The mainstream DC electronic power supplies are divided into three main types according to the circuit structure they work on: Silicon Controlled Rectifier (SCR) DC power supplies, linear DC power supplies, and switch-mode DC power supplies.
In essence, a Silicon Controlled Rectifier (SCR) power supply controls the output voltage and current by altering the conduction angle of the SCR. With its powerful output power and ultra-high power supply specifications, the SCR power supply cannot be replaced by transistor linear power supplies or switching power supplies.
Linear power supplies achieve voltage and current adjustments and stabilization by controlling the base of a transistor (also known as a regulating tube). This is akin to a secondary stabilization on a silicon-controlled rectifier (SCR) power supply, resulting in better electrical energy quality than SCR power supplies. However, due to the typical 5-10V voltage drop across the power adjustment tube, efficiency is lower than that of SCR power supplies. For every 1A of current output, 5-10W of power consumption is added, particularly for low-voltage, high-current specifications where efficiency is even lower.
(3) Switched-mode power supplies (SMPS) regulate voltage and current by controlling the pulse width of PWM signals, achieving stable voltage and current output. Due to their high operating frequencies, they eliminate the need for silicon-controlled rectifiers (SCRs) and linear power supplies' power transformers, being replaced by high-frequency transformers. This results in compact size and high efficiency, hence also known as high-frequency switched-mode power supplies. Initially, limited by high-frequency power semiconductor devices, the technology of switched-mode power supplies was not mature. SCRs and linear power supplies were indispensable. However, with the advancement of high-frequency semiconductor devices, their operating frequencies and power outputs have increased significantly, making the technology of switched-mode power supplies more mature. Manufacturers with strong technical capabilities have achieved reliability and performance that can match, and even exceed, conventional linear power supplies. Added to their advantages of small size and light weight, DC switched-mode power supplies are gradually replacing SCR and linear DC power supplies, particularly for high-power specifications. This trend is especially evident in the gradual exit of the market for high-power SCR DC power supplies and linear DC power supplies. 36V aviation power supply, 400Hz frequency conversion power supply, 115/200V power supply, 27V DC power supply, 400Hz power supply, aviation power supply
(4) Currently, the high-power DC power supply market still lags behind international brands in terms of optimization of high-frequency switching circuit structures. The reliability and performance criteria do not meet the standards of industry manufacturers. Many domestic manufacturers are still producing high-power silicon-controlled rectifiers (SCRs) and linear power supplies using controllable silicon and linear circuit structures, whereas these are largely obsolete technologies overseas, having been replaced by high-frequency switching circuits. Therefore, when selecting power supply options, the standard for determining the quality of a DC power supply cannot be simply judged by the circuit structure or the name of the power supply.
