• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
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    • 专利摘要:
    energy converter resonance detection apparatus and method. Energy conversion systems and methods are presented for detecting filter capacitor resonance conditions in an energy conversion system in which filter currents are measured and filtered using a bandpass filter, and one or more average values, rms, and /or Fourier transform are computed based on the filtered value(s). the computed measurement value or values are compared to a predetermined threshold and a suspected filter capacitor resonance condition is selectively identified based on the comparison result.
    公开号:BR102013010702B1
    申请号:R102013010702-6
    申请日:2013-04-30
    公开日:2021-06-22
    发明作者:Kevin L. Baumann；Martin D. Ball；Yogesh Popatlal Patel；Russel J. Kerkman；Brian J. Seibel；Lixiang Wei
    申请人:Rockwell Automation Technologies, Inc.；
    IPC主号:
    专利说明:

    REFERENCE TO RELATED REQUEST
    This application claims priority and the benefit of provisional patent application US 61/640,456, filed April 30, 2012, entitled DRIVE RESONANCE CONDITION REDUCTION TECHNIQUES, the entirety of which is incorporated herein by reference. BACKGROUND
    Motor drives and other power conversion systems operate using power from AC power sources, and may include an input filter to reduce switching noise associated with power converter operation, particularly to control total harmonic distortion (THD). ) generated by high frequency operation of active front end rectifiers (AFE). The input filter employed in these converters often includes an inductor-capacitor (LC) circuit or an LCL (inductance-capacitance-inductance) associated with each AC input phase to control the harmonic content of an electrical power network. LCL and LC filter circuits can interact with power conversion circuitry under circumstances resulting in resonant conditions that can damage or degrade filter circuit components and other elements of the power converter. Such degradation can be costly in terms of replacement component costs, labor for inspection and replacement, as well as downtime for the energy conversion system and any associated machinery. Furthermore, continuous drive operation with internal resonant conditions degrades system efficiency and can inhibit the ability to properly drive a load. So far, however, evaluating energy converter resonance has been difficult and these conditions are not easily identifiable by operators or service personnel. SUMMARY
    Various aspects of the present disclosure are now summarized to facilitate a basic understanding of the disclosure, in that this summary is not an extensive overview of the disclosure, and is not intended to identify certain elements of the disclosure, nor to delineate the scope of the disclosure. Rather, the primary purpose of this summary is to present various concepts of revelation in simplified form before the more detailed description that follows.
    Energy conversion systems and methods are presented to detect energy converter resonance conditions according to measured filter currents. A power conversion system is provided which includes a filter circuit with filter capacitors coupled between an AC input and a rectifier. A controller identifies suspicious resonance conditions in the filter circuit at least partially in accordance with components of one or more filter currents in a predetermined frequency band. In certain embodiments, filter current is current flowing in one or more capacitors in the filter circuit. In other embodiments, the filter circuit is an LCL or LC circuit and the controller evaluates one or more line or phase currents flowing in the filter circuit. The controller in certain embodiments includes a bandpass filter with an upper cutoff frequency below a rectifier switching frequency, and a lower cutoff frequency above a fundamental frequency of the signal or filter current value. In certain embodiments, furthermore, the controller identifies a suspected resonance condition if an average or RMS value of the filter current components in the predetermined frequency band exceeds a predetermined threshold. In other embodiments, the controller identifies suspected resonance based on Fourier analysis of the filter current components in the predetermined frequency band.
    Non-transient computer readable methods and media are provided with computer executable instructions for detecting resonance in an energy conversion system, including receiving or analyzing at least one signal or filter current value representing a current flowing in a filter circuit of the energy conversion system, and selectively identify a suspected resonance condition at least partially according to components in a predetermined frequency band. Certain modalities include filtering the filter current using a bandpass filter, computing at least an average value or RMS, and selectively identifying a suspected resonance condition in the energy conversion system if the average value or RMS exceeds a threshold. BRIEF DESCRIPTION OF THE DRAWINGS
    The following description and drawings set out in detail certain illustrative implementations of the disclosure which are indicative of various exemplary ways in which the various principles of the disclosure may be carried out. The illustrated examples, however, are not exhaustive of the many possible modalities of revelation. Other goals, advantages and unprecedented features of the disclosure will be exposed in the detailed description below when considered in combination with the drawings, in which:
    Figure 1 is a schematic diagram illustrating an energy conversion system with a controller configured to identify suspicious input filter resonance conditions according to current measurements;
