CN2447848Y - Wide AC input range switch power supply for computer - Google Patents

Abstract

A wide AC input range switching power supply for computers, including: filter circuit, rectifier circuit, main circuit, control circuit, drive circuit, feedback circuit, etc., which is connected with a pulse between the rectifier circuit and the voltage-dividing DC filter circuit Wide control voltage compensation circuit, the pulse width control voltage compensation circuit is triggered alternately by the two compensation control coils of the driving transformer of the drive circuit to compensate for the excessive reduction of the AC input voltage, so that the input AC voltage can reach 120-260 volts, especially It is suitable for use as a power supply part of a computer to produce a computer with a wide AC input voltage.

Description

Wide AC Input Range Switching Power Supply for Computer

The utility model relates to a switching power supply, in particular to a wide range switching power supply for computers.

At present, the AC input voltage of switching power supplies for computers is 176-256 volts, and the voltage of power grids where many users are located in many areas of the country fluctuates greatly. , Factories, rural areas, troops, etc. are ubiquitous, and some voltages are as low as about 130 volts. Voltage instability is very prone to frequent startup, data loss, crash, the whole machine cannot work normally, and the service life is shortened.

In order to solve the problem of voltage instability and low voltage, computer users generally add voltage regulators, UPS and other equipment, and some even need to bring their own generators, which greatly increases the input cost of users.

The utility model patent "Wide Range High Power Switching Stabilized Power Supply" (ZL 98229858), its design idea is to sample at the AC input end, then divide the voltage into two gears for switching, process them separately, and output DC voltage. The power supply cost of this scheme is relatively high, and its precision still cannot meet the requirements of switching power supplies for computers.

The purpose of the utility model is to overcome the above-mentioned shortcomings of the prior art and provide a switching power supply for computers with a wide AC input range to meet the needs of computer users in areas with large AC voltage fluctuation ranges.

The wide AC input range switching power supply of the utility model is an improved product based on the half-bridge switching power supply circuit, which can meet the use requirements of the computer. It includes: bidirectional filter circuit, full-bridge rectifier circuit, main circuit including DC filter, half-bridge switch and switching transformer, auxiliary power supply, control circuit connected to the drive circuit, drive circuit, rectification filter connected to the output end of the main circuit and The DC output circuit is connected to the feedback circuit and the comparison circuit between the DC output circuit and the control circuit;

It is characterized in that: a pulse width control voltage compensation circuit is connected between the full-bridge rectifier circuit and the voltage-dividing DC filter circuit, and the pulse width control voltage compensation circuit is alternately triggered to work by two compensation control coils of the drive transformer of the drive circuit to Compensates for excessive reduction in AC input voltage.

The accompanying drawings of the utility model are as follows:

Figure 1 is a schematic block diagram of the switching power supply;

Fig. 2 is the schematic diagram of its main circuit;

Fig. 3 is the schematic diagram of its pulse width control voltage compensation circuit;

Fig. 4 is the schematic diagram of its driving circuit;

Fig. 5 is its driving control circuit principle diagram;

The functional block diagram of the switching power supply shown in FIG. 1 is as described above, and will not be repeated here.

The basic principle of the main circuit in normal operation is shown in Figure 2. The drive circuit is excited by the pulse transformer, and two pulse currents with opposite polarities are generated in the two secondary coils. When Q1 is turned on and Q2 is turned off, the current flows from V+, Q1, and T2 Then flows through T1 to charge C6 and C2, and the pulse current flowing through the switching transformer causes T1 to generate electromagnetic conversion and magnetoelectric conversion; when the driving conversion is completed, Q1 is cut off, and after Q2 is turned on, C6 starts to discharge, and the current flows from C6, T1, T2 and Q2 flow to the ground. After the switching transformer T1 is electromagnetically converted and coupled, it outputs a DC voltage for use by the computer. The primary pole of the driving transformer T2 is connected to the driving circuit, and the secondary is the switching circuit. The capacitor C6 here is 1μF/250V, while the conventional circuit Take 0.68μf/250V.

The basic principle of the pulse width control voltage compensation circuit is shown in Figure 3.

The pulse width control voltage type compensation circuit includes: triodes (Q9, Q10, Q15, Q16), compensation control coils (n, n') on the secondary side of the drive transformer T2, connected to the emitter of the triode Q9 and two filter capacitors (C1, C2 ), the diode D21 between the common point G of the triode Q9, the diode D15, the resistor R20 and the coil n series branch connected between the base of the triode Q9 and the G point, and the series branch connected between the base of the triode Q15 and the emitter D19, resistor R20' and coil n' are connected in series, the collector of triode Q15 is connected to the G point mentioned above, the collector of transistor Q9 is connected to the input terminal B of the full bridge, and the emitter of the triode Q15 is connected to terminal B of the full bridge input through the diode D20; the triode The collector of Q10 is connected to the base of transistor Q9, its emitter is connected in series with the voltage regulator tube and the resistor is grounded, and its base is connected to the voltage dividing end of the voltage dividing resistor; the collector of transistor Q16 is connected to the base of transistor Q15, its emitter is grounded, and its base The pole is connected to the other voltage dividing end of the voltage dividing resistor.

When the input voltage is higher than 170V, Q10 and Q16 are turned on and Q9 and Q15 are turned off under the voltage dividing resistor, the compensation circuit does not work, and the whole circuit works within the normal range. When the input circuit voltage is lower than 170V, Q10 and Q16 are cut off, and Q9 and Q15 can be turned on under the action of the two compensation control coils of the drive transformer T2 of the drive circuit. The width of the pulse current sent to the drive triode decreases with the decrease of the input AC voltage and the decrease of the output DC voltage, and the pulse width of the drive current increases again. The widest time can reach 20μs. T2 is the drive transformer, and n and n' are two Compensation control coil.

