CN103997203B - The power circuit of distribution net equipment temperature rise monitoring device - Google Patents

Abstract

The invention discloses a power supply circuit of a temperature rise monitoring device for distribution network equipment, which includes an input circuit and an output circuit; the input circuit includes an overcurrent protection circuit and a filter energy storage circuit; the overcurrent protection circuit is in phase with the plug joint J2 connected, and connected to an external power supply through the plug connector J2; the output circuit includes a step-down circuit, a voltage stabilizing filter circuit, feedback resistors R4~R6, and an energy storage inductor L2; the feedback resistors R4~R6, and energy storage inductor L2 are connected to Between the step-down circuit and the voltage stabilizing filter circuit. The power supply circuit of the temperature rise monitoring device for distribution network equipment of the present invention has the advantages of high power supply reliability, low power consumption, strong anti-interference ability, and the like.

Description

Power supply circuit of temperature rise monitoring device for distribution network equipment

technical field

The invention relates to a power supply circuit of a temperature rise monitoring device for distribution network equipment.

Background technique

The power distribution equipment of the power system is generally composed of circuit breakers, ring network cabinets, cables, bus bars, switch cabinets and other electrical equipment. They are connected with each other by busbars, leads, cables, etc. Since the current flows to generate heat, almost all electrical faults will lead to changes in the temperature of the fault point. The monitoring of the temperature can realize the real-time alarm for the abnormality of the power equipment such as high temperature and rapid heating, and can detect and deal with the phenomenon of equipment overheating in time, avoid serious equipment accidents caused by ablation, and help to quickly locate hidden dangers of equipment and prevent accidents. To prevent problems before they happen. At the same time, it provides an important evaluation basis for the realization of equipment condition maintenance, reduces the working pressure of front-line production personnel to collect equipment status, has great advantages in realizing efficiency and intelligent analysis level, and transforms distribution network equipment maintenance from regular maintenance to status Overhaul shift.

The temperature rise monitoring device of distribution network equipment generally uses solar panel battery packs or energy-taking CTs to obtain electricity, and selects the appropriate power supply mode according to different application sites. In outdoor or outdoor sunny distribution network equipment, solar panel battery packs are generally used. Way. It is more convenient to use CT energy harvesting at urban backbone network nodes or places with large load currents. The two methods are generally output with voltage DC 12V and current 500-1500mA, and the output power is small. Since the temperature rise monitoring device works continuously for a long time, in order to ensure the reliability of the system, the power supply circuit of the distribution network equipment temperature rise monitoring device should be converted Efficiency and low power consumption are particularly important.

The power supply equipment of the temperature rise monitoring device of the distribution network equipment has the characteristic of trickle continuous power supply, and most of them have poor ability to provide high power. Therefore, it is required that the design efficiency of the power supply in the temperature rise monitoring device is as high as possible, and it has the ability of over-current protection and short-circuit protection, and reduces the probability of burning out the device. The input of the power circuit is connected to the output of the power supply device.

Fig. 2 is a power supply circuit of a distribution network equipment temperature rise monitoring device implemented in the prior art. J1 is the power socket, the self-recovery fuse PTC1 and TVS-D2 cooperate to prevent overcurrent and pulse voltage, C1 and C3 are filter capacitors, U1 is a voltage converter that converts DC 12V to DC 5V, and provides power for the subsequent loads, C2 C4 and C4 are low-voltage filter capacitors, and C5 is an energy storage capacitor to realize the instantaneous power consumption of the subsequent load or the sending signal module.

The main problem existing in the prior art is that the circuit design has low power conversion efficiency and low power consumption, especially when it is difficult to obtain energy, a lot of energy is wasted. For example: when the circuit load is 500mA, the input voltage of the circuit is 12V, the current is 500mA, the output voltage is 5V, and the current is 500mA, then the power consumption is 3.5W, and the conversion efficiency is only 41.67%. And when the latter stage requires instantaneous high power, the power converter U1 cannot provide the limited power provided only by the energy storage of the capacitor C5. Therefore, the circuit in Fig. 1 has problems such as high power consumption and poor reliability.

