Battery Module Switch Array for Low-Voltage Bus Charge Balancing
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Solution Overview
Problem
The divergence in state of charge across battery module groups in a vehicle's battery pack leads to a decline in the operation of the electric system, necessitating a method to balance the charge states.
Innovation Solution
A switch array is used to connect module groups to low voltage buses in different configurations, cycling through modes to balance the state of charge, with a processor controlling the switch array to adjust durations and configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a battery pack includes multiple module groups to provide power to high voltage and low voltage loads, then the power supply capability is improved, but the state of charge diverges across module groups causing system operation to decline
Solution Approach 1:
The battery pack is divided into multiple module groups, each with its own DC/DC converter and switch array. This segmentation allows independent control of each module group's power output while maintaining overall system functionality. The switch array further segments the connection paths to different low voltage buses, enabling selective power distribution and charge balancing between module groups.
Solution Approach 2:
The system dynamically changes the connection configuration parameters by switching between different switch states (first state connecting to first low voltage bus, second state connecting to second low voltage bus, third state disconnected). This parameter change enables the module groups to alternately connect to different buses, facilitating charge transfer and balancing while maintaining power supply capability.
2Adaptability or versatility
If DC/DC converters are used to connect battery modules to switches, then power conversion and distribution is improved, but device complexity increases
Solution Approach 1:
The DC/DC converters are designed as unidirectional power conversion devices that perform multiple functions: power conversion from battery modules to bus level, isolation between high voltage and low voltage sides, and enablement of bidirectional power flow at the system level through the switch array. This multi-functionality reduces the need for additional dedicated components.
Solution Approach 2:
The switch array acts as an intermediary component between the DC/DC converters and the low voltage buses. It provides a simple binary switching mechanism that controls power distribution without requiring complex power electronic devices, thereby managing system complexity while maintaining adaptability.
3Reliability
If the switch array cycles through multiple configurations to balance charge, then charge balancing effectiveness is improved, but control complexity increases
Solution Approach 1:
The switch array operates in cyclic modes, periodically switching module groups between different connection configurations. Each cycle includes phases where different module groups connect to different low voltage buses, creating periodic charge transfer opportunities. This periodic action systematically balances charge across all module groups while using simple on/off switching logic rather than complex continuous control.
Solution Approach 2:
The system dynamically adjusts the connection topology by changing switch states based on the operational phase. The switch array transitions between different valid configurations (modes) during operation, allowing the system to adaptively balance charge while maintaining simple binary switch control logic. The processor manages the dynamic reconfiguration without requiring complex real-time calculations.
Data Source
AI summary
A vehicle includes an electrical system for balancing a state of charge in a battery pack. The electrical system includes a plurality of module groups. A switch array includes a plurality of switches. Each switch is coupled to a respective module group. The switch can be in one of a first state that connects the module group to a first low voltage bus, a second state that connects the module group to a second low voltage bus, and a third state in which the module group is disconnected from both the first low voltage bus and the second low voltage bus. The array is placed in a first phase of a mode of operation with at least one switch in one of the first state and the second state and cycles through the phases of the mode to balance a charge between the plurality of module groups.