WO2004111742A1 - A circuit for detecting electric current - Google Patents

A circuit for detecting electric current Download PDF

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Publication number
WO2004111742A1
WO2004111742A1 PCT/KR2004/001426 KR2004001426W WO2004111742A1 WO 2004111742 A1 WO2004111742 A1 WO 2004111742A1 KR 2004001426 W KR2004001426 W KR 2004001426W WO 2004111742 A1 WO2004111742 A1 WO 2004111742A1
Authority
WO
WIPO (PCT)
Prior art keywords
diode
current
anode
capacitor
circuit
Prior art date
Application number
PCT/KR2004/001426
Other languages
French (fr)
Inventor
Yong Jai Kwon
Original Assignee
Yong Jai Kwon
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Yong Jai Kwon filed Critical Yong Jai Kwon
Priority to US10/561,172 priority Critical patent/US7312612B2/en
Priority to JP2006516927A priority patent/JP4249225B2/en
Priority to EP04773931A priority patent/EP1639419B1/en
Publication of WO2004111742A1 publication Critical patent/WO2004111742A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/04—Measuring peak values or amplitude or envelope of ac or of pulses
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/145—Indicating the presence of current or voltage
    • G01R19/15—Indicating the presence of current
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10—Regulating voltage or current
    • G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
    • G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
    • G05F1/565—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor
    • G05F1/567—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor for temperature compensation
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/04—Sources of current

Definitions

  • the present invention relates to a circuit for detecting an electric current and,
  • CT current transformer
  • a resistor (Rl) disposed for establishing an output
  • CT transformer
  • FIG. 2(a) An ideal forward current (A) flowing in a diode can be explained by FIG. 2(a).
  • the present invention is disclosed to solve the aforementioned drawback and it is an object of the present invention to provide a circuit for detecting an electric
  • detecting an electric current is constructed to detect a peak value of an input current
  • diode having a cathode connected to an input side and an anode connected to
  • circuit further comprises a zener diode
  • detecting a current is constructed to detect a peak value of an input current using a
  • diode having a cathode connected to an input side and an anode connected to an output
  • circuit further comprises a shunt resistor having one
  • detecting a current is constructed to detect a peak value of an input current using a
  • diode having a cathode connected to an input side and an anode connected to an output
  • circuit further comprises a zener diode having an
  • resistor having one end connected to the anode of the diode and the other end being
  • FIG. 1 is a schematic drawing for illustrating a current detecting circuit
  • FIG. 2 (a) is a schematic drawing for illustrating an ideal forward current value
  • FIG. 2 (b) is a schematic drawing for illustrating a backward leakage current
  • FIG. 3 is a schematic drawing for illustrating a current detecting circuit
  • FIG. 4 (a) is a schematic drawing for illustrating an ideal forward current value
  • FIG. 4 (b) is a schematic drawing for illustrating a backward leakage current
  • FIG. 4 (c) is a schematic drawing for illustrating a state of the backward
  • FIG. 5 is a schematic drawing for illustrating a current detecting circuit
  • FIG. 6 (a) is a schematic drawing for illustrating an ideal forward current value
  • FIG. 6 (b) is a schematic drawing for illustrating a backward leakage current
  • FIG. 6 (c) is a schematic drawing for illustrating a state of the backward
  • FIG. 7 is a schematic drawing for illustrating a current detecting circuit
  • FIG. 8 (a) is a schematic drawing for illustrating an ideal forward current value
  • FIG. 8 (b) is a schematic drawing for illustrating a backward leakage current
  • FIG. 8 (c) is a schematic drawing for illustrating the state of the forward
  • FIG. 3 is a schematic drawing for illustrating a current detecting circuit
  • CT current transformer
  • Rl resistor
  • Dl diode
  • the current transformer receives a load current and transforms same to a
  • the resistor (Rl) is
  • a cathode of the diode (Dl) is connected to one end (3) of the secondary
  • capacitor (Cl) is connected to an anode of the diode (Dl) and the other end of the
  • the non-inversion terminal of the operational amplifier (OA) is connected to
  • operational amplifier (OA) are connected to each other.
  • the anode of the zener diode (ZDl) is connected to the anode of the diode
  • the current transformer (CT) receives the load current of alternating current
  • CT current transformer
  • OA is inputted to a control apparatus (such as a micro computer for controlling a
  • FIG. 5 illustrates a current detecting circuit according to the second
  • CT computed resistor
  • Rl resistor
  • Dl diode
  • Cl capacitor
  • OA operational amplifier
  • the current transformer receives a load current, transforms same to a
  • the resistor (Rl) is
  • a cathode of the diode (Dl) is connected to one end (3) of the secondary
  • the non-inversion terminal of the operational amplifier (OA) is connected to
  • One end of the shunt resistor (R2) is connected to the anode of the diode (Dl),
  • the current transformer (CT) receives the load current of alternating current
  • CT is half-wave rectified by the diode (Dl) and smoothened by the
  • CT is detected by the diode (Dl) and the capacitor (Cl).
  • OA is inputted to a control apparatus (such as a micro computer for controlling the
  • FIG. 7 illustrates a current detecting circuit according to the third embodiment
  • the current transformer receives a load current and transforms same to a
  • the resistor (Rl) is
  • a cathode of the diode (Dl) is connected to one end (3) of the secondary
  • An anode of the zener diode (ZDl) is connected to the anode of the diode (Dl),
  • the current transformer (CT) receives the load current of alternating current
  • CT is half-wave rectified by the diode (Dl) and smoothened by the
  • CT is detected by the diode (Dl) and the capacitor (Cl).
  • the peak current value detected by the diode (Dl) and the capacitor (Cl) is buffered by the operational amplifier (OA), delayed momentarily and is then outputted.
  • OA is inputted to a control apparatus (such as a micro computer for controlling the
  • resistor (R2) to further decrease the loss portion in relation to the backward leakage
  • detected load current can be minimized.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Automation & Control Theory (AREA)
  • Power Engineering (AREA)
  • Measurement Of Current Or Voltage (AREA)
  • Induction Heating Cooking Devices (AREA)
  • General Induction Heating (AREA)
  • Power Conversion In General (AREA)

