DE102021110787A1 - NOISE FILTER AND CONVERTER - Google Patents

Abstract

A noise filter comprises a common mode choke coil, a plurality of input capacitors in delta connection, the plurality of input capacitors being provided on an input side of the common mode choke coil, a plurality of output capacitors in a star connection, the plurality of output capacitors being provided on the output side of the common mode choke coil, and an output capacitor of the plurality of neutral points and connected to one earth.

Description

BACKGROUND OF THE INVENTION

1. Field of the invention

The present disclosure relates to a noise filter and a power converter.

2. Description of the prior art

A power converter such as an inverter or a pulse width modulation (PWM) rectifier is configured using a semiconductor device such as a MOSFET (metal oxide semiconductor field effect transistor) or IGBT (insulated gate bipolar transistor) as a switching device. Power converters are used in a variety of areas because they have the advantage of being able to convert electricity into a desired form.

However, electromagnetic noise (line noise and radiation noise) generated by switching operations in which switching elements are repeatedly turned on and off at high speeds from a few kHz to several hundred kHz can propagate into the air from the converter housing. Electromagnetic noise can also travel through a cable that connects the converter to a grid or a cable that connects the converter to a load. Propagation of electromagnetic noise in this way can cause problems such as damage or malfunction of peripheral devices and noise pollution of radio devices. For this reason, the electromagnetic noise generated by an electric and electronic device such as the power converter needs to be limited by the electromagnetic compatibility standard (EMC standard), and the electromagnetic noise needs to be sufficiently reduced.

As an EMC filter for reducing such electromagnetic noise, a noise filter using a common mode choke coil is known (see, for example, Patent Documents 1 and 2).

[State of the art]

[Patent document]

• [Patent Document 1] Japanese Patent Application Laid-Open No. H7-22886
• [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-216997

SUMMARY OF THE INVENTION

Line noise is generally divided into a common mode component and a differential mode component, depending on the propagation path. A noise attenuation performance of an EMC filter must be suitably determined in order to meet standards.

However, it may be necessary not only to reduce the common mode component and the differential mode component, but also to reduce a mode conversion component between the common mode component and the differential mode component.

The present disclosure provides a noise filter capable of attenuating the conversion component from the common mode component to the differential mode component and a power converter including the noise filter.

SUMMARY OF THE INVENTION

The present disclosure provides a noise filter comprising a common mode choke coil, a plurality of input capacitors in delta connection, the plurality of input capacitors being provided on an input side of the common mode choke coil, a plurality of output capacitors in star connection, the plurality of output capacitors being provided on the output side of the common mode choke coil, and a grounding capacitor. connected between zero points of the plurality of output capacitors and a ground. The present disclosure also provides a power converter with such a noise filter.

[Effects of the invention]

According to the present disclosure, the conversion component can be attenuated from the common mode component to the differential mode component.

