Electric Motor Auto-Tuning Using Virtual Damping Feedback
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Solution Overview
Problem
Existing static auto-tuning methods for electric motors are complex, calculation intensive, and costly, with limited accuracy and safety concerns due to unpredictable rotor displacement and speed response during tuning.
Innovation Solution
A less complex and less costly static auto-tuning system and method that uses a closed-loop feedback mechanism and a virtual damping coefficient to accurately determine inertia and friction coefficient values, and subsequently calculate gains for improved motor control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional static auto-tuning methods are used to determine motor characteristics, then estimation accuracy is improved, but device complexity and computational requirements increase significantly
Solution Approach 1:
The patent extracts only the essential information needed for accurate estimation by using peak detection of the speed response signal rather than performing comprehensive spectral analysis. This removes unnecessary computational complexity while retaining the core functionality of characterizing system dynamics.
Solution Approach 2:
Instead of using complex signal processing to extract parameters from noisy data, the patent inverts the approach by designing an excitation signal that produces a clean, measurable speed response with distinct peaks. The system characteristics are derived from the timing and magnitude of these peaks rather than from complex spectral decomposition.
2Measurement precision
If complex signal processing algorithms like FFT are used to reduce noise effects, then measurement precision is improved, but device complexity and processing requirements increase
Solution Approach 1:
The patent applies preliminary action by designing the excitation signal characteristics in advance to inherently produce a speed response with clearly distinguishable peaks. This pre-planned signal structure eliminates the need for complex post-processing noise reduction algorithms, as the measurement signal itself is optimized for clarity.
3Productivity
If vibrational torque command is used to estimate parameters in frequency domain, then productivity of parameter estimation is improved, but reliability decreases due to unpredictable rotor displacement and speed response
Solution Approach 1:
The patent implements feedback by continuously monitoring the speed response during the tuning process and using this information to determine when parameter estimation is complete. The closed-loop feedback ensures that the excitation signal is applied only when safe and that the process can be terminated if abnormal conditions occur, thereby improving reliability while maintaining productivity.
Data Source
AI summary
A static auto-tuning system and method for controlling operation of a motor in a system. A speed reference signal is generated resulting in a speed response of the motor. Closed-loop feedback magnifies the rotating friction effect to an observable level. Inertia and rotating friction coefficient values of the system are estimated based on the speed frequency response and a virtual damping coefficient. A fixed low frequency speed signal may result in a first frequency response function for determining virtual damping, and a variable frequency excitation signal may result in a second frequency response function for determining the inertia and rotating friction characteristics. Closed-loop gains are determined based on these characteristics. The excitation signal may be sampled and a peak value in each interval may be identified and stored to produce an envelope of peak values for determining the gain response. Operation of the motor is controlled using the determined gains.