Noise filter

Abstract

An active filter circuit is connected to a power reception end of a power line that supplies AC power supplied from an AC power system or a DC power source interconnected with the AC power system or DC power supplied from the DC power source to a power conversion device, reduces a harmonic component of conducted noise propagated to the power line, and outputs to the power line, and a control section monitors a state change of input power input to a power module that generates driving power of an active element constituting the active filter circuit or a state change of the driving power supplied from the power module, and diagnoses an abnormality of circuit operation of a circuit including the active element of the active filter circuit based on the state change of the input power or the state change of the driving power.

Description

Technical Field

[0001] This invention relates to noise filters that suppress conducted noise in power regulators. Background Technology

[0002] Previously, a power conversion device (power regulator) was known that converts DC power to AC power (or from AC to DC) in a power system equipped with DC power sources such as solar power modules and batteries, and interconnected with commercial power supplied from the system. In this power conversion device, noise filters are installed at the input and output sides of both the supplied DC and AC power sources to suppress conducted noise such as common-mode noise and constant-mode noise.

[0003] Here, a typical noise filter is as follows: Figure 12 As shown, it is constructed using passive components. Specifically, the noise filter is constructed using a reactor (CMC: common-mode coil) that functions as a common-mode filter, capacitors (Cx1, Cy1, Cy2) located on the input side of the reactor, and capacitors (Cx2, Cy3, Cy4) located on the output side. The capacitors Cx1 on the input side and Cx2 on the output side function as X capacitors connected between the power lines, suppressing common-mode noise. The capacitors Cy1 and Cy2 on the input side and Cy3 and Cy4 on the output side function as Y capacitors, connecting each power line to the rack ground (FG) as a reference potential and dissipating the common-mode noise current of each power line to the reference potential such as FG. The reactor, the Y capacitors on the input side, and the Y capacitors on the output side constitute an LC filter.

[0004] In passive filters constructed with such passive components, for example, when the converted power is large (e.g., several kW), the current flowing through the reactor constituting the passive filter increases relatively, thereby increasing the thickness of the reactor wire. If the reactor wire becomes relatively thicker, the noise filter, including reactors such as CMCs, becomes larger, and the power conversion device in which this noise filter is constructed is also forced to become larger. As a recent trend, there is a desire for miniaturization of power conversion devices, leading to the mainstream adoption of hybrid noise filters that combine passive filters and active filters made of passive components to suppress size while achieving miniaturization.

[0005] However, active filters, due to the inclusion of active components such as operational amplifiers and transistors, are relatively more prone to failure compared to passive filters constructed from passive components. Therefore, in the event of an active filter failure, conducted noise that should have been suppressed by the noise filter may increase. Consequently, for example, if the power conversion device continues to operate while the active filter is faulty, conducted noise may propagate to surrounding equipment interconnected with the power conversion device, potentially causing malfunctions in that equipment.

[0006] It should be noted that the following patent documents exist as prior art documents that describe technologies related to the technologies described in this specification.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2003-88099

[0010] Patent Document 2: International Publication No. 2018 / 109801 Summary of the Invention

[0011] The technical problem that the invention aims to solve

[0012] The present invention was made in view of the problems mentioned above, and its object is to provide a technique capable of detecting faults in noise filters that include active filters in their construction and preventing conducted noise from propagating to surrounding devices.

[0013] Technical solutions for solving technical problems

[0014] The noise filter of the present invention, which is used to solve the above-mentioned technical problems, is characterized by comprising:

[0015] An active filter circuit is connected to the receiving end of a power line supplying AC power from an AC power system or a DC power source interconnected with the AC power system to a power conversion device, or supplying DC power from the DC power source, to reduce the harmonic components of conducted noise propagating to the power line and outputting it to the power line; and

[0016] The control unit monitors the state changes of the input power supplied to the power supply module that generates drive power for the active elements constituting the active filter circuit, or the state changes of the drive power supplied from the power supply module, and diagnoses any abnormalities in the circuit operation of the circuit including the active elements of the active filter circuit based on the state changes of the input power or the drive power.

[0017] Therefore, it is possible to monitor the behavior of a power module connected to the power receiving end of a power line supplying AC power from an AC power system or a DC power source interconnected with the AC power system to a power conversion device, or supplying DC power from the DC power source, and to diagnose any faults (abnormalities) or normal operation of the active filter. According to the present invention, it is possible to detect faults in noise filters that include active filters in their configuration.

[0018] Furthermore, in this invention, the control unit may stop the operation of the power conversion device when it diagnoses an abnormality in the operation of the active filter circuit including the active element based on a change in the state of the drive power. This allows the operation of a power conversion device that includes a noise filter in its configuration to be stopped when the active filter is diagnosed as faulty. According to this invention, it is possible to prevent conducted noise from propagating to surrounding equipment due to a fault in the active filter.

[0019] Furthermore, in this invention, the control unit may continue to operate the power conversion device when it diagnoses, based on the state change of the drive power, that the active filter circuit including the active element is operating normally. Thus, when the active filter is diagnosed as normal, the continued operation of the power conversion device improves its operating efficiency and reduces the harmonic components of conducted noise propagating to the power line through the active filter.

[0020] Furthermore, in this invention, the power supply module may have a positive power supply that generates a positive side voltage and a negative power supply that generates a negative side voltage. Additionally, the control unit may monitor the state changes of the drive power supplied from the power supply module based on at least one of the following current values: a first current value flowing from the positive power supply of the power supply module into the reference potential side; a second current value flowing from the negative power supply of the power supply module into the reference potential side; and a third current value flowing from the connection point connecting the negative electrode of the positive power supply and the positive electrode of the negative power supply into the reference potential side. Thus, the state changes of the drive power supplied from the power supply module can be monitored based on any one of the following current values: the first current value (Ip) flowing from the positive power supply of the power supply module into the reference potential side; the second current value (In) flowing from the negative power supply into the reference potential side; and the third current value (Ig) flowing from the connection point connecting the negative electrode of the positive power supply and the positive electrode of the negative power supply into the reference potential side.