    Figure IA is a schematic diagram illustrating an alternative mode power converter with a main circuit breaker between the AC input and the input filter circuit, as well as a pre-charge circuit connected between the filter output and the rectifier input. ;
    Figure 2 is a schematic diagram illustrating a pre-charge circuit in the energy converter of Figure 1;
    Figure 3 is a schematic diagram illustrating an LC filter circuit connected in delta with a controller performing a threshold comparison of average filter capacitor current values or bandpass filtered RMSs to detect converter resonance;
    Figure 3A is a schematic diagram illustrating an LC filter circuit arrangement for a current source converter embodiment including delta connected filter capacitors;
    Figure 4 is a schematic diagram illustrating another LC filter circuit having Y-connected filter capacitors connected between individual converter phases and a common node;
    Fig. 4A is a schematic diagram illustrating an LC filter circuit arrangement for a current source converter mode including Y-connected filter capacitors;
    Figure 5 is a schematic diagram illustrating another LC filter circuit connected in delta to the controller performing a bandpass filtered RMS or average line current threshold comparison for converter resonance detection;
    Figure 6 is a schematic diagram illustrating another Y-connected LCL filter with a controller measuring line currents to detect converter resonance conditions;
    Figure 7 is a schematic diagram illustrating an active front end rectifier (AFE) and a DC link in the power conversion system of Figure 1;
    Figure 8 is a schematic diagram illustrating a three-phase inverter in the energy conversion system of Figure 1;
    Figure 9 is a flowchart illustrating a method of identifying a suspected resonance condition in an energy conversion system using measured current values and averaging or RMS computations;
    Figure 10 is a graph showing three-phase AC voltages, line currents, filter currents and average computed values with corresponding threshold comparisons for conditions with and without converter resonance;
    Figure 11 is a flowchart illustrating another method of identifying suspected energy conversion system resonance using Fourier transform techniques and measured filter currents; and
    Figures 12-14 are graphs illustrating Fourier transforms of filter capacitor currents with and without bandpass filtering for conditions with and without power converter resonance. DETAILED DESCRIPTION
    Referring now to the figures, various embodiments or implementations are described below in combination with the drawings, in which like reference numerals are used to refer to like elements throughout the drawings, and in which the various features are not necessarily drawn in scale.
    Figure 1 illustrates a power conversion system 2 including a precharge circuit 10, an LCL or LC input filter circuit 20, an active front end rectifier (AFE) 30, a DC link circuit 40, a inverter 50 and a controller 60 that detects resonance conditions at least partially in accordance with harmonic content of one or more converter currents in a predetermined frequency band. The power conversion system 2 has a pluggable AC input 3 for receiving polyphase AC input power from a power source 4 and a single-phase or polyphase AC inverter output 52 providing AC output power to a single-phase or polyphase 6 load, such as like an engine.
    In certain embodiments, the power conversion system is a current source converter (CSC) system having an LC filter circuit 20 and a DC link 40 with one or more inductances (e.g., such as a DC link inductor) to accommodate DC link current supplied by rectifier 30 and used as input power by inverter 50. In other embodiments described herein, converter 2 is a voltage source converter (VSC) with an LC filter circuit 20, wherein the DC link circuit 40 includes one or more DC link capacitances (for example, Cl and C2 as seen in Figure 7 below).
    Power source 4 provides polyphase AC input power, where the illustrated examples show a three-phase implementation, although other polyphase implementations are possible having three or more input phases. Inverter 50 may provide a single-phase or polyphase output 52, with examples illustrated showing a three-phase inverter 50 driving a three-phase load 6 (e.g., a motor). The converter 2, furthermore, can be a motor drive although any form of energy conversion system 2 can be implemented in accordance with the present disclosure, whether driving a motor or a different form of AC 6 single-phase or polyphase load or a DC load (not shown) in which case the inverter 50 can be omitted.
    Controller 60 may be implemented as any hardware, processor-executed software, processor-executed firmware, programmable logic, and/or combinations thereof to implement the resonance detection functionality set forth herein including other functions associated with operation of the conversion system. power 2. In certain embodiments, controller 60 may be implemented as a circuit based on a single processor and/or may be implemented using multiple processor elements. For example, certain resonance detection functions discussed in this document can be implemented in a local controller 60, such as a field programmable gate array (FPGA) implemented in the LCL or LC 20 input filter circuit, and/or such features can be implemented using a centralized controller 60 in certain embodiments or in multiple controller elements 60. For example, a localized controller 60 can be implemented in the LCL or LC filter circuit 20 or in association with it, which receives one or more threshold values of a central controller board 60. Also in other possible implementations, hardware circuitry can be used to implement one or more of the resonance detection features, alone or in combination with one or more processor components.
