Airflow health prognostic maintenance for motor drive

Abstract

An airflow health prognostic maintenance system and method for motor drive apparatuses includes a differential pressure sensor that senses a differential pressure between a sensing location and a reference location within an enclosed cabinet space of a motor drive apparatus. The system includes an electronic control system configured to select a setpoint that indicates that airflow through the cabinet space has reached a value associated with an air filter maintenance need. The control system is further configured to periodically obtain differential pressure measurements from the differential pressure sensor and generate an actual trend comprising a series of values, wherein each of the values of the actual trend is derived from one or more of the differential pressure measurements. The control system is further configured to project the actual trend based on the series of values of the actual trend to derive a projected trend and compare the projected trend to the setpoint to predict an end-of-life event that can be used to determine a time at which air filter maintenance is predicted to be needed, wherein the end-of-life event is based on a predicted intersection of the projected trend and the setpoint.

Description

Background Technology

[0001] A motor drive is a power conversion system or "converter" used to provide power to a motor in a controlled manner to control one or more motor performance parameters, such as speed and torque. Often referred to as a variable frequency drive (VFD), such motor drives typically receive multiphase AC input power, which is converted to DC power by a rectifier. This DC power is supplied to and from the DC link to an inverter in a current source drive. The inverter switches the DC link current to provide AC output current to the motor load, which is controlled in a closed-loop manner by the inverter to drive the motor at the desired speed and / or torque. Alternatively, DC power can be supplied directly from the DC link to the load. The rectifier is typically an active switching rectifier that selectively activates switches to provide current from the AC input to the DC link bus, achieving AC-to-DC power conversion. The inverter then implements a switching scheme to selectively connect motor leads to the DC link bus terminals to provide motor phase currents with controlled amplitude, phase, and frequency, enabling specific motor control strategies based on motor performance feedback values ​​and desired performance setpoints or curves. The voltage source drive is similar, but the DC link provides a selected constant DC voltage instead of a selected constant DC current.

[0002] Rectifier and inverter switches are solid-state switching devices, such as gate turn-off thyristors (GTOs), silicon controlled rectifiers (SCRs), insulated-gate bipolar transistors (IGBTs), and symmetrical gate commutated thyristors (SCGTs). Regardless of the specific type of motor drive and switch implemented, switches generate a significant amount of heat that must be dissipated. As the power output ratings of motor drives increase, the need for reliable cooling systems becomes increasingly critical. These cooling systems typically rely on establishing airflow through the motor drive to cool the switches and other components. Therefore, ensuring that the quality (flow rate) of the airflow meets minimum requirements over time is crucial.

[0003] The entire contents of which are expressly incorporated herein by reference, commonly assigned U.S. Patent No. 9,092,030, entitled "Method to Implement Drive Diagnostics and Prognostics Automatically," provides an example of a motor drive that relies on a predictive temperature rise model to determine airflow health. This patent discloses a method for determining drive predictions and / or diagnostics based on ambient temperature sensed in the area of ​​the fan's air inlet.

[0004] When motor drives utilize forced air cooling systems that include air filters, maintaining clean air filters and ensuring fans operate within specifications is one of the primary factors required to sustain the necessary airflow to cool the drive's switches and other electrical components. In larger drives, the number of air filters that need replacement when clogged is considerable. Current methods rely on fixed filter replacement schedules that do not accurately reflect actual operating conditions, especially when such conditions frequently change over time. Therefore, the need has been recognized for systems and methods that predict the air filter maintenance schedule for forced air cooling systems in motor drives to ensure that the motor drives always operate within the manufacturer-specified operating parameters. Summary of the Invention

[0005] According to one aspect of the invention, an airflow health prediction and maintenance system for a motor drive includes a differential pressure sensor that senses the air pressure difference between a sensing location and a reference location within an enclosed cabinet space of the motor drive. The system includes an electronic control system configured to select a setpoint indicating that airflow through the cabinet space has reached a value associated with air filter maintenance needs. The control system is also configured to periodically acquire air pressure difference measurements from the differential pressure sensor and generate a real trend comprising a series of values, wherein each value in the real trend is derived from one or more air pressure difference measurements. The control system is further configured to predict the real trend based on the series of real trend values ​​to derive a predicted trend, and to compare the predicted trend with the setpoint to predict a life-end event, which will be used to determine the predicted time when air filter maintenance is required, wherein the life-end event is based on the predicted intersection of the predicted trend and the setpoint.

