I want to control the N-MOSFET with the transistor TIP121 which is controlled with PWM from arduino. Did I connect it well? Will it work?
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Either use normal schematic symbols, or clearly label each pin on the transistor with their names. Gate, drain, source, base, emitter, collector. No one can tell what's going on with that mess.
Regardless of the pin designations, I cannot see this being viable. I guess pin designations would determine either smoke or nothing.
What are you trying to accomplish?
Try it and see then figure out why you get (or don't get) a result. Most of us old farts learned what we know by reading and experimentation, not by asking for answers. Yes, you will get the occasional release of smoke but at the levels of voltages we're talking about there is very little personal risk (irrespective of what today's risk-averse community wish to tell you) Seriously, you learn more by doing something than by being told about it.
You are going to want to switch the transistor on and have it control the gate voltage of the MOSFET.
Sorry that was a little circular. Transistors and MOSFETS come natural to me, so I assumed you would know what I meant. I do not think your schematic is wired correctly. My best advice would be to make the Arduino output go into the base of the transistor and connect the emitter to the gate of MOSFET.
Patryk20:
I want to control the N-MOSFET with the transistor TIP121 which is controlled with PWM from arduino. Did I connect it well? Will it work?
Cannot follow that schematic - its vital to use the correct symbols for devices otherwise there will
just be confusion.
Normally if you are switch a 12V load you just require a single logic-level n-MOSFET (for low-side
switching of the load), or an NPN transistor (like an 2N2222, not a big darlington) driving a
p-MOSFET for high-side switching.
But first questions: What is your load? What maximum current does it take, is it inductive?
What frequency PWM do you want to use (if high you may need a MOSFET driver chip).
So I made the tests and it comes out that my circuit works fine, but I came across a problem.
Voltage in the circuit is max 100V (usually 60) current up to 35A I need a capacitor on the power supply so that the power absorbed by this circuit is constant without big oscillations.
I need to use a capacitor, I need a very large capacitor if it can work with arduino frequency (60kHz). So my plan is that the modulated PWM signal from the arduino with the help of a capacitor will convert to an analog signal of 0-5V this signal is controlling mosfet controller. I find it hard to find such ic, the only one I found is the LTC6992CS6-1 which has a signal voltage of 0-1V can reduce the voltage with arduino resistor to have such values. It looks like everything would be fine but the switching frequency of this ic is 1MHz can anyone help me to find something with higher frequency and maybe for 0-5V signal voltage?
My goal is to have as much switching frequency as possible to make my capacitor as small as possible, I know that there are some limitations due to the mosfet controller and the mosfet itself so I'm asking for the optimum solution with acceptable efficiency and cost.
WHOA!! Where did 100 volts come from? We need waaay more info than what you have provided, what kind of load are you trying to switch (volts and amps) at what frequency, is it some kind of coil?
Patryk20, I think that it is way above your capabilities to produce a circuit that will switch 35A at 100V and >1MHz.
You haven't even demonstrated to us that you can draw a schematic correctly.
Hi,
Are you still "playing" with PV and charging your batteries?
https://forum.arduino.cc/index.php?topic=485399.msg3312294#msg3312294
Tom... 
I can draw diagrams. Yes, I am still working on the project, slowly but forward.
I have ready mpp tracker code for 230V heater. I still have a 60V DC heater which has 3 pins 260,540,1200W. The problem was the value of the capacitor at the output of the photovoltaic panels. As for the code for the 60V heater is not yet ready but I already know how can I do this, it is a harder task because there are 3 pins. So if I use 1 Mhz frequency the MKT 50 uF 250V capacitor should be suitable. But if something goes wrong I can switch to a 60V heater and use capacitors of higher capacity.
I think I have to use MKT capacitors because 1 Mhz for electrolytic capacitors is too much. As for the 230V version, the maximum current is 9A and 250V. I have only one serious concern, let's say we have 6 panels connected in series, give a current of 9A and the voltage at the maximum power point will be from 150V to 218V which gives 1350W power to 1960W.
The 2000W heater at 230V consumes 8.7A
218V is 8.25A
150V is 5.8A
See what I mean? There is a situation when the panels can give a higher current but the heater can not pick it up, so I would have to use a heater with more power than I can produce. But what happens when the heater will want to get more current than the source can provide, how will it affect the pwm, I do not know, I will find out in practice.
Rather than build a highly illegal 1MHz radio transmitter (and fail in the process), please take my advice:
Switching a large heater element should be done at sub-Hz rates. Any attempt to use high frequencies will
end up being hugely difficult, will emit tons of EMI, and have no benefit.
Driving a high power MOSFET gate is done best with a MOSFET gate driver chip. Its what they are for.
Darlingtons are not remotely sensible for this, way too slow leading to massive switching losses.
High power switching circuits are fraught with difficulty - you need lcircuitry devoted to protection
from the various failure modes because at these power levels any failure mode will explode your MOSFETs
immediately. Yes, explode them... You should wear eye protection always for these power levels for two
reasons: exploding semiconductor packages, high energy sparks. 100V and 35A will defeat you unless
you proceed cautiously, say starting with 30V 5A, and gradually upping the power levels. Expect to
get it wrong. IGBTs may be a more reasonable approach than MOSFETs as they are more robust at
higher voltages.
This is clearly a project where DC-rated SSRs might be much much simpler to employ.
So the optimum solution would be to use a 60V heater, use a frequency that I can easily get from arduino for example 30kHz and use larger capacitors for 100V.
I could switch between the heater pins 260,540,1200W to always get the right parameters. I think I will go to this site, despite the fact that this heater is 5 times more expensive than 230V of the same power.
Is this still for your project of finding MPP of a PV panel or solar array.
And you think you can solve this by simply PWM-ing a heating element?
Leo..
So this is the same project, in this topic from the electronic side. As for the program, at the beginning of my adventure I had no idea about arduino and now I have a program ready, maybe I will encounter some difficulty when making a program for 3 heaters, then surely ask for help on the forum
Regarding the simplicity of the PWM solution, if you consider that I will use 3 heaters and i can give any distorted voltage to the heater and it will not make a difference, then PWM is enough. If I would like to hook up to anything else and would like to maintain high efficiency I would have to do dc-dc converter with adjustable input voltage.
I quickly draw a circuit diagram that I use now for testing. The problem is that I can not measure the voltage by voltage divider. I have 3 different masses, the first one is mass arduino, the other is "0V" from the power supply and the mass of the photovoltaic panel. Between the arduino mass and the ground from the voltage divider is 3-12V depending on the PWM setting. The shortage of these masses results in a 100% dutycycle on the mosfet. Could someone please suggest me how to change the layout so that I can measure the voltage by voltage divider?
Hi,
Connect all the masses together... otherwise you will not be able to control the N-Ch MOSFET with the Arduino.
I presume you are using a transistor in the control circuit because your MOSFET is not a logic level device.
Why PNP transistor?
Something like this, sorry its not tried and its almost midnight here and I'm off to bed.
Tom..
PS When you draw your circuits. put ALL masses gnd along the bottom of the sheet and positive supplies towards the top of the sheet.
I went with mosfet driver and it works very well. I am very happy with my work. I have one question. Because I am using acs712-30A ammeter and it has quite big errors of even 0.15A. I know that the more accurate layout is the 20A version which would be better but I'm looking for greater accuracy. After all, a $ 10 multimeter measures exactly the current up to 20A and I can not find such an IC. I do not need to measure negative currents so something in the 0-5V range would be better because of higher accuracy. Does anyone know of a layout similar to acs712 but with more accuracy?