JP2013183558A - Motor controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor controller in which response and stability of control are enhanced, by reducing the influence of delay time of current detection and calculation, thereby avoiding problems such as divergence when increasing the control gain of a voltage calculating section.SOLUTION: The motor controller includes a voltage calculating section 2 which calculates command voltages Vd, Vq on the basis of the command currents Id, Iqand feedback currents Id, Id, voltage application means 4 for applying an application voltage, generated based on the command voltages Vd, Vq, to the armature winding, current detection means 5 for detecting the actual currents, over a predetermined period of time, as the measurement currents Id, Iq, angular speed detection means 6 for detecting the angular speed ω of the rotor, and a current estimation observer 7 which estimates the actual current, at a required detection time before the detection end time of the measurement currents Id, Iq, based on the measurement currents Id, Iq while taking account of the command voltages Vd, Vq and the angular speed ω, and determines the actual current thus estimated as feedback currents Id, Id.

Description

  The present invention relates to a motor control device that feedback-controls a current to be supplied to an armature winding of a motor.

  In recent years, a technique for applying an inverter to a control device for a three-phase synchronous motor has become widespread, and control performance has been greatly improved as compared with the old state. In the control device to which the inverter is applied, the phase of the rectangular wave voltage is controlled by detecting and feeding back the current of each phase flowing in the armature winding of the stator, based on the command torque or command current from the outside. In many cases, the current is controlled by controlling the effective voltage value by a pulse width modulation (PWM) method. An example of this type of control technique is disclosed in Patent Document 1.

  The motor control device disclosed in Patent Document 1 estimates a current observer that estimates a current value using a model for one phase of the motor, and a current disturbance voltage using a model for one phase of the motor. A disturbance observer is provided, and an estimated current value at the time of current detection is obtained using past estimated values of both observers and used for current control. Thus, it is described that a current estimation value with a small calculation delay in current control and a small variation can be obtained, and that highly accurate current control can be performed.

JP 2002-252991 A

  By the way, in the control device of Patent Document 1, the phase delay (calculation delay time) that occurs when the current estimated value is calculated using the voltage command (command voltage) and the current detection value is considered. The time required for detection when acquiring is not considered. The detected current value is usually digitally measured using an AD converter, but requires a predetermined latch time for the purpose of stabilizing the measured value during AD conversion operation. For this reason, the acquired current detection value actually becomes a past value corresponding to the latch time, and this detection delay time contributes to the calculation error.

  In addition to Patent Document 1, many arithmetic processing methods have been proposed for the purpose of improving control performance in a general current control system. The background is the improvement in performance of CPUs and peripherals, and digital processing has become common instead of analog processing. However, there are problems such as an increase in calculation delay time accompanying an increase in calculation load and an increase in detection delay time caused by AD conversion time and communication delay. In particular, in the motor control device, the delay in obtaining the detected current value hinders improvement in control responsiveness. In other words, if the control gain (proportional gain, integral gain, etc.) is increased by proportional integral control of the voltage calculation unit that calculates the command voltage, the response may diverge depending on the motor speed, and the control gain is limited. It is difficult to improve control responsiveness and stability.

  In this type of control, a method of reducing the calculation load by calculation using a dq coordinate axis based on the rotational position of the rotor magnet is often used. However, Patent Document 1 uses a model for one phase of the motor. The operation that was performed. For this reason, the same calculation is performed for each of the three phases, the calculation load increases, and the calculation delay time increases.

  The present invention has been made in view of the above problems of the background art, and reduces the influence of current detection and calculation delay time to reduce the risk of problems such as divergence when the control gain of the voltage calculation unit is increased. An object to be solved is to provide a motor control device that avoids and improves control responsiveness and stability.

