JP5141228B2 - Active filter device and power conversion device - Google Patents

Description

  The present invention relates to a filter device provided in power conversion equipment, and in particular, an active filter device for reducing the amount of common mode current and EMI noise caused by switching flowing out to an AC system and power provided with an active filter device on the input side. The present invention relates to a conversion device.

  With the improvement of characteristics of power semiconductor elements, it has become possible to increase the switching frequency. A power converter represented by an uninterruptible power supply and a communication power supply is widely used a high-frequency switching method using PWM control because of demands for high-speed response, low noise, a request for downsizing a filter, and the like.

  As the switching frequency becomes higher, the high-frequency leakage current that flows to the ground via the DC link portion and the cable is increasing. This high-frequency leakage current flows into the AC system and becomes noise, which adversely affects other devices connected to the AC system and has become a social problem. For example, when a large-capacity storage battery is connected in a floating state especially in the uninterruptible power supply, a large high-frequency leakage current tends to flow from the long DC cable to the ground, and this high-frequency leakage current flows into the AC system.

  As a method for reducing the high-frequency leakage current flowing out to the AC system, for example, an active filter device described in Patent Document 1 is known. FIG. 11 is a configuration diagram of the conventional noise reduction device and power conversion device shown in FIG. The power converter includes a noise filter unit 51, a rectifying / smoothing circuit unit 52, a power conversion circuit unit 53, a leakage current detector 54, and an amplifier circuit 55.

  The noise filter unit 51 reduces the switching noise generated by the switching element of the power conversion circuit unit 53 from flowing out to the AC power source 56 side. The rectifying / smoothing circuit unit 52 includes a bridge rectifier circuit including four diodes D61 to D64 and a capacitor C64. The power conversion circuit unit 53 includes an inverter, a switching regulator, or the like, converts DC power into predetermined AC power or DC power, and supplies it to a load R60 such as a motor. Leakage current detector 54 is constituted by a zero-phase current transformer in which a main power supply line and a detection line are passed through a toroidal core, and detects a leakage current flowing through the main power supply line as a current difference. The amplifier circuit 55 amplifies the difference in current detected by the leakage current detector 54.

  According to such a configuration, the load R60 such as a motor has a ground-to-ground capacity, and the leakage current leaked from the load R60 flows to the ground line via the ground-to-ground capacity (not shown) of the load R60. . This leakage current returns to the load R60 via the AC power supply 56, the noise filter unit 51, the leakage current detector 54, and the power conversion circuit unit 53.

  The leakage current detector 54 detects a leakage current (hereinafter referred to as a common mode current) as a difference between currents flowing through the main power supply line, and the amplifier circuit 55 amplifies the difference between the currents to cancel the common mode current. Is supplied to the ground line through the low-frequency separation capacitor C65.

  However, in the power conversion device shown in FIG. 11, since the detected leakage current is small with respect to the compensation current, the difference in current flowing through the main power supply line must be amplified with a high amplification factor. The larger the capacitance between the load R60 and the ground, the larger the common mode current flowing through the capacitor C65 to the ground line.

  However, the feedback method shown in FIG. 11 has a problem that if the amplification factor of the amplifier circuit 55 is increased, oscillation is likely to occur unless the phase compensation is accurately performed, and the operation of the circuit becomes unstable.

  Therefore, as a solution to this problem, there is one shown in FIG. FIG. 12 is a configuration diagram of another example of the conventional noise reduction device and power conversion device shown in FIG. The power conversion apparatus includes a noise filter unit 101, a rectifying / smoothing circuit unit 102, a power conversion circuit unit 103, and a noise reduction circuit unit 104.

  The noise reduction circuit unit 104 includes a zero-phase current transformer 121, an amplifier circuit 122, and a constant voltage circuit 123. The zero-phase current transformer 121 sets the turns ratio of the main power source wire and the detection wire wound around the core to 1: 1, and detects the common mode current with the detection ratio of 1. The detected current is induced on the detection line of the zero-phase current transformer 121, and the amplifier circuit 122 amplifies the detected current with an amplification factor of 1. The noise reduction circuit unit 104 supplies this current as a compensation current to the ground line via the capacitor C6 in the opposite direction to the common mode current in order to cancel the common mode current.

That is, by detecting the common mode current with an amplification factor of 1 and returning the common mode current to the AC system 105 with an amplification factor of 1, the common mode current flowing out to the AC system 105 can be reduced. Further, since the amplification factor of the amplifier circuit 122 is 1, oscillation or the like does not occur. Furthermore, in this feedforward method, the amplifier circuit 122 can be downsized as compared with FIG.
JP 2003-174777 A (FIGS. 1 and 17)

  However, in the method of canceling the common mode current, the detected current is amplified with an amplification factor of 1, and a reverse current is passed through the power supply line. At this time, if there is a detection error or an amplification error, the common mode current cannot be canceled well, and the common mode current flows out to the AC power supply side.

  For this reason, a highly sensitive current detector and a fast response amplifier are required. In general, there is a trade-off relationship between the sensitivity of the current detector and the measurement range, and there is also a trade-off relationship between the response speed of the amplifier and the output capacity. For this reason, in order to make them compatible, there existed a problem that an apparatus became large.

  An object of the present invention is to provide an active filter device and a power conversion device that can reduce generated noise, are inexpensive, and can be downsized.

  In order to solve the above-mentioned problems, the invention of claim 1 provides a three-phase AC power source having one of the three power source lines as a ground phase, and a predetermined amount of AC power supplied from the three-phase AC power source. An active filter device that is provided between a power conversion device that converts AC power or DC power into a load and supplies the load and has a ground terminal in a housing, and reduces noise caused by a common mode current flowing in the power line. First power detection means for inserting the power supply line and the first detection line, detecting the common mode current with a detection ratio of gain 1 by the first detection line, and outputting a first common mode current detection signal; A first amplifying means for amplifying the first common mode current detection signal with an amplification factor of 1 and flowing between the ground phase power line and ground via a first capacitor; and the power line and second detection A line and an output of the first amplifying means; Second current detection means that is inserted, detects a difference between the common mode current and the output current of the first amplifying means by the second detection line with a detection ratio of gain 1, and outputs a second common mode current detection signal. And a second amplifying means for amplifying the second common mode current detection signal with an amplification factor of 1 and flowing between the power supply line of the ground phase and the ground through a second capacitor. .

