What is the principle of PWM technology?
3 Answers
The basic principle of PWM is: the control method involves managing the switching of inverter circuit devices to generate a series of equal-amplitude pulses at the output. These pulses are used to replace sine waves or other desired waveforms. In other words, multiple pulses are generated within half a cycle of the output waveform, making the equivalent voltage of these pulses resemble a sine wave, resulting in a smooth output with minimal low-order harmonics. By modulating the width of these pulses according to specific rules, both the output voltage magnitude and frequency of the inverter circuit can be adjusted. Below is a detailed introduction to PWM: 1. Concept of PWM: PWM stands for Pulse Width Modulation, which is an analog control method. It modulates the bias of the transistor base or MOS gate according to changes in the corresponding load, thereby altering the conduction time of the transistor or MOS tube, thus changing the output of the switching power supply. 2. Advantages of PWM: The signals from the processor to the controlled system remain in digital form, eliminating the need for digital-to-analog conversion. This is because keeping the signal in digital form minimizes the impact of noise, enhancing noise resistance.
PWM technology stands for Pulse Width Modulation. I understand its working principle is like rapidly switching a light on and off to control brightness. Specifically, it generates a series of pulse signals and adjusts the duration of each pulse's 'on' time (also called duty cycle). The higher the duty cycle, the greater the average voltage, making the device operate more powerfully; conversely, it operates more weakly. In automobiles, this technology is widely applied, such as in LED headlight brightness adjustment—without changing bulbs, it can smoothly transition from dim to full brightness, being both efficient and energy-saving. Another example is power window motor control, where PWM ensures smooth and jerk-free movement while preventing motor overload damage. The core principle lies in using rapid switching to average power output, reducing heat loss and extending component lifespan. It contributes significantly to modern automotive design, making electronic control more flexible and reliable.
I often encounter PWM technology when repairing cars, and it offers many benefits. By controlling the pulse width, it regulates energy output, making device operation smarter. For example, in controlling the speed of the car's interior fan: when the pulse width is small, the airflow is weak, and when it's large, the airflow is strong, resulting in low noise and energy savings. Compared to traditional resistor-based speed control, PWM doesn't generate heat or waste resources, significantly improving efficiency. When applied to windshield wiper motors, it ensures smooth starts and stops, protecting mechanical components from wear. Overall, this technology plays a key role in automotive electronics, enhancing driving comfort and fuel efficiency, making it a small perk for modern car owners. It's simple to use and cost-effective.
