Burroughs, Inc.

Gm Global Technolgoy Operations, Inc.

Truman T Schmalzriedt

Daniel A Wisner

Paul Anthony Battiston

David R Lancaster

Flavius A Mathamel

David C Schlick

An electrical system for supplying power to an electrical resistive heater that heats the catalyst of a catalytic converter. The electrical system includes an alternating current generator that has an output winding and a field winding that is carried by the rotor of the generator. The rotor is driven by an engine on a motor vehicle. The motor vehicle loads, including a storage battery are supplied with current by a first bridge rectifier that is connected to the output winding of the generator. The resistive catalyst heater is supplied with current by a circuit that includes a step-up transformer connected between the output winding of the generator and a second bridge rectifier that feeds the heater. The system can be operated in a high power mode for supplying a higher level of power to the heater. In the high power mode, the motor vehicle loads and battery are disconnected from the first bridge rectifier while still allowing the battery to supply current to the electrical loads, a voltage regulating means for controlling field current is disabled and the field winding is supplied with a predetermined current and the engine idle speed is increased. The output voltage of the second bridge rectifier is controlled as a function of the temperature of the catalyst and the output voltage of the second bridge rectifier can be pulse-width modulated.

System for supplying power to an electrically heated catalyst

A voltage regulator for converting an unregulated input voltage into a regulated D.C. voltage. The voltage regulator includes a driver transformer which periodically receives energizing current from a voltage source through a transistor switch. A switching regulator controller regulates the conduction time of the transistor so as to control the amount of energizing current supplied to the driver transformer. The driver transformer secondary windings drive the base of output transistors which, when conducting, connect the primary windings of an output transformer to the voltage supply. A capacitor is connected in parallel with the primary winding of the driver transformer so as to short circuit the primary winding of the drive transformer when the driver transistor is turned off. The current flow in the secondary of the driver transistor causes removal of the stored base charge from the output transistors which decreases the turn off time of the output transistors. The primary windings of the output transformer are connected in series with first and second capacitors connected between the common junction of the primary windings and the voltage supply to effectively create a virtual ground at the common junction. One end of each of the secondary windings of the output transformer is connected to Schottky diodes arranged in a full-wave, center tapped rectifier configuration. A hollow ferrite sleeve is disposed around a conductor connecting each Schottky diode with a secondary winding and provides sufficient inductance to protect the Schottky diodes from transient reverse overvoltages.

Voltage regulator

An apparatus that provides constant illumination in response to an AC input power source having variable magnitude. The input power passes through a full wave rectifier and is then switched by a solid state switching device having conductive and nonconductive states to a passive L-C filter. The output of the filter energizes one or more lamps to provide the illumination. A phase control circuit is responsive to a sync signal from the full wave rectifier and a feedback signal from the output of the filter and controls the phase angle conduction time of the solid state switching device at a repetition rate related to the frequency of the AC input power to provide constant illumination from the lamp.

Constant illumination apparatus

D.C. power supply having a reactive buck automatic D.C. voltage regulator which directly controls the rectified D.C. output of a loosely coupled transformer thereby providing load regulation from an unregulated alternating current source. The load current passes through the secondary winding of an auxiliary buck transformer and is stepped down to a much lower value in the primary winding of the auxiliary buck transformer. The primary winding of the auxiliary buck transformer is coupled to an isolated winding on the core of a ferroresonant C.V.T. transformer which receives the unregulated alternating current input signal, and the coupling between the isolated winding and the primary winding of the buck transformer effects a bilateral energy transfer between the two transformers which effects a real time reactive compensation which regulates the D.C. output of the power supply for changes in the input voltage and in the load while conserving the energy which would normally be wasted in achieving regulation by transferring it back to the resonant circuit via the bilateral energy transfer between the two transformers. The control system is set up so that the auxiliary buck transformer is normally bucking under all line and load conditions when the frequency is precisely at the resonant frequency of the saturable inductor and capacitor. A frequency shift either above or below resonance simply changes the amount of bucking that takes place in a complimentary manner. It should be noted that little power is consumed during the buck process as the power is returned from the auxiliary buck transformer to the loosely coupled ferroresonant transformer. The operating point of a negative feedback system which determines the point about which the bilateral energy transfer occurs, may be fine-tuned by an error-sensing feedback circuit for altering the voltage level which the coupling network operates to hold constant by controlling the bilateral energy transfer. A capacitor is provided across the primary of the auxiliary buck transformer to reflect capacitance into the secondary winding during conditions of little or no bucking action in order to enhance the stability of the regulator.

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Farmington Hills, MI, United States of America

Truman T Schmalzriedt