Procedure for converting direct electrical energy into alternating electrical energy

A procedure for converting direct electrical energy into alternating electrical energy is disclosed. An apparatus sequentially sweeps the connecting points of a number of DC power supplies in order to provide an alternating current wave form. The sequential sweep of each consecutive connection point is carried out such that the second connection is initiated prior to disconnecting the first connection. Overlapping connections are not, however, used where there is a reversal of the direction of the current at the output terminals. The speed of the sweep may be varied in accordance with the specific frequency required for the alternating current wave form.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
As set out in the specification, this invention relates to a procedure for 
the conversion of direct electric current into alternating current by 
means of sequential switching, by which it is possible to obtain 
alternating currents of any desired voltage and frequency, using direct 
current sources of suitable characteristics. 
2. Related Art 
As is known, the present means of production and distribution of electrical 
energy, used at the international level, is oriented towards the use of 
alternating current, which implies basically that the vast majority of 
electrically driven apparatus available on the market is designed to use 
alternating current as supply power. 
However, in practice, it is relatively common that, for other geographical 
reasons, electrical power is not available in AC form, yet it is necessary 
to operate equipment which is designed for use with other than direct 
current. In such cases, where there is normally a storage battery or some 
similar unit, it is essential to make use of a convertor, which transforms 
the direct current into alternating current so as to permit the operation 
of the apparatus concerned from the previously mentioned direct current 
power supply. 
There are currently a large variety of convertors on the market, using many 
different schemes for obtaining improved performance according to the 
specific application or use, specifically as a function of the nature of 
the power supply, the power to be transformed, the frequency required, 
etc. 
The basic problem with such converters are that they consume an excessive 
amount of internal energy, which makes their use difficult, especially 
when the power supplies are low power, as frequently occurs where the 
classical battery is used and, as well, when photovoltaic energy is used. 
SUMMARY OF THE INVENTION 
The conversion procedure prepared in this invention resolves this problem 
by minimizing internal energy consumption, and is based on sequentially 
switching, by means of successive sweeps of link points, between different 
DC supply sources. This system can be designed, as will be shown 
subsequently, in a large variety of ways. 
In more specific terms, the present invention generates an alternating 
current wave form having clear, corresponding positive and negative 
half-cycles (which give it its "alternating" character) by taking the 
instantaneous values of the amplitude of a tension wave arrived at by 
means of sequential sweeps of connecting points of a number of DC power 
supplies. 
According to another aspect of the invention, the sequential sweep of each 
two consecutive link or connection points is carried out so that the 
connection at the second point is initiated prior to disconnection from 
the first. This is a feature of each complete cycle of the wave, except 
for polarity changes or points of reversal of the direction of the 
current, where a "0" energy situation is created before the reversal is 
carried out. 
In order to prevent short-circuiting between the DC supply sources, each 
link point of the sources is connected with the AC charge or outlet by 
means of uni-directional barriers. 
Preferably, within the positive half-cycle of the wave corresponding to the 
alternating current to be obtained, a permanent connection is established 
between the negative terminal of the overall DC feed supply group and one 
of the AC output terminals. In parallel, during the same positive 
half-cycle, the other output terminal is successively and sequentially 
connected to the positive terminals or connection points of the different 
supply sources so that, during the first quarter of the period, in which 
the output alternating current value is positive and rising, the supplies 
are successively added at this terminal; then, in the second quarter 
period, which completes this positive half period, a sweep is made in the 
opposite direction, in other words, progressively eliminating the sources 
which had been added sequentially in the first quarter period, until 
reaching the initial zero voltage point. 
In the second or negative half-cycle of the alternating output wave, the 
connections are reversed, i.e. the first terminal mentioned above remains, 
connected throughout the negative half to the positive output terminal of 
the supply source group as a whole, and the second terminal is connected 
to the sources, successively and sequentially with a sweep contrary to 
that of the previous half period, in an increasing direction during the 
third quarter period and a decreasing direction during the fourth quarter 
period which completes this second half-cycle. 
