JPS58201593A - Drive circuit for motor - Google Patents

Abstract

PURPOSE:To alleviate a vibration and beat which feasibly occur in the high speed zone of a motor by decreasing the gain of an error amplifier in the high speed zone of the motor. CONSTITUTION:The output of a 3-phase AC power source 116 is supplied through a rectifier 117, and a transistor inverter 115 to an AC motor 101. A plurality of position compensating circuits are provided in an error amplifier 105 which amplifies the difference between the actual speed and the instruction speed of the motor 101, and a speed detector 106 which detects the fact that the actual speed of the motor reaches the prescribed high speed is provided. When the fact that the motor is rotated at the high speed is detected by the detector 106, the phase compensator having small position compensation value is connected to the amplifier 105.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a motor drive circuit that controls the speed of a motor using a speed feedback loop, and particularly to a motor drive circuit that is capable of reducing mechanical vibrations in the crystal speed range.

To increase the speed of a motor, generally, obtain the deviation between the commanded speed and the actual speed of the motor, amplify it with a current amplifier, and then increase it with a power intensifier. A configuration is used in which power is applied in the evening, and an inverter is included in the power amplifier in the AC mt%-meter.

Thyristors are generally used in such power amplifiers, but thyristors have a gain (gay/
) force) decrease - move towards. As is clear from the diagram of the motor speed and grinding machine vibration (including the motor) shown in FIG. 1, this is advantageous because it serves to reduce the mechanical vibration that increases in the grinding area.

On the other hand, when using a transistor pulse modulation control method, that is, a combination of a pulse adjustment circuit and a transistor inverter, as the Shima force increase f'l, the linearity of the pulse width variable control method is good; Since there is no decrease in gain/gain in the flat area, it is easier to detect machine vibrations in the high-speed rotation range of the motor, and depending on the dynamic frequency and detection method (semi-full-close method, nor-close method), resonance may occur. No J
・The phenomenon of vibration and vibration was occurring.

Therefore, an object of the present invention is to provide a motor drive circuit that reduces vibrations in the high-speed range and enables stable drive! M is available.

Hereinafter, the present invention will be explained in detail by way of examples.

FIG. 2 is a block diagram of an example of a motor drive circuit according to the present invention.

Sure to hit, 101 is a three-phase u4'tWJJ machine, 102 hao -
A pulse generator such as a pulse generator/coder is used to generate first and second pulse trains 1'1, . P, is generated.

Note that a resolver can be used as the pulse generator 102, but in this case, the output wave of the resolver is a sine wave, so a pulsing circuit is required. Reference numeral 105 denotes a frequency-to-voltage conversion unit (b''v conversion), which converts the first and second pulses p1 .
The above-mentioned frequency fn is generated by differentiating P, and the pulse train P
The frequency of v is converted into a voltage value, and a voltage TEA proportional to the actual rotational speed n is output.

104 is the difference between the speed command voltage VCMD commanded from a speed command circuit (not shown) and the actual speed voltage TEA (hereinafter referred to as speed t1
1gl string that calculates the EEL (referred to as 4 luck), 105 is an error amplifier that amplifies the moderate error Ea and outputs the amplitude 1s of armature current, 1o6 is a speed detection circuit and IC that will be described later.
19U, 109V, 109W are each &phase' IIL flow generation circuits, which output three-phase command currents Iu, Iv, and Iw whose amplitudes are limited by the amplitude limiting circuit 105, and INIU, 110V, and 110W, respectively. It is an arithmetic circuit with an IC installed for each phase, and the command current is 1u, f
v, Iw and the actual phase currents t au, t av,
Arithmetic circuit for calculating the current difference between i and w, 112U
, ttzv, 112W c+hfhU phase, vm and W
Current transformer that detects phase currents Iau, Iav, and law, 111[J, 113V, 115W H+t'L(
114i, 1 pulse width modulation circuit, 115 is an F range inverter controlled by the output signal of the pulse width modulation circuit, 116 is a three-phase AC power supply, 117 is a known rectifier circuit that rectifies three-phase AC into DC; diode group 117;
m and a capacitor 117b. As shown in FIG. 5, the pulse width modulation circuit 114 generates a square wave 8TSt4 [[wave generation 1dM 5T8G, ! :, comparison 11
COMU, (X)MV.