Abstract

A circuit for detecting an electric current by which a loss portion of a forward current caused by a backward leakage current of a diode generated by the influence of temperature increase can be compensated such that error in the peak value of a load current detected by surrounding high temperature can be minimized, and credibility can be increased for electric instruments that call for an accurate control of the load current and that generate a high temperature such as induction heating cookers, induction heaters and the like.

Description

A CIRCUIT FOR DETECTING ELECTRIC CURRENT
FIELD OF THE INVENTION
The present invention relates to a circuit for detecting an electric current and,
more particularly, to a circuit for detecting an electric current adapted to compensate a
leakage current of a diode sensitive to temperature changes to improve accuracy and
minimize errors.
BACKGROUND OF THE INVENTION
As is well known, an increasingly accepted trend of late for electric and
electronic gadgets is a requirement for a more accurate load current control in
controlling operations thereof. In order to discriminate whether a load current is
accurately outputted in relation to a target value, it is necessary to be equipped with a
current detecting circuit where the load current is fed back for detection by way of a
closed loop method.
As illustrated in FIG. 1, a current detecting circuit according to the prior art
includes a current transformer (CT) for receiving a load current to transform same to a
small current of easy measurement, a resistor (Rl) disposed for establishing an output
voltage level of the secondary winding side of the current transformer (CT) as a
designed value, a diode (Dl) and a capacitor (Cl) for half-wave rectifying and smoothening the alternating current output of the secondary winding side of the current
transformer (CT) to thereby detect a peak value of a measured current, and an
operational amplifier (OA) for buffering the output in relation to the peak value of the
measured current detected by the diode (Dl) and the capacitor (Cl).
Current detection circuits adopted in cookers such as induction heating
cookers and the like for heating food contained in cooking containers by flowing
current on coils for generation of heat are easily exposed to high heat, whereby the
entire temperature of the circuits is increased. An element most sensitive to
temperature in the current detection circuits is a diode, and it is a well-known fact that
a backward leakage current is increased in the diode as the temperature therein rises.
An ideal forward current (A) flowing in a diode can be explained by FIG. 2(a).
However, when the temperature is raised due to the influence of the surrounding
temperature, a leakage current (ΔA) flowing backward in the diode is increased to
thereby decrease the forward current (A') flowing in the diode (A'=A-ΔA).
In other words, there is a drawback in that an error can occur in the peak value
of the load current detected by the diode and the capacitor due to changes of the
forward current (A') flowing in the diode.
SUMMARY OF THE INVENTION
The present invention is disclosed to solve the aforementioned drawback and it is an object of the present invention to provide a circuit for detecting an electric
current adapted to offset a change in current detection value in relation to an increase
of backward leakage current caused by a temperature increase, thereby improving the
accuracy of the load current detection and heightening the reliability of products.
In accordance with a first embodiment of the present invention, a circuit for
detecting an electric current is constructed to detect a peak value of an input current
using a diode having a cathode connected to an input side and an anode connected to
an output side and a capacitor having one end connected to the anode of the diode and
the other end being grounded, wherein the circuit further comprises a zener diode
having an anode connected to the anode of the diode and a cathode being grounded.
In accordance with a second embodiment of the present invention, a circuit for
detecting a current is constructed to detect a peak value of an input current using a
diode having a cathode connected to an input side and an anode connected to an output
side and a capacitor having one end connected to the anode of the diode and the other
end being grounded, wherein the circuit further comprises a shunt resistor having one
end connected to the anode of the diode and the other end being grounded.
