STUDY OF DYNAMIC MODES OF THE SPEED-OPTIMIZED ELECTRIC DRIVE CONTROL SYSTEM UNDER CONDITIONS OF ALTER THE DESIGN VOLTAGE AMPLITUDE

The relevance of the work is due to the need to adapt the methods of the theory of optimal control to modern technical capabilities. The complexity of optimization of control systems by variational methods led to the creation of the N–i switching method. It is characterized by the simplicity of the mathematical apparatus, however, certain methodological aspects encourage research aimed at improving this method with a focus on software implementation. The purpose of this study is to develop the mathematical apparatus of the N–i switching method by developing a technique for correcting the settings of cascade structure relay systems for speed control of electric drives, based on the use of empirically obtained data. To achieve this goal, the following tasks were solved in the work: the parameters of the mathematical model of the electric drive were calculated, on which a series of numerical experiments were performed under the conditions of varying the calculated amplitude of the voltage of the power converter, which made it possible to reveal a stable pattern of changes in the speed of the system depending on the coefficient of the calculated voltage; built a calibration diagram, which is designed to determine the correction factor in the entire range of speed control. The revealed regularity is based on the indirect influence of the varied parameters on the conditions of controllers switching, the moments of occurrence and the nature of their sliding modes. The result of the work is a method for correcting the parameters of relay controllers, which brings the duration of the speed control of the electric drive closer to the empirically set optimal value. Its implementation does not require the involvement of large additional resources and provides an improvement in the quality of transient processes. The empirical component of the proposed optimization method consists not in the direct selection of one of the key parameters of the system, but in the preliminary refinement of the initial data, which is effective within the used synthesis method. The prospect of this study is an analytical solution to the problem of determining the correction coefficient, which will contribute to the practical application of the proposed optimization algorithm.

A High Gain AC-DC Rectifier Based on Current-Fed Cockcroft-Walton Voltage Multiplier for Motor Drive Applications

This paper proposes a novel high-gain AC-DC converter based on the Cockcroft–Walton (CW) voltage multiplier which can be utilized in motor drive systems with low input voltage. In this topology, use of the voltage multiplier and boost circuit results in the increment of converter gain which has a significant impact on the cost and efficiency of the system. Moreover, in this converter, the AC voltage is directly changed to DC voltage using the switching method in high frequency and, as well, the power factor is corrected. Besides, this high-frequency converter contributes to the reduction of output ripple. On the other hand, cost efficiency, the low voltage stress on capacitors and diodes, compactness, and the high voltage ratio, are achieved from the Cockcroft–Walton circuit. Furthermore, the hysteresis method is presented for converter switching to correct the power factor. The converter is simulated in MATLAB software to demonstrate the effectiveness of the suggested method. Lastly, a laboratory prototype of the suggested converter is built, several tests are done in order to verify the theoretical analysis, and comprehensive comparison with the state-of-the-art converter is done.

Solar Hybrid Hatching Machine Applying a Thermal Accumulator with a Reflective Array Method

In this research, a hybrid egg hatcher machine applied two types of energy for heating, namely solar thermal energy and an electric (fossil) heater. Solar energy was the main energy, and the electric heater was the secondary energy. This hybrid system was related to Indonesian geography, with high solar energy of an average of 5 kWh/m2/day in one year. Therefore, solar thermal energy storage will be effectively used in Indonesia to reduce fossil energy exploitation. The solar thermal energy was stored in an accumulator with a 4 m2 collector. The solar thermal accumulator was an insulated vessel with high reflectivity and insulation. The heat energy was stored and kept in some water bars. In maximizing absorption capability, the collector used a reflective array method that was operated by opening or closing the arrays. The arrays were controlled by an electronic controller, which compared the thermal energy inside with the energy of sunlight. The array’s movement to charge the accumulator was done automatically by using the hysteresis switching method. The electric heater will be used only if the accumulator temperature is less than 40 °C. The capacity of the egg hatcher machine accumulator was 300 eggs. Raw data were collected using a data logger of DAQ (Data Acquisition Interface) DT9813 to determine and analyze the performance of system parameters. From the data collected, the solar thermal accumulator showed its capability for storing thermal energy up to 7.07 kWh. However, its average absorption efficiencies were 54–58 % by direct solar and 60–70 % by diffuse solar. Experiments verified the effectiveness of the designed accumulator. The experimental results showed that the electrical energy consumption was reduced up to 64 %.

