I. TECHNICAL FIELD
[0001] The present invention relates to alternating current regulation. Specifically, it
provides a method and system for low cost regulation of alternating current applications
and includes embodiments that may be useful for ac fault simulation, non-linear load
power factor correction, and reactive load correction in three phase systems.
II. BACKGROUND OF THE INVENTION
[0002] In the generation and delivery of power, utility companies must face natural problems
such as tree limbs falling across power lines, ice storms which may create ice loads
on power lines causing them to fall, lightning strikes on power lines, and many types
of electrical defects which can occur in substations. These problems can and often
do cause disturbances on power being delivered to the utility customers.
[0003] These disturbances may or may not cause the user of the power, the utility customer,
problems. Some industries, such as petroleum processing plants, and residences, are
usually not much affected by these disturbances, provided that sensitive equipment
such as electronics are protected by surge suppressing devices. Other industries,
such as data processing centers and semiconductor fabrication plants, can be seriously
affected by surges or dips on the power coming into their facilities. In the former
case loss of data is possible and in the latter loss of product; in both cases the
losses are often extremely expensive, and can run to the millions of dollars for an
incident or disturbance which may last only a few cycles of the incoming power (that
is, for a small fraction of a second).
[0004] Many studies of power quality at various sites have been conducted, and they typically
show that, while surges in power do occur, they make up a very small fraction of the
total problem, and the dominant disturbance which causes expense is a dip, or momentary
reduction in power. Typically the dip is a reduction in voltage of less than 50% of
the nominal voltage, with a duration of less than one second. In one study, 95% of
the problem-causing disturbances were dips in voltage which lasted less than 20 cycles
(1/3 second) and in which the magnitude of the dip was less than 30% of nominal (i.e.,
70% of the voltage remained). In another study, of an average of five dips per month,
the majority of voltage dips were to a voltage of from 70% to 90% of nominal, and
most sags had a duration of 10 cycles or less. From these studies one can see that
if a regulator were available which could handle dips as large as 50% (that is, could
provide a steady output in the presence of as little as half nominal voltage), a very
large fraction of the problems would be ameliorated.
[0005] There are a number of prior art technologies which can be brought to bear to bring
the power quality at the user's load to a level which does not cause problems. One
such technology is the Dynamic Voltage Restorer, or DVR. This device can do voltage
correction, or regulation, for a brief period, and works by adding a compensating
voltage to the power line to correct for a "sag" or dip in the power line voltage.
It is generally not designed to protect against complete outages or severe dips. The
DVR is a transformer with multiple taps such that electronic switches, usually thyristors,
can be switched to provide a "boost" of fixed amounts, such as 5% per step. Thus a
voltage of 5, 10, 15, 20% or other multiple of 5% can be added to the power line at
its output. The DVR can be made very large, and therefore capable of handling megawatts
of power, and at high powers is reasonable in cost per kilowatt. Its disadvantages
are the inability to provide smooth output power, as it can only switch in steps,
and its large size and weight. Because of this large size and weight, it is not a
portable device.
[0006] A second technology used to ameliorate these problems is the High Speed Electronic
Transfer Switch, or HSETS. The HSETS is used when an alternate source of power is
available from the utility. That is, the utility runs two power lines into the customer's
facilities, one from each of two substations, and the HSETS can switch the input power
to the facility from a source with a lowered voltage level to the second, backup source,
which presumably is undisturbed. Of course, optimum performance requires that the
two sources be as independent of one another as possible, as a dip on both cannot
be dealt with. The cost is not high per megawatt handled, but as it must be installed
together with an alternate power feed from a separate substation, and must handle
the entire power load of the facility, the installation, or initial, cost is high,
generally over $1,000,000.
[0007] A third solution involves storage of energy. In this case a storage unit stores energy
which may be used to supplement the utility power during a dip and therefore provide
unblemished power to the user's load. The energy storage may be through an electric
field device, such as a capacitor, a magnetic field device such as an inductor, a
chemical device, such as a battery, or a mechanical device, such as a flywheel/generator.