[0006] According to another aspect of the invention, a method for predictive maintenance of airflow health for a motor drive includes operating a fan to direct airflow through an enclosed space of a motor drive cabinet, wherein the airflow enters the enclosed space through at least one air filter. A pressure difference generated by the fan is measured between a sensing location and a reference location communicating with the enclosed space to obtain a pressure difference measurement. The method includes at least one of the following: (i) comparing the pressure difference measurement with a pressure difference setpoint and predicting when maintenance of at least one air filter will be required; (ii) deriving an airflow rate based on the pressure difference measurement and comparing the airflow rate with an airflow rate setpoint to predict when maintenance of the at least one air filter will be required. Attached Figure Description

[0007] Figure 1An example of a motor-driven power conversion system (“motor drive”) including an airflow health prediction and maintenance system and method according to an embodiment of the present invention is shown;

[0008] Figure 2 It is a motor-driven power conversion system (e.g., contained within multiple interconnected enclosures or cabinets) Figure 1 A front view of the system shown or another motor drive system.

[0009] Figure 3 This illustrates an airflow health prediction and maintenance system and method that implements an embodiment of the present invention. Figure 2 One of the server racks.

[0010] Figure 4 This is a graph showing the cabinet differential pressure (vacuum) and air filter blockage.

[0011] Figure 5 This is a graph showing the cabinet differential pressure (vacuum) versus time, which shows an increase as air filter clogging increases.

[0012] Figure 6 It is a graph showing how airflow in the cabinet changes over time, showing that it decreases as air filter blockage increases over time.

[0013] Figure 7A and Figure 7B A flowchart is provided, which discloses an example of an airflow health prediction and maintenance system and method according to embodiments of the present invention. Detailed Implementation

[0014] Figure 1 and Figure 2 An example of a motor drive power conversion system 100 (also referred to as a "motor drive unit") is shown, which is used to convert input power, such as single-phase or multi-phase AC power, from the power grid or other source 102 into output AC power 104 for a motor or other load, such that the output power has the desired voltage, current, frequency, and / or phase, thereby driving the load with the desired effect. A DC power output 105 may also be provided. The motor drive unit 100 is housed within a cabinet C or other enclosure or one or more metal sheets containing multiple printed circuit board assemblies (PCBAs) and other components, including the necessary switches and other electrical equipment and circuitry for the operation of the motor drive unit 100 as described below.

[0015] Figure 1An example motor drive 100 includes a rectifier 130 connected to an output inverter 150 via a DC bus circuit or "link" 140. The rectifier 130 includes multiple rectifier switches 130X for rectifying AC input power 102 and supplying it to the DC bus 140. A power conditioning circuit, such as an LCL filter circuit 120, may be connected between the input power 102 and the rectifier 130. The inverter 150 includes multiple inverter switches 150X for inverting the DC bus voltage to the desired AC output power 104. The rectifier switches 130X and inverter switches 150X can each be a gate turn-off thyristor (GTO), a silicon controlled rectifier (SCR), an insulated gate bipolar transistor (IGBT), a symmetrical gate commutated thyristor (SCGT), or other suitable semiconductor switch. The motor drive 100 can be a current source drive or a voltage source drive. In a non-limiting example, the voltage source drive may include a cascaded H-bridge multilevel inverter, but other switching methods may also be used.

