JPS62210884A - Speed control unit for three-phase synchronous motor - Google Patents

Abstract

PURPOSE:To obtain a control unit superb in high responsibility with less torque ripple, by operationally outputting the armature winding impressed voltage so that the armature current will agree with the command value by an equivalent circuit of an armature winding. CONSTITUTION:In an inductance potential drop prediction circuit 12, a voltage drop due to the armature winding inductance is predicted by multiplying a rate of change of current by an inductance value of an armature winding. In DC resistance potential drop prediction circuit 13 a voltage drop due to the resistance of an armature winding is predicted. In inducing a voltage prediction circuit 14 the inducing voltage in an armature winding is predicted. A two-phase command circuit 15 adds output signals of each prediction circuit 12, 13 and 14 and strikes a two-phase voltage command signal, which is then turned into a three-phase voltage command signal by a two-phase-to-three-phase conversion circuit 16. By amplifying this signal by an amplification circuit 5 a three-phase synchronous motor 7 is driven.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a speed control device for a three-phase synchronous motor such as a brushless motor.

[Conventional technology]

A brushless motor is similar to a general permanent magnet type synchronous machine, and is composed of a fixed armature and a rotating magnet field.

A permanent magnet is used for the field. In a brushless motor, the positions of the armature and magnet field are reversed on the inside and outside of a typical magnet-field stone flow servomotor, and the rectifying mechanism using the brushes and commutator is connected to the rotor position detection mechanism and semiconductors. It was replaced by a switch.

The torque generation principle of a brushless motor will be explained below.

The torque of a brushless motor is similar to that of a DC motor, so that the armature magnetomotive force and the rotor magnetic flux always maintain an orthogonal relationship.
The magnetic flux of the rotor can be indirectly observed from the induced voltage waveform of the armature winding according to Faraday's law and Lenz's law.
By determining the reference position of the rotor position detection mechanism described above in accordance with the induced voltage waveform, the armature magnetomotive force direction to be taken can be determined. The armature windings of brushless motors are usually three-phase balanced windings, so as the rotor rotates, each armature winding has a displacement angle (electrical angle) from the rotor's reference position. Induced voltages with a phase shift of 120 degrees are generated. The motor magnetic circuit is designed so that the magnetic flux crossing the armature conductors of each phase is distributed in a sinusoidal manner in the circumferential direction. That is, the magnetic flux density of each phase is Bu # BY t BW
If the maximum value of magnetic flux density is Bm and the displacement angle of the rotor is θ, then Bu=Bm−out(θr)−−(1)BY
=Brn-1IhI(θr-120') ---
C2) BW=Bm-8hI(θr-240')
−・Auto−・(3). The generated torque T of a brushless motor is the sum of the generated torques of each phase, and according to Fleming's law, is expressed as (where: constant). Here, by making the armature currents I, , Iv, I, of each phase sinusoidal and matching the phase information with the phase of each magnetic flux density, TOC8In2 θ1 +gtn'' (θr −120
') 10g+n'' (θF -2400)=1.5...
(5) Therefore, the generated torque T depends only on the product of the respective maximum values of the armature current and the magnetic flux density, and is unrelated to the displacement angle θ1 of the rotor.

Next, a conventional brushless motor speed control device will be explained with reference to FIG.

A speed command circuit 1 generates a speed command signal corresponding to a predetermined speed command. The speed compensation circuit 2 performs PID compensation calculation on the speed deviation signal obtained from the speed command signal from the speed command circuit 1 and the speed feedback signal from the speed detection circuit 9, and generates a current command signal. The three-phase current command circuit 3 generates three-phase current command signals for three phases of the armature winding based on the current command signal from the speed compensation circuit 2 and the displacement angle signal from the displacement angle detection circuit 8. The current compensation circuit 4 calculates the three-phase current obtained from the three-phase current command signal from the three-phase current command circuit 3 and the current detection signal for the three phases of the armature winding detected by the three-phase current detection circuit 6. A PID compensation calculation is performed on the deviation signal to generate a three-phase voltage command signal. The amplifier circuit 5 amplifies the three-phase voltage command signal from the current compensation circuit 4 and drives the three-phase synchronous motor 1. Further, the displacement angle detection circuit 8 and the speed detection circuit 9 each have a sensor section connected to the rotor shaft of the three-phase synchronous motor 70,
Displacement angle θ1゜ [Problem to be solved by the invention] By the way, in order to prevent the torque l and f of a three-phase synchronous motor, the phase of the armature current must be accurately aligned with the phase of the magnetic flux density, as described above. 5. The phase of the magnetic flux is determined by the rotation angle of the armature, so the change in the phase of the magnetic flux becomes large during high-speed rotation. Therefore, control of the armature current requires high-speed response.