  The invention of the motor control device according to claim 1 that solves the above-described problem includes a command current obtained from an external command current or an external command torque, and an actual current flowing in an armature winding provided in a stator of the motor. Based on a feedback current that is detected and fed back, a voltage calculation unit that calculates a command voltage to be applied to the armature winding in order to make the actual current coincide with the command current, and a calculated command voltage A voltage applying means for generating an applied voltage and applying the applied voltage to the armature winding; a current detecting means for detecting the actual current over a predetermined time required for detection; and a rotor for the motor. An angular velocity detecting means for detecting an angular velocity at which the rotation of the motor is performed, and based on the actual measurement current and taking the command voltage and the angular velocity into consideration, the time when the detection is required rather than the end of the detection of the actual current Only previous actual current is estimated, and a current estimating observer which the actual current estimated and the feedback current.

  The invention according to claim 2 is the three-phase synchronous motor according to claim 1, wherein the motor has a magnet in the rotor and the armature winding in the stator, and the voltage calculator and the current estimation The observer performs calculation and estimation using a dq coordinate axis based on the rotational position of the rotor magnet.

  The invention according to claim 3 is the armature winding according to claim 2, wherein the current estimation observer is based on a detection deviation obtained by subtracting the estimated actual current from the measured current, and is represented on the dq coordinate axis. The resistance, inductance, and induced voltage constant are estimated in consideration of the command voltage and the angular velocity.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the current detection unit includes an AD converter that converts an analog actual current into a digital actual measured current. It includes a latch time during the conversion operation of the AD converter.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the voltage calculation unit performs proportional-integral control based on a command deviation obtained by subtracting the feedback current from the command current.

  In the motor control device according to the first aspect of the present invention, the current estimation observer estimates the actual current before the time required for detection from the end of detection of the measured current, and uses the estimated actual current as a feedback current. As a result, the delay of the required detection time is compensated, and the command current, the feedback current, and the command voltage have the same time value. Therefore, the influence of the delay time of the current detection can be reduced, and the calculation accuracy is improved. Furthermore, even if the control gain of the voltage calculation unit is increased, problems such as divergence do not occur, and control responsiveness and stability can be improved.

  In the invention according to claim 2, the voltage calculation unit and the current estimation observer perform calculation and estimation using the dq coordinate axes. Therefore, the calculation load is reduced as compared with the calculation method in the three-phase region including Patent Document 1, and the influence of the calculation delay time is reduced and the calculation accuracy is improved.

  In the invention according to claim 3, the current estimation observer is based on the detection deviation obtained by subtracting the estimated actual current from the measured current, and takes the command voltage and angular velocity into consideration for the resistance, inductance, and induced voltage constant of the armature winding. And make an estimate. Therefore, when the command current changes and a transient response is required, the previous actual current can be accurately estimated based on the motor voltage equation, improving the response and stability during the transient response. it can.

  In the invention according to claim 4, the current detection means includes an AD converter that converts an actual current of an analog amount into a measured current of a digital amount, and the required detection time includes a latch time during the conversion operation of the AD converter. . Therefore, the current estimation observer estimates the actual current before the AD converter latch time as a feedback current, so that problems such as divergence do not occur even if the control gain of the voltage calculation unit is increased. Responsiveness and stability can be improved.

  In the invention according to claim 5, the voltage calculation unit performs proportional-integral control based on the command deviation obtained by subtracting the feedback current from the command current. As described above, the present invention has a remarkable effect of improving the responsiveness and stability at the time of transient response by combining the method for calculating the command voltage by the proportional integral control and the current estimation observer.

It is a block diagram showing the whole motor control unit composition of an embodiment. It is a block diagram which shows the internal structure of a current estimation observer. It is a figure which shows the result of having simulated the change of d-axis current and q-axis current when an electric current command increases in embodiment. It is a figure which shows the result of having simulated the change of d-axis current and q-axis current when an electric current command increases in a prior art.

  A motor control device 1 according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram illustrating an overall configuration of a motor control device 1 according to an embodiment. The motor control device 1 is configured to include a computer that is operated by software. A control target is a three-phase synchronous motor 9 and control amounts are three-phase voltages Vu, Vv, and Vw applied to the motor 9.

