Regenerative Braking Control via Thermal Energy Storage
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Solution Overview
Problem
Regenerative braking in electric vehicles is limited by battery full charge state, leading to impaired user-friendliness due to insufficient braking force and increased mechanical brake wear, especially under varying environmental and road conditions.
Innovation Solution
A regenerative braking apparatus comprising a motor generator, inverter, refrigeration cycle unit, and heating cycle unit, controlled by a unit that consumes battery power through the refrigeration and heating cycles when the battery is fully charged, ensuring regenerative braking force is maintained regardless of environmental or road conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If regenerative braking is applied to recover electric power during braking, then energy efficiency is improved, but the system becomes inoperative when the battery is fully charged, reducing reliability
Solution Approach 1:
The patent introduces a thermal energy storage medium (phase change material) as an intermediary between the regenerative braking system and the battery. When the battery is fully charged, the braking energy is converted to thermal energy and stored in the phase change material instead of being discarded, allowing regenerative braking to continue operating reliably under all conditions
Solution Approach 2:
The system changes the energy storage parameter from electrical energy (battery charge state) to thermal energy (phase change material temperature). This parameter transformation allows the system to bypass the battery full-charge limitation and maintain continuous regenerative braking capability by storing excess energy in thermal form
2Reliability
If the battery charge state is monitored to prevent overcharging, then battery safety is improved, but regenerative braking must be disabled when fully charged, increasing mechanical brake wear
Solution Approach 1:
The patent converts the harmful effect of braking energy that cannot be stored (when battery is full) into a beneficial thermal energy storage opportunity. The previously wasted braking energy now charges the phase change material, transforming a system limitation into a useful thermal energy reservoir that prevents mechanical brake wear while maintaining battery safety
Solution Approach 2:
The system creates a multi-functional energy management approach where the thermal energy storage medium serves dual purposes: (1) storing braking energy when the battery is full, and (2) providing a fallback energy storage path that maintains regenerative braking functionality. This universal solution addresses both battery safety and mechanical brake wear prevention simultaneously
3Reliability
If regenerative braking is limited by battery charge state, then battery overcharge is prevented, but user-friendliness deteriorates due to insufficient braking force and cruise control cancellation
Solution Approach 1:
The phase change material acts as an intermediary energy storage buffer that decouples the regenerative braking system from the battery charge state limitation. This intermediary allows the regenerative braking system to operate independently of battery charge level, maintaining cruise control functionality and braking force availability while the battery charge management system continues to prevent overcharge
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 ensures consistent regenerative braking force, reducing mechanical brake wear and maintaining user-friendliness by precisely consuming battery power, thus preventing insufficiency of braking force and canceling cruise control.
Implementation Method 1
The refrigeration cycle unit compresses the refrigerant with the electric power of the battery to heat the heat exchanger
Implementation Method 2
The heating cycle unit is a unit in which a medium heated by the heat exchanger flows to heat the battery
Data Source
AI summary
A regenerative braking apparatus has an inverter. The inverter uses the rotational energy of the wheels to let the motor generator generate electric power for the purpose of providing regenerative braking. The regenerative braking apparatus also includes a refrigeration cycle unit and a heating cycle unit. The refrigeration cycle unit compresses a refrigerant with the electric power of the battery in order to heat a heat exchanger. The heating cycle unit is a unit in which a medium heated by the heat exchanger flows to heat the battery. When the battery is in a fully charged state where the battery cannot be charged with regenerative electric power of the motor generator, the regenerative braking apparatus exercises electric power consumption control to force the refrigeration cycle unit and the heating cycle unit to consume the electric power of the battery.