DC-DC Converter Bypass Topology for Wide-Voltage Battery Charging
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Solution Overview
Problem
Existing DC-DC converters face inefficiencies in charging battery packs with varying voltage capabilities, particularly during high-voltage charging, due to high current requirements and voltage boosting losses.
Innovation Solution
A DC-DC converter with a bypass connection that directly connects a switching pair to the battery pack, incorporating a dual active bridge (DAB) configuration and an inductor-capacitor (LC) circuit, reducing current flow and enhancing efficiency by bypassing traditional boost stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If traditional voltage boosting methods are used in DC-DC converters, then high voltage charging capability is achieved, but current flow increases and efficiency decreases
Solution Approach 1:
The battery-side bridge is segmented into multiple switching pairs (first switching pair, second switching pair, third switching pair) with distinct functions. The first switching pair handles direct connection for low-voltage charging, while the second and third switching pairs handle voltage boosting for high-voltage charging. This segmentation allows the system to optimize the current path based on charging requirements, reducing unnecessary current flow through boosting circuitry when not needed.
Solution Approach 2:
The converter dynamically switches between different operating modes by controlling the state of the first power switch. When the battery voltage is low, the first power switch connects the first switching pair directly to the output node, enabling direct charging without boosting. When the battery voltage is high, the first power switch disconnects, and the second and third switching pairs are activated for voltage boosting. This dynamic reconfiguration optimizes efficiency across varying battery voltage conditions.
2Adaptability or versatility
If DC-DC converters are designed to support varying battery voltage capabilities, then versatility is improved, but device complexity increases
Solution Approach 1:
The DC-DC converter is designed with multi-functionality to handle both low-voltage and high-voltage charging scenarios using a unified circuit architecture. The same battery-side bridge with three switching pairs can operate in direct-connection mode for low-voltage batteries or voltage-boosting mode for high-voltage batteries. The isolation circuit and control processor enable the system to adapt to different battery voltage capabilities without requiring separate dedicated circuits for each voltage level.
Solution Approach 2:
The control processor acts as an intermediary that manages the complexity of supporting multiple voltage capabilities. It monitors battery voltage levels and automatically configures the switching pairs and power switches accordingly. This intelligent control layer simplifies the overall system design by providing a unified interface that handles the complexity of multi-voltage support, allowing the hardware to remain relatively simple while achieving high versatility.
3Productivity
If high charging power is delivered to battery packs, then charging speed is improved, but current requirements increase
Solution Approach 1:
The converter changes the voltage parameter dynamically based on battery needs. By using the first switching pair for direct connection during low-voltage charging, the system delivers power at lower voltage with correspondingly lower current. When high-voltage charging is needed, the second and third switching pairs boost the voltage, reducing the current required to deliver the same power level. This parameter change strategy allows high charging power to be achieved with reduced current flow through intelligent voltage management.
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
The converter achieves reduced current flow and increased efficiency in charging battery packs with varying voltage capabilities, minimizing losses and supporting a wide range of voltage levels without additional hardware complexity.
Implementation Method 1
The bypass connection in one or more implementations directly connects a switch of the battery-side bridge to the battery pack
Implementation Method 2
an isolation circuit electrically isolating the first set of power switches from the second set of power switches
Data Source
AI summary
A direct current-to-direct current (DC-DC) converter includes an output node that is connectable to a battery pack, a first set of power switches, an isolation circuit, and a second set of power switches connected to the isolation circuit. The second set of power switches is arranged in three switching pairs. The second and third switching pairs are connected in parallel, with the third switching pair connected to the output node. A boost capacitor is arranged in parallel with the second and third switching pairs. A bypass connection connects a power switch of the first switching pair directly to the output node.