System and method for inertial compensation in a motor drive

A method of controlling operation of a motor with a motor drive, the method comprising the steps of:

• receiving a position feedback signal at the motor drive from a position sensor operatively connected to the motor;
• receiving a command signal at the motor drive, wherein the command signal defines a desired operation of the motor;
• generating an acceleration feedforward signal with a processor in the motor drive as a function of the command signal;
• generating an acceleration reference signal with the processor as a function of the command signal and of the position feedback signal;
• generating an estimated disturbance acceleration with the processor as a function of the acceleration reference signal;
• multiplying the acceleration feedforward signal by a first gain to obtain a first product, wherein the first gain is a function of a first portion of the system inertia;
• multiplying the estimated disturbance acceleration by a second gain to obtain a second product, wherein the second gain is a function of a second portion of the system inertia;
• generating a current reference signal as a function of the first product and the second product;
• and
• generating an output voltage to control operation of the motor as a function of the current reference signal.

A motor drive, comprising:

• a DC bus having a positive rail and a negative rail, wherein the DC bus is operable to receive a DC voltage between the positive rail and the negative rail;
• an inverter section having a plurality of switching elements, wherein each switching element is controlled by a gating signal and wherein the inverter section is operable to receive the DC voltage from the DC bus and provide an AC voltage at an output of the motor drive;
• a memory device operable to store a plurality of instructions and a plurality of configuration parameters;
• a first input configured to receive a command signal corresponding to desired operation of a motor connected to the motor drive;
• a second input configured to receive a position feedback signal corresponding to an angular position of the motor connected to the output of the motor drive;
• a controller operable to execute the plurality of instructions to:
• sample the position feedback signal,
• generate an acceleration feedforward signal as a function of the command signal,
• generate an acceleration reference signal as a function of the command signal and of the position feedback signal,
• generate an estimated disturbance acceleration as a function of the acceleration reference and the position feedback signal,
• multiply the acceleration feedforward signal by a first gain to obtain a first product, wherein the first gain is a function of a load inertia value,
• multiply the estimated disturbance acceleration by a second gain to obtain a second product, wherein the second gain is a function of a motor inertia value, and
• sum the first product with the second product to obtain a modified acceleration reference signal;
• and
• a gate driver module operable to generate the gating signal for each of the plurality of switching elements in the inverter section as a function of the modified acceleration reference signal from the controller.