Three-phase four-wire electric energy meter with open-phase and neutral-line open-circuit detection

Abstract

The utility model discloses a three-phase four-wire electric energy meter with open-phase and neutral-line open-circuit detection, which comprises a microcontroller, and a metering chip, a fault detection module, a display module, a communication module and a storage module which are respectively and electrically connected with the microcontroller, the metering chip is used for A-phase voltage sampling, B-phase voltage sampling, C-phase voltage sampling, A-phase current sampling, B-phase current sampling and C-phase current sampling, and sending electric energy metering information of voltage sampling and current sampling to the microcontroller; the microcontroller sends a high-low level control signal to the fault detection module, and the fault detection module performs open-phase detection and neutral line open-circuit detection according to the high-low level control signal; the display module adopts a segment code type LCD display screen and is provided with a key for switching display contents; the communication module is used for setting the electric energy meter or reading the electric energy meter; the storage module is used for storing electric energy data and configuration parameters.

Description

Technical Field

[0001] The utility model belongs to the technical field of electronic circuits, and in particular relates to a three-phase four-wire electric energy meter with phase loss and neutral line open circuit detection capabilities. Background Art

[0002] In three-phase, four-wire AC applications, phase loss and neutral open circuit faults are common. These faults can cause equipment to malfunction and even pose a threat to life and property. Currently, phase loss and neutral open circuit faults in electricity meters are typically detected and evaluated independently. Furthermore, neutral open circuit faults are often detected by adding a dedicated detection chip or by using a current transformer to sample the neutral current.

[0003] However, detecting phase loss and neutral open faults separately can lead to fault misjudgment under certain conditions. It can even prevent detection of one fault while the other is occurring. For example, a neutral open fault cannot be detected when a phase loss fault occurs. Furthermore, adding a dedicated detection chip or using a current transformer to sample the neutral current for neutral open fault detection increases circuit costs. Furthermore, using a current transformer to sample the neutral current for neutral open detection cannot accurately detect the three-phase load. Utility Model Content

[0004] In view of the above problems, the utility model provides a three-phase four-wire electric energy meter with phase loss and neutral line open circuit detection.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A three-phase four-wire electric energy meter with phase loss and neutral line open circuit detection includes a microcontroller and a metering chip electrically connected to the microcontroller, a fault detection module, a display module, a communication module and a storage module.

[0007] The metering chip is used for sampling the voltage of phase A, the voltage of phase B and the voltage of phase C, as well as sampling the current of phase A, the current of phase B and the current of phase C, and sends the electric energy metering information of the voltage sampling and the current sampling to the microcontroller;

[0008] The microcontroller sends high and low level control signals to the fault detection module, and the fault detection module performs phase loss detection and neutral line open circuit detection according to the high and low level control signals;

[0009] The display module adopts a segment code LCD display screen and is provided with a button for switching the display content;

[0010] The communication module is used to set up or read the electric energy meter;

[0011] The storage module is used to store electric energy data and configuration parameters.

[0012] In a possible implementation, the fault detection module has three fault detection circuits corresponding to phase A voltage sampling, phase B voltage sampling, and phase C voltage sampling, respectively.

[0013] In one possible implementation, the fault detection circuit corresponding to the A-phase voltage sampling includes a tenth resistor, an eleventh resistor, a twelfth resistor, and a first MOSFET, one end of the twelfth resistor is respectively connected to the A-phase detection control signal pin of the microcontroller and the gate of the first MOSFET, the other end of the twelfth resistor is grounded and the source of the first MOSFET, the drain of the first MOSFET is connected to one end of the eleventh resistor, the other end of the eleventh resistor is connected to one end of the tenth resistor, and the other end of the tenth resistor is connected to the A-phase voltage input terminal.

[0014] In a possible implementation manner, the microcontroller model is V8531.

[0015] In a possible implementation, the communication module adopts an RS485 communication module.

[0016] In a possible implementation, the storage module uses an EEPROM chip.

[0017] The utility model has the following beneficial effects: the phase loss detection function and the neutral line open circuit detection function are combined in the electric energy meter, thereby avoiding missed detection or false detection, having a simple structure, and facilitating the safe use of electric energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a functional block diagram of a three-phase four-wire electric energy meter with phase loss and neutral line open circuit detection according to an embodiment of the present utility model;

[0019] Figure 2 This is the schematic diagram of the fault detection circuit corresponding to phase A voltage sampling;

[0020] Figure 3 This is the schematic diagram of the fault detection circuit corresponding to the B-phase voltage sampling;

[0021] Figure 4 This is the schematic diagram of the fault detection circuit corresponding to the C-phase voltage sampling. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0023] Reference Figure 1 , shown is a principle block diagram of a three-phase, four-wire electric energy meter with phase loss and neutral line open circuit detection according to an embodiment of the present invention. The meter includes a microcontroller 102, a metering chip 101 electrically connected to the microcontroller 102, a fault detection module 106, a display module 103, a communication module 104, and a storage module 105. The metering chip 101 is used to sample the voltage of phase A, phase B, and phase C, as well as the current of phase A, phase B, and phase C, and transmits the electric energy metering information obtained from the voltage and current sampling to the microcontroller 102. The microcontroller 102 transmits high and low level control signals to the fault detection module, and the fault detection module 106 performs phase loss detection and neutral line open circuit detection based on the high and low level control signals. The display module 103 uses a segmented LCD display screen and is provided with a button for switching display content. The communication module 104 is used to set or read the electric energy meter. The storage module 105 is used to store electric energy data and configuration parameters. The configuration parameters may include communication baud rate, meter reading date, and fault detection cycle.

