Abstract: An apparatus and method for generating a low frequency AC signal such as a ringing voltage signal for a telephone subscriber interface unit or the like. The apparatus comprises an oscillator which drives a pair of counters whose outputs differ by a desired low frequency. The output of the first counter is fed to a controlled current source so as to excite a resonant tank circuit and thereby provide a high voltage sinusoidal signal. The output of the second counter drives a switch which samples the high voltage sinusoidal signal. An alias frequency is thus generated which is filtered by an output capacitor. The method comprises steps which follow directly from the above-described apparatus.

Abstract: A method and apparatus for AC-to-AC power conversion wherein commutation from one switch in a switching group to a second switch is effected while both switches are enabled simultaneously without causing a short circuit between the phase input lines associated with each respective switch. Each switch in a switching group is bidirectional and polarity-controlled, and may be selectively enabled to conduct only negative-polarity or positive-polarity current, or may be disabled. An overvoltage clamping circuit is also provided with each switch. A switch gating control circuit is employed to provide selective operation of the switches in a particular switch group.

Abstract: A power supply for supplying the heating coils of a tube (WR), in particular a traveling-wave tube, wherein a transformer (Tr) and an inverter (S1, S2) are provided in the heating circuit of the tube (WR), and the frequency of the AC current is reduced from a high initial value to a lower value during the heat-up time of the tube (WR) in such a way that the change of the inductive voltage drop caused by this frequency change limits the heating current at the leakage inductance (LS) of the transformer (Tr).

Abstract: A three-phase a.c. uninterruptible power supply includes a transformer providing isolation between an input and an output, a single-phase inverter, and a cycloconverter. The uninterruptible power supply operates to convert a d.c. voltage into a high-frequency a.c. voltage in the single-phase inverter, transmit the output voltage of the single-phase inverter in an isolated state, and convert the output of the transformer into a three-phase voltage having a lower frequency, such as 50 or 60 Hz, than the frequency of the output voltage of the single-phase inverter. This enables the transformer providing isolation to operate at a high frequency, thereby enabling the size of the transformer to be reduced.

Abstract: A power conversion apparatus includes: a reference signal generating circuit for generating a reference signal which has a first frequency; a first power converter for converting D.C. power into A.C. power which has the first frequency; a transformer connected to the first power converter; a carrier signal generating circuit for generating a carrier signal which has a second frequency which is higher than the first frequency; a second power converter having a plurality of switching devices and as well as converting the output from the transformer into A.C.

Abstract: A power conversion apparatus comprises an inverter circuit for converting DC power into AC power which has a first frequency; a transformer connected to the inverter circuit. A cyclo converter circuit having a bidirectional switch controls a direction in which an electric current passes and converts the output from the transformer into AC power which has a second frequency. A switching signal generating circuit generates a switching signal for controlling the polarity of the bidirectional switch of the cyclo converter circuit in such a manner that the output voltage from the inverter circuit does not encounter a short circuit.

Abstract: A batteryless, portable, frequency divider includes a first resonant circuit that is resonant at a first frequency for receiving electromagnetic radiation at the first frequency; and a second resonant circuit that is resonant at a second frequency that is one-half the first frequency for transmitting electromagnetic radiation at the second frequency; and a circuit element electrically connecting the first resonant circuit to the second resonant circuit.

Abstract: A DC-to-AC electric power converting apparatus including an invertor circuit having a plurality of switching elements, a transformer connected to the invertor circuit, and a cyclo-converter circuit for converting the frequency of the output from the transformer. A carrier signal generator is provided for generating a carrier signal of a predetermined frequency.

Abstract: A DC-to-AC electric power converting apparatus includes: an inverter circuit for converting DC electric power into AC electric power; a transformer connected to the inverter circuit; a cyclo-converter circuit for converting the frequency of the output from the transformer; a carrier signal generator for generating a carrier signal of a predetermined frequency; an inverter switching circuit for generating a signal for controlling the inverter circuit in synchronization with the carrier signal; a reference voltage signal generating circuit for generating a reference signal for the AC voltage to be transmitted from the cyclo-converter circuit; a first switching signal generating circuit for generating a switching signal in accordance with the reference voltage signal supplied from the reference voltage signal generating circuit and the carrier signal supplied from the carrier signal generator; and a cyclo-converter switching circuit for generating a signal for controlling the cyclo-converter circuit in accordanc

Abstract: A power conversion apparatus capable of eliminating inexpedient higher harmonic components from its output, without lowering the conversion efficiency. The apparatus includes a first power converter for converting an input power from a power supply into an output power; a detector for detecting an output current and an output voltage of the first power converter; a high harmonic detector for detecting a higher harmonic component on a basis of the output current and the output voltage, and for producing current reference signal corresponding to the detected higher harmonic component; and a second power converter for producing an inverse of the detected higher harmonic component according to the current reference signal, and combining the produced inverse of the higher harmonic component with the output current of the first power converter such that the higher harmonic component in the output current of the first power converter are cancelled by the inverse of the higher harmonic component.

