DC-DC Converter for Gate Driver Circuitry (Electric Motorcycle)

In summary, a DC-DC converter is needed to supply the low voltage needed for the gate driver circuitry. The output current needs to be supply by VCC, and the decoupling capacitors for the high side switch are also needed to supply current. The 100uF capacitor is used to stablize the VCC supply.
  • #1
jegues
1,097
3
Evening all,

I'm trying to pick out a suitable DC-DC Converter for our low power gate driver circuitry and I'm unsure about a number of different things.

First some background on the circuitry and what the DC-DC Converter is needed for.

To date, we've designed, built and tested a low power gate driver circuit similar (almost identical) to the one shown in the figure below. The end goal is to use such a circuit to drive a Power MOSFET Module for an electric motorcycle.

attachment.php?attachmentid=65023&stc=1&d=1387733624.jpg


Anyways, we built and tested this circuit on a lab bread board that has its own variable 15V and fixed 5V supplies, and everything seems to work fine. However, the final product must have its own low voltage supplied via a DC-DC converter fed by battery bank of the motorcycle which is ~55V.

Thus we need a DC-DC converter capable of supplying us with an isolated 12V(or 15V) and 5V supplies. The 12V(or 15V) supply is used to power the gate driver IC (IR2110) as well as the power buffer circuitry,(i.e. VCC = 12V or 15V) while the 5V supply will act as the logic supply for the chip. (i.e. VDD = 5V)

One simple option would be to find a DC-DC converter that will provide the 55V to 12V(or 15V) needed and simply feed the 12V(or 15V) into a regulator such as the LM7805 and obtain our 5V logic supply from there.

It seems straightforward enough to find a suitable DC-DC converter that will meet our input/output voltage requirements, but I am uncertain as to what our output current requirements are.

According to the application note for our gate driver, the power buffers in the schematic shown above (i.e. the circuitry shown to the right of the IR2110) are needed to provide a higher gate drive current and lower gate drive impedance than what a typical gate driver IC can provide. (Application note is attached below)

They mention that the one shown in the figure above is capable of providing 8A peak output current, which is sufficient for driving Power Modules. (We are using a MOSFET power module, I've attached its data sheet below)

So does this imply that the 12V(or 15V) output from DC-DC Converter (i.e. VCC = 12V or 15V) must be capable of supplying 8A peak output current? The current needed to the drive the gate must be supplied by VCC, right? Or does the power buffer somehow amplify or boost the current?

Thanks for reading!
 

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  • #2
Firstly you should convert the 55volt supply down to the +12V using an isolated switching converter. Then use a linear regulator such as a 7805 to produce the +5Vdc.

Take a look at things like this:
http://www.allelectronics.com/make-a-store/item/DC-1225/12V-25A-DC-DC-CONVERTER/1.html

Use selection systems like these to find suitable converters.

http://www.digikey.com.au/product-s...ard/dc-dc-converters/590047?k=DC-DC converter

http://au.mouser.com/Power/DC-DC-Converters/_/N-5gc7?Keyword=Power+DC+DC+Converters&FS=True
 
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  • #3
jegues said:
So does this imply that the 12V(or 15V) output from DC-DC Converter (i.e. VCC = 12V or 15V) must be capable of supplying 8A peak output current?
No, in proper design circuit this extra current needed for driver should be supply by a "big" capacitor. In your case it is a bootstrap calculator. Vcc current will be equal to the average current.
 
  • #4
Jony130 said:
No, in proper design circuit this extra current needed for driver should be supply by a "big" capacitor. In your case it is a bootstrap calculator. Vcc current will be equal to the average current.

Hi Jony130! :smile:

So are the decoupling capacitors for the high side switch also functioning as the bootstrap capacitor? Or is a separate bootstrap capacitor needed?

Also, what is the purpose of the leftmost 100uF capacitor? It seems to be connected between Vcc and Vss, but I'm not sure what's there for.
 
  • #5
jegues said:
So are the decoupling capacitors for the high side switch also functioning as the bootstrap capacitor? Or is a separate bootstrap capacitor needed?
Its looks like this 10uF act as a bootstrap capacitor for high side also.

jegues said:
Also, what is the purpose of the leftmost 100uF capacitor? It seems to be connected between Vcc and Vss, but I'm not sure what's there for.
This capacitor "provide a current" for IRF210 and for this 10uF caps also.
 
  • #6
Jony130 said:
Its looks like this 10uF act as a bootstrap capacitor for high side also.


This capacitor "provide a current" for IRF210 and for this 10uF caps also.

Isn't the 100uF used to stablize the VCC supply, not necessarily supply current like the decoupling capacitors?
 
  • #7
It's all depend on the point of view. This capacitor don't serve only one role.
Also this circuit looks strange, do you really need all this mosfet do drive a singe IGTB?
 
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Related to DC-DC Converter for Gate Driver Circuitry (Electric Motorcycle)

1. What is a DC-DC converter for gate driver circuitry?

A DC-DC converter for gate driver circuitry is a device that converts a direct current (DC) input voltage to a different output voltage, typically for the purpose of driving a gate driver circuit in an electric motorcycle. This conversion is necessary because the input voltage from the battery may not be suitable for directly driving the gate driver, and therefore needs to be converted to the appropriate voltage.

2. Why is a DC-DC converter necessary for an electric motorcycle?

An electric motorcycle typically operates on a high voltage battery, which is not suitable for driving the gate driver circuit directly. Therefore, a DC-DC converter is necessary to convert the high voltage input to the appropriate voltage for the gate driver, ensuring proper functioning of the electric motorcycle.

3. What are the types of DC-DC converters used for gate driver circuitry?

The most common types of DC-DC converters used for gate driver circuitry in electric motorcycles are buck converters and boost converters. A buck converter steps down the input voltage, while a boost converter steps up the input voltage. Other types of converters, such as flyback converters and SEPIC converters, may also be used depending on the specific requirements of the gate driver circuit.

4. What are the key factors to consider when selecting a DC-DC converter for gate driver circuitry?

Some key factors to consider when selecting a DC-DC converter for gate driver circuitry include the input and output voltage requirements, current rating, efficiency, and size/footprint. It is also important to consider the overall design and compatibility of the converter with the specific gate driver circuit and electric motorcycle system.

5. How does a DC-DC converter affect the performance of an electric motorcycle?

The performance of an electric motorcycle can be affected by the efficiency and reliability of the DC-DC converter used for gate driver circuitry. A high-quality converter can improve the overall efficiency of the electric motorcycle, which can lead to longer battery life and better performance. However, a faulty or incompatible converter can result in performance issues such as voltage drops, which can impact the functioning of the gate driver and overall performance of the electric motorcycle.

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