JPH0753433Y2 - Operation control device for synchronous motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an operation control device for a synchronous motor, and more particularly to an operation control device for preventing rocking of the synchronous motor when rotation stops.

B. Outline of the Invention The present invention is a device for driving a synchronous motor based on a speed command signal and a driving current command signal of a speed command circuit unit formed in an open loop, and in the device, the motor current is supplied for a predetermined period from immediately before the stop of the motor. By strengthening it, the swinging phenomenon when the motor is stopped is reduced.

C. Prior Art FIG. 5 shows an operation control device for a synchronous motor in the prior art. In the figure, 10 is a synchronous motor that is a controlled unit, 20 is a drive circuit unit that drives the synchronous motor 10, and 30 is a drive circuit unit 20.
The reference numeral 40 is a gate circuit section for controlling the gate circuit section, and 40 is a speed instruction circuit section for controlling the gate circuit section 30.

The drive circuit unit 20 includes a converter 21 that is a forward conversion unit and an inverter 22 that is an inverse conversion unit, and the gate circuit unit 30 includes a gate logic 31, a current control circuit 32, a matching circuit 33, and a current detector 34. . Speed command circuit section
Reference numeral 40 is composed of a speed command voltage converter 41 for converting a speed command into a voltage, a voltage / frequency oscillator (VCO) 42, a sine wave generator 43, and a multiplier 44.

According to the operation control device of the synchronous motor of FIG. 5, the gate circuit section 30 is controlled by the open loop circuit means including the speed command circuit section 40, and the gate circuit section 30 controls the drive circuit section 20 based on this. As a result, the synchronous motor 10 is controlled.

That is, the speed command voltage converter 41 converts the speed command signal into a voltage signal, and the voltage / frequency converter 42 converts the voltage signal into a frequency signal. The sine wave generator 43 generates a sine wave signal based on the frequency signal. In the multiplier 44, the sine wave signal is multiplied by the current command signal to obtain the current command value for the peak value of the sine wave signal. In the gate circuit unit 30, the matching circuit 33 determines a deviation value between the current command value and the actual current detection signal of the synchronous motor 10, and based on this deviation value, the current control circuit 32 and the gate logic 31 drive circuit unit 20. It controls the inverter 22 of the synchronous motor 10 as a result.
Operation control.

D. Problems to be Solved by the Invention As shown in FIG. 5, when the synchronous motor 10 is operated and controlled by the open loop circuit means having no speed detection loop, the control characteristic depends only on the speed command. However, when the speed command value is set to zero when stopping the operation of the synchronous motor 10, the control current to the inverter 22 suddenly becomes zero and the output current of the inverter 22 is cut off.
As a result, the rotor of the synchronous motor 10 swings. Therefore, the mechanical system driven by the electric motor also swings, which is not preferable.

The present invention solves the above-mentioned problems of the prior art, and when driving a synchronous motor in an open loop, by increasing the motor current for a predetermined time immediately before the stop, the stop operation is smoothed and oscillated. An object of the present invention is to provide an operation control device that can reduce dynamic phenomena.

E. Means for Solving the Problems In order to achieve the above-mentioned object, the present invention is a driving control for driving a synchronous motor based on a speed command signal and a driving current command signal of a speed command circuit unit formed in an open loop. In the device, operation control is performed by a differentiation circuit that differentiates the speed command signal, and means that adds the output signal of the differentiation circuit and the operation current command signal and increases the electric motor current for a predetermined time from immediately before the stop of the synchronous motor. Configure the device.

F. Action During normal operation, the product of the output of the sine wave generator and the operating current command is the current command. Here, the comparator operates immediately before the stop, and the output of the comparator changes. The change in the output of the comparator is differentiated by the differentiating circuit.
The added value of the differentiated signal and the operating current command is obtained. As a result, the peak value of the current command increases as the output of the differentiating circuit increases, and the output current of the inverter also increases.

G. Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 shows an operation control device for a synchronous motor according to an embodiment of the present invention. In FIG. 1, the same or corresponding parts as those in FIG. 5 are designated by the same reference numerals, and the detailed description thereof will be omitted.

In the present embodiment, the current command compensation circuit section 50 is added to the speed command circuit section 40. That is, the current command compensation circuit section 50 is a comparator which receives the set voltage of the zero speed setting device 51 and the voltage of the speed command voltage converter 41 in order to set the reference voltage corresponding to when the rotation speed of the synchronous motor 10 is zero.
52 and a differentiation circuit 53 that differentiates the output signal of the comparator 52
And an adder 54 that inputs the differential signal of the differentiating circuit 53 and the operating current value command signal and outputs the added value signal to the multiplier 44.
It is composed by.

