Single-phase motor stepless speed regulation circuit and speed regulation method

Abstract

The invention provides a stepless speed regulation circuit and a stepless speed regulation method. A stepless speed regulation circuit for a driving motor comprises a switching circuit, wherein an input end of the switching circuit is used for receiving a one-way pulsation steamed bun wave signal obtained after full-wave rectification of a sine alternating-current electric signal, and a motor is coupled between a first output end and a second output end; the synchronizing signal generating circuit is used for generating a synchronizing signal according to the sinusoidal alternating current signal; and a switch driving circuit which is used for selecting at least one switch in the switch circuit to perform chopping at a second frequency according to the state of the synchronization signal,and is used for forming a sine envelope chopping signal between the first output end and the second output end, wherein an envelope line of the sine envelope chopping signal is synchronous with the waveform of the sine alternating current signal. According to the motor stepless speed regulation circuit and the speed regulation method provided by the invention, the circuit volume is small, the power factor is relatively high, and the efficiency of the motor at a low speed can be greatly improved.

Description

technical field [0001] The invention relates to the field of electronics, in particular to a stepless speed regulation circuit and a speed regulation method for driving a single-phase motor. Background technique [0002] A single-phase motor generally refers to an asynchronous motor powered by a single-phase AC power supply provided by the mains AC. Because the mains power supply is very convenient and economical, and it is used for family life, single-phase motors are not only used in large quantities in production, but also closely related to people's daily life. Especially with the improvement of people's living standards, the amount of single-phase motors used in household appliances such as electric fans is also increasing. The single-phase motor adjusts the speed of the motor through the speed regulating circuit. [0003] The first method of speed regulation for single-phase motors is inductive mechanical switch speed regulation. The speed regulation scheme is realiz...

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Problems solved by technology

[0003] The first method of speed regulation for single-phase motors is inductive mechanical switch speed regulation. The speed regulation scheme is realized by adjusting the inductance mechanical ratio between the auxiliary winding and the main winding by adjusting the size of the inductance connected in series. However, the speed regulation range of this scheme is limited and difficult. Actual low speed start or regulation

[0004] The second speed regulation method of single-phase motor is stepless speed regulation of series reactance, which can realize smooth speed regulation, but the speed regulation range is limited, and the reactance size is large, and the system efficiency is low

However, when the SCR is adjusted at low speed, the waveform is chopped more and deformed greatly, so the power factor (PF) is too low, which does not meet the power supply requirements.

Moreover, the torque ripple is large and the noise is large

[0006] The fourth method is AC chopper speed regulation. This type of speed regulation circuit often requires multiple isolated auxiliary power supplies, and uses a large number of high-voltage components, such as usually requiring 8 high-voltage diodes and 2 high-voltage bidirectional switches, and The high-voltage devices do not share the same ground, so the circuit design is complex, the high-voltage devices and the control unit need to be isolated from each other, and multiple isolated power supplies are required, making it difficult to achieve system integration

But this also increases system cost and introduces additional loss

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