Figure list

• 1 Figure 3 illustrates an embodiment of a motor drive system including a power converter in accordance with an embodiment.
• 2 Fig. 10 illustrates an example of a structure of a noise filter in a first comparative embodiment.
• 3 Fig. 13 illustrates an example of a structure of the noise filter according to a second comparative embodiment.
• 4th FIG. 11 illustrates an example of a measurement result of line noise of a Inverter to which the in 3 the illustrated noise filter is applied.
• 5 illustrates an example of the parallel resonance of the in 3 illustrated noise filter.
• 6th FIG. 14 illustrates an example of a path of a parallel resonance circuit of the noise filter of FIG 3 .
• 7th Fig. 10 illustrates a line connection state when measuring inductance components of a parallel resonance circuit.
• 8th Fig. 11 illustrates an example of a measurement result of line noise of an inverter to which a noise filter is applied.
• 9 Fig. 11 illustrates an example of a structure of the noise filter according to the embodiment.
• 10 FIG. 11 illustrates an example of a parallel resonance circuit of the in FIG 9 illustrated noise filter.
• 11th FIG. 11 illustrates an example of a simplified simulation result of a noise terminal voltage in the cases of FIG 4th (Reference), 8th (Moving to 150 kHz or less) and 9 (line-side Δ switching).
• 12th FIG. 11 illustrates an example of a simulation result obtained when the ratio of capacitances between the line-side and inverter-side line capacitors is changed while the resonance frequency is different from that in FIG 11th illustrated standard condition is kept almost constant.
• 13th Fig. 3 is an enlarged view of a portion of the frequency domain.
• 14th Fig. 11 illustrates an example of a simulation result in which the ratio is increased by increasing each capacitance of the multiline capacitors on the inverter side without changing the capacitance of the multiline capacitors on the network side from the standard condition.
• 15th Fig. 3 is an enlarged view of a portion of the frequency domain.
• 16 Fig. 11 illustrates an example of a simulation result in which the ratio is increased by reducing each capacitance of the multiline capacitors on the grid side without changing the capacitance of the multiline capacitors on the inverter side from the standard condition.
• 17th FIG. 13 is an enlarged view of a portion of the FIG 16 illustrated frequency range.
• 18th Fig. 11 illustrates an example of the simulation result in a case where the ratio is increased by reducing the capacities of the multi-line capacitors on the network side using the standards in which the capacities of all the line capacitors are set to 0.3 [µF].
• 19th FIG. 13 is an enlarged view of a portion of the FIG 18th illustrated frequency range.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments according to the present disclosure will be described below with reference to the drawings. 1 FIG. 10 illustrates an example of a structure of a motor drive system including a power converter in one embodiment. This in 1 illustrated motor drive system 100 includes a power converter 300 for converting AC power from an AC power supply 90 is supplied in alternating current with different frequencies and a motor 94 by one of the converter 300 supplied alternating current is driven.

The motor drive system 100 includes an input cable 91 that is an AC power supply 90 such as a utility power supply with the converter 300 connects. 1 Fig. 10 illustrates a mode in which a network model (LISN) is used to measure line noise of the variable speed motor drive system 100 between the AC power supply 90 and the input cable 91 is inserted. The LISN is not inserted in the normal usage mode in which the line noise does not need to be measured.

The input cable 91 comprises a cable 91r for supplying R-phase AC voltage from the AC power supply 90 is provided, a cable 91s for supplying an S-phase AC voltage from the AC power supply 90 is provided, a cable 91t for supplying an AC voltage of T-phase from the AC power supply 90 is provided, and a ground wire 91a. The cables 91r, 91s and 91t are respectively connected to the input terminals R, S and T which are in the converter 300 are provided. The ground wire 91a is connected to an input ground terminal E provided in the power converter 300 is provided. The converter 300 is via a ground wire 91a to a reference ground plane 93 such as the earth or the ground.

The converter 300 includes a noise filter 18th connected to the input terminals R, S, T and the input ground terminal E, and an inverter 200 that with the noise filter 18th connected is.

The noise filter 18th is a device that reduces electromagnetic noise (especially line noise) and has a function of reducing line noise generated from the inverter 200 of the converter 300 for AC power supply 90 flows. The noise filter 18th may have the function of being one of the inverter 200 of the converter 300 to reduce radiation noise emitted outside. The noise filter 18th has a structure including an LC filter, the detailed structure of which will be described below.

The inverter 200 controls the engine 94 by taking one off the AC power supply 90 supplied three-phase alternating current through diode rectification on the converter part 19th converts to a direct current and one from the inverter part 20th generated alternating current with the desired voltage and frequency. The inverter 200 comprises a converter part 19th that with the noise filter 18th is connected, decoupling capacitors C _dc and C _s , which are connected to the converter part 19th are connected, and an inverter part 20th connected to decoupling capacitors C _dc and C _s .

The converter part 19th is a rectifier circuit that feeds the three-phase alternating current from the intermediate terminals R ', S' and T 'through the noise filter 18th converts to direct current. The converter part 19th comprises six diodes 19a, 19b, 19c, 19d, 19e and 19f, to each of which one of the intermediate connections R ', S' and T 'via the noise filter 18th AC voltage provided is applied.

A diode 19a and a diode 19d are connected in series. The AC voltage of the R phase of the AC power supply 90 is via the R-phase power line of the noise filter 18th is applied to an intermediate point to which the diodes 19a and 19d are connected. The cathode of the diode 19a is connected to the positive electrode rail 21 of the inverter 200 and the anode of the diode 19d is connected to the negative electrode rail 22 of the inverter 200 tied together.

