I understand there are bipolar, unipolar SPWM. Since the switching loss is quite high in these, there also exists a hybrid scheme where for half of the cycle the gates are either on or off reducing the loss by half. I want to find out more about this hybrid scheme especially how the the PWM signals are generated for each of the 4 MOSFETs. In the modulation I am referring to, for half a cycle the first leg is switched at carrier frequency and the switches in other leg is either on or off. In the remaining cycle, the second leg is gated at high frequency and the other one is either on or off. Unfortunately I cannot find more detailed analysis of this circuit. Can someone please explain how the 4 signals are generated, the circuit behind it, the relation between triangular carrier signal and the reference voltage, or refer to a book or a paper where I can find more info. Thanks a lot.
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1\$\begingroup\$ This might help \$\endgroup\$– Andy akaJun 30, 2021 at 7:30
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1 Answer
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Here is a paper on it, although it is for three-phase inverters.
nxp.com/docs/en/application-note/AN4869.pdf
You can copy and paste the numbers into your code from the pdf. I guess I will add the array declaration here, too, at the end.
The waveform looks like this:
The array:
static unsigned char SinusoidalWaveTable[384]={127,131,135,138,142,145,149,152,155,159,162,165,168,171,174,177,180,183,186,189,192,194,197,200,202,205,207,210, 212,214,217,219,221,223,225,227,229,231,232,234,236,237,239,240,242,243,244,245,247,248,249,250,250,251,252,253,253,254,254,255,255,255,255,255,255,255,255,255,255,255,254,254,253,253,252,252,251,250,249,248,247,246,245,244,242,241,240,238,237,235,233,232,230,228,226,224,222,222,225,226,228,230,232,234,235,237,238,240,241,243,244,245,246,247,248,249,250,251,252,252,253,254,254,254,255,255,255,255,255,255,255,255,255,255,254,254,254,253,252,252,251,250,249,248, 247,246,245,244,243,241,240,238,237,235,234,232,230,228,227,225,223,220,218,216,214,212,209,207,204,202,199,197,194,191,188,185,183,180,177,174,171,167,164,161,158,154,151,148,144,141,137,134,130,127,123,119,116,112,108,104,101, 97, 93, 89, 85, 81, 77, 73, 69, 65, 61, 57, 53, 49, 45, 41,36, 32, 28, 24, 20, 16, 12, 7, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 6, 10, 15, 19, 23, 27, 31,35, 39, 44, 48, 52, 56, 60, 64, 68, 72, 76, 80, 84, 88, 92, 96, 99,103,107,111,115,118,121,124 }