  The invention of claim 2 converts a three-phase AC power source using one of the three power source lines as a ground phase and AC power supplied from the three-phase AC power source into predetermined AC power or DC power. An active filter device that is provided between a power conversion device that supplies a load and has a ground terminal in a housing and that reduces noise due to a common mode current flowing in the power supply line, wherein the power supply line and the first detection device A first current detection means for detecting the common mode current with a detection ratio of gain 1 / N1 (N1 ≧ 2) by the first detection line and outputting a first common mode current detection signal; A first amplifying means for amplifying the first common mode current detection signal with an amplification factor N1 and flowing the power between the ground phase power line and the ground via a first capacitor; the power line and the second detection line And the output of the first amplifying means are inserted. The second detection line detects a difference between the common mode current and the output current of the first amplifying means with a detection ratio of gain 1 / N2 (N2 ≧ 2), and outputs a second common mode current detection signal. And a second amplifying means for amplifying the second common mode current detection signal with an amplification factor N2 and flowing between the ground phase power line and the ground via a second capacitor. It is characterized by having.

  According to a third aspect of the present invention, a three-phase AC power source having one of the three power source lines as a ground phase and AC power supplied from the three-phase AC power source are converted into predetermined AC power or DC power. An active filter device that is provided between a power conversion device that supplies a load and has a ground terminal in a housing and that reduces noise due to a common mode current flowing in the power supply line, wherein the power supply line and the first detection device A first current detection means for detecting the common mode current with a detection ratio of gain 1 / N1 (N1 ≧ 2) by the first detection line and outputting a first common mode current detection signal; A first amplifying means for amplifying the first common mode current detection signal with an amplification factor of 1 and passing the first common mode current detection signal between the power line of the ground phase and the ground via a first capacitor; 1) have double admittance, A third capacitor for passing a current to the ground-phase power line or ground, a power line, a second detection line, and an output of the first amplifying means are inserted from a terminal having substantially the same potential as the first amplifying means. The second detection line detects a difference between the common mode current and the output current of the first amplifying means with a detection ratio of gain 1 / N2 (N2 ≧ 2), and outputs a second common mode current detection signal. A second current detecting means; a second amplifying means for amplifying the second common mode current detection signal at an amplification factor of 1 and flowing between the ground phase power line and ground through a second capacitor; And a fourth capacitor having an admittance (N2-1) times that of the second capacitor and flowing a current from a terminal having substantially the same potential as that of the second amplifying means to the power line or ground of the ground phase. And

  According to a fourth aspect of the present invention, a three-phase AC power source to which three power supply lines are connected and AC power supplied from the three-phase AC power source is converted into predetermined AC power or DC power and supplied to a load, and a housing Is an active filter device that reduces noise due to a common mode current flowing in the power line, and is obtained by dividing the three-phase AC power source with a capacitor. The power line and the first detection line are inserted, and the first detection line detects the common mode current with a detection ratio of gain 1, and outputs a first common mode current detection signal. A first current detecting means; a first amplifying means for amplifying the first common mode current detection signal with an amplification factor of 1 and flowing between the virtual neutral point and ground via a first capacitor; and the power supply Line, second detection line and said first The output of the amplifying means is inserted, and the second detection line detects the difference between the common mode current and the output current of the first amplifying means with a detection ratio of gain 1, and outputs a second common mode current detection signal. And a second amplifying unit that amplifies the second common mode current detection signal with an amplification factor of 1 and passes the signal between the virtual neutral point and the ground via a second capacitor. It is characterized by that.

  The invention according to claim 5 is a three-phase AC power source to which three power supply lines are connected, and AC power supplied from the three-phase AC power source is converted into predetermined AC power or DC power and supplied to a load, and a housing Is an active filter device that reduces noise due to a common mode current flowing in the power line, and is obtained by dividing the three-phase AC power source with a capacitor. A common potential is detected, and the first detection line detects the common mode current with a detection ratio of gain 1 / N1 (N1 ≧ 2). A first current detection means for outputting a mode current detection signal; and a first common mode current detection signal amplified by an amplification factor N1 and passed between the virtual neutral point and ground via a first capacitor. 1 amplifying means and the power line The second detection line and the output of the first amplifying means are inserted, and the difference between the common mode current and the output current of the first amplifying means is gained by a gain of 1 / N2 (N2 ≧ 2). A second current detecting means for detecting a detection ratio and outputting a second common mode current detection signal; and amplifying the second common mode current detection signal with an amplification factor N2 and passing through the second capacitor to the virtual neutral It has the 2nd amplification means to flow between a point and grounding, It is characterized by the above-mentioned.

  The invention of claim 6 converts a three-phase AC power source to which three power supply lines are connected and an AC power supplied from the three-phase AC power source into a predetermined AC power or DC power and supplies it to a load, and a housing. Is an active filter device that reduces noise due to a common mode current flowing in the power line, and is obtained by dividing the three-phase AC power source with a capacitor. A common potential is detected, and the first detection line detects the common mode current with a detection ratio of gain 1 / N1 (N1 ≧ 2). A first current detecting means for outputting a mode current detection signal; and a first common mode current detection signal amplified by an amplification factor of 1 and passed between the virtual neutral point and ground via a first capacitor. 1 amplifying means and the first controller A third capacitor having an admittance (N1-1) times that of the sensor and flowing a current from the terminal having substantially the same potential as the first amplifying means to the virtual neutral point or ground, the power supply line, and the second detection Line and the output of the first amplifying means are inserted, and the difference between the common mode current and the output current of the first amplifying means is detected by a detection ratio of gain 1 / N2 (N2 ≧ 2) by the second detection line. A second current detecting means for detecting and outputting a second common mode current detection signal; and amplifying the second common mode current detection signal at an amplification factor of 1 and grounding the virtual neutral point via a second capacitor A second amplifying means flowing between the second amplifying means and an admittance (N2-1) times that of the second capacitor, and a current from a terminal having substantially the same potential as the second amplifying means to the virtual neutral point or ground. And a fourth capacitor.