The diode 19b and the diode 19e are connected in series. The AC voltage of the S phase of the AC power supply 90 is via the S-phase power line of the noise filter 18th is applied to an intermediate point which is the connection point between the diode 19b and the diode 19e. The cathode of the diode 19b is connected to the positive electrode rail 21 of the inverter 200 and the anode of the diode 19e is connected to the negative electrode rail 22 of the inverter 200 tied together.

The diode 19c and the diode 19f are connected in series. The AC voltage of the T phase of the AC power supply 90 is via the T-phase power line of the noise filter 18th is applied to an intermediate point between the diode 19c and the diode 19f. The cathode of the diode 19c is connected to the positive electrode rail 21 of the inverter 200 and the anode of the diode 19f is connected to the negative electrode bar 22 of the inverter 200 tied together.

The decoupling capacitors C _dc and C _s are connected in parallel between the positive electrode rail 21 and the negative electrode rail 22. The decoupling capacitor C _dc has a larger capacitance than the decoupling capacitor C _s . The decoupling capacitor C _dc reduces the ripple of the direct voltage between the positive and the negative electrode rail 21. The decoupling capacitors C _s reduce high-frequency noise via ripples in the direct voltage.

The inverter part 20th is a circuit for converting DC voltage between the positive electrode bar 21 and the negative electrode bar 22 into a three-phase alternating current. The inverter part 20th comprises six switching elements S ₁ , S ₂ , S ₃ , S ₄ , S ₅ and S ₆ . The switching elements S ₁ , S ₂ , S ₃ , S ₄ , S ₅ and S ₆ are semiconductor devices such as IGBT.

The connection point between the switching element S ₁ and the switching element S ₄ is connected to the output terminal U. The connection point between the switching element S ₂ and the switching element S ₅ is connected to the output terminal V. The connection point between the switching element S ₃ and the switching element S ₆ is connected to the output connection W.

The motor drive system 100 includes an output cable 9 _{2 connecting} the power converter 300 with the engine 94 connects. The output cable 92 comprises a cable 92u for providing an AC voltage of the U phase to the motor 94 , a cable 92v for supplying V-phase AC voltage to the motor 94 , a cable 92w for supplying an AC voltage of W phase to the motor 94 and a ground wire 92a. The cables 92u, 92v and 92w are correspondingly connected to the output connections U, V and W of the converter 300 tied together. The grounding cable 92a is connected to an output grounding terminal E ″ included in the power converter 300 is provided.

The grounding part 12 is via the intermediate grounding terminal E ', the grounding conductor of the noise filter 18th , the input ground terminal E and the ground wire 91a to a reference ground plane 93 grounded. The grounding part 12 can be a heat sink for the inverter 20th be. The grounding part 12 is via the intermediate grounding connection E ', the grounding conductor of the noise filter 18th , the input ground terminal E, and the ground wire 91a to the reference ground plane 93 grounded. Hence the engine 94 via the converter 300 and the ground wire 91a to the reference ground plane 93 grounded.

The measuring device (not shown) measures and evaluates the over the input cable 91 incoming voltage at the LISN as the line noise. Multiple modes of the noise filter 18th are considered to meet a noise rule defined by CISPR or the like.

2 Fig. 11 illustrates an example of the structure of the noise filter in the first comparative embodiment. 3 Fig. 11 illustrates an example of the structure of the noise filter in the second comparative embodiment.

The in 2 illustrated noise filter 18A comprises multi-line _capacitors C X1-1 to C _X1-3 and multi-line _capacitors C X2-1 to C _X2-3 , which are respectively provided with Δ circuits (delta circuits) on both sides of a common mode choke coil Lc, and a plurality of grounding capacitors C _Y1 to C _Y3 connected between a power line of each phase on the inverter side and the grounding conductor. The in 3 illustrated noise filter 18B comprises the multi-line _capacitors C x1-1 to C _X1-3 and C _X2-1 to C _{X2-3 provided} with Y-connections (star connections) on both sides of a common mode choke coil Lc, and a grounding capacitor C _Y , the is connected between zero points of the multi-line _capacitors C X2-1 to C _X2-3 , which are provided with the Y-connection on the inverter side and the grounding conductor.

