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    Can I drive a Full-Bridge with PWM1H1 and PWM1L1 signals of dsPIC33 and IR2112?

    Can I drive a Full-Bridge with PWM1H1 and PWM1L1 signals of dsPIC33 and IR2112?

    I need to get 220V AC 5kHz from the Full-Bridge output. Due to low PWM resolution issue in PIC18F, I am preferring to use dsPIC33FJ32MC204.

    My PWM frequency will be 100kHz.

    I need to get 50kHz Sine signal from the SPWM.

    So, can I drive Full-Bridge (4 N-Channel Mosfets) with PWM1H1 and PWM1L1 signals using 2x IR2112?

    I have not yet started writing the code.

    This much circuit I have designed (check the attached PDF file).

    The voltages of graph 1 and 2 doesn't look right. Why?

    - - - Updated - - -

    Consider this file.
    Last edited by baileychic; 27th December 2019 at 00:17.

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    Re: Can I drive a Full-Bridge with PWM1H1 and PWM1L1 signals of dsPIC33 and IR2112?

    50 kHz sine? 5 kHz sine? Or is it 50 Hz?

    The voltages of graph 1 and 2 doesn't look right. Why?
    The waveforms have nothing to do with full bridge or PWM. What you see is a trivial inrush current effect. Why do you worry about it?


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    Re: Can I drive a Full-Bridge with PWM1H1 and PWM1L1 signals of dsPIC33 and IR2112?

    I want 50 kHz sine voltage output and PWM frequency will be 100 kHz.

    I am not talking about waveforms. My issue is can PWM1H1 and PWM1Li signals enough to drive the Full-Bridge of course using the IR2112.

    Why there will be an inrush current?

    I will use PTC to avoid inrush current if needed at the transformer primary of top transformer.



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    Re: Can I drive a Full-Bridge with PWM1H1 and PWM1L1 signals of dsPIC33 and IR2112?

    I am not talking about waveforms.
    Apparently you have been talking about waveforms:
    The voltages of graph 1 and 2 doesn't look right. Why?
    Anyway, I guess we should ignore the inrush current point for the time being.

    O.K., actually 50 kHz. But there can be no SPWM then, just 50 kHz square wave. This simplifies the drive signal generation a lot.


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    Re: Can I drive a Full-Bridge with PWM1H1 and PWM1L1 signals of dsPIC33 and IR2112?

    Yes, regarding graphs I had mentioned about incorrect voltages for the top 2 graphs. The graphs have to show the peak values for the 220 V RMS.

    I need a 50kHz sine wave output. If SPWM is not used then how can I get sine wave output?



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    Re: Can I drive a Full-Bridge with PWM1H1 and PWM1L1 signals of dsPIC33 and IR2112?

    My issue is can PWM1H1 and PWM1Li signals enough to drive the Full-Bridge of course using the IR2112.
    Yes, if the right half bridge shall be driven with the inverted waveform of the left half bridge.

    - - - Updated - - -
    I thought you are worrying about the distorted S1 and S2 values, which is an inrush problem.
    Yes, regarding graphs I had mentioned about incorrect voltages for the top 2 graphs. The graphs have to show the peak values for the 220 V RMS.
    They do, peak voltage V(P1)-V(P2) is 325 V. Think again.

    I need a 50kHz sine wave output. If SPWM is not used then how can I get sine wave output?
    Using a low pass filter.

    - - - Updated - - -

    It's probably useful to take the load circuit into account. Depending on the application, a resonant circuit matching the load (LC series circuit, LLC circuit) is preferred in terms of switching losses.


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    Re: Can I drive a Full-Bridge with PWM1H1 and PWM1L1 signals of dsPIC33 and IR2112?

    Hi,

    I want 50 kHz sine voltage output and PWM frequency will be 100 kHz.
    It's the very edge situation.
    In my eyes it has nothing to do with SPWM.
    It is just one single pulse for positive halfwave and one for negative halfwave. Just ON and OFF. The signal waveform has nothing to do with sine shape, one just uses the fundamental frequency while one tries to suppress all overtones...beginning with 3rd harmonic, which is a challenge.

    Usually the PWM_frequency to sine_frequency rate should be higher than 20. Makes just 5 different duty_cycle values.
    If you want to get an fairly clean SPWM up to 30th overtone, one should consider a PWM frequency of 2 x 50Hz x 30 = 3000Hz.
    For sure elaborated analog filters will have a big influence.

