Flux Estimator for Accurate Rotor Speed and Angle
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electric motor control systems face challenges in accurately estimating rotor speed and angle, particularly at high speeds, leading to inefficiencies and increased switching losses due to the use of unmodulated voltage commands that do not account for DC bus voltage and time duration thresholds.
Innovation Solution
A controller device with a flux estimator that determines reconstructed alpha and beta voltages based on modulated time durations, providing more accurate estimates of rotor speed and angle, which reduces PWM frequency and switching losses while maintaining control accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If unmodulated voltage commands are used for rotor speed and angle estimation, then the control system is simpler to implement, but the estimation accuracy deteriorates especially at high speeds
Solution Approach 1:
The patent changes the parameter used for voltage estimation from unmodulated voltage commands to reconstructed modulated voltages. By using the actual PWM modulated voltages that account for DC bus voltage and time duration thresholds, the estimation accuracy is improved without significantly increasing system complexity, as the reconstruction uses existing controller parameters.
Solution Approach 2:
The patent implements a feedback mechanism where the controller device uses the reconstructed voltages from actual PWM signals to continuously update and improve rotor speed and angle estimates. This feedback loop allows the system to compensate for inaccuracies and maintain high estimation accuracy across different operating conditions.
2Measurement precision
If higher PWM frequency is used to improve control accuracy, then the rotor speed and angle estimation becomes more accurate, but switching losses increase
Solution Approach 1:
The patent changes the approach from using high PWM frequency to using accurately reconstructed voltages from actual PWM signals. This parameter change allows the system to maintain high control accuracy while operating at lower PWM frequencies, thereby reducing switching losses in the power conversion circuitry.
3Device complexity
If unmodulated alpha and beta voltages are used, then the voltage calculation is simpler, but the voltages do not accurately represent actual voltages applied to field windings
Solution Approach 1:
The patent changes the voltage calculation from using unmodulated alpha and beta voltages to using reconstructed modulated voltages. By incorporating the actual PWM time durations and DC bus voltage into the reconstruction process, the system achieves accurate representation of actual voltages applied to field windings while using parameters already available in the controller.
Data Source
AI summary
In some examples, a controller device includes processing circuitry configured to determine an alpha voltage and a beta voltage based on time durations for control signals for power-conversion circuitry that drives an electric motor including a rotor. In some examples, the controller device also includes a flux estimator configured to estimate a speed of the rotor and an angle of the rotor based on the alpha voltage and the beta voltage.