Power supply circuit based on power transformer
Through the power transformer-based power circuit design, the problem of smart meter not being able to work normally when the neutral line is disconnected is solved, and the normal operation and service life of the system are achieved in a short period of time.
Patent Information
- Application Number
- CN202421258869.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-04
- Publication Date
- 2025-03-25
- Estimated Expiration
- 2034-06-04
AI Technical Summary
When the smart meter is off-line (no voltage is applied but current is passed), it cannot work normally and the current volume cannot be detected.
A power circuit based on a power transformer is designed to induce the AC voltage through the power transformer and power the system through rectification, filtering, and bucking operations.
When the smart meter is in a neutral line state, it can maintain the normal operation of the system in a short time and extend the service life of each component of the system. The circuit principle is simple, low-cost, high sensitivity, and has strong adaptability and practicality.
Smart Images
Figure CN222674159U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of power supply circuits for electric meters, in particular to a power supply circuit based on a power transformer. Background Art
[0002] With the continuous development and popularization of smart meters overseas, such phenomena as power theft and leakage have occurred repeatedly. When the smart meter is in the broken neutral state, that is, no voltage is applied but current flows, the smart meter often has no power supply, causing the metering function to fail to work normally and unable to detect the current normally. Utility Model Content
[0003] The utility model aims to solve the above problems and provides a power supply circuit based on a power transformer, and the technical solution adopted is as follows:
[0004] A power supply circuit based on a power transformer comprises a power transformer, a rectifier bridge DP1, a first resistor RP1, a voltage regulator diode D2, a first capacitor CP1, a second capacitor CP2, a linear voltage regulator UP1 and a rectifier diode DP2, wherein an input end JM1 of the power transformer is connected to an input end of the rectifier bridge DP1, an output positive electrode of the rectifier bridge DP1 is connected to one end of the first resistor RP1, an output negative electrode of the rectifier bridge DP1 is grounded, the other end of the first resistor RP1 is connected to the negative electrode of the voltage regulator diode D2, the positive electrode of the voltage regulator diode D2 is grounded, one end of the first capacitor CP1 is connected to the positive electrode of the voltage regulator diode D2, and the other end is grounded, a connection end of the first capacitor CP1 and the voltage regulator diode D2 is connected to an input end of the linear voltage regulator UP1, a ground end of the linear voltage regulator UP1 is grounded, an output end of the linear voltage regulator UP1 is connected to one end of the second capacitor CP2 and the positive electrode of the rectifier diode DP2, the other end of the second capacitor CP2 is grounded, and a negative electrode of the rectifier diode DP2 is connected to an electric meter power supply MVDD.
[0005] On the basis of the above solution, a second resistor RP2 is further included. The second resistor RP2 is a winding resistor, and the second resistor RP2 is connected in parallel with the first resistor RP1.
[0006] Based on the above solution, the power of the second resistor RP2 is 3W.
[0007] Preferably, an electrolytic capacitor E1 is further included, wherein the electrolytic capacitor E1 is connected in parallel with the voltage stabilizing diode D2, and the positive electrode of the electrolytic capacitor E1 is connected to the negative electrode of the voltage stabilizing diode D2.
[0008] Preferably, the power of the voltage stabilizing diode D2 is 5W.
[0009] Preferably, the first resistor RP1 is a chip resistor, and the first capacitor CP1 and the second capacitor CP2 are chip capacitors.
[0010] Preferably, the linear regulator UP1 is of model AL8840.
[0011] The beneficial effects of the utility model are: when the smart meter is in the state of no voltage applied but current passing through, current still passes through the power transformer, and according to electromagnetic induction, the power transformer induces an AC voltage, and the induced AC voltage is used to power the system through rectification, filtering, voltage reduction and other operations, which can maintain the normal operation of the system in a short time and extend the service life of each component of the system. The circuit principle is simple, the cost is low, the sensitivity is high, and it has strong adaptability and practicality. BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Figure 1 : Schematic diagram of the circuit of the utility model;
[0013] Figure 2 : Schematic diagram of the circuit of the utility model linear voltage regulator;
[0014] Figure 3 : Schematic diagram of the rectifier bridge circuit of the utility model;
[0015] Figure 4 : Flow chart of the circuit principle of the utility model. DETAILED DESCRIPTION
[0016] The utility model is further described below in conjunction with the accompanying drawings and embodiments:
[0017] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0018] like Figures 1 to 4As shown, a power supply circuit based on a power transformer includes a power transformer, a rectifier bridge DP1, a first resistor RP1, a zener diode D2, a first capacitor CP1, a second capacitor CP2, a linear regulator UP1 and a rectifier diode DP2, the input end JM1 of the power transformer is connected to the input end of the rectifier bridge DP1, the output positive electrode of the rectifier bridge DP1 is connected to one end of the first resistor RP1, the output negative electrode of the rectifier bridge DP1 is grounded, the other end of the first resistor RP1 is connected to the negative electrode of the zener diode D2, the positive electrode of the zener diode D2 is grounded, one end of the first capacitor CP1 is connected to the positive electrode of the zener diode D2, and the other end is grounded, the connection end of the first capacitor CP1 and the zener diode D2 is connected to the input end of the linear regulator UP1, the ground end of the linear regulator UP1 is grounded, the output end of the linear regulator UP1 is connected to one end of the second capacitor CP2 and the positive electrode of the rectifier diode DP2, the other end of the second capacitor CP2 is grounded, and the negative electrode of the rectifier diode DP2 is connected to the meter power supply MVDD.