  The three-phase synchronous motor 9 is an embedded magnet synchronous motor configured by embedding a magnet in a rotor core (not shown) and winding an armature winding around a stator core (not shown), and is not limited thereto. The motor control device 1 performs an operation using the dq coordinate axes so as to energize the motor 9 with a command current received from the outside or a command current obtained from a command torque received from the outside, and performs a three-phase voltage Vu, Vv, Vw. To control. The motor control device 1 includes a voltage calculation unit 2, a voltage application unit 4, a current detection unit 5, an angular velocity detection unit 6, and a current estimation observer 7.

  The angular velocity detection means 6 includes an angle sensor that detects the rotational phase θ of the rotor of the three-phase synchronous motor 9 and an angular velocity converter (not shown) that converts the rotational phase θ into an angular velocity ω of an electrical angle. The angle sensor can be configured using, for example, a known resolver, and sends the detected rotational phase θ to the angular velocity conversion unit. The angular velocity conversion unit calculates the angular velocity ω by dividing the change amount of the rotational phase θ obtained by the two detections by the elapsed time (corresponding to time differentiation), and applies the voltage applying means 4, the current estimation observer 7, and a later-described Output to the 3/2 phase converter 53.

  The current detection means 5 is a means for detecting the actual current of the motor 9 over a predetermined time required for detection to obtain an actual measurement current. The current detection means 5 includes two current detection units 51v and 51w, an AD converter 52, and 3/2. The phase conversion unit 53 is configured. The two current detection units 51v and 51w are respectively provided on the V-phase input line 91v and the W-phase input line 91w of the three-phase input lines 91u, 91v, and 91w connected to the armature winding of the motor 9. ing. The current detectors 51v and 51w can be configured using, for example, a known current transformer or a shunt resistor, and detect the V-phase current Iv and the W-phase current Iw, respectively, and send an analog detection signal to the AD converter 52. Output.

  The AD converter 52 is a two-channel type, and converts the analog detection signals of the V-phase current Iv and the W-phase current Iw into digital measured currents and transmits them to the 3 / 2-phase conversion unit 53. First, the 3 / 2-phase conversion unit 53 calculates the third-phase U-phase current Iu using the fact that the vector sum of the three-phase currents Iu, Iv, and Iw is zero. Next, the 3/2 phase conversion unit 53 uses a known conversion formula using the angular velocity ω to convert the three-phase currents Iu, Iv, and Iw into d-axis currents on the dq coordinate axis based on the rotational position of the rotor magnet. Id and q-axis current Iq are converted and output to the current estimation observer 7.

  Here, when the actual current flowing through the three-phase input lines 91u, 91v, 91w is used as a reference, the d-axis current Id and the q-axis current Iq have a delay time corresponding to a predetermined required time ΔT. Yes. The breakdown of the required detection time ΔT is the longest latch time during the conversion operation of the AD converter 52. In addition, the required transmission time from the AD converter 52 to the 3/2 phase conversion unit 53 and the 3/2 phase conversion unit The calculation required time in 53, the output required time from the 3/2 phase conversion part 53 to the electric current estimation observer 7, etc. are included.

  The voltage calculation unit 2 calculates a command voltage to be applied to the armature winding in order to match the actual current with the command current based on the command current from the outside and the feedback current. The voltage calculation unit 2 performs calculation using the dq coordinate axes, and performs calculation processing in parallel with respect to the d-axis and the q-axis as illustrated. The voltage calculation unit 2 includes a d-axis side adder 21 and a d-axis proportional integration controller 22 (d-axis PI controller), a q-axis side adder 23 and a q-axis proportional integration controller 24 (q-axis PI controller). It consists of and.

d-axis-side adder 21 calculates the d-axis command deviation ΔId by subtracting the d-axis feedback current Id ^∧ from the d-axis command current Id ^*, and outputs the d-axis PI controller 22 (d-axis PI controller) . The d-axis proportional integration controller 22 obtains a command d-axis voltage Vd by proportional integration control and outputs it to the voltage applying means 4. Similarly, the q-axis side adder 23 subtracts the q-axis feedback current Iq ^∧ from the q-axis command current Iq ^* to obtain the q-axis command deviation ΔIq, and the q-axis proportional integration controller 24 (q-axis PI controller). Output to. The q-axis proportional integration controller 24 obtains a command q-axis voltage Vq by proportional integration control and outputs it to the voltage applying means 4. The d-axis feedback current Id ^∧ and the q-axis feedback current Iq ^∧ are estimated values of the actual current output from the current estimation observer 7 as will be described in detail later.

