JP3951075B2 - Method and apparatus for controlling motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for controlling an electric motor driven through an inverter.
[0002]
[Prior art]
As shown in FIG. 8, the conventional motor generates d and q-axis current commands id ^* and iq ^* from the torque command Tref by the current command calculator 1 and is detected by the current detector 10 by the current controller 2. The current value is compared with the current detection values id and iq converted by the current calculator 6 and coordinate-converted, and the current is controlled to flow according to the current command. The output of the current controller 2 is set as voltage commands vd ^* and vq ^*, and the voltage command v ^* and the voltage phase θv are generated by the calculator 3 from this. This is given to the inverter 5 from the PWM calculator 4 to output a voltage to drive the motor 7. The motor speed is detected by the speed detector 8 and the speed is fed back. The speed signal ω is integrated by the integrator 11 to calculate the motor phase (position) θm.
When the motor 7 and the inverter 5 are combined and operated, first, tuning is performed to adjust the parameters of the motor. However, the temperature change during operation causes the temperature change of the magnet in the synchronous motor. Parameter deviation due to a decrease in induced voltage caused by temperature, parameter deviation due to temperature change in induction motors, error in parameters such as induced voltage constant caused by temperature change in sensorless speed control, etc. Has led to a decline.
As an attempt for such parameter correction, for example, there is a “vector control device for induction motor” proposed in Japanese Patent Laid-Open No. 8-9697 in which an induced voltage constant is corrected. In this case, the main purpose is to improve the control accuracy at low speed, but basically, the output voltage is adjusted by correcting the induced voltage constant Φ from the relationship of motor speed = induced voltage component / Φ. Have speed control.
[0003]
[Problems to be solved by the invention]
However, in the above-described conventional example, the torque does not come out according to the torque command value due to the deviation of the parameter such as the resistance value in the induction motor due to the temperature change, and the change in the induced voltage due to the temperature of the magnet in the synchronous motor. Incorrect voltage constants and other parameters cause errors in correct speed estimation and control becomes unstable.However, adjustment of the motor constants performed before operation can prevent parameter deviations due to temperature changes during operation. There was a problem that it was not effective.
In addition, the correction method disclosed in Japanese Patent Laid-Open No. 8-9697 also uses the voltage value to adjust the induced voltage constant so as to increase the speed accuracy, and there is no compensation effect on the essential torque. There was a problem.
SUMMARY OF THE INVENTION Accordingly, the present invention provides a motor control method that enables stable control that can match the torque command and the actual output torque regardless of the motor parameter deviation such as temperature change or inductance. .
[0004]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a control device for an electric motor having a control circuit configured to flow a current for generating a torque corresponding to a predetermined torque command and having means for detecting an output voltage and an output current. From the inverter output power Pinv calculated as Vdet × I × cos θ or Vref × I × cos θ from the voltage command V * or the voltage detection value Vdet, the current detection value and the phase difference θ between the voltage and current, the copper loss of the motor Calculate the motor output power Pout minus I ² × r and iron loss W, and correct the torque command so that the output power command Pref = Tref × ω (mechanical rotation speed) and Pout match. It is a feature.
In calculating the inverter output power Pinv, the inner product vd * × id + vq when the d-axis and q-axis components are vd, id, vq, iq using the voltage command Vref or the voltage detection value Vdet and the current detection value. * Xiq is used to calculate Pinv.
Further, it is characterized in that the induced voltage constant of the motor used for control is corrected with respect to a preset initial value and used based on the ratio Pout / Pref between the power command Pref and the motor output power Pout. Yes.
Further, the correction control for making the power command Pref and the motor output power Pout coincide with each other is based on PI control.
Further, in a motor control device having a control circuit configured to flow a current that generates torque according to a predetermined torque command by vector control, a magnetic axis direction is a d axis and a direction orthogonal to the d axis is a q axis. When the output voltage converted into the rotating coordinate system is vd, vq, the current is id, iq, the induced voltage constant is Φ, the rotational speed of the motor is ωm, and the inductance is Ld, Lq,
Reactive power Q1 = vd × iq−vq × id,
Reactive power Q2 = ωm × Φ × i d -ωm (Ld × id 2 + Lq × iq 2),
The induced voltage constant Φ of Q2 is adjusted so that the reactive powers Q1 and Q2 expressed by the above formulas coincide with each other, and control is performed using the adjusted induced voltage constant Φ ′.
Further, when the electric motor is driven by vector control based on a preset induced voltage constant, a value obtained by multiplying the torque command by the induced voltage constant variation rate K1 = Φ / Φ ′ is used as a new torque command.
