JP5141216B2 - 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 to the DC side in a floating state in an uninterruptible power supply device, a large high-frequency leakage current tends to flow from a long DC cable, 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. 12 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 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. 12, 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. 12 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. 13 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. Further, in this feed forward method, the amplifier circuit 122 can be reduced in size.
JP 2003-174777 A (FIGS. 1 and 17)

  However, in order to cause the same high frequency current as that of the main power supply line to flow to the detection line of the zero-phase current transformer 121 (current transformer), it is necessary to reduce the impedance of the detection line to about the main power supply line. For this reason, a current transformer becomes 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. Current detection means for inserting the power supply line and the detection line, detecting the common mode current with a detection ratio of 1 / N (N> 1) by the detection line, and outputting a common mode current detection signal; Amplifying means for amplifying the common mode current detection signal with an amplification factor of 1 and flowing between the ground phase power line and the ground through the first capacitor, and (N-1) times the first capacitor. The admittance of From means and having substantially the same potential terminal, and having a second capacitor supplying a current to the power supply line or ground of the ground phase.

  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 for reducing noise caused by a common mode current flowing in the power line, the power filter being provided between the power converter having a ground terminal in the housing, Is inserted, and the detection line detects the common mode current at a detection ratio of 1 / N (N> 1) and outputs a common mode current detection signal, and the common mode current detection signal is amplified. A first amplifying means that amplifies at 1 and flows between the ground phase power line and the ground via a first capacitor; and a second output that outputs the same potential as the output of the first amplifying means. An amplifying means and the first capacitor; Has N-1) times the admittance, the output of the second amplifying means, and having a second capacitor supplying a current to the power supply line or ground of the ground phase.

  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 for reducing noise caused by a common mode current flowing in the power line, the power filter being provided between the power converter having a ground terminal in the housing, Is inserted, and the detection line detects the common mode current at a detection ratio of 1 / N (N> 1) and outputs a common mode current detection signal, and the three-phase than the current detection means. The common mode current detection signal is amplified with an amplification factor of 1 based on a DC power supply that inputs an AC power supply voltage on the AC power supply side, outputs a predetermined DC voltage by rectifying and smoothing, and a DC voltage supplied from the DC power supply. The first Amplifying means that flows between the power line of the ground line and the ground via a capacitor, (N-1) times admittance of the first capacitor, and from a terminal having substantially the same potential as the amplifying means, And a second capacitor for passing a current to the ground phase power line or ground.

  The invention of claim 4 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 for reducing noise caused by a common mode current flowing in the power line, the power filter being provided between the power converter having a ground terminal in the housing, Is inserted, and the detection line detects the common mode current at a detection ratio of 1 / N (N> 1) and outputs a common mode current detection signal, and the three-phase than the current detection means. The common mode current detection signal is amplified with an amplification factor of 1 based on a DC power supply that inputs an AC power supply voltage on the AC power supply side, outputs a predetermined DC voltage by rectifying and smoothing, and a DC voltage supplied from the DC power supply. The first A first amplifying means that flows between the power line of the ground line and the ground via a capacitor; a second amplifying means that outputs the same potential as the output of the first amplifying means; and the first capacitor And (N-1) times the admittance, and having a second capacitor for flowing a current from the output of the second amplifying means to the power line of the ground phase or the ground.

  According to a fifth aspect of the present invention, in the active filter device according to the third or fourth aspect, a negative electrode or a positive electrode of the DC power supply is connected to the power line of the ground phase.

  The invention according to claim 6 is the power converter for converting the AC power supplied from the three-phase AC power source into predetermined AC power or DC power and supplying the converted power to the load. The active filter device described in 1 is provided on the input side.

  According to the present invention, the current detecting means detects the common mode current with a detection ratio of 1 / N, and the amplifying means amplifies the detected common mode current detection signal with an amplification factor of 1, and passes through the first capacitor. The second capacitor is caused to flow between the power line of the ground phase and the ground, and the (N-1) / N current of the common mode current detection signal is caused by admittance (N-1) times that of the first capacitor. To the ground phase or grounded power line. That is, since the current having the same value as the common mode current flows through the ground phase power line or ground, the common mode current flowing out to the AC system can be reduced. For this reason, the noise which generate | occur | produces can be reduced, and it can achieve low cost and size reduction.

