JPWO2014147757A1 - Motor drive system, motor control device and motor - Google Patents

Abstract

A motor drive system according to an embodiment includes a motor having a distortion portion that causes mechanical distortion due to an excitation current, a motor control device that controls driving of the motor, and a distortion detection unit that detects distortion generated in the distortion portion of the motor. Is provided. The motor control device includes an estimation unit that estimates at least one of the speed and the position of the motor based on the distortion of the distortion portion detected by the distortion detection unit.

Description

  Embodiments disclosed herein relate to a motor drive system, a motor control device, and a motor.

  Conventionally, in a system equipped with a motor, when driving control of the motor is performed, a method of detecting the position and speed of the motor using a position sensor such as an encoder (for example, refer to Patent Document 1), a voltage or current of the motor A method for obtaining the position and speed of a motor is known (for example, see Patent Document 2).

JP 2009-095154 A JP 2012-228128 A

  However, it is difficult for a method using a position sensor such as an encoder to improve environmental resistance such as vibration and impact. In addition, the method for obtaining the position and speed of the motor based on the voltage and current of the motor can improve the environmental resistance, but there are many restrictions on the type and speed range of the applicable motor.

  One aspect of the embodiments has been made in view of the above, and an object thereof is to provide a new motor drive system, motor control device, and motor that are excellent in environmental resistance.

  A motor drive system according to an aspect of an embodiment includes a motor, a motor control device, and a distortion detection unit. The motor has a distortion portion where mechanical distortion is caused by an excitation current. The motor control device controls driving of the motor. The strain detection unit detects strain generated in the strain site. The motor control device includes an estimation unit that estimates at least one of a speed and a position of the motor based on the distortion of the distortion portion detected by the distortion detection unit.

  According to one aspect of the embodiment, it is possible to provide a new motor drive system, motor control device, and motor that are excellent in environmental resistance.

FIG. 1 is a diagram illustrating a configuration example of a motor drive system according to the embodiment. FIG. 2 is a schematic side view illustrating a configuration example of the motor illustrated in FIG. 1. 3 is a schematic cross-sectional view taken along line AA shown in FIG. FIG. 4A is a diagram showing the relationship between the magnetic repulsion force applied to the motor and the excitation current. FIG. 4B is a diagram showing the relationship between the magnetic attractive force applied to the motor and the excitation current. FIG. 5 is a diagram illustrating a configuration example of the distortion detection unit. 6 is a schematic cross-sectional view showing another configuration of the motor shown in FIG. FIG. 7 is a partial perspective schematic view of the motor shown in FIG. FIG. 8 is a schematic cross-sectional view showing still another configuration of the motor shown in FIG. FIG. 9 is a diagram illustrating a configuration example of the motor control device illustrated in FIG. 1. FIG. 10 is a diagram illustrating the relationship between the d-axis current, the distortion detection signal, the distortion signal, and the distortion rate. FIG. 11 is a diagram illustrating a relationship between an estimated electrical angle error and a high-frequency current command. FIG. 12A is a diagram illustrating a state of a distortion signal and a distortion rate when the electrical angle of the motor can be accurately estimated. FIG. 12B is a diagram illustrating a state of a distortion signal and a distortion rate when the electrical angle of the motor cannot be accurately estimated. FIG. 13 is a diagram showing the relationship between the strain rate and the strain differential value. FIG. 14 is a diagram illustrating a configuration example of a motor drive system according to another embodiment.

  Hereinafter, embodiments of a motor drive system, a motor control device, and a motor disclosed in the present application will be described in detail with reference to the drawings. In addition, this invention is not limited by embodiment shown below.

  FIG. 1 is a diagram illustrating a configuration example of a motor drive system according to the embodiment. As shown in FIG. 1, the motor drive system 1 according to the embodiment includes a three-phase AC motor 2 (hereinafter referred to as a motor 2) and a motor control device 3.

  The motor 2 is, for example, a permanent magnet synchronous motor such as an IPM (Interior Permanent Magnet) motor or an SPM (Surface Permanent Magnet) motor. A mechanical load 5 is connected to the output shaft of the motor 2. The motor 2 is not limited to a motor having a driving function, but may be a motor generator or a generator having power generation performance. For example, the motor 2 may be a generator connected to a rotor of a windmill or the like.

  The motor control device 3 includes a power conversion unit 11, a current detection unit 12, and a control unit 13. The motor control device 3 converts the DC power supplied from the DC power supply 4 into three-phase AC power having a desired frequency and voltage by known PWM (Pulse Width Modulation) control, and outputs it to the motor 2. The motor control device 3 may include a DC power supply 4.

