JP5378244B2 - Power converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power converter capable of suppressing a leakage current flowing to an AC power source and a load. <P>SOLUTION: A converter 11 is connected to an AC power source through an input-side filter 2 to convert AC to DC. An inverter 12 is connected to the converter 11 through a DC bus line 15, and converts DC to AC which is supplied to a load through an output-side filter 3. Neutral points of input-side and output-side capacitors 22 and 32 are connected together using a connection line 16, and the connection line 16 is grounded using a capacitor 5, resulting in reduced leakage current caused by stray capacitance. In a bridge circuit 100, an input side is connected to a DC bus line 15 and an output side is grounded by a serial circuit of a reactor 101 and a capacitor 102. A control circuit 200 generates in the capacitor 102 a voltage which cancels a common mode voltage VCEN that occurs at the capacitor 5 and a common mode voltage Vc that occurs at the DC bus line 15 to suppress the leakage current that reflows from a converter 1 to an AC power source and a load. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a power conversion device that receives an AC power supply and outputs an AC voltage of an arbitrary frequency, and in particular, an AC power supply by an operation of a converter that converts an AC voltage into a DC voltage or a DC voltage into an AC voltage. The present invention relates to a power conversion device that can reduce leakage current generated on the side.

  In general, in a power conversion device that receives an AC power supply and outputs an AC voltage having an arbitrary frequency, the converter includes a converter and an inverter, and the converter temporarily converts the AC voltage of the AC power supply into a DC voltage. The obtained DC voltage is converted into a stable AC voltage by an inverter and supplied to a load.

  In such a power conversion device, a filter is provided on the input side of the converter so that the influence of the carrier frequency component generated by switching of the switching elements constituting the converter is not transmitted to the AC power source side, and the inverter is installed. A filter is provided on the output side of the inverter so that the influence of the carrier frequency component generated by switching of the constituting switching element is not transmitted to the load side, and the influence of the carrier frequency is reduced by each of these filters. Yes.

  However, when filters are installed on the input side of the converter and on the output side of the inverter as described above, the carrier frequency component can be removed, but the DC voltage viewed from the ground includes the carrier frequency component. The resulting voltage fluctuation occurs. In view of such a situation, in the conventional power conversion device, the neutral point of the Y-connected capacitor constituting the filter on the input side of the converter and the Y-connected capacitor constituting the filter on the output side of the inverter There has been proposed a power conversion device that electrically connects sex points to each other (see, for example, Patent Document 1).

JP 09-294381 A (paragraph number 0007 and FIG. 1)

  The conventional power converter is configured as described above, and the neutral points of the input and output filter capacitors are connected to each other, but floating between the converter and inverter constituting the converter and the ground. Since the capacity is inevitably present, the high-frequency current generated by the switching of the converter leaks to the ground via the stray capacitance, and the high-frequency current again passes from the ground point on the AC power supply side through the input-side filter to the converter again. The high frequency current leaked to the ground through the stray capacitance flows from the ground point on the load side to the inverter again via the output side filter and circulates. Since the high-frequency current leaking from the converter through the stray capacitance is higher than the current of the carrier frequency component of the converter or inverter, the capacitor of the filter provided on the input side and the output side of the converter respectively. Depending on the situation, the circulation cannot be sufficiently prevented.

  The high-frequency current circulating in this way becomes a radiation noise source, which causes problems such as inducing interference to other devices connected to the AC power supply side that is the power supply system and affecting the radio frequency band.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain an AC power source connected to the power converter and a power converter capable of suppressing a leakage current flowing in a load. And

In the power converter according to the present invention,
A power conversion device having an input side filter, a converter, an output side filter, a bypass capacitor, a compensation circuit, and a compensation control device,
The input side and output side filters each have a reactor and a capacitor, and the capacitor has one terminal connected to the reactor and the other terminal connected in common.
The converter has a converter and an inverter,
The converter is connected to an AC power source through a filter on the input side and converts AC input to DC,
The inverter is connected to the DC output side of the converter, converts DC to AC, and supplies it to the load via the filter on the output side.
The other terminals of the input side and output side filter capacitors are connected by a connection line and grounded via a bypass capacitor,
The compensation circuit has a bridge circuit and a circulation capacitor, the input side of the bridge circuit is connected to the DC output side of the converter, and the output side is grounded via the circulation capacitor,
Compensation control device is intended to generate a direction of voltage to reduce the current flowing through the bypass capacitor on the basis of the common-mode voltage generated to the DC output side of the common mode voltage and converter occur bypass capacitor circulating condenser .

