Do you know enough about pwm? Find out pwm control technology

Pwm is one of the important modern technologies. Pwm exists in various Electronic devices. In order to enhance everyone’s understanding of pwm, this article will explain the pwm control technology.

Pwm is one of the important modern technologies. Pwm exists in various electronic devices. In order to enhance everyone’s understanding of pwm, this article will explain the pwm control technology.

Do you know enough about pwm? Find out pwm control technology

1. Introduction to pwm

PWM, or pulse width modulation, is the abbreviation of “Pulse Width ModulaTIon” in English, and pulse width modulation for short. It is a very effective technology that uses the digital output of a microprocessor to control analog circuits. It is widely used in measurement, Communication to many areas of power control and conversion.

Two, pwm control technology

The PWM (Pulse Width ModulaTIon) control technology is a technology for modulating the width of a pulse, that is, by modulating the width of a series of pulses to equivalently obtain the desired waveform (including shape and amplitude). The area equivalent principle is an important basic theory of PWM technology. A typical PWM control waveform SPWM: the pulse width changes according to the sine law. The PWM waveform equivalent to sine wave is called SPWM wave.

Pulse Width Modulation (PWM, Pulse Width ModulaTIon) is a very effective technology that uses the digital output of a microprocessor to control analog circuits. It is widely used in many fields from measurement and communication to power control and conversion. PWM is a method of digitally encoding analog signal levels. Through the use of high-resolution counters, the duty cycle of the square wave is modulated to encode the level of a specific analog signal.

Do you know enough about pwm? Find out pwm control technology

(1) Features of pwm control technology

Switching power supplies generally use pulse width modulation (PWM) technology, which is characterized by high frequency, high efficiency, high power density, and high reliability. However, because its switching devices work in a high-frequency on-off state, the high-frequency fast transient process itself is an electromagnetic disturbance (EMD) source, and the EMI signal it generates has a wide frequency range and a certain amplitude. If this power supply is directly used in digital equipment, the EMI signal generated by the equipment will become more intense and complex.

One of the advantages of PWM is that the signals from the processor to the controlled system are in digital form and are undergoing digital-to-analog conversion. Can minimize the impact of noise. The enhancement of noise resistance is another advantage of PWM over analog control, and this is also the main reason why PWM is used for communication in some cases. Switching from analog signal to PWM can greatly extend the communication distance.

(2) Advantages of pwm control technology

Because PWM can realize the characteristics of frequency conversion and voltage transformation to suppress harmonics at the same time. As a result, it is widely used in AC drives and other energy conversion systems. PWM control technology can be roughly divided into three categories:

1. Sinusoidal PWM (including various PWM schemes targeting the sine of voltage, current or magnetic flux, multiple PWM should also be included in this category). Sinusoidal PWM is well known. The multiple PWM technology designed to improve the output voltage, current waveform, and reduce the harmonics of the power supply system has its unique advantages in high-power inverters.

2. Optimizing PWM Optimizing PWM pursues the smallest current harmonic distortion (THD), the highest voltage utilization, the best efficiency, the smallest torque ripple, and other specific optimization goals.

3. Random PWM.

Do you know enough about pwm? Find out pwm control technology

(3) PWM control method

There is an important conclusion in the sampling control theory: when narrow pulses with equal impulse but different shapes are applied to a link with inertia, the effect is basically the same. The PWM control technology is based on this conclusion to control the turn-on and turn-off of the semiconductor switching device, so that a series of pulses of equal amplitude but unequal width are obtained at the output terminal, and these pulses are used to replace sine waves or other pulses. The desired waveform.

The width of each pulse is modulated according to certain rules, which can change the output voltage of the inverter circuit and the output frequency.

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