Motor Control Current Reference Generation via Bisection Search
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Solution Overview
Problem
Existing motor control systems for interior permanent magnet synchronous motors (IPMSM) face challenges in accurately determining the reference d-axis current, which is crucial for output torque calculation, due to the complexity of voltage command and phase advance angle determination.
Innovation Solution
A motor control system that includes a current command controller monitoring bridge voltage and torque reference commands to determine a peak current, current angle, and subsequently the reference d-axis current, using iterative methods like the bisection search within defined solution domains, to calculate the reference d-axis and q-axis currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If traditional voltage command and phase advance angle determination methods are used, then output torque can be controlled, but the complexity of determining reference d-axis current increases
Solution Approach 1:
The patent transforms the complex voltage command and phase advance angle determination into a simplified parameter-based calculation using peak current and current angle. By changing the control parameters from voltage/angle domain to current magnitude/angle domain, the reference d-axis current can be determined directly through algebraic equations without complex iterative solving, thus reducing determination complexity while maintaining torque control capability
Solution Approach 2:
The patent calculates the peak current and current angle as preliminary parameters before determining the reference d-axis current. By performing these preliminary calculations using the torque reference command and motor parameters, the system prepares the necessary intermediate values that simplify the final current determination step, avoiding direct complex computation
2Measurement precision
If iterative methods like bisection search are used to determine reference currents, then accuracy improves, but computational time increases
Solution Approach 1:
The patent pre-calculates the solution domain boundaries and initial estimates for the current angle based on motor parameters and torque command before executing the iterative search. By preparing these preliminary values, the iterative method converges faster with fewer iterations required, thus reducing computational time while maintaining high accuracy in reference current determination
Solution Approach 2:
The patent segments the solution space by defining specific solution domains for the current angle based on motor operating conditions. By dividing the possible angle range into meaningful segments and searching only within relevant domains, the iterative method focuses computational effort on the most probable solution regions, improving both accuracy and efficiency
Data Source
AI summary
A motor control system for determining a reference d-axis current is provided, and includes a motor, a DC power source and DC input lines, and a current command controller. The DC power source generates a bridge voltage across the DC input lines. The current command controller is in communication with the motor and the DC input lines. The current command controller is configured to monitor the bridge voltage and a torque reference command. The current command controller is configured to determine a peak current based on the torque reference command. The current command controller is configured to determine a current angle based on the peak current. The current command controller is configured to determine the reference d-axis current based on the current angle.