After the compensation circuit is started, the positive half cycle of AC flows in from the full bridge B, driven by the pulse current, the pulse current flows through Q9 to charge C2, and the current flows through Q9, D21, C2 and returns to the full bridge A to form a circuit to complete the half cycle charging, so that C2 The voltage on C1 is increased. When A is a positive half cycle, the current is rectified to charge C1, and the current flows to B through C1, Q15, D20, so that the voltage of C1 is increased. The increased voltage range is determined by the pulse width. When the voltage is increased, the switch main The loop efficiency is increased, the output DC voltage is increased, the power supply is stabilized, and the pulse width is also appropriately reduced. If the compensation voltage is too high or the input AC is increased too fast, the base voltage of Q10 and Q16 will immediately increase, and Q10 and Q16 will be turned on. Make Q9, Q15 locked, and the compensation circuit stops working.

This switching power supply uses the traditional drive circuit shown in Figure 4. It is mainly composed of a driving transformer T2, transistors Q3 and Q4, several diodes, resistors and capacitors. The collectors of the transistors Q3 and Q4 are respectively connected to the two ends of the primary side of the driving transformer T2. The bases of the transistors Q3 and Q4 are respectively as shown in Figure 5. The two output ends of the drive control circuit are connected.

Figure 5 is a schematic diagram of its drive control circuit. The commonly used TL494CN integrated circuit is used, which is composed of a sawtooth wave generating circuit, a linear comparison circuit, a pulse width control circuit, and a reference voltage. Pins 5 and 6 determine the oscillation frequency, which is related to the maximum width of the voltage adjustment range. At this point, the capacitor selection 103. Due to the large input range of the switching power supply, parameter design is the key to the circuit. It is more appropriate to choose 28K oscillation frequency. The voltage at pin 2 is set to 4.65V, and the voltage at pin 1 is composed of a sampling resistor circuit at 4.65V. In addition, the entire circuit The most important thing is that the current pin 4 is the dead zone control voltage, which determines the width of the output pulse. When +12V or +5V decreases, the output voltage of the comparator decreases, and the output pulse width increases when the voltage of pin 3 decreases.

The basic working principle is as follows. When the AC power is plugged into the socket, the auxiliary power supply starts to work, and the voltage is sent to pin 12, and pin 14 outputs a reference 5V voltage, which is used as a reference for circuit parameter distribution. At this time, because the PS-ON circuit is not working, it is in the initial stage. Position, pin 4 is high level, when PS-ON is connected, it is processed by the circuit, and then sent to the low level of pin 4, the pulse circuit starts to output, and generates two pulses with opposite polarities and adjustable width. Output from pin 8 and pin 11 to the corresponding input end of the drive circuit. The principle of TL494CN integrated circuit can refer to the relevant circuit manual.

The utility model has the following advantages:

The wide-range power supply technology of the utility model is novel in conception, and a pulse width control voltage compensation circuit is connected between the full-bridge rectifier circuit and the voltage-dividing DC filter circuit, and the pulse width control voltage compensation circuit is formed by the drive transformer of the drive circuit The two compensation control coils are triggered alternately to compensate for the excessive reduction of the AC input voltage, so that the input AC voltage of the switching power supply is greatly widened, and the input AC voltage can reach 120-260 volts, ensuring that the computer can operate under harsh AC voltage environments. Normal use.

The switching power supply is especially suitable for use as a power supply part of a computer and for producing computers with a wide AC input voltage range. The switching power supply can also be used in other electronic equipment, electronic instruments and the like.

Claims (2)

1, a kind of wide interchange input range Switching Power Supply that is used for computing machine, it comprises: the bidirectional filtering circuit, full bridge rectifier, the major loop that contains DC filtering, half-bridge switch and switch transformer, accessory power supply, the control circuit that is connected with driving circuit, driving circuit, be connected in the rectifying and wave-filtering and the dc output circuit of major loop output terminal, be connected in feedback circuit and comparator circuit between dc output circuit and the control circuit;

It is characterized in that: be connected with the pulse-width controlled voltage compensating circuit between full bridge rectifier and partial pressure type DC filtering circuit, the pulse-width controlled voltage compensating circuit replaces triggering work by two compensation control coils of the driving transformer of driving circuit.

2, wide interchange input range Switching Power Supply according to claim 1, it is characterized in that described pulse-width controlled voltage compensating circuit comprises: triode (Q9, Q10, Q15, Q16), compensation control coil (the n of driving transformer (T2) secondary, n '), be connected in triode (Q9) emitter and two filter capacitor (C1, C2) diode (D21) between the common point (G), the diode (D15) of cross-over connection between triode (Q9) base stage and described G point, resistance (R20) and coil (n) series arm, be connected in (D19) between triode (Q15) base stage and the emitter, resistance (R20,) and coil (n ') series arm, triode (Q15) collector connects described G point, triode (Q9) collector connects full-bridge input B end, and triode (Q15) emitter connects full-bridge input B end by diode (D20); Collector connecting transistor (Q9) base stage of triode (Q10), its emitter series connection stabilivolt and resistance eutral grounding, its base stage connects the branch pressure side of divider resistance; Triode (Q16) collector connecting transistor (Q15) base stage, its grounded emitter, its base stage connects another minute pressure side of divider resistance.

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