[0016] One or more fans 160 are disposed inside or outside the cabinet C to draw ambient air into the cabinet C and circulate the air within and through the cabinet C to cool the switches 130X, 150X, and other electrical components of the motor drive unit 100. The motor drive unit 100 also includes an electronic control system or controller 170, which includes one or more microprocessors, microcontrollers, storage devices, random access memory devices, input / output devices, etc., necessary for the control system 170 to control the fans 160, switches 130X, 150X, and all other components of the motor drive unit 100 based on executed software, firmware, logic, and other control instructions, and also based on feedback signals received from the voltage or current of the output power 104, from the driven motor or other load, or from other sources. The control system 170 is also connected to one or more personal / machine interface (HMI) devices 106, such as one or more keyboards, visual displays, audio devices, touchscreens, or other human input / output devices. The control system 170 is also connected to one or more wired or wireless network interface devices 108, such as network ports, fiber optic transceivers, wireless transceivers, etc., for sending data to one or more connected systems and receiving data from one or more connected systems.

[0017] Figure 2 A front view of a motor drive system, such as system 100 described above, is provided. Figure 2As shown, multiple cabinets C1, C2, and C3 are positioned adjacent to each other and interconnected to define the entire enclosure C. Each cabinet C itself may include multiple cabinets or sub-enclosures. In one example, cabinet C1 is a control cabinet that houses controller 170, and cabinets C2 and C3 are power unit cabinets, transformer cabinets, filter cabinets, or any other cabinets that house switches 130X, 150X, transformers, and other electrical components of motor drive unit 100 and are cooled by forced air. At least some of the cabinets C (e.g., C2 and C3 in the illustrated embodiments) include one or more fans 160 connected thereto (e.g., on the top wall or elsewhere) to implement a forced air cooling system that draws ambient air into the cabinet C and its internal space CS via an air inlet CI formed by an opening defined in the cabinet C (e.g., in a wall or door of the enclosure), circulates the air within and through the enclosed space CS to cool the switches 130X, 150X and other electrical components of the motor drive unit 100 located in the enclosed space CS, and exhausts the air through an air outlet CO. The air inlet CI includes an air filter AF positioned in a covering relationship with the air inlet CI to filter dust, debris and other contaminants from the surrounding or ambient air drawn into the cabinet space CS via the air inlet CI. Although each cabinet C with forced air cooling may utilize only a single fan 160, as shown herein, two or more fans 160 are typically used for each enclosure C to implement forced air cooling to provide increased airflow and redundancy.

[0018] Figure 3 Racks C2 or C3 are illustrated in diagram form, showing that each fan 160 includes a fan shroud 160h containing the fan 160. The fan shroud 160h is connected to rack C. Each fan shroud 160h includes a fan inlet FI and a fan outlet FO. Air is drawn into fan 160 through the fan inlet FI and exhausted by fan 160 through the fan outlet FO. Each fan inlet FI is typically in fluid communication with the internal space CS of rack C near the upper part of rack C, and each fan outlet FO is typically in fluid communication with an air outlet CO, which may be part of the fan shroud 160h. When fan 160 operates to direct airflow from fan inlet FI to fan outlet FO, a pressure difference is established between fan inlet FI (and the internal space CS of rack C) and fan outlet FO. This pressure difference may or may not be equal to the ambient atmospheric pressure outside rack C (C2, C3), where the pressure at fan inlet FI is lower than that at fan outlet FO. The air pressure difference established by fan 160 causes ambient air to be drawn into the rack space CS through air inlet CI, flow through the rack space CS for cooling, flow across fan 160 from fan inlet FI to fan outlet FO, and be discharged through air outlet CO, thereby providing cooling airflow through the rack space CS.