  The voltage applying means 4 generates a three-phase applied voltage based on the calculated command d-axis voltage Vd and command q-axis voltage Vq and applies it to the armature winding. The voltage applying means 4 can be composed of a 2/3 phase converter, a battery, and a pulse width modulation circuit (not shown). The 2 / 3-phase converter converts the command d-axis voltage Vd and the command q-axis voltage Vq into three-phase voltages Vu, Vv, and Vw by a known conversion formula using the angular velocity ω. The pulse width modulation circuit controls switching between positive and negative polarities of the DC output voltage of the battery, controls the energizing time width by pulse width modulation (PWM), and adjusts the effective voltage value to adjust the three-phase voltages Vu, Vv, Vw. Is applied to the armature winding.

Next, voltage equations expressed on the dq coordinate axes will be described, and the internal configuration of the current estimation observer 7 will be described. As is well known, in the magnet-embedded three-phase synchronous motor 9, the following equation 1 is established as a voltage equation.

When Expression 1 is expressed by a differential equation, the following Expression 2 is established. In Equation 2, when the actual current of the d-axis current Id and the q-axis current Iq is the state variable vector x, the command d-axis voltage Vd and the command q-axis voltage Vq are the input vector u, and the coefficient matrix is rewritten, Equation 3 is obtained.

Here, the current estimation observer 7 is based on the actually measured d-axis current Id and q-axis current Iq, and considers the command d-axis voltage Vd, the command q-axis voltage Vq, and the angular velocity ω, and from the end of detection of the measured current. Also, the previous actual current is estimated for the required detection time ΔT. Furthermore, the estimated actual current is output to the voltage calculation unit 2 as a feedback current. In the present embodiment, represent actual current estimated d-axis feedback current Id ^∧, and in the q-axis feedback current Iq ^∧, which is the estimated value x ^∧ of the state variable vector. Further, the d-axis current Id and the q-axis current Iq when the three-phase voltages Vu, Vv, Vw corresponding to the command d-axis voltage Vd and the command q-axis voltage Vq (input vector u) are input to the motor 9 are output vectors y. And Then, the estimated value y ^∧ of the output vector is represented by multiplied by the matrix C in the estimated value x ^∧ of the state variable vector. Furthermore, the current estimation observer 7 increases the calculation accuracy by feeding back the estimated value y ^出力 of the output vector internally.

Thus, the estimated value x ^∧ of the state variable vector, and estimate y ^∧ of the output vector is expressed by Equations 4 and 5.

  From the above, the internal configuration of the current estimation observer 7 is determined. FIG. 2 is a block diagram showing the internal configuration of the current estimation observer 7. As illustrated, the current estimation observer 7 includes an adder 71, a multiplier 72, an adder 73, a multiplier 74, a multiplier 75, an integrator 76, a multiplier 77, and a delayer 78.

The adder 71 subtracts the estimated value y ^{か ら} from the output vector y to obtain a detection deviation e, and outputs it to the multiplier 72. The multiplier 72 multiplies the detected deviation e by L, and outputs the multiplication result (L · e) to the adder 73. However, L is a constant coefficient. The multiplier 74 multiplies the coefficient matrix B by the input vector u and outputs the multiplication result (B · u) to the adder 73. Further, the multiplier 75 multiplies the coefficient matrix A by the estimated value x ^{フ ィ}ー^{ド バ ッ ク of} the state variable vector fed back from the output side, and outputs the multiplication result (A · x ^∧ ) to the adder 73.

