Noise filters, power conversion systems and control systems

Abstract

A noise filter (100) according to the present disclosure is provided to either a cable run (2) connecting an AC or DC power source (1) and a power conversion device (80) that converts power outputted from the power source (1) into AC or DC power or a cable run (11) connecting the power conversion device (80) and a load. The noise filter comprises: a noise detection unit (12) that detects common-mode noise generated during the operation of the power conversion device (80); a cancellation signal generation unit (16) that generates a cancellation signal which cancels the common-mode noise; a cancellation signal injection unit (14) that injects the cancellation signal into the cable run (2, 11); and an abnormality detection unit (17) that outputs an abnormality detection signal when the cancellation signal is detected to be abnormal. 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 noise filters, power conversion systems and management systems. [Background technology]

[0002] Power conversion devices are known that convert input power from a power source into DC or AC power and supply it to a load. Such power conversion devices perform power conversion by switching multiple bridge-connected switching elements, generating high-frequency noise as the switching elements operate. This high-frequency noise travels to the ground potential via parasitic capacitance and other factors, causing common-mode noise to flow to the power source or load. To suppress this common-mode noise, a known configuration is to install a noise filter in the electrical path between the power source and the power conversion device, or in the electrical path between the power conversion device and the load.

[0003] One type of noise filter is an active noise filter. For example, the active noise filter described in Patent Document 1 detects a common-mode voltage via a grounded capacitor connected to an electrical path between an AC power supply and a rectifier, generates a cancellation voltage of the same magnitude but opposite polarity as the detected common-mode voltage using a cancellation voltage source, and superimposes the cancellation voltage between the connection point between the AC power supply and the grounded capacitor in the electrical path. In this way, the active noise filter described in Patent Document 1 injects a cancellation voltage that cancels out the common-mode voltage, which is common-mode noise, into the electrical path as a noise cancellation signal (hereinafter referred to as a cancellation signal). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-57268 Summary of the Invention [Problem to be solved by the invention]

[0005] While an active noise filter is operating, the control characteristics of the active noise filter may change due to environmental factors, aging, etc. In the active noise filter described in Patent Document 1, if a change in the control characteristics occurs that was not anticipated at the time of design, there is a risk that an abnormal cancellation signal will be generated, such as one that causes oscillation of the cancellation signal injected into the electrical circuit due to a loss of control margin (gain margin and phase margin), or that the amount of compensation in noise cancellation will be excessive.

[0006] If an abnormal cancellation signal is injected into the electrical circuit, not only will it not be able to cancel out the common mode noise, but the cancellation signal itself may cause problems.

[0007] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a noise filter, a power conversion system, and a management system that can achieve high reliability. [Means for solving the problem]

[0008] AC or DC power supply and the output from the AC or DC power supply Required to drive the load A noise filter provided in either an electric path connecting a power conversion device that converts electric power into AC or DC power or an electric path connecting the power conversion device and a load, a noise detection unit that detects common mode noise generated during operation of the power conversion device; a cancellation signal generation unit that generates a cancellation signal that cancels the common mode noise; a cancellation signal injection unit that injects the cancellation signal into the electrical path; an abnormality detection unit that outputs an abnormality detection signal when detecting that the cancellation signal is abnormal; a protection relay and a terminating impedance having one end connected to the protection relay; Based on the abnormality detection signal By switching the relay contact of the protection relay, the cancellation signal injection unit and the cancellation signal generation unit are separated, and an abnormality processing sequence is executed to bring the noise cancellation into a stopped state in which the cancellation signal injection unit and the termination processing impedance are connected. a protection circuit; The abnormality processing sequence is executed based on the abnormality detection signal.

[0009] The power conversion system disclosed in the present application comprises: a power conversion device that converts power output from an AC or DC power source into AC or DC power; The noise filter is as described above.

[0010] The management system disclosed in the present application comprises: a power conversion device that converts power output from an AC or DC power source into AC or DC power; the noise filter further comprising a communication unit connected to a cancellation signal output unit constituting the noise filter and transmitting data to an external device; and a management device having a database for storing the data transmitted from the communication unit and a data analysis unit for analyzing the data. [Effects of the Invention]

[0011] The noise filter and power conversion system disclosed in the present application operate stably even when an abnormality occurs in the cancellation signal, thereby achieving high reliability.

[0012] According to the management system disclosed in the present application, since it has a management device that performs data analysis using data transmitted from the power conversion system, it is possible to quickly address the cause of an abnormality, which has the effect of further improving the reliability of the power conversion system and also has the effect of improving the maintainability, such as the management and maintenance of the power conversion system. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a system configuration diagram illustrating a power conversion system according to a first embodiment. [Figure 2] 1 is a circuit configuration diagram illustrating a power conversion device that constitutes a part of a power conversion system according to a first embodiment. [Figure 3]4 is a diagram illustrating common mode noise generated in the power conversion system according to the first embodiment. FIG. [Figure 4] 1 is a configuration diagram illustrating a noise filter and a power conversion system according to a first embodiment. [Figure 5A] 3 is a configuration diagram illustrating an example of a noise detection section in the noise filter according to the first embodiment. FIG. [Figure 5B] 3 is a configuration diagram illustrating an example of a noise detection section in the noise filter according to the first embodiment. FIG. [Figure 6] 3 is a configuration diagram illustrating an example of a cancellation signal generating section in the noise filter according to the first embodiment. FIG. [Figure 7] 3 is a configuration diagram illustrating an example of an abnormality detection unit in the noise filter according to the first embodiment. FIG. [Figure 8] 3 is a configuration diagram illustrating an example of a feature amount detection unit in the noise filter according to the first embodiment. FIG. [Figure 9] 3 is a configuration diagram illustrating an example of a feature comparison unit in the noise filter according to the first embodiment. FIG. [Figure 10] 3 is a configuration diagram illustrating a cancellation signal injection unit in the noise filter according to the first embodiment. FIG. [Figure 11] 1 is an example of a hardware configuration diagram for realizing a noise filter and a power conversion system according to a first embodiment. [Figure 12A] 4A and 4B are diagrams illustrating the behavior of the injection transformer in the noise filter according to the first embodiment during normal operation. [Figure 12B] 4 is a diagram illustrating the relationship between the impedance and frequency of the injection transformer during normal operation in the noise filter according to the first embodiment. FIG. [Figure 13A] 5A and 5B are diagrams illustrating the behavior of the injection transformer in the noise filter according to the first embodiment during a protective operation. [Figure 13B] 4 is a diagram illustrating the relationship between impedance and frequency during a protective operation of the injection transformer in the noise filter according to the first embodiment. FIG. [Figure 14]2 is a configuration diagram illustrating an example of a protection circuit in the noise filter according to the first embodiment. FIG. [Figure 15] FIG. 10 is a configuration diagram illustrating a noise filter according to a second embodiment. [Figure 16] FIG. 10 is a diagram illustrating another configuration example of the noise filter according to the second embodiment. [Figure 17] 10A and 10B are diagrams illustrating an example of processing of an abnormality detection signal in a cancellation signal output unit in the noise filter according to the second embodiment. [Figure 18] FIG. 10 is a configuration diagram illustrating a power conversion system according to a third embodiment. [Figure 19] 10 is a diagram illustrating common mode noise generated in the power conversion system according to the third embodiment. FIG. [Figure 20] FIG. 10 is a configuration diagram illustrating a noise filter according to a third embodiment. [Figure 21] Regarding the control response of the main circuit section of the noise filter, FIG. 21A is a diagram showing the control response when there is no filter section, FIG. 21B is a diagram showing the pass characteristics of the filter section, and FIG. 21C is a diagram showing the control response when there is a filter section. [Figure 22] Regarding the control response of the noise filter, FIG. 22A is a diagram showing the gain characteristic, and FIG. 22B is a diagram showing the phase characteristic. [Figure 23] Regarding the control response of the noise filter, FIG. 23A is a diagram showing the change in gain characteristics when a change in control characteristics occurs due to the occurrence of an abnormality, and FIG. 23B is a diagram showing the change in phase characteristics when a change in control characteristics occurs due to the occurrence of an abnormality. [Figure 24] 10A and 10B are diagrams illustrating an abnormal output waveform of a cancellation signal output unit of a noise filter. [Figure 25] FIG. 25A is a diagram showing the waveform of the common mode voltage under normal conditions, FIG. 25B is a diagram showing the waveform of the common mode current under normal conditions, FIG. 25C is a diagram showing the waveform of the output voltage of the cancellation signal under normal conditions in the noise filter, and FIG. 25D is a diagram showing the waveform of the output current of the cancellation signal under normal conditions in the noise filter. [Figure 26]FIG. 26A is a diagram showing the waveform of the common mode voltage when an abnormality occurs, FIG. 26B is a diagram showing the waveform of the common mode current when an abnormality occurs, FIG. 26C is a diagram showing the waveform of the output voltage of the cancellation signal when an abnormality occurs, and FIG. 26D is a diagram showing the waveform of the output current of the cancellation signal when an abnormality occurs. [Figure 27] FIG. 10 is a configuration diagram illustrating a noise filter and a power conversion system according to a fourth embodiment. [Figure 28] FIG. 10 is a configuration diagram illustrating a management system according to a fifth embodiment. [Figure 29] FIG. 10 is a configuration diagram illustrating a noise filter and a power conversion system according to a fifth embodiment. [Figure 30] FIG. 10 is a configuration diagram illustrating a noise filter and a power conversion system according to a sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Noise filters according to embodiments of the present invention will be described in detail below with reference to the drawings. In the drawings, the same reference numerals denote the same or corresponding parts.

