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Domestic Water Heating
Published in William C. Dickinson, Paul N. Cheremisinoff, Solar Energy Technology Handbook, 2018
All pumped systems have at least four basic solar components, the collector(s), the storage tank(s), the control system, and the circulation pump(s). See Fig. 27.2 for an example. In pumped systems the absorbed energy in the collector is transferred to the storage tank by forced circulation of the collector fluid by a pump. The pump is controlled (turned on and off) by an electronic differential controller. The controller has two sensors, one mounted at the collector outlet and the other near the bottom of the tank. In the morning, as the sun heats up the stagnant collector fluid to a temperature about 6 to 10°C above the storage tank bottom temperature, the controller turns the pump on. This 6 to 10°C differential temperature needed to activate the pump is called the turn-on ΔT. As the circulation is established, ΔT between collector and storage drops to about 3 to 5°C. If the sunshine is insufficient to maintain a ΔT of 0.5 to 1.5°C (the turn-off ΔT), the controller stops the pump. The turn-on and turn-off ΔT’s can be adjusted on some controllers. So far the above discussion assumes fixed flow-rate pumps, which are the most widely used pumps for solar DHW systems. Recently some have started using proportional flow controls which vary the pump speed to collect a greater amount of energy. See Ref. 6 for a discussion of proportional flow controllers.
Principles of Energy Conversion
Published in Hamid A. Toliyat, Gerald B. Kliman, Handbook of Electric Motors, 2018
Hamid A. Toliyat, Gerald B. Kliman
Rosenberry [14] and Griffith et al. [15] consider induction motor rotor thermal esponse for several loading conditions and are useful references. Rosenberry [14] defines a representative thermal circuit and makes use of an electronic differential analyzer to reach a solution for the temperature response of an induction motor rotor winding when the rotor is stalled. McCoy et al. [15] utilize the finite element analysis technique. This is an advanced mathematical technique that allows the representation of motor thermal characteristics by a multielement approach that can closely replicate the actual distributed system. This analysis is also of an induction motor rotor winding. The computer program developed in Ref. 15 has capabilities for thermal analysis together with the capability of evaluating the mechanical fatigue life of the rotor winding for a defined duty cycle of motor loading. The analysis has the capability to evaluate the loading situations listed above. In Section 12.1, it was noted that the motor stator winding insulation temperature is limited by standards in order to insure a long insulation life. In the case of a squirrel-cage rotor, the squirrel-cage winding is not normally insulated. Nevertheless, temperature still plays a key role in squirrel-cage winding life. The temperature must be limited first to insure that no melting of the winding or gross distortion occurs. In addition, the material of the winding may be subject to fatigue by a combination of both centrifugal and thermal strains. The thermal strain is generally the more significant and the rotor winding temperatures must be obtained to determine the mechanical fatigue life of the winding.
Some audio principles
Published in John Watkinson, The Art of Digital Audio, 2013
Differential working with twisted pairs is designed to reject hum and noise, but it only works properly if both signal legs have identical frequency/impedance characteristics at both ends. The easiest way of achieving this is to use transformers which give much better RF rejection than electronic balancing. Whilst an effective electronic differential receiver can be designed with care, a floating balanced electronic driver cannot compete with a transformer. An advantage of digital audio is that these transformers can be very small and inexpensive, whereas a high-quality analog transformer is very expensive indeed.
Synthesized Fe-doped Co3O4 nanoparticles-based anode for high-performance lithium-ion batteries application
Published in International Journal of Green Energy, 2023
Lanlan Feng, Guofa Mi, Zhenluo Yuan, Zeping Liu, Baozhong Liu, Guangxin Fan
The phase structure of the samples was characterized by X-ray diffraction (XRD) using Rigaku Smart-lab diffractometer with Cu Kα radiation (λ = 0.15406 nm) at 40 kV and 150 mA. The data of XRD was collected in a 2θ range of 15–80° with step increments of 0.02°. Crystallite size and lattice parameters were obtained by Rietveld refinement. A field emission scanning electron microscope (FE-SEM) with Zeiss Merlin Compact and a transmission electron microscope (TEM) with JEOL JEM-2100F were used to obtain the morphology and size of particles. Electronic differential system (EDS) with Oxford Instruments and OXFOFD data were collected to confirm the composition of the material. Surface elemental valences of the CF-6 were performed using X-ray photoelectron spectroscopy (XPS) from Thermo Fisher Scientific Inc. Raman spectra was conducted with inVia-5000 by Renishaw. Specific surface areas and pore size of the samples were tested by 3Flex surface characteristic analyzer.
Dynamic control of electronic differential in the field weakening region
Published in International Journal of Electronics, 2019
In this paper, the electronic differential control method of the electric vehicle using outer rotor BLDC motor is proposed for the field weakening operation region. Unlike other electric machines, surface magnet BLDC motors are increasingly unstable because of their reduced control capability in the field weakening region. In order to reduce this instability and provide more dynamic control, the gain values of the PI controller are determined by the fuzzy controller. The membership functions are obtained according to the steering angle, phase advanced angle, and torque oscillation factors and also the error rate of the reference speed is determined and the gains of the PI controller are updated on-line. The proposed control algorithm is performed under different road conditions such as a road curved left and right, a straight road and a straight road with slope, and the effect of the proposed method is monitored. Experimental results show that the proposed method presents greater stability under various drive conditions.
MPC-based compensation control system for the yaw stability of distributed drive electric vehicle
Published in International Journal of Systems Science, 2018
Ke Shi, Xiaofang Yuan, Guoming Huang, Qian He
The control of vehicle yaw stability is a very important research topic in DDEV. The torque distribution strategy directly affects the vehicle stability by adjusting vehicle body posture (Shi, Yuan, & Liu, 2018). Numerous algorithms were employed to yaw stability strategy, such as fuzz control (Geng, Mostefai, Denai, & Hori, 2009; Park, Jeong, Jang, & Hwang, 2015), sliding mode variable structure control (Fazeli, Zeinali, & Khajepour, 2012), coordinated control (Ren & Atkins, 2010; Zhang, Wei, Yuan, & Tang, 2016). These yaw stability strategies were mainly based on the hierarchical control structure, and the desired torque was usually distributed to actuators via a low-level part (Guo, 2013). In low-level part, conventional torque distribution strategies mainly assigned motor torques at the left and right side to achieve electronic differential drive steering (Wang, Wang, Jin, & Song, 2011), or changed the distribution of inner and outer wheel drive forces to affect the slip ratio (Shino & Nagai, 2001). However, the instantaneous variations of four independent tyres slip ratio and the effect of disturbance have not been considered sufficiently in conventional yaw stability strategies (Xu, Zhu, Han, Zhao, & Qian, 2010). Therefore, the robustness of yaw stability for DDEV is hard to be achieved efficiently under the varied operating conditions.