In the 2 The structure illustrated has the advantage that an equivalent line capacitance compared to the line capacitance in the in 3 illustrated structure can be increased by providing the line capacitors in the Δ connection to the line capacitors. On the other hand, the in 3 The structure illustrated has the advantage that a capacitor with a lower voltage can be used by having the line capacitors compared to the one in FIG 2 illustrated structure can be provided in the Y-connection. Since it is in the in 3 If the illustrated structure is only one unit of the grounding capacitor, there is an advantage that the mounting area can be reduced by considering the insulating distance. In view of these characteristics, the in 2 The structure illustrated is preferably applied to a relatively low voltage system (e.g., a 200 VAC system) and the structure illustrated in FIG 3 The illustrated structure is preferably applied to a system with a higher voltage (e.g. a 400 VAC system).

In the 2 and 3 The illustrated noise filters 18A and 18B primarily reduce the line noise of the common mode component flowing through the ground conductor by means of the excitation inductance and the grounding capacitor of the common mode choke coil, and reduce the line noise of the normal mode component flowing through the power line of each phase by means of the shunt inductance and the line capacitance of the common mode choke.

However, the line noise that the noise filter reduces may need to reduce not only the common mode component and the differential mode component, but also the mode conversion component (from common mode component to differential mode component, or from differential mode component to common mode component).

Next, a problem of mode conversion from the common mode component to the differential mode component that occurs when the in 3 illustrated noise filter 18B is applied.

4th FIG. 11 illustrates an example of a measurement result of the line noise of the inverter to which the in 3 the illustrated noise filter is applied. An undesirable spike that exceeds the norms appears at around 250 kHz. The peak exceeding these norms is as in 5 illustrated caused by parallel resonance.

Next, consider a case where a high-frequency leakage current iL generated in a single phase of a three-phase diode rectifying circuit (T phase in 5 ) flows through the grounding conductor, bypassing the grounding capacitor C _{Y is returned} to the inverter side. In this case, the path in the R phase and the S phase is the path in which the high-frequency leakage current i _L via the network capacitors C _X2-2 and C _X2-3 on the inverter side to the conductive phase (R phase and S- Phase) of the diode rectifier circuit returns, secured. In the T phase, on the other hand, the high-frequency leakage current iL returns via the power lines of the common-mode choke coil Lc, which Line _capacitors C x1-1 to C _X1-3 on the mains side and the R- and S-phase back to the R- and S-phase diodes. At this point, the solid arrows in 5 indicated parallel resonance path (parallel resonance circuit) is formed and a large current flows at the resonance frequency. A large amount of line noise can be observed when part of the resonance current flows to the grid side (AC side). In other words, the common-mode component flowing through the ground conductor is _{converted into a phase voltage} , that is to say, a push-pull _{component, by the line capacitors} C x1-1 to C X1-3 on the network side.

The resonance frequency of the parallel resonance circuit corresponds to the resonance frequency of an in 6th illustrated circuit path A. The inductance component of the parallel resonance circuit here corresponds to the shunt inductance of the common mode choke coil Lc and is determined by connecting as in 7th illustrated measured.

For example, if the capacitance of the line _capacitors C x1-1 to C _X1-3 and C _X2-1 to C _{X2-3 is} 0.15 [µF] and the capacity of the in 7th Shunt inductance measured in the illustrated connection is 8 [µH], then the resonance frequency becomes 252 [kHz], which is almost identical to that in 4th illustrated resonance frequency. In this case there is a method for reducing the resonance frequency outside the specified frequency range. If the capacitances of the line _capacitors C X1-1 to C _X1-3 and C _X2-1 to C _{X2-3 are increased} to 1.0 [µF], the resonance frequency is 97 [kHz]. Therefore, as in 8th illustrates that the standard can be met because the resonance frequency moves as intended to the lower cutoff frequency of 150 [kHz] or less.

In general, the size and excitation inductance of the common mode choke coil are often determined according to the common mode component measurements, and it is difficult to intentionally adjust the shunt inductance. As a result, the capacitance of the multi-line capacitors is increased to make the resonance frequency low.

