The method of enlarging the range of constant torque variable frequency speed regulation by adopting y-shaped winding with tap connection

Abstract

The invention relates to a method for broadening the torque-constant frequency-variable speed regulation scope via a Y type winding with tap connection. Each phase of the Y type three-phase winding into two winding parts, the two winding parts are the same in the number of serial-connected turns and the structure but different in sectional area, the two parts are connected in series, and a tap isled out therebetween. When the motor voltage is increased with frequency to a rated value, a changeover switch switches a PWM power supply to the tap, the winding part of larger area is connected withthe power supply, and the other winding part is disconnected from the power supply. Thus, the number of serial-connected turns of the winding is halved, and the conductive sectional area of the winding is increased. According to change of the number of serial-connected turns after power switching, the modulation degree M of PWM is decreased, the voltage value of each winding phase is halved, equivalently, the motor voltage is doubled in the new winding connection manner, and the torque-constant speed regulation scope is doubled. The motor torque-constant frequency-variable speed regulation scope can be broadened without increase of the power supply voltage and increasing the number of semiconductor switching devices of an inversion circuit.

Description

technical field [0001] The invention relates to the fields of power electronics, DSP technology, motors and electrical appliances, in particular to a method for enlarging the range of constant-torque frequency conversion and speed regulation by adopting Y-shaped windings with tap connections. Background technique [0002] The constant torque speed regulation range of the existing AC motor frequency conversion speed regulation system below the base frequency (50HZ) is strongly restricted by the rated voltage of the motor. When the voltage increases with the speed (or frequency) to the rated voltage U N At this time, the constant torque speed regulation reaches the limit. Although the output frequency can continue to be increased to increase the speed, the torque will decrease with the increase of the speed. ) In the case of constant torque output drive requirements are still maintained. For example, the air resistance suffered by electric vehicles and high-speed trains incre...

AI Technical Summary

Problems solved by technology

Therefore, this method can only improve constant power speed regulation, but cannot expand the range of constant torque speed regulation

In addition, when this method is running at high speed, because half of the windings are vacant, the utilization rate of the windings is reduced, only 50%.

[0009] To sum up, the main disadvantage of the existing method of increasing the rated voltage of the motor is that it increases the pressure on the semiconductor power devices, which must be solved by increasing the number of devices, but this increases the complexity of the system cost and control. Extremely detrimental to operational reliability

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