[0021] Furthermore, in this invention, the control unit may diagnose abnormalities in the circuit operation of the active filter circuit, including the active components, based on a first current value flowing from the positive power supply of the power module into the reference potential side, a second current value flowing from the negative power supply of the power module into the reference potential side, and a third current value flowing from the connection point connecting the negative electrode of the positive power supply and the positive electrode of the negative power supply into the reference potential side. Thus, the noise filter can improve the diagnostic accuracy of fault diagnosis.

[0022] Furthermore, in this invention, the control unit may determine that the circuit including the active element of the active filter circuit is operating normally when the first current value or the second current value is above a first threshold and below a second threshold greater than the first threshold. Therefore, fault diagnosis can be performed using the first current value or the second current value within a specified range (a range above the first threshold and below the second threshold greater than the first threshold).

[0023] Furthermore, in this invention, the control unit may determine that the circuit including the active element of the active filter circuit is operating normally when the third current value is above a third threshold and below a fourth threshold greater than the third threshold. Therefore, fault diagnosis can be performed using a third current value within a specified range (a range above the third threshold and below the fourth threshold greater than the third threshold).

[0024] Furthermore, this invention may also include a passive filter that reduces common-mode noise propagating in the power conversion device side of the power line supplying AC power from an AC power system or a DC power source interconnected with the AC power system to the power conversion device, or the power line supplying DC power from the DC power source. Accordingly, a hybrid noise filter can be realized that can suppress common-mode noise using a passive filter and suppress harmonic components included in conducted noise using an active filter.

[0025] Invention Effects

[0026] According to the present invention, it is possible to detect faults in noise filters that include active filters in their configuration and to prevent conducted noise from propagating to surrounding equipment. Attached Figure Description

[0027] Figure 1 This is a block diagram illustrating a simplified configuration of the power supply system in Embodiment 1 of the present invention.

[0028] Figure 2 This is a block diagram illustrating a simplified circuit configuration of a noise filter according to Embodiment 1 of the present invention.

[0029] Figure 3This is a diagram illustrating the monitoring of the behavior of the power supply for the filter in Embodiment 1 of the present invention.

[0030] Figure 4 This is an example of a graph simulating the change in current value caused by a fault in the active filter in Embodiment 1 of the present invention.

[0031] Figure 5 This is another example of a graph simulating the change in current value caused by a failure of the active filter in Embodiment 1 of the present invention.

[0032] Figure 6 This is another example of a graph simulating the change in current value caused by a failure of the active filter in Embodiment 1 of the present invention.

[0033] Figure 7 This is an example of a table summarizing the fault determination conditions of the active filter in Embodiment 1 of the present invention.

[0034] Figure 8 This is a flowchart illustrating an example of fault diagnosis processing for a noise filter in Embodiment 1 of the present invention.

[0035] Figure 9 This is a block diagram illustrating a simplified configuration of the noise filter in Embodiment 2 of the present invention.

[0036] Figure 10 This is a block diagram illustrating a simplified configuration of a noise filter in a modified example of Embodiment 2 of the present invention.

[0037] Figure 11 This is an example of a graph illustrating the change in the primary-side current value due to a fault in the active filter, as described in a variation of Embodiment 2 of the present invention.

[0038] Figure 12 This is a diagram illustrating the structure of existing passive filters. Detailed Implementation

[0039] [Application Example]

[0040] Hereinafter, application examples of the present invention will be described with reference to the accompanying drawings.

[0041] Figure 1 This is a block diagram of a power supply system 100 that includes a power conversion device 102 employing the noise filter 1 described in the application example of the present invention. Figure 1 An example is shown of a simplified configuration of a power supply system capable of interconnection, in which a DC power source 101 supplying DC power and a commercial power system (hereinafter also referred to as "the system") 103 supplying AC power are interconnected.

[0042] The power conversion device 102 includes a DC-DC converter 102b and an inverter 102c for converting DC power supplied from DC power source 101 into AC power synchronized with the power supplied from the system, or converting AC power supplied from the system into DC power synchronized with the power supplied from DC power source 101. Furthermore, the power conversion device 102 includes noise filters such as DCF 102a and ACF 102d for suppressing conducted noise (common-mode noise, constant-mode noise) generated by the conversion processes from DC to AC or from AC to DC (boost-buck conversion, frequency conversion, etc.). DCF 102a is located at the input / output terminal on the DC power source 101 side of the power conversion unit 102, while ACF 102d is located at the input / output terminal on the system 103 side of the power conversion unit 102. Although DCF 102a and ACF 102d differ in voltage and current specifications due to the difference between DC and AC, the components constituting their respective circuits are roughly the same.

[0043] Figure 2 This is a block diagram illustrating a simplified circuit configuration of a noise filter 1 according to an application example of the present invention. Figure 2 As shown, the noise filter 1 in the application example of the present invention is configured as a hybrid noise filter combining a passive filter 20 and an active filter 10. The passive filter 20 of the noise filter 1 is provided, for example, on the noise source side (power conversion circuit (DC-DC converter 102b, inverter 102c, etc.)) to suppress common-mode noise current propagating in the power lines connected to terminals 20a and 20b. Furthermore, the active filter 10 in the application example of the present invention is connected to terminals 20c and 20d of the power line on the side of the power source (DC power supply 101, system 103) supplied with DC or AC power to the passive filter 20, and detects the high-frequency components of conducted noise propagating to the power line, thereby reducing the harmonic current corresponding to these high-frequency components. The active filter 10 includes active components such as an operational amplifier 13a, transistor TR1, and transistor TR2 in its circuit configuration.

[0044] The active filter 10 according to the application example of the present invention includes a dual power supply module in its constituent elements. This dual power supply module has a positive power supply P1 that supplies power with a positive voltage (Vp) for driving the active components and a negative power supply P2 that supplies power with a negative voltage (Vn). Furthermore, the noise filter 1 according to the application example of the present invention includes an anomaly detection unit 30 for monitoring the behavior of the power supply that supplies operating power to the active components of the active filter 10, and for measuring the current value of the power supplied from the aforementioned power supply module to the active components constituting the active filter 10. Specifically, as... Figure 3As shown, the current value (Ip) flowing from the positive power supply P1 into the reference potential FG side and the current value (In) flowing from the negative power supply P2 into the reference potential FG side are measured. In addition, the current value (Ig) flowing from the connection point where the negative electrode of the positive power supply P1 and the positive electrode of the negative power supply P2 connects into the reference potential FG side is measured.

