JPS583586A - Torque controller for thyristor motor - Google Patents

Abstract

PURPOSE:To accurately suppress a torque ripple by calculating the generated torque of a motor based on a current command signal and a position signal and varying the current command signal in response to the difference between the actual torque value and the torque command value. CONSTITUTION:The firing angle of a cycloconverter 1 is controlled by a current control circuit having a detector 8, an amplifier 9 and an automatic pulse phase shifter 10 and a phase control circuit having a position detector 11 and an automatic pulse phase shifter 12, thereby operating a motor 2. At this time, a current command signal and a position signal are inputted, a torque calculator 7 for calculating the generated torque of the motor 2 is added to feed back the output to the input of a torque deviation amplifier 6, thereby obtaining the difference from the torque command value and varying the current command signal. Accordingly, even if the actual torque value is employed, the current command signal is controlled in reverse phase to the torque pulsation. Accordingly, even if the operating conditions are varied, the torque ripple can be accurately suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a torque control device that suppresses torque ripple in a thyristor motor.

In a thyristor motor that drives a synchronous motor using a thyristor converter whose output current is in the form of a square wave, torque ripple occurs due to harmonic components of the current.

One way to suppress torque ripple is to make the armature winding multi-phase, but this increases the number of thyristor phases, which increases manufacturing costs, especially in small and medium capacity machines. Furthermore, as a method that does not rely on multiphase, a control method is known in which torque ripple is detected from the motor input, and based on this, the armature current is changed to a phase opposite to the torque ripple to cancel the torque ripple. However, since the current is controlled by feedback control, when trying to obtain a fast response, the system tends to become unstable due to the response delay of the control loop, and it is difficult to suppress torque ripple up to high frequencies.

As a way to improve this point, we first proposed
Methods such as those described in No. 364 are known.

That is, this method detects a signal equal to the frequency of torque ripple based on the position signal of a position detector that detects the rotor position of the motor, and suppresses it by changing the motor current to the opposite phase of the torque ripple accordingly. . However, with this device, there is no problem when the operating conditions such as the magnitude of the armature current and field current are constant, but when the operating conditions change, the armature reaction causes a difference between the signal phase of the position detector and the actual torque ripple. This has the disadvantage that the phases do not match and torque ripple cannot be sufficiently removed.

An object of the present invention is to provide a torque control device for a thyristor motor that can accurately suppress torque ripple even when operating conditions change.

The feature of the present invention is that the torque generated by the motor is determined based on the current command signal and the position signal, and the motor current is changed according to the difference between the actual torque value and the torque command value. .

FIG. 1 shows an embodiment of the present invention.

In Figure 1, 1 is a cycloconverter that outputs alternating current with variable voltage and variable frequency, 2 is a synchronous motor, and 3 is a motor 2.
4 is a speed command circuit, and 5 is a speed deviation amplification device, the output of which becomes a torque command value. 6 is a torque deviation amplifier; 7 is a torque calculation circuit that calculates the torque generated by the motor based on the output signals of the amplifier 6 and the automatic pulse phase shifter 12; and 8 is a torque calculation circuit that detects the AC input current of the cycloconverter 1. 9 is a current deviation amplifier; 10 is a firing angle on the power supply side of the cycloconverter 1 (
automatic pulse phase shifter for controlling the control delay angle), 11
12 is an automatic pulse phase shifter for controlling the firing angle (control advance angle) on the motor side; 13 is an automatic pulse phase shifter 10. for detecting the relative position of the field and the armature; 1
This is a gate output circuit that generates a thyristor gate signal according to the AND of two output signals.

FIG. 2 shows a detailed configuration diagram of the torque calculation circuit 7.

In FIG. 2, reference numeral 14 denotes a current command signal generator which is the output signal of the amplifier 6, and a current calculation circuit 15 which calculates the armature current of the motor based on the output signal of the automatic pulse phase shifter 12.
16 is a magnetic flux calculation circuit, 17° and 18 are multipliers, and 19″ is an adder. A power signal is applied to the amplifier 60 power.

Next, the operation of the present invention will be explained.

The components except for the torque deviation amplification device 6 and the torque calculation circuit 7 are the same as those of a well-known AC type thyristor motor control device. That is, detector 8? A current control circuit consisting of an amplifier 9 and an automatic pulse phase shifter 10 makes the motor current proportional to the output signal (speed deviation) of the amplifier 5 by controlling the firing angle on the power supply side of the cycloconverter 1. control like this. On the other hand, a phase control circuit including a position detector 11 and an automatic pulse phase shifter 12 controls the motor current to a predetermined phase with respect to the induced electromotive force by controlling the firing angle on the motor side of the cycloconverter 1.

In this way, the electric motor 2 is operated at a predetermined power factor, and the torque of the electric motor 2 is controlled according to the speed deviation to perform speed control.

