Vehicle Thermal Control for EV Oil Temperature and Friction Loss
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Solution Overview
Problem
Existing vehicle temperature control systems fail to effectively manage oil temperature in electric vehicles, leading to increased friction loss in rotary electric machines and gearboxes, which negatively impacts efficiency and performance.
Innovation Solution
A vehicle temperature control system comprising a first temperature control circuit for the rotary electric machine and gearbox, a second temperature control circuit for the electric-power conversion unit, and a heat exchanger, where the control device adjusts the carrier frequency of the inverter and flow rate of the second temperature control medium based on the temperature of the first temperature control medium to minimize heat exchange and reduce friction loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heat exchange between the first temperature control medium and second temperature control medium is increased to cool the rotary electric machine and gearbox, then the temperature of the first temperature control medium decreases, but the friction loss of the rotary electric machine and gearbox increases due to excessively low temperature
Solution Approach 1:
The control device dynamically adjusts the flow rate of the second temperature control medium through the heat exchanger based on the detected temperature of the first temperature control medium. When the temperature is low, the flow rate is reduced or stopped to prevent excessive cooling, thereby maintaining optimal temperature and reducing friction loss. When temperature rises, the flow rate is increased to provide cooling. This dynamic parameter adjustment resolves the contradiction between maintaining temperature and preventing friction loss.
2Productivity
If the flow rate of the second temperature control medium through the heat exchanger is increased to improve cooling efficiency, then the temperature control capability improves, but the energy consumption increases and friction loss increases due to lower oil temperature
Solution Approach 1:
The system dynamically adjusts the flow rate parameter of the second temperature control medium based on real-time temperature detection. By changing the flow rate from high to low or zero based on temperature conditions, the system optimizes cooling efficiency while preventing excessive temperature reduction that would increase friction loss. This adaptive parameter change resolves the contradiction between cooling efficiency and energy loss.
3Use of energy by moving object
If the carrier frequency of the inverter is increased to improve power conversion efficiency, then the electric-power conversion unit operates more efficiently, but the temperature of the first temperature control medium decreases leading to increased friction loss
Solution Approach 1:
The control device adjusts the carrier frequency of the inverter based on the temperature of the first temperature control medium. When the temperature is low, the carrier frequency is reduced to decrease heat generation from the inverter, thereby preventing excessive cooling of the first temperature control medium and reducing friction loss. When temperature is adequate, the carrier frequency can be increased for better power conversion efficiency. This dynamic parameter adjustment resolves the contradiction between power conversion efficiency and friction loss.
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
The system effectively suppresses the increase in friction loss of rotary electric machines and gearboxes by optimizing temperature control, enhancing efficiency and performance by reducing energy consumption and NV characteristics.
Implementation Method 1
a heat exchanger in which heat exchange between a first temperature control medium circulating through the first temperature control circuit and a second temperature control medium circulating through the second temperature control circuit is performed
Implementation Method 2
a radiator with which heat exchange between the second temperature control medium and outside air is performed
Data Source
AI summary
A vehicle temperature control system includes: a first temperature control circuit; a second temperature control circuit; a heat exchanger in which heat exchange between a first temperature control medium and a second temperature control medium is performed; and a control device. The control device is capable of controlling a carrier frequency and a flow rate control valve of the second temperature control circuit based on the temperature of the first temperature control medium detected. In a case where the temperature of the first temperature control medium is lower than a predetermined value, the control device is configured to set the carrier frequency to be lower and controls the flow rate control valve such that the flow rate to a second branch flow path is smaller, as compared with a case where the temperature of the first temperature control medium is equal to or higher than the predetermined value.