Advantages of regulated power supplies
Low power consumption and high efficiency. In the switching power supply circuit shown in Figure 1, transistor V, under the excitation signal, alternately operates in a switching state between on-off and off-on, with a very fast switching speed. The frequency is generally around 50kHz, and in some technologically advanced countries, it can reach several hundred or even close to 1000kHz. This results in very low power consumption of the switching transistor V, and the efficiency of the power supply can be greatly improved, reaching up to 80%.
Small size and light weight. The block diagram of the switching power supply clearly shows that a bulky power frequency transformer is not used. Because the power dissipation on the regulating transistor V is significantly reduced, a large heat sink is also eliminated. For these two reasons, the switching power supply is small in size and light in weight.
Wide voltage regulation range. The output voltage of the switching power supply is adjusted by the duty cycle of the excitation signal. Changes in the input signal voltage can be compensated for by frequency modulation or pulse width modulation. Thus, even when the mains voltage fluctuates significantly, it can still maintain a relatively stable output voltage. Therefore, the switching power supply has a wide voltage regulation range and excellent voltage regulation effect. Furthermore, there are two methods for changing the duty cycle: pulse width modulation (PWM) and frequency modulation (FM). This gives switching power supplies not only a wide voltage regulation range but also a variety of methods for achieving voltage regulation, allowing designers to flexibly select various types of switching power supplies according to the requirements of their applications.
The filtering efficiency is greatly improved, significantly reducing the capacitance and size of the filter capacitor. Switching power supplies typically operate at 50kHz, which is 1000 times that of linear power supplies, resulting in a nearly 1000-fold increase in filtering efficiency after rectification. Even using half-wave rectification followed by capacitor filtering improves efficiency by 500 times. Under the same ripple output voltage, the capacitance of the filter capacitor in a switching power supply is only 1/500 to 1/1000 of that in a linear power supply.
The circuit configuration is flexible and diverse. For example, there are self-excited and externally excited types, pulse width modulation and frequency modulation types, single-ended and double-ended types, etc. Designers can leverage the strengths of various types of circuits to design switching power supplies that can meet the needs of different applications.
