Patent ID: 7486489
Filing Date: 2009-02-03
Classification: H02H,H02P

Abstract:
1. A speed control and stall protection system for an electric DC brush motor, the system comprising: a DC brush motor, at least one relay connected between the motor and a power supply, a speed sensing circuit constructed and arranged to generate a signal indicative of a speed of the motor, and a motor control and protection circuit constructed and arranged to receive 1) the signal from the speed sensing circuit and 2) a control signal input for operating the at least one relay to control operation of the motor, wherein, when a stall condition is determined based on the signal from the speed sensing circuit, the motor control and protection circuit is constructed and arranged to control the at least one relay to disconnect power to the motor, and wherein the motor is a dual speed motor and a first relay is provided together with a series resistor for operating the motor at a low speed and a second relay is provided for operating the motor at a speed greater than the low speed, the motor control and protection circuit being constructed and arranged to receive the control signal input in the form of a speed control signal to selectively activate the first and second relays to control speed of the motor, and to inactivate the first and second relays to disconnect power to the motor.