Further, in a motor control device having a control circuit that allows a current to generate a torque corresponding to a predetermined torque command to flow, and having means for detecting an output voltage and an output current, the torque command value T ref , Primary winding resistance r, iron loss W, rotation speed ω (mechanical angle conversion) or rotation speed command ω ref (mechanical angle conversion), output voltage V, output current I, and output voltage V and phase angle θ of output current I When
The output power command P ref obtained from T ref × ω or T ref × ω ref ,
Copper loss r of the motor from the inverter output power P inv obtained from V det × I × cos θ using the output voltage V det detected by the voltage detector or V ref × I × cos θ using the output voltage command V ref The torque command is corrected so that the motor output power P out obtained by subtracting I ² and the iron loss W matches.
The effective power Pout is calculated from the voltage command Vref or the voltage detection value Vdet and the current feedback value, and the torque command Tref is compared with the output power command Pref obtained from the mechanical rotational speed ω of the motor. By controlling the torque command Tref so that the electric power Pout matches, the torque command and the actual output torque can be matched regardless of the deviation of the motor parameter due to the temperature change.
Alternatively, when the inverter output power Pinv is obtained, since it is calculated as the inner product of the d-axis and q-axis components vd, vq, id, iq, an accurate output is obtained by calculating the power converted into the dq rotating coordinate system. Power calculation can be performed.
Alternatively, since the initial value of the induced voltage constant Φ of the motor is corrected and used by the ratio Pout / Pref of the power command Pref and the active power Pout, it is reflected in the estimation of the speed estimated value ω of the motor speed estimator in the sensorless control. Thus, it is possible to accurately control the torque command Tref and the output power Pout.
Alternatively, since the control for matching the power command Pref and the active power Pout is performed by PI control, accurate control becomes possible. Alternatively, the reactive power Q1 calculated from the voltage and current of the motor is compared with the reactive power Q2 calculated from the d-axis inductance Ld, the q-axis inductance Lq, the induced voltage constant Φ of the motor and the motor speed, and Q1 and Q2 match. By adjusting the induced voltage constant Φ as described above and adjusting the torque command value Tref according to the change in the induced voltage constant, it becomes possible to perform torque control with little influence of fluctuation of the induced voltage constant, particularly in a synchronous motor, In the case of sensorless control, the control accuracy can be increased by the adjusted induced voltage constant Φ ′.
Alternatively, when the torque command Tref is adjusted by adjusting the induced voltage constant Φ, the adjustment is performed by multiplying the torque command Tref by the induced voltage constant variation rate K1 = Φ / Φ ′. Regardless of the torque command, the torque command and the actual output can be matched.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of a control circuit for an electric motor according to the first embodiment of the present invention.
In FIG. 1, 9 is a voltage detector that detects the output voltage of the inverter 5, and 12 is the same as the current calculator 6 in which the value detected by the voltage detector 9 is converted and coordinate-converted to output voltage detection values vd and vq. This is a voltage calculator. Reference numeral 13 denotes a power calculator which inputs current values id and iq from the current calculator 6, voltage values vd and vq from the voltage calculator 12, and a motor speed ω from the speed detector 8, and a power ratio K1 = Pref / Pout is calculated. A coefficient multiplier 14 corrects the torque command Tref based on the power ratio K1 from the power calculator 13.
In addition, the same code | symbol is attached | subjected to the other same structure as the prior art example shown in FIG. 8, and the overlapping description is abbreviate | omitted.
Next, the operation will be described.
The inverter output is detected by the voltage detector 9, converted by the voltage calculator 12, coordinate conversion is performed, and voltage detection values vd and vq are output. The power calculator 13 inputs the vd and vq, the current values id and iq from the current calculator 6 and the motor speed ω, and calculates the power command Pref and the output power Pout (active power).
The power command Pref inputs the torque command Tref,
Pref = Tref × ω (mechanical angle conversion) (1)
Asking. The motor speed ω (mechanical angle conversion) used in the expression (1) may be used by converting the speed command ωref into a mechanical speed.
The output power Pout is obtained as the value obtained by subtracting the copper loss rI ² and the iron loss W of the motor 7 from the inverter output Pinv = V × Icos θ.
That is, the output power Pout = Vdet × Icos θ−rI ² −W.
In this, I = (id ² + iq ² ) ^1/2
The same applies to Vdet, and the phase difference angle θ between Vdet and I for calculating the power factor cos θ is calculated from vd, vq, id, iq. Further, the copper winding motor winding resistance r and the iron loss W are obtained in advance by another method.
