Vehicle Electrical System with Battery Cell Bypass Switches
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Solution Overview
Problem
Modern hybrid vehicles face challenges with the weight and cost of power electronic converters needed to supply high electrical power to auxiliary services, which increases the overall weight and energy consumption of the vehicle.
Innovation Solution
The electrical system employs a dual-battery configuration with independent twin batteries connected in series, featuring electronic bypass switches to manage voltage and power distribution efficiently, using a Buck-Boost converter and inverter to connect storage and traction sections, and a control unit to manage switches and converters for optimal energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a high-power power electronic converter is used to supply electrical power to auxiliary services, then the electrical power requirement is met, but the weight of the vehicle increases
Solution Approach 1:
The battery system is divided into multiple cells with individual bypass switches, allowing selective activation of cells based on power requirements. This segmentation enables the system to use only the necessary number of cells for auxiliary power, avoiding the need for a dedicated high-power converter and reducing overall system weight.
Solution Approach 2:
The battery cells serve multiple functions: they provide power for traction through the main converter and simultaneously power auxiliary services directly when needed. This multi-functionality eliminates the need for separate dedicated converters for auxiliary services, reducing weight while maintaining full power capability.
2Power
If a high-power power electronic converter is used to supply electrical power to auxiliary services, then the electrical power requirement is met, but the cost of the system increases
Solution Approach 1:
The existing battery cells and bypass switches are used for dual purposes: traction power management and auxiliary service power supply. This eliminates the need for additional dedicated high-power converters, reducing system cost while maintaining the capability to supply high electrical power to auxiliary services.
Solution Approach 2:
The battery system with bypass switches autonomously manages power distribution to auxiliary services without requiring a dedicated converter. The system self-regulates by activating appropriate cells based on power demand, eliminating the need for expensive additional power conversion hardware.
3Power
If a high-power power electronic converter is used to supply electrical power to auxiliary services, then the electrical power requirement is met, but the energy consumption of the vehicle increases
Solution Approach 1:
By segmenting the battery into individual cells with bypass switches, the system activates only the necessary number of cells for auxiliary power, avoiding the energy losses associated with running a dedicated high-power converter at partial load or idle states.
Solution Approach 2:
The bypass switches, originally designed for cell isolation and protection, are repurposed to enable direct battery-to-auxiliary power connection. This converts a potential harm (direct battery connection complexity) into a benefit (elimination of converter energy losses).
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 reduces the need for a dedicated high-power converter, saving weight, cost, and energy while enabling efficient energy distribution and equalization of battery cell charges, enhancing the vehicle's performance and autonomy.
Implementation Method 1
The bypass switches are controlled (i.e. opened and closed) to obtain a 'balanced' discharge of the cells so as to exploit in greater measure the cells having higher electric charge
Implementation Method 2
a two-way power electronic converter (i.e. that is either capable of absorbing electrical power from the storage section for powering the electric machine working as motor or capable of providing the electrical power generated by the electric machine working as generator to the storage section)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An electrical system (15) of a vehicle (1) with electric propulsion achieved by at least one electrical machine (8); the electrical system (15) has: a storage section (16) provided with at least one battery (21) consisting of a plurality of cells (33), each of which is connected in series with the other cells (33) and is provided with a bypass branch (34) that is connected in parallel to the cell (33) and has a bypass switch (35); a section (17) of traction that interacts with the electric machine (8) and is equipped with a power electronic converter (13) that exchanges electrical energy with the storage section (16); and a section (18) of the auxiliaries, which powers auxiliary services (19) of the vehicle (1), has a buffer battery (20) and is electrically powered by the storage section (16); a first connecting switch (24) connecting the storage section (16) to the section (17) of traction; and a second connecting switch (25) connecting the storage section (16) to the section (18) of the auxiliaries.