JP2008067534A - Filter and power converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filter for a power converter which reduces a motor terminal surge voltage, a high-frequency noise to a power supply side, a common mode current to be applied to a motor and a leakage current of a basic component flowing on the power supply side without applying a filter current to a ground line, and to provided a power converter employing this filter. <P>SOLUTION: The filter is used for the power converter represented by an inverter or a matrix converter. The filter has a configuration in which an input filter of the power converter and an output filter of the power converter are integrated. The input filter is used to reduce a noise terminal voltage, and the output filter has a configuration in which a common mode filter and a normal mode filter are integrated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a filter device that reduces high-frequency noise generated by a switching operation of a power converter, and a power converter using the filter device.

As one of the problems on the input side of the power converter, there are noise terminal voltage and conduction EMI (Electro Magnetic Interference). In order to solve the above problem, conventionally, measures have been taken by adding an input filter to the input side of the power converter. In the conventional technique of a general input filter, in order to reduce common mode noise flowing out to the power supply side, a method of increasing the inductance of the common mode choke of the input filter or a method of increasing the capacitance of the grounding capacitor can be mentioned. However, the method of increasing the inductance of the common mode choke is larger in size and expensive than the method of increasing the capacitance of the grounding capacitor. Further, although the method of increasing the capacitance of the grounding capacitor is small in size and inexpensive, the leakage current of the fundamental wave component flowing on the power supply side increases.

Next, the prior art of the output filter will be described. Problems on the output side of the power converter include high-frequency leakage current, noise terminal voltage, radiation EMI, and electric corrosion of motor bearings (the contact between the bearing ring and the rolling element due to the high-frequency current passing through the rotating bearing ball bearing) A phenomenon that damages the surface, characterized by wavy wear) and surge voltage at the motor terminals. Conventionally, for example, an EMI filter disclosed in Patent Document 1 is used to suppress noise terminal voltage. Moreover, the countermeasure on the output side of the power converter has been implemented by adding an output filter. For example, there are Patent Document 2 and Non-Patent Documents 1 and 2 as output filters of conventional power converters. Patent Document 2 and Non-Patent Document 1 are common mode filters for suppressing common mode current.
Non-Patent Document 2 is composed of a normal mode filter for suppressing the noise current in the normal mode and a common mode filter for suppressing the common mode current. Since the common mode filter represented by Patent Document 2 and Non-Patent Document 1 has a resonance frequency of the filter lower than the carrier frequency of the power converter, high-frequency leakage current, conduction EMI, radiation EMI, and motor bearing power Eclipse can be effectively suppressed, but the surge voltage at the motor terminal cannot be suppressed. Further, the method represented by Non-Patent Document 2 is smaller in size because the filter cutoff frequency is much higher than the carrier frequency of the power conversion device, compared to the methods of Patent Document 2 and Non-Patent Document 1. And it becomes inexpensive. In addition to high-frequency leakage current, conduction EMI, and radiation EMI, surge voltage at the motor terminal can be suppressed. However, the method of Non-Patent Document 2 cannot suppress the electric corrosion of the motor bearing because the cut-off frequency of the common mode filter is much higher than the carrier frequency of the power converter.

  6A is a system configuration diagram when the motor 105 is driven by the power converter 102. FIG. Moreover, the measurement result of each part waveform at that time is shown to Fig.7, Fig.9 and Fig.11 (a). FIG. 7 shows the power converter output side phase voltage Vuv, the motor terminal voltage V′uv, and the phase currents Iu and I′u. 9A shows the common mode voltages Vc1 and Vc2 and the common mode current Ic1, and FIG. 9B shows the common mode voltage Vc2, the shaft potential Vs, and the bearing current Ib. FIG. 11A shows the noise terminal voltage.