  Further, even when an electric wire that is thinner (high impedance) than the main power supply line is adopted as the detection line, it is less susceptible to the voltage effect generated on the detection line, and the current detection means can be made smaller. Further, since the input impedance of the amplifying means can be increased, the amplifying means is also reduced in size.

  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 earth-to-ground capacities everywhere, and these are put together, and the earth-to-ground capacitance between the negative electrode of the capacitor C0 of the power conversion device 3 and the ground terminal E is summarized. It will be shown as 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 (current detection means), an amplifier 11 (amplification means) consisting of a transistor 11a made of NPN and a transistor 11b made of PNP, a low frequency separation capacitor C1 (first capacitor), It has a low frequency separation capacitor C2 (second capacitor) and a DC power supply Vc. It is assumed that the amplification factors of the transistors 11a and 11b are sufficiently large with respect to the number of detection line turns described later. When the amplification factors of the transistors 11a and 11b are small and cannot be ignored, the method shown in FIG. 5 described later is used.

  In the current transformer 10, power supply lines 1a to 1c for R-phase, S-phase, and T-phase, which are main power supply lines, are wound (penetrated) by 1T (turn) on a toroidal core, and a detection line 10a is For example, it is wound by 10T.

  The collector of the transistor 11a is connected to the positive electrode of the DC power supply Vc, 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 C1, and the low-frequency separation capacitor C1. The end is connected to the power supply line 1b which is a ground phase.

  The emitter of the transistor 11a is connected to the emitter of the transistor 11b, the other end of the detection line 10a, and one end of the low-frequency separation capacitor C2, and the other end of the low-frequency separation capacitor C2 is connected to the power line 1b that is the ground phase. Yes. The collector of the transistor 11b is connected to the negative electrode of the DC power source Vc and the ground terminal E.

  The low frequency separation capacitor C2 has an admittance that is nine times the admittance of the low frequency separation capacitor C1. That is, the low frequency separation capacitor C2 has a capacitance value nine times that of the low frequency separation capacitor C1.

  Further, choke coils L1, L2, and L3 are connected in series to the power supply lines 1a, 1b, and 1c inserted through the current transformer 10, 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.

  In addition, as a power converter device, you may use the inverter which converts the alternating current power supplied from the three-phase alternating current power supply 1 into predetermined alternating current power, and supplies it to the load 5. FIG.

  FIG. 2 is a diagram illustrating an equivalent circuit of the active filter device according to the first embodiment. FIG. 3 is a diagram showing an equivalent circuit of the conventional active filter device shown in FIG.

  Next, the operations of the conventional active filter device and the active filter device of the first embodiment will be described with reference to FIGS. 1 to 3.

First, in the conventional configuration shown in FIG. 3, the flows common mode current _{i 0} to the power supply line 1a~1c of 1T, the detection line of 1T, it flows common mode current _{i 0} and the same current _{i 0} '. The amplifier unit V causes a current i ₁ equal to the current i ₀ ′ to flow to the ground line via the capacitor C6. However, since it is difficult to reduce the impedance of the amplifier unit V from the detection line, there is a problem that the current transformer becomes large.

Next, in the configuration of the first embodiment, when the common mode current i ₀ flows through the 1T power supply lines 1a to 1c in the current transformer 10, the 10T detection line 10a has a current of 1/10 of the common mode current. i ₁ = i _0/10 flows.

Amplifier 11, an amplifier V1 for controlling the voltage to equal the current i ₁ flowing to the low-frequency isolation capacitor C1 to the current i _0/10, has a voltage identical to the voltage of the amplifier unit V1, the low-frequency separating capacitors C1 is equivalent to having an amplifier portion V2 for supplying a current _{i 2 = 9i 1 = 9i 0} /10 to the low-frequency isolation capacitor C2 with 9 times the volume of.

