Adaptive Startup Control for Electric Drives
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Solution Overview
Problem
In aerospace and military applications, electric drives face challenges with high startup temperatures due to delayed coolant availability, leading to excessive peak junction temperatures during startup, which can result in thermal shutdowns and require costly thermal enhancements to manage heat loads effectively.
Innovation Solution
An adaptive startup control method that initially starts the electric drive at full performance, monitors junction temperatures, adjusts speed or current commands to maintain safe temperatures until coolant reaches steady-state, and gradually increases power once temperatures are within limits, using a junction temperature estimator based on baseplate temperature and inverter losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the electric drive is started at full performance immediately, then the startup time is reduced and productivity is improved, but the junction temperature spikes excessively causing thermal shutdowns and reliability issues
Solution Approach 1:
The control system dynamically adjusts the power output of the electric drive during startup based on real-time coolant temperature conditions. The controller transitions from full-power operation to a controlled power reduction when high junction temperature is detected, and then gradually increases power as coolant temperature decreases, creating a dynamic adaptation to thermal conditions
Solution Approach 2:
The system implements feedback control by monitoring the coolant temperature and junction temperature estimates, then adjusting the power output accordingly. The controller continuously compares actual temperature conditions against safe operating limits and modifies the drive performance to maintain reliability while minimizing startup time
2Reliability
If thermal enhancements are added to manage heat loads, then semiconductor temperature control is improved and reliability increases, but device complexity and cost increase
Solution Approach 1:
The patent replaces complex mechanical thermal management enhancements with a control-based solution. Instead of adding physical thermal inertia or complex cooling systems, the invention uses software control to dynamically adjust power output based on temperature monitoring, substituting mechanical/physical solutions with electronic control
3Reliability
If thermal inertia is increased to limit maximum junction temperatures, then semiconductor temperature control is improved, but device weight increases
Solution Approach 1:
The control system uses real-time temperature feedback to adjust power output, eliminating the need for increased thermal inertia. The controller monitors junction temperature estimates and coolant temperature, then dynamically modulates power delivery to maintain safe operating temperatures without requiring additional thermal mass
Solution Approach 2:
The system changes the operational parameters of the electric drive during startup by reducing power output when temperature limits are approached. This parameter adjustment allows the same thermal mass to handle higher temperature excursions by controlling the heat generation rate rather than increasing heat capacity
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 method reduces peak junction temperatures, minimizes thermal inertia requirements, and allows for efficient operation without extensive thermal enhancements, enabling faster startup and reduced weight and cost while maintaining reliable semiconductor temperatures.
Implementation Method 1
a junction temperature estimator that estimates a junction temperature of the power modules based on baseplate temperature and inverter losses
Data Source
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AI summary
A controlled start up technique may eliminate the excessive peak junction temperature by controlling the speed of the electric device. Lower speed may result in reduced power to the load. Reduced power may result in reduced losses to maintain reliable operating junction temperatures, Once the junction reaches the predetermined temperature limit, speed may be controlled to hold the junction temperature constant. As time elapses, the coolant temperature may reduce, thereby allowing a higher power lever without an increase in IGBT temperature. Unlike conventional methods which may allow for full power continuously upon start up, thereby either potentially causing a high temperature shut-down condition or requiring additional thermal inertia to handle a high heat load due to a continuous full-power start up, the controlled start up eliminates the design penalties for extensive thermal enhancements to accommodate the occasional extreme hot start up.