Interface circuit and electrical appliance system comprising the same

An electrical appliance system, comprising:

• at least one Electronically Commutated Motor (ECM);
• and
• a main control circuit board of electrical equipment;
• wherein
• the ECM and the main control circuit board are connected to an AC input power supply;
• the ECM and the main control circuit board are connected to independent grounding wires;
• the main control circuit board is configured to output between 0 and 10 V analog voltage signals to control speed of the ECM;
• the ECM is connected to the main control circuit board via an interface circuit;
• the interface circuit comprises a micro control unit (MCU), an isolated power supply, and a signal isolating circuit;
• the MCU, the isolated power supply, and the signal isolating circuit are integrated on a circuit board;
• an output end of the isolated power supply supplies power for circuits;
• an input end of the isolated power supply is connected to an output end of a power supply of the ECM;
• an A/D conversion input port of the MCU is connected to the analog voltage signals;
• the MCU is configured to convert the analog voltage signals into pulse width modulation (PWM) signals or variable frequency signals, and output the PWM signals or the variable frequency signals to an input end of the signal isolating circuit;
• and the signal isolating circuit is configured to output the PWM signals or the variable frequency signals to a motor controller of the ECM.