Source: http://www.allindianpatents.com/patents/197283-filter-apparatus-for-use-in-an-inverter-apparatus
Timestamp: 2018-08-17 16:35:35
Document Index: 684725879

Matched Legal Cases: ['art 124', 'art 124', 'arts 101', 'art 101', 'art 10', 'art 101', 'art 101', 'art 10', 'art 10', 'art 101', 'art 101', 'art 101', 'art 101']

Indian Patents. 197283:"FILTER APPARATUS FOR USE IN AN INVERTER APPARATUS"
"FILTER APPARATUS FOR USE IN AN INVERTER APPARATUS"
The present invention relates to a filter apparatus for use in the inverter apparatus.
An refrigerating apparatus such as an air conditioner or a refrigerator comprises a compressor and an inverter apparatus for driving the electric motor incorporated in the compressor.
The electric motor is a brush-less DC motor having three phase-windings. Electrostatic capacitance
(generally known as "stray capacitance") exists between the closed case (i.e., the earth terminal) and the phase-windings. As the switching circuit operates, switching the DC voltage output from the DC circuit, a leakage current having a frequency of several megahertz (MHz) flows from the phase-windings to the earth terminal.
To reduce the high-frequency leakage current, choke coils may be provided on the conduction lines that connect the output of the inverter apparatus to the electric motor. Alternatively, the switching frequency of the inverter apparatus may be lowered for the same purpose. If choke coils are so provided, however, it may still be difficult to reduce the high-frequency leakage current sufficiently when the switching frequency of the inverter apparatus increases. If the switching frequency of the inverter apparatus increases, it will be impossible to enhance the performance of the compressor, resulting in an inadequate refrigerating efficiency.
JP-A-9-266677 discloses a filter apparatus for use in an inverter apparatus for supplying drive power to a motor, comprising a core, coils mounted on the core and adapted to be provided on lines incorporated in the inverter apparatus. A current-detecting coil for detecting a leakage current is mounted on said core and has ends adapted to be connected to a circuit board of the inverter apparatus.
EP-A 0 661 453 further discloses an inverter circuit including a noise filter.
It is an object of the present invention to provide a filter apparatus having an improved reliability of a leakage current detection, while maintaining a good noise suppression.
According to the present invention this object is achieved by a filter apparatus for use in an inverter apparatus for supplying drive power to a motor, comprising: a core; coils mounted on said core, said coils being adapted to be provided on lines
incorporated in the inverter apparatus; a current-detecting coil for detecting a leakage current, said current-detecting coil being mounted on said core and having ends adapted to be connected to a circuit board of the inverter apparatus; and an annular holding member for spacing said current-detecting coil from said coils.
The dependent claims are related to further advantageous aspects of the invention.
Accordingly the instant invention provides for a filter apparatus for use in an inverter apparatus for supplying drive power to a motor, comprising:
coils mounted on said annular core, said coils being adapted to be provided on lines incorporated in the inverter apparatus; and
a current-detecting coil for detecting a leakage current, said current-detecting coil being mounted on said core and having ends adapted be connected to a circuit board of the inverter apparatus; and
an annular holding member set in the center space of said annular core for spacing said current-detecting coil from said coils.
The accompanying drawings, which are incorporated in an constitute a part of the specification, illustrated presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention.
FIG. 4 shows the waveform of the high-frequency leak current I1 generated in each embodiment of the
FIG. 5 shows the waveform of the canceling current I2 generated in each embodiment of the invention; FIG. 6 shows the waveform of the current I3 flowing to the earth terminal E when the current I2 cancels the high-frequency leak current I1 in each embodiment of the invention;
FIG. 12 is a front view of the filter apparatus incorporated in a third embodiment of this invention; FIG. 13 is a front view of the filter apparatus incorporated in a fourth embodiment of the present invention;
FIG. 14 is a side view of the filter apparatus
FIG. 16 is a front view of the filter apparatus incorporated in a fifth embodiment of the invention; FIG. 17 is a front view of the filter apparatus incorporated in a sixth embodiment of the present invention;
FIG. 20 is a front view of the filter apparatus incorporated in a tenth embodiment of the invention; FIG. 21 is a plan view of the base of the core stand provided in the filter apparatus shown in FIG. 20;
FIG. 23 is a front view of the filter apparatus incorporated in a twelfth embodiment of this invention;
DETAILED DESCRIPTION OF THE INVENTION The first embodiment of the invention will be described.
