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Showing papers on "Buck–boost converter published in 1988"


Journal ArticleDOI
01 Apr 1988
TL;DR: In this paper, the half-bridge series-resonant, parallel-reonant and combination series-parallel resonant converters are compared for low-output-voltage power supply applications.
Abstract: The half-bridge series-resonant, parallel-resonant, and combination series-parallel resonant converters are compared for use in low-output-voltage power supply applications. It is shown that the combination series-parallel converter, which takes on the desirable characteristics of the pure series and the pure parallel converter, avoids the main disadvantages of each of them. Analyses and breadboard results show that the combination converter can run over a large input voltage range and a large load range (no load to full load) while maintaining excellent efficiency. A useful analysis technique based on classical AC complex analysis is introduced. >

1,795 citations


Journal ArticleDOI
TL;DR: In this paper, a multistage capacitor divider Cuk converter was proposed for a 50 V to 5 V converter with high voltage step-down ratio without a transformer and a very small duty ratio.
Abstract: A novel switching DC-to-DC converter is introduced in which large voltage step-down ratios can be achieved without a very small duty ratio and without a transformer. The circuit is an extension of the Cuk converter to incorporate a multistage capacitor divider. A particularly suitable application would be a 50 V to 5 V converter in which DC isolation is not required. The absence of a transformer and a larger duty ratio permits operation at a high switching frequency and makes the circuit amenable to partial integration and hybrid construction techniques. An experimental 50 W three-stage voltage divider Cuk converter converts 50 V to 5 V at 500 kHz, with an efficiency higher than that for a basic Cuk converter operated at the same conditions. A corresponding voltage-multiplier Cuk converter is described, as well as dual buck-boost-derived step-down and step-up converters. >

298 citations


Patent
28 Apr 1988
TL;DR: In this paper, a full bridge integrable dc-to-dc converter is described which includes four FET switching devices wherein the parasitic capacitors of the switching devices exchange energy with the leakage and magnetizing inductances of the converter transformer.
Abstract: A full bridge integrable dc-to-dc converter is described which includes four FET switching devices wherein the parasitic capacitors of the switching devices exchange energy with the leakage and magnetizing inductances of the converter transformer. Since energy is exchanged between the passive components of the circuit, the switching is accomplished in a substantially lossless manner. Energy not transmitted to the load is returned to the source rather than being dissipated in the active devices of the converter. Further, single frequency operation is accomplished over a broad range of output conditions by phase shifting the converter legs relative to one another.

135 citations


Patent
18 May 1988
TL;DR: In this article, the output alternating current of the input filter is rectified and electronically switched by buck and boost switching circuits at a frequency much higher than the frequency of the alternating line current input.
Abstract: An AC to DC power converter comprises an input filter for filtering the alternating current input and an output filter for filtering and smoothing the direct current power output to a load. The output alternating current of the input filter is rectified and electronically switched by buck and boost switching circuits at a frequency much higher than the frequency of the alternating line current input. The rectified line current is sensed and provided to a control circuit which controls the operation of the buck and boost switching such that the power line current will follow a predetermined reference voltage waveform.

116 citations


Patent
13 Oct 1988
TL;DR: In this paper, a current mode converter with continuously variable optimized slope compensation and improved power factor is presented, where a ramp signal is generated with a slope that is determined by the loading of the converter.
Abstract: A current mode converter with continuously variable optimized slope compensation and improved power factor is disclosed. In the slope compensation circuit, the output voltage of the converter is sensed and a ramp signal is generated with a slope that is determined by the loading of the converter. The ramp signal is combined with a conventional sensed current signal of the converter to generate a composite sensed current signal which is coupled to the comparator of the converter. The other input to the comparator is a conventional error amplifier and the comparator's output is used to control switching of the converter. In an alternate embodiment, the continuously variable slope compensation circuit is operative using an un-filtered full-wave rectified input voltage waveform. An output is produced for the comparator which is the multiplied product of this input voltage and the output of the converter's error amplifier thereby amplitude-modulating the error signal and providing a composite error voltage that will always be proportional to the unsmoothed input voltage waveform.

