Battery Switching Circuit for Multi-Voltage EV Charging
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Solution Overview
Problem
Vehicles equipped with secondary batteries face inefficiencies in charging due to the use of voltage converters for different charging equipment classes, leading to increased manufacturing costs and reduced efficiency, especially when transitioning between 400 V, 800 V, and 1200 V charging systems.
Innovation Solution
A power storage system with a battery comprising multiple power storage units and a switch group that can switch between different voltage states, a three-phase motor, an inverter, DC power supply circuits, and auxiliary device drive circuits, allowing direct charging without voltage converters by utilizing the three-phase motor and inverter for voltage conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a voltage converter is used to enable charging at different voltage classes (400V, 800V), then the vehicle can be charged by both 400V and 800V charging equipment, but charging efficiency deteriorates due to voltage conversion losses
Solution Approach 1:
The patent removes the voltage converter from the charging path by directly connecting the battery to the charging equipment through switching circuits. The battery connection system is reconfigured to switch between series and parallel connections of battery modules, enabling direct voltage matching with charging equipment without energy-lossy conversion.
Solution Approach 2:
The patent implements dynamic switching of battery connection configurations (series/parallel arrangements) based on the detected charging equipment voltage class. The switching circuit dynamically reconfigures the battery modules to match the required voltage level, eliminating the need for static voltage conversion during charging.
2Ease of operation
If a voltage converter is used for auxiliary devices during charging, then auxiliary devices can operate at appropriate voltages, but manufacturing cost increases due to the expense of voltage converters
Solution Approach 1:
The patent makes the switching circuit serve multiple functions: it enables direct charging at different voltage classes and simultaneously provides appropriate voltage to auxiliary devices. The same switching infrastructure that handles charging voltage adaptation also manages auxiliary device power distribution, eliminating the need for separate voltage converters.
Solution Approach 2:
The patent merges the charging voltage adaptation function and auxiliary device power supply function into a single switching circuit system. Instead of having separate voltage converters for charging and auxiliary devices, the system combines both functions into one integrated switching architecture.
3Object-affected harmful factors
If higher voltage charging (800V, 1200V) is used to reduce current and burden on power distribution units, then the burden on terminals and power distribution units decreases, but the need for voltage conversion for auxiliary devices increases system complexity
Solution Approach 1:
The patent dynamically switches between different battery module connection configurations (series for high voltage, parallel for lower voltage) depending on the charging equipment class. This dynamic reconfiguration allows the system to accept high-voltage charging when available (reducing current burden) while automatically adapting to lower voltage equipment, maintaining simplicity across different operating conditions.
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 efficient charging and operation of auxiliary devices without expensive voltage converters, reducing manufacturing costs and maintaining efficiency across varying charging voltages.
Implementation Method 1
an inverter connected to an electric power transmission path between the battery and the three-phase motor
Implementation Method 2
a three-phase motor in which coils of three phases are connected at a neutral point, the three-phase motor being driven by electric power supplied from the battery
Data Source
AI summary
A system includes: a battery including a switch group configured to switch a connection state of a plurality of power storage; a three-phase motor; an inverter; a DC power supply circuit connected to a first connection portion positioned on an electric power transmission path between the inverter and the battery; an auxiliary device; and a drive circuit connected to a second connection portion on an electric power transmission path between the inverter and the first connection portion. The DC power supply circuit on a positive electrode side includes a branch circuit connected to a coil of one phase among coils of three phases at a third connection portion, the branch circuit is connected to the drive circuit at a fourth connection portion via a first switch, and the drive circuit has a second changeover switch between the second connection portion and the fourth portion.