Understanding Half Bridge Driver

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In summary, the conversation discusses the function of an IC and its typical application circuit, which involves converting AC to DC, then back to AC at a higher frequency, and finally back to DC at a lower ripple current. The purpose of the feedback loop is to vary the frequency of the driver in order to maintain a steady output voltage. This topology is used for its benefits of reduced ripple currents, easier voltage regulation, and high efficiency, particularly for lower power applications.
  • #1
smk037
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I'm trying to understand what this IC is doing and what the "typical application" circuit is doing

http://www.onsemi.com/pub_link/Collateral/NCP1392-D.PDF

It looks to me like this is the basic idea. AC comes in, PFC is done, signal is rectified so that a DC signal is coming into the IC. Then, the IC converts back into AC, but this time at a higher frequency, driven through an isolation transformer and then rectified AGAIN, but this time at a lower ripple current due to the higher frequency.

Do I have this correct? If that is the case, what is the purpose of the feedback loop, since it looks like it varies the frequency of the driver, not the output voltage?


Thanks,
 
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  • #2
In my book this is really a controller, more then a driver, but it includes the "driver" stage.

Your description is about right - it is set up for a Half Bridge DC/DC converter ( ref http://www.ti.com/lit/sg/sluw001e/sluw001e.pdf )

The front end rectifier / PFC is part of a typical application - but not a requirement - highlighting that the chip has a PFC delay - allowing front end - DC to get to voltage and stabilize.

The frequency varies to maintain a given Vdc on the output - this seems odd at first, but the idea is that each pulse through the transformer - carries a fixed amount of energy (think voltage and current)- to hold the voltage steady as the current varies you adjust the number of pulses over time = Frequency. When you got to resonant mode, it gets a little trickier in the logic, but the current is nearly a sine, as the F increased you are "over Resonant" putting more energy in the tank circuit - but this is to support the output that is taking more energy out - to keep the tank balanced ( E in = E out)
 
  • #3
Thank you! That makes sense and that TI webpage is a very good reference.

One more question, what is the reasoning for doing this? The only benefits I see are:
1. Reduced Ripple Currents
2. Easier to regulate voltage by varying the frequency of the oscillator

Are these the only reasons? It seems to me if you are not required to keep a low ripple requirement and do not require careful regulation of voltage/current, it would be easier to just go

120VAC->Step up/step down Transformer->rectifier
 
  • #4
Yes, this topo is for higher quality dc, good regulation, efficency, large voltage changes, etc, and gendrally for lower power. For a basic dc supply there a lot of ways to go.
 
  • #5

What is a half bridge driver?

A half bridge driver is an electronic circuit that is used to control the switching of power to a half bridge configuration. It is commonly used in power electronics applications to drive high voltage and current loads, such as motors and DC-DC converters.

What is the purpose of a half bridge driver?

The purpose of a half bridge driver is to provide the necessary signals to control the switching of power in a half bridge configuration. This allows for efficient and precise control of high voltage and current loads, which is essential in many industrial and automotive applications.

How does a half bridge driver work?

A half bridge driver typically consists of a high and low side driver, which are controlled by a microcontroller or other control circuit. The high and low side drivers work together to switch the power supply on and off, creating a high frequency pulse that is delivered to the load through the half bridge configuration.

What are the advantages of using a half bridge driver?

Using a half bridge driver allows for efficient and precise control of high voltage and current loads. It also reduces the overall size and cost of the circuit compared to using a full bridge configuration. Additionally, it allows for bi-directional current flow, making it suitable for applications that require both forward and reverse motor operation.

What are the potential drawbacks of using a half bridge driver?

One potential drawback of using a half bridge driver is the need for careful circuit design and proper heat dissipation to avoid overheating and damaging components. Additionally, it may require additional components, such as gate drivers and protection circuits, which can increase the complexity and cost of the overall system.

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