It consists of CO anchor, NOT game) N0Tt~NOT, driver DV,~1)V, and inverter INV.
has six power transistors QaNQs and a diode ~D6. Pulse width bar 111 device FWMO each comparator COMU, COMV, C0NW respectively receives sawtooth wave signal f8T8 and three-phase AC signal 1u, 1v, 1w (
Compare the Dg width and iu.

When the quantities v and muW are larger than the value of 8T8, 111 is output, and when they are smaller, %QI is output. Therefore, if we look at the layer for iu, comparison 11 COMU outputs the # passing command iuc shown in Figure 4. iu, ly,
Three-phase current commands iuc, ivc, and iwc that are pulse width modulated according to the amplitude of jw are output. and,
These three-phase current commands iuc, ivc, iwc are not gate ML)T, ~NO'l'l, F lie/(
City/verter movement signal S via v~l, ~l)~'6
(,!, -8-, 'C output 8, inverter 115
is input. These inverter 1 dynamic signals Sq to S-, which are applied to the inverter 115V, are applied to the base VC of the power transistors Q1 to QA, respectively, and turn off/off 181I the power transistors Q*-Qa to supply three signals to the cocoon guiding alarm machine 101. Supply phase 'd flow.

It should be noted that the pulse modulation circuit 114, the output/distorter/verter 115, the three-phase AC storm #116, and the rectifier circuit 117 constitute a power amplifier for the transistor pulse modulation control system.

As shown in FIG.
Phase compensation circuit 105 for audience 1 connected between 5m of people
b and the second phase compensation 1gl path IQ5 connected to the output side of the DC amplifier 7105a via an analog switch SW.
The first and '2nd phase compensation circuits 105b and 105c are composed of the capacitors CI and C2, the resistors [41, R2, and the resistors 1tF].
L1. This is a known proportional-integral circuit consisting of two circuits, but the values of each capacitor and resistor are set so that the phase compensation value of the first phase compensation circuit 105b is smaller than the phase compensation value of the $2 phase compensation circuit 105C. is set, and the second phase N compensation circuit 105
C is used for phase compensation in a high speed range. The speed detection circuit 106 includes a pair of comparators 106a, 106.
Comparator -106a compares the actual speed voltage 1'' with a predetermined magnetic pressure +Vc, and detects that it is high when the motor is rotating in the forward direction, comparator to6
b compares the actual speed-pressure T8A and the predetermined voltage-vO,
When the motor is rotating in reverse, it is detected that the motor is at a high speed.

Next, the operation shown in FIG. 2 will be explained in the case where the speed command increases as soon as 4114111m44101 rotates at a certain speed.

84m! $1111 In order to rotate the machine 101 at the desired rotational speed Vc, a predetermined analog 4dL is applied by 1° to the addition terminal of the arithmetic circuit 104. 1 command voltage VCMI) is input.

On the other hand, since the a84 horizontal grinding shaft 101 is rotating at the actual speed Va (<Vc), the pulse generator 102, FV & converter 10s generates an actual speed °magnetic pressure TSA proportional to the actual speed Va.
is output, and this actual speed voltage T8A is input to the calculation terminal of the calculation circuit 104. Therefore, performance Jl! The circuit 104 calculates a speed gA difference H&, which is the difference between the commanded speed Vc and the actual speed VaO, and manually inputs this to the error amplifier 105.

The error amplifier f05 performs a ratio integral calculation as shown in the following equation.

In addition, the calculation result I$ of equation (1) is the armature current b m v
Corresponds to c. That is, when the load fluctuates or the speed command changes, the speed #l difference E (-Vc-Va) increases, and the armature current amplitude 1 m also increases accordingly. I
As s becomes larger, a larger torque is generated, and this torque brings the actual speed of the electric motor to the commanded speed.

Is the amplitude Is of this current command the phase current generating circuit 1G of each phase?
U, HI9V, l? W4c is manually operated, each JrfM width 1st/C4 sine 1ainθ, 51n(σ-Tg), 5in(θ-repipi) is outputted, and three-phase current commands Iu, Iv, and Iw are output respectively (4).

After that, the three-phase current commands Iu, Iv, and Iw are calculated by -
Actual phase current Iau, Iav at line 110U, 110V, I NEW.

The difference is taken from Iaw, and then the difference is the three-phase AC signal 1u, iv, iw! Current 17 pu 11!
11,115V.

The signal is amplified at 115W and input to the pulse width modulation circuit 114.

