SU966838A1 - Electric drive - Google Patents

Description

(5k} ELECTRICAL APPLIANCE

.;- one

The invention relates to electrical engineering and can be used in electric drives with a synchronous hysteresis motor.

Known drive containing. hysteresis motor, the main source of alternating current and an additional source of alternating current connected in series with the phase of the motor O. Its disadvantage lies in the fact that a pulsed alternating current source is used, connected in series to the motor power supply circuit from the main source in each half-cycle of the power frequency, which requires an increased energy expenditure on re-excitation.

The closest to the invention to the technical essence is an electric drive with a hysteresis electric motor, comprising a three-phase bridge inverter, a master oscillator, a pulse source and a circuit from

series-connected blocks of frequency, phase, and duration of excitation pulses. By selecting the frequency, amplitude, duration, and phase of the excitation pulses, the power consumption of C23 is reduced.

However, during the operation of a hysteresis electric motor, its power factor changes and the position of the excitation pulse relative to the half-wave of the supply voltage, chosen for one of the operating modes of the electric motor, appears to be non-optimal, which leads to an increase in dynamic disturbances in the electric motor, the occurrence of rotor oscillations, its part excitation and deterioration of the energy characteristics of the electric drive as a whole.

Claims (2)

The purpose of the invention is to improve the energy characteristics of electro3. 9 of a drive with a hysteresis electric motor. The goal is achieved by the fact that an electric drive containing a hysteresis electric motor to which a three-phase bridge inverter connected to a master oscillator is connected, and a pulse source connected to the master oscillator through serially connected sets of phase, duration and frequency of pulses , is supplied with series-connected sensor of power limiting coefficient, included in the power circuit of the inverter, and with a value switch The phase of the overdrive pulses is connected to; 1; 1 is the OUTPUT With the block for setting the phase of the pulsing impulses, and the input with the sensor of the power limiting factor. Figure 1 shows the structural scheme of the drive; FIG. 2 shows the time diagrams of currents 1f. and voltages of Uf, which show the operation of the electric drive. The electric drive contains a hysteresis electric motor 1, to which a three-phase bridge inverter 2 with a power supply .3 connected to a master oscillator is connected, and a pulse source 5. Pulse power supply 5 can be connected to the electric motor 1 directly or via inverter keys 2. The pulse source 5 is connected to the master oscillator via a series-connected phase setting unit 6, block 7 of the duration of the over-. excitation pulses and a block of 8 frequencies of excitation pulses. The electric drive also contains series-connected power factor sensor 9 connected in the power supply circuit 3 of the inverter 2, and a switch 10 for the value of the overdrive pulses phase, connected to the block 6 for specifying the overloading pulses phase. The drive works as follows. It is known that the smallest dynamic disturbances in an electric motor "minimal energy costs for magnetization occur in the case when the pulses are supplied at the times when the instantaneous value of the phase current reaches a maximum. When an electric motor is operating from a three-phase bridge inverter, the phase current reaches its maximum value at a strictly defined time moment do: for Cos of-o 180 el. hail, relative to the half-wave of the supply voltage, with Cos "fn70,53 cLQ 120 el.grad. (FIG. 2) The formation of the parameters of the overdrive pulses is carried out in blocks 8, 7, 6, and the phase setting unit 6 determines the position of the pulse overrun in accordance with the expression where t.j is the pulse duration; o (- time point corresponding to the maximum value of the phase current. The sensor of the limit power factor determines the value of the inequality Cos, 7 0.53 by the presence or absence of reactive current 1 in the inverter power supply circuit. , 53 Cosif f, 0.5J V IP. О and outputs a control signal to the switch 10 of the phase value of the forward pulses, which is discrete. But it changes the time moment ofg respectively:; l for Cos4v, 0.53 180 el. hail, at Conv. 70,53 120. This allows the formation of magnetizing current pulses in Time corresponding to the maximum: the value of the phase of the electric motor in any mode of operation, which leads to an improvement in the energy characteristics of the electric drive as a whole and a reduction of dynamic disturbances in the electric motor. Invention The electric drive is a complex hysteresis electric motor connected to a three-phase bridge inverter connected with the master oscillator, and a pulse source connected to the master oscillator through serially connected