  According to a seventh aspect of the present invention, in the active filter device according to any one of the first to sixth aspects, an AC power source is closer to the three-phase AC power source than the first current detecting means and the second current detecting means. A DC power supply is provided, which receives voltage, rectifies and smoothes to generate a predetermined DC voltage, and supplies the DC voltage to the first amplifying unit and the second amplifying unit.

  According to an eighth aspect of the present invention, in the active filter device according to the seventh aspect, a negative electrode or a positive electrode of the DC power supply is connected to the power line of the ground phase or the virtual neutral point.

  The invention according to claim 9 is the power converter according to any one of claims 1 to 8, wherein the AC power supplied from the three-phase AC power source is converted into predetermined AC power or DC power and supplied to the load. The active filter device described in 1 is provided on the input side.

  According to the present invention, the first current detecting means detects the common mode current with a detection ratio of gain 1, and the first amplifying means amplifies the detected first common mode current detection signal with an amplification factor of 1, The common mode current is almost canceled by flowing between the ground phase power line and the ground via the first capacitor. The second current detection means detects a residual common mode current that could not be canceled by the first current detection means, and the second amplification means amplifies the detected second common mode current detection signal with an amplification factor of 1. The residual common mode current is canceled by flowing between the ground phase power line and the ground via the second capacitor.

  That is, the common mode current is roughly removed by the first amplifying means, and the common mode current that could not be removed by the first amplifying means is removed by using the second amplifying means. The common mode current flowing out to the AC power supply (AC system) is determined by the sensitivity of the second filter. Therefore, a high-sensitivity current detector and a high-speed response amplifier are not required for the first filter, and a current detector with a wide detection sensitivity and a large-capacity amplifier can be used. Since the second filter removes the common mode current that has passed through the first filter, a current detector with a wide detection range and a large-capacity amplifier are not required.

  Further, the detection accuracy and the detection range that are difficult to be compatible with each current detector are not required, and the large capacity and the high-speed response that are difficult to be compatible with each amplifier are not required. For this reason, the noise which generate | occur | produces can be reduced and an apparatus can be achieved at low cost and size reduction.

  Hereinafter, embodiments of an active filter device and a power conversion device of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a configuration diagram of an active filter device and a power conversion device according to the first embodiment. In FIG. 1, a three-phase AC power source 1, a power conversion device 3, a load 5, and an active filter device 7 provided between the three-phase AC power source 1 and the power conversion device 3 are provided.

  The three-phase AC power supply 1 is connected to an R-phase power supply line 1a, an S-phase power supply line 1b, and a T-phase power supply line 1c. The S-phase power supply line 1b is a ground-phase power supply line. Yes, grounded. A casing (frame) 3a of the power conversion device 3 is connected to the ground terminal E and grounded. Between the power conversion device 3 and the housing 3a, there are ground-to-ground capacities everywhere in the structure, but these are collectively put together and the ground between the negative electrode of the capacitor C0 of the power conversion device 3 and the ground terminal E This is indicated by an interspace 4.

  The R-phase, S-phase, and T-phase power lines 1a to 1c are connected to the terminals R1, S1, and T1 of the active filter device 7, respectively. The active filter device 7 includes a current transformer 10 (first current detecting means), a current transformer 20 (second current detecting means), and an amplifier 11 (first amplifying means) comprising a transistor 11a made of NPN and a transistor 11b made of PNP. ), An amplifier 21 (second amplification means) composed of a transistor 21a made of NPN and a transistor 21b made of PNP, a low frequency separation capacitor 12a (first capacitor), and a low frequency separation capacitor 22a (second capacitor), DC power supply 30 (operating power supply for amplifiers 11 and 12).

  In the current transformer 10, R-phase, S-phase, T-phase power lines 1 a to 1 c and a detection line 10 a which are main power lines are wound around the toroidal core by 1T (turn). In the current transformer 20, the R-phase, S-phase, and T-phase power lines 1a to 1c, the detection line 20a, and the output line 11e of the amplifier 11 are wound around the toroidal core by 1T (turn). Yes. The negative electrode of the DC power supply 30 is connected to the ground phase power supply line 1b.

  The collector of the transistor 11a is connected to the positive electrode of the DC power supply 30, and the base of the transistor 11a is connected to the base of the transistor 11b, one end of the detection line 10a, and one end of the low frequency separation capacitor 12a. The end is connected to the ground terminal E through the current transformer 20.

  The emitter of the transistor 11a is connected to the emitter of the transistor 11b and the other end of the detection line 10a. The collector of the transistor 11 b is connected to the negative electrode of the DC power supply 30.

  The collector of the transistor 21a is connected to the positive electrode of the DC power supply 30, and the base of the transistor 21a is connected to the base of the transistor 21b, one end of the detection line 20a, and one end of the low frequency separation capacitor 22a. The end is connected to the ground terminal E.

  The emitter of the transistor 21a is connected to the emitter of the transistor 21b and the other end of the detection line 20a. The collector of the transistor 21 b is connected to the negative electrode of the DC power supply 30.

