Single-Stage Power Converter Control for Low Output Ripple
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Solution Overview
Problem
Power converters face challenges with high losses and volume due to two conversion stages, reliance on bulky electrolytic capacitors and inductors, and complex control schemes in cyclo-converters, limiting lifetime and efficiency.
Innovation Solution
A power converter with a switching circuit and controller that adjusts the length of alternating intermediate voltage periods based on measured output voltage to reduce ripple and enhance compatibility with variable power loads, using a switching circuit with bi-directional switches and DC-block capacitors, and a control method that identifies and balances input voltages to generate intermediate voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If two conversion stages (PFC and isolated DC/DC) are used to achieve target power density and efficiency, then power conversion performance is improved, but losses and volume increase
Solution Approach 1:
The patent combines the PFC and isolated DC/DC conversion functions into a single integrated power converter stage. The switching circuit processes three-phase AC input directly to generate the output voltage, eliminating the need for separate PFC and DC/DC stages while maintaining both power factor correction and isolation functions in one unified architecture.
Solution Approach 2:
The single power converter stage performs multiple functions simultaneously: it provides power factor correction, voltage conversion, and galvanic isolation. The switching circuit is designed to handle both PFC and DC/DC conversion requirements within the same operational framework, making the system more versatile and efficient.
2Reliability
If electrolytic capacitors and PFC inductors are used as energy storage elements to achieve reliable power conversion, then power conversion stability is improved, but device weight and volume increase
Solution Approach 1:
The patent removes the electrolytic DC link capacitor and PFC inductors from the converter architecture. Instead of using these bulky energy storage elements, the design relies on the switching circuit topology and control methodology to achieve stable power conversion without requiring large capacitors or inductors.
Solution Approach 2:
The patent changes the operational parameters of the power converter by using a switching frequency and control strategy that eliminates the need for large energy storage components. The alternating intermediate voltage generation and period adjustment enable the system to maintain stability without relying on traditional bulky energy storage elements.
Data Source
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AI summary
A controller for a power converter, and a method for operating a power converter is provided. The power converter comprises a switching circuit configured to receive alternating input voltages, and having switches connected to respective alternating input voltages and controllable to generate an alternating intermediate voltage. Furthermore, the power converter comprises a transmitter and rectifier circuit. For each period of the alternating intermediate voltage, the control scheme comprises the identification with the greatest and second alternating input voltages or greatest and second greatest line-to-line voltages, and then controlling the switching circuit to generate the alternating intermediate voltage based on the identified voltages. The length of the period of the alternating intermediate voltage is then adjusted for subsequent periods of the alternating intermediate voltage based at least in part on a measured value of the output voltage. Accordingly, an output control variable of the power converter (e.g., output voltage, output current, output power) may have a reduced ripple, and thus the power converter may be compatible with variable power loads.