Introduction to linear regulated power supplies, switching power supplies and phase-controlled power supplies
DC power supply can be divided into three categories: linear regulated power supply, switching power supply and phase-controlled power supply according to different conversion methods.
1. The linear regulated power supply can meet the DC voltage requirements and power supply quality (accuracy, ripple, etc.) requirements required by electronic circuits. However, it has two major shortcomings: First, the adjustment tube VT works in a linear amplification state, and the loss is very high. Large, the power supply efficiency is very low; second, a power frequency transformer T is required, making the entire power supply large in size and heavy in weight.
2. The switching power supply emerged to overcome the shortcomings of the linear regulated power supply. It is named after its electric (power) electronic devices that always work in the switching state.
3. Phase controlled power supply is the abbreviation of thyristor phase controlled power supply. Like the switching power supply, the power electronic devices in the phase-controlled power supply also work in the switching state, but their working frequency is power frequency (50Hz), not high frequency. In contrast, a significant advantage of phase-controlled power supply is simple circuit and convenient control. Its main disadvantage is that it requires a power frequency transformer, making the entire power supply large and heavy. In addition, the DC output voltage ripple frequency of the phase-controlled power supply is only several times the power frequency (2 times for single-phase full-bridge control and 6 times for three-phase full-bridge control). A larger filter is required to achieve better filtering. Effect. The switching power supply DC output voltage ripple frequency is very high, often above 20kHz, so only a small filter is needed. Due to the low switching frequency of the phase-controlled power supply, its control response speed is also slower than that of the switching power supply.
According to custom, switching power supply refers specifically to DC power supply with electric (power) electronic devices working in high-frequency switching state, so it is also called high-frequency switching power supply, while phase-controlled power supply is not included in switching power supply.
