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Electrophysiology
Published in A. Bakiya, K. Kamalanand, R. L. J. De Britto, Mechano-Electric Correlations in the Human Physiological System, 2021
A. Bakiya, K. Kamalanand, R. L. J. De Britto
In the preamplifier stage, most of the noise and interference of the measured signals can be eliminated (Nagel, 2000). Few considerations need to be taken into account while designing the preamplifiers, such as electrode potential, noise, the connection between the amplifier and biological sources and electromagnetic interference. The high- and low-pass filters are used to eliminate the interference in the acquired signals, such as preamplifier offset potential, electrodes half-cell potential and to reduce the noise in a particular frequency range. The isolation amplifiers are used to protect the measurement devices and patients. The isolation amplifier is designed with one of the three different techniques, namely, the transformer isolation, opto isolation and capacitor isolation (Nagel, 2000).
Giga-Ohm High-Impedance FET Input Amplifiers for Dry Electrode Biosensor Circuits and Systems
Published in Iniewski Krzysztof, Integrated Microsystems, 2017
Gaetano Gargiulo, Paolo Bifulco, Rafael A. Calvo, Maria Romano, Mariano Ruffo, Richard Shephard, Mario Cesarelli, Craig Jin, Alistair McEwan, André van Schaik
Another crucial point in the implementation of the complete biopotential recording system is the subject protection. In Figure 8.2 it is represented by isolation amplifiers that are also useful for breaking ground current loops and eliminating source ground connections. However, in a biopotential recording system, the main purpose of the isolation amplifier is to protect the patient by eliminating the hazard of electric shock resulting from interactions among the patient, the amplifier, and other electric devices in the patient’s environment, specifically defibrillators and electrosurgical equipment. Isolation amplifiers are realized in three different technologies: transformer isolation, capacitor isolation, and optical isolation. An isolation barrier provides a very high galvanic separation of the input side (i.e., the patient and the preamplifier) from all expected equipment on the output side. Ideally, there will be no flow of electric current across the barrier [2,4]. But, in practice, devices have an isolation of thousands of volts, which protects the subject from any reasonable risk they may encounter. Furthermore, advanced complete biopotential amplifier designs are completely floating and coupled wirelessly with data analysis stages. Here we have not addressed the filter design; however, this is highly dependent on application and the frequency range of the biopotentials of interest. The filter stages do not usually present great difficulties compared to the other issues such as contact impedance and safety concerns and so we believe that the filter stages are not as crucial as the preamplifier and insulation stages. These analog stages are followed by digitization via analog-to-digital conversion. Once the signal has been digitized it is much more flexible and convenient to apply sharp digital filters.
A novel low-cost microcontroller-based implementation of SVM algorithm for an indirect matrix converter
Published in EPE Journal, 2019
Ahmad Khajeh, Mohamad Hosseini Abardeh, Reza Ghazi, Sayed Masoud Barakati, Mahmood Oukati Sadegh
The modulation algorithm is implemented using an ARM-based controller (SAM7X256 from ATMEL) which has 55-MHz clock frequency. The development tool used for the ARM is Keil µVision version 4.0. The MCU generates 12 gate pulses for the rectifier and inverter stages. Two ADC channels are used to read the output data of the sensors which measure the IMC input voltages. Two line voltages are measured by AD202 isolation amplifier (from Analog Device) and the third line voltage is calculated considering a balanced three phase source. The currents are sensed by LTS 25-NP, a closed loop Hall Effect current sensor with wide frequency bandwidth, manufactured by LEM company. The IMC is implemented using 18 IGBT switches provided by Fuji electric (1MBH30D, VCE = 600 V, IC = 30 A). The switching frequency (fs) is 2 kHz. The RLC filter (R = 10 Ω;L = 1 mH and C = 20 µF) is connected to the IMC input side to reduce the switching harmonics. The load is a three-phase-balanced RL (R = 20 Ω and L = 20 mH) with star configuration. The input grid and output voltage frequencies are fi = 50 and fo = 30 Hz. The components types and their parameters used in the experimental set-up are reported in Table 2.
Design and development of three-phase EV charger based on the integration of voltage-oriented pulse width modulation control and water cycle algorithm fractional-order PI controller
Published in International Journal of Ambient Energy, 2023
Rheesabh Dwivedi, Sanjeev Singh, Bhim Singh
It is designed with optimum versatility and convenience of use in a wide range of applications needing rapid analog measurements. This voltage sensor circuit isolates and amplifies wide bandwidth analogue signals using the AD215 analogue input isolation amplifier. Between inputs and outputs, the AD215 provides galvanic isolation. The AD215 has an input/output range of ±10 V, a specified gain range of 1 V/V to 10 V/V, and a buffered output with offset trim. A ±15 V dc at ± 10 mA supply is used to power this fully functional design.
A Reduced Switch Five-Level VSI for High-Performance Vector Controlled PMSM Drive
Published in Electric Power Components and Systems, 2020
Rajesh Kumar Mahto, Ambarisha Mishra, Ramesh C. Bansal
The circuit diagram of traditional three-phase inverter consists of six-switches with anti-parallel diodes as shown in Figure 1. The individual switch requires gate pulse that is provided using SPWM where a modulating signal having frequency 50 Hz, compared with a carrier signal of high frequency (integer multiple of modulating wave frequency). Based on input signals output of the comparator generates a square wave pulse that is given to gate driver circuit of switches through isolation amplifier.