That is, the amplifier unit V1 amplifies the current i _0/10 , which is one-tenth of the common mode current detected by the detection line 10a, with an amplification factor of 1, and supplies the ground-phase power line 1b via the low-frequency separation capacitor C1. Shed. Also, the amplifier unit V2, the power supply line of the low-frequency isolation 9 times the current of the current _i 1 _{= i} 0/10 flowing through the capacitor _{C1 i 2 = 9i 1 = 9i} 0/10 a via a frequency separating capacitors C2 ground phase Current is passed through 1b.

Therefore, the power supply line 1b of the ground phase, the current flows i ₀ of the same value and the common-mode current i _0, can reduce common mode current flowing to the AC system. For this reason, the noise which generate | occur | produces can be reduced, and it can achieve low cost and size reduction.

  Further, since the current flowing through the detection line 10a is small, the detection line 10a thinner than the power supply lines 1a to 1c can be used. Further, since the current flowing through the detection line 10a is small, the voltage drop in the detection line 10a is small, and the physical distance between the current transformer 10 and the amplifier 11 can be increased.

  Further, since the output signal level of the detection line 10a is increased by increasing the number of turns of the detection line 10a, the S / N ratio for detecting the common mode current can be improved. Further, the core of the current transformer 10 can be made small.

  In the first embodiment, the turn ratio of the power supply lines 1a to 1c of the current transformer 10 and the detection line 10a is 1:10. However, the turn ratio is not limited to 1:10 (N> N). 1) is also acceptable.

  Further, since the common mode current can be reduced, electric power with less distortion can be supplied to the load 5.

(Modification)
FIG. 4 is a configuration diagram of an active filter device according to a first modification of the first embodiment. The first modification shown in FIG. 4 differs from the first embodiment shown in FIG. 1 in the following points.

  The negative electrode of the DC power supply Vc and the collector of the transistor 11b are connected to the ground phase power supply line 1b. One end of the low frequency separation capacitor C1 is connected to a connection point between the base of the transistor 11a and the base of the transistor 11b and one end of the detection line 20a, and the other end of the low frequency separation capacitor C1 is grounded. One end of the low frequency separation capacitor C2 is connected to a connection point between the emitter of the transistor 11a and the emitter of the transistor 11b and the other end of the detection line 20a, and the other end of the low frequency separation capacitor C2 is grounded. In FIG. 4, the current transformer is 20 and the detection line is 20a. The detection line 20a in FIG. 4 is opposite to the winding direction of the detection line 10a in FIG.

  Thus, according to the structure of the modification 1, it operate | moves similarly to the operation | movement of Example 1, and the same effect is acquired.

  FIG. 5 is a configuration diagram of an active filter device according to a second modification of the first embodiment. The modification 2 shown in FIG. 5 is characterized in that an amplifier 12 (second amplification means) connected in parallel with the amplifier 11 (first amplification means) is added to the modification 1 shown in FIG. And

  The amplifier 12 includes a transistor 12a and a transistor 12b. The connection point between the base of the transistor 12a and the base of the transistor 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 detection line 20a. One end of the low frequency separation capacitor C2 is connected to the connection point between the emitter of the transistor 12a and the emitter of the transistor 12b, and the other end of the low frequency separation capacitor C2 is grounded.

  The collector of the transistor 11a and the collector of the transistor 12a are connected to the positive electrode of the DC power supply Vc. The collector of the transistor 11b and the collector of the transistor 12b are connected to the negative electrode of the DC power supply Vc and the ground phase power supply line 1b.

  According to the second modification, since the amplifiers 11 and 12 are provided, the current flowing through the first-stage transistors 11a and 11b can be reduced as compared with the first modification. For this reason, the detection sensitivity of the amplifiers 11 and 12 can be improved.

  Further, in the first embodiment shown in FIG. 1 and the first modification shown in FIG. 4, a current 1 / hfe times the emitter current flows through the bases of the transistors 11a and 11b, which may cause an error. . Note that hfe is the amplification factor of the transistors 11a, 11b, 12a, and 12b.

  In the second modification shown in FIG. 5, the current flowing through the base of the amplifier 11 at the first stage is small and becomes almost negligible, so that an error hardly occurs.