A 3D head pointer: a manipulation method that enables the spatial position and posture for supernumerary robotic limbs

This paper introduces a novel interface ‘3D head pointer’ for the operation of a wearable robotic arm in 3D space. The developed system is intended to assist its user in the execution of routine tasks while operating a robotic arm. Previous studies have demonstrated the difficulty a user faces in simultaneously controlling a robotic arm and their own hands. The proposed method combines a head-based pointing device and voice recognition to manipulate the position and orientation as well as to switch between these two modes. In a virtual reality environment, the position instructions of the proposed system and its usefulness were evaluated by measuring the accuracy of the instructions and the time required using a fully immersive head-mounted display (HMD). In addition, the entire system, including posture instructions with two switching methods (voice recognition and head gestures), was evaluated using an optical transparent HMD. The obtained results displayed an accuracy of 1.25 cm and 3.56° with the 20-s time span necessary for communicating an instruction. These results demonstrate that voice recognition is a more effective switching method than head gestures.

Independent Upper- and Lower-Arm Switching Scheme Based on Reference Current Polarity for Three-Level NPC Inverters

This study presents a novel switching scheme for three-level neutral point clamped (NPC) inverters. The proposed switching method independently drives the upper- and lower-arm elements of the inverter based on the polarity information of the reference current. The proposed switching scheme does not require the inclusion of dead-time for each switching, except when the current polarity changes. Therefore, unlike the conventional inverter switching method, dead-time compensation is not needed, and the possibility of an arm-short accident is prevented. In this study, a switching procedure is detailed, and the operation mode analysis of the proposed switching scheme is presented. The effectiveness of the proposed switching method is verified experimentally by application to a grid-connected inverter that requires inverter current control.

A Two-Channel High-Performance DC-DC Converter for Mobile AMOLED Display Based on the PWM–SPWM Dual-Mode Switching Method

In this paper, we propose a design of a two-channel high-performance DC-DC converter that provides a positive voltage VPOS with a low ripple, and a negative voltage VNEG with high power efficiency, for the purpose of enhancing power efficiency and output ripple under light loads of 100 mA or less for mobile active-matrix organic light-emitting diode (AMOLED) displays. The VPOS was designed as a boost converter using a novel input voltage variation reduction circuit (IVVRC), which rapidly changes the pulse width for input voltage fluctuations, using a feed-forward path. The VNEG was designed as an inverting buck–boost converter based on the pulse width modulation–set time variable pulse width modulation (PWM–SPWM) dual-mode switching method to enhance power efficiency, especially under light loads, and to reduce the overhead of the circuit configuration using a voltage-controlled oscillator. In addition, an adaptive dead-time using voltage detection of switching node (ADTVS) circuit was proposed to enhance power efficiency, which detects the voltage of the switching node at every cycle, and keeps the dead-time constant irrespective of changes in driving conditions. The proposed converter was fabricated with a chip size of 1.67 mm × 2.44 mm, using a 0.35 μm BCD process. Measurement results showed that the power efficiency of our converter was 72.9%~90.4% at 5 mA–100 mA light load output current, which is 2.7%~5.8% higher than the output of the previous converter. Furthermore, the output voltage ripple of VPOS and VNEG at 5 mA light load output current was 3.0 mV and 5.3 mV, respectively, which improved by 19% and 25% as compared to those of the previous converter, respectively.