Integrated Motor-Inverter Cooling Loop for Low-Viscosity Coolant Flow
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Solution Overview
Problem
Existing cooling systems for electric drive systems, which include both motors and inverters, are inefficient as they require separate coolant flow passages for each component, increasing weight and reducing mobility and fuel economy of moving objects.
Innovation Solution
A cooling system that uses a single circulating flow passage with a coolant to cool both the motor and inverter, where an inverter controller adjusts current values to increase heat generation when coolant temperature is low, maintaining output torque and reducing viscosity, thus minimizing pump size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate coolant flow passages are used for motor and inverter cooling, then each component can be cooled effectively, but the overall system weight increases and mobility decreases
Solution Approach 1:
The patent combines the motor cooling passage and inverter cooling passage into a single integrated coolant flow passage. The coolant flows sequentially through the motor cooler and inverter cooler within the same circulation loop, eliminating the need for separate cooling systems while maintaining effective cooling of both components. This merging reduces system weight and improves mobility without sacrificing cooling performance.
2Temperature
If coolant temperature is low, then cooling efficiency is high, but coolant viscosity increases and flow rate decreases
Solution Approach 1:
The patent implements a temperature detection mechanism that monitors coolant temperature and provides feedback to the control system. When the coolant temperature is detected to be at or below a predetermined threshold, the system automatically increases the d-axis current component of the motor current. This feedback loop enables the system to respond dynamically to temperature changes and adjust operating parameters accordingly.
Solution Approach 2:
The patent changes the electrical operating parameters of the motor by increasing the d-axis current component when coolant temperature is low. This parameter change increases the amount of heat generated by the motor, which warms the coolant and reduces its viscosity. The result is improved coolant flow rate and circulation efficiency without requiring additional pumping power.
3Quantity of substance
If d-axis current is increased to warm coolant, then coolant viscosity decreases and flow improves, but motor torque may deviate from target
Solution Approach 1:
The patent adjusts the d-axis current component of the motor current to change the motor's internal resistance heating, which warms the coolant and reduces viscosity. By carefully controlling the magnitude of the d-axis current increase, the system achieves sufficient warming effect while keeping torque deviation within acceptable limits. This parameter adjustment strategy balances thermal management needs with torque control requirements.
Solution Approach 2:
The patent converts the potentially harmful effect of increased d-axis current (which causes torque deviation) into a beneficial effect by utilizing the additional resistive heating to warm the coolant. The controlled torque deviation is accepted as a temporary trade-off to achieve the greater benefit of improved coolant flow and thermal management. The system effectively transforms a control challenge into a thermal solution.
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 configuration reduces the overall weight of the cooling system, maintains output torque, and prevents uncomfortable deviations, ensuring efficient coolant flow and reduced system size.
Implementation Method 1
a first cooler configured to cool the motor by heat exchange using a coolant flowing through the first cooler
Implementation Method 2
a second cooler configured to cool the inverter by heat exchange using the coolant flowing through the second cooler
Implementation Method 3
an pump arranged in the circulating flow passage to pump the coolant
Implementation Method 4
a temperature sensor configured to detect a coolant temperature which is a temperature of the coolant circulating in the circulating flow passage
Data Source
AI summary
Disclosed is a cooling system for cooling an electric drive system. The electric drive system includes a motor and an inverter configured to drive the motor. The cooling system includes a first cooler, a second cooler, a circulating flow passage and a pump. The first cooler is configured to cool the motor by heat exchange using a coolant flowing through the first cooler. The second cooler is configured to cool the inverter by heat exchange using the coolant flowing through the second cooler. The circulating flow passage passes through both the first and second coolers, and the coolant circulates in the circulating flow passage. The pump is arranged in the circulating flow passage to pump the coolant.