The adder 73 is a three input (L · e), and (B · u), and by adding the ^{(A · x ∧) (dx} ∧ / dt), and outputs to the integrator 76. The integrator 76, (dx ^∧ / dt) integral to the determined estimated value x ^∧ of the state variable vector, which feedback output to the multiplier 75 and outputs to the multiplier 77. The multiplier 77, the estimated value y ^∧ of the output vector by multiplying the estimated value x ^∧ the matrix C, that obtains a d-axis feedback current Id ^∧ and q-axis feedback current Iq ^∧. Estimates y ^∧ of the output vector is output to the voltage calculating portion 2, and is fed back output to the delay unit 78. The delay unit 78 delays the estimated value y ^の of the output vector by the detection delay time ΔT and outputs the delayed result to the adder 71.

With the internal configuration of the current estimation observer 7 described above, it is possible to estimate the output vector estimation value y ^示 expressed by Equation 4 and Equation 5. Here, since the delay unit 78 performs a delay corresponding to the detection delay time ΔT required for detecting the actual current on the motor 9 side, the estimated value y ^∧ of the output vector, that is, the d-axis feedback current Id ^∧ and the q-axis feedback current Iq. ^∧ is a value obtained by estimating the previous actual current for the required detection time ΔT.

The current estimation observer 7 constitutes a feedback control system of the estimated value y ^、, and the pole of this system can be arbitrarily determined by a constant coefficient L. That is, by setting the constant coefficient L optimally, high-speed and stable control can be realized.

  Next, the operation and effect of the motor control device 1 of the embodiment will be described in comparison with the prior art. As a conventional motor control device, a configuration is considered in which the current estimation observer 7 is not provided and the d-axis current Id and the q-axis current Iq detected by the current detection means 5 are fed back to the voltage calculation unit 2 as they are.

3 and 4 show the results of simulating changes in the d-axis currents Id1 and Id2 and the q-axis currents Iq1 and Iq2 when the current command (q-axis current command Iq ^* ) increases in the embodiment and the prior art. FIG. 3 and FIG. 4, the horizontal axis represents time t (sec), the vertical axis represents current (%), FIG. 3 shows changes in the d-axis current Id1 and the q-axis current Iq1, and FIG. Shows changes in the d-axis current Id2 and the q-axis current Iq2. As simulation conditions, the q-axis current command Iq ^* increased from 0% to 100% at time t0, and the d-axis current command Id ^* was 0% and unchanged, and the actual current was simulated.

  As a result of the simulation, in the embodiment shown in FIG. 3, the q-axis current Iq1 increases sharply from time t0, and when it approaches 100%, the increasing tendency slows down and smoothly settles to 100%. In other words, it responds quickly and stably. Further, the d-axis current Id1 is generated only slightly after time t0 and is stable. Therefore, the control gain (proportional gain and integral gain) of the voltage calculation unit 2 can be further increased.

  On the other hand, in the prior art, the q-axis current Iq2 increases sharply from time t1 that is later than time t0, temporarily overshoots 100% and vibrates, resulting in an unstable response. . The d-axis current Id2 also oscillates after time t0 and has an unstable response. Therefore, when both are compared, the embodiment is superior in both the response and stability at the time of transient response than the prior art.

  Furthermore, since the voltage calculation unit 2 and the current estimation observer 7 of the motor control device 1 according to the embodiment perform calculation and estimation using the dq coordinate axis, compared with the calculation method in the three-phase region including Patent Document 1. The calculation load is reduced, the influence of the calculation delay time is reduced, and the calculation accuracy is improved.

The current estimation observer 7, measured current Id, actual current Id ^∧ estimated from Iq, together based on the detection deviation e obtained by subtracting the Iq ^∧, resistance R of the armature winding, the inductance Lp, Lq and the induced voltage constant Ke Is estimated in consideration of the command voltages Vd and Vq and the angular velocity ω. Thus, the command current Id ^*, when it is required transient response Iq ^* changes, the detection time required based on the voltage equation of the motor 9 [Delta] T by previous actual current Id ^∧, it can accurately estimate the Iq ^∧ In addition, the response and stability during a transient response can be improved.

