TECHNICAL FIELD
[0001] The subject matter disclosed herein generally relates to an over voltage
protection circuit. More specifically, the present disclosure relates to an over voltage
protection circuit that works in combination with power factor correction circuit.
BACKGROUND
[0002] Background description includes information that may be useful in
understanding the present invention. It is not an admission that any of the information
provided herein is prior art or relevant to the presently claimed invention, or that any
publication specifically or implicitly referenced is prior art.
[0003] Supply power fed to electrical devices may contain certain abnormalities such as
fluctuations, and voltage higher than rated voltage. Over voltage may result in such abnormal
working of device, and therefore an overvoltage protection circuit is typically incorporated in
existing power supply circuits in order to provide a proper working voltage for the electronic
device.
[0004] Power factor (PF) is the ratio between actual load power and apparent load
power and is considered as a good indicator of the effect of load current on efficiency of a
power system. Power factor is simply a measure of efficiency of the power being used, and
therefore a PF of 1 would mean that 100% of input supply is being used efficiently. A PF of
0.5-0.7 therefore can be construed as inefficient use of input supply. PF can typically be
improved by using an active Power Factor Correction (PFC) circuit, which can
involveinstalling suitably sized switched capacitors that enable the power factor to approach a
value of 0.95 to 0.99.PFC circuit restores power factor to as close to unity as is economically
possible and has a purpose to minimize inefficient and costly reactive loads on the power
grid. Alternatively, implementing a PFC front-end in a product can maximize available
power that can be drawn from a standard outlet. Generally, the PFC circuit does this by
making the appliance look purely resistive; e.g. by incorporating no phase difference between
the voltage (Vac) and current (Iac) from the grid.
[0005] PFC circuits are typically designed to operate in specific input voltage
ranges.For instance, a general BLDC motor has a power factor in the range of .5 to 0.7, which
can be improved by using an active PFC circuit such that the power factor approaches a value
of 0.95 to 0.99. Such a PFC circuit can be designed to operate in specific input voltage range,
generally ranging from 85VAC to 265VAC at 50/60 Hz input.
3
[0006] Often, it may also be desired to have a constant output voltage that
isindependent of the applied AC voltage input from, say 85VAC to 265VAC input. If the
input voltage increases beyond a defined maximum voltage for which thePFC circuit is
designed, the PFC circuit stops being operational and the output can be designed to follow the
input directly, resulting in DC output voltage of rectified AC input voltage value.
[0007] Figure 1 shows a typical prior art power factor correction (PFC) circuit 100
showing the active PFC circuit as being configured between the input Vin (AC) and a load.
During operation, when the PFC circuit is functional, voltage applied on the load is constant
for the entire range of input voltage, enabling a situation wherein the output power demand
and the input power demand is constant. When PFC stops functioning, the power factor
reverts back to about 0.5-0.7 and input current increases correspondingly, typically by a
factor of 1.4-2 times.
[0008] Figure 2 depicts a graph of the input voltage Vin (AC) vs. Input current I, and a
further graph between the input voltage Vin (AC) and load power PL, wherein, in normal
course of operation, the PFC circuit is designed to operate for the Vin between V1 to V2. This
maintains a constant load power between P1 to P2 when the PFC circuit is operational.Since
thepower demand is constant as input voltage is increased, the drawn input current decreases
proportionately.On the other hand, when the PFC circuit stops working based on increase in
Vin beyond the defined maximum operating voltage V2 for which the PFC circuit has been
designed, the power factor also reverts back to about 0.5-0.7 for the exemplary BLDC motor
and input current increases correspondingly, typically by a factor of 1.4-2 times, which is
shown through a transition of input current from B to C. As the input voltage further
increases beyond the designed maximum voltage value and PFC is non- functional, the output
voltage increases, increasing the current from point ‘C’ to point ‘D’,along with increasing the
load power from P2 to P3. Input current therefore increases linearly with voltage, and power
increases proportional to square of the voltage.In summary, when the PFC stops working due
to higher input voltage for which it is designed, the only option that remains is to stop the
supply to the load as the higher voltage can damage the load. However, there may be several
electronics or load that may be kept operational for even higher input voltage, but the risk
remains.
[0009] State of the art in the field of electronics provides several voltage protection
electronics/circuits that can control input voltage to any electronics or load to provide the
safety. However, power factor of such circuits is not satisfactoryas they don’t implement a
PFC circuit.
