Showing papers on "Filter capacitor published in 1991"

A current source PWM inverter with instantaneous current control capability

Abstract: A new approach for the control of a current source pulse width modulated (PWM) inverter is proposed to achieve instantaneous current control capability. The proposed scheme provides instantaneous current response in the AC motor by altering the modulation index of the current source PWM patterns. In order to achieve this task, optimum programmed PWM patterns with selective elimination of lower order harmonics in the motor line currents are used. Output filter capacitors are provided to bypass the current harmonics in the inverter output and allow for the instantaneous changes in the line currents. This method of control provides sinusoidal output voltages and sinusoidal currents in the AC motor. The proposed scheme guarantees fast response characteristics combined with high-performance steady-state behavior. A design procedure for the current source PWM and selection of programmed PWM current patterns for a variable-speed situation is illustrated. Selected results are verified experimentally. >

Inrush current limiter

Abstract: A circuit for limiting the inrush current in DC to DC and DC to AC power supplies. The circuit utilizes a small capacitor for taking a charge which slowly turns on a FET transistor placed in series with a large filter capacitor; the slowly reducing resistance of the transistor provides the desired inrush current limiting.

Dynamic adjusting reference voltage for ferroelectric circuits

Abstract: A reference voltage circuit used for determining the polarization state of a ferroelectric capacitor. The circuit includes a pair of ferroelectric capacitors, each polarized to an opposite polarization state. The charge stored in each ferroelectric capacitor is discharged into respective sense capacitors, thereby generating different voltages, each representative of the different polarization states. The sense capacitors are then short circuited together to thereby average the representative voltages and provide a reference voltage that is of intermediate value. The reference voltage can then the used to compare memory cell signals generated by other ferroelectric capacitors to determine the respective polarization states.

Class D current-driven rectifiers for resonant DC/DC converter applications

Abstract: Analyses and experimental results are given for a family of three Class D current-driven rectifiers. The diode current is half-sine wave and the diode voltage is a square wave. The diode forward voltage and forward resistance are taken into account in the analyses. The basic performance parameters of the rectifiers are determined, such as input resistance, voltage transfer function, efficiency, and power factor. The ripple voltage is estimated, and some effects of the equivalent series resistance and equivalent series inductance of filter capacitors on the ripples are discussed. The experimental results were obtained using IR31DQ06 Schottky diodes at 1 MHz and 16 W output power. >

Rectifier able to operate with at least two separate ranges of alternating current supply voltage

Abstract: A rectifier power supply automatically adjusts to operate over either of two separate ranges of AC line voltages by reconfiguring filter capacitors so as to charge the capacitor serially when operated over the higher range of voltages and to charge the capacitors separately over each half cycle when operated over the lower voltage range. A triac device, used to control charging of the capacitors, is selectively activated only during a small portion of each half cycle to minimize power consumption. The device includes a bridge rectifier circuit receiving an AC line voltage and supplying pulsating DC to the serially connected two filter capacitors. The triac is used as a switch and is connected between one input terminal of the diode bridge and a node point between the two capacitors. An AC line voltage range detector and triac control circuit responsive to the range detector causes the triac to conduct when the AC line voltage is detected within the lower range. In particular, the control circuit causes the triac to conduct after a first time interval after a zero crossing of the AC line voltage and to cease conducting after a second time interval.

Voltage regulator with active turnoff

Abstract: A base voltage of a regulator transistor (Q2) is developed during normal operation in a filter capacitor (C2) coupled to a flyback transformer (24) of a horizontal deflection circuit (Q5,LY,CS). After a transition to a standby mode of operation, the deflection circuit is disabled and the capacitor begins discharging. The emitter of the transistor is coupled to a load circuit (L3). A supply voltage (+V₁) is coupled to the collector of the transistor during both standby and normal mode. To reduce the loading of a standby power supply that generates the collector voltage as long as the capacitor is not fully discharged, an active turnoff (Q3) of the regulator transistor is provided immediately after the receiver goes into the standby mode of operation so as to actively turnoff the current drawn by the transistor.

Electric circuit for providing a high tension impulse, particularly for a defibrillator

Abstract: The HV pulse circuit uses a series of capacitors (C1...Cn) connected in a series circuit via associated switches (S1...Sn) for selective discharge of the capacitors (C1...Cn). The latter are charged in a parallel circuit, with stored energy within the circuit used for operating the switches (S1...Sn). Pref. a control unit is used for controlled connection of the charged capacitors (C1...Cn) in the series circuit, to obtain a voltage pulse with a given signal characteristic.