    As seen in Figure 2, the pre-charge circuit 10 includes a main circuit breaker 12, a bonded disconnect device 14, a pre-charge contactor 16 and pre-charge resistors 18, and is operable in one of three modes. The precharge circuit 10 may be omitted in certain embodiments. As seen in Figure 1A, alternative power converter arrangements can provide the main circuit breaker 12 between the AC input 3 and the input filter circuit 20, with a pre-charge circuit 10 having a pre-charge contactor 16 and the pre-charge resistors 18 connected between the filter output 22 and the rectifier input 30. The pre-charge circuitry 10 in Figure 2 is operated by the controller 60, which typically holds the disconnect device contacts together. 14 in a closed condition and opens these contacts only when an overcurrent condition occurs. In a normal operating mode, controller 60 (eg, a central controller or a local precharge I/O board or precharge controller) holds the main circuit breaker 12 in the closed position to allow input power to flow. from the power source 4 to the precharge output terminals 13, but maintains the precharge contactor 16 in an "open" (eg non-conductive) condition, whereby current does not flow through the precharge resistors. load 18. In a "pre-charge" mode (eg on controlled start or reset of the power conversion system 2), the controller 60 switches the main circuit breaker 12 to the "open" condition and closes the pre contactor. -charge 16, to allow current to flow from AC source 4 through precharge resistors 18 to precharge output terminals 13. This effectively inserts precharge resistors 18 into the polyphase power circuitry during the "pre-charge" mode to control overcurrent increases. those for charging the capacitance of a DC bus in the DC link circuit 40 at the output of the rectifier 30 and/or at the input of the inverter 50 (for example, capacitors Cl and C2 in the example in figure 7 below). Controller 60 can be provided with one or more feedback signals by which a DC link voltage can be monitored, and once the DC voltage exceeds a predetermined value, controller 60 closes the main circuit breaker 12 and opens the contactor. precharge 16 to enter normal operating mode. The pre-charge circuitry 10 may also be operated in a "standby" mode, in which the controller 60 maintains both the main circuit breaker 12 and the pre-charge contactor 16 in the "open" condition, with auxiliary power being supplied to several control circuits by a power supply 19 (figure 2). In certain embodiments, furthermore, pre-charge circuit 10 is operable by controller 60 to selectively open both main circuit breaker 12 and pre-charge contactor 16 in response to indication of suspicious converter resonance conditions as described further. Next.
    As seen in Figure 1A, in other possible embodiments, the pre-charge circuit 10 can be placed between the filter circuit 20 and the rectifier 30. In certain implementations, a main circuit breaker 12 can be connected between the AC input 3 and the filter circuit 20 to facilitate power off, and the precharge circuit 10 will include a precharge contactor 16 and precharge resistors 18 connected in a bypass circuit around a precharge circuit breaker , such as circuit breaker 12 shown in figure 2.
    Referring also to Figures 3-6, the precharge circuit outputs 13 are connected to an LCL input filter circuit 20 for VSC modes or to an LC filter circuit 20 for CSC modes. In certain embodiments, the pre-charge circuitry 10 may be omitted, and the LCL or LC filter circuit 20 is directly or indirectly coupled to the AC input terminals of power converter 3. The filter circuit 20 includes an LCL or LC circuit for each input phase including a first inductor LI (eg LIA, LIB and L1C) and the LCL filter modalities 20 include a second inductor L2 (L2A, L2B and L2C) with LI and L2 being coupled in series with each other between the corresponding precharge circuit output 13 (or the corresponding AC input terminal 3) and a corresponding phase output 22 of the filter circuit 20. A plurality of CF filter capacitors are provided , with at least one of the CF filter capacitors being connected to each of the phase lines at a central node between the corresponding first and second LI and L2 inductors (or following the LI inductor for LC filter modes).
    In the examples in Figures 3 and 5, the CF filter capacitors are connected in a delta configuration with a first CF capacitor connected between phases A and B, a second CF capacitor connected between phases B and C, and a third CF filter capacitor connected between phases C and A. Discharge resistors can be provided in certain embodiments as shown in Figures 3 and 5, with each discharge resistor being connected between a corresponding phase of the power phases and an internal node. Figures 4 and 6 illustrate other modalities in which CF filter capacitors and corresponding parallel connected discharge resistors are connected in a "Y" configuration, with each CF filter capacitor being connected between a corresponding phase of the power phases and a common node, which in turn can be connected to a system ground, a neutral of input power source 4, or which can be connected only to CF filter capacitors in various modes.
    Controller 60 in certain embodiments is operatively coupled to connected current sensors in order to measure one or more filter capacitor currents (Ica, Icb and/or Icc) flowing through the CF filter capacitors for selective determination of suspicious resonance conditions in the energy conversion system 2 in general and/or resonance conditions in the filter circuit 20. Alternatively or in combination, the controller 60 can be coupled to sensors as shown in Figures 5 and 6 for measuring or detecting currents. of line or phase iA, iB and/or ic flowing through filter 20 to detect such resonance conditions.
    As seen in Figures 3A and 4A, current source converter arrangements may include an LC filter with a plurality of CF filter capacitors connected downstream of the corresponding LIA, LIB and L1C inductors in the corresponding power phases between the connection points of filter capacitor and AC input 3. In these modes, in addition, discharge resistors can be connected in parallel with each of the CF filter capacitors as shown, or such discharge resistors can be omitted in other modes. Figure 3A illustrates a current source converter embodiment of the filter circuit 20 in which the CF filter capacitors are connected in a delta configuration with discharge resistors connected between the corresponding filter capacitor connections and a central node. Figure 4A illustrates another embodiment of an LC filter circuit 20 for a current source converter system 2 in which the CF filter capacitors are connected in a Y configuration along with discharge resistors connected in parallel.