FIG. 1 shows the refrigeration cycle relating to the first embodiment. The refrigeration cycle comprises a compressor 101, a condenser 102, a pressure reducer 103, and an evaporator 104. The pressure reducer 103 is, for example, an expansion value or a capillary tube. The compressor 101, condenser 102, device 103 and evaporator 104 are connected by pipes, constituting a loop. The refrigeration cycle thus formed is filled with refrigerant.
As shown in FIG. 2, the compressor 101 comprises a closed case 111 made of metal. A suction pipe 112 is connected to the lower end part of the case 111. A discharge pipe 113 and a terminal 114 are connected
to the top of the case 111. The compressor 101 further comprises a motor 120 and a compressing section 130, which are contained in the closed case 111. The motor 120 is provided to drive the compressing section 130.
The motor 120 is a brush-less DC motor comprising a stator 121 and a rotor 122. Three phase-windings 123r, 123s and 123t are wound around the stator 121. The rotor 122 is comprises a number of steel discs and permanent magnets (for example, four magnets). The steel discs are piled one upon another, forming a cylinder which has an axial hole. A shaft 124 extends through the axial hole of the cylinder composed of the steel discs. The permanent magnets are embedded in the cylinder, surrounding the shaft 124.
An electric current is supplied to the phase-windings 123r, 123s and 123 sequentially and repeatedly, thus accomplishing commutation. As a result, the windings 123r, 123s and 123t generate magnetic fields, one after another. The magnetic fields interact with the magnetic fields of the permanent magnets in the rotor 122, generating a torque in the rotor 122.
The compressing section 130 has a main bearing 131, a sub-bearing 132, and a cylinder 133. The main bearing 131 and the sub-bearing 132 support the shaft 124. The cylinder 133 is clamped between the bearings 131 and 132 and loosely mounted on the shaft 124. The shaft 124 has an eccentric part 124a, which is
contained in the cylinder 133. A roller 134 is mounted on the eccentric part 124a. A compression chamber 135 is defined between the outer circumferential surface of the roller 134 and the inner circumferential surface of the cylinder 133. The compression chamber 135 communicates with an inlet port 136, which in turn communicates with the inlet pipe 112. The cylinder 133 has a discharge port (not shown), which connects the compression chamber 135 to the upper part of the closed case 111.
Lubricant oil 140 is contained in the bottom of the closed case 111. The oil 140 performs two function. First, it lubricates the mechanical components of the compression section 130. Second, it cools the
compression section 130.
The first filter apparatus 2 comprises two choke coils 3 and two capacitors 4. The first filter appara¬tus 2 prevents a high-frequency noise from propagating from the DC circuit 5a to the power supply 1.
The DC circuit 5a comprises a rectifier circuit 6, a second filter apparatus (low-pass filter) 8, and a smoothing capacitor 10. The rectifier circuit 6 has four diodes 6a connected, forming a bridge. The second filter apparatus 8 is connected to the output of the rectifier circuit 6, for removing noise. The smoothing capacitor 10 is connected to the output of the second filter apparatus 8. Thus structured, the DC circuit 5a converts the AC voltage applied from the power supply 1 to a DC voltage. The output of the DC circuit 5a is connected to the switching circuit 13, which will be described later.
The output voltage of the switching circuit 13 is applied to the phase-windings 123r, 123s and 123 of the motor 120 through conduction lines 15r, 15s and 15t, respectively. The closed case 111, which contains the motor 120, is connected to an earth terminal E for the sake of safety. The phase-windings 123r, 123s and 123t
are connected to a common point Po for star connection.
