Torque Ripple Compensation Controller for IPMSM
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Solution Overview
Problem
Interior permanent magnet synchronous motors (IPMSMs) produce significant torque ripple, which is undesirable in electric power steering applications where low torque ripple is required.
Innovation Solution
A motor control system that includes a torque ripple compensation controller, which determines a harmonic ripple current based on reference q-axis and d-axis currents, and adds these currents to compensate for torque ripple, thereby reducing motor harmonic-induced torque ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If IPMSM is used for its cost-effectiveness, then manufacturing cost is reduced, but torque ripple increases
Solution Approach 1:
The patent converts the harmful torque ripple generated by the IPMSM into a beneficial effect by calculating compensating currents that generate an opposing torque ripple. The controller computes harmonic ripple currents based on motor parameters and operating conditions, then adds these compensating currents to the phase currents to cancel out the original torque ripple, thus transforming the harmful effect into a beneficial torque smoothing effect.
2Object-generated harmful factors
If torque ripple compensation is implemented, then torque ripple is reduced, but control system complexity increases
Solution Approach 1:
The patent implements preliminary action by pre-calculating the compensating torque ripple currents based on motor parameters and expected operating conditions. The controller computes the harmonic ripple currents in advance using the motor's inductance values, flux linkage, and operating point, then applies these pre-computed compensation currents to proactively cancel torque ripple before it manifests, rather than reacting to it after occurrence.
3Object-generated harmful factors
If harmonic ripple currents are calculated and added, then torque ripple is compensated, but computational requirements increase
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the compensating currents based on the motor's operating parameters such as speed, torque demand, and inductance values. The controller modifies the harmonic ripple current calculations according to the current operating point, using the motor's electrical parameters (inductance Ld, Lq, flux linkage) and operating conditions to adaptively compute the appropriate compensation magnitude and phase, optimizing the balance between compensation effectiveness and computational effort.
Data Source
AI summary
A motor control system is provided. The motor control system includes a motor having plurality of motor harmonics, and a torque ripple compensation controller in communication with the motor. The torque ripple compensation controller is configured to determine a harmonic ripple current for a corresponding one of the plurality of motor harmonics. The harmonic ripple current is based on a reference q-axis current and a reference d-axis current. The torque ripple compensation controller is configured to add the harmonic ripple current for each of the plurality of motor harmonics together to determine the ripple compensating current.