JPS607473B2 - Control equipment for commutatorless motors - Google Patents

Description

[Detailed Description of the Invention] Field of Application of the Invention The present invention relates to a firing angle (control advance angle) on the motor side of a frequency converter.
This invention relates to a control device for a non-commutated Viscount motive that makes variable the.

BACKGROUND OF THE INVENTION In general, in a non-commutator motor in which a synchronous motor is driven by a thyristor frequency converter, the control advance angle is switched continuously or stepwise based on the commutation operation of the thyristor.

However, when the control lead angle of the frequency converter or the field current of the synchronous motor is changed, the ratio of the motor torque to armature current (torque coefficient) changes.

When the torque coefficient changes, the response characteristics of the speed control system change, making control unstable and, in extreme cases, uncontrollable.
Furthermore, torque fluctuations occur due to unstable control. OBJECTS OF THE INVENTION The present invention has been made to address the above-mentioned problems, and its purpose is to provide stable control without changing the response characteristics of the speed control system even when the control advance angle is changed. An object of the present invention is to provide a control device for a commutator motor.

Summary of the Invention The present invention is characterized in that a compensation current command signal obtained by multiplying the current command signal output by the speed control circuit by the reciprocal value of the cosine value of the control advance angle is applied to the current control circuit;
The reason is that the torque coefficient is always kept at a constant value.

Embodiment of the Invention FIG. 1 shows an embodiment of the invention.

In Fig. 1, 1 is a first thyristor converter (forward converter) that converts the three-phase AC input lac obtained from a commercial AC power supply into DC, and 2 is a smoother for smoothing the DC output of the forward converter 1. The reactor 3 is a second thyristor converter (inverse converter) that converts the DC output from the forward converter 1 into alternating current, and the daily converter 1, smoothing reactor 2, and inverse converter 3 constitute a frequency converter. do. 4 is a synchronous motor driven by the inverter 3; 5 is a distributor that detects the rotational angular position of the rotor of the synchronous motor 4 and generates a distribution signal; 6 is a speed detector that detects the speed of the synchronous motor 4. , 7 is the speed detector 6
8 is a function generator that outputs two related signals A and B that have a certain functional relationship with respect to the speed detection signal of The quantity is controlled according to the function signal A.

Reference numeral 9 denotes a gate signal amplifier that amplifies the gate signal of the phase shifter 8 and applies it to each thyristor of the inverse converter 3. The gate signal amplifier 9 is used to adjust the control advance angle by the divider 5, phase shifter 8, and gate signal amplifier 9. constitute means.

1. For example, a speed command circuit consisting of a potentiometer,
11 is the speed command signal of the speed command circuit 0 and the speed detector 6
12 is a speed control circuit that outputs a current command signal according to the speed deviation obtained by comparing the speed detection signal of , and 12 is a compensation calculation circuit that outputs a compensation current command signal proportional to the product of the current command signal and the function signal B. The circuit consists of a multiplier.

13 is a current detector for rectifying the AC input of the converter 1 and extracting a current feedback signal proportional to the magnitude thereof; 14 is a current detector for comparing the compensation current command signal of the compensation calculation circuit 12 with the current feedback signal. A current control circuit 15 outputs a phase control signal according to the current deviation, and 15 is an automatic pulse phase shifter that controls the firing phase of the forward converter 1 in accordance with the phase control signal of the current control circuit 14.

Next, its operation will be explained.

Since the operation of the commutatorless motor is well known, a detailed explanation will be omitted, but the forward converter 1 controls the magnitude of the armature current ld of the synchronous motor 4, and the inverse converter 3 controls the frequency.

The control advance angle of the inverse converter 3 is controlled based on the position signal of the distributor 5. The control advance angle is set to zero at low speeds and switched to a constant value at high speeds. The control advance angle is switched continuously or stepwise. When controlling in this manner, the following operations are further performed in the present invention.

The function generator outputs a function signal A (see FIG. 2) which has a certain relationship with the speed detection signal of the speed detector 6.

Since the phase shifter 8 determines the amount of phase shift in accordance with the function signal A, the control advance angle y of the inverter 3 changes as shown in FIG. 2 in accordance with the speed of the synchronous motor 4. Further, the function generator 7 outputs a function signal B as shown in FIG. 2, which has a functional relationship with the magnitude of the control advance angle y (this also has a certain functional relationship with the output of the speed detector 6), and compensates. It is added to the arithmetic circuit 12. The compensation calculation circuit 12 outputs a signal (compensation current command signal) D proportional to the product of the current command signal and the signal B. This can be expressed as follows.

lpm戊lp.

XF(y) ...m where lpm is the output signal D1po of the compensation calculation circuit 12 and the speed control circuit 11
The output signal CF(c) of represents the output signal B of the function generator 7, respectively.

