Sensorless Rotating Machine Control with Decoupled Flux Estimation
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Solution Overview
Problem
Existing position sensor-less control methods for rotating machines face challenges in achieving highly responsive and accurate rotor position estimation due to interference between flux linkage computation and position estimate computation, particularly in methods that rely on stator currents and inductances.
Innovation Solution
A control device for rotating machines that includes a current detector, a position estimator, and a control unit to compute rotor position and rotational speed estimates, using stator voltage command values and a flux observer to update flux linkages, thereby preventing interference and enhancing accuracy and responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If flux linkages are computed by a flux observer on the basis of both stator voltages and stator currents, then rotor position estimation can be achieved, but interference occurs between rotor position estimation and flux linkage computation, degrading estimation accuracy and responsiveness
Solution Approach 1:
The patent divides the flux linkage computation into two independent parts: (1) a flux observer that computes flux linkages using only stator voltages and previous flux linkage values, and (2) a position estimator that uses these flux linkages along with stator currents for position estimation. This segmentation prevents interference between the two computation processes while maintaining the ability to estimate rotor position accurately.
Solution Approach 2:
The patent extracts the flux linkage computation from the position estimation process by having the flux observer compute flux linkages independently using only voltage information, then separating this from the position estimation that uses both flux linkages and current information. This extraction eliminates the interference that occurs when both computations share the same input variables.
2Productivity
If stator currents are used for both rotor position estimation and flux linkage computation, then both functions can be performed, but interference between the two computations prevents highly responsive and accurate position estimation
Solution Approach 1:
The patent segments the computation responsibilities by assigning the flux observer to handle only voltage-based flux linkage computation, while the position estimator handles the combined flux linkage and current-based position estimation. This segmentation allows the position estimation to use current information without interfering with the flux linkage computation, thereby achieving both high responsiveness and high accuracy.
Data Source
AI summary
A control device for a rotating machine includes a current detector that detects stator currents flowing through a stator of the rotating machine; a position estimator that computes a rotor position estimate and a rotational speed estimate on the basis of computed flux linkages of the rotating machine, the rotor position estimate being an estimated position of a rotor of the rotating machine, the rotational speed estimate being an estimated speed; a control unit that outputs stator voltage command values based on the stator currents and the rotor position estimate for driving the rotating machine; and a voltage application unit that applies drive voltages to the rotating machine on the basis of the stator voltage command values. The position estimator updates the computed flux linkages on the basis of the stator voltage command values, the rotational speed estimate, and the most recent computed flux linkages.