Including Means For Reducing Ripples From The Output Patents (Class 363/45)
  • Patent number: 5093641
    Abstract: A smoothing filter for a rectifier (LR) includes a series inductance (L) and a parallel capacitance (C). Because the capacitive voltage drop (V.sub.c) is in counterphase relative to the inductive voltage drop (V.sub.c) there is found on the series inductance (L) a point (K) where the voltage drop towards earth is zero for a given frequency (fg). The load (Z) on the rectifier is connected to this point (K) in order to achieve high attenuation the fundamental harmonic of the ripple voltage at this frequency.
    Type: Grant
    Filed: April 18, 1990
    Date of Patent: March 3, 1992
    Assignee: Telefonaktiebolaget L M Ericsson
    Inventor: Tadeus Wolpert
  • Patent number: 5014177
    Abstract: A ripple reduction circuit includes a controllable switch, an impedance coupled to one of a pair of main current path electrodes of the controllable switch whereby the impedance and the switch are coupled between first and second DC conductors and gating circuitry coupled between one of the conductors and a control electrode of the controllable switch for closing the switch when AC ripple power is carried by the conductors whereby at least a portion of the AC ripple power is removed from the conductors and delivered to the impedance.
    Type: Grant
    Filed: December 19, 1989
    Date of Patent: May 7, 1991
    Assignee: Sundstrand Corporation
    Inventor: Paul E. Nuechterlein
  • Patent number: 4939486
    Abstract: Filter equipment for power lines has a double-tuned shunt filter (F1) which has a series resonance circuit (C1, L1) connected in series with a parallel resonance circuit (C2, L2). The capacitor banks of the two resonance circuits are formed so as to have opposite signs on the temperature coefficent of the capacitor capacitance.
    Type: Grant
    Filed: January 4, 1989
    Date of Patent: July 3, 1990
    Assignee: Asea Brown Boveri AB
    Inventors: Bernt Bergdahl, Jan T. Holmgren
  • Patent number: 4903186
    Abstract: A power supply having a low ripple component to minimize waste power and improve efficiency. In a full wave power supply, additional circuitry is provided for decreasing the time between charging episodes of the output capacitor. The circuitry is comprised of additional capacitors and diodes, and is connected between taps on the transformer and the output capacitor.
    Type: Grant
    Filed: May 22, 1989
    Date of Patent: February 20, 1990
    Inventor: Keats A. Pullen, Jr.
  • Patent number: 4885675
    Abstract: A single stage power conditioner which produces an isolated DC output while drawing resistive input current from the utility has been described. A high frequency switch-mode technique was used which operates in continuous conduction mode to reduce electro-magnetic interference (EMI) generation and ripple losses.
    Type: Grant
    Filed: October 7, 1988
    Date of Patent: December 5, 1989
    Assignee: Unisys Corporation
    Inventors: Christopher P. Henze, James A. Smith
  • Patent number: 4872127
    Abstract: A ripple rejection filter for removing the fundamental frequency of load voltage from control signals in closed-loop phase controlled systems operating from an AC power source. A low-pass filter is connected in parallel with a firing point synchronized sample and hold and high-pass filter series combination. The output of the low-pass and high-pass filters are combined to produce a resulting signal representative of an input signal but with ripple rejected.
    Type: Grant
    Filed: January 7, 1988
    Date of Patent: October 3, 1989
    Assignee: MagneTek, Inc.
    Inventor: Dennis C. Nolan
  • Patent number: 4868732
    Abstract: A regulated voltage electrical power system has a driving section and a driven section. The driving section includes a power transformer primary structure and a ripple current carrying, driving winding of a filter system for the smoothed outputs circuits of the power system, each of which includes a single turn, driven filter winding magnetically coupled to the driving winding by a multi-path core structure. Each driven filter winding links that part of the multi-path structure which corresponds in cross-sectional area to the relative ripple voltage imposed by the power transformer on it. The power transformer secondaries for the outputs of the power system are also of a single turn each, differing output voltages being achieved by provision of differing number of primary winding turns associated with the various outputs. Planar diodes and core gap-filling ferrite inserts are provided in the secondary winding structures.