In accordance with a third embodiment of the present invention, a circuit for
detecting a current is constructed to detect a peak value of an input current using a
diode having a cathode connected to an input side and an anode connected to an output
side and a capacitor having one end connected to the anode of the diode and the other end being grounded, wherein the circuit further comprises a zener diode having an
anode connected to the anode of the diode and a cathode being grounded, and a shunt
resistor having one end connected to the anode of the diode and the other end being
grounded.
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the nature and objects of the present invention,
reference should be made to the following detailed description with the accompanying
drawings, in which:
FIG. 1 is a schematic drawing for illustrating a current detecting circuit
according to the prior art;
FIG. 2 (a) is a schematic drawing for illustrating an ideal forward current value
of a diode shown in FIG. 1;
FIG. 2 (b) is a schematic drawing for illustrating a backward leakage current
value caused due to the influence of temperature and a forward current value decreased
by the backward current value in the diode of Fig. 1;
FIG. 3 is a schematic drawing for illustrating a current detecting circuit
according to the first embodiment of the present invention;
FIG. 4 (a) is a schematic drawing for illustrating an ideal forward current value
of the diode shown in FIG. 3; FIG. 4 (b) is a schematic drawing for illustrating a backward leakage current
value caused due to the influence of temperature and a forward current value decreased
by the backward current value in the diode of Fig. 3;
FIG. 4 (c) is a schematic drawing for illustrating a state of the backward
leakage current value of the diode of FIG. 4 (b) decreased by the zener diode of FIG. 3;
FIG. 5 is a schematic drawing for illustrating a current detecting circuit
according to a second embodiment of the present invention;
FIG. 6 (a) is a schematic drawing for illustrating an ideal forward current value
of the diode of FIG. 5;
FIG. 6 (b) is a schematic drawing for illustrating a backward leakage current
value caused due to the influence of temperature and a forward current value decreased
by the backward current value in the diode of Fig. 5;
FIG. 6 (c) is a schematic drawing for illustrating a state of the backward
current value shown in FIG. 6 (c) increased by a shunt resistor of FIG. 5;
FIG. 7 is a schematic drawing for illustrating a current detecting circuit
according to a third embodiment of the present invention;
FIG. 8 (a) is a schematic drawing for illustrating an ideal forward current value
of a diode shown in FIG. 7;
FIG. 8 (b) is a schematic drawing for illustrating a backward leakage current
• value caused due to the influence of temperature and a forward current value decreased by the backward current value in the diode of Fig. 7; and
FIG. 8 (c) is a schematic drawing for illustrating the state of the forward
current value of the diode shown in FIG. 8 (b) decreased by a zener diode of FIG. 7 and
the state of the forward current value of the diode increased by the shunt resistor
shown in FIG. 7.
DETAILED DESCRIPTION OFTHE PREFERRED EMBODIMENT
The preferred embodiments of the present invention will now be described in
detail with reference to the annexed drawings, where the present embodiments are not
limiting the scope of the present invention but is given only as an illustrative purpose.
[FIRST EMBODIMENT]
FIG. 3 is a schematic drawing for illustrating a current detecting circuit
according to the first embodiment of the present invention, where the current detecting
circuit includes a current transformer (CT), a resistor (Rl), a diode (Dl), a capacitor
(Cl), an operational amplifier (OA) and a zener diode (ZDl).
The current transformer (CT) receives a load current and transforms same to a
small current that is easy for measurement and outputs same. The resistor (Rl) is
connected to both ends. (3, 4) of a secondary winding of the current transformer (CT)
in order to set up an output voltage at the secondary winding of the current transformer (CT).
A cathode of the diode (Dl) is connected to one end (3) of the secondary
winding of the current transformer (CT) and an anode of the diode (Dl) is connected
to a non-inversion terminal (7) of the operational amplifier (OA). One end of the
capacitor (Cl) is connected to an anode of the diode (Dl) and the other end of the
capacitor (Cl) is grounded.