  In addition, you may change the modification 2 of Example 1 shown in FIG. 5 as follows. That is, as in the first embodiment shown in FIG. 1, the other ends of the low frequency separation capacitors C1 and C2 are connected to the ground phase power line 1b, and the collectors of the transistors 11b and 12b are grounded. good. The current transformer is 10 and the detection line is 10a.

  FIG. 6 is a configuration diagram of an active filter device according to a third modification of the first embodiment. The active filter device of Modification 3 is obtained by adding a bias circuit having resistors 13A and 13B and capacitors C3 and C4 to the active filter device of Embodiment 1 shown in FIG. The base-emitter voltage drop of the transistors 11a and 11b is corrected.

  The resistor 13A is connected between the collector and base of the transistor 11a. The capacitor C3 is connected between the base of the transistor 11a and one end of the detection line 10a and one end of the capacitor C1. The resistor 13B is connected between the collector and base of the transistor 11b. The capacitor C4 is connected between the base of the transistor 11b and one end of the detection line 10a and one end of the capacitor C1.

  In a general transistor, the base current does not flow unless a voltage of about 1 V is applied between the base and the emitter due to the barrier voltage of the PN junction between the base and the emitter.

  According to the active filter device of the third modification, since the bias circuit for correcting the voltage drop between the base and emitter of the transistors 11a and 11b is provided, the dead band is obtained by biasing the base potential using the voltage effect across the capacitor. An amplifier with excellent linearity can be realized.

  FIG. 7 is a configuration diagram of the active filter device and the power conversion device according to the second embodiment. The detection line 20a in FIG. 7 is opposite to the winding direction of the detection line 10a in FIG. The active filter device 7a according to the second embodiment is used as a DC power source (operation power source for the amplifier 11) that inputs an AC power source voltage on the three-phase AC power source 1 side of the current transformer 20 and outputs a predetermined DC voltage by rectifying and smoothing. The diode D7 and the capacitor C5 are provided, and the DC voltage of this DC power supply is supplied to the amplifier 11. The anode of the diode D7 is connected to the R-phase power line 1a, and the cathode of the diode D7 is connected to the collector of the transistor 11a and one end of the capacitor C5. The other end of the capacitor C5 is connected to the ground phase power line 1b and the collector of the transistor 11b.

  One end of the capacitor C1 is connected to the bases of the transistors 11a and 11b, and the other end of the capacitor C1 is grounded. One end of the capacitor C2 is connected to the emitters of the transistors 11a and 11b, and the other end of the capacitor C2 is grounded.

  According to the active filter device of the second embodiment configured as described above, the positive voltage of the AC voltage between the R-phase power line 1a and the ground-phase power line 1b is reduced by the diode D7 and the capacitor C5. The wave is rectified and smoothed, and a predetermined DC voltage is output to the amplifier 11 to operate the amplifier 11.

Further, with respect to the common mode current _{i 0,} the amplifier 11 amplifies the common-mode current _i 0/10 detected by the detection ratio of 1/10 by the current transformer 20 by an amplification degree 1, via a capacitor C1 It flows between the ground phase power line 1b and the ground. Further, the amplifier 11, a current flows _9i 0/10 between the ground and the power supply line 1b of the ground phase via a capacitor C2 (= 9C1).

  Therefore, since the current having the same value as the common mode current flows through the power phase 1b of the ground phase, the common mode current flowing out to the AC system can be reduced. For this reason, the effect similar to the effect of Example 1 is acquired. Further, there is an advantage that a DC power source for operating the amplifier 11 can be generated using the AC voltage of the three-phase AC power source 1.

  In addition, you may change Example 2 shown in FIG. 7 as follows. That is, as in the first embodiment shown in FIG. 1, the other ends of the low frequency separation capacitors C1 and C2 may be connected to the ground phase power line 1b and the collector of the transistor 11b may be grounded. The current transformer is 10 and the detection line is 10a.

(Modification)
FIG. 8 is a configuration diagram of an active filter device according to a first modification of the second embodiment. A modification 1 of the second embodiment shown in FIG. 8 is characterized in that an amplifier 12 shown in FIG. 5 is further provided to the second embodiment shown in FIG. The parallel connection relationship between the amplifier 11 and the amplifier 12 and the grounding of the low frequency separation capacitor C2 are the same as those of the second modification of the first embodiment shown in FIG.

