Noise filter, power conversion system, and management system

Abstract

This noise filter (100) is provided in either a circuit (2) that connects an AC or DC power supply (1) to a power conversion device (80) that converts power output from the power supply (1) to AC or DC power, or a circuit (11) that connects the power conversion device (80) to a load, and is provided with: a noise detection unit (12) that detects noise generated by the noise detection unit (12); a common-mode noise detection unit that detects common-mode noise generated during operation of the power conversion device (80); a cancellation signal generation unit (16) that generates a cancellation signal for cancelling the common-mode noise; a cancel signal injection unit (14) that injects a cancel signal into the circuits (2, 11); and an abnormality detection unit (17) that outputs an abnormality detection signal when it is detected that the cancellation signal is abnormal, and the noise filter (100) executes an abnormality processing sequence on the basis of the abnormality detection signal.

Description

Technical Field

[0001] The present disclosure relates to a noise filter, a power conversion system, and a management system. Background Art

[0002] A power conversion device is known that converts input power from a power supply into any DC power or AC power and supplies it to a load. Such a power conversion device performs power conversion by opening and closing a plurality of switching elements connected in a bridge manner, but high-frequency noise is generated as the switching elements operate. This high-frequency noise passes through the ground potential via parasitic capacitance and the like, and becomes the cause of common-mode noise flowing through the power supply or the load. Therefore, a structure is known in which a noise filter is provided in a circuit between a power supply and a power conversion device, or in a circuit between a power conversion device and a load in order to suppress such common-mode noise.

[0003] As one of the noise filters, there is an active noise filter. For example, in the active noise filter described in Patent Document 1, the common mode voltage is detected via the grounding capacitor of the circuit connected between the AC power supply and the rectifier, and a cancellation voltage having the same magnitude and opposite polarity as the detected common mode voltage is generated by a cancellation voltage source, so that the cancellation voltage is superimposed between the connection point between the AC power supply and the grounding capacitor in the circuit. In this way, the active noise filter described in Patent Document 1 injects the cancellation voltage for canceling the common mode voltage as the common mode noise into the circuit as a noise cancellation signal (hereinafter referred to as the cancellation signal).

[0004] Patent Document 1: Japanese Patent Application Publication No. 2010-57268 Summary of the invention

[0005] Problem that the invention aims to solve

[0006] During the operation of the active noise filter, the control characteristics of the active noise filter may change due to environmental factors or time factors, etc. In the active noise filter described in Patent Document 1, when a change in the control characteristics that was not originally intended occurs, there is a concern that an abnormal cancellation signal may be generated, such as oscillation of the cancellation signal injected into the circuit due to loss of control margin (gain margin and phase margin) or excessive compensation amount in noise cancellation.

[0007] When an abnormal cancellation signal is injected into the circuit, not only will the common mode noise not be eliminated or cancelled, but the cancellation signal itself may also cause problems.

[0008] The present disclosure has been made to solve the above-mentioned problems, and an object of the present disclosure is to provide a noise filter, a power conversion system, and a management system that can achieve high reliability.

[0009] Solutions for solving problems

[0010] The noise filter disclosed in the present application is a noise filter provided in a circuit that connects an AC or DC power supply to a power conversion device that converts power output from the AC or DC power supply into AC or DC power, and a circuit that connects the power conversion device to a load, and is characterized by comprising:

[0011] a noise detection unit for detecting common mode noise generated when the power conversion device operates;

[0012] a cancellation signal generating unit, which generates a cancellation signal for canceling the common mode noise;

[0013] a cancellation signal injection unit, which injects the cancellation signal into the circuit; and

[0014] The abnormality detection unit outputs an abnormality detection signal when detecting that the elimination signal is abnormal.

[0015] Based on the anomaly detection signal, an anomaly handling sequence is executed.

[0016] The power conversion system disclosed in the present application comprises:

[0017] A power conversion device converts the power output from the AC or DC power source into AC or DC power; and

[0018] The noise filter mentioned above.

[0019] The management system disclosed in this application has:

[0020] A power conversion device converts the power output from an AC or DC power source into AC or DC power;

[0021] The noise filter further comprises a communication unit connected to the cancellation signal output unit constituting the noise filter and transmitting data to the outside; and

[0022] The management device includes a database storing the data transmitted from the communication unit and a data analysis unit analyzing the data.

[0023] Effects of the Invention

[0024] According to the noise filter and the power conversion system disclosed in the present application, even when an abnormality occurs in the cancellation signal, the system operates stably, thereby achieving an effect of achieving high reliability.

[0025] According to the management system disclosed in the present application, there is a management device that uses data sent from the power conversion system to perform data analysis, so it is possible to quickly respond to the cause of the abnormality, thereby further improving the reliability of the power conversion system and improving the maintainability of the management and maintenance of the power conversion system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 1 is a system configuration diagram showing a power conversion system according to the first embodiment.

[0027] Figure 2 This is a circuit configuration diagram showing a power conversion device constituting a part of the power conversion system according to the first embodiment.

[0028] Figure 3 This is a diagram for explaining common mode noise generated in the power conversion system according to the first embodiment.

[0029] Figure 4 It is a diagram showing the configuration of a noise filter and a power conversion system according to the first embodiment.

[0030] Figure 5A 1 is a diagram showing a configuration of an example of a noise detection unit in the noise filter according to the first embodiment.

[0031] Figure 5B 1 is a diagram showing a configuration of an example of a noise detection unit in the noise filter according to the first embodiment.

[0032] Figure 6 This is a diagram showing a configuration of an example of a cancellation signal generation unit in the noise filter according to the first embodiment.

[0033] Figure 7 1 is a diagram showing a configuration of an example of an abnormality detection unit in the noise filter according to the first embodiment.

[0034] Figure 8 1 is a diagram showing a configuration of an example of a feature quantity detection unit in the noise filter according to the first embodiment.

[0035] Fig. 9 1 is a diagram showing a configuration of an example of a feature quantity comparison unit in the noise filter according to the first embodiment.

[0036] Fig.10 1 is a diagram showing the configuration of a cancellation signal injection unit in the noise filter according to the first embodiment.

[0037] Fig.11 This is an example of a hardware configuration diagram for realizing the noise filter and the power conversion system according to the first embodiment.

[0038] Fig. 12A This is a diagram for explaining the behavior of the injection transformer in the noise filter according to the first embodiment during normal operation.

[0039] Fig. 12B This is a diagram showing the relationship between the impedance of the injection transformer and the frequency during normal operation in the noise filter according to the first embodiment.

[0040] Fig.13A This is a diagram for explaining the behavior of the noise filter according to the first embodiment during the protection operation of the injection transformer.

[0041] Fig. 13B This is a diagram showing the relationship between impedance and frequency during protection operation of the injection transformer in the noise filter according to the first embodiment.

[0042] Fig.14 This is a diagram showing a configuration of an example of a protection circuit in the noise filter according to the first embodiment.

[0043] Fig.15 : is a diagram showing the structure of a noise filter according to the second embodiment.

[0044] Fig.16 This is a configuration diagram showing another configuration example of the noise filter according to the second embodiment.

[0045] Fig.17 This is a diagram for explaining an example of a process of canceling an abnormality detection signal in a signal output unit in a noise filter according to the second embodiment.

[0046] Fig.18 It is a diagram showing the configuration of a power conversion system according to the third embodiment.

[0047] Fig.19 This is a diagram for explaining common mode noise generated in the power conversion system according to the third embodiment.

[0048] Fig. 20 : is a diagram showing the structure of a noise filter according to the third embodiment.

[0049] Fig.21 :Regarding the control response of the main circuit of the noise filter, Fig.21 A is a diagram showing the control response when there is no filter unit. Fig.21 B is a graph showing the pass characteristics of the filter unit. Fig.21 C is a diagram showing a control response when a filter unit is present.

[0050] Fig. 22 : Regarding the control response of the noise filter, Fig. 22A is a graph showing gain characteristics, Fig. 22 B is a graph showing phase characteristics.

[0051] Fig.23 : Regarding the control response of the noise filter, Fig.23 A is a diagram showing changes in gain characteristics when changes occur in control characteristics due to abnormality. Fig.23 B is a diagram showing a change in phase characteristics when a change occurs in control characteristics due to an abnormality.

[0052] Fig.24 It is a diagram showing an abnormal output waveform of a cancellation signal output portion of a noise filter.

[0053] Fig.25 : Fig.25 A is a diagram showing the waveform of the common mode voltage in normal conditions. Fig.25 B is a diagram showing the waveform of the common mode current under normal conditions. Fig.25 C is a diagram showing the waveform of the output voltage of the cancellation signal in a normal state in the noise filter. Fig.25 D is a diagram showing a waveform of an output current of a cancellation signal in a normal state of the noise filter.

[0054] Fig.26 : Fig.26 A is a diagram showing the waveform of the common mode voltage in an abnormal situation. Fig.26 B is a diagram showing the waveform of the common mode current in an abnormal situation. Fig.26 C is a diagram showing the waveform of the output voltage of the cancellation signal in an abnormal situation. Fig.26 D is a diagram showing the waveform of the output current of the cancellation signal in an abnormal state.

[0055] Fig. 27 It is a diagram showing the configuration of a noise filter and a power conversion system according to a fourth embodiment.

[0056] Fig.28 This is a structural diagram showing the management system involved in Implementation Example 5.

[0057] Fig.29 It is a diagram showing the configuration of a noise filter and a power conversion system according to the fifth embodiment.

[0058] Fig.30 It is a diagram showing the configuration of a noise filter and a power conversion system according to the sixth embodiment. DETAILED DESCRIPTION

[0059] Hereinafter, the noise filter in each embodiment of the present application will be described in detail with reference to the drawings. In addition, the same reference numerals in each figure represent the same or corresponding parts.

[0060] Implementation method 1.

[0061] based on Figures 1 to 11 The noise filter 100 and the power conversion system 500 according to the first embodiment will be described. Figure 1 1 is a system configuration diagram showing a power conversion system 500 according to Embodiment 1. Figure 2 1 is a circuit configuration diagram showing a power conversion device 80 constituting a part of a power conversion system 500 according to the first embodiment.

