Resolver Rotor Position Compensation for Abnormal AD Errors
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Solution Overview
Problem
Abnormal AD conversion errors in resolver-to-digital converters for environmentally friendly vehicles lead to errors in rotor position angle and speed estimation, reducing motor controllability and potentially disabling hybrid or electric vehicle functions.
Innovation Solution
A method that calculates and compensates for the current motor position angle by comparing changes in rotor position between sampling periods, using a calibration variable to determine when compensation is necessary, ensuring accurate rotor position information is maintained even in the absence of direct AD conversion data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If maximum torque operation is performed at high temperature and low speed, then motor power output is improved, but abnormal AD conversion errors occur in the RDC causing rotor position and speed estimation errors
Solution Approach 1:
The patent performs preliminary detection of abnormal AD conversion errors by monitoring the relationship between resolver output signals and motor operating conditions (temperature, speed, torque) before these errors cause motor control failures. This early detection allows the system to take preventive measures, such as switching to alternative control methods or alerting the operator, thereby maintaining reliable motor operation under maximum torque conditions without waiting for actual control failures to occur.
2Measurement precision
If resolver-to-digital converter is used to detect rotor position, then measurement capability is improved, but abnormal AD conversion errors cause loss of accurate position information
Solution Approach 1:
The patent implements a feedback mechanism that continuously monitors the resolver output signals and compares them against expected values based on motor operating conditions. When abnormal AD conversion errors are detected through this feedback loop, the system can identify the loss of accurate position information and trigger compensatory actions, such as using sensorless control algorithms or interpolating from previous valid measurements, thereby recovering the lost position information and maintaining continuous accurate rotor position tracking.
3Reliability
If conventional resolver failure detection method is used, then failure detection capability is improved, but abnormal AD conversion errors are not detected causing undetected control errors
Solution Approach 1:
The patent changes the detection parameters from simply monitoring resolver signal presence to analyzing the relationship between resolver output signals and motor operating parameters (temperature, speed, torque). By introducing these additional parameter dimensions to the detection process, the system can identify abnormal AD conversion errors that occur under specific operating conditions, thereby improving measurement precision in detecting abnormal errors while maintaining reliable failure detection capability across all operating ranges.
Data Source
AI summary
Disclosed is a technique for compensating for an abnormal output of a resolver. More specifically, a central processing unit (CPU) sets a current motor position angle before compensation θn,ORG as a current motor position angle θn and obtains a motor position change Δθn[rad] between a current sampling [n] and a previous sampling [n−1] and a motor position change Δθn-1[rad] between the previous sampling [n−1] and a more previous sampling [n−2]. Subsequently, a variable A is calculated based on the above angles. The CPU determines whether to perform the compensation by comparing the calculated variable A and a calibration variable K and calculates a current motor position angle for compensation θn[rad]. Finally, the CPU compensates for the absence of motor rotor position information with the calculated current motor position angle for compensation θn[rad].