Another aspect of the invention is that the speed of the sweep may be 
varied at will, in accordance with the specific frequency which it is 
wished for in the alternating current to be obtained. 
As a further aspect of the invention, the DC sources are preferably 
connected so that the voltage at each link point, relative to the zero 
voltage point, is a function of the maximum amplitude of the voltage to be 
obtained in the alternating current, and of the angle of conduction of 
each link point, so as to obtain alternate sine, trapezoid, square or any 
other type of waves. 
As yet a further aspect of the invention a single generator or energy 
transformer, is preferably provided with means to establish several 
simultaneous sweeps, duly out of phase in the angular direction, so as to 
create a multi-phase alternating current. 
Preferably means for adjusting the link point conduction time is provided 
to permit adjustment in the AC output voltage. 
With suitable synchronism in the sweep onsets and in the corresponding 
sweep speeds, several AC generators may be coupled to operate 
simultaneously and in parallel be compatible with commercial AC 
distribution networks. 
Preferably, at the current direction reversal points, there are provided 
uni-directional barriers or static switches, for the recovery of the 
energy produced as a consequence of Lenz's law, with inductive means to 
store such charge, or else deliver the charge to a storage source. 
In terms of a preferential practice design, the sweep connections are 
preferably made with the assistance of static switches each of which is 
controlled by means of an impulse generation system with floating ground 
or earth. 
According to a preferred design, and as a further aspect of the invention, 
there is provided a system for the generation of impulses, the system 
having a floating ground, and two transistors connected so that the first 
conducts only when the second conducts and so that, through the base of 
the first, a signal is generated to a corresponding static switch 
according to the sequential impulses applied to the base of the second. 
The first transistor is connected to the static switch through the primary 
of a transformer having a suitable transformation ratio and core, designed 
in accordance with the frequency of the signal applied to it. The signal, 
for its part, is supplied by the transformer, duly rectified. 
Following rectification of the signal, and to limit the crest of the 
impulse at the level required, there may be provided resistive divider 
with a Zener diode.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
In the theoretical circuit of FIG. 1, it can be seen how the procedure 
being advanced is given form in the arrangement on a support (not shown) 
of four concentric tracks of electrolytic copper or any other conducting 
material, electrically insulated amongst themselves and with a 
cross-section in accordance with the current densities it is planned to 
pass through them. The said tracks are marked A, B, C and D in the 
drawing. 
Track A is divided into segments or sectors 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 
11 and 12 which are all of identical dimensions. While the number of 
segments may vary, there must always be a number of segments which is a 
multiple of the number of DC supplies used. In this case, provision has 
been made for the use of three sources of direct current, referenced L, M, 
and N, and twelve segments or sectors are used. 
Track B is continuous, in other words, it is made up of a single piece, 
without divisions. 
Track D, like B, is also of a single piece, undivided. 
The said tracks A, B and D are concentric; a cursor, P, collaborates with 
them, with its center of rotation coinciding with the point fixed by the 
concentricity of the tracks; the cursor, P, is rotary, being driven by a 
motor or the like not shown in the figure. 
Cursor P is designed to constitute the drive support element for four 
brushes Q-Q' connected together and intended to establish the point of 
electrical connection between tracks A and B, while brushes R-R' are also 
interconnected and in turn establish the connection bridge between tracks 
C and D. 
To return to the compartmentalization of tracks A and C, it should be 
emphasized that the size, and specifically the width of the brushes Q' 
must be more than the separation or distance between the different 
segments of track A, with the exception of the separation spaces between 
segments 1 and 12, between segments 6 and 7, which spaces define the two 
halves on this segmented track A, one half comprising segments 1-6 and 
theother segments 7-12. In this way, brush Q', on passing from one segment 
to another, makes contact with the second before losing contact with the 
first, except in the case where it passes from segments 6 to 7 and from 12 
to 1, where contact with the first segment is lost before contact is made 
with the second. 