111 citations


Proceedings ArticleDOI
01 Feb 1988
TL;DR: An experimental DC-to-DC converter prototype based on a zero-voltage switching, resonant circuit topology is described in this article, which is suitable for mounting directly on a circuit card.
Abstract: An experimental DC-to-DC converter prototype based on a zero-voltage switching, resonant circuit topology is described. The converter is suitable for mounting directly on a circuit card. The unit provides a regulated 5 V output at power levels up to 50 W with an input between 40 and 60 V. The switching frequency is between 20 and 24 MHz, depending on the input voltage and load. Differential input and output ripple and EMI are extremely low and somewhat difficult to measure. The converter prototype has been designed to demonstrate compatibility with a fully automated assembly process based on surface-mount technology. Solutions are presented to a number of problems, including MOSFET gate-drive and rectifier diode capacitance, that have seriously limited the performance of high-frequency converters operating with useful input and output voltages. >

85 citations


Journal ArticleDOI
TL;DR: In this article, an analysis of the phase-controlled DC-AC converter is presented, where a pair of switches in each side of the primary and the secondary of the isolation transformer are controlled by the phase difference between the two switches.
Abstract: An analysis of the phase-controlled DC-AC converter is presented. This converter has a pair of switches in each side of the primary and the secondary of the isolation transformer. The voltage conversion ratio is controlled by the phase difference between the two pairs of switches. The averaged equivalent circuit for low frequency operation is derived. The switching surge during commutation is much reduced by dividing the reactor into two parts. As a result, the transformer is miniaturized by increasing the switching frequency and the reactive energy can be easily recovered to the DC source. This DC-AC converter is especially suitable for small uninterruptible power supply systems. >

78 citations


Proceedings ArticleDOI
16 May 1988
TL;DR: In this paper, a 16-bit oversampling D/A (digital-to-analog) converter was designed using a fourth-order all-digital noise-shaping loop followed by a 3-bit converter.
Abstract: A 16-bit oversampling D/A (digital-to-analog) converter has been designed using a fourth-order all-digital noise-shaping loop followed by a 3-bit D/A converter. The 3-bit D/A converter, which uses a novel form of dynamic element matching achieves high accuracy and long-term stability without requiring precision matching of components. The harmonic distortion of the untrimmed monolithic CMOS prototype D/A converter is less than -90 dB. This converter achieves performance comparable to that of a 1-bit noise-shaping D/A that operates at nearly four times its clock rate. >

76 citations


Proceedings ArticleDOI
H. Sugimoto1, S. Morimoto1, M. Yano1
11 Apr 1988
TL;DR: In this paper, a high-performance control method for a voltage-type pulsewidth-modulated voltage type converter is introduced, starting from the modeling of the converter, power-factor control and five types of DC voltage control.
Abstract: A high-performance control method for a voltage-type pulsewidth-modulated voltage-type converter is introduced. Starting from the modeling of the converter, power-factor control and five types of DC voltage control are discussed. The stability and responses of these control methods are analyzed and compared with the root locus method and by digital simulation. The most promising approach, which uses current feedforward control, is applied to the drive test of an induction motor, and its excellent performance is confirmed. >

73 citations


PatentDOI
02 Mar 1988
TL;DR: In this article, a digital-to-analog converter (DAC) is proposed for converting a digital signal (DS) into an analog signal (UOUT) having a maximum voltage range which corresponds to a second supply voltage (UH).
Abstract: A digital to analog converter (DAC) for converting a digital signal (DS) having a maximum voltage range which corresponds to a first supply voltage (UL) into an analog signal (UOUT) having a maximum voltage range which corresponds to a second supply voltage (UH). The first supply voltage (UL) is offered between a first supply terminal (VSS) and a second supply terminal (VDDL). The second supply voltage (UH) is offered between the first supply terminal (VSS) and a third supply terminal (VDDH). The digital to analog converter (DAC) comprises conversion resistors (RCNV0 - RCNVn) and coupling means (CPL) for coupling a number of said conversion resistors (RCNV2 - RCNVn) in between the first supply terminal (VSS) and an output terminal (OUT), and for coupling the remainder of said conversion resistors (RCNV0 - RCNV1) in between the third supply terminal (VDDH) and the output terminal (OUT). The value of said number depends on the data content of the digital signal (DS). Digital to analog converters are generally implemented in ICs. For modern ICs there is a trend toward ever decreasing supply voltages. Often circuits implemented in new IC processes have to be able to interface with ICs processed in less modern processes which are generally operated on higher supply voltages. In the modern process, therefore, circuits designed in modern ICs have to cope with voltages which are above the maximum specification for their transistors or other components. The DA-converter (DAC) mentioned above fulfils this requirement by the fact that material, such as polycrystalline silicon, is used for the conversion resistors (RCNV2 - RCNVn), which material can cope with relatively high voltages, and furthermore by the fact that only the coupling means (CPL) have to be designed to cope with relatively high voltages.