Novel OTA-C filter structures using grounded capacitors

Abstract: The derivation of operational transconductance amplifiers and capacitor (OTA-C) filters from active RC filter structures using a nodal voltage simulation method is presented. Some of the derived structures use floating capacitors. A technique for simulating floating capacitors using only OTAs and grounded capacitors is also described, together with its applications to realize biquads. Ladder filters using only grounded capacitors and OTAs are described. >

Integrated series capacitors for high reliability electronic applications including decoupling circuits

Abstract: An integrated series capacitor includes two capacitors mounted in series in a unitary insulated package. The capacitors are formed of stacked plates separated by a dielectric material. Every other stacked plate for each capacitor terminates along an outer termination edge that is connected to a solder connection on an end of the insulated package. These stacked plates alternate with every other plate which has an inner termination edge. The inner termination edges of each capacitor are connected. The integrated series capacitor is adapted for connection to a circuit board between a chip supply voltage (Vss) and a ground connection (Vss) to provide a decoupling circuit to replace two separate series wired capacitors.

High frequency performance of capacitors

Abstract: The high-frequency performance of capacitors is related to their geometry and material properties. By considering multilayer capacitors as distributed electrical systems, the tools of ICONSIM are applied to study resonant frequencies, equivalent circuits of capacitors, and the influence of ground planes, test fixtures, and type of connection topology. The methods established are applied to well-documented capacitors described in the literature and good agreement between experimental results and analyses is obtained. >

Input filter design of forced commutated cycloconverters

Abstract: Input filter analysis and the design of forced commutated cycloconverters (FCCs) is presented. The input filter in each input phase is a second-order LC filter. The FCC, as the input filter load, is represented by a multifrequency current generator. For the FCC control the space vector modulation technique is used. The objective of the input filter design is to minimize the filter total kVA rating (T/sub kVA/) for given constraints of the input current and output voltage total harmonic distortion (T/sub HDi/ and T/sub HDv/). The FCC input filter design is performed using three sets of curves: T/sub kVA/, T/sub HDi/, and T/sub HDv/ versus filter capacitor reactance X/sub c/, for particular values of filter inductor reactance X/sub L/. It is shown that the T/sub kVA/ curves, for each particular X/sub L/, have a conditional minimum, obtained either with T/sub HDi/ or with T/sub HDv/ constraint. >

Auxiliary power supply for vehicle

Abstract: PURPOSE:To prevent secondary failure upon occurrence of ground fault by detecting voltage across a filter capacitor and interrupting a circuit breaker if thus detected voltage does not exceed a reference level upon elapse of a sufficient time after start of charging of the filter capacitor. CONSTITUTION:Under a state where a filter capacitor 8 is not yet charged and the voltage Vf across the filter capacitor 8 is lower than a reference level Vfr while the overhead line voltage Vd is normal and higher than a reference level Vdr, a high speed circuit breaker 4 is turned ON by a high speed circuit breaker ON signal ION to start charging of the filter capacitor 8. When a detection signal Vf of a capacitor voltage sensor 14 does not exceed the reference level Vfr because of ground fault, frequency signal of a logic circuit 33 remains in H level even upon elapse of a delay time and a high speed circuit breaker OFF signal IOFF is outputted from a delay circuit 34. Consequently, the high speed circuit breaker 4 is turned OFF to interrupt current flow to the grounded part thus preventing secondary failure such as burning of charging resistor RC or breakdown of grounded part.

Variable voltage and variable frequency inverter for car

Abstract: PURPOSE:To simplify a structure by composing an inverter for driving a 3-phase induction motor for a car of three sets of transistor stacks, arranging them in two rows under a floor, and forming a dry air-cooling type capable of inspecting from a window of its side face. CONSTITUTION:Phases U1, U2,..., W2 of an inverter for driving an induction motor for a car by VVVF are reduced at a current capacity per one by stacking a plurality of transistors Trs. Each Tr has cooling fins 20, and the transistors are contained in two rows in a box 10 under the floor. inverter controllers 16, 18 and filter capacitor units C1, C2 are also contained in the box 10, and wired with the capacitors C1, C2 via polyphase low inductance bars, not shown. It can be inspected from windows at both sides of the box 10. Thus, it is formed of a simple structure of dry air cooling type to facilitate maintenance and inspection.

