Synchronous speed regulating method of reversely speed regulating frequency-converter

Abstract

The invention discloses a synchronous speed regulating method of a reversely speed regulating frequency-converter. A motor stator is connected with the electric supply directly, a rotor is connected with an output of the reversely speed regulating frequency-converter which is of a current mode, the reversely speed regulating frequency-converter can regulate magnitude, phase and frequency of current flow independently without being affected by rotor induced electromotive force. The synchronous speed regulating method has the advantages that motor speed is reverse to output frequency of the speed regulating frequency-converter, and the higher the output frequency of the speed regulating frequency-converter is, the lower the motor speed is; output power of the motor is reverse to output power of the speed regulating frequency-converter, and the higher the motor speed is, the bigger total output power of the motor is, while the lower the output power of the speed regulating transducer is; the motor is operated in a broadly synchronous state which belongs to synchronous motor operating performance.

Description

technical field [0001] The invention relates to a speed regulation method of an AC excitable motor, the output frequency, the speed regulation power and the rotor speed change inversely. Background technique [0002] a) At present, the more advanced AC speed regulation is frequency conversion speed regulation, hereinafter referred to as "conventional frequency conversion speed regulation". Larger than the load, this kind of full-power drive inverter has high cost, large power consumption, and large volume; the voltage level of conventional inverters must be greater than or equal to the rated voltage of the motor, and high-voltage motors require high-voltage inverters, which are required in most operating environments. Installing an isolation transformer has high manufacturing cost, large volume, and low reliability; most conventional inverters do not have PFC function, and the harmonics are relatively large, which is harmful to the power grid; conventional inverters are diff...

AI Technical Summary

Problems solved by technology

[0002] a) At present, the more advanced AC speed regulation is frequency conversion speed regulation, hereinafter referred to as "conventional frequency conversion speed regulation". Larger than the load, this kind of full-power drive inverter has high cost, large power consumption, and large volume; the voltage level of conventional inverters must be greater than or equal to the rated voltage of the motor, and high-voltage motors require high-voltage inverters, which are required in most operating environments. Installing an isolation transformer has high manufacturing cost, large volume, and low reliability; most conventional inverters do not have PFC function, and the harmonics are relatively large, which is harmful to the power grid; conventional inverters are difficult to adjust the internal power factor of the motor and cannot reduce the loss of the motor itself; Conventional frequency converters cannot convert mechanical loads into electrical energy and feed it back to the grid, and can only be consumed through braking resistors, which is a serious waste; conventional frequency converters are difficult to realize electronic brakes; conventional frequency converters are difficult to accurately control the rotor speed

b) At present, there is also a high-voltage rotor frequency converter for speed regulation. The energy flow direction is from the stator to the rotor, and then a part of the rotor energy flows to the rotor frequency converter, and then feeds back from the rotor frequency converter to the power grid, which is controlled by adjusting the current fed back to the power grid Rotor speed, rotor excitation cannot be independently controlled

The speed regulation characteristic is related to the slip rate, the speed regulation range is small (within 70%-95% synchronous speed), the power factor is low, the regulation accuracy is low, because of the energy flow cycle, the efficiency is also low, and the application is relatively small, due to the appearance Similar to the speed regulation method of the present invention, but has no essential connection with the speed regulation method of the present invention

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