In the operation control device for a synchronous motor configured as described above, the speed command signal is converted into a voltage signal by the speed command voltage converter 41. This voltage signal is input to the multiplier 44 as a sine wave signal through the voltage / frequency oscillator 42 and the sine wave generator 43. On the other hand, in the current command compensation circuit section 50, the voltage output signal of the speed command voltage converter 41 is input to the comparator 52. The comparator 52 compares this voltage signal with the zero speed setting voltage and outputs a deviation voltage signal to the differentiating circuit 53. The differentiating circuit 53 differentiates the output signal of the comparator and outputs the differentiated signal to the adder 54. The adder 54 adds the differential signal and the operating current command, and inputs the added value to the multiplier 44.

Here, when the operating current command signal rises as shown by the characteristic curve l ₂ in FIG. ₂ and in response to this, when the electric motor accelerates from the stopped state as shown by the characteristic curve l ₁ , the comparator 52 operates. However, the output of the differentiation circuit 53 is set so as not to change at 0 [V] (characteristic curve l ₃ ). In addition, when the synchronous motor 10 is in the steady operation state, the sine wave generator
The product of the output of 43 and the operating current command is the current command.
In other words, the frequency of the current command is the speed command voltage converter 41
Of the operating current command.

Next, immediately before the synchronous motor 10 is stopped (the value determined by the zero speed setting), the comparator 52 operates, and the output of the comparator 52 changes from the high level “H” to the low level “L” (or L → H). Change. The change in the output of the comparator 52 is input to the differentiating circuit 53, and the output of the adder 54 is the sum of the operating current command value and the output of the differentiating circuit 53. As a result, the peak value of the current command increases as the output of the differentiating circuit 53 increases as indicated by the characteristic curves l ₃ and l _4, and the output current of the inverter 22 also increases as indicated by the characteristic curve l _5. To do. In FIG. 2, curves l _4a and l _5a are characteristics of the conventional one. Therefore, the inverter current is added by the output of the differentiating circuit when the motor is stopped, and the torque load angle characteristic of the synchronous motor 10 is as shown in FIG. In FIG. 3, a curve l ₆ is the torque (τ) -load angle (θ) characteristic according to the present invention, and l _6a
Is a characteristic of the conventional one. As shown by the arrow in FIG. 3, the vibration can be reduced from the angle θ ₁ to θ ₂ (θ ₁ <θ ₂ ) by raising the torque-load angle characteristic.

FIG. 4 shows an operation control device according to another embodiment of the present invention, and shows a case where a speed command is given by a pulse train. In this embodiment, the speed command circuit unit 40 is composed of a sine wave generator 43 and a multiplier 44, and the current command compensation circuit unit 50 has a frequency / voltage converter for converting the frequency of the pulse train speed command into a voltage signal. (F / V) 55 is added.

According to the operation control device of FIG. 4, the speed command of the pulse train is converted into a voltage signal by the frequency / voltage converter 55, and the comparator 52
With the above input, the same operation and effect as those of the above-described embodiment can be obtained.

H. Effect of the Invention The present invention is as described above, and when controlling the operation of the synchronous motor in the open loop, by adding a circuit with a simple configuration, the motor current can be supplied for a certain period of time immediately before the stop of the synchronous motor. Since it is strengthened, it is possible to obtain a high-performance and highly reliable operation control device at low cost.

[Brief description of drawings]

FIG. 1 is a block diagram of an operation control device for a synchronous motor according to an embodiment of the present invention, FIGS. 2 and 3 are operation characteristic diagrams, and FIG. 4 is an operation control device for a synchronous motor according to another embodiment of the present invention. FIG. 5 is a block diagram of a conventional synchronous motor operation control device. 10 …… Synchronous motor, 22 …… Inverter, 30 …… Gate circuit part, 31 …… Gate logic, 32 …… Current control circuit, 33
…… Matching circuit, 40 …… Speed command circuit section, 41 …… Speed command voltage converter, 42 …… Voltage frequency oscillator, 43 …… Sine wave generator, 44 …… Multiplier, 50 …… Current command compensation circuit Section, 51 ... Zero speed setting device, 52 ... Comparator, 53 ... Differentiating circuit, 54 ... Adder, 55 ... Frequency-voltage converter.

Claims (1)

[Scope of utility model registration request] 1. An operation control device for operating a synchronous motor based on a speed command signal and a driving current command signal of a speed command circuit section formed in an open loop, and a differentiation circuit for differentiating the speed command signal, and the synchronization. An operation control device for a synchronous motor, comprising means for increasing the electric motor current by adding the output signal of the differentiating circuit to the operating current command signal immediately before the electric motor is stopped.