  According to the active filter device of the first modification of the second embodiment configured as described above, the effects of the second embodiment and the effects of the second modification of the first embodiment can be obtained.

  In addition, you may change the modification 1 of Example 2 shown in FIG. 8 as follows. That is, as in the first embodiment shown in FIG. 1, the other ends of the low frequency separation capacitors C1 and C2 may be connected to the ground phase power line 1b, and the collectors of the transistors 11b and 12b may be grounded. . The current transformer is 10 and the detection line is 10a.

  FIG. 9 is a configuration diagram of the active filter device and the power conversion device according to the third embodiment. The detection line 20a in FIG. 9 is opposite to the winding direction of the detection line 10a in FIG. The active filter device 7b of the third embodiment is different from the active filter device of the second embodiment shown in FIG. 7 in that the cathode of the diode D7 is connected to the R-phase power line 1a and the anode of the diode D7 is connected to the capacitor C5. One end (negative electrode) is connected to the collector of the transistor 11b, and one end (positive electrode) of the capacitor C5 is connected to the ground phase power line 1b and the collector of the transistor 11a.

  According to such a configuration, the negative voltage of the AC voltage between the R-phase power supply line 1a and the ground-phase power supply line 1b is half-wave rectified and smoothed by the diode D7 and the capacitor C5 to obtain a predetermined direct current. The voltage is output to the amplifier 11 to operate the amplifier 11. Other operations of the third embodiment are the same as those of the second embodiment, and the same effects as those of the second embodiment are obtained.

  FIG. 10 is a configuration diagram of the active filter device and the power conversion device according to the fourth embodiment. The detection line 20a in FIG. 10 is opposite to the winding direction of the detection line 10a in FIG. The active filter device 7c according to the fourth embodiment supplies a DC voltage obtained by smoothing a half-wave rectified positive half voltage of the AC voltage of the three-phase AC power supply 1 to the amplifier 11.

  In FIG. 10, 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 collector of the transistor 11a. 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 collector of the transistor 11b. The connection point between the cathode of the diode D8 and the capacitor C5 is connected to the collector of the transistor 11a.

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 for the amplifier 11.

  FIG. 11 is a configuration diagram of an active filter device and a power conversion device according to the fifth embodiment. The detection line 20a in FIG. 11 is opposite to the winding direction of the detection line 10a in FIG. In the active filter device 7d of the fifth embodiment, a DC voltage obtained by rectifying and smoothing the AC voltage of the three-phase AC power source 1 is supplied to the amplifier 11.

  In FIG. 11, a series circuit of a capacitor C5 and a capacitor C6 is connected between a collector of a transistor 11a and a collector of a transistor 11b, and a series circuit of a diode D7 and a diode D8 is connected. The connection point between the diode D7 and the diode D8 is connected to the R-phase power line 1a, and the connection point between the capacitor C5 and the capacitor C6 is connected to the ground-phase power line 1b.

  According to such a configuration, when the AC voltage of the R-phase power line 1a is positive, a current flows from the power line 1a to the ground-phase power line 1b via the diode D7 and the capacitor C5. A DC voltage obtained by rectifying and smoothing a positive AC voltage is generated at both ends of the capacitor C5. When the AC voltage of the R-phase power line 1a is a negative voltage, a current flows from the ground-phase power line 1b to the power line 1a via the capacitor C6 and the diode D8. A DC voltage is generated by rectifying and smoothing a positive AC voltage.

  For this reason, a double voltage rectified voltage is generated between the collector of the transistor 11a and the collector of the transistor 11b. That is, the AC voltage between the R-phase power supply line 1a and the ground-phase power supply line 1b is double-voltage rectified and smoothed to generate a DC voltage having the ground phase as a fixed potential and supply it to the amplifier 11. it can.