An electrostatic capacitance C (also known as "stray capacitance") exists between the closed case (i.e., the earth terminal E) and each of the phase-windings 123r, 123s and 123t. When the motor 120 is driven, a common mode voltage is generated between the earth terminal E and the common point Po of the phase-windings 123r, 123s and 123t, through the electrostatic capacitances C. A common mode current is generated from the common mode voltage and flows from the phase-windings 123r, 123s and 123t to the earth terminal E through the capacitances C. The common mode current is equivalent to a high-frequency leak current Ij_.
The current-detecting coil L3 is designed to detect the common mode current (i.e., the high-frequency leak current I1). The coil L3 is characterized in at least one of the following respects, First, it is made of wire thinner than the wires forming the coils L1 and coil L2 of the second filter apparatus 8. Second, it has less turns than the coils L1 and coil L2 of the second filter apparatus 8. The current-detecting coil 1.3 has a predetermined inductance of, for example, 100 µH or more.
The current-canceling circuit 30 comprises an amplifier circuit, two diodes 34, a capacitor 35, and two resistors 36 and 37. The amplifier circuit has an NPN transistor 32 and a PNP transistor 33 and is
designed to amplify the output voltage of the current-detecting coil L3. The amplifier circuit is driven to operate by the output voltage of the DC circuit 5a. The diodes 34 are provided for preventing a reverse electromotive force. The first diode 34 is connected between the collector and emitter of the transistor 32. The second diode 34 is connected between the collector and emitter of the transistor 33. The capacitor 35 is provided for removing a DC component and has a capacitance equal to the electrostatic capacitances C that exists between the closed case 111 and each of the phase-windings 123r, 123s and 123t. The resistors 36 and 37 are used to remove noises.
The amplifier circuit generates a current I2 having a waveform similar to that of the high-frequency leak current I2. The current I2 is output through the capacitor 35 and the resistor 36, thereby to cancel out the high-frequency leak current I1. The current-canceling circuit 30 has an output terminal 30a, which is connected to the earth terminal E.
The DC circuit 5a further has grounding capacitors 11 a and 11b for removing noises. These capacitors 11a
and 11b are connected in series between DC lines P and N which connect the second filter apparatus 8 and the switching circuit 13.
The indoor temperature sensor 21 detects the temperature Ta in the room which is to be air-conditioned by the air conditioner. The receiver 22 receives the infrared rays emitted from an operating unit 24 of remote-control type. The operating unit transmits data for setting operating conditions into the air conditioner, in the form of infrared rays. The drive control circuit 23 turns on and off the power transistors of the switching circuit 13. The circuit 23 controls the on-drive cycle and off-drive cycle of the power transistors, i.e., the circuit 23 controls the switching frequency of each power transistor. The circuit 23 also performs control (PWM control) on the on-period (on-off duty) of each power transistor.
The operating unit 24 is operated, setting a desired indoor temperature Ts. The unit 24 is further operated, thereby starting the air conditioner.
The switching circuit 13 is driven. The output of the switching circuit 13 drives the motor 120. The difference AT between the indoor temperature Ta detected by the indoor temperature sensor 21 and the desired temperature Ts set by the operating unit 24 is obtained. The switching frequency of the switching circuit 13 is controlled in accordance with the difference AT.
When the switching frequency of the circuit 13 is changed, the rotational sped of the motor 120 changes. The change in the rotational speed of the motor 120 results in a change in the performance of the compres¬sor 101. When the difference reduces to nil, the switching circuit 13 stops operating, and the motor 120 stops, interrupting the operation of the compressor 101
As the switching circuit 13 operates, a common mode voltage is generated between the earth terminal E and the common point Po of the phase-windings 12 3r, 123s and 123t, through the electrostatic capacitances C, Due to the common mode voltage, a high-frequency leak current I1 of several megahertz flows from the phase-windings 123r, 123s and 123t to the earth terminal E through the electrostatic capacitances C. The common mode current I1 has such a waveform as is shown in FIG. 4.
The high-frequency leak current I1 dielectrically flows toward the commercially available power supply 1.
