CN202957750U - Power supply circuit for improving load capacity of two-wire meter - Google Patents

Abstract

The utility model relates to a power supply circuit for improving the load capacity of a two-wire meter. An oscillating circuit composed of an oscillating transformer, a transistor Q2, a transistor Q3, a resistor R2 and a resistor R3 is connected with a return circuit of a power unit in series. When the power supply is on, the circuits have working voltage and start the continuous oscillation due to the existing of a voltage regulating diode Z1, AC (alternating current) voltage is generated by the secondary level of the oscillation transformer, the AC voltage is rectified to unstable DC (direct current) voltage by a rectifier bridge which is formed by low drop-out fast rectifier diodes D1-D4, the unstable DC voltage is changed to stable DC voltage through filtering of a capacitor C1 and a voltage regulator IC1, and the stable DC voltage supplies power to a sensor equivalent load RX through a low drop-out diode D5. The voltage obtained by a primary isolating and the second isolating of the oscillating transformer can be used in parallel with the voltage of the power unit, and the input power of the sensor equivalent load RX is improved without increasing the return circuit current, so that the power supply circuit for improving the load capacity of the two-wire meter is obtained. The power supply circuit for improving the load capacity of the two-wire meter has the advantage of ensuring the precision and accuracy of the meter measurement.

Description

A kind of power circuit that improves two-wire system instrument load capacity

Technical field

The utility model relates to a kind of power circuit that improves two-wire system instrument load capacity in instrument and meter for automation field.

Background technology

In current instrument and meter for automation, use the mode of connection of two-wire system very many, its operation principle is that control system provides power supply by two power lines for instrument, instrument changes between 4mA-20mA according to the circuit of the big or small control loop of sensor measurement physical quantity, the power supply of whole like this instrument is restricted, especially when loop current is 4mA, the power of outside input is little, load capacity is poor, directly result is that its power unit load capacity is low, when the Sensor section power consumption is larger, can't work.

Summary of the invention

In view of the deficiency that prior art exists, the utility model provides a kind of power circuit that improves two-wire system instrument load capacity, can well solve the existing problem of current two line gauge sensor power supply circuits.

The utility model to achieve these goals, the technical scheme adopted is: a kind of power circuit that improves two-wire system instrument load capacity, comprise power subsystem and transducer equivalence load RX, it is characterized in that: also comprise oscillation transformer TRAN, triode Q2, triode Q3, voltage stabilizing didoe Z1, low voltage difference fast recovery rectifier diode D1-D4, pressurizer IC1, low voltage difference diode D5, low voltage difference diode D6, 1 pin of described oscillation transformer TRAN primary coil connects the collector electrode of triode Q2, one end of resistance R 2, 3 pin of oscillation transformer TRAN primary coil connect the collector electrode of triode Q3, one end of resistance R 3, the base stage of another termination triode Q2 of resistance R 2, the base stage of another termination triode Q3 of resistance R 3, triode Q2, the emitter of triode Q3 is connected and connects the positive pole of voltage stabilizing didoe Z1 and the drain electrode of described power subsystem N channel depletion type field effect transistor, 3 pin of oscillation transformer TRAN primary coil meet negative pole and the external dc power V+ of voltage stabilizing didoe Z1, 4 pin of oscillation transformer TRAN secondary coil and 5 pin connect the ac input end of the rectifier bridge of low voltage difference fast recovery rectifier diode D1-D4 composition, the DC output end of the rectifier bridge that low voltage difference fast recovery rectifier diode D1-D4 forms is in parallel with capacitor C 1, 1 pin of pressurizer IC1 connects the negative pole of capacitor C 1, an end and the ground of transducer equivalence load RX, 2 pin of pressurizer IC1 connect the positive pole of capacitor C 1, 3 pin of pressurizer IC1 connect the other end of transducer equivalence load RX by low voltage difference diode D5.

The beneficial effects of the utility model are: the electric energy that whole instrument is obtained by loop increases, and the stability of instrument can well be provided, the accuracy of effective guarantee instrument measurement and accuracy, and due to the increase of Sensor section power supply capacity, antijamming capability strengthens.

Fig. 1 is circuit theory diagrams of the present utility model.

