Advantages and disadvantages of switching power supply

　　Advantages of switching power supply:

　　1. Low power consumption and high efficiency. In the switching power supply circuit, the transistor V works alternately in the on-off and off-on switching states under the stimulation of the excitation signal. The switching speed is very fast, and the frequency is generally around 50kHz. In some technologically advanced countries, it can reach several hundred or nearly 1000kHz. This makes the power consumption of the switching transistor V very small, and the efficiency of the power supply can be greatly improved, and its efficiency can reach 80%.

　　2. Small size and light weight. From the principle block diagram of the switching power supply, it can be clearly seen that no bulky power frequency transformer is used here. Since the power dissipation on the adjustment tube V is greatly reduced, a large heat sink is omitted. Due to these two reasons, the switching power supply is small in size and light in weight.

　　3. Wide voltage regulation range. The output voltage of the switching power supply is adjusted by the duty cycle of the excitation signal, and the change of the input signal voltage can be compensated by frequency modulation or width modulation. In this way, when the power frequency grid voltage changes greatly, it can still ensure a relatively stable output voltage. Therefore, the voltage regulation range of the switching power supply is very wide and the voltage regulation effect is very good. In addition, there are two methods to change the duty cycle: pulse width modulation and frequency modulation. The switching power supply not only has the advantage of a wide voltage regulation range, but also has many ways to achieve voltage regulation. Designers can flexibly select various types of switching power supplies according to the requirements of actual applications.

　　The efficiency of filtering is greatly improved, which greatly reduces the capacity and volume of the filter capacitor. The operating frequency of the switching power supply is currently basically 50kHz, which is 1000 times that of the linear voltage-regulated power supply. This makes the filtering efficiency after rectification almost 1000 times higher; even if half-wave rectification is used and capacitor filtering is added, the efficiency is also increased by 500 times. Under the same ripple output voltage, when using a switching power supply, the capacity of the filter capacitor is only 1/500~1/1000 of the filter capacitor in the linear voltage-regulated power supply. The circuit form is flexible and diverse, including self-excitation and external excitation, width modulation and frequency modulation, single-ended and double-ended, etc. Designers can give full play to the strengths of various types of circuits and design switching power supplies that can meet different application occasions.

　　Disadvantages of switching regulated power supply:

　　The disadvantage of the switching power supply is the existence of serious switching interference. In the switching power supply, the power adjustment switch transistor V works in the switching state, and the AC voltage and current it generates pass through other components in the circuit to generate spike interference and resonance interference. If these interferences are not suppressed, eliminated and shielded by certain measures, they will seriously affect the normal operation of the whole machine. In addition, since the switching power supply oscillator is not isolated by the power frequency transformer, these interferences will be connected to the power frequency power grid, causing serious interference to other nearby electronic instruments, equipment and household appliances.

　　At present, due to the gap between domestic microelectronics technology, resistor and capacitor device production technology and magnetic material technology and some technologically advanced countries, the cost cannot be further reduced, which also affects the further improvement of reliability. Therefore, in my country's electronic instruments and mechatronics instruments, switching power supplies cannot be widely popularized and used. In particular, for high-voltage electrolytic capacitors, high-reverse-voltage high-power switching tubes, and magnetic core materials of switching transformers in switching power supplies without power frequency transformers, they are still in the research and development stage in my country.

　　In some technologically advanced countries, although the switching power supply has made some progress, there are still some problems in practical applications, which are not very satisfactory. This exposes another disadvantage of the switching power supply, that is, the circuit structure is complex, the failure rate is high, and the maintenance is troublesome. In this regard, if the designers and manufacturers do not pay enough attention to it, it will directly affect the promotion and application of the switching power supply. Today, the main reason why the switching power supply is difficult to promote and apply is that its manufacturing technology is difficult, the maintenance is troublesome, and the cost is high.