Capacitor charging FET switcher with controller to adjust pulse width

Patent · Tue Dec 31 23:00:00 EST 1985

OSTI ID:865832

Mihalka, Alex M ^[1]

---

1. Livermore, CA

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.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA
• DOE Contract Number: W-7405-ENG-48
• Assignee: United States of America as represented by United States (Washington, DC)
• Patent Number(s): US 4586118
• OSTI ID: 865832
• Country of Publication: United States
• Language: English

Related Subjects

/363/
20-50
adjust
adjusting
bridge
capacitor
causing
charge
charges
charging
choose
circuitry
clocked
configuration
connected
connected directly
constant
control
controller
counter
counter counts
counting
counts
current
current control
dc
dc input
decoded
desired
determining
digital
directly
discharge
drive
drive circuit
drive circuitry
due
dynamically
energy
energy storage
excessive
failure
fault
fed
ferrite
fet
fets
final
final output
frequency
held
held constant
including
increased
input
khz
kv
latch
load
maintain
major
mosfets
output
output current
overcurrent
peak
peak current
power
power supply
predetermined
primary
programmable
programmable control
programmable controller
protective
pulse
pulse width
pulses
reached
rectifier
resistors
ripple
saturation
secondary
shuts
steps
storage
storage capacitor
supply
switched
switcher
switches
switching
switching power
systems
timing
timing capacitor
transformer
up-counter
variable
variable frequency
variety
varying
voltage
wave
wave rectifier
width