[0062] The power conversion system 500 includes: a power conversion device 80, which is arranged between an AC power source 1 and a load 90, and converts input power from the AC power source 1 into any DC power or AC power; a load 90, to which any DC power or AC power is supplied from the power conversion device 80; and a noise filter 100, which is provided in a circuit 11 connecting the power conversion device 80 and the load 90. The input power from the AC power source 1 is input to the power conversion device 80 via a circuit 2. In addition, the AC power source 1 is only an example of a power source, and a DC power source may be substituted for the AC power source 1. Similarly, in each embodiment described later, a DC power source may be applied instead of the AC power source 1.

[0063] The power conversion device 80 converts the input power input from the AC power supply 1 into the power required for driving the load 90 and outputs it. In the first embodiment, the noise filter 100 is arranged between the power conversion device 80 and the load 90, but it can also be provided in the circuit 2 connecting the AC power supply 1 and the power conversion device 80.

[0064] The power conversion device 80 is, for example, Figure 2 The 2-level three-phase inverter shown in FIG. 1 is a 2-level three-phase inverter. That is, two semiconductor switches 82a and 82b connected in series form an upper and lower arm 82. In addition, two semiconductor switches 83a and 83b connected in series form an upper and lower arm 83. Furthermore, two semiconductor switches 84a and 84b connected in series form an upper and lower arm 84. A DC power supply 81 is connected to the three upper and lower arms 82, 83, and 84.

[0065] The DC power supply 81 is composed of a converter or the like that converts the AC input power input from the AC power supply 1 into a DC power supply. The midpoints of the three upper and lower arms 82, 83, and 84 are connected to the inverter output terminal 85. By switching the six semiconductor switches 82a, 82b, 83a, 83b, 84a, and 84b, AC power is output to the inverter output terminal 85. At this time, the output potential of the inverter output terminal 85 becomes the potential of either the positive voltage or the negative voltage of the DC power supply 81. Therefore, the common mode voltage of the power conversion device 80 becomes a non-zero constant voltage.

[0066] Figure 3 This is a diagram illustrating common mode noise generated in power conversion system 500 according to Embodiment 1, and shows a common mode equivalent circuit. In power conversion system 500 , AC power supply 1 and load 90 are connected to the ground via ground line 3 independently of circuit 11 described above.

[0067] The noise filter 100 is provided with a grounding capacitor 15 (not shown) whose one end is connected to the ground line 3. In addition, there are parasitic capacitances 86 and 91 between the power conversion device 80 and the ground line 3 and between the load 90 and the ground line 3, respectively. In the power conversion system 500, the common mode voltage Vcn generated in the power conversion device 80 is applied to the common mode loop via the parasitic capacitances 86, 91 and the ground line 3, so the common mode current (common mode noise CN) flows along the ground line 3. Figure 3 Flows in the direction indicated by the arrow.

[0068] Figure 4 1 is a diagram showing the configuration of a noise filter 100 and a power conversion system 500 according to Embodiment 1. The noise filter 100 is inserted between the power conversion device 80 and the load 90 . That is, the noise filter 100 is provided in the circuit 11 connecting the power conversion device 80 and the load 90 .

[0069] The noise filter 100 comprises: a noise detection unit 12 connected to the circuit 2; a cancellation signal output unit 13, which outputs a signal according to the common mode noise CN detected by the noise detection unit 12 (in Figure 4 The elimination signal CS is generated and outputted by the elimination signal injection unit 14, which is arranged on the circuit 11 closer to the output end than the noise detection unit 12, that is, closer to the load 90 side, and injects the elimination signal CS outputted from the elimination signal output unit 13 into the circuit 11; and the control power supply 19 supplies the power for generating and injecting the elimination signal CS to the elimination signal output unit 13.

[0070] The elimination signal output unit 13 includes: an elimination signal generating unit 16, which amplifies the noise detection signal DS output from the noise detecting unit 12; an abnormality detecting unit 17, which can send the output from the elimination signal generating unit 16 as an elimination signal CS to the elimination signal injecting unit 14, and output an abnormality detection signal AS based on the output voltage of the elimination signal generating unit 16.

[0071] The elimination signal output unit 13 further includes a protection circuit 18, which is inserted between the abnormality detection unit 17 and the elimination signal injection unit 14 and is an example of a connection disconnection unit that can disconnect the injection of the elimination signal. That is, the noise filter 100 involved in the first embodiment includes a connection disconnection unit that disconnects the connection between the elimination signal output unit 13 and the elimination signal injection unit 14 as a protection unit for suppressing the injection of the abnormal elimination signal CS into the circuit 11. In the first embodiment, the protection circuit 18 is applied as one form of the connection disconnection unit.

[0072] In the first embodiment, the abnormality detection unit 17 is composed of elements and circuits that have little effect on the output characteristics, so the output of the elimination signal generation unit 16 is almost the same as the elimination signal CS. Therefore, in the following description, unless otherwise specified, the output of the elimination signal generation unit 16 is referred to as the elimination signal CS.

[0073] In addition, a filter unit (not shown) capable of adjusting the characteristics of the elimination signal CS may be provided between the noise detection unit 12 and the elimination signal generation unit 16, or between the elimination signal generation unit 16 and the abnormality detection unit 17. When the filter unit is provided between the noise detection unit 12 and the elimination signal generation unit 16, the elimination signal generation unit 16 amplifies the noise detection signal DS adjusted by the filter unit to generate the elimination signal CS. In this case, the characteristics of the elimination signal CS are also adjusted by adjusting the noise detection signal DS.

[0074] The filter section may be an input filter circuit that adjusts the attenuation characteristics of the noise filter 100 by reducing the gain of a specific frequency band, etc. Specifically, an analog filter such as a high-pass filter, a low-pass filter, or a notch filter composed of resistors and capacitors may be used.

[0075] In the noise filter 100, a grounding capacitor 15 (not shown) connected between the circuit 11 and the ground line 3 is provided. The noise detection unit 12, the cancellation signal injection unit 14, and the grounding capacitor 15 constitute the main circuit unit 101 of the noise filter 100. The control characteristics of the noise filter 100 largely depend on the main circuit unit 101. The inductance value of the main circuit unit 101 is the sum of the inductance value of the common mode transformer constituting the noise detection unit 12 and the inductance value of the common mode transformer constituting the cancellation signal injection unit 14. In addition, the capacitance value of the main circuit unit 101 is the capacitance value of the grounding capacitor 15. In addition, in the above description, the case where the load 90 is included inside the power conversion system 500 is described, but it is not limited to the above structure. That is, when the load 90 is connected to the outside of the power conversion system 500, the main circuit unit 101 is also composed of the parasitic capacitance 91 that functions as the common mode impedance of the load 90. The same is true for the main circuit unit in each embodiment described later. The details of the control characteristics of the main circuit unit 101 will be described later.

[0076] Figure 5A and Figure 5B 1 is a diagram showing a configuration of an example of the noise detection unit 12 in the noise filter 100 according to the first embodiment. Figure 5B As shown in FIG. 1 , the noise detection unit 12 is composed of a capacitor network. Hereinafter, the plurality of capacitors constituting the noise detection unit 12 are referred to as a detection capacitor network 12n.

[0077] The detection capacitor network 12n includes a detection capacitor 12a connected to the U-phase power line in the circuit 11 connecting the power conversion device 80 and the load 90, a detection capacitor 12b connected to the V-phase power line, a detection capacitor 12c connected to the W-phase power line, and a detection capacitor 12e provided between the star point 12f connected to the detection capacitors 12a, 12b, 12c, which is not the other terminal of the power line, and the ground line 3. Figure 5B As shown, the detection capacitor network 12n operates as a noise detector that divides and detects the common mode voltage.

[0078] The detection ratio of the common mode voltage in the detection capacitor network 12n depends on the ratio of the parallel impedance of the detection capacitors 12a, 12b, 12c to the impedance of the detection capacitor 12e. Therefore, in the noise detection unit 12, the common mode noise CN applied to the detection capacitor network 12n generates a noise detection signal DS at both ends of the T-phase winding 12d.

[0079] Both ends of the T-phase winding 12d are connected to the elimination signal generating unit 16. That is, the noise detection signal DS generated at both ends of the T-phase winding 12d is sent to the elimination signal generating unit 16. Figure 3The common-mode equivalent circuit shown has sufficiently high impedance compared to the parasitic capacitance 86 of the inverter and the parasitic capacitance 91 of the load 90 , and therefore has relatively high impedance to ground, so that the leakage current of the power conversion device 80 is not adversely affected.

[0080] Figure 6 1 is a block diagram showing an example of the cancellation signal generating unit 16 in the noise filter 100 according to the first embodiment. The cancellation signal generating unit 16 includes an input resistor 16a, an operational amplifier 16b, and a feedback resistor 16c. The inverting input terminal of the operational amplifier 16b is connected to the input terminal side of the cancellation signal generating unit 16 via the input resistor 16a ( Figure 6 on the left side of the ).

[0081] The inverting input terminal of the operational amplifier 16b is connected to the output terminal of the operational amplifier 16b via the feedback resistor 16c. The non-inverting input terminal of the operational amplifier 16b is grounded. Figure 6 The elimination signal generating unit 16 shown in the figure is an inverting amplifier circuit using an operational amplifier 16b, but may be a non-inverting amplifier circuit. The elimination signal generating unit 16 amplifies the noise detection signal DS at an amplification factor provided by the ratio of the resistance value of the input resistor 16a to the resistance value of the feedback resistor 16c to generate the elimination signal CS, and outputs the elimination signal CS.

[0082] Figure 7 1 is a block diagram showing an example of the abnormality detection unit 17 in the noise filter 100 according to the first embodiment. The abnormality detection unit 17 includes: a feature quantity detection unit 171 that uses the output voltage of the cancellation signal CS to output a feature quantity signal CV for detecting an abnormality; and a feature quantity comparison unit 172 that generates and outputs an abnormality detection signal AS by performing a predetermined operation on the feature quantity signal CV. In the first embodiment, when an abnormality of the noise filter 100 is detected, the abnormality detection signal AS is output as ON, and when no abnormality is detected, the abnormality detection signal AS is output as OFF.

