How to convert a Modified /Square wave inverter to Pure Sine

hey guys in this video I am going to show you how to convert your modified or secure wave inverter to pure sine wave inverter here I have this cheap Chinese 500 watt inverter as you can see the output waveform is modified secure wave not pure sine-wave let's open it first of all you have to know who this inverter works first the two of volt DC comes from your battery connected to this couple of MOSFETs the gaze of the MOSFETs connected to a PWM generator IC switching frequency in this case is 33 kilohertz so the 12 volt continuous voltage converted to to avoid PWM pulses and goes to the transformer inputs the output voltage of this transformer will be 230 volt AC the output voltage of this transformer connected to bridge dealt rectifier and a bit capacitor the voltage across this capacitor will be about 260 volt DC then these four MOSFETs switching by another PWM generator IC to convert the 260 volt DC to about 230 AC voltage with the frequency of 50 Hertz then we are going to converting this secure inverter to pure sine wave inverter the first problem due to this conversion is the peak voltage assuming we have two AC waveform with the same frequency the secure wave peak voltage should be 260 watt to give us 220 volt RMS but the sine wave peak water should be 311 words to give us 220 volt RMS so if you convert this inverter to pure sine without solving this problem the output voltage will be 180 volts instead of 220 volt RMS to solving this problem you have to increase the output voltage of this transformer to increasing the output voltage of any transformer you have two ways the first way is increased the outputs or secondary winding turns number the second way is decreasing the primary winding towards number so I removed this transformer from the board and open it the primary side made by two coil each coil three turns I decreased the winding number from three to only two tours the primary wire made by eight wires in parallel for handle the high current then IRA's order this transformer on the board then we have to increase the switching frequency of the input MOSFETs from 33 kilohertz to 96 kilohertz because we decreased the turning number of the primary and decreased the inductance according to data sheet of ICT l four nine four I have to replace this fifteen kilo ohm resistor to 4.7 kilo ohm resistor after running the circuit as you can see the voltage across this capacitor increases from 260 volt DC to 335 DC voltage the next step is feeding s PWM signal to the MOSFETs gates I removed the IC from the board and connect to s PWM signals comes from Arduino board in place of pin number eight and pin number 10 of the IC know we have s PWM in the output of the inverter the low-pass filter in the output to convert s PWM to pure sine-wave as you can see after connecting the low-pass filter in the output know we have a sine wave but this waveform is not very clean there are some spike so I put a zero point 8 micro farad capacitor in the output and the output become a clean pure sine wave this transformer is a feedback loop connected to the feedback pin of the IC to make the output voltage stable whether the load is on or off see what happens if I remove the feedback loop the output voltage change depends on the load so the feedback loop is necessary to make the output voltage stable whether the load is on or off so there are five steps to convert any modified or secure wave inverter to pure sine-wave step number one is increasing the output voltage of the transformer step number two is increasing the frequency of output MOSFET switching step number three is feeding a s pwm signal to the gates of the output MOSFETs step number four is using a low-pass filter to converting the s PWM to pure sine-wave and finally step number five is using a feedback loop to make the output voltage stable as always I put the wiring and Arduino coding in the description of this video thanks for watching [Music]

Channel: Mousa - Simple Projects

Views: 243,225

Keywords: How to convert square wave inverter to pure sine, Inverter, Pure sine inverter, Sine inverter, How to convert a Modified /Square wave inverter to Pure Sine, Modified /Square wave inverter

Id: GIsgjr0CU6Q

Length: 7min 25sec (445 seconds)

Published: Sun Nov 04 2018