Multi-Inverter Coolant Flow Control for Uneven Thermal Loads
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Solution Overview
Problem
Existing multi-inverter propulsion systems in electric vehicles face inefficiencies in coolant distribution, as fixed portion ratios of coolant flow to inverters do not adapt to changing operating conditions, leading to insufficient cooling, especially when one inverter is more heavily loaded.
Innovation Solution
A cooling system with an adjustable flow valve and coolant pump, controlled by a controller that determines and adjusts coolant flow rates based on commanded torque, speed, and net losses of each inverter to optimize coolant distribution, allowing for a ratio of up to 5:1 between inverters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If fixed portion ratios of coolant flow are used to distribute coolant to inverters, then the system structure is simple and easy to manufacture, but the cooling effectiveness is insufficient when inverters have significantly different loadings
Solution Approach 1:
The patent applies dynamics by replacing fixed coolant flow distribution with adjustable flow valves that can dynamically change the proportion of coolant flow to each inverter based on real-time loading conditions. The controller receives loading information from each inverter and adjusts valve positions accordingly, enabling the system to adapt to varying operational demands and maintain optimal cooling effectiveness.
Solution Approach 2:
The patent implements parameter changes by varying the coolant flow rate parameters to each inverter based on their respective loading levels. The system calculates optimal flow rates according to inverter loading and adjusts the physical flow parameters through controllable valves, allowing each inverter to receive appropriate cooling proportional to its thermal load.
2Adaptability or versatility
If fixed diameter ratio T-connections are used to distribute coolant, then the manufacturing is simple, but the coolant flow proportion does not adapt to changing operating conditions
Solution Approach 1:
The system transitions from static fixed-orifice T-connections to dynamic controllable flow valves that can adjust coolant distribution in real-time. Each valve is controlled independently based on inverter loading conditions, enabling the system to adapt to various operating scenarios while maintaining manageable manufacturing complexity through standardized valve components.
Solution Approach 2:
The patent replaces the purely mechanical fixed-orifice distribution system with an electro-hydraulic or electro-pneumatic control system. The controller receives electrical signals from inverter loading sensors and actuates the flow valves accordingly, substituting fixed mechanical flow restriction with controllable actuated valves that respond to electrical control signals.
3Productivity
If equal coolant flow is provided to all inverters, then the distribution system is simple, but heavily loaded inverters do not receive sufficient cooling
Solution Approach 1:
The patent applies local quality by providing differentiated coolant flow rates to each inverter based on its specific loading condition. Instead of uniform cooling, each inverter receives a customized flow rate proportional to its thermal load, with heavily loaded inverters receiving higher flow rates and lightly loaded inverters receiving lower flow rates, optimizing overall system cooling efficiency.
Solution Approach 2:
The system implements feedback control where the controller continuously monitors inverter loading conditions and uses this information to adjust flow valve positions. The loading information from each inverter feeds back to the controller, which calculates the optimal flow distribution and commands the valves accordingly, creating a closed-loop control system that optimizes cooling efficiency.
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 enables more precise control of coolant flow, reducing net losses and maintaining inverter temperatures within thresholds, thereby enhancing the efficiency and longevity of the drivetrain and its components.
Implementation Method 1
a coolant pump is positioned along the coolant circuit to urge the flow of coolant through the coolant circuit at a selected coolant flow rate
Implementation Method 2
a heat exchanger is positioned along the coolant circuit to reject heat from the flow of coolant
Data Source
AI summary
A cooling system for a drivetrain of an electric vehicle includes a coolant circuit directing a flow of coolant through a first inverter and a second inverter of the drivetrain, and an adjustable flow valve positioned along the coolant circuit to selectably alter proportions of the flow of coolant directed through each of the first inverter and the second inverter. A method of operating a cooling system for a first inverter and a second inverter of a vehicle drivetrain includes commanding a speed and torque of each of the first and second inverter, and estimating losses and temperature of each of the first inverter and the second inverter as a result of the commanded speed and torque. A valve position of an adjustable flow valve operably connected to the first inverter and the second inverter is selected, and a change of the valve position is commanded.