    Type: Grant
    Filed: October 28, 1987
    Date of Patent: September 19, 1989
    Assignee: International Business Machines Corporation
    Inventors: John B. Gillett, James H. Spreen
  • Patent number: 4864484
    Abstract: A high-pass element of a filter assembly for a line connected to static converters having a high voltage level for filtering harmonics and damping resonance sites includes a first series circuit including a first capacitor, a first choke coil, and a second choke coil. A resistor is connected in parallel with the choke coils. A second series circuit is connected directly in parallel with the second choke coil. The second series circuit includes a second capacitor and a damping resistor. On the other hand, the second capacitor and the damping resistor may be in parallel with the second choke coil and at least one other series circuit may be connected in parallel with the second choke coil. The at least one other series circuit includes a series capacitor and a series resistor.
    Type: Grant
    Filed: December 5, 1988
    Date of Patent: September 5, 1989
    Assignee: Siemens Aktiengesellschaft
    Inventors: Kurt Krueger, Heino Schmitt, Walter Schultz
  • Patent number: 4858098
    Abstract: To obtain a ripple-free direct-current focusing voltage in a split-diode technology high-voltage transformer, the tap is made not at the middle point of the second section of the secondary winding but at a point determined by the ratio of the stray capacitances of the two half-windings of this section, and it is directly linked to a high-value resistor.
    Type: Grant
    Filed: October 21, 1988
    Date of Patent: August 15, 1989
    Assignee: Societe Orega Electronique et Mecanique
    Inventor: Joel Vincent
  • Patent number: 4849065
    Abstract: A crystal growing method for growing a crystal from a raw material melt highly magnetic field is being applied to the raw material melt, the electromagnet for applying the magnetic field being supplied with a direct current having a ripple factor of less than 5% to thereby grow a crystal with good crystallinity properties.
    Type: Grant
    Filed: September 25, 1987
    Date of Patent: July 18, 1989
    Assignee: Sony Corporation
    Inventors: Yasunori Ohkubo, Toshihiko Suzuki, Nobuyuki Izawa
  • Patent number: 4833585
    Abstract: The present invention pertains to an AC electrical distribution system. The AC distribution system includes at least one nonlinear load. The nonlinear load causes distortion voltage in the AC distribution system. The AC distribution system also includes a zone filter which provides voltage to the AC distribution system. The AC distribution system can have a first zone which includes a nonlinear load and can have a second zone which includes at least one sensitive load. The zone filter regulates the voltage in the first zone as applied to the second zone and essentially eliminates the distortion voltage in the first zone as applied to the second zone. The zone filter can include a transformer device which provides a voltage to the AC distribution system. There is also a device for supplying power to the transformer device.
    Type: Grant
    Filed: August 3, 1988
    Date of Patent: May 23, 1989
    Assignee: Westinghouse Electric Corp.
    Inventor: Steven A. Moran
  • Patent number: 4803610
    Abstract: The invention relates to switching power supplies receiving DC input voltage, particularly for highly efficient regulators operating at high switching frequency and high power audio amplifiers. A switching power supply generally provides a pair of switching power supplies operating alternatively to supply energy to and from an output. Also provided are simplified designs of the combination of the two switching power supply circuits and the use of the present invention in a power amplifier.
    Type: Grant
    Filed: April 7, 1987
    Date of Patent: February 7, 1989
    Inventor: Zdzislaw Gulczynski
  • Patent number: 4703409
    Abstract: A power supply circuit for producing at least one output which is essentially free from current ripple is disclosed. A chopped DC voltage source is applied to a transformer having a primary coil and at least two secondary coils. The secondary coils provide input voltages to output stages which each include a rectifier diode, a freewheeling diode and an LC filter. The inductors in the LC filter of adjacent output stages are magnetically coupled together. The characteristics of these inductors are selected such that the current ripple through the inductors in all the output stages, other than the first output stage, is essentially zero. Multiple inductors can also be employed in the first output stage with each one being magnetically coupled to the inductor in a different succeeding output stage.These multiple inductors in the first output stage can be combined in series or in parallel.