[0045] like Figures 4 to 6 As shown, in the circuit configuration included in the active filter 10, when an open-circuit fault or a short-circuit fault occurs, the states of the current values ​​Ip, In, and Ig supplied from the dual power supply module to the active components change drastically. In the active filter 10 according to the application example of the present invention, the behavior of the power supply is monitored by measuring at least two of the three current values, namely, current value Ig and current value In or current value Ip, thereby diagnosing the abnormality of the active filter 10.

[0046] Figure 7 The table below shows a summary of fault determination conditions for each of the current values ​​Ip, In, and Ig in the fault diagnosis section of the active filter 10. In the noise filter 1 according to the application example of the present invention, the current measurement function 31 of the anomaly detection unit 30 measures at least the current value Ig and the current value In or the current value Ip. Then, the anomaly diagnosis function 32 of the anomaly detection unit 30 uses the fact that each measured current value is within a predetermined determination threshold as a determination condition to diagnose a fault in the active filter 10. In the noise filter 1 according to the application example of the present invention, when the active filter 10 is diagnosed as normal, the operation of the power conversion device 100, which includes the noise filter 1 in its configuration, continues. On the other hand, when the active filter 10 is diagnosed as faulty, the operation of the power conversion device 100, which includes the noise filter 1 in its configuration, is stopped. As a result, in the noise filter 1 according to the application example of the present invention, it is possible to detect faults in the noise filter that includes the active filter in its configuration and to prevent the propagation of conducted noise to surrounding equipment.

[0047] [Example 1]

[0048] Hereinafter, the noise filter of the power conversion device according to the embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0049] <System Composition>

[0050] Figure 1 This is a block diagram showing a simplified configuration of the power system 100 installed within the desired building structure. Figure 1The power system 100 shown is a system interconnection system that interconnects a DC power supply 101 that supplies direct current (DC) power and a commercial power system (hereinafter also referred to as "the system") that supplies alternating current (AC) power 103. The power system 100 includes a power conversion device (power regulator) 102, which converts the DC power supplied from the DC power supply 101 (such as from solar power modules, batteries, EVs, etc.) into specified AC power (e.g., single-phase three-wire 200 / 100V). The specified AC power converted by the power conversion device 102 is supplied, for example, to lighting equipment, loads, etc. (not shown) installed in the desired building structure, or to the interconnected system 103. Additionally, the power conversion device 102 converts the AC power supplied from the system 103 into specified DC power. The DC power converted by the power conversion device 102 is then supplied to batteries, EVs, etc., which are interconnected as the DC power supply 101.

[0051] The power conversion device 102 includes a DC-DC converter 102b and an inverter 102c for converting DC power supplied from DC power source 101 into AC power synchronized with the power supplied from the system, or converting AC power supplied from the system into DC power synchronized with the power supplied from DC power source 101. Additionally, the power conversion device 102 includes noise filters such as DCF 102a and ACF 102d for suppressing conducted noise (common-mode noise, constant-mode noise) generated during the conversion processes (boost-buck conversion, frequency conversion, etc.) from DC power to AC power or from AC power to DC power. DCF 102a is located at the input / output terminal on the DC power source 101 side of the power conversion unit 102, while ACF 102d is located at the input / output terminal on the system 103 side of the power conversion unit 102. Although DCF 102a and ACF 102d differ in voltage and current specifications due to the difference between DC and AC, the components constituting their respective circuits are roughly the same. Hereinafter, DCF102a and ACF102d will be collectively referred to as "noise filters".

[0052] <Noise Filter Construction>

[0053] Figure 2 This is a block diagram illustrating a simplified circuit configuration of the noise filter involved in this embodiment. Figure 2The noise filter 1 shown is a hybrid noise filter comprising a passive filter 20 and an active filter 10. The active filter 10 detects the high-frequency components of conducted noise propagating to the power line and functions to reduce the harmonic current corresponding to these high-frequency components. The noise filter 1 of this embodiment combines a passive filter 20 composed of passive components and an active filter 10 comprising operational amplifiers, transistors, and other active components in its circuit configuration, thereby achieving miniaturization even when performing power conversion at the several kW level. Furthermore, the noise filter 1 of this embodiment further includes an anomaly detection unit 30, which monitors the behavior of the power supply that provides operating power to the active components of the active filter 10. For example, the anomaly detection unit 30 measures the current value of the power supply to the active components in the noise filter 1 when it is energized. Then, based on the state changes of the measured current value, the anomaly detection unit 30 diagnoses an anomaly in the active filter 10, including the active components.

[0054] In the noise filter 1 of this embodiment, the passive filter 20 is disposed on the noise source side of the power conversion device 102. For example, when the noise filter 1 is used as... Figure 1 When the DFC102a is functioning as shown, the power lines connecting the DC-DC converter 102b of the power conversion device 102 and the DFC102a are connected to terminals 20a and 20b of the passive filter 20. Furthermore, the power lines connecting the DFC and the DC power supply 101, which serves as a DC power source, are connected to terminals 20c and 20d of the passive filter 20. On the other hand, when the noise filter 1 functions as… Figure 1 When the AFC102d is functioning as shown, the power lines connecting the inverter 102c of the power conversion device 102 and the AFC102d are connected to terminals 20a and 20b of the passive filter 20. Furthermore, the power lines connecting the AFC and the system 103, which serves as an AC power source, are connected to terminals 20c and 20d of the passive filter 20.