  The power conversion unit 11 is connected between the DC power supply 4 and the motor 2 and supplies the motor 2 with a voltage and a current corresponding to the PWM signal supplied from the control unit 13. The power converter 11 is, for example, a three-phase inverter circuit configured by connecting six switching elements in a three-phase bridge.

  Note that the DC power supply 4 may have a configuration in which AC power is converted to DC power and output, for example, a configuration in which a rectifier circuit using a diode and a smoothing capacitor are combined. In this case, an AC power supply is connected to the input side of the rectifier circuit.

The current detection unit 12 detects a current (hereinafter referred to as an output current) supplied from the power conversion unit 11 to the motor 2. Specifically, the current detection unit 12 includes instantaneous values Iu, Iv, Iw (hereinafter referred to as output current I _{UVW) of} currents flowing between the power conversion unit 11 and the U phase, V phase, and W phase of the motor 2. Detect). The current detection unit 12 is a current sensor that detects a current by using, for example, a Hall element that is a magnetoelectric conversion element.

  The control unit 13 generates a PWM signal for performing on / off control of the switching elements constituting the power conversion unit 11 and outputs the PWM signal to the power conversion unit 11. The control unit 13 includes an estimation unit 15 that estimates the speed and position of the motor 2 based on the mechanical distortion of the motor 2 due to the excitation current. Based on the estimation result of the estimation unit 15, A PWM signal to be output to the conversion unit 11 is generated.

The motor 2 has a distortion part G that causes mechanical distortion due to the excitation current, and the mechanical distortion of the distortion part G is detected by the distortion detection unit 6. Information corresponding to the mechanical distortion of the motor 2 detected by the distortion detector 6 is output to the controller 13 as a distortion detection signal ε _fb . The control unit 13 estimates the speed and position of the motor 2 based on the mechanical strain information of the strain site G.

  Hereinafter, a specific example of the configuration of the motor drive system 1 will be described in detail. First, the mechanical distortion of the motor 2 due to the excitation current will be described.

  FIG. 2 is a schematic side view showing a configuration example of the motor 2, and FIG. 3 is a schematic cross-sectional view taken along the line AA shown in FIG. For convenience of explanation, FIG. 2 and FIG. 3 schematically show the motor 2. FIG. 2 shows a motor having two poles and six slots as an example of the motor 2. The motor 2 is a motor having more than two poles (for example, four poles and six poles) and an appropriate number of slots. May be.

  As shown in FIG. 3, the motor 2 includes a shaft 20, a rotor 21, and a stator 22, and the rotor 21 rotates about the rotation axis B by current supplied from the motor control device 3. The rotor 21 is attached to the shaft 20, and the stator 22 is disposed to face the outer peripheral surface of the rotor 21 via a predetermined gap.

  The rotor 21 includes a rotor core 31 and permanent magnets 32a and 32b. The rotor core 31 is formed in a cylindrical shape, and permanent magnets 32a and 32b are arranged side by side along the circumferential direction on the outer peripheral surface. The permanent magnet 32a and the permanent magnet 32b have different polarities. For example, the permanent magnet 32a has an N pole, and the permanent magnet 32b has an S pole.

  The stator 22 includes a yoke portion 33, a tooth portion 34, and a coil 35. The yoke portion 33 is formed in a cylindrical shape, and a plurality of tooth portions 34 are arranged at intervals along the inner peripheral surface of the yoke portion 33. A coil 35 is wound around each tooth portion 34. The yoke part 33 and the teeth part 34 form a stator core, and the stator core is formed, for example, by laminating a plurality of thin electromagnetic steel plates.

  Next, the magnetic force applied to the motor 2 when an excitation current is supplied to the motor 2 will be described. 4A is a diagram showing the relationship between the magnetic repulsive force applied to the motor 2 and the excitation current, and FIG. 4B is a diagram showing the relationship between the magnetic attraction force applied to the motor 2 and the excitation current.

  When a positive polarity excitation current (+ d-axis current) is supplied to the motor 2 (see the left diagram in FIG. 4A), as shown in the right diagram in FIG. 4A, the rotation axis B is between the rotor 21 and the stator 22. A magnetic repulsive force is generated in a direction orthogonal to (hereinafter referred to as a radial direction). On the other hand, when a negative excitation current (−d-axis current) is passed through the motor 2 (see the left diagram in FIG. 4B), as shown in the right diagram in FIG. 4B, between the rotor 21 and the stator 22. A magnetic attractive force is generated in the radial direction.

  Thus, when an exciting current is passed through the motor 2, a force acting in the radial direction is applied. Therefore, in the motor drive system 1 according to the present embodiment, the motor 2 is provided with a distortion portion G in which mechanical distortion occurs in the radial direction due to the excitation current, and the mechanical distortion of the distortion portion G is detected. Estimate the speed and position of 2.