Such devices have the advantage of being able to supply power during a complete outage,
or blackout, because they can deliver the energy they have stored during normal operation.
Also, they can maintain a constant output of power during a dip without drawing a
proportional additional current from the incoming power line again because of the
stored energy. They have two principal disadvantages: they are costly, and the stored
energy can be dangerous if a fault causes it to be released abruptly.
[0008] Heretofore, then, there have been solutions to the problem of inferior power quality
but they have been either expensive, or are affordable only for large power users,
and all are large and heavy, making them unsuitable for portable installation.
[0009] A regulator of low frequency ac power as described heretofore is also an adjuster
of low frequency ac power. As used herein, the term "regulator" implies a unit which
contains circuitry to maintain the output voltage, current, or power at a constant
value independent of changes in input line voltage or load impedance. The term adjuster
encompasses the concept of a regulator, but also may be used to describe a circuit
which merely raises or lowers the output power, without the circuitry to maintain
the output constant under changing conditions. That is, a regulator is a special case
of the adjuster, with the regulation circuitry required to maintain the output.
[0010] Heretofore there has been available variable transformers which can provide continuous
adjustment, without regulation, of low frequency ac power, but these "variable auto
transformers" are large, expensive, and heavy and have sliding contacts, or "brushes"
which wear in time and cause reliability problems.
[0011] The high cost of power dips is due to poor power quality on the one hand, and poor
immunity on the part of equipment of certain types on the other. To address this,
some organizations are setting standards for equipment behavior under conditions of
power dips, and requiring newly designed equipment for their use be able to withstand
dips of larger magnitude for short times and lesser magnitude for longer times. In
one case, as an example, a standard has been proposed which would require that equipment
operate normally in the presence of a power dip of up to 50% for three to twelve cycles,
30% for twelve to thirty cycles, and 20% for thirty to sixty cycles. Testing equipment
to ensure that it meets this standard is not easy. For one thing, the equipment must
be run in actual production conditions to ensure that the test is valid with regard
to "normal" operation, but another difficult task is to simulate the dip on the power
line. This is not so hard if the times involved are long, but if the equipment would
operate through a power dip of 50% for 0.2 seconds (12 cycles at 60 Hz) but not longer
(thus meeting the specification), the test setup must create a dip of just that length
and no longer. This precludes the use of relays and mechanical contactors. Also, the
test, to be accurate, must start a dip at any phase of the power line, and this requires
a nicety of timing not possible with mechanical devices. The only device available
which can switch voltage levels fast enough is the DVR, and the nature of the semiconducting
devices (thyristors) permits changes to be made only at the end of cycles if they
are to last for a number of full cycles, and in any event the DVR is not portable,
and portability is very important in test equipment.
[0012] Some loads have an entirely different problem for the power source: they have poor
power factor. If the root-mean-square voltage times the root-mean-square current (called
the VA product) is larger than the power, which can happen if there is a reactive
component to the load impedance or if the load is non-linear, then transformers, circuit
breakers, and other power delivery components must be increased to accommodate. The
ratio of power to VA product is called the power factor. If this ratio is less than
about 0.9 it begins to be a problem in the power system, and in many districts the
utility may charge more per unit of power if a facility has a low power factor. There
are methods available to correct power factor if caused solely by reactive components,
but there is not currently available a small, lightweight, inexpensive method of correcting
power factor in large installations due to non-linear loads. Also, the methods used
to adjust for poor power factor due to reactive loads can be bulky and awkward and
it would be advantageous to have available a small, lightweight method of accomplishing
correction of power factor even for reactive loads.
III. DISCLOSURE OF THE INVENTION
[0013] It is an object of this invention to provide a reliable design for a low frequency
ac voltage regulator with fewer parts and more reliable parts than prior art designs.
[0014] It is a further object of the present invention to provide a design for a low frequency
ac voltage regulator which is simple and which can be manufactured easily at a manufacturing
cost lower than prior art designs.
[0015] It is yet a further object of the present invention to provide a design for a low
frequency ac voltage regulator which can be smaller and lighter in weight than prior
art designs, permitting it to be used in portable designs. Naturally, this may enhance
the scope of application of such regulators.