However, in order to match the resonance frequency only with the capacitance of the line capacitor as described above, it is often necessary to switch to a very large capacitance. Therefore, there may be a problem in increasing the size of the noise filter.

In one embodiment in accordance with the present disclosure, the noise filter reduces the degradation of line noise caused by the resonance of the path that is converted from a common mode component to a differential mode component.

9 Fig. 11 illustrates an example of the structure of the noise filter in this embodiment. The in 9 illustrated noise filter 18C differs from that in FIG 3 illustrated noise filter 18B in that the line _capacitors C X1-1 to C _{X1-3 are} on the network side in the Δ connection.

The noise filter 18C comprises a common mode choke _coil Lc, a plurality of line capacitors C X1-1 to C _X1-3 in the Δ circuit connected to the input side of the common mode choke coil Lc, a plurality of line _capacitors C X2-1 to C _X2-3 in a Y connection , which are connected to the input side of the common mode choke coil Lc, and a grounding capacitor C _{Y connected} between the neutral point 16 the multiple line _capacitors C X2-1 to C _X2-3 and the grounding conductor 17th connected is. The input terminals R, S and T and the input ground terminal E are the input terminal of the noise filter 18C, and the intermediate terminals R ', S' and T 'and the intermediate ground terminal E' are the output terminal of the noise filter 18C.

The common mode choke coil Lc has a structure in which three phases of power lines are wound around a core, each input end of the power lines wound around the core having input terminals R, S and T and each output end having intermediate terminals R ', S' and T ' connected is.

The multi-line capacitors C X1-1 to C _{X1-3 are examples of a plurality of input capacitors connected to the input terminals} R, S and T in a delta connection. The line _capacitor C X1-1 is connected between the R-phase and S-phase power lines, the multi- _{line capacitor C X1-2} is connected between the R-phase and T-phase power lines, and the multi-line _{capacitor C is X1-3} connected between the power lines of the S-phase and the T-phase.

The plurality of line _capacitors C X2-1 to C _X2-3 are examples of a plurality of output capacitors and are connected in a star connection to the intermediate connections R ', S' and T '. The line _capacitor C X2-1 is between the power line of the R phase and the star point 16 connected, the line _capacitor C X2-2 is between the power line of the S-phase and the star point 16 connected and the line _capacitor C X2-3 is between the power line of the T-phase and the neutral point 16 tied together.

A ground capacitor C _Y is between the zero point 16 and the grounding conductor 17th tied together. The grounding conductor 17th is an example of the ground and connects the input ground terminal E and the intermediate earth connection E '. Incidentally, the number of ground connections of the noise filter can be one or more, and in this example there are two (the input ground connection E and the intermediate ground connection E ').

The parallel resonance of the aforementioned mode-converted component of the noise filter 18C of FIG 9 is through an in 10 illustrated circuit path B determined by the solid line arrow. 10 FIG. 11 illustrates an example of a circuit path of the parallel resonance circuit of the in 9 illustrated noise filter 18C. _{The parallel resonance circuit} is formed by a common mode choke coil Lc, a plurality of link capacitors C X1-1 to C _X1-3 , a plurality of _{link capacitors} C X2-1 to C _X2-3, and a grounding _{capacitor C Y.}

As in 10 As illustrated, the path B runs through two line _capacitors C X1-1 and C _X1-2 connected in parallel on the network side. _{Accordingly, the synthesized capacitance of the resonance path} on the network side is larger than the mode in which the Y circuit is formed by the line _capacitors C X1-1 to C X1-3 on the network side. For example, if each capacitance (C _X1-1 to C _X1-3 , which form the Δ circuit, C _X2-1 to C X2-3, which form the Y circuit) of a plurality of line _{capacitors is 0.15 [µF],} and if the shunt inductance caused by the in 7th the illustrated connection is measured, 8 [µH], the resonance frequency is 205 [kHz], whereby the resonance frequency is compared to 252 [kHz] of the standards mode ( 3 ), which includes only the Y circuits, is significantly reduced.