[0015] Embodiment 1 A noise filter 100 and a power conversion system 500 according to the first embodiment will be described with reference to Fig. 1 to Fig. 11. Fig. 1 is a system configuration diagram showing the power conversion system 500 according to the first embodiment, and Fig. 2 is a circuit configuration diagram showing a power conversion device 80 that constitutes a part of the power conversion system 500 according to the first embodiment.

[0016] The power conversion system 500 is arranged between an AC power source 1 and a load 90 and is composed of a power conversion device 80 that converts input power from the AC power source 1 into any DC power or AC power, the load 90 to which any DC power or AC power is supplied from the power conversion device 80, and a noise filter 100 provided on an electric circuit 11 that connects 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 an electric circuit 2. Note that the AC power source 1 is merely one example of a power source, and a DC power source may be used instead of the AC power source 1, and similarly, a DC power source may be used instead of the AC power source 1 in each of the embodiments described below.

[0017] The power conversion device 80 converts input power input from the AC power supply 1 into power required to drive the load 90 and outputs the converted power. In the first embodiment, the noise filter 100 is disposed between the power conversion device 80 and the load 90, but it may be disposed in the electric circuit 2 connecting the AC power supply 1 and the power conversion device 80.

[0018] The power conversion device 80 is, for example, a two-level three-phase inverter as shown in Fig. 2. That is, one upper and lower arm 82 is formed by two semiconductor switches 82a and 82b connected in series. Further, one upper and lower arm 83 is formed by two semiconductor switches 83a and 83b connected in series. Furthermore, one upper and lower arm 84 is formed by two semiconductor switches 84a and 84b connected in series. A DC power supply 81 is connected to these three upper and lower arms 82, 83, and 84.

[0019] The DC power supply 81 is composed of a converter and the like that converts AC input power input from the AC power supply 1 into DC. The midpoints of three upper and lower arms 82, 83, and 84 are connected to an inverter output terminal 85. These six semiconductor switches 82a, 82b, 83a, 83b, 84a, and 84b perform switching operations, thereby outputting AC power to the inverter output terminal 85. At this time, the output potential of the inverter output terminal 85 becomes 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 constant voltage that is not zero.

[0020] 3 is a diagram illustrating a common mode equivalent circuit for explaining common mode noise generated in the power conversion system 500 according to the first embodiment. In the power conversion system 500, the AC power supply 1 and the load 90 are connected to each other on the ground side by a grounding wire 3, separate from the above-described electric circuit 11.

[0021] The noise filter 100 is provided with a grounding capacitor 15 (not shown), one end of which is connected to the ground line 3. Furthermore, a parasitic capacitance 86 exists between the power conversion device 80 and the ground line 3, and a parasitic capacitance 91 exists between the load 90 and the ground line 3, respectively. In the power conversion system 500, a common mode voltage Vcn generated in the power conversion device 80 is applied to a common mode loop that passes through the parasitic capacitances 86, 91 and the ground line 3, and therefore a common mode current (common mode noise CN) flows in the direction indicated by the arrow in FIG.

[0022] 4 is a configuration diagram illustrating a noise filter 100 and a power conversion system 500 according to the first embodiment. The noise filter 100 is inserted between a power conversion device 80 and a load 90. In other words, the noise filter 100 is provided in an electric circuit 11 that connects the power conversion device 80 and the load 90.

[0023] The noise filter 100 comprises a noise detection unit 12 connected to the electrical circuit 2, a cancellation signal output unit 13 that generates and outputs a cancellation signal CS from common mode noise CN (not shown in FIG. 4) detected by the noise detection unit 12, a cancellation signal injection unit 14 that is provided on the electrical circuit 11 closer to the output end than the noise detection unit 12, i.e., on the load 90 side, and that injects the cancellation signal CS output from the cancellation signal output unit 13 into the electrical circuit 11, and a control power supply 19 that supplies power to the cancellation signal output unit 13 for generating and injecting the cancellation signal CS.

[0024] The cancellation signal output unit 13 includes a cancellation signal generation unit 16 that amplifies the noise detection signal DS output from the noise detection unit 12, and an abnormality detection unit 17 that transmits the output from the cancellation signal generation unit 16 to the cancellation signal injection unit 14 as a cancellation signal CS and can output an abnormality detection signal AS based on the output voltage of the cancellation signal generation unit 16.

[0025] The cancellation signal output unit 13 further includes a protection circuit 18 that is an example of a connection cutoff means that is inserted between the abnormality detection unit 17 and the cancellation signal injection unit 14 and can cut off the injection of the cancellation signal. That is, the noise filter 100 according to the first embodiment includes a connection cutoff means that cuts off the connection between the cancellation signal output unit 13 and the cancellation signal injection unit 14, as a protection means for preventing an abnormal cancellation signal CS from being injected into the electrical circuit 11. In the first embodiment, the protection circuit 18 is used as one form of connection cutoff means.

[0026] In the first embodiment, the abnormality detection unit 17 is configured with elements and circuits that have almost no effect on the output characteristics, so the output of the cancellation signal generation unit 16 is almost the same as the cancellation signal CS. Therefore, in the following description, unless otherwise specified, the output of the cancellation signal generation unit 16 will be referred to as the cancellation signal CS.

[0027] A filter unit (not shown) capable of adjusting the characteristics of the cancellation signal CS may be provided between the noise detection unit 12 and the cancellation signal generation unit 16, or between the cancellation signal generation unit 16 and the abnormality detection unit 17. When a filter unit is provided between the noise detection unit 12 and the cancellation signal generation unit 16, the cancellation signal generation unit 16 will amplify the noise detection signal DS adjusted by the filter unit to generate the cancellation signal CS. Even in this case, the characteristics of the cancellation signal CS will be adjusted by adjusting the noise detection signal DS.

[0028] The above-mentioned filter section may be an input filter circuit that adjusts the attenuation characteristics of the noise filter 100, such as by reducing the gain of a specific band. Specifically, for example, an analog filter such as a high-pass filter, low-pass filter, or notch filter configured with resistors and capacitors may be used.

[0029] The noise filter 100 includes a grounded capacitor 15 (not shown) connected between the electric circuit 11 and the ground conductor 3. The noise detection unit 12, the cancellation signal injection unit 14, and the grounded capacitor 15 constitute a main circuit unit 101 of the noise filter 100. The control characteristics of the noise filter 100 depend heavily 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. The capacitance value of the main circuit unit 101 is the capacitance value of the grounded capacitor 15. Note that, although the above description describes a case where the load 90 is included inside the power conversion system 500, the present invention is not limited to such a configuration. That is, even when the load 90 is connected outside the power conversion system 500, the main circuit unit 101 is configured using a parasitic capacitance 91 that functions as the common mode impedance of the load 90. The same applies to the main circuit units in the following embodiments. The control characteristics of the main circuit section 101 will be described in detail later.

[0030] 5A and 5B are configuration diagrams illustrating an example of the noise detection unit 12 in the noise filter 100 according to the first embodiment. As shown in Fig. 5B, the noise detection unit 12 is configured with a capacitor network. The multiple capacitors that make up the noise detection unit 12 are hereinafter referred to as a detection capacitor network 12n.

[0031] Detecting capacitor network 12n includes, in electric circuit 11 connecting power conversion device 80 and load 90, detecting capacitor 12a connected to the U-phase power line, detecting capacitor 12b connected to the V-phase power line, detecting capacitor 12c connected to the W-phase power line, and detecting capacitor 12e provided between star connection point 12f connected to the other terminals of detecting capacitors 12a, 12b, and 12c that are not connected to the power lines and grounding conductor 3. As shown in FIG. 5B, detecting capacitor network 12n operates as a noise detector that divides and detects a common-mode voltage.

[0032] The detection ratio of the common-mode voltage in detection capacitor network 12n is determined by the ratio between the parallel impedance of detection capacitors 12a, 12b, and 12c and the impedance of detection capacitor 12e. Therefore, in noise detection unit 12, a noise detection signal DS is generated across T-phase winding 12d due to the common-mode noise CN applied to detection capacitor network 12n.

[0033] Both ends of T-phase winding 12d are connected to cancellation signal generator 16. That is, noise detection signal DS generated across both ends of T-phase winding 12d is sent to cancellation signal generator 16. Detection capacitor network 12n has an impedance that is sufficiently higher than parasitic capacitance 86 of the inverter and parasitic capacitance 91 of load 90 in the common-mode equivalent circuit shown in FIG. 3 , and therefore has a relatively high impedance to ground, and does not adversely affect the leakage current of power conversion device 80.

[0034] 6 is a configuration diagram showing an example of the cancellation signal generation unit 16 in the noise filter 100 according to the first embodiment. The cancellation signal generation 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 generation unit 16 (the left side in FIG. 6) via the input resistor 16a.

[0035] The inverting input terminal of the operational amplifier 16b is connected to the output terminal of the operational amplifier 16b via a feedback resistor 16c. The non-inverting input terminal of the operational amplifier 16b is grounded. The cancellation signal generation unit 16 shown in FIG. 6 is an inverting amplifier circuit using the operational amplifier 16b, but it may also be a non-inverting amplifier circuit. The cancellation signal generation unit 16 amplifies the noise detection signal DS with an amplification factor given by the ratio between the resistance value of the input resistor 16a and the resistance value of the feedback resistor 16c to generate the cancellation signal CS, and outputs the cancellation signal CS.

