AC Rotating Machine Current Control to Prevent Integrator Windup
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Solution Overview
Problem
Existing control devices for AC rotating machines face instability due to windup in integrators, leading to reduced control accuracy and overshoot.
Innovation Solution
A control device for AC rotating machines that includes an inverter, a current detector, and calculators for voltage command values on two rotational axes, performing integral calculations using deviations between command and detected currents to stabilize control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple integrators are used in voltage command value calculators for two rotational axes, then control accuracy is improved, but integrator windup occurs causing control instability and overshoot
Solution Approach 1:
The patent segments the calculation of voltage command values by axis. The d-axis voltage command value calculator and q-axis voltage command value calculator are separated into independent functional units, each performing integral calculations only for its respective axis without interfering with the other axis calculations, thereby preventing integrator windup while maintaining control accuracy
Solution Approach 2:
The patent extracts the integral calculation function from a unified voltage command value calculator and creates separate integral calculation units for the d-axis and q-axis. This extraction allows each axis to have its own dedicated integrator that does not suffer from windup caused by calculations for the other axis
2Reliability
If anti-windup limiting is applied to integral terms, then control stability is improved, but calculation complexity increases when multiple integrators are involved
Solution Approach 1:
The patent segments the control system into independent d-axis and q-axis voltage command value calculators. Each calculator has its own integral calculation unit that processes only its axis deviations, eliminating the need for complex anti-windup mechanisms while maintaining stability through architectural simplicity
3Measurement precision
If integral calculations use deviations from both axes, then control precision is improved, but integrator windup causes overshoot and reduces stability
Solution Approach 1:
The patent segments the deviation processing by creating separate calculation paths: the d-axis voltage command value calculator uses only d-axis current deviation for its integral calculation, and the q-axis voltage command value calculator uses only q-axis current deviation. This segmentation maintains control precision while preventing cross-axis interference that causes windup
Solution Approach 2:
The patent applies local quality by making each voltage command value calculator specialized for its axis. The d-axis calculator has the property of processing only d-axis deviations, and the q-axis calculator processes only q-axis deviations, giving each component a specific functional quality that prevents windup while maintaining overall control precision
Data Source
AI summary
A control device of an AC rotating machine includes an inverter, a current detector, a first axis voltage command value calculator, and a second axis voltage command value calculator. The first axis voltage command value calculator performs an integral calculation using a first deviation that is a deviation between a current command value on the first axis and a detected current value of the rotating machine current on the first axis, and a second deviation that is a deviation between a current command value on the second axis and a detected current value of the rotating machine current on the second axis, and calculates the voltage command value of the first axis on the basis of the result of the integral calculation.