AC Rotary Machine Controller Flux-Based Voltage Command
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Solution Overview
Problem
Existing AC rotary electric machine controllers fail to accurately control interlinkage fluxes of d-axis and q-axis, which change mutually with currents of both axes due to nonlinear magnetic saturation characteristics, leading to deteriorated control accuracy.
Innovation Solution
A controller for AC rotary electric machines that includes a rotation detection unit, interlinkage flux command calculation, model response calculation, two-axis voltage command calculation, and switching control units, which calculate voltage command values based on interlinkage flux model response values and electrical angle speed to consider the mutual changes of interlinkage fluxes, allowing for linear calculation processing and improved control accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional current feedforward control using d-axis and q-axis inductance is used, then calculation is simplified, but control accuracy deteriorates due to inability to consider mutual changes of interlinkage fluxes
Solution Approach 1:
The patent changes the control parameters from current-based (Id, Iq) to interlinkage flux-based (ψd, ψq). By using interlinkage flux command values and their model response values instead of current values, the control system can accurately represent the nonlinear magnetic saturation characteristics while maintaining manageable calculation complexity through the use of pre-established mathematical models.
Solution Approach 2:
The patent introduces interlinkage flux as an intermediary parameter between the control input and the actual current. The interlinkage flux command calculation unit and model response calculation unit act as intermediaries that transform the control objectives into accurate voltage commands, bridging the gap between simplified calculation and high precision control.
2Measurement precision
If interlinkage flux model response values are used for voltage command calculation, then control accuracy improves by considering nonlinear characteristics, but calculation processing load increases
Solution Approach 1:
The patent performs preliminary actions by pre-establishing the mathematical models for interlinkage flux command calculation and model response calculation. These models are prepared in advance and stored in the control system, allowing the runtime calculation to simply evaluate these pre-defined models rather than computing complex nonlinear relationships from scratch, thereby reducing the actual processing load during operation.
Solution Approach 2:
The patent uses model response values as copies or approximations of the actual interlinkage flux behavior. Instead of directly measuring or computing the complex nonlinear interlinkage flux in real-time, the system creates a simplified mathematical copy (model response) that captures the essential behavior, enabling accurate control with reduced computational burden.
Data Source
AI summary
To provide a controller for AC rotary electric machine which can control considering the interlinkage fluxes of first-axis and second-axis which change mutually according to the currents of first-axis and second-axis, such as d-axis and q-axis. A controller for AC rotary electric machine calculates interlinkage flux model response values of first-axis and second-axis by performing a response delay processing of a model response to the interlinkage flux command values of first-axis and second-axis; and calculates voltage command values of first-axis and second-axis which make interlinkage fluxes of first-axis and second-axis change to the interlinkage flux model response values of first-axis and second-axis in a feedforward manner, based on the interlinkage flux model response values of first-axis and second-axis, and the electrical angle speed.