[0083] Figure 8 1 is a block diagram showing an example of a feature quantity detection unit 171 as a part of the abnormality detection unit 17 in the noise filter 100 according to the first embodiment. The feature quantity detection unit 171 generates and outputs a feature quantity signal CV based on the voltage value of the output voltage of the cancellation signal CS. The feature quantity signal CV is a signal indicating a feature quantity for abnormality detection. Various values ​​can be conceived as to what kind of value is used as the feature quantity.

[0084] Figure 8The example of the feature quantity detection unit 171 shown in FIG. 1 illustrates the configuration of the feature quantity detection unit 171 when the voltage average value of the output voltage of the cancellation signal CS is used as the feature quantity. Figure 8 As shown, the characteristic quantity detection unit 171 is composed of a low-pass filter composed of a capacitor 171k and a resistor 171l connected to the output side of an absolute value detection circuit composed of operational amplifiers 171a, 171b, resistors 171c, 171d, 171e, 171h, 171i, 171j, 171m and diodes 171f, 171g.

[0085] In the feature quantity detection unit 171, an input terminal (not shown) is connected to an output terminal (not shown) of the elimination signal generation unit 16, and an output voltage as the elimination signal CS output by the elimination signal generation unit 16 is input as an input signal to the feature quantity detection unit 171. This input signal is input to the above-mentioned absolute value detection circuit, whereby the absolute value of the voltage value of the output voltage as the elimination signal CS is output from the absolute value detection circuit.

[0086] The output of the absolute value detection circuit is averaged by the low-pass filter, so the output from the low-pass filter is the voltage average value of the output voltage of the elimination signal CS. That is, the output of the feature quantity detection unit 171 becomes the voltage average value of the output voltage of the elimination signal CS. The output of the feature quantity detection unit 171 is output to the feature quantity comparison unit 172 as the feature quantity signal CV. In addition, the circuit of the feature quantity detection unit 171 is not limited to Figure 8 The example shown can be freely configured without departing from the gist of the present application.

[0087] Fig. 9 1 is a structural diagram showing an example of a feature quantity comparison unit 172 as a part of the abnormality detection unit 17 in the noise filter 100 according to Embodiment 1. The feature quantity comparison unit 172 generates an abnormality detection signal AS by performing a predetermined operation on the feature quantity signal CV output by the feature quantity detection unit 171, and outputs the generated abnormality detection signal AS.

[0088] As the noise filter 100 according to the first embodiment, Fig. 9 FIG. 1 shows an example of a feature quantity comparison unit 172 that is formed using a comparator circuit that compares a feature quantity signal CV with a preset threshold voltage. The feature quantity comparison unit 172 includes a comparator 172a, a DC voltage source 172b, and a pull-up resistor 172c. The inverting input terminal of the comparator 172a is connected to the input terminal side of the feature quantity comparison unit 172 ( Fig. 9The non-inverting input terminal of the comparator 172a is connected to the positive electrode of the DC voltage source 172b. The negative electrode of the DC voltage source 172b is grounded. The output terminal of the comparator 172a is connected to the output terminal side of the characteristic quantity comparison unit 172. A pull-up resistor 172c is connected between the output terminal of the comparator 172a and the output terminal of the characteristic quantity comparison unit 172.

[0089] When the characteristic quantity signal CV is input as an input signal to the characteristic quantity comparison unit 172, the voltage of the characteristic quantity signal CV is compared with the voltage of the DC voltage source 172b, and the abnormality detection signal AS is output according to the comparison result. Specifically, for example, when the voltage of the characteristic quantity signal CV is greater than the voltage of the DC voltage source 172b, it is considered that an abnormality is detected and the abnormality detection signal AS is output as ON. In this case, the voltage value of the DC voltage source 172b becomes the threshold voltage for determining whether there is an abnormality. In addition, the circuit constituting the characteristic quantity comparison unit 172 is not limited to Fig. 9 The example shown can be freely configured without departing from the gist of the present application.

[0090] Fig.10 1 is a structural diagram showing the elimination signal injection unit 14 in the noise filter 100 involved in the first embodiment. The elimination signal injection unit 14 is composed of a common mode transformer. Hereinafter, the common mode transformer constituting the elimination signal injection unit 14 is referred to as an injection transformer 14g. The injection transformer 14g includes an R-phase winding 14a wound on the R-phase power line, an S-phase winding 14b wound on the S-phase power line, a T-phase winding 14c wound on the T-phase power line, and an injection winding 14d in the circuit 11. The R-phase winding 14a, the S-phase winding 14b, and the T-phase winding 14c are wound in the same phase. The injection transformer 14g constructed as above has a high inductance value only for the common mode and functions as a common mode choke coil.

[0091] In the elimination signal injection unit 14 formed by the injection transformer 14g as described above, when the elimination signal CS is input to both ends of the injection winding 14d, an induced voltage V for eliminating the common mode noise CN is induced in the R-phase winding 14a, the S-phase winding 14b and the T-phase winding 14c through the elimination signal CS input to the injection winding 14d.

[0092] The hardware structure of the control system according to the first embodiment may also be as follows: Figure 8 and Fig. 9 Although the present invention is constituted by an analog circuit as shown, an example different from the analog circuit is described here.

[0093] Fig.111 is an example of a hardware configuration diagram for realizing the control system of the noise filter 100 according to Embodiment 1. In addition, the "control system" here refers to the overall control of the noise filter 100, especially including the control power supply 19. The control system of the noise filter 100 according to Embodiment 1 is mainly composed of a processor 71, a memory 72 as a main storage device, an auxiliary storage device 73, and an interface 74.

[0094] The processor 71 is constituted by, for example, a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), or the like.

[0095] The memory 72 is composed of a volatile storage device such as a random access memory, and the auxiliary storage device 73 is composed of a non-volatile storage device such as a flash memory or a hard disk. A predetermined program executed by the processor 71 is stored in the auxiliary storage device 73. The processor 71 reads and executes the program as appropriate to perform various calculations. At this time, the above-mentioned predetermined program is temporarily stored in the memory 72 from the auxiliary storage device 73, and the processor 71 reads the program from the memory 72.

[0096] The various calculation processes of the control system of the noise filter 100 and the power conversion system 500 according to the first embodiment are realized by executing a predetermined program by the processor 71 as described above. The result of the calculation process of the processor 71 is temporarily stored in the memory 72, and is stored in the auxiliary storage device 73 according to the purpose of the calculation process executed. In this way, as a method of realizing the control system, it can be composed of an analog circuit or a digital circuit.

[0097] The following describes problems that occur when an abnormality occurs in the control device of the noise filter 100, such as a temporary abnormality in the command value of the power conversion device 80 as the controlled device, an abnormality in the winding of the injection coil, or a failure of components such as a transistor and a power supply capacitor as the control circuit.

[0098] In order to stop the noise cancellation operation for the purpose of protecting the control device itself from overcurrent or overvoltage and for the purpose of protecting the controlled device from increased path noise, it is necessary to perform a protection operation of disconnecting the cancellation signal generation unit 16 and the cancellation signal injection unit 14 .

[0099] When the connection between the elimination signal generating unit 16 and the elimination signal injecting unit 14 is disconnected during the protection operation, the low output impedance of the elimination signal generating unit 16 is no longer connected to the auxiliary winding connected to the control circuit side of the injection transformer 14g constituting the elimination signal injecting unit 14, so the insertion impedance of the injection transformer 14g constituting the elimination signal injecting unit 14 as a part of the main circuit unit 101 increases significantly. At this time, the injection transformer 14g acts as a common mode choke coil having the same number of turns as the main winding, and has a large inductance component. As a result, the resonant frequency of the injection transformer 14g and the load common mode capacitance changes.

[0100] If the resonant frequency of the injection transformer 14g and the load common mode capacitor changes, the resonant frequency of the changed common mode path overlaps with the switching frequency of the power conversion device 80 and the frequency band of its higher harmonic frequency, which may increase the common mode noise CN sharply. In order to avoid the increase of the common mode noise CN, it is necessary to select a large number of turns of the injection transformer 14g so that the resonant frequency during the protection action is lower than the switching frequency in advance to increase the inductance component of the injection transformer 14g during the protection action. However, the increase in the number of turns of the injection transformer 14g leads to an increase in the size of the noise filter 100, which is not preferable.

[0101] In addition, other problems that occur during protection operation will be described below from the viewpoint of voltage sharing.

[0102] Regarding the common mode voltage contribution on the load side from the perspective of the power conversion device 80 as a noise source, according to Figure 4 The impedance ratio of the main circuit unit 101 shown is shared. When the connection between the elimination signal generating unit 16 and the elimination signal injecting unit 14 is disconnected, the low output impedance of the elimination signal generating unit 16 is no longer connected to the auxiliary winding of the injection transformer 14g connected to the control circuit side, so the insertion impedance of the injection transformer 14g constituting the elimination signal injecting unit 14 as a part of the main circuit unit 101 is greatly increased.

[0103] As a result of the significant increase in the insertion impedance of the injection transformer 14g, the injection transformer 14g passively shares the Figure 3 The common mode voltage of the common mode noise CN shown in the figure increases significantly, which may cause magnetic saturation of the core. Magnetic saturation causes problems such as heat generation, noise, and vibration, so magnetic saturation must be avoided. On the other hand, the size of the core increases, which leads to an increase in the size of the noise filter 100, which is not preferable.

[0104] use Fig. 12A and Fig. 12B The insertion impedance of the injection transformer 14g constituting the cancellation signal injection unit 14 in a normal noise cancellation operation will be described. Fig. 12A1 is a diagram for explaining the behavior of the injection transformer 14g in the noise filter 100 according to the first embodiment during normal operation. Fig. 12B This is a diagram showing the relationship between the impedance and the frequency of the injection transformer 14g in the noise filter 100 according to the first embodiment during normal operation.