As shown in FIG. 7, when the motor 105 is driven by the motor driving device 102, when the motor cable is long, even if the motor driving device output side voltage Vuv is a stepped voltage, the motor terminal voltage V'uv becomes an oscillating surge voltage. The crest value reaches about twice. Therefore, partial discharge occurs in the motor coil portion, which becomes a main factor of insulation deterioration.
Also, as shown in FIG. 9, at the moment when the common mode voltage Vc1 changes, the common mode current Ic1 becomes a high-frequency oscillating current having a peak value of 10A and flows to the ground line through the motor. The common mode current Ic1 is one of the main causes of conduction noise and radiation noise. Further, the common mode voltage Vc1 is divided by the stray capacitance of each part of the motor to cause the shaft potential Vs. When this axial potential Vs is generated, a discharge phenomenon is caused in the motor bearing portion, and a bearing current Ib on the order of several hundred mA flows through the bearing, and electric corrosion occurs. Moreover, as shown to Fig.11 (a), with respect to a noise terminal voltage, it is about 130 dBuV in 150 kHz, and it turns out that the big noise current is flowed out to the power supply side.

  FIG. 6B is a system configuration diagram when the input filter 101 is added to the motor drive device 102. Moreover, the noise terminal voltage at that time is shown in FIG.

As shown in FIG. 11B, the noise terminal voltage is about 88 dBuV at 150 kHz, which is about 40 dBuV lower than when the input filter 101 is not added.

As described above, the conventional input filter reduces noise terminal voltage by bypassing conduction noise, which is one of the causes of malfunction of peripheral devices, by the grounding capacitor.

JP-A-10-107571, page 5, FIG. Japanese Patent No. 3466118 IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL.28, NO.4, p858-p863, JULY / AUGUST 1992 IEEJ Transactions D, Vol.116, No.12, 1996, p1211-1219

When an input filter is added to the power converter, the common mode current Ic2 flowing out to the power supply side is reduced, but the common mode current Ic1 flowing into the motor is increased, and stress on the power converter 102 or the motor 105 is increased. Cause failure. Further, as a conventional technique, when reducing the common mode current Ic2 flowing out to the power supply side, there is a method of increasing the inductance of the common mode choke of the input filter or a method of increasing the capacitance of the grounding capacitor. However, the method of increasing the inductance of the common mode choke has a problem that the size is increased and the cost is increased as compared with the method of increasing the capacitance of the grounding capacitor. Further, although the method of increasing the capacitance of the grounding capacitor is small in size and inexpensive, there is a problem that the leakage current of the fundamental wave component flowing on the power supply side increases.
Further, when a common mode filter is added to the output side as in Patent Documents 1 and 2 and Non-Patent Document 1, high-frequency leakage current Ic1 flowing into the motor and electric corrosion of the motor bearing portion can be suppressed. Insulation breakdown of the wire cannot be suppressed. Further, as in Non-Patent Document 2, when a common mode filter and a normal mode filter having a cut-off frequency far higher than the carrier frequency of the power converter are added to the output side, the common mode current Ic1 and surge voltage flowing into the motor Although it is possible to suppress the dielectric breakdown of the motor winding due to, it is not possible to suppress the electric corrosion of the motor bearing portion.
In addition, although it is somewhat reduced against high-frequency noise such as noise terminal voltage, a dramatic effect cannot be obtained, so it is not suitable for countermeasures against noise flowing out to the power supply side. Rather, the current of the low frequency component (carrier frequency component) tends to increase. In general, the conventional output filter is often added as an external option of the motor drive device. When the motor drive device is vector-controlled, the vector control current sensor CT has to be rearranged. There is a problem that the motor must be driven by V / f control because it is normally impossible.

  The present invention provides a power conversion device that reduces motor terminal surge voltage, high-frequency noise to the power supply side, common mode current flowing to the motor, and leakage current of the fundamental wave component flowing on the power supply side without flowing the filter current through the ground line. An object is to provide a filter and a power converter using the filter.

