Onboard Braking Resistor for EV Energy Transfer
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Solution Overview
Problem
Existing plug-in electric vehicles require additional dedicated components for transferring energy between the on-board electrical storage device and an external source, increasing cost and weight.
Innovation Solution
An apparatus and method that utilize a DC bus, a braking resistor, and a controller to dissipate energy during regenerative braking events and receive charging energy from a high-impedance voltage source, bypassing the resistor after a threshold is crossed, thereby reducing the number of components needed for energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dedicated components (boost converters, high-frequency filters, choppers, inductors) are used to transfer energy between the on-board electrical storage device and external source, then energy transfer reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies multi-functionality by enabling the DC bus and braking resistor to serve dual purposes: (1) as energy dissipation path during regenerative braking, and (2) as energy transfer path during vehicle charging. The controller intelligently switches between these functions based on operational mode, eliminating the need for dedicated charging components and reducing overall system complexity while maintaining reliable energy transfer.
Solution Approach 2:
The patent merges previously separate functions into unified components. The DC bus and braking resistor, originally dedicated to regenerative braking energy dissipation, are combined to also handle external charging energy transfer. This consolidation reduces the number of dedicated components needed for charging operations while maintaining system reliability through controlled operation.
2Power
If dedicated components are added for energy transfer, then energy transfer capability is improved, but vehicle weight increases
Solution Approach 1:
The DC bus and braking resistor are designed to perform multiple functions including external charging energy transfer alongside their traditional regenerative braking roles. This multi-functionality eliminates the need for additional dedicated charging components that would increase vehicle weight, while still providing robust energy transfer capability through the shared components.
3Adaptability or versatility
If energy is transferred through the braking resistor during charging, then component utilization is improved, but power loss increases
Solution Approach 1:
The controller implements a two-stage charging process where preliminary action is taken by first charging the storage device through the braking resistor to an intermediate state, then switching to direct charging when the storage device reaches a threshold charge level. This preliminary use of the resistor enables safe initial energy transfer while minimizing subsequent power losses through direct charging path.
Solution Approach 2:
The system dynamically switches the charging path based on real-time conditions. The controller monitors the charging state and transitions from resistor-based charging to direct charging when the storage device reaches a threshold level. This dynamic adaptation optimizes component utilization while minimizing energy losses by using the resistor only when necessary.
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 approach simplifies the energy transfer process, reduces component count, and enables efficient charging by minimizing power loss through the resistor during the second stage of charging, thus enhancing the efficiency and cost-effectiveness of energy transfer.
Implementation Method 1
cause on the DC bus to be dissipated through the braking resistor during a regenerative braking event
Implementation Method 2
cause the first energy storage device to receive a charging energy from the high-impedance voltage source through the braking resistor during a charging event
Data Source
AI summary
An apparatus for transferring energy using onboard power electronics comprises a first energy storage device configured to output a DC voltage and a DC bus coupled to the first energy storage device, the DC bus coupleable to a high-impedance voltage source. The apparatus also comprises a braking resistor coupled to the DC bus and to a control circuit, and a controller. The controller is configured to control the control circuit to cause energy on the DC bus to be dissipated through the braking resistor during a regenerative braking event, cause the first energy storage device to receive a charging energy from the high-impedance voltage source through the braking resistor during a charging event, and after a threshold value has been crossed, cause the first energy storage device to receive the charging energy from the high-impedance voltage source bypassing the braking resistor during the charging event.