Motor Control for Eco-Friendly Vehicle Regenerative Braking
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Solution Overview
Problem
Eco-friendly vehicles face inconvenience and battery overcharge during regenerative braking when fully charged, as existing systems struggle to balance regenerative braking with battery charging and motor/inverter protection from overheating.
Innovation Solution
Implementing a low-efficiency control method for the motor system that adjusts the motor's current driving point based on battery state of charge and temperature, reducing regenerative braking when fully charged to prevent overcharge and overheating, while maintaining braking operability through hydraulic compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If regenerative braking is continuously applied to recharge the battery, then battery charging efficiency is improved, but battery overcharge occurs and motor/inverter overheating is caused
Solution Approach 1:
The patent dynamically adjusts the motor's current driving point based on real-time battery state of charge (SoC) and temperature conditions. When battery SoC reaches a predetermined level or temperature exceeds thresholds, the system transitions from normal regenerative braking to low-efficiency control mode, forcing the motor to operate at reduced efficiency driving points to limit charging current and prevent overcharge and overheating
Solution Approach 2:
The system changes the motor's operating parameters (current driving point) based on battery conditions. By forcing the motor to operate at low-efficiency driving points during specific conditions, the patent controls the amount of energy recovered during regenerative braking, thereby preventing battery overcharge and motor/inverter overheating while maintaining braking functionality
2Reliability
If regenerative braking is stopped when battery is fully charged, then battery overcharge is prevented, but driving inconvenience occurs due to loss of regenerative braking function
Solution Approach 1:
Instead of completely stopping regenerative braking when battery is full, the patent dynamically switches the motor's operating mode from normal efficiency to low-efficiency control. This allows regenerative braking to continue functioning (maintaining driving convenience and braking operability) while limiting the energy recovery amount to prevent battery overcharge
Solution Approach 2:
The system changes the motor's current driving point to low-efficiency operating points when battery SoC reaches predetermined levels. This parameter change reduces the regenerative braking efficiency just enough to prevent overcharge while keeping the braking function active, thus avoiding driving inconvenience
3Use of energy by moving object
If motor operates at high efficiency driving point during regenerative braking, then energy recovery efficiency is improved, but motor and inverter temperature increases causing overheating
Solution Approach 1:
The patent monitors motor and inverter temperatures during regenerative braking. When temperatures reach predetermined thresholds, the system forces the motor to operate at low-efficiency driving points, reducing the energy recovery rate but also reducing heat generation, thereby preventing overheating while maintaining controlled energy recovery
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 stabilizes vehicle braking operability, prevents battery overcharge, and protects the motor and inverter from overheating by dynamically adjusting motor efficiency during regenerative braking, ensuring continuous braking performance and component safety.
Implementation Method 1
a motor for driving and regenerative braking
Implementation Method 2
a high-voltage rechargeable battery (hereinafter, referred to as a battery) that is connected to a motor and an inverter
Data Source
AI summary
The present disclosure provides a method of controlling a motor system of an eco-friendly vehicle, which includes: determining whether a regenerative braking is an on-state; upon determining that regenerative braking is the on-state, checking a battery state of charge (SoC); and upon checking that the battery SoC is fully recharged, entering into a motor low-efficiency control procedure that forcibly lowers a current driving point of a motor.