In order to solve the above problems, the present invention is a filter device used in a power converter represented by an inverter, a matrix converter, etc., and includes an input filter of the power converter, an output filter of the power converter, In the filter device with a single structure, the input filter is a filter for reducing a noise terminal voltage, and the output filter is a common mode filter and a normal mode filter integrated with each other.
The present invention also relates to a filter device used in a power converter represented by an inverter, a matrix converter, etc., wherein the input filter of the power converter and the output filter of the power converter are integrated. In the apparatus, the input filter has a Y-connected capacitor, and a return line of the output filter of the power converter can be connected to a neutral point of the Y-connected capacitor. .
The present invention also relates to a filter device used in a power converter represented by an inverter, a matrix converter, etc., wherein the input filter of the power converter and the output filter of the power converter are integrated. In the apparatus, the output filter includes a common mode choke connected in series between the output unit of the power converter and the motor, a parallel circuit including an AC reactor and a resistor, the common mode choke, and the AC reactor. It is characterized in that a capacitor Y-connected between U, V, and W phases between parallel circuits formed of resistors, a neutral point of the Y-connected capacitor, and an input filter are configured via a capacitor. .
The present invention also relates to a filter device used in a power converter represented by an inverter, a matrix converter, etc., wherein the input filter of the power converter and the output filter of the power converter are integrated. In the apparatus, the output filter is connected to an output unit of the power converter, and includes a common mode choke connected in series between the output unit of the power converter and the motor and the Y-connected capacitor. A common mode filter, a normal mode filter composed of an AC reactor and a resistor are arranged in this order.
Moreover, this invention mounts the said filter apparatus as described in any one of Claim 1 thru | or 4 in a power converter device, It is characterized by the above-mentioned.
Further, the present invention is characterized in that the power converter is a matrix converter.

According to the present invention, in the filter device, the input filter is a noise terminal voltage reduction filter, and the output filter is a filter device that reduces the dV / dt of the common mode voltage / current and the output voltage of the power converter, and therefore flows out to the power source. High frequency noise, common mode current flowing in the power converter and motor, electric corrosion of the motor bearing portion, and surge voltage at the motor terminal can be suppressed.
Further, the present invention has a structure in which the return line of the output filter of the power converter can be connected to the neutral point of the Y-connected capacitor of the input filter, so that the output filter current does not flow to the ground line. Therefore, the noise terminal voltage can be reduced as compared with the conventional method. Further, since the present invention can reduce the noise terminal voltage as compared with the conventional method, the capacity of the grounding capacitor of the input filter can be reduced accordingly. Therefore, the leakage current of the fundamental wave component flowing on the power source side can be reduced, which leads to the solution of safety problems such as electric shock.
The present invention also includes a parallel circuit composed of a common mode choke, an AC reactor, and a resistor connected in series between the output unit of the power converter and the motor, and the common mode choke, the AC reactor, and a resistor. Since the capacitors connected to the U, V, and W phases between the parallel circuits that are Y-connected, the neutral point of the Y-connected capacitor, and the input filter are configured via capacitors, The filter can be designed with a resonance frequency lower than the carrier frequency of the converter, and for the normal mode, the filter can be designed with a cutoff frequency much higher than the carrier frequency.
Further, according to the present invention, since the filter device according to any one of claims 2 to 5 is mounted on the power conversion device according to claim 1, high frequency noise flowing out to the power source and common mode current flowing through the power conversion device and the motor are reduced. In addition, the motor can be driven not only by V / f control but also by vector control, and the labor of changing the arrangement of the vector control current sensor can be saved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a circuit diagram in the case where the input filter and the output filter of the present invention are added to the power conversion device according to the first embodiment. Reference numeral 106 denotes an integrated input filter and output filter according to the present invention. In FIG. 1, reference numeral 100 denotes a power source having a neutral point or one of three phases grounded, 105 denotes a motor whose frame is grounded, 103 denotes a power converter output filter, and 102 denotes It is a power converter and 101 input filter. Further, the power converter input filter of the present invention has a configuration as shown in 101. Here, the power converter input filter 101 of the present invention includes a common mode choke coil connected in series between a power source and the power converter, and each R, S, T between the common mode choke coil and the power converter. Each phase is composed of a grounding capacitor and a Y-connected capacitor between the R, S, and T phases, and the return line of the output filter of the power converter is connected to the neutral point of the Y-connected capacitor. It has a structure.

  Reference numeral 104 is a circuit diagram when the power converter input filter device and the output filter of the present invention are housed in an integrated structure as one module, and the input / output integrated filter device is added to the motor drive device.

