Method for increasing rotational speed range of ECM motor

A method for increasing rotational speed range of an ECM motor, the ECM motor comprising:

• a) a stator assembly;
• b) a rotor assembly;
• and
• c) a motor controller, the motor controller comprising:
• a power circuit, a microprocessor, an inverter circuit, a bus current detecting circuit, and a hall sensor;
• the power circuit supplying power to each circuit;
• the bus current detecting circuit inputting a DC bus current I into the microprocessor;
• the hall sensor inputting a rotor position signal to the microprocessor and converting the rotor position signal into a real rotational speed n of the rotor;
• the microprocessor controlling the inverter circuit to drive the stator assembly;
• and
• the method comprising the following steps:
• 1) starting the motor and initializing parameters;
• 2) reading the rotor position signal from the hall sensor by the microprocessor and updating a rotor angle;
• 3) reading the DC bus current I and the rotational speed n of the motor by the microprocessor;
• 4) inputting a target rotational speed S from an external device, acquiring the target rotational speed S by the microprocessor, calculating a rotational difference e according to an equation:
• rotational difference e=target rotational speed S−rotational speed n of motor, and utilizing a rotational speed PI regulator to output a regulating parameter V_D;
• 5) calculating an advance angle α=F(I, n) by the microprocessor based on the DC bus current I and the rotational speed n of the motor, and calculating a real-time angle of the rotor θ=ω×t by the microprocessor, in which, ω represents an angular velocity and is calculated based on the rotational speed n of the motor, and t represents a time;
• and
• 6) calculating a PWM signal input into the inverter circuit by the microprocessor, outputting a PWM chopper voltage U by the inverter circuit, wherein U=F(V_D, θ+α), and repeating step 2).