From the power command Pref and the output power Pout thus obtained,
Ratio of two powers K1 = Pref / Pout
The multiplier 14 multiplies the torque command Tref by K1 to create a corrected torque command Tref ′.
The calculation here is performed by unifying and calculating between three lines per phase for each phase. As a result, the power command Pref and the effective power of the output power match. The fact that the powers match means that the torque command Tref and the actual torque match, so that accurate torque control is possible.
[0006]
Next, a second embodiment of the present invention will be described with reference to the drawings.
FIG. 2 is a configuration diagram of a control circuit for an electric motor according to the second embodiment of the present invention.
In the second embodiment shown in FIG. 2, the voltage detector 9 and the voltage calculator 12 are omitted from the first embodiment shown in FIG. 1, and voltage commands vd ^* and vq ^* are used as voltage values. It is what I did. Other configurations are the same as those in FIG.
Next, the operation will be described.
In this case, the power calculator 13 calculates the inverter output power Pinv as the inner product of the voltage and current in the dq coordinate system.
Input the current id, iq, voltage command vd ^* , vq ^* and motor speed ω,
Output power ^{Pout = vd * × id + vq} * × iq -rI 2 -W
Is calculated as In this calculation, instead of the voltage commands vd ^* and vq ^* , vd and vq obtained from the current detection value, or the current commands id ^* and iq ^* may be used instead of the current detection value. Using the output power Pout calculated in this way,
Power ratio K1 = Pref / Pout
The operation after obtaining the torque command Tref is the same as that of the first embodiment of the present invention.
In the second embodiment, since the output power is calculated on the dq rotating coordinate system, the output power can be calculated accurately and quickly.
In addition, although the example of the induction motor was demonstrated so far in FIG.1 and FIG.2, paying attention to the induced voltage constant (PHI) of a parameter in the case of a synchronous motor,
Power ratio K1 = Pref / Pout
Based on the above, efficient control is possible if the induced voltage constant Φ is controlled to be corrected.
[0007]
Next, a third embodiment of the present invention will be described with reference to the drawings.
FIG. 3 is a block diagram of an electric motor control circuit according to the third embodiment of the present invention.
In FIG. 3, 16 is an initial value of the induced voltage constant set value Φ that is set in advance, and 17 is a coefficient multiplier that outputs the induced voltage constant Φ ′ corrected by 1 / K1.
Reference numeral 15 denotes a motor speed estimator (observer) for estimating the motor speed in the case of sensorless control in which the speed detector 8 is omitted. The induced voltage is obtained from the current values id and iq, and the motor speed ω = induced voltage / Φ ′. , To estimate the motor speed. Other configurations are the same as those in FIG.
Next, the operation will be described.
The third embodiment shows a method of correcting the induced voltage constant Φ used in the speed estimation observer 15 in the case of performing sensorless control, and the correction amount K1 = Pref / Pout is the previous execution. In the same manner as in the embodiment, the power calculator 13 calculates the initial value Φ16 and corrects the coefficient multiplier 17 by multiplying the coefficient 1 / K1 (corresponding to 1 / K1 = Pout / Pref) based on K1 from the power calculator 13. Based on the induced voltage constant Φ ′, the observer 15 estimates and outputs a corrected motor speed estimated value ω = induced voltage E / Φ ′.
The subsequent adjustment of the torque command Tref by the power ratio K1 obtained by the power calculator 13 is the same procedure as in the previous embodiment.
[0008]
Next, a fourth embodiment of the present invention will be described with reference to the drawings.
FIG. 4 is a block diagram of an electric motor control circuit according to the fourth embodiment of the present invention.
In FIG. 4, reference numeral 18 denotes a power calculator 13 which outputs the output power Pout from the voltage commands vd ^* , vq ^* , currents id, iq, or current commands id ^* , iq ^* , etc.
Pou = | vq ^* × iq ^* + vd ^* × id ^* −rI−W |
This is an output power calculator that calculates with 19 designates the power command Pref as Pref = | Tref ′ × ω |
, And 20 is a PI controller with a proportional gain P and an integration time constant Ti.
The fourth embodiment shown in FIG. 4 is a circuit corresponding to the power calculator 13 and the coefficient multiplier 14 shown in FIGS. 1 to 3, and the output power Pout calculated by the output power calculator 18 and the power command calculator. The PI controller 20 performs PI control so that the deviation of the power command Pref calculated in 19 is zero, and the torque command Tref and the actual torque are controlled to coincide with each other.
[0009]
Next, a fifth embodiment of the present invention will be described with reference to the drawings.
FIG. 5 is a configuration diagram of a control circuit for an electric motor according to the fifth embodiment of the present invention.