Contents of the invention

The present invention aims to avoid the shortcomings in the above-mentioned prior art, and provides a power supply circuit of a temperature rise monitoring device for distribution network equipment, so as to reduce power consumption, improve power supply reliability and anti-interference ability.

The present invention adopts the following technical solutions to solve the technical problems.

The power supply circuit of the temperature rise monitoring device for distribution network equipment has the following structural characteristics: it includes an input circuit and an output circuit; the input circuit includes an overcurrent protection circuit and a filter energy storage circuit; the overcurrent protection circuit is connected to the plug connector J2 , and connect to an external power supply through the plug connector J2; the output circuit includes a step-down circuit, a voltage stabilization filter circuit, feedback resistors R4~R6, and an energy storage inductor L2; the feedback resistors R4~R6 and energy storage inductor L2 are connected to the Between the step-down circuit and the voltage regulator filter circuit.

The structural features of the power supply circuit of the distribution network equipment temperature rise monitoring device of the present invention also lie in:

The overcurrent protection circuit includes a resettable fuse PTC2 and a TVS tube D3; one end of the resettable fuse PTC2 is connected to a terminal of the plug joint J2, and the other end of the resettable fuse PTC2 is connected to the TVS tube D3. The negative pole of D3 is connected, and the positive pole of the TVS tube D3 is connected with the other terminal of the plug joint J2.

The filter energy storage circuit includes aluminum electrolytic capacitors C7-C8, inductor L1, and non-polar ceramic capacitors C9-C10; the positive pole of the aluminum electrolytic capacitor C7 is connected to one end of the inductor L1, and the other end of the aluminum electrolytic capacitor C7 is connected to The anode of the TVS tube D3 is connected and grounded; one end of the aluminum electrolytic capacitor C8, the non-polar ceramic capacitor C9, and C10 connected in parallel is connected to the other end of the inductor L1, and is also connected to the other end of the inductance L1. The step-down circuits of the output circuits are connected; the other ends of the aluminum electrolytic capacitor C8 and the non-polar ceramic capacitors C9 and C10 are connected in parallel to ground.

The step-down circuit includes a power converter U2, a bootstrap capacitor C6 and a Schottky diode D4; the power converter U2 is connected to the filter energy storage circuit of the input circuit; the Schottky diode D4 passes through the The bootstrap capacitor C6 is connected to the power converter U2;

The voltage stabilizing filter circuit includes aluminum electrolytic capacitors C11, C12 and non-polar ceramic capacitors C13; one end of the aluminum electrolytic capacitors C11, C12 and non-polar ceramic capacitors C13 is connected in parallel through the energy storage inductance L2 and The power converter U2 is connected, the other end of the parallel connection between the aluminum electrolytic capacitors C11, C12 and the non-polar ceramic capacitor C13 is connected to one end of the feedback resistor R4, and the other end of the feedback resistor R4 It is connected with the power converter U2 through the feedback resistor R6 and the feedback resistor R5 in turn.

Compared with the prior art, the beneficial effects of the present invention are reflected in:

The power supply circuit of the distribution network equipment temperature rise monitoring device of the present invention, its input circuit includes components such as self-recovery fuse PTC2, voltage regulator tube D3, energy storage capacitor C7, C8, filter inductor L1, filter capacitor C9, C10, and its output The circuit includes inductor L2, capacitors C6, C11, C12, C13, resistors R4, R5, R6, DC/DC power converter U2, Schottky diode D4 and other components.

In the design of the input stage of the power supply circuit of the present invention, protection measures are adopted, which can effectively prevent problems such as short circuit and overcurrent of the circuit input, and according to the characteristics of the power supply equipment, an energy storage capacitor is used in front of the power converter U2 to ensure that U2 The instantaneous power supply is stable, the output stage uses filter capacitors to effectively ensure the quality of power ripple, and uses Schottky diodes to cooperate with power converter U2 to effectively improve the conversion efficiency. Such a power supply circuit design makes the power consumption lower and the instantaneous power more reliable, which effectively solves the shortcomings of the prior art.

