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...

Examples

Embodiment Construction

[0010] After testing the existing traditional symmetrical chopping thyristor phase-shifting circuit, it is found that when the phase-shifting angle is 90 degrees, the harmonic current value is the largest, which seriously exceeds the requirements of EMC standards. If the phase angle is lower, the harmonic current value will be significantly reduced. Therefore, it is assumed that in the three consecutive half-waves with a phase shift angle of 90 degrees, the middle phase shift angle remains unchanged, and the two phase shift angles before and after one increase and the other decrease, and the average power remains unchanged. This should enable The harmonic current value is greatly reduced and the output power of the motor can be stably controlled. After testing, the even-order harmonic current value will increase slightly, while the odd-order harmonic current will be greatly reduced, which shows that this method is effective and feasible.

[0011] As shown in Figure 1, the AC ...

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...

Examples

Embodiment Construction

[0010] After testing the existing traditional symmetrical chopping thyristor phase-shifting circuit, it is found that when the phase-shifting angle is 90 degrees, the harmonic current value is the largest, which seriously exceeds the requirements of EMC standards. If the phase angle is lower, the harmonic current value will be significantly reduced. Therefore, it is assumed that in the three consecutive half-waves with a phase shift angle of 90 degrees, the middle phase shift angle remains unchanged, and the two phase shift angles before and after one increase and the other decrease, and the average power remains unchanged. This should enable The harmonic current value is greatly reduced and the output power of the motor can be stably controlled. After testing, the even-order harmonic current value will increase slightly, while the odd-order harmonic current will be greatly reduced, which shows that this method is effective and feasible.

[0011] As shown in Figure 1, the AC ...

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