초록 ▼

In a brushless motor of the kind not employing a sensor for detecting rotor position, a rotational reference position of the rotor is detected based on an induction voltage in a stator excitation coil, and an energization switching point of the stator excitation coil is determined to occur a delayed

In a brushless motor of the kind not employing a sensor for detecting rotor position, a rotational reference position of the rotor is detected based on an induction voltage in a stator excitation coil, and an energization switching point of the stator excitation coil is determined to occur a delayed time from the reference position. The time delay is increased or decreased in response to the rotational speed of the motor, so that energization switching of the excitation coils is performed at the optimum position in accordance with corresponding changes in the rotational speed of the motor. Signal masking is performed so that noise generated by the excitation coil switching does not interfere with the detection of the rotor reference position.

대표청구항 ▼

A sensorless brushless motor comprising: a rotor having a magnet; an excitation coil; a switching circuit for performing energization switching of said excitation coil; a reference position detector for detecting a reference position of rotor rotation based on a voltage induced in said excitation co

A sensorless brushless motor comprising: a rotor having a magnet; an excitation coil; a switching circuit for performing energization switching of said excitation coil; a reference position detector for detecting a reference position of rotor rotation based on a voltage induced in said excitation coil by said magnet; a delay circuit for producing a delay clock signal having clock pulses delayed by a predetermined amount from the reference position detected by said reference position detector; a delay pulse signal forming circuit for forming a delay pulse signal based on the delay clock signal from said delay circuit; a switching signal generator for generating an energization switching signal based on the delay pulse signal and supplying the switching signal to said switching circuit; and a control circuit for detecting a rotational speed of said rotor for controlling the amount of delay in said delay circuit, and adjusting the energization switching position to said excitation coil in accordance with the rotational speed of said rotor. A sensorless brushless motor comprising: a rotor; an excitation coil; a switching circuit for performing energization switching of the excitation coil; a reference position detector for detecting a reference position of rotor rotation based on a voltage induced in said excitation coil by said rotor; a delay circuit for producing a delay clock signal having pulses delayed by a predetermined amount from the reference position detected by said reference position detector; a delay pulse signal forming circuit for producing a delay pulse signal based on the delay clock signal from said delay circuit; a switching signal generator for generating an energization switching signal fed to said switching circuit in response to the delay pulse signal; and a masking circuit for forming a noise masking signal based on at least the delay clock signal for suppressing noise pulses in a detection output of said reference position detector at the reference position.