PWM Control for Parallel Step-Up Converter Overheating
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Solution Overview
Problem
Existing electric power conversion systems experience significant power losses in switching elements during parallel step-up operations, leading to overheating issues due to overlapping currents and frequent switching, which are not adequately addressed by phase shift control alone.
Innovation Solution
The system employs an electronic control unit to adjust the on-time of PWM signals for the step-up circuits, ensuring the trailing edge of one signal connects with the leading edge of the other, and the combined on-time falls within a specific range, reducing overlap and switching losses by optimizing the PWM control period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PWM duty ratio is increased to improve voltage conversion efficiency, then power transfer increases, but switching element temperature rises due to increased power loss
Solution Approach 1:
The control unit monitors the temperature of switching elements and adjusts PWM signal timing accordingly, reducing on-time overlap when temperature exceeds thresholds to prevent overheating while maintaining voltage conversion efficiency
Solution Approach 2:
The patent dynamically adjusts PWM signal parameters (trailing edge connection timing) based on temperature conditions, optimizing the balance between power transfer efficiency and thermal management
2Speed
If switching frequency is increased to improve response speed, then voltage regulation speed increases, but switching loss increases due to more frequent on/off operations
Solution Approach 1:
The patent optimizes PWM signal timing parameters by connecting trailing edges to leading edges, reducing the effective switching frequency and loss while maintaining adequate voltage regulation response speed
Data Source
AI summary
An electronic control unit of an electric power conversion system is configured to, when voltages of first and second batteries are stepped up in parallel and a temperature of a common switching element exceeds a threshold temperature, execute on time change control such that following conditions i) and ii) are satisfied: i) a trailing edge of one of the first and second PWM signals and a leading edge of the other one of the first and the second PWM signals connect with each other; and ii) the sum of the on time of the first and second PWM signals in a single PWM control period falls within a range from the single PWM control period to an allowable period. The electronic control unit is configured to change an on time of at least one of the first and second PWM signal in the on time change control.