Embodiment

As shown in Figure 1, improve the power circuit of two-wire system instrument load capacity, comprise power subsystem and transducer equivalence load RX, also comprise oscillation transformer TRAN, triode Q2, triode Q3, voltage stabilizing didoe Z1, low voltage difference fast recovery rectifier diode D1-D4, pressurizer IC1, low voltage difference diode D5, low voltage difference diode D6, 1 pin of oscillation transformer TRAN primary coil connects the collector electrode of triode Q2, one end of resistance R 2, 3 pin of switch transformer TRAN primary coil connect the collector electrode of triode Q3, one end of resistance R 3, the base stage of another termination triode Q2 of resistance R 2, the base stage of another termination triode Q3 of resistance R 3, triode Q2, the emitter of triode Q3 is connected and connects the positive pole of voltage stabilizing didoe Z1 and the drain electrode of described power subsystem N channel depletion type field effect transistor, 3 pin of oscillation transformer TRAN primary coil meet negative pole and the external dc power V+ of voltage stabilizing didoe Z1, 4 pin of switch transformer TRAN secondary coil and 5 pin connect the ac input end of the rectifier bridge of low voltage difference fast recovery rectifier diode D1-D4 composition, the DC output end of the rectifier bridge that low voltage difference fast recovery rectifier diode D1-D4 forms is in parallel with capacitor C 1, 1 pin of pressurizer IC1 connects the negative pole of capacitor C 1, an end and the ground of transducer equivalence load RX, 2 pin of pressurizer IC1 connect the positive pole of capacitor C 1, 3 pin of pressurizer IC1 connect the other end of transducer equivalence load RX by low voltage difference diode D5.

Improve the implementation method of the power circuit of two-wire system instrument load capacity, connected in the loop of power subsystem and comprised oscillation transformer TRAN, triode Q2, triode Q3, resistance R 2, the oscillating circuit that resistance R 3 forms, switch on power, existence due to voltage stabilizing didoe Z1, circuit has possessed operating voltage, start continuous oscillation, at the secondary generation alternating voltage of oscillation transformer, become unstable direct current through the rectifier bridge rectification that low voltage difference fast recovery rectifier diode D1-D4 forms, through capacitor C 1 filtering, pressurizer IC1, become stable DC voltage, through low voltage difference diode D5, it is transducer equivalence load RX power supply, elementary due to oscillation transformer TRAN, the voltage that secondary isolation obtains, can use with the voltage parallel of power subsystem, under the prerequisite of the electric current that does not increase loop, improve the input power of transducer equivalence load RX, become the power circuit that whole instrument improves load capacity.

Foregoing circuit V+ is connected external dc power with V-, and voltage range can 24V-36V; The part of dotted line be current two-wire system instrument typical circuit be power subsystem, U1 is that the CPU of two-wire system instrument is responsible for image data, controls according to the size of collection signal the electric current that current controller U2 regulates current loop and changes between 4mA-20mA.Existing power subsystem connected mode, VDD is 3.3V, and the operating current of 4mA can be provided for whole instrument, and wherein a part is consumed by U1 and auxiliary circuit thereof, and a part provides electric current by diode D6 for transducer equivalence load.

Claims (1)

1. a power circuit that improves two-wire system instrument load capacity, comprise power subsystem and transducer equivalence load RX, it is characterized in that: also comprise oscillation transformer TRAN, triode Q2, triode Q3, voltage stabilizing didoe Z1, low voltage difference fast recovery rectifier diode D1-D4, pressurizer IC1, low voltage difference diode D5, low voltage difference diode D6, 1 pin of described oscillation transformer TRAN primary coil connects the collector electrode of triode Q2, one end of resistance R 2, 3 pin of oscillation transformer TRAN primary coil connect the collector electrode of triode Q3, one end of resistance R 3, the base stage of another termination triode Q2 of resistance R 2, the base stage of another termination triode Q3 of resistance R 3, triode Q2, the emitter of triode Q3 is connected and connects the positive pole of voltage stabilizing didoe Z1 and the drain electrode of described power subsystem N channel depletion type field effect transistor Q1, 3 pin of oscillation transformer TRAN primary coil meet negative pole and the external dc power V+ of voltage stabilizing didoe Z1, 4 pin of oscillation transformer TRAN secondary coil and 5 pin connect the ac input end of the rectifier bridge of low voltage difference fast recovery rectifier diode D1-D4 composition, the DC output end of the rectifier bridge that low voltage difference fast recovery rectifier diode D1-D4 forms is in parallel with capacitor C 1, 1 pin of pressurizer IC1 connects the negative pole of capacitor C 1, an end and the ground of transducer equivalence load RX, 2 pin of pressurizer IC1 connect the positive pole of capacitor C 1, 3 pin of pressurizer IC1 connect the other end of transducer equivalence load RX by low voltage difference diode D5.

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