Research And Design On High-precision Electric Energy Metering Chip Based On Time-division Multiplier

To achieve the goal of"carbon neutrality"and"carbon peak"on time,China has begun building more and more renewable energy stations and energy storage stations.After these stations connect to the grid,the energy structure and stability of the grid have improved.However,energy management and distribution in the grid have become more complicated.With the demand for more straightforward grid control and more refined energy management,the grid is turning into the"smart grid"with the support of modern information and communication technology.In contrast,the base stone of the smart grid relies on adequate and on-time information collection from the grid nodes.Therefore,smart meters,which measure and transmit informations,are the anchor of the modern smart grid.Currently,many metering chip manufacturers have launched their electric energy metering chips.While these chips use the analog-to-digital converter structure,the accuracy is only up to 0.1%.Hence,these chips cannot meet requests of refined energy management under the High-Voltage Grid and cannot guarantee the fairness of economic interests between power companies and users within the Mains Electricity Grid.A high-precision analog energy metering chip based on Time-Division Multiplier（TDM）is developed in this dissertation.The main works of this dissertation are as follows:（1）For the problem that methods in the time domain are too complex to support the TDM-based high-precision design.The proposed method analysis the TDM structure which is composed of pulse width modulator,pulse amplitude modulator,and filter,and draws the conclusion that the first two modules can be abstracted as oversampling modulator and digital-analog hybrid multiplier respectively.Moreover,the factors that affect the TDM output from these two modules are analyzed,and the errors consist of phase shift error,quantization noise error,nonlinearity error,and harmonic error.Based on the general definition of error,the specific expressions of phase shift error,nonlinearity error,and quantization noise error are derived.In addition,the precision improvement methods for the TDM structure are proposed.Compared with conventional methods,the proposed method is based on frequency domain analysis.It has a simple form and is more suitable for circuit integration.（2）To meet the demands of high-precision energy metering instruments in the smart grid,a TDM-based high-precision energy metering chip is developed.Based on the previously proposed accuracy improvement methods,to achieve the high-precision energy metering circuit,the quantization noise error is reduced by increasing the operating frequency of the oversampling modulator,the phase shift error is eliminated by using a modulator with phase compensation branch,the nonlinearity error is minimized by designing a high open-loop gain operational amplifier,and the harmonic error is diminished by using a notch filter.To eliminate the phase shift error and harmonic error properly in chip debugging stage,the modulator with phase compensation branch is analyzed,the specific expression of the phase compensation resistance ratio is derived,and the root locus method is used to simplify the design process of the notch filter.The high-precision energy metering chip adopts a 0.35μm high-voltage CMOS process.The overall area of the energy metering chip is 2.5×1.6mm².After off-chip adjustment and compensation,the test error of the energy metering chip does not exceed 76ppm,which is achieved the energy power metering accuracy of 0.01.（3）To further explore the potential of the proposed frequency domain-based analysis method in this dissertation for energy metering circuit design,a discrete-time high-precision energy metering system architecture is proposed.To bypass high power consumption and low integrity caused by large capacitors,the digital filter is used.To avoid off-chip capacitors and increase the order as well as the operating frequency of the modulator,a widely used discrete-time Sigma Delta modulator,which has a large number of theoretical foundations and practical circuits realization,is used.To prevent low-precision on-chip resistors,switched capacitor circuits are used.To process input signal which has power distortion and frequency offset,the CIC-based decimation filter and a phase-locked loop,which provide the system clock signal,are adopted.To maintain accuracy under long-term operation,chopper stabilization technology is used.After simulation validation,in the Verilog-A ideal circuit model,the maximum error of the circuit,which uses the second-order modulator,is only 4×10^-8.The simulation result demonstrates the energy metering system architecture has high accuracy.It provides a foundation to further develop higher precision energy metering chips.The research results in this dissertation improve and enrich the TDM theory,which significantly improve the accuracy of the energy metering chip,and provide a foundation to design the high-precision metering chip in the future.