JP2013005503A - Rotary electric machine controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary electric machine controller which can quickly change a current phase on the basis of a magnet temperature to improve driving efficiency of the rotary electric machine when the magnet temperature is changed to increase/decrease magnet torque.SOLUTION: A controller 20 is a controller that controls a drive of a motor 11 on the basis of combined torque τ consisting of magnet torque τM and reluctance torque τR. The controller 20 comprises: a current command generating unit 21; a PI operation unit 22; a first coordinate conversion unit 23; a PWM signal generating unit 24; a second coordinate conversion unit 25; and a revolution number operation unit 26. The current command generating unit 21 includes magnet temperature acquisition means 27 and current phase setting means 28. The current phase setting means 28 sets a current phase β to 0 degree when a magnet temperature T is a predetermined threshold Th or more.

Description

  The present invention relates to a rotating electrical machine control device, and more particularly to a rotating electrical machine control device that generates a magnet torque and a reluctance torque.

  A magnet-embedded motor (hereinafter referred to as an IPM motor) in which a permanent magnet is embedded in a rotor core is based on a change in the magnetic resistance of the gap between the stator and rotor in addition to the magnet torque caused by the attractive force / repulsive force of the coil and permanent magnet. The generated reluctance torque can be obtained. For this reason, the IPM motor is suitable for an application where high output performance is required, for example, a traveling motor for an electric vehicle such as a hybrid vehicle.

  In the IPM motor, it is necessary to set the current phase so that the combined torque obtained by combining the magnet torque and the reluctance torque becomes maximum. However, since the magnet torque varies depending on, for example, the magnet temperature, the ratio with the reluctance torque varies. For this reason, a deviation occurs in the current phase at which the combined torque becomes maximum.

  In view of such a situation, Patent Document 1 discloses a control device for a salient pole type permanent magnet motor that detects demagnetization of a permanent magnet and changes the current phase in accordance with the detected demagnetization. . In Patent Document 1, the current magnetic flux is obtained by modifying the voltage equation of the salient pole type PM motor, or the current magnetic flux is detected by a sensor such as a Hall element or a magnetoresistive element before demagnetization. It is disclosed that a demagnetizing factor is calculated using a magnetic flux.

JP-A-8-103093

  According to the technique disclosed in Patent Document 1, the current phase can be changed in accordance with the change in the magnet torque. However, this technique performs feedback control after demagnetization of the permanent magnet occurs, for example, when the influence of demagnetization appears on the motor voltage or the like, and there is room for improvement from the viewpoint of speed of control. Moreover, although the voltage equation includes the motor rotation speed, in applications such as an electric vehicle, the motor rotation speed frequently changes according to the driving state of the vehicle.

  That is, an object of the present invention is to provide a control device for a rotating electrical machine that can quickly change the current phase based on the magnet temperature and improve the driving efficiency of the rotating electrical machine when the magnet temperature changes and the magnet torque increases or decreases. Is to provide.

  A control device for a rotating electrical machine according to the present invention includes a means for acquiring a magnet temperature of a rotor in a control device that controls driving of the rotating electrical machine based on a combined torque of a magnet torque and a reluctance torque, and an acquired magnet temperature. And a current phase setting means for setting the current phase to an optimum current phase that maximizes the combined torque.

  According to the above configuration, by setting the current phase based on the magnet temperature so as to maximize the combined torque, when the magnet temperature changes and the magnet torque increases or decreases, the drive efficiency of the rotating electrical machine is quickly improved. Can be made. For example, the current phase setting means sets the current phase so that the reluctance torque becomes closer to the maximum current phase as the magnet temperature increases in a range where the magnet temperature is less than a predetermined threshold.

Further, it is preferable that the current phase setting means sets the current phase on the retard side with respect to the optimum current phase when the magnet temperature is equal to or higher than a predetermined threshold value.
The current phase setting means preferably sets the current phase to 0 degrees when the magnet temperature is equal to or higher than a predetermined threshold.

