| 摘要 |
PURPOSE: A circuit for controlling a motor is provided to control the magnitude of source voltage of the motor corresponding to a control signal although a converter circuit is established with a large time constant. CONSTITUTION: A low voltage detecting/comparing circuit(100) detects low voltage from output voltage wave of each phase of a motor, compares with reference voltage, and generating a low voltage comparing signal(PCS). A chopping wave generating circuit(200) generates a chopping wave swing between established maximum value and minimum value with the constant cycle. A comparator(300) receives the chopping wave voltage as the reference voltage and compares a level of the low voltage comparing signal. A converter circuit(400) operates in the case that the level of the low voltage comparing signal belongs to a range of the maximum value and the minimum value of the copping wave, and increases level of source voltage of the motor in the case that the output voltage of the comparator(300) is low level and decreases the level of source voltage of the motor in the case that the output voltage of the comparator(300) is high level. A time constant control circuit(500) operates in the case that the level of the low voltage comparing signal does not belong to the range of the maximum value and the minimum value of the copping wave, and decreases level of source voltage of the motor in the case that the output voltage of the comparator(300) is higher than the maximum value of the copping wave voltage regardless of a control of the converter circuit(400) and increases the level of source voltage of the motor in the case that the output voltage of the comparator(300) is lower than the minimum value of the copping wave voltage regardless of the control of the converter circuit(400).
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