JP5119824B2 - 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.

  An active filter device as shown in FIG. 4 is known as a method for reducing the high-frequency leakage current flowing into the AC system (Patent Document 1).

  FIG. 4 is a configuration diagram of a conventional active filter device and a power conversion device. In FIG. 4, a three-phase AC power source 1, a power conversion device 3, a load 5, and an active filter device 8 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 8, respectively. The active filter device 8 includes a current transformer 10, an amplifier 11 composed of an NPN transistor 11a and a PNP transistor 11b, a low frequency separation capacitor 12, and a DC power source Vc.

  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 1T is wound.

  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 12. 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 and the other end of the detection line 10a, and the collector of the transistor 11b is connected to the negative electrode of the DC power source Vc and the ground terminal E.

  Further, Y capacitors (line bypass capacitors) 5A, 5B, and 5C are respectively connected between the power supply lines 1a, 1b, and 1c inserted through the current transformer 10 and the ground. 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 converter 3 includes Y capacitors 5A, 5B, and 5C, choke coils L1, L2, and L3, six diodes D1 to D6, switching elements Q1 to Q6 including six IGBTs, and a capacitor C0. Have. 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.

  According to the above configuration, the potential on the DC side changes sharply due to the switching of the switching elements Q1 to Q6 of the IGBT constituting the power conversion device 3. Accordingly, a high-frequency current flows through the ground-to-ground capacitor 4, and this current flows through the AC system as a common mode current.

When a common mode current flows through the 1T power lines 1a to 1c of the current transformer 10, the 1T detection line 10a of the current transformer 10 detects the same current as the common mode current and outputs it as a common mode current detection signal. The amplifier 11 amplifies the common mode current detection signal detected by the detection line 10 a of the current transformer 10 with an amplification factor of 1 and passes the amplified signal to the ground phase power supply line 1 b via the low frequency separation capacitor 12. For this reason, the common mode electric current which flows out into an alternating current system can be reduced.
JP 2003-174777 A

  However, in the active filter device 8 shown in FIG. 4, the main path of the common mode current is that by the Y capacitors 5 </ b> A, 5 </ b> B, and 5 </ b> C, and that through the ground-to-ground capacitance 4 that is parasitic on the DC side of the power converter 3. is there.

  When the three-phase AC power supply 1 is a three-phase three-wire system, the currents flowing through the Y capacitors 5A, 5B, and 5C of each phase are unbalanced, and the commercial frequency component is relative to the total current (total of each phase current). Superimpose. Further, the commercial frequency component is also superimposed on the current flowing through the ground capacitance 4 of the power conversion device 3. That is, many commercial frequency components of the three-phase AC power supply 1 are superimposed on the common mode current.

  When canceling the commercial frequency component superimposed on the common mode current with the conventional active filter device 8, in order to compensate the commercial frequency component via the low frequency separation capacitor 12, if the commercial frequency component is compensated, the low frequency separation capacitor 12 The terminal voltage increases and the output voltage of the amplifier 11 is saturated. When this voltage is saturated, the active filter device 8 does not function. Therefore, the conventional active filter device 8 needs to use a large-capacity low-frequency separation capacitor 12 or a large-capacity amplifier 11.

  An object of the present invention is to provide an active filter device and a power conversion device that can remove a commercial frequency component superimposed on a common mode current and are inexpensive with a simple configuration.

  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. Converted into AC power or DC power, supplied to the load, and provided with a power converter having a ground terminal on the housing and a Y capacitor on the input side, noise caused by the common mode current flowing in the power line An active filter device for reducing, wherein the power supply line and the detection line are inserted, the current detection means for detecting the common mode current by the detection line and outputting a common mode current detection signal, and the power supply for the ground phase Amplifying means connected between the line and ground, amplifying the common mode current detection signal with an amplification factor of 1, and flowing between the ground phase power line and the ground via a first capacitor; Electric A commercial frequency component in the common mode current detection signal by passing a current between two ungrounded phase power supply lines and the ground phase power supply line and adding the current to the common mode current detection signal. And removing means for removing.