In the power converter according to the present invention,
A power conversion device having an input side filter, a converter, an output side filter, a bypass capacitor, a compensation circuit, and a compensation control device,
The input side and output side filters each have a reactor and a capacitor, and the capacitor has one terminal connected to the reactor and the other terminal connected in common.
The converter has a converter and an inverter,
The converter is connected to an AC power source through a filter on the input side and converts AC input to DC,
The inverter is connected to the DC output side of the converter, converts DC to AC, and supplies it to the load via the filter on the output side.
The other terminals of the input side and output side filter capacitors are connected by a connection line and grounded via a bypass capacitor,
The compensation circuit has a bridge circuit and a circulation capacitor, the input side of the bridge circuit is connected to the DC output side of the converter, and the output side is grounded via the circulation capacitor,
Compensation control device is intended to generate a direction of voltage to reduce the current flowing through the bypass capacitor on the basis of the common-mode voltage generated to the DC output side of the common mode voltage and converter occur bypass capacitor circulating condenser So
Leakage current flowing from the converter to the AC power supply or load can be suppressed.

It is a circuit diagram of the power converter device which is Embodiment 1 of this invention. It is explanatory drawing for demonstrating operation | movement of the power converter device of FIG. FIG. 2 is a detailed circuit diagram of a control circuit for controlling the bridge circuit of FIG. 1. 6 is a circuit diagram of a power conversion device according to a second embodiment. FIG. It is a detailed circuit diagram of the control circuit of FIG. FIG. 10 is a circuit diagram of a power conversion device according to a fourth embodiment. FIG. 9 is a circuit diagram of a power conversion device according to a fifth embodiment. FIG. 10 is a circuit diagram of a power conversion device showing a modification of the fifth embodiment. FIG. 10 is a detailed circuit diagram of a control circuit according to a sixth embodiment.

Embodiment 1 FIG.
1 to 3 show a first embodiment for carrying out the present invention. FIG. 1 is a circuit diagram of a power converter, and FIG. 2 is a diagram for explaining the operation of the power converter of FIG. FIG. 3 is a detailed circuit diagram of a control circuit for controlling the bridge circuit of FIG. In FIG. 1, a converter 1 converts an AC voltage received from a three-phase AC power supply having a commercial frequency (not shown) into a DC voltage, and converts the obtained DC voltage into a stable AC voltage. A filter 2 is provided on the input side of the converter 1, and a filter 3 is provided on the output side of the converter 1. A stray capacitance existing between the converter 1 and the ground is represented as a stray capacitance 4.

  The converter 1 includes a converter 11 that receives power from an AC power supply and converts the power into a DC voltage, and an inverter 12 that converts the DC voltage obtained by the converter 11 into a stable AC voltage and supplies the AC voltage to a load (not shown). The DC output side of the converter 11 and the DC input side of the inverter 12 are connected by a DC bus 15, and a voltage smoothing circuit 13 having a capacitor C 0 is connected to the DC bus 15.

  The converter 11 is configured by a three-phase full bridge circuit having a switching element Tr1 and a diode D1 as switching means, and the inverter 12 is a three-phase full bridge circuit having a switching element Tr2 and a diode D2 as switching means. It is configured. The switching elements Tr1 and Tr2 are subjected to switching control by a control means (not shown).