    Figure 7 illustrates an active front-end rectifier (AFE) circuit 30 in the power conversion system of Figure 1, as well as a DC link circuit 40. In the illustrated example, the rectifier 30 includes switching devices Q1-Q6, such as insulated gate bipolar transistors (IGBTs) or other electrical switching devices. The Q1-Q6 devices are individually operable in accordance with a corresponding rectifier switching control signal from controller 60 to selectively couple a corresponding phase line of phase lines A, B and C to one of the two DC circuit nodes 32 or 34 to rectify input AC power to supply DC power to the DC link 40, where controller 60 can supply the switching control signals in accordance with any suitable switching scheme such as pulse width modulation (PWM). Rectifier 30 alternatively or in combination can provide passive rectifier diodes D1-D6 individually coupled between one of AC nodes 22 at the filter circuit output and a corresponding DC node of DC nodes 32, 34 for passive rectification of AC input power to establish DC link 40. Certain modalities of rectifier 30 can provide regenerative operation (with or without passive rectifier diodes D1-D6 rectifying input power to charge capacitors Cl, C2 of DC link circuit 40) where controller 60 drives selectively rectifier switches Q1-Q6 by means of pulse width modulation or other suitable switching technique for selective connection of DC nodes 32, 34 with input nodes 22 to allow regenerative current conduction from DC link 40 back in direction of the power source 4 .
    The DC link circuit 40 includes one or more capacitances coupled between the DC circuit nodes 32 and 34 for voltage source converter implementations, where Figure 7 illustrates an embodiment in which two capacitances C1 and C2 are connected in series with one another. another between nodes 32 and 34. The DC link capacitance can be constructed using any suitable number of capacitor devices connected in any suitable series, parallel or series/parallel configurations to provide a connected capacitance between the DC nodes 32 and 34. Current source converter modes are possible in which the DC link circuit 40 includes one or more inductances (not shown) and the filter 20 for such CSC implementations may be an LC circuit as shown in the indicated figures 3A and 4A above.
    Figure 8 illustrates an inverter circuit 50 including inverter switching devices Q7-Q12 and corresponding parallel connected rectifier diodes D7-D12, where controller 60 provides inverter switching control signals to devices Q7-Q12 in order of selectively coupling a corresponding DC terminal 32, 34 with a corresponding output of the AC outputs 52 in order to convert DC link power to supply AC output power to drive the load 6 in a controlled mode. Controller 60 can provide the inverter switching control signals in accordance with any suitable pulse width modulation or other switching technique in order to provide AC output power to drive load 6, which can be performed in accordance with any suitable control technique, eg to regulate output frequency, output power, motor speed control, motor torque control, etc. or combinations thereof.
    Certain embodiments of controller 60 include at least one processor (e.g., a microprocessor, microcontroller, field-programmable gate array, programmable logic, etc.) programmed or otherwise configured to identify one or more suspicious resonance conditions based on the less partly in the filter capacitor currents Ic flowing in the CF filter capacitors (Ica, Icb and Icc in the three-phase examples of figures 3 and 4) and/or in the line currents iA, iB, ic (figures 5 and 6). In certain embodiments, controller 60 implements resonance detection functionality using one or more processors of a general energy conversion system controller. In other embodiments, one or more of these functions are performed by an FPGA or other local processor to the LC filter circuit 20, which can, but need not, receive one or more TH threshold values from a central control board or main controller of power conversion system 2. In other embodiments, hardware circuitry can be used alone or in combination with one or more processor components to implement the resonance detection functions.
    As noted earlier, CF filter capacitors can be connected in a delta configuration (eg figures 3 and 5, alone or with optional discharge resistors as shown) or they can be connected in a Y configuration (eg figures 4 and 6). The controller 60 in figures 3 and 4 is provided with signals or values indicating the levels of the filter capacitor currents Ica, Icb and Icc by any suitable means, such as by current sensors in the lines connecting the CF filter capacitors to the phase lines A, B, and C. In this aspect, capacitor currents Ica, Icb, and Icc in the delta-connected filter capacitors configuration of figure 3 can be detected or measured using sensors configured in the lines connecting the delta configuration to the lines of phase A, B and C as shown, or sensors can be connected in series with each of the individual CF capacitors delta connected in other modes. It is noted that these filter capacitor currents Ica, Icb and Icc will typically be less than the phase currents iA, iB and ic flowing between the filter circuit inputs and outputs 22 which can be used alternatively or in combination for the concepts of described residence detection. In the example in Figure 4, current sensors are provided in series with each of the CF filter capacitors in order to measure the corresponding filter capacitor current because of the Y connection.
    In the embodiments of figures 5 and 6, the controller 60 is provided with signals or values indicating the levels of line currents iA, iB, ic for situations where the CF filter capacitors are connected in a delta configuration (figure 5) or in a Y configuration (figure 6). In addition, in certain embodiments, controller 60 may also be provided with signals or values indicating AC voltages in the filter circuit, such as line-to-line voltages (eg, VAB, VBC and VCA) and/or line voltages to neutral (VA, VB and Vc) via sensors or other suitable devices (not shown).
