yeah well, 18000uF is quite a lot. You want to put the 1000uF only to avoid blowing the MOSFET up, if the problem you are having is related to voltage spikes.I checked a way to calculate the required capacitance for the power supply depending on the voltage and the current , C = (5*I)/(V*f) , for me , I =30A , V = 160V , f=50HZ , this will give 18750 uF , the max capacitor I can get is 1000uF , I can put more than one on parallel , but It's cost will be way out of my budget , Is it necessary to put this capacitance value , can the mosfet work with a signal with high ripple values.
and can it work with a variable DC voltage (output of the full wave bridge rectifier ) , or an AC signal?
the k1519 ran out in the store , so I'm using IRFP460 temporarly
http://www.datasheetcatalog.org/datasheet/irf/irfp460.pdf
Your biggest problem is that you don't have anything to measure. Sure you can totally overrate the MOSFET/IGBT and then it will work.Can I replace the mosfet by an IGBT with the same conditions , I know IGBTs are available in much higher current and voltage ratings , I have burned many mosfets till now and I can't afford to burn others .
and I was able to use the mosfet without a mosfet driver IC because I tried to use it before and I couldn't understand how it works , so , can the IGBT work without a driver, If this is impossible , can you tell me the basic operation principles of the driver IC and what is the use of the capacitors connected to it , because the application notes were not helpful for me.
also , can it work with the low frequency I have (1KHZ) or not .
looks slightly overrated, but ok, it worked...-used a 600V , 55A IGBT.
Don't worry about it, just use the bigger caps.both the mosfet and the diode are dead .
- when I was testing without the 3000 uF caps , when I measure the voltage output from the rectifier using the multimeter while it is in the dc mode , it measured 120V , I used it in the ac mode , it gave 45V ac , when I installed the 3000 uF caps , the dc reading became 160V while the ac reading became around 9 volts ac , I can't explain how did the dc voltage increase .
Everytime you turn the PWM pulse off you'll have a current through this diode, that's why it's heating up.- another thing is that when the circuit was working , the diode was heating up , what I know is that this diode has no effect when the motor is running , It only works when the motor stops suddenly , even this never happened , I change the motor speed very smoothly , why would the diode be heating when the motor is running at a constant speed
These caps are expensive in my place , If I don't add caps , would it be wrong , and what is the scientific reason behind that.Don't worry about it, just use the bigger caps.
Is there a protection that I can add?It looks like first burns the diode and then the MOSFET/IGBT since there is no more protection for it.
yes , but the small one I showed before , I wasn't aware that the diode will be working while the motor is running .1. Is the diode mounted on a heatsink? What was it's temperature?
I can't tell because I installed a huge heat sink and fan on top of it , and I couldn't find a thermometer to use , but the heat sink was very cold.2. Is the IGBT getting hot?
1KHZ3. What was the switching frequency?
15V , I tried to make it work with a 5v supply but it didn't work , In the datasheet it says that there is an undervoltage detect and that the pwm must be higher than 9v , and the pwm must be between (Vss - 0.3 ) and (Vdd + 0.3) so I made the supply voltage 15V , and it worked .4. What's the power supply voltage of the 2110 and therefore the voltage of the gate pulse?
Because there is an undervoltage detect in the IR2110 , pwm signal must be higher than 9V , so I use the amplifier to amplify the 5v pwm signal from the microcontroller , If I don't do that the IR doesn't work.Could the LM324 be causing problems? Why is it in the circuit if you have the MOSFET driver IC to drive the IGBT gate?
Just to have a (almost) constant DC-voltage. If the motor is not loaded and there is no problem in having varying torque according to the mains frequency, no problem.These caps are expensive in my place , If I don't add caps , would it be wrong , and what is the scientific reason behind that.
The diode is the protection. You could add a snubber , but without oscilloscope it doesn't make sense to try this. You have no information on what is going on in your circuit.Is there a protection that I can add?
That's ok.15V , I tried to make it work with a 5v supply but it didn't work , In the datasheet it says that there is an undervoltage detect and that the pwm must be higher than 9v , and the pwm must be between (Vss - 0.3 ) and (Vdd + 0.3) so I made the supply voltage 15V , and it worked .
heatsink, yes, if it got hot... the diode could also die because the motor exceeded the maximum surge current rating of the diode...what should I do , should I use another heatsink and fan for the diode as well .