Saturable Reactor Research Articles

A Nonconventional Amplistat Configuration

Circuits comprising saturable reactors driven into negative saturation offer very interestingpossibilities from both the theoretical and practical points of view.

Current Regulators for Large Rectifier Power Supplies Used on Electrochemical Processing Lines

Typical large silicon rectifier dc power supplies for electrochemical lines have ratings of 20 000 to over 300 000 amperes, at voltages of 50 to 1000 volts. The operating efficiency of such installations is of major economic importance, and experience has shown that the use of high-accuracy current regulation can substantially improve efficiency. Regulation is required to compensate for ac supply fluctuations and electrochemical cell or potline characteristics variations. Underload tap changing transformers provide an economical and highly efficient means of varying the rectifier dc output voltage. Control resolution, however, is relatively limited due to the finite voltage steps between taps, and precautions must generally be taken to avoid unnecessary tap changer operations in order to achieve reasonable operating periods without contact maintenance. Several techniques for achieving high-accuracy current regulation with tap changer controlled silicon rectifier power supplies are described. One approach utilizes partial range saturable reactors to provide vernier control between tap changer steps and a fast response feedback amplifier-driver to give essentially continuous high-accuracy (0.1 to 0.5 percent) current regulation. Another method controls the tap changer by means of an error integrating or reset amplifier technique which ignores minor short-tenn current fluctuations but maintains the average value over several hours of operation to within a fraction of a percent of the preset value.

Polarized and non-polarized saturable reactors

The present paper analyses the performance of the saturable core with and without external polarization. For the circuit without external control, positive and negative saturation are discussed; for the circuit with d. c. excitation three cases are pointed out: underexcitation; critical ecxitation and overexcitation. The various saturation and desaturation angles are computed and their physical meaning is discussed along with the relevant explanations pertaining to current amplification. Experimental results are quoted.

A Negative Impedance Transformer

In previous papers, the authors have described the principle of ``negative'' saturation and its practical applications. The main difference between circuits comprising saturable reactors driven into negative saturation on the one hand, and magnetic amplifiers on the other, is that in the former power current flows during the nonsaturation periods of the core (or cores), whereas in the latter it only flows when the core is saturated. In this paper, ``negative'' saturation is used as a means of obtaining a negative voltage-current characteristic. This characteristic, obtained by means of a suitable antiparallel saturable reactor configuration, resembles that of the tunnel diode, with the fundamental difference that in the latter electrons ``tunnel'' a potential barrier, whereas in the described circuit the negative slope is due to flux-resetting requirements.

Thyristor converters using saturable reactors

The dc to ac and ac to ac series converters have been discussed in earlier publications.[1]-[3] These systems are used with minimum component ratings at a fixed load resistance and a fixed output frequency.[1] The ranges of operation of the load and the frequency can be increased by using saturable reactors and variable capacitors. These systems are analyzed and the preferred operating conditions are discussed. Theoretical results are supplemented with the experimental results.

New detecting means with lead characteristics in carrier-type control system

In a carrier-type control system, necessary operation usually is conducted after demodulating a modulated actuating signal once to a dc signal. This demodulation undesirably retards a signal. Using a general principle, the value of a modulated signal can be determined during a half-cycle of a carrier wave. A reactor with a rectangular magnetization loop can easily integrate a voltage, add or subtract a flux change and a voltage integral, and store this information. In this paper, a circuit is described employing saturable reactors; an error can be measured during a half-cycle, and a large output corresponding to the (proportional plus derivative) value of an error can be obtained.

A Study of Saturable Reactor Performance by Analog Computer

A Study of Saturable Reactor Performance by Analog Computer

A reliable high-powered constant current supply

The use of series-connected saturable reactors operating in the constrained mode has proven to be a reliable and trouble-free means for developing constant current power such as that required by transoceanic cable systems. As the art has progressed towards the use of higher and higher ac power frequencies, however, it has become increasingly difficult to design a single ac power source of substantial power rating without resorting to rather complex and inefficient circuitry. In practice, the saturable reactors are used in conjunction with transformers. This paper demonstrates that by departing from convention in the design of the saturable reactor and output transformer, it is possible, using a single reactor and transformer, to combine the outputs from a multiplicity of ac power sources or converter stages on a load sharing basis so as to obtain a single supply with the required power rating. The particular arrangement of the specially designed saturable reactor and output transformer permits a unique interaction to be established in which the two complement one another; the reactor controlling the summation of source currents to achieve output regulation and the transformer proportioning these currents among the sources to insure proper sharing of load power. Variations in load power are automatically accompanied by a shift in the operating power factor of the individual sources. Also, because the method affords electrical isolation, sources of unequal current, voltage, and power ratings can readily be combined. Furthermore, this technique permits the use of excess (redundant) ac sources so that normal operation can be maintained following the loss of output from any one of the sources.

Voltage Conversion and Regulation Techniques Employed in the Prime Converter for the Anchored Interplanetary Monitoring Platform (AIMP) Spacecraft

This paper describes the major design concepts considered in the development of a DC to DC prime converter for the Anchored Interplanetary Monitoring Platform (AIMP) Spacecraft. This static converter is used to transform the power from the solar array and battery into suitable levels for the instrumentation and experiment electronics. The design approach chosen incorporates a duty cycle switching pre-regulator controlled by saturable reactors, a DC to DC converter synchronized at the basic operating frequency of the pre-regulator, and series dissipative regulators exhibiting short circuit protection. A breakdown of the power losses in the pre-regulator is presented. Of particular note are the procedures followed to achieve a low magnetic field disturbance.

