EV Circuit Arrangement with Reference Potential Terminal
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Solution Overview
Problem
Electric vehicles require a battery with a large capacity to enable long-distance travel, which often necessitates connecting multiple small-capacity battery cells in series, resulting in high voltages that demand extensive isolation and safety precautions, while other vehicle components require lower voltages, complicating power distribution.
Innovation Solution
A circuit arrangement that uses a single battery with a reference potential terminal to supply both the electric machine and the power net of an electric vehicle, eliminating the need for converters and reducing isolation and safety requirements by operating at a lower voltage range (6 V to 60 V), allowing the battery to power both the traction engine and auxiliary devices directly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple battery cells are connected in series to achieve large capacity, then the battery capacity is improved, but the battery voltage increases to several hundreds of volts requiring special isolation and safety precautions
Solution Approach 1:
The patent divides the battery system into two separate batteries: a high-voltage battery (e.g., 400V) for the electric machine and a low-voltage battery (e.g., 12V or 24V) for the power net. This segmentation allows each battery to operate at appropriate voltage levels, reducing the need for extensive isolation and safety precautions while maintaining large overall capacity through the combination of both batteries.
Solution Approach 2:
The low-voltage battery serves multiple functions: it powers the power net (radio, navigation, lights, wipers) and also provides auxiliary power to the electric machine when needed. This multi-functionality reduces the complexity of isolation requirements while maintaining system capacity.
2Quantity of substance
If high voltage battery is used to supply large capacity, then the battery capacity is improved, but the voltage level becomes incompatible with power net requirements
Solution Approach 1:
The patent segments the power supply system into two distinct voltage domains: a high-voltage battery for the electric machine and a low-voltage battery for the power net. This segmentation ensures voltage compatibility for each subsystem while maintaining large overall capacity through the combined system.
Solution Approach 2:
The patent introduces a DC-DC converter as an intermediary between the high-voltage battery and the low-voltage battery. This converter enables bidirectional power flow, allowing the high-voltage battery to charge the low-voltage battery and also allowing the low-voltage battery to power auxiliary loads, thus ensuring voltage compatibility across different subsystems.
3Productivity
If high voltage battery supplies both electric machine and power net, then the battery capacity utilization is improved, but the device complexity increases due to converters and isolation requirements
Solution Approach 1:
The patent segments the load distribution into two separate paths: the high-voltage battery directly supplies the electric machine, and the low-voltage battery supplies the power net. This segmentation eliminates the need for complex voltage conversion and isolation components while maximizing battery capacity utilization for each respective load.
Solution Approach 2:
The low-voltage battery is designed to serve multiple functions independently: powering the power net, providing auxiliary power to the electric machine during transient demands, and being charged from the high-voltage battery. This multi-functionality reduces device complexity while maintaining high capacity utilization.
Data Source
AI summary
A circuit arrangement (11) for supplying an electric vehicle with power comprises a battery (10) with a first terminal (16) and a second terminal (17), and a reference potential terminal (12) directly connected to the second terminal (17) of the battery (10). The circuit arrangement (11) further comprises a first output (18) that is coupled to the first terminal (16) of the battery (10) via a first switch (20) and that is configured to be connected to an electric machine (33) of the electric vehicle, and a second output (19) that is coupled to the first terminal (16) of the battery (10) and that is configured to be connected to a power net (34) of the electric vehicle. Furthermore, a power system (32) for an electric vehicle comprises the circuit arrangement (11), an electric machine (33) and a power net (34). The first output (18) is coupled to the electric machine (33) and the second output (19) is coupled to the power net (34).