  According to the above configuration, irreversible demagnetization can be prevented. As the current phase shifts toward the advance side and approaches 90 degrees, the reverse magnetic field increases and the demagnetization increases. That is, when the magnet temperature is higher than the threshold, demagnetization due to the high temperature and demagnetization due to the reverse magnetic field may occur, leading to irreversible demagnetization. For this reason, when the magnet temperature is equal to or higher than the threshold, the current phase is shifted to the retard side or set to 0 degree to suppress demagnetization caused by the reverse magnetic field and prevent irreversible demagnetization.

  According to the rotary electric machine drive control device of the present invention, when the magnet temperature changes and the magnet torque increases or decreases, the current phase can be quickly changed based on the magnet temperature to improve the drive efficiency of the rotary electric machine. It is. In addition, when the magnet temperature is equal to or higher than a predetermined threshold value, irreversible demagnetization is prevented by setting the current phase to the retard side of the optimum current phase or by setting the current phase to 0 degree. Can do.

It is a block diagram which shows the structure of the control apparatus which is embodiment of this invention. In the control apparatus which is embodiment of this invention, it is a figure which shows the relationship between an electric current phase and each torque (synthetic torque, magnet torque, and reluctance torque). It is a figure which isolate | separates and shows the synthetic | combination torque and magnet torque of FIG. In the control apparatus which is embodiment of this invention, it is a map which prescribes | regulates the relationship between magnet temperature and an electric current phase. It is a figure which shows the relationship between an electric current phase and a reverse magnetic field. 5 is a flowchart showing a procedure of current phase control in the control device according to the embodiment of the present invention.

  Hereinafter, embodiments of a control apparatus for a rotating electrical machine according to the present invention will be described in detail with reference to the drawings. Although the embodiment illustrates the motor drive system 10 mounted on an electric vehicle such as a hybrid vehicle, the application of the present invention is not limited to this. Although FIG. 1 shows a configuration diagram of the control device 20 that controls the driving of the motor 11, for example, the same configuration diagram can be applied to a generator mounted on a hybrid vehicle.

  First, the configuration of the motor drive system 10 will be described in detail with reference to FIG.

  As shown in FIG. 1, the motor drive system 10 boosts a DC voltage of a motor 11, a battery 12 that is a power storage device that supplies power to the motor 11, an inverter 13 that is an AC / DC converter, and a battery 12. Converter 14 that controls the motor 11 and a control device 20 that controls the drive of the motor 11. The motor drive system 10 also includes a rotation sensor 15, a current sensor 16, a temperature sensor 17, and the like as sensors for detecting information necessary for controlling the motor 11 by the control device 20.

  The hybrid vehicle has an engine that is a driving power source, a power distribution mechanism that distributes power between the engine and the two rotating electric machines (the motor 11 and the generator), an accelerator opening degree and a vehicle speed, and a charging rate of the battery 12. A power management control computer or the like that integrally controls the traveling function of the vehicle based on (SOC: State Of Charge) or the like is mounted.

  The motor 11 is a rotating electrical machine that generates magnet torque and reluctance torque. The motor 11 is rotationally driven by electric power supplied from the battery 12. Specifically, the direct current of the battery 12 is converted into a three-phase alternating current by the inverter 13 and supplied to the motor 11. The motor 11 includes, for example, a stator including U-phase, V-phase, and W-phase coils, and a rotor including permanent magnets. In addition, both a stator core and a rotor core can be comprised from the laminated body of an electromagnetic steel plate.

  In the rotor of the motor 11, for example, a magnet slot extending along the axial direction is formed in the peripheral portion of the rotor shaft, and the permanent magnet is inserted into the magnet slot. The permanent magnets are disposed, for example, at a predetermined interval around the periphery of the rotor shaft, and salient pole portions are formed between the permanent magnets. The motor 11 generates a magnet torque and a reluctance torque when the rotating magnetic field of the stator acts on the rotor.

  Inverter 13 includes a U-phase upper and lower arm, a V-phase upper and lower arm, and a W-phase upper and lower arm corresponding to each phase of motor 11. Each phase upper and lower arm includes a plurality of switching elements. As the switching element, a semiconductor element such as an IGBT (Insulated Gate Bipolar Transistor), a power MOS (Metal Oxide Semiconductor) transistor, or a power bipolar transistor can be used. On / off of the switching element is controlled by switching control signals S <b> 1 to S <b> 6 output from the control device 20.

