Electronic Converter Control for Zero-Voltage Switching
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Solution Overview
Problem
Electronic converters face challenges in achieving Zero Voltage Switching (ZVS) due to high circulating Root Mean Square (RMS) current, which leads to electrical losses and electromagnetic emissions, especially for auxiliary switches in low to medium power converters.
Innovation Solution
An electronic converter with a self-adjusting control mechanism that includes a measurement circuit to detect the derivative of the voltage across the main switch, allowing for the variation of the duration of the closed state of the auxiliary switch to achieve ZVS, thereby reducing RMS current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional switching control is used in electronic converters, then the converter can operate with simple control circuitry, but high circulating RMS current causes electrical losses and electromagnetic emissions
Solution Approach 1:
The patent implements a feedback mechanism where the control circuit continuously monitors the voltage across the auxiliary switch and uses this information to dynamically adjust the switching timing. The control circuit detects when the voltage across the auxiliary switch reaches a predetermined threshold level, and uses this feedback signal to trigger the main switch closure, ensuring Zero Voltage Switching conditions are met while maintaining simple overall circuit architecture
Solution Approach 2:
The control circuit automatically adjusts the auxiliary switch duration based on real-time voltage conditions without external intervention. The system self-regulates by detecting the voltage derivative and autonomously determining the optimal moment to close the main switch, eliminating the need for complex external control mechanisms while minimizing electrical losses
2Reliability
If the auxiliary switch remains closed for a fixed duration, then the control circuit is simple, but Zero Voltage Switching cannot be achieved under varying load conditions
Solution Approach 1:
The patent transitions from static fixed-duration auxiliary switching to dynamic adaptive switching. The control circuit continuously monitors the voltage derivative across the auxiliary switch and adjusts the auxiliary switch closure duration in real-time based on actual circuit conditions, enabling reliable Zero Voltage Switching achievement while maintaining relatively simple control implementation through natural voltage signal detection
3Object-generated harmful factors
If high RMS current is allowed to flow, then the converter can maintain simple switching operation, but electromagnetic emissions increase
Solution Approach 1:
The control circuit performs preliminary action by monitoring the voltage derivative across the auxiliary switch and determining the optimal switching moment in advance. By detecting when the voltage reaches the predetermined threshold level before actually closing the main switch, the system prepares the circuit for Zero Voltage Switching, thereby minimizing electromagnetic emissions while maintaining efficient power conversion operation
Data Source
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AI summary
There is described an electronic converter. The electronic converter includes two input terminals (112a, 112b) and two output terminals. Two electronic switches (S1, S2) are connected in series between both input terminals, wherein a respective capacitance (CA1, CA2) is associated with each one of the electronic switches (S1, S2), wherein one of both electronic switches represents a main switch, and the other one of both electronic switches represents an auxiliary switch. A reactive circuit (R) is connected between the intermediate point between both electronic switches (S1, S2) and the two output terminals. A control circuit (118') is configured to drive the switching of both electronic switches (S1, S2) via respective drive signals, wherein the control circuit (118') is configured to repeat the following steps periodically: - while the auxiliary switch is opened, closing the main switch for a first interval, wherein the control circuit varies the duration of the first interval as a function of the output voltage or current; - opening the auxiliary switch and the main switch for a second interval; - while the main switch is opened, closing the auxiliary switch for a third interval; - opening the auxiliary switch and the main switch for a fourth interval, wherein the duration of the fourth interval is constant. Specifically, the electronic converter includes a measurement circuit (122) configured to detect a measurement signal (VD) indicative of the derivative of the voltage (VSW) across the main switch or the auxiliary switch, and the control circuit (118') varies the duration of the third interval as a function of said measurement signal, in such a way as to allow a Zero Voltage Switching of the main switch at the start of the first interval.