Improved eddy current testing sensitivity using phase information

This paper describes a two-coil eddy current sensor being used in a transmit-receive arrangement at 1 MHz, where the drive and amplification electronics are miniaturised and built directly behind the coil to reduce noise and the effects from cable length. Small, simulated defects are detected, less than 500 microns in length, on titanium and titanium aluminide, which is an increasingly important alloy for aerospace applications. Data is analysed quantitatively in a parametric approach. This experiment uses a transmitting coil driven by a constant current source and a separate receiving coil, where the magnitude and phase of the induced voltage signals on both coils are measured independently. Experimental measurements are validated using finite element modelling and the phase of the signal on the receiving coil in particular is less susceptible to variations caused by changes in lift-off. A combination of experimental and simulation data of 2D surface scans and lift-off measurements show the variation in the magnitude and phase of the eddy current signal with lift-off on Ti, TiAl (Ti-45Al-2Mn-2Nb-1B) and 316L stainless steel. It is also shown that the high-frequency lower noise approach can reliably detect defects of less than 500 microns in length in both Ti and TiAl.

System anti-jamming technology in the design of intelligent single chip computer constant current source of field strength machine

With the development of the electric power industry, the technical level of automatic testing equipment for the reliability of electrical component circuit breakers in the transmission and distribution network is getting higher and higher. The stability and accuracy of the test power supply are the basis for ensuring the pass rate of the test product. Most of the electrical testing and testing equipment has defects such as inaccurate power supply current regulation, low power, and low level of intelligence, which are difficult to meet the testing requirements. Based on the theory of a closed-loop control system, this paper adopts embedded system design technology to realize a high-current, high-power, high-stability digital constant current source system for line detection. This paper studies the rule-based intelligent anti-jamming decision engine design and system anti-jamming performance analysis of NC-OFDM system. We give the design of an intelligent anti-jamming decision engine based on rule-based decision-making, and focus on two intelligent anti-jamming decision-making algorithms: Adaptive Modulation and Coding (AMC) algorithm based on signal-to-noise ratio difference and packet error rate and Adaptive Sub-Band Selection (ASBS) algorithm. Experimental test results show that the output current range is 200 mA to 2000 mA, the system has realized a microstep adjustment of±5 mA, and the absolute error of current measurement is less than 0.3%+4 mA. The system is stable and reliable, and has high practical value in the field of high precision and low power.

Estimation of SOC Based on LSTM-RNN and Design of Intelligent Equalization Charging System

Lithium battery packs are the main driving energy source for electric vehicles. A battery pack equalization charging solution using a constant current source for variable rate charging is presented in this paper. The charging system consists of a main constant current source and independent auxiliary constant current sources. Auxiliary constant current sources are controlled by the battery management system (BMS), which can change the current rate of the corresponding single battery, and achieve full charging of each single cell in the series battery pack. At the same time, the state of charge (SOC) is regarded as time series data to establish a long short-term memory recurrent neural network (LSTM-RNN) model, and it is possible to obtain the single battery with lower capacity, so that the charging efficiency and battery pack consistency can be improved. The experimental results show that the open circuit voltage difference between the single cells is less than 50 mV after the charging of 20 strings of lithium battery packs by using this method, which achieve the purpose of equalization charging.

Design of DFB Laser Drive and Temperature Control Circuit in TDLAS Gas Concentration Detection

In order to satisfy the requirements of TDLAS gas measurement, the DFB laser drive and temperature control system is designed with taking STM32F103RCT6 as the main control chip, including sine wave and sawtooth signal generation circuit, temperature acquisition circuit and temperature control circuit, etc. The sine wave and the sawtooth wave signal are respectively generated by using the DDS chip and the STM32 on-chip DAC, and the two are superimposed to control the constant current source to drive the laser. At the same time, the internal temperature of the laser is collected and controlled. The DFB laser with a center wavelength of 1653.7 nm is used to verify the CH4. The experiment proves that the system can generate stable laser driving signals and achieve precise temperature control. The temperature control accuracy can reach ±0.013 °C. The design satisfies the requirements of TDLAS gas detection system for laser driving and temperature control.

Smart branch and droop controller based power quality improvement in microgrids

This paper presents two unique smart branch controller for compensating several power quality disturbances. The first proposed intelligent branch controller comprises a series transformer with its indirectly controlled impedance by secondary voltage injection. Further, the smart controller is made adaptive and flexible. It is installed at the point of common coupling (PCC), where PCC voltage & load current can be locally acquired without the presence of a communication channel, which then tracks its references as pure sinusoidal waveforms. Therefore without any filter requirement, harmonic elimination is done by the smart branch controller. The proposed smart controller can be applied in microgrids (MGs) for multi-objective optimization of power quality (PQ). For proper elimination of harmonics and to enhance the quality of power supply, the smart branch is optimized by a droop controller, which delivers power to a constant current source and eliminates harmonics by providing an appropriate quantity of harmonic voltage to the inverter voltage. The total harmonic distortion (THD) becomes 23.06% for the voltage and 6.24% for the current with droop controller, whereas, with an only smart branch into the power network, the THD becomes 26.47% for the voltage and 12.30% for the current. The simulation result concludes that the discussed optimized smart branch-based droop controller reduces drastically THD. Also, a separate study has been performed on the improvement of PQ by second proposed smart controller called as Photovoltaic Distribution Static Compensator (PV-DSTATCOM) grid-tied system using an adaptive reweighted zero attracting (RZA) control algorithm with perturbation and by applying maximum power point tracking technique (MPPT) for a three-phase system. The converter with PV array along with an active filter feature known as PV-DSTATCOM is required to convert the DC voltage into AC and for the improvement of the PQ by limiting harmonic distortions. It is concluded from the simulation results that the use of the RZA strategy presents an excellent steady state and transient response. The proposed PV grid-tied system is capable of working round the clock for both constant and variable irradiation and linear loads. The system is termed as smart as it can perform both modes automatically sensing the PV power and is capable of multi-directional power flow. The proposed method performs dual functions of improving PQ by working as DSTATCOM and also transfers power to the load and the grid obtained from PV array.