Now, F(y) in the output B of the function generator 7 is 1/cos y...{2
), the above m formula becomes as follows.

lpm 戊lpo×1/cos y …{
3} The DC output ld of the forward converter 1 is converted to the output signal D of the compensation calculation circuit 12 according to the operations of the current control circuit 14 and phase shifter 15.
(compensation current command signal).

The torque 7 of the synchronous motor 4 is 7=lpo...
- [4}, and in the end, it is determined only by the output C of the speed control circuit 11, and the torque 7 does not change due to changes in the control advance angle y.

Although the control is performed in this manner, the torque 7 does not change due to a change in the control advance angle y, and the torque 7 changes in proportion to the current command signal output from the speed control circuit 11.

Generally, the output torque 7 of a commutatorless motor can be expressed by the following equation.

Ding=K・lf・ld・cos y
...{5) Here, K is a proportionality constant, lf is the field current of the synchronous motor, ld is the DC output current of the converter 1 (proportional to the current of the synchronous motor 4), and y is the current of the inverter 3. This is the control advance angle.

By the way, as can be seen from equation '5}, when the control advance angle y is changed, the magnitude of the current ld required to generate the same torque also changes accordingly.

For example, when cozy changes in the direction of decreasing, a larger current ld must be passed in order to maintain a predetermined torque. This means that the torque coefficient has become smaller, and the response characteristics of speed control have deteriorated. However, in the present invention, the torque changes in proportion to the current command signal even if the control advance angle y is changed, as shown in equation (2). Since the torque coefficient remains constant even if the control advance angle y is changed, the response characteristics can always be kept constant. FIG. 3 shows a portion of the function generator 7 that outputs the signal A in response to the speed detection signal from the speed detector 6.

In FIG. 3, point a shown in FIG. 2 is adjusted by a potentiometer 1. In FIG.

That is, the voltage at point A shown in FIG. 3 is determined by the sum of the input signal and the voltage of the potentiometer, but while this is a negative voltage, diode 4 is not conductive and no signal is output from multiplier 5. However, when the voltage at point A becomes positive when the voltage at point A becomes positive, diode 4 becomes conductive, and a signal is obtained from multiplier 5 in which the voltage at point A is multiplied by the resistance ratio of resistors 6 and 7. .
Since the voltage at point A changes depending on the input signal, the output of the multiplier 5 changes as shown in FIG. 2c at this time. The slope of this curve can be adjusted by the resistance value of the intensifier 7. Next, when the point b in FIG. 2 is reached, the voltage at the end point in FIG. 3 turns positive in the same manner as described above.

Then, the diode 11 becomes conductive and the signal is transferred to the polarity inverter 1.
2 to the intensifier 5. At this time, the haze pressure at the mouth point is multiplied by the resistance ratio of resistors 6 and 13, and appears at the output of multiplier 5, but because of the polarity inverter 12, the output signal is negative with respect to the input signal. It will have an inclination. however,
Since the output signal of the multiplier 5 changes according to the sum of the output signal of the diode 4 and the output signal of the phase inverter 12, the changes cancel each other out, and at this time, the signal remains constant as shown in FIG. 2d. It becomes a straight line. Note that the resistance at d is resistor 13.
It can be adjusted by Although signal A is generated as described above, signal B can also be extracted using a similar method.

Effects of the Invention As explained above, according to the present invention, even if the motor side firing angle (control advance angle) is changed, the torque coefficient can always be kept at a constant value, so stable control can be performed.

Note that the present invention can be applied to a device that changes not only the control lead angle but also the field current. Furthermore, similar effects can be obtained even if a cycloconverter is used as the frequency converter.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a signal waveform diagram for explaining the operation of Fig. 1, and Fig. 3 is a part of a function generator used in the device shown in Fig. 1. FIG. 1...Forward converter, 2...Smoothing IJ factor, 3...Inverse converter, 4...Synchronous motor, 5...Distributor , 6... Speed detector, 7.
...Function generator, 8...Phase shifter. Younger brother 1 picture Younger brother 2 picture 3

Claims (1)

[Claims] 1. A frequency converter that converts the frequency of alternating current, a synchronous motor driven by the frequency converter, and a speed control circuit that outputs a current command signal according to the deviation between the speed command signal and the actual speed signal of the synchronous motor. , comprising a current control circuit that controls the output current of the frequency converter according to the magnitude of the current command signal, and an adjusting means that changes the firing angle of the frequency converter on the motor side, wherein the synchronous motor function generating means for inputting a speed signal of and outputting a reciprocal value of the cosine value of the firing angle on the motor side; and a compensation current command signal obtained by multiplying the output signal of the function generating means by the current command signal to the current control circuit. A control device for a non-commutator motor, characterized in that the current control circuit controls the output current of the frequency converter based on the compensation current command signal.