4
[00010] There is therefore a need in the art for an over-voltage protection circuit that
works along with the PFC circuit in order to provide stability to the PFC circuit and to the
load/electronics that it is operatively coupled with.
[00011] All publications herein are incorporated by reference to the same extent as if
each individual publication or patent application were specifically and individually indicated
to be incorporated by reference. Where a definition or use of a term in an incorporated
reference is inconsistent or contrary to the definition of that term provided herein, the
definition of that term provided herein applies and the definition of that term in the reference
does not apply.
[00012] In some embodiments, the numbers expressing quantities of ingredients,
properties such as concentration, reaction conditions, and so forth, used to describe and claim
certain embodiments of the invention are to be understood as being modified in some
instances by the term “about.” Accordingly, in some embodiments, the numerical parameters
set forth in the written description and attached claims are approximations that can vary
depending upon the desired properties sought to be obtained by a particular embodiment. In
some embodiments, the numerical parameters should be construed in light of the number of
reported significant digits and by applying ordinary rounding techniques. Notwithstanding
that the numerical ranges and parameters setting forth the broad scope of some embodiments
of the invention are approximations, the numerical values set forth in the specific examples
are reported as precisely as practicable. The numerical values presented in some
embodiments of the invention may contain certain errors necessarily resulting from the
standard deviation found in their respective testing measurements.
[00013] As used in the description herein and throughout the claims that follow, the
meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates
otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and
“on” unless the context clearly dictates otherwise.
[00014] The recitation of ranges of values herein is merely intended to serve as a
shorthand method of referring individually to each separate value falling within the range.
Unless otherwise indicated herein, each individual value is incorporated into the specification
as if it were individually recited herein. All methods described herein can be performed in
any suitable order unless otherwise indicated herein or otherwise clearly contradicted by
context. The use of any and all examples, or exemplary language (e.g. “such as”) provided
with respect to certain embodiments herein is intended merely to better illuminate the
invention and does not pose a limitation on the scope of the invention otherwise claimed. No
5
language in the specification should be construed as indicating any non-claimed element
essential to the practice of the invention.
[00015] Groupings of alternative elements or embodiments of the invention disclosed
herein are not to be construed as limitations. Each group member can be referred to and
claimed individually or in any combination with other members of the group or other
elements found herein. One or more members of a group can be included in, or deleted from,
a group for reasons of convenience and/or patentability. When any such inclusion or deletion
occurs, the specification is herein deemed to contain the group as modified thus fulfilling the
written description of all Markush groups used in the appended claims.
OBJECTS OF THE INVENTION
[00016] It is another object of the present application to provide an improved over
voltage protection circuit.
[00017] It is an object of the present application to provide an improved Power Factor
Correction (PFC) circuit.
[00018] It is another object of the present application to provide PFC circuit with over
voltage protection.
[00019] It is another object of the present application to improve power factor of an
electrical machine to ensure good performance.
[00020] It is another object of the present application to implement PFC during high
voltage input power supply.
[00021] It is another object of the present application to implement overvoltage
protection to the machine by bypassing or charging of coil through a parallel circuit.
[00022] It is another object of the present application to reduce back current in the
circuit.
[00023] It is another object of the present application to reduce reactive power in the
circuit.
[00024] It is another object of the present application to reduce power consumption in
the circuit by regularizing power factor.
[00025] Various objects, features, aspects and advantages of the present invention will
become more apparent from the detailed description of the invention herein below along with
the accompanying drawing figures in which like numerals represent like components.
SUMMARY OF THE INVENTION
6
[00026] Aspects of present disclosure relate to anover voltage protection circuit for
electrical machines, including but not limited to motors such as brushless DC motors. Over
voltage protection circuit of the present application can be configured to ensure operability
and performance of motors or any other electrical machine during over voltage input supply.
In one aspect, the over voltage protection circuit is operatively coupled with a power factor
correction (PFC) circuit and can be configured to keep the electrical device/machine in
operation even for higher input voltage without causing any harm to be done to the load
and/or other operating electronics. In another aspect, the over voltage protection circuit is
configured on input voltage side and comprises an energizing coil that is cut-off to activate a
resistor when input voltage reaches a first threshold voltage, say Va. Such activation of the
resistor leads to a voltage drop thereby reducing the effective input voltage,to say Vb, and
also correspondingly reducing voltage available on the output. According to one
emboidment, the first threshold voltage Vafor input voltage can be selected based on one or
more of input voltage at which PFC becomes non-functional, and maximum output voltage
limit that can be applied to the load.