The leak current may adversely influence the control of the inverter apparatus and may cause errors in other electric appliance, the breaker and the like. The leak current is made to flow into the DC circuit 5a. The current-detecting coil 1.3 detects a current which is proportional to the high-frequency leak current I1. The output voltage of the current-detecting coil L3 is amplified the transistors 32 and 33, providing a canceling current 12 having a waveform similar to that of the high-frequency leak current I1, as is illustrated in FIG. 5.
The canceling current 12 has such polarity that it tends to flow from the earth terminal E toward the current-canceling circuit 30. Due to the specific polarity and waveform of the canceling current I2, the high-frequency leak current I1 is canceled as if absorbed into the current-canceling circuit 30. Hence, the current 13 flowing to the earth terminal E comes to have such a low-level waveform as is shown in FIG. 6.
As mentioned above, the high-frequency leak current I1 is detected, the canceling current 12, is generated whose waveform is similar to that of the leak current I1 and the leak current I1 is forcibly canceled with the canceling current I2. Thus, the high-frequency leak current I1 can be reduced reliably even if the switching frequency of the switching circuit 13 is high. It follows that the switching frequency of the circuit 13 can be increased as much as desired, without adversely influencing the control of the inverter apparatus and without causing errors in other electric appliance, the breaker and the like. Furthermore, the performance of the compressor 101 can be enhanced sufficiently, enabling the air conditioner to acquire high operating efficiency.
The refrigerant filled in the refrigeration cycle may be HFC refrigerant which has a small electrically insulating property and the lubricating oil used in the compressor 101 may be ester oil (or ether oil) which has a large dielectric constant. If so, the high-frequency leak current I1 is likely to increase. Nevertheless, the inverter apparatus can reliably reduce the leak current I1 which has increased due to the use of HFC refrigerant and ester oil (or ether oil).
Once the high-frequency leak current I1 is thus reduced, it will be possible to inhibit electromagnetic interference such as the voltage appearing on the motor-shaft and on the noise terminal.
Since the current-detecting coil 1,3 is made of wire thinner than the wires forming the coils L1 and coil L2 of the second filter "apparatus 8, its use scarcely increases the manufacturing cost of the inverter apparatus. In addition, the coil L3 has less turns than the coils L1 and coil L2• This also serves to minimize the manufacturing cost of the inverter
If the current-detecting coil L3 has an inductance of less than 100 µH, the second filter apparatus 8 may fail to remove noises as much as is desired. The coil L3 can detects the high-frequency leak current I1 without impairing the noise-removing function of the second filter apparatus 8, because it has an inductance of, for example, 100 µH or more, as indicated above.
The current-canceling circuit 30 outputs the canceling current 12, through the capacitor 35 which has a capacitance equal to the electrostatic capacitance between the closed case 111 and the phase-windings 123r, 123s and 123t and which is provided for removing a DC component. Passed through the capacitor 35, the canceling current I2 has a waveform very similar to the waveform of the high-frequency leak current I1. Hence, the current 12 cancels out the high-frequency leak current I1 efficiently.
In the current-canceling circuit 30, the noise-removing resistor 36 is connected to the capacitor 35. Therefore, the circuit 30 cooperate with the second filter apparatus 8, removing noises with high efficiency.
As indicated above, the capacitors 7a and 7b are connected in series between DC lines P and N connecting the rectifier circuit 6 and the switching circuit 13 and are located on the input side of the second filter
apparatus 8. Further, as mentioned above, too, the capacitors lla and lib are connected in series between DC lines P and N and are located on the output side of the second filter apparatus 8. The capacitors la, 7b, lla and lib also help increase the efficiency of removing noises.
As shown in 7, 8 and 10, connection terminals 8a and 8b are connected to the ends of the coil L}, respectively, and are provided on the DC line P. Connection terminals 8c and 8d are connected to the ends of the coil L2, respectively, and are provided on the DC line N.
The current-detecting coil 1,3 for detecting the high-frequency leak current (an unbalanced current) I1 has one turn or more turns. Connection terminals 8e and 8f are connected to the ends of the current-detecting coil 1,3, respectively. The connection terminals 8e and 8f are also connected to the current-canceling circuit 30.
The ferrite core 9 of the second filter apparatus 8 is ring-shaped. The core 9 stand upright on the circuit board (PC board) 4Opc of the DC circuit 5a.
