EV Drive Assembly With Delta-Star Switching for Lower Electric Loss
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Solution Overview
Problem
Existing electric vehicle drive assemblies have limited driving range without intermediate charging, as they are inefficient in managing power distribution due to constant voltage supply, leading to high electric losses.
Innovation Solution
A drive assembly with a battery unit and cell-level control units that can switch between delta and star configurations for the electric drive machine, allowing adjustable AC current and voltage, reducing phase current and increasing phase voltage, thereby minimizing electric losses and increasing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the battery unit provides constant voltage to the electric drive machine, then the drive assembly operates with simple control, but electric losses increase and driving range is limited
Solution Approach 1:
The battery unit is segmented into multiple independently controllable battery strings, each capable of being switched between series and parallel configurations. This segmentation allows granular control over voltage and current output, enabling the system to optimize power delivery and reduce electric losses while maintaining manageable control complexity through modular architecture.
Solution Approach 2:
The drive assembly implements dynamic reconfiguration of battery strings between series and parallel connections based on real-time operating conditions. This dynamic switching capability allows the system to adapt voltage and current output to match the electric drive machine's requirements, minimizing energy losses while preserving control simplicity through automated switching logic.
2Power
If the three phase strands are operated in delta configuration, then the drive assembly provides high power output, but phase current increases leading to higher electric losses
Solution Approach 1:
The system changes the electrical configuration parameter of the three-phase strands by switching between delta and star connections. By selecting star configuration during operation, the system reduces phase current by a factor of √3 while maintaining the same power output, thereby significantly reducing I²R losses in the windings and improving overall efficiency.
3Duration of action of moving object
If the battery unit uses traditional constant voltage supply, then the system structure is simple, but the driving range is limited without intermediate charging
Solution Approach 1:
The battery unit is divided into multiple independently controllable battery strings that can be selectively connected in series or parallel. This segmentation enables the system to extend driving range by optimizing power delivery efficiency through configuration switching, while the modular structure keeps the overall system complexity manageable.
Solution Approach 2:
The system changes the voltage and current output parameters dynamically by reconfiguring battery strings between series and parallel connections. This parameter adjustment optimizes power delivery to match the electric drive machine's instantaneous requirements, extending driving range without requiring intermediate charging stops.
4Loss of energy
If phase current is reduced by switching to star configuration, then electric losses decrease, but the voltage supply requirements increase
Solution Approach 1:
The system changes the connection configuration parameter from delta to star, which automatically adjusts the voltage and current parameters. In star configuration, phase current is reduced by √3 while phase voltage increases by the same factor, maintaining constant power (P = √3 × V × I). This parameter transformation reduces I²R losses while the battery unit's flexible configuration capability supplies the required voltage without increasing overall energy consumption.
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
The ability to operate in an energy-saving mode by reducing electric losses through adjustable voltage and current settings extends the driving range of electric vehicles without the need for intermediate charging.
Implementation Method 1
each of the cell-level control units SE:TOP comprises a cell-level inverter unit being configured to transform a direct current being provided by the associated battery cell or the associated group of battery cells into an alternating current of adjustable voltage
Implementation Method 2
the drive assembly comprises a switching means being electrically connected to the electric drive machine and being configured for selectively switching the three phase strands in a delta configuration or in a star configuration
Data Source
Figure 1~2
Figure 3~4
AI summary
The disclosure relates to a drive assembly (10) for an electric vehicle. The drive assembly (10) has an electric drive machine (12) with three phase strands (12a, 12b, 12c). Moreover, the drive assembly (10) comprises a switching means being configured for selectively switching the three phase strands (12a, 12b, 12c) in a delta configuration or in a star configuration. The drive assembly (10) also comprises a battery unit (14), wherein the battery unit (14) comprises a plurality of battery cells (16) and a plurality of cell-level control units. Each of the cell-level control units is electrically connected to an associated single battery cell (16) out of the plurality of battery cells (16) or to an associated group of battery cells (16) out of the plurality of battery cells (16) and each of the cell-level control units comprises a cell-level inverter unit. Additionally, the disclosure is directed to a method for operating such a drive assembly (10).