Description The invention relates to a wide-range electric energy meter, in particular to a wide-range electric energy meter based on a Hall sensor. Background of the invention Electromagnetic current transformers are commonly used in electric energy meters as current sensing units. Due to their magnetic saturation and limited bandwidth, it is difficult to accurately detect high frequency components and DC currents. With the popularization of non-linear devices such as power electronics in the power grid , electromagnetic current transformers have been unable to meet the needs of the market. The Hall sensor is a wideband current sensor that can be used to detect various AC and DC magnetic fields. However, since the dynamic range of the open-loop Hall sensor is generally narrow, the detectable magnetic field has a small variation range, and is generally only used in the case where the motor control, the Hall switch, etc. are not required for the detection accuracy and the dynamic range, and the electric energy meter The current detection unit requires a wide bandwidth and a wide dynamic range. In terms of the current specification of a common energy meter 5 (60) A, the current detection dynamic range is as high as 1200:1, and the dynamic range of the general open-loop Hall sensor can only be detected. 200:1, can not meet the practical requirements, and the measurement accuracy will be affected under strong magnetic interference. Summary of the invention In view of the existing problems, an object of the present invention is to provide a wide-range electric energy meter based on a Hall sensor with wide frequency band, wide dynamic range, high accuracy, and resistance to external magnetic interference. Figure is a block diagram of the invention The wide-range electric energy meter based on the Hall sensor provided by the invention comprises a Hall current detecting module, a voltage detecting module, an MCU signal processing control module, a metering module, a display alarm communication module and a power module; the Hall current detecting module senses The current changes, the measurement result is transmitted to the metering module and the MCU signal processing control module; the voltage detecting module measures the voltage and transmits the measurement result to the metering module; the metering module performs A/D conversion on the signal and compensates the corrected output signal to the MCU. The signal processing control module; the MCU signal processing control module performs temperature compensation processing on the signal output by the metering module and stores it, and then displays the alarm communication module for display, and performs current detection range through the voltage magnitude transmitted in the Hall current detecting module. Switching control; display alarm communication module includes LCD display module, alarm module and communication module, LCD module displays real-time display of power consumption, alarm module performs alarm when current and / or voltage is too large, and disconnects power through relay, communication Module for data exchange with the outside world , including far infrared communication, GPRS communication, carrier communication and 485 communication; the power module supplies power to the Hall current detection module, the MCU signal processing control module, the metering module and the display alarm communication module. The Hall current detecting module includes a No. 1 Hall current sensor and a No. 2 Hall current sensor, and both Hall current sensors are open-loop Hall sensors, and the two are placed in a vertical direction on the PCB. The PCB of the Hall current detecting module is U-shaped, and a metal block having the same shape as the PCB is detected under the PCB. The current detection range of the No. 1 Hall current sensor is larger than the current detection range of the No. 2 Hall current sensor; the ranges of the two can be modified online by the programmer; and both are equipped with a nickel-iron shield. The No. 1 Hall current sensor is provided with a U-shaped shield. The No. 2 Hall current sensor is equipped with a C-type shield. The Hall current detecting module comprises a No. 1 Hall current sensor U1 and a No. 2 Hall current sensor U2 and a signal switching control circuit; the signal switching control circuit comprises a No. 1 signal switching control circuit and a No. 2 signal switching control circuit; The signal switching control circuit includes a triode Q202 and a triode Q204, and the second signal switching control circuit includes a triode Q203 and a triode Q205. The detection voltage pin VDEC of the No. 1 Hall current sensor U1 is grounded through the capacitor C1; the output pin OUT is grounded through the resistor R1, and the output pin is also connected to the No. 1 signal switching control circuit, and the output pin also passes through the capacitor C3. Grounding; the power pin VDD of the chip U1 is connected to the power source VCC, and the pin is also grounded through the capacitor C2; the negative terminal VSS of the power supply of the chip U1 and the test pin TEST are grounded; the emitter of the transistor Q202 passes through the resistor R239 and a The output pin OUT of the Hall current sensor U1 is connected, the base thereof is connected to the collector of the transistor Q204 through the resistor R240, and the collector is used as the output port of the No. 1 signal switching control circuit; the emitter of the transistor Q204 is connected to the analog ground. The base is connected to the IO port of the MCU through a resistor R241 for transmitting the switching control signal of the MCU. The circuit connection structure of the second Hall current sensor U2 is the same as that of the No. 1 Hall current sensor U1; the circuit connection structure of the No. 2 signal switching control circuit is the same as the circuit connection structure of the No. 1 signal switching control circuit; Hall No. 2 current The circuit connection structure of the sensor U2 and the No. 2 signal switching control circuit is the same as that of the No. 1 Hall current sensor U1 and the No. 1 signal switching control circuit. The output end of the No. 2 signal switching control circuit is connected to the output end of the No. 1 signal switching control circuit, and the output signals are all sampled through the resistor R245. The sampling signal is filtered by a filter network composed of a resistor R217, a resistor R218, a capacitor C209, and a capacitor C210. After being connected to the metering module, the connection end of the resistor R245 and the resistor R218 is connected to the analog ground, and the connection of the capacitor C209 and the capacitor C210 is not connected to the analog ground. The voltage detecting module detects the voltage by using a resistor divider network, and then outputs the signal to the metering module. The power module uses a transformer, a switching power supply chip, and a linear low-dropout regulator to supply power to each module of the electric energy meter. The invention can measure the current in the range of 0.05A~200A and work normally under the external magnetic interference environment within 330mT. For the magnetic field interference from one direction, the electric energy meter is free from any interference and has the AC/DC detection. And high frequency nonlinear component detection. The invention adopts an open-loop Hall sensor, and the structural design is obviously simpler than the closed-loop Hall sensor, eliminating the complicated magnetic circuit design, and the nonlinearity can reach 5‰, and the temperature drift can be controlled within 50ppm\°C by the temperature compensation algorithm. . The invention can also modify the energy meter test range by real-time online, so the invention can be applied to a variety of applications. In addition, by designing the metal strip structure through which the current flows under the Hall sensor, the detection current can reach 2000A.
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Patented wide-range energy meter based on Hall sensor
There is no limit to creativity, and the instrument is invented. Today we introduce a national invention patent for granting a wide-range energy meter based on Hall sensors. The patent was filed by Wasion Group Co., Ltd. and was granted a notice of authorization on July 18, 2017.