More precisely, the core 9 is secured to the circuit board by means of a core stand 10. As shown in FIG. 7, the core stand 10 comprises a base 10H and two holding parts 101 and 10J. The lower holding part 101 extends vertically from the base 10H. The upper holding part 10J is connected to the top of the lower holding part 101 and extends upwards therefrom. The lower holding part 101 holds the lower part of the ferrite core 9, while the upper holding part 10J holds the upper part of the ferrite core 9. The base 10H of the core stand 10 is shaped like a plate. As FIG. 9 shows, the base 10H has four U-notches lOa to 10d, which allow passage of the rod-shaped connection terminals 8a to 8d, respectively.
FIG. ll shows the inverter apparatus incorporated in an inverter apparatus 8 according to the second embodiment. This filter apparatus is characterized in three respects. First, connection terminals 8e and 8f are male-type ones. Second, the circuit board 30pc of a DC circuit has female-type connectors 30e and 3.0f. Third, the connection terminals 8e and 8f are inserted in the connectors 30e and 30f, respectively. It is therefore easy to incorporate a current-detecting coil L3 into the filter apparatus 8 and removed the coil 1,3 therefrom.
FIG. 12 shows the filter apparatus 8 provided in an inverter apparatus according to the third embodiment, As shown in FIG. 12, the apparatus 8 has connection terminals 8e and 8f of female-type. These connectors 8e and 8f are secured to the top of the holding part 10J of a core stand 10. Signal lines 39 are soldered at one end to the circuit board 30pc of a DC circuit, and at the other end to female-type connectors 30e and 30f. The connectors 30e and 30f are inserted in the connection terminals 8e and 8f.
As shown in FIG. 13 and 14, the filter apparatus 8
has rod-shaped connection terminals 8e and 8f, which are connected to the ends of the current-detecting coil L3, respectively. The base 10H of the core stand 10 has a part extending sideways and is therefore longer than its counterpart used in the second and third embodiments. The extending part of the base 10H has U-notches lOe and 10f, in which the rod-shaped connection terminals 8e and 8f are held. (The notches lOe and lOf may be replaced by through holes.)
The filter apparatus 8 of the fourth embodiment has six connection terminals in all, i.e., the terminals 8a to 8f. Having six connection terminals, the filter apparatus 8 can be easily incorporated into the inverter apparatus.
FIG. 16 illustrates the filter apparatus 8 provided in an inverter apparatus according to the
fifth embodiment. As shown in FIG. 16, an annular holding member lOx is set in the center space of an annular ferrite core 9. The holding member lOx holds a current-detecting coil 1,3, spaced from coils L1 and L2- The member lOx is a part of a core stand 10. Spaced form the coils L1 and L2 by the holding member lOx, the current-detecting coil L3 is completely insulated from the coils LI and L2. The coil L3 can therefore detects noises and a high-frequency leak current I1, with high reliability.
FIG. 17 shows the filter apparatus 8 provided in an inverter apparatus according to the sixth embodiment. As shown in FIG. 17, a Y-shaped holding member lOy is set in the center space of an annular ferrite core 9. The holding member lOy holds a current-detecting coil L3, spaced from coils L1 and L2- The member lOy is a part of a core stand 10.
Spaced form the coils LI and L2 by the holding member lOy, the current-detecting coil L3 is completely insulated from the coils LI and L2. The coil L3 can therefore detects noises and a high-frequency leak current I1, with high reliability.