[00027] Another aspect of the present disclosure comprises a second over voltage
protection circuit configured to enable continued operation of the load from reduced input
voltage Vb to a second input threshold voltage Vc. Second over voltage protection circuit can
also include an energizing coil that is cut-off to activate a switch when input voltage reaches
the second input threshold voltage Vc.Activation of the switch of the second over voltage
protection circuit can be configured to shut the entire input from being applied to the load.
According to one embodiment, the second input threshold voltage Vc can be computed based
on maximum output voltage limit that can be applied to the load.Second over voltage
protection circuit therefore allows extension of input voltage application from first input
threshold voltage Va to second input threshold voltage Vc.
[00028] In order to further understand the techniques, means and effects of the present
disclosure, the following detailed descriptions and appended drawings are hereby referred,
such that, through which, the purposes, features and aspects of the present disclosure can be
thoroughly and concretely appreciated; however, the appended drawings are merely provided
for reference and illustration, without any intention to be used for limiting the present
disclosure.
[00029] Various objects, features, aspects and advantages of the inventive subject matter
will become more apparent from the following detailed description of preferred
7
embodiments, along with the accompanying drawing figures in which like numerals represent
like components.
BRIEF DESCRIPTION OF THE DRAWINGS
[00030] The accompanying drawings are included to provide a further understanding of
the present disclosure, and are incorporated in and constitute a part of this specification. The
drawings illustrate exemplary embodiments of the present disclosure and, together with the
description, serve to explain the principles of the present disclosure.
[00031] Figure 1 illustrates a typical prior art power factor correction (PFC) circuit
showing PFC circuit as being configured between input Vin (AC) and a load.
[00032] Figure 2 depicts a graph of the input voltage Vin (AC) vs. Input current I, and
further a graph between the input voltage Vin (AC) and load power PL
[00033] Figure 3 illustrates an exemplary schematic having an over voltage protection
circuit in accordance with a first embodiment of the present invention.
[00034] Figure 4 illustrates an exemplary schematic having two over voltage protection
circuits in accordance with a second embodiment of the present invention.
[00035] Figure 5 illustrates an exemplary schematic having two voltage analysis units in
accordance with a third embodiment of the present invention
[00036] Figure 6 illustrates an exemplary schematic having two voltage analysis units in
accordance with a fourth embodiment of the present invention
[00037] Figure 7 depicts a graph of the input voltage Vin (AC) vs. Input current I, and
further a graph between the input voltage Vin (AC) and load power PLin accordance with an
embodiment of the present disclosure.
[00038] Figure 8 is an exemplary waveform graph of Vinvs. Vout ofa circuit operation in
accordance with an exemplary embodiment of the present disclosure.
DETAILED DESCRIPTION
[00039] Unless the context requires otherwise, throughout the specification and claims
which follow, the word “comprise” and variations thereof, such as, “comprises” and
“comprising” are to be construed in an open, inclusive sense that is as “including, but not
limited to.”
[00040] Reference throughout this specification to “one embodiment” or “an
embodiment” means that a particular feature, structure or characteristic described in
connection with the embodiment is included in at least one embodiment. Thus, the
8
appearances of the phrases “in one embodiment” or “in an embodiment” in various places
throughout this specification are not necessarily all referring to the same embodiment.
Furthermore, the particular features, structures, or characteristics may be combined in any
suitable manner in one or more embodiments.
[00041] As used in this specification and the appended claims, the singular forms “a,”
“an,” and “the” include plural referents unless the content clearly dictates otherwise. It should
also be noted that the term “or” is generally employed in its sense including “and/or” unless
the content clearly dictates otherwise.
[00042] The headings and abstract of the disclosure provided herein are for convenience
only and do not interpret the scope or meaning of the embodiments.
[00043] Reference will now be made in detail to the exemplary embodiments of the
present disclosure, examples of which are illustrated in the accompanying drawings.
Wherever possible, the same reference numbers are used in the drawings and the description
to refer to the same or like parts.