[0105] like Fig. 12A As shown, in a normal noise canceling operation, the canceling signal generating unit 16 having a low output impedance is connected to the injection winding 14d of the injection transformer 14g, and the canceling signal injecting unit 14 injects the canceling signal CS into the circuit 11. In this case, for example, Fig. 12B As shown in FIG. 1 , the insertion impedance in the common mode path of the injection transformer 14g is suppressed to a low value corresponding to the impedance of the amplifier circuit. Therefore, in the frequency band where the common mode noise CN is generated, the resonance frequency of the common mode path is not affected, and the voltage contribution due to the common mode voltage is also low, so the magnetic saturation of the injection transformer 14g caused by the passive voltage contribution based on the impedance does not occur.

[0106] use Fig.13A and Fig. 13B The insertion impedance of the injection transformer 14g constituting the cancellation signal injection unit 14 during the protection operation will be described. Fig.13A 1 is a diagram for explaining the behavior of the injection transformer 14g in the noise filter 100 according to the first embodiment during the protection operation. Fig. 13B 1 is a diagram showing the relationship between the impedance and the frequency during the protection operation of the injection transformer 14g in the noise filter 100 according to the first embodiment. Fig.13A As shown, the injection winding 14d is open-circuited during the protection operation. In other words, a high open-circuit impedance is connected to the injection winding 14d.

[0107] In this case, the injection transformer 14g is, for example, Fig. 13B As shown, since the inductance component of the common mode choke coil corresponding to the core magnetic permeability, magnetic path length, cross-sectional area, and number of turns of the injection transformer 14g is present, it operates as an inductive impedance based on the inductance component, and thus has a great influence on the resonance frequency of the common mode path. In addition, in the frequency band where the common mode noise CN is generated, the voltage contribution from the common mode voltage also increases significantly, and as described above, the magnetic saturation of the injection transformer 14g may occur.

[0108] The abnormality detection unit 17 connected between the elimination signal generation unit 16 and the elimination signal injection unit 14 outputs the abnormality detection signal AS based on one or both of the voltage and the current of the elimination signal CS from the elimination signal generation unit 16 .

[0109] Fig.141 is a diagram showing the structure of the protection circuit 18 of the noise filter 100 according to Embodiment 1. The protection relay 18a constituting the protection circuit 18 can be switched to one of the following two states by switching the relay contact based on the abnormality detection signal AS: a noise elimination operation state in which the elimination signal injection unit 14 is connected to the elimination signal generation unit 16; and a noise elimination stop state in which the elimination signal injection unit 14 is disconnected from the elimination signal generation unit 16 and the elimination signal injection unit 14 is connected to the terminal processing impedance 18b.

[0110] In addition, Fig.14 The protection relay 18a is described as a single relay with a C-type contact, but the protection relay 18a can also be composed of a combination of relays with different A-type contacts and B-type contacts, and the protection relay 18a can be composed of not only a mechanical relay but also a semiconductor relay. The logic of the connected protection relay 18a can be to connect a normally open contact to the elimination signal generating unit 16 and a normally closed contact to the terminal processing impedance 18b, or vice versa.

[0111] have Fig.14 The protection relay 18a shown, when a protection action occurs, appropriately connects the auxiliary winding of the injection transformer 14g constituting the elimination signal injection unit 14 to the terminal processing impedance 18b, thereby suppressing the above-mentioned changes in the resonant frequency of the common mode path, the core magnetic saturation of the injection transformer 14g, and other problems.

[0112] As described above, the characteristic quantity detection unit 171 outputs the voltage effective value of the output voltage of the elimination signal CS as the characteristic quantity signal CV. In addition, the DC voltage source 172b of the characteristic quantity comparison unit 172 becomes the threshold voltage for determining whether the output voltage value of the elimination signal CS is abnormal. That is, the output voltage value of the DC voltage source 172b becomes the threshold voltage Vth of the voltage effective value. Thus, the characteristic quantity comparison unit 172 compares the voltage effective value of the output voltage of the elimination signal CS with the threshold voltage Vth of the voltage effective value.

[0113] When the effective voltage value of the output voltage of the elimination signal CS is greater than the threshold voltage Vth, the output of the comparator 172a becomes high, and the feature quantity comparison unit 172 outputs the abnormality detection signal AS as ON. On the other hand, when the effective voltage value of the output voltage of the elimination signal CS is less than the threshold voltage Vth, the output of the comparator 172a becomes low, and the feature quantity comparison unit 172 outputs the abnormality detection signal AS as OFF.

[0114] In the noise filter 100 according to the first embodiment, the abnormality detection signal AS output from the feature quantity comparison unit 172 is input to the protection circuit 18. Fig.14As shown, the protection circuit 18 is typically composed of a control relay with a C-type contact. Based on the abnormality detection signal AS, the protection circuit 18 disconnects the control power supply 19 from the elimination signal output unit 13, cuts off the connection between the elimination signal output unit 13 and the elimination signal injection unit 14, and connects the elimination signal injection unit 14 to the terminal processing impedance 18b. Through the above-mentioned operation of the elimination signal output unit 13, the injection of the elimination signal CS into the circuit 11 is cut off, so that the elimination signal CS having an abnormal output waveform can be prevented from being injected into the circuit 11, and the resonance frequency change of the common mode path caused by the insertion impedance change of the injection transformer 14g constituting the elimination signal injection unit 14 and the generation of the core magnetic saturation of the injection transformer 14g are suppressed.

[0115] In addition, after the abnormality is detected by the abnormality detection unit 17 and the protection circuit 18 is cut off, for example, when the abnormality detection signal AS is outputted as OFF from the characteristic amount comparison unit 172, the cut off action of the protection circuit 18 is reset, and the generation and injection of the elimination signal CS are restored. For an abnormality pattern in which the cut off action is determined in advance to be a temporary action, a recovery action may be performed after a preset time has passed by using a delay circuit or a counter circuit.

[0116] In addition, in the first embodiment, an example of a circuit using the operational amplifier 16b as the structure of the elimination signal generating unit 16 is shown, but as the structure of the elimination signal generating unit 16, for example, other inverting amplifier circuits or non-inverting amplifier circuits may also be used. In the above description, an example in which the protection circuit 18 performs a cut-off operation according to the abnormality detection signal AS is shown, but the cut-off operation may be further locked, or the cut-off operation may be released by combining with a reset circuit, and an operation other than a simple cut-off operation may be performed by combining with a logic circuit.

[0117] An example of a circuit using an operational amplifier as the structure of the feature quantity detection unit 171 is shown, but for example, a circuit of another structure that achieves the same purpose may be used. An example of using a voltage effective value as the detection quantity used in the feature quantity detection unit 171 is shown, but the feature quantity detection unit 171 may be configured to detect different values ​​such as an instantaneous value and an average value as the feature quantity. In addition, an example of a circuit using a comparator 172a as the structure of the feature quantity comparison unit 172 is shown, but for example, another circuit that achieves the same purpose may be used.

[0118] Furthermore, in the noise filter 100 according to the first embodiment, another common mode choke coil may be connected to the circuit 11 in addition to the noise detection unit 12 and the cancellation signal injection unit 14. The noise detection unit 12 may be configured using a capacitor instead of the common mode transformer.

[0119] As described above, the noise filter 100 according to the first embodiment is characterized in that a process for when an abnormality occurs in the cancellation signal CS, that is, an abnormality processing sequence is executed. Here, the abnormality processing sequence refers to the following sequence.

[0120] (1) Based on the abnormality detection signal AS, the protection circuit 18 is activated to cut off the injection of the elimination signal CS into the circuit, and the two ends of the elimination signal injection unit 14 are connected to the terminal processing impedance 18b;

[0121] (2) A sequence in which the power conversion device 80 determines an abnormality based on the abnormality detection signal AS and changes the switching frequency based on the resonant frequency predicted by the prediction operation unit included in the power conversion device 80;

[0122] (3) A sequence in which the power conversion device 80 determines that an abnormality has occurred based on the abnormality detection signal AS and stops the power conversion device 80 .

[0123] The abnormality processing sequence executes, for example, any one of the above-mentioned sequences (1) to (3). The details of the sequences (2) and (3) will be described in Embodiment 6 to be described later.

[0124] In addition, the sequences listed above are merely examples of exception processing sequences, and other processes that are effective in the event of an exception are of course also included.

[0125] <Effects of Implementation Method 1>

[0126] As described above, according to the noise filter 100 and the power conversion system 500 according to the first embodiment, even when an abnormality occurs in the cancellation signal, the noise filter 100 and the power conversion system 500 can stably operate, thereby achieving an effect of achieving high reliability.

[0127] More specifically, by providing an abnormality detection unit that detects abnormalities in the noise filter and the power conversion device based on the output voltage or output current of the elimination signal and outputs the abnormality detection signal, and a protection circuit that cuts off the connection between the elimination signal injection unit and the elimination signal output unit based on the abnormality detection signal and connects the elimination signal injection unit to the terminal processing impedance, when a certain abnormality that requires protection occurs in the noise filter, the abnormality is detected based on a change in the output voltage or output current of the elimination signal caused by the abnormal state, and the elimination signal is suppressed from being output from the elimination signal output unit to the elimination signal injection unit, thereby preventing the abnormal elimination signal from being injected into the circuit, and by connecting the terminal impedance to the auxiliary winding of the injection transformer constituting the elimination signal injection unit, the increase of common mode noise caused by unexpected resonance caused by the change in the resonant frequency of the common mode path or the generation of magnetic saturation caused by unexpected increase in the insertion impedance of the injection transformer is prevented, thereby achieving an effect of being able to realize a noise filter and a voltage conversion system with high reliability.

[0128] Implementation method 2.

[0129] use Figures 15 to 17 A noise filter 100a according to the second embodiment will be described.

[0130] Fig.15 1 is a block diagram showing a noise filter 100a according to Embodiment 2. The differences from Embodiment 1 are mainly described. In the elimination signal injection unit 14 that injects the elimination signal CS output from the elimination signal output unit 13 into the circuit 11, a plurality of elimination signal injection units are provided and connected in series and parallel. This is because, in particular, when the noise filter 100a is provided between a large-capacity power conversion device and a load, it is sometimes more advantageous to divide the elimination signal injection unit 14 into sections in view of the problem of core installation.

