PMSM MTPA Curve Tracing Using DC Power Feedback
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Solution Overview
Problem
Current methods for controlling vehicle permanent magnet synchronous motors, such as manual calibration and experimental testing, are inefficient and fail to account for manufacturing inconsistencies, motor misalignment, and temperature changes, leading to voltage saturation issues that affect torque output.
Innovation Solution
A method involving a current closed-loop adjuster, current command generator, current command angle generator, active power calculator, active power storage and comparison processor, and current given vector corrector to automatically search for the Maximum Torque Per Ampere (MTPA) curve based on DC power, allowing for real-time adjustment of dq current commands to optimize torque and voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual calibration and experimental testing are used to obtain MTPA curve, then the optimal current combination can be obtained, but the calibration efficiency is low and productivity is reduced
Solution Approach 1:
The system performs self-calibration by automatically searching for the MTPA curve through controlled current injection and active power measurement, eliminating the need for manual calibration operations. The motor controller autonomously determines optimal current combinations by executing the calibration algorithm and storing results in lookup tables.
Solution Approach 2:
The patent replaces manual mechanical calibration processes with an automated electronic control system that injects test currents, measures active power, and computes MTPA curves through software algorithms, thereby substituting human-operated mechanical procedures with automated electronic measurement and computation.
2Reliability
If manual calibration is performed, then the MTPA curve can be obtained, but it fails to account for manufacturing inconsistencies and motor misalignment
Solution Approach 1:
The calibration method dynamically determines optimal current parameters (id, iq) for each specific motor instance by measuring actual active power responses during the calibration process. This allows the system to adapt to manufacturing variations, magnetic saturation effects, and misalignment conditions by adjusting the MTPA curve parameters based on real motor characteristics rather than relying on theoretical or prototype data.
Solution Approach 2:
The system uses feedback from active power measurements during calibration to iteratively determine the optimal current combination. By measuring the actual active power consumed at different current angles and magnitudes, the system adjusts the MTPA curve parameters to match the specific motor's characteristics, compensating for manufacturing inconsistencies and assembly variations.
3Loss of time
If DC power is used for automatic MTPA curve search, then calibration time is reduced, but voltage saturation issues may occur
Solution Approach 1:
The calibration system dynamically adjusts current injection parameters including magnitude, angle, and duration based on real-time active power measurements and voltage saturation detection. The controller modifies the test current profile adaptively to prevent voltage saturation while maintaining calibration accuracy, and adjusts DC power levels according to motor operating conditions and thermal states.
Solution Approach 2:
The system applies partial current injection rather than full-rated current during calibration to avoid voltage saturation, using sufficient current magnitude to obtain measurable active power data while staying within voltage capabilities. The calibration process uses multiple incremental current steps rather than a single excessive current application, allowing accurate MTPA determination without exceeding voltage limits.
Data Source
AI summary
Disclosed is a method for searching a MTPA curve of a vehicle permanent magnet synchronous motor based on a DC power, which includes a current closed-loop adjuster, a current command generator, a current command angle generator, an active power calculator, an active power storage and comparison processor and a current given vector corrector. According to the present disclosure, the tedious manual calibration is relieved, the optimal angle is automatically searched, and the production efficiency is improved; according to the present disclosure, the step size can be arbitrarily set according to the calibration requirements, so as to achieve a higher calibration accuracy.