[0016] It is also an object of the present invention to provide a design for a low frequency
ac voltage regulator which can achieve stable yet faster control over its output power
than was possible using prior art techniques.
[0017] The present invention also has the object of providing more stable performance into
critical loads in the presence of incoming power which may vary rapidly.
[0018] It is yet another object of the present invention to provide a design for a low frequency
ac voltage regulator which is capable of supplying smooth output waveforms, even in
the presence of sub-cycle transients on the incoming power.
[0019] It is a further object of the present invention to provide a design for a simulator
capable of supplying reductions ("dips") in an otherwise steady power stream which
are short (<1 sec) and controllable to a small fraction of a cycle.
[0020] It is another object to provide a means for correcting power factor in a power system
due to non-linearity in the power load.
[0021] It is yet another object to provide a means for correcting power factor in a power
system due to reactive components in the power load.
[0022] Accordingly, the present invention provides a novel circuit operating at high frequency
which can produce an output voltage higher than its input voltage without transformers
or low frequency inductors, using switchmode power supply techniques, and a related
circuit which can produce an output voltage smaller than its input voltage without
transformers or low frequency inductors, also using switchmode power supply techniques.
Both circuits can, with suitable control circuitry, correct power factor.
[0023] Naturally, further goals and objects of the invention are disclosed throughout other
areas of the specification and claims.
IV. BRIEF DESCRIPTIONS OF THE DRAWINGS.
[0024]
Figure 1 is a simplified circuit diagram of a dc "boost" circuit as used in dc power
supplies.
Figure 2 is a simplified circuit diagram of a dc "buck" circuit as used in dc power
supplies.
Figure 3 shows the output of the regulator circuit with a sinusoidal input.
Figure 4 shows the output of the regulator with a bipolar sinusoidal input waveform.
Figure 5 is a simplified circuit diagram of a boost regulator circuit according to
the teachings of the present invention for regulation of single phase power lines.
Figure 6 is a simplified circuit diagram of an ac buck regulator circuit according
to the teachings of the present invention for simulation of single phase power line
dips.
Figure 7 is a representation of an oscillogram of a three-cycle power line dip, the
top and bottom dashed lines showing the nominal voltage, the inner dashed lines showing
the reduced line voltage, solid reduced sinusoid showing an unregulated dip, and the
dashed sinusoid showing the regulated output.
Figures 8a and 8b are representations of two alternative circuits which permit the
use of unipolar switches in alternating current circuits. Figure 8a shows a series
field effect transistor arrangement; Figure 8b shows a parallel field effect transistor
arrangement. In each, the inner connections (small circles) indicate the drive signal
connections.
Figures 9a and 9b are block diagrams of two types of three phase voltage regulator
circuits according to the teachings of the present invention. Figure 9a shows a Y-Δ
connection three phase regulator; Figure 9b shows a Δ-Y connection three phase regulator.
V. BEST MODES FOR CARRYING OUT THE INVENTION
[0025] As can be seen from the drawings, the basic concepts of the present invention may
be embodied in many different ways. The concept of a "boost" regulator is well known
in the prior art. Referring to Figure 1, which shows a classical dc boost regulator,
its operation will be explained. The dc source of power is connected through inductor
3 and diode 5 to load 7. Switch 4 is connected from the junction of inductor 3 and
diode 5 to the dc power common lead, as is the other terminal of load 7. Small capacitors
2 are used at both the input and the output to filter high frequency transients.