The power converter input filter has an effect of suppressing the noise terminal voltage, and the output filter of the power converter is a filter device that reduces the common mode voltage / current and the dV / dt of the output voltage of the power converter. High-frequency noise flowing into the power converter, common mode current flowing in the power converter and motor, electric corrosion of the motor bearing portion, and surge voltage at the motor terminal can be suppressed.
The part where the present invention is different from Patent Documents 1 and 2 and Non-Patent Documents 1 and 2 is a part including an input filter and an output filter of a power converter, and the return line of the power converter output filter does not go through a ground line. The part connected to the power converter input filter of this invention. In addition, the circuit configuration of the output filter is a combination of a normal mode filter and a common mode filter.

  Next, the operation will be described. FIG. 2 shows the output filter, motor cable and motor circuit of the present invention. FIG. 3 shows an equivalent circuit for one phase of the output filter, motor cable and motor of the present invention. FIG. 4 shows a common mode equivalent circuit of the output filter, motor cable and motor of the present invention.

In FIG. 3, A shows an equivalent circuit for one phase of the output filter, the motor cable, and the motor.
The output filter of the present invention has different characteristics depending on the frequency domain. In the case of a low frequency region such as an operating frequency, the impedance of the AC reactor made up of the inductance Ln is much smaller than Rn, so that the resistance Rn can be ignored. Therefore, in the low frequency region, it can be approximated to the equivalent circuit shown in FIG. On the contrary, in the high frequency region, the impedance of the AC reactor including the inductance Ln is much larger than that of Rn, so that the AC reactor can be ignored. Therefore, it can be approximated to an equivalent circuit shown in FIG. Here, Ccable1 shown in FIG. 3 represents the stray capacitance between the phases of the motor cable.

  FIG. 4 shows an output filter, a motor cable, and a common mode equivalent circuit of the motor. Here, Ccable2 represents the stray capacitance between the power line and the ground line of the motor cable, and Cm represents the stray capacitance between the motor winding and the motor frame.

  FIG. 5 shows a normal mode equivalent circuit between phases when the output filter, motor cable and motor of the present invention are viewed from the output terminal of the power converter, and the input / output filter, power converter and motor cable shown in claims 1 to 5 of the present invention. And shows a common mode equivalent circuit of the motor. For the normal mode, the frequency component of the voltage Vuv between phases at the moment of switching by the power converter is a component of about several MHz, so dV / dt of Vuv is determined by Rn and Ccable1 shown in FIG. The For the common mode, the common mode voltage Vc1 is divided by the common mode choke Lc, and is configured by a bypass circuit including Cc1 and Cc2 having a smaller impedance than the motor side.

FIG. 6 is a circuit diagram showing a first embodiment of the present invention. 6A and 6B are prior art schemes, and C is a scheme according to the present invention.
A of FIG. 6 is a circuit configuration of only the power converter, and the waveforms of the respective parts at that time are shown in FIGS. 7, 9 and 11A. FIG. 7 shows the power converter output side phase voltage Vuv, the motor terminal voltage V′uv, and the phase currents Iu and I′u. FIG. 9 shows common mode voltages Vc1 and Vc2, common mode current Ic1, shaft potential Vs, and bearing current Ib. FIG. 11A shows the noise terminal voltage. FIG. 6B shows a circuit configuration when an input filter is added to the power converter, and the noise terminal voltage at that time is shown in FIG.
C in FIG. 6 is a circuit configuration when an input / output filter is added to the power converter of the present invention. Further, the waveforms of the respective parts at that time are shown in FIG. 8, FIG. 10 and FIG. 11 (c). FIG. 8 shows the power converter output side phase voltage Vuv, the motor terminal voltage V′uv, and the phase currents Iu and I′u. FIG. 10 shows common mode voltages Vc1 and Vc2, common mode current Ic1, shaft potential Vs, and bearing current Ib. FIG. 11C shows the noise terminal voltage.

