Abstract: Efficient starting of solenoidal electric field discharge lamps is effected when a primary voltage exceeds a critical transition level. A starting potential may be applied to electrodes on the external surface of the lamp which are capacitatively coupled to a fill gas. Alternately, the electrodes may be disposed within the lamp envelope. Optimally, the starting electrodes are disposed along the axis of an annular transformer core at opposite ends of a tunnel region.

Abstract: A circuit and method is disclosed for detecting the presence of charges of appropriate magnitude and polarity on commutating capacitors of an inverter that converts a DC output current to a drive current of variable magnitude and frequency for driving an AC electric motor producing controllable rotation and torque. The presence of charges of appropriate magnitude and polarity is detected by measuring the voltages across the conduction controlled rectifying devices in the inverter. In addition, the existence of conduction controlled rectifying devices in the conducting state is determined by measuring the magnitude of the DC output current. An output signal is generated when the charges of appropriate magnitude and polarity are detected, which output signal is effective to allow the inverter to generate normal drive current.

Abstract: An inverter system for supplying variable frequency alternating current power to a load such as an a.c. motor includes an inverter bridge of controlled rectifiers which are selectively rendered conductive by the application thereto of gating pulses. The gating signals result from a control circuit which includes a voltage controlled oscillator responsive to a command signal having a d.c. magnitude and polarity which in turn outputs a signal having a substantially saw-tooth wave shape. Comparator circuits responsive to the saw-tooth wave shape signal provide timing pulses and direction signals which are applied to a shift register to effect movement of the register contents the extant status of which initiates the production of the gating signals for rendering the semiconductors conductive.

Abstract: An inverter system including a controlled direct current (d.c.) power source for providing a variable d.c. voltage to a variable output frequency inverter circuit by way of a suitable d.c. link, includes suitable circuitry for detecting a commutation fault or shoot-through condition within the inverter circuit and for taking appropriate remedial action to correct such condition. The shoot-through condition is determined as a function of the d.c. input current to the inverter circuit and the output alternating current (a.c.) of the inverter circuit. This determination is achieved by comparing signals representing the two currents at a fixed ratio, other than unity (e.g, at a fixed percentage of one to the other) so that the actual margin increases as the currents increase. Preferably a bias is also included in the comparison function so that a minimum differential is always required before a shoot-through determination is made.

Abstract: A controlled current inverter system including an inverter circuit having controlled rectifiers for supplying an output of variable voltage and frequency for application to a load; e.g., an electric motor, further includes a variable direct current power source for supplying electrical power to the inverter circuit. Protection against overvoltage conditions of the inverter circuit rectifiers is provided as a function of the inverter output voltage, current and the electrical characteristics of a load supplied by the inverter circuit. This protection takes the form of circuitry which anticipates a potential overvoltage condition and acts to reduce the output of the direct current power source and inhibit the firing of the rectifiers of the inverter circuit until such time as the potential overvoltage condition is eliminated.

Abstract: A controlled current inverter system forms the basis of an a.c. motor drive system for furnishing the motor load with a variable frequency, variable magnitude a.c. current from an inverter which is supplied from a variable d.c. current source by way of a d.c. link including an inductor. Torque is the control parameter employed in the system and the motor speed and torque are controlled through the control of motor flux and motor current, by maintaining a controlled ratio between the direct and quadrature motor currents, through separate control paths to the d.c. source and the inverter. A third control path functioning on the difference between the desired and actual motor flux serves as a modifier to the main control paths to improve overall operation and control. Means associated with the basic control paths provide for dynamic braking of the motor.

Abstract: A variable speed ac motor drive such as a controlled current inverter drive with load angle control generates an inverter frequency command signal which at low speed has a large ripple component and a small dc component representing the desired frequency. A variable frequency oscillator is responsive only to the dc component and supplies timing pulses to a ring counter which generates thyristor gating signals in the forward and reverse phase sequence. Smooth reversing over a wide range of torque is realized, and multipulse operation is inherent at low speeds to modulate the inverter output and minimize cogging torque.

Abstract: A controlled rectifier inverter system of the type in which the inverter circuit has capacitors across which voltages are developed as a function of the current output of the inverter, such voltages being utilized to commutate the rectifiers of the inverter circuit, includes means to limit the magnitude of the rise in output current between successive commutations of the rectifiers of a group to prevent the achievement of a current in excess of that which can be commutated by the voltages on the capacitors.

