Rotary Electric Machine Controller Using Polynomial Loss Coefficients
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Solution Overview
Problem
Existing rotary electric machine drive apparatus controllers face high data-processing loads and memory requirements due to the need to calculate power losses using map data for multiple voltage candidates, leading to increased costs and complexity.
Innovation Solution
A controller that calculates a voltage command value for a rotary electric machine drive apparatus by using polynomial coefficients to represent power loss characteristics, reducing the need for extensive map data and minimizing data-processing loads, and sets the voltage command value to minimize total power loss within a specified range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If map data of each power loss is used to calculate power loss for multiple voltage candidates, then search accuracy for minimum power loss voltage is improved, but data-processing load and memory requirements increase significantly
Solution Approach 1:
The patent changes the representation parameters of power loss characteristics from detailed map data to simplified polynomial coefficients. By expressing converter loss and inverter loss as polynomial functions of voltage and current respectively, the system maintains sufficient accuracy for finding minimum power loss voltage while dramatically reducing data-processing load and memory requirements.
Solution Approach 2:
The patent extracts only the essential characteristics needed for optimization by separating converter loss and inverter loss into distinct polynomial representations. This extraction allows the system to focus on voltage optimization without carrying the burden of complete map data, achieving the goal with minimal necessary information.
2Measurement precision
If the number of voltage candidates is increased to improve search accuracy, then minimum power loss voltage determination is improved, but data-processing load increases
Solution Approach 1:
By changing from discrete map data to continuous polynomial functions, the system achieves accurate power loss calculation without needing to evaluate multiple discrete voltage candidates. The polynomial representation allows analytical or efficient numerical optimization, reducing the number of calculations required while maintaining or improving accuracy.
3Measurement precision
If map data of converter power loss is provided finely for every DC voltage, output voltage, and output power, then power loss calculation accuracy is improved, but amount of memories and data-processing load increase significantly
Solution Approach 1:
The patent transforms the storage requirement from detailed multi-dimensional map data to simple polynomial coefficients. Converter loss is represented as a polynomial function of voltage with coefficients stored in memory, dramatically reducing the quantity of stored data while maintaining calculation accuracy through the mathematical model.
Solution Approach 2:
Instead of storing complete power loss maps and looking up values, the patent inverts the approach by storing compact polynomial coefficients that can generate power loss values on-demand. This inversion reduces memory requirements while maintaining the ability to calculate accurate power loss for any operating point.
Data Source
AI summary
There is provided a controller for a rotary electric machine drive apparatus capable of reducing data-processing load and amount of memories required for a data processing which calculates a voltage command value of the converter which reduces power loss. A controller calculates the required minimum voltage which is required in the case of performing a maximum torque/current control is calculated; calculates a converter loss coefficient which is a coefficient of a polynomial representing a power loss characteristic of the converter; calculates an inverter loss coefficient which is a coefficient of a polynomial representing a power loss characteristic of the inverter; calculates a sum total of loss coefficients for each order of polynomials; calculates the low loss voltage which the sum total power loss becomes a minimum, based on the sum total loss coefficients for each order; sets to the voltage command value of the converter.