Showing papers on "Converters published in 1980"

Time interleaved converter arrays

Abstract: High-speed monolithic converters normally use a variation of the flash technique, which 2/SUP n/ comparators in parallel to obtain a fast n-bit conversion. Although this method allows for high converter bandwidth, it is not very area efficient, and results in large die sizes for even modest resolution converters. In the technique presented here, a number of small but area efficient converters are operated in a time-interleaved fashion to achieve the bandwidth of a flash circuit, but in a substantially smaller area. This technique is analyzed with respect to noise and distortion resulting from nonideal array characteristics, and is demonstrated by way of a four-way array test-chip. This chip consists of four time-interleaved 7-bit weighted-capacitor A/D converters fabricated in a 10 /spl mu/m metal-gate CMOS process. Full 7-bit linearity is maintained up to a 2.5 MHz conversion rate, with operation at reduced linearity continuing to approximately 4 MHz. The design of this chip, and anticipated characteristics if fabricated in a modern 4-5 /spl mu/m process are described.

State-Space Average modelling of converters with parasitics and storage-time modulation

Abstract: The State-Space, Averaging approach to modelling switching converter power stages is used to extend the analytical descriptions of the buck, boost, back-boost, and Cuk converters to include the effects of all parasitic resistances and transistor storage-time modulation. The analysis reveals for the first time a new and unexpected term in the line to output response of the Cuk converter. The new term contains a right half-plane zero produced by the energy transfer capacitance in combination with the duty-ratio-weighted sum of the on-resistances of the transistor and diode plus a non-dissipative ac resistance term due to transistor storage-time modulation. The conventional circuit model of the converter is modified to include the effects of the new term. The improved model permits an easy physical interpretation of the, new zero, which has been observed only in the Cuk converter. An extended analysis of storage-time modulation in bipolar transistor switches shows that the ac small-signal performance of a switching converter is highly dependent on the nature of the base drive. It is demonstrated that storage-time modulation in conjunction with a proportional base drive can produce instability in switching converters, even open-loop. The results of these analyses are verified experimentally and their impacts on practical converters are discussed.

Comparison of Multiple-Output DC-DC Converters Using Cross Regulation

Abstract: A new multiple-output dc-dc converter is analyzed, in which the cross regulation is performed by the energy-storage reactor as well as the transformer. The steady-state and the dynamic characteristics of this converter are compared both theoretically and experimentally with those of the conventional one composed of the step-up-down type circuit. As the results of comparative analysis, it is revealed that this new converter is superior to the conventional one in the steady-state and the dynamic performances. Further, it is demonstrated experimentally that the cross regulation performance of this new multiple-output converter is less affected by the leakage flux in the energy-storage reactor, and also that this converter is very useful as a preregulator for the continuous series regulator in cases requiring a high degree of regulation of the multiple-output voltages.

Precise regulation of multiple output voltages in a dc-dc converter

Abstract: A new dc-dc converter is presented to perform the precise regulation of multiple output voltages, which is composed of the cascade connection circuit of the improved forward type multiple-output converter and the step-down type single-output converters. In the conventional multiple-output converter using cross regulation, the steady-state errors in the cross regulated outputs cannot be made smaller than some values for the change of the load even if the proportional gain of the feedback controller is increased. Also, in the multiple-output converters with additional switches, which are connected in series with the diode rectifiers in each cross regulated output unit, it is difficult to perform the precise regulation of multiple outputs for the large change of each load. On the other hand, by the method presented here, the satisfactory regulation performance can be achieved easily for the conditions of no load to full load. The steady-state and the dynamic characteristics are clarified through the equivalent circuits, and also it is demonstrated experimentally that this converter has a sufficiently high conversion efficiency.

The elimination of offset errors in dual-slope analog-to-digital converters

Abstract: A new method of eliminating offset error from a dual-slope analog-to-digital converter is described. Two dual-slope cycles, each with the same fixed time period, are needed for a complete conversion. The converter differs from other converters in that the sum and difference of the unknown and reference voltage, as well as the voltages themselves are integrated. Different combinations yield a number of error-free converters in which the ratio of the two voltages is equal to the ratio of the sum or difference of two time periods. The converters also have a limited computational capability In that useful outputs other than the ratio of the unknown and reference voltages can be obtained. For some of the converters the sum or difference of two time periods yields an output with greatly reduced offset error. Another sum or difference provides a correction factor. In addition, some of the converters require a single reference voltage for the entire positive and negative range of the unknown voltage.

A Unifying Principle Behind Switching Converters and some New Basic Configurations

Abstract: Switching converters are conventionally drawn in three basic configurations, namely, a) The Flyback converter b) The Forward Converter c) The Up-Converter Each of these configurations is characterised by a D. C. voltage transfer of the form where Vo and V1 are respectively, the output and input voltages, and d is the duty-ratio of the switch. To the extent that F(d) is different for each of the three configurations, they are considered to differ from each other in a basic, mathematical, sense.