The power supply circuit of the distribution network equipment temperature rise monitoring device of the present invention is especially suitable for distributed distribution network equipment temperature rise monitoring devices that require wireless transmission, and realizes the power supply design of the distribution network equipment temperature rise monitoring device with a low power consumption and high efficiency power supply circuit ; Increase the safety protection circuit to realize the safety performance of the temperature rise monitoring device, which has the advantages of high power supply reliability, low power consumption, and strong anti-interference ability.

Description of drawings

FIG. 1 is a schematic diagram of a power supply circuit of a temperature rise monitoring device for distribution network equipment according to the present invention.

Fig. 2 is a schematic diagram of a power supply circuit of a temperature rise monitoring device for distribution network equipment in the prior art.

The present invention will be further described below through specific embodiments and in conjunction with the accompanying drawings.

detailed description

Referring to Figure 1, the power supply circuit of the distribution network equipment temperature rise monitoring device includes an input circuit and an output circuit; the input circuit includes an overcurrent protection circuit and a filter energy storage circuit; the overcurrent protection circuit is connected to the plug connector J2 , and connect to an external power supply through the plug connector J2; the output circuit includes a step-down circuit, a voltage stabilization filter circuit, feedback resistors R4~R6, and an energy storage inductor L2; the feedback resistors R4~R6 and energy storage inductor L2 are connected to the Between the step-down circuit and the voltage regulator filter circuit.

The overcurrent protection circuit includes a resettable fuse PTC2 and a TVS tube D3; one end of the resettable fuse PTC2 is connected to a terminal of the plug joint J2, and the other end of the resettable fuse PTC2 is connected to the TVS tube D3. The negative pole of D3 is connected, and the positive pole of the TVS tube D3 is connected with the other terminal of the plug joint J2.

The filter energy storage circuit includes aluminum electrolytic capacitors C7-C8, inductor L1, and non-polar ceramic capacitors C9-C10; the positive pole of the aluminum electrolytic capacitor C7 is connected to one end of the inductor L1, and the other end of the aluminum electrolytic capacitor C7 is connected to The anode of the TVS tube D3 is connected and grounded; one end of the aluminum electrolytic capacitor C8, the non-polar ceramic capacitor C9, and C10 connected in parallel is connected to the other end of the inductor L1, and is also connected to the other end of the inductance L1. The step-down circuits of the output circuits are connected; the other ends of the aluminum electrolytic capacitor C8 and the non-polar ceramic capacitors C9 and C10 are connected in parallel to ground.

The step-down circuit includes a power converter U2, a bootstrap capacitor C6 and a Schottky diode D4; the power converter U2 is connected to the filter energy storage circuit of the input circuit; the Schottky diode D4 passes through the The bootstrap capacitor C6 is connected to the power converter U2;

The voltage stabilizing filter circuit includes aluminum electrolytic capacitors C11, C12 and non-polar ceramic capacitors C13; one end of the aluminum electrolytic capacitors C11, C12 and non-polar ceramic capacitors C13 is connected in parallel through the energy storage inductance L2 and The power converter U2 is connected, the other end of the parallel connection between the aluminum electrolytic capacitors C11, C12 and the non-polar ceramic capacitor C13 is connected to one end of the feedback resistor R4, and the other end of the feedback resistor R4 It is connected with the power converter U2 through the feedback resistor R6 and the feedback resistor R5 in turn.

Referring to Fig. 1, the power supply circuit of the temperature rise monitoring device for distribution network equipment of the present invention is composed of an input circuit and an output circuit. The input circuit includes an overcurrent protection circuit and a filter energy storage circuit; the output circuit includes a DC/DC power converter U2, a feedback resistor, and a filter voltage stabilization circuit.

