JPS6159072B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for preventing accidental reverse rotation of a commutatorless motor.

A non-commutator motor is a DC motor in which mechanical contact parts such as commutators and brushes are removed, the motor is connected to the AC terminal of a bridge-type thyristor converter, and a motor rotational position detector is installed. While determining the relationship between the motor voltage and the thyristor to be electrically connected, the thyristor in the bridge type thyristor conversion device is ignited to supply alternating current power to the motor.

Figure 1 shows an example of a known non-commutator motor speed control system using an indirect frequency converter, where 1 is an AC power supply, 2 is a thyristor converter on the power supply side, 3 is a DC reactor, and 4 is on the motor side. Thyristor converter, 5 is electric motor, 6 is rotational position detector, 7
is a speed detection alternator, 8 is a rectifier, 9 is a speed setting device, 10 is a speed regulator, 11 is a power supply detector,
12 is a current regulator, 13 is a firing angle regulator, 14 is a switching command calculator, and 15 is a pulse distributor.

To explain the operation of the system of FIG. 1 very simply, the deviation between the actual speed value signal obtained through the speed detection generator 7 and the rectifier 8 and the speed set value signal given as a command from the speed setting device 9. The DC supply voltage to the motor side thyristor converter 4 is changed by controlling the firing angle of the power supply side thyristor converter 2 through the speed regulator 10, current regulator 12 and firing angle regulator 13 according to the speed control. There are two series of ignition pulses for the motor-side thyristor converter 4, one for forward rotation torque and one for reverse rotation torque, and the switching command calculator 14 controls the ignition pulses of the motor according to the output voltage polarity of the speed regulator 10. The required torque direction is determined and switching is performed so that one of these two series is applied to the thyristor converter 4 on the motor side.

As shown in Figure 1, detection of the actual speed value of a non-commutated motor is generally performed by an alternator and a rectifier that rectifies its output, and the resulting actual speed value signal is It is a fixed polarity signal that is independent of the direction of rotation. This, combined with the fact that the torque direction during forward braking of the electric motor is the same as the torque direction when driving in reverse, may cause an incorrect reverse rotation accident when braking the electric motor. That is, considering the case where normal rotation drive is shifted to regenerative braking, in this case, the pulse distributor 15 changes the phase of the ignition pulse with respect to the induced voltage during normal rotation of the motor according to the output signal of the switching command calculator 14. However, after the motor stops and the actual speed value becomes zero, the motor stops rotating due to the inertia of the load. Suppose that the electric motor is rotated in the reverse direction and the actual speed increases again. In this state, the required torque direction detected by the switching command calculator 14 is the same as that during regenerative braking, and the electric motor The side thyristor converter 4 is supplied with an ignition pulse with the same phase as the ignition pulse that had been supplied up to that point, whereas the motor induced voltage is reversed during forward rotation and reverse rotation, and the phase is 180°. Because of the difference in angle, the motor-side thyristor converter 4 performs a reverse conversion operation to accelerate the motor 5. More specifically, in this state, the speed set value is zero, but if the motor 5 has a non-zero speed in the reverse direction, the motor 5 responds to the deviation between the absolute value of the speed and the speed set value. The speed regulator 10 generates a signal representing the current target value at its output, and the power supply side thyristor converter 2 performs a forward conversion operation so that the actual current value obtained from the current detector 11 matches the current target value. Conducted electric motor 5
It acts to accelerate the Such acceleration causes the motor to overspeed, and in extreme cases, can cause serious damage to the motor itself and the load.

One of the causes of the above-mentioned erroneous reversal accident is that the actual speed value signal is a signal with a fixed polarity regardless of the rotational direction of the motor, so that the speed control loop becomes a positive feedback loop during reversal. Therefore, in order to prevent such incorrect reversal accidents, it is possible to avoid them by using a DC generator from which an actual speed value signal whose polarity changes depending on the rotation direction is used.
However, this has the disadvantage that the advantage of eliminating the mechanical contact part is lost.

SUMMARY OF THE INVENTION An object of the present invention is to provide a device for preventing erroneous reversal accidents for commutatorless motors, which can eliminate the above-mentioned drawbacks and prevent erroneous reversal accidents with simple means.

Next, the present invention will be explained based on the drawings.

FIG. 2 shows a preferred embodiment of the invention, 1
6 is an actual speed value zero detector, 17 is a speed set value zero detector, and 18 is a firing angle shift command generating device.
Firing angle shift command generation device 18 is AND circuit 1
9. NOT circuit 20 and flip-flop 21
including. Other components shown in FIG. 2 are similar to those shown in FIG. 1 and are designated with the same reference numerals.

The speed actual value zero detector 16 outputs a logic signal of "1" when the speed actual value is determined to be zero, and the speed set value zero detector 17 outputs a logic signal of "1" when the speed set value is determined to be zero. ” outputs the logic signal. Therefore,
The AND circuit 19 outputs a logic signal of "1" only when both the actual speed value and the speed set value are determined to be zero, and the NOT circuit 20 outputs a logic signal of "1" when it is determined that the speed set value is not zero. Outputs a logical signal. Flip-flop 21 is “1” of the AND circuit
It is set by the output signal of , and reset by the "1" output signal of the NOT circuit.

