Systems and methods for torque control of actuator and brushless DC motor therein

A method for controlling an actuator that includes an output member that is mechanically driven by a brushless DC motor, said motor being energized by a plurality of drivers, said drivers supplying energy to said motor based upon a motor winding commutation pattern and a PWM control signal used therewith to control an amount of energy transferred to said motor and thereby controlling motor speed, said method comprising:

• determining said motor speed;
• determining a line voltage supplying said drivers of said motor;
• based upon said motor speed, said line voltage and predetermined motor performance data, determining a maximum PWM on-time for said PWM control signal, said maximum PWM on-time corresponding to a predetermined motor torque output limit;
• controlling said speed of said motor by regulation of said PWM control signal in response to said determined motor speed and a desired motor speed;
• and
• wherein said controlling includes limiting said PWM control signal to said maximum PWM on-time thereby limiting output of said motor to said predetermined motor torque output limit.

An apparatus comprising:

• a brushless DC motor;
• a plurality of drivers coupled to said motor for energization thereof, wherein said drivers supply energy to said motor based upon a motor winding commutation pattern and a PWM control signal used therewith to control an amount of energy transferred to said motor thereby controlling a speed thereof;
• means for determining a speed of the motor;
• means for determining a line voltage supplying said drivers of said motor;
• and
• means for determining a maximum PWM on-time for said PWM control signal based upon said speed, said line voltage and predetermined motor performance data, wherein said maximum PWM on-time corresponds to a predetermined motor torque output limit.

An apparatus for controlling an actuator that includes an output member that is mechanically driven by a brushless DC motor, said motor being energized by a plurality of drivers, said drivers supplying energy to said motor based upon a motor winding commutation pattern and a PWM control signal used therewith to control an amount of energy transferred to said motor and thereby controlling motor speed, said apparatus comprising:

• means for determining said motor speed;
• means for determining a line voltage supplying said drivers of said motor;
• means for determining a maximum PWM on-time based upon said motor speed, said line voltage and predetermined motor performance data, wherein said maximum PWM on-time corresponds to a predetermined motor torque output limit;
• means for controlling said motor speed by regulation of said PWM control signal in response to said determined motor speed and a desired motor speed;
• and
• wherein said means for controlling includes means for limiting said PWM control signal to said maximum PWM on-time thereby limiting output of said motor to said predetermined motor torque output limit.

An actuator comprising:

• an output member;
• a brushless DC motor mechanically coupled to said output member;
• a PWM control signal controllable coupled, at least in part, to said brushless DC motor and being operable to control an amount of energy transferred to said motor;
• means for positioning said output member by operating said motor;
• means for controlling output torque of said motor during said positioning thereof, said means for controlling including means for collecting operational motor data, said operational motor data being exclusive of motor current consumption;
• and
• means for using said collected data in combination with predetermined motor performance data to regulate motor torque using said PWM control signal.