[00044] The following discussion provides many example embodiments of the inventive
subject matter. Although each embodiment represents a single combination of inventive
elements, the inventive subject matter is considered to include all possible combinations of
the disclosed elements. Thus if one embodiment comprises elements A, B, and C, and a
second embodiment comprises elements B and D, then the inventive subject matter is also
considered to include other remaining combinations of A, B, C, or D, even if not explicitly
disclosed.
[00045] As mentioned above, existing power factor correction (PFC) circuits can be
configured to become non-functional sooner the input voltage becomes higher than a defined
voltage such that the PFC doesn’t support the load and simply cuts-off the power supply as
part of the basic safety measures for the load. The present disclosure provides an over-voltage
protection circuit that works in combination with the PFC circuit to keep the load operating
while the PFC is non-operational but output voltage is still available and still provide safety
at the higher input voltage.
[00046] Figure 3 illustrates an exemplary schematic 300 having an over voltage
protection circuit 302 in accordance with a first embodiment of the present invention. The
over voltage protection circuit 302 can include a switching circuit 304 and a resistive circuit
306. In an aspect, the over voltage protection circuit 302 can be configured on the input side
and be operatively positioned between the power terminal and a load 308. In another aspect,
the over voltage protection circuit 302 can be configured in series to a PFC circuit 310 that
9
provides a high power factor and safety to the load 308. According to one embodiment, the
over voltage protection circuit 302 can include a voltage detector unit (not shown in the
figure) coupled between the input port of the PFC and the source input power terminal for
outputting a setting voltage according to a voltage level of the source power terminal. In
another aspect, the resistive circuit 306 can be coupled between the source power terminal
and the input port of the PFC and can include a resistor R1 and a switch S1 in ‘normally
closed’ (NC) state, wherein the resistor R1 and the switch S1 are connected in parallel to each
other. In another aspect, the switching circuit 304 can be configured to activate the resistor
R1 and control operation of the switch S1 based on input voltage Vin, wherein the circuit 304
can include a voltage analysis unit 312 anda coil C1 such that when input voltage is above a
first defined threshold say Va, the coil C1 is energized, due to which the switchS1 (NC),
which is closed during normal course of action, is opened, enabling the input current to pass
through resistor R1. Such activation of resistor R1, also interchangeably referred to as power
resistor R1, leads to voltage drop in the resistor R1, thus, reducing the effective input voltage
from Vin to say Vin1, further enabling a corresponding reduction in voltage available on the
output.
[00047] According to one embodiment, the first threshold value Vafor input voltage can
be selected based on one or more of input voltage at which PFC becomes non-functional, and
maximum output voltage limit that can be applied to the load 308. In an implementation, the
first threshold value Va(represented as V3’ in Figure 8) for the input voltage Vincan be
decided such that it is lesser than the input voltage V3that corresponds to the maximum
output voltage VLthat can be applied to the load308. According to one implementation, the
first threshold value V3’for the input voltage can be higher than the input voltage V2, at which
the corresponding output voltage is Vpfc(Figure 8), and beyond which the output voltage
increases as if the PFC circuit 310 is non-functional (turned-off), leading to turning on of the
over voltage protection circuit 302.
[00048] Figure 4 illustrates an exemplary schematic 400 having two over voltage
protection circuits 402 and 404 in accordance with a second embodiment of the present
invention. In one aspect, the voltage protection circuit 402 comprises a first switching circuit
406 and a first resistive circuit 408, whereas the voltage protection circuit 404 comprises a
second switching circuit 410 and a second circuit 412. In one aspect of the present disclosure,
overvoltage protection circuits 402 and 404 can be connected in series with each other with
the circuits 402 and 404 being configured on input side between the power supply/terminal
and PFC circuit 414.
10
[00049] According to one implementation, over voltage protection circuit 402 can
function similar to circuit 302 of Figure 3, wherein once voltage analysis unit 416 of circuit
402 detects input voltage to be equal to a first threshold voltage V3’of Figure 8, resistor R1
leads to voltage drop in the resistor, thereby reducing effective input voltage from Vin to Vin1
and correspondinglyreducing output voltage from V01 to V02, as shown in Figure 8. Over
voltage protection circuit 404, on the other hand, enables extension of the operating input
voltage while still protecting load 418 from input voltage induced damage. Voltage analysis
unit 420 of circuit 404 can be configured to detect further rise in input voltage from V3 to
V4(represented in Figure 8) such that when the input voltage reaches a second threshold
voltage V4, which enables output voltage to be the maximum output voltage limit VLthat can
be applied to the load 418, the second circuit 412shuts the entire input voltage from being
applied to the load 418. Such an activity can help the load 418 operate under extended input
voltage value from V3 to V4 without exceeding limit of the load 418, input current, and
maximum output voltage that is applied to the load 418.
