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Hello everyone, today we are going to learn about the waveforms in PWM circuit

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Here, we focus on the upper and lower tube G-pole waveforms

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and the waveforms at the front and back of the inductor

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First of all, when the common point voltage is 19V,

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the peak value of the G pole of the upper tube is about 24V

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The blue wave is 10V per grid, so channel 2 is 10V per grid

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It takes up about two and a half grids here,

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so it's about 24 volts

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The peak at the G pole of the lower tube is 5V per grid, which is 5V per grid for channel 1

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It occupies exactly one grid, so the peak G of the lower tube is 5V

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Their PWM frequency is 330KHz

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This is the pulse waveform at the G pole of the upper and lower tubes

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Upper tube G is very high level, control the upper tube conduction

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Upper tube G is very low level, control the upper tube cutoff

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When the lower tube G is extremely high, control the conduction of the lower tube

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When the lower tube G is extremely low, control the lower tube cutoff

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From here, we can see that the conduction time of the upper tube is very short,

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the high level time of the lower tube is very long, and the conduction time of the lower tube is long

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The PWM chip will adjust the output voltage by controlling the duty cycle of the upper and lower tube pulses

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The output current can be adjusted by controlling the pulse frequency

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Now let's look at the waveforms at the front of the inductor

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The peak value of the front end of the inductor is equal to the peak value of the common point voltage

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This is coming through the upper tube

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Channel 1 is the inductor back end,

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it is a direct current

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Channel 2 is the front end of the inductor, which is a pulse

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Okay, this is the introduction of the common PWM circuit waveforms