    As best seen in Figure 3, certain embodiments of controller 60 include a bandpass filter 61 that receives one or more signals or current values representing filter capacitor currents and/or line (phase) currents in the filter circuit. 20 (for example Ica, Icb, Icc, iA, iB and/or ic). The current signal(s) or value(s) can be received directly from sensors as shown in figures 3-6 and/or can be received from other components of the energy conversion system 2. Based at least partially on one or more signals or current values, the controller 60 identifies suspicious resonance conditions in the filter circuit 20 and/or in the energy conversion system 2 generally. . In particular, the controller evaluates components of at least one current (eg Ica, Icb, Icc, iA, iB and/or ic) in a predetermined frequency band, such as about 500 Hz to about 2200 Hz in a possible implementation. In the embodiment of Figure 3, the controller 60 employs a second order bandpass filter or FIR (Finite Impulse Response) 61 to provide filtered output signals or values representing the predetermined frequency band components of the current(s). ) detected. The bandpass filter 61 in certain embodiments determines components of at least one signal or filter current value (e.g. Ica, Icb, Icc, iA, iB, and/or ic) in a predetermined frequency band (e.g. , 500-2200 Hz in one mode, 600-2200 Hz in another possible mode). Filter 61 may be any suitable form of analogue and/or digital bandpass filter having high and low cut-off frequencies. In certain embodiments, the low cut-off frequency is about 500 Hz or more and the high cut-off frequency is about 2200 Hz or less. In additional embodiments, the lower cut-off frequency can be about 600 Hz or more. In certain embodiments, furthermore, the lower cut-off frequency is above a fundamental frequency of the signals or filter current values (for example, the fundamental frequency of the currents Ica, Icb, Icc, iA, iB and/or ic flowing in the filter circuit 20) . In some embodiments, furthermore, the upper cut-off frequency of filter 61 is below a switching frequency of active front-end rectifier 30. For example, certain embodiments of rectifier 30 can perform active rectification and/or regenerative switching of devices Q1. -Q6 at a switching frequency of about 4 kHz, where the exemplar filter 61 provides an upper cut-off frequency of about 2200 Hz or less. Furthermore, certain modalities of the controller 60 allow to sample the one or more signals or filter current values at a FAMOSTRA sampling rate or sampling frequency of about 22 kHz or more.
    Controller 60 in Fig. 3 further includes a scaling component 62 (e.g. analog and/or digital implementations are possible) for scaling the signals filtered by bandpass filter 61 in accordance with any suitable scaling coefficients or values. As mentioned, controller 60 can be implemented using analog hardware circuitry, digital hardware circuitry, one or more programmable processing elements such as microprocessors, microcontrollers, programmable logic, etc. and/or combinations thereof. In certain embodiments, one, some, or all of the controller components illustrated 61-65, 67, and 68a-68c in Figure 3 may be implemented in hardware and/or as processor-executed components. In the illustrated implementation, one or more of the detected filter current values Ica, Icb, Icc, iA, iB and/or ic are filtered using a bandpass filtering component 61 of controller 60. The filtered signal or signals in certain embodiments are provided to the scaling component 62 with which the filtered signals or values are scaled according to any necessary scaling based on the calibration of the current sensor(s), on the gain of the bandpass filter circuit 61, on the scaling associated with threshold value 65, etc. In other embodiments, the scaling component 62 may be omitted. The controller 60 in certain embodiments uses the filtered signals or values (with or without subsequent scaling) to compute one or more average values or RMSs by means of a computing component 63 (which may be implemented per processor or which may be circuitry analog and/or digital hardware in certain modes). A comparison component 64 selectively provides an alarm and/or initiates one or more corrective actions 66 if the RMS or average value(s) exceed(s) a threshold 65. In this way, the controller 60 identifies a or more suspicious resonance conditions in converter 2 and/or filter circuit 20 thereof if at least one average value or RMS value of components of at least one signal or filter current value in the predetermined frequency band exceeds the predetermined threshold 65. This resonance detection concept, furthermore, can be used with one or more of the filter capacitor current signals or values Ica, Icb, Icc representing current flowing in one or more of the CF filter capacitors and/or these concepts can be employed using one or more of the line or phase current signals or values iA, iB and/or ic.
    Any suitable threshold value or values can be employed by which residents of a certain magnitude of interest can be detected. In certain embodiments, furthermore, threshold 65 is determined at least in part in accordance with a power conversion system frame size 68a, a power converter voltage class 68b, and/or one or more tolerance values 68c associated with CF filter capacitors. In hardware implementations, threshold 65 may be provided as one or more signals, and/or threshold 65 may be one or more values in programmable processor implementations. In certain embodiments, threshold 65 may be a predetermined value, and controller 60 in certain embodiments selectively adjusts threshold 65 based on one or more conditions measured in the energy conversion system 2. In certain embodiments, in addition, the threshold 65 may be provided by a main control board of power conversion system 2 to a local controller 60 implementing the resonance detection functions described herein, such as a local controller 60 operatively associated with filter circuit 20. The controller 60 may also be provided with frame size information 68a, such as a rating associated with power conversion system 2, an indicator or voltage class value 68b associated with power converter 2, and/or tolerance data. of capacitor, the value(s) or 68c information indicating one or more tolerance values (eg maximum rated current values, etc.) associated with the CF filter capacitors.