DC Transmission control system

Abstract: A DC power transmission control system for a DC line inserted between a pair of converters comprises a transformer provided on the AC side of each of the converters for maintaining constant the no-load voltage on the converter side by tap position control. One of the converters is operated as an inverter for control of the DC voltage. The control angle of the converter operated as the inverter is controlled by a signal associated with, e.g., a DC current as a load. The DC terminal voltages of the converters are made variable, thus reducing the amount of increase in the reactive power of the rectifier under a small load condition.

Dc-to-dc converters utilizing fet devices

Abstract: Light-activated power FETs (18, 20, 80, 82) are utilized as switching elements in DC-to-DC converters. The FETs are characterized by high speed and low losses. As a result, the converters are capable of providing very low DC voltages in an efficient low-cost way.

Application handbook for a Standardized Control Module (SCM) for DC-DC converters, volume 1

Abstract: The standardized control module (SCM) was developed for application in the buck, boost and buck/boost DC-DC converters. The SCM used multiple feedback loops to provide improved input line and output load regulation, stable feedback control system, good dynamic transient response and adaptive compensation of the control loop for changes in open loop gain and output filter time constraints. The necessary modeling and analysis tools to aid the design engineer in the application of the SCM to DC-DC Converters were developed. The SCM functional block diagram and the different analysis techniques were examined. The average time domain analysis technique was chosen as the basic analytical tool. The power stage transfer functions were developed for the buck, boost and buck/boost converters. The analog signal and digital signal processor transfer functions were developed for the three DC-DC Converter types using the constant on time, constant off time and constant frequency control laws.

Short time emergency supply for frequency converter system - uses single synchronous machine with flywheel as energy store

Abstract: During normal operation of the static frequency converters the synchronous machine, and its flywheel, runs as a motor connected to the converter bus-bar The mains is connected via a solid state switch to the converter bus-bar Mains interruptions, or major voltage depressions, are sensed by a logic unit The bus-bar connector is put into the blocking mode and the machine goes over to the generating state, providing energy from its rotating mass to supply the converter loads On restoration of the mains the machine is tripped, the converter rectifier sections blocked, and the connection between converter bus-bar and mains re-established Subsequently, the converters are restored to normal operation and the machine reconnected The converter interruption time on mains restoration is some 005 second The motor stored energy is typically sufficient for maintaining converter output for 3 seconds In the normal state the machine acts as power factor correcter for the converters A typical application is to variable speed drives in synthetic yarn mfr

Programmable two-quadrant transconductance amplifier

Abstract: Two multiplying digital-to-analog converters are used to digitally weight an analog current to produce a controllable output current. The output current is selected by a digital control signal applied to the control inputs of both converters. Two-quadrant operation is ensured by feeding the analog output of each converter to a current mirror amplifier which develops the required output current.

Polyphase thyristor motor controller

Abstract: PURPOSE:To reduce the torque ripple of a polyphase thyristor motor and the size of a DC reactor by conducting anti-parallel thyristors connected between the connecting point of a plurality of power supply side converters and the connecting point of a plurality of motor side converters in the low speed range of the motor. CONSTITUTION:When the rotating speed of a synchronous motor 5 is lower than predetermined value, any of thyristors 10, 11 is conducted according to the direction of an electric current. The output currents of converters 2, 3 are alternatively controlled to be interrupted to communicate converters 6, 7. Since the output currents of the converters 2, 3 are controlled in the same manner while the converters 6, 7 are not commutated, the thyristors 10, 11 are turned off to flow no current therethrough. Since the output current of one converter becomes zero while the converters 6, 7 are commutated, the output current of the other converter is flown through the thyristors 10, 11. When the rotating speed of the motor is higher than predetermined value, the converters 6, 7 are commutated by the counterelectromotive force of the motor to break the gate signals of the thyristors 10, 11.

Control system for reactiveepower compensator

Abstract: PURPOSE:To abtain a control system for a reactive-power compensator and also to improve its response remarkably, by combining a direct-current reactor to two converters differing in characteristics and then by using the reactive-power compensator. CONSTITUTION:The direct-current sides of power commutating converter 1 controlled at a lagging phase angle and forcible commutating converter 2 controlled at a leading phase angle are connected in parallel or series to direct-current reactor 3. The alternating-current sides of both those converters are connected to an alternating-current power system to be compensated and one converter holds a current through direct-current reactor 3 to a set value given corresponding to reactive power to be compensated. Then, the other converter controls the compensating adjustment of the reactive power of the system for excellent-response reactive power compensation.