Capacitor application considerations-Utility/user interface

Abstract: The continuously increasing use of power capacitors throughout utility and industrial paper systems has resulted in an increased awareness level of the application considerations associated with capacitor switching and harmonics. The author reviews these topics from a system point of view, emphasizing the system interaction effects and the means that can be used to minimize this interaction. It is noted that the switching of a capacitor bank can cause transient overvoltage concerns at other points in the system under certain conditions. A number of methods are discussed for reducing these transients, including closing and opening resistors, controlled closing, staggered closing, reactors, and surge arresters. Capacitor banks throughout the system can influence the distortion level that occurs due to a harmonic source. That effect can be minimized by using filter capacitor banks in the plant at the medium or low voltage buses which would be at or near the source of the harmonics. >

Optimum electrical PD test method for large capacitors

Abstract: The optimum method for electrical partial discharge testing of large capacitors, including the effects of internal inductance, is determined. The results indicate that internal inductance does not adversely affect detection sensitivity if the detection impedance is made equal to the critical damping resistance. This has the advantage of providing a nonresonant waveform which can be detected in a near-optimum manner using a simple low-pass filter. >

Controller for electric vehicle

Abstract: PURPOSE:To miniaturize high voltage main circuit by a constitution wherein a contactor, connected with the primary winding of a transformer, is thrown in when the contactor on the side of the high voltage main circuit is opened before starting in order to charge a filter capacitor through a rectifier. CONSTITUTION:When a contactor 2 on the side of high voltage main circuit is opened before starting, a contactor 13 connected with the primary winding of a transformer 12 is thrown in thus charging a filter capacitor 3 through a rectifier 11. At that time, a current suppressing resistor 14 connected with the primary winding of the transformer 12 suppresses surge current thus gradually increasing the voltage of the filter capacitor 3. When the filter capacitor 3 is charged upto a boost voltage to be determined by the turn ratio of the transformer 12 the charging current goes zero and thereby the contactor 2 on the side of high voltage main circuit can be thrown in to start operation of an inverter 4. Since high capacity charging resistor is not required, circuitry of high voltage main circuit can be simplified and miniaturized.

Interactive analysis and design program for phase-controlled rectifiers

Abstract: The authors describe an interactive computer program that accurately determines rectifier time waveforms in the periodic steady-state condition without the need for many of the previously used simplifying assumptions. The program provides important input data for the design of components associated with the rectifier. The DC, RMS, and peak currents through the output filter inductor and the DC voltage across and the RMS current through the output filter capacitor are sufficient for the selection and design of these components. The rectifier time waveforms are analysed for line-current harmonics, rectifier power factor, and other important rectifier performance data providing the user with a complete and accurate description of rectifier performance as a function of rectifier design. >

Resonant technique and apparatus for thermal capacitor screening

Abstract: A method and system for driving a plurality of transient decoupling capacitors connected in a circuit in order to heat them and to screen them via a thermal image of them. Radio-frequency excitation is provided for the purpose by connecting a pulse driver through an inductive circuit and a series capacitance to supply a driving current to the decoupling capacitors. The inductance is selected to yield resonance at a selected frequency; and the series capacitance provides a voltage divider to help set the frequency and to adjust the level of the drive of the decoupling capacitors.

Noise preventive device

Abstract: PURPOSE: To reduce a noise voltage to an allowable value or less even if a small noise filter is used by adding a noise preventive circuit for canceling a noise current flowing to a parasitic capacitance between a power converter circuit and a metal case. CONSTITUTION: In a noise preventive circuit 5, a compensating capacitor CC 2 and a primary winding of a current transformer CT 1 are connected in series between an output bus O and a power supply bus N, a current iCC 2 responsive to a variation in an output voltage flows, and a noise preventing current iCC 3 flows to a secondary side of the transformer CT 1 through a compensating capacitor CC 3 in a direction from a metal case E to the bus N. Here, the capacities of the capacitors CC 2 , CC 3 and a current ratio of the transformer CT 1 are suitably selected. A noise current iCS 2 and the current iCC 3 are substantially equalized to reduce a noise current cf3 flowing to a filter capacitor C f3 , thereby decreasing a noise voltage ΔV 3 . A noise filter 2 can be reduced in size by adding the circuit 5. COPYRIGHT: (C)1993,JPO&Japio

Time-multiplexed switched capacitor circuit having reduced capacitance

Abstract: A time-multiplexed switched capacitor circuit in which certain capacitors are shared during local time periods of a global time period to allow the total capacitance of the circuit to be reduced. Corresponding savings in chip area in an integrated circuit implementation and component savings in a discrete implementation may be achieved. The invention is particularly applicable to a multiplexed circuit comprising an array of capacitors including first and second common capacitors and first and second pluralities of capacitors. The capacitors may be switched into and out of the multiplexed circuit during different local time periods. The first common capacitor may be switched into the circuit when any one of the first plurality of capacitors is involved in the operation of the multiplexed circuit thus reducing the size of that one capacitor of the first plurality of capacitors. In a similar fashion, the first and second common capacitors may be switched into the circuit when any one of the second plurality of capacitors is involved in the operation of the multiplexed circuit.

