Study on the "Phase Hopping" AC-AC Frequency Conversion Method with Approximately Continuous Frequencies

2020 ◽  
Vol 13 (8) ◽  
pp. 1217-1226
Author(s):  
Zhengwang Xu ◽  
Guozhuang Jiang ◽  
Ke Kun ◽  
Yuchun Yi
Keyword(s):  
Output Voltage ◽  
Frequency Conversion ◽  
Frequency Control ◽  
Actual Application ◽  
Power Frequency ◽  
Voltage Frequency ◽  
The Law ◽  
Large Cycle ◽  
Selection Of ◽  
Conversion Technology

Background: The output voltage frequency for the previously proposed "phase hopping" AC-AC frequency conversion technology is determined by the law that the number of output voltage cycles is reduced by one relative to the power frequency in a large cycle containing six jumps. According to the law, only a limited number of output frequencies, such as 37.5 Hz, 42.86 Hz and 45 Hz are found. Due to the large spacing between the output frequencies, the "phase hopping" frequency conversion technology is difficult to put into practical use. Methods: In this paper, the law of the output frequency control is generalized so that the number of output cycles in a large cycle is reduced by n relative to the power frequency. The analysis shows that the appropriate selection of large cycles, including the number of power frequency cycles and the value of n, can find more frequencies to be used. Reducing the interval between the output frequencies within 1Hz. Results: The analysis results were verified in simulation by MATLAB, and the harmonics and the feasibility of the actual application were analyzed. Conclusion: Finally, an experimental platform was built and an experimental analysis was carried out. The experimental results show that the theoretical and simulation analyses are correct.

scholarly journals Power Quality Analysis of the Output Voltage of AC Voltage and Frequency Controllers Realized with Various Voltage Control Techniques

2021 ◽  
Vol 11 (2) ◽  
pp. 538
Author(s):  
Naveed Ashraf ◽  
Ghulam Abbas ◽  
Rabeh Abbassi ◽  
Houssem Jerbi
Keyword(s):  
Power Quality ◽  
Output Voltage ◽  
Frequency Control ◽  
Voltage Control ◽  
Voltage Regulation ◽  
Quality Analysis ◽  
Control Technique ◽  
Control Techniques ◽  
Power Quality Analysis ◽  
Selection Of

Single-phase and three-phase AC-AC converters are employed in variable speed drive, induction heating systems, and grid voltage compensation. They are direct frequency and voltage controllers having no intermediate power conversion stage. The frequency controllers govern the output frequency (low or high) in discrete steps as per the requirements. The voltage controllers only regulate the RMS value of the output voltage. The output voltage regulation is achieved on the basis of the various voltage control techniques such as phase-angle, on-off cycle, and pulse-width modulation (PWM) control. The power quality of the output voltage is directly linked with its control techniques. Voltage controllers implemented with a simple control technique have large harmonics in their output voltage. Different control techniques have various harmonics profiles in the spectrum of the output voltage. Traditionally, the evaluation of power quality concerns is based on the simulation platform. The validity of the simulated values depends on the selection of the period of a waveform. Any deficiency in the selection of the period leads to incorrect results. A mathematical analytical approach can tackle this issue. This becomes important to analytically analyze the harmonious contents generated by various switching control algorithms for the output voltage so that these results can be successfully used for power quality analysis and filtering of harmonics components through various harmonics suppression techniques. Therefore, this research is focused on the analytical computation of the harmonics coefficients in the output voltage realized through the various voltage and frequency control techniques. The mathematically computed results are validated with the simulation and experimental results.

scholarly journals Performance and Tracking Control of Three-Phase Induction-Motor Drive Fed from a DC-Modified Nano-grid

2021 ◽  
Vol 16 ◽  
pp. 8-21
Author(s):  
Essamudin Ali Ebrahim ◽  
Abuelmaaty M. Ali
Keyword(s):  
Induction Motor ◽  
Output Voltage ◽  
Low Voltage ◽  
Reference Model ◽  
Frequency Control ◽  
Simple Algorithm ◽  
Duty Ratio ◽  
Three Phase ◽  
Voltage Frequency ◽  
Two Parameters

Nowadays, induction motor (IM) can be used in tracking systems to follow a predefined path like in robotics and servos. The modified nanogrid is a small scalable-renewable energy intermittent source that powers loads via a single-stage inverter (SSI). Higher utilization of the inverter dc-link voltage improves its output voltage and dependently, the performance of the motor tracking speed. So, this paper proposed a switched boost inverter (SBI) to feed IM from PV-source to boost its dc-link output voltage. The usage SBI utilizes minimum passive components, more active elements, introduces shot-through mode as z-source inverter and produces both ac and dc voltages simultaneously. The performance of the motor-tracking speed depends directly on the motorstator voltage. So, the proposed method depends mainly on two parameters to verify the pre-defined trajectory speed. The first proposed intention is a simple algorithm for a closed-loop dc-link boosting control based-on the reference model to compute the optimum duty ratio (D). The second one depends mainly on the modulation index (M) to produce the reference signals needed to adjust the speed of the motor through a (voltage/frequency) control of a predefined value. The modelling and validation of the proposed system was implicit with the help of Matlab/ Simulink package. The robustness of the system has been tested by selecting several speed trajectories and was able to track them. Furthermore, SBI-based system was compared with other VSI-inverter techniques such as the space-vector PWM single- and two-stage VSI inverters. Test results explored that the SBI-based system is a strong competitor to other inverter techniques especially at low-voltage intermittent supply.

scholarly journals Analysis and Implementation of a Frequency Control DC–DC Converter for Light Electric Vehicle Applications

Electronics ◽  
2021 ◽  
Vol 10 (14) ◽  
pp. 1623
Author(s):  
Bor-Ren Lin
Keyword(s):  
Electric Vehicles ◽  
Output Voltage ◽  
Frequency Control ◽  
Input Voltage ◽  
Pulse Frequency ◽  
Switching Frequency ◽  
Battery Charger ◽  
Dc Microgrid ◽  
Load Voltage ◽  
Transportation Vehicle

In order to realize emission-free solutions and clean transportation alternatives, this paper presents a new DC converter with pulse frequency control for a battery charger in electric vehicles (EVs) or light electric vehicles (LEVs). The circuit configuration includes a resonant tank on the high-voltage side and two variable winding sets on the output side to achieve wide output voltage operation for a universal LEV battery charger. The input terminal of the presented converter is a from DC microgrid with voltage levels of 380, 760, or 1500 V for house, industry plant, or DC transportation vehicle demands, respectively. To reduce voltage stresses on active devices, a cascade circuit structure with less voltage rating on power semiconductors is used on the primary side. Two resonant capacitors were selected on the resonant tank, not only to achieve the two input voltage balance problem but also to realize the resonant operation to control load voltage. By using the variable switching frequency approach to regulate load voltage, active switches are turned on with soft switching operation to improve converter efficiency. In order to achieve wide output voltage capability for universal battery charger demands such as scooters, electric motorbikes, Li-ion e-trikes, golf carts, luxury golf cars, and quad applications, two variable winding sets were selected to have a wide voltage output (50~160 V). Finally, experiments with a 1 kW rated prototype were demonstrated to validate the performance and benefits of presented converter.

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