The armature current in conventional devices is controlled by PID control of the current compensation circuit as described above, but the responsiveness is not good enough to sufficiently suppress the torque.
Therefore, a control system with higher performance is desired.

Taking these points into consideration, the present invention has excellent high-speed response and
The purpose of the present invention is to provide a speed control device for a three-phase synchronous motor with low torque/reinol.

[Failure to solve the problem]

In the conventional current control system, the voltage applied to the armature winding (three-phase voltage command signal) was determined by the PID compensation register 9, but in the present invention, the current control system has an equivalent circuit of the armature winding. The voltage drop and induced voltage of the inductance and DC resistance are predicted by the equivalent circuit, and the voltage applied to the armature winding such that the armature current matches the armature current command value is calculated and output. In the present invention, in order to reduce the scale of the armature winding applied voltage calculation circuit, although it is a three-phase synchronous motor, it is configured with two phases including a detector and a control calculation circuit.

FIG. 1 is a diagram showing the configuration of the first invention of the present application, where 1 is a speed command circuit, 2 is a speed compensation circuit, 1 is a two-phase current command circuit, 12 is an inductance voltage drop prediction circuit, and 13 is a DC resistance. Voltage drop prediction circuit, 14, induced voltage prediction circuit, 15
16 is a two-phase voltage command circuit, 16 is a two-phase three-phase conversion circuit, 5 is an amplifier circuit, 17 is a two-phase current detection circuit, 7 is a three-phase synchronous motor, 18 is a two-phase displacement angle detection circuit, and 9 is a speed detection circuit. It is. The sensor sections of the two-phase displacement angle detection circuit 18 and the speed detection circuit 9 are both coupled to and driven by the rotor shaft of the three-phase synchronous motor 7.

A speed command circuit 1 generates a speed command signal corresponding to a predetermined speed command.

The speed compensation circuit 2 performs PID compensation calculation on the speed deviation signal obtained from the speed command signal and the speed feedback signal from the speed detection circuit 9 to generate a current command signal. The two-phase current command circuit 11 generates a two-phase current command signal based on the current command signal and the two-phase rotation angle signal from the two-phase displacement angle detection circuit 18.

The inductance voltage drop prediction circuit 12 calculates the two-phase voltage drop value due to the armature winding inductance from the two-phase current command signal, the two-phase current feedback signal from the two-phase current detection circuit 17, and the armature winding two-phase inductance value. Predict. The DC resistance voltage drop prediction circuit 13 predicts the two-phase voltage drop value due to the DC resistance of the armature winding based on the two-phase current command signal or the two-phase current feedback signal and the DC resistance value of the armature winding. The induced voltage prediction circuit 14td predicts the armature winding two-phase induced voltage value from the two-phase rotation angle signal from the two-phase displacement angle detection circuit 18. The two-phase voltage command circuit 15 receives a two-phase voltage drop signal due to the two-phase inductance of the inductance voltage drop prediction circuit 12, a two-phase voltage drop signal due to the two-phase DC resistance of the DC resistance voltage drop prediction circuit 13, and the induced voltage prediction circuit 14. A two-phase voltage command signal is generated from the two-phase induced voltage signal. The two-phase/three-phase conversion circuit 16 converts the two-phase voltage command signal from the two-phase voltage command circuit 15 into a three-phase voltage command signal. The amplifier circuit 5 amplifies the three-phase voltage command signal from the two-phase/three-phase conversion circuit 16 and drives the three-phase synchronous motor.

