Abstract: Voltage and current supplied to the primary winding of the transformer-rectifier (T-R) set of an electrostatic precipitator via silicon-controlled rectifiers and a reactor are automatically controlled by sensing spit and spark discharges within the precipitator and the phase shift which occurs between line voltage and line current (usually referred to herein as primary current) when precipitator voltage drops to a low value, as caused by a heavy spark or arc. Signals are developed therefrom which are used to control precipitator voltage through phase control of the SCR's. An arc is extinguished at the end of the current one-half cycle in which it starts. An inhibit circuit is provided for preventing detectable transients caused by SCR turn on from falsely triggering the automatic control system thereby permitting increased sensitivity in the spit sensing circuit.

Abstract: Power supply and method in which the primary current to a transformer is switched on and off to maintain the output of the supply at a desired level. When the energizing current is off, an additional current is applied to the transformer to maintain the core at a level of magnetization such that the full hysteresis characteristic of the transformer is utilized during the next half cycle of operation.

Abstract: A switched-mode converter produces a periodic square-wave signal whose amplitude depends on the input d.c. voltage. This signal is applied to an inductive network. A rectifier and a smoothing capacitor are coupled to this network with the output d.c. voltage being present across the capacitor. The frequency of the square-wave signal is controlled in dependence on the input voltage, namely so that it is directly proportional thereto or that the period decreases at a greater rate than the input voltage increases. A further control, for example, a series control, can be used to regulate the output voltage.

Abstract: In a power supply circuit for an electrical apparatus, comprising a power transformer having its secondary winding connected to a smoothing capacitor via a rectifying circuit and having its primary winding adapted to be applied with an ac voltage, a switching means is provided for applying the ac voltage to the primary winding only for a selected period of time in a half cycle of this ac voltage and for terminating the application of this ac voltage before an arrival of a zero crossing point of the ac voltage, whereby allowing a voltage of a time length corresponding to a current flowing through the secondary winding to be applied to the primary winding of the transformer, to thereby inhibit a flow of unnecessary exciting current to the primary side. This power supply circuit also contributes to stabilization of the dc output voltage of the power supply circuit.

Abstract: First and second rectifiers (37), (41) have inputs connected to an A.C. power source (12) through a unitary switch (33) and outputs connected to first and second smoothing filters (38), (42) respectively. An inductance (39) is connected between the switch (33) and the first rectifier (37) whereas a capacitance (43) is connected between the switch (33) and the second rectifier (41). The values of the inductance (39) and capacitance (43) are selected in such a manner that surge currents through the capacitance (43) and inductance (39) occuring when the switch (33) is closed are limited and the power factor of the power supply (31) is maximized.

Abstract: A regulated power supply circuit includes a transformer having a primary winding and a secondary winding electromagnetically coupled by an iron core. A source of AC operating voltage is coupled to the primary winding of the transformer via an actuable switch means. A load circuit coupled to the secondary winding circuit is adapted to be energized by a voltage developed in the secondary winding circuit. Means are provided for sensing the polarity of each half cycle of said source of AC operating voltage. Memory means are coupled to the transformer for providing information representative of the polarity of each half cycle of the source of operating voltage applied to the primary winding of the transformer. The memory means are operable to maintain the information for a period of time when the switch is actuated to be opened. Means are also provided for sensing a parameter in the secondary winding circuit related to the energy available in the secondary winding circuit.

Abstract: A power converter which provides precise waveshape regulation. An input pr waveform (three-phase or single phase power) is rectified and modulated to form a chopped waveform within an envelope defined by the rectified input waveform. The modulation is removed by passing the chopped signal through a low-pass filter. The output of the low-pass filter, which is equal to the instantaneous value of the chopped waveform envelope times the instantaneous value of the duty cycle of the chopped waveform, is converted to a complete sine wave output voltage in a power inverter. The output of the power inverter is sampled and compared with a low-power reference waveform in a differential amplifier. The output of the differential amplifier is phase compensated for the effects of the low-pass filter and applied as an error signal to a pulse-width-modulated oscillator to adjust the duty cycle of the chopped waveform so that the sine wave output voltage follows the reference waveform.

Abstract: A voltage regulator circuit of the type including a transistor having a base, an emitter representing a voltage output terminal and a collector representing a voltage input terminal, and a zener diode connected in series with the base to represent a common input-output terminal, wherein voltage regulation is achieved by the constant reverse bias voltage drop of the zener diode in combination with the constant forward bias voltage drop of the emitter-base junction of the transistor, the improvement including a second transistor having an emitter representing a second voltage output terminal with respect to the common input-output terminal, and the second transistor further having a base connected to the emitter of the first transistor, wherein voltage regulation is provided for the second output terminal with respect to the common input-output terminal by the combination of the voltage regulation provided at the first output terminal and the constant forward bias voltage drop of the emitter-base junction of th

Abstract: The current supplied by an AC power source to a DC load is controlled so that full current is supplied to the load during steady state operation and partial current is supplied during transient conditions. A selectively energized series switch, including first and second parallel branches, is connected between the power source and the load. An impedance in series with one of the switches causes the partial current to be supplied by the power source to the load. The other parallel branch includes no such impedance and therefore feeds full current to the load. A voltage threshold detection circuit, having hysteresis characteristics, responds to the amplitude of the AC source to activate the switches so that no current can be passed through the switches in response to the source amplitude being less than the threshold level.

Abstract: A charge-transfer voltage converter transforms a high voltage to a lower value without the use of a conventional transformer. Two capacitors are connected together to form an electrical circuit. The circuit is then broken in one place and a switch is inserted to form a continuous circuit. One of the two capacitors is charged to a high voltage. The switch is turned on and off rapidly and this transfers a charge from the charged capacitor to one which was initially uncharged. By controlling the duty cycle and/or repetition rate of the switch between the two capacitors, the output voltage of the capacitor which was initially uncharged can be maintained between the limits of zero volts and the value to which the supplying capacitor was initially charged. Thus, voltage transformation has been achieved without the use of a conventional transformer.

Abstract: An electrical power supply circuit for converting alternating circuit power into a direct current output comprises a transformer and rectifier, a filter capacitor across the output terminals and a phase control switching device and a non-saturating inductor in the primary circuit. The circuit arrangement reduces the volt-time integral of the transformer and allows its core to be made of a smaller size, in comparison to the transformer cores of previously known power supplies, without danger of saturation. Other advantages such as low RFI, reduced transformer wire size and overload current protection are obtained. A commutator circuit may also be provided for turning off the phase control switching device before the end of the associated half cycle of input voltage to further reduce the transformer volt-time integral and to accordingly allow a further reduction in its core size.