Which is preferable as High Side Mosfet/Igbt driver?

[tAhm1D]

Hi all,
Modern Power Electronics is based on efficient use of Mosfet,Igbt,power Transformer,Thyristors etc. Due to inherent drawback, use of power transistor and Thyristor has diminished and mostly now a days Mosfet and Igbt are used. But driving Mosfet and Igbt in all circuits/topologies is not an easy task, especially when High Side and Low Side drive is required. For that reason, different types of driving techniques are used-mentioned below.

a. High/High-Low side driver ic- like IR2110/2113 and numerous other Ics. Those are good but application technique is complex and costly and modern micro controllers can not drive those directly in most cases and optocoupler based ones like TLP 250 cannot be used greater than 25khz.

b. Discreet Driver is cheaper, but for higher frequency its use is difficult and not very reliable in all cases.

c. Many use Gate Driving Pulse Transformer. But its construction is very difficult as it requires core with stringent quality, which may not be available all 
   the time  and hence efficiency is not satisfactory, which generally causes damage of the Mosfet/Igbt itself.

So, what should be the best use or best alternative? Hope to get good suggestions from you all.

[king]

Hi!
  I think the use of gate driver IC's is not bad idea and MGD's like IR2110 or IR2104 or IR2109 are not complicated to operate you just have to provide them PWM signal (e.g 20KHz) using micro controller or by another mean, and as far as optocoupler concerned than they are easily available in the market or also you can by-pass them for first time practice and if you need any circuit in which MGD IC's are used then i will provide you the schematic for your guidance.

[tAhm1D]

Hi,
It is easier to drive high side MOSFET with discreet driver when frequency is low but the discreet driver circuit for high side MOSFET driver for high voltage (300V and up), high frequency (greater than 50kHz) is difficult to formulate. Does anyone have any idea regarding that sort of high frequency discreet driver circuit?

[jzaghal]

Hi,

I suggest you use a pulse transformer. Google "Tesla Coils" for D.I.Y pulse transformer.

Tried it ,good efficient and cheap.

Cheers.

[tAhm1D]

Hi,
Yes lot of things regarding pulse transformer can be obtained from google and it is often said that it is good and efficient- then what? Construction of it and getting proper signal from it is not easy. Have you tried it by constructing yourself- not using ready made one? I tried lot basing on the application notes of different companies but those did not work. Can you please spell out regarding the core,winding etc. in detail? Ready made ones are not available here. This is regarding high voltage and high frequency application.

[localcrack]

Use TC4469 for mosfet drive

[tAhm1D]

Hi localcrack,
TC4469 is an h-bridge driver for p-channel/n-channel mosfet driver, ie. p-channel as high side and n-channel as low side. But for N-Channel mosfet as high side, this driver can not be used. Since, in high voltage p-channel power mosfet is not available, normally N-channel mosfets are used in full bridge/half-bridge. And hence, this driver can not be used for high power application where all N-channel mosfets are used. Moreover, this can not be used for driving p-channel mosfets higher than 20v as it does not include level shifting for the p-channel high side fet, thus this needs to be externally provided.
So, this driver can actually be used as low-side driver.
Normally I use IR2110/IR2113. But the good ones made by IR are costly(much more expensive than discrete drivers). Chinese ones are cheaper but you can not rely on them as they will create 100s of problems in the circuit.
Discrete drivers are better, but I am in search of high-frequency high-voltage discrete drivers for high-side MOSFET drive.

[sohel]

here one design which fully isolated with pt.but didnt tryed yet.

[qolpa]

i used TLP250 before, it was ok but my freq was 20kHz. once in a time i heard about ISL6615 but i never tried it. have a look at it.

[sohel]

i used TLP250 before, it was ok but my freq was 20kHz. once in a time i heard about ISL6615 but i never tried it. have a look at it.

can u share ur hardware design

thanks

[tAhm1D]

i used TLP250 before, it was ok but my freq was 20kHz. once in a time i heard about ISL6615 but i never tried it. have a look at it.

Your circuit probably was of low voltage(<35v) because TLP250 can not be used as high side MOSFET driver in a circuit which consists greater than 35v.
You cannot use ISL6615 for h-bridge operating at greater than 13.2v(as stated in the datasheet).
So TLP250 and ISL6615 are inappropriate for high voltage high frequency high-side driving.

[Ichan]

Fairchild semiconductor high voltage gate driver ic are much cheaper than International Rectifier driver, look at FAN7xxx family.

-ichan

[qolpa]

Your circuit probably was of low voltage(<35v) because TLP250 can not be used as high side MOSFET driver in a circuit which consists greater than 35v.
You cannot use ISL6615 for h-bridge operating at greater than 13.2v(as stated in the datasheet).
So TLP250 and ISL6615 are inappropriate for high voltage high frequency high-side driving.

yes, mine was a low voltage application.

[tAhm1D]

Fairchild semiconductor high voltage gate driver ic are much cheaper than International Rectifier driver, look at FAN7xxx family.