[0036] 7 is a configuration diagram showing an example of the anomaly detection unit 17 in the noise filter 100 according to the first embodiment. The anomaly detection unit 17 is made up of a feature detection unit 171 that outputs a feature signal CV for detecting an anomaly using the output voltage of the cancellation signal CS, and a feature comparison unit 172 that performs a predetermined calculation on the feature signal CV to generate and output an anomaly detection signal AS. In the first embodiment, it is assumed that when an anomaly in the noise filter 100 is detected, the anomaly detection signal AS is output as an ON signal, and when no anomaly is detected, the anomaly detection signal AS is output as an OFF signal.

[0037] 8 is a configuration diagram illustrating an example of a feature detection unit 171 that is part of the anomaly detection unit 17 in the noise filter 100 according to the first embodiment. The feature detection unit 171 generates and outputs a feature signal CV based on the voltage value of the output voltage as the cancellation signal CS. The feature signal CV is a signal that represents a feature used for anomaly detection. Various values ​​can be assumed to be used as the feature.

[0038] An example of feature detection unit 171 shown in Fig. 8 is a configuration of feature detection unit 171 when an average voltage value of the output voltage serving as cancellation signal CS is used as the feature amount. As shown in Fig. 8, feature detection unit 171 is configured by connecting a low-pass filter constituted by capacitor 171k and resistor 171l to the output side of an absolute value detection circuit constituted by operational amplifiers 171a and 171b, resistors 171c, 171d, 171e, 171h, 171i, 171j, and 171m, and diodes 171f and 171g.

[0039] An input terminal (not shown) of the feature detection unit 171 is connected to an output terminal (not shown) of the cancellation signal generation unit 16, and the output voltage as the cancellation signal CS output by the cancellation signal generation unit 16 is input as an input signal to the feature detection unit 171. When this input signal is input to the above-mentioned absolute value detection circuit, the absolute value detection circuit outputs the absolute value of the voltage value of the output voltage as the cancellation signal CS.

[0040] The output of the absolute value detection circuit is averaged by the low-pass filter, and the low-pass filter outputs the average voltage value of the output voltage as the cancellation signal CS. That is, the output of the feature detection unit 171 is the average voltage value of the output voltage as the cancellation signal CS. The output of the feature detection unit 171 is output to the feature comparison unit 172 as the feature signal CV. Note that the circuit of the feature detection unit 171 is not limited to the example shown in FIG. 8 and can be freely configured as long as it does not deviate from the spirit of the present application.

[0041] 9 is a configuration diagram illustrating an example of a feature comparison unit 172 that is part of the anomaly detection unit 17 in the noise filter 100 according to Embodiment 1. The feature comparison unit 172 generates an anomaly detection signal AS by performing a predetermined calculation on the feature signal CV output by the feature detection unit 171, and outputs the generated anomaly detection signal AS.

[0042] FIG. 9 shows an example of the noise filter 100 according to the first embodiment, in which the feature comparison unit 172 is configured using a comparator circuit that compares the feature signal CV with a preset threshold voltage. The feature 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 (left side of FIG. 9) of the feature comparison unit 172. The 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 feature comparison unit 172. The pull-up resistor 172c is connected between the output terminal of the comparator 172a and the output terminal of the feature comparison unit 172.

[0043] When the feature signal CV is input as an input signal to the feature comparison unit 172, the voltage of the feature signal CV is compared with the voltage of the DC voltage source 172b, and an abnormality detection signal AS is output according to the comparison result. Specifically, for example, if the voltage of the feature signal CV is greater than the voltage of the DC voltage source 172b, an abnormality is detected and the abnormality detection signal AS is output as an ON signal. In this case, the voltage value of the DC voltage source 172b serves as a threshold voltage for determining whether or not an abnormality exists. Note that the circuit constituting the feature comparison unit 172 is not limited to the example shown in FIG. 9 and can be freely configured within the scope of the present application.

[0044] FIG. 10 is a configuration diagram showing the cancellation signal injection unit 14 in the noise filter 100 according to the first embodiment. The cancellation signal injection unit 14 is configured with a common mode transformer. The common mode transformer configuring the cancellation signal injection unit 14 is hereinafter referred to as an injection transformer 14g. In the electric circuit 11, the injection transformer 14g includes an R-phase winding 14a wound around the R-phase power line, an S-phase winding 14b wound around the S-phase power line, a T-phase winding 14c wound around the T-phase power line, and an injection winding 14d. The R-phase winding 14a, the S-phase winding 14b, and the T-phase winding 14c are wound in phase. The injection transformer 14g configured as described above has a high inductance value only for the common mode and functions as a common mode choke coil.

[0045] In the cancellation signal injection unit 14 configured with the injection transformer 14g described above, when a cancellation signal CS is input to both ends of the injection winding 14d, an induced voltage V that cancels the common-mode noise CN is induced in the R-phase winding 14a, the S-phase winding 14b, and the T-phase winding 14c by the cancellation signal CS input to the injection winding 14d.

[0046] The hardware configuration that realizes the control system according to the first embodiment may be configured with analog circuits as shown in FIGS. 8 and 9, but here an example that is different from analog circuits will be described.

[0047] 11 is an example of a hardware configuration diagram realizing the control system of the noise filter 100 according to embodiment 1. Note that the "control system" here refers to the overall control of the noise filter 100, particularly 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.

[0048] The processor 71 is configured by, for example, a central processing unit (CPU), an application specific integrated circuit (ASIC), a digital signal processor (DSP), a field programmable gate array (FPGA), or the like.

[0049] 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 nonvolatile storage device such as a flash memory or a hard disk. A predetermined program to be executed by the processor 71 is stored in the auxiliary storage device 73. The processor 71 reads and executes this program as appropriate to perform various arithmetic processing. At this time, the predetermined program is temporarily saved from the auxiliary storage device 73 to the memory 72, and the processor 71 reads the program from the memory 72.

[0050] As described above, various arithmetic processes of the control system of the noise filter 100 and the power conversion system 500 according to the first embodiment are realized by the processor 71 executing a predetermined program. The results of the arithmetic processes performed by the processor 71 are temporarily stored in the memory 72 and then stored in the auxiliary storage device 73 according to the purpose of the executed arithmetic process. As such, the control system may be realized using either an analog circuit or a digital circuit.

[0051] The following describes problems that may occur in the control device of the noise filter 100 when an abnormality occurs, such as a temporary command value abnormality in the power conversion device 80, which is the controlled device, an abnormality in the winding of the injection coil, or a component failure such as a transistor or power capacitor, which is the control circuit.

[0052] For the control device, in order to protect the control device itself from overcurrent or overvoltage, and for the controlled device, in order to protect against increased path noise, it is necessary to perform a protective operation of disconnecting the cancellation signal generation unit 16 from the cancellation signal injection unit 14 to stop the noise cancellation operation.

[0053] When performing protection operation, the insertion impedance of the injection transformer 14g, which constitutes the cancellation signal injection unit 14, which is part of the main circuit unit 101, increases significantly when the connection between the cancellation signal generation unit 16 and the cancellation signal injection unit 14 is cut off, because the low output impedance of the cancellation signal generation unit 16 is no longer connected to the auxiliary winding connected to the control circuit side of the injection transformer 14g. In this case, the injection transformer 14g behaves as a common-mode choke coil with the same number of turns in its main winding, resulting in a large inductance component. As a result, the resonant frequency between the injection transformer 14g and the load common-mode capacitance fluctuates.

[0054] If the resonant frequency between the injection transformer 14g and the load common-mode capacitance fluctuates, the resonant frequency of the fluctuating common-mode path may overlap with the switching frequency of the power conversion device 80 and the band of its harmonic frequencies, which may actually cause a sudden increase in common-mode noise CN. To avoid this increase in common-mode noise CN, it is necessary to increase the inductance component of the injection transformer 14g during protection operation by selecting a large number of turns for the injection transformer 14g so that the resonant frequency during protection operation is lower than the switching frequency. However, increasing the number of turns for the injection transformer 14g undesirably increases the size of the noise filter 100.

[0055] From the viewpoint of voltage sharing, another problem that occurs during protection operation will be described below. The common mode voltage share on the load side seen from power conversion device 80, which is the noise source, is shared by the impedance ratio of main circuit unit 101 shown in Fig. 4. When cancellation signal generation unit 16 and cancellation signal injection unit 14 are disconnected, the low output impedance of cancellation signal generation unit 16 is no longer connected to the auxiliary winding connected to the control circuit side of injection transformer 14g, and so the insertion impedance of injection transformer 14g, which constitutes cancellation signal injection unit 14, which is part of main circuit unit 101, increases significantly.

[0056] As a result of a significant increase in the insertion impedance of the injection transformer 14g, the common-mode voltage passively shared by the injection transformer 14g with the common-mode noise CN shown in Fig. 3 increases significantly, which may cause magnetic saturation in the core. Magnetic saturation causes problems such as heat generation, noise, and vibration, so it is necessary to avoid magnetic saturation. However, an increase in the size of the core undesirably leads to an increase in the size of the noise filter 100.

[0057] 12A and 12B, the insertion impedance of the injection transformer 14g constituting the cancellation signal injection unit 14 during normal noise cancellation operation will be described. Fig. 12A is a diagram illustrating the behavior of the injection transformer 14g in the noise filter 100 according to the first embodiment during normal operation, and Fig. 12B is a diagram showing the relationship between the impedance and frequency of the injection transformer 14g in the noise filter 100 according to the first embodiment during normal operation.