    Type: Grant
    Filed: October 30, 1986
    Date of Patent: October 27, 1987
    Assignee: International Business Machines Corporation
    Inventor: James H. Spreen
  • Patent number: 4689730
    Abstract: In a flyback transformer circuit for a cathode-ray tube of the type arranged such that secondary windings of the flyback transformer are isolated from an a.c. power source, a positive terminal of at least one secondary winding of the flyback transformer is connected via a capacitor or a series circuit of a capacitor and a parallel circuit of a resistor and a coil to a terminal which is coupled with the commercial a.c. power source via low impedance in connection with high frequency. With the provision of the capacitor or the series circuit including the capacitor, the potential at the positive terminal of the secondary winding is made equal to that at the commercial a.c. power source in connection with high frequency components, and thus the flyback pulse appearing at the positive terminal of the secondary winding has the same polarity and substantially the same peak value as that appearing at the above-mentioned terminal.
    Type: Grant
    Filed: April 4, 1986
    Date of Patent: August 25, 1987
    Assignee: Victor Company of Japan, Ltd.
    Inventor: Satoshi Kimura
  • Patent number: 4668921
    Abstract: A power supply circuit having rectifiers and selectable first to n-th power supply voltage terminals for supplying various levels of output voltages. Between respective terminals and an earth, first smoothing capacitors (e.g. C.sub.1 -C.sub.4) are connected. Between i-th terminal and (i-1)-th terminal (wherein, 2.ltoreq.i.ltoreq.n), second smoothing capacitors (e.g. C.sub.5, C.sub.6, C.sub.n, C.sub.n-1) are connected. When i-th terminal is selected, not only capacitance of the first smoothing capacitor connected between the i-th terminal and the earth, but also capacitance of the first capacitor connected between the (i-1)-th terminal and the earth and the second capacitor connected between the i-th and (i-1)-th terminals are utilized for smoothing operation.
    Type: Grant
    Filed: October 22, 1984
    Date of Patent: May 26, 1987
    Assignee: Trio Kabushiki Kaisha
    Inventor: Eijiro Tamura
  • Patent number: 4641229
    Abstract: The input direct current used to build up the electromagnetic field surrounding the windings of a flyback transformer is converted by direct transformer action to current for replenishing charge in a first capacitor. Flyback current from the flyback transformer is used to replenish charge in a second capacitor. The sum of the voltages across the capacitors is supplied as converted energy to a load. In accordance with the invention, ripple in this output voltage is suppressed by proportioning the capacitances of the first and second capacitors to equal a nominal value of the ratio of the durations of the time intervals where direct transformer action obtains to the durations of the flyback intervals.
    Type: Grant
    Filed: September 2, 1982
    Date of Patent: February 3, 1987
    Assignee: RCA Corporation
    Inventor: Finis C. Easter
  • Patent number: 4622474
    Abstract: In this three-phase filter circuit system for static converter systems and particularly high-voltage direct-current short ties, at least two high-pass filters are provided which are connected in parallel. Each high-pass filter consists of a choke connected in parallel with a resistance and, in series with both, a capacitor and can be individually connected to the three-phase busbar via a switch. The filter circuits are used not only for reducing harmonics but also as compensating devices, which can be switched in steps, for the reactive power requirement of the static converters so that in the lower partial load range of the system one of the filter circuits is disconnected for reasons of reactive power balance. In order to improve the filtering effect in this lower partial load range, a bus-coupler switch connecting in each case the common junctions of capacitor, resistance and choke of the high-pass filters is closed.
