Inverter Control via AC Pulsation Feedback
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Solution Overview
Problem
Existing power conversion systems face challenges in suppressing the beat phenomenon in inverters due to rectification ripple, requiring complex control systems and high-performance microcomputers, which increases costs and complexity.
Innovation Solution
A power conversion system that detects pulsation at the AC side, using current detecting means and pulsation detecting means to correct the phase, frequency, amplitude, and pulse position of the voltage output from the inverter, thereby simplifying the control system and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If DC voltage pulsation detection and feed-forward compensation is used to suppress inverter beat phenomenon, then current pulsation can be reduced, but phase compensation complexity increases and individual motor adjustment is required
Solution Approach 1:
Instead of detecting DC voltage pulsation and compensating in advance, this patent detects AC current pulsation at the inverter output and uses feedback compensation. The pulsation detection unit monitors the actual AC current pulsation caused by rectification ripple, and the control unit adjusts the inverter output based on this detected pulsation, reversing the conventional approach from feed-forward to feedback control.
Solution Approach 2:
The patent implements a feedback mechanism where the pulsation detection unit continuously monitors AC current pulsation at the inverter output, and the control unit uses this information to dynamically adjust the inverter output voltage frequency and phase. This closed-loop feedback system automatically compensates for pulsation without requiring manual phase adjustment or individual motor calibration.
2Object-generated harmful factors
If complex component separation calculation and multiple integrators are used to generate output voltage phase angle compensation, then torque pulsation can be reduced, but control system complexity and microcomputer capacity requirements increase
Solution Approach 1:
The patent extracts only the essential pulsation component from the AC current for compensation purposes, rather than performing complete component separation analysis. The pulsation detection unit identifies the specific pulsation frequency and amplitude caused by rectification ripple, and the control unit applies targeted compensation only for this extracted pulsation component, avoiding the need for complex Sin-wave calculators, Cos-wave calculators, and multiple integrators.
Solution Approach 2:
Instead of implementing complete sine wave generation with multiple calculators and integrators, the patent applies partial action by using simplified calculation that focuses only on the dominant pulsation component. The control unit generates compensation signals based on the detected pulsation characteristics without requiring full sinusoidal decomposition, reducing microcomputer processing requirements while achieving sufficient torque pulsation suppression.
3Measurement precision
If high-speed processing and enhanced microcomputer capability are implemented to achieve accurate sine wave calculation, then control precision is improved, but system cost increases
Solution Approach 1:
The patent changes the computational parameters from requiring high-speed accurate sine wave generation to using simplified pulsation-based compensation calculations. By focusing on detecting and compensating the specific pulsation frequency and amplitude rather than generating complete sine waves, the microcomputer can use lower processing speed and smaller capacity while maintaining sufficient control precision for suppressing torque pulsation.
Data Source
AI summary
A power conversion system includes a first power converter converting AC to DC, a second power converter converting DC to AC, a current detector detecting output current of the second power converter, a pulsation detector detecting a pulsating component associated with the AC to DC conversion of the first power converter from a pulsating component contained in at least any one of effective power, power, and apparent power of the second power converter, a voltage corrector outputting a correction amount correcting at least one of phase, frequency, and amplitude of a voltage output from the second power converter based on the pulsating component from the pulsation detector, and a voltage controller outputting a voltage instruction to be output from the second power converter based on the correction amount from the voltage corrector, wherein the second power converter converts DC to AC based on the voltage instruction from the voltage controller.