The non-inversion terminal of the operational amplifier (OA) is connected to
the anode of the diode (Dl), an anode of the zener diode (ZDl), and one end of the
capacitor (Cl), and an inversion terminal (6) and an output terminal (5) of the
operational amplifier (OA) are connected to each other.
The anode of the zener diode (ZDl) is connected to the anode of the diode
(Dl), and the cathode of the zener diode (ZDl) is grounded.
The operational effect of the first embodiment of the present invention thus
constructed will now be described.
The current transformer (CT) receives the load current of alternating current
form at terminals (1, 2) of the first winding and transforms same to a small current of
alternating current form for easy measurement and outputs same via terminals (3, 4) at
the secondary winding.
The alternating current output to the secondary winding of the current
transformer (CT) is half-wave rectified by the diode (Dl) and smoothened by the capacitor (Cl), and a peak value of current output from the current transformer (CT) is
detected by the diode (Dl) and the capacitor (Cl).
The peak current value detected by the diode (Dl) and the capacitor (Cl) is
buffered by the operational amplifier (OA), delayed momententarily and is then
outputted.
For reference, the peak current value outputted from the operational amplifier
(OA) is inputted to a control apparatus (such as a micro computer for controlling a
current applied to coils of induction heating cookers or the like) and can be utilized as
information for enabling the control apparatus to compare a target value with an
actually-outputted load current.
When the surrounding temperature is low, a normal forward current (A)
flowing from a cathode of the diode (Dl) to an anode is a value as shown in FIG. 4 (a).
However, if the surrounding temperature of the diode (Dl) rises, a backward leakage
current (ΔA) flowing from the anode of the diode (Dl) to the cathode increases to
decrease the forward current (A') of the diode (Dl) as illustrated in FIG. 4(b) (A=A-
ΔA).
However, as illustrated in FIG. 4(c), the backward leakage current (ΔA) of the
diode (Dl) decreases as much as an offset portion (ΔAz) due to the forward current of
the zener diode (ZDl) because the forward current of the diode (Dl) is added by a
forward current flowing to the anode from the cathode of the zener diode (ZDl), such that the value thereof is reduced to "ΔAa" (ΔAa = ΔA - ΔAz).
As a result, the loss portion of the forward current of the diode (Dl) is greatly
reduced, thereby resulting in less errors in the peak value of the detected load current.
[SECOND EMBODIMENT]
FIG. 5 illustrates a current detecting circuit according to the second
embodiment of the present invention, where the circuit includes a current transformer
(CT), a resistor (Rl)3 a diode (Dl), a capacitor (Cl), an operational amplifier (OA) and
a shunt resistor (R2).
The current transformer (CT) receives a load current, transforms same to a
small current that is easy for measurement and outputs same. The resistor (Rl) is
connected to both ends (3, 4) of a secondary winding of the current transformer in
order to set up an output voltage at the secondary winding of the current transformer.
A cathode of the diode (Dl) is connected to one end (3) of the secondary
winding of the current transformer and an anode of the diode (Dl) is connected to a
non-inversion terminal (7) of the operational amplifier (OA). One end of the capacitor
(Cl) is connected to an anode of the diode (Dl) and the other end of the capacitor (Cl)
is grounded.
The non-inversion terminal of the operational amplifier (OA) is connected to
the anode of the diode (Dl), one end of the capacitor (Cl), and one end of the shunt • resistor (R2) and an inversion terminal (6) and an output terminal (5) of the operational
amplifier (OA) are connected to each other.
One end of the shunt resistor (R2) is connected to the anode of the diode (Dl),
and the other end of the shunt resistor ( R2) is grounded.
The operational effect of the second embodiment of the present invention thus
constructed will now be described.
The current transformer (CT) receives the load current of alternating current
• form at terminals (1, 2) of the first winding and transforms same to a small current of
alternating current form for easy measurement and outputs same via terminals (3, 4) at
the secondary winding.
The alternating current outputted to the secondary winding of the current
transformer (CT) is half-wave rectified by the diode (Dl) and smoothened by the
