What does pwm mean?

pwm means "pulse width modulation"; pulse width modulation is an analog control method that modulates the bias of the transistor base or MOS tube gate according to changes in the corresponding load to realize the transistor or The change of the conduction time of the MOS tube realizes the change of the output of the switching regulated power supply. This method can keep the output voltage of the power supply constant when the working conditions change. It is a method of using the digital signal of the microprocessor to control the analog circuit. A very effective technology; widely used in many fields from measurement and communications to power control and conversion.

#The operating environment of this tutorial: Windows 10 system, Dell G3 computer.

What does pwm mean?

PWM generally refers to pulse width modulation. (Foreign name: Pulse width modulation)

Pulse width modulation is an analog control method that modulates the bias of the transistor base or MOS tube gate according to changes in the corresponding load to realize the transistor or The change in the conduction time of the MOS tube results in a change in the output of the switching regulated power supply. This method can keep the output voltage of the power supply constant when the working conditions change. It is a very effective technology for using the digital signal of the microprocessor to control the analog circuit. It is widely used in many fields from measurement and communication to power control and conversion.

Basic Principle Editorial Report

Basic Principle of Pulse Width Modulation (PWM): The control method is to control the on and off of the inverter circuit switching device, so that the output end gets a series of equal amplitudes but Pulses with inconsistent widths, use these pulses instead of sine waves or desired waveforms. That is, multiple pulses are generated in half a cycle of the output waveform, so that the equivalent voltage of each pulse is a sinusoidal waveform, and the obtained output is smooth and has few low-order harmonics. Modulating the width of each pulse according to certain rules can not only change the output voltage of the inverter circuit, but also change the output frequency [1].

For example, if the sine half-wave waveform is divided into N equal parts, the sine half-wave can be regarded as N connected to each other. A waveform composed of pulses. The width of these pulses is equal to π/n, but the amplitudes are different. The top of the pulse is not a horizontal straight line, but a curve. The amplitude of each pulse changes sinusoidally. If the above pulse sequence is replaced by the same number of rectangular pulse sequences of equal amplitude but not equal width, make the midpoint of the rectangular pulse coincide with the midpoint of the corresponding sine division, and make the area (i.e. impulse) of the rectangular pulse and the corresponding sine part If equal, we get a set of pulse sequences, which is the PWM waveform. It can be seen that the width of each pulse changes according to the sinusoidal law. According to the principle that equal impulses have the same effect, the PWM waveform and the sine half wave are equivalent. For the negative half cycle of the sine, the PWM waveform can also be obtained using the same method.

In the PWM waveform, the amplitude of each pulse is equal. When you want to change the amplitude of the equivalent output sine wave, you only need to change the width of each pulse according to the same proportional coefficient. Therefore, in the AC-DC - In an AC converter, the pulse voltage output by the PWM inverter circuit is the amplitude of the DC side voltage.

Based on the above principle, after giving the sine wave frequency, amplitude and the number of pulses in half a cycle, the width and interval of each pulse of the PWM waveform can be accurately calculated. By controlling the on and off of each switching device in the circuit according to the calculation results, the required PWM waveform can be obtained. Figure 1 shows the real-time waveform of the PWM wave output by the inverter.

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