  First, the distortion part G in which mechanical distortion occurs in the radial direction due to the excitation current in the motor 2 will be described. In the motor 2 shown in FIGS. 2 and 3, the thickness Da of the yoke portion 33 is set to be thin so that the cylindrical yoke portion 33 is mechanically distorted in the radial direction by the exciting current, and the yoke portion 33 is thin. It is formed. That is, the yoke part 33 is set as the distortion part G.

  As shown in FIG. 2, in the yoke portion 33, in the region facing the rotor 21 through the tooth portion 34, the central portion 36 in the direction of the rotation axis B is a thin distortion portion G, and both end portions 37 are thick. It is meaty. By making the both end portions 37 thick, the strength of the yoke portion 33 can be improved.

  The length L of the central portion 36 in the direction of the rotation axis B is not limited to the mode shown in FIG. 2 as long as it causes a distortion that can be detected by the distortion detector 6. In the example shown in FIGS. 2 and 3, the central portion 36 of the yoke portion 33 is thin. However, one end portion or all of both end portions 37 can be formed thin.

  Strain gauges 41 to 44 are attached to the outer peripheral surface of the central portion 36 of the yoke portion 33 as the strain detector 6. The strain gauges 41 to 44 are arranged at intervals of 90 degrees along the outer peripheral surface of the yoke portion 33.

  The strain detector 6 detects the strain at the strain site G based on the deformation rate of the strain gauges 41 to 44. FIG. 5 is a diagram illustrating a configuration example of the distortion detection unit 6. The strain detection unit 6 shown in FIG. 5 is configured by connecting strain gauges 41 to 44 and has power input terminals Tv1 and Tv2 and signal output terminals Tp and Tn.

The distortion detector 6 outputs a distortion detection signal ε _fb corresponding to the distortion of the distortion region G from the signal output terminals Tp and Tn by applying the voltage Va to the power input terminals Tv1 and Tv2. Note that the strain detection unit 6 is not limited to the configuration of FIG. The strain detector 6 may be other than a strain gauge, and for example, a piezoresistive element or the like can be used.

  Further, the outer peripheral surface of the stator 22 may be fixed to the inner peripheral surface of the cylindrical frame. For example, the yoke portion 33 and the frame are formed thin, and the yoke portion 33 and the frame are mechanically distorted in the radial direction by the excitation current. Thereby, the distortion site | part G can be formed with the yoke part 33 and a flame | frame. In this case, the distortion detector 6 can detect distortion due to the excitation current by being provided between the outer periphery of the yoke portion 33 and the inner periphery of the frame or on the outer periphery of the frame.

  Moreover, you may make it provide the distortion site | part G other than the yoke part 33 and a flame | frame. FIG. 6 is a schematic cross-sectional view showing another configuration of the motor 2, and FIG. 7 is a schematic partial perspective view of the E region shown in FIG. Depending on the strength of the yoke part 33 and the frame, it may not be easy to provide a thin part on the yoke part 33 or the frame, but even in such a case, the distortion part G should be arranged in the motor 2. Can do.

  In the motor 2 shown in FIG. 6, an annular member 45 is disposed as a distortion portion G in the gap between the rotor 21 and the stator 22. The annular member 45 is held in contact with the distal end surface of the tooth portion 34. As shown in FIG. 7, a strain gauge 41 is disposed between the outer peripheral surface of the annular member 45 and the tip surface of the tooth portion 34. Similarly, the other strain gauges 42 to 44 are disposed between the outer peripheral surface of the annular member 45 and the distal end surface of the tooth portion 34. Thereby, fixation of the strain gauges 41-44 can be performed stably.

  The strain gauges 41 to 44 need only be attached to the annular member 45 so that the strain of the annular member 45 can be detected. For example, the strain gauges 41 to 44 are attached to the inner peripheral surface of the annular member 45. Also good.

  Further, the annular member 45 can be made of, for example, a non-magnetic material, thereby avoiding the influence on the motor characteristics. However, if the influence on the motor characteristics is not a problem, the annular member 45 may not be a non-magnetic material. Further, instead of the annular member 45, an arcuate member may be used. In this case, for example, an arc-shaped member is disposed between the front end surfaces of the adjacent tooth portions 34, and a strain gauge is disposed on the arc-shaped member.

  The motor 2 shown in FIG. 6 has a configuration in which the tooth portion 34 is disposed. However, even in the case of a coreless motor that does not have the tooth portion 34 around which the coil 35 is wound, an annular member 45 or an arc-shaped member is used. Can be applied. FIG. 8 is a schematic cross-sectional view showing still another configuration of the motor 2 shown in FIG.

