| 摘要 |
PURPOSE:To control output torque from a motor precisely by comparing the mean value of currents interrupted by the control of a chopper with a certain set value proportional to a chopper-control duty. CONSTITUTION:Interrupted waveform currents approximately proportional to the number of revolution of a DC motor 4 flow through a current detecting resistor RSH. The currents are levelled by a low-pass filter consisting of a resistor R4, a time constant thereof is designed at a value larger than the period of a chopper, and a capacitor C1, and inputted to a comparator 6. A comparison level signal obtained by smoothing a chopper signal outputted from a chopper output terminal for a micro-computer 7 by a low-pass filter composed of a resistor R1 and a capacitor C2 is voltage-divided by resistors R2, R3, and inputted to another input terminal for the comparator 6. The comparison level of the comparator 6 is proportional to a revolution-number signal, thus allowing control corresponding to output torque from the brushless DC motor 4. |