Moreover, FIG. 2 is a diagram showing the configuration of the second invention of the present application, and the same parts as in FIG. 1 are given the same reference numerals. Therefore, duplicate explanations will be omitted. A two-phase speed command circuit 21 generates a two-phase speed command signal based on the speed command signal from the speed command circuit 1 and the two-phase rotation angle signal from the two-phase displacement angle detection circuit 18. Differentiating circuit 23 differentiates the two-phase rotation angle signal from two-phase displacement angle detection circuit 18 to generate a two-phase velocity feedback signal. The two-phase speed compensation circuit 22 is the two-phase speed command circuit 2.
A p-compensation calculation is performed on the speed deviation signal obtained from the two-phase speed command signal from 1 and the two-phase speed feedback signal from the differentiating circuit 23 to generate a two-phase current command signal. Induced voltage prediction circuit 2
4 predicts the armature winding two-phase induced voltage value from the two-phase speed command signal from the two-phase speed command circuit 21.

[Effect]

In explaining the operation, the theory underlying the present invention will first be explained.

Figure 3 shows the equivalent circuit of the armature winding for one phase of a three-phase synchronous motor. Here, rl is the armature winding DC resistance, L is the armature winding inductance, eu is the induced voltage of the U-phase armature winding, vu is the U-phase armature winding applied voltage,
□ indicates the U-phase armature winding current. Similarly ay
e f3yeVv, VW, I, , 1. are the induced voltages of V phase and W phase, respectively.

The applied voltage is 9 winding current.

The armature winding voltage equation of a three-phase synchronous motor is (however, p
: differential operator).

The induced voltage of each phase is the displacement angle of the rotor, θ.

Let Kffi be the induced voltage constant. That is, the armature current■. , Iy e 1w
In order to flow, it is sufficient to apply armature applied voltages vu, vv, V+ that satisfy equations (6) and (7). In the present invention, in order to reduce the scale of the calculation circuit, the calculation for determining the voltage applied to the armature is performed using a two-phase circuit. (6)
,' Needless to say, in order to perform the three-phase-to-two-phase transformation of equation (7) as defined in FIG. 4, it is sufficient to apply ■ct and ■β to flow the coordinate transformation matrix here.

Here ■α1, 1β0 are two-phase flow command signals, Vα1°V
If β1 is the two-phase voltage command signal and I, , Iβ are the two-phase current feedback signals, then from equations (8) and (11)...
...0'4 Also, since the inductance ring can be approximated as ....alpha.1 (where .DELTA.T: minute time), equation (6) can be expressed as ...a4. That is, once the two-phase current command is known, the optimum two-phase voltage command signals V♂ and Vβ1 to be applied to the armature windings can be determined using equation 04.

Here, the two-phase current feedback signals ■α and ■β are values in two phases and cannot be detected directly, so the three-phase current detection value ■
. , I, , L, Calculated using formula 61.

In other words, the two-phase voltage command signals ■♂ and ■β0 obtained here using the property that the sum of the three-phase currents is zero are the values for the two phases, and it is necessary to make them three-phase voltage command signals = 17-' This is calculated using the following equation using a two-phase to three-phase conversion matrix.

In the present invention, the inductance voltage drop prediction circuit 12 and the DC resistance voltage drop prediction circuit 13 predict the inductance of the armature winding and the voltage drop of the DC resistance, respectively, and the induced voltage prediction circuit 14 or 24 predicts the voltage drop of the armature winding. Since the induced voltage of is predicted, the armature current matches the armature current command value.