For example, when the torque command τ ^* of the motor 11 is positive, the inverter 13 converts the DC voltage of the battery 12 into an AC voltage by turning on / off the switching element based on the switching control signals S1 to S6. Then, drive control is performed so that a positive torque is output from the motor 11. On the other hand, during regenerative braking, the torque command τ ^* of the motor 11 is set negative. In this case, the inverter 13 converts the AC voltage generated by the motor 11 into a DC voltage, and supplies the converted DC voltage to the converter 14. Converter 14 steps down the DC voltage and then supplies it to battery 12.

  The rotation sensor 15 is a sensor that detects the rotor rotation angle θ of the motor 11. The current sensor 16 is a sensor that detects a current flowing through the motor 11. Since the sum of instantaneous values of the currents Iu, Iv, and Iw of each phase is 0, the current sensor 16 detects the motor current for two phases (for example, the V-phase current Iv and the W-phase current Iw). What is necessary is just to arrange.

  The temperature sensor 17 is installed in the stator of the motor 11 and is used for managing the stator coil temperature Ts. As the temperature sensor 17, for example, a thermistor can be applied. The temperature detected by the temperature sensor 17 can be used to determine the temperature of the permanent magnet of the rotor (magnet temperature T).

The control device 20 is, for example, an electronic control unit (ECU: Electronic Control Unit) that controls the motor 11 in accordance with an output request from a power management control computer, and includes a CPU, an input / output port, a memory, and the like. The control device 20 generates a switching control signal for controlling the switching operation of the inverter 13 according to the torque command τ ^* that is an output request, and controls the motor 11 using the inverter 13. In order to execute this control, the control device 20 includes a current command generation unit 21, a PI calculation unit 22, a first coordinate conversion unit 23, a PWM signal generation unit 24, a second coordinate conversion unit 25, and a rotation speed. And an arithmetic unit 26.

In addition, when the magnet temperature T of the permanent magnet of the rotor changes and the magnet torque τ _M increases or decreases, the control device 20 quickly sets the current phase β based on the magnet temperature T so that the combined torque τ becomes maximum. It has a function of controlling and driving the motor 11 with high efficiency. The control device 20 includes a magnet temperature acquisition unit 27 and a current phase setting unit 28 in order to realize the function. In the present embodiment, the magnet temperature acquisition unit 27 and the current phase setting unit 28 are included in the block of the current command generation unit 21.

In PWM control, for example, a sine wave voltage command corresponding to the torque command τ ^* is compared with a carrier that is a triangular wave, and 1 (ON) when the sine wave is larger than the triangular wave, and 0 (OFF) when the sine wave is smaller than the triangular wave. ) Is generated. The voltage command is supplied as a sine wave signal having a phase difference of 120 ° with respect to each phase of the motor 11. A pulse width modulation voltage as a pseudo sine wave voltage is applied to each phase by turning on / off the switching element based on the generated pulse signal. As a control method by the control device 20, synchronous PWM control that synchronizes the carrier frequency and the rotation frequency of the motor 11 can be applied.

The current command generation unit 21 obtains the current command I ^* from the torque command τ ^{* for the} motor 11 and the rotation speed Nm of the motor 11 according to, for example, a map stored in advance. Then, as will be described in detail later, a d-axis current command Id ^* and a q-axis current command Iq ^* are generated from the current command I ^* and the magnet temperature T. Since the current phase β is determined by the ratio of the d-axis current and the q-axis current, it can be said that the current command generator 21 generates the current phase command β ^* from the current command I ^* and the magnet temperature T. An example of the predetermined map is a τ-N control map that defines the relationship between torque and rotational speed for each current value.

  The rotation speed Nm of the motor 11 is calculated based on the rotor rotation angle θ detected by the rotation sensor 15 by the rotation speed calculation unit 26. Further, in the second coordinate conversion unit 25, the d-axis is based on the V-phase current Iv and the W-phase current Iw detected by the current sensor 16 by coordinate conversion using the rotor rotation angle θ (3 phase → 2 phase). A current Id and a q-axis current Iq are calculated.