An analysis of the frequency tripler

This paper deals with an analysis of the fundamental circuit of a frequency tripler, constructed with saturable reactors. In the analysis, the equation of the circuit is directly obtained by using the approximate expression of the characteristics of the reactor cores. The mechanism of the tripler is quantitatively analyzed by the solution and its criterion. The results of the analysis are in excellent agreement with the experiment.

Thyristorwechselrichter mit sättigbaren drosseln fü mittelfrequenzanwendungen

The frequency, which can be attained with conventional static inverters, is limited by the turn-off time of the controlled rectifiers. Resonant circuit inverters with controlled rectifiers and saturable reactors in combination make it possible to generate frequencies whose half-wave duration is equal to or less than, the turn-off time of the controlled rectifiers. When using thyristors for this purpose, resonant circuit inverters can be built for frequencies up to about 25 kc. The inverters described in this paper are suited as medium frequency generators for inductive heating purposes. In this case the inductor coil is a component of the resonant circuit. The workpiece is heated up by an effective frequency much higher than the frequency with which the thyristors are fired.

Improved multiple core transformer inverter with TRC regulation via external variable volt-second saturable reactor

Design of a polyfunction inversion device is described together with pertinent equations required for its development. The low-voltage converter under consideration was developed with switching drive power proportional to load current, utilizing multiple core techniques. Driven power transistors were used to rectify the output of the inverter-regulator to maintain system efficiency. Regulation was provided by using variable volt-second techniques which were external to the power transformer, permitting the power transformer to be fabricated from semi-square low-loss core material.

The Six Modes in Three-Phase Series-Type Saturable Reactor without Auxiliary Winding

The Six Modes in Three-Phase Series-Type Saturable Reactor without Auxiliary Winding

A Simplified Approach to Instruction in Saturable Reactors and Magnetic Amplifiers

This paper intends to cast new light on some problems that hamper beginners when studying saturable reactor performance. It is not easy to explain to students why the mean value of the current must be zero for a nonlinear circuit having a characteristic resembling that of a rectifier. In addition, it is hard to grasp at initial stages how direct current can be "transformed" from the control to the power circuit. These problems and many others are easily explainable taking into account the fact that in steady state the mean value of the voltage across the coil of a saturable reactor must be zero.

Silicon controlled rectifier with parametric phase shifter

The object of this paper is to present a new magnetic ignition device for the silicon controlled rectifier (SCR), called a parametric phase shifter, in which the theoretical range of the firing angle is 360 degrees. In this device, a magnetic frequency subdivider, called a parametron, is used as the supply for the conventional saturable reactor connected to the gate circuit of the SCR. The ac source for the SCR and for the parametron is common or selected to have the same frequency <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</tex> . The supply frequency of the saturable reactor becomes one half ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2 f</tex> ) of the source frequency by the frequency subdividing action of parametron. Thus, the firing angle range of the SCR can be extended to twice the value as that reached by the ordinary ignition circuit with the saturable reactor only. From the experimental results, its range is measured to about 300 degrees. The starting angle of the ignition in this device can be controlled by changing the supply voltage, the loss component of the oscillating circuit, and the constant part of the inductance of the parametron. If this device is used as an SCR amplifier, the characteristics, such as the gain, the linearity, and the maximum output, are improved considerably. As the firing angle can be extended to the inverter zone of the SCR, this combined device can be used as a regenerative braking of dc motor.

Transistor Saturable-Reactor System

Transistors can be operated as collector-base junction diode switches. In addition, the transistor emitter can be used to regulate the rectification, as a controlled rectifier. Connected in series with a saturable reactor, transistor-reactor network is analyezed as a magnetic amplifier, and characteristic rectified output waveforms are presented.

Transients in saturable reactors

Some interesting experimental results pertaining to magnetic-amplifier transients are reported, which seem to change present concepts on this subject.

Optimum Design of Self-saturating Reactor in the Application of Constant Voltage-Variable Current Power Supply†

ABSTRACT The self-saturating reactor is widely used for the control and regulation of alternating current. In this paper the design of saturable reactors for the application of constant voltage-variable current power supply has been discussed and some useful design formulae have been obtained, which give an easy and rapid design procedure. The basis of design has been discussed in brief while the design procedure has been worked ont in detail with a typical example.

Cable Power Facility

Submarine cable system power supplies must be designed to provide an uninterrupted flow of precisely controlled, transient-free operating power for a time interval equal to the service life of the cable system. Heavy reliance on redundancy along with conservative application of semiconductor and magnetic circuit elements form the basis for the circuit design. The equipment design emphasizes the techniques required to withstand high voltages, provide ease of maintenance and insure personnel safely. Saturable reactors operated in the constrained mode serve as the basic power control element. AC power for the saturable reactors is obtained from a transistor inverter fed from a continuously floated storage battery. Metering-type magnetic amplifiers are used to isolate the regulation, metering and alarm circuits from the high-voltage output. Transistor amplifiers and temperature-compensated silicon reference diodes complete the regulating loop.

Special Design Considerations for the Apollo Spacecraft Electrical System

In the Apollo spacecraft electrical power system weight is at a premium. Energy loss actually increases the system weight by added fuel requirements. A new type of switch gear was developed for the fuel cell system which eliminates the use of circuit breakers, diodes and uses instead solid state relay operated switches. Consideration was also given to use saturable reactor type current metering in the fuel cell line.