52 citations


DissertationDOI
01 Jan 1988
TL;DR: In this article, a low-frequency dynamic model of a single-phase ac-dc power conversion system is presented, where the conversion ratio of a quasi-resonant dc-dc converter is derived in terms of the well-known PWM topology.
Abstract: Part I: Quasi-resonant converters are a family of single-switch resonant dc-dc converters featuring zero-current or zero-voltage switching. Recognition of the topological structure uniting these resonant converters--and the rectangular-wave (PWM) converters on which they are based--leads to general models of their dc and low-frequency ac behavior. An expression is derived that yields the dc conversion ratio of a quasi-resonant converter in terms of the well-known conversion ratio of the underlying PWM topology. A small-signal, low-frequency dynamic model is developed whose parameters also incorporate the PWM conversion ratio. The dc and ac models reveal that any quasi-resonant converter with a full-wave resonant switch has dc and low-frequency behavior identical to that of its PWM parent, with switching-frequency control replacing duty-ratio control. Converters with half-wave resonant switches behave more like PWM converters in discontinuous conduction mode or with current programming, exhibiting lossless damping in the small-signal model and output resistance at dc. Although quasi-resonant converters come in an astounding variety of topologies, the dc (and to a large extent ac) behavior of these converters depends only on the underlying PWM topology and the class of resonant switch, and is unchanged by movement of the resonant reactances to various alternative positions. Part 2: The distorted input-current waveforms of nonlinear electronic loads cause interference and lead to poor utilization of the utility power line, a situation that is rapidly becoming intolerable with the increased application of electronic loads. Input-current shaping, also known as power-factor improvement, addresses the problem of improving current waveforms drawn from the power line. This study is restricted to single-phase ac-dc power conversion systems. Current-shaping circuits are shown to fall into just a few categories with common features and limitations. In addition to the more common buck- and boost-based current-shaping converters, a class of circuits with "automatic" current shaping is presented and analyzed. A set of rules is derived for determining whether a particular dc-dc converter topology is suitable for use as a current-shaping ac-dc converter, and the rules are used to judge the suitability of several resonant converter topologies for this application. A new, low-cost converter is suggested that combines input-current shaping, isolation, and fast output-voltage regulation. Input-current shaping requires that a converter store significant energy, leading to unfortunate size and weight restrictions. Additional implications of stored energy are examined, along with several methods of reducing the energy storage. It is shown that the ability of a current-shaping converter to regulate its output voltage is severely restricted as a result of the energy requirement. The methods and implications of introducing isolation to a shaping ac-dc converter are also studied.

Patent
29 Sep 1988
TL;DR: In this paper, the load current of the power converter is detected and averaged, and it is added to the voltage control signal of the voltage controller system which controls the converter output voltage to be constant, so that the converter control is less affected by the ripple of the load currents.
Abstract: A control circuit for an a.c. to d.c. power converter, in which the load current of the power converter is detected and averaged, and it is added to the voltage control signal of the voltage control system which controls the converter output voltage to be constant, so that the converter control is less affected by the ripple of the load current.

Proceedings ArticleDOI
11 Apr 1988
TL;DR: In this article, the DC behavior of a clamped-mode, series-resonant converter is characterized systematically, given a circuit operating condition, the converter's model of operation is determined and various circuit parameters are calculated, such as average inductor current (load current), RMS inductor currents, peak capacitor voltage, RMS switch currents, average diode currents, switch turn on currents, and switch turn off currents.
Abstract: The DC behavior of a clamped-mode, series-resonant converter is characterized systematically. Given a circuit operating condition, the converter's model of operation is determined and various circuit parameters are calculated, such as average inductor current (load current), RMS inductor current, peak capacitor voltage, RMS switch currents, average diode currents, switch turn-on currents, and switch turn-off currents. Regions of operations are defined, and various circuit characteristics are defined to facilitate the converter design. >

