In the information age, BP has become a commonly used communication tools. Currently, my BP machine total transmitting equipment adopt import equipment, the output voltage is 13. 8V, current is 15~20A. Importing power with Silicon parts, and large fluctuation in China, this design has such a low cost regulated power supply. The design on the basis of feedback adjustment type series power supply equipped with thyristor phase control device, used to adjust the ends of the pipe pressure drop control thyristor conduction angle that is triggered, maintain adjusted pipe pressure drop constant, to design the track-high power DC power supply. The voltage limit adjustment tube power, achieving high power.

The regulated power supply, mainly by single phase half-controlled bridge, linear regulator and rectifier filter composed of thyristor phase control and so on, and adding over-current protection, short-circuit protection, thermal protection device and display section. 220V voltage fluctuation ± 15% case, the output voltage of  JVC AA-VF8 Battery Charger 13. 8V output current up to 20A. As a result of the thyristor phase-control technique, adjust the ends of the pipe pressure drop can be limited to around 3V, Max 40W power consumption, improved power efficiency.

When the output while more than 20A currents, current-limiting protection to reduce the output current. Output short circuit, short-circuit turn-off thyristor output blocked signal. Start fan when you adjust the temperature above 60 ° c, off the fan when the temperature lower than 40 ° c, temperatures above 80 ° c turn-off thyristor. The power supply adopts the integrated thyristor trigger, dual operational amplifier and the voltage regulator tube with temperature compensation for reference, and equipped three-terminal regulator as an auxiliary power supply, enabling high-precision.

2 specific circuit implementation

Circuit diagram

Select one-way bridge half controlled rectifier circuit the circuit, reduced costs. High power or high current regulated power supply, generally use the L-C filter circuit. However, the current filter reactor volume, weight, prices are more expensive, therefore, is still used in the design of the power supply capacitor filtering. Linear voltage regulators-part series feedback adjustment regulator principles, forming a closed loop feedback system. Including adjustment tubes, sampling circuits, voltage reference source, error amplifiers. Due to the constant voltage power supply output current of 20A, electric current is large, so to reduce the adjustment tube power, takes the form of parallel, in the power, adjust the work two high-power transistors in parallel, so that each tube through the current to 10A. In this way, each pipe less than 40W power consumption, reduces the adjustment tube power. Adjusting the tube collector current to Panasonic DMW-S1 Battery Charger 10A, so you should use high power Crystal triode, select beta =40~50, so that the base current up to 2x0. 3 a, 600mA. Generally only dozens of Ma of output current level of integrated operational amplifier, amplifier output directly must not be allowed to promote adjustment tubes, in amplifier output and the adjustment between the base of the tube, joined promoted level, here to choose a low power transistor, constitute a form of composite pipe. Start a resistance Rc take 2k. Anti-vibrating capacitor c take 10 μ f.

Voltage regulator circuit, reference is the reference for the entire regulator system, final result depends on the reference level of voltage regulator. Therefore, in the power, select 2CW234 series silicon with temperature compensation characteristic of voltage regulator tube as a reference source, and select stable voltage to 6. 4V。 By the good characteristics of three-Terminal integrated voltage regulator power supply, current-limiting resistor using precision metal film resistor r (temperature coefficient of about ± 1x10-5/° c). In order to reduce the effects of noise, voltage regulator tube packaging in the prosperous oil in small containers, noise indicators will be significantly improved.

Sample the voltage as shown in Figure 2. Set-emitter voltage of the tube will be adjusted individually through resistor voltage divider, and pressure through a resistor into the emitter voltage amplifier RP end; string into the collecting electrode sampling circuit for voltage regulator tube, pipe pressure drop size determined by the pipe adjusted. -3 here. 3V。 And after the collector voltage minus the voltage regulator tube voltage value into the amplifiers with phase ends. To ensure that the sampling accuracy, set sampling-emitter resistance should be completely symmetrical, and choose a good temperature characteristics, the same type of precision metal film resistors. Amplifier with an integrated amplifier and negative feedback.

