanent magnet is T mag , and when the temperature of the permanent magnet is at a certain temperature T mag * and the magnet magnetic flux at this time is φ mag * , and when the proportionality coefficients are α, β, and γ,[[]] the magnet width of the permanent magnet is W, the bridge width between the outer peripheral surface of the rotor and the gap portion in which the permanent magnet is inserted is a, the temperature of the permanent magnet is T mag , and when the temperature of the permanent magnet is at a certain temperature T mag* When the magnetic flux density of the magnet is Be and the saturation magnetic flux density of the iron constituting the rotor core is Bs, The magnet magnetic flux magnet temperature conversion unit calculates the temperature of the permanent magnet using Equation (13), and is a rotating electrical machine drive device according to any one of Appendices 2 to 8.

[0116] (Appendix 11) The demagnetization determination unit calculates the demagnetization rate of the permanent magnet by referring to a demagnetization rate map showing the relationship between the demagnetization rate defined as the reduction rate of the fundamental wave component of the induced voltage with respect to the d-axis current and the q-axis current and the magnet temperature, and determines the presence or absence of demagnetization based on whether the calculated demagnetization rate exceeds a threshold value, and is a rotating electrical machine drive device according to any one of Appendices 1 to 10.

[0117] (Appendix 12) The demagnetization determination unit defines the demagnetization rate as the reduction rate of the fundamental wave component of the induced voltage, refers to a map showing the relationship between the demagnetization current threshold value at which the demagnetization rate for each magnet temperature becomes a predetermined value, and determines the presence or absence of demagnetization based on whether the actual d-axis current and the actual q-axis current exceed the demagnetization current threshold value corresponding to the calculated temperature of the permanent magnet, and is a rotating electrical machine drive device according to any one of Appendices 1 to 11.

[0118] (Appendix 13) When the current command generation unit receives a signal indicating a determination result of demagnetization from the demagnetization determination unit, it ramps down the command d-axis current and the command q-axis current to 0, and is a rotating electrical machine drive device according to any one of Appendices 1 to 12.

[0119] (Appendix 14) The control unit is provided with a carrier frequency selection unit that selects a carrier frequency for driving the power converter from the torque command and the rotation speed command, The rotating electric machine drive device according to any one of appendices 1 to 13, characterized in that when the carrier frequency selection unit receives a signal from the demagnetization determination unit indicating that the demagnetization rate of the permanent magnet is lower than a threshold for determining demagnetization and exceeds a second threshold that is lower than the threshold, it increases the carrier frequency.

[0120] (Note 15) The aforementioned rotating electric machine, and A rotating electric machine drive device according to any one of the appendices 1 to 14, which drives the aforementioned rotating electric machine. A rotating electric machine system characterized by having the following features.

[0121] (Note 16) A method for driving and controlling a rotating electric machine, which consists of a stator equipped with three-phase stator windings and a rotor with magnetic poles formed by permanent magnets, by converting power input from a power source into phase power for the three-phase stator windings, A three-phase to two-phase conversion step that converts the current flowing through the three-phase stator winding into the dq axis of a rotating coordinate system and calculates the actual d-axis current and the actual q-axis current. A current command generation step that generates command d-axis current and command q-axis current for setting the phase power from the torque command and rotational speed command, A magnet temperature calculation step in which the temperature of the permanent magnet is calculated from the actual d-axis current, the actual q-axis current, the commanded d-axis current, and the commanded q-axis current. A demagnetization determination step that determines whether or not the permanent magnet has been demagnetized based on the actual d-axis current, the actual q-axis current, and the calculated temperature of the permanent magnet, and A step to adjust the conversion to phase power according to the determination result in the demagnetization determination step, A method for driving a rotating electric machine, characterized by including the following:

[0122] (Note 17) An inductance calculation step that calculates the d-axis inductance and q-axis inductance based on the commanded d-axis current and the commanded q-axis current, The process includes a magnetic flux calculation step that calculates the magnetic flux of the permanent magnet from the actual d-axis current, the actual q-axis current, the commanded d-axis current, the commanded q-axis current, the d-axis inductance, and the q-axis inductance. The method for driving a rotating electric machine according to Appendix 16, characterized in that the temperature of the permanent magnet is calculated from the magnetic flux of the magnet in the magnet temperature calculation step. [Explanation of symbols]

