A Cascaded MEMS Amplitude Demodulator for Large Dynamic Range Application in RF Receiver

An amplitude demodulator with a large dynamic range, based on microelectromechanical systems (MEMS), is proposed in this paper. It is implemented as a cascade of a capacitive and a thermoelectric sensor. Two types of the transducer can improve the measurement range and enhance the overload capacity. This MEMS-based demodulation is realized by utilizing the square law relationship and the low-pass characteristic during the electromechanical and thermoelectric conversion. The fabrication of this device is compatible with the GaAs monolithic microwave integrated circuit (MMIC) process. Experiments show that this MEMS demodulator can realize the direct demodulation of an amplitude modulation (AM) signal with a carrier frequency of 0.35–10 GHz, and cover the power range from 0 to 23 dBm. This MEMS demodulator has the advantages of high power handling capability and zero DC power consumption.

Effect of Loads on Temperature Distribution Characteristics of Oil-Immersed Transformer Winding

The temperature of the hot-spots on windings is a crucial factor that can limit the overload capacity of the transformer. Few studies consider the impact of the load on the hot-spot when studying the hot-spot temperature and its location. In this paper, a thermal circuit model based on the thermoelectric analogy method is built to simulate the transformer winding and transformer oil temperature distribution. The hot-spot temperature and its location under different loads are qualitatively analyzed, and the hot-spot location is analyzed and compared to the experimental results. The results show that the hot-spot position on the winding under the rated power appears at 85.88% of the winding height, and the hot-spot position of the winding moves down by 5% in turn at 1.3, 1.48, and 1.73 times the rated power respectively.

Optimal control of traction electric drives

The monograph considers various types of traction electric drives of motor vehicles intended for operation in urban conditions. Mathematical models of these systems are proposed. On the basis of parametric optimization and graphoanalytic method, a method of joint control of electric drives according to the criteria of minimum losses and maximum overload capacity, taking into account possible restrictions on the resources of power elements, has been developed. For a wide range of readers interested in improving motor vehicles. It will be useful for students, postgraduates and teachers of engineering and technical universities.

Investigation of adequacy of mathematical model of the „crane-load” system with frequency-controlled drive

In this work, experimental studies were conducted to evaluate the adequacy of the model of the „crane-load” system movement. For research, a laboratory installation (trolley with a load on a flexible suspension), a frequency converter, and encoders were used to measure the position of the trolley and the angle of deviation of the rope with the load from the vertical. Six experiments were performed by varying the duration of the increase and decrease of the frequency of the supply voltage of the trolley drive from 0.5 to 3 s. The increase and decrease of frequency voltage occurred according to a linear law. The data obtained during the experiments were compared with those that correspond to the mathematical model of the „crane-load” system. The mathematical model uses the Kloss equation, and also takes into account the change of frequency of the supply voltage of the drive from the condition of ensuring the overload capacity of the drive. Estimation of deviation of experimental data with results of numerical integration of mathematical model of the movement of the „crane-load” system was carried out based on the coefficient of variation (quantitative analysis) and graphic dependences (qualitative analysis). The obtained results showed the adequacy of the mathematical model of the motion of the „crane-load” system in the form of a system of nonlinear differential equations. Key words: mathematical model, dynamic system, frequency-controlled drive

Analisis Kerusakan Differential Pada Kendaraan HINO 260 FM (SH17) : Studi Kasus di PT. Hudaya Maju Mandiri

Differential or often known as the axle is a component in a car that functions to transmit engine power to the wheel axle that previously passed through the transmission and propeller shaft. Problems or damage to the differential varies, ranging from a buzzing sound in the differential, damage to the gear pinion, worn gear pinion, oil leakage in the differential. In this case, finding the differential is damaged in the pinion gear, the pinion teeth are worn and damaged so that the vehicle cannot run or the torque from the engine cannot be continued due to damage to the differential. The differential on the HINO 260 FM vehicle has a lot of damage to the differential, because the overload. Overload capacity or weight of the vehicle's payload exceed the standard limits and there is a differential damage in the pinion gear. Differential atau sering dikenal dengan nama gardan adalah komponen pada mobil yang berfungsi untuk meneruskan tenaga mesin ke poros roda yang sebelumnya melewati transmisi dan propeller shaft. Problem atau kerusakan pada differential bermacam-macam, mulai dari bunyi berdengung pada bagian differential, kerusakan pada gear pinion, gear pinion aus, kebocoran oli pada differential. Pada kasus kali ini, menemukan kerusakan differential pada bagian pinion gear, gigi pinion aus dan rusak sehingga membuat kendaraan tidak bisa berjalan atau tenaga putaran dari mesin tidak bisa diteruskan keroda akibat kerusakan pada differential. Differential pada kendaraan Hino 260 FM sering sekali rusak, dikarenakan daya angkut yang melebihi kapasitas. Dan hal inilah yang biasanya menjadi penyebab kerusakan differential pada bagian pinion gear.