[0058] As shown in Fig. 12A, during normal noise cancellation operation, a cancellation signal generator 16 with low output impedance is connected to injection winding 14d of injection transformer 14g, and cancellation signal injection unit 14 injects cancellation signal CS into electrical circuit 11. In this case, as shown in Fig. 12B, for example, the insertion impedance in the common mode path of injection transformer 14g is suppressed to a low value corresponding to the impedance of the amplifier circuit. Therefore, in the frequency band where common mode noise CN occurs, there is no effect on the resonant frequency of the common mode path, and because the voltage distribution due to the common mode voltage is low, magnetic saturation of injection transformer 14g due to voltage distribution due to passive impedance does not occur.

[0059] 13A and 13B will be used to explain the insertion impedance of the injection transformer 14g constituting the cancellation signal injection unit 14 during protection operation. FIG. 13A is a diagram explaining the behavior of the injection transformer 14g in the noise filter 100 according to the first embodiment during protection operation, and FIG. 13B is a diagram showing the relationship between impedance and frequency during protection operation of the injection transformer 14g in the noise filter 100 according to the first embodiment. As shown in FIG. 13A, the injection winding 14d is open during protection operation. In other words, a high open impedance is connected to the injection winding 14d.

[0060] In this case, the injection transformer 14g has an inductance component as a common-mode choke coil corresponding to the core permeability, magnetic path length, cross-sectional area, and number of turns of the injection transformer 14g, as shown in Figure 13B, and therefore behaves as an inductive impedance due to the inductance component, which significantly affects the resonant frequency of the common-mode path. Furthermore, the voltage contribution due to the common-mode voltage also increases significantly in the band where common-mode noise CN occurs, and as mentioned above, there is a risk of magnetic saturation of the injection transformer 14g.

[0061] The abnormality detection unit 17, connected between the cancellation signal generation unit 16 and the cancellation signal injection unit 14, outputs an abnormality detection signal AS based on either or both of the voltage and current of the cancellation signal CS from the cancellation signal generation unit 16.

[0062] 14 is a configuration diagram showing the protection circuit 18 of the noise filter 100 according to embodiment 1. A protection relay 18a constituting the protection circuit 18 can switch its relay contacts based on an abnormality detection signal AS to one of two states: a noise cancellation operating state in which the cancellation signal injection unit 14 and the cancellation signal generation unit 16 are connected, and a noise cancellation stopped state in which the cancellation signal injection unit 14 and the cancellation signal generation unit 16 are disconnected and the cancellation signal injection unit 14 is connected to a terminating impedance 18b.

[0063] 14, the protective relay 18a is shown as a single C-contact relay, but it may be configured by combining different A-contact and B-contact relays, and it may be configured as a semiconductor relay as well as a mechanical relay.The logic of the connected protective relay 18a may be such that a normally open contact is connected to the cancellation signal generator 16 and a normally closed contact is connected to the terminating impedance 18b, or vice versa.

[0064] By providing a protective relay 18a as shown in FIG. 14 and appropriately connecting the auxiliary winding of the injection transformer 14g that constitutes the cancellation signal injection unit 14 to the terminating impedance 18b when a protective operation occurs, it is possible to suppress problems such as fluctuations in the resonant frequency of the common mode path and core magnetic saturation of the injection transformer 14g.

[0065] As described above, the feature detection unit 171 outputs the effective voltage value of the output voltage of the cancellation signal CS as the feature signal CV. Furthermore, the DC voltage source 172b of the feature comparison unit 172 uses the output voltage value of the cancellation signal CS as the threshold voltage for determining whether or not an abnormality exists. That is, the output voltage value of the DC voltage source 172b is the threshold voltage Vth for the effective voltage value. As a result, the feature comparison unit 172 compares the effective voltage value of the output voltage of the cancellation signal CS with the threshold voltage Vth for the effective voltage value.

[0066] When the effective voltage value of the output voltage of the cancellation signal CS is greater than the threshold voltage Vth, the output of the comparator 172a becomes high, and the feature 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 cancellation signal CS is equal to or less than the threshold voltage Vth, the output of the comparator 172a becomes low, and the feature comparison unit 172 outputs the abnormality detection signal AS as OFF.

[0067] In the noise filter 100 according to the first embodiment, the abnormality detection signal AS output from the feature comparison unit 172 is input to the protection circuit 18. As shown in FIG. 14 , the protection circuit 18 is typically configured with a contact C control relay. Based on the abnormality detection signal AS, the protection circuit 18 disconnects the control power supply 19 from the cancellation signal output unit 13, cuts off the connection between the cancellation signal output unit 13 and the cancellation signal injection unit 14, and connects the cancellation signal injection unit 14 to the terminating impedance 18b. This operation of the cancellation signal output unit 13 blocks the injection of the cancellation signal CS into the electrical circuit 11, thereby preventing the injection of the cancellation signal CS having an abnormal output waveform into the electrical circuit 11 and suppressing fluctuations in the resonant frequency of the common-mode path and core magnetic saturation of the injection transformer 14g, which are caused by fluctuations in the insertion impedance of the injection transformer 14g that constitutes the cancellation signal injection unit 14.

[0068] After the anomaly detection unit 17 detects an anomaly and causes the protection circuit 18 to perform a cutoff operation, it is assumed that the cutoff operation of the protection circuit 18 will be reset and the generation and injection of the cancellation signal CS will be restored if, for example, the feature comparison unit 172 outputs an off-state anomaly detection signal AS. For an abnormal mode in which it is known in advance that the cutoff operation is temporary, a delay circuit or a counter circuit may be used to perform the recovery operation after a preset time has elapsed.

[0069] In the first embodiment, an example of a circuit using operational amplifier 16b is shown as a configuration of cancellation signal generator 16, but other inverting amplifier circuits or non-inverting amplifier circuits may also be used as the configuration of cancellation signal generator 16. In the above explanation, an example has been shown in which protection circuit 18 performs a cut-off operation in response to abnormality detection signal AS, but it is also possible to perform operations other than a simple cut-off operation by combining it with a logic circuit, such as latching the cut-off operation or being able to release the cut-off operation in combination with a reset circuit.

[0070] Although an example of a circuit using an operational amplifier as the configuration of the feature quantity detection unit 171 has been shown, other circuit configurations that achieve the same purpose may also be used. Although an example of using an effective voltage value as the detection quantity used by the feature quantity detection unit 171 has been shown, the feature quantity detection unit 171 may also be configured to detect different values, such as instantaneous values ​​or average values, as the feature quantity. Furthermore, although an example of a circuit using a comparator 172a as the configuration of the feature quantity comparison unit 172 has been shown, other circuits that achieve the same purpose may also be used.

[0071] Furthermore, in the noise filter 100 according to the first embodiment, other common mode choke coils may be connected to the electrical path 11 in addition to the noise detection unit 12 and the cancellation signal injection unit 14. Furthermore, the noise detection unit 12 may be configured using a capacitor instead of a common mode transformer.

[0072] As described above, the noise filter 100 according to the first embodiment is characterized in that it executes a process when an abnormality occurs in the cancellation signal CS, that is, an abnormality processing sequence. Here, the abnormality processing sequence refers to the following sequence. (1) A sequence in which the protection circuit 18 is operated based on the abnormality detection signal AS, the injection of the cancellation signal CS into the electrical circuit is cut off, and both ends of the cancellation signal injection unit 14 are connected to the terminating impedance 18b. (2) A sequence in which the power conversion device 80 determines an abnormality based on the abnormality detection signal AS and varies the switching frequency based on the resonant frequency predicted by the prediction calculation unit included in the power conversion device 80. (3) A sequence in which the power conversion device 80 determines an abnormality based on the abnormality detection signal AS and stops the power conversion device 80. The abnormality processing sequence may be, for example, any one of the above sequences (1) to (3). Details of sequences (2) and (3) will be described later in the sixth embodiment. It goes without saying that the sequences listed above are merely examples of abnormality processing sequences, and other processing that is effective in the event of an abnormality is also included. <Advantages of First Embodiment>

[0073] As described above, the noise filter 100 and the power conversion system 500 according to the first embodiment operate stably even when an abnormality occurs in the cancellation signal, thereby achieving an advantageous effect of achieving high reliability.

[0074] More specifically, by providing an abnormality detection unit that detects an abnormality in the noise filter and the power conversion device based on the output voltage or output current of the cancellation signal and outputs an abnormality detection signal, and a protection circuit that cuts off the connection between the cancellation signal injection unit and the cancellation signal output unit based on the abnormality detection signal and connects the cancellation signal injection unit to a terminating impedance, if an abnormality requiring protection occurs in the noise filter, the abnormality is detected from a change in the output voltage or output current of the cancellation signal caused by the abnormal state, and the output of the cancellation signal from the cancellation signal output unit to the cancellation signal injection unit is suppressed, preventing the injection of the abnormal cancellation signal into the electrical circuit. In addition, by connecting a terminating impedance to the auxiliary winding of the injection transformer that constitutes the cancellation signal injection unit, an increase in common mode noise due to unintended resonance caused by fluctuations in the resonant frequency of the common mode path, or magnetic saturation due to an unintended increase in the insertion impedance of the injection transformer, can be prevented, thereby achieving the effect of realizing a highly reliable noise filter and voltage conversion system.

[0075] Embodiment 2 A noise filter 100a according to a second embodiment will be described with reference to Figs. 15 to 17. Fig. 15 is a configuration diagram showing the noise filter 100a according to the second embodiment. Differences from the first embodiment will be mainly described. The cancellation signal injection unit 14, which injects the cancellation signal CS output from the cancellation signal output unit 13 into the electrical circuit 11, is provided with multiple cancellation signal injection units connected in series and parallel. This is because, when the noise filter 100a is provided between a large-capacity power conversion device and a load, in particular, it may be advantageous to configure the cancellation signal injection unit 14 separately due to core implementation issues.