Abstract: An AC-to-AC converter operating as a current-source between an AC input line and an AC output line connected to a load, for instance an AC motor, includes three groups of bilateral switches controlled selectively within each group so as to generate a quasi square-wave current in each output phase while establishing a DC voltage between two of the output phases at a time, the third phase being idle, the magnitude of the output voltage being controlled in relation to the firing angle of the switches and the frequency being established by controlling the duration of each square-wave alternance. The duration of such alternances is set to 120 degrees of the output wave, followed and preceded by a 60 degree zero-current period.

Abstract: Frequency triplicator for microwaves having frequencies above about 30 GHz, for example 70 GHz, comprising a non-linear element of a weakly doped semiconductor material, in particular n-Si with a carrier concentration of 10.sup.13 cm.sup.-3 and less.

Abstract: The present invention achieves the above objects, among others, by providing apparatus for converting a supplied AC input signal into an AC output signal having a selected lower frequency than the frequency of the AC input signal, which apparatus translates individual half cycles of the supplied AC input signal to an intermediate output signal with selected amplitude and polarity such that during successive pairs of first and second periods, each such period corresponding to a predetermined number of half cycles of the AC input signal, the translated half cycles of the AC input signal all have the same first selected polarity during each first period and have the same second selected polarity during each second period, with the first and second polarities being opposite. The apparatus filters the intermediate output signal to develop the AC output signal having the selected lower frequency.

Abstract: In a direct AC to AC converter system the normal rectifier assistance functions are phase modulated by a 30.degree. lag and by a 30.degree. lead, and switching between lagging and leading function is effected at a high frequency according to a duty cycle: ##EQU1## and where .theta. is the electrical angle of the AC power supply, thereby insuring a sinusoidal input current in the system.

Abstract: The present invention provides a digital gate pulse generator which controls the output of a cycloconverter used for electrical power conversion applications by determining the timing and delivery of the firing pulses to the switching devices in the cycloconverter. Previous gate pulse generators have been built with largely analog or discrete digital circuitry which require many precision components and periodic adjustment. The gate pulse generator of the present invention utilizes digital techniques and a predetermined series of values to develop the necessary timing signals for firing the switching device. Each timing signal is compared with a reference signal to determine the exact firing time. The present invention is significantly more compact than previous gate pulse generators, responds quickly to changes in the output demand and requires only one precision component and no adjustments.

Abstract: A distributed balance frequency multiplier has a transmission line that is configured using lumped elements having connection points for inputting signals. Connected to each connection point is the output from a non-inverting amplifier which does not invert a signal applied thereto. A second transmission line is configured also using lumped element techniques and has connection points for receiving an inverted amplified signal whose odd harmonics are 180.degree. to the non-inverting amplified signals. The signal that is to be amplified is carried to both the non-inverting and the inverting amplifier by a third transmission line that also uses lumped elements distribution techniques to create a transmission line. The output of the first transmission line and the second transmission lines are tied together so that the odd harmonics due to the inverting amplification stages cancel and the even harmonics are additive, thereby achieving an effective multiplication of the input signal.

Abstract: Subject track lighting system comprises a more-or-less regular lighting track having at least two pairs of track conductors. Of these track conductors, an initial pair carries the regular 120 Volt/60 Hz power line voltage. Plugged into the track and connecting with the initial pair of track conductors is one or more voltage-conditioning adapters--with each such adapter receiving its input voltage from the initial pair of track conductors and providing its conditioned output voltage to one of the other pairs of track conductors. Thus, depending upon the particular functions provided by the adapters, the different pairs of track conductors may be used in independently different ways. For instance, with one adapter being a frequency converter with an output voltage of 12 Volt/30 kHz, the pair of track conductors to which its output is connected may be used directly with low-voltage Halogen lamps--while ordinary 120 Volt incandescent lamps may simultaneously be used with the initial pair of track conductors.

Abstract: The N converters of a UFC bridge system interconnecting an N-phase voltage source to N output loads, comprise each N bilateral switches connected to one end of the associated output load and (N-1) bilateral switches connected to the other end thereof. The (N-1) bilateral switches of the respective converters build up a polygonal assembly between the output loads which is selectively connected to the respective phases of the voltage source by selective control of the N groups of N switches and of the (N-1) groups of switches.