  Further, the above-mentioned filter 2 on the input side is configured so that the influence of the carrier frequency component generated by switching of the switching element Tr1 constituting the converter 11 is not transmitted to the AC power supply side, and the filter 3 on the output side is In order to reduce the influence of each carrier frequency so that the influence of the carrier frequency component generated by switching of the switching element Tr2 constituting the inverter 12 is not transmitted to the load side, the filter 2 on the input side Is composed of a reactor 21 and a capacitor 22, and similarly, the output-side filter 3 is also composed of a reactor 31 and a capacitor 32.

  The capacitor 22 constituting the input-side filter 2 has one terminal connected to the reactor 21 and the other terminal connected in common at a common connection point, which is a neutral point, and is connected to a Y-connection. 3 are connected in common at a common connection point where one terminal is connected to the reactor 31 and the other terminal is a neutral point to form a Y connection. The common connection point between the two is electrically connected to each other by the connection line 16 and is grounded via the bypass capacitor 5. A voltage detector 201 is connected to the terminal of the capacitor 5 and measures the terminal voltage. A voltage detector 202 for measuring the ground voltage on the negative side of the DC bus 15 connecting the converter 11 and the inverter 12 is provided.

  Further, the power conversion apparatus includes a bridge circuit 100 as a compensation circuit, a reactor 101, and a circulation capacitor 102, and is connected to a DC bus 15 on the DC output side of the converter 11. The bridge circuit 100 has a single-phase half-bridge circuit having a switching element Tr3 and a diode D3, and the output side of the bridge circuit is grounded via a series circuit of a reactor 101 and a capacitor 102. As shown in FIG. 3, the control circuit 200 as a compensation control device that controls the bridge circuit 100 includes bandpass filters 108 and 109, an adder 110, a polarity inverter 111, a carrier signal generator 112, and a comparator 113. . The power converter in this embodiment is characterized by having a bypass capacitor 5, a bridge circuit 100 as a compensation circuit, a reactor 101, a capacitor 102, and a control circuit 200 as a compensation control device.

  Prior to the description of the overall operation, the operation and problems when the bypass capacitor 5 is provided will be described. By providing the capacitor 5, even if a high-frequency current generated by switching the switching means of the converter 1 flows through the stray capacitance 4 existing between the converter 1 and the ground, the high-frequency current is It immediately flows from the input side filter 2 or the output side filter 3 to the converter 1 via the capacitor 5. For this reason, the high-frequency current leaked from the converter 1 to the ground via the stray capacitance 4 flows into the converter 1 again from the ground point on the AC power supply side via the input-side filter 2 and circulates, as in the prior art. Or high-frequency current leaked from the converter 1 to the ground via the stray capacitance 4 flows again from the load-side ground point to the converter 1 via the output-side filter 3 and circulates. It is suppressed from occurring.

  However, when the capacitor 102 for circulation is not provided but the capacitor 5 is provided alone, there are the following problems. That is, the neutral points of the capacitor 22 and the capacitor 32 are connected to each other and further grounded by the capacitor 5. At this time, as the operation of the converter 1, when the output voltage command of the converter 11 and the output voltage command of the inverter 12 are different from each other, for example, when the output frequencies are the same but the phases are different from each other, the common mode generated by each other Since the phase of the voltage is also different, there is a problem that the leakage current flows into the AC power supply side via the capacitor 5. In particular, when the common mode voltage is a low frequency that is a component that is three times the frequency of the output voltage of the converter 1, there is a possibility of causing a malfunction of a leakage breaker (not shown) installed on the AC power supply side. In the present invention, the capacitor 5 is provided to suppress the leakage current leaking to the ground via the stray capacitance, and the above-described problems when the capacitor 5 is provided alone can be solved.

  Next, the overall operation including the bridge circuit 100 will be described. In FIG. 2, a bridge circuit 100 generates a desired voltage VCEN2 in a capacitor 102 via a reactor 101 (details will be described later). At this time, assuming that the capacitance of the capacitor 5 and the capacitance of the capacitor 102 are equal, for example, if the bridge circuit 100 is controlled so as to satisfy the relationship VCEN = VCEN2, for example, low-frequency leakage flowing through the capacitor 5 The current iCEN is fed back to the converter 1 through the bridge circuit 100 as iCEN2 flowing by the voltage VCEN2 generated across the capacitor 102. In other words, since the current iCEN flowing through the capacitor 5 directly flows as iCEN2 through the capacitor 102, the leakage current flowing through the ground line on the AC power supply side can be made zero. The reactor 101 is for suppressing switching ripples generated by the switching operation of the bridge circuit 100.