[0076] 15 shows an example of noise filter 100a in which three cancellation signal injection units are connected in series and two in parallel. Cancellation signal injection unit 14 is made up of cancellation signal injection units 14A1, 14A2, and 14A3 provided in one electric circuit 11A arranged in parallel, and cancellation signal injection units 14B1, 14B2, and 14B3 provided in the other electric circuit 11B arranged in parallel.

[0077] A cancellation signal output unit 13 including a control power supply 19 that supplies power to the cancellation signal output unit 13 for generating and injecting the cancellation signal CS, and a protection circuit 18 that is inserted between the control power supply 19 and the cancellation signal output unit 13 and that, during protection operation, suppresses injection of the cancellation signal CS into the electrical circuits 11A, 11B and can be connected to a terminating impedance 18b, is provided for each unit of the number of cancellation signal injection units 14 connected in series. In other words, the noise filter 100a includes the same number of cancellation signal output units 13 as the number of cancellation signal injection units 14 connected in series.

[0078] That is, the noise filter 100a is configured such that a plurality of cancellation signal injection units are provided, the plurality of cancellation signal injection units arranged in series are further arranged in parallel with respect to the electrical path, and the number of the plurality of parallel cancellation signal injection units is the same.

[0079] The operation of each protection circuit during protection operation in noise filter 100a will be described. In noise filter 100a configured as shown in Fig. 15, when protection operation occurs in cancellation signal output unit 13, the protection operation is activated for cancellation signal injection units 14A1 and 14B1, and they are connected to terminating impedances 18b provided in each. In this case, the number of cancellation signal injection units 14 inserted between electrical circuit 11A and electrical circuit 11B is maintained the same.

[0080] 16 is a configuration diagram illustrating a noise filter 100b, which is another example of the noise filter according to embodiment 2. Differences from embodiment 1 and the noise filter 100a according to embodiment 2 shown in FIG. 15 will be mainly described.

[0081] In the noise filter 100b according to the second embodiment, a plurality of cancellation signal injection units are provided and connected in series and parallel for the cancellation signal injection unit 14 that injects the cancellation signal CS output from the cancellation signal output unit 13 into the electrical circuit 11. As with the configuration shown in Fig. 15 , the cancellation signal injection unit 14 of the noise filter 100b has, as an example, a configuration in which the number of series connections is N and the number of parallel connections is 2.

[0082] That is, the noise filter 100b is composed of cancellation signal injection units 14A1, 14A2, 14A3, ... 14AN provided in one electric circuit 11A arranged in parallel, and cancellation signal injection units 14B1, 14B2, 14B3, ... 14BN provided in the other electric circuit 11B arranged in parallel. The number of series, N, may be determined appropriately based on the characteristics required for the noise filter 100b and the characteristics required for the power conversion system.

[0083] The cancellation signal output unit 13 has a control power supply 19 that supplies the cancellation signal output unit 13 with power for generating and injecting the cancellation signal CS, and a protection circuit 18 that is inserted between the control power supply 19 and the cancellation signal output unit 13 and that suppresses the injection of the cancellation signal CS during protection operation and can be connected to a termination processing impedance 18b. N cancellation signal output units 13 are provided, the number of which is the same as the number of cancellation signal injection units 14 connected in series.

[0084] The abnormality detection signal AS from the abnormality detection unit 17 in the cancellation signal output unit 13 connected to the cancellation signal injection unit 14A1 of one electric circuit 11A arranged in parallel is also input to the cancellation signal injection unit 14B1. The abnormality detection signal AS from the abnormality detection unit 17 in the cancellation signal output unit 13 connected to the cancellation signal injection unit 14B1 of the other electric circuit 11B arranged in parallel is also input to the cancellation signal injection unit 14A1. A similar configuration is arranged below, up to the combination of the cancellation signal injection unit 14AN and the cancellation signal injection unit 14BN.

[0085] Fig. 17 shows an example of the configuration for communication of the abnormality detection signal AS between the cancellation signal output units 13 in the noise filter 100a shown in Fig. 15 and the noise filter 100b shown in Fig. 16. The abnormality detection signals AS output from the abnormality detection units 17 are input to wired-OR connected transistor circuits, for example, via base resistors, and combined into a single protection relay drive signal RY, which simultaneously switches the protection relays 18a of the two cancellation signal output units.

[0086] <Advantages of the Second Embodiment> As described above, according to the noise filter of the second embodiment, the cancellation signal injection unit is configured to be divided into multiple units, and therefore, even when the noise filter is provided between a large-capacity power conversion device and a load, high reliability can be achieved.

[0087] More specifically, even during protection operation, the number of cancellation signal injection units 14 is maintained the same between the electrical circuits 11A and 11B, thereby suppressing the imbalance in compensation voltages that occurs between the parallel electrical circuits 11A and 11B, and the occurrence of large circulating currents due to the imbalance in compensation voltages.

[0088] Therefore, while suppressing the occurrence of circulating current due to uneven compensation voltages between parallel circuits, similar to the first embodiment, it is possible to effectively prevent an increase in common mode noise due to unintended resonance caused by fluctuations in the resonance frequency of the common mode path or magnetic saturation due to an unintended increase in the insertion impedance of the injection transformer 14g, thereby achieving the effect of realizing a highly reliable noise filter even when the noise filter is provided between a large-capacity power conversion device and a load.

[0089] Embodiment 3 A noise filter 100d and a power conversion system 500d according to the third embodiment will be described with reference to FIGS. 18 is an overall configuration diagram showing a power conversion system 500d according to embodiment 3. The power conversion system 500d is arranged between an AC power supply 1 and a load 90 and includes a power conversion device 80 that converts input power from the AC power supply 1 into any DC power or AC power, and a noise filter 100d inserted between the AC power supply 1 and the power conversion device 80. The AC power supply 1 and the noise filter 100d are connected by an electric circuit 2, and the noise filter 100d, the power conversion device 80, and the load 90 are connected by an electric circuit 11.

[0090] The electric circuit 11 is connected to an electric circuit 2 of the AC power supply 1, and input power from the AC power supply 1 is input to the power conversion device 80 via the electric circuit 2. The power conversion device 80 converts the power input from the AC power supply 1 into power required to drive the load 90 and outputs the power. Note that, although the noise filter 100d is arranged between the AC power supply 1 and the power conversion device 80 in the third embodiment, it may also be arranged between the power conversion device 80 and the load 90.

[0091] FIG. 19 is a diagram illustrating common-mode noise CN generated in a power conversion system 500d according to the third embodiment, showing 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 by a grounding wire 3 in addition to the above-described electric circuit 11. The noise filter 100d is provided with a grounding capacitor 15 having one end connected to the grounding wire 3. Furthermore, a parasitic capacitance 86 and a parasitic capacitance 91 exist between the power conversion device 80 and the grounding wire 3, and between the load 90 and the grounding wire 3, respectively. In the power conversion system 500d, a common-mode voltage Vcn of the power conversion device 80 is applied to a common-mode loop that passes through the parasitic capacitances 86 and 91 and the grounding wire 3, and a common-mode current (common-mode noise CN) flows as shown by the arrows in FIG. 19.

[0092] 20 is a configuration diagram showing a noise filter 100d according to embodiment 3. The noise filter 100d is inserted between an AC power supply 1 and a power conversion device 80. The noise filter 100d includes: a noise detection unit 12 provided on an electric circuit 11 connected to an electric circuit 2; a cancellation signal output unit 13 that generates and outputs a cancellation signal CS from common mode noise CN (not shown in FIG. 20) detected by the noise detection unit 12; a cancellation signal injection unit 14 that is provided on the electric circuit 11 closer to the output end than the noise detection unit 12, i.e., on the power conversion device 80 side, and that injects the cancellation signal CS output from the cancellation signal output unit 13 into the electric circuit 11; a control power supply 19 that supplies power to the cancellation signal output unit 13 for generating and injecting the cancellation signal CS; and a protection circuit 18 that is inserted between the control power supply 19 and the cancellation signal output unit 13 and is capable of cutting off the supply of power from the control power supply 19.

[0093] The noise filter 100d according to the third embodiment includes a protection circuit 18 that can cut off the connection between the cancellation signal output unit 13 and the cancellation signal injection unit 14 as a protection means for preventing an abnormal cancellation signal CS from being injected into the electrical circuit 11.

[0094] Unlike the noise filters according to the first and second embodiments, the noise filter 100d according to the third embodiment configures a feedback control system. A feedback control system has the advantage of being more robust against impedance errors in the controlled object than a feedforward control system. The noise filter 100d includes a grounding capacitor 15 connected between the electric circuit 11 and the grounding conductor 3, and the noise detection unit 12, the cancellation signal injection unit 14, and the grounding capacitor 15 configure a main circuit unit 101d in the power conversion system 500d. A filter unit 20 is also provided between the noise detection unit 12 and the cancellation signal generation unit 16. The filter unit 20 adjusts the characteristics of the cancellation signal CS by adjusting the noise detection signal DS.

[0095] The control characteristics of the noise filter 100d depend heavily 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 that constitutes the noise detection unit 12 and the inductance value of the injection transformer 14g that constitutes the cancellation signal injection unit 14. The capacitance value of the main circuit unit 101d is the capacitance value of the grounded capacitor 15. The control characteristics of the main circuit unit 101d will be described in detail later.