capacitor (Cl), and the peak value of the current output from the current transformer
(CT) is detected by the diode (Dl) and the capacitor (Cl).
The peak current value detected by the diode (Dl) and the capacitor (Cl) is
buffered by the operational amplifier (OA), delayed momentarily and is then outputted.
For reference, the peak current value output from the operational amplifier
(OA) is inputted to a control apparatus (such as a micro computer for controlling the
current applied to coils of induction heating cookers or the like) and can be utilized as
information for enabling the control apparatus to compare a target value with an actually-outputted load current.
When the surrounding temperature is low, a normal forward current (A)
flowing from a cathode of the diode (Dl) to an anode is a value as shown in FIG. 6 (a).
However, if the ambient temperature of the diode (Dl) rises, a backward leakage
current (ΔA) flowing from the anode of the diode (Dl) to the cathode becomes
increased to decrease the forward current (A') of the diode (Dl) as illustrated in FIG.
6(b) (A'=A-ΔA).
However, as illustrated in FIG. 6 (c), the forward current (αA) of the diode
(Dl) is further increased by the installation of the shunt resistor (R2) to offset the loss
portion caused by the backward leakage current (ΔA ) of the diode (Dl), thereby
minimizing error in the peak value of the detected load current.
Further elaboration on the operation where the forward current (αA) of the
diode (Dl) by way of the shunt resistor (R2) is provided below.
Theoretically, a route to the non-inversion terminal (7) of the operational
amplifier (OA) from the anode of the diode (Dl) is equivalent to an open circuit
without the shunt resistor (R2), such that the current actually flowing through the diode
(Dl) is relatively weak.
When the shunt resistor (R2) is connected to the anode of the diode (Dl) to be
grounded, a closed circuit formed by the anode of the diode (Dl) connected to the
ground via the shunt resistor (R2) is constructed, thereby generating a current flowing from the anode of the diode (Dl) to the ground via the shunt resistor (R2).
In other words, the sum of the current flowing via the diode (Dl) is further
enlarged by the current flowing to the ground side to increase the forward current (αA')
of the diode (Dl), by which the loss portion caused by the backward leakage current
(ΔA) of the diode (Dl) can be counterbalanced.
[THIRD EMBODIMENT]
FIG. 7 illustrates a current detecting circuit according to the third embodiment
• of the present invention, where the circuit includes a current transformer (CT), a
resistor (Rl), a diode (Dl), a capacitor (Cl), an operational amplifier (OA)3 zener
diode (ZDl) and a shunt resistor (R2).
The current transformer (CT) receives a load current and transforms same to a
small current that is easy for measurement and outputs same. The resistor (Rl) is
connected to both ends (3, 4) of a secondary winding of the current transformer in
order to set up an output voltage at the secondary winding of the current transformer.
A cathode of the diode (Dl) is connected to one end (3) of the secondary
winding of the current transformer and an anode of the diode (Dl) is connected to a
non-inversion terminal (7) of the operational amplifier (OA). One end of the capacitor
(Cl) is connected to an anode of the diode (Dl) and the other end of the capacitor (Cl)
is grounded. The non-inversion terminal of the operational amplifier (OA) is connected to
the anode of the diode (Dl), an anode of the zener diode (ZDl), one end of the
capacitor (Cl), and one end of the shunt resistor (R2), and an inversion terminal (6)
and an output terminal (5) of the operational amplifier (OA) are connected to each
other.
An anode of the zener diode (ZDl) is connected to the anode of the diode (Dl),
and a cathode of the zener diode (ZDl) is grounded while one end of the shunt resistor
(R2) is connected to the anode of the diode (Dl), and the other end of the shunt resistor
(R2) is grounded.
The operational effect of the third embodiment of the present invention thus
constructed will now be described.
The current transformer (CT) receives the load current of alternating current
form at terminals (1, 2) of the first winding and transforms same to a small current of
alternating current form for easy measurement and outputs same via terminals (3, 4) at
the secondary winding.
The alternating current outputted to the secondary winding of the current
