Rotary Electric Machine Control Using Output-Based Conversion Map
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Solution Overview
Problem
Existing methods for controlling rotary electric machines face challenges in accurately determining current or voltage command values near constant power lines, requiring large numbers of maps and reducing torque accuracy due to complexity and memory limitations.
Innovation Solution
A method that uses a conversion map to calculate electric control amounts based on the rotation speed and DC voltage of a rotary electric machine, applying a ratio between the particular DC voltage and rotation speed to determine the electric control amount, allowing for accurate control without needing numerous maps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple torque-current command maps are used to improve control accuracy near constant power line, then control precision is improved, but device complexity increases
Solution Approach 1:
The patent changes the parameter used for map selection from torque to output. By using output-based conversion maps instead of torque-based maps, the system achieves accurate control near constant power lines with a single map, eliminating the need for multiple torque-current command maps and their associated complexity
Solution Approach 2:
The patent creates a universal conversion map that works for all operating conditions including near constant power lines. This single output-based conversion map replaces multiple specialized torque-current command maps, providing multi-functional capability across different operating regions without requiring separate maps for each condition
2Measurement precision
If a large number of maps are stored in memory to improve control accuracy, then control precision is improved, but memory requirements increase
Solution Approach 1:
By changing from torque-based mapping to output-based mapping, the patent reduces memory requirements from storing multiple torque-current command maps to storing a single conversion map. This parameter change eliminates the need for large memory capacity while maintaining control accuracy across all operating conditions
3Measurement precision
If complex theoretical determination methods are used to improve control accuracy, then control precision is improved, but calculation speed decreases
Solution Approach 1:
The patent simplifies the control method by changing from complex theoretical determination to simple map lookup based on output. This allows the controller to quickly determine current command values through direct map consultation rather than performing complex calculations, achieving both high accuracy and fast response
Solution Approach 2:
The patent performs preliminary work by creating the output-based conversion map in advance, which contains pre-calculated optimal current command values for various operating conditions. During actual control operation, the system only needs to lookup values from this pre-prepared map, eliminating the need for complex real-time calculations
4Stability of the object's composition
If torque is reduced to maintain rotation speed in existing methods, then rotation speed stability is improved, but torque accuracy decreases
Solution Approach 1:
The patent changes the fundamental parameter from torque to output for map-based control. By using output-based conversion maps, the system can accurately control both torque and rotation speed without the trade-off inherent in torque-based methods. The conversion map directly provides optimal current commands that achieve both speed stability and torque accuracy simultaneously
Data Source
AI summary
A method of controlling a rotary electric machine, which is configured to supply an electric control amount to a power conversion unit, which is configured to convert a DC voltage from a power source into a drive current to the rotary electric machine in accordance with the electric control amount, the method including: using a conversion map, which is used to calculate the electric control amount based on a rotation speed of the rotary electric machine at a particular DC voltage of the rotary electric machine and a required command value; and calculating the electric control amount in accordance with a ratio between the particular DC voltage and the rotation speed of the rotary electric machine in determining the electric control amount in accordance with the conversion map.