[0123] 1: Rotating electric machine drive unit, 2: Power converter, 21: Capacitor, 22: Power conversion circuit, 221~226: Switching element, 23: Rotating electric machine current detection unit, 26: Rectifier diode, 27: Reactor, 4: Control unit, 41: Magnet temperature calculation unit, 411: Inductance calculation unit, 412: Magnet magnetic flux calculation unit, 413: Magnet magnetic flux magnet temperature conversion unit, 42: Demagnetization determination unit, 43: Current command generation unit, 44: Voltage command generation unit, 45: Voltage control unit, 46: PWM signal generation unit, 47: Voltage calculation unit, 48: Three-phase two-phase conversion unit, 49: Carrier frequency selection unit, 5: Rotating electric machine, 51: Stator, 51c: Winding, 52: Rotor, 52fo: Outer surface, 52m: Permanent magnet, 5s: Rotation angle sensor, 70: DC power supply, 90: Single-phase AC power supply.

Claims

1. A power converter is provided to drive a rotating electric machine consisting of a stator equipped with three-phase stator windings and a rotor whose magnetic poles are formed by permanent magnets, by converting the power input from a power source and outputting phase power to the three-phase stator windings, and The power converter is provided with a three-phase to two-phase conversion unit that converts the current flowing through the three-phase stator winding into the dq axes of a rotating coordinate system and calculates the actual d-axis current and the actual q-axis current; a current command generation unit that generates a command d-axis current and a command q-axis current for setting the phase power from a torque command and a rotational speed command; a magnet temperature calculation unit that calculates the temperature of the permanent magnet from the actual d-axis current, the actual q-axis current, the command d-axis current and the command q-axis current; and a demagnetization determination unit that determines whether or not the permanent magnet has been demagnetized from the actual d-axis current, the actual q-axis current and the calculated temperature of the permanent magnet, and a control unit that adjusts the control of the power converter according to the determination result of the demagnetization determination unit. A rotating electric drive device characterized by being equipped with the following features.

2. The rotating electric machine drive device according to claim 1, characterized in that the magnet temperature calculation unit is provided with an inductance calculation unit that calculates the d-axis inductance and q-axis inductance based on the commanded d-axis current and the commanded q-axis current, a magnet flux calculation unit that calculates the magnetic flux of the permanent magnet from the actual d-axis current, the actual q-axis current, the commanded d-axis current, the commanded q-axis current, the d-axis inductance and the q-axis inductance, and a magnet flux-to-temperature conversion unit that calculates the temperature of the permanent magnet from the magnetic flux.

3. The rotating electric machine drive device according to claim 2, characterized in that the inductance calculation unit calculates the d-axis inductance and the q-axis inductance by referring to an inductance map showing the relationship between the d-axis inductance and the q-axis inductance with respect to the d-axis current and q-axis current when the temperature of the permanent magnet is constant.

4. The rotating electric machine drive device according to claim 3, characterized in that the magnetic flux calculation unit calculates the magnetic flux in the d-axis direction by referring to a magnetic flux map showing the relationship between the magnetic flux in the d-axis direction and the d-axis current when the temperature of the permanent magnet is constant.

5. The magnetic flux calculation unit calculates the magnetic flux of the magnet as φ mag , the magnetic flux of the magnet in the d-axis direction is φ d * , the d-axis inductance is L d , the actual d-axis current is i d So, f mag = φ d * - L d i d The rotating electric machine drive device according to claim 4, characterized in that the magnetic flux of the magnet is calculated using the above formula.

6. The rotating electric machine drive device according to claim 3, characterized in that the magnetic flux calculation unit calculates the magnetic flux from the magnetic flux of the permanent magnet at a certain temperature, the commanded d-axis current, the d-axis inductance, and the actual d-axis current.

7. The magnetic flux calculation unit calculates the magnetic flux of the magnet as φ mag , the d-axis inductance is L d , the actual d-axis current is i d , the magnetic flux of the permanent magnet when the temperature of the permanent magnet is a certain temperature is φ mag * So, f mag =L d i d * + f mag * - L d i d The rotating electric machine drive device according to claim 6, characterized in that the magnetic flux of the magnet is calculated using the above formula.

8. The rotating electric machine drive device according to any one of claims 2 to 7, characterized in that the magnet temperature calculation unit is provided with a magnet flux-to-magnet temperature conversion unit that calculates the temperature of the permanent magnet by referring to a map showing the relationship between the magnet flux and the magnet temperature.

