Abstract: A system for braking an electric motor. For each motor winding, a first switch is connected between the winding and electrical ground and in series with a resistor and is closeable to connect the winding to ground through the resistor, and a second switch is connected between the winding and ground and is closeable to bypass the resistor. A controller receives feedback regarding the speed and sends to the second switch a pulse width modulated signal which selectively opens and closes the second switch to connect and disconnect the resistor to achieve an optimal equivalent average stator resistance for the motor speed which results in a power transfer to the resistor and increases a braking torque as the motor slows. The pulse width modulated signal opens the second switch for a longer time when the motor speed is higher and for a shorter time when the motor speed is lower.

Abstract: A safety switching system and method for braking an electric motor in a mobile device. A multi-phase shorting system brakes the motor by diverting power from the motor windings. Multiple independent switching units each include a switch control unit controlling multiple normally-closed switches which, in response to a safety controller, close to connect a respective motor winding to electrical ground. An electromechanical brake system mechanically brakes the motor. An independent switching unit includes two normally-open switches which, in response to the safety controller, opens to activate an electromechanical brake. A feedback system communicates to the safety controller a switch failure of any of the switches either as a short circuit fault or an open circuit fault. The feedback system may include an analog and/or a digital feedback system. If a switch failure is detected, the safety controller may activate the multi-phase shorting system and the electromechanical brake system.

Abstract: A safety switching system and method for braking an electric motor in a mobile device. A multi-phase shorting system brakes the motor by diverting power from the motor windings. Multiple independent switching units each include a switch control unit controlling multiple normally-closed switches which, in response to a safety controller, close to connect a respective motor winding to electrical ground. An electromechanical brake system mechanically brakes the motor. An independent switching unit includes two normally-open switches which, in response to the safety controller, opens to activate an electromechanical brake. A feedback system communicates to the safety controller a switch failure of any of the switches either as a short circuit fault or an open circuit fault. The feedback system may include an analog and/or a digital feedback system. If a switch failure is detected, the safety controller may activate the multi-phase shorting system and the electromechanical brake system.

Abstract: A system for braking an electric motor. For each motor winding, a first switch is connected between the winding and electrical ground and in series with a resistor and is closeable to connect the winding to ground through the resistor, and a second switch is connected between the winding and ground and is closeable to bypass the resistor. A controller receives feedback regarding the speed and sends to the second switch a pulse width modulated signal which selectively opens and closes the second switch to connect and disconnect the resistor to achieve an optimal equivalent average stator resistance for the motor speed which results in a power transfer to the resistor and increases a braking torque as the motor slows. The pulse width modulated signal opens the second switch for a longer time when the motor speed is higher and for a shorter time when the motor speed is lower.