Step-Up Converter Switching Loss Reduction
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Solution Overview
Problem
Step-up converters experience increased switching losses due to parasitic capacitance in switching elements, which are exacerbated by the need to manage energy storage and discharge efficiently during the demagnetization and magnetization phases.
Innovation Solution
The method involves cyclic actuation of two switching elements, where the first switching element applies the input voltage to an inductive storage element and the second switching element acts as a rectifier, with specific timing and monitoring to ensure complete discharge of parasitic capacitance and minimize switching losses by using a second capacitive storage element and a compensating actuating circuit to manage current direction changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the switching element is turned on cyclically to store energy in the inductive storage element, then the step-up converter can transfer energy from input to output, but the parasitic capacitance of the switching element is charged to the output voltage during the turned-off period and discharged when turned on again, resulting in increased switching losses
Solution Approach 1:
The patent extracts the parasitic capacitance discharge function from the main power transfer path by introducing a separate discharge path through the second switching element. This allows the parasitic capacitance to be discharged independently through a dedicated current path that includes the inductive storage element, thereby separating the energy dissipation function from the power transfer function and reducing switching losses in the first switching element
Solution Approach 2:
The patent introduces a second switching element as an intermediary component that mediates the discharge process of the parasitic capacitance. This intermediary element enables controlled discharge through the inductive storage element without directly interfering with the main power transfer operation of the first switching element, thus reducing electromagnetic interference and switching losses
2Productivity
If the first switching element is turned on immediately after the inductive storage element is completely demagnetized, then the converter operates with high frequency and good regulation, but the parasitic capacitance is not fully discharged leading to increased switching losses and electromagnetic interference
Solution Approach 1:
The patent implements preliminary action by ensuring the parasitic capacitance is fully discharged before the first switching element is turned on again. The control circuit monitors the discharge current through the inductive storage element and only permits re-turning on after the discharge current returns to zero, thereby preliminarily eliminating the harmful voltage across the parasitic capacitance and preventing electromagnetic interference and switching losses
Solution Approach 2:
The patent employs feedback control by monitoring the current through the inductive storage element during the discharge phase and using this information to control the timing of the first switching element's re-turning on. The control circuit detects when the discharge current has returned to zero and uses this feedback signal to trigger the next switching cycle, ensuring complete discharge and minimizing electromagnetic interference
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces switching losses and ensures complete discharge of parasitic capacitance, minimizing power loss and electromagnetic interference, while maintaining a stable output voltage.
Implementation Method 1
During this turned-on period, energy is stored in the inductive storage element and the inductive storage element is magnetized thereby. When the switching element has been turned off, this stored energy is output to the rectifier arrangement.
Implementation Method 2
If the switching element has a parasitic capacitance, this capacitance is charged to the output voltage during the turned-off period and is discharged when the switching element is turned on again.
Data Source
AI summary
A system and method for controlling a converter. One embodiment provides the cyclic actuation of a first switching element, used for applying an input voltage to an inductive storage element. A second switching element is used as a first rectifier element in a rectifier arrangement, in a step-up converter. An actuating circuit is provided for the first and second switching elements.