[0055] The passive filter 20 is constructed using a reactor CMC as a passive element, capacitors (C1, C2) disposed on the noise source side, and capacitors (C3, C4) disposed on the DC power source (DC power supply 101) or AC power source (system 103) side. The capacitors C1 and C2 disposed on the noise source side and the capacitors C3 and C4 disposed on the DC or AC power source side function as Y capacitors connecting each power line and the rack ground (FG) as a reference potential, and dissipating common-mode noise current propagating in each power line to the reference potential such as FG. The reactor CMC, the Y capacitor disposed on the noise source side of the reactor, and the Y capacitor disposed on the power source side constitute an LC filter.

[0056] In this embodiment, the active filter 10 and the passive filter 20 are connected to terminals 20c and 20d of the power lines supplied with DC or AC power by the power source (DC power supply 101, system 103). The active filter 10 includes a circuit configuration that functions as a filter power supply 11, a detection unit 12, an amplification unit 13, and an injection unit 14. The filter power supply 11 is a dual power supply module that includes a positive power supply P1 that supplies positive voltage (Vp) and a negative power supply P2 that supplies negative voltage (Vn). The connection point between the negative electrode of the positive power supply P1 and the positive electrode of the negative power supply P2 is grounded to a rack ground (FG) or the like, which serves as a reference potential.

[0057] The detection unit 12 of the active filter 10 detects the high-frequency component of conducted noise propagating to the power supply (DC power supply 101, system 103) side of the passive filter 20 combined with it. Then, the detected high-frequency component is output to the amplification unit 13. One end of capacitor C5 constituting the detection unit 12 is connected to terminal 20c of the power supply line, and one end of capacitor C6 is connected to terminal 20d of the power supply line. Furthermore, the other ends of capacitor C5 connected to terminal 20c and capacitor C6 connected to terminal 20d are grounded to a reference potential (FG, etc.) through resistor R1. Here, capacitor C5 and resistor R1 constitute a high-pass filter (HPF) that allows the high-frequency component of conducted noise propagating to the power supply line connected to terminal 20c to pass through, and capacitor C6 and resistor R1 constitute a high-pass filter (HPF) that allows the high-frequency component of conducted noise propagating to the power supply line connected to terminal 20d to pass through. The high-frequency component of the conducted noise after passing through the high-pass filters is output to the amplification unit 13 as a voltage fluctuation corresponding to the high-frequency component through capacitor C7 and resistor R2 connected in series.

[0058] The amplification section 13 is an amplifier circuit that includes an operational amplifier 13a and active components such as an NPN transistor TR1 and a PNP transistor TR2 in its circuit configuration. A positive voltage (Vp) and a negative voltage (Vn) are supplied from the filter power supply 11 to the operational amplifier 13a as driving power. Similarly, the positive voltage (Vp) of the filter power supply 11 is supplied to the collector of transistor TR1 as driving power, and the negative voltage (Vn) of the filter power supply 11 is supplied to the collector of transistor TR2.

[0059] The voltage fluctuation based on high-frequency components output from the detection unit 12 is input to the inverting input terminal 2 of the operational amplifier 13a. Furthermore, a reference voltage for differential operation, grounded to the reference potential FG via resistor R3, is input to the non-inverting input terminal 3 of the operational amplifier 13a. The operational amplifier 13a differentially amplifies the difference between the current fluctuation input to the inverting input terminal 2 and the reference voltage input to the non-inverting input terminal 3 and outputs it to the output terminal 1. It should be noted that an anti-parallel circuit consisting of diodes D1 and D2 is connected to the inverting input terminal 2 of the operational amplifier 13a for input overvoltage protection. The differential voltage output from the output terminal 1 is input to the bases of transistors (TR1 and TR2) whose emitters are interconnected via resistor 4 for current amplification. The base of transistor TR1 is connected to the anode of diode D3, and the base of transistor TR2 is connected to the cathode of diode D4. The differential voltage output from the output terminal 1 is connected to the cathode side of diode D3 and the anode side of diode D4. Furthermore, a positive voltage (Vp) is applied to the anode side of diode D3 through resistor R5, and a negative voltage (Vn) is applied to the cathode side of diode D4 through resistor R6. Due to the voltage variation of the differential voltage, the current between the emitter / base of transistors TR1 and TR2 changes. Between the collector / emitter, the collector current, corresponding to the amplification of the transistor, is output as a harmonic current. The harmonic current output from the emitters of transistors TR1 and TR2 is fed back to the inverting input terminal 2 of operational amplifier 13a via a low-pass filter composed of resistor R7 and capacitor C8. As a result, the active filter 10 controls the output current of the active filter 10 according to the harmonic current fed back to the inverting input terminal 2, thereby reducing the harmonic current flowing through the power lines connecting terminals 20c and 20d.

[0060] It should be noted that the output current from the emitter of each transistor is input to the injection section 14. The output current input to the injection section 14 is injected into the power line connected to terminal 20c through resistor R8 and capacitor C9, and into the power line connected to terminal 20d through resistor R8 and capacitor C10.

[0061] The anomaly detection unit 30 is a control module that has a current measurement function 31 and an anomaly diagnosis function 32. A typical example of the anomaly detection unit 30 is a microcomputer for control. The anomaly detection unit 30 monitors the behavior of the positive voltage (Vp) and negative voltage (Vn) supplied from the filter power supply 11 to each active element in order for the active filter 10 to function, and diagnoses the anomalies of the active filter.

[0062] Figure 3 This diagram illustrates the monitoring of the power supply behavior supplied to each active component from the filter power supply 11 as driving power. (See diagram for example.) Figure 2 As shown, the behavior of the power supplied from the filter power supply 11 to each active component can be monitored, for example, by measuring the current value (Ip) flowing from the positive power supply P1 into the reference potential FG side and the current value (In) flowing from the negative power supply P2 into the reference potential FG side. Furthermore, the behavior of the power supplied to each active component can also be monitored by measuring the current value (Ig) flowing from the connection point connecting the negative electrode of the positive power supply P1 and the positive electrode of the negative power supply P2 into the reference potential FG side.

