Modern communications industry becomes more prosperous, but he can not do without reliable power source for the heart?? Regulated power supply. Communication with secondary power supply which is used in communications of a high reliability, high-performance power supply, use the number plate is usually installed near or in the communications control panel near the driver, shall not affect its investment and use of quality communications systems . This requires the reasonable structure, convenient maintenance, small size, high efficiency, low noise and reliable. Secondary power supply current communication structure of the main circuit generally use more Forward, flyback, half-bridge structure. This article describes the base station for mobile communication Collector's GY-400-type high-frequency energy-saving switching power supply, he has special requirements: the base station power supply voltage 48 V DC (range: 36 ~ 72 V DC) rose for the DC high voltage 230 V DC (Adjust able range: 220 ~ 300 V DC), and requires a high peak power, multi-protection test remote control signals, and has a leakage detection protection. Based on the above requirements, the principle scheme of an advanced and efficient use of pre-transform theory and the use of active clamp boost soft-switching technology to transform DC-DC isolated power supply. 1 GY-400-type switching power supply key technical indicators DC input voltage range: 36 ~ 72 V DC; input current: 80% (full load); protection type : power protection; output over-current protection: 100 000 h; shape and size: substrate type, 237 * 100 * 52 mm. 2 GY-400 Converter principles of composition 2.1 Electric theory Electric principle diagram shown in Figure 1. As can be seen from the Figure 1, the converter are: to UC2846 control IC as the core controller, drive control push-pull converter, the main converter circuit isolation, input and output filters to LM324 for the core components of the feedback control det ection and protection parts. 2.2 to UC2846 isolation as the core of the push-pull converter 2.2.1 UC2846 principle UC2846 Block Diagram Figure 2. UC2846 TI company is a high performance PWM current control, is mainly used for push-pull converter. UC2846 internal circuit including: oscillator circuit, the current determination of amplifiers, error feedback amplifier, voltage reference, over-voltage protection circuit and under-voltage lockout circuit. His main features are: Week-by-pulse current limit is programmable, a strong ability to limit peak current, external synchronization control, soft start function, dual push-pull pulse PUSH-PULL capacity, pulse frequency of 500 kHz, is the push-pull ideal converter. 2.2.2 Auxiliary power supply and input filter circuit briefly the main Original position shown in Figure 3, the main circuit input filter common mode inductor L1, X capacitors C1, C2, Y capacitors C3, C4 together to complete EMI features, RT start to limit the impact of current thermal resistance, in order to reduce the circuit losses, start after the MOS-FET Q1 shorted RT. U1 (UC3842) for the auxiliary power supply of the PWM generator, drive MOSFET Q2, while driving Q1, TI get through the transformer secondary voltage of +15 V1, +15 V2, and then get through the ZD14 regulator +12 V supply voltage control loop uses the corresponding . Flyback transformer T1 with EEL16 ferrite core, 80-turn primary, secondary and the secondary are 42 turns, the design of appropriate inductance can work. Original position Original position 2.3 to UC2846 main circuit as the core principle of push-pull Shown in Figure 4, the MOSFET Q33, Q34, the main transformer T2, rectifier diodes D6, D7, D8, D9, and the filter inductor L4 constitute a push-pull converter main circuit. U2 (UC2846) complete the push-pull current-mode PWM chip pulse, generating a difference of 180 and the dead-time control of the driving pulse. At the same time to complete current feedback and voltage feedback, current feedback circuit in which the R25, R26, R27, R17, C19 and other components, the current work by detecting the main circuit to adjust the pulse width, so that the inductor current through the transformer following error voltage. Voltage feedback from the feedback loop shown in Figure 5, isolation achieved through the optocoupler U3. U2 to achieve a voltage, current loop loop system, therefore, regardless of switch power supply voltage regulation, load regulation and transient response characteristics are improved, the same time, the use of current-mode control chip, eliminating the partial push-pull transformer magnetic problem. Transformer T2 use EC40 ferrite core, 8-turn primary, secondary 60 turns, the middle screen, close winding, dipping insulated. Key part by T3, Q35, Q36, C66, R102, L5, D10 other components to achieve active clamp technique that allows the second high-voltage rectifier circuit to reduce losses, to achieve high efficiency. L4, C96 form the output filter, R100 for the current sampling resistor, D11, D12 debug output to prevent short-circuit protection setting. Original position Original position 2.4 Feedback control and protection of test section Original position Figure 5 shows the link to LM324 as the core, the main form to adjust voltage and current feedback control part, on the output voltage, light-load starting current limit, on the no-load, over current, over voltage, under voltage protection, and the LM324 U11 , U12, etc. constitute the leakage protection circuit, the circuit has a light direction, the distant signal remote control. The circuit is basically the principle of using GY-238. Original position Original position Original position 3 Conclusion GY-400-type DC-DC converter is specially designed for communication base station communication secondary power supply, after put into use by the user feedback, the GY-238 upon the basis of continuous improvement, has gradually matured, been promoted and applied . Proved that the principle of DC-DC power supply advanced, high efficiency, good performance, protection function, the communications base station products in the preferred configuration, but also can be used for other control devices.
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