RU2724979C1 - Phase-shifting device - Google Patents

Abstract

FIELD: electrical engineering.SUBSTANCE: claimed technical solution relates to electric drives of synchronous motors made on the basis of self-contained inverters, and can be used in system for suppression of rotor swings of synchronous motors. Disclosed phase-shifting device comprises a reference frequency generator, wherein in order to increase the phase shift variation range, decreasing resolution of phase shift and simplifying the device as a reference frequency generator using a frequency-controlled generator, wherein the phase control signal is transmitted to the control input of the frequency of the reference oscillator.EFFECT: technical result consists in increase of signal phase shift variation range, reduction of phase shift step-likeness, simplification of device.1 cl

Description

The claimed technical solution relates to the field of electrical engineering, namely to electric drives of synchronous motors made on the basis of autonomous inverters, and can be used in a system for suppressing rocking of a rotor of synchronous motors.

Currently, several methods for constructing phase-shifting devices are known:

- the formation of a sawtooth voltage during the period of the phase-shifted signal and comparing it with the control voltage on the comparator. At the moment of equality of these voltages, a phase-shifted signal is generated at the output of the comparator ("Controlled phase shifter", USSR Author's Certificate No. 1195419, class IPC Н03Н 11/20, priority date 10/28/1983) [1];

- the formation of a pulse during the transition through zero phase-shifted signal and the start of this pulse generator. When the number of pulses from the output of the generator is equal to the specified number, a phase-shifted output signal is generated ("Digital Phase Shift Device", USSR Author's Certificate No. 868622, IPC class G01R 25/04, priority date 01/03/1980) [2].

The aforementioned phase-shifting devices [1,2], as well as most other known devices have a phase shift range of not more than (0-360) degrees, electrical. For efficient operation of the swing suppression system of a rotor of a synchronous motor, powered by an autonomous inverter with pulse-width modulation, the phase shift range should be several times larger, since the phase-shifting device is turned on in this case before the pulse-width modulator, which operates at a frequency of order is higher than the output frequency of the autonomous inverter, therefore, the phase range of the output voltage of the autonomous inverter is an order of magnitude smaller than the output of the phase-shifting device.

The closest in technical essence to the claimed technical solution and therefore adopted as a prototype is the device shown in the USSR Author's Certificate No. 1337818 "Method for discrete phase shift and device for its implementation" class. IPC G01R 25/04, priority date 03/31/1987 [3]. The magnitude of the phase shift of the signal in this device is defined as the product of the change in the signal frequency by the duration of the time interval during which the signal frequency is changed.

This device for setting the phase shift contains a reference generator, the output of which is connected to a block of reference frequencies, a programmable counter connected to a frequency synthesizer through a series of logic circuits. The frequency shift in this device is set by the difference of the reference frequencies, is a constant value and determines the discreteness of the phase change at the output of the frequency synthesizer. The duration of the time interval during which the frequency synthesizer operates at a changed frequency is set by a programmable counter.

The disadvantages of this device include the presence of discreteness of the phase angle and the complexity of the device.

The objectives of the proposed technical solution are to increase the range of the phase shift of the signal, reduce the phase shift, simplify the device. These tasks are solved due to the fact that in the inventive phase-shifting device containing a reference frequency generator, a frequency controlled oscillator is used, and the phase shift control signal is supplied to the frequency control input of the reference generator.

The magnitude of the phase shift in the inventive phase-shifting device is determined in the same way as in [3]. When changing the frequency of the reference oscillator and the duration of the time interval during which the reference oscillator operates at a changed frequency, in the inventive phase-shifting device, a phase shift can be obtained more than 360 ⁰ : ∆φ = 360 ⁰ ∆f∆t.

In the prototype, the frequency shift of the signal occurs abruptly and is a constant value, which creates discreteness

phase changes, and in the inventive phase shifting device with a smooth change in the magnitude of the phase control signal, the frequency shift gradually increases from zero to a predetermined value, as a result of which the discreteness of the phase change is practically zero. The time interval of operation of the reference oscillator at a changed frequency is determined by the duration of the phase control signal and is equal to the time interval for establishing a new phase value. With an increase in the frequency of the reference generator, the phase shift at the output of the phase-shifting device decreases, and with a decrease in the frequency of the reference generator, it increases. The linearity of the dependence of the phase shift on the magnitude of the phase control signal is determined by the linearity of the dependence of the frequency of the reference oscillator on the magnitude of the frequency control signal of this generator.

The use of the inventive phase-shifting device in an autonomous inverter with pulse-width modulation provides effective suppression of the swing of the rotor of the synchronous motor connected to the output of this autonomous inverter.

The inventive phase-shifting has the following advantages compared with analogues and prototype:

- a large range of phase changes;

- small discreteness of phase change;

- simplicity of the device.

Sources of information

1. USSR author's certificate No. 1195419, cl. IPC Н03Н 11/20, priority date 10/28/1983;

2. Copyright certificate of the USSR No. 868622, cl. IPC G01R 25/04, priority date 01/03/1980;

3. Copyright certificate of the USSR No. 1337818, cl. IPC G01R 25/04, priority date 03/31/1987

Claims (1)

A phase-shifting device comprising a reference frequency generator, characterized in that in order to increase the phase shift range, reduce the phase shift discreteness and simplify the device, a frequency-controlled oscillator is used as the reference frequency generator, the phase control signal being supplied to the frequency control input to the reference generator .