Rotor Position Validation in Unsynchronized Electric Machines
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Solution Overview
Problem
Existing methods for validating the angular position of a rotor in electric machines, particularly in unsynchronized architectures, fail to ensure the accuracy and safety of the position validation, leading to potential unsafe events like untimely acceleration or braking.
Innovation Solution
A method that generates an excitation signal by the angular position calculation means and retrieves it by the on-board control unit, allowing for the estimation of the angular position at a second instant based on the elapsed time and rotor speed, to determine if the deviation between the calculated and measured positions is within a predetermined threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the excitation signal is generated by the angular position calculation means and retrieved by the on-board control unit in a non-synchronized manner, then the device complexity is reduced and ease of operation is improved, but the measurement precision and reliability of angular position validation deteriorate due to time delays
Solution Approach 1:
The method performs preliminary actions by storing the rotor speed value and the angular position value determined at the first instant, and by calculating the elapsed time between the first and second instants before validating the angular position. This preparation of data in advance allows the validation to account for time delays without requiring synchronized operation, thus maintaining measurement precision while enabling easier operation.
Solution Approach 2:
The method introduces an intermediary calculation step that computes the expected angular position at the second instant by combining the stored angular position, rotor speed, and elapsed time. This intermediary value serves as a reference to validate whether the angular position determined at the second instant is correct, bridging the gap caused by non-synchronized operation between the excitation signal generation and position validation.
2Reliability
If the angular position is determined at different instants by the angular position calculation means and the on-board control unit, then the reliability of position validation is improved through comparison, but the time difference between measurements causes accuracy deterioration
Solution Approach 1:
The method performs preliminary actions by storing the rotor speed value and the angular position value determined at the first instant, and by calculating the elapsed time between the first and second instants before validating the angular position. This preparation of data in advance allows the validation to account for time delays without requiring synchronized operation, thus maintaining measurement precision while enabling easier operation.
Solution Approach 2:
The method introduces an intermediary calculation step that computes the expected angular position at the second instant by combining the stored angular position, rotor speed, and elapsed time. This intermediary value serves as a reference to validate whether the angular position determined at the second instant is correct, bridging the gap caused by non-synchronized operation between the excitation signal generation and position validation.
3Adaptability or versatility
If the rotor speed varies between the first and second instants, then the adaptability of the system to dynamic conditions is improved, but the measurement precision of angular position validation deteriorates due to the assumption of constant speed
Solution Approach 1:
The method applies partial action by using the rotor speed value determined at the first instant as an approximation for the speed during the interval between the first and second instants. While this assumes constant speed and may introduce some error when speed varies, it provides a practical solution that maintains system adaptability to dynamic conditions while achieving sufficient measurement precision for safety validation purposes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Ensures the validity of the angular position in unsynchronized architectures, preventing unsafe events by accurately compensating for the time difference between position determination and measurement, thereby enhancing the safety and reliability of electric machine control.
Implementation Method 1
The resolver functions as a rotary electrical transformer. It consists of three coils: a primary coil 1, and two secondary coils 2 and 3, labeled cos and sin. The resolver's rotor 4 acts as a variable flux.
Data Source
Figure 1~2
AI summary
Method for validating the angular position of the rotor of an electric machine for a motor vehicle equipped with an on-board control unit and a means for measuring the components of the angular position of the rotor capable of delivering signals proportional to the sine and cosine of the angular position of the rotor, in which an excitation signal of the means for measuring the components of the angular position of the rotor is generated by the means for calculating the angular position and retrieved by the on-board control unit in a non-synchronized manner, the angular position of the rotor is estimated as a function of the components of the angular position of the rotor and the excitation signal.The process includes the following steps: the time elapsed between the determination of the angular position of the rotor by the calculation means at a first instant and the measurement of the components of the angular position of the rotor by the on-board control unit at the second instant is determined; the value of the angular position that the calculation means would have determined at the second instant, synchronized with the excitation signal, is estimated; the angular position is determined to be valid if the difference between this angular position estimated at the time of the emission of the excitation signal and the angular position of the rotor determined by the calculation means is less than a predetermined threshold.