    Referring now to Figures 3, 9 and 10, Figure 9 illustrates an exemplary process 100 for detecting resonance in energy conversion system 2 and Figure 10 illustrates a graph 70 showing various signals in energy converter 2 during non-resonance operation. (indicated at 72 in figure 10) as well as operation with internal resonant conditions (74 in figure 10). In this regard, a resonant condition of interest is resonance in filter circuit 20, although method 100 can be employed to detect resonance in energy conversion system 2 generally. Although exemplary method 100 of Figure 9 and method 200 of Figure 11 below are illustrated and described below in the form of a series of procedures or events, the various methods of the present disclosure are not limited by the illustrated ordering of such procedures or events. except as specifically stated in this document. In this regard, except as specifically provided in the claims, some procedures or events may occur in a different order and/or concurrently with other procedures or events alongside those procedures or events and ordering illustrated and described in this document, and not all procedures or events illustrated may be required to implement a process or method in accordance with the present disclosure. The disclosed methods, furthermore, can be implemented in hardware, processor-executed software, programmable logic, etc., or combinations thereof, in order to provide the described functionality, where these methods can be practiced in the energy conversion system 2 described above, as in controller 60, although the methods currently disclosed are not limited to the specific applications and implementations illustrated and described in this document. In addition, methods 100 and 200 may be incorporated as computer executable instructions stored on non-transient computer readable media, such as memory operatively associated with controller 60 and/or power conversion system 2. The method 100 of Figure 9 facilitates identification of suspected resonance in the converter 2 and/or the included filter circuit 20 by comparing average or RMS computation thresholds of harmonic components of one or more line or filter capacitor currents. At 102, one or more of these signals or values (for example, Ica, Icb, Icc, iA, iB and/or ic) are measured or received or otherwise obtained, and are analyzed to selectively identify a suspected resonance condition with based at least partially on components thereof that are in a predetermined frequency band (eg, 500-2200 Hz in one mode, 600-2200 Hz in another illustrative mode). The harmonic components of interest can be obtained by bandpass filtering the signal(s) or current value(s) filter at 104 using a bandpass filter (eg filtering component 61 in figure 3 indicated above) with lower and upper cutoff frequencies defining the predetermined frequency band. At 106, the filtered signal(s) or value(s) can be scaled in certain modalities, and one or more average and/or RMS values are computed at 108. The computation Averaging or RMS in 10 8 may be performed using any suitable numerical techniques as are known, and may be performed using any suitable analog circuitry, digital circuitry, processor-executed firmware or processor-executed software, etc.
    A determination is made at 110 in Fig. 9 such as to check whether the computed mean value(s) or RMS(s) exceeds a threshold TH (e.g., threshold 65 in figure 3) . If not (NOT at 110), process 100 repeats, returning to 102-108 as described above. If the threshold value is exceeded (YES at 110), controller 60 identifies or otherwise determines at 112 that there is suspicion of resonance in converter 2. In this mode, controller 60 can optionally report the suspected resonance condition and/or execute one or more corrective actions at 114. For example, the controller may open main breaker 12 and precharge contactor 16 in precharge circuitry 10 of figure 2 shown above and/or may initiate another controlled shutdown and reporting operations such as activating an alarm, indicating a suspected resonance condition on a user interface of power conversion system 2, sending an error message to a controlling supervisor associated with power converter 2, etc. In addition, or separately, controller 60 can record a fault and reset power converter 2, such as by storing a value in a fault register in a non-volatile memory of power converter 2 (not shown), or controller 60 may indicate an incapable of resetting fault for a person-machine interface (HMI, not shown) for different levels of suspected resonance (e.g., as indicated by relative comparison with threshold 65), and/or can only allow a fault to be reset upon password-protected entry by service personnel after system inspection.
    Figure 10 illustrates exemplary line voltages (phase voltages VΦ including VA, VB, and Vc in the illustrated three-phase mode), line currents iΦ (eg iA, ÍB/ic) iθ filter capacitor currents IcΦ (eg, Ica, Icb and/or Icc) together with bandpass filtered signals or mean values in energy conversion system 2 for normal conditions (eg no resonance) at 72 and during resonance at 74. The inventors realized that currents lines iA, iB and/or ic will have a detectable harmonic component within the predetermined frequency band (for example, above the fundamental frequency of the power source and below the rectifier switching frequency, such as between about 500 and 2200 Hz ) when the power converter 2 is in the resonant condition 74. Furthermore, the inventors have realized that the filter capacitor currents Ica, Icb and/or Icc (IcΦ) will have a comparatively larger harmonic component in this frequency band predetermined for system resonance 74 than for normal operation (no resonance) at 72, as seen in Figure 10. In this aspect, without system resonance, the line currents i' are of normally regular swells at the fundamental frequency of the source of power (eg, 50 or 60 Hz), and filter capacitor currents IcΦ typically include a small harmonic component.