FIG. 6 is a detailed view of the induced voltage constant identifier shown in FIG.
In FIG. 5, reference numeral 30 denotes the motor voltage ωm detected by the motor voltage, current, or the speed detector 8, the induced voltage constant set value Φ, and the inductances Ld and Lq to calculate the reactive powers Q1 and Q2, and the induced voltage constant fluctuation rate. This is an induced voltage identifier for obtaining K1 ′ = Φ / Φ ′. A coefficient multiplier 31 corrects the torque command Tref by K1 ′ obtained by the induced voltage identifier 30 to obtain Tref ′. Since other configurations are the same as those of the previous embodiment, description thereof is omitted.
Next, the operation will be described.
As shown in FIG. 5, the induced voltage constant identifier 30 calculates reactive powers Q1 and Q2 by the following equations 1 and 2 from inputs such as vd ^* , vq ^* , id, iq, and motor speed ωm.
[0010]
Q1 = vd * .times.iq-vq * .times.id (1)
Q2 = ωm × Φ × i d -ωm (Ld × id 2 + Lq × iq 2) ··· (2)
Next, the deviation = Q1-Q2 is obtained, and the induced voltage constant set value Φ is adjusted in a direction to reduce the deviation. The adjusted induced voltage constant set value Φ is set as Φ ′, the induced voltage constant fluctuation rate K1 ′ from the initial state is calculated by K1 ′ = Φ / Φ ′, and the calculation result is added to the torque command Tref as a coefficient multiplier 31. To create a corrected torque command Tref ′. Thus, by correcting the torque command with respect to fluctuations in the induced voltage constant due to temperature changes during operation, torque control that does not affect fluctuations in the induced voltage constant or the like can be realized. FIG. 6 shows the details of the operation circuit of such reactive powers Q1 and Q2. The output voltages vd and vq (FIG. 6 shows an example using vd and vq instead of vd * and vq *. Vd *, vq *, or vd, vq can be used), current id, iq, more reactive power Q1, current id, iq, motor speed ωm, inductance Ld, Lq, induced voltage constant set value A specific example is shown in which the reactive power Q2 is calculated from Φ, and the induced voltage constant Φ is corrected by PI control or the like in the adjustment rule to be Φ ′ so as to reduce the deviation obtained by subtracting Q2 from Q1. The motor speed is basically based on the detected value ωm by the speed detector 8, but a speed command value may be used during sensorless control. The method for adjusting the induced voltage constant Φ ′ is the adjustment rule shown in FIG. 6, and the deviation (deviation = Q1−Q2) is adjusted using a proportional type, an integral type, or a combination thereof. Such a correction method of the torque command Tref ′ based on the induced voltage constant fluctuation rate K1 ′ is particularly effective for controlling the synchronous motor as compared with the correction using the power ratio K1.
[0011]
Next, a sixth embodiment of the present invention will be described with reference to the drawings.
FIG. 7 is a configuration diagram of a control circuit for an electric motor according to the sixth embodiment of the present invention.
The sixth embodiment shown in FIG. 7 is a case of sensorless control with respect to the previous embodiment, and the speed detector 8 is omitted and a motor speed estimator 15 is added.
The torque command correction amount K1 ′ = Φ / Φ ′ is the same as that in the previous embodiment, and the observer 15 estimates the motor speed estimated value (speed command value) ω = induced voltage / Φ ′ as a torque command Tref. Correction is performed.
[0012]
【The invention's effect】
As described above, according to the present invention, the active power Pout is calculated from the voltage command or the detected voltage value and the current feedback value, and the torque command and the power Pref of the output power command obtained from the speed ω are compared. Since the torque command Tref is corrected and controlled so that the actual power and the actual power coincide with each other, the torque command and the actual output torque can be made to coincide with each other regardless of the deviation of the motor parameters such as temperature change and inductance. The reactive power Q1 calculated from the voltage and current of the motor is compared with the reactive power Q2 calculated from the d-axis inductance and the q-axis inductance, the induced voltage constant Φ of the motor and the motor speed, and the two reactive powers match. By adjusting the induced voltage constant Φ so that the induced voltage constant can be corrected by correcting the torque command Tref according to the change in the induced voltage constant, it is possible to correct the deviation of the induced voltage, which has a great influence on the stability of the synchronous motor control. Thus, it is possible to make the torque command and the actual output torque coincide with each other regardless of the deviation of the parameters of the electric motor due to a temperature change or the like, and in particular, stable torque control of the synchronous motor can be realized.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a control circuit for an electric motor according to a first embodiment of the present invention.