The PI calculation unit 22 generates a d-axis voltage command Vd ^* and a q-axis voltage command Vq ^* according to the control deviation. The PI calculation unit 22 includes a d-axis current command Id ^* and a q-axis current command Iq ^* generated by the current command generation unit 21, and a d-axis current Id and a q-axis current Iq calculated by the second coordinate conversion unit 25. the deviation between the ^{ΔId (ΔId = Id * -Id)} , ΔIq (ΔIq = Iq * -Iq) is input. Then, the PI calculation unit 22 performs a PI calculation (proportional integration calculation) with a predetermined gain for each of the d-axis current deviation ΔId and the q-axis current deviation ΔIq to obtain a control deviation, and a d-axis voltage corresponding to the control deviation A command Vd ^* and a q-axis voltage command Vq ^* are generated.

The first coordinate conversion unit 23 performs coordinate conversion (2 phase → 3 phase) using the rotor rotation angle θ of the motor 11, and the d-axis voltage command Vd ^* and the q-axis voltage command created by the PI calculation unit 22. Vq ^* is converted into voltage commands Vu ^* , Vv ^* , Vw ^* corresponding to each phase of the motor 11.

For example, the PWM signal generation unit 24 selects six switching elements of the inverter 13 based on the comparison between the voltage commands Vu ^* , Vv ^* , and Vw ^{* of} each phase supplied from the first coordinate conversion unit 23 and the carrier. Switching control signals S1 to S6 for turning on / off are generated. Then, the inverter 13 is switched according to the switching control signals S1 to S6, so that an AC voltage for outputting torque according to the torque command τ ^* is applied to the motor 11.

  Here, the configurations of the magnet temperature acquisition unit 27 and the current phase setting unit 28 will be described in detail with reference to FIGS.

  The magnet temperature acquisition unit 27 has a function of acquiring the magnet temperature T of the permanent magnet provided in the rotor of the motor 11. The magnet temperature acquisition means 27 can estimate the magnet temperature T using, for example, the coil temperature Ts detected by the temperature sensor 17 attached to the stator of the motor 11. As a method of estimating the magnet temperature T from the coil temperature, the loss of the motor 11 is calculated from the input current and its frequency, the heat generation amount is calculated from the loss, and the magnet temperature T is calculated based on the heat generation amount and the coil temperature Ts. An estimation method can be exemplified. The amount of heat generated by the motor 11 is approximately equal to the sum of the amount of heat generated by the loss around the coil, the amount of heat generated by the loss of the core, and the amount of heat generated by the loss around the magnet. The magnet temperature T can be estimated from the temperature Ts.

  Further, the magnet temperature acquisition means 27 can also estimate the magnet temperature T from the back electromotive voltage of the motor 11. Since a certain relationship is established among the counter electromotive voltage, the rotational speed Nm, and the magnet temperature T, the magnet temperature T can be estimated based on the counter electromotive voltage and the rotational speed Nm. When estimating the magnet temperature T from the coil temperature Ts or the counter electromotive voltage, a relationship between the coil temperature Ts or the counter electromotive voltage and the magnet temperature T is obtained in advance through experiments or the like, and a map defining this relationship is prepared. It is preferable to keep it.

  The magnet temperature acquisition means 27 can also acquire the actually measured magnet temperature T. Examples of the method for actually measuring the magnet temperature include a method of installing a thermocouple and a slip ring on the rotor, a method of installing a temperature sensor around the magnet, and transmitting detection information to the control device 20 wirelessly. Alternatively, when the coil temperature Ts and the magnet temperature T are approximately the same, the detected value by the temperature sensor 17 may be the magnet temperature T.