During braking, when the speed of the motor 4 reaches zero with a speed setting value of zero, the flip-flop 21 outputs a logic signal of "1", and this logic signal of "1" is used to adjust the current through the switching command calculator 14. It acts to shift the firing angle of the power supply side thyristor converter 2 so that the power supply side thyristor converter 2 is in an operating state in which power is regenerated to the AC power supply 1. Such a shift of the firing angle is such that the control advance angle, that is, the minimum control angle γ, is such that the power supply side thyristor converter 2 reaches the maximum possible inverse conversion output state.
It is sufficient to phase-shift the firing pulse to min. In a normal operating state where the speed setting value is not zero, the output of the flip-flop 21 is "0", and such a shift to the minimum control advance angle .gamma.min is not performed.
Even when the normal operating state shifts to the regenerative control state with a speed setting value of zero, the flip-flop 21 is not set unless the actual speed value becomes zero, so the regenerative braking operation is not performed while the electric motor 5 is rotating. It is carried out without any problems.

If we consider a case where the motor 5 is rotated in the reverse direction for some reason after it reaches zero speed, the motor induced voltage phase becomes opposite due to the reverse rotation.
The motor side thyristor converter 4 is a pulse distributor 15
The operation changes to the reverse conversion operation without switching the ignition pulse sequence at . On the other hand, the flip-flop 21 is set and outputs a logic signal of "1" when the actual speed value of the motor 5 becomes zero due to regenerative braking. Since the flip-flop 21 is not reset unless the speed setting value becomes a value other than zero, even if the motor 5 is reversed, the firing angle of the power supply side thyristor converter 2 will be determined by the power supply side thyristor converter 2. It remains shifted so that it is in an operating state in which it is regenerated to the AC power supply 1. In this way,
Even though the motor-side thyristor converter 4 is in an inverse conversion operation state and is in an operation state in which it attempts to supply power to the electric motor 5, the power supply-side thyristor converter 2, which is the power source for the converter 4, Since the electric power is not supplied to the converter 4 side but is returned to the power source 1 side, the electric motor is not accelerated. After that, when the speed setting value becomes a value other than zero again, the flip-flop 21 is reset, so the above-mentioned shift of the firing angle for the power supply side thyristor converter 2 is canceled, and the converter 2 returns to forward conversion operation. state and can enter normal operation state.

In FIG. 2, the present invention has been described using an indirect frequency converter, but the present invention can also be applied to a non-commutator rectifier using a direct frequency converter (cycloconverter). The direct frequency conversion device is a device that directly performs AC frequency conversion by combining converter 2 for AC-DC conversion and converter 4 for DC-AC conversion in Fig. 2.
It is exactly the same as in Fig. 2, except that two converters are used, and a control device part is provided that has both the functions of the pulse distributor 15 and the firing angle adjuster 13 in Fig. 2. The present invention is applicable because the components 5-12 and 14 have exactly the same configuration. In this case, if there is no shift in the firing angle, power at the AC power frequency is converted to power at the motor frequency, and if there is a shift in the firing angle, the reverse conversion is performed. All you have to do is do it.

As explained above, the present invention makes use of the advantage of a commutatorless motor that has no mechanical contact parts, and by adding a few extremely simple and inexpensive components, it is possible to reliably prevent erroneous reversal accidents. It has the advantage of being preventable.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a known commutatorless motor speed control system, and FIG. 2 is a diagram showing an embodiment of the present invention. 1: AC power supply, 2: power supply side thyristor converter,
4: Motor side thyristor converter, 5: Electric motor,
6: Rotational position detector, 7: Alternator, 8: Rectifier, 9: Speed setting device, 10: Speed regulator, 11:
Current detector, 12: Current regulator, 13: Firing angle regulator, 14: Switching command calculator, 15: Pulse distributor, 16: Speed actual value zero detector, 17: Speed set value zero detector, 18 : Firing angle shift command generator,
21: Flip flop.

Claims (1)

[Scope of Claims] 1. Electric power is supplied from an AC power supply through a thyristor conversion device whose firing angle is controlled depending on the deviation between a fixed polarity actual speed value signal representing a detected value of the actual speed of the electric motor and a speed setpoint signal. In the non-commutator motor supplied with the following, an actual speed value zero detector, a speed set value zero detector, and the thyristor conversion on the condition that the detected speed actual value becomes zero when the speed set value is zero. An erroneous reversal accident prevention device for a commutatorless motor, characterized in that it is provided with a firing angle shift command generating device that shifts the firing angle so that the device is in an operating state in which power is regenerated to the AC power supply. . 2. In the erroneous reversal accident prevention device according to claim 1, each of the actual speed value zero detector and the speed set value zero detector is set to "1" when the detected value is zero.
The firing angle shift command generating device outputs a logic signal of the speed actual value zero detector and the output signal of the speed set value zero detector as a set input, and outputs a logic signal of the speed set value zero. A device for preventing an erroneous reversal accident of a commutatorless motor, which has a flip-flop whose reset input is a negative signal of an output signal of a detector, and whose firing angle is shifted while the flip-flop is in a set state. 3. In the erroneous reversal accident prevention device according to claim 1, the thyristor conversion device includes a power supply side thyristor converter connected to an AC power source and a motor side thyristor converter that converts its DC output into AC and supplies it to the electric motor. The power supply side thyristor converter is controlled in firing angle according to the deviation between the detected speed actual value and the detected speed set value, and the motor side thyristor converter is configured to control the motor voltage by a motor rotation position detector. A firing pulse series for forward torque or a firing pulse series for reverse torque is supplied according to the required torque direction determined according to the deviation while determining the relationship between the thyristors to conduct with the thyristor, and the shifting of the firing angle is determined by A device for preventing accidental reverse rotation of a non-commutated motor, which is applied to a side thyristor converter. 4. The erroneous reversal accident prevention device for a non-commutator motor, wherein the thyristor conversion device is a cycloconverter in the erroneous reversal accident prevention device as set forth in claim 1.