  Here, the purpose of the bridge circuit 100 is to generate − (VCEN + VC) as a desired VCEN2 in the capacitor 102 shown in FIG. 2 (described later). Since the bridge circuit 100 is connected to the capacitor CO via the DC bus 15 (FIG. 1), there is already a common mode voltage VC generated by the converter 11, which is a voltage between the ground. is there. Therefore, as a voltage command to the bridge circuit 100, first, a voltage (−VC) (a voltage having the same peak value and opposite phase) opposite to the common mode voltage VC of the DC bus 15 on the DC output side of the converter 11 is generated. , Ensure the grounding point potential. At the same time, a voltage (-VCEN) having a phase opposite to that of the common mode voltage VCEN generated in the capacitor 5 is superimposed on both ends of the capacitor 102. As a result, the bridge circuit 100 has a voltage (−VCEN) opposite in phase to the common mode voltage VCEN and a voltage opposite in phase to the common mode voltage VC (−). A voltage VCEN2 (= − (VCEN1 + VC)) of the sum of VC) is generated.

  This operation will be described in more detail with reference to FIG. The control device 200 receives VCEN which is the voltage across the capacitor 5 detected by the voltage detectors 201 and 202 shown in FIG. 1 through the bandpass filters 108 and 109, and the common mode voltage VC generated by the converter 11 as an input voltage. Input as a signal. Note that VCEN and VC are voltages indicated by arrows in FIG.

  From the detected signals, frequency components to be reduced (for example, a triple component of the basic output frequency f of the converter 11) are extracted through bandpass filters 108 and 109, respectively. Next, these voltages are added by the adder 110 and the signal added by the polarity inverter 111 is inverted to generate a voltage command Vd * to the bridge circuit 100. Next, the PWM signal Vpwm is obtained by the carrier signal generator 112 and the comparator 113, and the on / off control of the switching element Tr3 constituting the bridge circuit 100 is performed by a known method. As a result, a desired voltage VCEN2 = − (VCEN1 + VC) as a compensation common mode voltage is generated at both ends of the capacitor 102, and a leakage current from the converter 1 is suppressed.

  As described above, according to this embodiment, the high-frequency current associated with the switching of the converter 1 is generated as a noise current via the stray capacitance of the converter 1 via the ground point on the AC power supply side or the ground point on the load side. The leakage current leaking to the AC power supply side through the noise suppression capacitor 22 on the input side can be reduced by the common mode voltage generated by the converter 1 while being suppressed from flowing. In addition, it is possible to prevent inconveniences such as inducing interference to other devices that are used and affecting the radio frequency band, and it is possible to prevent malfunction of the earth leakage breaker installed on the AC power supply side.

  In the power conversion device of FIG. 1, the neutral point of the capacitor 22 and the neutral point of the capacitor 32 are connected to each other and further grounded by the capacitor 5, thereby stray capacitance between the converter 1 and the ground. Leakage current due to is suppressed. However, when the capacitor 5 is provided, when the voltage command of the converter 11 and the voltage command of the inverter 12 are different, for example, when the output frequency is the same but the phase is different, the common mode voltage generated by the converter 11 and the inverter 12 are different. Since the phase of the common mode voltage at which the noise occurs is also different in synchronization, there is a problem that a common mode noise current is generated via the capacitor 5. In particular, when a low-frequency common mode voltage is generated, such as when the third harmonic voltage V3f is superimposed on the control signal of the converter 11, there is a possibility of causing a malfunction of the earth leakage breaker. The occurrence of this phenomenon is provided on the AC power supply 1 side by providing a capacitor 102 for circulation and generating a terminal voltage corresponding to the common mode voltage VCEN generated on the DC bus on the DC output side of the converter 11 in the reverse direction. This is prevented by reducing the leakage current that circulates and the leakage current that circulates the load side. The same applies to the following embodiments.