  According to a second aspect of the present invention, in the active filter device according to the first aspect, the removing means includes a second capacitor having one end connected to one power line of the two non-grounded power lines, and the two A third capacitor having one end connected to the other power supply line of the non-ground phase power supply line and one end connected to the other end of the second capacitor and the other end of the third capacitor are inserted into the current detecting means. And a first compensation winding having the other end connected to the ground phase power line.

  According to a third aspect of the present invention, in the active filter device according to the second aspect, the removing means includes a fourth capacitor having one end connected to one power supply line of the two non-grounded power supply lines, and the two A fifth capacitor having one end connected to the other power line of the non-ground phase power line and one end connected to the other end of the fourth capacitor and the other end of the fifth capacitor are inserted into the current detection means. And a second compensation winding having the other end connected to the ground phase power line.

  According to a fourth aspect of the present invention, in the active filter device according to the third aspect, each of the first compensation winding and the second compensation winding is wound N (a positive integer) around the current detection means. In this case, the capacitance values of the second capacitor and the third capacitor are values obtained by dividing the capacitance value of the Y capacitor by N, and the capacitance values of the fourth capacitor and the fifth capacitor are It is a value obtained by dividing the capacitance value between the power converters by 3 · N.

  Invention of Claim 5 is the power converter device which converts the alternating current power supplied from the three-phase alternating current power supply into predetermined alternating current power or direct current power, and supplies it to a load, Any one of Claim 1 thru | or 4 The active filter device is provided on the input side of the Y capacitor.

  According to the first aspect of the present invention, the removing means causes a current to flow between the two non-ground phase power lines and the ground phase power lines, and adds the current to the common mode current detection signal to detect the common mode current. Remove commercial frequency components in the signal. That is, the commercial frequency component superimposed on the common mode current can be removed, and the capacities of the first capacitor and the amplifying means can be reduced, so that an inexpensive device can be realized with a simple configuration.

  According to the invention of claim 2, a current flows between one power line of the two non-ground phase power lines and the ground phase power line via the second capacitor and the first compensation winding, Since current flows between the other power line of the two non-ground phase power lines and the ground phase power line via the three capacitors and the first compensation winding, the common mode current detection signal causes the Y capacitor. The commercial frequency component between the current to be generated and the current due to the capacitance between the ground can be removed.

  According to the invention of claim 3, the same effect as that of the invention of claim 2 can be obtained.

  According to the invention of claim 4, by setting the capacitance value of each of the second capacitor and the third capacitor to a value obtained by dividing the capacitance value of the Y capacitor by N, the commercial frequency component of the current caused by the Y capacitor can be obtained. The capacitance value of each of the fourth capacitor and the fifth capacitor can be set to a value obtained by dividing the ground capacitance value of the power converter by 3 · N, so that the commercial frequency component of the current caused by the ground capacitance can be reduced. Can be removed.

  According to the invention of claim 5, since the active filter device of any one of claims 1 to 4 is provided on the input side of the power converter, the effects of claims 1 to 4 can be obtained.

  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. Since FIG. 1 differs from the configuration of the active filter device 8 shown in FIG. 4 only in the active filter device 7, only the active filter device 7 will be described.

  In FIG. 1, R-phase, S-phase, and T-phase power lines 1 a to 1 c are connected to terminals R 1, S 1, and T 1 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 12 (first capacitor), a direct current A power supply Vc, compensation windings 22 and 23, and compensation capacitors 20A, 20B, 21A, and 21B are provided.

  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, 1T winding is performed, and the compensation windings 22 and 23 are each wound, for example, 10T (turn).

  One end of the compensation capacitor (second capacitor) 20A is connected to the non-grounded phase power line 1a, and one end of the compensation capacitor (third capacitor) 20B is connected to the non-grounded phase power line 1c. One end of the compensation winding 22 (first compensation winding) is connected to the other end of the compensation capacitor 20A and the other end of the compensation capacitor 20B, and the other end of the compensation winding 22 is connected to the ground-phase power line 1b. Has been.

