Power supply method for asynchronous motor

Abstract

The invention provides a power supply method used for an asynchronous motor which supplies power to the motor by a PWM pulse voltage with the duty cycle changing according to the specific rules. The phase number m of the motor is not less than 3; the PWM pulse voltage supplied to each phase of winding can be provided with unipolarity or bipolarity, with the basic waveform of quasi square-wave. Byadopting the power supply type, the advantages caused by the power supply of quasi square-wave can be remained; furthermore, no-polarity capacitor which is used for generating smooth transition section can be removed without changing other parts of the inverter modules of the quasi square-wave frequency converter; more importantly, after the power supply type is adopted, the inverter module has afunction of voltage regulation, and the voltage regulation function of a DC module which is used for power supply is not required; the complexity of the DC module can be reduced, thus increasing the reliability of the power supply, reducing the volume, reducing the cost and being beneficial to achieving the integration of inverter power and the motor body.

Description

technical field [0001] The invention relates to a power supply method for an asynchronous motor. Background technique [0002] With the continuous development of power electronics technology, frequency conversion speed control system is being used more and more widely in motor speed control due to its remarkable advantages. However, in order to realize frequency conversion speed control, a frequency converter must be equipped. This will inevitably increase the complexity of the whole unit. In some applications, such as coal mines, oil fields and other places that require explosion protection, it is necessary to design a special explosion-proof cabinet for the inverter, which not only increases the volume, but also reduces the reliability of operation. Therefore, at present, in such special occasions, all-in-one machines (that is, the inverter is integrated into the motor body) have been used, which has high requirements for the size and reliability of the inverter. [0003]...

AI Technical Summary

Problems solved by technology

Although this method is simple, when the power is large and the number of motor phases is large, the volume and quantity of capacitors required are large, which leads to the bulky inverter module in the frequency converter; secondly, in order to realize frequency conversion speed, the voltage amplitude of the quasi-square wave (that is, the voltage value of the flat top section) is required to change accordingly with the frequency, and the inverter module of the quasi-square wave inverter does not have the function of voltage regulation, which requires its rectification module must be It has the function of voltage regulation, which leads to an increase in the complexity of the rectifier module

The above two characteristics of the quasi-square wave inverter are not conducive to the realization of the all-in-one machine

Images