Dynamic Turn-Off Speed Control for Power Converter Loss Reduction
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Solution Overview
Problem
Existing power converters in electric vehicles experience high electrical losses due to slow turn-off speeds of semiconductor switches, leading to inefficient energy conversion and increased power consumption.
Innovation Solution
A method for operating a power converter that dynamically adjusts the turn-off speed of semiconductor switches based on real-time monitoring of intermediate circuit voltage, operating temperature, and load current, allowing for flexible adaptation to different operating conditions and optimizing switch-off speeds for reduced electrical losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the semiconductor switches are switched off quickly, then the electrical losses are reduced, but the turn-off time increases due to slow turn-off speed
Solution Approach 1:
The patent applies dynamics by making the turn-off speed adjustable rather than fixed. The control device dynamically adapts the turn-off speed of the semiconductor switches based on real-time operating conditions (temperature, voltage, current). This allows the system to optimize between fast turn-off (for low losses) and controlled turn-off (for reliability) depending on the operating state, directly resolving the contradiction between reducing electrical losses and managing turn-off speed limitations
Solution Approach 2:
The patent changes the parameter of turn-off speed from a static characteristic to a dynamically adjustable parameter. By modifying the turn-off speed parameter according to operating conditions (using different gate resistance values based on temperature, voltage, and current thresholds), the system can achieve fast turn-off when conditions permit (reducing electrical losses) while preventing excessive turn-off speeds under unfavorable conditions, thus resolving the contradiction
2Productivity
If the turn-off speed is increased to reduce electrical losses, then the efficiency improves, but the risk of exceeding maximum permissible switching rates increases
Solution Approach 1:
The patent implements feedback control by continuously monitoring operating parameters (temperature, voltage, current) and using this information to adjust the turn-off speed. The control device receives feedback from sensors and adapts the gate resistance values accordingly, ensuring that the turn-off speed never exceeds safe limits while maximizing efficiency within those limits. This feedback mechanism directly resolves the contradiction between improving efficiency and maintaining reliability
Solution Approach 2:
The system dynamically adjusts the turn-off speed based on real-time operating conditions rather than using a fixed speed. By making the turn-off speed adaptive, the system can operate at high speeds (for efficiency) when conditions are favorable and automatically reduce speed (for safety) when conditions approach critical thresholds, thus resolving the contradiction between efficiency and reliability
3Device complexity
If a fixed turn-off speed is used, then the control is simple, but the electrical losses cannot be optimized across different operating ranges
Solution Approach 1:
The patent changes the control approach from fixed parameters to variable parameters. Instead of using a single fixed turn-off speed, the system varies the turn-off speed parameter (through gate resistance adjustment) based on operating conditions. This parameter change enables optimization of electrical losses across different operating ranges while maintaining manageable control complexity through structured decision logic
Solution Approach 2:
The patent segments the operating range into different regions based on temperature, voltage, and current thresholds. Each segment is assigned an appropriate turn-off speed strategy, allowing optimization for specific operating conditions without requiring complex continuous control. This segmentation approach resolves the contradiction by enabling targeted optimization in different operating ranges while keeping the overall control structure manageable
Data Source
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AI summary
The invention relates to a method for operating a current converter (8), in particular of an electric machine (2), in which, for the or for each semiconductor switch (22) of the current converter (8), a control signal (P') for setting a switch-off speed (Anew) is generated, wherein an electric intermediate circuit voltage (Udc) of an intermediate circuit (10) is measured and compared to a voltage threshold value (Uthresh), wherein an operating temperature (TB) of the respective semiconductor circuit (22) is measured and compared to a temperature threshold value (Tthresh), wherein a load current (Ic) switched by means of the respective semiconductor circuit (22) is measured and compared to a current threshold value (Ithresh), and wherein the control signal (P') for setting the switch-off speed (Anew) is generated on the basis of the comparisons.