  One end of the compensation capacitor (fourth capacitor) 21A is connected to the non-ground phase power line 1a, and one end of the compensation capacitor (fifth capacitor) 21B is connected to the non-ground phase power line 1c. One end of the compensation winding 23 (second compensation winding) is connected to the other end of the compensation capacitor 21A and the other end of the compensation capacitor 21B, and the other end of the compensation winding 23 is connected to the ground-phase power line 1b. Has been.

  The compensation windings 22 and 23 and the compensation capacitors 20A, 20B, 21A and 21B constitute a removing means, and a current flows between the non-ground phase power supply lines 1a and 1c and the ground phase power supply line 1b. The current is added to the common mode current detection signal detected by the detection line 10a to remove the commercial frequency component in the common mode current detection signal.

  The detection line 10a, the amplifier 11, the low frequency separation capacitor 12, and the DC power source Vc have the same configuration as that shown in FIG.

  Next, the operation of the active filter device according to the first embodiment configured as described above will be described. Here, the capacitance value between the ground capacitors 4 is C4, the capacitance values of the Y capacitors 5A to 5C are C5, the capacitance values of the compensation capacitors 20A and 20B are C5 / 10, respectively, and the capacitance values of the compensation capacitors 21A and 21B. Is C4 / 30, respectively.

Currents i5A, i5B, and i5C flowing through the Y capacitors 5A, 5B, and 5C can be expressed by Expression (1).

  Here, (v1A-vE) is a voltage applied between one end of the Y capacitor 5A (the potential of the R-phase power line 1a) and the other end (the ground potential). (v1B-vE) is a voltage applied between one end of the Y capacitor 5B (the potential of the S-phase power supply line 1b) and the other end (the ground potential). (v1C-vE) is a voltage applied between one end (the potential of the T-phase power supply line 1c) and the other end (the ground potential) of the Y capacitor 5C.

  Since the S-phase power line 1b is grounded and v1B (potential of the S-phase power line 1b) and vE (ground potential) are substantially the same potential, i5B≈0.

The low frequency component (commercial frequency component) of the current i4 flowing through the ground-to-ground capacitance 4 can be expressed by equation (2).

These currents have a commercial frequency as a main component and flow to the three-phase AC power source 1. Currents i22 and i23 flowing through the compensation windings 22 and 23, respectively, can be expressed by equation (3).

  Since each of the compensation windings 22 and 23 is 10T, the total current of the sum of the current i22 and the sum of the current i23 is (i4 + i5A + i5C). That is, by winding the compensation windings 22 and 23 around the current transformer 10, the current caused by the Y capacitors 5A to 5C and the current caused by the ground capacitance 4 are detected from the common mode current detection signal detected by the detection line 10a. And commercial frequency components can be removed.

  Therefore, the low frequency component is eliminated from the current processed by the active filter device 7, the maximum terminal voltage of the low frequency separation capacitor 12 can be suppressed low, and the terminal voltage of the amplifier 11 can be suppressed low.

  FIG. 2 is a configuration diagram of the active filter device and the power conversion device according to the second embodiment. In the active filter device 7 of the first embodiment shown in FIG. 1, the number of turns of the auxiliary windings 22 and 23 is 10 times. However, in the active filter device 7a of the second embodiment shown in FIG. The number of windings is arbitrary N (positive integer), for example, 5 times.

  In this case, the capacitance values of the compensation capacitor 20a and the compensation capacitor 20b are values obtained by dividing the capacitance value C5 of the Y capacitors 5A to 5C by N. The capacitance values of the compensation capacitor 21a and the compensation capacitor 21b are values obtained by dividing the capacitance value C4 of the ground-to-ground capacitance 4 by 3 · N.

  Even the active filter device and the power conversion device according to the second embodiment operate in the same manner as the active filter device and the power conversion device according to the first embodiment, and the same effect can be obtained.

  FIG. 3 is a configuration diagram of the active filter device and the power conversion device according to the third embodiment. In the first embodiment shown in FIG. 1, when the compensation windings 22 and 23 are each wound 10T, the capacitance value of the ground capacitance 4 is C4, and the capacitance values of the Y capacitors 5A to 5C are C5, respectively, the compensation is performed. The capacitance values of the capacitors 20A and 20B were C5 / 10, respectively, and the capacitance values of the compensation capacitors 21A and 21B were C4 / 30, respectively.

