MOTOR DRIVE CIRCUIT, MOTOR DRIVE METHOD, AND COOLING DEVICE USING THE MOTOR DRIVE CIRCUIT

摘要

PPROBLEM TO BE SOLVED: To provide a drive circuit capable of flexibly executing torque control, when a motor is started. PSOLUTION: The motor drive circuit 100 generates a pulse-modulated drive signal SD for controlling the energizing period of a coil in a fan motor 120 as a drive target and controls the rotational frequency. A time-constant circuit 10 generates a first start-control voltage Vstrt1, whose voltage value changes together with the lapse of time, when the fan motor 120 is started. An amplifier 20 inversely amplifies the first start-control voltage Vstrt1, outputted from the time constant circuit 10 so as to output it as a second start-control voltage Vstrt2. A drive signal generating circuit 30 combines a rotation control voltage Vcnt, set corresponding to the torque target value of the motor, with the first/second start-control voltages Vstrt1, Vstrt2 so as to generate a pulse-modulated drive signal SD, having duty ratio that corresponds to one among the three voltages. PCOPYRIGHT: (C)2007,JPO&INPIT