  The motor 2 shown in FIG. 8 is a coreless motor without the teeth portion 34 (see FIG. 6), and an annular member 45 is disposed on the rotor 21 side surface of the coil 35. Although not shown, strain gauges 41 to 44 are arranged on the outer peripheral surface or inner peripheral surface of the annular member 45 in the same manner as in the case of the motor 2 shown in FIGS. 6 and 7.

As described above, the motor 2 according to the embodiment has the distortion part G in which mechanical distortion occurs in the radial direction by the excitation current, and the distortion detection unit 6 is provided in the distortion part G. Then, a strain detection signal ε _fb corresponding to the strain at the strain site G is output from the strain detector 6.

The excitation current supplied from the motor control device 3 to the motor 2 is the d-axis component current (d-axis current) of the dq-axis rotation coordinate system synchronized with the rotation of the rotor 21 among the current supplied to the motor 2. . The motor control device 3 estimates the position and speed of the motor 2 based on the strain detection signal ε _fb output from the strain detection unit 6 and performs current control in the dq axis rotation coordinate system.

FIG. 9 is a diagram illustrating a configuration example of the motor control device 3. As shown in FIG. 9, the motor control device 3 includes an estimation unit 15, a position control unit 16, a speed control unit 17, a high-frequency current command device 18, and a current control unit 19. The motor control device 3 shown in FIG. 9 is a configuration example when the position of the motor 2 is controlled. When the speed of the motor 2 is controlled, the position control unit 16 can be omitted. Further, the high frequency current command device 18 may be provided as an external device different from the motor control device 3. Although not shown, the motor control device 3 has a part for supplying the voltage Va to the distortion detection unit 6 and a part for inputting the distortion detection signal ε _fb output from the distortion detection unit 6.

The estimation unit 15 estimates the position and speed of the motor 2 based on the strain detection signal ε _fb output from the strain detection unit 6. Position of the motor 2, which is estimated by the estimation unit 15 is a rotational position of the motor 2, where is the electric angle theta _e. The speed of the motor 2 estimated by the estimation unit 15 is the mechanical angular speed ω _m of the motor 2.

Estimation unit 15 outputs the information of the electrical angle theta _e of the estimated motor 2 as the estimated electrical angle theta ^ _e, also outputs the information of the mechanical angular omega _m of the estimated motor 2 as the estimated mechanical angular omega ^ _m . The estimating unit 15 will be described in detail later.

The position control unit 16 includes an integrator 61, a subtractor 62, and an APR (automatic position adjustment device) 63, and sends a speed command ω ^* to the speed control unit 17 based on the position command P ^* and the estimated mechanical angular velocity ω ^ _m ^. Is output. The integrator 61 outputs the estimate mechanical angle P ^ _m integrates the estimated mechanical angular omega ^ _m from the estimator 15 as an estimate of the mechanical angle P _m. Subtractor 62 outputs a deviation between the position command P ^* and the estimated mechanical angle P ^ _m and compares with the position command P ^* and the estimated mechanical angle P ^ _m to APR63. The APR 63 generates and outputs a speed command ω ^* so that the deviation between the position command P ^* and the estimated mechanical angle P ^ _m becomes zero.

The speed control unit 17 includes a subtractor 65 and an ASR (automatic speed adjustment device) 66, and sends a q-axis current command Iq ^* to the current control unit 19 based on the speed command ω ^* and the estimated mechanical angular velocity ω ^ _m. Output. Subtractor 65 outputs by comparing the speed command omega ^* and the estimated mechanical angular omega ^ _m a deviation between the speed command omega ^* and the estimated mechanical angular omega ^ _m to ASR66. The ASR 66 generates and outputs a q-axis current command Iq ^* so that the deviation between the speed command ω ^* and the estimated mechanical angular velocity ω ^ _m becomes zero.

The high frequency current command device 18 generates a high frequency current command Id _hfi and outputs it to the current control unit 19. The frequency of the high-frequency current command Id _hfi is set higher than the frequency of the voltage for driving the motor 2 and a desired speed control band, and is set to be equal to or lower than the current control frequency.

  The current control unit 19 includes a three-phase / dq coordinate converter 71, an adder 72, an ACRd (d-axis current controller) 73, an ACRq (q-axis current controller) 74, adders 75 and 76, dq / three-phase coordinate converter 77.

The three-phase / dq coordinate converter 71 performs three-phase / two-phase conversion on the output current I _UVW detected by the current detection unit 12, and further, the dq axis component of the orthogonal coordinates rotated according to the estimated electrical angle θ ^ _e. Convert to As a result, the output current I _UVW is converted into a q-axis current Iq _fb (torque current) that is the q-axis component of the dq-axis rotation coordinate system and a d-axis current Id _fb (excitation current) that is the d-axis component.

