Patent ID: 6545442
Filing Date: 2003-04-08
Classification: H02P

Abstract:
An apparatus for controlling a rotation speed of a brushless motor, comprising:a commanded rotation speed detecting section that detects a commanded rotation speed of a rotor of the brushless motor from an inputted rotate command signal to command the rotor to rotate at the commanded rotational speed; a first target value calculating section that calculates a target value of the rotation speed of the rotor on the basis of the commanded rotation speed of the rotor detected by the commanded rotation speed detecting section; a second target value calculating section that raises the rotation speed of the rotor of the brushless motor by a first gradient for the rotation speed of the rotor to be reached to a present target value of the rotation speed of the rotor presently calculated by the first target value calculating section when the rotor is stopped and the present target value of the rotation speed presently calculated by the first target value calculating section is received so as to perform a soft start control for the rotation of the rotor and lowers the rotation speed of the rotor by a second gradient for the rotation speed of the rotor to be reached to the present target value of the rotation speed of the rotor when the rotor of the motor is rotating at a previous target value of the rotor of the motor previously calculated by the first target value calculating section and the present target value of the rotor of the motor is lower than the previous target value thereof at which the rotor of the motor is rotating; and a rotational drive section that outputs a rotational drive signal to drive the rotor of the motor to be rotated to a switching device to supply a power supply voltage to a stator of the motor in response to the rotational drive signal, the rotational drive signal being generated in accordance with the target value of the rotational speed of the rotor.