Embodiment 2. FIG.
4 and 5 show the second embodiment. FIG. 4 is a circuit diagram of the power converter, and FIG. 5 is a detailed circuit diagram of the control circuit. In FIG. 4, a voltage detector 301 is provided for detecting a terminal voltage of one phase of the capacitor 32 constituting the output side filter 3, for example, a U-phase capacitor. Note that the terminal voltage of the V-phase or W-phase capacitor may be detected. A control circuit 300 as a compensation control device is provided. As shown in FIG. 5, the control circuit 300 includes bandpass filters 120, 121, 122, an adder 123, a subtractor 124, an adder 125, a polarity inverter 111, a carrier signal generator 112, and a comparator 113. A feature of the power conversion device in this embodiment is that the voltage detector 301 detects the one-phase terminal voltage VINV of the capacitor 32 instead of directly detecting VC. Since other configurations are the same as those of the first embodiment shown in FIG. 1, the same reference numerals are given to the corresponding components and the description thereof is omitted.

Here, when the common mode voltage command generated by the inverter 12 is Vi, VC is calculated by the following equation (1). Since the common mode voltage command Vi is known in terms of control, VC is obtained by detecting VCEN and VINV. A voltage due to the common mode current is also generated at both ends of the reactor 31, but the value thereof is small, so that it can be ignored when the target common mode is a low frequency. VINV may be the terminal voltage of any phase of the capacitor 32. This is because the purpose is to detect only the common mode component by a band-pass filter described later, and it is irrelevant which phase voltage is detected.
VC = VCEN + VINV−Vi (1)

  The input voltage signal of the control circuit 300 (FIG. 5) includes VCEN which is a voltage across the capacitor 5 detected by the voltage detector 201, a common mode voltage VINV generated in the capacitor 32 detected by the voltage detector 301, This is a common mode voltage command Vi output from a control device of the inverter 12 (not shown). VCEN and VINV are voltages indicated by arrows in FIG. 4 and are detected by the voltage detectors 201 and 301.

  The detected voltage signals VCEN and VINV and the voltage command Vi are extracted through the bandpass filters 120 to 122, respectively, and frequency components to be reduced (for example, three times the basic output frequency f of the converter) are extracted. Next, an adder 123 and a subtractor 124 perform an operation corresponding to the above equation (1) to obtain VC, add the voltage VCEN, invert it with the polarity inverter 111, and invert the voltage command Vd * to the bridge circuit 100. Is generated. Next, the PWM signal Vpwm is obtained by the carrier signal generator 112 and the comparator 113, and the on / off control of the switching element Tr3 constituting the bridge circuit 100 is performed by a known method. As a result, a desired voltage VCEN2 = − (VCEN + VC) as a compensation common mode voltage is generated at both ends of the capacitor 102.

  Instead of detecting the one-phase terminal voltage VINV of the capacitor 32 of the filter 3 on the output side and the common mode voltage command voltage command Vi generated by the inverter 12, one of the capacitors 22 of the filter 2 on the input side is detected. The common terminal voltage VCON generated by the converter 11 and the common mode voltage command voltage command V2 generated by the converter 11 are detected, and together with the voltage VCEN across the capacitor 5, the common mode voltage VC of the DC bus 15 is detected in the same manner as in (1) above. Can also be requested.

  As described above, according to this embodiment, the high-frequency current associated with the switching of the converter 1 is generated as a noise current via the stray capacitance of the converter 1 via the ground point on the AC power supply side or the ground point on the load side. The leakage current leaking to the AC power supply side through the noise suppression capacitor 22 on the input side can be reduced by the common mode voltage generated by the converter 1 while being suppressed from flowing. In addition, it is possible to prevent inconveniences such as inducing interference to other devices that are used and affecting the radio frequency band, and it is possible to prevent malfunction of the earth leakage breaker installed on the AC power supply side.