The adder 72 outputs the d-axis current command Id ^** generated by adding the high-frequency current command Id _HFI to the d-axis current command Id ^* to ACRd73. For example, the d-axis current command Id ^* is set to zero when the motor 2 is driven in the constant torque region, and is a value corresponding to the mechanical angular velocity ω _m of the motor 2 when the motor 2 is driven in the constant output region. Set to

The ACR d 73 generates a d-axis voltage command Vd ^* so that the deviation between the d-axis current command Id ^** and the d-axis current Id _fb becomes zero, and outputs it to the adder 75. In addition, ACRq 74 generates q-axis voltage command Vq ^* such that the deviation between q-axis current command Iq ^* and q-axis current Iq _fb becomes zero, and outputs it to adder 76.

The adder 75 adds the d-axis compensation voltage Vd _ff generates d-axis voltage command Vd ^** to the d-axis voltage command Vd ^*, the adder 76, the q-axis compensation voltage Vq to the q-axis voltage command Vq ^* _The q-axis voltage command Vq ^** is generated by adding _ff . The d-axis compensation voltage Vd _ff and the q-axis compensation voltage Vq _ff compensate for interference between the d-axis and the q-axis and the induced voltage. For example, the d-axis current Id _fb , the q-axis current Iq _fb, and the motor Calculated using parameters and the like.

The dq / three-phase coordinate converter 77 converts the d-axis voltage command Vd ^** and the q-axis voltage command Vq ^** into a three-phase voltage command V _UVW ^* by coordinate conversion based on the estimated electrical angle θ ^ _e . The three-phase voltage command V _UVW ^* is input to a PWM signal generation unit (not shown), and a PWM signal corresponding to the three-phase voltage command V _UVW ^* is generated by the PWM signal generation unit and output to the power conversion unit 11.

  Next, the configuration of the estimation unit 15 will be specifically described. As shown in FIG. 9, the estimation unit 15 includes a subtractor 81, an absolute value calculator 82, an LPF (low pass filter) 83, a differentiator 84, a subtractor 85, a PI controller 86, and an integrator. 87 and a mechanical angle calculation unit 88.

The subtractor 81 subtracts the distortion offset value ε _offset from the distortion detection signal ε _fb . As a result, the offset of the distortion detection signal ε _fb is canceled and output to the absolute value calculator 82. For example, when the strain detection unit 6 has the configuration shown in FIG. 5, the offset value ε _offset is a voltage Vc that is generated by a voltage Vb (= Va / 2) that is ½ of the voltage Va, a variation in the strain gauges 41 to 44, or the like. Is set in consideration of For example, the offset value ε _offset = Vb + Vc.

By canceling the offset of the strain detection signal ε _{fb in} this way, a signal corresponding to the strain at the strain site G can be extracted. Note that when the d-axis current command Id ^* is not zero, the d-axis current command Id ^* also appears as an offset of the distortion detection signal ε _fb , so the estimation unit 15 sets the distortion offset value ε _offset to the d-axis current command Id ^*. Adjust according to. Further, instead of the subtractor 81 that subtracts the distortion offset value ε _offset , a band pass filter that extracts only the component of the high-frequency current command Id _hfi from the distortion detection signal ε _fb may be used.

The absolute value calculator 82 calculates a distortion signal ε _r that is the absolute value of the distortion detection signal ε _fb from which the offset has been canceled, and outputs the distortion signal ε _r to the LPF 83. The LPF 83 (an example of a distortion rate calculator) is information indicating the distortion rate of the distortion region G by _performing an averaging process on the distortion signal ε _r with a frequency higher than the frequency of the high frequency current command Id _hfi as a cutoff frequency. A certain distortion rate ε _lpf is obtained.

FIG. 10 is a diagram illustrating a relationship among the d-axis current Id _fb , the strain detection signal ε _fb , the strain signal ε _r, and the strain rate ε _lpf . Note that the d-axis current Id _fb and the distortion detection signal ε _fb shown in FIG. 10 show a state in which there is no offset for convenience of explanation.

As described above, since the high-frequency current command Id _hfi is added to the d-axis current command Id ^* , a harmonic signal is superimposed on the d-axis current Id _fb . Since the d-axis current Id _fb is an excitation current of the motor 2, the harmonic signal is a harmonic excitation current and causes distortion at the distortion portion G of the motor 2. Therefore, the distortion detection signal epsilon _fb outputted from the strain detection unit 6 is at the same frequency as the high frequency current command Id _HFI, and a magnitude signal of corresponding to the high-frequency current command Id _HFI.