[0063] It should be noted that the behavior of the filter power supply 11 can also be monitored, for example, by measuring the positive voltage (Vp) and negative voltage (Vn). The characteristics of the dual power supply module used in the filter power supply 11 can be configured, for example, by a power supply whose voltage drops due to an increase in the current flowing into the reference potential (FG) side during a fault. Furthermore, the current waveform of the current value (Ig) flowing into the reference potential FG side from the connection point connecting the negative electrode of the positive power supply P1 and the positive electrode of the negative power supply P2 can be used as the monitoring object. For example, a fault in the active filter 10 can be detected if a current waveform dominated by a DC component and lacking an AC component is observed.

[0064] In the circuit configuration of the active filter 10, the amplification section 13, which includes the operational amplifier 13a and transistors (TR1, TR2) as active components, is a relatively easy part of the circuit to fail. Furthermore, the injection section 14, where the output current controlled by the active filter 10 to reduce harmonic current is injected into the power line, is composed of passive components and can also be considered a part where a failure would significantly impact peripheral devices. Therefore, the anomaly detection unit 30 of the noise filter 1 measures the current values ​​Ip, In, and Ig from the filter power supply 11 using the current measurement function 31. Then, the anomaly detection unit 30 diagnoses anomalies in the active filter 10, which uses the amplification section 13 and injection section 14 as monitoring components, based on the anomaly diagnosis function 32.

[0065] Next, refer to Figures 4 to 6 The changes in current values ​​caused by the failure of the active filter 10 are explained. Figure 4 This is an example of a graph showing the current change when the injection section 14 of the simulated active filter 10 experiences an open-circuit (disconnected state) fault. As an example of an open-circuit fault in the injection section 14, damage to resistor R8 due to overcurrent is shown. Figure 4 The vertical axis of the simulation graph represents the current value (mA), and the horizontal axis represents time (μsec). Figure 4 In the graph, the dashed line represents the current value during normal operation, while the solid line represents the current value during a fault. It should be noted that... Figure 4The vertical and horizontal axis properties of the graph showing current changes, as well as the graph's display properties, also apply to this. Figure 5 , Figure 6 .

[0066] exist Figure 4 In the event of an open-circuit failure in the injection unit 14, the current values ​​Ip and In flowing through the filter power supply 11 become approximately zero due to the fluctuation caused by the AC component, resulting in a continuously measured current value. Furthermore, the current value Ig also exhibits approximately zero fluctuation due to the AC component, and the current flowing into the reference potential FG is approximately zero. It should be noted that, as shown by the dashed line, the fluctuation of the current value Ig under normal conditions is relatively large compared to the fluctuations of the current values ​​Ip and In under normal conditions. Therefore, during the operation of the power conversion device 102, an open-circuit failure in the injection unit 14 can be detected based on the fluctuation of the current value Ig measured from the filter power supply 11. However, as shown by the solid line, during a fault, the current values ​​Ip and In also become a constant current state with approximately zero fluctuation caused by the AC component; therefore, the open-circuit failure in the injection unit 14 can be detected based on the measurement of this constant current state.

[0067] Figure 5 This is an example of a graph showing the current change on the positive voltage (Vp) side of the operational amplifier 13a, which constitutes the amplification section 13 of the active filter 10, when a short-circuit fault occurs. For example... Figure 5 As shown, the normal current value Ip, including fluctuations caused by the AC component, shifts to around -10mA, and the current value Ig, also including fluctuations caused by the AC component, shifts to around 0mA. Furthermore, in the event of a short-circuit fault, both current values ​​Ip and Ig shift significantly towards the negative current side (approximately 120mA in the illustrated example). Conversely, the current value In decreases slightly before and after the fault, shifting to around 10mA, including fluctuations caused by the AC component. Therefore, based on the changes in the current values ​​Ip and Ig measured from the filter power supply 11 of the power conversion device 102, short-circuit faults on the positive voltage (Vp) side of the operational amplifier 13a can be detected.

[0068] Figure 6 This is an example of a graph illustrating the current changes of the transistors (TR1, TR2) that constitute the amplification section 13 of the active filter 10 when a short-circuit fault occurs. For example... Figure 6As shown, under normal conditions, each current value, including the fluctuation caused by the AC component, tends to move around 0 mA. However, in the event of a short-circuit fault, the current value Ip shifts significantly towards the negative current side (approximately 600 mA in the illustrated example), and the current value In shifts significantly towards the positive current side (approximately 600 mA). It should be noted that even in the event of a fault, the current value Ig also tends to move around 0 mA, including the fluctuation caused by the AC component. Therefore, based on the state changes of the current values ​​Ip and In measured from the filter power supply 11 of the power conversion device 102, short-circuit faults in the transistors (TR1, TR2) constituting the amplification section 13 can be detected.

[0069] Figure 7 The results of simulations performed on the amplification section 13 and injection section 14 of the active filter 10 for open-circuit faults and short-circuit faults, respectively, are shown. Figure 7 In the section on fault diagnosis of active filter 10, an example is shown of a table summarizing the fault determination conditions for each of the current values ​​Ip, In, and Ig.

[0070] like Figure 7 As shown, open-circuit and short-circuit faults in the transistors (TR1, TR2) of the amplification section 13 can be diagnosed using measurements of the electrical power value Ip or In. Furthermore, open-circuit faults in the operational amplifier 13a of the amplification section 13 can be diagnosed using measurements of the electrical power value Ip or In, and short-circuit faults can be diagnosed using measurements of at least two of the current values ​​Ip, In, and Ig. Open-circuit and short-circuit faults in the injection section 14 can be diagnosed using measurements of the electrical power value Ig. Therefore, in the anomaly detection unit 30 of the noise filter according to this embodiment, anomalies in the active filter 10 can be diagnosed by using measurements of at least two of the current values ​​Ip, In, and Ig (electrical power value Ig and electrical power value Ip or electrical power value In).

[0071] Furthermore, regarding open-circuit faults in the transistors (TR1, TR2) of the amplification section 13, the fault is determined by the condition that the measured power value Ip or power value In is less than the threshold A. On the other hand, regarding short-circuit faults in the transistors (TR1, TR2) of the amplification section 13, the fault is determined by the condition that the measured power value Ip or power value In exceeds the threshold B.

