Voltage detection method for alternating-current electric tool and alternating-current electric tool

Abstract

A voltage detection method for an alternating-current electric tool comprises the following steps: rectifying a voltage sinusoidal signal input by the voltage input end of the alternating-current electric tool, and obtaining a periodic waveform signal; acquiring a voltage value u corresponding to a sampling moment t of the periodic waveform signal in a preset sampling time period; carrying out linear fitting on the acquired voltage value u to obtain a slope k corresponding to the phase of the voltage sinusoidal signal; when the slope k is equal to a preset value, obtaining a phase phi corresponding to the voltage sinusoidal signal at the moment; and obtaining the phase phi of the voltage sinusoidal signal at any moment in a period T by taking the phase phi as an initial phase phi0. According to the voltage detection method, the initial phase and the phase at any moment in the period can be accurately obtained, the invention further provides the alternating-current electric tool applying the voltage detection method, the alternating-current electric tool can drive the motor to operate more accurately, and the problems of phase change errors, driving failures and the like are avoided.

Description

【Technical field】 [0001] The invention relates to the technical field of electric tools, in particular to a voltage detection method, and also to an AC electric tool. 【Background technique】 [0002] AC power tools are connected to the AC power supply and powered by the AC power supply. In the AC motor control technology, it is usually necessary to obtain the zero-crossing point of the AC voltage sinusoidal signal as the starting point of the periodic voltage sinusoidal signal, and use this starting point as a reference. Get the corresponding phase at any time in the cycle, and the corresponding sine value of the phase. The control module of the AC power tool uses the phase and the sine value of the phase as important parameters for accurately controlling the brushless motor. However, in the existing conventional AC power tools Due to the circuit characteristics in the control circuit, there may be a time difference between the zero-crossing point detected by the control modu...

AI Technical Summary

Problems solved by technology

[0004] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a voltage detection method for AC power tools, which can avoid the problem of inaccurate detection of the zero-crossing point of the voltage sinusoidal signal, and obtain a more accurate relative initial phase, which can Accurate control of motor operation

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