The current phase setting means 28 has a function of setting the current phase β to the optimum current phase β _Z at each magnet temperature T based on the magnet temperature T acquired by the magnet temperature acquisition means 27. The optimum current phase β _Z is a current phase at which the combined torque τ obtained by adding the magnet torque τ _M and the reluctance torque τ _R is maximum. The combined torque τ is represented by τ = p {φIq + (Ld−Lq) IdIq} where the number of pole pairs is p, the magnetic flux of the permanent magnet is φ, the d-axis inductance is Ld, and the q-axis inductance is Lq. τ _M = pφIq = pφIcos β and τ _R = p (Ld−Lq) IdIq = p (Ld−Lq) Isin2β. The current phase beta when a value obtained by differentiating the resultant torque τ in current phase β (dτ / dβ) is 0 is optimal current phase beta _Z.

When the torque command τ ^* and the rotational speed Nm change, the current phase setting means 28 determines the current phase β based on the magnet temperature T and the current command I ^* obtained from the torque command τ ^* and the rotational speed Nm. Set. That is, the current phase setting means 28 generates the d-axis current command Id ^* and the q-axis current command Iq ^* based on the magnet temperature T and the current command I ^* .

As shown in FIGS. 2 and 3, the magnet torque τ _M becomes maximum when the current phase β is 0 degree, and increases and decreases as the magnet temperature T changes. On the other hand, the reluctance torque τ _R becomes maximum when the current phase β is 45 degrees and does not change with the magnet temperature T. That is, the optimum current phase β _Z changes in the range of 0 to 45 degrees when the magnet temperature T changes. The current phase setting means 28 sets the current phase β in the range of 0 to 45 degrees according to the magnet temperature T.

For example, when magnet temperature T1 <magnet temperature T2, the magnet torque τ _M is magnet torque τ _M1 (magnet torque at magnet temperature T1)> magnet torque τ _M2 (magnet torque at magnet temperature T2). . For this reason, the optimum current phase β _{Z2 at the} magnet temperature T2 is shifted to the advance side rather than the optimum current phase β _{Z1 at} the magnet temperature T1. That is, the current phase setting means 28, as the magnet temperature T becomes higher, so as to approach the current phase beta _R reluctance torque tau _R is maximized, to shift the current phase beta to the advance side.

The current phase setting means 28 preferably sets the current phase β using, for example, a β-T map that defines the relationship between the current phase β and the magnet temperature T. The β-T map illustrated in FIG. 4 is a map for a predetermined current value, and defines an optimum current phase β _Z corresponding to the magnet temperature T in a range where the magnet temperature T is less than the threshold Th. That is, a plurality of β-T maps exist corresponding to each current level, and the current phase setting means 28 selects a β-T map corresponding to the current command I ^* .

In the β-T map illustrated in FIG. 4, the optimum current phase β _Z increases as the magnet temperature T increases in the range where the magnet temperature T is less than the threshold Th. The optimum current phase β _Z approaches the current phase β _R as the magnet temperature T increases, and the slope of the curve increases. This is because the degree of demagnetization increases as the magnet temperature T increases. On the other hand, the in beta-T map, the extent magnet temperature T is equal to or larger than the threshold Th, current phase beta is 0 degrees (hereinafter, the current phase in the case of 0 degrees between the current phase beta ₀ to) are.

The current phase setting unit 28 sets the current phase β to the retard side with respect to the optimum current phase β _Z when the magnet temperature T becomes equal to or higher than a threshold Th (for example, 150 ° C.). For example, in the range where the magnet temperature T is equal to or higher than the threshold Th, the current phase setting means 28 sets the current phase β to a constant value regardless of the magnet temperature T, or the current phase β is retarded as the magnet temperature T increases. Shift to. More preferably, when the magnet temperature T becomes equal to or higher than the threshold Th, the current phase β is set to 0 degrees. The current phase setting means 28 performs the setting using, for example, a β-T map illustrated in FIG.

That is, the current phase setting means 28 sets the current phase β to the optimum current phase β _Z according to the magnet temperature T when the magnet temperature T is lower than the threshold Th. Alternatively, a lower limit threshold value may be provided in addition to the threshold value Th that is the upper limit threshold value, and the current phase β may be set to the optimum current phase β _Z corresponding to the magnet temperature T within the range of the lower limit threshold value <T <the upper limit threshold value.

