Bidirectional Power Converter Eliminates Bulk Capacitors
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Solution Overview
Problem
Existing vehicle-to-grid integration systems face inefficiencies due to energy conversion losses, particularly in high power density applications, where conventional power converters require bulk energy storage elements that are costly and unsuitable for vehicle applications.
Innovation Solution
A bidirectional power converter for electric vehicles that performs AC to DC and DC to AC power conversion, eliminating the need for bulk energy storage elements by using a switch controller to synchronize with grid voltage signals and control switching duty cycles, allowing the vehicle to act as a distributed power source without large DC bus capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional power converters are used to achieve high power density, then power conversion capability is improved, but system size and cost increase due to bulk energy storage elements
Solution Approach 1:
The patent extracts and eliminates the bulk energy storage elements (large DC bus capacitors) from the power converter system. By using a three-stage converter architecture (AC-AC, DC-AC, and DC-DC converters) with synchronized control, the system achieves high power density without requiring large energy storage components, thus reducing system size while maintaining power conversion capability.
Solution Approach 2:
The patent changes the operating parameters and control strategy by implementing synchronized control of multiple converter stages. The switch controller synchronizes the switching duty cycles of all stages with the grid voltage signal, enabling efficient power conversion without bulk energy storage. This parameter change in control methodology allows the system to achieve high power density with reduced component size.
2Stability of the object's composition
If conventional power converters with bulk energy storage are used, then power stability is improved, but energy conversion efficiency deteriorates due to losses
Solution Approach 1:
The patent implements continuous synchronized control across all three converter stages, ensuring uninterrupted and efficient energy conversion. The switch controller continuously synchronizes the switching duty cycles with the grid voltage signal, maintaining continuous useful action in power conversion. This eliminates the need for bulk energy storage that causes losses, while maintaining power stability through continuous controlled operation.
Solution Approach 2:
The patent employs feedback control mechanisms where the switch controller monitors the grid voltage signal and adjusts the switching duty cycles of all converter stages accordingly. This feedback ensures power stability is maintained while optimizing energy conversion efficiency by dynamically adapting to grid conditions, eliminating losses associated with bulk energy storage elements.
3Adaptability or versatility
If bidirectional power conversion is implemented for vehicle-to-grid integration, then energy storage utilization is improved, but device complexity increases
Solution Approach 1:
The patent implements a universal three-stage converter system that can operate in multiple modes (charging, discharging, vehicle-to-grid). The same AC-AC, DC-AC, and DC-DC converter stages perform different functions depending on the operating mode, achieved through synchronized control of switching duty cycles. This multi-functionality improves energy storage utilization while managing device complexity through a unified control architecture.
Solution Approach 2:
The patent employs dynamic control where the switching duty cycles of all converter stages are continuously adjusted based on the desired operating mode. The switch controller dynamically synchronizes the operation of AC-AC, DC-AC, and DC-DC converters, enabling flexible bidirectional power flow. This dynamic adaptability improves energy storage utilization while the coordinated control manages overall system complexity.
Data Source
AI summary
A power converter can be controlled to generate a target output power based on a reactive power reference and an active power reference. The control process may include monitoring a time-varying power signal (e.g., a power grid voltage signal from a power grid), and filtering the time-varying power signal to derive a filtered sine component of the time-varying power signal and a filtered cosine component of the time-varying power signal. A sine coefficient and cosine coefficient each based on at least the reactive power reference and the active power reference can be determined, and applied to the filtered sine component and filtered cosine component of the time-varying power signal, respectively. A target current reference of the power converter can then be set to include a sum of the current reference sine component and the current reference cosine component.