Next, the operations of the torque calculation circuit 7 and the torque deviation amplifier 6 will be explained using the waveform diagram shown in FIG.

The current calculation circuit 14 outputs a current signal iU-iW corresponding to the motor current from the output signals of the automatic/Curus phase shifter 12 and the torque deviation amplifier 6. The relationship is expressed as follows.

io= (a-b) l i-p 1 iv= (c-d) 1i,, 1 1w= (e-f) l 'ap l ---
---tl Here, the signals a-f are signals with a <717 width of 120 degrees as shown in FIG. J
The negative sign appended to d and f indicates that the polarities are reversed and added. Moreover, Il and pl are the absolute values of the output signal (current command signal) of the torque deviation amplifier 6. These operations are performed, for example, in a circuit as shown in FIG. 4, which includes an absolute value circuit 20, analog gates 21-26, and subtracters 27-29. In this way, the signals iU to I shown in FIG.
W is obtained. Furthermore, the calculation shown in the following formula is performed, and i U
-i Convert the three-phase signal of w into two-phase signals ia and iβ.

This conversion is performed to simplify subsequent calculations, and can be performed by well-known orthogonal two-axis conversion.

In addition, 2-phase signal! As is clear from equations (1) and (2), the conversion to α and iβ can also be performed at once using the following equation.

First, in the dq-axis current calculation circuit 15, the following equation is given, where CO5ωt and sinωt are sine wave signals extracted based on the signal of the position detector 11, and the motor 2
It has a phase relationship with the no-load induced electric power eU shown in FIG. The calculation of equation (4) is performed by multipliers 30 to 30 as shown in FIG.
33 and adders/subtractors 34 and 35. The waveforms of the d-axis current 1- and the q-axis current 19 are as shown in the third diagram.

Next, the magnetic flux calculation circuit 16 calculates the d-axis and q-axis magnetic fluxes φd and φ9 according to the following equations.

Here, Tea, T2d, TIq, T2Q
is the time constant of the damper winding of the motor 2, 1, and / is a signal proportional to the field current (converted to the armature side). These calculations can be easily performed using, for example, the operational amplifier A1, resistor R, and capacitor as shown in FIG.

Furthermore, multipliers 17.18 and subtractor 1.9 calculate the following equation to obtain the generated torque τ of electric motor 2.

Calculate.

τ,=φ,−1. -Φ, lid, torque τ obtained by equation (7) (7) (7) (7) (7), the torque actual value is added to the torque deviation increased width.

The torque calculation circuit 7 forms a feedback system,
In addition, the amplifier 6 usually has a high gain. Therefore, the actual torque value of the torque calculation circuit 7 is forced to be proportional to the torque command value which is the output signal of the amplifier 5. As a result, the current command signal 1. As shown in FIG. 3, p is controlled in the opposite phase to the torque pulsation. Therefore, by changing the motor current in proportion to the current command signal IAF, it is possible to suppress pulsations in the generated torque. At this time, since the actual torque value is calculated in consideration of the armature current, field current, and control advance angle, torque ripple can be suppressed with sufficient accuracy regardless of the operating conditions.

As described above, according to the present invention, torque ripple can be suppressed with high accuracy even if operating conditions change.

In the above embodiment, an example was described in which a cycloconverter that directly converts constant frequency alternating current to variable frequency alternating current is used as a thyristor converter. Of course, the present invention can also be applied to a so-called DC type thyristor motor that performs the following, and similar effects can be obtained.

Further, although the case where an analog circuit is used as the control calculation means has been described, it is clear that the present invention can be applied even when digital calculation is used.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing one embodiment of the present invention, a circuit block diagram of a thyristor motor device, and Figs.
A detailed circuit diagram of the circuit elements shown in the figure, and FIG. 3 is a waveform diagram for explaining the operation of the present device. 1...Cycloconverter, 2...Synchronous motor, 3
...Speed detector, 4...Speed command circuit, 5...Speed deviation amplifier, 6...-Torque deviation amplifier, 7...Torque calculation circuit, 8...Current detector , 9... Current deviation amplifier, 10... Automatic pulse phase shifter, 11... Position detector, 12... Automatic pulse phase shifter, 13... Gate output circuit.

Claims (1)

[Claims] 1. A cyrisk converter that outputs a variable voltage variable frequency alternating current, a synchronous motor driven by the converter, a current control means for controlling the output current of the converter according to a current command signal, and the motor a position detector for detecting the relative position of the field and the armature; a phase control means for controlling the firing phase of the cyrisk converter based on the position signal of the position detector; A thyristor comprising: a torque calculation means for calculating the torque generated by the electric motor based on the signal; and a thyristor that changes the current command signal according to the difference between the actual torque value calculated by the torque calculation means and the torque command value. Motor torque control device.