[0131] exist Fig.15 , as an example of a noise filter 100a, shows a configuration in which the number of series-connected cancellation signal injection units is 3 and the number of parallel-connected units is 2. The cancellation signal injection unit 14 includes: cancellation signal injection units 14A1, 14A2, and 14A3, which are provided in a circuit 11A on one side of the parallel configuration; and cancellation signal injection units 14B1, 14B2, and 14B3, which are provided in a circuit 11B on the other side of the parallel configuration.

[0132] The elimination signal output unit 13 is provided for each unit of the number of series-connected elimination signal injection units 14, and the elimination signal output unit 13 includes: a control power supply 19 that supplies power for generating and injecting the elimination signal CS to the elimination signal output unit 13; and a protection circuit 18 that is inserted between the control power supply 19 and the elimination signal output unit 13, and can suppress the elimination signal CS from being injected into the circuits 11A and 11B during protection operation and is connected to the terminal processing impedance 18b. In other words, the noise filter 100a includes the same number of elimination signal output units 13 as the number of series-connected elimination signal injection units 14.

[0133] That is, the noise filter 100a has a structure in which a plurality of cancelling signal injection units are provided, the plurality of cancelling signal injection units arranged in series are further arranged in parallel in the circuit, and the number of the plurality of cancelling signal injection units arranged in parallel is the same.

[0134] The operation of each protection circuit during the protection operation in the noise filter 100a will be described. Fig.15 In the noise filter 100a configured as shown, when the protection action occurs in the elimination signal output unit 13, the protection action acts on the elimination signal injection units 14A1 and 14B1, which are connected to the terminal processing impedance 18b respectively provided. In this case, the number of the elimination signal injection units 14 inserted between the circuit 11A and the circuit 11B remains the same.

[0135] Fig.16 1 is a diagram showing the structure of a noise filter 100b as another example of the noise filter according to the second embodiment. Fig.15 The noise filter 100a according to the second embodiment shown is different in this respect.

[0136] In the noise filter 100b according to the second embodiment, a plurality of cancelling signal injection units 14 are provided for injecting the cancelling signal CS output from the cancelling signal output unit 13 into the circuit 11, and the cancelling signal injection units 14 are connected in series and parallel. Fig.15 Similarly, the structure shown is a structure in which the number of series connections is N and the number of parallel connections is 2 as an example of the structure.

[0137] That is, the noise filter 100b includes: a cancellation signal injection unit 14A1, 14A2, 14A3, ... 14AN, which is provided in the circuit 11A on one side of the parallel configuration; and a cancellation signal injection unit 14B1, 14B2, 14B3, ... 14BN, which is provided in the circuit 11B on the other side of the parallel configuration. The number N of series connections can be appropriately determined based on the characteristics required for the noise filter 100b and the characteristics required for the power conversion system.

[0138] There are provided N elimination signal output units 13, which are the same number as the number of elimination signal injection units 14 connected in series. The elimination signal output unit 13 has: a control power supply 19, which supplies power for generating and injecting the elimination signal CS to the elimination signal output unit 13; and a protection circuit 18, which is inserted between the control power supply 19 and the elimination signal output unit 13, can suppress the injection of the elimination signal CS during the protection action and is connected to the terminal processing impedance 18b.

[0139] The abnormality detection signal AS from the abnormality detection unit 17 in the elimination signal output unit 13 connected to the elimination signal injection unit 14A1 of the circuit 11A on one side of the parallel configuration is also input to the elimination signal injection unit 14B1. In addition, the abnormality detection signal AS from the abnormality detection unit 17 in the elimination signal output unit 13 connected to the elimination signal injection unit 14B1 of the circuit 11B on the other side of the parallel configuration is also input to the elimination signal injection unit 14A1. Hereinafter, the same structure is arranged until the combination of the elimination signal injection unit 14AN and the elimination signal injection unit 14BN.

[0140] exist Fig.17 Shown in Fig.15 The noise filter 100a shown in FIG. Fig.16An example of the structure of exchanging the abnormality detection signal AS between the elimination signal output unit 13 in the noise filter 100b shown. The abnormality detection signal AS output from the abnormality detection unit 17 is input to a transistor circuit connected by wired OR, for example, via a base resistor, and converged into a protection relay drive signal RY, and the protection relays 18a of the two elimination signal output units are switched at the same time.

[0141] <Effects of Implementation Method 2>

[0142] As described above, according to the noise filter according to the second embodiment, since the cancellation signal injection portion is divided into a plurality of parts as described above, even when the noise filter is provided between a large-capacity power conversion device and a load, it is possible to achieve high reliability.

[0143] More specifically, during the protection action, the number of elimination signal injection units 14 is also kept the same between circuit 11A and circuit 11B, thereby suppressing the inconsistency of the compensation voltage generated between circuit 11A on one side of the parallel connection and circuit 11B on the other side and the generation of large circulating current caused by the inconsistency of the compensation voltage.

[0144] Therefore, while suppressing the generation of circulating current due to the inconsistency of compensation voltages between parallel connections, it is possible to effectively prevent the increase of common-mode noise caused by unexpected resonance due to the change in the resonant frequency of the common-mode path, or the generation of magnetic saturation caused by unexpected increase in the insertion impedance of the injection transformer 14g, as in the first embodiment. Therefore, even when the noise filter is provided between a large-capacity power conversion device and a load, it is possible to achieve a noise filter with high reliability.

[0145] Implementation method 3.

[0146] use Figures 18 to 26 A noise filter 100d and a power conversion system 500d according to the third embodiment will be described.

[0147] Fig.18 1 is an overall configuration diagram of a power conversion system 500d according to Embodiment 3. The power conversion system 500d includes: a power conversion device 80 disposed between an AC power source 1 and a load 90, and converting input power from the AC power source 1 into any DC power or AC power; and a noise filter 100d inserted between the AC power source 1 and the power conversion device 80. The AC power source 1 and the noise filter 100d are connected via a circuit 2, and the noise filter 100d, the power conversion device 80, and the load 90 are connected via a circuit 11.

[0148] The circuit 11 is connected to the circuit 2 of the AC power supply 1, and the input power from the AC power supply 1 is input to the power conversion device 80 via the circuit 2. The power conversion device 80 converts the power input from the AC power supply 1 into the power required for driving the load 90 and outputs it. In addition, in the third embodiment, the noise filter 100d is arranged between the AC power supply 1 and the power conversion device 80, but it can also be arranged between the power conversion device 80 and the load 90.

[0149] Fig.19 This is a diagram for explaining the common mode noise CN generated in the power conversion system 500d involved in the third embodiment, and shows a common mode equivalent circuit. In the power conversion system 500d, the AC power supply 1 and the load 90 are connected on the ground side through the ground line 3 in addition to the above-mentioned circuit 11. A grounding capacitor 15 is provided in the noise filter 100d, and one end of the grounding capacitor 15 is connected to the ground line 3. In addition, there are parasitic capacitances 86 and 91 between the power conversion device 80 and the ground line 3 and between the load 90 and the ground line 3, respectively. In the power conversion system 500d, the common mode voltage Vcn of the power conversion device 80 is applied to the common mode loop via the parasitic capacitances 86, 91 and the ground line 3, and the common mode current (common mode noise CN) is as shown in Fig.19 Flows as indicated by the arrows.

[0150] Fig. 20 1 is a block diagram showing a noise filter 100d according to Embodiment 3. The noise filter 100d is inserted between the AC power supply 1 and the power conversion device 80. The noise filter 100d comprises: a noise detection unit 12 provided in a circuit 11 connected to the circuit 2; a cancellation signal output unit 13, which generates a cancellation signal according to the common mode noise CN detected by the noise detection unit 12 (in Fig. 20 The circuit 11 includes an elimination signal injection unit 14, which is arranged on the output side of the noise detection unit 12, that is, on the side of the power conversion device 80, and injects the elimination signal CS output from the elimination signal output unit 13 into the circuit 11; the control power supply 19 supplies the power for generating and injecting the elimination signal CS to the elimination signal output unit 13; and the protection circuit 18 is inserted between the control power supply 19 and the elimination signal output unit 13, and can cut off the supply of power from the control power supply 19.

[0151] The noise filter 100 d according to the third embodiment includes the protection circuit 18 capable of disconnecting the cancellation signal output unit 13 and the cancellation signal injection unit 14 as a protection unit for suppressing the injection of the abnormal cancellation signal CS into the circuit 11 .

[0152] The noise filter 100d involved in the third embodiment is different from the noise filter involved in the first and second embodiments, and constitutes a feedback control system. The feedback control system has the advantage of being more robust to the impedance error of the control object than the feedforward. In the noise filter 100d, a grounding capacitor 15 connected between the circuit 11 and the ground line 3 is provided, and the noise detection unit 12, the elimination signal injection unit 14 and the grounding capacitor 15 constitute the main circuit unit 101d in the power conversion system 500d. In addition, a filter unit 20 is provided between the noise detection unit 12 and the elimination signal generation unit 16. The filter unit 20 adjusts the characteristics of the elimination signal CS through the adjustment of the noise detection signal DS.

[0153] The control characteristics of the noise filter 100d largely depend on the main circuit unit 101d. The inductance value of the main circuit unit 101d is the sum of the inductance value of the common mode transformer constituting the noise detection unit 12 and the inductance value of the injection transformer 14g constituting the cancellation signal injection unit 14. In addition, the capacitance value of the main circuit unit 101d is the capacitance value of the grounding capacitor 15. The details of the control characteristics of the main circuit unit 101d will be described later.

[0154] The following describes a problem in the case where the noise filter 100d constitutes a feedback control system. First, the control response of the main circuit unit 101d of the noise filter 100d is described. Fig.21 A. Fig.21 B and Fig.21 C is a diagram showing a control response of the main circuit unit 101d of the noise filter 100d according to the third embodiment. Fig.21 A is a diagram showing a control response when the filter unit 20 is not present. Fig.21 B is a diagram showing the pass characteristics of the filter unit 20, Fig.21 C is a diagram showing the control response when the filter unit 20 is present. Fig.21 A. Fig.21 B and Fig.21 In C, the horizontal axis is frequency and the vertical axis is gain.

[0155] Here, the control response indicates an open loop response in a path from the output of the noise detector 12 to the noise detector 12 via the cancellation signal output unit 13 and the cancellation signal injection unit 14. The control stability of the noise filter 100d depends on the values ​​of the gain margin and phase margin of the open loop response.

