Abstract: A converter for interconnecting two electric networks to transmit electric power from one network to the other, each network being coupled to a respective power generator station. The converter, having an AC side and a DC side, includes a bridge of semiconductor switches with gate turn-off capability coupled to a control system to produce a bridge voltage waveform having a fundamental Fourier component at the frequency of the electric network coupled to the AC side of the converter. The control system includes three inputs for receiving reference signals allowing to control the frequency, the amplitude and the phase angle of the fundamental Fourier component with respect to the alternating voltage of the network coupled to the AC side of the converter.
February 13, 1989
Date of Patent:
July 10, 1990
The Royal Institution for the Advancement of Learning
Abstract: This invention controls the operation of solid state swithing devices in an output stage of an electronic inverter by using a counter to maintain a fixed delay between transition points in a switching command signal and a modified switch operation signal. The counter begins counting clock pulses following a transition in the switch command signal and produces a transition point in a switch drive signal when it reaches a predetermined count. The solid state switching device changes conduction states in response to the transition points in the switch drive signal. This produces a transition point in a switch operation signal. Those transition points are time-shifted by an amount corresponding to the level of DC voltage in the inverter output to produce the modified switch operation signal. The counter stops counting in response to one of the transition points in that modified switch operation signal.
Abstract: A touch responsive power control system in which the majority of the signal processing functions are achieved through digital circuitry and includes a controllable pulse generator responsive to the change in capacitance caused by a human touch at a touch sensitive control point of the device to be regulated. The magnitude of the change in capacitance caused by the human touch is encoded in the form of the number of pulses contained in a pulse train or a series of pulse trains over a selected time period. The number of pulses is counted and digitally compared with a stored count. If the present count is different from the stored count, the stored count is adjusted and an error signal proportional to the difference between counts is supplied, after a sufficient interval, to a load driver which adjusts the power level supplied to the load from an electrical power source.
Abstract: Disclosed is an apparatus for storing electrical energy in a superconducting coil. The secondary phenomenon of magnetic induction which limits the size of existing superconducting energy storage coils is overcome by utilizing two superconductor material coils coupled by mutual induction through a high permeability magnetic material. This eliminates induction in the superconductor material thus eliminating the difficulty of the destruction of superconducting capability because of secondary induction. This construction permits high current storage capability in a small volume.
Abstract: A rotor assembly for a permanent magnet motor includes a set of laminations forming a rotor body, each lamination having a first magnet slot therein. A generally rectangular permanent magnet is disposed in the magnet slot, the magnet slot of each lamination being shaped so as to receive the rectangular permanent magnet through all the skewed laminations with a minimum air gap. A method of making an assembly such as a rotor includes the steps of providing an assembly body made of ferromagnetic material defining at least one magnet slot therein. The slot is at least partially filled with a mixture of magnetizable particles in a binder. The mixture is compressed and then cured, to bond the magnetizable particles together in the slot, and the bonded particles are then magnetized in the slot to form a magnet in situ in the slot without an air gap.
Abstract: Instability resulting from the presence of reactive components in the output filter of regulated power supplies of the general type in which regulation is obtained by feeding back the output voltage to the regulator circuitry is eliminated by deriving a feedback signal from the output voltage which includes not only a direct component, but also separately derived first and second derivative components referenced to the reactive characteristics of a series output choke and parallel output capacitor of the output filter circuit. The amplitude ratios of the feedback signal components are selected in accordance with a key aspect of the invention to eliminate the output filter from the characteristic equation of the power supply to thereby eliminate instability whatever its source.
Abstract: A linear reciprocating electromagnetic machine has an outer stator member having axially spaced apart pole pieces, an open-slot coil cavity housing a coil, and an inner stator member spaced from the outer stator member and providing means for completing a path for magnetic flux. The machine also includes a permanent magnet plunger arranged for reciprocation with respect to the stator members and within the space between such stator members. The plunger is provided with three permanent magnet segments arranged axially along the plunger such that the interface zones between the magnet segments are substantially within the region defined by the stator pole pieces for all operating axial positions of the plunger. The two outer magnet segments are of equal axial length while the center magnet segment is axially longer than an outer magnet segment by an amount equal to the axial length of the open slot of the coil cavity.
