D-Q Motor Control for Magnetic Cross-Coupling Compensation
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Solution Overview
Problem
Traction motors experience attenuated torque responses and torque disturbances due to magnetic cross coupling between the direct and quadrature axes, which negatively impacts motor torque tracking performance in electric vehicles and hybrid electric vehicles.
Innovation Solution
A model predictive controller operating in the d-q reference frame generates voltage command signals to counteract magnetic cross coupling, using feedforward and feedback adjustments, and transforming these signals into stationary reference frame commands to control a power inverter coupled to the motor's poly-phase stator winding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If model predictive control is used to handle complex multivariable control problems, then control performance in wide operating ranges and rapid dynamic response is improved, but magnetic cross coupling between direct axis and quadrature axis causes attenuated torque responses and torque disturbances
Solution Approach 1:
The patent introduces an intermediary decoupling network between the cost function output and the voltage command signals. This network includes feedforward adjustment modules that calculate compensating voltage signals based on d-q axis currents and motor parameters, and feedback adjustment modules that use proportional-integral controllers to eliminate steady-state errors. The intermediary network processes the cost function outputs and generates corrected voltage commands that counteract magnetic cross coupling effects, thereby resolving the contradiction between control performance and torque tracking accuracy.
2Reliability
If feedforward adjustments are applied to counteract magnetic cross coupling, then torque tracking performance is improved, but device complexity increases due to additional adjustment modules
Solution Approach 1:
The patent implements feedforward adjustments by dynamically calculating compensating voltage signals based on real-time d-q axis currents and motor parameters (inductance, resistance, angular velocity). The adjustment modules modify the voltage command parameters to counteract magnetic cross coupling effects. This parameter-based approach improves torque tracking performance without requiring additional physical hardware components, thereby limiting the increase in device complexity to software/algorithm level.
3Measurement precision
If feedback adjustments with proportional-integral controllers are used, then steady-state accuracy is improved, but response time may be reduced due to additional processing
Solution Approach 1:
The patent employs a dual-adjustment strategy where feedforward adjustments are applied in advance to counteract magnetic cross coupling effects before they manifest as torque disturbances. The feedback adjustments with proportional-integral controllers then fine-tune the voltage commands to eliminate steady-state errors. This preliminary action approach, particularly the feedforward component, reduces the burden on the feedback loop and minimizes additional processing time, thereby balancing steady-state accuracy with response time.
Data Source
AI summary
A method and apparatus for electric motor control includes a model predictive controller operating in a d-q reference frame to provide d-q reference frame voltage command signals that counteract a magnetic cross coupling within the motor.