# US 12,191,785 B2 · System and method for inertial compensation in a motor drive > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,191,785 B2 - Document ID: US12191785B2 - Status: Granted - Kind: B2 - Application number: 18/107,827 - Filed: 2023-02-09 - Published: 2024-08-15 - Granted: 2025-01-07 - Earliest claimed: 2023-02-09 - Assignees: Rockwell Automation Technologies, Inc. - Applicants: Rockwell Automation Technologies, Inc. - Inventors: Jonathan D. Hoffman; Adam M. Shea; Robert J. Miklosovic - Web page: https://patentgrep.com/patent/US12191785B2 ## CPC - H02P 23/14: Estimation or adaptation of motor parameters, e.g. rotor time constant, flux, speed, current or voltage - H02P 23/18: Controlling the angular speed together with angular position or phase - H02P 6/06: Arrangements for speed regulation of a single motor wherein the motor speed is measured and compared with a given physical value so as to adjust the motor speed - H02P 6/08: Arrangements for controlling the speed or torque of a single motor (H02P6/10, H02P6/28 take precedence) - H02P 21/13: Observer control, e.g. using Luenberger observers or Kalman filters - H02P 23/12: Observer control, e.g. using Luenberger observers or Kalman filters - H02P 23/20: Controlling the acceleration or deceleration - H02P 27/08: with pulse width modulation - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS ## Abstract A motor drive receives a position feedback signal from a position sensor operatively connected to a motor. The motor drive receives a command signal defining a desired operation of the motor. A processor in the motor drive generates an acceleration feedforward signal from the command signal and an acceleration reference signal from the command signal and the position feedback signal. The processor also generates an estimated disturbance acceleration from the acceleration reference signal. The acceleration feedforward signal is multiplied by a first gain to obtain a first product, and the estimated disturbance acceleration by a second gain to obtain a second product. The first and second gains are functions of first and second portions of the system inertia. A current reference signal is generated based on the first product and second products, and an output voltage to the motor is generated from the current reference signal. ## Claims ### Claim 1 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 and the position feedback signal; multiplying 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; multiplying the estimated disturbance acceleration by a second gain to obtain a second product; summing the first product with the second product to obtain a modified acceleration reference signal; and generating an output voltage to control operation of the motor as a function of the modified acceleration reference signal. ### Claim 2 (depends on 1) The method of claim 1, wherein the motor drive includes a load observer and the step of generating the estimated disturbance acceleration is performed by the load observer. ### Claim 3 (depends on 2) The method of claim 2, further comprising the step of executing an autotuning module with the processor, wherein the autotuning module includes the steps of: generating a predefined voltage reference to control operation the motor; sampling the position feedback signal with the motor drive while generating the predefined voltage reference; and determining at least one observer gain for the load observer as a function of the predefined voltage reference and of the position feedback signal sampled while generating the predefined voltage reference. ### Claim 4 (depends on 3) The method of claim 3, wherein the load inertia value is obtained as a function of the predefined voltage reference from the autotuning module and of the position feedback signal sampled while generating the predefined voltage reference. ### Claim 5 (depends on 1) The method of claim 1, wherein the first gain is the load inertia value and the second gain is a motor inertia value. ### Claim 6 (depends on 1) The method of claim 1, wherein the first gain is a ratio of the load inertia value over a motor inertia value and the second gain is a unity gain, the method further comprising the step of multiplying a sum of the first product and the second product by the motor inertia to obtain the modified acceleration reference signal. ### Claim 7 (depends on 1) The method of claim 1, wherein the acceleration feedforward signal is one component of the command signal. ### Claim 8 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. ### Claim 9 (depends on 8) The method of claim 8, wherein the motor drive includes a load observer and the step of generating the estimated disturbance acceleration is performed by the load observer. ### Claim 10 (depends on 9) The method of claim 9, further comprising the step of executing an autotuning module with the processor, wherein the autotuning module includes the steps of: generating a predefined voltage reference to control operation the motor; sampling the position feedback signal with the motor drive while generating the predefined voltage reference; and determining at least one observer gain for the load observer as a function of the predefined voltage reference and of the position feedback signal sampled while generating the predefined voltage reference. ### Claim 11 (depends on 8) The method of claim 8, wherein: the first portion of the system inertia value is a load inertia value; the second portion of the system inertia value is a motor inertia value; the first gain is a ratio of the load inertia value over the motor inertia value; the first product is added to the estimated disturbance acceleration before multiplying by the second gain; and the second gain is the motor inertia value divided by a torque constant. ### Claim 12 (depends on 8) The method of claim 8, wherein: the first gain is a load inertia value; the second gain is a motor inertia value; and the current reference is generated by adding the first product to the second product to generate a sum and by dividing the sum by a torque constant. ### Claim 13 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. ### Claim 14 (depends on 13) The motor drive of claim 13, wherein the configuration parameters include a motor inertia value corresponding to an unloaded state of the motor. ### Claim 15 (depends on 13) The motor drive of claim 13, wherein the controller is further operable to execute a load observer and the estimated disturbance acceleration is an output from the load observer. ### Claim 16 (depends on 15) The motor drive of claim 15, wherein the controller is further operable to execute an autotuning module to: generate a predefined voltage reference to control operation the motor; sample the position feedback signal while generating the predefined voltage reference; and determine at least one observer gain for the load observer as a function of the predefined voltage reference and of the position feedback signal sampled while generating the predefined voltage reference. ### Claim 17 (depends on 16) The motor drive of claim 16, wherein the load inertia value is determined as a function of the predefined voltage reference from the autotuning module and of the position feedback signal sampled while generating the predefined voltage reference. ### Claim 18 (depends on 13) The motor drive of claim 13, wherein the first gain is the load inertia value and the second gain is the motor inertia value. ### Claim 19 (depends on 13) The motor drive of claim 13, wherein the first gain is a ratio of the load inertia over the motor inertia and the second gain is a unity gain, and wherein the controller multiplies a sum of the first product and the second product by the motor inertia to obtain the modified acceleration reference signal. ### Claim 20 (depends on 13) The motor drive of claim 13, wherein the acceleration feedforward signal is one component of the command signal.