Abstract: To protect a semiconductor switch from high forward blocking voltage stresses during turn-off, a relief circuit is provided comprising a diode and a capacitor. The energy generated when the semiconductor switch is turned off or switched to the non-conducting state, is temporarily stored in the capacitor of the relief circuit until the semiconductor switch is changed back to its conducting state. Then the energy stored in the capacitor is transferred to a useful impedance by means of a further semiconductor switch being changed to its conducting state.
Abstract: A brushless dc motor, suitable for use as a hand-held surgical tool, includes a plurality of coils arranged in a substantially electrically non-conductive environment closely juxtaposed to a plurality of magnets which generate high-intensity, substantially unidirectional magnetic field lines such that the plurality of coils intersect the magnetic field lines at points of substantially maximum strength in order to minimize electrical losses.
Abstract: The present invention discloses an apparatus for damping resonance of an LC type low-pass filter provided on the DC input side of a power converter having a DC input terminal. The apparatus comprises an electric circuit connected in parallel to a reactor constituting the LC type low-pass filter. The electric circuit has an impedance which takes a substantially minimum value at a frequency equal to the resonance frequency of the LC type low-pass filter.
Abstract: A device to produce alternating electric current of high frequency for power consumers such as fluorescent tubes comprises a transformer with a winding connected in series with an output terminal and active electronic components controlling the output current, said active components being controlled by electric voltages produced by inductive feed back. Magnetic saturation is utilized to modify the induction relationship in such way that the active components cyclically change the direction of the output current. According to the invention the feedback takes place in two magnetic cores, each core being equipped with at least one further electric magnetization winding designated a command winding, as electric current is fed through the command windings whereby magnetic saturation of the magnetic cores is controlled.
October 30, 1987
Date of Patent:
June 19, 1990
Jorck & Larsen A/S, Halberg & Thomsen Elektronik L/S
Peer Herbsleb, Kjell Herbsleb, Kurt Halberg, Karl A. Jensen
Abstract: A phase switched power controller connects a load to a alternating current source for a proportion of each half cycle selected by the user. A first full wave rectifier is connected to the voltage source and produces an unfiltered full wave rectified output signal varying between zero and a predetermined peak. A low pass filtered full wave rectified signal is preferably obtained from a second full wave rectifier, the filtered voltage and unfiltered voltage being applied as inputs to a voltage comparator, the output of which triggers a timer. The timer determines the phase delay until a further pulse is triggered for activating a triac, applying power to the load during the remainder of each half cycle.
July 12, 1989
Date of Patent:
June 19, 1990
Dodge-Romig Research & Development, Incorporated
Abstract: First and second portions having different magnetizable properties are alternately disposed on a stator. A head movable relative to the stator has first and second poles each having a pair of magnetizable legs contiguous to the stator and displaced from each other, and from the other pole legs, along a first axis relative to the stator portions. The poles introduce magnetic flux in the same direction to the legs. First and second windings, each respectively associated with the legs on an individual pole, produce in one leg a flux aiding the pole flux and in another a flux opposing the pole flux. Alternating currents flow through each winding at each instant at a frequency dependent upon the head speed to the produced along the first axis at that instant. The windings are programmed to provide signals for producing a movement of the head to a plurality of different destinations along the first axis.
Abstract: In a direct-current machine comprising a permanent-magnetic stator, the detent torque or resting moment of the rotor is to be reduced by simple and low-cost technical means. This is achieved by disposing the permanent-magnet shells of the stator asymmetrically with respect to each other.
