Bidirectional DC/DC Converter for Cold-Start Battery Management
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Solution Overview
Problem
Conventional battery systems in vehicles face performance issues below freezing temperatures, including difficulty starting the engine, restricted regenerative braking, decreased vehicle range, and slow charging, which can be mitigated by replacing smaller batteries with larger ones but at increased cost.
Innovation Solution
An energy storage system (ESS) comprising multiple battery modules with a bidirectional DC/DC power converter, a starter, and a controller that dynamically adjusts power transfer modes based on battery state, temperature, and power demand to optimize energy distribution and usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a larger and more powerful battery is used to maintain vehicle performance in cold temperatures, then the power capability and starting capability are improved, but the cost increases significantly
Solution Approach 1:
The battery system is divided into two separate battery modules: a first battery (conventional lead-acid) and a second battery (lithium-ion). Each battery operates in its optimal performance range, with the controller managing power distribution between them. This segmentation allows the system to achieve high power capability without requiring a single oversized expensive battery.
Solution Approach 2:
The first battery serves multiple functions: it can operate independently for normal starting and power needs, or it can work in conjunction with the second battery when high power is required. The system provides universal functionality across different operating conditions without needing a completely different battery configuration for each scenario.
2Use of energy by moving object
If a larger battery is used to extend vehicle range in cold temperatures, then the energy storage capacity is improved, but the cost increases significantly
Solution Approach 1:
The energy storage system is segmented into two batteries with different characteristics. The lithium-ion second battery provides high energy density for extended range, while the lead-acid first battery handles immediate power demands. This segmentation allows the system to achieve extended range without requiring a single large expensive lithium-ion battery.
Solution Approach 2:
The system changes the electrical parameters (voltage, current) dynamically based on operating conditions. The controller adjusts the operating voltage between 12V and 48V systems, allowing the batteries to operate in their optimal parameter ranges for both range and power delivery without requiring oversized components.
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
Enhances vehicle performance by efficiently managing energy flow across battery modules, improving starting capabilities, regenerative braking, and extending range while maintaining cost-effectiveness by avoiding the need for larger, more expensive batteries.
Implementation Method 1
a bidirectional DC/DC power converter ('converter') electrically coupled to the voltage buses
Data Source
AI summary
An energy storage system (ESS) for a vehicle propulsion system includes a first battery electrically coupled to a first voltage bus, a second battery electrically coupled to a second voltage bus, and a bidirectional DC/DC power converter electrically coupled to the voltage buses. A starter for cranking an engine is electrically coupled to the first voltage bus. A controller executes computer code stored in memory. The computer code is configured to operate the converter in a boost mode to transfer power from the second voltage bus to the first voltage bus, in response to the controller determining that: a power capability of the first battery is below a power demand on the first voltage bus; a state of charge of the first battery is below a state of charge threshold; or a temperature of the first battery is below a temperature threshold.