EV Drivetrain Battery Switching for 400V-to-800V Pulse Charging
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Solution Overview
Problem
Current high-voltage power supply systems for electric vehicles require costly and power-limiting DC/DC converters to charge at 800V using conventional 400V charging stations, leading to increased complexity and longer charging times, while conventional CC-CV charging can negatively impact battery lifetime.
Innovation Solution
A power supply system comprising two high-voltage battery units connected in series, with a circuit arrangement and electronic control system that routes high-voltage DC from a charging source alternately between the battery units at a high frequency, eliminating the need for a 400/800V DC/DC converter and enabling pulse charging, which improves battery lifetime and charging efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a 400V to 800V DC/DC converter is used to enable charging at 800V from conventional 400V charging stations, then high-voltage fast charging capability is achieved, but system cost and complexity increase
Solution Approach 1:
The battery system is segmented into two separate 400V battery units (first and second battery units) that can be charged independently. During charging, the circuit arrangement alternates between charging each battery unit separately at 400V, avoiding the need for a 400V to 800V DC/DC converter while still enabling high-power charging capability.
2Adaptability or versatility
If a DC/DC converter is used to convert 400V to 800V for charging, then charging voltage compatibility is achieved, but charging time increases due to limited power level
Solution Approach 1:
The charging process uses periodic alternation between charging the first battery unit and the second battery unit. The electronic control system switches between charging modes at frequencies of at least 100 Hz (specifically 500-10,000 Hz), creating a pulsed charging effect that maintains high average charging power while ensuring voltage compatibility with conventional 400V charging stations.
3Ease of operation
If conventional CC-CV charging is used to charge high-voltage batteries, then charging simplicity is maintained, but battery lifetime is negatively impacted
Solution Approach 1:
The system implements periodic pulsed charging by alternating between charging the first and second battery units at high frequency. This pulsed charging mode reduces continuous stress on battery cells, allows thermal management between pulses, and prevents dendrite formation, thereby extending battery lifetime while maintaining operational simplicity through automated electronic control.
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 fast charging of 800V batteries using conventional 400V stations without a DC/DC converter, reducing costs and extending battery life through pulse charging, which reduces charge time and enhances safety by allowing positive ion intercalation and preventing dendrite formation.
Implementation Method 1
routing high-voltage DC received from a vehicle external charging source alternatingly to the first high-voltage battery unit and to the second high-voltage battery unit, with an alternating frequency of at least 100 Hz, specifically at least 500 Hz, and more specifically in the range of 100 - 10 000 Hz
Implementation Method 2
allowing positive ion intercalation and preventing dendrite formation
Implementation Method 3
enabling pulse charging, which improves battery lifetime and charging efficiency
Data Source
Figure 1~3
Figure 4A~4C
Figure 5A~5B
AI summary
A power supply system for an electric vehicle drivetrain comprising a first high-voltage battery unit (21), a second high-voltage battery unit (22) connected in series with the first high-voltage battery unit (21), a circuit arrangement (23) having a plurality of high-power switching semiconductor devices (31-34) connected to the first and second high-voltage battery units (21, 22), and an electronic control system (24). The electronic control system (24) is configured for controlling operation of the plurality of high-power switching semiconductor devices (31-34) for, during a charging mode of the first and second high-voltage battery units (21, 22), routing high-voltage DC received from a vehicle external charging source (25) alternatingly to the first high-voltage battery unit (21) and to the second high-voltage battery unit (22), with an alternating frequency of at least 100 Hz, specifically at least 500 Hz, and more specifically in the range of 100 - 10 000 Hz. Moreover, the electronic control system (24) configured for controlling operation of the plurality of high-power switching semiconductor devices (31-34) for, during a power supply mode of the power supply system, supplying high-voltage DC from both the first and second high-voltage battery units (21,22) for driving a vehicle electrical traction machine (26) of the electric vehicle drivetrain, wherein the supplied high-voltage DC has a voltage level corresponding to the accumulated voltage level of the series connected first and second high-voltage battery units (21, 22).