-ichan

FAN Series are not available here. IR2110/2113 are good for both high and low side drive but Microcontroller can not drive it directly and for that additional arrangement has to made. It would be better if any optocoupler based high side driver for high voltage and high frequency should be there, so that it can be driven directly  by microcontroller. I could not find any. Is there any?

[samud]

there are several ways to drive high side mosfet or igbts. u can use pulse transformer to drive highside mosfet. or u can use ir2118 or ir2110. u have to use optocoupler to drive ir2110 or ir 2118. using optocoupler u can get isolation and logic level for drive them from microcontroller. i use last technic to drive 200 volts 1.5 kw pmdc motor  from microcontroller.

[tAhm1D]

Hi,
Which optocoupler have you used? Most of the optocouplers can not be used in high frequency as they have high rise and fall times. I am talking about high frequency (greater than 50khz). Probably your circuit is of low frequency. For low frequency,any optocoupler can be used for driving any load in combination with microcontroller and driver ic as you have mentioned.

[sohel]

R u talking like that?

[HackerNo.1]

Hi sohel,
Good picture. But what does it indicate? I also think most of the optocouplers are slow other than one or two. Is this circuit operates in HIgh Frequency? Can it be operated in the range of 50khz range? If so, what is the frequency and which optocouplers are used? Please tell us so that we can learn from you. Here optocoupler is used for interface only.

Hi Tahmid,
I think discreet driver and optocoupler based driver are not available for high frequency drive. It is better to use Mosfet gate driver Ic like IR2113 or L6386 can be used for high frequency and high side drive. Interfacing with microcontroller can be done like the picture given by Sohel if the rise and fall time of those optocouplers cope up with the microcontroller in high frequency. Let us hear from Sohel what the picture says.

[sohel]

why u want to switching  at  > 50khz pwm? 
look at
http://www.edaboard.com/ftopic354456.html

[HackerNo.1]

Hi Sohel,
I wanted to know from you since the schematic is posted by you. However,if you are not clear regarding your writings and just copied the schematic from somewhere, it is not wise because we undergo the posts here to learn something, not just copy something blindly. I don't want anything. It is just a discussion regarding high voltage and highfrequency switching. However, while I make some smps, I use 140khz freq , which becomes 70khz in each phase in push pull topology normally. However, the example one in http://www.edaboard.com/ftopic354456.html is a failure example,where igbts are burned and circuit was an utter failure. Should we follow the failure case?

[sohel]

R u talking like that?

I AM NOT BLIND, I HAVE TOLD "LIKE THAT" SO HA HAH

[tAhm1D]

Hi HackerNo.1,
In your High frequency application probably you use high low side driver. I am in search of a discreet driver circuit for using in high frequency and high voltage application. It will be used in single phase.Can you put some light on that?

[Ichan]

If you are looking for high speed optocoupler then maybe 6N137 will fit the requirement.

It is more common to use gate driver IC for high voltage section and optocoupler on logic level isolation.

-ichan

[tAhm1D]

Hi Ichan,
Useful information. Your cooperation is appreciatable. I will study in detail.

[myheadhurts]

theres a floating discrete high side driver here..
http://www.innovatia.com/Design_Center/High-Side%20Drivers.htm

Ive built it and it works...although you'll have to tweak it for your requirements ..
I mainly use the st L6386 and the other variations and have had no headaches when using them.

Rob

[sohel]

optocupler is best device for high side isolated  switching. ir2110 is very complicated. if u use  optocupler why u need ir2110 ? 

[jzaghal]

Hi,

Previous discrete design should work, but you need a separate supply to power the Hi-Side.

Quote: " While transformers and couplers offer isolation, an isolated (floating)VGH supply may also be required, to swing along with the gate voltage."

Still I prefer pulse transformer.

Cheers.

[tAhm1D]

Hi jzaghal,
If you use separate supply to power Hi-side, then why you require any other circuit? You can drive the low side with any means like optocouplier etc.
Yes Pulse Transformer is better if you get those readily available and can purchase and use. Making those is real troublesome.
Regards.

[jzaghal]

Hi,

The problem is with driving the Hi-Side, which needs to be at a higher potential than the actual supply by

something like 15 to 20V dc in order to drive the Hi-Side Switch.

You don't have this problem with the Low-Side switch since the driving voltage is present using the normal

voltage supply. So you need one more supply for the Hi-Side. Hope it is clear.

You need one supply when you use a pulse transformer, since you get an isolated drive for both sides.

Cheers.

[tAhm1D]

Hi jzaghal,
Requirements and theory for Hi side and Low side mosfet drive is known to me as I have made lot of s.m.p.s. products. I normally use Mosfet/Igbt drivers like IR2110/2113. I tried to use Pulse Transformer but the one constructed by me was not appropriate and here pulse transformers are not available so that I can purchase. I am searching a discreet driver like I use in low voltage and low frequency application but could not make or find one for high voltage and high frequency. But this time I hope to make one with the help of optocouplers as I get the informations from Ichan.
Hope, I could make you understand what I wanted to mean.  