The standards can be met by changing the resonance frequency of the parallel resonance circuit with a circuit path B as in 10 illustrated is set to the standard lower limit frequency of 150 [kHz] or lower.

11th is an example of a simplified simulation result of the noise terminal voltage in the cases of 4th (Standards mode ( 3 )), 8th (moving to 150 kHz or lower) and 9 (line-side Δ switching). According to 11th A simulation result shows that the tendencies coincide at around 1 [MHz] or lower. It can be confirmed that the resonance frequency changes as described above.

In addition, under the condition that the standards mode and the line-side Δ switching are used, the measured value clearly exceeds the quasi-peak value control value (solid line) of the line noise limit value (IEC61800-3) of the variable-speed motor drive system (PDS). On the other hand, under the condition that the resonance frequency is shifted to 150 kHz or lower, it can be expected that the measured value also satisfies the mean control value (broken lines). That is, the simulation results confirm that the behavior of the observed line noise can be reproduced even if there are some errors in the absolute values of the peak values of the resonance frequencies.

Accordingly, only the in 9 illustrated Δ circuit of the line capacitors on the network side, the resonance frequency of the components that convert from the common mode component to the differential mode component can be made lower than in the case in which the Y circuit of the line capacitors has the same capacitance.

As a result, the noise filter 18C can be downsized because the line capacitance required to lower the resonance frequency can be reduced until the standards are met. Since the noise filter 18C is made with the line capacitors in the Y-connection on the inverter side, it is unlikely that the problem of the isolation distance from the ground potential will arise.

As described above, when the line capacitors are in the Δ connection, a component having a higher voltage resistance must be used as compared with the case where the line capacitors are in the Y connection. When filter substrates with the same capacity of the 200 V system and the 400 V system are used together, the Y connection was often required in the past. In the case of the noise filter in an embodiment according to the present disclosure, however, it is preferable to provide an installation pattern on the same substrate that enables both the Y-connection and the Δ-connection for the line capacitors on the line side of the filter substrate. That is, the structure of the noise filter can be rearranged relatively easily by using the Δ circuit in a case where the noise filter is only applied to the 200 V system.

The resonance frequency of the component converted from the common mode component to the differential mode component is determined by an in 10 illustrated circuit path B is determined. Even at the same resonance frequency, the line noise flowing from the grid side can be reduced if the current returning to the intermediate connections R 'and S' _{via the line capacitors} C X2-1 and C _{X2-2 on the inverter side is made larger than that via C X1 -1} to C _X1-3 on the inverter side to the intermediate connections R 'and S' returning stream. That is, each capacitance of the _{multiline capacitors} C X1-1 to C _X1-3 on the grid side can be made smaller than each capacitance of the _{multiline capacitors} C X2-1 to C _X2-3 on the inverter side.

In particular, the ratio of the capacitances C to C _{X1-1 X1-3} between the multiple line capacitors C is _{X2-1 X2-3} -C-C _X2-3 between the multiple line capacitors C _X2-1 on the inverter side to 1: 3 or more effective. In other words, each capacitance of the multiple capacitors C _X2-1 to C _X2-3 is more effective when it is more than three times the capacitance of each of the multiple line _capacitors C X1-1 to C _X1-3 . More preferably, it is more effective that each capacitance of the multi-line _capacitors C X2-1 to C _X2-3 is five to ten times or less than each capacitance of the multi-line _capacitors C X1-1 to C _X1-3 .

Next, the difference in reducing effect due to the difference in circuit constants will be described based on the simulation results.

12th illustrates an example of a simulation result in which the capacitance ratio between line-side and inverter-side line capacitors is changed while the resonance frequency is compared to that in FIG 11th illustrated state of the standards is kept almost constant. 13th FIG. 14 is an enlarged view of a portion of the frequency range of FIG 12th . When the resonance peak is checked at around 250 [kHz], it can be confirmed that the resonance peak decreases as the ratio increases. When the ratio of 1: 3 or higher is provided, a reduction effect of about 10 [dB] or higher can be obtained, and it can be confirmed that the peak can be reduced more effectively.