[0019] Continue to refer to Figure 3 At least one of the enclosed cabinets (C2, C3) with forced air cooling, and optionally multiple or all enclosed cabinets (C2, C3) with forced air cooling, include and implement the airflow health prediction maintenance system S according to the present invention. In the case where two or more cabinets C each implement the airflow health prediction maintenance system S, each such system S will operate independently of any other system S. System S includes a differential pressure sensor DP for sensing the pressure difference or differential pressure between a sensing location (e.g., in the central region of the space CS, or in or otherwise adjacent to the fan inlet FI) and a reference location (e.g., the ambient atmosphere outside the cabinet C, or in or otherwise adjacent to the fan outlet FO). The differential pressure sensor DP may be located within the cabinet space CS where the pressure difference is being measured, or it may be located at a distance outside the cabinet space CS, wherein the negative and positive ports of the differential pressure sensor DP are fluidly connected via conduits or the like to the desired sensing location and reference location, such as the sensing location within the internal cabinet space CS and the reference location, such as the ambient atmosphere. The sensed pressure difference measured by the differential pressure sensor DP corresponds to and can represent the vacuum pressure established within the enclosed cabinet space CS due to the operation of fan 160. In the example shown, the differential pressure sensor DP includes a negative (-) pressure port NX and a positive (+) pressure port PX. The differential pressure sensor DP senses the pressure difference between the positive port PX and the negative port NX and outputs an electrical output signal DX having a voltage magnitude proportional to the magnitude of the sensed pressure difference between the positive port PX and the negative port NX, such that the magnitude of the output signal DX varies with the magnitude of the sensed pressure difference. The differential pressure sensor DP is operatively connected to a motor drive controller 170, such that the controller 170 actively monitors the pressure difference signal DX and periodically derives a pressure difference measurement based on the pressure difference signal DX, and uses the measurement value as described below to implement the airflow health prediction and maintenance system and method of the present invention as described herein.

[0020] Figure 3The system S is also shown to include an absolute pressure sensor AP that senses the absolute atmospheric pressure at which the motor drive 100 is located. The absolute pressure sensor may be located inside (as shown) or outside the cabinet space CS, but in each case, it measures the natural or unaffected atmospheric pressure of the ambient atmosphere surrounding the motor drive 100. The absolute pressure sensed by the absolute pressure sensor can be used by the controller 170 to determine the altitude of the drive, as described below. Alternatively, the actual altitude, geographic region, and / or other information can be input to the controller 170 using the HMI 106 and / or network interface 108 or other means, and used by the controller 170 as an altitude parameter (if the altitude is directly input) and / or to derive an altitude parameter (if geographic data or indirect altitude data is input).

[0021] System S may also include a temperature sensor T for sensing the temperature of the ambient atmosphere surrounding the cabinet space CS. Temperature sensor T is operatively connected to controller 170 and provides a signal to controller 170 representing the sensed temperature. Temperature sensor T may additionally or alternatively be configured to sense the temperature of the air within the cabinet space CS, such as the air temperature entering at least one of the fan inlets FI, for input to controller 170.

[0022] like Figure 4 As shown, when the air filter AF of the enclosed cabinet C is clogged with dust and other contaminants, the pressure difference between the enclosed cabinet space CS and the external ambient atmosphere increases as airflow through the filter AF becomes increasingly restricted. The relationship between the percentage of clogging of the enclosed inlet air filter AF on the X-axis and the pressure difference (shown in millimeters (mm) H2O) measured by the differential pressure sensor DP on the Y-axis is non-linear, where the pressure difference increases more rapidly as the filter becomes more clogged, particularly when the filter AF becomes approximately 80% clogged. According to an embodiment of the invention, the baseline setpoint SP1 is selected and implemented by the controller 170 to represent a pressure difference magnitude that indicates the filter AF is sufficiently clogged to require maintenance (replacement and / or cleaning) to remove the contaminants. In one example, the baseline setpoint SP1 is selected to meet a filter clogging percentage of at least 90% (e.g., 92% or 95%). Therefore, when controller 170 receives a differential pressure signal DX from differential pressure sensor DP, controller 170 performs the additional action described below to predict or indicate the need for filter maintenance (i.e., cleaning or replacement of filter AF), the magnitude of which corresponds to the differential pressure across the positive port PX and negative port NX of differential pressure sensor DP, and this differential pressure is close to or equal to the baseline setpoint differential pressure such that the baseline setpoint SP1 is met or satisfied. It should be noted that, although... Figure 4 mm H2O is used as the unit of pressure difference, but any pressure unit can be used alternatively, such as pounds per square inch (PSI), inches (in.) H2O, millibars (mb), etc.