  In addition, choke coils L1, L2, and L3 are connected in series to the power supply lines 1a, 1b, and 1c inserted through the current transformers 10 and 20, respectively. The power conversion device 3 includes choke coils L1, L2, and L3, six diodes D1 to D6, switching elements Q1 to Q6 including six IGBTs, and a capacitor C0. Both ends of the series circuit of switching element Q1 and switching element Q2, both ends of the series circuit of switching element Q3 and switching element Q4, and both ends of the series circuit of switching element Q5 and switching element Q6 are both ends of capacitor C0. And connected to both ends of the load 5.

  Corresponding diodes D1 to D6 are connected between the collectors and emitters of the switching elements Q1 to Q6, respectively. A choke coil L1 is connected to a connection point between the diode D1 and the diode D2, a choke coil L2 is connected to a connection point between the diode D3 and the diode D4, and a choke coil L3 is connected to a connection point between the diode D5 and the diode D6. Is connected. The gate terminals of the switching elements Q1 to Q6 are connected to a control circuit (not shown). The control circuit controls on / off of the switching elements Q1 to Q6, and the power conversion device 3 is supplied from the three-phase AC power source 1. It operates as a converter (AC / DC converter) that converts the supplied AC power into predetermined DC power and supplies it to the load 5.

  Note that an inverter (AC / AC converter) that converts AC power supplied from the three-phase AC power source 1 into predetermined AC power and supplies the AC power to the load 5 may be used as the power converter 3.

  FIG. 2 is a configuration diagram illustrating a modification of the amplifier provided in the active filter device according to the first embodiment. In FIG. 2, a resistor 13a is connected between the collector and base of the transistor 11a, and a resistor 13b is connected between the collector and base of the transistor 11b. A series circuit of a capacitor 14a and a capacitor 14b is connected between the base of the transistor 11a and the base of the transistor 11b. A diode 15a is connected in parallel to the capacitor 14a, and a diode 15b is connected in parallel to the capacitor 14b. The diodes 15a and 15b may be parasitic diodes of the transistors 11a and 11b.

  According to such a configuration, the capacitors 14a and 14b are charged by the resistors 13a and 13b, and the charged voltage becomes the forward voltage of the diodes 15a and 15b.

  By adding the base potential of the transistors 11a and 11b by the capacitors 14a and 14b, the dead zone of the amplifier 11 can be reduced, and the linearity of the amplifier 11 whose input is near zero can be improved. The amplifier 21 can be configured in the same manner as the modification of the amplifier 11.

  Next, the operation of the active filter device according to the first embodiment will be described with reference to FIG. The current transformer 10 detects a common mode current generated from the power converter 3, and outputs a common mode current detection signal i10a.

  The amplifier 11 amplifies the common mode current detection signal i10a detected by the 1T detection line 10a with an amplification factor of 1, and passes the obtained current i10b to the ground via the low frequency separation capacitor 12a and the current transformer 20.

  The current transformer 20 detects the difference between the common mode current generated from the power converter 3 and the current i10b, and outputs a common mode current detection signal i20a.

  The amplifier 21 amplifies the common mode current detection signal i20a detected by the 1T detection line 20a with an amplification factor of 1, and passes the obtained current i20b to the ground via the low frequency separation capacitor 22a.

  Since the currents i10b and i20b of the amplifiers 11 and 21 flow to the ground via the ground phase power line 1b, the common mode current flowing out to the three-phase AC power source 1 is derived from the common mode current generated from the power converter 3. A value obtained by subtracting the total current of the current i10b and the current i20b.

  In the first embodiment, when the common mode current generated from the power converter 3 is equal to the current i10b, the common mode current detected by the current transformer 20 becomes zero.

  However, in practice, there is a common mode current component that cannot be removed due to the detection error of the current transformer 10 and the amplification error of the amplifier 11. By detecting this current component with the current transformer 20 and removing it through the amplifier 21, the common mode current flowing out to the three-phase AC power source 1 can be greatly reduced.

  That is, the common mode current is roughly removed by the amplifier 11, and the common mode current that cannot be removed by the amplifier 11 is removed by using the amplifier 21. The common mode current flowing out to the three-phase AC power source 1 is determined by the sensitivity of the second filter. For this reason, the first filter (current transformer 10 on the power converter side, amplifier 11 and low frequency separation capacitor 12a) does not require a highly sensitive current transformer and a fast response amplifier, and has a wide detection sensitivity and a large capacity. Can be used. The second filter (current transformer 20, amplifier 21 and low frequency separation capacitor 22a on the three-phase AC power supply side) removes the common mode current that has passed through the first filter. Do not need.

  Further, it is not necessary to have a detection accuracy and a detection range that are difficult to achieve for each of the current transformers 10 and 20, and a large capacity and a high-speed response that are difficult to achieve for each of the amplifiers 11 and 21 are not required. For this reason, the noise which generate | occur | produces can be reduced and an apparatus can be achieved at low cost and size reduction.

  FIG. 3 shows an equivalent circuit diagram of the active filter device and the power conversion device according to the first embodiment. In FIG. 3, the current source CC <b> 1 through which the current i <b> 10 b flows corresponds to the amplifier 11. The current source CC2 through which the current i20b flows corresponds to the amplifier 21. The current source CC1 is connected to the current source CC2 and the ground-phase power line 1b via the current transformer 20. The current i10a and the current i10b of the current source CC1 are equal. The current i20a is equal to the current i20b of the current source CC2.

  FIG. 4 is a configuration diagram of the active filter device and the power conversion device according to the second embodiment. In the second embodiment shown in FIG. 4, the detection line 30 a is wound N1 times (N1 ≧ 2, here 10T) around the current transformer 30. The current transformer 30 detects the common mode current with the detection ratio of gain 1 / N1 by the detection line 30a, and outputs a first common mode current detection signal.

  The current source CC3 amplifies the first common mode current detection signal with an amplification factor N1 (here, 10), and connects the ground phase power line 1b and the ground via the current transformer 40 and the first capacitor (not shown). Run between.