transformer (CT) is half-wave rectified by the diode (Dl) and smoothened by the
capacitor (Cl), and a peak value of the current output from the current transformer
(CT) is detected by the diode (Dl) and the capacitor (Cl).
The peak current value detected by the diode (Dl) and the capacitor (Cl) is buffered by the operational amplifier (OA), delayed momentarily and is then outputted.
For reference, the peak current value output from the operational amplifier
(OA) is inputted to a control apparatus (such as a micro computer for controlling the
current applied to coils of induction heating cookers or the like) and can be utilized as
information for enabling the control apparatus to compare a target value with an
actually-outputted load current.
When the surrounding temperature is low, a normal forward current (A)
flowing from a cathode of the diode (Dl) to an anode is value as shown in FIG. 8 (a).
However, if the surrounding temperature of the diode (Dl) rises, a backward leakage
current (ΔA) flowing from the anode of the diode (Dl) to the cathode becomes
increased to decrease the forward current (A') of the diode (Dl) as illustrated in FIG.
8(b) (A=A-AA).
However, as illustrated in FIG. 8(c), when the forward current of the diode
(Dl) is added by the forward current flowing to the anode from the cathode of the
zener diode (ZDl), the backward leakage current (ΔA) of the diode (Dl) is decreased
by the forward current of the zener diode (ZDl) as much as an offset portion (ΔAz),
such that the value thereof is decreased to "ΔAa" (ΔA a = ΔA - ΔAz).
At the same time, as illustrated in FIG. 8(c), the forward current (αA) of the
diode (Dl) is further increased by the shunt resistor (R2) to enable to counterbalance
the loss portion caused by the backward leakage current (ΔA). In other words, the loss portion caused by the backward leakage current (ΔAa)
of the diode (Dl) is first decreased by the forward current of the zener diode (ZDl) in
relation to the backward leakage current (ΔA) of the diode (Dl)
Second, the forward current (αA!) of the diode (Dl) is increased by the shunt
resistor (R2) to further decrease the loss portion in relation to the backward leakage
current (ΔAa) of the diode (Dl). As a result, error in relation to the peak value of the
detected load current can be minimized.
An elaborate explanation about the operation where the forward current (αA')
of the diode (Dl) is increased by the shunt resistor (R2) will be described below.
Theoretically, a route to the non-inversion terminal (7) of the operational
amplifier (OA) from the anode of the diode (Dl) is equivalent to an open circuit
without the shunt resistor (R2), such that the current actually flowing through the diode
(Dl) is relatively weak.
When the shunt resistor (R2) is connected to the anode of the diode (Dl) to be
grounded, a closed circuit formed by the anode of the diode (Dl) connected to the
ground via the shunt resistor (R2) is constructed, thereby generating a current flowing
from the anode of the diode (Dl) to the ground via the shunt resistor (R2).
In other words, the sum of the current flowing via the diode (Dl) is further
enlarged by the current flowing to the ground side to increase the forward current (αA)
of the diode (Dl), by which the loss portion caused by the backward leakage current (ΔA) of the diode (Dl) can be counterbalanced.
As apparent from the foregoing, there is an advantage in the circuit for
• detecting an electric current thus described according to the embodiments of the
present invention in that the loss portion of the forward current caused by the
backward leakage current of the diode generated by the influence of temperature
increase can be compensated such that error in the peak value of load current detected
by the surrounding high temperature can be minimized.
There is another advantage in that credibility can be increased for electric
instruments that call for an accurate control of the load current and that generate a high
• temperature such as induction heating cookers, induction heaters and the like.
The foregoing description of the preferred embodiments of the present
invention has been presented for the purpose of illustration and description. It is not
intended to be exhaustive or to limit the invention to the precise form disclosed, and
modifications and variations are possible in light of the above teachings or may be
acquired from practice of the invention. It is intended that the scope of the invention be
defined by the claims appended hereto, and their equivalents.

