Torque Error Estimation for IPMSM Current Sensor Optimization
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Solution Overview
Problem
Current electric drive systems face challenges in accurately determining the minimal sensor accuracy required for torque control, leading to increased costs due to over-specification of current sensors, and existing methods fail to effectively isolate, predict, or compensate for current sensing errors affecting torque output.
Innovation Solution
A system comprising a processor and a torque error estimation module that uses current sensor characteristics and machine characteristics to estimate torque control errors, including submodules for sensing error determination and torque error calculation, allowing for optimal sensor specification and cost-effective electric drive system design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high accuracy current sensors are used to minimize torque errors, then torque control accuracy is improved, but system cost increases
Solution Approach 1:
The system performs preliminary error estimation by calculating expected torque control errors based on current sensor characteristics and machine parameters before actual operation. This allows the design of an estimation module that predicts torque errors without requiring ultra-precise sensors, thereby reducing sensor specification costs while maintaining adequate torque control accuracy through compensatory calculations
Solution Approach 2:
The patent introduces a torque error estimation module as an intermediary between the current sensor and the torque control system. This module acts as a mediator that processes current sensor data, estimates resulting torque errors, and provides compensation signals. This intermediary layer allows the use of lower-cost sensors while maintaining torque control accuracy through software-based error compensation
2Ease of manufacture
If current sensor accuracy is reduced to lower costs, then system cost decreases, but torque control accuracy deteriorates
Solution Approach 1:
The system implements a feedback mechanism where the torque error estimation module continuously monitors current sensor readings, calculates expected torque errors based on known sensor characteristics and machine parameters, and feeds back compensation signals to the torque control system. This closed-loop feedback approach allows lower-cost sensors to achieve the required torque control accuracy through active error compensation
Solution Approach 2:
The patent changes the approach from relying solely on sensor hardware parameters (accuracy) to incorporating software-based estimation parameters. By introducing parameters such as sensor gain errors, offset errors, and machine-specific characteristics into the error estimation algorithm, the system compensates for lower sensor accuracy through parameter-based corrections rather than hardware precision
3Adaptability or versatility
If systematic approach for determining minimal sensor accuracy is developed, then sensor specification is optimized, but system complexity increases
Solution Approach 1:
The torque error estimation module is segmented into distinct functional components: a current sensor error determination submodule that calculates sensor errors based on characteristics, a torque error determination submodule that computes resulting torque errors, and a compensation generation module. This segmentation allows each component to perform a specific function efficiently, reducing overall system complexity through modular design while providing comprehensive error estimation and optimization capabilities
Data Source
AI summary
A method for estimating torque control error at an electric machine considers the effects of current sensor error characteristics. Systems and methods can be practiced to determine the maximum sensor error that can be tolerated without causing unacceptable torque error. An example method uses sensor characteristics and machine characteristics to determine current sensing error, current control error, and torque control error. Determining the lowest sensor accuracy required for a desired torque control accuracy can facilitate the use of lower cost sensors in current-feedback controlled electric drive systems without compromising performance. Other applications can include vehicle diagnostics and torque error compensation.