[0156] like Fig.21 As shown in A, in the open loop response of the noise filter without the filter unit 20, a large resonance peak occurs at the resonance frequency f1 of the main circuit unit 101d, and the gain increases sharply. Fig.21Although not shown in Figure A, phase rotation also occurs at the resonance frequency f1. Thus, in the absence of the filter unit 20, the control response of the noise filter at the resonance frequency f1 becomes unstable. If the common mode noise CN detected by the noise detection unit 12 contains a component of the resonance frequency f1, the cancellation signal CS may also become unstable. In addition, regarding the resonance frequency f1,

[0157] f1=1 / {2π√(L1×C1)} Here, L1 is the inductance value of the main circuit portion 101d, and C1 is the capacitance value of the main circuit portion 101d.

[0158] As described above, in the absence of the filter unit 20, the control response of the noise filter 100d becomes unstable at the resonance frequency f1. Fig.21 The filter unit 20 having the filter pass characteristic shown in FIG. B is provided between the noise detection unit 12 and the cancellation signal generation unit 16. The filter unit 20 is configured so that the suppression frequency coincides with the resonance frequency f1 of the main circuit unit 101d. For example, such a filter unit 20 can be realized by using a notch filter. By configuring the filter unit 20 as described above, Fig.21 As shown in FIG. 2B , a filter pass characteristic is obtained in which the gain is greatly reduced at the resonance frequency f1. Therefore, in the open loop response of the noise filter 100d in the case where the filter unit 20 is present, as shown in FIG. Fig.21 As shown in C, the large resonance peak at the resonance frequency f1 is attenuated by the filter transmission characteristic of the filter unit 20 .

[0159] As described above, when the filter unit 20 is provided between the noise detection unit 12 and the cancellation signal generation unit 16, even when the common mode noise CN detected by the noise detection unit 12 includes a component of the resonance frequency f1, it is possible to generate the cancellation signal CS in which the resonance peak is attenuated. As a result, the noise filter 100d can exert a stable noise suppression effect.

[0160] Fig. 22 A and Fig. 22 B is a diagram showing the control response of the noise filter 100d according to the third embodiment. Fig. 22 A is a graph showing gain characteristics, Fig. 22 B is a diagram showing phase characteristics. In the control response characteristics (control characteristics) of the noise filter 100d, the phase gradually rotates due to the phase delays of the main circuit unit 101d, the cancellation signal generation unit 16, and the filter unit 20.

[0161] exist Fig. 22 A and Fig. 22In the example shown in FIG. 1B, a notch filter and a low-pass filter (not shown) are combined as the filter unit 20 of the noise filter 100d, and the resonance peak at the resonance frequency f1 as described above is suppressed, and the gain margin G2 at the phase reversal frequency f2 of the low frequency band and the gain margin G3 at the phase reversal frequency f3 of the high frequency band are set to values ​​that can ensure control stability. Here, the gain margins G2 and G3 are indicated by an upward arrow when they have a positive value, and by a downward arrow when they have a negative value. In addition, the value that can ensure control stability is, for example, 6 dB.

[0162] The following instructions are as follows Fig. 22 A and Fig. 22 As in the example shown in B, in the noise filter 100d in which the resonance peak is attenuated and the gain margins G2 and G3 at the phase inversion frequency are set to values ​​capable of ensuring control stability, the control characteristics of the noise filter 100d change due to the occurrence of some abnormality.

[0163] Fig.23 A and Fig.23 B is a diagram showing a control response of the noise filter 100d according to the third embodiment when a change in control characteristics occurs due to an abnormality. Fig.23 A is a graph showing changes in gain characteristics, Fig.23 B is a diagram showing the change of phase characteristics. In addition, in order to compare normal and abnormal conditions, the gain characteristics and phase characteristics in normal conditions are represented by solid lines, and the gain characteristics and phase characteristics in abnormal conditions are represented by dotted lines. Here, as an "abnormality", an example of the phase reversal frequency f3 in the high frequency band changing to the frequency f3* is shown.

[0164] As a typical example of such anomaly, there can be cited a case where the function of the low-pass filter is lost due to a component failure, and the characteristics of the filter unit change accordingly. In such a case, the value of the gain margin G3 at the phase reversal frequency f3 of the high frequency band sometimes changes and deviates from a value that can ensure control stability.

[0165] like Fig.23 As shown in FIG. 1A , the gain margin at the phase inversion frequency f3 in the high frequency band changes to a gain margin G3* having a negative value. It can be seen from this that the control response of the noise filter 100d becomes unstable. In the case of an unstable control response, the elimination signal CS output from the elimination signal output unit 13 also becomes an unstable signal having an abnormal output waveform, and the abnormal and unstable elimination signal CS is injected into the circuit 11.

[0166] Fig.24FIG. 1 is a diagram showing an abnormal output waveform of the cancellation signal output unit 13 according to the third embodiment, and shows an example of the waveform of the cancellation signal CS in the case of an abnormality. Fig.24 In the example, the horizontal axis is time. Since the gain margin at the phase inversion frequency f3 is a negative value, Fig.24 As shown in FIG. 1 , the frequency component of the phase inversion frequency f3 is continuously amplified, causing oscillation. Fig.24 The section enclosed by the arrow and the dotted line in FIG. 1 represents the period T3 of the cancellation signal CS in the abnormality. The period T3 is equal to the inverse of the phase inversion frequency f3.

[0167] In the case where the cancellation signal CS generates oscillation, Fig.19 In the common mode equivalent circuit shown, the noise source of common mode noise CN is also generated in the noise filter 100d. In the common mode equivalent circuit, the load 90, the system, and the power conversion device 80 share the noise source voltage according to their impedance ratios.

[0168] On the system side, not only does the noise filter 100d fail to operate normally and the normal attenuation cannot be obtained, but also the conduction noise from the oscillation operation of the noise filter 100d itself flows into the system via the circuit 11. On the load 90 side, for example, the shaft voltage of the motor may increase. In addition, in the power conversion device 80, there is a problem that a malfunction occurs due to the common mode noise CN generated by itself.

[0169] As described above, when using an active noise filter constituting a feedback control system such as the noise filter 100d according to the third embodiment, it is undesirable to leave abnormal output behavior represented by control oscillation that may occur due to characteristic changes caused by component failure or the like.

[0170] As described above, the canceling signal injector 14 of the noise filter 100d according to the third embodiment is constituted by the injection transformer 14g. The injection transformer 14g constituting the canceling signal injector 14 is an inductive load having an inductive impedance for the canceling signal output unit 13, and therefore has high impedance in the high frequency band.

[0171] Therefore, even if the elimination signal output unit 13 continues to Fig.24 In the state where the noise filter fails to perform normal noise suppression due to abnormal high-frequency oscillation as shown, overvoltage or overcurrent that affects the specifications of circuit components will not be immediately generated in the elimination signal output unit 13. This means that since the abnormality of the noise filter cannot be detected, even if an overvoltage protection circuit or an overcurrent protection circuit is provided in the noise filter, the noise filter will not be stopped based on the protection function.

[0172] Therefore, in the noise filter 100d involved in the third embodiment, the abnormality detection is performed by the abnormality detection unit 17, and the protection circuit 18 is activated when the abnormality is detected, thereby stopping the injection of the elimination signal CS and connecting the terminal processing impedance 18b to the elimination signal injection unit 14, thereby solving the problem when constructing a feedback control system. The following is a specific description comparing the elimination signal CS in a normal state with the elimination signal CS in an abnormal state.

[0173] Fig.25 A is a diagram showing the waveform of the common mode voltage in normal conditions. Fig.25 B is a diagram showing the waveform of the common mode current in normal conditions. Fig.25 C is a diagram showing a waveform of an output voltage of a cancel signal CS of the noise filter 100d according to the third embodiment in a normal state. Fig.25 D is a diagram showing the waveform of the output current of the cancel signal CS in normal conditions. Fig.25 A to Fig.25 In D, the horizontal axis is time.

[0174] exist Fig.25 The common mode voltage in A is the voltage of the common mode noise CN. Fig.25 The common mode current in B is the current flowing through the circuit 11 due to the common mode voltage. That is, the common mode current is Fig.19 The common mode equivalent circuit shown is an input common mode voltage and a current flowing through the circuit 11 assuming that the noise filter 100d is not present.

[0175] The common mode voltage is Figure 2 The switching operation of each semiconductor switch constituting the power conversion device 80 shown in FIG. Fig.25 A is a rectangular waveform. Common mode current is Fig.25 The waveform has a spike shape as shown in B, causing noise problems at various locations on the path.

[0176] The noise detection unit 12 of the noise filter 100 d detects the common mode current and sends the noise detection signal DS to the cancellation signal output unit 13 , which generates the cancellation signal CS based on the noise detection signal DS. The cancellation signal CS is injected into the circuit 11 via the cancellation signal injection unit 14 .

[0177] The output voltage of the normal elimination signal CS is as follows Fig.25 C has a peak-shaped waveform. In addition, the output current of the cancel signal CS generated by the output voltage of the cancel signal CS is also as shown in Fig.25It has a peak-shaped waveform as shown in D. The output current of the cancel signal CS is a current that cancels the common mode current, and therefore has a characteristic of being a waveform whose effective value is extremely small compared to the peak value, similarly to the common mode current.

[0178] In fact, the noise current flowing from the power conversion device 80, which is the noise source of the common mode noise CN, passes through the cancellation signal injection unit 14, thereby superimposing an interference component on the output current of the cancellation signal CS, and also superimposing an interference component on the output voltage of the cancellation signal CS due to the product of the output impedance of the cancellation signal CS and the current. However, in order to facilitate understanding of the gist of the present disclosure, Fig.25 C and Fig.25 In D, the superposition of interference components as described above is neglected.

[0179] Fig.26 A is a diagram showing the waveform of the common mode voltage in an abnormal situation. Fig.26 B is a diagram showing the waveform of the common mode current in an abnormal situation. Fig.26 C is a diagram showing a waveform of an output voltage of a cancel signal CS in an abnormal state in the noise filter 100d according to the third embodiment. Fig.26 D is a diagram showing the waveform of the output current when the abnormality of the signal CS is eliminated. Fig.26 A to Fig.26 In D, the horizontal axis is time.

