Active-clamp flyback converter and operating method therefor
A multilevel converter topology with flying capacitors and an active-clamp circuit in flyback converters addresses voltage spikes, enabling the use of lower voltage-rated semiconductors and enhancing efficiency.
WO2026008280A1 Publication Date: 2026-01-08ROBERT BOSCH GMBH
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Patent Information
- Application Number
- PCT/EP2025/066571
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2024-07-02
- Filing Date
- 2025-06-13
- Publication Date
- 2026-01-08
AI Technical Summary
Technical Problem
Flyback converters in electric vehicles face challenges with voltage spikes exceeding the dielectric strength of semiconductor components due to reflected voltages from the transformer's secondary coil, limiting the selection of suitable components and increasing costs.
Method used
Implementing a multilevel converter topology with a quasi-2-level (Q2L) operating principle using flying capacitors to distribute voltage spikes across multiple semiconductor switches, coupled via flying capacitors, and an active-clamp circuit to manage switching sequences.
Benefits of technology
This approach allows the use of lower voltage-rated semiconductor devices, reducing component costs and improving switching efficiency by evenly distributing voltage loads.
✦ Generated by Eureka AI based on patent content.
Abstract
The invention relates to a method for operating a flyback converter (2) having an active-clamp circuit (4), a main switching branch (3) being connected to a primary-side coil (51) of a transformer (5) in series between a first supply potential (VH) and a second supply potential (VL), the active-clamp circuit (4) being connected to a central node (M) between the main switching branch (3) and the primary-side coil (51) and one of the supply potentials (VH, VL), the active-clamp circuit (4) having an active-clamp switching branch (42) in series with an active-clamp capacitance (41), the main switching branch (3) and the active-clamp switching branch (42) each having two or more series-connected semiconductor switches (31, 32, 43, 44), one or more flying capacitances (7) each being connected to an intermediate node (ZH, ZAC) between the series-connected semiconductor switches (31, 32) of the main switching branch (3) and to an intermediate node between the series-connected semiconductor switches (43, 44) of the active-clamp switching branch (42), wherein the semiconductor switches (31, 32, 43, 44) of the main switching branch (3) and the active-clamp switching branch (42) are each switched to open and close in chronological succession, wherein, in order to open or close the main switching branch (3) and the active-clamp switching branch (42), that semiconductor switch (31, 32, 43, 44) of the main switching branch (3) or active-clamp switching branch (42) in question that leads to a current path through a freewheeling diode of at least one of the semiconductor switches (31, 32, 43, 44) of the other, main switching branch (3) or active-clamp switching branch (42) is opened or closed first so that a voltage (UC) across the flying capacitance is changed in the direction of a predefined setpoint voltage (Usoll).
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