Frequency Changer Research Articles

Study on Interconnecting Operation Control of Electronic Frequency Converters for Shinkansen Realizing the Replacement of Rotary Frequency Changers

Study on Interconnecting Operation Control of Electronic Frequency Converters for Shinkansen Realizing the Replacement of Rotary Frequency Changers

INVESTIGATION OF THE STARTING CHARACTERISTICS OF AN ASYNCHRONOUS MOTOR FOR DRIVING A ROTOR-PULSATION APPARATUS USING A FREQUENCY CONVERTER

The method was used to carry out mathematical modeling for the follow-up of transitional processes during the start-up of an asynchronous engine to drive a rotary-pulsation apparatus for the preparation of water-grain feed for the clarity and frequency of the frequency changer. Mathematical modeling of transient processes during the start-up of an asynchronous electric motor for driving a rotary-pulsation apparatus for the preparation of liquid grain feed in the absence and presence of a frequency converter was carried out using the Matlab Simulink application program package. The following start-up parameters of the asynchronous motor were obtained: the current in the stator windings, the speed of rotation of the rotor and the electromagnetic moment on the motor shaft. The dynamic mechanical characteristics of the asynchronous motor during its start-up are obtained. A comparative analysis of simulation results with and without the use of a frequency converter was carried out. It is shown that the use of a frequency converter significantly improves the starting characteristics of an asynchronous motor.

A Direct Single-Phase to Three-Phase AC/AC Power Converter

The traditional DC-link indirect AC/AC power converters (AC/DC/AC converters) employ two-stage power conversion, which increases the circuit complexity along with gate driving challenges, placing an excessive burden on the processor while implementing complex switching modulation techniques and leads to power conversion losses due to the use of a large amount of controlled power semiconductor switches. On the contrary, the traditional direct AC/AC voltage controllers, as well as frequency changers, suffer from high total harmonic distortion (THD) problems. In this paper, a new single-phase to three-phase AC/AC step-down power converter is proposed, which utilizes a multi-linking transformer and bilateral triode thyristors (TRIACs) as power semiconductor switches. The proposed direct AC/AC power converter employs single-stage power conversion, which mitigates the complexity of two-stage DC-link indirect AC/AC converters and traditional single-stage AC/AC frequency changers. Instead of using high-frequency pulse width modulated gate driving signals, line frequency gate pulses are used to trigger the TRIACs of the proposed AC/AC converter, which not only aids in reducing the power loss of the converter but also mitigates the cost and complexity of gate driver circuits. The proposed AC/AC converter reduces the THD of the output voltage significantly as compared to traditional direct AC/AC frequency changers. The performance of the proposed AC/AC converter is validated against RL and induction motor load in terms of overall THD and individual harmonic components through MATLAB/Simulink environment. A reduced-scale laboratory prototype is built and tested to evaluate the performance of the proposed AC/AC power converter. The experimental and simulation outcomes reveal the feasibility and excellent features of the proposed single-phase to three-phase AC/AC converter topology.

Simulation of boost AC-AC converter using single-phase matrix converter

Generally, AC-AC converters are implemented using thyristors. These converters generate harmonics and have a low power factor. To eliminate these problems matrix converters (MC) are become used as AC-AC converter. Matrix converters have the capability of being used as frequency changer, rectifier, inverter and chopper. In this work, it is proposed to achieve the desired output of AC-AC Boost converter using single phase matrix converter (SPMC). The operation of single-phase AC-AC boost converter using MC is studied in this paper. The output voltage of this boost converter is higher than the AC input supply voltage. insulated gate bipolar transistors (IGBTs) are used as the switching elements in the SPMC power circuit. Sinusoidal Pulse width modulation (SPWM) technique is applied to generate switching signals to obtain the output voltage. The model of the matrix converter is constructed in MATLAB/Simulink programming software package. The behavior of SPMC is simulated with various switching frequencies. The simulation results together with harmonic spectrum and total harmonic distortion (THD) values are presented. Successful operation of boost SPMC is achieved.