The overcurrent protection circuit is composed of a self-recovery fuse PTC2 and a TVS tube D3-SMCJ40A; the reverse end of D3 is connected to one end of PTC2, and PTC2 can effectively prevent excessive current and allow a large overcurrent to pass, but the reaction of PTC2 The time is at the ms level, and the response time is slightly longer. TVS (Transient Voltage Suppressor, Transient Voltage Suppressor) tube D3 has the function of overvoltage and overcurrent protection, and the response time is only ns level, but the current allowed to pass is lower than that of PTC2. The two can be seamlessly combined to reliably prevent the circuit from malfunctioning. Faults such as overload and short circuit.

The filter energy storage circuit is composed of an aluminum electrolytic capacitor C7, an inductor L1, an aluminum electrolytic capacitor C8, and non-polar ceramic capacitors C9 and C10. Due to the characteristics of the power supply equipment, large-capacity aluminum electrolytic capacitors C7 and C8 are used as energy storage capacitors in front of the power converter, which can greatly improve the stability of the power converter. Since the input stage of the power supply equipment has a long line and the ripple of the input voltage is relatively large, it is necessary to use non-polar ceramic capacitors C9 and C10 for filter design. C9 is 100nf to filter low-frequency ripple, and C10 is 10nf to filter high-frequency ripple.

Referring to Fig. 1, the input circuit includes a protection circuit, a filter energy storage circuit and other parts. The power interface J2-2 (terminal 2 on J2) inputs DC12V and connects to one end of PTC2. Connect the negative pole of C7 to the GND of the power supply equipment, L1 to DC-12V, the other end of L1 to the positive pole of the energy storage capacitor C8, and the negative pole of C8 to GND with one end of the filter capacitors C9 and C10. Its other end is connected to the VIN pin of the power converter U2, so that the input power can be stably input at 12V reliably.

The output circuit is composed of a step-down circuit and a voltage stabilizing filter circuit. The power converter U2 has excellent linearity and load regulation characteristics. Higher efficiency is achieved by using a low on-resistance N-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor). The application uses a Schottky reflux diode. For the application of U2 in high input voltage and low output voltage applications, the nearly ideal reverse recovery characteristics and low forward voltage drop of Schottky diode D4 are particularly important diode characteristics. Its reverse recovery characteristic determines the duration of the current surge when the N-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor) is turned on in each cycle. When D4 is used, the corresponding switching losses are greatly reduced.

The bootstrap capacitor C6 between the BOOST and SW pins of U2 in the step-down circuit provides the gate current to turn on the internal N-channel MOSFET of U2. The capacitance of this capacitor should be 10nF, and a high-quality, low-ESR ceramic capacitor should be selected. A small resistor in series with the bootstrap capacitor can be used to extend the turn-on transition time of the internal N-channel MOSFET. A 10 to 50Ω resistor can be used to extend the transition time. This helps reduce electromagnetic interference on switched power circuits.

The voltage stabilizing filter circuit is composed of aluminum electrolytic capacitors C11, C12 and non-polar C13. The 470uf C11 and C12 can effectively filter the switching noise and low frequency ripple of the power supply. The non-polar C13 is 100nf, which can effectively filter out high-frequency ripples, and the effect of paralleling the three is better.

Referring to Figure 1, the bootstrap capacitor C6 is connected to one end of the energy storage inductor L2 and the inverting end of the Schottky diode D4, the positive end of D4 is connected to GND, the other end of L2 is connected to one end of filter C11, C12 and C13, the other end is connected to GND, and the feedback resistor R4, R5, R6 are connected to pin 4 and pin 8 of U2 and connected to GND. This power supply circuit converts DC12V into VCC5 efficiently through DC conversion, and its efficiency is increased to about 90% through Schottky diode D4, which greatly reduces its power consumption. Experiments have proved that when the load is in the same condition as shown in Figure 1, the input voltage 12V, input current 228.5mA, output voltage 5V, output current 500mA, power consumption 0.25W, efficiency 91.16%, compared with the circuit in Figure 1, the efficiency is 49.49%. And through the pre-stage energy storage circuit, the instantaneous power supply capability is strengthened, which significantly increases the reliability of the circuit.

