Inverter Thermal Management via Predictive Current Restriction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electric automobile inverter systems face overheating issues, particularly when driving on sloping roads under high torque conditions, leading to characteristic changes, impairment, and reduced lifespan, which can disrupt motor control and drivability.
Innovation Solution
A motor control device with a temperature sensor and inverter restricting unit that sets threshold values for electric current restrictions based on temperature regions, adjusting duty ratio and pulse number to maintain optimal inverter temperature, preventing overheating and ensuring reliable motor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inverter is provided with a cooling unit to prevent excessive heating, then the inverter is protected from temperature-related impairment, but the device complexity increases and the cooling system occupies additional space
Solution Approach 1:
The control device predicts future inverter temperature based on current temperature and heating rate, and proactively restricts electric current before excessive heating occurs. This preliminary action prevents the need for complex cooling systems while maintaining inverter reliability.
Solution Approach 2:
The system continuously monitors inverter temperature and heating rate, using this feedback to dynamically adjust electric current restrictions. This closed-loop control maintains reliability through real-time adaptation without requiring complex hardware cooling solutions.
2Reliability
If the driving current of the motor is restricted by monitoring excessive loading through temperature measurement, then the inverter is protected from overheating, but the drivability of the automobile is suddenly disturbed
Solution Approach 1:
The system predicts temperature trends and restricts electric current before excessive heating occurs, preventing sudden drivability disturbances while still protecting the inverter. The prediction-based approach allows smoother transitions compared to reactive temperature-based restrictions.
Solution Approach 2:
The electric current restriction is dynamically adjusted based on predicted temperature and heating rate, allowing the system to maintain optimal current levels rather than applying fixed restrictions. This dynamic control preserves drivability while ensuring inverter protection.
3Power
If the inverter operates under high torque generating condition for a long time, then the motor performance is maintained, but the inverter temperature excessively increases leading to characteristic change and impairment
Solution Approach 1:
The system predicts inverter temperature based on current temperature and heating rate, and proactively restricts electric current command before excessive heating occurs during high torque operation. This prevents characteristic change and impairment while allowing sustained motor performance within safe temperature limits.
Solution Approach 2:
The patent replaces physical cooling mechanisms with a control-based thermal management system that uses temperature prediction and electric current restriction. This substitution maintains power output while controlling temperature through software logic rather than hardware cooling.
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 effectively prevents inverter characteristic changes, impairment, and lifespan reduction, maintaining motor performance and avoiding sudden drivability disruptions by meticulously controlling inverter temperature through dynamic electric current management.
Implementation Method 1
a temperature sensor Sa provided in the inverter 31 to detect the temperature Tc of the inverter 31
Implementation Method 2
an inverter 31 to convert a direct current power of a battery into an alternating current used in driving the motor 6
Implementation Method 3
an inverter 31 to convert a direct current power of a battery into an alternating current used in driving the motor 6
Implementation Method 4
the inverter is supplied with a large amount of electric current for the motor drive, heat generation is considerable
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An inverter (31) is provided with a temperature sensor (Sa) for detecting the temperature (Tc) of the inverter (31). A plurality of threshold values are set up for the temperature (Tc) detected by the temperature sensor (Sa), electric current restricting conditions different from each other are set up for each of the temperature regions sorted out by each threshold value, and an inverter restricting unit (95) for applying a restriction to an electric current command applied to the inverter (31) in dependence on the electric current restricting condition of the temperature region, in which the detected temperature (tc) is included, is provided. Without the drivability of an automobile being disturbed, by means of a temperature control of the inverter (31), not only are any change in characteristic and impairment, resulting from an overheating thereof, prevented, but also an undesirable reduction of the life of the inverter (31) is avoided.