Performance and characteristics of a hybrid induction motor with magnetic frequency changer

Performance and characteristics of a hybrid induction motor with magnetic frequency changer

Harmonic Analysis of Modular Multilevel Matrix Converter for Fractional Frequency Transmission System

Fractional Frequency Transmission is a competitive technology for offshore wind power transmission. Modular Multilevel Matrix Converter (M3C) plays a key role in a Fractional Frequency Transmission System (FFTS) as the frequency changer. M3C is broadly considered as the AC–AC converter for the future with its attractive advantages in high voltage and high power applications. Due to the lack of a DC link, electrical quantities at different frequencies from two AC systems couple in M3C, resulting in a complex harmonic condition. Harmonics can lead to stability issues and its analysis is of great importance. This paper focuses on the harmonic analysis of M3C. The arm capacitor voltage ripples and the harmonic currents are analyzed at various frequencies. Major factors influencing the harmonics magnitude are discussed. Analysis is conducted on sub-module capacitance and arm inductance selection. A zero-sequence current mitigation controller for M3C is implemented and tested. It is found that for a FFTS, some current harmonics flow into AC systems even though the system is balanced, while the others circulate within the converter. The theoretical harmonic analysis is verified by simulations in Real Time Digital Simulator (RTDS) of a M3C system where each arm consists of forty sub-modules.

A Hierarchical Energy Balance Control Method for M3C Based on Injecting Output Frequency Circulating Currents

This paper presents a simplified hierarchical energy balance control method for a modular multilevel matrix converter (M3C) operating as a frequency changer (50–50/3 Hz) for low-frequency ac transmission system. The proposed method employs an independent energy balance control for each subconverter of the M3C with only injecting the output frequency circulating current, aiming at balancing the energy among the three arms of the subconverter. Then, the modulation technique is redesigned to balance the energy among n submodules within each arm. The proposed method simplifies the computational complexity of the M3C by considering the subconverter independently, enabling an easy and efficient way to control the M3C. The feasibility of the proposed method is evaluated with normal and dynamic operation, which includes step changes in the output frequency and voltage. The performance and effectiveness of the proposed control strategy is demonstrated by extensive simulation studies and experimentally validated using a scaled-down laboratory prototype.

A Single-Phase Buck-Boost Matrix Converter with Low Switching Stresses

The suggested single-phase ac-to-ac matrix converter operated with inverting and noninverting characteristics may solve the grid voltage swell and sag problem in power distribution system, respectively. It is also employed as a direct frequency changer for domestic induction heating. The output voltage is regulated through duty cycle control of high frequency direct PWM (DPWM) and indirect PWM (IDPWM) switching devices. The DPWM control switches control the switching states of IDPWM switching devices. The inverting and noninverting characteristics are achieved with low voltage stresses and hence low dv/dt across the high and low frequency-controlled switches. This reduces their voltage rating and losses. The high voltage overshoot problem in frequency step-up operation is also analyzed. The sliding mode (SM) controller is employed to solve this problem. Pulse selective approach determines the power quality of load voltage. The validity of the mathematically computed values is carried out by modelling the proposed topology in MATLAB/Simulink environment and through hardware results.

Provision of ancillary services by renewable hybrid generation in low frequency AC systems to the grid

Wind energy high penetration levels in power systems lead to continuous power imbalance due to the intermittent nature of wind power. This paper proposes and investigates different methods to enable a hybrid generation system to provide frequency support to the grid. The hybrid generation is 100% renewable and composed of a wind farm and hydropower plant (HPP) of comparable generation capacities, and they are interconnected through a Low Frequency AC system (LFAC). The grid–tie is composed of a Voltage-Source Converter based High-Voltage, Direct Current (VSC-HVDC) junction that acts as frequency changer to maintain the grid nominal frequency. The HPP provides two types of ancillary services: wind power smoothing and frequency drops mitigation to avoid the use of thermal generation and battery energy storage. The paper offers different control methods to provide the two AS with improved coordination between the different controls in the hybrid generation system and complying with the common requirements of Grid Codes. The results obtained show that the frequency at the LFAC can tolerate mild drops to provide frequency support to the grid. The controllers’ parameters have a clear impact on the frequency response at both systems. Simulation environment is MATLAB and Simulink.