As described above, the pulse width modulation circuit 114 compares the amplitudes of the single tooth wave signal 8TS and the three-phase AC signals 1u, iv, and iw, and applies pulse width modulated three-phase current commands to each of the inverter 115. The bases of power transistors Qt-Ql are manually connected, and each of these power transistors Qa-Q
A is controlled on/off to supply three-phase current to the induction motor 101.

Thereafter, similar control is performed and finally the induction motor 101
will rotate at the commanded speed.

Since the actual speed voltage T8A is also input to the speed detection circuit 106, the comparators 106m and 104b compare the actual speed voltage TSA with the reference voltages +Vc and -Vc.

Since the reference voltage is determined in accordance with a predetermined speed, the comparator 106& is TSA>10vc during forward rotation, that is, when the actual speed voltage T8A is positive.

When the actual speed voltage T8A is negative, the comparator 106b outputs a high speed detection output.
In the case of Vc, a high speed detection output is generated. When the switching transistor SW is off, only the first phase compensation circuit 105b is connected to the current amplifier 11Ha, and the phase compensation circuit 105b is connected to the current amplifier 11Ha.
Although the proportional integral of equation (1) is executed with the gain/determined by the phase compensation value of ijm105b, the speed detection circuit 1
When a high speed detection output is generated from 06, the analog switch SW is turned on, and the second phase compensation circuit 105C is also connected to the current amplifier 1osaKm, and the phase compensation circuit 105b whose phase compensation value of the second phase compensation circuit 1150 is 1 is turned on. Since it is larger than the phase compensation value of , it is drawn into the larger phase compensation value, so the proportional integration of equation (1) is performed using the gain determined by the phase compensation value of the second phase compensation circuit 105C. It turns out.

Therefore, before the rotational speed of the motor reaches the high speed range, the gain is 5, which is determined by the phase compensation E of the first phase compensation circuit 105b, and when the rotational speed of the motor reaches the high speed range, the gain is relatively large. The current amplifier 105a executes proportional integration with a relatively small gain determined by the phase compensation value of the second phase compensation circuit 105C.

Therefore, since the gain decreases in the high-speed range, vibrations and undulations can be reduced.

As explained above, according to the present invention, the error amplifier is provided with phase compensation circuits for decimals having different phase compensation values, and is also provided with a speed detection circuit that detects when the actual speed reaches a predetermined high speed. Since the configuration is such that when the speed detection circuit detects a high speed, a phase compensation circuit with a small phase compensation value is connected to the a-difference amplifier, the gain can be reduced in the high speed range of the motor. This has the effect of reducing vibrations and waviness that tend to occur in the high speed range of the motor. Furthermore, the above-mentioned effects can be achieved by adding a simple circuit, and the present invention has an excellent practical effect of being inexpensive and simple to construct.

It should be noted that although the present invention has been explained using four and one embodiments, it is possible to make various modifications in accordance with the spirit of the present invention, and these are not excluded from the scope of the present invention.

[Brief explanation of the drawing]

Zheng 1 is a diagram explaining the solution of the present invention 1i141-, JllZ is a block diagram of an embodiment of the present invention, and 5th
ii1 is an expanded circuit diagram of the configuration shown in FIG. 2, FIG. 4 is an explanatory diagram of the operation of the circuit diagram of FIG. 5, and FIG. In the diagram, 101...AC motor (Massenden 11.104.
...Arithmetic circuit, tOS...error a/1.105b,
105c...Phase compensation circuit, 106...Operation test circuit, 109 Ll, 109V. jO? W...phase current generation circuit, 110L], 110~
', 110W... Arithmetic path, 112Ll, 112V
, 112W...Current number, 114...HULL

Claims (1)

[Claims] A detector that detects the actual speed of the motor, a difference circuit that obtains the difference between the command speed and the actual speed output, a difference amplifier that amplifies the difference between the stop and N roads, and the - difference γ/1v) A transistor pulse l14d cross-control type power amplifier for amplifying the output, and a motor J) drive circuit that drives the motor with an output of -4 m of force, -deviation A phase compensation circuit for the heart fM number with a phase compensation value of A is provided in the A/G, and a speed recovery circuit is provided to detect when the real race has reached the high speed of #9T running. A motor drive tdJliI circuit is configured to be connected to a phase compensation circuit with a large phase compensation value.