FIG. 5 shows the relationship between the current phase β and the reverse magnetic field at a predetermined current value. As shown in FIG. 5, the reverse magnetic field increases as the current phase β shifts toward the advance side and approaches 90 degrees. And as the reverse magnetic field increases, the demagnetization also increases. When the magnet temperature T is a high temperature equal to or higher than the threshold Th, the current phase setting unit 28 sets the current phase β to 0 degrees (current phase β ₀ ), for example, from the viewpoint of component protection. Suppresses demagnetization. That is, the current phase setting unit 28 sets the q-axis current command Iq ^* to 0 and generates a q-axis current command Iq ^* equal to the current command I ^* .

  Next, the control of the current phase β by the control device 20 having the above configuration will be described in detail with reference to the flowchart of FIG. FIG. 6 shows a control procedure in the current command generator 21.

  First, the coil temperature Ts detected by the temperature sensor 17 is acquired to determine the magnet temperature T (S10). This procedure is executed by the function of the magnet temperature acquisition means 27. As described above, the magnet temperature acquisition unit 27 can obtain the magnet temperature T using the map that defines the relationship between the coil temperature Ts or the back electromotive voltage and the magnet temperature T.

Subsequently, the current phase β is set to the optimum current phase β _Z (S12) or the current phase β ₀ (S14) depending on whether the magnet temperature T is equal to or higher than the threshold Th (S11). This procedure is executed by the function of the current phase setting means 28. As described above, the current phase setting means 28 can set the current phase β using the β-T map that defines the optimum current phase β _Z and the current phase β ₀ with the threshold Th as a boundary. Alternatively, a procedure for determining whether or not the magnet temperature T is equal to or higher than the threshold Th may be separately provided, and a current phase β may be set by selecting a map corresponding to the determination result from a plurality of β-T maps.

Then, the d-axis current command Id ^* and the q-axis current command Iq ^* are generated from the optimum current phase β _Z (S13) set in S12 or the current phase β ₀ (S15) set in S14.

As described above, since the control device 20 includes the magnet temperature acquisition unit 27 and the current phase setting unit 28, the control unit 20 sets the current phase β based on the magnet temperature T so that the combined torque τ is maximized. Can do. Therefore, when the magnet temperature T changes and the magnet torque τ _M increases or decreases, the drive efficiency of the motor 11 can be improved quickly. Further, the current phase setting means 28 sets the current phase β to 0 degree when the magnet temperature T is equal to or higher than a predetermined threshold Th, and therefore suppresses demagnetization caused by the reverse magnetic field, and is irreversible. Demagnetization can be prevented.

  The above-described embodiment can be changed in design without departing from the object of the present invention.

For example, in the above embodiment, the current phase setting means 28 sets the current phase β based on the magnet temperature T and the current command I ^*, and generates the d-axis current command Id ^* and the q-axis current command Iq ^*. As described above, after the current phase β is set based on the current command I ^* , the current phase β may be changed and set based on the magnet temperature T.

  DESCRIPTION OF SYMBOLS 10 Motor drive system, 11 Motor, 12 Battery, 13 Inverter, 14 Converter, 15 Rotation sensor, 16 Current sensor, 17 Temperature sensor, 20 Control apparatus, 21 Current command production | generation part, 22 PI calculating part, 23 1st coordinate conversion part , 24 PWM signal generation unit, 25 second coordinate conversion unit, 26 rotation speed calculation unit, 27 magnet temperature acquisition means, 28 current phase setting means.

Claims (3)

In a control device that controls the driving of the rotating electrical machine based on the combined torque of the magnet torque and the reluctance torque,
Means for obtaining the magnet temperature of the rotor;
Based on the acquired magnet temperature, a current phase setting means for setting the current phase to an optimum current phase at which the combined torque is maximum,
A control device for a rotating electrical machine, comprising: The control apparatus for a rotating electrical machine according to claim 1,
The control apparatus for a rotating electrical machine, wherein the current phase setting means sets the current phase to the retard side of the optimum current phase when the magnet temperature is equal to or higher than a predetermined threshold value. The control apparatus for a rotating electrical machine according to claim 2,
The current phase setting means sets the current phase to 0 degrees when the magnet temperature is equal to or higher than a predetermined threshold value.

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