Unsaturating composite magnetic core transformer, consisting of two separate parallel cores designed so impending core saturation causes signal generation, terminates high current spike in converter primary circuit. Simplified waveform, demonstrates transformer effectiveness in eliminating current spikes

Schwarz, F. C.

English

NASA Technical Reports Server

IL
I' 
I	 I 
----!--j 
(B) Suppression of 
Current Spike 
May 1971	 Brief 71-10142 
.
NASA TECH BRIEF 
Electronics Research Center	 4V 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the. Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D. F. 20546. 
Saturation Current Spikes Eliminated in Saturable Core Transformers 
The problem: 
To eliminate the high magnetization current spikes 
generated by saturable core transformers at the be-
ginning of core saturation. In dc-to-dc power con-
version circuits, these high current spikes cause over-
EC
ILLD . 
Figure 1.. 
heating of the power transistors, and denstruction 
eventually occurs. 
The solution: 
An unsaturating composite magnetic core trans-
former, consisting of two separate cores in parallel 
(see Fig. 1), designed so that the impending core 
saturation causes a signal to be generated, which
is then used to terminate the high current spike 
in the converter primary circuit. 
How it's done: 
The transformer comprises two uncut, saturable, 
magnetic cores C 1 and C 2 , stacked on top of each 
ith 
_,..e 
Figure 2. 
other. Each core has a pair of control winds Wri 
and Wr2, and sensing windings Wdl and W d2 con-
nected in series opposition. Both of the cores and 
their respective control windings are enclosed by 
common centertapped primary and secondary windings 
W 11 and W 21 , respectively, such that the individual 
cores operate in parallel within the same transformer 
core, C l . When connected in a conventional dc-to-dc 
inverter circuit, no signal appears across the resistor 
Rdas long as the cores are unsaturated, because the 
control windings have an equal number of turns and 
have opposite polarity. However, when one of the 
cores begins to saturate, a voltage Ed developed 
across Rd activates a switch that removes the input 
power. 
A simplified waveform (see Fig. 2) demonstrates 
the effectiveness of the transformer in eliminating the 
continued overleni) 
This document was prepared under the sponsorship of the National 	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States
	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	 . will be free from privately owned-rights.
https://ntrs.nasa.gov/search.jsp?R=19710000141 2020-03-17T02:24:13+00:00Z
current spikes. The actual circuit implementation for 
controlling the current flow requires a simple thres-
hold circuit and a sequencing circuit that prevents 
the continuation of the inverter cycle until S 1 has 
reopened. This operation virtually eliminates the main 
cause of power failure and enables the power transis-
tor to process twice the load current than is presently 
available. 
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
Headquarters 
National Aeronautics 
and Space Administration 
Washington, D.C. 20546 
Reference: TSP7I-10142
Patent status: 
This invention is owned by NASA and a patent 
application has been filed. Royalty-free, nonexclusive 
licenses for its commercial use will be granted by 
NASA. Inquiries concerning license rights should be 
addressed to: 
Patent Counsel 
Mail Code 200-1 IA 
Ames Research Center 
Moffett Field, California 94035 
Source: Francis C. Schwarz
Electronics Research Center 
(ERC-10125) 
Brief 71-10142	 Category Ol,02


Saturation current spikes eliminated in saturable core transformers

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server