SU532164A1 - Device for driving a synchronous motor - Google Patents

Description

one

The invention relates to the field of semiconductor excitation of synchronous machines, in particular, to the excitation devices of synchronous motors having an excitation control unit, and can be used in the electrical industry.

It is known that the pre-accelerated to nasynchronous speed of a vrah synchronous motor has an optimal excitation engagement angle at which the motor receives the maximum nmnul of the synchronizing torque ensuring its synchronization 1.

It is also known a device 2 for driving a synchronous motor, comprising an adjustable converter with a pulse-phase control unit, a discharge resistor with anti-parallel connected thyristors, an excitation control unit with sensitive, timing and switching elements, ensuring the activation of the excitation winding in the corner area differing 60-90 degrees from the optimum. This reduces the pulse of the synchronizing torque, which reduces the reliability of synchronization.

The aim of the invention is to increase the reliability of synchronization.

This is achieved due to the fact that a differentiated

the organ whose input is connected to the discharge resistor, and the output is connected to the input of the sensing organ.

Thanks to the introduction of differentiating

The device performs the supply of excitation in the region of negative inducible current (or its cause to a positive value) and, therefore, ensures the development of a maximum synchronizing torque by the motor, which increases the reliability of synchronization and resynchronization of the engine.

The drawing shows the block diagram of the proposed device.

The device contains a converter 1 with a control unit 2, which is connected to the excitation winding 3 of a synchronous motor. The discharge resistor 4 is connected in parallel with the excitation winding 3 through anti-parallel connected thyristors 5 and 6. The control electrodes of these thyristors are connected to their anodes through zener diodes 7 and 8. The excitation control unit 9 contains differentiating element 10, sensing body 11, timing body 12 , the switching body 13, which is connected to the block-pin 14 of the apparatus, including a synchronous motor.

The device works as follows.

When the synchronous motor is disconnected, the device; a, and, the motor's input, a positive voltage is applied to the input of the switching body 13, under the action of which, from the output of the switching body 13, a signal is removed from the output phase control unit 2 that removes the control pulses with converter 1. When starting a synchronous motor under the action of a voltage induced in the excitation winding 3 through the zener diodes 7 and 8, the thyristors 5 and b turn on, the excitation winding current flows Erez the discharge resistor 4. The voltage to the discharge resistor 4 is fed to the input of the differentiating element 10, which is removed from the output signal, phase-shifted relative to the input voltage to the

the angle is close to, and is applied to the sensing organ 11, which produces a bipolar rectangular signal in accordance with the zero position of the input signal. The clock unit 12 reacts to a positive signal from the output of the sensing organ I, for which the duration of the setpoint / o produces a signal to the input of the switching organ 13, preparing it for the switch. When the polarity of the signal at the output of the sensing organ 11 is changed from positive to negative, an instantaneous switching of the switching organ 13 occurs and a signal is output to the input of the pulsed-phase control unit 2 to turn on the converter 1. In the absence of a signal at the output of the timing organ 12, the switching organ 13 occurs change the polarity of the signal at the output of the sensing organ 11 is greater than the specified value. Two cases of current change in the excitation winding during the start of a synchronous motor are impossible ate

In the first case, during engine acceleration, the half-wave duration of the induced current passes through the set value / o. In this case, the duration of the positive signal at the output of the sensing organ 11 exceeds a predetermined time o and the timing unit 12 provides the input of the switching organ 13 to the input

signal. At the moment of changing the polarity of the output signal of the sensing organ 11, the non-switching organ 13 switches and the pulse-phase control unit 2 is fed to the input of the signal, which ensures that the converter 1 is turned on. setpoint, then the signal at the output of the clock element 12 is absent and the switching of the switching body 13, and therefore, the inclusion of the converter 1 occurs After the change of signal polarity on the floor

the output of the sensing organ 11 with a time delay t.

Thus, the activation of the excitation winding occurs in the region of angles when the magnetic axes of the stator and rotor fields either

coincide, or the axis of the floor of the rotor is slightly ahead of the axis of the floor of the stator. By the time the current rises in the field winding to the steady-state level, a positive sign of the motor torque is obtained, which contributes to an increase in the reliability of motor synchronization.

Claims (2)

1. Petelin D. P., Automatic control of synchronous electric drives “Energy, 1968, p. 45. 2. The patent of England No. 1217564, cl. H 2j, 31.12.70. R