Method for controlling a BLDC motor and corresponding control circuit

A control circuit of a brushless DC (BLDC) motor, configured to control the BLDC motor based on a position of a rotor of the BLDC motor, the BLDC motor being driven with three driving phases supplied to three-phase driving terminals by a three-phase inverter having three arms, each of the arms respectively including a high side switch and a low side switch, the BLDC motor configured to operate with a sinusoidal commutation, the control circuit comprising:

• processing circuitry configured to calculate a current position of the rotor based on zero-crossing times of back electromotive forces, the processing circuitry comprising:
• PWM generation circuitry configured to generate a PWM signal for each of three PWM phases, each of the PWM signals including a respective pair of complementary signals with dead-time and having a duty cycle based on a current position of the rotor, and to drive the three-phase inverter by supplying each pair of complementary signals with dead-time to a respective high side switch and low side switch;
• measurement circuitry configured to generate corresponding signals indicating zero-crossing times by performing a zero-crossing time measurement on each of the back electromotive forces sensed at the three-phase driving terminals of the BLDC motor, the current position of the rotor being calculated based on the zero-crossing times of the back electromotive forces;
• and
• trigger circuitry configured to generate trigger signals based on the occurrence of a time interval corresponding to the dead-time in the respective PWM phase, which activate the measurement circuitry to perform the zero-crossing time measurement on each of the back electromotive forces, wherein the zero-crossing time measurement is performed during the occurrence of the dead-time.

A device, comprising:

• a brushless DC (BLDC) motor configured to be driven with three driving phases supplied to three-phase driving terminals by a three-phase inverter having three arms, each of the arms respectively including a high side switch and a low side switch, the BLDC motor configured to operate with a sinusoidal commutation;
• and
• a control circuit configured to:
• control the BLDC motor based on a position of a rotor of the BLDC motor;
• calculate a current position of the rotor based on zero-crossing times of back electromotive forces;
• generate a PWM signal for each of three PWM phases, each of the PWM signals including a respective pair of complementary signals with dead-time and having a duty cycle based on a current position of the rotor, and to drive the three-phase inverter by supplying each pair of complementary signals with dead-time to a respective high side switch and low side switch;
• generate corresponding signals indicating zero-crossing times by performing a zero-crossing time measurement on each of the back electromotive forces sensed at the three-phase driving terminals of the BLDC motor the current position of the rotor being calculated based on the zero-crossing times of the back electromotive forces;
• and
• generate trigger signals based on the occurrence of a time interval corresponding to the dead-time in the respective PWM phase, which activate the control circuit to perform the zero-crossing time measurement on each of the back electromotive forces, wherein the zero-crossing time measurement is performed during the occurrence of the dead-time.