Discharge lamp lighting apparatus

Abstract: PURPOSE:To achieve high power efficiency of a lighting apparatus by sending current with similar waveform as the waveform of input voltage. CONSTITUTION:A commercial electric power source V is rectified by a rectifying device 2 and made into pulse flow. The pulse flow is sent in a step-up type converter composed of a choke coil 11, a switching device 12, a resistor 13 for current detection, a diode 14, a filter capacitor 3, and resistors 15, 16 for output voltage detection. At that time, in the case that the switching frequency by an IC for current mode switching control is sufficiently high as compared with the frequency of the commercial electric power source V, current corresponding to the voltage applied to run instantly to the device 12. The current running in the device 12 is converted into voltage by a resistor 13, sent in a controller 17, and by controlling the device 12 properly by the controller 17, current with similar waveform to the waveform of the input voltage is made to run. Consequently, with a simple circuit structure, high power efficiency of an apparatus is achieved.

Low inductance gto switching circuit for an inverter

Abstract: With respect to their connection to snubber capacitors (C1, C2), a discharge resistor (12) connecting these snubber capacitors, and a link capacitor bank (3), inverter circuits with GTO thyristors (T1, T2) connected in series have parasitic leakage inductances which limit the level of the permissible link direct voltage. In order to reduce the leakage inductances, the snubber capacitors (C1, C2) are surrounded by effectively conducting capacitor covers (17). Sheet-metal shielding covers are fitted over the two ends of the discharge resistor (12). Parallel and series connected capacitors of the link capacitor bank (3) are connected to the positive/negative terminals (23, 24) of the GTO thyristors (T1, T2) in the middle of a heat sink connecting strainer (33), the supply leads being guided essentially parallel and the capacitors being arranged in opposite planes.

Control method of inverter for driving electric car and inverter drive electric car system

Abstract: PURPOSE:To realize reduction of size, weight and cost by connecting filter capacitors and chopper circuits in parallel with transistor inverters, having DC sides connected in series, for every plurality of AC motors in a single electric car. CONSTITUTION:A DC high voltage, e.g. 1,500V, collected from a stringing 2 through a pantograph 3 and a filter reactor 4, is applied onto transistor inverters Tr In 10-40 having DC sides connected in series, and the DC voltage returns through a wheel 7 to a rail 8. Each Tr In inverts DC voltage into VVVF three- phase AC voltages for individually driving four induction motors 11-41 in a single electric car. Filter capacitors 12-42, chopper control circuits 15-45, and series circuits of choppers 13-43 and resistors 14-44 are connected in parallel with respective Tr In 10-40. Consequently, imbalance of load for each Tr In is prevented resulting in the reduction of overall size, overall weight and cost.

A high-reliability, low-cost, interleaved bridge converter

Abstract: The interleaved bridge topology uses two transformers in series to act as both inductor and transformer, allowing zero-voltage resonant transition switching for high-frequency, low-loss operation. High frequency reduces the requirement for large filter capacitors and reduces the size of the magnetics. Costs are reduced by trading electrolytic capacitors for ceramic capacitors, which also improves reliability. Costs are also reduced by eliminating gate driving isolation transformers and snubbers. Experimental results compare favorably with previous designs and costs. Both cost and reliability concerns are discussed. >

Representation of series capacitors in electric power system stability studies

Abstract: Series capacitor compensation applied to long-distance power transmission systems is addressed. Series capacitors reduce the effective transmission line inductive reactance, resulting in a larger capacity for stable power transfer. It is important to mention the effect of series capacitors on increased short-circuit current levels, as compared with the corresponding currents for noncompensated systems. These currents may reach very high values, especially for faults electrically near capacitor bank terminals, depending on their location, on network electric characteristics, and also on how series compensation is distributed. The authors analyze the representation of bypassed capacitors in stability studies of one-phase-to-ground short circuit, during and after short-circuit occurrence. The short-circuit and bypass periods are also discussed, leading to the adoption of a conservative modeling. >