[0019] The circuit also includes a second resistor RP2, which is a winding resistor and is connected in parallel with the first resistor RP1. The power of the second resistor RP2 is 3W, and it is used to replace the first resistor RP1 to protect the circuit when the instantaneous current is too large. The circuit also includes an electrolytic capacitor E1, which is connected in parallel with the voltage stabilizing diode D2, and the positive electrode of the electrolytic capacitor E1 is connected to the negative electrode of the voltage stabilizing diode D2, so as to remove the remaining low-frequency AC component and make the output voltage more stable.
[0020] The first resistor RP1 is a chip resistor, and the first capacitor CP1 and the second capacitor CP2 are chip capacitors to reduce the size of components.
[0021] The main voltage stabilizing element of the above circuit is the voltage stabilizing diode D2. When the external voltage of the meter disappears, the power transformer induces an AC voltage, and the AC voltage outputs a DC voltage after passing through the rectifier bridge DP1. Since the current flowing through after the external voltage is interrupted is large, the energy output by the power transformer also increases accordingly, so the voltage stabilizing diode D2 is needed to stabilize the voltage to protect the subsequent circuit from being broken down. The first capacitor CP1 and the second capacitor CP2 are respectively the input capacitor and output capacitor of the linear regulator UP1. The first capacitor CP1 can filter the input of the linear regulator UP1 and improve the load transient response. The second capacitor CP2 can play a role in stabilizing the voltage and improving the transient response. The maximum input voltage of the linear regulator UP1 is 35V, and it can stably output a 4V voltage. Since the forward voltage drop of the rectifier diode DP2 is about 0.7V, the 4V voltage can drive the 3.3V of the single-chip microcomputer after passing through the diode.
[0022] When the smart meter is in a broken neutral line state, that is, no voltage is applied but current flows, the power transformer senses an AC voltage, which is rectified by the rectifier bridge DP1, stabilized by the voltage regulator diode D2, filtered by the electrolytic capacitor E1, and stepped down by the linear regulator UP1 to power the meter.
[0023] The linear regulator UP1 is an electronic component used to stabilize the output DC voltage. The linear regulator model used in this solution is AL8840, and its internal components mainly include an error amplifier, a reference voltage source, a series adjustment element, a compensation circuit, a protection circuit, etc. One end of the error amplifier is connected to a stable reference voltage source, and the other end is connected to the output end through a voltage divider resistor network, so that the output voltage can be monitored and compared with the reference voltage. When the output voltage is lower than the set value (i.e., the reference voltage), the error amplifier will output a positive signal to increase the conduction degree of the series adjustment element (such as a P-channel MOSFET), so that more current can flow from the input through this device to the output end, thereby increasing the output voltage. Conversely, if the output voltage rises and exceeds the set value for some reason, the error amplifier will output a negative signal to reduce the conduction degree of the series adjustment element, limit the current flowing to the load, and thus reduce the output voltage. Traditional linear regulators require a large input voltage margin to work properly, while the design of LDO allows it to maintain an effective working state under a small input / output voltage difference, which can usually be as low as a few hundred millivolts or even lower. LDO also has good noise suppression and extremely high linearity, and the output voltage is very stable with small ripple, which is suitable for applications that are sensitive to noise and require precise voltage control. In general, LDO uses a negative feedback mechanism to accurately keep the output voltage constant by real-time monitoring and adjusting the conduction state of the series adjustment element, and can achieve high-precision voltage regulation even when the load changes or the input voltage fluctuates.
[0024] The main power consumption of the above power supply circuit is concentrated in the voltage stabilizing diode D2, and the power of the voltage stabilizing diode D2 is selected to be 5W.
[0025] The present invention is described above by way of examples, but the present invention is not limited to the above specific embodiments, and any changes or modifications based on the present invention belong to the scope of protection required by the present invention.
Claims
1. A power supply circuit based on a power transformer, characterized in that: It includes a power transformer, a rectifier bridge DP1, a first resistor RP1, a zener diode D2, a first capacitor CP1, a second capacitor CP2, a linear regulator UP1 and a rectifier diode DP2. The input end JM1 of the power transformer is connected to the input end of the rectifier bridge DP1, the output positive electrode of the rectifier bridge DP1 is connected to one end of the first resistor RP1, the output negative electrode of the rectifier bridge DP1 is grounded, the other end of the first resistor RP1 is connected to the negative electrode of the zener diode D2, the positive electrode of the zener diode D2 is grounded, one end of the first capacitor CP1 is connected to the positive electrode of the zener diode D2, and the other end is grounded. The connecting end of the first capacitor CP1 and the zener diode D2 is connected to the input end of the linear regulator UP1, the ground end of the linear regulator UP1 is grounded, the output end of the linear regulator UP1 is connected to one end of the second capacitor CP2 and the positive electrode of the rectifier diode DP2, the other end of the second capacitor CP2 is grounded, and the negative electrode of the rectifier diode DP2 is connected to the meter power supply MVDD.
2. A power supply circuit based on a power transformer according to claim 1, characterized in that: The device further includes a second resistor RP2, which is a winding resistor and is connected in parallel with the first resistor RP1.
3. A power supply circuit based on a power transformer according to claim 2, characterized in that: The power of the second resistor RP2 is 3W.
4. A power supply circuit based on a power transformer according to claim 1, characterized in that: It also includes an electrolytic capacitor E1, which is connected in parallel with the voltage stabilizing diode D2, and the positive electrode of the electrolytic capacitor E1 is connected to the negative electrode of the voltage stabilizing diode D2.
5. A power supply circuit based on a power transformer according to claim 1, characterized in that: The power of the voltage stabilizing diode D2 is 5W.
6. A power supply circuit based on a power transformer according to claim 1, characterized in that: The first resistor RP1 is a chip resistor, and the first capacitor CP1 and the second capacitor CP2 are chip capacitors.
7. A power supply circuit based on a power transformer according to claim 1, characterized in that: The model of the linear regulator UP1 is AL8840.