  The current source CC3 is connected to the current source CC4 and the ground phase power line 1b via the current transformer 40. A detection line 40a is wound around the current transformer 40 N2 times (N2 ≧ 2, here 10T). The current transformer 40 detects the difference between the common mode current and the output current of the current source CC3 by the detection line 40a with a detection ratio of gain 1 / N2, and outputs a second common mode current detection signal.

  The current source CC4 amplifies the second common mode current detection signal with an amplification factor N2 (here, 10), and passes the signal between the ground phase power line 1b and the ground via a second capacitor (not shown). .

  That is, the common mode current is roughly removed by the current source CC3, and the common mode current that cannot be removed by the current source CC3 is removed by using the current source CC4. For this reason, also in Example 2, the effect similar to the effect of Example 1 is acquired.

  FIG. 5 is a configuration diagram of the active filter device and the power conversion device according to the third embodiment. Example 3 shown in FIG. 5 differs from Example 1 shown in FIG. 1 in the following points.

  A detection line 30a is wound around the current transformer 30 N1 times (here, 10T). A detection line 40a is wound N2 times (here, 10T) around the current transformer 40.

  One end of the low frequency separation capacitor 12b is connected to the connection point between the emitter of the transistor 11a and the emitter of the transistor 11b, and the other end of the low frequency separation capacitor 12b is connected to the other end of the low frequency separation capacitor 12a.

  The low frequency separation capacitor 12b has an admittance (N1-1) times that of the low frequency separation capacitor 12a (9 times here). That is, the low frequency separation capacitor 12b has a capacitance value that is nine times the capacitance of the low frequency separation capacitor 12a.

  One end of the low frequency separation capacitor 22b is connected to a connection point between the emitter of the transistor 21a and the emitter of the transistor 21b, and the other end of the low frequency separation capacitor 22b is connected to the other end of the low frequency separation capacitor 22a.

  The low frequency separation capacitor 22b has an admittance (N2-1) times that of the low frequency separation capacitor 22a (9 times here). That is, the low frequency separation capacitor 22b has a capacitance value nine times that of the low frequency separation capacitor 22a.

  According to such a configuration, when the common mode current i flows through the 1T power supply lines 1a to 1c in the current transformer 30, the current i30a = 1/10 of the common mode current i is applied to the 10T detection line 30a. i / 10 flows.

  The amplifier 11 amplifies the current i / 10 detected by the detection line 30a with an amplification factor of 1 and passes it to the ground via the low frequency separation capacitor 12a and the current transformer 40. In addition, the amplifier 11 causes a current 9i / 10, which is nine times the current i / 10 flowing in the low frequency separation capacitor 12a, to flow to the ground via the low frequency separation capacitor 12b and the current transformer 40.

  Therefore, the total current i of the current i / 10 flowing through the low frequency separation capacitor 12a and the current 9i / 10 flowing through the low frequency separation capacitor 12b flows to the ground via the current transformer 40. That is, since a current having the same value as the common mode current i flows through the ground, the common mode current flowing out to the three-phase AC power source 1 can be reduced. For this reason, the noise which generate | occur | produces can be reduced, and it can achieve low cost and size reduction. The current transformer 40 side operates in the same manner as the current transformer 30 side, and the same effect can be obtained.

  Further, in the third embodiment, the current transformers 30 and 40 can be further downsized and the current detection signal can be improved as compared with the first embodiment.

  FIG. 6 is a configuration diagram of the active filter device and the power conversion device according to the fourth embodiment. In the fourth embodiment, a DC voltage obtained by half-wave rectifying and smoothing a positive half voltage of the AC voltage of the three-phase AC power source 1 is supplied to the amplifiers 11 and 21.

  In FIG. 6, a series circuit of a diode D7, a capacitor C6, a diode D8, and a capacitor C5 is connected between the R-phase power line 1a and the ground-phase power line 1b. The connection point between the cathode of the diode D7 and the capacitor C6 is connected to the emitter of the transistor Q7, and the collector of the transistor Q7 is connected to the collectors of the transistors 11a and 21a. The base of the transistor Q7 is connected to the anode of the diode D7 via the resistor 13C.

  The cathode of the diode D9 is connected to the connection point between the capacitor C6 and the anode of the diode D8, and the anode of the diode D9 is connected to the ground-phase power line 1b and the collectors of the transistors 11b and 21b. The connection point between the cathode of the diode D8 and the capacitor C5 is connected to the collectors of the transistors 11a and 21a. A capacitor C4 is connected in parallel with the capacitor C5.

According to such a configuration, after an AC voltage is applied, when a positive voltage is applied, a current flows through a path of D7 → C6 → D8 → C5, and the capacitors C5 and C6 are charged. When the AC power supply voltage starts to decrease from the positive peak,
AC power supply voltage <(voltage across C5 + voltage across C6)
The diode D7 is reverse-biased and the transistor Q7 is turned on. In this case, a current path of C6 → Q7 → C5 → D9 is formed. The voltage across the capacitor C5 is always charged with about ½ voltage of the positive peak value of the AC power supply voltage. The voltage across the capacitor C5 can be used as a DC power source (operating power source) for the amplifiers 11 and 21.

  Although the positive half voltage of the alternating voltage is half-wave rectified in the fourth embodiment, the present invention may generate a rectified voltage having an arbitrary voltage.

  FIG. 7 is a configuration diagram of the active filter device and the power conversion device according to the fifth embodiment. The fifth embodiment shown in FIG. 7 is different from the third embodiment shown in FIG. 5 in that transistors 11c and 11d are provided corresponding to the transistors 11a and 11b, and transistors 21c and 21d are provided corresponding to the transistors 21a and 21b. Each amplifier has a two-stage configuration.