Abstract: A batteryless, portable, frequency divider consists of a single resonant circuit consisting of an inductor and a diode. The resonant circuit detects electromagnetic radiation at a first predetermined frequency and responds to said detection by transmitting electromagnetic radiation at a second frequency that is one-half of the first frequency. The circuit is resonant at the second frequency when the voltage across the diode is zero. The frequency divider is utilized in a presence detection system that uses a tag containing the frequency divider. The system transmits electromagnetic radiation at the first frequency into a surveillance zone, and detects the second frequency to detect the presence of the tag in the surveillance zone.

Abstract: A radio frequency multiplier circuit includes a first plurality of non-linear devices, each device having an input electrode and an output electrode. The input electrode of each one of the first plurality of non-linear devices is successively interconnected via a first input coupling means to a first input terminal. The multiplier further includes a second like plurality of non-linear devices, each device having an input electrode and an output electrode. The input electrode of each one of the second plurality of non-linear devices is successively interconnected via a second input coupling means to a second input terminal. A common output coupling means is provided to interconnect the output electrode of each one of the first plurality of devices with the output electrode of a corresponding one of the second plurality of devices. The multiplier further includes means for coupling a pair of signals having a 180.degree. differential phase shift to the pair of input terminals.

Abstract: A three-pulse UFC system uses three groups of three bilateral switches controlled according to a switch polarity pattern to generate AC currents to a load, and a deadband hysteresis having upper and lower limits is used to maintain the load current so as to match a reference current.

Abstract: The invention resides in providing bilateral switches between the respective phase lines of an AC input source and a common phase line of an AC output to form a phase line group of said bilateral switches on each AC output line; in fact, controlling the bilateral switches of each group so as to generate with AC input lines a DC link voltage with respect to the associated AC output line, and secondly in controlling the bilateral switches in such group to modulate such DC link voltage in relation to a desired AC voltage for such associated AC output line, each of said groups being operated with a corresponding phase shift to provide a corresponding phase shift between the respective output phase lines.

Abstract: A microwave frequency divider circuit. The frequency divider comprises a nonlinear amplifier including input and output ports for amplifying signals applied to the input port. The amplifier exhibits a nonlinear transconductance characteristic between its input and output ports. The amplifier input port is adaptable to receive a first signal having a frequency f.sub.l. The frequency divider further includes a feedback network coupled between the amplifier output and input ports to couple a second signal having a frequency f.sub.o appearing at the amplifier output port back to the input port. The first and second signals combine at the amplifier input port to modulate the nonlinear transconductance of the amplifier such that said first and second signals are mixed together and amplified. The circuit regeneratively oscillates such that the frequency f.sub.o equals a frequency f.sub.l /2. The frequency f.sub.l of the first signal is thus divided by the circuit.

Abstract: A three phase voltage system, balanced and sinusoidal, is converted into another one, having the same properties, but with amplitude, frequency and phase changed, by means of sequential sampling of all input phases. The desired output system is synthetized through a matrix of electronic switches, which are operated sequentially by control pulses having a duration proportional to the instant value of a linear combination of sinusoidal waveforms and with a duty cycle modulated accordingly to the required output parameters.

Abstract: A wideband microwave device for generating even harmonics of an incident microwave signal. A co-planar-type input structure conducts an incident microwave signal with an asymmetrical propagation mode. Two asymmetrical mode outputs of an equiphase divider are applied to respective inputs of two nonlinear circuit structures, whose respective output signals include even harmonics of the incident signal. The two outputs signals are combined in a circuit having an asymmetrical propagation mode output and which may be followed by a filtering circuit helping to isolate the desired even harmonic.

Abstract: A system for forming address signals which address respective converter switches in a frequency converter. The frequency converter is of the type wherein a DC voltage is provided for supplying electrical energy to phase outputs thereof in response to the states of the converter switches. In accordance with the invention, the phase output voltages, phase output currents, and predetermined desired phase currents are treated as space vectors from which are generated control difference space vectors. In one embodiment, a trigger pulse is generated externally and may be suppressed when the control difference vector has a value which is below a preselected tolerance limit. In a further embodiment, the trigger pulse is generated internally and is suppressed if the tolerance limit is exceeded. Upon the occurrence of each trigger pulse, a voltage space vector is addressed having a direction which is opposite to the control difference space vector.

Abstract: A phase modulated DC-to-AC or a DC-to-DC power converter utilizes input terminals connected to a source of power and output terminals connected to a suitable load. The transfer of power between the power source and the load or from the load back to the power source is accomplished by electronic switching that is phase displaced controlled in all four quadrants.

