Three-Winding Power Conversion Topology for Dual EV Battery Charging
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Solution Overview
Problem
Existing power conversion topologies for electric vehicles are costly and large due to the need for separate OBC circuits and DC-DC converters for charging HV and LV batteries, which also increase the size and complexity.
Innovation Solution
A three-winding transformer-based power conversion topology that integrates the functions of the OBC circuit and DC-DC auxiliary converter, using a GR-rectifier, HV-rectifier, and LV-rectifier, along with an auxiliary inductor and filters to reduce size and cost, and enhance power density by electromagnetically interacting windings and employing bidirectional designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If separate OBC circuit and DC-DC converter are used for charging HV and LV batteries, then charging function is achieved, but device complexity and size increase
Solution Approach 1:
The patent combines the OBC circuit and DC-DC converter into a single integrated power conversion topology with a unified control system. The primary winding connects to the utility grid through a GR-rectifier, the secondary winding charges the HV-battery through an HV-rectifier, and the tertiary winding charges the LV-battery through an LV-rectifier, all controlled by one controller that manages power distribution between batteries based on their respective charging requirements.
Solution Approach 2:
The integrated power conversion topology serves multiple functions simultaneously: it acts as an OBC circuit for charging the HV-battery from the utility grid, as a DC-DC converter for charging the LV-battery from the HV-battery, and as a power management system that can independently control charging of either or both batteries. This multi-functional design eliminates the need for separate dedicated circuits for each function.
2Ease of manufacture
If separate OBC circuit and DC-DC converter are used, then charging capability is provided, but cost increases
Solution Approach 1:
The patent merges the OBC circuit and DC-DC converter into a single integrated power conversion topology. The controller统一管理 (unified management) the power flow from the utility grid through the primary winding, and distributes it to the HV-battery via the secondary winding and to the LV-battery via the tertiary winding, eliminating the need for separate control systems and reducing overall component count.
Solution Approach 2:
The integrated topology provides universal charging capability for both HV and LV batteries through a single system. The controller can independently regulate power delivery to each battery type, maintaining full charging functionality while reducing manufacturing cost through component consolidation and shared control architecture.
3Volume of stationary object
If three-winding transformer is used to integrate OBC and DC-DC functions, then device size is reduced, but current density increases
Solution Approach 1:
The patent uses a three-winding transformer where the primary winding connects to the utility grid, the secondary winding to the HV-battery, and the tertiary winding to the LV-battery. This integration reduces the overall device size by eliminating separate transformers and control circuits, while the controller manages current distribution to balance density across windings.
Solution Approach 2:
The controller dynamically adjusts operating parameters including switching frequencies, duty cycles, and phase angles to optimize current distribution across the three windings. By changing these parameters, the system maintains appropriate current density levels despite the compact integrated structure, preventing excessive heating and stress in any single winding.
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
This solution reduces the size and cost of the power conversion topology, decreases the RMS and peak values of the LV-side current, and allows for independent charging of HV and LV batteries while enabling bidirectional energy flow, thus improving power density and operational efficiency.
Implementation Method 1
the primary winding, the secondary winding and the tertiary winding interact electromagnetically with each other
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a power conversion topology (7) for charging a HV-battery (4) and/or a LV-battery (5) of an electric vehicle (1). The power conversion topology (7) comprises: - a three-winding transformer (16) with a primary winding (16a), a secondary winding (16b), and a tertiary winding (16c); - a GR-rectifier (9), a HV-rectifier (10) and a LV-rectifier (13).