Patent ID: 6545443
Filing Date: 2003-04-08
Classification: H02P

Abstract:
A PWM control device, comprising:a microprocessor; interrupt processing means which allows the microprocessor to execute a process for detecting a predetermined rotational position interval of a rotor of a brushless motor by use of rotation position detecting means according to interrupt processing; PWM control means which allows the microprocessor to execute a process for outputting a PWM signal through the use of a detected signal of the predetermined rotational position interval with respect to the amount of each current supplied from an inverter circuit for driving the brushless motor to thereby cause the microprocessor to perform PWM control; and inrush current limiting means which allows the microprocessor to execute a process for enlarging the pulse width of the PWM signal during the interrupt processing upon the startup of the brushless motor and for progressively enlarging the pulse width of the PWM signal according to the repetition of the interrupt processing; wherein the inrush current limiting means allows the microprocessor to execute a process for monotonously decreasing a value of a current control signal for determining the pulse width of the PWM signal by comparison with a predetermined repetitive waveform during the interrupt processing to thereby monotonously change the pulse width.