Claims

WHAT IS CLAIMED IS:
1. A circuit for detecting an electric current constructed to detect a peak value of
an input current using a diode having a cathode connected to an input side and an
anode connected to an output side and a capacitor having one end connected to the
anode of the diode and the other end being grounded, wherein the circuit further
comprises a zener diode having an anode connected to the anode of the diode and a
cathode being grounded.
2. A circuit for detecting an electric current constructed to detect a peak value of
an input current using a diode having a cathode connected to an input side and an
anode connected to an output side and a capacitor having one end connected to the
anode of the diode and the other end being grounded, wherein the circuit further
comprises a shunt resistor having one end connected to the anode of the diode and the
other end being grounded.
3. A circuit for detecting an electric current constructed to detect a peak value of
an input current using a diode having a cathode connected to an input side and an
anode connected to an output side and a capacitor having one end connected to the
anode of the diode and the other end being grounded, wherein the circuit further comprises:
a zener diode having an anode connected to the anode of the diode and a
cathode being grounded; and
a shunt resistor having one end connected to the anode of the diode and the
other end being grounded.
PCT/KR2004/001426 2003-06-16 2004-06-15 A circuit for detecting electric current WO2004111742A1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US10/561,172 US7312612B2 (en) 2003-06-16 2004-06-15 Circuit for detecting electric current
JP2006516927A JP4249225B2 (en) 2003-06-16 2004-06-15 Current detection circuit for induction heating equipment
EP04773931A EP1639419B1 (en) 2003-06-16 2004-06-15 A circuit for detecting electric current