[0072] Regarding an open-circuit fault in the operational amplifier 13a of the amplification section 13, the fault is determined by the condition that the measured power value Ip or In is less than the threshold A. Conversely, regarding a short-circuit fault in the operational amplifier 13a of the amplification section 13, the fault is determined by the condition that at least two of the measured power values ​​Ip, In, and Ig exceed the threshold B. Furthermore, regarding an open-circuit fault in the injection section 14, the fault is determined by the condition that the measured power value Ig is less than the threshold C. And furthermore, regarding a short-circuit fault in the injection section 14, the fault is determined by the condition that the measured power value Ig exceeds the threshold D.

[0073] It should be noted that for short-circuit faults in operational amplifier 13a, measurements of at least two of the electrical current values ​​Ip, In, and Ig are required. However, if the current measurement accuracy is sufficiently high, then... Figure 5 The current value In shows the current changes during normal and fault conditions. Even with only one current measurement, the fault in that part can be detected.

[0074] It should be noted that the timing for determining the fault of the active filter 10 can be exemplified, for example, before the start of operation of the power conversion device 100, which performs power conversion processing on the power supplied from the interconnected DC power supply 101 and system 102. By detecting the fault of the active filter 10 at this timing, the power conversion device 100 can be stopped from operating, thereby preventing conducted noise generated by the power conversion process from propagating to interconnected peripheral devices.

[0075] Here, after the power conversion device 100 starts operating, an output current controlled by the active filter 10 to reduce harmonic current is injected into the power line via the injection unit 14. Therefore, the timing for fault determination of the injection unit 14 can also be performed after the power conversion device 100 starts operating (during operation). By performing fault determination of the injection unit 14 during operation, it is possible to prevent the harmonic current of conducted noise in the power line, which is normally reduced by the active filter 10, from propagating to peripheral devices if it is not reduced due to a fault in the injection unit 14. It should be noted that the fault determination of the injection unit 14 after the start of operation can be omitted if the fault detection unit 30 does not detect a fault in the injection unit 14.

[0076] <Processing Flow>

[0077] Figure 8 This is a flowchart illustrating an example of fault diagnosis processing in a noise filter according to this embodiment. Figure 8In the process, the noise filter 1 is diagnosed using two current values: Ig and Ip or In. First, if the power conversion device 100 is activated, the noise filter 1 in this embodiment becomes energized, and the filter power supply 11 and the amplification unit 13 are powered on (step S101). When the fault detection unit 30 obtains the measured values ​​of the two current values ​​(Ig and Ip or In) from the energized filter power supply 11 via the current measurement function 31, the process proceeds to step S102. In step S102, it is determined that the measured current value Ip or In is within the range of threshold A to threshold B. If, in step S102, the measured current value Ip or In is within the range of threshold A to threshold B (step S102, "Yes"), the process proceeds to step S103, and the operation of the power conversion device 100 begins. On the other hand, in step S102, if the measured current value Ip or current value In is not within the range of threshold A to threshold B (step S102, "No"), proceed to step S106 to diagnose a fault in the noise filter 1. If, for example, the power conversion device 100, which includes the noise filter 1 in its configuration, is diagnosed as faulty via the abnormality diagnosis function 31, the operation of the power conversion device 100 is stopped.

[0078] After operation begins, in step S104, it is determined that the measured current value Ig is within the range of threshold C to threshold D. If, in step S104, the measured current value Ig is within the range of threshold C to threshold D (step S104, "Yes"), the process proceeds to step S105, and the noise filter 1 is diagnosed as functioning normally. The power conversion device 100, which includes the noise filter 1 in its configuration, continues operation. On the other hand, if, in step S104, the measured current value Ig is not within the range of threshold C to threshold D (step S104, "No"), the process proceeds to step S106, and a fault in the noise filter 1 is diagnosed. The power conversion device 100 stops the operation of the power conversion device 100 that began in step S103. If the processing of steps S105 and S106 is completed, this routine is temporarily terminated.

[0079] As explained above, in this embodiment, the behavior of the power supply 11 for the active filter 10 constituting the noise filter 1 can be monitored, and the malfunction or normality of the active filter 10 can be diagnosed. In this embodiment, if the active filter 10 is diagnosed as normal, the operation of the power conversion device 100, which includes the noise filter 1 in its configuration, continues. On the other hand, if a malfunction is diagnosed in the active filter 10, the operation of the power conversion device 100, which includes the noise filter 1 in its configuration, can be stopped. According to this embodiment, malfunctions of the noise filter, which includes an active filter in its configuration, can be detected, preventing conducted noise from propagating to surrounding equipment.

[0080] Furthermore, in this embodiment, as information for monitoring the behavior of the power supply 11 for the filter, the current value Ip flowing from the positive power supply P1 into the reference potential FG side, the current value In flowing from the negative power supply P2 into the reference potential FG side, and the current value Ig flowing from the connection point connecting the negative electrode of the positive power supply P1 and the positive electrode of the negative power supply P2 into the reference potential FG side can be measured. By measuring the current value Ip or the current value In, open-circuit faults and short-circuit faults in the circuit configuration including active components of the active filter 10 can be diagnosed based on the state changes of the measured value. Furthermore, by measuring the current value Ig, open-circuit faults and short-circuit faults in the circuit configuration not including active components of the active filter 10 can be diagnosed based on the state changes of the measured value. Therefore, according to this embodiment, by measuring at least the current value Ig and the current value Ip or the current value In, it is possible to determine open-circuit faults and short-circuit faults in the circuit configuration not including active components, thus improving the accuracy of fault diagnosis.

[0081] Furthermore, in this embodiment, the timing for determining the fault of the active filter 10 can be performed, for example, before the power conversion device 100 is started and operation begins to convert power supplied from the interconnected DC power supply 101 and system 102. Since the power conversion device 100, which includes a noise filter 1 in its configuration, can diagnose the fault of the active filter 10 before operation begins, it is possible to prevent conducted noise generated during power conversion from propagating to interconnected peripheral devices. According to this embodiment, it is possible to prevent the power conversion device 100 from operating while the active filter 10 is faulty.