Journal ArticleDOI
TL;DR: In this article, the authors measured short-circuit tests on a 262.5 MVA, three-phase, five limb converter transformer at various frequencies from 50 Hz to 1 KHz.
Abstract: Losses were measured during short-circuit tests on a 262.5 MVA, three-phase, five limb converter transformer at various frequencies from 50 Hz to 1 KHz. Using these and the calculated values of the harmonic currents produced by the AC/DC converter, load losses were determined. Variations of these losses with the converter firing angle, with the transformer reactance and with the load were studied. A simple method of loss calculation which has the potential for application at the design stage was developed. >

Proceedings ArticleDOI
H. Seidel1
11 Apr 1988
TL;DR: An approach for achieving high power factor in a zero-current/zero-voltage-switching tuned converter is presented in this article, where a tuned 90 degrees C phase shift section at the switching frequency fundamental of the Class D converter is used to render the power line into a current source.
Abstract: An approach for achieving high power factor in a zero-current/zero-voltage-switching tuned converter is presented. A tuned 90 degrees C phase shift section at the switching frequency fundamental of the Class D converter is used to render the power line into a current source. As a result, rectification occurs over the full AC cycle, drawing a constant line current over each half cycle. A 93%-power-factor, 1700 W, 300 kHz converter is discussed to demonstrate practicability. >

Journal ArticleDOI
TL;DR: In this paper, a clamped-mode parallel-resonant converter with a wide output voltage regulation range was proposed and analyzed using graphical state-plane techniques, and five circuit operating modes were identified and their mode boundaries defined.
Abstract: A novel clamped-mode parallel-resonant converter which operates at a constant frequency and provides a wide output voltage regulation range is proposed and analyzed. Employing graphical state-plane techniques, five circuit operating modes are identified and their mode boundaries defined. Regions for natural and forced commutation of power devices are specified. The DC control-to-output characteristics are derived to facilitate converter design. The predicted operating modes are experimentally verified using a 105 kHz prototype circuit. >

Proceedings ArticleDOI
Javier Sebastian, J. Uceda, M. Rico1, M.A. Perez, F. Aldana 
11 Apr 1988
TL;DR: In this article, a two-output DC-to-DC converter is studied using only a power transistor, and both outputs have been regulated by controlling duty cycle and switching frequency.
Abstract: A novel two-output DC-to-DC converter is studied. Using only a power transistor, both outputs have been regulated by controlling duty cycle and switching frequency. The number of power components is very low, as the use of demagnetizing components of the isolation transformer is avoided. A static and dynamic study of the converter has been carried out, and the results are verified for a prototype. >

Journal ArticleDOI
TL;DR: In this article, the performance of a three-phase converter is evaluated under both balance and unbalanced supply situations, and it is observed that the level of imbalance in the supply voltage increases the harmonic content of the input current and decreases the power factor of the converter.
Abstract: A three-phase converter is fully analyzed, and the performance of the converter is evaluated under both balance and unbalanced supply situations. It is observed that the level of imbalance in the supply voltage increases the harmonic content of the input current and decreases the power factor of the converter. This situation worsens toward the lower output region of the converter. The nature of the analysis has been kept very general so that future related work can be incorporated. >

Journal ArticleDOI
TL;DR: In this paper, a high-efficiency, high-frequency, boost zero-voltage-switching resonant DC/DC power converter is analyzed and the basic performance parameters of the circuit are analyzed as functions of the normalized load resistance and switching frequency.
Abstract: Analysis and design procedures are presented for a high-efficiency, high-frequency, boost zero-voltage-switching resonant DC/DC power converter. Equations describing converter operation are derived. The basic performance parameters of the circuit are analyzed as functions of the normalized load resistance and switching frequency. These equations are then used to determine conditions for lossless converter operation and design equations that yield the required component values. >

Journal ArticleDOI
TL;DR: In this article, a steady-state analysis of the parallel-resonant converter is presented using a novel frequency-domain model, where various circuit variables are determined by simple expressions for both the frequency and the phase control techniques, simplifying the steady state analysis.
Abstract: A steady-state analysis of the parallel-resonant converter is presented using a novel frequency-domain model. Various circuit variables are determined by simple expressions for both the frequency and the phase control techniques, simplifying the steady-state analysis. The existence of a multiple conduction mode is pointed out. The variations of output voltage, turn-off time, output power, and converter efficiency are studied. >

