If you use a controlled rectifier to control the voltage and fixed PWM to control the frequency of the inverter it will reduce the harmonic content at the output. Used a lot in machine tools at 100-120,000 rpm

Can i use single phase rectifier for obtaining 300 v dc at the output of a rectifier having a 220 v rms ( or 310 peak ) at the input side of the full wave single phase rectifier ? If not then can you propose some solutions ?

You can use a diode rectifier with a closed loop voltage control step down chopper to produce a variable DC link voltage. The inverter can then have a fixed PWM pattern with variable frequency. It used to be called the six step topology but is largely unused today.

So In this case my rectifier would be made of diodes instead of tyristors , Am i right about this statement ?

And Can i use single phase rectifier for getting an output of 300v ( Dc) using a 310 volt ( peak voltage of input sinusoidal signal ) as input ?

Yes.

However, you can also use a controlled rectifier with an outer voltage control loop and inner current control loop to control the DC link capacitor voltage. It may be single or three phase.

Do u know how the Pwm can change the frequency of the output of the inverter in vfd ? I mean how Pwm generated signal can change the frequency of the output of the inverter ??

You can have a simple fixed PWM pattern (ie square wave) and vary frequency. You can do this with a micro and have fixed PWM pattern and just sweep through at higher rate for higher frequencies. What frequency range are you looking at and what application?

I am making the simulations for a VFd drive ,where i am trying to control the inverter output signal frequency using pwm generated by microcontroller .This Vfd will control the speed of induction motor . The inverter output frequency could be changed in the range of " 0Hz to 60 Hz ".I need some guidance about how can pwm changes the frequency of inverter .In microntrollers the prescaler used for changing the frequency of pwm signal ,how can it help me ?

Give me a detailed explanation if u have knowledge regarding this .

How can i sweep through at higher rate for higher frequencies in micro ? Give some explanation

Many micos now have PWM available. They have a fequency input. It is normally an up-down counter and you can control the clock or rate at which the counter counts . You can output 0-1000 Hz . See microchip for example

Ok , how is the output frequency of the inverter is related to the frequency of the Pwm signal? I mean If i have pwm signal of 2kHz then how much approximately will be the inverter output frequency ?

Dear Karrar, I am working on the similar project where I have to make an inverter which will be Inverting DC to 50Hz AC. I want to do it with the help of Diode or MOSFET switches with Micro controller.

Please guide me through.

It can be controlled by using any PWM technique such as sine-PWM or vectoriel PWM that generate the pulses wich control the power component gates.

It can be controlled by using any PWM technique such as sine-PWM or vectoriel PWM that generate the pulses wich control the power component gates.

just use the pulse width modulation technique to create the control pulses of the inverter switches. therefore the frequency and amplitude of the output voltage are controlled by the reference signal used for the modulation.