Performance Improvement of Single Phase Inverter using SPWM

This paper concentrates on modelling and simulation of single phase inverter as a frequency changer modulated by Pulse Width Modulation (PWM). An inverter is a circuit that converts DC sources to AC sources. Pulse Width Modulation is a method that utilization as an approach to abatement add up to harmonic distortion in inverter circuit. The model is executed utilizing MATLAB/Simulink software with the SimPower System Block Set in light of PC simulation. PC simulation assumes an imperative part in the plan, investigation, and assessment of force electronic converter and their controller. MATLAB is a successful instrument to examine a PWM inverter. Preferences of utilizing MATLAB are the accompanying: Faster reaction, accessibility of different simulation devices and utilitarian squares and the nonappearance of joining issues. Safe-replacement methodology need be actualized is to explain exchanging Transients. In this way, Insulated Gate Bipolar Transistor (IGBT) is use as exchanging gadgets. IGBT is ideal since it is anything but difficult to control and low misfortunes. The outcome from Simulink was checked utilizing MATLAB simulation.

Ac to Ac Frequency Changer THD Reduction Based on Selective Harmonic Elimination

AC to AC frequency converters had a challenge to be proposed as a reduction of THD. This challenge due to eliminate the most effective harmonics in frequency spectrum with low cost and no difficulty. However, the challenge is represented by producing new technique for AC to AC frequency changer with lower total harmonic distortion compared with regular AC to AC frequency changer. This proposed work introduces reduction based on eliminate the 3rd predominant harmonic by imposing a waveform with same frequency, amplitude and poly phase of presented harmful harmonic the elimination for the most effective harmonic will cause reduction in THD . The proposed technique gave a significant reduction in THD (about 52%) with respect to regular AC to AC frequency changer with low cost implementation requirements.

Steady state analysis of a three phase indirect matrix converter fed 10 HP, 220 V, 50 Hz induction machine for efficient energy generation

The matrix converter or pulse width modulated frequency changer, invented in the mid-1980s, is a direct power conversion device that can generate a variable voltage and frequency from a variable input source. Industrially, it is applied in adjustable speed control of induction motor drive, power quality conditioner, and traction applications. The aim of this paper is to evaluate the steady state characteristic behavior of an induction machine in terms of its speed and torque when driven by a three phase indirect matrix converter at reduced harmonics. Similarly, projecting an AC-AC matrix converter that ensures a uniform synchronization in frequency and voltage supplies between the three phase wound rotor machine and the transformer's grid voltage supply is discussed in the Scherbius scheme. The different methods of torque calculations pertaining to some selected machine circuit diagrams are presented for comparison and analysis. Emphasis on the torque-speed characteristics of the machine at varied resistance and slip values were graphically analyzed in MATLAB to determine the degree of torque-speed dependence on the rotor resistance and slip. The overall behavior of the machine under motoring, plugging, and regenerative modes was considered in this work, while a detailed Simulink modeling of an indirect matrix converter on the Scherbius drive scheme is also presented for further analysis.

Research on Cooling Control System of Flue Gas Based on Fuzzy Control

High-temperature flue gas in the factory has three features: high flow, strong corrosive and high temperature. It must be cooled to the rated temperature of different working conditions. There are nonlinear, time-varying issues and difficult to establish accurate mathematical model in the control of pump water quantity. We put PLC as the core to design the cooling control system which adjusts the pump water quantity by frequency changer based on fuzzy control theory.

Study on System Design Scheme for Electrical Control Scheme of Boiler

The breeding plumbing boiler is a full automatic temperature adjustment system with double efficacy of winter heating and summer cooling, constituted by host, auxiliary engine, control system and plumbing pipes, etc. Intermediate between PLC output port and AC contactor is to achieve the isolation between weak current and strong current, enhance the reliability of the system. Two frequency changers are designed for the hardware of system. Frequency converter input power linked up front access air switch. Frequency converter input terminals main circuit switch and the three phase power through air connection, frequency converter main circuit output terminals connected to the contactor three-phase motor. It is proved by field experimental operation that the control system proposed not only can realize automatic control of boiler burning process efficiently, but also reduced energy consumption greatly and effectively improved the level of boiler control management.

