Non feedback type AC frequency conversion apparatus for asynchronous motor

Abstract

The invention relates to an AC frequency conversion speed regulating technique of an asynchronous motor, in particular to an AC frequency converting apparatus of a feedback-free type asynchronous motor. The invention solves the problems that the asynchronous motor has wattles current and loss in the processes of converting frequency and regulating speed, and the prior frequency converting apparatus has higher cost, can not fully balance the wattles power and does not have ideal energy-saving effect. The AC frequency converting apparatus comprises a three phase rectifier bridge, and a three phase inverter bridge which is connected between DC output ends of the three phase rectifier bridge and consists of six thyristors, wherein three main capacitance bridge circuits respectively formed by connecting in serial with two power capacitors are connected between the DC output ends of the three phase rectifier bridge, three midpoints of the three phase inverter bridge lead out three ends respectively as one end of each phase of the three phase AC output, and the three midpoints of the three main capacitance bridge circuits lead out the other ends respectively as the other end of each phase of the three phase AC output. The AC frequency converting apparatus overcomes the significant defect of a series of loss caused by the feedback wattless current in the inverting process, and adopts ordinary thyristors, the power capacitors and a rectifying tube to form a main loop of the apparatus, thereby remarkably reducing the cost.

Description

technical field [0001] The invention relates to an AC frequency conversion speed regulation technology for an asynchronous motor, in particular to an AC frequency conversion device for a non-feedback asynchronous motor. Background technique [0002] The current electrical and electrical transmission technology mainly uses power electronic devices that can be turned off and high-frequency pulse width modulation to control the speed of asynchronous motors with both variable voltage and variable frequency. Under the condition that it adopts relatively expensive power electronic components, configures feedback rectifier and relatively complicated control system, the manufacturing cost of its products is relatively high. For the reactive energy problem of the asynchronous motor itself in the frequency conversion, the current technology mostly uses a feedback rectifier for its feedback. In the case of a large reactive current and its loss in the motor, it can be said that only the...

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Problems solved by technology

[0003] In order to solve the problem of the reactive current and its loss in the frequency conversion and speed regulation of the asynchronous motor, but the existing frequency conversion device is expensive and cannot fully balance the reactive power, so the energy saving effect is not ideal, it provides a non-feedback Type asynchronous motor AC frequency conversion device

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