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In the paper energy transmission system which transmits the energy from lower voltage AC network to higher voltage AC network is presented. The system contains the DC link subsystem. It is proven that step up chopper used in DC link subsystem decreases the inverter reactive power from AC network. The AC/DC/AC subsystem is used with synchronous generator system and in rotor circuit of slip-ring induction...
A new harmonic current compensator composed of a static power converter was developed. It is composed of two voltage-type inverters in a multiplex configuration, this new compensator has a number of features that make it superior to the conventional passive filter composed of an AC reactor and a capacitor. This paper describes the principle of harmonic current compensation, the capability which the...
A cycloconverter with a tank circuit for induction heating which can deliver power to load keeping an input displacement factor at 1.0 is proposed in this paper. Static characteristics are analyzed using the switching functions and the mode functions and operation regions in which the input displacement factor is kept at 1.0 are found. A starting method which uses only a gate pulse sequence for thyristors...
The active and reactive load distribution between n paralleled single-phase UPS inverters is equalized by virtue of n − 1 load sharing control loops. The approach permits the construction of UPS systems of any desired power rating at maximum utilization of the power components. The method of harmonic cancellation decreases the switching frequency of the power devices while maintaining good dynamic...
A line current modulated high-frequency (hf) link dc to utility interface power conditioning system using a square-wave output resonant inverter is proposed. The proposed system consists of a square wave output hf resonant inverter, a rectifier and a line connected inverter. The system is modeled using Constant current model for the high-frequency inverter and Step model for the dc link current. The...
The modeling, analysis and design of a high-frequency resonant converter using LCC type commutation circuit is presented. Constant current model and State space approach are used for the analysis. Closed form solutions are derived for the inverter under steady state conditions. Experimental results obtained from a prototype converter under different loading conditions are compared with the theory.
In this article, the authors present the design and realisation of a DC/AC inverter. The power cell described is reversible and thus enables the handling of highly reactive loads. A state variable feed-back study leads to the large signal mastery of the power cell. The adaptation of the feedback loop for load variations and source voltage variations are also considered. The article concludes with...
An improved PWM inverter waveform synthesis technique for harmonic control in delta modulation (DM) process is presented. Filtering approach is incorporated in the DM technique to reduce harmonics of lower frequencies and suppress the unwanted subharmonics. Analytical method is described to determine the performance of multistage delta modulated inverter and the results are substantiated by experimental...
Almost all PWM converters using bipolar transistors experience the problem of reverse transistor conduction. This effect is analysed for various types of base drive. It is shown to be most serious for low impedance direct drives. A mathematical model is developed for this case and verified experimentally. Problems associated with turn-on and turn-off in the reverse conduction mode are investigated.
The paper presents a novel analysis of the harmonic content of current, torque pulsations and harmonic copper losses of a three phase induction machine fed by a two phase PWM inverter. The purely analytical results are based on the assumption that the switching frequency is high compared with the fundamental frequency. However, it turns out that the results hold for frequency ratios fs/f1 > 9.
This paper deals with the realization technique that optimizes the flux level to improve the efficiency of an induction motor. When harmonics and saturation effects are considered, the slip of minimum loss, or optimal slip, depends both on the speed and on the load torque. The measurements of speed and torque are achieved with motor terminal quantities dispensing with conventional torque and speed...
Two identical 3-phase, bipolar transistor, controlled-current, PWM power modulators are integrated so that one functions as a rectifier and the other as an inverter in an ac drive system. The rectifier input currents maintain near 60 Hz sinusoidal waveforms with unity power factor. Leading power factor option is available. The modulators do not depend on the availability of bidirectional switch elements...
The goal of the field orientated control principle for inverter fed asynchronous machines, is to control the torque of the machine and the flux inside the machine independently from each other.
Generalized root-loci techniques, developed in the mid-70's for squirrel cage motors, have been extended to wound rotor, slip energy recovery systems (static Scherbius drive). In this paper, the influence of a feedback control loop on these root-loci is considered. General conclusions on Scherbius drive dynamics as well as some experimental verifications are also included.
A new control technique based on deadbeat control theory is proposed to obtain a nearly sinusoidal PWM inverter output voltage using only a voltage sensor. The closed loop sampled-data feedback scheme inherently results in very fast response to load disturbance and nonlinear load, producing low total harmonic distortion. Parameter estimation of the plant provides a type of self-tuning of the proposed...
Generating torque in starting of self-controlled synchronous motor is analyzed, and the developed method of torque measurement using the space rotating current vector is described. A self-controlled synchronous motor known as a commutatorless dc motor, consists of a synchronous motor with a shaft position sensor and a inverter switched by the pulses from the position sensor. The inverter frequency...
A promising approach regarding variable-speed fractional horse power drives consists in the use of a capacitor-run motor driven by D-modulation PWM inverters. A drive of this kind is not only cheap and reliable but allows also an easy implementation of the required linear relationship between the drive voltage frequency and amplitude. This paper proposes a simulation procedure for such systems that...
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