    Type: Grant
    Filed: October 10, 1984
    Date of Patent: November 11, 1986
    Assignee: BBC Brown, Boveri & Company, Limited
    Inventors: Norbert Christl, Kadry Sadek
  • Patent number: 4573004
    Abstract: A variable electrical energy stabilizer is supplied with a source having a voltage magnitude that varies to maintain a constant ratio with the pulsation frequency of the source. The variable supply is derived from a variable energy source such as a kinetic energy accumulator which is intended for feeding a telephone exchange or an electrical unit on a sealed off site. The stabilizer supplies a d.c. output current to a load having a predetermined impedance. To provide the load with continuous energy with a constant amplitude via solely passive components, the stabilizer comprises an inductive circuit having an inductance substantially equal to the quotient of the constant ratio to the amplitude of the output current. The inductance circuit has a very high impedance compared to the load impedance.
    Type: Grant
    Filed: January 19, 1983
    Date of Patent: February 25, 1986
    Inventor: Marcel Herve
  • Patent number: 4562525
    Abstract: A circuit for supplying direct current to a line (a, b) from a battery via two supply resistors (RA, RB). Part of the current supplied by the battery flows in a secondary path including a resistor (R4) and a transistor (16), and is maintained at a constant value. A symmetrical and differential resistance bridge connected between the supply resistors and the line detects the transverse alternating current flowing into the battery, and means (15) are provided to cause the transistor to generate a negative-feedback alternating current whose value is adjusted to cancel said transverse alternating current.
    Type: Grant
    Filed: July 9, 1984
    Date of Patent: December 31, 1985
    Assignee: International Business Machines Corporation
    Inventors: Michel F. M. S. Ferry, Jacques L. Trehin
  • Patent number: 4521841
    Abstract: Circuitry for use in the current control loop of switched mode power supplies which in a first embodiment increases the a-c gain of that loop. In a second embodiment the circuit rejects common mode noise in the loop. In this embodiment the secondary of the transformer used to sense current in the power switching means of the circuit is made up of two windings in series which are wound bifilar with respect to each other. The d-c signal representative of the current in the switching means is taken between one end of the secondary and the center point of the series connection. In a third embodiment the circuit provides a relatively accurate representation of low current in the power switching device. In this embodiment the circuit uses at least one compensation means in series with resistive means connected across the secondary of the transformer to compensate for the turn-on voltage of the at least one diode used in the peak charging portion of the circuit.
    Type: Grant
    Filed: July 28, 1982
    Date of Patent: June 4, 1985
    Assignee: Reliance Electric Company
    Inventor: Neil A. Kamiller
  • Patent number: 4509108
    Abstract: A three phase a.c. to d.c. voltage converter is disclosed. First, second and third rectifier circuits rectify respective phases of a three phase a.c. source into respective varying d.c. voltages. First, second and third converters connected to the output of the first, second and third rectifier circuits, respectively, each converting the varying d.c. input generated by its associated rectifier circuit into a substantial d.c. voltage. Each of the converters also generate at least one isolated d.c. voltage. At least one of the isolated d.c. voltages is applied to the input of each of the converters to reduce the harmonic currents fed back into the a.c. line.
    Type: Grant
    Filed: September 15, 1983
    Date of Patent: April 2, 1985
    Assignee: Venus Scientific Inc.
    Inventor: George C. Gallios
  • Patent number: 4507721
    Abstract: A floating type DC-DC converter for remote power feeding is connected via a power separating filter to a signal line on which an AC signal is superimposed on DC power. The DC power separated by the power separating filter is stored in an input capacitor and is supplied by a switching operation of a switching element to the primary winding of a transformer and AC power induced in its secondary winding is supplied to an output capacitor after being rectified by a rectifying element. An electrostatic shield layer is interposed between the primary and secondary windings of the transformer and is connected to the capacitor connected to one of the primary and secondary windings.
    Type: Grant
    Filed: July 21, 1983
    Date of Patent: March 26, 1985
    Assignee: Nippon Telegraph & Telephone Public Corporation
    Inventors: Seiichi Yamano, Haruo Ogiwara
  • Patent number: 4504897
    Abstract: Voltage regulators of the waveform chopping type operable with alternating current sources are operated in a mode wherein a wave train complementary to the chopping wave train is provided with the property that each of the wave trains has equal amplitude and inverse polarity harmonics. Thus the two wave trains may be added together to cancel out all the noise introduced by the chopping. This is done by synchronously switching the respective wave trains in two corresponding processing channels leading to two respective power output channels, wherein one channel has incorporated therein amplitude regulation means, preferably of the feedback type. To remove the noise components, the higher frequency harmonics are isolated from the fundamental frequency which serves as the power supply medium, and then the equal amplitude and opposite sense harmonics are added together to cancel the noise components.
