Electromagnetic
A. Nejadmalayeri; P. Yousefi; M. Safaei
Abstract
Background and Objectives: The speed sensor is one of the main components of the control and monitoring systems of rotational machines which is widely used in the aviation industry, railway, and automotive applications. Variable Reluctance Speed sensor (VRS) is a kind of magnetic sensor that has been ...
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Background and Objectives: The speed sensor is one of the main components of the control and monitoring systems of rotational machines which is widely used in the aviation industry, railway, and automotive applications. Variable Reluctance Speed sensor (VRS) is a kind of magnetic sensor that has been traditionally employed for many different industrial measurements because of several well-known advantages, such as passive nature, non-contact operations, robustness, low cost, low sensitivity to dirt, and large-signal output.Methods: In this paper, a variable reluctance speed sensor is proposed. The design process of the proposed sensor is presented and both the magnetic and electrical models of this sensor are derived by assuming the effect of magnetomotive force caused by eddy current formed on the outer edge of the target gear at high frequencies. As a result, the proposed model can demonstrate the performance of the variable reluctance speed sensor at high frequencies very well.Results: The proposed VRS is designed and simulated using MATLAB and Ansys Maxwell software to verify the theoretical results is constructed and tested.Conclusion: In this paper, a variable reluctance speed sensor is proposed and studied. The magnetic and electrical models of the proposed sensor are derived and the output voltage equation has been calculated as a function of the air gap length. The proposed VR sensor is simulated using 2D Finite Element Analysis software to identify the main parameters that influence the sensor output and also to verify the accuracy of the model. According to the simulation results, the output waveform quality will be affected by parameters such as air gap length, target gear material, the self-inductance of the VR sensor, and the load component values. In terms of the electrical model, we were able to simulate the effect of load resistance and capacitance on the sensor output.
Pulsed Power
A. Nejadmalayeri; H. Bahrami; َA. Bali Lashak; I. Soltani
Abstract
Background and Objectives: Dielectric Barrier discharge (DBD) is a suitable method to generating Non-thermal plasma at atmospheric pressure, which utilizes Pulsed power supplies as exciters. Increasing pulse voltage range and frequency and compactness are important issues that should be taking into consideration.Methods: ...
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Background and Objectives: Dielectric Barrier discharge (DBD) is a suitable method to generating Non-thermal plasma at atmospheric pressure, which utilizes Pulsed power supplies as exciters. Increasing pulse voltage range and frequency and compactness are important issues that should be taking into consideration.Methods: The high voltage pulse generators which are introduced in the literature have some disadvantages and complexities such as need of additional winding to reset the transformer core and operating under hard switching which increases electromagnetic noise and loss. The leakage inductance of the high voltage transformer increases the rise time of the pulse which is undesirable for DBD applications. The energy stored in the leakage inductance causes the voltage spike across the switch, witch necessitates the use of snubber circuits. The main contribution of this paper is a new high voltage pulse generator with the following characteristics, 1) a capacitor is paralleled with the main switch to reset the transformer core and to provide the soft switching condition for the switch. 2) The resonant charging technique is used which doubles the secondary winding voltage which reduces the turns ratio of high voltage transformer for a certain output pulse peak. 3) The sharpening circuit using magnetic switch produces a sharp high voltage pulse.Results: The proposed high voltage pulse generator is designed and simulated using Pspice software. To verify the theoretical results, a prototype with the input voltage 48 V, the output voltage pulse 1.5 kV, and the rise time of the output pulse 50 ns is constructed and tested.Conclusion: This paper proposes a new pulse generator (PG). The proposed PG uses three techniques named forward, resonant charging, and magnetic switch to produce a high-voltage nanosecond pulse. The resonant charging double the secondary voltage of the pulse transformer, which causes reduction in turn ratio of the pulse transformer and decreases the weigh, volume, and price of the PT. The magnetic switch section finally produces a nanosecond high-voltage pulse. The magnitude of the output pulse can be varied using the input source voltage, the MS reset current and the duty cycle. The core of the pulse transformer resets by using a capacitor paralleled with the switch and the PG does not need any additional reset winding like the conventional DC-DC forward converter.