[0023] A baseline setpoint SP1 is selected and stored in the controller 170 based on standard operating condition parameters of the motor drive unit 100 (e.g., standard operating load range (power output range), standard ambient temperature range, standard air quality range in terms of particulate or other pollutant concentrations, and standard altitude range). The baseline setpoint SP1 is also selected based on the minimum airflow required to cool the motor drive unit 100 under nominal (standard expected) operating conditions, wherein the required minimum airflow is converted into a nominal pressure difference (vacuum pressure) within the enclosed cabinet space CS to establish the baseline setpoint SP1. (Continuing to refer to...) Figure 4As can be seen, the invention may optionally also include adjusting the baseline setpoint SP1 to a higher or lower size or level based on actual changes in one or more operating condition parameters to obtain an adjusted setpoint SP2, said operating condition parameters including: (i) operating load range or power output range (expected heat generation within the cabinet space CS); (ii) ambient temperature range; (iii) air quality range in terms of particulate or other contaminant concentrations; and (iv) altitude. The adjusted setpoint SP2 is stored in the controller 170 and used in place of the baseline setpoint SP2 to assess and predict clogging of the enclosed air filter AF. More specifically, when the operating conditions of the motor drive 100 are less demanding and allow less cooling airflow through the cabinet space CS, for example, in at least one of the following situations: (i) lower operating load; (ii) lower ambient temperature; (iii) lower altitude where the fan 160 moves air more effectively, the differential pressure magnitude of the baseline setpoint SP1 is increased (adjusted upwards). Conversely, when the operating conditions of the motor drive are more demanding and require more cooling airflow through the cabinet space CS, such as in at least one of the following situations: (i) higher operating load; (ii) higher ambient temperature; (iii) higher altitude where the fan 160 moves air less efficiently, the differential pressure magnitude of the baseline setpoint SP1 is reduced (adjusted downwards). Furthermore, the baseline setpoint SP1 can be adjusted based on the ambient air quality in terms of particulate contaminant concentration to obtain an adjusted setpoint SP2. When the motor drive 100 is subjected to demanding operating conditions with lower air quality (more particles), the baseline setpoint SP1 is adjusted downwards because the cleaning or replacement of the air filter AF should be performed and / or predicted earlier than the nominal (standard) operating conditions of the motor drive 100. It should be noted that the adjusted setpoint SP2 is not necessarily static when the motor drive 100 operates under different load conditions and ambient air temperature conditions monitored by the controller 170, but can be dynamic and adjusted over time (e.g., each time the controller 170 obtains a differential pressure reading from the differential pressure sensor DP).

