I have a PM DC motor. I am controlling the motor speed using PWM. I wanted to know what is the relation between the torque vs dutycycle and speed vs dutycycle for the motor( given the fact that the peak amplitude of the PWM signal is Vm and frequency is f) . Characteristics of the motor in the datasheet are only stated as vsrelative to armature current. How do you relate armature current with the PWM voltage signal?