Abstract: A local oscillator and logic circuit pulses the open winding of a brushless DC motor at start up and the back EMF is used to generate a voltage to boost the voltage available to the control circuit for optimizing performance when starting with low supply voltage. As the rotor of a motor rotates and the windings are commutated by the drive electronics there is generated in each winding a voltage caused by the collapse of the current and the inherent inductance of the winding. These voltages exceed the normal operating voltage of the motor. The energy in these voltages is used to generate a regulated power feed to the analogue circuitry of the control circuit at a suitable voltage level. During steady state conditions, when the motor is running, the commutation of the windings is continual and there is ample energy available to power analogue electronics, and, if required, associated digital electronics as well.

Abstract: A local oscillator and logic circuit pulses the open winding of a brushless DC motor at start up and uses the back EMF to generate a voltage to boost the voltage available to the control circuit for optimizing performance when starting with low supply voltage.