Parallel PFC Converter Topology for Bidirectional EV Power Flow
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Solution Overview
Problem
Existing power conversion devices for electric vehicles require additional DC-AC inverters for bidirectional power transmission, increasing costs and reducing efficiency, especially when using expensive switching elements like SiC or GaN.
Innovation Solution
A power conversion device with a diode rectifier-based PFC converter in parallel with a totem-pole bridgeless PFC converter, allowing bidirectional power supply without an additional DC-AC inverter, using Si-MOSFETs and GaN-FETs to minimize costs and losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a totem-pole bridgeless PFC converter is used to enable bidirectional power transmission, then the need for additional DC-AC inverters is eliminated and power conversion efficiency is improved, but the number of switching elements increases significantly and costs increase when using expensive switching elements like SiC or GaN
Solution Approach 1:
The power conversion device is divided into two separate PFC converters operating in parallel: a first PFC converter with diode rectifier for unidirectional power flow, and a second PFC converter with totem-pole bridgeless configuration for bidirectional power flow. This segmentation allows each converter to be optimized for its specific function, reducing the overall complexity compared to a single full bidirectional converter.
Solution Approach 2:
The second PFC converter is configured to operate in bidirectional mode only when needed (excessive action), while the first PFC converter handles the primary unidirectional charging function. This partial application of bidirectional capability reduces the need for expensive switching elements while maintaining versatility when required.
2Ease of manufacture
If a diode bridge is used for rectification in the PFC converter, then the implementation cost is reduced, but bidirectional power transmission is prevented requiring an additional DC-AC inverter
Solution Approach 1:
The system segments the rectification function into two paths: the first PFC converter uses a simple diode bridge for cost-effective unidirectional rectification, while the second PFC converter uses a more complex totem-pole bridgeless configuration for bidirectional capability. This segmentation allows the system to achieve bidirectional functionality without requiring all components to be expensive.
Solution Approach 2:
The second PFC converter with totem-pole bridgeless configuration serves multiple functions: it can operate in bidirectional mode when AC outlet functionality is needed, and can also contribute to unidirectional charging. This multi-functionality reduces the need for separate DC-AC inverter hardware while maintaining versatility.
3Adaptability or versatility
If multiple switching elements made of SiC or GaN are used in the totem-pole bridgeless PFC converter, then bidirectional power transmission is enabled, but the manufacturing cost increases significantly
Solution Approach 1:
The system segments the bidirectional functionality to only the second PFC converter, allowing the use of expensive SiC or GaN switching elements only where necessary for bidirectional operation, rather than requiring all switching elements in the system to be expensive wide-bandgap devices.
Solution Approach 2:
Different quality levels of switching elements are used in different parts of the system: the first PFC converter uses standard, lower-cost switching elements with diode rectification, while the second PFC converter uses high-quality SiC or GaN switching elements only in the specific totem-pole bridgeless configuration where bidirectional capability is required.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables bidirectional power supply with low loss and low costs, eliminating the need for additional DC-AC inverters and reducing harmonic currents and noise during charging and power output.
Implementation Method 1
a first power factor correction (PFC) converter and a second PFC converter that are coupled to the AC voltage input terminal
Implementation Method 2
a second PFC converter includes a totem-pole bridgeless PFC converter
Data Source
AI summary
When a secondary battery is charged, a switch is closed, and a first boost chopper circuit, a second boost chopper circuit, and a totem-pole bridgeless power factor correction circuit, which are coupled in parallel to each other, are driven to operate in an interleaving manner, and in this state, an alternating-current voltage inputted from an AC input terminal is converted into a direct current, and the direct current is outputted from a direct current output terminal. When alternating current is outputted using an AC output terminal, the switch is closed, and the totem-pole bridgeless PFC circuit is used, and in this state, a DC voltage from the secondary battery is converted into an alternating current, and the alternating current is outputted from the AC output terminal.