FIG. 2 is a configuration diagram of a control circuit for an electric motor according to a second embodiment of the present invention.
FIG. 3 is a configuration diagram of a control circuit for an electric motor according to a third embodiment of the present invention.
FIG. 4 is a configuration diagram of a control circuit for an electric motor according to a fourth embodiment of the present invention.
FIG. 5 is a configuration diagram of a control circuit for an electric motor according to a fifth embodiment of the present invention.
6 is a detailed diagram of the induced voltage constant identifier shown in FIG. 5. FIG.
FIG. 7 is a configuration diagram of a control circuit for an electric motor according to a sixth embodiment of the present invention.
FIG. 8 is a configuration diagram of a control circuit of a conventional electric motor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Current command calculator 2 Current controller 3 V ^* , (theta) v calculator 4 PWM calculator 5 Inverter 6 Current calculator 7 Electric motor 8 Speed detector 9 Voltage detector 10 Current detector 11 Integrator 12 Voltage calculator 13 Power calculation 14, 17, 31 Coefficient multiplier 15 Motor speed estimator 16 Induced voltage constant set value 18 Output power calculator 19 Power command calculator 20 PI controller 30 Induced voltage constant identifier

Claims (7)

In a control method for an electric motor having a control circuit configured to flow a current for generating torque according to a predetermined torque command, and having means for detecting an output voltage and an output current,
Torque command value Tref, motor primary winding resistance r, iron loss W, rotation speed ω (mechanical angle conversion) or rotation speed command ωref (mechanical angle conversion), output voltage V, output current I, output voltage V and output current When the phase angle θ of I is
Output power command Pref obtained from Tref × ω or Tref × ωref,
The copper loss r × I ^{2 of the} motor and iron from the inverter output power Pinv obtained from Vdet × I × cos θ using the output voltage Vdet detected by the voltage detector or Vref × I × cos θ using the output voltage command Vref A method for controlling an electric motor, wherein the torque command is corrected so that the electric motor output power Pout minus the loss W matches. The motor control method according to claim 1,
The voltage command is Vref, the d-axis component is vd *, the q-axis component is vq *, the d-axis component of the voltage detection value is vd, the q-axis component is vq, the d-axis component of the current detection value is id, and the q-axis component is If iq,
Inner product (vd ** id + vq ** iq) or (vd * id + vq * iq)
An inverter output power Pinv is calculated using a motor. In the motor control method according to claim 1 or 2,
Based on the ratio Pout / Pref between the power command Pref and the motor output power Pout, the induced voltage constant of the motor used for the control is corrected with respect to a preset initial value and used. Electric motor control method. In the motor control method according to claim 1 or 2,
A method for controlling an electric motor, wherein PI control is performed so that the electric power command Pref and the electric motor output electric power Pout coincide with each other. In a control method of an electric motor having a control circuit configured to flow a current that generates torque according to a predetermined torque command by vector control,
The output voltage converted into a rotating coordinate system having the magnetic axis direction as the d-axis and the direction orthogonal to the d-axis as the q-axis is vd, vq, the output current is id, iq, the induced voltage constant is Φ, When the rotational speed is ωm and the inductances are Ld and Lq,
Reactive power Q1 = vd × iq−vq × id,
Reactive power Q2 = ωm × Φ × i d -ωm × (Ld × id2 + Lq × iq2),
The induced voltage constant Φ of Q2 is adjusted so that the reactive powers Q1 and Q2 expressed by the following match, and control is performed using the adjusted induced voltage constant Φ ′. In this case, vd and vq are their commands. A method for controlling an electric motor, characterized in that values vd * and vq * may be used. In the motor control method according to claim 5,
When the motor is driven by vector control based on a preset induced voltage constant, a value obtained by multiplying the torque command by the induced voltage constant fluctuation rate K1 = Φ / Φ ′ is used as a new torque command. Method. In a control device for an electric motor having a control circuit configured to flow a current that generates torque according to a predetermined torque command, and having means for detecting an output voltage and an output current,
  Torque command value T ref , Motor primary winding resistance r, iron loss W, rotational speed ω (mechanical angle conversion) or rotational speed command ω ref (Mechanical angle conversion), when the output voltage V, the output current I, and the phase angle θ between the output voltage V and the output current I,
  T ref × ω or T ref × ω ref Output power command P obtained from ref When,
  Output voltage V detected by voltage detector det V using det × I × cos θ or output voltage command V ref V using ref × I × cos Inverter output power P obtained from θ inv To copper loss of motor r × I ² And electric motor output power P minus iron loss W out A control device for an electric motor, wherein the torque command is corrected so as to match.

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