AWNIS: Energy-Efficient Adaptive Wireless Network Interface Selection for Industrial Mobile Devices

Mobile devices such as personal digital assistants (PDAs) and smartphones are widely used not only in our everyday lives but also in various industrial fields. Most of these mobile devices have multiple wireless network interfaces, such as Bluetooth, 3G, and Wi-Fi. A considerable amount of energy is consumed to transfer the data through wireless communication. Moreover, most of these mobile devices operate on limited battery power. In industrial environments, changes in the communication environment are severe due to significant noise sources and due to distortion in the transceiver circuitry of strong motors, static frequency changers, electrical discharge devices, and other devices. It is necessary to select the network interface efficiently in order to extend the lifetimes of mobile devices and their applications. Therefore, in this paper, we propose an energy-efficient adaptive wireless network interface-selection scheme (AWNIS). Our scheme is proposed based on the mathematical modeling of energy consumption and data transfer delay patterns. Our scheme selects the best wireless network interface in terms of energy consumption by considering the link quality and adapting a dynamic network interface-selection interval according to the network environment. The simulation results show that proposed scheme effectively improves the energy efficiency while guaranteeing a certain level of data transfer delay.

Power Frequency Converter Based on Integral-cycle Triggering Mode of Thyristors with Multi-control Periods

Conventional integral-cycle control was abandoned as an AC motor speed controller many years ago because the unbalanced sets of sub-harmonic and higher-order harmonic voltages generated by this type of control create severe problems for AC machines, causing excessive heat, mechanical vibrations, and noise. On the other hand, integral-cycle control has many advantages over phase-angle control as it generates fewer harmonics, reduces the electromagnetic interference, and possesses all the advantages of zero-voltage switching techniques. In the present work, an attempt is made to develop an integral-cycle control based power frequency changer using multi-conduction and multi-control periods that can compete with the conventional power frequency changers used to drive AC machines, such as inverters and cycloconverters. A comprehensive mathematical analysis for the generated voltage waveforms is carried out as well as a prototype experimental model of the frequency changer has been designed and built in the laboratory to investigate its performance with several types of load. The problem of phase unbalance associated with integral-cycle control when it is used with three-phase system is also studied, and an attempt is made to solve this problem by using different phase-angle triggering and phase-shifting techniques.

Research on Application of 36-Pulse Phase-Shifting Transformer to High-Voltage Frequency Converter

Abstract The power cell series multi-level high-voltage frequency converter is one of present electric power electron area research hot spots. This paper selected the power unit tandem type structure to realize the high-pressured frequency conversion, one of its biggest superiority was the input end uses the phase-shifting transformer to realize inputs the multi-densification, thus served the input output overtone small purpose. This paper also studies phase-shifting transformer's phase shifting principle emphatically, and designs 36 pulse wave phase-shifting transformer's related parameter, will provide the theory and the computation basis for the present phase-shifting transformer's design. Therefore, this paper provided the important reference and the instruction for next high pressure frequency changer's engineering design.

Single-Phase Voltage-Fed Z-Source Matrix Converter

This paper proposes a novel single-phase ac-ac converter topology based on the Z-source concept. The converter provides buck-boost function and plays the role of frequency changer. Compared to the traditional ac-dc-ac converter, it uses fewer devices, realizes direct ac-ac power conversion, and has a simpler circuit structure, so as to have higher efficiency and better circuit characteristics. Compared to the traditional matrix converter, it provides a wider voltage regulation range. The circuit topology, operating principle, control method and simulation results are given in this paper, and the rationality and feasibility is verified.

Autonomous AC Grid Based on Multi-infeed Voltage Source Converter Stations

It is desirable that remote isolated communities can become self-sufficient in electric power through harnessing energy from renewable energy sources. Taking advantage of the high controllability of voltage source converters, a scheme to realize a stand-alone AC grid for such an isolated community is examined. It uses voltage source converter stations as frequency changers. The multi-infeed voltage source converter design succeeds in the dual roles of maintaining the grid AC voltage while balancing real power generation and loads using local information only. The stability of the power system under the proposed control scheme, as affected by the control coefficients and operating conditions, is investigated. An analysis of eigenvalue sensitivity to control parameters is also included. Proof of the concept is carried by digital simulation studies.

An efficient algorithm for generalised single-phase converter

This paper describes the various common converters and illustrates the working principle of single phase matrix converter that shows a single topology capable of performing all function required in basic converter. An algorithm is developed that enables a single-phase matrix converter (SPMC) to perform functions of a generalised single phase power electronics converter such as acting as a frequency changer, rectifier, inverter and chopper. This reduces the need for new converter hardware. The algorithm is implemented on computer simulation software Orcad Capture CIS version 9.1. Simulation results are presented for all five types of converters with a control input variable that decides the 1) type of converter and 2) type of output waveform. The simulated results verify the working and operation of a generalised converter based on SPMC.