〔Example〕

FIG. 5 shows the configuration of an embodiment of the present invention. The speed command circuit 1 divides the voltage of DC power supplies 101 and 102 using a variable resistor 103, and outputs a speed command signal Vref according to a predetermined speed command. The speed compensation circuit 2 includes an adder 105 that calculates the deviation between the speed command signal Vref and the speed feedback signal dθ from the speed detection circuit 9, and a PID that performs a PID compensation calculation on the deviation 1Q- signal to generate a current command signal. It consists of a computing unit 106. Two-phase current command circuit 11
consists of multipliers 111 and 112 that generate the current command signal and two-phase displacements Iαds and r. The inductance voltage drop prediction circuit 12 receives two-phase electrical command signals ■♂, Iβ
0 and the two-phase current feedback signal Ic from the two-phase current detection circuit 17
Adders 121 and 12 that take the two-phase current deviation from t and Iβ
2, the two-phase current deviation is multiplied by the value of U1, and the armature winding Δ
It consists of multipliers 123 and 124 that output two-phase voltage drop signals due to T inductance. The DC resistance voltage drop prediction circuit 13 multiplies the two-phase current command signal ■♂, ■β1 or the two-phase voltage command signal 塾, ■β by the armature winding DC resistance value rl to calculate the voltage drop due to the armature winding DC resistance. It consists of multipliers 131 and 132 that output phase voltage drop signals. The two-phase induced voltage signals in the armature windings are each multiplied by K1-1ct by induction and output. The two-phase surface pressure command circuit 15 is an adder 151
, 152, 153, and 154, and adds the output signal of the inductance voltage drop prediction circuit 12, the output signal of the DC resistance voltage drop prediction circuit 13, and the output signal of the electromotive voltage prediction circuit 14, and calculates the two-phase voltage. Outputs command signals V♂, V/. The two-phase/three-phase conversion circuit 16 is a multiplier 161.162
, 163, adders 164, 165, and a multiplier 16
1 adds the two-phase voltage command signal and the output of the multiplier 163 to output the three-phase voltage command signal u'', and the adder 165 inverts and adds the outputs of the multiplier 161 and the adder 164 to obtain the three-phase voltage. Outputs the command signal vW*.

That is, the two-phase/three-phase conversion circuit 16 performs the calculation of the above-mentioned 0→formula. The amplifier circuit 5 includes a three-phase amplifier 1
66.167.168, and three-phase voltage command signals vu, ■. , vw are amplified and the three-phase synchronous motor 7 is driven. The two-phase current detection circuit 17 generates a two-phase current feedback signal Ia from the three-phase current feedback signals I, , I, , I, obtained from the current detectors 171, 172, 173 of each phase section.
and Iβ. That is, the adder 114 subtracts 1 from Iv and outputs 2 of the multiplier two-phase current feedback signal to the obtained value.

That is, the calculation of the above-mentioned equation (g) is performed.

The two-phase displacement angle detection circuit 18 uses a two-phase excitation, two-phase output type resolver 181. The oscillation circuit 182 is the ninth clock for generating resolver excitation signals.

generates a signal. 90@Phase difference generation circuit 183 receives the above clock signal and outputs a two-phase signal with a phase of 90 degrees.・1st and bus filters 184 and 185 are bandpass filters with a center frequency π, and remove harmonic components of the two-phase signal to produce a two-phase sine wave vector ωtect11ωt. This two-phase sine wave is amplified by amplifiers 186 and 181,
Energize the primary winding of the resolver. When the primary winding of the resolver 181 is excited, the secondary winding receives a two-phase sine wave signal th (ωt-θ,) which is phase-modulated at a displacement angle θ1.

(2) (ω - θr) is induced.

The multiplier 191 inputs the signal (2) ω and *(ω - θr)
The multiplier 192 multiplies the signal ω and (2)
Multiplication is performed by ('ω is - θr), and an adder 193 adds these multiplication results. In other words, output ωt-ccs
(ωt-or)-oosωt-ghI(ωt-01)=
-01 ... α force is calculated, and the addition result is v' *
19y. Similarly, a multiplier 194 multiplies the signals ω and th (ω is - θr), a multiplier 195 multiplies the signals (2) ω and Add the results. In other words, part ωt−cQ! l (ω - θr) + slnωt-1 + Ir
+ (ω - θr): cos θ1...0 is calculated, and the addition result becomes the cluster θ1.

The multipliers 191 and 198 generate a speed feedback signal using an electronic circuit from the signal of the two-phase displacement angle detection circuit 18, although the obtained two-phase sine wave speed detection circuit 9 is constituted by a speed generator or the like. is also possible.