9. If the aforementioned rotating electric machine is a surface magnet type synchronous rotating electric machine, The temperature of the permanent magnet is T mag The temperature of the permanent magnet is a certain temperature T mag * In the case of the aforementioned magnetic flux of the magnet, φ mag * If the proportionality constant is α, [Math 1] The rotating electric machine drive device according to any one of claims 2 to 7, characterized in that the magnet flux magnet temperature conversion unit calculates the temperature of the permanent magnet using the above formula.

10. If the aforementioned rotating electric machine is an embedded magnet type synchronous rotating electric machine, The temperature of the permanent magnet is T mag The temperature of the permanent magnet is a certain temperature T mag * In the case of the aforementioned magnetic flux of the magnet, φ mag * Let the proportionality constants be α, β, and γ. Let W be the width of the permanent magnet, a be the bridge width between the outer surface of the rotor and the gap in which the permanent magnet is inserted, and T be the temperature of the permanent magnet. mag The temperature of the permanent magnet is a certain temperature T mag * If the magnetic flux density of the magnet in this case is Be, and the saturation magnetic flux density of the iron constituting the rotor core is Bs, [Math 2] The rotating electric machine drive device according to any one of claims 2 to 7, characterized in that the magnet flux magnet temperature conversion unit calculates the temperature of the permanent magnet using the above formula.

11. The demagnetization determination unit calculates the demagnetization rate of the permanent magnet by referring to a demagnetization rate map that shows the relationship between the demagnetization rate, defined as the rate of decrease of the fundamental wave component of the induced voltage for the d-axis current and the q-axis current, and the magnet temperature. The rotating electric machine drive device according to any one of claims 1 to 7, characterized in that the presence or absence of demagnetization is determined by whether or not the calculated demagnetization rate exceeds a threshold.

12. The demagnetization determination unit defines the demagnetization rate as the rate of decrease of the fundamental wave component of the induced voltage, refers to a map showing the relationship between the demagnetization rate for each magnet temperature and the demagnetization current threshold at which the demagnetization rate becomes a predetermined value, and determines whether or not demagnetization has occurred based on whether or not the actual d-axis current and the actual q-axis current exceed the calculated demagnetization current threshold corresponding to the temperature of the permanent magnet, as described in any one of claims 1 to 7.

13. The rotating electric machine drive device according to any one of claims 1 to 7, characterized in that when the current command generation unit receives a signal from the demagnetization determination unit indicating that demagnetization is present, it ramps down the command d-axis current and the command q-axis current to zero.

14. The control unit is provided with a carrier frequency selection unit that selects a carrier frequency for driving the power converter from the torque command and the rotational speed command. The rotating electric machine drive device according to any one of claims 1 to 7, characterized in that when the carrier frequency selection unit receives a signal from the demagnetization determination unit indicating that the demagnetization rate of the permanent magnet is lower than a threshold for determining demagnetization and exceeds a second threshold that is lower than the threshold, it increases the carrier frequency.

15. The aforementioned rotating electric machine, and A rotating electric machine drive device according to any one of claims 1 to 7, for driving the aforementioned rotating electric machine, A rotating electric machine system characterized by having the following features.

16. A method for driving and controlling a rotating electric machine, which consists of a stator equipped with three-phase stator windings and a rotor with magnetic poles formed by permanent magnets, by converting power input from a power source into phase power for the three-phase stator windings, A three-phase to two-phase conversion step that converts the current flowing through the three-phase stator winding into the dq axis of a rotating coordinate system and calculates the actual d-axis current and the actual q-axis current. A current command generation step that generates command d-axis current and command q-axis current for setting the phase power from the torque command and rotational speed command, A magnet temperature calculation step in which the temperature of the permanent magnet is calculated from the actual d-axis current, the actual q-axis current, the commanded d-axis current, and the commanded q-axis current. A demagnetization determination step that determines whether or not the permanent magnet has been demagnetized based on the actual d-axis current, the actual q-axis current, and the calculated temperature of the permanent magnet, and A step to adjust the conversion to phase power according to the determination result in the demagnetization determination step, A method for driving a rotating electric machine, characterized by including the following:

17. An inductance calculation step that calculates the d-axis inductance and q-axis inductance based on the commanded d-axis current and the commanded q-axis current, The process includes a magnetic flux calculation step that calculates the magnetic flux of the permanent magnet from the actual d-axis current, the actual q-axis current, the commanded d-axis current, the commanded q-axis current, the d-axis inductance, and the q-axis inductance. The method for driving a rotating electric machine according to claim 16, characterized in that the temperature of the permanent magnet is calculated from the magnetic flux of the magnet in the magnet temperature calculation step.

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