The brush R, which travels on track C, is not as wide as the space between 
the two sectors, 13 and 14, of track C. 
According to the structure described, the different segments of the track A 
are sequentially connected with track B through brushes Q-Q' by means of 
the rotation of the cursor and, in the same way the two segments 13 and 14 
of track C are connected with track D, sequentially, through brushes R and 
R'. 
The multiple DC sources, three in the embodiment of FIG. 1, and marked L, M 
and N, respectively are interconnected in series and connected to the 
tracks as shown in FIG. 1 and as described below. 
As alluded to above P is drive, e.g., by a DC motor or the like which 
causes it to rotate at a speed corresponding to the frequency of the 
alternating current to be obtained. 
During each complete turn of the cursor, in other words, every 360.degree., 
an alternating current appears at the output terminals I-J at an amplitude 
which is in accordance with the number of DC current sources and their 
voltages, and at a frequency which is a function of the speed of the 
motor. In the embodiment of FIG. 1, at 3000 r/min, the frequency will be 
50 cps. 
The voltage of this alternative suitable current may be raised if desired, 
by fitting a transformer, 25, in series with the AC output, I-J. 
Specifically, the transformation process of the direct current into 
alternating current is produced as follows: 
When cursor P is between segments 1 and 12 of track A, brush Q' is isolated 
from that track so that track A, is cut off from track B, at the same time 
as brush R is located between segments 13 and 14 of track C so that track 
C is cut off from track D. With tracks B and D isolated, there will be no 
voltage at the I-J output terminals. 
From this point, during the rotation of the cursor, 23, brush Q' comes into 
contact with segment 1 of track A, which is at the positive potential of 
the battery L, i.e. at point F potential, in relation with point E, which 
in turn corresponds to the battery's negative potential, so that the 
positive potential F is supplied to the output terminal I through brush 
Q-Q', and negative potential E is transmitted to the output terminal J 
through brushes R-R' as these are opposed to the Q-Q' brushes within the 
cursor P. 
As cursor P continues in its advance, brush Q' will come into contact with 
segment 2 of track A before losing contact with segment 1, so that output 
I is connected to an increase of positive potential with respect to J, 
corresponding to the sum of the output voltages of battery L and battery M 
at point G. 
During the instant at which brush Q' is in simultaneous contact with 
segments 1-2 of track A, except for the diodes 15 and 16, the battery M is 
short circuited. In order to prevent problems from discharge current from 
this condition, an arrangement of blocking diodes 15, 16, 17, 18, 19, 20, 
21, 22, 23, and 24, are provided as shown in the diagram. 
Still following the movement of the cursor, brush Q' next contacts segments 
3 and 4 of track A and terminal I will receive maximum voltage as against 
terminal J, i.e., the voltage corresponding to connection H which voltage 
is a function of the number of batteries used. 
From segment 4 onwards, and during the cursor's clockwise movement towards 
segment 6 of track A, the respective connections with the supply sources 
F-G-H which previously resulted in an incrementally rising potential now 
result in an incrementally descending potential in other words, the real 
potential at point I will incrementally drop in the same manner as it rose 
during the movement along sectors 1, 2 and 3, until reaching zero, 
specifically at the point where brush Q' is located between segments 6 and 
7 of track A. 
During the 180.degree. rotation described, a positive hemicycle or half 
wave has been produced in terminal I-J. 
At the moment in which brush Q comes into contact with segment 7 of track 
A, brush R also comes into contact with segment 14 of track C, so that a 
change of polarity is given and, with it, a change in the direction of the 
current at terminals I-J. 
During the continued clockwise movement of the cursor from the beginning of 
segment 7 to the end of segment 12, in other words, during the remaining 
180.degree. of the complete cycle, the same phenomenon is created as in 
the first hemicycle, but now with the current in the opposite direction, 
i.e. so as to obtain the relative wave hemicycle. 