According to the present invention, the means for insulating the current-detecting coil 1,3 from the coils L1 and L2 is not limited to the holding members lOx and lOy. In the inverter apparatus according to the seventh embodiment, the current-detecting coil 1.3 may be made of a wire in an insulting sheath. Instead, partitions may be provided to insulate the coil L3 from the coils L1 and L2. Alternatively, a plate having holes may be provided, guiding the current-detecting coil L3 through the holes and spacing the same away from the coils L12 and L2•
FIG. 18 shows the filter apparatus 8 provided in an inverter apparatus according to the eighth embodiment. As shown in FIG. 18, a current-detecting coil 1,3 is provided, corresponding to the lower holding part 101 of a core stand 10. The lower holding part 101 connects the base 10H of the core stand 10 to a lower part of a ferrite core 9. The part 101 also holds the ferrite core 9 upright. The base 10H has U-notches lOe and lOf in the vicinity of the lower
holding part 101. Rod-shaped connection terminals 8e and 8f are held in the U-notches lOe and lOf, respectively. A holding member 10Z in the form of an inverted Y is provided, holding the current-detecting coil 1,3 and spacing the same from the coils L1 and L2• The current-detecting coil L3 can be made shorter.
Further, the base 10H of the core stand 10 can be made
as small as is desired, though the current-detecting
coil 1,3 is secured to it.
Except for the features mentioned above, the
eighth embodiment is identical to the first embodiment
FIG. 19 shows the filter apparatus 8 provided in an inverter apparatus according to the ninth embodiment. As shown in FIG. 19, the base 10H of a core stand 10 has a part extending sideways. Transistors 32 and 33 and capacitor 35, which constitute a current-canceling circuit 30, are attached to the extending part of the base 10H. Thus, the current-canceling circuit 30 is integral with the filter apparatus 8. In other words,
the filter apparatus 8 has a current/noise-canceling section and can be handled as a single part.
FIG. 20 shows the filter apparatus 8 provided in an inverter apparatus according to the tenth embodiment. FIG. 21 is a plan view of the base 10H of the core stand 10 provided in the filter apparatus 8.
As FIGS. 20 and 21 show, the base 10H of a core stand 10 has a part extending sideways. Transistors 32 and 33 and capacitor 35, which constitute a current-canceling circuit 30, are attached to the extending part of the base 10H. Thus, the current-canceling circuit 30 is integral with the filter apparatus 8. It is therefore possible to connect the output terminal 30a of a canceling circuit 30 to a circuit board 40pc, by soldering a signal line 38 to the circuit board 40pc. Except for the features mentioned above, the tenth embodiment is identical to the first embodiment in structure.
FIG. 22 shows the filter apparatus 8 provided in an inverter apparatus according to the eleventh embodiment. As shown in FIG. 22, the output terminal 30a of a canceling circuit 30 to one end of the signal line 38. The signal line 38 has a connector 38a at the other end. The connector 38a is connected to a circuit board 4Opc. Hence, the output terminal 30a is electrically connected to the circuit board 4Opc.
FIG. 23 illustrates the filter apparatus 8 provided in an inverter apparatus according to the eleventh embodiment. As shown in FIG. 22, a signal
line 38 is connected at one end to a circuit board 40pc.
The signal line 38 has a connector 38a at the other end.
The connector 38a is connected to the output terminal
30a of a canceling circuit 30. Hence, the output
terminal 30a is electrically connected to the circuit
board 4Opc.
The thirteenth embodiment of the present
invention will be described, with reference to FIGS. 24,
FIG. 24 shows the filter apparatus 8 incorporated
in an inverter apparatus according to a thirteenth embodiment of the invention. FIG. 25 is a side view of the filter apparatus, and FIG. 26 is a plan view of the base of the core stand provided in the filter apparatus. As shown in FIGS. 24, 25 and 26, the base 10H of a core stand 10 has a part extending sideways. A chip 300 is mounted on the extending part of the base 10H. The extending part has a U-notch lOg, in which a rod-shaped output terminal 30a is inserted and held. As a result, the filter apparatus has five terminals, i.e., one output terminal 30a and four connection terminals 8a,
8b, 8c and 8d.
Except for the features mentioned above, the thirteenth embodiment, is identical to the first embodiment in structure.
In the first to thirteenth embodiments described above, the filter apparatus 8 is provided on a
single-phase line. Nonetheless, the filter apparatus 8 can operate in the same way if it is provided on a line of three or more phases.