A constant current integrated power supply

Abstract: A positive energizing voltage, preferably in a CMOS circuit, is converted, primarily by a pair of buffer capacitors and secondarily by a filter capacitor, to a particular negative potential. One buffer capacitor is charged through first switches by the positive voltage during the positive half cycles of a clock signal. The buffer capacitor is discharged to a load during the negative half cycles of the clock signal through a circuit including such buffer capacitor, second switches, a third switch, a reference voltage (e.g. ground) line and a negative potential line. The other buffer capacitor is charged through fourth switches by the positive voltage during the negative half cycles of the clock signals. This buffer capacitor is discharged to the load during the positive half cycles of the clock signals through a circuit including such other buffer capacitor, fifth switches, the third switch, the reference voltage line and the negative potential line. The third switch has at each instant a variable state of conductivity dependent upon the magnitude of the negative potential at that instant. The magnitude of the negative potential is varied in accordance with the variations in the state of conductivity of the third switch to regulate the negative potential at a particular value. The filter capacitor is charged by the negative potential and is discharged to the load when the second and fifth switches are simultaneously open. This occurs for a brief interval every time that the polarity of the clock signal changes.

Parallel connecting method of semiconductor switch and capacitor and switch circuit and inverter

Abstract: PURPOSE:To improve application rate of switch element and realize reduction of size by dividing a filter capacitor, equalizing inductance of wiring viewed from each of switch elements connected in parallel, lowering inductance of a power supply wiring viewed from each of filter capacitor and t-he equalizing the bearing currents CONSTITUTION:Filter capacitors 11, 12, 13 are respectively divided, wirings L71, L73, L75 are laid symmetrically to switch elements S1, S3 and S5 Thereby, fluctuation of wiring inductances L71, L73, L75 is lowered to equalize bearing currents immediately after turning ON Moreover, the filter capacitors 11, 12, 13 are connected in parallel with conductors and are arranged in parallel with a power feeding line from the power supply Accordingly, a total inductance can be balanced with the mutual inductance between such elements Steady currents flowing into the switch elements S1, S2, S3 are equalized by equalizing the current flowing into the filter capacitors 11, 12, 13

Receiver control for adjusting tuned circuits in HF filter - uses individual computer controlled tuning circuits to produce required adjustment voltage for channel selection

Abstract: A receiver oscillator tuning voltage (VTo) produced by a PLL circuit (10) is fed via a series resistor (R1) to a filter capacitor (C) which provides the necessary adjustment voltage (VT) for a tuned circuit. A control micro-processor (16) provides a pulse train, whose mark to space ratio is dependent on channel selection, to the base of an input transistor (T1). The inverted output of the input transistor (T1) is applied to the base of current source transistor (T2) and current sink transistor (T3). Dependent on pulse level (low or high) the collector of either the current source or current sink transistor (T1, T2) will be switched through to increase or decrease the charge potential on the filter capacitor (C) effecting fine control on the tuned circuit adjusting voltage (VT). USE/ADVANTAGE - Accurate tuning process for TV and radio receivers. Uses cheap and cost effective circuitry. Easy to adapt existing TV micro-processor for required tuning pulse outputs.

Autonomous gain normalization circuit

Abstract: An autonomous gain normalization circuit has a fixed capacitor for receiving a current signal such as that output by an infrared detector element and a plurality of switchable capacitors connectable in parallel with the fixed capacitor. The first switchable capacitor preferably has a capacitance of approximately one half of that of the fixed capacitor and each successive capacitor preferably has a capacitance of approximately one half that of the preceding capacitor. An analog-to-digital converter converts the voltage stored upon the capacitors into a first digital word. During a normalization cycle, the most significant bits of the first digital word cause connection of the switchable capacitors in parallel with the fixed capacitors such that second digital word having a value within a desired range is then provided by the analog-to-digital converter. Thus, the outputs of a plurality of such autonomous gain normalization circuits are normalized to a common range of values to facilitate signal processing thereupon.

Control device for electric rolling stock

Abstract: PURPOSE:To extend the life of capacitors by forming a present duct communicat ed to the outside air on a sealed box fitted on the car body of an electric rolling stock, and fitting capacitors to the sealed box so that main body heating section of capacitors are located in the duct and terminal sections are located in the sealed box. CONSTITUTION:An inverter device constituted of a semiconductor switching element and a filter capacitor 2 is mounted on an electric rolling stock, and a nearly square columnar duct 16 serving as a fitting plate of electrolytic capacitors 10 constituting the filter capacitor 2 is provided on a sealed box 6 fitted below the floor of the car body of the electric rolling stock so as to penetrate the sealed box 6. The duct 16 is fixed by fastening a flange section formed at its lower end to the opening periphery formed at the bottom section of a box frame 7. Capacitors 10 are fitted through the side wall of the duct 16 with fitting metals so that main body heating sections 10a are located in the duct 16 and terminal sections 10b are located in the sealed box 6.