Multiport DC-DC Converter for Bidirectional EV Power Flow
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Solution Overview
Problem
Existing DC-DC converters for electrified vehicles are limited by single output ports, lack bidirectional power transfer capability, inefficient switch economy, poor integration of energy sources, and inadequate flexibility in power flow management, which restricts their effectiveness in dynamic power scenarios.
Innovation Solution
A non-isolated multiport DC-DC converter with five ports integrating fuel cell, battery, and ultracapacitor, along with traction and auxiliary loads, utilizing high and low frequency switches and inductors for flexible power management, enabling single-stage power processing and bidirectional power transfer across multiple ports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-output DC-DC converter is used, then the device complexity is reduced, but the adaptability to integrate multiple load types is limited
Solution Approach 1:
The DC-DC converter is designed with multiple independent output ports (first output port and second output port) that can simultaneously connect to different load types (traction load and auxiliary loads). This multi-functional design allows a single converter device to serve multiple purposes and integrate various load types without requiring separate converters for each load, thus improving adaptability while maintaining relatively simple device structure.
2Adaptability or versatility
If dedicated inductors are provided for each input energy source, then the power flow management flexibility is improved, but the device complexity and component count increase
Solution Approach 1:
The converter uses a single inductor that is shared across multiple input energy sources (fuel cell and battery) rather than providing dedicated inductors for each source. This inductor is configured to handle power flow from any combination of input sources through appropriate switching arrangements, thereby reducing the total component count and device complexity while maintaining the flexibility to manage power flow between multiple energy sources and loads.
3Loss of energy
If regenerative braking energy is not recovered, then the system simplicity is maintained, but the energy loss increases
Solution Approach 1:
The converter enables recovery of regenerative braking energy by allowing bidirectional power flow where the traction load can return energy to the battery during braking events. The switching mechanism directs the regenerative energy from the traction load through the inductor and switches back to charge the battery, converting what would otherwise be wasted energy into a useful resource. This is achieved through intelligent power flow management without requiring additional hardware beyond the existing converter components.
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
Enhances power delivery and regenerative power recuperation, supports diverse dynamic load scenarios, and optimizes energy source utilization through flexible power flow management and efficient component integration.
Implementation Method 1
periodically energizing or de-energizing the inductor(s) to accomplish the desired mode of operation
Implementation Method 2
integrating multiple energy sources like fuel cell, battery and ultracapacitor
Implementation Method 3
integrating multiple energy sources like fuel cell, battery and ultracapacitor
Implementation Method 4
integrating multiple energy sources like fuel cell, battery and ultracapacitor
Data Source
AI summary
The technology described herein discloses a non-isolated multiport dc-dc converter with three input dc ports to integrate three different energy sources namely fuel cell, battery and ultracapacitor, and two dedicated output ports for traction load and auxiliary loads, respectively. The invented system is capable of providing high flexibility in power flow management among the three energy sources, corresponding to diverse dynamic load power events encountered in an EV. Besides, the system exhibits prominent features like simultaneous and bidirectional power transferring capability between the multiple dc ports and single stage power processing in every possible power flow scenarios. Furthermore, the technology embodies distinct operating modes depending upon the dynamic load power variations and state of voltage levels of the energy sources. Nevertheless, the technology aims at improving the utilization efficiency of the energy storage system by maneuvering power flows between multiple dc ports, thereby augmenting the overall performance of EV powertrain.