Although the present invention has been described above based on preferred embodiments, this does not mean that the scope of the present invention is limited to the above structures, as long as the structures covered by the claims of the present invention are within the scope of protection. Those skilled in the art can easily develop equivalent replacement structures after reading the above descriptions, and all equivalent changes and modifications made without departing from the spirit and scope of the present invention should be covered by the protection scope of the present invention Inside.

Claims (1)

1. The power supply circuit of the temperature rise monitoring device of the distribution network equipment is characterized by comprising an input circuit and an output circuit; the input circuit comprises an overcurrent protection circuit and a filtering energy storage circuit; the overcurrent protection circuit is connected with the plug connector J2 and is connected with an external power supply through the plug connector J2; the output circuit comprises a voltage reduction circuit, a voltage stabilization filter circuit, feedback resistors R4-R6 and an energy storage inductor L2; the feedback resistors R4-R6 and the energy storage inductor L2 are connected between the voltage reduction circuit and the voltage stabilization filter circuit;

the overcurrent protection circuit comprises a self-recovery fuse PTC2 and a TVS tube D3;

the filtering energy storage circuit comprises aluminum electrolytic capacitors C7 and C8, an inductor L1, and non-polar ceramic chip capacitors C9 and C10;

the voltage reduction circuit comprises a power converter U2, a bootstrap capacitor C6 and a Schottky diode D4;

the voltage-stabilizing filter circuit comprises aluminum electrolytic capacitors C11 and C12 and a non-polar ceramic chip capacitor C13;

wherein,

in the overcurrent protection circuit, a terminal J2-2 on a plug J2 is connected with one end of a self-recovery fuse PTC2, the other end of the self-recovery fuse PTC2 is connected with the reverse end of a TVS tube D3 and the anode of a capacitor C7, a terminal J2-1 on a plug J2, the forward end of the TVS tube D3 and the cathode of an aluminum electrolytic capacitor C7 are connected with GND, and one end of an inductor L1 is connected with the anode of a direct-current 12V power supply and the anode of a capacitor C7;

in the filtering energy storage circuit, the other end of an inductor L1 is connected with the anode of an aluminum electrolytic capacitor C8, the cathode of the aluminum electrolytic capacitor C8 and one ends of a nonpolar ceramic chip capacitor C9 and C10 are connected with GND, and the anode of the aluminum electrolytic capacitor C8 and the other ends of the nonpolar ceramic chip capacitors C9 and C10 are connected with a VIN pin of a power converter U2;

in the voltage reduction circuit, the power converter U2 is connected with a filtering energy storage circuit of the input circuit; the cathode of the Schottky diode D4 is connected with the BOOST pin of the power converter U2 through the bootstrap capacitor C6; the cathode of the Schottky diode D4 is simultaneously connected with the SW pin of the power converter U2; power converter U2 has an N-channel MOSFET with low on-resistance; the bootstrap capacitor C6 between the BOOST pin and the SW pin of the power converter U2 provides the gate current for turning on the internal N-channel MOSFET of the power converter U2;

in the voltage stabilizing filter circuit, two parallelly connected ends of the aluminum electrolytic capacitors C11 and C12 and the nonpolar ceramic chip capacitor C13 are connected with a SW pin of the power converter U2 through an energy storage inductor L2, two parallelly connected ends of the aluminum electrolytic capacitors C11 and C12 and the nonpolar ceramic chip capacitor C13 are connected with one end of a feedback resistor R4, and the other end of the feedback resistor R4 is connected with a TPAD pin and a GND pin of the power converter U2 sequentially through the feedback resistor R6 and a feedback resistor R5.