Patent
Sadao Hokari1, Kiyoshi Nakamura1, Katsu Komuro1, Takeki Ando1, Hiromi Inaba1, Shigeta Ueda1 
12 Jan 1988
TL;DR: In this article, a current-type converter including a DC power source, a current type converter, a load and a converter control unit, the converter control units controlling so as to cause as least two states among a powering conduction state for supplying power from a DC source to a load within predetermined control periods of both a powering control mode and a regenerative control mode.
Abstract: A current-type converter including a DC power source, a current-type converter, a load and a converter control unit, the converter control unit controlling so as to cause as least two states among a powering conduction state for supplying power from said DC power source to said load within predetermined control periods of both a powering control mode and a regenerative control mode, a regenerative conduction state for regenerating power supplied from the load toward the DC power source, and a reflux conduction state for short-circuiting the output of the current-type converter and returning the circuit current of the load, and the converter control unit varying the period length of respective states.

Patent
Hiroshi Araki1
10 Aug 1988
TL;DR: In this paper, a power converter apparatus comprising an initial voltage-setting circuit by which a signal for generating a predetermined voltage on the alternating (A.C.) side of a converter is applied to a current negativefeedback circuit at the start of the converter.
Abstract: A power converter apparatus comprising an initial voltage-setting circuit by which a signal for generating a predetermined voltage on the alternating (A.C.) side of a converter is applied to a current negative-feedback circuit at the start of the converter.

Patent
06 May 1988
TL;DR: In this article, an electric power converter operating with a rotating or moving magnetic field having a substantially constant flux density or of substantially constant magnitude is described. But the converter is not a phase changer/phase shifter or voltage adjuster.
Abstract: An electric power converter operable by means of a rotating or moving magnetic field having a substantially constant flux density or of a substantially constant magnitude. The electric power converter functions as a AC to DC, DC to AC or DC converter, or as a phase changer/phase shifter or a voltage adjuster. A feature of the converter is the continuous supply of power from the primary phases in contrast to prior art converters in which only the phase having the highest voltage supplies power at any one time. Harmonic current distortion is, therefore, substantially reduced.

Proceedings ArticleDOI
01 Feb 1988
TL;DR: In this paper, a full-wave zero-voltage switching quasiresonant converter flyback converter with a novel multiloop control was built which operates over the range of input voltage and load of a typical distributed-system power supply.
Abstract: A full-wave zero-voltage switching quasiresonant converter flyback converter with a novel multiloop control was built which operates over the range of input voltage and load of a typical distributed-system power supply. The maximum converter frequency of 880 kHz is shown to be close to the practical limit for this specific application. Reasonable full-load efficiency is achieved, and the predicted losses agree with actual circuit measurements. The multiloop control scheme provides noise-immune and stable control over the full operating range of the converter. Design guidelines for the control are given, and it is shown theoretical and measured small-signal performance are in agreement. Performance and stress predictions are also very close to measurements. >

Journal ArticleDOI
TL;DR: In this paper, a buck-flyback DC-DC converter circuit is proposed that overcomes this limitation by performing a voltage ratio d/sup 2/(1-d) in the best operating mode.
Abstract: It is difficult to obtain a large input/output voltage ratio with a DC-DC converter, because the duty factor d may not reach very small values. For the same reason, it is difficult to obtain an output voltage that is adjustable in a large range. A DC-DC converter circuit is proposed that overcomes this limitation by performing a voltage ratio d/sup 2//(1-d) in the best operating mode. Circuit operation is analyzed, operating modes are evidenced, and the voltage ratio is deduced in each operating mode as a function of output current, duty factor, and circuit component values. Boundary conditions between different operating modes are obtained; consequently, it is concluded that these conditions do not occur for some operating modes. Component ratings are summarized, to facilitate circuit design. The buck-flyback DC-DC converter is very suitable for low-voltage (e.g. computer) power supplies and for power supplies with the output voltage (adjustable in a large range) supplied from the mains without a mains voltage transformer. >