    Type: Grant
    Filed: November 15, 1983
    Date of Patent: March 12, 1985
    Assignee: White Scientific Consultants Inc.
    Inventor: Carl I. R. Blackwood
  • Patent number: 4488211
    Abstract: A harmonic and pulsation reducing circuit used in multiplex polyphase rectifier circuits such as a multiplex polyphase rectifier, a branch reactor, an external commutated invertor, etc. which is characterized in that a rectifier circuit to rectify the induced voltage of a secondary winding provided at interphase reactors interposed between other plural rectifier circuits is connected between the center of the interphase reactors and loads or a DC power source so that the rectified voltage may be superposed on the DC output voltage of the said plural rectifier circuits or the other DC power source.
    Type: Grant
    Filed: August 17, 1982
    Date of Patent: December 11, 1984
    Inventor: Shota Miyairi
  • Patent number: 4463431
    Abstract: Test equipment for measuring the amplitude of certain a.c. signals and comprising, a signal processing means responsive to each of such a.c. signals for transforming that signal into a d.c. level signal of a magnitude proportional to the r.m.s. amplitude of the a.c. signal, an analog to digital converter responsive only to those of such d.c. signals having magnitudes within an acceptance range for the converter to provide binary indications representative of such magnitudes of those signals, and circuit means for causing only d.c. level signals derived from a.c. signals with r.m.s. amplitudes in a subrange of a full range of such amplitudes to fall within the acceptance range of the converter.
    Type: Grant
    Filed: June 1, 1982
    Date of Patent: July 31, 1984
    Assignee: AT&T Technologies, Inc.
    Inventor: John W. Schumaker
  • Patent number: 4433368
    Abstract: A novel converter circuit converts AC input voltage within the range of 85-260 VAC to a constant voltage, current limited DC output voltage wth substantially no input voltage, all without the use of a transformer or input voltage-select switch. The AC input voltage is inputted directly to a rectifier and then to the input of a phase-controlling element (SCR) for controlling the phase of the unfiltered rectified signal. A trigger signal-generating circuit generates a trigger signal for regulating the operation of the phase-controlling element. A ripple-removing filter circuit receives the output from the phase-controlling element and removes the ripple component. A voltage-regulating circuit, a current-limiting circuit, and a rapid start-up circuit to facilitate rapid generation of DC output signal soon after energization of the overall circuit by an AC power source are also disclosed.
    Type: Grant
    Filed: January 5, 1982
    Date of Patent: February 21, 1984
    Assignee: Samsung Electronics Co., Ltd.
    Inventor: Hak-Ki Choi
  • Patent number: 4374346
    Abstract: A power supply control circuit is especially useful for a traveling wave tube, although it may also be used anyplace where desirable. An a-c power voltage is supplied to an input of the control circuit, where its frequency is multiplied to become a voltage having a period which is no greater than the duration of a power voltage fluctuation which might damage the traveling wave tube, unless corrected. The wave form of the multiplied frequency is shaped to provide a comparison voltage wave form, which is compared with a reference voltage. The a-c power voltage applied to said traveling wave tube is controlled responsive to the output of the comparison means.
    Type: Grant
    Filed: February 22, 1980
    Date of Patent: February 15, 1983
    Assignee: Nippon Electric Co., Ltd.
    Inventors: Takuichi Tsuchiya, Hiroshi Togo
  • Patent number: 4366532
    Abstract: In a transformer-rectifier converter system, at least one inductance is inserted in the commutation path of two adjacent diode or thyristor devices in a cluster of three devices related to a common DC polarity pole, the reactance due to such inductance being sufficient to lengthen the commutation overlap thereby to minimize AC line harmonics. The invention is applicable to AC/DC as well as to DC/AC conversion.