Abstract: A digital firing control circuit is disclosed for controlling the generation of firing pulses for the eight controlled rectifiers (thyristors) in a bridge power converter in five distinct operating modes as well as effecting a smooth continuous transition between modes. The circuit compares and combines a plurality of locally generated time related waveforms according to a predetermined control algorithm in response to an applied analog command voltage to control the d.c. output voltage as well as providing certain protection functions such as end stops or inversion limits. The locally generated time related waveforms comprise sets of square voltage signals generated in accordance with selected cross-overs of the line voltages of the a.c. sources as well as the cross-overs of six firing reference ramp voltage signals separated from each other by 60.degree. and extending 240 electrical degrees.

Abstract: The voltage drop in induction ionized lamps is reduced by utilization of annular magnetic cores of inwardly convex cross section. Core power dissipation may be minimized by use of cores having a circular cross section. Lamp voltage drop may further be reduced by eccentrically positioning the core within a substantially globular lamp enevelope.

Abstract: A circuit for shutting down an inverter that includes at least a series combination of first and second gate controlled rectifiers and a load. The circuit is comprised of means for sensing the direction and magnitude of the instantaneous current flowing through the load, and means responsive to the direction and magnitude of the sensed current for generating an output signal when the magnitude of the current exceeds a predetermined threshold level and the current is flowing in a first direction. The circuit further comprises means responsive to the simultaneous receiving of a shutdown signal and the generated output signal for further generating a gating pulse to be applied to the second gate controlled rectifier to cause the current flowing through the load to quickly extinguish. Further included is means responsive to the shutdown signal for inhibiting further regular gating of the gate controlled rectifiers to ensure quick turn off of the inverter.

Abstract: A constant voltage square wave inverter drives a load connected as the damping element in an otherwise high Q, resonant matching circuit. The frequency of the inverter is maintained near the resonant frequency of the load circuit to provide substantially constant load power.The frequency of the inverter operation may be maintained near load circuit resonance by forcing commutation of the square wave output voltage as the rate of change of load current is substantially zero. The inverter output voltage may also be commutated as the peak current reaches a predetermined reference value to stabilize inverter operation for loads which cannot accept real power.

Abstract: A high frequency inverter power supply includes a high power inverter section powered by substantially unfiltered rectified a.c., and a control section including rectifier and filter means for providing substantially pure d.c. to maintain continuous instantaneous control over the high power inverter section. High frequency transformer means and optional output rectifiers and filters provide for a.c. or d.c. output.

Abstract: A variable frequency AC source drives a gas discharge lamp which is connected in parallel with the capacitance of a series resonant circuit. The polarity of the voltage applied to the resonant circuit is commutated at such times as the rate-of-change of current flow in the resonant circuit is at or near zero. The source frequency is thus maintained at or near the circuit resonant frequency to maintain high output voltage when the lamp is starting or reigniting.The polarity is also commutated at such times as the current flow from the source reaches a predetermined level. Lamp current is thus controlled in the running mode.

Abstract: Method and apparatus for start and hot restart of a high pressure arc discharge lamp includes the application of an AC ionizing potential to the lamp, the ionizing potential characterized by a period such that the electron density of the fill material of the lamp is increased on each half cycle of said potential until the lamp is started. The invention is disclosed in an integrated ballast, and in an addition to an existing conventional ballast.This application is a continuation-in-part of Ser. No. 506,116, filed Sept. 16, 1974, and now abandoned.

Abstract: A push-pull ballast for an arc discharge lamp has a high power portion comprising a semiconductor switching inverter and transformer means for step-up or step-down of voltage to be supplied to a load and a low power portion comprising control means sensitive to load parameters as, for example, load current which provides instantaneous control over the switching inverter thereby providing the advantages of high input power factor and precise control over the load voltage and current characteristics.

Abstract: Full-wave and half-wave rectifier circuits are disclosed; the former circuit using two transistors and the latter circuit using one transistor. In both circuits transistors are connected in an inverted mode so that, for example, with an NPN transistor current flow is such that line current flows into the emitter and load current flows out of the collector. Furthermore, voltage blocking is performed by the collector-base junction instead of the emitter-base junction. High efficiency is achieved by controlling the transistor base current in response to the emitter current so that the base current is proportional to the emitter current and is also at an optimum magnitude so as to minimize circuit losses.