[0026] The circuit operates as follows: Switch 4 is closed periodically at a frequency f
s for a fraction η of the period 1/f
s. During the time the switch is closed current rises in inductor 3 at a rate equal
to the input voltage V
i divided by the inductance L of inductor 3. When switch 4 opens, the magnetic field
of inductor 3 starts to collapse, which causes the voltage across switch 4 to rapidly
rise. This causes conduction of diode 5, carrying the inductor current into load 7,
at a higher voltage than V
i. There is therefore a voltage difference across the inductor equal to the output
voltage V
o minus the input voltage V
i. This voltage difference causes a drop in the current in inductor 3, at a rate of
(V
o-V
i)/L. In steady state, this drop in current (when the switch is open) is equal to the
rise in current when the switch is
closed: Here t
c is the time the switch is closed and t
o is the time it is open. Since t
c+t
o=1/f
s, and t
c=η/f
s, the above equation provides the result that
So the duty cycle η of the switch determines the ratio of the output to input voltage,
called the "boost" factor, V
o/V
i. If the switch is closed for only a small fraction of the total period, the factor
η is small, and the output is nearly equal to the input. As the switch is closed a
larger and larger fraction of the total time, the output voltage increases relative
to the input. For the output to be held steady during the time the switch is off,
the inductance L must be large enough to support a small change in current; this value
depends upon the resistance R of the load 7 as well in a manner well known to those
skilled in the art. Diode 5 conducts only when switch 4 is open, so the diode and
the switch conduct alternately.
[0027] A close relative of this circuit provides a "buck" circuit, as shown in Figure 2.
Here the diode 5 has exchanged positions with the switch 4 as compared to the boost
circuit, and the circuit reversed input-to-output. Analysis of the operation of the
buck circuit is along the same lines taken with the boost circuit. Here when the switch
is closed the difference between the input and the output voltage appears across inductor
3, and when the switch is open the diode conducts to maintain the current in inductor
3 (note again that the switch and the diode conduct alternately). Equating as before
the rise and fall of the current in inductor 3 in steady state yields:
and
assuming that the current flow in inductor 3 is continuous.
Here, of course, the output voltage is smaller than the input voltage.
[0028] Both circuits can operate as dc transformers; that is, at a fixed duty factor η they
have a constant ratio of input to output voltage. Thus, if connected to a source of
varying dc voltage, the output variation will be a faithful representation of the
input variation, but multiplied by the transformation ratio, which is bigger than
unity for the boost circuit and smaller than unity for the buck circuit, provided
that the switching period t
c+t
o is short compared to the variations in the input voltage. This is represented in
Figure 3, wherein is depicted the beginning of a sinusoidal waveform. Superimposed
on this is a series of pulses, each representing the closing-of switch 4, with the
output waveform represented by the dark line. As can be seen, the dark line approximates
the sinusoid, and would more closely approximate it if the frequency of the pulses
were higher (that is, if the pulses were more closely spaced). Either of the two circuits
will produce this result, with the boost circuit "amplifying" the input voltage and
the buck circuit "reducing" it.
[0029] Both of these circuits operate only on direct current. For the circuits shown in
Figures 1 and 2, and for the output shown in Figure 3, the polarity of the power source
is shown as positive (positive up). For a circuit operating on a negative supply (negative
up), one would reverse the direction of the diode. Of course, in either case the switch
must be arranged to conduct electricity in the appropriate direction.
[0030] Neither circuit can operate with an alternating input, because of the necessity of
polarizing both the diode and, generally, the switch. It will be clear that it is
not possible to simultaneously select the diode orientation and switch polarity for
positive and negative input voltages. This has prevented using these circuits for
alternating power in the past.
[0031] Either circuit could be made to operate in a bipolar mode (i.e., with ac power),
however, if advantage is taken of the fact that the diode and the switch conduct alternately.
That is, if the diode is replaced by a switch, the circuit would operate on ac input,
provided that the switches could conduct in both directions. A semiconductor switch
is generally able to operate in one direction of current flow only, but if the switch
is placed within a diode bridge, the action of the four diodes is to force current
flow through the switch always in the same direction regardless of the direction of
current flow external to the bridge. If the semiconductor switches were, then, replaced
by a switch surrounded by a diode bridge, and if two switches are used, both halves
of a sinusoidal input waveform could be handled with either a boost or buck configuration.
This approach permits the regulation of alternating powers. In this mode, (without
the reserve mentioned below) a boost circuit may be used to compensate for dips in
the incoming power, and a buck circuit may be used to compensate for surges.