    Type: Grant
    Filed: May 11, 1981
    Date of Patent: December 28, 1982
    Assignee: Westinghouse Electric Corp.
    Inventors: John Rosa, Raymond J. Radus
  • Patent number: 4347561
    Abstract: An electronic device that converts alternating current to direct current with high efficiency. This is accomplished by constructing the device in such a manner that the device turns itself on slowly so that a surge resistor is not needed.In common power supplies of this type the surge resistor accounts for a large part of the power loss. In making the surge resistor not necessary power is saved.
    Type: Grant
    Filed: December 17, 1980
    Date of Patent: August 31, 1982
    Inventor: Norvel J. McLellan
  • Patent number: 4307305
    Abstract: A precision rectifier circuit includes two differential amplifiers each having a negative feedback path including a diode. Two pnp transistors have their base-emitter paths connected in parallel with the respective diodes and their collectors connected together and via an output resistor to ground. An a.c. signal to be rectified is applied to non-inverting inputs of the amplifiers, whose inverting inputs are interconnected via a resistor in series with a capacitor, to develop a unipolar output voltage across the output resistor. The capacitor renders the output voltage independent of input offset voltages of the amplifiers. The transistors can comprise Darlington-connected transistors to avoid the need for matching.
    Type: Grant
    Filed: January 8, 1980
    Date of Patent: December 22, 1981
    Assignee: Northern Telecom, Inc.
    Inventor: Darryl C. Morris
  • Patent number: 4302806
    Abstract: A filter for a polyphase rectifier includes first and second substantially identical sections each including a capacitor connected in series with a parallel circuit of a diode and a resistor, the capacitors of each section being connected at one end in common to a neutral or reference voltage terminal of the rectifier, the other ends of the first and second sections being connected to positive and negative output terminals, respectively, of the rectifier, the diode of the first section being polarized for passing current from the positive output terminal to its respective capacitor, the diode of the second section being polarized for passing current from the neutral terminal to its respective capacitor, the values of the resistors and capacitors being chosen for preventing the flow of ripple current through the first and second sections and substantially preventing discharging of said capacitors, for ensuring that the rectifier supply most of the load current, and for substantially eliminating peak current de
    Type: Grant
    Filed: January 11, 1980
    Date of Patent: November 24, 1981
    Assignee: Exxon Research & Engineering Co.
    Inventor: Richard H. Baker
  • Patent number: 4274133
    Abstract: A switching dc-to-dc converter employs inductance in series with the source to form an input circuit, and in series with the load to form an output circuit. Suitable switching means alternately connects an energy transfer capacitance in series in the input circuit and in the output circuit. The inductance may be provided by separate windings coupled to form a transformer. To reduce switching ripple in the input circuit, or output circuit, the transformer may be provided with an imbalance of leakage inductance in the primary winding and the secondary winding. The imbalance may be inherent in the design of the transformer, or in the design of the transformer core. In the case of tightly coupled inductances in the transformer, an equivalent imbalance may be achieved by a separate, external inductor connected in series in the input circuit, or the output circuit.
    Type: Grant
    Filed: June 20, 1979
    Date of Patent: June 16, 1981
    Assignee: California Institute of Technology
    Inventors: Slobodan M. Cuk, Robert D. Middlebrook
  • Patent number: 4224662
    Abstract: A power supply unit for a plasma plant, in particular for a plasma spraying plant, comprises an isolating transformer for connection to three-phase mains, a current control array and a rectifier array. The rectifier array comprises silicon wafer thyristors in a three-phase bridge configuration, which thyristors are electronically controlled through a current control loop, and an exterior voltage control loop is provided for additional electronic control of the silicon wafer thyristors.In the output from the thyristor array, a filter with a transient voltage suppressor may be provided as high-frequency protection and with di/dt limitation.
