JPS6359722A - Overload protecting circuit for synchronous motor controller - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an overload prevention circuit for a synchronous motor control device, and is for preventing overload of a synchronous motor in the event of a mechanical collision or the like.

(Prior Art) FIG. 3 shows a block diagram of a conventional synchronous motor control device using a power converter. This device is composed of a velocity loop A, a 1ift pole position detection loop B, and a current feedback loop C, as shown in the figure.

The speed loop A includes a first addition circuit 2, a compensation circuit 3, a multiplication circuit 4, a second addition circuit 5, an amplifier circuit 6, a power converter 7, a current transformer 8, a synchronous motor 9, and a speed detector 11. It is configured. The first adding circuit 2 adds a command human power signal (hereinafter referred to as "r speed command signal") 1 inputted from the outside and an output signal from the speed detector 11 fed back and outputs the result. The compensation circuit 3 receives the output signal from the first addition circuit 2 and generates a torque command voltage. The multiplier circuit 4 multiplies the torque command voltage from the compensation circuit 3 by an output signal from a function generator 13, which will be described later, and outputs sinusoidal voltage signals having different amplitudes. Second addition circuit 5
adds the sinusoidal voltage signal from the multiplier circuit 4 and the output signal from the current transformer 8 fed back via the current feedback loop C and outputs the result. The amplifier circuit 6 receives the output signal from the second addition circuit 5, amplifies the deviation between the sine wave voltage signal from the multiplication circuit 4, and the output signal from the current transformer 8, and outputs the amplified signal. The power converter 7 receives the output signal from the amplifier circuit 6, amplifies its power, and outputs it. Current transformer 8 detects and outputs the magnitude of the current supplied from power converter 7 to synchronous motor 9. The speed detector 11 outputs a signal proportional to the rotational speed of the synchronous motor 9, and uses, for example, a tacho generator.

The magnetic pole position detection loop B includes the multiplier circuit 4, the second addition circuit 5, the amplifier circuit 6, the gravity converter 7, the current transformer 8, the synchronous motor 9, the magnetic pole position detector 10, and the counter that constitute the speed loop A. 12 and a function generator 13. The magnetic pole position detector 10 detects and outputs the magnet position of the rotating synchronous motor 9. The counter 12 converts the output signal from the magnetic pole position detector 10 into a pulse signal, counts it, and outputs it. The function generator 13 is the counter 1
Using the count value output from 2 as an address, a sine wave signal corresponding to the address value is generated.

The current feedback loop C is constituted by the second adder circuit 5, the amplifier circuit 6, the power converter 7, and the current transformer 8, which constitute the speed loop A.

Note that the reference numeral 14 in the figure is a comparator, and the comparator outputs a detection signal when it detects that the current value detected by the current transformer 8 has exceeded a certain set value. Reference numeral 15 denotes a time constant circuit, into which the output detection signal of the comparator 14 is input, and this human power is delayed for a certain period of time. 16 is an alarm circuit, which is operated by the time constant circuit 15; These comparator 14, time constant circuit 15, and alarm circuit 16 constitute an alarm control circuit.

In the conventional synchronous motor control device configured as described above, when the speed command signal 1 is input to the first addition circuit 2,
As described above, a torque command voltage is generated in the compensation circuit 3. The synchronous motor 9 starts rotating by outputting the command voltage to the magnetic pole position detection loop B, and the speed detector 11 detects the rotational speed of the motor 9 and outputs it to the first addition circuit 2.

In the first adding circuit 2, the feedback output signal from the speed detector 11 and the speed command No. 43 are added, and as a result, the torque command voltage is outputted to the magnetic pole position detection loop via the compensation circuit 3. is adjusted.

On the other hand, the magnet position detection signal of the rotating synchronous motor 9 detected by the magnetic pole position detector 10 is fed back to the counter 12, and the counter 12 converts the fed-back output signal into a pulse signal and counts it. This count value is input manually to the function generator 13, and the function generator generates a sine wave according to the count value. This sine wave is input to the multiplication circuit 4, where the amplitude of the sine wave signal output to the current feedback loop C is adjusted.

When the synchronous motor 9 accelerates or decelerates, or when a large load is applied to the synchronous motor 9, an excessive current flows through the synchronous motor. When this excessive current exceeds the set value of the comparator 14, the comparator 14 outputs an alarm signal to the time constant circuit 15. After receiving the signal from the comparator 14, the time constant circuit 15 outputs the signal to the alarm circuit 16 after a certain period of time. When the signal from the time constant circuit 15 is input to the alarm circuit 16, the signal from the alarm circuit 16 is sent to the synchronous motor 9.
In order to protect the synchronous motor 9 from overheating, the operation of the synchronous motor 9 is stopped by a system not shown.

[Problem that the invention seeks to solve]

By the way, in the conventional synchronous motor control device configured as described above, the above-mentioned alarm circuit is activated even by an excessive current flowing through the synchronous motor during acceleration/deceleration of the synchronous motor or during heavy cutting. Therefore, there was a problem in that normal operations such as acceleration/deceleration and heavy cutting could not be performed.

This invention was made to solve the above-mentioned problems, and uses the presence or absence of an output signal from a speed detector to distinguish between an overload caused by a mechanical collision and an overload caused by acceleration, deceleration, or heavy cutting. The object of the present invention is to obtain an overload prevention circuit for a synchronous motor control device that makes it possible to operate an alarm control circuit only in the event of a mechanical collision.

