Brake Resistor Airflow Dissipation for EV Auxiliary Braking
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Solution Overview
Problem
Electric vehicles face challenges in achieving effective auxiliary braking without overburdening the cooling system, as energy dissipation during braking places a significant load on the cooling capacity, particularly in fuel cell electric vehicles (FCEVs) and battery electric vehicles (BEVs).
Innovation Solution
An electric energy dissipating system is implemented, comprising a polyphase electric machine connected to an air flow producing unit, with an electric brake resistor arrangement in the fluid conduit downstream, both connected in parallel to a common inverter, allowing for efficient energy dissipation through heated air release to the ambient environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate inverter is used for the electric brake resistor arrangement, then the dissipation of electric energy is effective, but the device complexity and cost increase
Solution Approach 1:
The patent combines the control of the polyphase electric machine and the electric brake resistor arrangement into a single inverter. The inverter has multiple output terminals that can independently control different loads, allowing one inverter to serve dual purposes: driving the air flow producing unit during normal operation and driving the brake resistor arrangement during braking, thereby eliminating the need for a separate inverter while maintaining effective energy dissipation
Solution Approach 2:
The inverter is designed with multi-functionality to perform both the air flow production function and the brake energy dissipation function. By configuring the inverter with multiple output terminals capable of independent control, a single device achieves what previously required two separate devices, reducing system complexity and cost while maintaining full functionality
2Ease of manufacture
If a separate inverter is used for the electric brake resistor arrangement, then the energy dissipation control is independent, but the manufacturing cost increases
Solution Approach 1:
The patent merges the functionality of two inverters into one, reducing the bill of materials and manufacturing costs. By designing the inverter with multiple output terminals that can be independently controlled, the system achieves the same functionality with fewer components, directly lowering manufacturing expenses while maintaining independent control capability through electronic control strategies
3Temperature
If the cooling system capacity is increased to handle braking energy, then the cooling capacity is sufficient, but the vehicle weight and space increase
Solution Approach 1:
The patent converts the harmful effect of braking energy (which would otherwise require large cooling systems) into a useful function by directing it to heat air that is then discharged to the atmosphere. The air flow producing unit directs air through the brake resistor arrangement, where braking energy heats the air, and this heated air is discharged to ambient, effectively dissipating energy without requiring large cooling capacity
Solution Approach 2:
The patent extracts the energy dissipation function from the cooling system by creating a separate pathway through the brake resistor arrangement. Instead of requiring the cooling system to handle all thermal management including braking energy, the system extracts and redirects braking energy to heat and discharge air separately, allowing the cooling system to be downsized to handle only its original thermal management functions
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 system effectively dissipates electric energy with reduced strain on the cooling system, enabling cost-effective and space-saving solutions by using a shared inverter, thus downsizing cooling systems and optimizing energy management.
Implementation Method 1
an electric brake resistor arrangement located in said fluid conduit downstream of the air flow producing unit, the electric brake resistor arrangement comprising one resistor unit for each one of said predefined number of phases
Implementation Method 2
a polyphase electric machine configured to run on a predefined number of phases, wherein the air flow producing unit is mechanically connected to, and operated by, the polyphase electric machine
Implementation Method 3
an inverter which converts a DC input into a polyphase AC output
Data Source
AI summary
An electric energy dissipating system for a vehicle. An air flow producing unit provides a pressurized air flow through a fluid conduit. A polyphase electric machine runs on a predefined number of phases. The air flow producing unit is mechanically connected to, and operated by, the electric machine. An electric brake resistor arrangement is located downstream of the air flow producing unit, and comprises one resistor unit for each one of said phases. An electric power system is configured to receive electric power generated by an electric traction motor during braking of the vehicle. The power system comprises an inverter which converts a DC input into a polyphase AC output. The electric machine and the resistor arrangement are electrically connected to the inverter in parallel, such that each phase of the AC output of the inverter is connected to a respective phase of the electric machine and to a respective resistor unit, in parallel.