When the cursor once more moves to segment 1 of part A, brush R once more 
passes to segment 14 of track C and a new operative cycle of the system is 
initiated. 
In accordance with the following, at the output terminals I-J and in the 
secondary of the transformer 25, an alternating current is obtained having 
a voltage which is a function of the characteristics of the DC supplies L, 
M and N, and with a frequency which, is a function of the speed with which 
cursor P is rotates. 
As has also been pointed out above, by connecting the DC sources L, M and N 
so that the voltage at each link point F,G, H is a function of the maximum 
amplitude of the AC voltage to be obtained, and varying the angle or 
conduction time of each link point, it is possible to secure any type of 
wave within the general scope of alternating current, i.e., sinusoidal, 
trapezoid, square, etc. 
By synchronizing the sweep of cursor P with that of another similar 
generator, it is possible to couple the two generators in parallel. 
Further, by making simultaneous sweeps, in other words, by making use of 
several cursors which are out of phase by a pre-determined angle, it is 
possible to obtain poly-phased alternating current. 
It should be highlighted, as has also been pointed out above, that with the 
establishment at the points of reversal of the current of uni-directional 
barriers or static switches, it is possible to recover the energy which is 
generaed as a result of Lenz's law, with inductive charges, so as to 
secure energy utilization; this energy may be applied to the charge 
itself, or else fed to storage sources. 
As has been mentioned, the representation of FIG. 1, described 
exhaustively, has no further aim than to give a clear understanding of the 
procedure for the conversion of electrical energy as advanced here. For 
the practical design of this procedure, a circuit is used as shown in FIG. 
2, in which there are no moving parts, and in which the supply sources are 
marked number 30, and where the tracks and brushes have been replaced by 
static switches, 31, with their corresponding uni-directional barriers, 
32, and in which the same references, I-J, are used for the corresponding 
charge terminals or AC output terminals. Control circuits, 33, for the 
regulation of the static switches, 31, are shown in detail in FIG. 3. 
With this circuit, in FIG. 3, and, as has already been pointed out, it is 
possible to create control impulses for the static switches, 31, with 
floating earth or ground, in other words so that the said control impulses 
are insulated from any other circuit, in the general context of the 
convertor. 
Two transistors, 34 and 35, are used to do this; they are connected so that 
the emitter of transistor 34 is connected to the collector of transistor 
35 so that the former is able to conduct only as long as the latter does 
so. 
The collector of transistor 34 is connected to the supply, i.e. to the 
corresponding static switch, through the primary of a transformer 36, with 
a suitable transformation ratio, and with a core in accordance with the 
frequency of the signal applied to it. 
At the base of transistor 35, a series of impulses, 37, are applied, in 
sequential form, so as to define the conduction of the linking points, the 
oft-cited "sequential sweep". 
Both transistors will conduct during the period of the sequential impulse, 
37, applied to the base of transistor 35 and, as a consequence, in the 
secondary of transformer 36 a voltage, corresponding to the signal 38 
applied to the base of transistor 34, will appear having a voltage 
amplified as a function of the transformation ratio of the transformer 36. 
This signal is rectified with a full-wave rectifier, 39, on the diode 
bridge which is shown in FIG. 3, so as to obtain an impulse of duration 
equal to the duration of the pulse applied to the base of transistor 35, 
with an amplified voltage, and insulated from earth or ground, in other 
words, with a floating earth or ground, which will serve to control the 
conduction of the static switches at the linking points. 
As has also been pointed out aove, in order to perfect the impulse and cut 
the peak ripple, a resistive divider is used with a Zener diode, 40, which 
makes it possible to cut the impulse at the desired level so as to 
establish the up and down times likewise as required. 
It is not thought necessary to amplify this description for any expert in 
the field to understand the scope of the invention and the advantages 
derived from it. 
The materials, form, size and layout of the elements will be susceptible to 
variation, always provided that this does not involve an alteration to the 
essence of the invention. 
The terms in which these specifications have been set out must at all times 
be taken in their broad and nonlimitative sense.