[0082] Furthermore, in this embodiment, fault determination of the active filter 10 can be performed after the power conversion device 100 starts operating. Therefore, it is possible to prevent harmonic currents of conducted noise from the power line, which are normally reduced by the active filter 10, from propagating and adversely affecting the operation of peripheral equipment if they are not reduced due to a fault in the active filter 10. According to this embodiment, it is possible to prevent the power conversion device 100 from continuing to operate when the active filter 10 has failed.

[0083] [Example 2]

[0084] Figure 9 This is a block diagram illustrating a simplified configuration of the noise filter 2 according to Embodiment 2. In Embodiment 1, the active filter 10 of the noise filter 1 is configured to include a noise filter power supply 11 as a driving power supply for the active element, and to measure the current values ​​Ip, In, and Ig related to fault diagnosis from this power supply. In Embodiment 2, the noise filter 2 is configured to include an AF circuit 42 consisting of a detection unit 12, an amplification unit 13, and an extraction unit 14 as an active filter. Furthermore, in Embodiment 2, a positive voltage (Vp) and a negative voltage (Vn) are supplied to the AF circuit 42 from an externally located AF power supply 40. Thus, a configuration where a driving power supply for the active element is supplied from an external side can also be used. In addition, the current values ​​Ip and In supplied from the AF power supply 40 to the AF circuit 42 are measured by a microcomputer 41 for controlling the power conversion device 100. In this configuration, the behavior of the AF power supply 40 supplied to the AF circuit 42 can be monitored, just as in Embodiment 1, to diagnose the fault or normal operation of the noise filter 2 including the AF circuit.

[0085] Therefore, the microcomputer 41 for controlling the power conversion device 100 performs fault diagnosis on the AF circuit 42 based on two current values ​​within the measured current values ​​Ip, In, and Ig. If the microcomputer 41 diagnoses the AF circuit 42 as faulty, it can stop the operation of the power conversion circuit 2b. It should be noted that... Figure 9 The power supply 2a shown corresponds to the DC power supply 101 and system 103 of Embodiment 1, and the power conversion circuit 2b corresponds to the DC-DC converter 102b and inverter 102c of Embodiment 1. The power converted by the power conversion circuit 2b is supplied to the load 2c connected to the power conversion device.

[0086] In the noise filter 2 of this embodiment, the circuit configuration does not include the power supply 11 for the filter and the abnormality detection unit 30. Therefore, compared with the noise filter 1 of Embodiment 1, it is possible to achieve relative miniaturization and reduce product cost due to the reduction in the number of components. In addition, the control microcomputer 41 can be equipped with the function of the abnormality detection unit 30, which can suppress power consumption as a power conversion device 100.

[0087] [Variation Example]

[0088] Figure 10 This is a block diagram illustrating a simplified configuration of the noise filter 3 according to a modified example of Embodiment 2. In Embodiment 2, the power conversion device 100 is configured to measure the current value Ip of the positive power supply supplied from the AF power supply 40 to the AF circuit 42, the current value In of the negative power supply, and the current value Ig flowing into the reference potential FG using the control microcomputer 41. Therefore, the reference potential involved in fault detection needs to be the ground potential of the control microcomputer 41. In the modified example, the power supply that supplies power to the AF circuit is configured as an isolated power supply 50b for the AF, and a drive power supply 50a that supplies power to this isolated power supply is also included. Here, as the isolated power supply 50b for the AF, for example, a transformer is shown that converts the power input to the primary side from the drive power supply 50a and outputs the converted power (power for the AF circuit 52) ​​to the secondary side. In addition, in the modified example, the power conversion device 100's control microcomputer 51 is configured to measure the current value Ia supplied to the isolated power supply 50b for the AF. In the event of an open-circuit or short-circuit fault in the AF circuit 52, the power state supplied from the AF isolated power supply 50b changes compared to normal operation. Furthermore, based on the change in the power state on the secondary side, the power state supplied from the drive power supply 50a to the primary side of the AF isolated power supply 50b changes, thus changing the current value Ia supplied to the AF isolated power supply 50b. With this configuration, the behavior of the AF isolated power supply 50b supplied to the AF circuit 52 can be monitored, similar to Embodiment 1, to diagnose faults or normal conditions of the noise filter 3, including the AF circuit.

[0089] Figure 11 This is an example of a graph showing the change in the primary-side current value (Ia) due to a fault in the active filter 10 in a simulated variant. Figure 11 In the diagram, (a) represents the current change when an open-circuit fault occurs in the injection section 14 of the active filter 10; (b) represents the current change when a short-circuit fault occurs on the positive voltage (Vp) side of the operational amplifier 13a constituting the amplification section 13; and (c) represents the current change when a short-circuit fault occurs in the transistors (TR1, TR2) constituting the amplification section 13. Furthermore, in Figure 11 In the graph, the vertical axis represents the current value (mA), and the horizontal axis represents the time (μsec). The dashed line curve represents the current value during normal operation, while the solid line curve represents the current value during a fault.

[0090] like Figure 11 As shown by the dashed arrow in (a), when the injection section 14 is normal, the primary side current value (Ia) varies within a specified amplitude range (roughly ±1mA in the illustrated example). On the other hand, in the event of an open-circuit failure of the injection section 14, the primary side current value (Ia), as shown by the solid arrow, has an amplitude of approximately 0mA, and the current consumed during fault standby flows. Here, the fault standby current is, for example, the current value specified by the rated current of the AF-type insulated power supply 50b, etc. Figure 11 In (a), it is approximately 15.5 mA.

[0091] Similarly, in the event of a short-circuit fault on the positive voltage (Vp) side of the operational amplifier 13a constituting the amplification section 13, Figure 11 The primary-side current value (Ia), which changes from approximately 15mA as indicated by the dashed arrow in (b), increases to approximately 50mA as indicated by the solid arrow. Furthermore, in the event of a short-circuit fault in the transistors (TR1, TR2) constituting the amplification section 13, ... Figure 11 The primary side current value (Ia) that changes from mA level as indicated by the dashed arrow in (c) is as indicated by the solid arrow, increasing to approximately 17A.