    Type: Grant
    Filed: April 10, 1978
    Date of Patent: September 23, 1980
    Assignee: Paul Boniger
    Inventor: Paul Boniger
  • Patent number: 4188586
    Abstract: In a demodulator circuit for a chopper amplifier including a rectifier and a smoothing filter having a capacitor, an impedance conversion circuit is connected to the output side terminal of the capacitor to ensure holding of the stored charges of the capacitor at each negative half-cycle of the amplitude-modulated AC signal applied to the demodulator circuit. A discharge circuit including a switching element is further provided for the capacitor and the discharge circuit is rendered conductive at each positive half-cycle of the amplitude-modulated AC signal which is also applied to a control terminal of the switching element.
    Type: Grant
    Filed: August 8, 1978
    Date of Patent: February 12, 1980
    Assignee: Nippon Soken, Inc.
    Inventor: Tsuneyuki Egami
  • Patent number: 4164013
    Abstract: A six-pulse rectifier circuit includes a rectifier bridge, with six valves, arranged in the secondary circuit of a three phase transformer having an increased internal resistance and shunted by a load resistor arrangement for sensing the actual value voltage for use in a fast control device with the resistance of the load resistor arrangement matched to the increased internal resistance of the transformer, so that at least three but no more than four of the six valves are always commutating.
    Type: Grant
    Filed: December 15, 1977
    Date of Patent: August 7, 1979
    Assignee: Siemens Aktiengesellschaft
    Inventor: Wolfgang Kaufhold
  • Patent number: 4122515
    Abstract: This invention is applied to a power converter with a converting apparatus comprising one or more units including only controlled rectifiers or combination of controlled rectifiers and non-controlled rectifiers, said converting apparatus being connected with an AC power source, whereby high harmonic currents generated in the AC circuit during commutating periods are reduced.In the present invention, at the commutating period of the converting apparatus, the reactance in the AC circuit of the converter is changed to increase in accordance with change of the AC current of the converting apparatus, so that the change of the AC current during the commutating period is made more slowly thereby reducing high harmonic currents.
    Type: Grant
    Filed: February 11, 1976
    Date of Patent: October 24, 1978
    Assignee: Hitachi, Ltd.
    Inventors: Kyozo Tachibana, Takashi Tsuboi, Yutaka Suzuki, Mitsugu Matsutake, Shozuchi Miura, Shigeru Hatano, Takao Goto, Yoshio Nozaki
  • Patent number: 4112287
    Abstract: An apparatus for inductively heating cooking utensils comprising four induction cooking coils excited by a central power oscillator providing an alternating sinusoidal excitation voltage at about 25 kilohertz which is 100% amplitude modulated at 120 hertz. Power to the four induction coils is duty cycle controlled by four 60 hertz triacs each series inserted between the power oscillator and a respective one of the induction coils. The triacs switch to excite their respective induction coils only at the zero point of the excitation voltage modulation envelope. Line power fluctuations are minimized by sequential switching of the triacs in a manner that results in an effective power switching frequency of approximately 46 hertz when all four induction cooking coils are excited. The central power oscillator is inherently protected from high Q load conditions without the provision of feedback loops.
    Type: Grant
    Filed: November 4, 1976
    Date of Patent: September 5, 1978
    Assignee: White-Westinghouse Corporation
    Inventors: Robert M. Oates, Theodore M. Heinrich
  • Patent number: 4099227
    Abstract: A circuit for sensing the motor stator voltage on any one or more phases of an AC electrical drive system. In a three phase system, all three phases of the motor terminal voltage are applied to a modified six-pulse rectifier bridge which in turn feeds a loading resistor. A resistor is added in series with each diode pair of the six-pulse rectifier bridge in order to provide any degree of attenuation of the peak voltage developed across the load resistor by simply varying the resistance values of these series input resistors and the load resistor. The resulting DC voltage generated across the load resistor is then fed into a differential amplifier (stage) where the voltage is attenuated and impedance isolated from the source to provide a DC output which is proportional to the average applied AC motor stator voltage.
    Type: Grant
    Filed: December 1, 1976
    Date of Patent: July 4, 1978
    Assignee: Square D Company
    Inventor: Julius M. Liptak