EV Charging Thermal Control Using Motor Neutral-Point Boosting
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Solution Overview
Problem
The excessive heating of rotating electric machines during external charging in electrified vehicles leads to performance degradation and reduced charging efficiency due to temperature rises, which can be exacerbated by continued operation during vehicle stops.
Innovation Solution
Implementing a control system that predicts charging conditions and adjusts cooling capacity, refrigerant flow, drive power, and regenerative power to maintain apparatus temperatures within safe limits before charging, using a cooling device, electric power conversion, and a control device to manage temperature and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If external charging is performed by supplying electric power to the neutral point of the rotating electric machine, then charging capability is improved, but the rotating electric machine generates excessive heat causing temperature rise and performance degradation
Solution Approach 1:
The control device executes cooling control before external charging starts by predicting the traveling time to the charging place. When the predicted time is short and temperature is high, the system proactively cools the rotating electric machine to prevent excessive temperature rise during charging, thereby maintaining both charging capability and acceptable temperature levels.
2Temperature
If charging operation is restricted to prevent excessive temperature rise of the rotating electric machine, then temperature control is improved, but charging efficiency decreases and charging time increases
Solution Approach 1:
Instead of restricting charging operation, the system performs cooling control before charging starts. By predicting the traveling time to the charging place and checking temperature conditions in advance, the system cools the rotating electric machine proactively, enabling full-power charging without temperature restrictions and thus avoiding charging time extension.
Solution Approach 2:
The control device continuously monitors the temperature of the rotating electric machine and compares it against a predetermined threshold. Based on this feedback and the predicted traveling time, the system dynamically adjusts cooling control intensity to maintain temperature within acceptable ranges while maximizing charging efficiency.
3Use of energy by moving object
If the rotating electric machine operates during vehicle stop for drive power generation or regenerative braking, then power utilization is improved, but temperature accumulates and exacerbates heating during subsequent charging
Solution Approach 1:
The system predicts the traveling time to the charging place in advance and accumulates temperature information from recent operations including drive power generation and regenerative braking. When the predicted time is short and temperature is high, cooling control is executed before charging to remove accumulated heat, enabling both continuous power utilization and safe charging.
Solution Approach 2:
The control device monitors temperature trends from recent operations and uses this feedback to determine whether cooling control is needed before charging. The system balances power utilization with temperature management by adjusting cooling intensity based on actual temperature measurements and predicted charging timing.
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
Prevents excessive temperature rises during charging, protecting apparatus performance and maintaining efficient charging operations by proactive cooling and power management.
Implementation Method 1
a cooling device configured to cool the charging group... increase cooling capacity of the cooling device... increase a refrigerant amount that is supplied by the cooling pump
Implementation Method 2
The rotating electric machine generates the drive power using electric power from the battery, and generates electricity by external force (inertial force) at the time of regenerative braking... The rotating electric machine generates heat by the electric current that flows through the rotating electric machine
Implementation Method 3
a battery capable of being charged and discharged... convert direct-current power from the battery into alternating-current power
Data Source
AI summary
A vehicle includes a battery, a rotating electric machine, an electric power conversion device, a charging device, and a control device. When the battery is charged, the charging device supplies direct-current power to a neutral point of the rotating electric machine, and the rotating electric machine and the electric power conversion device boost the direct-current power and supply the power to the battery. During traveling, the control device predicts a traveling time to a charging place, and executes a control that restrains rise in the temperature of a charging group in a case where the predicted traveling time is equal to or shorter than a criterion time and where a condition is satisfied, the condition being a condition that temperatures of the battery, the rotating electric machine and the electric power conversion device that are included in the charging group is higher than a criterion temperature.