[0096] The following describes the problems that arise when the noise filter 100d forms a feedback control system. First, the control response of the main circuit unit 101d of the noise filter 100d will be described. FIGS. 21A, 21B, and 21C are diagrams showing the control response of the main circuit unit 101d of the noise filter 100d according to embodiment 3. FIG. 21A shows the control response when the filter unit 20 is not present, FIG. 21B shows the pass characteristics of the filter unit 20, and FIG. 21C shows the control response when the filter unit 20 is present. In FIGS. 21A, 21B, and 21C, the horizontal axis represents frequency, and the vertical axis represents gain.

[0097] Here, the control response refers to an open-loop response in a path that starts from the output of the noise detection unit 12, passes through the cancellation signal output unit 13 and the cancellation signal injection unit 14, and returns to the noise detection unit 12. The control stability of the noise filter 100d depends on the values ​​of the gain margin and phase margin of the open-loop response.

[0098] As shown in FIG. 21A, 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. Although not shown in FIG. 21A, phase rotation also occurs at the resonance frequency f1. Thus, without the filter unit 20, the noise filter's control response becomes unstable at the resonance frequency f1. 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. The resonance frequency f1 is given by f1=1 / {2π√(L1×C1)}, where L1 is the inductance value of the main circuit unit 101d, and C1 is the capacitance value of the main circuit unit 101d.

[0099] As described above, without the filter unit 20, the noise filter 100d has an unstable control response at the resonance frequency f1. To address this issue, the filter unit 20, which has the filter pass characteristic shown in FIG. 21B, is provided between the noise detection unit 12 and the cancellation signal generation unit 16. The filter unit 20 is configured so that its reject frequency matches the resonance frequency f1 of the main circuit unit 101d. Such a filter unit 20 can be realized, for example, by a notch filter. By configuring the filter unit 20 as described above, a filter pass characteristic that significantly reduces the gain at the resonance frequency f1 is obtained, as shown in FIG. 21B. Therefore, in the open-loop response of the noise filter 100d with the filter unit 20, the large resonance peak at the resonance frequency f1 is attenuated by the filter pass characteristic of the filter unit 20, as shown in FIG. 21C.

[0100] As described above, when the filter unit 20 is provided between the noise detection unit 12 and the cancellation signal generation unit 16, it is possible to generate a cancellation signal CS with an attenuated resonance peak even if the common mode noise CN detected by the noise detection unit 12 contains a component of the resonance frequency f1. As a result, the noise filter 100d can exert a stable noise suppression effect.

[0101] 22A and 22B are diagrams showing the control response of the noise filter 100d according to embodiment 3, with Fig. 22A showing the gain characteristic and Fig. 22B showing the phase characteristic. In the control response characteristic (control characteristic) of the noise filter 100d, the phase rotates due to phase delays of the main circuit unit 101d, the cancellation signal generation unit 16, and the filter unit 20.

[0102] 22A and 22B, the filter section 20 of the noise filter 100d is a combination of a notch filter and a low-pass filter (neither of which is shown), which suppresses the resonance peak at the resonance frequency f1 as described above, and the gain margin G2 at the phase inversion frequency f2 in the low-frequency band and the gain margin G3 at the phase inversion frequency f3 in the high-frequency band are set to values ​​that ensure control stability. Here, the gain margins G2 and G3 are indicated by upward arrows when they have positive values ​​and downward arrows when they have negative values. The value that ensures control stability is, for example, 6 dB.

[0103] As shown in the example of FIGS. 22A and 22B , in a 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 ​​that ensure control stability, a situation will be described below in which the control characteristics of the noise filter 100d change due to the occurrence of some kind of abnormality.

[0104] 23A and 23B are diagrams showing control responses when a change in control characteristics occurs due to the occurrence of an abnormality in the noise filter 100d according to embodiment 3, with Fig. 23A showing changes in gain characteristics and Fig. 23B showing changes in phase characteristics. To compare normal and abnormal conditions, the gain and phase characteristics in normal conditions are represented by solid lines, and the gain and phase characteristics in abnormal conditions are represented by dashed lines. Here, an example is shown in which the phase inversion frequency f3 in the high frequency band has shifted to frequency f3* as an "abnormality."

[0105] A typical example of such an abnormality is when the low-pass filter loses its function due to a component failure, causing a change in the characteristics of the filter section. In such a case, the value of the gain margin G3 at the phase inversion frequency f3 in the high-frequency band fluctuates, and may deviate from the value that ensures control stability.

[0106] 23A, the gain margin at the high-frequency phase inversion frequency f3 fluctuates to a negative gain margin G3*. This indicates that the control response of the noise filter 100d is unstable. When the control response is unstable, the cancellation signal CS output from the cancellation signal output unit 13 also becomes an unstable signal with an abnormal output waveform, and an abnormal and unstable cancellation signal CS is injected into the electrical circuit 11.

[0107] FIG. 24 is a diagram showing an abnormal output waveform of the cancellation signal output unit 13 according to the third embodiment, illustrating an example of the waveform of the cancellation signal CS when an abnormality occurs. In FIG. 24, the horizontal axis represents time. Because the gain margin at the phase inversion frequency f3 is a negative value, the frequency component of the phase inversion frequency f3 continues to be amplified, causing oscillation, as shown in FIG. 24. Note that the section between the arrow and the dashed line in FIG. 24 indicates the period T3 of the cancellation signal CS when an abnormality occurs. The period T3 is equal to the reciprocal of the phase inversion frequency f3.

[0108] When the cancellation signal CS oscillates, the noise source of the common mode noise CN also appears in the noise filter 100d in the common mode equivalent circuit as shown in Fig. 19. 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 respective impedance ratios.

[0109] On the system side, not only does the noise filter 100d not operate normally and normal attenuation cannot be achieved, but also there is a problem that conducted noise resulting from the oscillation of the noise filter 100d itself leaks into the system via the electric circuit 11. On the load 90 side, for example, there is a risk of an increase in the shaft voltage of the motor. Also, there is a problem that the common mode noise CN generated by the power conversion device 80 itself causes malfunction.

[0110] As described above, when using an active noise filter that constitutes a feedback control system such as the noise filter 100d according to the third embodiment, it is undesirable to leave abnormal output operation, such as controlled oscillation, that can occur due to a change in characteristics caused by a component failure or the like.

[0111] As described above, the cancellation signal injection unit 14 of the noise filter 100d according to embodiment 3 is configured with the injection transformer 14g. The injection transformer 14g that constitutes the cancellation signal injection unit 14 acts as an inductance load with inductive impedance for the cancellation signal output unit 13, and therefore has high impedance in the high frequency band.

[0112] 24 continues to operate abnormally at high frequencies, preventing the noise filter from performing normal noise suppression, but phenomena that would affect the specifications of circuit components, such as overvoltage or overcurrent, do not immediately occur in the cancellation signal output section 13. This means that, since it is not possible to detect an abnormality in the noise filter, even if the noise filter is equipped with an overvoltage protection circuit or overcurrent protection circuit, the protection function will not stop the noise filter.

[0113] Therefore, in the noise filter 100d according to the third embodiment, abnormalities are detected by the abnormality detection section 17, and when an abnormality is detected, the protection circuit 18 is activated to stop the injection of the cancellation signal CS and connect the terminating impedance 18b to the cancellation signal injection section 14, thereby simultaneously solving the problem of constructing a feedback control system. A specific description will be given below, comparing the cancellation signal CS in a normal state with the cancellation signal CS in an abnormal state.

[0114] Fig. 25A shows the waveform of the common-mode voltage under normal conditions, and Fig. 25B shows the waveform of the common-mode current under normal conditions. Fig. 25C shows the waveform of the output voltage of the cancellation signal CS under normal conditions for the noise filter 100d according to Embodiment 3, and Fig. 25D shows the waveform of the output current of the cancellation signal CS under normal conditions. In Figs. 25A to 25D, the horizontal axis represents time.

[0115] In Fig. 25A, the common mode voltage is the voltage of the common mode noise CN. In Fig. 25B, the common mode current is the current that flows in the electric circuit 11 due to the common mode voltage. In other words, the common mode current is the current that flows in the electric circuit 11 when a common mode voltage is input to the common mode equivalent circuit shown in Fig. 19 and when it is assumed that the noise filter 100d is not included.

[0116] Common-mode voltage is generated in conjunction with the switching operation of each semiconductor switch constituting the power conversion device 80 shown in Fig. 2, and has a rectangular waveform as shown in Fig. 25A. Common-mode current has a spike-like waveform as shown in Fig. 25B, and causes noise problems at various points along the path.

[0117] The noise detection unit 12 of the noise filter 100d detects the common-mode current and transmits a noise detection signal DS to the cancellation signal output unit 13. The cancellation signal output unit 13 generates a cancellation signal CS from the noise detection signal DS. The cancellation signal CS is injected into the electrical circuit 11 via the cancellation signal injection unit 14.

[0118] The output voltage of the cancellation signal CS under normal conditions has a spike-like waveform as shown in Figure 25C. The output current of the cancellation signal CS, which is generated by the output voltage of the cancellation signal CS, also has a spike-like waveform as shown in Figure 25D. The output current of the cancellation signal CS is a current that cancels out the common mode current, and so, like the common mode current, it has the characteristic of having a waveform whose effective value is extremely smaller than the peak value.

[0119] In reality, a noise current flowing out from power conversion device 80, which is the noise source of common mode noise CN, passes through cancellation signal injection unit 14, causing a disturbance component to be superimposed on the output current of cancellation signal CS, and also causing a disturbance component to be superimposed on the output voltage of cancellation signal CS due to the product of the output impedance and current of cancellation signal CS. However, to make the gist of the present disclosure easier to understand, the superposition of such disturbance components is ignored in Figures 25C and 25D.

