Chopper Frequency Synchronization to Minimize Ripple and Loss
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Solution Overview
Problem
Existing power conversion devices experience increased ripple due to inappropriate timing in changing switching frequency, which is not addressed by conventional methods.
Innovation Solution
A power conversion device with synchronized detection and switching frequency control, utilizing a control unit that includes a voltage control unit, frequency control unit, and carrier generation unit, which adjusts switching frequency and detection timing to minimize ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If switching frequency is changed to minimize losses in the chopper circuit, then energy efficiency is improved, but ripple increases due to inappropriate timing of frequency change
Solution Approach 1:
The control unit determines the optimal switching frequency in advance based on detected voltage and current values, then applies this frequency at the appropriate timing. This preliminary determination allows the system to minimize losses while avoiding ripple increase by carefully timing when frequency changes are applied.
Solution Approach 2:
The system continuously detects voltage and current values, calculates losses based on these measurements, and adjusts switching frequency accordingly. This closed-loop feedback mechanism ensures that frequency changes are made at optimal moments to minimize losses without causing excessive ripple.
2Loss of energy
If switching frequency is optimized based on loss calculation, then energy efficiency is improved, but system complexity increases due to additional control mechanisms
Solution Approach 1:
The control unit performs multiple functions: detecting voltage and current, calculating losses, determining optimal frequency, and generating gate signals. By consolidating these functions in a single multi-functional control unit, the patent avoids adding separate dedicated components for each function, thereby limiting the increase in system complexity.
Solution Approach 2:
The system optimizes performance by dynamically changing the switching frequency parameter based on calculated losses. This approach allows energy efficiency improvement through parameter optimization without requiring fundamental changes to the hardware architecture, thus avoiding excessive complexity increase.
Data Source
AI summary
An object is to obtain a power conversion device that can prevent ripple from increasing owing to change in switching frequency. A power conversion device includes: semiconductor switching elements connected between a DC voltage source and an output side, and connected in series to each other; a reactor; a control unit which controls a switching frequency of each semiconductor switching element; and a voltage detector, a voltage detector, and a current detector which respectively detect a voltage value of an input voltage, a voltage value of an output voltage, and a current value of an inductor current. Changing of the switching frequency and detection of the voltage value of the input voltage, the voltage value of the output voltage, and the current value of the inductor current are each performed at a timing that allows synchronization with a carrier.