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Electrical Aspects
Published in Frank R. Spellman, The Science of Wind Power, 2022
A Transformer is an electric control device (with no moving parts) that raises or lowers voltage or current in an electric distribution system. The basic transformer consists of two coils electrically insulated from each other and wound upon a common core (see Figure 8.96). Magnetic coupling is used to transfer electric energy from one coil to another. The coil, which receives energy from an a-c source, is called the primary. The coil that delivers energy to an a-c load is called the secondary. The core of transformers used at low frequencies is generally made of magnetic material, usually laminated sheet steel. Cores of transformers used at higher frequencies are made of powdered iron and ceramics, or nonmagnetic materials. Some coils are simply wound on nonmagnetic hollow forms such as cardboard or plastic so that the core material is actually air.
Research on a small wireless power transfer device via magnetic coupling resonant
Published in Lin Liu, Automotive, Mechanical and Electrical Engineering, 2017
Liu Xin, Ruqiang Dou, Yuben Yang, Ping Wu, Xuanyu Xiao, Sen Chen, Jianing Sun
The second type is through electromagnetic coupling resonant. It can be mainly divided into two types: electric coupling and magnetic coupling. Generally, it transfers energy due to the same resonant frequency of resonators mutual coupling with each other in the form of a electromagnetic field in the space. Compared to the electric field, strong magnetic coupling is safer to explore as the magnetic field is safe for people inside. According to theoretical calculation, its transmission distance of strongly magnetic coupling is in the range of 10 cm to 5 m. Also, in terms of the characteristics of the magnetic field, it can penetrate the non-magnetic substance, which does not change the characteristic of the distribution of electromagnetic field. We think it is the theory model with the most potential.
Linear Transformer
Published in Nassir H. Sabah, Circuit Analysis with PSpice, 2017
This chapter introduces magnetic coupling between coils, whereby a time-varying magnetic field of a current-carrying coil induces a voltage in a nearby coil. Magnetic coupling is the basis for transformer action and plays an essential role in many types of devices, circuits, and systems.
Improved quadratic boost converter using switching coupled-inductor and voltage-doubler
Published in Australian Journal of Electrical and Electronics Engineering, 2019
Yiyang Li, Swamidoss Sathiakumar, John Long Soon
To meet high output voltage requirements, using the magnetic coupling technique like coupled-inductors has attracted researchers’ attention. This technique can achieve extremely high voltage gain easily by increasing the turns-ratio of the coupled-inductor. Magnetic coupling is widely used in both isolated and non-isolated DC-DC converters. This technique can reduce the number of inductor cores and shrink the device size, which is important in circuit layouts (Li and Sathiakumar 2017b). There are two main types of magnetic coupling: transformer and coupled-inductor. DC-DC converters that use transformers provide freedom in the topology since circuits can achieve a high boosting ability using only a single transformer. The coupled-inductor is a component which can store energy in one switching state and deliver the energy to the load in another state. This technique is often used in non-isolated DC-DC boost converters and it provides a boosting effect by simple coupling inductors. To improve the voltage gain, the fly-back coupled-inductor found in classical switched-mode converter circuits performs well. This is an extension of conventional power converters. During the operation period, the energy is stored in the inductor during the on-state and then delivered to the load side in the off-state. Theoretically speaking, the step-up ratio of the circuit using coupled-inductor can be very high and the efficiency is improved (Choi et al. 2015). In Figure 1, the quadratic boost converter is improved using a coupled-inductor. The secondary part of the coupled-inductor is laid in the output side. This design can increase the voltage gain by both increasing the turns-ratio of the coupled-inductor and the duty cycle, but, in the quadratic boost design, when the coupling coefficient of the coupled-inductor is low, under 98%, there will be higher oscillations and overshoots in waveforms. This is because there is only one diode in the output side and it cannot totally block the effect of inductors in the real test.