An approach to the design of energy storage reactors for DC-to-DC switching power converters using ferrite structures

Abstract: The method for the design of energy storage reactors for dc-to-dc power converters is outlined. With the dynamic equations of the power converter and the calculations of the total power losses in the reactor as a starting point, the approximate expression describing the required volume of the core is derived, and the optimal geometry of the magnetic circuit is found analytically. The method, for a given power stage specification and constant coefficients of the geometry of a normalized core series, uses a designer-selected value of the difference between the operating temperature of the reactor's external surface and the ambient temperature as a major design constraint. The design procedure makes use of a family of core-loss characteristics. The boost type of power regulator is used as an example, yet the design technique may be applied to each of nine different dc-to-dc power converters and is applicable to most core shapes and most modern magnetic materials.

Design of energy-storage reactors for single-winding constant-frequency DC-to-DC converters operating in the discontinuous-reactor-current mode

Abstract: This paper presents an algorithm and equations for designing the energy-storage reactor for dc-to-dc converters which are constrained to operate in the discontinuous-reactor-current mode. This design procedure applies to the three widely used single-winding configurations: the voltage step-up, the current step-up, and the voltage-or-current step-up converters. A numerical design example is given to illustrate the use of the design algorithm and design equations.

Controlling method of induction machine

Abstract: PURPOSE:To enable control of quick response in a wide range, by separately instructing a component of a stator current in the same direction as a magnetic field and another component perpendicular thereto and supplying the current components from separate power converters. CONSTITUTION:A magnetic field detector 4 comprising Hall elements 41a, 41b and a vector analyzer 42 is provided. A calculation circuit 51 comprising multipliers 511-514 and a polarity inversion amplifier 515 is provided to transform coordinates. Phase number converters 52A, 52B and the power converters 2A, 2B are provided further. The component iM1 of the stator current of an induction machine in the same direction as the magnetic field and the other component iT1 perpendicular thereto are separately instructed. The current components are supplied from the separate power converters 2A, 2B. The stator current is synthesized from the output currents iM1, iT1 of the separate power conveter verters. The output currents can be varied with quick response independently of each other although the phase angles of the currents cannot be sharply changed. Therefore, the stator current can be quickly altered.

Harmonic filter for electric power

Abstract: PURPOSE:To reduce power loss and make a harmonic filter compact, by providing a power regeneration circuit which has a rectifier, connecting the circuit in series with a DC circuit of converters and regenerating a fundamental wave and harmonics on the DC sides of the converters. CONSTITUTION:A DC reactor 21 is provided in a DC line DC-L which connects converters 14, 15 at one conversion place to those 19, 20 at another conversion place. A filter 22 comprising series circuits of capacitances C and inductances L of bypass filters is connected to the tertiary sides of three-winding transformers 12, 13. A power regeneration circuit 23 is composed of an auxiliary transformer 24, a rectifier 25 and a DC filter 26. The input terminals of the power regeneration circuit are connected to the coupled nodes of the capacitances C and inductances L of the filter 22. The output terminals of the power regeneration circuit 23 are connected in series with the converters 14, 15, 19, 20. This results in reducing power loss and making a filter unit compact as a whole.

Device to compensate for the reactive power of a consumer and/or to balance an unbalanced consumer

Abstract: Individually controllable, self-commutated power converters (11, 12, 13) are in each case connected on the AC voltage side between two different phase conductors (1, 2; 2, 3; 1, 3) of a multi-phase AC voltage system, their controllable, automatically resettable valves (A to D) being disposed in a single-phase bridge circuit A transformer (14, 15, 16) is in each case disposed between the AC voltage-side outputs of the individual power converters (11, 12, 13) and the AC voltage system (4) A DC source (20) feeds a constant direct current (Id) into the power converters interconnected in series on the DC side The amplitude, and also the phase angle referred to the AC voltage system, of the fundamental oscillation of the output current (ix, iy, ix) of each individual power converter (11, 12, 13) can be set via its own control device (31, 32, 33) This achieves a high adjustment speed in compensating for the reactive power and/or in balancing the unbalance changes of a consumer (6) connected to the AC voltage system

A review of basic machine theory

Abstract: There are many types of rotating electromechanical energy converter. When these transform mechanical energy to electrical energy, they are called generators. When they convert electrical to mechanical energy, they are operating as motors. Most energy converters can operate either as generators or motors. We shall, however, refer to these rotating electromechanical energy converters simply as electrical machines.

A novel pulse firing scheme for constant angle triggering of 3-phi thyristor converters

Abstract: The details of a novel and simple triggering circuit for the firing angle control of 3-phi thyristor converters operating under variable frequency supply is explained. The firing angle remains almost constant for a given control voltage and for a wide range of supply frequency variations. The circuit uses only 1-phi sensing, to generate the triggering pulses necessary for 3-phi converters working under variable frequency supply and the firing pulses are spaced equidistantly. The circuit is inherently immune to noise and transients, due to the use of CMOS integrated circuits and optocouplers. The circuit can be used for applications such as rotor control of slip-ring induction motors. The experimental results obtained for the triggering circuit are presented.13;