Interleaved Totem-Pole Converter ZVS via Auxiliary Inductor Control
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Solution Overview
Problem
Existing CCM totem-pole converters face challenges in achieving Zero Voltage Switching (ZVS) without additional active circuits, leading to increased losses and complexity due to the need for additional semiconductor and magnetic components.
Innovation Solution
An interleaved totem-pole power converter with a single auxiliary inductor and a frequency variation modulation control strategy, which adjusts the switching frequency at each switching instant to ensure ZVS in high frequency devices while minimizing reactive current circulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional active circuits are added to achieve ZVS in CCM totem-pole converter, then ZVS operation is guaranteed, but device complexity and losses increase due to additional semiconductor devices and magnetic components
Solution Approach 1:
The patent extracts and eliminates the need for additional active auxiliary circuits by using a passive inductor combined with frequency variation modulation. This removes the harmful complexity while preserving the beneficial ZVS operation through a simpler circuit configuration.
Solution Approach 2:
The patent changes the operating frequency parameter dynamically to achieve ZVS. By varying the switching frequency based on load conditions, the system achieves zero voltage switching without requiring additional active circuits, thus resolving the contradiction between reliability and device complexity.
2Reliability
If fixed frequency operation is used with auxiliary inductor, then ZVS current can be produced, but excessive reactive current circulates at lighter loads increasing losses
Solution Approach 1:
The patent makes the switching frequency dynamic rather than fixed. The frequency varies with load conditions, allowing the auxiliary inductor to produce exactly the required ZVS current without excessive circulation. This dynamic adjustment eliminates the energy losses at lighter loads while maintaining ZVS reliability.
Solution Approach 2:
The patent implements feedback control where the switching frequency is adjusted based on the actual load conditions and the current through the auxiliary inductor. This ensures that the reactive current is optimized to achieve ZVS without excessive circulation, reducing energy losses.
3Power
If higher switching frequency is used to increase power density, then power density improves, but ZVS becomes harder to achieve without active auxiliary circuits
Solution Approach 1:
The patent introduces a passive inductor as an intermediary element that facilitates ZVS at higher frequencies. This inductor, combined with frequency variation modulation, acts as a mediator that enables high power density operation while maintaining reliable ZVS without requiring complex active auxiliary circuits.
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
The solution achieves optimal ZVS with minimal reactive current circulation, reducing losses and complexity, and maintaining high efficiency and power density in totem-pole converters.
Implementation Method 1
The auxiliary inductor connected in between switching legs of the converter formed by the pairs of high frequency switching devices
Implementation Method 2
by changing a switching frequency of the high frequency switching devices at each switching instant
Data Source
AI summary
An interleaved totem-pole power converter (500) includes a direct current, DC, capacitor (502), a pair of low frequency switching devices (504a and 504b) connected in series with each other and in parallel with the DC capacitor and two pairs of high frequency switching devices (506 a, 506b, 506c and 506d) connected in series with each other and in parallel with the DC capacitor (502). The two pairs of high frequency switching devices (506 a, 506b, 506c and 506d) are connected in an interleaving manner to a first output inductor (508a) and a second output inductor (508b) which are connected to an alternating current, AC, capacitor (512), and a resistive load is connected in parallel with the AC capacitor. An auxiliary inductor (510) is connected in between switching legs of the converter (500) with a control system (516,704) configured for regulating a current circulation through the auxiliary inductor (510).