Active-Clamped Isolated SEPIC Converter for Wide-Input MHz Operation
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Solution Overview
Problem
Existing DC power converters face challenges in efficiently converting a wide range of input voltages to stable output voltages for low-power electronic loads, particularly in applications like vehicles, where backup batteries require efficient voltage conversion without significant size or efficiency losses.
Innovation Solution
The active-clamped isolated SEPIC DC-DC power converter operates in resonant discontinuous conduction mode, utilizing a transformer with leakage and magnetizing inductance, a resonance capacitor, and a loop controller to achieve zero voltage switching and efficient voltage conversion across a wide input voltage range, including a backup battery voltage of 9-18 volts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional DC power converters are used to convert wide input voltage range to stable output voltage, then voltage conversion function is achieved, but efficiency is reduced and size increases
Solution Approach 1:
The patent applies resonant operation by configuring the circuit to operate at a resonant frequency determined by the leakage inductance and resonance capacitor. This resonant oscillation enables soft switching conditions, reducing switching losses and improving efficiency while allowing operation at higher frequencies for compact size.
Solution Approach 2:
The patent changes the operating mode from conventional continuous conduction mode to resonant discontinuous conduction mode. This parameter change enables the circuit to achieve both high efficiency and wide input voltage range capability by utilizing the resonant characteristics of the leakage inductance and capacitance.
2Adaptability or versatility
If conventional DC power converters are used for wide input voltage range, then voltage conversion is achieved, but transformer size increases
Solution Approach 1:
The patent converts the harmful effect of transformer leakage inductance, which is normally considered a loss mechanism, into a useful resonant element. By configuring the resonance capacitor to work with the leakage inductance, the circuit achieves resonant operation that enables wide input voltage range while keeping the transformer compact.
3Power
If conventional switching operation is used, then voltage conversion is achieved, but reverse recovery losses occur
Solution Approach 1:
The patent prepares the switching conditions in advance by using the resonant oscillation to naturally zero out the current through the switching element before it turns off. This preliminary action prevents reverse recovery losses by ensuring the current is already zero when the switch transitions, eliminating the need for hard switching recovery.
4Volume of stationary object
If higher switching frequency is used to reduce size, then transformer size decreases, but switching losses increase
Solution Approach 1:
The patent uses resonant oscillation at the switching frequency to create soft switching conditions. The resonant frequency is configured to match the operating frequency, enabling the circuit to operate at high frequencies for compact size while the resonant current waveform ensures zero-voltage or zero-current switching, minimizing switching losses.
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 solution provides improved power density and efficiency, reducing reverse recovery losses and transformer size, while maintaining stable output voltage across a wide input range, enhancing the performance of DC power converters in automotive and similar applications.
Implementation Method 1
a transformer configured to isolate an output terminal of the circuit from an input terminal of the circuit, wherein the transformer includes a leakage inductance and a magnetizing inductance
Implementation Method 2
a resonance capacitor in series with the leakage inductance, wherein a value of capacitance for the resonance capacitor, a value for the magnetizing inductance and a value for the leakage inductance configure the circuit to operate in resonant discontinuous conduction mode (DCM)
Data Source
AI summary
An active-clamped isolated SEPIC DC-DC power converter (ACISC) to convert a DC voltage to supply a variety of DC loads. The single-ended primary-inductor converter (SEPIC) of the ACISC may be configured to perform both buck and boost converter functions. The ACISC of this disclosure may be configured to operate over a wide input voltage range to provide an output voltage for DC electronic loads supplied by the power converter. In the example of an automobile, a back-up twelve volt battery may output voltages to the ACISC over a wide voltage range, e.g., nine volts to eighteen volts. The wide input voltage range of the ACISC may be desirable when used as the converter for a back-up battery supply. The circuitry arrangement and component selection of the ACISC of this disclosure cause the power converter to operate in resonant DCM mode in the megahertz (MHz) frequency range.