[0120] Fig. 26A is a diagram showing the waveform of a common-mode voltage when an abnormality occurs, and Fig. 26B is a diagram showing the waveform of a common-mode current when an abnormality occurs. Fig. 26C is a diagram showing the waveform of the output voltage of cancellation signal CS when an abnormality occurs in noise filter 100d according to Embodiment 3, and Fig. 26D is a diagram showing the waveform of the output current of cancellation signal CS when an abnormality occurs. In Figs. 26A to 26D, the horizontal axis represents time.

[0121] As shown in Figures 26A and 26B, the common-mode voltage and common-mode current do not change even when an abnormality occurs. However, when an abnormality occurs, a change in the control characteristics occurs in the noise filter 100d, causing the cancellation signal CS to oscillate. As a result, as shown in Figures 26C and 26D, the waveforms of the output voltage and output current of the cancellation signal CS become abnormal output waveforms like those shown in Figure 24.

[0122] The abnormal output waveform does not have the characteristic of a normal waveform, namely, the characteristic that the RMS value is extremely smaller than the peak value. Specifically, in the abnormal waveforms shown in Figures 26C and 26D, the RMS voltage value of the output voltage of the cancellation signal CS is 1 / √2 times the voltage peak value, and there is no large difference between the peak value and the RMS value.

[0123] Furthermore, the effective current value of the output current of the cancellation signal CS is 1 / √2 times the peak current value, and there is not much difference between the peak value and the effective value. This is also true even when the output voltage of the operational amplifier becomes saturated due to high-gain oscillation, causing the output voltage waveform of the cancellation signal CS to become rectangular.

[0124] As described above, it can be seen that during an abnormality, the effective voltage value of the output voltage of the cancel signal CS and the effective current value of the output current are greater than those during normal operation. That is, during an abnormality, the effective voltage value of the output voltage of the cancel signal CS can be used as a determination criterion for the abnormality. By applying this determination criterion, an appropriate threshold voltage or threshold current can be set, and by comparing the actual effective voltage value with the above threshold voltage, or the actual effective current value with the above threshold current, it can be determined 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.

[0125] Typically, if the effective voltage value of the output voltage of the cancel signal CS during normal operation is V1, the threshold voltage of the effective voltage value for determining the presence or absence of an abnormality is Vth, and the effective voltage value during abnormal operation is V2, then by selecting the threshold voltage Vth of the effective voltage value such that V1 < Vth < V2, the presence or absence of an abnormality can be determined. The same applies when using the effective current value of the output current of the cancel signal CS to determine the presence or absence of an abnormality.

[0126] <Effect of Embodiment 3> As described above, according to the noise filter according to Embodiment 3, even when the noise filter constitutes a feedback control system, an effect of achieving high reliability can be obtained.

[0127] More specifically, when an abnormality that requires protection occurs in the noise filter, the abnormality is detected from the change in the output voltage or output current of the cancel signal CS due to the abnormality, the output of the noise cancel signal from the cancel signal output unit to the cancel signal injection unit is suppressed, and it is prevented that an abnormal cancel signal is injected into the circuit. By connecting a termination impedance to the auxiliary winding of the injection transformer that constitutes the cancel signal injection unit, an increase in the common mode noise CN due to an unintentional resonance caused by a change in the resonance frequency of the common mode path, or the occurrence of magnetic saturation due to an unintentional increase in the insertion impedance of the injection transformer can be prevented, thereby achieving an effect of realizing high reliability.

[0128] Furthermore, since an abnormality in the noise filter is detected based on the output voltage or output current of the cancellation signal CS, it is possible to reliably detect an abnormality in the noise filter in the high frequency band even if the cancellation signal injection section for the cancellation signal CS is configured with an inductance load such as a common mode transformer (injection transformer).

[0129] Furthermore, because the protection circuit stops generating and injecting the cancellation signal CS when an abnormality is detected, stable operation can be achieved while setting the gain margin and phase margin for suppressing controlled oscillation in the feedback control system lower than before. Setting the gain margin and phase margin lower than before means improving the control gain of the noise filter, which has the effect of improving the amount of noise suppression.

[0130] Embodiment 4 A noise filter 100e and a power conversion system 500e according to a fourth embodiment will be described with reference to Fig. 27. Components that are the same as or equivalent to those in Figs. 1 to 26 are designated by the same reference numerals, and descriptions thereof will be omitted. Fig. 27 is a configuration diagram showing the noise filter 100e and the power conversion system 500e according to the fourth embodiment. The noise filters according to the first, second, and third embodiments all include a protection circuit 18 that, in response to an abnormality detection signal AS, disconnects the cancellation signal injection unit 14 from the cancellation signal output unit and connects the cancellation signal injection unit 14 to the terminating impedance 18b.

[0131] On the other hand, the noise filter 100e according to the fourth embodiment has a function of notifying the power conversion device 80, which is the noise source, of an abnormality in the noise filter 100e, instead of the above-mentioned protection circuit 18. Therefore, the protection circuit 18 is not an essential component of the noise filter 100e according to the fourth embodiment. In the noise filter 100e, the cancellation signal output unit 13 is provided with an abnormal state signal output unit 21, and the abnormality detection signal AS output by the abnormality detection unit 17 is input to the abnormal state signal output unit 21. The noise filter 100e according to the fourth embodiment includes the abnormal state signal output unit 21 as protection means for preventing an abnormal cancellation signal CS from being injected into the electric circuit 11.

[0132] 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, outputs an abnormal state signal AS2 to the power conversion device 80. The abnormal state signal AS2 is typically a differential signal or a low-impedance current signal that is resistant to external disturbances, and is generated based on the abnormal state detection signal AS. Furthermore, the abnormal state signal AS2 is isolated from the control potential of the noise filter 100e as necessary. Upon receiving the abnormal state signal AS2, the power conversion device 80 recognizes that the noise filter 100e is in an abnormal state.

[0133] The power conversion device 80, which has recognized that the noise filter 100e is in an abnormal state, takes measures such as stopping operation depending on the nature of the abnormality, for example, using a predictive calculation unit (not shown). A control circuit that stops the power conversion device 80 based on the abnormal state signal AS2 may be provided outside or inside the power conversion device 80. Such a control circuit receives the abnormal state signal AS2 and transmits a stop command to the power conversion device 80 as necessary.

[0134] <Advantages of the Fourth Embodiment> As described above, the noise filter according to the fourth embodiment is provided with an abnormal state signal output section, which has the effect of providing a highly reliable noise filter.

[0135] Unlike the first, second, and third embodiments, the noise filter according to the fourth embodiment does not directly address problems such as fluctuations in the common-mode resonant frequency due to fluctuations in the insertion impedance of the injection transformer 14g during protection operation and core magnetic saturation of the injection transformer 14g. However, the abnormal state signal is used to make the power converter, which is the noise source of the common-mode noise CN, aware of an abnormality in the noise filter. In this case, the power converter takes measures such as halting operation as necessary, thereby preventing the generation of an abnormal cancellation signal that is injected into the electrical circuit by stopping the noise source of the common-mode noise CN, or the increase in the common-mode noise CN due to an unintended common-mode resonant frequency.

[0136] In this way, the noise filter according to the fourth embodiment has the effect of realizing high reliability as a noise filter by making the power conversion device 80, which is the noise source, aware of an abnormality in the noise filter, thereby indirectly preventing an abnormal cancellation signal CS from being injected into the electrical circuit or an unintended increase in common mode noise CN.

[0137] The noise filter 100e according to the fourth embodiment may be combined with the protection circuit 18 of the noise filters according to the first, second, and third embodiments. 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, if there is another controlled device that is also a noise source of the common mode noise CN, the noise filter 100e may be configured to output the abnormal state signal AS2 to the other controlled device as well.

[0138] Embodiment 5 28 is a configuration diagram illustrating a management system 1000 according to Embodiment 5. The management system 1000 includes a power conversion system 500f and a management device 200.

[0139] The power conversion system 500f is arranged between an AC power source 1 and a load 90 and is composed of a power conversion device 80 that converts input power from the AC power source 1 into any DC power or AC power, the load 90 to which any DC power or AC power is supplied from the power conversion device 80, and a noise filter 100f having a communication function that is provided on an electric circuit 11 connecting the power conversion device 80 and the load 90. Note that the noise filter 100f may also be provided on an electric circuit 2 that connects the AC power source 1 and the power conversion device 80. Also, as described above, a DC power source may be used instead of the AC power source 1.

[0140] 29 is a configuration diagram illustrating a noise filter 100f having a communication function, which is applied to a power conversion system 500f according to embodiment 5. The power conversion system 500f according to embodiment 5 differs in configuration 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.

[0141] The communication unit 24, which is part of the configuration of the noise filter 100f, converts various signals generated inside the cancellation signal output unit 13, such as the cancellation signal CS and the abnormality detection signal AS, into data and transmits the data to the outside of the power conversion system 500f. The transmission may be performed via the Internet.

[0142] The management device 200 constituting the management system 1000 includes a receiving unit 201, a database 202, a data analysis unit 203, and a transmitting unit 204, as shown in FIG.

[0143] 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. Note that the receiving unit 201 can also simultaneously receive data transmitted from each of the power conversion systems 500f owned by a plurality of clients.

[0144] The database 202 sequentially stores data transmitted from the power conversion system 500f. Note that data transmitted separately from a plurality of power conversion systems 500f for different clients may be stored separately in areas in the database 202 designated for each client.

