Integrated EV Charger-Converter for Internal Battery Voltage Balancing
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Solution Overview
Problem
Existing electric vehicle battery systems face challenges in balancing high voltage batteries without external balancing circuits, which can lead to reduced battery pack longevity due to voltage imbalances.
Innovation Solution
The proposed solution involves an electric vehicle battery system architecture that includes a battery pack with two batteries, each connected to a bidirectional DC-AC converter and a bidirectional HV AC-DC converter. A power factor correction AC-DC module is coupled to these converters via switches, enabling internal balancing of voltages between the batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional power conversion modules are increased in size to meet growing power demands, then power capacity is improved, but packaging space and integration complexity increase significantly
Solution Approach 1:
The patent combines the on-board charger and DC-DC converter into a single integrated power conversion module. The on-board charger converts AC to DC for battery charging, while the DC-DC converter manages power distribution and battery balancing. By merging these two previously separate modules into one unified system, the patent reduces overall packaging space while maintaining or enhancing power capacity. The integrated module shares common components such as transformers, switches, and control circuits, thereby achieving space efficiency without sacrificing functionality.
2Reliability
If external balancing circuits are added to balance high voltage batteries, then voltage balance is improved, but device complexity and packaging requirements increase
Solution Approach 1:
The integrated power conversion module performs multiple functions: AC-DC conversion for charging, DC-DC conversion for power distribution, and battery voltage balancing. The DC-DC converter within the integrated module can redirect current between series-connected battery cells to equalize voltage imbalances. This multi-functionality eliminates the need for separate external balancing circuits, reducing system complexity while maintaining voltage balance reliability.
Solution Approach 2:
The system uses its own internal DC-DC converter to perform battery balancing without requiring external balancing circuits. The DC-DC converter can operate in a recirculation mode where it draws current from higher-voltage batteries and feeds it to lower-voltage batteries, enabling the system to self-balance. This self-service capability reduces external dependencies and simplifies the overall system architecture.
3Adaptability or versatility
If separate on-board chargers and DC-DC converters are used, then functional versatility is improved, but integration challenges and packaging difficulty increase
Solution Approach 1:
The patent integrates the on-board charger and DC-DC converter into a single modular unit that maintains both functions. The integrated module includes AC input circuitry for the charger, DC output circuitry for the DC-DC converter, and shared power conversion components. This merging approach preserves functional versatility while reducing the number of separate components that need to be integrated, thereby simplifying the overall integration process and reducing packaging complexity.
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 effectively balances the voltages of the batteries within the system, improving the longevity of the battery pack by preventing voltage imbalances and reducing the need for external balancing circuits.
Implementation Method 1
a first bidirectional high-voltage (HV) alternating current to direct current (AC-DC) converter; a second bidirectional HV AC-DC converter
Implementation Method 2
a first bidirectional direct current to alternating current (DC-AC) converter electrically coupled to the first battery; a second bidirectional DC-AC converter coupled to the second battery
Implementation Method 3
a power factor correction AC-DC module electrically coupled to: the first bidirectional HV AC-DC converter via a first switch; and the second bidirectional HV AC-DC converter via a second switch
Data Source
AI summary
An electric vehicle battery system is provided. In some embodiments, the electric vehicle battery system can comprise a battery pack comprising a first battery and a second battery. In various embodiments, a first bidirectional direct current to alternating current (DC-AC) converter can be electrically coupled to the first battery and to a first bidirectional high-voltage (HV) alternating current to direct current (AC-DC) converter. In various implementations, a second bidirectional DC-AC converter can be coupled to the second battery and to a second bidirectional HV AC-DC converter. In further embodiments, and a power factor correction AC-DC module can be electrically coupled to the first bidirectional HV AC-DC converter via a first switch and the second bidirectional HV AC-DC converter via a second switch.