14th illustrates an example of the simulation result in which the ratio is increased by increasing the capacities of the line _capacitors C X2-1 to C _X2-3 on the inverter side, without the capacities of the line capacitors on the grid side (0.15 [µF]) compared to the in 11th to change the illustrated standard conditions. 15th FIG. 13 is an enlarged view of a portion of the FIG 14th illustrated frequency range. The resonance frequency at the in 15th The illustrated resonance peak shifts in the direction of a lower value, while the ratio between the grid-side and inverter-side line capacitors increases. The amount of reduction in the resonance peak is also larger than that in 13th . It is assumed that the current flowing into the line capacitors C X2-1 to C _X2-3 on the inverter side has increased, so that the line _{noise from flowing out to the grid side is suppressed.}

16 _{Fig. 10} illustrates an example of the simulation result in which the ratio is increased by reducing the capacities of the line capacitors C X1-1 to C _X1-3 on the grid side, excluding the capacitance of the line capacitors on the inverter side (0.15 [µF]) the norm condition of 11th to change. 17th FIG. 13 is an enlarged view of a portion of the FIG 16 illustrated frequency range. The resonance frequency at the resonance peak of 17th shifts in a higher direction, while each capacitance of the multiline capacitors on the grid side becomes smaller than each capacitance of the multiline capacitors on the inverter side. The amount of reduction in the resonance peaks is also greater than in 13th . The capacitance of the multi-line capacitors can be made smaller than the standard conditions.

18th illustrates an example of a simulation result in which the ratio is increased by reducing the capacities of the line _capacitors C X1-1 to C _X1-3 on the network side with standards to a state in which the capacitance of all line capacitors is 0.3 [µF ] is set. 19th FIG. 13 is an enlarged view of a portion of the FIG 18th illustrated frequency range. Similar to in 17th the resonance frequency moves at the in 19th illustrated resonance peak upward, while the capacitance of each of the multiline capacitors on the grid side becomes smaller than the capacitance of each of the multiline capacitors on the inverter side. If each capacitance of the multi-line capacitors on the line side is 1/10 (0.03 [µF]), the resonance frequency is 500 [kHz] or less. Therefore, it can be confirmed that the resonance frequency can be sufficiently reduced to the quasi-peak control value.

As described above, in the noise filter 18C, the capacitances of the line capacitors C _X1-1 to C _X1-3 in the line-side inverters are selected to be smaller than the capacitances of the line capacitors C _X2-1 to C _X2-3 on the inverter side. As a result, the components that convert the common mode component into the differential mode component can be appropriately reduced. As a result, the standards are met and the filter is miniaturized and made compact.

Although the noise filters and power converters have been described according to the embodiments, the present disclosure is not limited to the embodiments described above limited. Various modifications and modifications such as combinations and substitutions with some or all of the other embodiments are possible within the scope of the present invention.

List of reference symbols

16

Zero point

17th

Grounding conductor

18th

Noise filter

19th

Converter part

20th

Inverter part

90

AC power supply

91

Input cable

93

Reference ground plane

94

engine

100

Motor drive system

200

Inverter

300

Power converter

LC

Common mode choke coil

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• JP H722886 [0004]
• JP 2014216997 [0004]

Claims (5)

Noise filter comprising: a common mode choke coil; a plurality of input capacitors in a delta connection, the plurality of input capacitors being provided on an input side of the common mode choke coil; a plurality of output capacitors in a star connection, the plurality of output capacitors being provided on the output side of the common mode choke coil; and a ground capacitor connected between the neutral points of the plurality of output capacitors and a ground. Noise filter after Claim 1 , wherein a resonance frequency of a parallel resonance circuit formed by the common mode choke coil, the plurality of input capacitors, the plurality of output capacitors, and the grounding capacitor is less than 150 kHz. Noise filter according to the Claims 1 or 2 wherein each capacitance of the plurality of output capacitors is greater than each capacitance of the plurality of input capacitors and is less than or equal to ten times each capacitance of the plurality of input capacitors. Noise filter after Claim 3 wherein each capacitance of the plurality of output capacitors is three times or more than each capacitance of the plurality of input capacitors. A power converter comprising: the noise filter according to one of the Claims 1 until 4th ; and an inverter connected to the noise filter, the inverter including a converter part connected to the noise filter and an inverter part connected to the converter part.

Images