[Means for solving problems]

The overload prevention circuit of the synchronous motor control device according to the present invention includes a speed loop that detects the rotational speed of the synchronous motor and controls the current supplied to the synchronous motor by feeding back this detection signal, and a synchronous motor control circuit as described above. and an alarm control circuit that detects the current A[4 supplied to the motor and issues an alarm when the current value exceeds a set value, and the synchronous voltage ! A gate circuit is provided that enables the alarm control circuit to operate only when the III machine is rotating.

(Function) In this invention, when a current with a set value is supplied to the synchronous motor, it is in a state where an alarm can be issued via the gate circuit, and in the event of a mechanical collision, the synchronous motor stops, so the rotation speed detection signal is obtained. This causes the alarm control circuit to operate through the gate circuit.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure is a block diagram of a synchronous motor control device showing one embodiment of the present invention. 6 In FIG. It is something.

Reference numeral 17 denotes an absolute value circuit, which is provided in the speed loop A and converts both positive and negative signals fed back from the speed detector 11 into positive signals. 18 is an inverter circuit which outputs a signal when the output of the absolute value circuit 17 disappears, that is, when the machine stops. A gate circuit 19 supplies the output of the current transformer 8 to the comparator circuit 14 when a signal is output from the inverter circuit 18.

The operation of the synchronous motor control device configured as described above will be explained below.

First, when the speed command signal 1 is input to the first adder circuit 2 constituting the speed loop A, a current flows through the synchronous motor 9, and a magnet position detection signal is output from the magnetic pole position detector 10. Output to counter 12 and function generator 13
A sine wave is output from the synchronous motor 9, and the synchronous motor 9 starts rotating.

The operation up to this point is similar to the conventional one described above.

When the synchronous motor 9 starts rotating as described above, the speed detection signal shown in FIG. 2(a) is outputted from the speed detector 11, and is manually inputted to the absolute value circuit F of the alarm control circuit. The absolute value circuit 17 converts the speed detection signal into a positive value and outputs it as shown in FIG. 2(b). When no signal is output from the absolute value circuit 17, the inverter circuit 18
It outputs an H signal as shown in FIG. As shown in FIG. 2(d), the gate circuit 19 outputs the current feedback signal from the current transformer 8 to the comparator 14 when the signal from the inverter circuit 18 is H, and outputs the current feedback signal from the current transformer 8 to the comparator 14 when the signal from the inverter circuit 18 is L. The output of is not output to the comparator 14. For this reason, this gate circuit 19 is composed of, for example, an analog switch.

The comparator 14 receives a current feedback signal from the gate circuit 19, and when the current feedback signal exceeds the set value of the comparator 14, the time constant circuit 1 outputs an output signal to the time constant circuit 15.
5, the signal from the comparator 14 is output after a certain period of time, and the alarm circuit 16 is operated as described above.

In the above embodiment, the gate circuit 19 is provided before the comparator 14, but the gate circuit 19 may be provided after the comparator 14. In this case, since it is sufficient to pass, for example, an ON signal indicating that the set value has been exceeded from the comparator 14, the gate circuit 1
4 is composed of an AND circuit.

(Effects of the Invention) As described above, according to the present invention, it is detected that the synchronous motor is stopped based on the output signal of the speed detector, that is, the rotation signal of the synchronous motor, and the current flowing through the synchronous motor at this time is The alarm circuit is activated when the set value is exceeded, so even if the current flowing through the synchronous motor becomes excessive during acceleration or deceleration, the alarm circuit will not activate while the synchronous motor is rotating. It doesn't work, like in a mechanical collision.
When an excessive current flows while the synchronous motor is stopped, the alarm circuit is activated, which prevents the alarm circuit from malfunctioning and protects the machine in the event of a mechanical collision.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a synchronous motor control device showing an embodiment of the present invention, and Fig. 2 shows signals of various parts in Fig. 1, where (a) shows a speed detector output signal, (b) is the output signal of the absolute value circuit, (c) is the output signal of the inverter circuit, (a) is the output signal of the gate circuit, and Figure 3 is the conventional synchronous room! FIG. 1 is a block diagram of the I1 aircraft control device. Symbols in the figure: A is a speed loop, B is a magnetic pole position detection loop, C is a current feedback loop, 1 is a command input signal (speed command signal), 3 is a compensation circuit, 4 is a multiplication circuit, 6
is an amplifier circuit, 7 is a power converter, 8 is a current transformer, 9 is a synchronous motor, 12 is a kakunta, 13 is a function generator, 14 is a comparator, 15 is a time constant circuit, 16 is an alarm circuit, 17 is an absolute 18 is an inverter circuit, and 19 is a gate circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (3)

[Claims] (1) Includes a speed loop that detects the rotational speed of the synchronous motor and controls the current supplied to the synchronous motor by feeding back this detection signal, and detects the current value supplied to the synchronous motor as described above. Then, in the overload prevention circuit of the synchronous motor control device, which is equipped with an alarm control circuit that issues an alarm when this current value exceeds a set value, the above-mentioned alarm is controlled only when the above-mentioned synchronous motor has stopped rotating. An overload prevention circuit for a synchronous motor control device, characterized in that it is provided with a gate circuit that enables the circuit to operate. (2) The alarm control circuit includes a comparator and an alarm circuit, and the gate circuit is provided before the comparator and sends the drive current signal of the synchronous motor to the comparator when there is no rotation signal of the synchronous motor. An overload prevention circuit for a synchronous motor control device according to claim 1. (3) A patent claim in which the alarm control circuit includes a comparator and an alarm circuit, and the gate circuit is provided on the output side of the comparator and sends out the output of the comparator when there is no rotation signal from the synchronous motor. An overload prevention circuit for a synchronous motor control device according to item 1.