Electric Power Converter Phase Control for Switching Loss Reduction
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Solution Overview
Problem
Existing electric power converters in hybrid and electric vehicles face challenges in reducing switching losses of specific switching elements without compromising output voltage or current values, particularly in parallel mode operations.
Innovation Solution
An electric power converter with a controller that manages switching elements by using phase difference settings between PWM signals to minimize the number of ON-OFF cycles of specific switching elements, thereby reducing heat generation and switching losses, while maintaining output characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If phase difference control between PWM signals is applied to reduce switching losses, then switching loss of specific switching elements is reduced, but output voltage or current values may be limited
Solution Approach 1:
The patent dynamically adjusts the phase difference between PWM signals based on the operating mode (series or parallel) and operational state. The control is not fixed but adapts in real-time to maintain output characteristics while minimizing switching losses. This dynamic adjustment allows the system to optimize switching element operation without compromising output voltage or current capabilities.
Solution Approach 2:
The patent changes the phase difference parameter between PWM signals as a control variable to reduce switching losses. By adjusting this parameter differently in series mode versus parallel mode, the system achieves loss reduction while preserving full output voltage and current value ranges. The parameter change is strategically applied only to timing relationships, not to the fundamental power conversion capability.
2Temperature
If switching frequency of specific switching elements is reduced to minimize heat generation, then heat generation is suppressed, but power conversion efficiency may deteriorate
Solution Approach 1:
The patent applies local quality control by targeting specific switching elements for phase difference adjustment rather than uniformly controlling all switching elements. This allows selective reduction of switching frequency and heat generation in particular elements while maintaining optimal switching performance in others, thereby preserving overall power conversion efficiency while suppressing heat generation where needed.
Data Source
AI summary
An electric power conversion unit of an electric power converter establishes two converter circuits including four switching elements and two batteries and carries out electric power conversion in a parallel mode in which the batteries are connected in parallel with each other. A controller is configured to set a control signal for each of the switching elements, identify a target switching element of which a temperature is suppressed, determine a state having a maximum loss value in correspondence with input-output data, and execute phase control for suppressing the maximum loss value.