[0032] Generally, power dips may be of larger concern as they are more common. Thus a boost
topology may be of higher practical value in some applications. However, even with
only a boost configuration, by adjusting the input to be smaller than nominal (such
as through the use of an autotransformer), thereby requiring a certain level of boost
at nominal line, an amount of power surge could be handled by a boost topology as
well.. This could occur -- without combining or perhaps further switching between
boost and buck circuitry -- by lowering the nominal boost level during the power surge.
Conversely, a buck circuit intended to handle surges may be used to handle a certain
level of dips perhaps through a similar use of an autotransformer to provide slightly
higher than nominal voltage, requiring a certain level of bucking action at nominal
line. This "reserve" of buck may then be used to provide a measure of compensation
for dips. In either case, the reserve (of buck or boost) and be available to handle
at least some amount of an opposite condition.
[0033] Returning to the basic arrangement for understanding, the resulting output is represented
in Figure 4. Here each rectangle indicates a complete cycle of the switches in the
circuit and again the dark line indicates the nature of the approximated output. Also
as before, the higher the switching frequency (the shorter the period of the pulses)
the closer the dark line would approximate the sinusoid. And again, either of the
two circuits will produce this result, with the boost circuit "amplifying" the input
voltage and the buck circuit "reducing" it.
[0034] The resulting circuits are shown in Figures 5 and 6 for the boost and buck circuits
respectively. Either of the two circuits will produce the result shown in Figure 4
for a sinusoidal input, with the boost circuit "amplifying" the input voltage and
the buck circuit "reducing" it.
[0035] In Figures 5 and 6, the ac input power 14 is applied to the circuit, and inductor
3, capacitors 6 and load 7 perform in the same roles as they had in Figures 1 and
2. Switch 4 and diode 5, respectively, have each been replaced by a diode bridge 8
and 10, respectively, surrounding a semiconductor switch 9 and 11, respectively, here
shown as an Insulated Gate Bipolar Transistor (IGBT), but it should be noted that
this switch could be replaced by a Field Effect Transistor (FET), Bipolar Junction
Transistor (BJT) or other kind of electronic switch as would be known by a worker
skilled in the art. As should be easily understood, these circuit elements serve as
bi-directional switch elements 12 and 13, respectively. The parallel bi-directional
switch-element 12 replaces the switch in the boost arrangement; the series bi-directional
switch element 13 replaces the diode in the boost arrangement. Similarly, in the buck
circuit arrangement shown in Figure 6, the parallel bi-directional switch element
12 replaces the diode in the buck arrangement; the series bi-directional switch element
13 replaces the switch in the buck arrangement. Also, in each the diode bridge could
be replaced by a series combination of FET devices, as shown n Figure 8a, or by a
pair of series combinations of a diode and FET, said pair of elements placed in parallel,
as shown in Figure 8b. Other combinations are possible as well, and any circuit which
permits bilateral flow of current to be controlled by a drive signal will serve the
purpose of the invention.
[0036] Also, not shown in Figures 5 and 6 is the circuitry required to provide a drive signal
to the semiconductor switch, or the logic to determine the timing of the drive pulses,
as the exact method of accomplishing this would also be apparent to a worker skilled
in the art. Naturally, for the regulator, circuitry would be required to measure the
output voltage and adjust the length of the pulses to maintain the output voltage
to a desired (nominal) level. In order to provide a steady voltage across the power
system load, the output voltage of the regulator may be compared to a steady "reference"
signal, and the conduction time of the switch adjusted to produce an output equal
to the reference. A steady smooth sinusoidal waveform of the same frequency as the
power line may be used as a reference. Such a waveform may be generated by a sine
wave oscillator, or generated digitally by use of a sine table memory circuit coupled
with a digital-to-analog converter. It will be clear that in the former case the oscillator
may need to be phase locked to the power line to ensure that the comparison is made
correctly, and in the latter case the lookup should be made synchronously with the
power line perhaps through phase locking of the clock circuits to the power line.
Thus, where in a dc circuit, the desired reference signal would be a simple dc level,
in this application the reference to which the output should be compared would be
a standard sinusoidal signal, likely phase locked to the input sinusoid.
