Patent ID: 9605681
Date: 2017-03-28
CPC Classifications: F04D,H02P,Y02B

Claim:
1. A vacuum pump comprising: a motor for driving to rotate a pump rotor; a sine wave driving command generating section for generating a sine wave driving command; a PWM driving command generating section for generating a PWM driving command based on the sine wave driving command; an inverter circuit, having a plurality of switching elements controlled to be on/off based on the PWM driving command, for supplying, to the motor, a driving current to be generated by turning on/off the plurality of switching elements or regenerating the driving current from the motor; an estimating section for detecting motor phase voltage of the motor, and estimating a magnetic pole electric angle and a rotational speed of the motor; and a driving current controller for repeating generation and cut-off of the driving current supplied from a power supply to the motor via the inverter circuit or regenerated from the motor to the power supply in a low-speed period between a stopped state and a predetermined rotational speed in an accelerating operation at a motor starting time or a decelerating operation at a motor stopping time, wherein the estimating section detects the motor phase voltage at the cut-off time so as to estimate the magnetic pole electric angle and the rotational speed in the low-speed period based on the motor phase voltage, the driving current controller repeats the supply or the regeneration of the driving current based on an on/off command of the PWM driving command, and the cut-off of the driving current by making all the plurality of switching elements be in an off state in the low-speed period, and the estimating section detects the motor phase voltage at the cut-off time in the low-speed period, and estimates the magnetic pole electric angle and the rotational speed.