Our country is moving from a manufacturing powerhouse to an intelligent manufacturing powerhouse, and the updates and upgrades of consumer electronics and intelligent products are becoming faster and faster. The high frequency, efficiency, and miniaturization of switch power adapters have become the pursuit of consumers, and are also the goals of development and design for switch power supply pcb board manufacturers.
Power Supply Module
The intelligent transformation of power plants is facing a series of more complex issues, such as reliability design, testability, and producibility. The role of frontline R&D engineers is not only in the production of prototype prototypes, but also in the transformation from R&D to mass production, and then to product automation production. In the face of today’s massive knowledge, frontline R&D technicians have become even more confused. How to organize, absorb, and transform into their own skills in the vast and complex data has become a major challenge for entry-level switching power supply engineers. The switch power adapter, USB charger, and PD fast charger head of Advanced Product Solution Technology are mainly consumer oriented. In subsequent website articles, we will popularize some basic knowledge of power supply to everyone.
What is the power factor in the fast wall charger product?
Power factor, also known as PF value, is the first letter abbreviation of Power Factor in English. It is a parameter name that we power engineers are very familiar with. Basically, from the beginning of contact with the power adapter, we will hear the name PF. However, the actual situation is that the concept and significance of PF is a question that many engineers are puzzled about, whether it is a beginner or an experienced engineer, there is a greater or lesser lack of this concept. For example, during a recruitment interview, interviewers have encountered headache questions that may seem so simple, but in reality, they are unable to answer:
Question 1: Does DC DC also have the concept of PF? The answer is: No, because the definition of PF is in AC power supply systems and is based on a sine wave signal as a reference.
Question 2: Does the PF value measure the characteristics of the load device or the input power grid? Because the reference standard is the municipal power grid, and the load is always ever-changing and unpredictable, the PF value is usually used to express the power load itself.
Question 3: Will the absolute value of PF be greater than 1? The answer is: it will not be greater than 1, and the absolute value of PF is between 0 and 1, with a maximum of 1
Question 4: Is there a relationship between the PF value and the load of the power supply? The answer is: It’s relevant, when the load is different from the load of different applications, it will affect PF
Question 5: Why does IT information technology equipment require a PF value above 75W, while LED lighting products generally require a PF value above 25W? After various standards and regulations were issued, the government has put forward requirements for the PF value of products.
Question 6: Is there a negative number in the PF value? The answer is: there can be negative numbers in the displacement term, and if the current is ahead of the voltage, it is a negative number.
The above questions seem so natural. Let’s start from the source step by step, pick up the textbooks we once forgot, and start understanding the concept of PF from the simplest foundation of electrical engineering.
The power factor includes two parts, one is the displacement factor and the other is the distortion factor.
For ease of understanding, it is assumed that the voltage signal of 220V in the municipal power grid is used as the reference, and its waveform is a standard sine curve. The displacement factor is defined as the phase difference between voltage and current fixed at a certain reference point, that is, the voltage and current are not synchronized. This is seen from a time series perspective, and it has positive and negative directions. The distortion factor is defined as the difference in waveform shape between current and voltage, as previously set, the voltage is a perfect sine curve. However, due to the different loads connected to the mains network, the shape of the absorbed current waveform is different from that of the voltage waveform. This is observed and compared from the perspective of waveform shape.
Due to the different forms of loads connected to the municipal power grid, PF will be affected by different loads, and thus different; There are generally three types of load situations:
1. Pure resistance load: Pure resistance load has no effect on displacement factor, nor does it affect distortion factor. Typical loads such as microwaves, heaters, incandescent bulbs, etc.
2. Pure reactive component load: This only affects the displacement factor and does not affect the distortion factor. Typical loads are capacitive or inductive, such as refrigerators, motors, and other products.
3. Nonlinear load: It is a combination of resistive load and reactive load, which is a common situation we encounter. This type of load not only affects the displacement factor, but also the distortion factor. A typical load is the use of various electronic devices in our daily lives, such as power supplies, computers, energy-saving lights, etc.
Post time: May-10-2023