[0037] These circuits may be used not only for output voltage regulation or simple adjustment,
but also as a form of power factor regulation for non-linear loads. If a load is non
linear, when a sinusoid of voltage is impressed upon it, the current will not be sinusoidal.
The power, therefore, as the product of voltage and current is also non-sinusoidal,
and therefore contains harmonic content. The resulting high frequency current components
of the power can cause difficulties in the power distribution system. By modifying
the control circuitry it is possible to create an output voltage with a waveform which
is not a sinusoid, just so that the input current is kept sinusoidal, eliminating
the harmonic currents. This is a type of power factor correction, for which the subject
invention is well suited.
[0038] For the simulator circuit, a different logic, also apparent to a worker skilled in
the art, would be required to reduce the output by a selectable percentage for a selectable
time with a selectable phase relative to the input sinusoid. Since it may be assumed
that the input voltage would be steady during the test, no feedback is required in
this case, and the pulse width need only be adjusted by an amount required to provide
the percentage change desired, with the timing and length of the adjustment providing
the phase and length of the simulated "dip".
[0039] It should be noted that, while the above discussion assumes that the frequency of
the switching is held constant and the time of transition from one switch being closed
to the other being closed varied, it would be equally valid to hold the time of transition
constant and to vary the frequency, because either method would vary the duty cycle
η of the switch.
[0040] It should also be noted that, while Figures 5 and 6 show the switch to be formed
by an Insulated Gate Bipolar Transistor (IGBT) enclosed within a diode bridge, it
is also possible to form series and parallel combinations with IGBT elements or Field
Effect Transistors as shown in Figures 8a and 8b, and these possibilities and others
as heretofore mentioned may be employed and even mixed in a single embodiment without
departing from the essence of the invention. As those skilled in the art should easily
understand, in the parallel arrangement the Field Effect Transistors
15 may be configured with diodes
16 to achieve the desired effect. These arrangements may even be more efficient. As
one can easily understand, the diode bridge shown in Figures 5 and 6 has the advantage
of requiring but a single switching element, with the diodes providing the alternating
current capability. The diodes do, however, drop a certain small voltage. This voltage,
multiplied by the load current, may represent a loss which is converted into heat
in the diodes, and may need to be cooled as a result. As one can understand, the configurations
in Figures 8a and 8b, while utilizing two switches, may present a smaller voltage
drop than the diode bridge arrangement of Figures 5 and 6, and so may represent a
smaller loss. That is, use of the switch elements of Figures 8a and 8b may generally
result in a more efficient power regulator than possible using the diode bridge, although
at a cost of additional switches and switch drive circuitry.
[0041] Figures 9a and 9b show two embodiments of a three-phase version of the ac regulator.
In these embodiments each phase may be regulated independently, or control circuits
may be employed which couple the actions of the three regulators 16. Figure 9a shows
one arrangement in which the multiple phase supply (three phases are shown) is transformed
by a y-delta transformer 18. The resulting signals are then regulated by conceptually
separate regulators 16 as discussed earlier. As shown in Figure 9b a similar arrangement
is accomplished for a delta-y transformer 17.
[0042] The discussion included in this application is intended to serve as a basic description.
The reader should be aware that the specific discussion may not explicitly describe
all embodiments possible; many alternatives are implicit. It also may not fully explain
the generic nature of the invention and may not explicitly show how each feature or
element can actually be representative of a broader function or of a great variety
of alternative or equivalent elements. Again, these are implicitly included in this
disclosure. Where the invention is described in device-oriented terminology, each
element of the device implicitly performs a function. Additional apparatus claims
may not only be included for the device described, but also additional method or process
claims may be included to address the functions the invention and each element performs.
Neither the description nor the terminology is intended to limit the scope of the
claims which are supportable by this patent application.
[0043] It should also be understood that a variety of changes may be made without departing
from the essence of the invention. Such changes are also implicitly included in the
description. They still fall within the scope of this invention. A broad disclosure
encompassing both the explicit embodiment(s) shown, the great variety of implicit
alternative embodiments, and the broad methods or processes and the like are encompassed
by this disclosure and.may be relied upon when drafting any additional claims for
the patent. It should be understood that such language changes and broad claiming
may be accomplished at any time during pendency of this application (or any continuations
or divisional of it). Claims designed to cover numerous aspects of the invention both
independently and as an overall system are to be understood as supported by this disclosure.