[0145] The data analysis unit 203 performs various analyses of the tendency, frequency, cause, etc. of abnormalities that have occurred in the power conversion system 500f based on the data accumulated in the database 202. As an example of the analysis, a diagnosis of each component may be performed to determine whether the power conversion device 80 should be replaced because it has a high failure frequency.

[0146] The transmission unit 204 transmits the analysis result of the data analysis unit 203 to an external device outside the management system 1000, for example, via the Internet. The transmission destination may be a management system of a client that operates the power conversion system 500f.

[0147] In the noise filter 100f constituting the power conversion system 500f, as described above, when an abnormality is detected, the abnormality detection unit 17 transmits an abnormality detection signal AS, and the protection circuit 18 operates to perform a protective operation of cutting off the connection between the cancellation signal generation unit 16 and the cancellation signal injection unit 14, thereby achieving high reliability in the power conversion system 500f.

[0148] However, in a situation where the above-described protective operation occurs frequently, it is essential to find the cause of the abnormality and take measures corresponding to the cause, and this is also important for improving the reliability of the power conversion system. When the management system 1000 according to the fifth embodiment is applied, the data transmitted from the power conversion system 500f to the management device 200 is analyzed by the data analysis unit 203, and for example, the cause of the abnormality can be identified and a countermeasure to resolve the abnormality can be proposed, thereby making it possible to eliminate the cause of the abnormality at an early stage, and thus the reliability of the power conversion system 500f can be further improved.

[0149] Furthermore, by using the management system 1000 according to the fifth embodiment, it becomes possible to grasp the operating state of the power conversion system 500f remotely, thereby facilitating management and maintenance of the power conversion system 500f. Furthermore, for the client operating the power conversion system 500f, the analysis results of an abnormality by the management device 200 and countermeasures can be easily obtained, for example, via the Internet. This makes it possible to perform maintenance, inspection, etc. of the power conversion system 500f at an appropriate time, or to reduce the frequency of maintenance, inspection, etc., thereby simultaneously realizing labor savings.

[0150] <Advantages of the Fifth Embodiment> As described above, the management system 1000 according to the fifth embodiment has the management device 200 that performs data analysis using data transmitted from the power conversion system 500f, and therefore it is possible to quickly deal with the cause of the abnormality, which has the effect of further improving the reliability of the power conversion system 500, and also has the effect of improving the maintainability, such as the management and maintenance of the power conversion system.

[0151] Embodiment 6 A power conversion system 500g according to the sixth embodiment will be described with reference to Fig. 30. Fig. 30 is a configuration diagram illustrating the power conversion system 500g according to the sixth embodiment. The power conversion system 500g according to the sixth embodiment differs from the power conversion system 500 according to the first embodiment in that a power conversion device 80a includes a prediction calculation unit 181 and an abnormality estimation unit 182. The configuration of the noise filter 100 is the same as that of the first embodiment.

[0152] When the noise filter 100 falls into an abnormal state, that is, when the abnormality detection unit 17 of the noise filter 100 transmits an abnormality detection signal AS, the prediction calculation unit 181 of the power conversion device 80a recognizes that the noise filter 100 is in an abnormal state and outputs a resonant frequency prediction value based on the abnormality detection signal AS. The prediction calculation unit 181 can also take measures such as varying the switching frequency based on the resonant frequency prediction value.

[0153] When the abnormality detection signal AS continues for a predetermined period or longer, the abnormality estimation unit 182 of the power conversion device 80a outputs an abnormality continuation determination value. Furthermore, it is also possible to stop the operation of the power conversion device 80a based on the abnormality continuation determination value.

[0154] <Advantages of Sixth Embodiment> As described above, according to the power conversion system of embodiment 6, a prediction calculation unit and an abnormality estimation unit are provided inside the power conversion device, so that it is possible to respond to abnormal conditions on the power conversion device side as well, thereby achieving the effect of providing a highly reliable power conversion system.

[0155] Although the present disclosure describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to application to a particular embodiment, but may be applied to the embodiments alone or in various combinations.

[0156] Therefore, countless variations not illustrated are conceivable within the scope of the technology disclosed in the present specification, including, for example, cases where at least one component is modified, added, or omitted, and cases where at least one component is extracted and combined with components of another embodiment. [Explanation of symbols]

[0157] 1 AC power supply, 2, 11, 11A, 11B circuit, 3 grounding wire, 12 noise detection section, 12a, 12b, 12c, 12e detection capacitor, 12d T-phase winding, 12f star connection point, 12n detection capacitor network, 13 cancellation signal output section, 14, 14A1, 14A2, 14A3, 14B1, 14B2, 14B3 cancellation signal injection section, 14a R-phase winding, 14b S-phase winding, 14c T-phase winding, 14d injection winding, 14g injection transformer, 15 grounding capacitor, 16 cancellation signal generation section, 16a input resistor, 16b operational amplifier, 16c feedback resistor, 17 abnormality detection section, 18 protection circuit, 18a protection relay, 18b terminating impedance, 19 control power supply, 20 filter section, 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 detection unit, 171a, 171b Operational amplifier, 171c, 171d, 171e, 171h, 171i, 171j, 171m, 171l Resistor, 171f, 171g Diode, 171k Capacitor, 172 Feature comparison unit, 172a comparator, 172b DC voltage source, 172c pull-up resistor, 181 prediction calculation unit, 182 abnormality estimation unit, 200 management device, 201 receiving unit, 202 database, 203 data analysis unit, 204 transmitting 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 cancellation signal, CV feature signal, DS noise detection signal

Claims

1. A noise filter provided in either an electric path connecting an AC or DC power source and a power conversion device that converts power output from the AC or DC power source into AC or DC power required to drive a load, or an electric path connecting the power conversion device and a load, a noise detection unit that detects common mode noise generated during operation of the power conversion device; a cancellation signal generation unit that generates a cancellation signal that cancels the common mode noise; a cancellation signal injection unit that injects the cancellation signal into the electrical path; an abnormality detection unit that outputs an abnormality detection signal when detecting that the cancellation signal is abnormal; a protection circuit including a protection relay and a terminating impedance having one end connected to the protection relay, and which executes an abnormality processing sequence by switching a relay contact of the protection relay based on the abnormality detection signal to separate the cancellation signal injection unit from the cancellation signal generation unit and bring the noise cancellation into a stopped state in which the cancellation signal injection unit and the terminating impedance are connected; The noise filter executes an abnormality processing sequence based on the abnormality detection signal.

2. A noise filter provided in either an electric path connecting an AC or DC power source and a power conversion device that converts power output from the AC or DC power source into AC or DC power required to drive a load, or an electric path connecting the power conversion device and a load, a noise detection unit that detects common mode noise generated during operation of the power conversion device; a cancellation signal generation unit that generates a cancellation signal that cancels the common mode noise; a cancellation signal injection unit that injects the cancellation signal into the electrical path; an abnormality detection unit that outputs an abnormality detection signal when detecting that the cancellation signal is abnormal, a noise filter that executes an abnormality processing sequence based on the abnormality detection signal, the abnormality processing sequence being a sequence in which the power conversion device determines an abnormality based on the abnormality detection signal and varies a switching frequency based on a resonance frequency predicted by a prediction calculation unit provided in the power conversion device.

3. A noise filter provided in either an electric path connecting an AC or DC power source and a power conversion device that converts power output from the AC or DC power source into AC or DC power required to drive a load, or an electric path connecting the power conversion device and a load, a noise detection unit that detects common mode noise generated during operation of the power conversion device; a cancellation signal generation unit that generates a cancellation signal that cancels the common mode noise; a cancellation signal injection unit that injects the cancellation signal into the electrical path; an abnormality detection unit that outputs an abnormality detection signal when detecting that the cancellation signal is abnormal, a noise filter that executes an abnormality processing sequence based on the abnormality detection signal, wherein a plurality of the cancellation signal injection units are provided, the plurality of cancellation signal injection units arranged in series are further arranged in parallel with respect to the electrical path, and the plurality of parallel cancellation signal injection units are the same number.

4. 2. The noise filter according to claim 1, wherein the termination impedance is set to an impedance value that prevents magnetic saturation of an injection transformer that constitutes the cancellation signal injection unit when the protection circuit operates.

5. 4. The noise filter according to claim 1, wherein the abnormality detection unit determines that an abnormality has occurred 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, and outputs the abnormality detection signal.

6. 5. The noise filter according to claim 1, wherein the abnormality processing sequence is a sequence that activates the protection circuit based on the abnormality detection signal, blocks injection of a cancellation signal into the electrical path, and connects both ends of the cancellation signal injection section to the terminating impedance.

7. 4. The noise filter according to claim 1, wherein the noise filter is provided on the electric path on an output side of the power conversion device.

8. 4. The noise filter according to claim 1, wherein the noise filter is provided on the electrical path on an input side of the power conversion device.

9. 8. The noise filter according to claim 7, wherein a filter section is provided between the noise detection section and the cancellation signal generation section.

10. a power conversion device that converts power output from an AC or DC power source into AC or DC power; A noise filter according to any one of claims 1 to 3; A power conversion system comprising:

11. a power conversion device that converts power output from an AC or DC power source into AC or DC power; the noise filter further comprising a communication unit connected to a cancellation signal output unit constituting the noise filter according to any one of claims 1 to 3 and configured to transmit data to an external device; a management device having a database for storing the data transmitted from the communication unit and a data analysis unit for analyzing the data; A management system comprising:

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