FIG. 6 shows a circuit configuration for generating the speed feedback signal dθ1 from the signal of the two-phase displacement angle detection circuit 18. In FIG.
Differentiate θr)−am(ω−01) and ω
-1) Fish (ωt-θr)-(ω-Sat L) painting (ω-01
)dθ1 dt dt
generate. In the multiplier 203, the signal (ω-9't') cns (ω is one θr) and the signal (ω
The multiplier 204 multiplies the signals -(ω-W) by (ω=1θ) and -(ωt-θ,). The adder 205 subtracts the output signal of the multiplier 204 from the output signal of the multiplier 203 to generate a (ω--Or-) signal.

The adder 206 subtracts the output of the adder 205 from the ω signal set by the constant setter 207 to generate the d#r (2) signal.

With the above configuration, an applied voltage is applied to the armature winding of the three-phase synchronous motor 7 so that the armature current matches the armature current command value.

Next, a second embodiment of the present invention will be explained based on FIG. 7. In FIG. 7, a two-phase speed command circuit 21, a two-phase speed compensation circuit 22. Induced voltage prediction circuit 24. Except for the differential circuit 23, the other configurations and operations are the same as those shown in FIG. 5, so the two-phase speed command circuit 21, two-phase speed compensation circuit 22. Differentiation circuit 23° induced voltage prediction circuit 24. I will only explain about.

The two-phase speed command circuit 21 consists of multipliers 211 and 212, and converts the speed command signal vref from the speed command circuit 1 and the two-phase rotation signal from the two-phase displacement angle detection circuit 18. Differential circuit 23
consists of differentiators 231 and 232, which differentiate the two-phase rotation angle signals to generate two. The two-phase speed compensation circuit 22 inputs the two-phase speed and generates a two-phase current command signal. That is, the adders 221 and 222 calculate the two-phase velocity deviation signal,
P compensators 223 and 224 generate two-phase current command signals from the two-phase speed deviation signals.

(Here, the reason why the p compensators 223 and 224 are not used as PID compensators is that the two-phase rotation angle information is included in the speed deviation signal, so if the 1.D compensation calculation is performed, the two-phase conditions will collapse. ) The induced voltage prediction circuit 24 multiplies the two-phase speed command circuit 21 and outputs a two-phase induced voltage signal in the armature winding. This is because the speed command signal Vref can be regarded as rotation angle differential signal information.

The above configuration also provides the same effects as the first embodiment described above.

〔Effect of the invention〕

As described above, according to the present invention, in the current control system,
It has an equivalent circuit for the armature winding, and uses that equivalent circuit to calculate and output the voltage applied to the armature winding so that the armature current matches the armature current command value, so current control is easier than with conventional devices. Responsiveness can be improved.

In addition, although it is a three-phase synchronous motor, it is configured with two phases including a detector and a control calculation circuit, so that it is possible to reduce the circuit scale.

C-

[Brief explanation of drawings]

Figure 1 is a professional diagram showing the configuration of the first invention of the present application, Figure 2 is a block diagram showing the configuration of the second invention of the present application, and Figure 3 is a block diagram showing the configuration of the second invention of the present application.
The figure is an equivalent circuit diagram of a three-phase synchronous motor, Figure 4 is a diagram for explaining three-phase to two-phase conversion in the present invention, and Figure 5 is a speed control device for a three-phase synchronous motor according to an embodiment of the present invention. 6 is a block diagram showing the configuration of a speed detection circuit applicable to the same device, and FIG. 7 is a block diagram showing the configuration of a speed control device for a three-phase synchronous motor according to another embodiment of the present invention. 8 are block diagrams showing the configuration of a conventional speed control device for a three-phase synchronous motor. 1...Speed command circuit, 2...Speed compensation circuit, 5...
- Amplifier circuit, 7... Three-phase synchronous motor, 9... Speed detection circuit, 11... Two-phase current command circuit, 12... Inductance voltage drop prediction circuit, 13... DC resistance voltage drop prediction Circuit, 14.24... Induced voltage prediction circuit, 1
5... Two-phase voltage command circuit, 16... Two-phase three-phase conversion circuit, 17... Two-phase current detection circuit, 18... Two-phase displacement angle detection circuit, 21... Two-phase speed command Circuit, 22...
Two-phase speed compensation circuit, 23... Differential circuit.