[tAhm1D]

Hi myheadhurts,
This circuit is not completely alright, as you have to provide the VGH for the MOSFET with external bootstrap circuitry. This, I had done earlier, but it is not going to work for high voltage, high frequency (say, 300V, 50kHz), as I would need to provide 310v minimum at VGH, and in turn damage the transistors (unless 400v ones are used). Also the high value resistors would cause a problem for high frequency signals.
Anyway, I appreciate your cooperation.

[Walkura]

Personaly i used several options .
I designed a ac-ac chopper using the HCPL3120.
http://www.bmh.nu/pdf/Opto/HCPL3120.pdf
Depending on the gatecapacity i think the IR2101 is also a quite nice option .
Also from time to time i abuse PC817 optocouplers to isolate my highside driver from the MCU .
The point is a little that with the HP and the PC817 you need to make your own bias supply .
Usualy one of my selection criteria is , what if it goes wrong ?
Otherwise i prototype while using optoisolated gatedrive ,when its *mature* i change to a cheap IR .
This way i can limit the (potential) damage while being in experimental phase .
It depends a little on what you can get in your country .

[tAhm1D]

HI Walkura,
So, you use different drivers as the circuit/situation requires. Yes, that should be the ideal method. Instead of using OPtocoupler and then making high side floating supply seperately, I think it is better to use Highspeed Optocoupler to supply the Microcontroller signal to Mosfet drivers like IR2110 etc. and that can be the suitable system for high frequency and high voltage full bridge circuit. I am using this process. However, I will try to use optocoupler and  separate floating supply with boost capacitor for high frequency and high voltage circuit.

[myheadhurts]

hi

one of the reasons I tried a discrete solution rather than a Mosfet/Igbt driver like IR2110/2113 ,was to solve a problem of voltage spikes (caused by tail-end currents in the h bridge )at the higher than normal frequencies I needed.
I found that under certain conditions shoot-through by erroneous firing could occur and removing the Mosfet/Igbt driver and its bootstrap circuits was a cure...providing power to the high sides from a boost circuit mc34063 and multitap transformer to provide all 12 highside supplies.
I later solved the spike issue by using the pwm drive signal to control the tail-end current towards the end of the commutation cycle..removing the charge pump effect altogether..

Rob

[tAhm1D]

Hi myheadhurts,
Your concept is correct. The way you have described is workable I think. I will work with your idea.

[tAhm1D]

optocupler is best device for high side isolated  switching. ir2110 is very complicated. if u use  optocupler why u need ir2110 ? 

Hi,
Are you convinced that IR2110 is not necessary and only Microcontroller and Optocouplers are enough to drive all 4 Mosfets in a full bridge circuit operating in around 300V? If it is, then how?

[jzaghal]

Hi,

What Sohel is suggesting is possible.

You can use a fast opto_isolator such as 6N136 and, use a separate 12V PSU.

Cheers.

[tAhm1D]

Hi jzaghal,
Using separate power supply for high side virtual ground is the first lesson in full bridge topology in power electronics.If I use separate power supply for high side mosfets, then there is no need for such a long discussions in this thread. Instead of supplying separate power supply to the highside mosfets, creating artificial virtual ground with discreet process is the aim. However, Your system is workable but I prefer IR2113 instead of separate power supply. Your idea is welcome.

[Jehan]

If your duty cycle is less than 50% you can use an isolation transformer type drive , many small drivers transformers are available from Coilcraft, pulse and many manufacturers, you can also manufacture your own transformer using toroids.
Also there are dedicated fully contained drivers from Infinieon if you are going to use high
power IGBTs

[sohel]

using two 6n137 opto for high side and normal low side. can u clear me which product u want make. r u talking 50khz pwm or something else.

[tAhm1D]

Hi,
Do you think that 6n137 opto in highside is enogh for a circuit where voltage is almost 320v? I am considering about an smps circuit to convert 320v DC to 230v sinusoidal AC with > 50khz Freq.

[sohel]

convert 380v DC to 230v/50hz sinusoidal AC with > 50khz pwm Freq ? look at picture for one high side with 6n137.

[tAhm1D]

Hi,
What you are trying to say is not clearly comprehensible from the pcb, so could you please provide the schematic?

[tAhm1D]

Hi sohel,
I have tested your circuit. It works fine at low frequency, below approximately 8khz, but higher frequencies cause distortion of waveform (slow rise time) due to pull up resistor. You cannot discard pullup resistor since 6n137 is an open collector device. Reducing the resistor will destroy the 6n137. so, your circuit can not be used for high frequency applications.

[sohel]

can u show picture from output.

[tAhm1D]

Hi sohel,
I don't have camera in my possession now and hence can not show the output waveform. However, have you not tested the circuit by yourself? What is your observation regarding the circuit?

[lito108]

Hi Ichan
good info !

[qolpa]

can u share ur hardware design

thanks

sohel, sorry for a so late answer, but i missed your reply and i do not have the whole schema, i tried to put some little parts together and hope this helps. this was a 48V to 27,5V battery charger with ~20A output and 20kHz switching freq. it was a school project and had a  basic circuit.