[00050] Figure 5 illustrates an exemplary schematic 500 having two voltage analysis
units 502 and 504 in accordance with a third embodiment of the present invention. In an
aspect, the voltage analysis unit 502 can be operatively coupled with Coil 1, and unit 504can
be operatively coupled with Coil 2, in order to form first and second switching circuits 506
and 508 respectively. In one aspect of the present invention, the first switching circuit 506
and second switching circuit 508 are connected in parallel to theoutput of voltage detection
unit510. The voltage detection unit 510 can be coupled between power terminal and ground,
wherein the voltage detection unit 510 can output a setting voltage Vin according to voltage
level at the power terminal. In another aspect, the first switching circuit506 and the second
switching circuit 508 can be connected in parallel, wherein voltage analysis unit 502 of the
circuit 506 can be configured to energize the Coil 1 if the input voltage Vinis higher than a
first predefined threshold (say V3’ in case of Figure 8) and voltage analysis unit 504 of the
circuit 508 can be configured to energize the Coil 2 if the input voltage Vinis higher than a
second predefined threshold (say V4 in case of Figure 8).
[00051] According to one embodiment, voltage analysis unit 502 can include a
comparator that has its +ve connected to Vin and the –ve connected to the first predefined
threshold VR1 (corresponding to V3’ of Figure 8), and further include a NOT gate connected
in series, wherein anode of the input of the NOT gate is connected to output of the
comparator and out of the NOT gate is connected to the Coil1.On similar lines, voltage
analysis unit 504 can include a comparator that has its +ve connected to Vin and the –ve
11
connected to the second predefined threshold VR2 (corresponding to V4 of Figure 8), and
further include a NOT gate connected in series, wherein anode of the input of the NOT gate is
connected to output of the comparator and out of the NOT gate is connected to the Coil2. It is
also possible to design a circuit wherein the NOT gate is either eliminated or folded into the
comparator. This change, however, does not alter the intent of this invention.
[00052] Figure 6 illustrates an exemplary schematic 600 having two voltage analysis
units 602 and 604 in accordance with a fourth embodiment of the present invention. One
should appreciate that although the representation 600 is on the lines of Figure 5, any other
construction can be used to implement the voltage analysis units 602/604 and respective
Coils 1 and 2, which are operatively coupled with corresponding resistive circuits for
enabling drop in effective input voltage. Figure 6 further illustrates exemplary placement and
arrangement of various active/passive components, arranged in the circuit. As is evident from
the architecture, an AC to DC voltage converter or rectifier 606 is used to convert 85V AC to
265V AC 50/60 Hz input AC supply into DC supply. Rectifer used in the circuit may be a
bridge rectifier or center-tap rectifier or any other suitable component.
[00053] According to one embodiment rectifier arrangement 606 can be followed by a
filter circuit 608, wherein the filter 608 can be used to remove the AC ripples/content from
DC supply, or for conditioning of the DC voltage. AC ripples are undesirable for any DC
operated electrical machine. Such filter circuits can include capacitors, which allow easy path
for AC, which blocks DC voltage, enabling pure DC voltage to appear at the load. In another
aspect, voltage analysis unit 602 includes a first comparator U1 and similarly the voltage
analysis unit 604 incldues a second comparator U2, wherein each comparator can be
connected with output of filter circuit and voltage regulator “VR”. VR1 shows output of
voltage regulator 610 for voltage analysis unit 602, while VR2 shows output of voltage
regulator 612 for voltage analysis unit 604. Voltage regulator(s) 610/612 can be configured to
maintain a constant voltage level, wherein a simple voltage regulator, in one exemplary
instance, can be makde from a resistor in series with diode/diodes. Due to logarithmic shape
of diode V-I curves, the voltage across the diode changes slightly due to changes in current
drawn or changes in the input. According to one embodiment, representation 600 of Figure 6
shows an implementation, wherein VR2 is greater than VR1.