Here, the relationship between the distortion rate ε _lpf and the error Δθ _e of the estimated electrical angle θ ^ _e will be described with reference to FIG. Figure 11 is a diagram showing the relationship between the error [Delta] [theta] _e and the high-frequency current command Id _HFI of estimated electrical angle theta ^ _e.

If the estimated electrical angle theta ^ _e is an error _{Δθ e (= θ e -θ ^} e), as shown in FIG. 11, the high-frequency current command Id _HFI is on d 'axis obtained by rotating by an error [Delta] [theta] _e min . This is because the dq axis rotation coordinate system is set by the estimated electrical angle θ ^ _e , and the component of the d axis current flowing to the motor 2 by the high frequency current command Id _hfi is Id _hfi × cos (Δθ _e ). .

Therefore, distortion factor epsilon _lpf is greater the error [Delta] [theta] _e of the estimated electrical angle theta ^ _e the estimation unit 15 estimates is small (see FIG. 12A), conversely, a large error [Delta] [theta] _e of the estimated electrical angle theta ^ _e (See FIG. 12B). FIG. 12A is a diagram showing the state of the distortion signal ε _r and the distortion rate ε _lpf when the electrical angle θ _e of the motor 2 can be accurately estimated, and FIG. 12B shows the accuracy of the electrical angle θ _e of the motor 2. It is a figure which shows the state of distortion signal (epsilon) _r and distortion rate (epsilon) _lpf when not estimating well. 12A and 12B, the magnitude of the high-frequency current command Id _hfi is the same.

Therefore, the estimating unit 15 adjusts the estimated electrical angle θ ^ _e by configuring a PLL (Phase Locked Loop) so that the distortion rate ε _lpf is maximized, and thereby the electrical angle θ of the motor 2 is adjusted. _e is estimated accurately. Specifically, the differentiator 84 of the estimation unit 15 performs first-order differentiation of the distortion rate ε _lpf with the estimated electrical angle θ ^ _e and inverts the polarity, so that −dε _lpf / dθ ^ that is the strain differential value dε. _{Find e} . By inverting the polarity, the PLL is made negative feedback.

Incidentally, differentiator 84 calculates the time differential epsilon _lpf / dt of the strain rate epsilon _lpf, a time differential θ ^ _e / dt of the estimated electrical angle _{θ ^ e, (ε lpf /} dt) / (θ ^ e / dt), −dε _lpf / dθ ^ _e can be obtained as the strain differential value dε. In this case, if the time change of the estimated electrical angle θ ^ _e is small, the calculation error tends to increase. Therefore, the differentiator 84 performs a calculation when the estimated electrical angle θ ^ _e changes by a predetermined value. Thereby, a calculation error can be suppressed. Instead of calculating when the estimated electrical angle θ ^ _e changes by a predetermined value, for example, a technique such as an adaptive identification method (for example, a fixed trace method) can be applied.

The subtractor 85 compares the strain differential value dε output from the differentiator 84 with zero, and obtains the deviation between the strain differential value dε and zero. The PI controller 86 calculates and outputs the estimated electrical angular velocity ω ^ _e so that the deviation between the strain differential value dε and zero becomes zero. The estimated electrical angular velocity ω ^ _e is an estimated value of the electrical angular velocity ω _e of the motor 2.

FIG. 13 is a diagram showing the relationship between the strain rate ε _lpf and the strain differential value dε (= −dε _lpf / dθ ^ _e ), and the vertical axis shows the magnitude of the strain rate ε _lpf and the strain differential value dε. The horizontal axis indicates the error Δθ _e of the estimated electrical angle θ ^ _e with respect to the electrical angle θ _e . As shown in FIG. 13, it can be seen that the strain rate ε _lpf is maximized when the strain differential value dε is zero. Therefore, the estimation unit 15 obtains the estimated electrical angular velocity ω ^ _e so that the strain differential value dε becomes zero. Thereby, the estimated electrical angular velocity ω ^ _e can be adjusted to the electrical angle θ _e of the motor 2 with high accuracy.

The integrator 87 integrates the estimated electric angular velocity ω ^ _e, obtains and outputs the estimated electrical angle θ ^ _e. The estimated electrical angle θ ^ _e is an estimated value of the electrical angular velocity ω _e of the motor 2. Further, the mechanical angle calculation unit 88 calculates the estimated mechanical angular velocity ω ^ _m by dividing the estimated electrical angular velocity ω ^ _e by the number of poles of the motor 2 (two poles in the example shown in FIG. 3). The estimated mechanical angle P ^ _m (see FIG. 9) can be obtained by integrating the estimated mechanical angular velocity ω ^ _m .