  On the other hand, in the active filter device 7b of the third embodiment, the compensation winding 25 is wound 10T around the toroidal core of the current transformer 10. One end of the compensation capacitor 24A is connected to the R-phase power supply line 1a, the other end of the compensation capacitor 24A is connected to one end of the compensation winding 25, and the other end of the compensation winding 25 is connected to the ground-phase power supply line 1b. It is connected. One end of the compensation capacitor 24B is connected to the T-phase power line 1c, and the other end of the compensation capacitor 24B is connected to one end of the compensation winding 25.

  Further, when the capacitance value of the ground capacitance 4 is C4 and the capacitance values of the Y capacitors 5A to 5C are C5, the capacitance values of the compensation capacitors 24A and 24B are (C5 / 10) + (C4 / 30), respectively. / 2.

  By doing so, a current of (i5A + i4 / 2) / 10 flows through the compensation capacitor 24A and a current of (i5C + i4 / 2) / 10 flows through the compensation capacitor 24B, so that (i5A + i5C + i4) flows through the compensation winding 25. Current flows. Therefore, the commercial frequency components of the current caused by the Y capacitors 5A to 5C and the current caused by the ground capacitance 4 can be removed from the common mode current detection signal detected by the detection line 10a.

  As described above, the effect similar to the effect of the first embodiment can be obtained only by using the compensation winding 25, the compensation capacitor 24A, and the compensation capacitor 24B, and the number of parts can be further reduced.

  In addition, this invention is not limited to the active filter apparatus and power converter device of Examples 1-3 which were mentioned above. In the first embodiment, the capacitance values of the compensation capacitors C21A and C21B are set to 1/30 of the capacitance value C4 of the ground capacitance 4, but may be any value close to this.

  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 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 conventional active filter apparatus and a power converter device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Three-phase alternating current power supply 1a R-phase power supply line 1b S-phase power supply line 1c T-phase power supply line 3 Power converter 4 Capacitance between ground 5 Load 5A, 5B, 5CY Y capacitor 7, 7a, 7b Active filter device 10 Current Transformer 10a detection line 11a, 11b transistor
12 Low frequency separation capacitors 20A, 20B, 20a, 20b, 21A, 21B, 21a, 21b, 24A, 24B Compensation capacitors 22, 22a, 23, 23a, 25 Compensation winding C0 Capacitors Q1-Q6 Switching elements D1-D6 Diode L1 ~ L3 Choke coil Vc DC power supply

Claims (5)

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 converter having a ground terminal on the body and having a Y capacitor on the input side, and reducing 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 by the detection line, and outputting a common mode current detection signal;
An amplifying means connected between the ground phase power line and the ground, 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 a first capacitor When,
Among the three power lines, a current is passed between two ungrounded phase power lines and the ground phase power lines, and the current is added to the common mode current detection signal. Removing means for removing the commercial frequency component of
An active filter device comprising: The removing means includes
A second capacitor having one end connected to one of the two ungrounded phase power lines;
A third capacitor having one end connected to the other power line of the two ungrounded phase power lines;
A first compensation winding inserted into the current detection means, connected at one end to the other end of the second capacitor and the other end of the third capacitor, and connected at the other end to the power line of the ground phase;
The active filter device according to claim 1, comprising: The removing means includes
A fourth capacitor having one end connected to one of the two ungrounded phase power lines;
A fifth capacitor having one end connected to the other power line of the two ungrounded phase power lines;
A second compensation winding inserted into the current detection means, connected at one end to the other end of the fourth capacitor and the other end of the fifth capacitor, and connected at the other end to the power line of the ground phase;
The active filter device according to claim 2, further comprising:   When each of the first compensation winding and the second compensation winding is wound N (a positive integer) around the current detection means, the capacitance values of the second capacitor and the third capacitor are , A value obtained by dividing the capacitance value of the Y capacitor by N, and the capacitance values of the fourth capacitor and the fifth capacitor are values obtained by dividing the capacitance value between the power converter and the ground by 3 · N. 4. The active filter device according to claim 3, wherein the active filter device is provided.   5. The power conversion apparatus 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 of the Y capacitor.

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