[0180] like Fig.26 A and Fig.26 As shown in B, even in the abnormality, the common mode voltage and common mode current remain unchanged. On the other hand, in the abnormality, the control characteristics of the noise filter 100d change, and the cancellation signal CS oscillates. Therefore, Fig.26 C and Fig.26 As shown in D, the waveforms of the output voltage and output current of the elimination signal CS become as follows Fig.24 The abnormal output waveform is shown.

[0181] The abnormal output waveform does not have the characteristic of the normal waveform, that is, the effective value is extremely small compared to the peak value. Fig.26 C and Fig.26 In the waveform at the time of abnormality shown in D, the effective value of the output voltage of the cancellation signal CS is 1 / √2 times the peak value of the voltage, and there is no large difference between the peak value and the effective value.

[0182] In addition, the effective value of the output current of the cancel signal CS is 1 / √2 times the current peak value, and there is no large difference between the peak value and the effective value. This is also the case when the output voltage of the operational amplifier is saturated by the high-gain oscillation operation, and the waveform of the output voltage of the cancel signal CS becomes a rectangular wave.

[0183] As described above, it can be seen that during an abnormality, the effective value of the output voltage of the cancellation signal CS and the effective value of the output current become larger than those during normal operation. That is to say, during an abnormality, the effective value of the output voltage of the cancellation signal CS can be used as a determination criterion related to the abnormality. If this determination criterion is applied, by setting an appropriate threshold voltage or threshold current and comparing the actual effective value of the voltage with the above-mentioned threshold voltage, or comparing the actual effective value of the current with the above-mentioned threshold current, it is possible to determine whether the noise filter 100d is operating normally, that is, whether the noise filter 100d can cancel the common-mode current, or whether it has fallen into abnormal operation for some reason.

[0184] Typically, when the effective value of the output voltage of the cancellation signal CS during normal operation is set to V1, the threshold voltage of the effective value of the voltage for determining the presence or absence of an abnormality is set to Vth, and the effective value of the voltage during abnormal operation is set to V2, it is possible to determine the presence or absence of an abnormality by selecting the threshold voltage Vth of the effective value of the voltage so that V1 < Vth < V2. The same applies when the effective value of the output current of the cancellation signal CS is used in the determination of the presence or absence of an abnormality.

[0185] <Effect of Embodiment 3>

[0186] As described above, according to the noise filter according to Embodiment 3, the effect of achieving high reliability can be obtained even when the noise filter constitutes a feedback control system.

[0187] More specifically, in the case where an abnormality that needs to be protected occurs in the noise filter, the abnormality is detected based on the change in the output voltage or output current of the cancellation signal CS caused by the abnormality, the output of the noise cancellation signal from the cancellation signal output unit to the cancellation signal injection unit is suppressed, the abnormal cancellation signal is prevented from being injected into the circuit, and by connecting a terminal impedance to the auxiliary winding of the injection transformer constituting the cancellation signal injection unit, an increase in the common-mode noise CN caused by an unexpected resonance due to a change in the resonance frequency of the common-mode path, or the generation of magnetic saturation caused by an unexpected increase in the insertion impedance of the injection transformer is prevented, thereby achieving the effect of being able to achieve high reliability.

[0188] In addition, since the abnormality of the noise filter is detected based on the output voltage or output current of the cancellation signal CS, the effect of being able to reliably detect the abnormality of the noise filter in the high-frequency band can be obtained even when the cancellation signal injection unit of the cancellation signal CS is constituted by an inductive load such as a common-mode transformer (injection transformer).

[0189] Furthermore, the generation and injection of the cancellation signal CS is stopped by the protection circuit when an abnormality is detected, so that a stable operation can be performed while setting the gain margin and phase margin for controlling oscillation suppression in the feedback control system lower than before. The ability to set the gain margin and phase margin lower than before means that the control gain of the noise filter is increased, so that the noise suppression amount can also be increased.

[0190] Implementation method 4.

[0191] use Fig. 27 The noise filter 100e and the power conversion system 500e according to the fourth embodiment are described. Figures 1 to 26 The same or corresponding parts are denoted by the same reference numerals, and description thereof will be omitted. Fig. 27 1 is a block diagram showing a noise filter 100e and a power conversion system 500e according to Embodiment 4. The noise filters according to Embodiments 1, 2, and 3 all include a protection circuit 18 that disconnects the elimination signal injection unit 14 from the elimination signal output unit and connects the elimination signal injection unit 14 to the terminal processing impedance 18b according to the abnormality detection signal AS.

[0192] On the other hand, the noise filter 100e according to the fourth embodiment has a function of notifying the power conversion device 80 as a noise source of the abnormality of the noise filter 100e, instead of the above-mentioned protection circuit 18. Therefore, in the noise filter 100e according to the fourth embodiment, the protection circuit 18 is not an essential component. The noise filter 100e is provided with an abnormal state signal output unit 21 in the elimination signal output unit 13, and the abnormality detection signal AS output by the abnormality detection unit 17 is input to the abnormal state signal output unit 21. In the noise filter 100e according to the fourth embodiment, the abnormal state signal output unit 21 is provided as a protection unit for suppressing the injection of the elimination signal CS of the abnormality into the circuit 11.

[0193] The abnormal state signal output unit 21 has an output circuit capable of outputting a signal to the power conversion device 80, and when the abnormal state detection signal AS is input, the abnormal state signal AS2 is output to the power conversion device 80. The abnormal state signal AS2 is typically a differential signal with strong anti-interference or a low-impedance current signal, etc., and is generated based on the abnormal state detection signal AS. In addition, as required, the abnormal state signal AS2 is isolated from the control potential of the noise filter 100e. The power conversion device 80 that receives the abnormal state signal AS2 recognizes that the noise filter 100e is in an abnormal state.

[0194] The power conversion device 80 that recognizes that the noise filter 100e is in an abnormal state, for example, uses a prediction operation unit (not shown) to implement measures such as stopping the operation according to the content of the abnormality. A control circuit that stops the power conversion device 80 based on the abnormal state signal AS2 may also be provided outside or inside the power conversion device 80. Such a control circuit receives the abnormal state signal AS2 and sends a stop command to the power conversion device 80 as needed.

[0195] <Effects of Implementation Method 4>

[0196] As described above, according to the noise filter according to the fourth embodiment, since the abnormal state signal output unit is provided, there is an effect that a noise filter having high reliability can be provided.

[0197] The noise filter according to the fourth embodiment is different from the first, second and third embodiments in that it does not directly deal with the change in common mode resonance frequency caused by the change in insertion impedance of the injection transformer 14g during the protection operation and the core magnetic saturation of the injection transformer 14g. However, the abnormal state signal allows the power conversion device, which is the noise source of the common mode noise CN, to recognize the abnormality of the noise filter. In this case, the power conversion device takes measures such as stopping the operation as needed, thereby achieving the effect of preventing the abnormal cancellation signal from being generated and injected into the circuit, or preventing the common mode noise CN from increasing due to an unexpected common mode resonance frequency, by stopping the noise source of the common mode noise CN.

[0198] Thus, according to the noise filter involved in the fourth embodiment, by making the power conversion device 80 as the noise source recognize the abnormality of the noise filter, it is indirectly prevented that the abnormal cancellation signal CS is injected into the circuit or the unexpected common mode noise CN increases, thereby achieving the effect of achieving high reliability as a noise filter.

[0199] Furthermore, the noise filter 100e according to the fourth embodiment may be combined with the protection circuit 18 of the noise filter according to the first, second, and third embodiments. Furthermore, since the noise filter 100e according to the fourth embodiment outputs the abnormal state signal AS2 to the noise source of the common mode noise CN, when there are other controlled devices that are the noise source of the common mode noise CN, the abnormal state signal AS2 may be output to the other controlled devices as well.

[0200] Implementation method 5.

[0201] Fig.28 1 is a diagram showing a configuration of a management system 1000 according to Embodiment 5. The management system 1000 is composed of a power conversion system 500 f and a management device 200 .

[0202] The power conversion system 500f includes: a power conversion device 80, which is arranged between an AC power source 1 and a load 90, and converts the input power from the AC power source 1 into any DC power or AC power; a load 90, which is supplied with any DC power or AC power from the power conversion device 80; and a noise filter 100f, which is provided in a circuit 11 connecting the power conversion device 80 and the load 90, and has a communication function. In addition, the noise filter 100f can also be provided in a circuit 2 connecting the AC power source 1 and the power conversion device 80. In addition, as mentioned above, a DC power source can also be applied instead of the AC power source 1.

[0203] Fig.29 1 is a diagram showing a configuration of a noise filter 100f having a communication function applied to a power conversion system 500f according to Embodiment 5. The power conversion system 500f according to Embodiment 5 is structurally different from the noise filter 100 according to Embodiment 1 in that the noise filter 100f includes a communication unit 24 connected to the cancellation signal output unit 13.

[0204] The communication unit 24 as a part of the noise filter 100f converts various signals such as the cancellation signal CS and the abnormality detection signal AS generated in the cancellation signal output unit 13 into data and transmits them to the outside of the power conversion system 500f. The Internet can also be used for transmission.

[0205] like Fig.28 As shown, the management device 200 constituting the management system 1000 includes a receiving unit 201 , a database 202 , a data analyzing unit 203 , and a transmitting unit 204 .

[0206] The receiving unit 201 receives data transmitted to the outside of the power conversion system 500f via the communication unit 24 of the noise filter 100f, and stores the data in the database 202. The receiving unit 201 can also simultaneously receive data transmitted from the power conversion systems 500f owned by a plurality of clients.

[0207] The database 202 sequentially stores data transmitted from the power conversion system 500f. Alternatively, data transmitted from a plurality of power conversion systems 500f having different clients may be separately stored in an area designated for each client in the database 202.

[0208] The data analysis unit 203 performs various analyses of the trend, frequency, and cause of abnormalities occurring in the power conversion system 500f based on the data accumulated in the database 202. As an example of the analysis, a diagnosis for each component may be performed, such as whether the power conversion device 80 has a high failure frequency and should be replaced.

