Current control method and motor control circuit

A motor control circuit for controlling a motor to operate, the motor control circuit comprising:

• a power supply, comprising a live wire and a natural wire;
• a first rectification circuit and a second rectification circuit, connected in parallel between the live wire of the power supply and the natural wire of the power supply, and configured to rectify the power supply;
• a driving circuit, wherein an output end of the first rectification circuit is connected to the motor through the driving circuit;
• a sampling resistor, connected to the driving circuit;
• and
• a controller, connected to an output end of the second rectification circuit through a voltage detection circuit, wherein the controller is configured to:
• obtain a periodic waveform signal of a bus voltage;
• collect a bus current value through the sampling resistor;
• sample the periodic waveform signal for a plurality of times;
• linearly fit a plurality of voltage values obtained at a plurality of sampling time points t to obtain a plurality of slopes;
• obtain a power frequency f according to the plurality of slopes;
• calculate a compensation current value according to the power frequency;
• and
• generate a control signal according to the compensation current value and the bus current value to control the motor.

A motor control circuit for controlling a brushless motor, the motor control circuit comprising:

• a power supply, comprising a live wire and a natural wire;
• a first rectification circuit, connected in parallel between the live wire of the power supply and the natural wire of the power supply, configured to rectify the power supply, and comprising an output end connected to a driving circuit through a capacitor connected in parallel to the driving circuit, wherein the driving circuit is further connected to the brushless motor, and the capacitor has an equivalent capacitance value of less than 15uF;
• a second rectification circuit, connected in parallel between the live wire of the power supply and the natural wire of the power supply, and configured to rectify the power supply;
• a sampling resistor, connected to the driving circuit;
• and
• a controller, connected to an output end of the second rectification circuit through a voltage detection circuit, and configured to:
• obtain a periodic waveform signal of a bus voltage;
• collect a bus current value through a sampling resistor;
• sample the periodic waveform signal for a plurality of times;
• linearly fit a plurality of voltage values obtained at a plurality of sampling time points to obtain a plurality of slopes;
• obtain a power frequency according to the plurality of slopes;
• calculate a compensation current value according to the power frequency;
• and
• generate a control signal according to the compensation current value and the bus current value to control the brushless motor.