Article : [DIV478]

Titre : D.J. HAMO, AN9506 - A 50W, 500 kHz, Full-Bridge, Phase-Shift, ZVS Isolated DC to DC Converter Using the HIP4081A, Intersil application note n° AN9506, Avril 1995, 16 pages.

Cité dans : [DIV126]  T. LEQUEU, Librairie des fichiers PDF de composants, octobre 2022.
Cité dans :[THESE137]
Cité dans :[LIVRE384]

Source : Intersil application note
Date : Avril 1995
Pages : 1 - 16
Lien : AN9506.pdf - 16 pages, 433 Ko, David J. Hamo, A 50W, 500kHz, Full-Bridge, Phase-Shift, ZVS Isolated DC to DC Converter Using the HIP4081A, AN9506, April 1995, Intersil Intelligent Power.
Lien : UC3823.pdf - 13 pages, 2949 Ko, High Speed PWM Controller.
Lien : HIP4081.pdf - 15 pages, 195 Ko, HIP4081A, 80V/2.5A Peak, High Frequency Full Bridge FET Driver, November 1996

Introduction :
Many articles and papers have been published recently promoting the performance and benefits of the Phase-Shift, Full-Bridge Topology and rightly so.
This topology productively utilizes the same elements that have been plaguing power supply designers for decades, those infamous parasitic components.
The topology enables designers to advantageously employ transformer leakage inductance, MOSFET output capacitance and the MOSFET body diode, enabling designers to easily move their designs upwards in frequency.
The topology offers additional advantages like zero-voltage-switching at a constant switching frequency, which substantially reduces switching losses.
This can be significant enough to eliminate heatsinking of power MOSFETS and/or enabling the use of less expensive power devices.
Reduced EMI and RFI are additional benefits, since the voltage and current switching waveforms are much "cleaner" and waveform edges switch softly compared to conventional pulse width modulation (PWM) techniques.
The ability to move upwards in frequency will ultimately reduce the overall size and lower the cost of the supply. One megahertz operation and beyond is possible with this topology. This is truly a major advancement in topological architecture.
The requirements for this design are a full bridge configuration, an additional
inductor to aid resonant operation and output structure consisting of a dual diode rectifier and an LC filter.
Special thermal substrates may not be required. As a result, cost savings can be realized by utilizing inexpensive FR4 printed circuit board material in place of elaborate thermal designs.
What's more, EMI/RFI filtering requirements and heatsinking are less rigorous further reducing costs. Therefore, focusing on the overall system cost, it can be demonstrated that employing this topology does have merit.
Presently, there are limited phase-shift controllers on the market, and those that are available are still expensive. Having faced this problem, an investigation of designing a discrete solution was performed. What was discovered proved to be encouraging.
With any low cost single ended controller and two low cost logic ICs, one can generate all the gating and delay functions necessary to derive the phase-shift control waveforms.
What makes this all possible is the Intersil HIP4081A MOSFET driver. The HIP4081A is capable of independently driving four MOSFETs directly, eliminating the need for traditional drive transformers. The HIP4081A also allows additional drive and control capabilities unavailable with conventional gate drive transformers.
This includes the ability to vary the turn-on delays of both upper and lower MOSFET switches. This is an essential feature for realizing zero voltage switching (ZVS).
The net result is flexibility and capacity to derive the control logic drive signals necessary for phase-shift ZVS switching. The voltage rating of the
HIP4081A is 80V, which is ideal for telecom DC to DC converters.
With the added overvoltage protection circuit which turns on the lower MOSFETS and turns off the upper MOSFETS, further protection is supplied to the system.
The block diagram of the full-bridge phase-shift power supply described in this application note is shown in Figure 1. The circuit discussed here has an output power capability of 50W, but operation can be scaled upwards to the 500W range with the appropriate power component changes.

This topology was exciting and surprisingly simple to implement.
It has been shown that the HIP4081A can be used successfully to realize the phase shift ZVS full-bridge topol-ogy. Not only does the HIP4081A drive the H-bridge but it also is capable of delivering the needed ZVS transition delay times required by this topology.
In addition, a simple logic block was used to convert a single ended PWM output into the required phase shift logic drive signals.
A design process was developed to enable designers to accomplish their own designs. This was achieved by deriving essential equations and exposing key concepts.
Following these procedures should allow designers to obtain success when incorporating this topology. What's more, much of the mystery of this topology has been removed, especially in the area of parasitic functionality within the design.
It was shown that the output capacitance variation does not have a great impact on overall performance. It was shown that the effects of this variation can be determined easily with graphical methods.

Bibliographie

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