Energy-saving controller for three-phase alternating-current asynchronous motor and control method of energy-saving controller

The invention discloses an energy-saving controller for a three-phase alternating-current asynchronous motor. The energy-saving controller comprises a minimum system peripheral circuit, a voltage synchronization signal circuit, a tube voltage drop signal detection circuit and a thyristor trigger circuit. The invention further discloses a control method used for controlling the energy-saving controller for the three-phase alternating-current asynchronous motor. The control method comprises the first step of detecting the zero-crossing time of a voltage through voltage synchronization signals, the second step of detecting the zero-crossing time of a current through the tube voltage drop signal detection circuit, the third step of calculating a power factor angle through the minimum system peripheral circuit according to the zero-crossing time difference of the voltage and the current, the fourth step of obtaining a thyristor trigger angle corresponding to the power factor angle through an STM32 in a table look-