System and method of increasing resolution of position feedback for motor control

A motor drive configured to increase resolution of a position feedback signal, the motor drive comprising:

• an input configured to receive a position feedback signal;
• and
• a processor configured to execute a first series of instructions at a first time interval and to execute a second series of instructions at a second time interval, wherein:
• the first time interval is shorter than the second time interval,
• the first series of instructions execute to:
• increment a first counter when a new pulse from the position feedback signal is detected,
• read a high resolution counter register from a high resolution counter during each first time interval,
• add a value of the first counter to the high resolution counter register to obtain a new value for the high resolution counter register during each first time interval, and
• store the new value in the high resolution counter register during each of the first time intervals,
• the second series of instructions executes a speed regulator using the high resolution counter during each second time interval.

A method for increasing resolution of a position feedback signal to a motor drive, the method comprising the steps of:

• receiving a position feedback signal at an input to the motor drive;
• determining a number of counts in the motor drive as a function of the position feedback signal;
• monitoring the number of counts at a first time interval;
• incrementing a first counter within the motor drive during the first time interval when a new count is detected;
• reading a high resolution counter register from a high resolution counter during each of the first time intervals;
• adding a value of the first counter to the high resolution counter register to obtain a new value for the high resolution counter register during each of the first time intervals;
• storing the new value in the high resolution counter register during each of the first time intervals;
• and
• executing a speed regulator in the motor drive during a second time interval, wherein:
• the speed regulator uses the high resolution counter, and the second time interval is longer than the first time interval.