    Klaus
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    Re: Can I drive a Full-Bridge with PWM1H1 and PWM1L1 signals of dsPIC33 and IR2112?

    Okay, thanks. Got the graphs correct.

    Will write some code for the Full-Bridge and update this thread.

    - - - Updated - - -

    Quote Originally Posted by KlausST View Post
    Hi,
    Usually the PWM_frequency to sine_frequency rate should be higher than 20. Makes just 5 different duty_cycle values.
    If you want to get an fairly clean SPWM up to 30th overtone, one should consider a PWM frequency of 2 x 50Hz x 30 = 3000Hz.
    For sure elaborated analog filters will have a big influence.

    Klaus

    3000Kz = 3kHz PWM can give 50kHz sine wave output? Actually I want 20kHz to 50kHz variable sine wave output.



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    Re: Can I drive a Full-Bridge with PWM1H1 and PWM1L1 signals of dsPIC33 and IR2112?

    3000Kz = 3kHz PWM can give 50kHz sine wave output? Actually I want 20kHz to 50kHz variable sine wave output.
    You mean 3 MHz PWM? Impossible with high voltage Si MOSFET. Might work with GaN, but that's completely different (and very demanding) technology. For the said purpose there are probably more simple ways than MHz PWM.



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    Re: Can I drive a Full-Bridge with PWM1H1 and PWM1L1 signals of dsPIC33 and IR2112?

    Sorry, it was 3000Hz = 3kHz as mentioned by Klaus.



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    Re: Can I drive a Full-Bridge with PWM1H1 and PWM1L1 signals of dsPIC33 and IR2112?

    Your lastest statement about sine frequency was 50 kHz, hence 3 kHz pwm is just ridiculous. Would you mind to try once more a consistent specification of the inverter parameters?


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    Re: Can I drive a Full-Bridge with PWM1H1 and PWM1L1 signals of dsPIC33 and IR2112?

    I need a 20kH to 50kHz Sine wave output from the Full-Bridge + output filter (LC filter).

    I can use any PWM frequency from 10kHz to 300kHz.

    What good PWM frequency can give 20kHz to 50kHz sine wave output?



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    Re: Can I drive a Full-Bridge with PWM1H1 and PWM1L1 signals of dsPIC33 and IR2112?

    Hi,

    Sorry for the confusion.

    My 3kHz calculation is for 50Hz line frequency applications.

    But you can easily apply 50kHz to the given formula:
    F_PWM = 2 × 50,000Hz x 30 = 3MHz.

    But as already said: the filter has much influence.
    With audio they take a higher effort on filter calculation and additionally don't care that much of overtones in the high audible frequencies, thus they go closer to the edge.

    Klaus
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    Re: Can I drive a Full-Bridge with PWM1H1 and PWM1L1 signals of dsPIC33 and IR2112?

    @FvM

    What are the more simple ways to achieve my requirements.



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    Re: Can I drive a Full-Bridge with PWM1H1 and PWM1L1 signals of dsPIC33 and IR2112?

    Do you have a load impedance specification, acceptable harmonic level, output voltage range?


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    Re: Can I drive a Full-Bridge with PWM1H1 and PWM1L1 signals of dsPIC33 and IR2112?

    No, I don't have any other specification other than 220V AC 20kHz to 50kHz output voltage. Just answer for a general design.



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    Re: Can I drive a Full-Bridge with PWM1H1 and PWM1L1 signals of dsPIC33 and IR2112?

    Quote Originally Posted by baileychic View Post
    What are the more simple ways to achieve my requirements.
    Here's a self-oscillating astable H-bridge made from transistors. The series LC shapes AC square waves into sines. LC values determine resonating frequency.

    Click image for larger version. 

Name:	astable H-bridge 4 transistors 270VDC auto-oscillator series LC shapes sine waves 330VAC amplitu.png 
Views:	4 
Size:	49.3 KB 
ID:	157111

    The challenge is to obtain frequency range 20-50 kHz. It's easier if you can find the right variable components.


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    Re: Can I drive a Full-Bridge with PWM1H1 and PWM1L1 signals of dsPIC33 and IR2112?

    Okay, thanks. I will find out the LC filter values and then simulate it. I will update after testing.



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