  As described above, the motor control device 3 includes the estimation unit 15 and the distortion detection unit 6, and the estimation unit 15 estimates the position and speed of the motor 2 based on the distortion of the distortion portion G of the motor 2. Thereby, the position and speed of the motor 2 can be detected without using an encoder. In the above example, the position and speed of the motor 2 are estimated in the motor control device 3, but at least one of the position and speed of the motor 2 may be estimated.

  Further, in the conventional sensorless method in which the position and speed of the motor are estimated based on the induced voltage of the motor, it is difficult to estimate the position appropriately when the speed of the motor is low and no induced voltage is generated. On the other hand, in the motor drive system 1 of the present embodiment, the position and speed of the motor 2 can be easily estimated even when the induced voltage of the motor 2 is not generated.

  Further, the conventional sensorless control that estimates the position and speed of the motor by using the magnetic saliency of the motor is designed on the assumption of a motor having a magnetic saliency (for example, an IPM motor), such as an SPM motor. It is difficult to apply to motors with excellent power density. On the other hand, in the motor drive system 1 of this embodiment, since the distortion of the motor 2 due to the excitation current is used, the position and speed of the SPM motor and the like can be easily estimated.

  Further, in the conventional sensorless control, it is generally difficult to secure a sufficient estimation band of the motor position (phase), and therefore there is a possibility that torque ripple and speed ripple cannot be sufficiently compensated. On the other hand, in the motor drive system 1 of the present embodiment, the estimated band of the motor position (phase) can be easily ensured, thereby improving the operating performance.

In addition, the estimation part 15 is not restricted to the structure shown in FIG. For example, the estimation unit 15 may be configured to adjust the estimated electrical angular velocity ω ^ _e so that the amplitude of the distortion signal ε _{r and} the amplitude of the distortion detection signal ε _fb are maximized.

  Further, the distortion portion G of the motor 2 is not limited to the above-described configuration, and distortion is generated with respect to at least one of a magnetic repulsive force and a magnetic attractive force due to an excitation current supplied from the motor control device 3. Any configuration may be used.

The high frequency current commander 18, as shown in FIGS. 12A and 12B, has been described as outputting a sinusoidal high-frequency current command Id _HFI varying positive and negative around the zero frequency current command Id _HFI is The signal is not limited to such a waveform. For example, the high frequency current command Id _hfi may be a sine wave signal offset to the positive side or the negative side. Similarly to the distortion signal epsilon _r, it may be a waveform having a value only on the positive side half-wave waveform is continuously sinusoidal. By using such a waveform, the absolute value calculator 82 can be omitted.

Further, in the strain detection unit 6 shown in FIG. 5, the strain detection signal ε _fb is generated by making the four strain gauges 41 to 44 into a bridge configuration. However, as described above, the configuration of the strain detection unit 6 is applied. The configuration is not limited. For example, the strain detector 6 may be composed of one strain gauge and a resistance detector. In this case, the strain detection unit 6 detects the resistance value of one strain gauge with the resistance value detector, and outputs a signal having a magnitude corresponding to the resistance value as the strain detection signal ε _fb .

In the motor drive system 1, the distortion of the distortion part G of the motor 2 is detected by one distortion detection unit 6. However, the distortion of the distortion part G of the motor 2 is detected by two or more distortion detection units 6. The average value of the detected distortion may be used as the distortion detection signal ε _fb .

(Other embodiments)
Here, another embodiment of the motor drive system 1 will be described. FIG. 14 is an explanatory diagram showing a motor drive system according to another embodiment. In FIG. 14, among the configurations shown in FIGS. 1 and 9, elements different from the motor drive system 1 are mainly described, and description of components having functions similar to the motor drive system 1 is omitted, or The same reference numerals are assigned and the description is omitted.

  A motor drive system 1 </ b> A shown in FIG. 14 includes an encoder 7 that detects the position of the motor 2 in addition to the configuration of the motor drive system 1. The motor control device 3 </ b> A includes a determination unit 14.

The determination unit 14 receives the position detection signal θ _fb from the encoder 7 and the estimated mechanical angle P ^ _m output from the position control unit 16, and the difference between the position detection signal _θfb and the estimated mechanical angle P ^ _m is calculated. When it is equal to or greater than the predetermined value, it is determined that the encoder 7 is abnormal.

When there is no abnormality in the encoder 7, the control unit 13A controls the motor 2 using the position detection signal θ _fb from the encoder 7 as a position feedback signal. On the other hand, when the abnormality of the encoder 7 is determined, the control unit 13A controls the motor 2 using the estimated electrical angle θ ^ _e and the estimated mechanical angular velocity ω ^ _m estimated by the estimation unit 15.