[0092] Therefore, when using the AF isolated power supply 50b, by detecting the state change of the current value (Ia) supplied from the drive power supply 50a to the primary side of the AF isolated power supply 50b, the fault or normal state of the noise filter including the AF circuit 52 can be diagnosed based on the state change of the current value (Ia).

[0093] The microcomputer 51 of the power conversion device 100 can, for example, use the ground potential as its own reference potential and perform fault diagnosis of the AF circuit 52 based on the current value Ia supplied from the drive power supply 50a to the AF isolated power supply 50b. The control microcomputer 51 can stop the operation of the power conversion circuit 3b if the AF circuit 52 is diagnosed as faulty. It should be noted that... Figure 10 The power source 3a shown is equivalent to the power source 2a in Embodiment 2, and the power conversion circuit 3b is equivalent to the power conversion circuit 2b. The power converted by the power conversion circuit 3b is input to the load 3c connected to the power conversion device.

[0094] In this embodiment, there is an advantage that the fault condition of the AF circuit 52 of the noise filter 3 can be diagnosed based solely on the measured value of the current Ia supplied from the drive power supply 50a to the AF insulating power supply 50b. In the control microcomputer 51 of the power conversion device 100, which includes the noise filter 3, the number of input values ​​for the diagnostic measurements can be relatively reduced compared to Embodiment 2; therefore, the freed-up input values ​​can be allocated to other control inputs.

[0095] It should be noted that the above-described embodiments and modifications can be combined as much as possible without departing from the technical problem and concept of the present invention. For example, in the above embodiments, solar power generation modules and battery modules are shown as examples of DC power sources. The present invention can also be applied to power systems that replace these modules and use energy sources such as fuel cell modules, internal combustion engine modules, wind power generation modules, tidal power generation modules, hydropower generation modules, geothermal power generation modules, or combinations thereof.

[0096] It should be noted that, in order to compare the constituent elements of the present invention with the configuration of the embodiments, the constituent elements of the present invention are described below with reference to the numerals in the accompanying drawings.

[0097] <Invention 1>

[0098] A noise filter (1) is characterized by comprising: an active filter circuit (10) connected to a power receiving end (20c, 20d) of a power line supplying AC power from an AC power system (103) or a DC power supply (101) interconnected with the AC power system (103) to a power conversion device (102) or DC power from the DC power supply, for reducing harmonic components of conducted noise propagating to the power line and outputting them to the power line; and

[0099] The control unit (30) monitors the state changes of the input power input to the power supply module that generates drive power for the active elements constituting the active filter circuit (10), or the state changes of the drive power supplied from the power supply module, and diagnoses abnormalities in the circuit operation of the circuit including the active elements of the active filter circuit (10) based on the state changes of the input power or the state changes of the drive power.

[0100] Explanation of reference numerals in the attached figures

[0101] 1, 2, 3: Noise filters

[0102] 10: Active Filter

[0103] 11: Power supply for the filter

[0104] 12: Testing Department

[0105] 13: Enlarged section

[0106] 14: Injection Section

[0107] 20: Passive Filter

[0108] 20a, 20b, 20c, 20d: terminals

[0109] 30: Anomaly Detection Department

[0110] 31: Current measurement function

[0111] 32: Abnormal diagnosis function

[0112] 100: Power System

[0113] 101: DC Power Supply

[0114] 102: Power conversion device

[0115] 102a: DCF

[0116] 102b: DC-DC converter

[0117] 102c: Inverter

[0118] 102d: ACF

[0119] 103: System.

Claims

1. A noise filter, characterized in that, have: An active filter circuit is connected to the power receiving end of the power line supplying AC power or DC power from an AC power system or a DC power source interconnected with the AC power system to the power conversion device, reducing the harmonic components of conducted noise propagating to the power line and outputting them to the power line. as well as The control unit monitors changes in the state of the input power supplied to the power supply module that generates drive power for the active elements constituting the active filter circuit, or changes in the state of the drive power supplied from the power supply module, and diagnoses abnormalities in the circuit operation of the active filter circuit, including the active elements, based on the changes in the state of the input power or the drive power. The power module has a positive power source that generates a positive side voltage and a negative power source that generates a negative side voltage. The control unit monitors the state changes of the drive power supplied from the power module based on at least one of the following current values: a first current value flowing from the positive power supply of the power module into the reference potential side, a second current value flowing from the negative power supply of the power module into the reference potential side, and a third current value flowing from the connection point connecting the negative electrode of the positive power supply and the positive electrode of the negative power supply into the reference potential side.

2. The noise filter according to claim 1, characterized in that, When the control unit diagnoses an abnormality in the operation of the active filter circuit, which includes the active element, based on the state change of the drive power, it stops the operation of the power conversion device.

3. The noise filter according to claim 1 or 2, characterized in that, When the control unit diagnoses the circuit operation of the active filter circuit including the active element as normal based on the state change of the driving power, it causes the power conversion device to continue operating.

4. The noise filter according to claim 1, characterized in that, The control unit diagnoses abnormalities in the operation of the circuit including the active element of the active filter circuit based on the first current value, the second current value, and the third current value.

5. The noise filter according to claim 1 or 4, wherein, When the control unit determines that the circuit including the active element of the active filter circuit is operating normally, either the first current value or the second current value is above a first threshold and below a second threshold greater than the first threshold.

6. The noise filter according to claim 4, wherein, When the third current value is above the third threshold and below the fourth threshold which is greater than the third threshold, the control unit determines that the circuit of the active filter circuit, including the active element, is operating normally.

7. The noise filter according to claim 1, characterized in that, The noise filter further includes a passive filter on the side of the power conversion device that reduces common-mode noise propagating in the power line, provided that the AC power is supplied to the power conversion device from an AC power system or a DC power source interconnected with the AC power system, or from a power line supplied by the DC power source.

Images