Power Converter Switching Frequency Control for Thermal Overload Prevention
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Solution Overview
Problem
Conventional power converter control methods fail to effectively prevent thermal overload caused by exceeding maximum switching frequency or current, leading to potential damage and increased complexity and cost.
Innovation Solution
A method and system that determine two switching frequencies, one based on current/torque and the other on rotor speed, with the controller selecting the lesser frequency to control the power converter, thereby preventing thermal overload.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the switching frequency is increased to improve power converter efficiency, then the efficiency is improved, but thermal overload occurs causing potential damage
Solution Approach 1:
The patent implements dynamic adjustment of switching frequency based on real-time temperature feedback from power transistors. The control system continuously monitors transistor temperatures and adjusts the switching frequency accordingly, allowing the system to operate at higher frequencies when cool and reduce frequency when temperature rises, thus preventing thermal overload while maximizing efficiency during normal operation.
Solution Approach 2:
The patent employs a feedback mechanism where temperature sensors monitor the thermal state of power transistors and feed this information back to the control system. The controller uses this temperature feedback to dynamically adjust the switching frequency, creating a closed-loop control system that prevents thermal overload while maintaining optimal efficiency.
2Device complexity
If conventional single-frequency control is used to simplify the control system, then the device complexity is reduced, but thermal overload protection is insufficient
Solution Approach 1:
The patent transitions from static single-frequency control to dynamic multi-frequency control based on temperature conditions. The controller selectively applies different switching frequencies (first switching frequency for normal operation, second switching frequency for high-temperature conditions) based on real-time temperature feedback, providing adequate thermal protection without requiring complex control circuits.
Solution Approach 2:
The patent changes the switching frequency parameter dynamically based on temperature conditions. Instead of using a fixed frequency, the system switches between at least two different frequency values depending on the thermal state of the power transistors, providing simple yet effective thermal overload protection through parameter adjustment.
3Reliability
If temperature-based power sharing is implemented to balance power converters, then thermal protection is improved, but the maximum current is not directly controlled leading to potential damage
Solution Approach 1:
The patent directly controls the switching frequency parameter based on temperature feedback, which inherently limits the maximum current that can flow through the power transistors. By reducing the switching frequency when temperatures rise, the system directly controls current levels to prevent thermal overload, providing both thermal protection and current limitation through a single control mechanism.
Data Source
AI summary
A method of controlling a power converter in an electric drive machine is disclosed. The method may include determining a first switching frequency and determining a second switching frequency. The method may also include comparing the first switching frequency and the second switching frequency. The method may further include selecting a power converter switching frequency from the lesser of the first switching frequency and the second switching frequency to control a power converter.