  The collector of the transistor 11a is connected to the collector of the transistor 11c, and the emitter of the transistor 11a, the emitter of the transistor 11b, the base of the transistor 11c, and the base of the transistor 11d are connected to the other end of the detection line 30a. The emitter of the transistor 11c and the emitter of the transistor 11d are connected to one end of the low frequency separation capacitor 12b, and the other end of the low frequency separation capacitor 12b is connected to the other end of the low frequency separation capacitor 12a.

  The collector of the transistor 21a is connected to the collector of the transistor 21c, and the emitter of the transistor 21a, the emitter of the transistor 21b, the base of the transistor 21c, and the base of the transistor 21d are connected to the other end of the detection line 40a. The emitter of the transistor 21c and the emitter of the transistor 21d are connected to one end of the low frequency separation capacitor 22b, and the other end of the low frequency separation capacitor 22b is connected to the other end of the low frequency separation capacitor 22a.

  According to such a configuration, since each amplifier has a two-stage configuration, a transistor having a small amplification factor hfe can be used for the transistors 11a and 11b and the transistors 21a and 21b, and the current capacity thereof can be increased. Can be small. Further, the frequency response accuracy can be improved by using a transistor having a small current capacity.

  FIG. 8 is a configuration diagram of an active filter device and a power conversion device according to the sixth embodiment. The sixth embodiment shown in FIG. 8 differs from the first embodiment shown in FIG. 1 in the following configuration.

  The power supply line 1b is not connected to the ground phase. A capacitor C1 is connected between the power supply line 1a and the collectors of the transistors 11b and 21b and the negative electrode of the DC power supply 30. A capacitor C2 is connected between the power supply line 1b and the collectors of the transistors 11b and 21b and the negative electrode of the DC power supply 30. A capacitor C3 is connected between the power supply line 1c and the collectors of the transistors 11b and 21b and the negative electrode of the DC power supply 30. The capacitance value of the capacitor C1, the capacitance value of the capacitor C2, and the capacitance value of the capacitor C3 are all the same.

  According to such a configuration, the point at which the capacitor C1, the capacitor C2, and the capacitor C3 are connected in common (the point at which the collectors of the transistors 11b and 21b and the negative electrode of the DC power supply 30 are connected) is defined as the virtual neutral point. As a result, current can flow through the virtual neutral point that is divided by the capacitors C1, C2, and C3 instead of the ground phase. For this reason, Example 6 has a great effect on the three-phase AC power source 1 that does not have a ground phase or an AC system in which the ground phase is unknown.

  FIG. 9 is a configuration diagram of the active filter device and the power conversion device according to the seventh embodiment. The seventh embodiment shown in FIG. 9 differs from the third embodiment shown in FIG. 5 in the following configuration.

  The power supply line 1b is not connected to the ground phase. A capacitor C1 is connected between the power supply line 1a and the collectors of the transistors 11b and 21b and the negative electrode of the DC power supply 30. A capacitor C2 is connected between the power supply line 1b and the collectors of the transistors 11b and 21b and the negative electrode of the DC power supply 30. A capacitor C3 is connected between the power supply line 1c and the collectors of the transistors 11b and 21b and the negative electrode of the DC power supply 30. The capacitance value of the capacitor C1, the capacitance value of the capacitor C2, and the capacitance value of the capacitor C3 are all the same.

  According to such a configuration, the point at which the capacitor C1, the capacitor C2, and the capacitor C3 are connected in common (the point at which the collectors of the transistors 11b and 21b and the negative electrode of the DC power supply 30 are connected) is defined as the virtual neutral point. As a result, current can flow through the virtual neutral point that is divided by the capacitors C1, C2, and C3 instead of the ground phase. For this reason, Example 7 has a great effect on the three-phase AC power source 1 having no ground phase or an AC system in which the ground phase is unknown.

  7 is provided with capacitors C1, C2, and C3 as shown in FIG. 9, and the capacitors C1, C2, and C3 are connected in common (transistors 11b, 11d). , 21b and 21d and the negative electrode of the DC power source 30 are connected to each other as a virtual neutral point, and a current is passed through the virtual neutral point divided by the capacitors C1, C2, and C3 instead of the ground phase. May be. In this case, the same effect as that of the seventh embodiment can be obtained.

  In addition, this invention is not limited to the active filter apparatus of the Examples 1 thru | or 7 mentioned above. In the active filter devices of the first to seventh embodiments, a low frequency separation capacitor 12a is connected between the bases of the transistors 11a and 11b and the ground phase power line 1b, and a low frequency is connected between the emitters of the transistors 11a and 11b and the ground. The separation capacitor 12b is connected. For example, a series circuit of a capacitor 12a and a resistor Ra (admittance is 1 / R) is connected between the bases of the transistors 11a and 11b and the ground, and the emitters of the transistors 11a and 11b are grounded. A series circuit of a capacitor 12b and a resistor Rb (admittance is (N1-1) / R) may be connected between the two. The transistors 21a and 21b can be configured similarly to the transistors 11a and 11b.

  Further, a DC voltage obtained by negative half voltage half-wave rectification or one-third voltage half-wave rectification may be used as an operating power source for the amplifiers 11 and 21.

  In the first to seventh embodiments, one current transformer 10 (or 30) and one current transformer 20 (or 40) are provided. For example, a plurality of current transformers 10 (or 30) and a plurality of currents are provided. A transformer 20 (or 40) may be provided. In this case, a plurality of amplifiers 11 are provided corresponding to the plurality of current transformers 10 (or 30), and a plurality of current transformers 20 (or 40) are provided. A plurality of amplifiers 21 may be provided corresponding to the above.

  Moreover, it can replace with the active filter apparatus of Example 1 shown in FIG. 1, and a modification as shown in FIG. 10 can also be used. In FIG. 10, an active filter device 7 'includes a current transformer 10' (first current detection means), a current transformer 20 '(second current detection means), a transistor 11a made of NPN, and a transistor 11b made of PNP. An amplifier 11 (first amplification means), an amplifier 21 (second amplification means) comprising a transistor 21a made of NPN and a transistor 21b made of PNP (second amplification means), a low frequency separation capacitor 12a (first capacitor), and a low frequency separation capacitor 22a (Second capacitor) and a DC power source 30 (operating power source for the amplifiers 11 and 12).

