[SOLVED] My sine wave inverter.

[kabiru]

How sinewave is generated in PWM inverter?

Thank's for the reply, now are you saying if i generate high freq out put (square wave) let say 15-20khz with my pwm ic like SG3525 or TL494 then using low pass filter will eliminate high freq and alow the low freq to pass ? are you taking about space vector?

Added after 12 minutes:

i am using IR2110 hi&lo side driver as H-bridge arrangment and how can i generate sinewave info?

 

[betwixt]

Re: How sinewave is generated in PWM inverter?

The output of the micro is, or is close to a square wave, it is a digital signal.

The sine wave is generated by taking the average (by filtering) of the on to off ratio of the digital signal. Consider that a continuous digital zero averages to zero volts and a continuous logic high averages to supply voltage, typically 5V. By rapidly switching between high and low, any average between zero and supply can be generated. The difference between the low period and the high period within a fixed time period sets the analog voltage, this is how PWM works.

To get the sine shape, the PWM output is set a t a suitable high frequency, possibly 10s of KHz and at a lower rate the on/off period is changed to make each step of the waveform. For example, to simulate a 50Hz sine in 100 steps, you would change the ratio 500 times a second, each ratio representing one of 100 points in the sine waveform.

Brian.

 

[srizbf]

Re: How sinewave is generated in PWM inverter?

pwm ics 3525 /494 is suitable for this.

'space vector ' ..here?

give pwm o/p to ir2110 gates .
follow the phases reqd for switching h bridge.
you will get pwm output.

srizbf
17thmay2010

 

[kabiru]

Re: How sinewave is generated in PWM inverter?

Thanks for your reply guys, i think i am understand something can we move to my previous tread{Named my sine wave inverter}

Added after 2 minutes:

The output of the micro is, or is close to a square wave, it is a digital signal.

The sine wave is generated by taking the average (by filtering) of the on to off ratio of the digital signal. Consider that a continuous digital zero averages to zero volts and a continuous logic high averages to supply voltage, typically 5V. By rapidly switching between high and low, any average between zero and supply can be generated. The difference between the low period and the high period within a fixed time period sets the analog voltage, this is how PWM works.

To get the sine shape, the PWM output is set a t a suitable high frequency, possibly 10s of KHz and at a lower rate the on/off period is changed to make each step of the waveform. For example, to simulate a 50Hz sine in 100 steps, you would change the ratio 500 times a second, each ratio representing one of 100 points in the sine waveform.

Brian.

Added after 4 minutes:

betwix can you explain it more clearly please,

thanks

Added after 5 minutes:

at srizbf its a nice idea but what would be the output wave form?

Added after 1 minutes:

pwm ics 3525 /494 is suitable for this.

'space vector ' ..here?

give pwm o/p to ir2110 gates .
follow the phases reqd for switching h bridge.
you will get pwm output.

srizbf
17thmay2010

 

[srizbf]

still pwm but a bipolar type.

srizbf
17thmay2010

 

[kabiru]

Thank's alot, but what do you mean with still pwm but a bipolar type?

 

[srizbf]

the waveform in the h-bridge load is still a pwm wave
but it will change to opposite polarity on alternate pwm cycle.

srizbf
18thmay2010

 

[kabiru]

The most important thing here is how to achieved the pwm signal, thank's for help my fellow members everthing is working fine.