Method for suppressing harmonic current of high-power AC motor

Abstract

The present invention discloses a method of restrain the harmonic current of large power AC motor and consists of a DC power supply circuit, a waveform rectification circuit, a power output set circuit, a single chip microprocessor and a two-way controllable silicon moving phase control circuit. In continuous semiwave that follows one by one to supply the AC motor with voltage, different moving phase angle is used for slightly increasing the circuit value of even-numbered resonance wave and to greatly reduce the current of odd-numbered resonance wave. The boundary is to keep the resonance current value within EMC standard; when controlling the two-way controllable silicon moving phase, the phase angel can be moved according to the output power of the motor. Three different phase shifting angles of large, middle and small are adopted and the odd-numbered resonance waveform current value that is produced by restraining the work of motor uses the method of equalizing the medium value of the three phase shifting angles and the needed phase shifting angle. The present invention can make the large power motor to achieve the requirement of resonance waveform current stipulated by the EMC standard by only increasing a small amount of control procedure and with the method of shifting phase and needless of alternating the common motor to achieve the aim of economically employing resources.

Description

technical field [0001] The invention relates to a method for suppressing the harmonic current of a high-power AC motor, in particular to a method for suppressing the harmonic current of an AC motor such as a high-power vacuum cleaner and an electric tool. Background technique [0002] In AC vacuum cleaners and electric tools, the widely used power regulation method is the thyristor phase-shift control method, which is a very classic control method, which has high reliability, low cost and full-scale continuous adjustment of output power, etc. advantage. However, since this method achieves the purpose of adjusting the output power of the motor by adjusting the power supply voltage of the motor through symmetrical chopping of the alternating current, a certain amount of harmonic current will be generated, especially the odd harmonic current. After testing, when the rated power of the motor is less than 1400W, its harmonic current is relatively small and can meet the requireme...

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Problems solved by technology

However, the above methods also have their own deficiencies. For example, the high-power vacuum cleaner governor with the application number "200410069306.9" has a high cost, and the motor manufacturing process is relatively complicated, and when the rated power of the motor is large to more than 1800W, it is necessary to increase the available power. Only the number of silicon controlled silicon and motor taps can meet the requirements of the ECM standard; the methods of several other companies have the problem of unstable output power (motor jitter)

The patent number is "ZL03142104.0", "Low Harmonic AC Motor Controller and Control Method" and the ST company's method is quite obvious when the motor rated power is greater than 1600W. The KURZ company's method is more than 1800W. The jitter is quite obvious, so these three methods will affect the service life of the motor

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