Electric Machine Loss Control for Low-Dust Regenerative Braking
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Solution Overview
Problem
Electrified vehicles emit brake dust and particulate matter pollution, especially in high-density traffic areas with poor air quality, and may not utilize regenerative braking due to high battery state of charge, leading to increased pollution.
Innovation Solution
A control system for electrified vehicles that increases the operation loss of the electric machine using a surplus current reference setting, employing regenerative braking over friction braking to charge the battery pack, even in high-density traffic areas, by adjusting current commands and switching frequency based on environmental conditions and battery energy levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If regenerative braking is used to charge the battery pack, then energy efficiency is improved and brake dust emissions are reduced, but the battery state of charge increases which limits further regenerative braking utilization
Solution Approach 1:
The control system dynamically adjusts the current reference setting for the electric machine based on environmental conservation conditions and battery state of charge. By modifying operational parameters (current commands, switching frequency) of the electric machine, the system enables continued regenerative braking even when battery charge levels are high, thus resolving the contradiction between energy efficiency improvement and battery charge limit constraints
2Reliability
If friction braking is used instead of regenerative braking, then battery charge level is maintained, but brake dust and particulate matter emissions increase in environmental conservation areas
Solution Approach 1:
The system replaces the mechanical friction braking system with an electromagnetic-based regenerative braking system using the electric machine. By substituting the mechanical friction mechanism with an electromagnetic generation mechanism, the system eliminates brake dust emissions while maintaining battery charge levels through controlled energy recovery
3Loss of energy
If the electric machine operates at high efficiency, then energy loss is minimized, but emissions control in environmental conservation areas is compromised
Solution Approach 1:
The control system dynamically adjusts the operating point of the electric machine based on real-time conditions including environmental conservation status and battery state of charge. By making the system dynamic and adaptive rather than static, it can optimize for low emissions in conservation areas while maintaining acceptable energy efficiency, resolving the contradiction between minimal energy loss and emissions control
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
Reduces emissions of brake dust and particulate matter by prioritizing regenerative braking, maintaining battery charge, and ensuring efficient energy use in environmentally sensitive areas.
Implementation Method 1
An electric drive system may include an electric machine that operates as a motor to provide positive torque to a driveline and as a generator to produce electric power for charging a battery pack of the electrified vehicle, which may occur during a regenerative braking operation to slow the EV
Implementation Method 2
The control system is configured to discharge power using the electric machine to increase operation loss of the electric machine based on a setting obtained from a current reference setting, a drive input, and a desired surplus loss limit in response to detecting an environmental conservation condition
Data Source
AI summary
A vehicle includes a battery pack, an electric machine, and a control system including one or more controllers. The control system is configured to discharge power using the electric machine to increase operation loss of the electric machine based on a setting obtained from a current reference setting, a drive input, and a desired surplus loss limit in response to detecting an environmental conservation condition.