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Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
metal 2 the second layer applied in a fabrication process. In general the nth layer of the fabrication process is called metal n. metal halide molecule formed by the reaction of metals and halogen atoms. metal-electrode semiconductor field-effect transistor (MESFET) a specific type of FET that is the dominant active (amplifying) device in GaAs MMICs. An FET is composed of three terminals called the gate, drain, and source, and a conducting "channel." In an amplifier application, the source is connected to ground, and DC bias is applied between the drain and source causing a current to flow in the channel. The current flow is controlled and "modulated" by the AC or DC voltage applied to the gate. metal-insulator-metal (MIM) capacitor a capacitor, which has a thin insulator layer between two metal electrodes. Generally, this capacitor is fabricated in semiconductor process, and this insulator layer provides high capacitance. Two extreme behaviors of a capacitor are that it will act as an open circuit to low frequencies or DC (zero frequency), and as a short frequency at a sufficiently high frequency (how high is determined by the capacitor value). Also called a thin film capacitor. metal-organic chemical vapor deposition (MOCVD or OMCVD) a material growth technique that uses metal organic molecules in an atmospheric or low pressure growth chamber and a controlled chemical reaction on a heated substrate to grow a variety of II-VI, III-V, and group IV materials with atomic layer control. Used to create material structures for a variety of electronic and
Capacitance and Capacitance Measurements
Published in John G. Webster, Halit Eren, Measurement, Instrumentation, and Sensors Handbook, 2017
The electric equivalent circuit of a capacitor consists of a pure capacitance (Cp), plate inductances (L1,L2), plate resistances (R1, R2), and a parallel resistance Rp that represents the resistance of the dielectric or leakage resistance, as shown in Figure 28.13. The capacitors that have high leakage currents flowing through the dielectric have relatively low Rp values. Very low leakage currents are represented by extremely large Rp values. Examples of these two extremes are electrolytic capacitors that have high leakage current (low Rp) and plastic film capacitors, which have very low leakage current (high Rp). Typically, an electrolytic capacitor might easily have several microamperes of leakage current (Rp < 1 Mω), while a plastic film capacitor could have a resistance greater than 100,000 Mω
C&G Unit 302: Principles of electrical science
Published in Trevor Linsley, Advanced Electrical Installation Work, 2019
Polyester capacitors are an example of the plastic film capacitor. Polypropylene, polycarbonate and polystyrene capacitors are other types of plastic film capacitor. The capacitor value may be marked on the plastic film, or the capacitor colour code given in Table 3.5 may be used. This dielectric material gives a compact capacitor with good electrical and temperature characteristics. They are used in many electronic circuits, but are not suitable for high-frequency use.
Performance evaluation of transformerless photovoltaic inverter
Published in International Journal of Electronics, 2023
Tarun Naruka, Ramesh Kumar Pachar
The 2 ripple shown in Equation 2 is injected into the DC source which creates capacitive ground between SPV terminal and ground. The common mode leakage current creates electromagnetic interference (EMI) problem that compromises the reliability of the system. The reliability challenges are mitigated by different methods: Use of costly film capacitor instead of electrolytic capacitor;Topological changes in DC-AC inverter to reduce the capacitive ground issue (Roy et al., 2018);Appropriate control technique to mitigate SHC (Gautam et al., 2020; Jeong et al., 2013; Kan et al., 2018);
A single-stage AC-DC-AC buck-boost converter with variable frequency operations for power quality
Published in International Journal of Electronics Letters, 2021
Shabab Zahra, Jawad Hussain, Muhammad Mubasher Akram, Muhammad Siddique
This paper proposes new symmetric NI and inverting buck-boost (IBB) operating states of the proposed ac-(dc)-ac converter. The suggested operating modes provide single-stage power conversion with bipolar B-B voltage gain of . In addition, the proposed approach minimises the dc-link capacitance requirement (<10 μF) and thus, film capacitor can be used instead of electrolytic capacitor with low loss and longer life. Based on these novel operating states, switching techniques are introduced for step-changed frequency output. This essentially makes this circuit a shared leg MC with buck and boost voltage functionality, bipolar gain range, and step-changed frequency operation. The new NI and IBB states along with other prominent features of MC (shared leg, no commutation problem, continuous input/output currents), make it very suitable solution for grid voltage compensation applications, such as FUT and DVR. Due to bipolar voltage gain, it can overcome broad range of both voltage dip and surge without using low-frequency negative-tapped windings. In addition, the step-changed frequency operation can also be utilised in applications such as induction heating, induction motor drive, and high gain ac-dc rectifier, etc. The comprehensive study for these operating modes is presented to support the outcome of proposed converter.
Enhanced Power Output from the PV with Low Input Ripple DC-DC Converter
Published in Electric Power Components and Systems, 2018
Chandrasekar Venkatesan, Chakkarapani Manickam, Maddikara Jaya Bharata Reddy, Saravana Ilango Ganesan, Nagamani Chilakapati
This paper has presented a model to confirm the reduction of switching frequency voltage ripple injected into the PV module integrated on low-voltage DC grid by using an interleaved boost converter. The model requires knowledge of the first harmonic voltage ripple imposed on the PV module, which is derived from small-signal modeling. This topology offers the following advantages for a PV system:The two-phase interleaved boost converter reduces the power loss introduced by the conventional boost converter by at least 75%.The PV power is enhanced by reducing the oscillation around the MPP.Electrolytic capacitor, with a short lifespan can be replaced by the longer lasting film capacitor, which increases life time of the entire PV system.The overall PV system efficiency is improved, especially under low insolation conditions.