Design and Applications of Controllable Magnetic Devices in Power Electronic Circuits and Power Systems

Magnetic components are characterized by high robustness and reliability. Controllable magnetic components, which used to dominate, have been out of fashion for about 50 years. However, they have great advantages in terms of longevity, radiation resistance and overload capacity and become smaller and smaller with increasing operating frequency. This makes them interesting in modern power electronics applications with the increasing use of WGB semiconductors. The article shows how the performance of power electronic converters can be improved with modern power electronics and with field-controlled magnetic components using modern magnetic materials. Keywords: Magnetic components; Passive components; Modelling; Magnetic amplifiers; Controllable filters;

Integrated Risk Assessment for Robustness Evaluation and Resilience Optimisation of Power Systems after Cascading Failures

Power systems face failures, attacks and natural disasters on a daily basis, making robustness and resilience an important topic. In an electrical network, robustness is a network’s ability to withstand and fully operate under the effects of failures, while resilience is the ability to rapidly recover from such disruptive events and adapt its structure to mitigate the impact of similar events in the future. This paper presents an integrated framework for jointly assessing these concepts using two complementary algorithms. The robustness model, which is based on a cascading failure algorithm, quantifies the degradation of the power network due to a cascading event, incorporating the circuit breaker protection mechanisms of the power lines. The resilience model is posed as a mixed-integer optimisation problem and uses the previous disintegration state to determine both the optimal dispatch and topology at each restoration stage. To demonstrate the applicability of the proposed framework, the IEEE 118-bus test network is used as a case study. Analyses of the impact of variations in both generation and load are provided for 10 simulation scenarios to illustrate different network operating conditions. The results indicate that a network’s recovery could be related to the overload capacity of the power lines. In other words, a power system with high overload capacity can withstand higher operational stresses, which is related to increased robustness and a faster recovery process.

Comparative analysis of analog parameters signal multi-pliers by differential transistor pairs

This paper is devoted to the comparative analysis of modern integral variables. Today, a number of foreign companies, such as Texas Instruments and Analog Devices, produce analog signal multipliers (APS) in integrated design. Russian industry produces chips of the 525PS and 174HA series. Each manufacturer uses its own method of implementing the device. The main task of such devices is to calculate the current voltage, phase, exponential and transcendental functions. Wide applicability of APS in integrated design was found in devices for analog processing and conversion of signals of communication and radio equipment, in devices for automatic control of onboard and ground radio equipment. A very important characteristic of such equipment is the dynamic range. The dynamic range of the receiver is the range of input signal amplitudes that provide the required quality of reproduction of the received message. The lower limit of the dynamic range is determined by the level of internal noise or external interference in the device, and the upper limit is determined by the device's overload capacity. In this regard, manufacturers of multipliers are faced with the task of maximizing the voltage that can be applied to its inputs. The difficulty is that the upper limit of the dynamic range is set by non-linear distortions. The non-linearity of the multiplier is a component of the multiplication error and characterizes the limiting capabilities of the APS inputs. In this paper, a comparative analysis of the main types of integral multipliers offered on the market is carried out in order to identify the best construction method for achieving the value of the dynamic range of the multiplier in 90 dB with high multiplication accuracy, which will allow using such a multiplier in modern radio equipment.

Аdaptive broadband low-noise RF amplifier

Adaptive broadband low-noise radio frequency amplifiers (ABLNRFA) are widely used in the construction of systems for protecting radio receiving paths from nonlinear damage in a non-stationary electromagnetic environment (EME). One of the promising focus areas on the creation of ABLNRFA is the development of devices in the class of circuits with switched networks. The creation of such devices has certain features, since, along with the need to ensure a low noise figure and digital control of the regulation characteristic, it is required to provide high linearity and a large dynamic range (DR) of the device. This paper presents the results of the logical-heuristic synthesis of ABLNRFA with an adaptively adjustable transducer gain, which changes due to switching of transformer feedback circuits. In order to check the functional and technical characteristics of the synthesized ABLNRFA and optimize its parameters, a model was developed and studied in the ADS environment. The proposed ABLNRFA technical solution provides a discrete (23, 14, 10 and 5 dB) wideband change in the transmission coefficient, while the DR for third-order intermodulation in terms of a 1 MHz band is 83, 92, 98 and 104 dB, respectively. A step change in the transducer gain in the circuit of the lossless feedback circuit developed by ABLNRFA avoids the accumulation of additional noise in the structure and provides a low-noise figure that does not exceed 1 dB. The technical characteristics of ABLNRFA allow one to adaptively increase the overload capacity of the radio receiving path with a proportional expansion of its DR in the conditions of non-stationary EME, and thus increase the efficiency of the level protection system against nonlinear damage to the receiving paths of radio communication, radar and radio navigation.