Accession Number : ADD012347

Title :   Capacitor Charging FET Switcher with Controller to Adjust Pulse Width.

Descriptive Note : Patent,

Corporate Author : DEPARTMENT OF THE AIR FORCE WASHINGTON DC

Personal Author(s) : Mihalka,Alex M

Report Date : 29 Apr 1986

Pagination or Media Count : 16

Abstract : A switching power supply includes an FET full bridge, a controller to drive the FETs, a programmable controller to dynamically control final output current by adjusting pulse width, and a variety of protective systems, including an overcurrent latch for current control. Power MOSFETS are switched at a variable frequency from 20-50 kHz to charge a capacitor load from 0 to 6 kV. A ferrite transformer steps up the DC input. The transformer primary is a full bridge configuration with the FET switches and the secondary is fed into a high voltage full wave rectifier whose output is connected directly to the energy storage capacitor. The peak current is held constant by varying the pulse width using predetermined timing resistors and counting pulses. The pulse width is increased as the capacitor charges to maintain peak current. A digital ripple counter counts pulses, and after the desired number is reached, an up-counter is clocked. The up-counter output is decoded to choose among different resistors used to discharge a timing capacitor, thereby determining the pulse width. A current latch shuts down the supply on overcurrent due to either excessive pulse width causing transformer saturation or a major bridge fault, i.e,. FET or transformer failure, or failure of the drive circuitry. (Author)

Descriptors :   *PATENTS, *POWER SUPPLIES, *FIELD EFFECT TRANSISTORS, *SWITCHING, *PULSE TRANSFORMERS, MOSFET SEMICONDUCTORS, CAPACITORS, DIRECT CURRENT, COMPUTER PROGRAMMING, ENERGY STORAGE, RESISTORS, COUNTING METHODS, PEAK POWER, ELECTRIC BRIDGES, CONSTANTS, CONFIGURATIONS, FAULTS, TRANSFORMERS, BRIDGES, VARIABLES, INPUT, ELECTRIC CURRENT, DRIVES, TRANSFORMERS, CONTROL, FERRITES, PULSES, CIRCUITS

Subject Categories : Electrical and Electronic Equipment
      Electric Power Production and Distribution

Distribution Statement : APPROVED FOR PUBLIC RELEASE