    During resonance, however, harmonics in the predetermined frequency band appear at line currents iΦ and the amplitude of harmonics and filter currents IcΦ increase. In this way the average value(s) or RMS(s) 76 associated with the filter current in the predetermined frequency band or the average value(s) or RMS(s) s) 78 associated with the phase current components in the predetermined frequency band is(are) seen to increase during the resonant condition 74 in Figure 10. In this way, the controller 60 compares one or more of these values. 76, 78 with a corresponding threshold value TH (e.g. threshold 65 in Fig. 3) and selectively identifies a suspected resonance condition when the value 76, 78 exceeds threshold TH (e.g. YES at 110 in Fig. 9). As seen in Figure 10, controller 60 advantageously provides threshold 65 with a level TH slightly above the normal operating level of the average value or RMS 76, 78 of the detected filter current(s) for detect the onset of suspicious resonance conditions and in this way can initiate an alarm and/or other corrective action via component 66. In addition, threshold 65 can be adapted according to a specific frame size 68a, voltage class 68b and/ or one or more 68c filter capacitor specifications.
    Referring now to Figures 3 and 11-15, in other embodiments, controller 60 may include processor-executed circuitry and/or instructions to perform Fourier analysis, such as Fast Fourier Transform (FFT) components, to analyzing one or more signal component(s) and/or filter current value(s) for selective identification of suspicious resonance conditions in converter 2 and/or filter circuit 20 thereof. Figure 11 illustrates an exemplary resonance condition detection method 200 in which controller 60 measures or otherwise receives and analyzes one or more filter capacitor currents (e.g., Ica, Icb and/or Icc) and/or line currents (eg iA, 1B, ic) at 202 and optionally can apply bandpass filter to the current value(s) and scaling can be performed at 204 according to any suitable scaling technique. Fourier analysis is performed at 206 and a total harmonic distortion (THD) value in a predefined frequency band is determined at 208. This THD value is compared with a TH threshold at 210. If the THD value exceeds the threshold (YES at 210). 210), converter resonance is identified at 212 and controller 60 can report the resonant condition and/or take corrective action at 214. Otherwise (NOT at 210), the process is repeated at 202-208 as described above.
    Figures 12-15 provide graphs 80, 86, 90, and 92, respectively, illustrating frequency spectra based on Fourier transforms of filter capacitor currents. Figures 12 and 13 illustrate graphs 80 and 86 showing frequency components before and after bandpass filtering, respectively, for non-resonant system, while figures 14 and 15 illustrate graphs 90 and 92 showing frequency components before and after bandpass filtering, respectively, for resonant conditions in power converter 2. As shown in figures 12-15, the power supply fundamental frequency component 81 (eg, 50 or 60 Hz) is well below the rectifier switching frequency components 83 (e.g., about 4 kHz in one mode), and resonant frequencies 82 in the illustrated system 2 are found primarily in a predetermined frequency band between about 500 Hz and about 2200 Hz in certain modalities. Furthermore, the switching operation of the active front-end rectifier 30 (figure 7 above) can generate the harmonics 84 far above the resonant frequency band of interest.
    As seen in graphs 80 and 90 of figures 12 and 14, the frequency components in the predetermined frequency band (e.g., 500-2200 Hz) are significantly greater during system resonance (figure 14) than otherwise (figure 12), and the FFT implementation of Fig. 11 can perform threshold comparison of component amplitudes in this predetermined frequency band to selectively identify suspicious resonance conditions. With bandpass filtering (eg using bandpass filter 61 in controller 60) the spectrum of signals (figures 13 and 15) following the bandpass filter can also be used to selectively identify suspected resonance in converter 2, wherein the frequency components within the predetermined frequency band 85 are significantly greater during resonance (Figure 15) than otherwise (Figure 13). The inventors thus realized that the bandpass filtering described above in combination with averaging or RMS computations can be used with the appropriate threshold values 65 to selectively identify suspicious conditions residing in an energy conversion system 2. Furthermore, such as seen in figures 13 and 15, Fourier analysis can also be used to detect the differences between THD amplitudes in the 85 frequency band for resonant conditions and for normal (non-resonant) conditions.
    The foregoing examples are only illustrative of several possible embodiments of various aspects of the present disclosure, where equivalent changes and/or modifications will occur to those skilled in the art upon reading and understanding this descriptive report and the accompanying drawings. With particular reference to the various functions performed by the components (assemblies, devices, systems, circuits and the like) described above, the terms (including a reference to a "feature") used to describe such components are intended to correspond, unless which is otherwise indicated, to any component, such as hardware, software executed by the processor, or combinations thereof, that performs the specified function of the described component (that is, which is functionally equivalent), even if not structurally equivalent to the disclosed structure which performs the function in the illustrated implementations of the disclosure. Furthermore, although a particular feature of the disclosure may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application. . Also, to the extent that the terms "including", "includes", "having", "has", "with", or variants thereof are used in the detailed description and/or in the claims, such terms are intended to be inclusive in a way similar to the term "comprising". COMPONENT LIST 10 precharge circuit 12 main circuit breaker 14 disconnect device bonded 16 precharge contactor 18 precharge resistors 19 power supply 2 power conversion system 20 input filter circuit 22 filter output 3 AC input 30 rectifier 32 nodes DC 32 terminal DC 34 terminal DC 4 power supply 40 link circuit DC 50 inverter 52 outputs AC 6 load AC 60 controller 61 bandpass filter 63 computing component 64 comparison component 65 threshold 66 corrective actions LI first inductor
    权利要求:
    Claims (9)
    [0001]
    1. A power conversion system (2), comprising: an AC input (3) attachable for receiving AC input power from a power source (4); a rectifier (30) operative to convert AC input power to provide a DC output; an inverter (50) operatively coupled with the DC output of the rectifier (30) to provide an AC output (52); a filter circuit (20) coupled between the AC input (3) and the rectifier (30), the filter circuit (20) comprising a plurality of filter capacitors (CF); and a controller (60) operative to identify a suspected resonance condition in the filter circuit (20) based partially on components of a signal or current value representing a filter capacitor current (Ica, Icb, Icc) flowing in the circuit. of filter (20) in a predetermined frequency band (85), characterized in that the controller (60) comprises a bandpass filter (61) operative to receive one or more signals or current values representing filter in the filter circuit, the bandpass filter still being operative to determine the signal components or current value (Ica, Icb, Icc) in the predetermined frequency band (85), the bandpass filter (61) having a upper cut-off frequency below a switching frequency of the rectifier (30), and a lower cut-off frequency above a fundamental frequency of the signal or current value (Ica, Icb, Icc; iA, iB, iC).
