Power Conversion System Current Balance via Temperature Feedback
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Solution Overview
Problem
Power conversion systems with parallel-connected power modules face current unbalance and temperature rise due to variations in module characteristics and cooling system arrangements, leading to operational defects and reduced service life.
Innovation Solution
A power conversion system that includes temperature detection and calculation sections to estimate current switching characteristics and calculate correction values for input signals to drive circuits, aligning ON/OFF timings and reducing current variations among power modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If power modules are connected in parallel to increase output capacity, then system power capability is improved, but current unbalance and temperature rise occur due to characteristic variations
Solution Approach 1:
The system dynamically adjusts switching timing parameters based on detected temperature variations. The calculation section computes correction values that modify ON/OFF timings of switching devices according to their individual temperature-dependent characteristics, thereby maintaining balanced current distribution across parallel power modules despite manufacturing variations and temperature changes
2Manufacturing precision
If switching device characteristics are adjusted based on test results, then initial current unbalance is reduced, but temperature variations during operation cause deviation from optimal adjustment
Solution Approach 1:
The system implements real-time temperature monitoring using detection sections that measure operating temperatures of individual power modules. These temperature measurements feed back to the calculation section, which continuously computes and updates correction values for switching timings, ensuring optimal current balance is maintained throughout operation despite temperature drift from initial test conditions
Solution Approach 2:
The system transitions from static adjustment based on initial test results to dynamic adjustment that adapts to changing operating conditions. The correction values are not fixed but are continuously updated based on real-time temperature measurements, allowing the switching timings to adapt dynamically to thermal effects during operation
3Reliability
If ON/OFF timings are adjusted based on electrical characteristic information, then current sharing is improved, but temperature-dependent characteristic changes cause adjustment deviation
Solution Approach 1:
The system changes the timing parameters of switching operations based on detected temperature conditions. By measuring actual operating temperatures and calculating appropriate correction values, the system adapts its switching characteristics to compensate for temperature-dependent variations in power module performance, maintaining reliable current sharing across different thermal states
Data Source
AI summary
A power conversion system includes: a plurality of power modules connected in parallel to each other, a plurality of drive circuits driving the plurality of power modules based on input signals respectively; a plurality of correction sections correcting the input signals inputted to the plurality of drive circuits based on a plurality of correction values respectively; a temperature detection section detecting operating temperatures of the plurality of power modules; and a calculation section estimating current switching characteristics of the plurality of power modules based on the measured operating temperatures and temperature dependency of switching characteristics of the plurality of power modules, and calculating the plurality of correction values based on the estimated current switching characteristics so as to reduce variations of currents flowing through the plurality of power modules.