MOTOR CONTROLLER FOR VACUUM CLEANER

PURPOSE:To suppress excessive power dissipation in a zone in which the air flow rate exceeds an optimum one for actual cleaning work by detecting a current through a motor by the use of a current detection circuit, controlling the time constant of a time constant circuit in an ignition pulse generation circuit corresponding to a detected current and controlling the current though the motor. CONSTITUTION:When a brush is opened or it is set in a state near to be opened, the air flow rate Q is large, and the current through the motor 21 is large, and a large current is detected by the current detection circuit 27. A signal in accordance with the large current is supplied to the time constant circuit of the ignition pulse generation circuit 25, which increases the time constant. Consequently, the phase angle of an ignition pulse outputted from the ignition pulse generation circuit 25 to an ignition circuit 26 is delayed, and power supply to the motor 21 is suppressed at standard of around 1kW. While, when the brush is brought into contact closely with a surface to be cleaned, the current through the motor 21 and a current control element 22 are decreased, and the detected current is also decreased, therefore, the time constant of the time constant circuit is decreased, and an energizing current through the motor 21 is increased.