[0044] In addition, each of the various elements of the invention and claims may also be
achieved in a variety of manners. This disclosure should be understood to encompass
each such variation, be it a variation of an embodiment of any apparatus embodiment,
a method or process embodiment, or even merely a variation of any element of these.
Particularly, it should be understood that as the disclosure relates to elements of
the invention, the words for each element may be expressed by equivalent apparatus
terms or method terms -- even if only the function or result is the same. Such equivalent,
broader, or even more generic terms should be considered to be encompassed in the
description of each element or action. Such terms can be substituted where desired
to make explicit the implicitly broad coverage to which this invention is entitled.
As but one example, it should be understood that all actions may be expressed as a
means for taking that action or as an element which causes that action. Similarly,
each physical element disclosed should be understood to encompass a disclosure of
the action which that physical element facilitates. Regarding this last aspect, the
disclosure of a "switch" should be understood to encompass disclosure of the act of
"switching" -- whether explicitly discussed or not -- and, conversely, were there
only disclosure of the act of "switching", such a disclosure should be understood
to encompass disclosure of a "switch." Such changes and alternative terms are to be
understood to be explicitly included in the description.
[0045] The foregoing discussion and the claims which follow describe the preferred embodiments
of the invention. Particularly with respect to the claims it should be understood
that changes may be made without departing from their essence. In this regard it is
intended that such changes would still fall within the scope of the present invention.
It is simply not practical to describe and claim all possible revisions which may
be accomplished to the present invention. To the extent such revisions utilize the
essence of the invention each would naturally fall within the breadth of protection
accomplished by this patent. This is particularly true for the present invention since
its basic concepts and understandings are fundamental in nature and can be applied
in a variety of ways to a variety of fields.
[0046] All these disclosed aspects may be claimed -- now or at a later stage of the application
-- either separately or in various permutations or combinations. Further, to the extent
the methods claimed in the present invention are not further discussed, they should
be understood as natural outgrowths of the system or apparatus claimed. Therefore,
separate and further discussion of the methods is unnecessary as they otherwise claim
steps that are implicit in the use and application of the system or the apparatus
claims. Furthermore, while many steps are organized in one logical fashion, other
sequences may occur. Therefore, the method claims should not be construed to include
only the order of sequence and steps presented. As to the claims' use of the term
"comprise" or variations such as "comprises" or "comprising", unless the context otherwise
requires, these terms are intended to imply the inclusion of a stated element or step
or group of elements or steps but not the exclusion of any other element or step or
group of elements or steps. Such terms should be interpreted in their most expansive
form so as to afford the applicant the broadest coverage legally permissible in countries
such as Australia and the like.
[0047] Thus, the applicant should be understood to have support to claim at least: i) a
regulator device as herein disclosed and described, ii) the related methods disclosed
and described, iii) similar, equivalent, and even implicit variations of each of these
devices and methods, iv) those alternative designs which accomplish each of the functions
shown as are disclosed and described, v) those alternative designs and methods which
accomplish each of the functions shown as are implicit to accomplish that which is
disclosed and described, vi) each feature, component, and step shown as separate and
independent inventions, and vii) the various combinations and permutations of each
of the above.
1. A method of simulation of disturbances on low frequency ac power sources across a
load comprising:
a. supplying an input power having an alternation period;
b. storing energy from said input power in an energy storage element for a time short
compared to said period;
c. discharging said energy into said load;
d. repeating (a)-(c) at a frequency substantially higher than the reciprocal of said
period; and
e. adjusting the ratio of said time to the reciprocal of said frequency to produce
a desired disturbance across said load.
2. The method of simulation of disturbances on low frequency ac power sources across
a load as described in claim 1 wherein said energy storage element comprises an inductor.
3. The method of simulation of disturbances on low frequency ac power sources across
a load as described in claim 1 or 2 wherein said frequency is in the range from 1
kHz to 1000 kHz.