  In the current transformer 10 ′, R-phase, S-phase, T-phase power lines 1 a to 1 c and a detection line 10 ′, which are main power lines, are wound around the toroidal core by 1T (turn). In the current transformer 20 ′, the main power supply lines for the R-phase, S-phase, and T-phase power supply lines 1a to 1c, the detection line 20′a, and the output line 11e of the amplifier 11 are each wound by 1T (turn). It has been turned. The negative electrode of the DC power supply 30 is grounded.

  The detection line 10′a in FIG. 10 is opposite to the winding direction of the detection line 10a in FIG. 1, and the detection line 20′a in FIG. 10 is opposite to the winding direction of the detection line 20a in FIG.

  The collector of the transistor 11a is connected to the positive electrode of the DC power supply 30, and the base of the transistor 11a is connected to the base of the transistor 11b, one end of the detection line 10'a, and one end of the low frequency separation capacitor 12a. Is connected to the ground phase power line 1b via a current transformer 20 '.

  The emitter of the transistor 11a is connected to the emitter of the transistor 11b and the other end of the detection line 10′a. The collector of the transistor 11 b is connected to the negative electrode of the DC power supply 30 and the ground terminal E.

  The collector of the transistor 21a is connected to the positive electrode of the DC power supply 30, and the base of the transistor 21a is connected to the base of the transistor 21b, one end of the detection line 20′a, and one end of the low frequency separation capacitor 22a. Is connected to the ground phase power line 1b.

  The emitter of the transistor 21a is connected to the emitter of the transistor 21b and the other end of the detection line 20′a. The collector of the transistor 21b is connected to the negative electrode of the DC power supply 30 and the ground terminal E.

  According to the configuration of such a modification, the operation is the same as that of the first embodiment, and the same effect can be obtained.

  The present invention can be used for a power converter represented by an uninterruptible power supply and a communication power supply.

It is a block diagram of the active filter apparatus and power converter device of Example 1. FIG. 6 is a configuration diagram illustrating a modification of an amplifier provided in the active filter device according to the first embodiment. FIG. 2 is an equivalent circuit diagram of the active filter device and the power conversion device according to the first embodiment of FIG. 1. It is a block diagram of the active filter apparatus and power converter device of Example 2. It is a block diagram of the active filter apparatus and power converter device of Example 3. It is a block diagram of the active filter apparatus and power converter device of Example 4. It is a block diagram of the active filter apparatus and power converter device of Example 5. It is a block diagram of the active filter apparatus and power converter device of Example 6. It is a block diagram of the active filter apparatus and power converter device of Example 7. It is a block diagram of the active filter apparatus and power converter device of the modification of Example 1. FIG. It is a block diagram of the conventional noise reduction apparatus and power converter device. It is a block diagram of the other example of the conventional noise reduction apparatus and power converter device.

Explanation of symbols

1 Three-phase AC power supply 1a R-phase power supply line 1b S-phase power supply line 1c T-phase power supply line 3 Power converter
4 Ground-to-ground capacity 5 Loads 7, 7a to 7e, 7 'Active filter device 10, 10', 20, 20 ', 30, 40 Current transformer 10a, 10'a, 20a, 20'a, 30a, 40a Detection line 11a , 11b, 11c, 11d, 21a, 21b, 21c, 21d Transistors 12a, 22a, 12b, 22b Low frequency separation capacitors C0 to C3 Capacitors Q1 to Q6 Switching elements Q7 Transistors D1 to D9 Diodes L1 to L3 Choke coil 30 DC power supply

Claims (9)

