Converter Control Reducing Flux Error and Harmonic Distortion
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Solution Overview
Problem
Existing converter control methods face challenges in achieving fast torque response with low harmonic distortion, as direct torque control leads to high harmonic distortion, and optimized pulse patterns result in long transients and harmonic excursions.
Innovation Solution
A method for controlling a converter that determines a switching sequence based on the actual state of the electrical system, modifies transition times to minimize flux errors, and applies the modified sequence to correct for assumptions made during optimization, thereby reducing harmonic distortion and achieving fast torque response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If direct torque control is used, then fast torque response is achieved, but harmonic distortion of stator currents and electromagnetic torque increases
Solution Approach 1:
The patent segments the control approach into two distinct parts: (1) pre-calculated optimized pulse patterns that minimize harmonic distortion, and (2) real-time correction values that adjust for actual operating conditions. This segmentation allows each part to optimize for its specific function without compromising the other.
Solution Approach 2:
The patent performs preliminary calculation of optimized pulse patterns offline before actual operation. These pre-calculated patterns are stored and ready for immediate application, eliminating the need for complex real-time optimization calculations while maintaining low harmonic distortion characteristics.
2Object-generated harmful factors
If optimized pulse patterns are applied, then current distortion is minimized, but transients become very long and harmonic excursions occur during operating point changes
Solution Approach 1:
The patent implements a feedback mechanism where the actual operating point is continuously monitored and compared with the pre-calculated optimized pulse patterns. Correction values are generated based on the difference between actual and reference operating points, enabling the system to adapt to transients while maintaining low harmonic distortion.
Solution Approach 2:
The patent makes the control system dynamic by allowing selection of different pre-calculated optimized pulse patterns based on the current operating point. When operating point changes are detected, the system dynamically switches to appropriate patterns and applies correction values, enabling fast response during transients while maintaining optimization during steady-state operation.
Data Source
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Figure 3
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AI summary
A converter (12) for an electrical system (10) is controlled in such a way, that switching sequences with switching time instants for the converter (12) that have been determined with respect to a certain first optimization goal are modified in a second step. A resultant flux error is determined. The switching time instants are modified to reduce the flux error.