SU1378002A1 - A.c. electric drive - Google Patents

Abstract

The invention relates to electrical engineering. The aim of the invention is to increase reliability by ensuring uniform voltage division on the inverter. The goal is achieved by introducing into the electric drive an alternating current of sensors 19-24 phase currents, each of which is included in one of the phases corresponding to the lean group of stator windings, blocks 25, 26, 27 of the comparison, regulators 28, 29, 30 of current, switches 34-36 analog signals, trigger 37 and clock generator 38. Generator 38 (L 00 00

Description

controls the operation of the trigger 37 with a counting input, the outputs of which are connected to the control inputs of the switches 34-36. As a result, sensors 19-24 are connected alternately with a switching frequency equal to half the frequency of the generator 38, sensors 19–24 are connected, the current in each phase of the stator circuits groups formed by coils 3, 14, 15 and 16, 17, 18 is monitored. Since the like keys of the bridge voltage inverters turn on and off simultaneously, each voltage key currently closed will be equal to half the voltage of the power source. 2 Il.

one

The invention relates to electrical engineering and can be used to control the frequency of rotation of AC motors using static frequency converters based on transistor inverters.

The aim of the invention is to increase reliability by providing uniform voltage division across the inverters.

The drawing shows the scheme of the proposed electric drive.

The AC drive contains two serially connected and connected to the DC busses bridge inverters made of transistor switches, an AC motor with a stator winding divided into two phase groups 13,14,15 and 16,17,18. The windings of each group, connected in a star or delta, are connected to the outputs of both inverters. Through sensors 19-24 phase currents. The inputs of the units 25-27 of the comparison of the regulators 28-30 phase current are connected to the blocks 31-33 setting the phase currents. The outputs of the current sensors of the same phase specified. ; stator winding groups of the electric motor are connected to the corresponding power inputs of switches 34-36 of analog signals, the outputs of which are connected to the second inputs of blocks 25-27 © of regulators 28-30, and the control inputs of switches of analog BSDC signals are connected to the trigger outputs 37 The generator output 38 of the frequency tag is connected to the trigger input 37 and the third

the inputs of the blocks 25-27 comparison regulators 28-30. Outputs of phase current regulators through amplifiers 39-50

power is connected to the control inputs of the transistor switches 1-12 bridge inverters.

The drive works as follows.

To the input of blocks 25-27 of the comparison of the regulators of 28-30 phase currents, besides the reference and feedback signals, a triangular-shaped carrier signal is received from the 38 clock generator

frequencies, i.e. structured pulse-width modulation with sweeping balance is organized. Phase current regulators form a signal for switching transistor switches 1-12 at the points of equality of the input and carrier signals, while the switching frequency of the keys is constant and equal to the frequency of the generator 38. The generator 38 controls the operation of the trigger 37 with a counting input, the outputs of which are connected to the control the inputs of the switches 34-36 analog signals. Thus, the phase current sensors of the winding groups of the electric motor, i.e., are connected to the comparison units of the phase current regulators alternately with a frequency equal to half the frequency of the clock frequency generator. The tracking of the formation of the actual current in each half winding of the electric motor occurs. Since the like keys of both bridge inverters turn on and off simultaneously, the voltage on the inverters and, therefore, on the currently closed transistor switches will be equal to half the voltage of the power source.

The construction of an AC electric drive according to this scheme allows, by reducing the operating voltage of the transistor switches of the frequency converter, to significantly increase the reliability of the electric drive.

Claims (1)

Invention Formula An AC drive containing an electric motor with two groups of phase windings on a stator, a frequency converter made of two series-connected bridge voltage inverters, the output of each of which is connected to a corresponding group of phase windings, about that that, in order to increase reliability by ensuring uniform voltage division on the inverters, current sensors included in each phase are introduced stator winding groups, three comparison units, three current regulators, a clock frequency generator, a trigger and three analog signal switches with two power and control inputs, while the power inputs of each analog signal switch are connected to the current sensors respectively the ctaTopa winding groups, and the switch outputs are connected to the first inputs of the respective comparison blocks, The control inputs of the switches are connected to the trigger outputs, the input of which and the second inputs of the comparison blocks are connected to the output of the clock frequency generator, the third inputs of the comparison blocks are connected to the phase current reference blocks, and their outputs to the inputs of the phase current regulators, respectively, whose outputs connected to the corresponding control inputs of bridge voltage inverters.