Claims (2)

[Claims] (1) A speed command circuit that generates a speed command signal corresponding to a predetermined speed command, and a two-phase current that detects the armature winding current of the three-phase synchronous motor to be controlled and generates a two-phase current feedback signal. a detection circuit; a two-phase displacement angle detection circuit that detects the rotation angle of the rotor of the three-phase synchronous motor and generates a sinusoidal two-phase rotation angle signal; and a two-phase displacement angle detection circuit that detects the rotation angular velocity of the rotor and provides speed feedback. a speed detection circuit that generates a signal; a speed compensation circuit that subtracts the speed feedback signal from the speed command signal and performs a PID compensation calculation on the obtained speed deviation signal to generate a single-phase current borrow signal; a two-phase current command circuit that generates a two-phase current command signal by multiplying the single-phase current command signal by the two-phase rotation angle signal; The rate of change of the armature current is predicted by dividing by predetermined control period information, and the rate of change of the armature current is multiplied by the inductance value of the armature winding to calculate the two-phase control due to the inductance of the armature winding. an inductance voltage drop prediction circuit that predicts a voltage drop in the armature winding; A DC resistance voltage drop prediction circuit that predicts a two-phase voltage drop; and a circuit that differentiates the two-phase rotation angle signal and multiplies the differential value by an induced voltage constant value to predict the two-phase induced voltage in the armature winding. an induced voltage prediction circuit; and a two-phase circuit that generates a two-phase voltage command signal by adding an output signal of the inductance voltage drop prediction circuit, an output signal of the DC resistance voltage drop prediction circuit, and an output signal of the induced voltage prediction circuit. A voltage command circuit, a two-phase three-phase conversion circuit that converts the two-phase voltage command signal into a three-phase voltage command signal, and an amplifier circuit that amplifies the three-phase voltage command signal and drives the three-phase synchronous motor. A speed control device for a three-phase synchronous motor, characterized by: (2) A speed command circuit that generates a speed command signal corresponding to a predetermined speed command, and a two-phase current that detects the armature winding current of the three-phase synchronous motor to be controlled and generates a two-phase current feedback signal. a detection circuit; a two-phase displacement angle detection circuit that detects the rotation angle of the rotor of the three-phase synchronous motor and generates a sinusoidal two-phase rotation angle signal; a two-phase speed command circuit that multiplies the two-phase speed command signal to generate a two-phase speed command signal; a differentiation circuit that differentiates the two-phase rotation angle signal to generate a two-phase speed feedback signal; a two-phase speed compensation circuit that performs a p-compensation calculation on a two-phase speed deviation signal obtained by adding and subtracting a speed feedback signal to generate a two-phase current command signal; and a two-phase speed compensation circuit that generates a two-phase current command signal; The rate of change of the armature current is predicted by dividing the difference by predetermined control period information, and the rate of change of the armature current is multiplied by the inductance value of the armature winding. an inductance voltage drop prediction circuit that predicts a two-phase voltage drop; and an inductance voltage drop prediction circuit that predicts a two-phase voltage drop; a DC resistance voltage drop prediction circuit that predicts a two-phase voltage drop; an induced voltage prediction circuit that predicts a two-phase induced voltage in an armature winding by multiplying the two-phase speed command signal by an induced voltage constant value; a two-phase voltage command circuit that adds an output signal of the inductance voltage drop prediction circuit, an output signal of the DC resistance voltage drop prediction circuit, and an output signal of the induced voltage prediction circuit to generate a two-phase voltage command signal; A two-phase three-phase conversion circuit that converts the two-phase voltage command signal into a three-phase voltage command signal, and an amplifier circuit that amplifies the three-phase voltage command signal and drives the three-phase synchronous motor. A speed control device for a three-phase synchronous motor.