Abstract: This disclosure is concerned with a motor technique for generating speeds that are fractions of synchronous speeds, through novel time-staggered selected half-cycle energization of a plurality of magnetic poles by a controlled switching sequence, generating such a fractional motor speed that would otherwise have to be produced by a much larger number of magnetic poles.

Abstract: Electrical circuits, apparatus and methods for a variety of applications. A switching device subdivides an alternating current input signal into a plurality of lower voltage pulses by switching on and off in response to the characteristics, such as the voltage and current, of the input signal, and the pulses of current are intermittently passed to a capacitor in series with the device as the voltage on the input signal is positive-going. When the voltage becomes negative-going, the capacitor is discharged, usually with the pulses passing through the switch in the opposite direction. Work is done by energizing the series capacitor, or by energizing a capacitor in parallel with the switch, or by energizing an inductor in parallel or series relation to the switch, or a combination of the above. The inductor may be the primary winding of a transformer, or may create an electrical or magnetic field which is transduced into mechanical motion. The load may also be a resistive load.

Abstract: An amplifier-oscillator frequency multiplier apparatus utilizing a pair of servo-connected amplifiers which are electronically switchable to provide either a coherent amplifier or a non-coherent oscillator.

Abstract: A mixer is provided with a first waveguide part for the transmission of an input signal to be converted to a lower frequency band and with a second waveguide part for the transmission of a signal supplied by a local oscillator. The first and second waveguide parts open into a cavity containing a semiconductor which, disposed of its encapsulation, is mounted on a substrate and is used to obtain an output signal. The frequencies (f.sub.u) of the output signal form a linear combination of the frequencies (f.sub.s) of the input signal and the local oscillator frequency (f.sub.LO). The substrate comprises at least two microwave integrated circuits, forming a connection between the semiconductor and the two waveguide parts, while the mixer further comprises a transmission line for the output signal.

Abstract: A cycloconverter apparatus and method is disclosed in which the cycloconverter works into an active load. The cycloconverter is connected between an external power source and a load so that the load current flows through the cycloconverter. In the preferred embodiment, the cycloconverter is used to impress a signaling voltage waveform upon the voltages of the three phases of an electric power distribution feeder. This voltage is impressed by injecting it between the common point of the wye-connected secondary of the substation transformer and the grounded neutral that serves all phases of the distribution feeder. The neutral current of the distribution feeder flows through the cycloconverter. Protective by-pass circuitry is provided to maintain the integrity of the neutral path in the event of a phase-to-neutral short circuit or a failure of the cycloconverter.

Abstract: A harmonic mixer utilizing an anti-parallel configuration of two diodes which, when excited by a voltage waveform V.sub.LO sin .omega..sub.LO t + V.sub.s sin .omega..sub.s t where V.sub.LO is much greater than V.sub.s, yields a terminal current having angular frequency components m .omega..sub.LO .+-. n .omega..sub.s with the restriction that m + n is an odd integer. The diode configuration results in low conversion loss mixing when the local oscillator frequency is a subharmonic of the usually required local oscillator frequency, suppression of local oscillator noise sideband effects without the use of filters or hybrid junctions, and suppression of direct video detection.

Abstract: A varactor multiplier circuit is driven by a pulsed source of radio frequency and self-biased such that it operates in its snap condition to generate harmonic frequencies. The output pulse has essentially the same configuration and length as the input pulse. These pulse envelopes may have a relatively slow voltage build-up with time. A separate bias drive circuit is directly connected to the varactor and provides a negative-going pulse of sufficient voltage to bias the varactor to its off condition. This gating bias pulse is variable as to pulse width and is very steeply rising and serves to either turn on or cut off the varactor sharply to thus provide a shaped envelope of the output wave form. An isolating capacitor and a band stop filter operate to prevent loading of the multiplier circuit by the bias drive circuit and to prevent radio frequency leakage into the drive circuit.

Abstract: A protection arrangement for an inverter having fuses connected in series with its d-c inputs is disclosed. In particular, in one form of the arrangement, an electronic voltage monitoring device is provided for monitoring the input d-c voltage to the inverter at the connection points of the inverter inputs and the fuses. If the voltage monitored by the monitoring device falls below a predetermined level, the monitoring device delivers a protection signal to the control unit of the inverter directing the latter to release firing pulses for extinguishing the valves in the valves branches of the inverter.In another form of the arrangement, the voltage monitoring device monitors the voltage across each of the fuses at the d-c inputs of the inverter, and, if a monitored voltage exceeds a predetermined value, delivers a protection signal to the control unit of the inverter.