[0024] In the specific application example, the microcontroller model is V8531, the communication module adopts RS485 communication module, and the storage module adopts EEPROM chip.

[0025] Another embodiment of the present invention is a three-phase four-wire electric energy meter with phase loss and neutral line open circuit detection, see Figures 2 to 4 As shown, the fault detection module has three fault detection circuits, corresponding to the A phase voltage sampling, the B phase voltage sampling and the C phase voltage sampling respectively. Figure 2 As shown, the fault detection circuit corresponding to the A-phase voltage sampling includes a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, and a first MOSFET Q1. One end of the twelfth resistor R12 is respectively connected to the A-phase detection control signal pin Detec_ctrA of the microcontroller 102 and the gate (G) of the first MOSFET Q1, the other end of the twelfth resistor R12 is grounded and the source (S) of the first MOSFET Q1, the drain (D) of the first MOSFET Q1 is connected to one end of the eleventh resistor R11, the other end of the eleventh resistor R11 is connected to one end of the tenth resistor R10, and the other end of the tenth resistor R10 is connected to the A-phase voltage input terminal. Figure 3 The B-phase voltage sampling and Figure 4 The circuit connection relationship between the fault detection circuit for phase C voltage sampling and the corresponding fault detection circuit for phase A voltage sampling is not described again here. The microcontroller 102 sequentially outputs high-level control signals to Detec_ctrA, Detec_ctrB, and Detec_ctrC (when one outputs a high level, the other two output a low level). After each high-level control signal is output, the microcontroller 102 reads the voltage sampling values ​​of ADC1, ADC2, and ADC3 in the metering chip 101. If, after any high-level control signal is output, the voltage sampling values ​​of ADC1, ADC2, and ADC3 change by a rate greater than a set change threshold (e.g., 10%), that is, the rate of change between the voltage sampling value when the control signal is output and the voltage sampling value when the control signal is not output is greater than 10%, then it is considered that a neutral line open circuit fault has occurred. Otherwise, it is considered that no neutral line open circuit fault has occurred. At the same time, if any of the voltage sampling values ​​of ADC1, ADC2, and ADC3 is consistently less than the set phase loss threshold, then the corresponding phase is confirmed to be a phase loss, regardless of whether the neutral line is open or not.

[0026] By using the above-mentioned three-phase four-wire electricity meter with phase loss and neutral line open circuit detection, the phase loss detection function and the neutral line open circuit detection function are combined in the electricity meter, thereby avoiding missed detection or false detection. The structure is simple and contributes to the safe use of electricity.

[0027] It should be understood that the exemplary embodiments described herein are illustrative and not restrictive. Although one or more embodiments of the present invention have been described with reference to the accompanying drawings, it should be understood by those skilled in the art that various changes in form and detail may be made without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims

1. A three-phase four-wire electric energy meter with phase loss and neutral line open circuit detection, characterized in that: It includes a microcontroller and a metering chip, a fault detection module, a display module, a communication module and a storage module electrically connected to the microcontroller. The metering chip is used for sampling the voltage of phase A, the voltage of phase B and the voltage of phase C, as well as sampling the current of phase A, the current of phase B and the current of phase C, and sends the electric energy metering information of the voltage sampling and the current sampling to the microcontroller; The microcontroller sends high and low level control signals to the fault detection module, and the fault detection module performs phase loss detection and neutral line open circuit detection according to the high and low level control signals; The display module adopts a segment code LCD display screen and is provided with a button for switching the display content; The communication module is used to set up or read the electric energy meter; The storage module is used to store electric energy data and configuration parameters.

2. The three-phase four-wire electric energy meter with phase loss and neutral line open circuit detection according to claim 1, characterized in that: The fault detection module has three fault detection circuits, which correspond to phase A voltage sampling, phase B voltage sampling and phase C voltage sampling respectively.

3. The three-phase four-wire electric energy meter with phase loss and neutral line open circuit detection according to claim 2, characterized in that: The fault detection circuit corresponding to the A-phase voltage sampling includes a tenth resistor, an eleventh resistor, a twelfth resistor, and a first MOSFET. One end of the twelfth resistor is respectively connected to the A-phase detection control signal pin of the microcontroller and the gate of the first MOSFET, the other end of the twelfth resistor is grounded and the source of the first MOSFET, the drain of the first MOSFET is connected to one end of the eleventh resistor, the other end of the eleventh resistor is connected to one end of the tenth resistor, and the other end of the tenth resistor is connected to the A-phase voltage input terminal.

4. The three-phase four-wire electric energy meter with phase loss and neutral line open circuit detection according to any one of claims 1 to 3, characterized in that: The model of the microcontroller is V8531.

5. The three-phase four-wire electric energy meter with phase loss and neutral line open circuit detection according to any one of claims 1 to 3, characterized in that: The communication module adopts RS485 communication module.

6. The three-phase four-wire electric energy meter with phase loss and neutral line open circuit detection according to any one of claims 1 to 3, characterized in that: The storage module adopts an EEPROM chip.

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