A three-phase AC power supply having one of the three power supply lines as a ground phase, and AC power supplied from the three-phase AC power supply is converted into predetermined AC power or DC power, supplied to a load, and a housing. An active filter device provided between a power conversion device having a ground terminal in a body and reducing noise due to a common mode current flowing in the power line,
First power detection means for inserting the power supply line and the first detection line, detecting the common mode current with a detection ratio of gain 1 by the first detection line, and outputting a first common mode current detection signal;
A first amplifying means for amplifying the first common mode current detection signal with an amplification factor of 1 and flowing between the ground phase power line and ground via a first capacitor;
The power supply line, the second detection line, and the output of the first amplifying unit are inserted, and the difference between the common mode current and the output current of the first amplifying unit is detected by a detection ratio of gain 1 by the second detection line. Second current detection means for detecting and outputting a second common mode current detection signal;
A second amplifying means for amplifying the second common mode current detection signal at an amplification factor of 1 and flowing between the ground phase power line and ground via a second capacitor;
An active filter device comprising: A three-phase AC power supply having one of the three power supply lines as a ground phase, and AC power supplied from the three-phase AC power supply is converted into predetermined AC power or DC power, supplied to a load, and a housing. An active filter device provided between a power conversion device having a ground terminal in a body and reducing noise due to a common mode current flowing in the power line,
The power supply line and the first detection line are inserted, and the common mode current is detected with a detection ratio of gain 1 / N1 (N1 ≧ 2) by the first detection line, and a first common mode current detection signal is output. First current detection means;
A first amplifying means for amplifying the first common mode current detection signal with an amplification factor N1 and flowing between the ground phase power line and the ground via a first capacitor;
The power supply line, the second detection line, and the output of the first amplifying unit are inserted, and the difference between the common mode current and the output current of the first amplifying unit is gained by a gain 1 / N2 (N2) by the second detection line. Second current detection means for detecting at a detection ratio of ≧ 2) and outputting a second common mode current detection signal;
A second amplifying means for amplifying the second common mode current detection signal at an amplification factor N2 and flowing between the ground phase power line and ground via a second capacitor;
An active filter device comprising: A three-phase AC power supply having one of the three power supply lines as a ground phase, and AC power supplied from the three-phase AC power supply is converted into predetermined AC power or DC power, supplied to a load, and a housing. An active filter device provided between a power conversion device having a ground terminal in a body and reducing noise due to a common mode current flowing in the power line,
The power supply line and the first detection line are inserted, and the common mode current is detected with a detection ratio of gain 1 / N1 (N1 ≧ 2) by the first detection line, and a first common mode current detection signal is output. First current detection means;
A first amplifying means for amplifying the first common mode current detection signal with an amplification factor of 1 and flowing between the ground phase power line and ground via a first capacitor;
A third capacitor having an admittance (N1-1) times that of the first capacitor and flowing a current from a terminal having substantially the same potential as the first amplifying means to the power line or ground of the ground phase;
The power supply line, the second detection line, and the output of the first amplifying unit are inserted, and the difference between the common mode current and the output current of the first amplifying unit is gained by a gain 1 / N2 (N2) by the second detection line. Second current detection means for detecting at a detection ratio of ≧ 2) and outputting a second common mode current detection signal;
A second amplifying means for amplifying the second common mode current detection signal at an amplification factor of 1 and flowing between the ground phase power line and ground via a second capacitor;
A fourth capacitor having an admittance (N2-1) times that of the second capacitor and flowing a current from a terminal having substantially the same potential as the second amplifying means to the ground-phase power line or ground;
An active filter device comprising: Three-phase AC power source to which three power lines are connected, and AC power supplied from the three-phase AC power source is converted into predetermined AC power or DC power and supplied to the load, and power conversion having a ground terminal in the housing An active filter device provided between the device and reducing noise due to a common mode current flowing in the power line,
Having a virtual neutral point potential obtained by dividing the three-phase AC power supply with a capacitor;
First power detection means for inserting the power supply line and the first detection line, detecting the common mode current with a detection ratio of gain 1 by the first detection line, and outputting a first common mode current detection signal;
A first amplifying means for amplifying the first common mode current detection signal with an amplification factor of 1 and flowing between the virtual neutral point and ground via a first capacitor;
The power supply line, the second detection line, and the output of the first amplifying unit are inserted, and the difference between the common mode current and the output current of the first amplifying unit is detected by a detection ratio of gain 1 by the second detection line. Second current detection means for detecting and outputting a second common mode current detection signal;
A second amplifying means for amplifying the second common mode current detection signal at an amplification factor of 1 and flowing between the virtual neutral point and ground via a second capacitor;
An active filter device comprising: Three-phase AC power source to which three power lines are connected, and AC power supplied from the three-phase AC power source is converted into predetermined AC power or DC power and supplied to the load, and power conversion having a ground terminal in the housing An active filter device provided between the device and reducing noise due to a common mode current flowing in the power line,
Having a virtual neutral point potential obtained by dividing the three-phase AC power supply with a capacitor;
The power supply line and the first detection line are inserted, and the common mode current is detected with a detection ratio of gain 1 / N1 (N1 ≧ 2) by the first detection line, and a first common mode current detection signal is output. First current detection means;
A first amplifying means for amplifying the first common mode current detection signal with an amplification factor N1 and flowing between the virtual neutral point and ground via a first capacitor;
The power supply line, the second detection line, and the output of the first amplifying unit are inserted, and the difference between the common mode current and the output current of the first amplifying unit is gained by a gain 1 / N2 (N2) by the second detection line. Second current detection means for detecting at a detection ratio of ≧ 2) and outputting a second common mode current detection signal;
A second amplifying means for amplifying the second common mode current detection signal at an amplification factor N2 and flowing between the virtual neutral point and ground via a second capacitor;
An active filter device comprising: Three-phase AC power source to which three power lines are connected, and AC power supplied from the three-phase AC power source is converted into predetermined AC power or DC power and supplied to the load, and power conversion having a ground terminal in the housing An active filter device provided between the device and reducing noise due to a common mode current flowing in the power line,
Having a virtual neutral point potential obtained by dividing the three-phase AC power supply with a capacitor;
The power supply line and the first detection line are inserted, and the common mode current is detected with a detection ratio of gain 1 / N1 (N1 ≧ 2) by the first detection line, and a first common mode current detection signal is output. First current detection means;
A first amplifying means for amplifying the first common mode current detection signal with an amplification factor of 1 and flowing between the virtual neutral point and ground via a first capacitor;
A third capacitor having an admittance (N1-1) times that of the first capacitor, and causing a current to flow from the terminal having substantially the same potential as the first amplification means to the virtual neutral point or ground;
The power supply line, the second detection line, and the output of the first amplifying unit are inserted, and the difference between the common mode current and the output current of the first amplifying unit is gained by a gain 1 / N2 (N2) by the second detection line. Second current detection means for detecting at a detection ratio of ≧ 2) and outputting a second common mode current detection signal;
A second amplifying means for amplifying the second common mode current detection signal at an amplification factor of 1 and flowing between the virtual neutral point and ground via a second capacitor;
A fourth capacitor having an admittance (N2-1) times that of the second capacitor, and causing a current to flow from the terminal having substantially the same potential as the second amplification means to the virtual neutral point or ground;
An active filter device comprising:   An AC power supply voltage is input on the three-phase AC power supply side from the first current detection means and the second current detection means, and rectified and smoothed to generate a predetermined DC voltage. The first amplification means and the second current supply The active filter device according to any one of claims 1 to 6, further comprising a DC power supply for supplying to the amplifying means.   8. The active filter device according to claim 7, wherein a negative electrode or a positive electrode of the DC power supply is connected to the power line of the ground phase or the virtual neutral point.   9. The power conversion device according to claim 1, wherein AC power supplied from a three-phase AC power source is converted into predetermined AC power or DC power and supplied to a load. A power converter provided on the input side.

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