The current detection means 5 includes an AD converter 52 that converts an analog actual current into digital measured currents Id and Iq, and a required detection time ΔT includes a latch time during the conversion operation of the AD converter 52. Yes. Therefore, the current estimation observer 7 estimates the previous actual current by the latch time of the AD converter 52 the feedback current Id ^∧, and Iq ^∧, thereby, increasing the control gain of the voltage calculating portion 2 diverge like Thus, the control responsiveness and stability can be improved.

  Furthermore, in this embodiment, the voltage calculation unit 2 that calculates the command voltages Vd and Vq by proportional-integral control and the current estimation observer 7 are combined, and the effect of improving the response and stability at the time of transient response is remarkable. Become.

  The internal configuration of the current estimation observer 7 according to the embodiment is an example, and various applications and modifications are possible. Further, the internal configuration of the voltage calculation unit is not limited to the proportional integral control method.

1: Motor controller 2: Voltage calculation unit
21: d-axis side adder 22: d-axis proportional integral controller
23: q-axis side adder 24: q-axis proportional integral controller 4: voltage application means 5: current detection means
51v, 51w: current detection unit 52: AD converter
53: 3/2 phase conversion unit 6: Angular velocity detection means 7: Current estimation observer
71: Adder 72: Multiplier 73: Adder 74: Multiplier
75: Multiplier 76: Integrator 77: Multiplier 78: Delay device 9: Three-phase synchronous motor Id ^* : Command d-axis current Iq ^* : Command q-axis current ΔId: d-axis command deviation ΔIq: q-axis command deviation Iv, Iw: V-phase and W-phase current ω: angular velocity u: input vector
Vd: Command d-axis voltage Vq: Command q-axis voltage x: State variable vector x ^∧ : Estimated value of state variable vector y: Output vector
Id: d-axis current Iq: q-axis current y ^∧ : estimated output vector
Id ^：: d-axis feedback current Iq ^：: q-axis feedback current

Claims (5)

Based on the command current obtained from the command current from the outside or the command torque from the outside, and the feedback current obtained by detecting and feeding back the actual current flowing in the armature winding provided in the stator of the motor, the actual current is A voltage calculation unit for calculating a command voltage to be applied to the armature winding in order to match the command current;
Based on the calculated command voltage, voltage applying means for generating an applied voltage and applying it to the armature winding;
Current detecting means for detecting the actual current over a predetermined time required for detection and making it an actually measured current;
Angular velocity detection means for detecting the angular velocity at which the rotor of the motor rotates;
Based on the measured current and taking into account the command voltage and the angular velocity, an actual current before the detection required time is estimated from the end of detection of the measured current, and the estimated actual current is used as the feedback current An estimated observer,
A motor control device comprising:   2. The motor according to claim 1, wherein the motor is a three-phase synchronous motor having a magnet in the rotor and the armature winding in the stator, and the voltage calculation unit and the current estimation observer are magnets of the rotor. The motor control apparatus which performs calculation and estimation using the dq coordinate axis on the basis of the rotation position.   The current estimation observer according to claim 2, wherein the current estimation observer is based on a detection deviation obtained by subtracting the estimated actual current from the measured current, and the resistance, inductance, and induced voltage of the armature winding represented on the dq coordinate axis A motor control device that estimates the constant voltage in consideration of the command voltage and the angular velocity.   4. The current detection unit according to claim 1, wherein the current detection unit includes an AD converter that converts an analog actual current into a digital actual measured current, and the time required for the detection is during a conversion operation of the AD converter. Motor control device including the latch time.   5. The motor control device according to claim 1, wherein the voltage calculation unit performs proportional integral control based on a command deviation obtained by subtracting the feedback current from the command current. 6.

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