[00054] According to one embodiment, output of each comparator U1/U2 can be
followed by an inverter, wherein the inverter can work as a switch to open or close the
current carrying path to the respective coils 1 and 2. Coils are used to regulate over voltage
12
supply through charging, wherein diodes D1 and D2 are connected in parallel with respective
coils 1 and 2 to act as snubbers and support them in regulation of over voltage in the circuit.
[00055] According to another embodiment, feedback can be provided through resistor
R7 and R14 to comparator U1 and U2 respectively, wherein output of U1 can be fed to the
base of the transistor switch Q2 through resistor R8 and output of U2 is fed to the based of
the transistor switch Q3 through R15. Collector of transistor Q1 can be connected to parallel
combinations of coil 1 and diode D1 and emitter can be connected to ground supply, and
similarly, collector of transistor Q2 can be connected to parallel combinations of coil 2 and
diode D2 and emitter can be connected to ground supply.
[00056] Figure 7 is an exemplary diagram 700illustrating circuit operation in accordance
with an embodiment of the present disclosure. Figure 7 depicts a graph of input voltage Vin
(AC) vs. Input current I, and another graph between input voltage Vin (AC) vs. Load Power
PL, wherein the PFC circuit is designed to operate for the Vin between V1 to V2, and load is
designed to operate between V1 to V4, wherein V4 is greater than V2 and represents an input
voltage at which the corresponding output voltage reaches VL(maximum output voltage limit
that can be applied to the load).As depicted, load power Pl is constant between P1 to P2 when
the PFC circuit is operational. Since power demand is constant, as input voltage is increased,
the drawn input current decreases proportionately. The PFC circuit stops working when the
Vin is greater than the maximum operating voltage V2 for which the PFC circuit has been
designed. When the input voltage is greater than V2but less than V3’(as shown in Figure 8),
the input power is directly supplied to the load, which increases the input current from B to C
and then gradually increases with voltage increase from C to D, and increases load power
from P2 to P3. In an implementation, sooner the input supply reaches the input voltage of
V3’the resistive circuit is activated in order to reduce the effective input voltage from Vin to
Vin1 and drop input currentfrom D to E, along with corresponding reduction in load power.
Under such reduction of effective input voltage, the input voltage can be continued from
V3’uptoV4, at which the second circuit cuts-off the power supply to the load.
[00057] Figure 8 is an exemplary diagram graph 800 of Vinvs. Vout of a circuit operation
in accordance with an embodiment of the present disclosure.Voutrepresents the voltage
available at the input port of the load, and Vinrepresents the voltage at the source input power
terminal. As illustrated, when the PFC circuit is in operation for input voltage between V1 to
V2, the Vout is constant at Vpfc.In one aspect, the first over voltage protection circuit of the
present disclosure works for input value between V3’to V4, wherein at first threshold input
voltage V3’, the first resistive circuit reduces the input voltage from V01 to V02. When the load
13
continues to operate from V3’ to V4, the second over voltage protection circuit is activated at
V4 (corresponding to output voltage of VL), at which point second over voltage protection
circuit, by means of its switch, cuts-off the supply to the load.
[00058] The above-mentioned descriptions represent merely the exemplary embodiment
of the present invention, without any intention to limit the scope of the present invention
thereto. Various equivalent changes, alterations or modification based on the present
invention are all consequently viewed as being embraced by the scope of the present
invention.
[00059] As used herein, and unless the context dictates otherwise, the term "coupled to"
is intended to include both direct coupling (in which two elements that are coupled to each
other contact each other) and indirect coupling (in which at least one additional element is
located between the two elements). Therefore, the terms "coupled to" and "coupled with" are
used synonymously. Within the context of this document terms "coupled to" and "coupled
with" are also used euphemistically to mean “communicatively coupled with” over a
network, where two or more devices are able to exchange data with each other over the
network, possibly via one or more intermediary device.
[00060] It should be apparent to those skilled in the art that many more modifications
besides those already described are possible without departing from the inventive concepts
herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of
the appended claims. Moreover, in interpreting both the specification and the claims, all
terms should be interpreted in the broadest possible manner consistent with the context. In
particular, the terms “comprises” and “comprising” should be interpreted as referring to
elements, components, or steps in a non-exclusive manner, indicating that the referenced
elements, components, or steps may be present, or utilized, or combined with other elements,
components, or steps that are not expressly referenced. Where the specification claims refers
to at least one of something selected from the group consisting of A, B, C …. and N, the text
should be interpreted as requiring only one element from the group, not A plus N, or B plus
N, etc.