  In addition, this invention is not limited to the active filter apparatus of Example 1 thru | or Example 5. In the active filter devices of the first to fifth embodiments, the capacitor C1 is connected between the bases of the transistors 11a and 11b and the ground phase power line 1b, and between the emitters of the transistors 11a and 11b and the ground phase power line 1b. Is connected to the capacitor C2 (= 9C1). For example, a series circuit of a capacitor C1 and a resistor Ra (admittance is 1 / R) is connected between the bases of the transistors 11a and 11b and the ground phase power line 1b. A capacitor C2 (= 9C1) and a resistor Rb (admittance is 9 / R) may be connected between the emitters of the transistors 11a and 11b and the ground phase power line 1b.

  A DC voltage obtained by negative half voltage half-wave rectification or one-third voltage half-wave rectification may be used as the power source of the amplifier 11.

  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. It is a figure which shows the equivalent circuit of the active filter apparatus of Example 1. FIG. It is a figure which shows the equivalent circuit of the conventional active filter apparatus shown in FIG. It is a block diagram of the active filter apparatus of the modification 1 of Example 1. FIG. It is a block diagram of the active filter apparatus of the modification 2 of Example 1. FIG. It is a block diagram of the active filter apparatus of the modification 3 of Example 1. FIG. 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 of the modification 1 of Example 2. FIG. 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 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 capacitance 5 Loads 7, 7a to 7d, 7-1, 7-2, 7a-1 Active filter device 10, 20 Current transformer 10a, 20a Detection lines 11a, 11b, 12a, 12b Transistors
13A, 13B, 13C resistance
C1, C2 Low frequency separation capacitors C0, C3, C4, C5, C6 Capacitors Q1-Q6 Switching element Q7 Transistors D1-D9 Diodes L1-L3 Choke coil Vc DC power supply

Claims (6)

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,
Current detection means for inserting the power line and the detection line, detecting the common mode current with a detection ratio of 1 / N (N> 1) by the detection line, and outputting a common mode current detection signal;
Amplifying means for amplifying the common mode current detection signal with an amplification factor of 1 and flowing between the power line of the ground phase and the ground via a first capacitor;
A second capacitor having an admittance (N-1) times that of the first capacitor and flowing a current from a terminal having substantially the same potential as that of the amplifying means to the power line or ground of the ground phase;
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,
Current detection means for inserting the power line and the detection line, detecting the common mode current with a detection ratio of 1 / N (N> 1) by the detection line, and outputting a common mode current detection signal;
A first amplifying means for amplifying the common mode current detection signal with an amplification factor of 1 and flowing between the ground phase power line and ground through a first capacitor;
Second amplification means for outputting the same potential as the output of the first amplification means;
A second capacitor having an admittance (N-1) times that of the first capacitor, and causing a current to flow from the output of the second amplifying means to the power line or ground of the ground phase;
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,
Current detection means for inserting the power line and the detection line, detecting the common mode current with a detection ratio of 1 / N (N> 1) by the detection line, and outputting a common mode current detection signal;
A DC power supply that inputs an AC power supply voltage on the three-phase AC power supply side than the current detection means, outputs a predetermined DC voltage by rectifying and smoothing,
Amplifying means for amplifying the common mode current detection signal with an amplification factor of 1 based on a direct current voltage supplied from the direct current power source, and flowing between the power line of the ground line and the ground via a first capacitor; ,
A second capacitor having an admittance (N-1) times that of the first capacitor and flowing a current from a terminal having substantially the same potential as that of the amplifying means to the power line or ground of the ground phase;
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,
Current detection means for inserting the power line and the detection line, detecting the common mode current with a detection ratio of 1 / N (N> 1) by the detection line, and outputting a common mode current detection signal;
A DC power supply that inputs an AC power supply voltage on the three-phase AC power supply side than the current detection means, outputs a predetermined DC voltage by rectifying and smoothing,
Based on the DC voltage supplied from the DC power supply, the common mode current detection signal is amplified by an amplification factor of 1, and is supplied between the power supply line of the ground line and the ground through a first capacitor. Amplifying means;
Second amplification means for outputting the same potential as the output of the first amplification means;
A second capacitor having an admittance (N-1) times that of the first capacitor, and causing a current to flow from the output of the second amplifying means to the power line or ground of the ground phase;
An active filter device comprising:   5. The active filter device according to claim 3, wherein a negative electrode or a positive electrode of the DC power supply is connected to a power line of the ground phase.   6. 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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