R1=R3,R2=R4; n=R2/set pressure coefficient (R1+R2), integrated operational amplifier output Uo; magnification coefficient k; adjust the pipe collector voltage UC; adjustment tubes the emitter voltage UE;A voltage UA;B voltage UB;:

When pipe pressure drop increases, rising UcE, Uo increases trigger voltage Ub control increases, and integrated trigger-KJ785 is negative: control voltage increases conduction angle decreases. Thus, trigger moves after, Rectifier output decreases.

Working voltage of controllable Silicon rectifier as a first step, its output voltage change is decided by the conduction angle changes. Phase control part is based on the adjusted changes to change the voltage drop of thyristor conduction angle, thereby changing the rectified filter circuit output voltage, keep adjusting the voltage drop at 3V. In the regulated power supply, and a KJ785 thyristor phase-shifted trigger circuit. Because as a power products, shall make every effort to achieve the same function under device properties, simple circuit, achieving easy. 180 degrees different from the trigger circuit can output two trigger pulses, can move in the 0~180du range, can be used to control single phase, bidirectional thyristors and transistors.

KJ785 synchronous detection circuit for hosting, base power, sawtooth wave-forming circuit, phase shift voltage, and sawtooth wave controlled power amplifier integrated circuits and logic components. Sawtooth wave slope determined by external capacitor is external resistor is 9 feet and 10 feet. Pulse width is determined by foot external capacitors, when the capacitor is not answering, pulse width determined by the capacitor, about 30 μ s.

KJ785 single supply operation, triggering circuit to negative polarity, phase-shifted voltage increases, breakover angle decreases.

Sync voltage from 5 feet to enter, you can directly from the grid voltage, step-down current-limiting resistor take grid voltage x103 ω, synchronous transformer isolated inputs can also be used. 7,6 feet provide pulses and pulse control end of the blockade.

The pin functions as shown in table 1.

Due to the constant voltage power supply is a power supply, heat a large transformer, rectifier diode, thyristor, integrated regulator and other, more important is, adjust the pipe is a high power transistor, heat a large. Therefore the regulated Nikon D40 Battery Charger  power supply, fans, air, choose cheap, very good AD590 heat sensor, its installation in tubes on the heatsink. When the when the temperature up to about 60 ° c, start the cooling fan when when the temperatures dropped to around 40 ° c, turn off the fan. When the temperature of up to 85 ° c, sent to SCR trigger circuits of blocked signals, turn-off thyristor and closed off roads, avoid adjusting the tube overheating damage.

Electric circuit as shown in Figure 3.

AD590 external characteristics: 0 ℃, at 273 μA; temperature increase of 1 ° c, current increases 1 μA; falling temperature 1 ° c, current decrease 1 μA; working temperature ~+150 ℃-50 ℃; to avoid frequent actions or malfunction, select hysteresis width of 1V.

Preparation of R=40k ω; select integrated amplifier +5V power supply from a single supply, can get from CW78M15.

Set temperature 65 ° c comparator voltage reference for the EmH, are:

Set temperature-40 ℃ comparator voltage reference for the EmL,

Access: R1=2k; Rf=10k

Validation:

So: when the temperature is 61 ° c, start fan when reduced to 40 ° c, turn off the fan. When you adjust temperature up to around 80 ° c, comparator output zero level, blocking SCR, turn power off power off road.

In the regulated power supply, function of short circuit protection is detected when the output voltage is lower than 2V and 2s delay after, judging for short circuit. Issue a blocking signal turn-off thyristor, closed off roads, and prevent damage to the device.

When the load current is the current-limiting protection for more than 20A, reduce the adjusted base current, the output current decreases.

3 closing

This new type of tracking SCR DC voltage-stabilized power supply low cost, better performance, higher accuracy, and launch pad for BP. Output voltage range 12V to 15V, currents up to 20A. Characteristics of the power section is phase control, it also has advantages of SCR and feedback series regulator, to overcome the traditional series of feedback adjustment of adjusting voltage tube power disadvantage.

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