October 27, 1988
Date of Patent:
June 19, 1990
Standard Elektrik Lorenz Aktiengesellschaft
Abstract: A DC to DC series-parallel resonant converter (10) having a plurality of switches (Q1-Q4) which are switched alternatively between on and off states to cause electrical current to flow alternatively in first and second directions through a series-resonant circuit (60) Including a variable frequency ramp generator (28) having a reset input (R) for casuing an output ramp signal produced at an output to drop to zero in response to each reset signal; a comparator (30) having an input coupled to the output of the ramp signal generator, a second input for controlling the output DC voltage of the series-parallel resonant circuit and an output which changes level each time the ramp signal reaches the magnitude of the second input; a bistable circuit (32) having first and second outputs (Q, Q) for respectively outputting first and second signals, the output signals changing in response to a change in the output signal of the comparator coupled to the input; a pulse generator (26), coupled to the series-parallel resona
Abstract: A MHD turbomachine includes a rotary ferromagnetic rotor, a stationary ferromagnetic stator surrounding the rotor and defining axially-spaced annular cavities which extend circumferentially about and radially from the rotor, and axially-spaced annular ferromagnetic disks surrounding the rotor and mounted for rotation with the rotor. The disks are disposed in the stator cavities so as to define a pair of annular passages on opposite sides of each disk which are connected in flow communication with one another at inner and outer peripheries of the disk. An electrically conductive fluid occupies the passages and is capable of flowing along an endless path through the passages. A pair of electrodes mounted to the stator radially conduct a flow of electrical current through the fluid between the outer and inner peripheries of the disk. A field coil mounted to the stator generates a magnetic field in axial relation to the stator and disk and transversely across the fluid within the passages.
Abstract: In a PWM control type power supply apparatus, there are provided a single-phase full-wave rectifier coupled to a power source having a low frequency, for rectifying a first AC (alternating current) voltage to produce a DC (direct current) voltage; a DC-to-AC inverter including a first pair of switching elements connected to an input terminal thereof, and a second pair of switching elements connected to an output terminal thereof and to the first pair of switching elements to constitute a bridge inverter circuit, for inverting the DC voltage into a second AC voltage to be applied to a load; and a switching controller connected to the DC/AC inverter for alternately turning ON/OFF the second pair of switching elements in response to a sync signal (SYC) in synchronism with the first AC voltage at the low frequency of the power source, and for alternately turning ON/OFF the first pair of switching elements in response to a PWM (pulse-width modulation) control signal obtained from the first AC voltage and the secon
Abstract: An automatically controlled dynamic vibration absorber in which the characteristic frequency of the vibration absorber is adjusted automatically to the frequency of vibration from a vibrating source to dissipate the vibration by mating a response vibration with a forced vibration.
Abstract: An optical pulse generator for an electric-motor drive arrangement, especially for a motor vehicle window lifting drive with an electric motor and a flanged transmission is to be provided in a simple manner which improves the operating reliability of the drive arrangement while the overall size is reduced. To this end it is proposed, according to the invention, to arrange a code wheel (1) within the electric-motor drive arrangement on the rotor shift (4) of the electric motor or on a transmission output gear (5) within the flanged transmission. A protective encapsulation is achieved while the code wheel (1) is arranged on the rotor shaft (4) by a protective housing (3) supported on the code wheel (1). Alternatively, the code wheel is arranged on the transmission output gear (5), by a protective housing formed by transmission housing wall (201), the transmission output gear (5) itself. Sealing rings (8) arranged adjacent to the code wheel.
Abstract: An electric generating system having a discharge circuit for a DC filter capacitor includes an electric power source for producing a DC voltage on a pair of conductors and a DC filter capacitor electrically connected between the conductors. A voltage indicating signal, representative of the actual output voltage of the generator, is combined with a reference signal to obtain a control signal which varies in proportion to the difference between the desired output voltage of the power source and the actual output voltage. Power source output voltage is controlled in response to the control signal. A branch circuit with a solid state switching device is connected across the DC filter capacitor. The solid state switching device is turned on for a limited time in response to a change in the magnitude of the control signal resulting from an increase in the actual output voltage of the power source, thereby discharging the DC filter capacitor.