[0209] The transmission unit 204 transmits the analysis result of the data analysis unit 203 to the outside of the management system 1000 via the Internet, for example. As a transmission destination, a management system of a client operating the power conversion system 500f can be mentioned.

[0210] In the noise filter 100f constituting the power conversion system 500f, as described above, when an abnormality is detected, the abnormality detection unit 17 sends an abnormality detection signal AS, and the protection circuit 18 operates to perform a protection action such as cutting off the connection between the elimination signal generation unit 16 and the elimination signal injection unit 14, thereby achieving high reliability in the power conversion system 500f.

[0211] However, in the case where the above-mentioned protection actions frequently occur, it is indispensable to find out the cause of the abnormality and take countermeasures corresponding to the cause. In addition, it is also important for improving the reliability of the power conversion system. If the management system 1000 involved in the fifth embodiment is applied, the data analysis unit 203 analyzes the data sent from the power conversion system 500f to the management device 200, for example, the cause of the abnormality is found, and a countermeasure that can solve the abnormality is proposed, thereby eliminating the cause of the abnormality at an early stage, so that the reliability of the power conversion system 500f is further improved.

[0212] In addition, by using the management system 1000 according to Embodiment 5, the operating state of the power conversion system 500f can be grasped remotely, so that the management and maintenance of the power conversion system 500f become easy. In addition, for a client operating the power conversion system 500f, for example, the analysis results and the response methods of the management device 200 for abnormalities can be easily obtained via the Internet, so that the maintenance and inspection of the power conversion system 500f can be performed at an appropriate time, or the number of maintenance and inspections can be reduced, etc., and labor saving can be achieved at the same time.

[0213] <Effects of Implementation Method 5>

[0214] As described above, according to the management system 1000 involved in Implementation Example 5, there is a management device 200 that uses the data sent from the power conversion system 500f to perform data analysis, so it is possible to quickly respond to the cause of the abnormality, thereby further improving the reliability of the power conversion system 500, and at the same time also improving the maintainability of the management and maintenance of the power conversion system.

[0215] Implementation method 6.

[0216] use Fig.30 A power conversion system 500g according to the sixth embodiment will be described. Fig.301 is a block diagram showing a power conversion system 500g according to Embodiment 6. In the power conversion system 500g according to Embodiment 6, the power conversion device 80a includes a prediction operation unit 181 and an abnormality estimation unit 182, which is different from the power conversion system 500 according to Embodiment 1. In addition, the structure of the noise filter 100 is the same as that of Embodiment 1.

[0217] When the noise filter 100 is in an abnormal state, that is, when the abnormality detection unit 17 of the noise filter 100 sends an abnormality detection signal AS, the prediction operation unit 181 of the power conversion device 80a recognizes that the noise filter 100 is in an abnormal state, and outputs a resonance frequency prediction value based on the abnormality detection signal AS. The prediction operation unit 181 can further perform a countermeasure of making the switching frequency variable based on the resonance frequency prediction value.

[0218] The abnormality estimation unit 182 of the power conversion device 80a outputs an abnormality continuation determination value when the abnormality detection signal AS continues for a predetermined period or longer. The operation of the power conversion device 80a can also be stopped based on the abnormality continuation determination value.

[0219] <Effects of Implementation Method 6>

[0220] As described above, according to the power conversion system involved in embodiment 6, a prediction operation unit and an abnormality estimation unit are provided inside the power conversion device, so that abnormal conditions can also be dealt with on the power conversion device side, thereby achieving the effect of being able to provide a power conversion system with high reliability.

[0221] The present disclosure describes various exemplary embodiments and examples, but various features, methods, and functions described in one or more embodiments are not limited to application in specific embodiments and can be applied to the embodiments alone or in various combinations.

[0222] Therefore, numerous modifications not shown in the examples are conceivable within the technical scope disclosed in the present specification, including, for example, modifying, adding or omitting at least one structural element, and extracting at least one structural element and combining it with structural elements of other embodiments.

[0223] (Explanation of Reference Numerals)

[0224] 1: AC power supply; 2, 11, 11A, 11B: circuit; 3: ground wire; 12: noise detection unit; 12a, 12b, 12c, 12e: detection capacitor; 12d: T phase winding; 12f: star connection point; 12n: detection capacitor network; 13: elimination signal output unit; 14, 14A1, 14A2, 14A3, 14B1, 14B2, 14B3: elimination signal injection unit; 14a: R phase winding; 14b: S phase winding; 14c: T phase winding; 14d: injection winding; 14g: injection transformer; 15: Grounding capacitor; 16: Elimination signal generating unit; 16a: Input resistor; 16b: Operational amplifier; 16c: Feedback resistor; 17: Abnormality detection unit; 18: Protection circuit; 18a: Protection relay; 18b: Terminal processing impedance; 19: Control power supply; 20: Filter unit; 21: Abnormal state signal output unit; 24: Communication unit; 71: Processor; 72: Memory; 73: Auxiliary storage device; 74: Interface; 80, 80a: Power conversion device; 81: DC power supply; 82, 83, 84: Upper and lower arms; 82a, 82b, 83a , 83b, 84a, 84b: semiconductor switch; 85: inverter output terminal; 86, 91: parasitic capacitance; 90: load; 100, 100a, 100b, 100d, 100e, 100f: noise filter; 101, 101d: main circuit unit; 171: feature quantity detection unit; 171a, 171b: operational amplifier; 171c, 171d, 171e, 171h, 171i, 171j, 171m, 171l: resistor; 171f, 171g: diode; 171k: capacitor; 172: feature quantity detection unit Characteristic quantity comparison unit; 172a: comparator; 172b: DC voltage source; 172c: pull-up resistor; 181: prediction operation unit; 182: abnormality estimation unit; 200: management device; 201: receiving unit; 202: database; 203: data analysis unit; 204: sending unit; 500, 500d, 500e, 500f, 500g: power conversion system; 1000: management system; AS: abnormality detection signal; AS2: abnormal state signal; CN: common mode noise; CS: elimination signal; CV: characteristic quantity signal; DS: noise detection signal

Claims

1. A noise filter provided in any one of the following circuits: a circuit connecting an AC or DC power source and a power conversion device for converting power output from the AC or DC power source into AC or DC power; or a circuit connecting the power conversion device and a load, The noise filter is characterized by comprising: a noise detection unit for detecting common mode noise generated when the power conversion device operates; A cancellation signal generating unit, generating a cancellation signal for canceling the common mode noise; a cancellation signal injection unit, which injects the cancellation signal into the circuit; and The abnormality detection unit outputs an abnormality detection signal when detecting that the elimination signal is abnormal. An exception handling sequence is executed based on the exception detection signal.

2. The noise filter according to claim 1, wherein: A protection circuit is further provided, the protection circuit controlling injection of the cancellation signal into the circuit based on the abnormality detection signal.

3. The noise filter according to claim 2, characterized in that The protection circuit includes a protection relay and a terminal processing impedance, one end of which is connected to the protection relay.

4. The noise filter according to claim 3, characterized in that The termination processing impedance is set to an impedance value that prevents magnetic saturation of the injection transformer constituting the cancellation signal injection unit when the protection circuit is activated.

5. The noise filter according to any one of claims 1 to 4, characterized in that The abnormality detection unit regards the output voltage of the cancellation signal as abnormal and outputs the abnormality detection signal when the output voltage of the cancellation signal is higher than a preset threshold voltage or when the output current of the cancellation signal is higher than a preset threshold current.

6. The noise filter according to claim 3 or 4, characterized in that: The abnormality processing sequence is a sequence of operating the protection circuit based on the abnormality detection signal to cut off injection of the elimination signal into the circuit and connecting both ends of the elimination signal injection unit to the terminal processing impedance.

7. The noise filter according to any one of claims 1 to 5, characterized in that The abnormality processing sequence is a sequence in which the power conversion device determines that an abnormality exists based on the abnormality detection signal and changes a switching frequency based on a resonance frequency predicted by a prediction operation unit included in the power conversion device.

8. The noise filter according to any one of claims 1 to 5, characterized in that The abnormality processing sequence is a sequence in which the power conversion device determines that an abnormality has occurred based on an abnormality detection signal and stops the power conversion device.

9. The noise filter according to any one of claims 1 to 8, characterized in that A plurality of the elimination signal injection units are provided, and the plurality of the elimination signal injection units are arranged in series or in parallel in the circuit.

10. The noise filter according to any one of claims 1 to 8, characterized in that A plurality of the elimination signal injection units are provided, and the plurality of the elimination signal injection units arranged in series are further arranged in parallel in the circuit, and the number of the plurality of the elimination signal injection units arranged in parallel is the same.

11. The noise filter according to any one of claims 1 to 10, characterized in that: The noise filter is provided in the circuit on the output side of the power conversion device.

12. The noise filter according to any one of claims 1 to 10, characterized in that: The noise filter is provided in the circuit on the input side of the power conversion device.

13. The noise filter according to claim 11, characterized in that A filter unit is provided between the noise detection unit and the cancellation signal generation unit.

14. A power conversion system comprising: A power conversion device converts the power output from the AC or DC power source into AC or DC power; and The noise filter according to any one of claims 1 to 13.

15. The power conversion system according to claim 14, characterized in that: The power conversion device includes a prediction calculation unit that outputs a resonance frequency prediction value based on the abnormality detection signal, and makes a switching frequency variable based on the resonance frequency prediction value.

16. The power conversion system according to claim 14 or 15, characterized in that: The power conversion device includes an abnormality estimation unit that determines whether the abnormality detection signal continues for more than a preset period and outputs an abnormality continuation determination value when the abnormality detection signal continues for more than the preset period, and stops the operation of the power conversion device based on the abnormality continuation determination value.

17. A management system comprising: A power conversion device converts the power output from an AC or DC power source into AC or DC power; The noise filter according to any one of claims 1 to 13, further comprising a communication unit connected to a cancellation signal output unit constituting the noise filter and transmitting data to the outside; and The management device includes a database storing the data transmitted from the communication unit and a data analysis unit analyzing the data.

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