4. The method of simulation of disturbances on low frequency ac power sources across
a load as described in claim 1 or 2 wherein storing energy further comprises causing
a charging semiconductor switch to conduct such that said energy storage element is
connected to a source of said input power.
5. The method of simulation of disturbances on low frequency ac power sources across
a load as described in claim 1 or 2 wherein discharging further comprises causing
a discharging semiconductor switch to conduct such that said energy storage element
is connected to said load.
6. A method of adjusting low frequency ac power factor comprising:
a. supplying an input power having an alternation period and a power factor;
b. storing energy from said input power in an energy storage element for a time short
compared to said period;
c. discharging said energy into said load;
d. repeating (a)-(c) at a frequency substantially higher than the reciprocal of said
period; and
e. adjusting the ratio of said time to the reciprocal of said frequency to bring said
power factor to a desired value.
7. A simulator of disturbances on low frequency ac power sources across a load comprising:
a. a source of input power having an alternation period;
b. an energy storage element;
c. a first switch to cause said energy storage element to be connected across said
input power for a time short compared to said period;
d. a second switch connected to cause discharging of said energy into said load;
wherein said switches operate at a frequency substantially higher than the reciprocal
of said period and wherein the ratio of said time to the reciprocal of said frequency
is adjusted to produce a desired disturbance across said load.
8. The simulator of disturbances on low frequency ac power sources across a load as described
in claim 7 wherein said energy storage element comprises an inductor.
9. The simulator of disturbances on low frequency ac power sources across a load as described
in claim 7 or 8 wherein said frequency is in the range from 1 kHz to 1000 kHz.
10. The simulator of disturbances on low frequency ac power sources across a load as described
in claim 7 or 8 wherein said first and second switches each comprise semiconductor
switches.
11. A simulator of disturbances on low frequency ac power sources across a load comprising
a. a source of input power having an alternation period and a first and second lead;
b. an energy storage element connected in series with said first lead;
c. a first switch connected from said second lead to said first lead at a point after
said energy storage element;
d. a second switch connected in series with said first lead at a point after said
first switch
wherein said load is connected from said first lead to said second lead at a point
after said second switch.
12. The simulator of disturbances on low frequency ac power sources across a load as described
in claim 11 wherein said energy storage element comprises an inductor.
13. The simulator of disturbances on low frequency ac power sources across a load as described
in claim 11 wherein said first and second switches comprise semiconductor switches.
14. The simulator of disturbances on low frequency ac power sources across a load as described
in claim 13 wherein said first and second semiconductor switches each comprise a diode
bridge connected across a semiconductor switch element such that current always flows
in said element in the same direction, while permitting current flow in said switch
in alternating directions.
15. The simulator of disturbances on low frequency ac power sources across a load as described
in claim 13 wherein said first and second semiconductor switches each comprise a pair
of Field Effect Transistors connected in series.
16. The simulator of disturbances on low frequency ac power sources across a load as described
in claim 13 wherein said first and second semiconductor switches each comprise a pair
of the series combination of a diode and a Field Effect Transistor, said pair connected
in parallel.
17. A simulator of disturbances on low frequency ac power sources across a load comprising:
a. a source of input power having an alternation period and having a first and second
lead;
b. an first switch connected in series with said first lead;
c. a second switch connected from said second lead to said first lead at a point after
said first switch;
d. an energy storage element connected in series with said first lead at a point after
said first switch
wherein said load is connected from said first lead to said second lead at a point
after said energy storage element.
18. The simulator of disturbances on low frequency ac power sources across a load as described
in claim 17 wherein said energy storage element comprises an inductor.
19. The simulator of disturbances on low frequency ac power sources across a load as described
in claim 17 wherein said first and second switches comprise semiconductor switches.
20. The simulator of disturbances on low frequency ac power sources across a load as described
in claim 19 wherein said first and second semiconductor switches each comprise a diode
bridge connected across a semiconductor switch element such that current always flows
in said element in the same direction, while permitting current flow in said switch
in alternating directions.