Patent
07 Oct 1988
TL;DR: In this paper, a 12-bit sub-ranging A/D converter with an 8:1 gain change between the cycles is presented. Butts et al. proposed a flash converter input circuit consisting of identical residue and reference amplifiers driving symmetrical residue and network for controlling the flash converter comparators.
Abstract: A 12-bit sub-ranging A/D converter which operates through four successive sub-ranging cycles with an 8:1 gain change between the cycles. The residue signal for each cycle is directed to a four-bit flash converter the output of which sets the latches for corresponding bit-current-­sources of a DAC. The flash converter input circuit com­prises identical residue and reference amplifiers driving symmetrical residue and reference networks for controlling the flash converter comparators. The DAC output for each cycle is compared with the analog input signal to produce a corresponding new residue signal. There are 15 bit-current-­sources, three for the first cycle, and four for each of the last three cycles. The MSB of each group of four bit-­current sources is an overlap bit having the same current weighting as the LSB of the preceding group. Setting of the overlap bit makes it possible to develop a correct output for the DAC for each of the 2nd through 4th cycles without altering bits already determined in previous cycles. The converter provides an optional 5th cycle making possi­ble a 14-bit output or an increased yield of 12-bit con­verters.

Journal ArticleDOI
TL;DR: In this article, a variable-speed generation (VSG) system that uses a series-resonant converter to excite the rotor windings of a doubly-fed generator is presented.
Abstract: Results of study and measurements are presented for a variable-speed generation (VSG) system that uses a series-resonant converter to excite the rotor windings of a doubly-fed generator The capabilities of this system include maximum-efficiency operation and limited converter rating for a speed range from stand-still (zero RPM) to well beyond synchronous speed, as well as flexibility for line-voltage control, reactive power generation, and synchronization at zero RPM Measurements of the harmonic distortion are provided showing the superiority of this converter as compared with a VSG system using a conventional cycloconverter or a DC-link converter A convenient tool for analyzing the operating modes of the system is discussed that can be developed under varying resource conditions >

Journal ArticleDOI
TL;DR: In this paper, the authors developed a stateplane method of analysis of a parallel inductor transformer resonant DC-DC converter using integrated magnetics to combine in a single magnetic structure the high-frequency output transformer, the resonant inductor, and an inductor for shortcircuit protection.
Abstract: The state-plane method of analysis of a parallel inductor transformer resonant DC-DC converter is developed. A key feature is the use of integrated magnetics to combine in a single magnetic structure the high-frequency output transformer, the resonant inductor, and an inductor for short-circuit protection. Use of integrated magnetics reduces the weight, size, and cost of the converter. The design of the magnetic structure is discussed, and design equations for leakage and magnetizing inductance control are derived. The effect of the leakage inductances on the shape of the equilibrium trajectories, converter derating, and available turn-off time are discussed. >

Patent
13 May 1988
TL;DR: In this paper, a DC Hall converter with an insertion hole is particularly well suited for weighting and combining the currents of each individual winding system, and the summation current formed in this manner does not have any null zones in normal operation of the converter.
Abstract: OF THE DISCLOSURE A state signal is formed to indicate a transition to a bypass mode of operation. In forming the signal of each winding system of a corresponding converter transformer on a side of the converter transformer are determined, weighted with weighting factors and summed up. The summation current formed in this manner does not have any null zones in the normal operation of the converter. All weighting factors are different if the phase currents between the converter and the converter transformer are used to produce the summation current. In the case of a converter transformer which is connected to the converter via a delta-connected winding system and in which the winding currents are used, certain differences formed by the weighting factors are not to be the same. A DC Hall converter with an insertion hole is particularly well suited for weighting and combining the currents of each individual winding system.

Patent
28 Dec 1988
TL;DR: In this paper, a unique multi-output isolated buck DC-DC converter system is described, which can be adapted to two or three-bobbin integrated-magnetic embodiments, or in discrete magnetic form.
Abstract: A unique multi-output isolated buck DC-DC converter system is disclosed. The converter system has non-pulsating input and output current waveforms. The converter can be adapted to two- or three-bobbin integrated-magnetic embodiments, or in discrete-magnetic form. One embodiment of the converter comprises capacitor means joined at one end to a first common core inductor and joined at its opposite end to a second common core inductor; and switch means having a duty cycle, for alternately joining an output lead to one end of the capacitor means and to the opposite end of the capacitor means, such that a voltage proportional to "VD" is produced at the output lead when a DC voltage "V" is applied across opposite ends of the first and the second common core inductor.