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KR10-2003-0038949 2003-06-16
KR20030038949 2003-06-16

Related Child Applications (1)

Application Number Title Priority Date Filing Date
US10561172 Continuation 2004-06-15

Publications (1)

Publication Number Publication Date
WO2004111742A1 true WO2004111742A1 (en) 2004-12-23

Family

ID=36696112

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Application Number Title Priority Date Filing Date
PCT/KR2004/001426 WO2004111742A1 (en) 2003-06-16 2004-06-15 A circuit for detecting electric current

Country Status (5)

Country Link
US (1) US7312612B2 (en)
EP (1) EP1639419B1 (en)
JP (1) JP4249225B2 (en)
KR (1) KR100687772B1 (en)
WO (1) WO2004111742A1 (en)

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* Cited by examiner, † Cited by third party
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS58165674A (en) * 1982-03-25 1983-09-30 Toshiba Electric Equip Corp Power source
JPS605776A (en) * 1983-06-23 1985-01-12 Hiroshi Kamiyama Dc power source circuit
JPS63117656A (en) * 1986-11-05 1988-05-21 Matsushita Electric Ind Co Ltd Control circuit for electric apparatus
KR940001193Y1 (en) * 1991-09-26 1994-03-07 주식회사 금성사 Circuit for reducing heat radiation in a constant voltage device
JPH10146050A (en) * 1996-11-07 1998-05-29 Hitachi Ltd Switching power unit and inverter device
JP2003017287A (en) * 2001-07-02 2003-01-17 Lecip Corp Power supply device for lighting cold cathode discharge lamp having ground protection function

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3414766A (en) * 1965-10-19 1968-12-03 Kenneth H. Miller Power control circuit
US4422039A (en) * 1981-04-24 1983-12-20 Brown Boveri Electric Inc. Self-powered ammeter
US4847554A (en) * 1987-03-04 1989-07-11 Sangamo Weston, Inc. Current measuring and magnetic core compensating apparatus and method
US5003230A (en) * 1989-05-26 1991-03-26 North American Philips Corporation Fluorescent lamp controllers with dimming control
ATE349879T1 (en) * 1999-11-03 2007-01-15 Nexicor Llc HANDHELD INDUCTION DEVICE

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS58165674A (en) * 1982-03-25 1983-09-30 Toshiba Electric Equip Corp Power source
JPS605776A (en) * 1983-06-23 1985-01-12 Hiroshi Kamiyama Dc power source circuit
JPS63117656A (en) * 1986-11-05 1988-05-21 Matsushita Electric Ind Co Ltd Control circuit for electric apparatus
KR940001193Y1 (en) * 1991-09-26 1994-03-07 주식회사 금성사 Circuit for reducing heat radiation in a constant voltage device
JPH10146050A (en) * 1996-11-07 1998-05-29 Hitachi Ltd Switching power unit and inverter device
JP2003017287A (en) * 2001-07-02 2003-01-17 Lecip Corp Power supply device for lighting cold cathode discharge lamp having ground protection function

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP1639419A4 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102486490A (en) * 2010-12-01 2012-06-06 寇地斯股份有限公司 Current detection system in current mode controller
CN109374961A (en) * 2018-10-31 2019-02-22 西安科技大学 A kind of current signal detecting device
CN109374961B (en) * 2018-10-31 2019-07-12 西安科技大学 A kind of current signal detecting device

Also Published As

Publication number Publication date
JP2007535656A (en) 2007-12-06
EP1639419B1 (en) 2012-08-01
KR20040111062A (en) 2004-12-31
US7312612B2 (en) 2007-12-25
EP1639419A4 (en) 2008-01-30
US20060164096A1 (en) 2006-07-27
KR100687772B1 (en) 2007-02-27
JP4249225B2 (en) 2009-04-02
EP1639419A1 (en) 2006-03-29

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