  In addition, although VINV is detected as voltage detection, for example, since a voltage detector for detecting VINV is already present in a power converter, a new voltage detector is additionally provided by using the voltage detector also for VINV detection. Since it becomes unnecessary, the number of parts can be reduced.

Embodiment 3 FIG.
In the first embodiment, the common mode voltage VC is directly detected by the voltage detector 201 (FIG. 1), and in the second embodiment, the current detector 301 detects the terminal voltage of the capacitor 32, thereby indirectly. However, the command value of the common mode voltage generated by the converter 11 may be used as VC. As a result, the voltage detection location is only VCEN, and the detection circuit and the arithmetic circuit can be simplified.

Embodiment 4 FIG.
FIG. 6 is a circuit diagram of a power conversion apparatus according to the fourth embodiment. In FIG. 6, a current detector 401 for detecting a current flowing through the bypass capacitor 5 is provided, and the detected current signal is input to a control circuit 400 as a compensation control device. Since other configurations are the same as those of the first embodiment shown in FIG. 1, the same reference numerals are given to the corresponding components and the description thereof is omitted. In the first to third embodiments, the voltage across the capacitor 5 is directly detected. However, as shown in FIG. 6, the current iCEN flowing through the capacitor 5 is detected by the current detector 401, and the capacitor is detected according to the following equation (2). The terminal voltage of 5 may be detected indirectly. Here, C5 is the capacitance of the capacitor 5.
VCEN = 1 / C5 × × (iCEN) dt (2)
Thereby, the current detector 401 can be applied as an alternative to the voltage detector 201 (FIG. 1). The current detector is generally less expensive than the voltage detector, has high noise resistance, and can be insulated from the capacitor 5.

Embodiment 5 FIG.
7 and 8 show the fifth embodiment, FIG. 7 is a circuit diagram of a power conversion device, and FIG. 8 is a circuit diagram of a power conversion device showing a modification. In FIG. 7, a current detector 501 is provided for detecting the current of one phase of the capacitor 32 constituting the output-side filter 3, for example, a U-phase capacitor. Also, a control circuit 500 is provided as a compensation control device to which the detection results of these current detectors 501 are input. In the second embodiment, the voltage across the capacitor 32 is directly detected. However, as shown in FIG. 7, the current iINV flowing through the capacitor is detected by the current detector 501, and the following equation (3) is applied. The voltage across the capacitor 32 may be detected indirectly. Here, C 32 is the capacitance of the capacitor 32.
VINV = 1 / C32 × ∫ (iINV) dt (3)

  Thereby, a current detector can be applied as an alternative to the voltage detector. Current detectors are generally less expensive than voltage detectors, have good noise resistance, and have the effect of eliminating the need for wiring to the main circuit.

  Further, although the current detector 501 is used in the one shown in FIG. 7, the current flowing through the connection line 16 connecting the common connection point of the capacitor 32 and the common connection point of the capacitor 22 as shown in FIG. You may detect with the detector 601. FIG. The control circuit 600 as the compensation control device operates in the same manner as the control circuit 500 shown in FIG. At this time, the total capacity of the capacitor is three times the capacity of C32 and the above equation (3) is applied.

Embodiment 6 FIG.
FIG. 9 is a detailed circuit diagram of the control circuit according to the sixth embodiment. In FIG. 9, a control circuit 700 as a compensation control device includes bandpass filters 108 and 109, an adder 110, a polarity inverter / multiplier 150, a carrier signal generator 112, and a comparator 113. In each of the above embodiments, the case where the capacitance of the capacitor 5 and the capacitance of the capacitor 102 are equal is shown. However, when these capacitances are different from each other, the capacitor 102 is set according to the difference in capacitance. Change the voltage command given to. That is, the relationship between the capacitance C5 of the capacitor 5 and the capacitance C102 of the capacitor 102 is expressed by the following equation (4).
C5 = C102 × K (4)

  At this time, in order to make the amplitude of the current iCEN flowing through the capacitor 5 and the current iCEN2 flowing through the capacitor 102 the same, the voltage command applied to the capacitor 102 is multiplied by K. For this purpose, the polarity inverter / multiplier 150 inverts the polarity of the signal from the adder 110 and multiplies it by K. Thereby, even when the capacitances of the capacitor 5 and the capacitor 102 are different from each other, the leakage current flowing out to the AC power supply side can be reduced, so that the degree of freedom in selecting the capacitance value is increased.