As shown in FIG. 7, when the motor 105 is driven by the power converter 102, when the motor cable is long, even if the power converter output side voltage Vuv is a stepped voltage, the motor terminal voltage V'uv becomes an oscillating voltage, The peak value reaches about twice. Therefore, partial discharge occurs in the motor coil portion, which becomes a main factor of insulation deterioration. Also, as shown in FIG. 9, at the moment when the common mode voltage Vc1 changes, the common mode current Ic1 becomes a high-frequency oscillating current having a peak value of 10A and flows to the ground line through the motor. The common mode current Ic1 is one of the main causes of conduction noise and radiation noise. Further, the common mode voltage Vc2 is divided by the stray capacitance of each part of the motor to generate an axial potential Vs. When the shaft potential Vs is large, a discharge phenomenon occurs in the motor bearing, the bearing current Ib flows to the motor bearing, and electric corrosion of the motor bearing occurs. Moreover, as shown to Fig.11 (a), with respect to a noise terminal voltage, it is about 130 dBuV in 150 kHz, and it turns out that the big noise current is flowed out to the power supply side.

In addition, when the input filter 101 is added to the power conversion device 102 and the motor 105 is driven, as in the case of driving only with the power conversion device, if the motor cable is long, partial discharge occurs in the motor coil portion, resulting in insulation deterioration. Is the main factor. Further, the common mode current Ic1 and the electric corrosion of the motor bearing cannot be suppressed. Conversely, when the common mode current Ic1 is reached, the peak value increases. As shown in FIG. 11B, the noise terminal voltage is about 88 dBuV at 150 kHz, which is about 40 dBuV lower than when the input filter 101 is not added. As described above, when the input filter 101 is added, the noise terminal voltage is reduced, but the surge voltage and the electric corrosion of the motor bearing are not suppressed, and the peak value increases conversely when the common mode current Ic1 is reached. It will be counterproductive.

  As shown in FIG. 8, when the input filter 101 and the output filter 103 of the present invention are added to the power converter 102 and the motor 105 is driven, no surge voltage is generated at the motor terminal voltage V′uv even when the motor cable is long. . For this reason, partial discharge is unlikely to occur in the motor coil portion, and a longer motor life can be expected. As shown in FIG. 10, the common mode current Ic1 is suppressed to a current having a peak value of 1A or less at the moment when the common mode voltage Vc1 changes. Furthermore, since the shaft potential Vs is also small, a discharge phenomenon hardly occurs in the motor bearing, and electric corrosion of the motor bearing can be suppressed. Further, as shown in FIG. 11C, it can be seen that the noise terminal voltage is about 75 dBuV at 150 kHz, and is further reduced by about 10 dBuV compared to the case where only the input filter 101 is added. This is because the common mode current flowing to the power supply side is reduced by the output filter. Thus, by combining the input filter 101 and the output filter 103, the noise terminal voltage can be reduced without increasing the grounding capacitor capacity of the input filter 101. In addition, surge voltage and common mode current Ic1 at the motor terminal and electric corrosion of the motor bearing can be suppressed.

Here, it is possible to obtain the level of the noise terminal voltage shown in FIG. 11C by using only the input filter shown in FIG. 6B. As the method, the inductance value of the common mode choke is increased or the capacitance of the grounding capacitor of the input filter is increased. The method of increasing the inductance value of the common mode choke is large and expensive. Therefore, generally, the capacitance of the grounding capacitor is increased to suppress the noise terminal voltage. In order to obtain the level of the noise terminal voltage shown in FIG. 11C only by the input filter, a ground capacitor capacity 10 times as large as the ground capacitor of the input filter used in FIG. As shown in FIG. 12A, when the noise terminal voltage is reduced to the level shown in FIG. 11C using only the input filter, a leakage current of a fundamental wave component having a peak value of 200 mA flows. This value is 10 times the value of the method of the present invention shown in FIG. This leads to an increase in leakage current of the fundamental wave component flowing on the power supply side, which is a problem for human body protection.

Therefore, the power conversion device input / output integrated structure filter device of the present invention leads to longer motor life, malfunction of peripheral devices, reduction of noise terminal voltage, and prevention of electric shock.

FIG. 1 is a diagram showing the configuration of the second embodiment. The difference from the first embodiment is a portion in which the input / output filter and the power converter according to the present invention are integrated. Reference numeral 105 denotes a motor whose frame is grounded, and reference numeral 100 denotes a neutral point or a power source whose ground phase is grounded. Reference numeral 103 denotes a power converter output filter according to the method of the present invention, and reference numeral 101 denotes an input filter according to the method of the present invention.
By incorporating the input / output integrated type filter device of the present invention in the power conversion device, the vector control current sensor is arranged on the output side of the output filter, so that erroneous detection of the current generated by the influence of the common mode current can be prevented. Thus, vector control as well as V / f control is possible.