    [0002]
    2. Power conversion system (2), according to claim 1, characterized in that the controller (60) is operative to identify a suspected condition of resonance in the filter circuit (20) if an average value of the components the signal or current value (Ica, Icb, Icc) in the predetermined frequency band (85) exceeds a predetermined threshold (65).
    [0003]
    3. Power conversion system (2) according to claim 1, characterized in that the controller (60) is operative to identify a suspected condition of resonance in the filter circuit (20) if an RMS value of the components the signal or current value (Ica, Icb, Icc) in the predetermined frequency band (85) exceeds a predetermined threshold (65).
    [0004]
    4. Power conversion system (2) according to claim 1, characterized in that the controller (60) is operative to identify a suspected condition of resonance in the filter circuit (20) if a harmonic distortion value total in the predetermined frequency band (85) of a Fourier transform of the signal or current value (Ica, Icb, Icc) exceeds a predetermined threshold (65).
    [0005]
    5. Power conversion system according to claim 1, characterized in that the controller (60) is operative to identify a suspected condition of resonance in the filter circuit (20) based partially on an average value of the components of current (Ica, Icb, Icc) flowing in the filter circuit (20) in the predetermined frequency band (85).
    [0006]
    6. Power conversion system according to claim 1, characterized by the fact that the controller (60) is operative to identify a suspected condition of resonance in the filter circuit (20) based partially on an RMS value of the components of the current (Ica, Icb, Icc) flowing in the filter circuit (20) in the predetermined frequency band (85).
    [0007]
    7. Method for detecting resonance in a polyphase energy conversion system (2), the method characterized by the fact that it comprises: receiving or analyzing a signal or current value representing a filter capacitor current (Ica, Icb, Icc) flowing in a filter circuit (20) of the energy conversion system (2); and selectively identifying a suspected resonance condition in the energy conversion system (2) based partially on signal components or current value in a predetermined frequency band (85), wherein the signal components or filter current value in the predetermined frequency band are determined by filtering the signal or current value (Ica, Icb, Icc) using a bandpass filter (61), the bandpass filter (61) having an upper cut-off frequency below a frequency switching of a rectifier (30) of the power conversion system, and a lower cut-off frequency above a fundamental frequency of the signal or current value (Ica, Icb, Icc).
    [0008]
    8. Method according to claim 7, characterized in that it comprises: computing average value based on the measured filtered signal or current value; comparing the mean value to a predetermined threshold (65); and selectively identifying a suspected resonance condition in the energy conversion system (2) if the average value exceeds the predetermined threshold (65).
    [0009]
    9. Method according to claim 7, characterized in that it comprises: computing the RMS value based on the measured filtered signal or current value; comparing the RMS value to a predetermined threshold (65); and selectively identifying a suspected resonance condition in the energy conversion system (2) if the RMS value exceeds the predetermined threshold (65).
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    法律状态:
    2015-11-17| B03A| Publication of a patent application or of a certificate of addition of invention [chapter 3.1 patent gazette]|
    2018-05-22| B03H| Publication of an application: rectification [chapter 3.8 patent gazette]|
    2018-12-04| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|
    2020-09-08| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|
    2021-02-02| B06A| Notification to applicant to reply to the report for non-patentability or inadequacy of the application [chapter 6.1 patent gazette]|
    2021-05-11| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    2021-05-25| B03H| Publication of an application: rectification [chapter 3.8 patent gazette]|Free format text: REFERENTE A RPI 2341 DE 17/11/2015, QUANTO AO ITEM 32, 54, 71 E 72. |
    2021-06-22| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 30/04/2013, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
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    US201261640456P| true| 2012-04-30|2012-04-30|
    US61/640,456|2012-04-30|
    US13/570,919|US9667128B2|2012-04-30|2012-08-09|Power converter resonance detection apparatus and method|
    US13/570,919|2012-08-09|
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