When the metal housing 16 is mounted on the outdoor unit, it is automatically connected to the ground by the components of the outdoor unit. In other words, once the housing 16 is placed on the outdoor unit, the output terminal 30a of the current-canceling circuit 30 is automatically connected to the ground by the metal housing. Hence, the fourteen embodiment serves to facilitate the assembling of the air conditioner. Furthermore, the fourteenth embodiment achieves the same advantages as the first embodiment. The fifteenth embodiment of the present invention
will be described, with reference to FIG. 28.
FIG. 28 shows the control circuit incorporating an inverter apparatus according to the fifteenth embodiment. As shown in FIG. 28, a DC circuit 5b is connected by the filter apparatus 2 to a commercially available power supply 1. The DC circuit 5b comprises a rectifier circuit 6 and a smoothing capacitor 14. The rectifier circuit 6 (second rectifier circuit) has four diodes 6a connected, forming a bridge. The smoothing capacitor 14 is connected to the output of the rectifier circuit 6. The DC circuit 5b converts the AC voltage applied from the power supply 1 to a DC voltage that is lower than the output voltage of a DC circuit 5a. The output voltage of the DC circuit 5b is applied, as an operation voltage, to a current-¬canceling circuit 30.
Having the structural features described above, the fifteenth embodiment can operate correctly, without breaking down the transistors 32 and 33 incorporated in the current-canceling circuit 30, even if the
transistors 32 and 33 have relatively low withstand voltage. In addition, the fourteenth embodiment achieves the same advantages as the first embodiment.
1.	A filter apparatus for use in an inverter apparatus for supplying drive
power to a motor, comprising:
a annular core;
2.	The filter apparatus as claimed in claim 1, having a connector for
connecting ends of the current-detecting coil to said circuit board.
3.	The filter apparatus as claimed in claim 1, having connection terminals
being provided at the ends of the said coils and said current-detecting coil;
and a core stand for holding said connection terminals and securing said core
to said circuit board of the inverter apparatus.
4.	The filter apparatus as claimed in claim 1, having connection terminals
provided at the ends of said coils and at the ends of said current-detecting
coil; and a core stand adapted to be provided on said circuit board of said
inverter apparatus comprising:
a base having notches for receiving end holding said connection terminals;
a lower and an upper part for holding said annular core; and said annular holding member.
5.	The filter apparatus as claimed in claim 1, wherein said annular core is
ring-shaped and said annular holding member is set in the center space of
said annular core.
6.	The filter apparatus as claimed in claim 1, having
detection means for detecting through said current-detecting coil a leakage current and a noise generated in the inverter apparatus; and
canceling means for canceling the leakage current and noise detected by the detection means.
7.	The filter apparatus for use in an inverter apparatus for supplying dry
power to a motor substantially as herein described with reference to and as
3016-del-1998-abstract.pdf
3016-del-1998-claims.pdf
3016-del-1998-correspondence-others.pdf
3016-del-1998-correspondence-po.pdf
3016-del-1998-description (complete).pdf
3016-del-1998-drawings.pdf
3016-del-1998-form-1.pdf
3016-del-1998-form-19.pdf
3016-del-1998-form-2.pdf
3016-del-1998-form-4.pdf
3016-del-1998-form-6.pdf
3016-del-1998-gpa.pdf
3016-del-1998-petition-137.pdf
3016-del-1998-petition-others.pdf
3016/DEL/1998
1 HIROSHI MIYAZAKI 540, Morishima, Fuji-shi, Shizuoka-ken540, MORISHIMA, FUJI-SHI, SHIZUOKA-KEN, JAPAN.
2 JINICHI TAKUMA 344-7-105, MORISHIMA, FUJI-SHI, SHIZUOKA-KEN JAPAN.
3 HIDETOSHI KANAZAWA 1474-9, Tenma, Fuji-shi, Shizuka-ken1474-9, TENMA, FUJI-SHI, SHIZUOKA-KEN, JAPAN.
4 EIJI SATO 526-6, NAKAMARU, FUJI-SHI, SHIZUOKA-KEN, JAPAN.
5 TOSHIYUKI KAMIMURA 156, FUTOOCHO, KOHOKU-KU, YOKOHAMA-SHI, JAPAN.
1 9-283670 1997-10-16 Japan
2 9-355433 1997-12-24 Japan