  In addition, this invention is not limited to the structure shown in said Embodiment 1-6, It is possible to add various deformation | transformation within the range which does not impair the objective. For example, in FIG. 1, the bridge circuit 100 is a two-level half-bridge inverter, but the same effect can be obtained even in the case of a multi-level inverter capable of generating three or more voltage levels. Further, although the converter 11 and the inverter 12 are two-level inverters, the same effect can be obtained when a multi-level inverter capable of generating three or more voltage levels is applied.

  Further, in each of the embodiments described above, switching elements such as a transistor (Tr), an IGBT (Insulated Gate Bipolar Transistor), and a MOSFET (Metal Oxide Field Effect Transistor) are used as switching elements of the converter 11 and the inverter 12 in the converter 1. Can be used as appropriate.

1 converter, 2, 3 filter, 5 capacitor, 11 converter,
12 inverter, 15 DC bus, 16 connection line, 22 capacitor,
32 capacitors, 100 bridge circuit, 102 capacitors,
150 polarity inverter / multiplier, 200 control circuit, 201 voltage detector,
202 voltage detector, 300 control circuit, 301 voltage detector, 400 control circuit,
401 current detector, 500 control circuit, 501 current detector, 600 control circuit,
601 Current detector, 700 Control circuit.

Claims (8)

A power conversion device having an input side filter, a converter, an output side filter, a bypass capacitor, a compensation circuit, and a compensation control device,
The input side filter and the output side filter each have a reactor and a capacitor, and the capacitor has one terminal connected to the reactor and the other terminal connected in common.
The converter has a converter and an inverter,
The converter is connected to an AC power source through the filter on the input side and converts AC input to DC,
The inverter is connected to the DC output side of the converter, converts the DC to AC and supplies the load to the load via the output side filter,
The other terminals of the capacitors of the input side and output side filters are connected to each other by a connection line and grounded via the bypass capacitor,
The compensation circuit has a bridge circuit and a circulation capacitor, the input side of the bridge circuit is connected to the DC output side of the converter, and the output side is grounded via the circulation capacitor,
The compensation control device, the direction of the voltage to reduce the current flowing through the bypass capacitor on the basis of the common-mode voltage generated to the DC output side of the common mode voltage and the converter to be generated in the bypass capacitor to the circulating condenser A power conversion device to be generated. The power conversion device according to claim 1 , wherein the compensation control device obtains a common mode voltage generated in the bypass capacitor based on a voltage of the bypass capacitor. The power conversion device according to claim 1 , wherein the compensation control device obtains a common mode voltage generated in the bypass capacitor based on a current flowing through the bypass capacitor. The voltage in the direction of decreasing the current flowing through the bypass capacitor is multiplied by the capacitance ratio according to a capacitance ratio between the capacitance of the bypass capacitor and the capacitance of the circulation capacitor. The power conversion device according to any one of claims 1 to 3 . The compensation control device according to claim 1, characterized in that those obtained by the common-mode voltage generated to the DC output side of the converter, detects the voltage between the DC output side and ground of the converter The power converter device described in 1. The compensation control device includes a common mode voltage generated on the DC output side of the converter, a voltage of the capacitor of the filter on the output side, a common mode voltage generated on the bypass capacitor, and a common mode voltage generated on the inverter. The power conversion device according to claim 1 , wherein the power conversion device is obtained based on the above. The power conversion device according to claim 6 , wherein the compensation control device obtains the voltage of the capacitor of the output-side filter based on a current flowing through the capacitor of the output-side filter. . The power conversion device according to claim 1 , wherein the compensation control device uses a common mode voltage acquired from a control command of the converter as a common mode voltage generated on the DC output side of the converter.

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