ADVANTAGES OF THE INVENTION
[00061] The present disclosure provides an improved Power Factor Correction (PFC)
circuit.
[00062] The present disclosure provides an improved over voltage protection circuit.
14
[00063] The present disclosure provides an improved PFC in combination with over
voltage protection circuit.
[00064] The present disclosure provides improvement in power factor of electrical
machine to ensure lower transmission line voltage drop.
[00065] The present disclosure provides implementation of PFC even during high
voltage input power supply.
[00066] The present disclosure disables the proposed PFC when voltage exceeds the
operating range of PFC.
[00067] The present disclosure improves performance of the machine by regularizing
power factor (PF).
[00068] The present disclosure provides one or more techniques to maintain power
factor close to unity using PFC and over voltage protection circuits.
[00069] The present disclosure enables implementation of overvoltage protection to the
machine by not charging or charging of coil through a parallel circuit.
[00070] The present disclosure provides reduction in reactive power loss of the circuit.
15

CLAIMS
We claim:
1. An over voltage protection circuit positioned between a power terminal and a load, said
circuit comprising a switching circuit and a resistive circuit, wherein said resistive circuit
comprises a resister and a switch, and wherein said switching circuit activates said resistor
when input voltage is above a first defined threshold voltage, and wherein activation of said
resistor leads to voltage drop.
2. The circuit of claim 1, wherein said switching circuit comprises a voltage analysis unit
operatively coupled with a coil such that when input voltage is above said first defined
threshold voltage, said coil is energized to activate said resistor.
3. The circuit of claim 2, wherein said switch, in normal condition, is in a closed position, and is
in open condition when said coil is energized.
4. The circuit of claim 1, wherein said circuit is configured in series with a PFC circuit, wherein
said PFC is positioned between said circuit and said load.
5. The circuit of claim 4, wherein said first defined threshold voltage is selected based on one or
more of input voltage at which said PFC become non-functional, and maximum output
voltage limit that can be applied to said load.
6. An electronic device comprising a PFC and arranging a first overvoltage protection circuit for
providing a proper working voltage to the electronic device, the overvoltage protection circuit
comprising:
a first switching circuit comprising a voltage analysis unit and a coil, wherein
said voltage analysis unit detects input voltage and energizes said coil when input voltage is
equal to a first threshold voltage; and
a first resistive circuit comprising a switch and a resistor, wherein said switch
opens from closed position when said coil is energized, thereby activating said resistor to
reduce effective input voltage.
7. The device of claim 6, wherein said device further comprises a second overvoltage protection
circuit comprising a second first switching circuit and a second resistive circuit, wherein said
second overvoltage protection circuit is configured in parallel with said first overvoltage
protection circuit.
8. The device of claim 7, wherein said second first switching circuit comprises a second voltage
analysis unit configured to detect rise in said effective input voltage till a second threshold
input voltage, wherein said second threshold input voltage corresponds to output voltage
being equal to maximum output voltage limit that is applicable to said load, and wherein
16
sooner said second threshold input voltage is reached, said second resistive circuit leads to
shutting down of said input voltage from being applied to said load.
9. An over voltage protection circuit comprising a first switching circuit and a second switching
circuit configured in parallel, wherein said first switching circuit comprises a first voltage
analysis unit and a first coil, and said second switching circuit comprises a second voltage
analysis unit and a second coil, and wherein said first switching circuit and said second
switching circuit are configured in parallel to a voltage detection unit that outputs a setting
voltage based on voltage level at power terminal.
10. The circuit of claim 9, wherein said first voltage analysis unit enables energizing of said first
coil when input voltage is higher than a first defined threshold and said second voltage
analysis unit enables energizing of said second coil when input voltage is higher than a
second defined threshold.
11. The circuit of claim 9, wherein one or both of said first voltage analysis unit and said second
voltage analysis unit comprises a comparator and a NOT gate.
For Rajni Kant
TARUN KHURANA [IN/PA-1325]
AGENT FOR THE APPLICANT
Dated: 2nd January, 2014