  With this configuration, in the motor drive system 1A, even if a problem occurs in the encoder 7 used for motor control, motor control based on the distortion detector 6 is possible, and a fail-safe function can be realized at low cost. .

  As described above, the motor drive system 1, 1 </ b> A according to the embodiment includes the motor 2 having the distortion portion G in which mechanical distortion occurs due to the excitation current, and the motor control device 3 that controls driving of the motor 2. 3A and a distortion detection unit 6 that detects distortion of the distortion part G. The motor control devices 3 and 3 </ b> A include an estimation unit 15 that estimates at least one of the position and the speed of the motor 2 based on the distortion of the distortion site G detected by the distortion detection unit 6.

  According to the motor drive systems 1 and 1A, it is possible to estimate at least one of the position and speed of the motor 2 using a robust and low-cost distortion detection method, thereby improving environmental resistance performance and cost. Reduction can be achieved. Note that a motor can also be configured by the motor 2 (motor body) and the strain detection unit 6.

  Further, as described above, the motor drive systems 1 and 1A according to the present embodiment can be applied regardless of the type, regardless of whether the permanent magnet of the motor 2 is an embedded type or a surface-mounted type. Therefore, for example, it is possible to use an SPM motor having a high power density in which a permanent magnet is bonded to the surface of the rotor 21, which contributes to miniaturization of the motor 2.

  Further effects and modifications can be easily derived by those skilled in the art. Thus, the broader aspects of the present invention are not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications can be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

1, 1A Motor drive system 2 Motor (motor part)
3, 3A Motor control device 4 DC power supply 5 Mechanical load 6 Strain detection unit 7 Encoder 11 Power conversion unit 12 Current detection unit 13, 13A Control unit 14 Determination unit 15 Estimation unit 16 Position control unit 17 Speed control unit 18 High frequency current command device 19 Current control unit 21 Rotor 22 Stator 82 Absolute value calculator 83 LPF (distortion rate calculator)
84 Differentiator

Claims (11)

A motor having a distortion part that causes mechanical distortion due to the excitation current;
A motor control device for controlling the driving of the motor;
A strain detection unit that detects strain generated in the strain site;
The motor control device
A motor drive system comprising: an estimation unit configured to estimate at least one of a speed and a position of the motor based on the distortion of the distortion portion detected by the distortion detection unit. The motor control device
A high-frequency current command device for generating a high-frequency current command for superimposing a high-frequency excitation current on the output current to the motor;
The distortion detector
Detecting distortion generated in the distortion site by the high-frequency excitation current,
The estimation unit includes
2. The motor drive system according to claim 1, wherein at least one of a speed and a position of the motor is estimated based on a distortion due to the high-frequency excitation current of the distortion portion detected by the distortion detection unit. The estimation unit includes
The motor drive system according to claim 1, wherein a speed or position at which the distortion of the distortion portion detected by the distortion detection unit is maximized is estimated as the speed or position of the motor. The estimation unit includes
An absolute value calculator for calculating an absolute value of a distortion detection signal from the distortion detector;
A distortion rate calculator that calculates an average value of the absolute values of the distortion detection signals calculated by the absolute value calculator and outputs the distortion as a distortion rate;
The motor drive system according to claim 3, wherein a speed or position at which the distortion rate is maximized is estimated as a speed or position of the motor. The estimation unit includes
A differentiator for differentiating the distortion rate;
The motor drive system according to claim 4, wherein the position of the motor is estimated so that a differentiation result by the differentiator becomes zero. The motor is
A rotor, and a stator disposed opposite to the rotor via a gap,
The motor drive system according to any one of claims 1 to 5, wherein the distortion part is formed in the stator. The motor is
A rotor, and a stator disposed opposite to the rotor via a gap,
The motor drive system according to any one of claims 1 to 5, wherein the distortion part is disposed in the gap. A power converter for supplying torque current and excitation current to the motor;
An acquisition unit that acquires a distortion detection signal from a distortion detection unit that detects distortion generated in a distortion part of the motor in which mechanical distortion occurs due to the excitation current;
A motor control apparatus comprising: an estimation unit configured to estimate at least one of a speed and a position of the motor based on a distortion detection signal acquired by the acquisition unit. A high-frequency current command device for generating a high-frequency current command for superimposing a high-frequency excitation current on the output current to the motor;
The estimation unit includes
The motor control device according to claim 8, wherein at least one of a speed and a position of the motor is estimated based on a distortion due to the high-frequency excitation current of the distortion portion detected by the distortion detection unit. A motor comprising a motor section having a predetermined distortion portion where mechanical distortion is caused by an exciting current. The motor according to claim 10, further comprising a distortion detection unit that detects distortion generated in the distortion site.

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