| 摘要 |
PURPOSE:To correct the position detecting signal outputted from a control circuit for a DC brushless motor by comparing an induced voltage with a prescribed reference value by means of a comparator circuit and storing the output signal of the comparator circuit at the rising and falling time of a PWM waveform signal only when the PWM waveform signal is generated. CONSTITUTION:In a position detecting circuit 7, a digital comparator compares position detecting U-, V-, and W-phase input signals supplied from a signal processing circuit 6 with three-bit reference values stored in a reference value register and, when both signals coincide with each other, the comparator outputs a coincidence signal by considering that the rotor of a motor 3 is at a specific position. A counter which counts the number of coincident times counts the coincidence signal and when the count value of the counter reaches a prescribed number of coincident times stored in a number-of-coincident-time setting register, outputs a position detecting output signal 10. Therefore, the malfunction of the control circuit for the DC brushless motor can be prevented even when a position-detected result erroneously become coincident. |