  Moreover, since the number of components can be reduced by making the input filter and output filter of the power conversion device built-in type, it is possible to contribute to cost reduction and miniaturization.

By adding a power conversion device input / output integrated filter device to the power conversion device, an inverter and a matrix converter (with a main circuit power switching element capable of flowing current in both directions, from an AC voltage of a commercial power source to a variable voltage / variable frequency) Directly converts power to AC voltage (also called PWM cycloconverter), so that noise generated in power converters such as represented by This can be applied to systems that require prevention of malfunction of peripheral equipment and longer motor life. In addition, since the input / output integrated filter device can suppress the leakage current of the fundamental wave component flowing on the power supply side, it leads to human body protection.
In addition, since the number of components can be reduced by making the input filter and output filter of the power conversion device into a built-in power conversion device, it is possible to contribute to cost reduction and downsizing.

The circuit diagram which shows the power converter device with a built-in input-output filter which shows the 1st and 2nd Example of this invention Circuit diagram showing the output filter, motor cable and motor of the present invention Equivalent circuit diagram showing one phase of output filter, motor cable and motor of the present invention Common mode equivalent circuit diagram showing output filter, motor cable and motor of the present invention An output filter, a motor cable and an equivalent circuit diagram showing the phase when the motor is viewed from the output terminal of the power converter, and an input / output filter built-in type power converter and motor showing the first and second embodiments of the present invention Common mode equivalent circuit shown A circuit diagram (A, B) showing the prior art and a circuit diagram (C) showing the power converter with built-in input / output filter of the present invention Measurement result diagram showing motor terminal voltage when using conventional technology Measurement result diagram showing motor terminal voltage when using power converter with built-in input / output filter of the present invention Measurement result diagram showing common mode voltage / current and shaft potential / bearing current when using conventional technology Measurement result diagram showing common mode voltage / current and shaft potential / bearing current when using the power converter with built-in input / output filter of the present invention Measurement result diagram showing noise terminal voltage Measurement result diagram showing the leakage current of the fundamental wave component flowing on the power supply side

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Power supply 101 Input filter 102 Power converter 103 Output filter 104 Power converter 105 which combined the integrated input filter and output filter by this invention system 105 Motor 106 Integrated input filter and output filter 107 by this invention system Motor cable

Claims (6)

  A filter device used in a power converter represented by an inverter, a matrix converter, etc., wherein the input filter of the power converter and the output filter of the power converter are integrated into the input device. The filter is a filter for reducing a noise terminal voltage, and the output filter has a common mode filter and a normal mode filter integrated with each other.   A filter device used in a power converter represented by an inverter, a matrix converter, etc., wherein the input filter of the power converter and the output filter of the power converter are integrated into the input device. The filter device has a structure in which the filter has a Y-connected capacitor, and a return line of the output filter of the power converter can be connected to a neutral point of the Y-connected capacitor.   In a filter device used in a power conversion device represented by an inverter, a matrix converter, and the like, in the filter device in which an input filter of the power conversion device and an output filter of the power conversion device are integrated, the output The filter includes a common mode choke, an AC reactor and a resistor connected in series between the output unit of the power converter and the motor, and a common circuit choke, the AC reactor, and a resistor. A filter device comprising: a capacitor Y-connected between U, V, and W phases between parallel circuits; a neutral point of the Y-connected capacitor; and an input filter.   In a filter device used in a power conversion device represented by an inverter, a matrix converter, and the like, in the filter device in which an input filter of the power conversion device and an output filter of the power conversion device are integrated, the output A filter connected to the output unit of the power converter, a common mode choke composed of a common mode choke connected in series between the output unit of the power converter and the motor and the Y-connected capacitor; AC A filter device, wherein a normal mode filter composed of a reactor and a resistor is arranged in this order.   A power conversion device comprising the filter device according to any one of claims 1 to 4 mounted on a power conversion device.   6. The power converter according to claim 5, wherein the power converter is a matrix converter.

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