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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...
This paper presents an analytical solution for predicting switching performances of a forward power converter with insulation transformer. We will calculate the circuit wave-forms and especially those which concern the transistor, in relation to the parameters of the adopted converter.
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.
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...
The active power filter is the harmonic filter which suppresses the ac harmonics by injecting PWM compensating current into the ac side. The novel model of PWM compensating current Is derived from the optimized injection method. By injecting the derived PWM current, the ac harmonics up to the order of the modulation number are eliminated. With no external source it is possible to build up the inductor...
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...
In recent years there has been paid much attention to the development of computer aided methods in analysis and design of power electronic circuits because the recent advances of switching power semiconductor devices. In this paper we propose a new and efficient computer aided algorithm for computing parameter sensitivities of turn-on and turn-off instants of power semiconductors for any given power...
Small-signal model of coupled-inductor Ćuk converter including parasitic minding resistances is derived, and its essential network functions are presented. The basic model is transformed into an easy to use simplified form with analytic expressions for the zeros and poles locations. The dynamic properties of two practically important cases of inductor coupling are discussed and conditions for minimum-phase...
Improved efficiency, better steady-state performance, and reduced complexity were the objectives set for a new control system for reciprocating linear motors. The control system comprises a low-frequency tri-state switching circuit, a linear motor, and an axial position sensor along with three distinct feedback loops (peak-amplitude feedback, average-position feedback, and phase feedback). The system...
Algorithms and techniques are presented to tailor the values of circuit elements in fixed-topology circuit models to match data measured from physical inductors and capacitors. Measurements from several types of capacitors and inductors are used to illustrate the results as applied to models of differing complexity.
The concept of resonant switch has been extended to generate a family of new quasi-resonant converter topologies. The converter circuits feature zero-current switching and are particularly suited for high-frequency (MHz) power-conversion applications.
The basic circuit of a push-pull parallel resonant converter with an input inductor is analyzed for the continuous conduction mode and the discontinuous conduction mode concerning the output-inductor current. It is found that the output voltage of this resonant converter is controlled by varying the switching frequency in the discontinuous conduction mode, while another power controller is required...
The application of GTO-thyristors requires special short-circuit protection equipment. A simple method based on the proportionality of turn-off current and storage time of a GTO is shown to protect GTO-thyristors against turn-off failure during a short circuit. Additionally, this method can be employed for overload protection, failure diagnosis and current monitoring.
With the introduction and wide acceptance of gate turn off power devices (e.g. Bipolars, Power Fets, GTO's, etc.), the switching behavior of converters has reached the point where further improvements in firing and switching networks bring only marginal benefits. Consequently, the research interests in the area of static converters have been shifting toward improving the process of power conversion...
This paper describes a control scheme of a high frequency, high power current source inverter using static induction transistors to suppress the surge voltage and to reduce the switching loss during the commutation of current. The inverter is operated at a leading power factor, which requires the phase angle of the output current to be adjusted to each specific load point by the controller. The stable...
In this article an analytical method for calculating the conducted interference voltages of the three basic ac-dc converters buck, boost and buck-boost with sinusoidal input current and unity power factor is presented. The analysis includes a simulation of the quasi-peak measurement according to CISPR (Comité International Spécial des Perturbations Radioélectriques). The influence of the different...
It is shown that internal low-frequency energy storage can be used to achieve harmonic-free operation and controllable power factors in converters whose desired operations require unequal instantaneous input and output powers, such as in single-phase rectifiers, inverters, cycloconverters, and reactive power generators. A systematic synthesis and analysis technique is developed for such converters...
The validity of applying state-space averaging and linearization to the control law of current-injected switching regulators for designs with wide-band, first-order, open-loop responses without RHP zeroes is verified. Quantitative closed-loop performance comparisons are made of current-injected versus voltage control for the boost and buck switching regulator topologies.
The open-loop-gain of PWM voltage regulators at f = 0 can be expressed by simple formulae that are derived in this paper by means of charge and energy balances and the Campbell theorem. The three basic circuit topologies (Buck, Boost, Buck-Boost) are analysed both in the conventional duty-cycle control mode and in the current control mode. As each circuit can work either in the continuous or in the...
Power converters with free-running current-mode control (hysteretic, constant-“off”- time, or constant-“on”-time) can be frequency-stabilized or can be synchronized to a reference frequency. Those can by accomplished by feedforward, feedback, or phase-locking techniques. With hysteretic control, the frequency is controlled by varying the current hysteresis. With constant-“off”-time or constant-“on”-time...
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