800V Traction Battery Power System Using 600V MOSFETs
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Solution Overview
Problem
Existing electric vehicle power systems face challenges with high DC bus voltage, requiring re-design of components like on-board chargers and generators, and struggle with selecting suitable MOSFETs for higher voltage ratings, leading to increased expense and performance issues.
Innovation Solution
An integrated 800V traction battery power system using a DC to AC converter, AC to DC converters, and a transformer with 600V MOSFETs and capacitors, allowing for balanced voltage stresses and efficient power transfer across modes like battery charging, driving, and vehicle-to-grid operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If higher voltage ratings are used for MOSFETs, then power transfer capability is improved, but component expense and selection complexity increase
Solution Approach 1:
The patent changes the voltage parameter from conventional higher ratings to a specific 600V rating for MOSFETs, which optimizes the balance between power capability and component availability. This parameter selection allows use of existing 400V hardware designs while achieving 800V traction battery operation through controlled voltage stress distribution across the converter components
2Power
If 800V traction battery system is implemented, then power capability is improved, but existing 400V hardware designs become incompatible
Solution Approach 1:
The system operates with 800V traction battery but controls the voltage stress across converter components to remain within 400V ratings. This parameter control enables compatibility with existing 400V hardware designs including MOSFETs, capacitors, and PCBs, eliminating the need for complete system re-design while achieving higher power capability
Solution Approach 2:
The voltage stress is segmented and distributed across multiple components (MOSFETs, capacitors, transformer) such that each component experiences only 400V stress even though the battery operates at 800V. This segmentation allows existing 400V components to be used in an 800V system configuration
3Power
If voltage stress is increased for higher power transfer, then power capability is improved, but component reliability decreases
Solution Approach 1:
The patent maintains voltage stress parameter at 400V for all power semiconductor components (MOSFETs, capacitors) regardless of the 800V battery voltage. This parameter control ensures components operate within their rated specifications, maintaining reliability while achieving high power transfer capability through the overall system configuration and control strategy
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 enables the use of existing 400V hardware designs, reduces component selection complexity, improves efficiency, and lowers costs by utilizing 600V MOSFETs and a single high-frequency transformer, while maintaining voltage balance and reliability across operational modes.
Implementation Method 1
a transformer including a core, a primary winding wound about the core and electrically connected to an output of the DC to AC converter, and a pair of secondary windings wound about the core
Data Source
AI summary
A vehicle power system has a DC to AC converter, a pair of AC to DC converters, a transformer including a core, a primary winding wound about the core and electrically connected to an output of the DC to AC converter, and a pair of secondary windings wound about the core, a traction battery electrically connected to a collective output of the AC to DC converters, and a controller.