Distributed LV Charging for Overdischarged HV Battery Modules
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Solution Overview
Problem
Existing charging systems for high voltage rechargeable energy storage systems (RESS) in vehicles are impractical or impossible to use in situations where regenerative braking is unavailable, the RESS is overly discharged, and the vehicle cannot connect to a utility power grid or another vehicle.
Innovation Solution
A low voltage (LV) charging system that converts LV electrical power from a source, such as a 12 VDC battery, into charging electrical power for a high voltage (HV) RESS using a distributed converter system and a controller to individually control the charging power for each module of the RESS.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If HV charging systems are used to charge the RESS, then charging speed and power delivery are improved, but system complexity and availability are worsened when HV systems are unavailable
Solution Approach 1:
The charging system is segmented into multiple independent charging circuits (first charging circuit, second charging circuit, etc.) that can operate autonomously. Each circuit includes its own bidirectional converter and control logic, allowing the system to divide the charging function across multiple pathways. This segmentation enables the system to maintain charging capability even when some circuits are unavailable, directly addressing the reliability issue while preserving power delivery capability.
Solution Approach 2:
The bidirectional converters are designed to perform multiple functions: they can convert LV electrical power to HV charging power, enable vehicle-to-vehicle power transfer, and support regenerative braking energy recovery. This multi-functionality ensures that the charging system remains available through multiple mechanisms (LV source, V2V, regenerative braking) rather than relying solely on external HV charging infrastructure, thereby improving charging availability without sacrificing power delivery capability.
2Reliability
If LV electrical power is used to charge HV RESS, then charging availability is improved when HV systems are unavailable, but charging power and speed are worsened
Solution Approach 1:
Bidirectional DC-DC converters serve as intermediary devices between the LV electrical source and the HV RESS. These converters transform the low voltage power into high voltage charging power suitable for the RESS modules. The intermediary converters enable power transfer across different voltage levels, allowing LV sources to effectively charge HV systems while maintaining both availability and adequate power delivery capability.
Solution Approach 2:
The system merges multiple power sources (LV battery, regenerative braking, vehicle-to-vehicle transfer) into a unified charging architecture that feeds into the same RESS modules through coordinated bidirectional converters. This merging allows the system to aggregate power from various sources, compensating for the lower power output of individual LV sources while maintaining charging availability across different operating conditions.
3Reliability
If multiple charging circuits are used to charge RESS modules, then charging reliability and flexibility are improved, but device complexity is worsened
Solution Approach 1:
The charging system is divided into multiple independent charging circuits, each responsible for specific RESS modules. Each circuit contains its own bidirectional converter and control logic, creating modular units that can be independently managed. This segmentation improves reliability through redundancy while containing complexity within standardized, repeatable circuit modules rather than creating a monolithic complex system.
Solution Approach 2:
The controller continuously monitors the state of charge, temperature, and operational status of each RESS module and charging circuit, using this feedback to dynamically adjust charging parameters. The feedback mechanism enables the controller to optimize power distribution across multiple circuits, coordinate charging sequences, and maintain system stability, thereby managing the complexity of multiple charging circuits through intelligent control rather than hardware 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
Enables the charging of HV RESS and provides jumpstart capabilities when HV charging systems are unavailable, ensuring the vehicle can be powered and operated even in challenging situations.
Implementation Method 1
a bidirectional converter configured for converting the LV electrical power to the charging electrical power
Data Source
AI summary
A low voltage (LV) charging system for charging a high voltage (HV) rechargeable energy storage system (RESS), such as a HV RESS operable for electrically powering a traction motor of an electric vehicle. The LV charging system may include an input configured for receiving LV electrical power from a LV source and a distributed converter system configured for charging a plurality of modules of the HV RESS via a plurality of charging circuits. The charging circuits may be configured for separately charging one of the modules with a charging electrical power derived from converting the LV electrical power. The LV charging system may further include a controller configured for individually controlling the charging electrical power provided via each of the charging circuits.