[0024] Figure 5This is a graph showing the air pressure difference (mm H2O) on the Y-axis versus the number of weeks of operation of the motor drive 100. The controller 170 implements this predictive maintenance method for the enclosed air filter AF by first determining the initial pressure difference value P1 within the enclosed cabinet space CS with a new (clean / unclogged) filter under various fan operating configurations. It should be noted here that the initial pressure value P1 can vary depending on the number of fans 160 operating at any given time. During the operation of the motor drive 100, the controller 170 periodically samples and stores the air pressure difference signal DX output by the differential pressure sensor DP to obtain air pressure difference readings or measurements. Over time, the controller 170 derives a series of air pressure difference values ​​P2, P3, ..., Pn, which record the change (increase) in pressure difference over time due to clogging of the air filter AF, and these air pressure difference values ​​P2, P3, ..., Pn are saved and monitored by the controller 170. Each pressure difference value P2, P3, ... Pn can be derived from a single pressure difference measurement obtained from the differential pressure sensor DP, or it can be derived from the average of multiple (two or more) pressure difference measurements obtained by the controller 170 from the differential pressure sensor DP over a selected time period, such as obtaining 24 hourly measurements within 1 day (24 hours), obtaining 7 weekly measurements per day within 1 week (7 days), or other measurement frequencies and time periods. The interval for sampling the pressure difference measurements and using them to derive the next pressure difference value P2, P3... Pn can be selected and changed based on ambient air quality (i.e., the expected or actual particulate concentration in the ambient air), the expected or actual operating load of the motor drive unit 100, the expected or actual ambient air temperature, and / or other factors. A series of pressure difference values ​​P1, ..., Pn (each derived from one or more pressure difference measurements) define the actual pressure difference trend PT as shown by the solid line, which indicates the actual pressure difference value determined over several weeks (or other units, such as days, hours, minutes, months, etc.) of operation of the motor drive 100.

[0025] The controller 170 periodically and continuously extrapolates the actual pressure difference trend PT to obtain the projected pressure difference trend PT′ (projected filter clogging trend PT′) as shown by the dashed line. In one example, the controller 170 performs a linear extrapolation to obtain the projected pressure difference trend PT′. Various extrapolation methods, such as linear or nonlinear rate-of-change extrapolation of the actual pressure difference trend PT, may be used alternatively or additionally without departing from the scope and intent of this disclosure to obtain... Figure 5The expected pressure difference trend curve PT″ is shown. The controller 170 also derives the expected end-of-life parameter or value EOL of the air filter AF based on the expected intersection (equal) of the expected pressure difference trend PT′ (or the expected pressure difference trend curve PT″ as shown at EOL″) with the baseline setpoint SP1 or the adjusted setpoint SP2 (if the adjusted setpoint SP2 is used instead of the baseline setpoint SP1). The end-of-life parameter EOL can be expressed as a future time unit starting from the current time, such as several minutes, hours, days, weeks, months, etc. The controller 170 also determines when the actual pressure difference trend PT intersects (equals) with the baseline setpoint SP1 or the adjusted setpoint SP2 (if the adjusted setpoint SP2 is used instead of the baseline setpoint SP1). At this time, the actual end-of-life event of the air filter AF has occurred. In either case, the controller 170 outputs the expected end-of-life or actual end-of-life (EOL) prediction to the user of the motor drive 100 using any known output device (e.g., human / machine interface device 106, wired or wireless network interface device 108, and / or other output devices) to generate a visual or audible warning to the operator of the motor drive 100. The expected EOL event and / or its timing can be displayed to the user, and warnings or alarms can be issued at a predetermined remaining operating time before the air filter AF must be replaced and / or when the air filter AF must be replaced immediately. In one embodiment, for the predicted future filter end-of-life (EOL) event, the controller 170 communicates via an HMI. The outputs of 106 and / or network interface 108 include lower-level warnings (with or without their expected future timing) including visual indications or markings and / or audible outputs, and / or more severe warnings including visual indications or markings and / or audible outputs when the filter has reached or has reached its end-of-life (EOL) period, allowing the user to assess the severity of filter clogging based on the type or severity of the warnings output by controller 170.

[0026] According to embodiments of the invention, it has been found advantageous to implement the above method using fan airflow data rather than differential pressure data. System S uses published airflow-pressure curves for fan 160 to convert the measured differential pressure DP (fan static pressure) across the fan into airflow data expressed in cubic feet per minute (CFM) or other volumetric units. In such an embodiment, the differential pressure sensor DP is operatively connected such that its negative port NX is in fluid communication with a sensing location within or otherwise adjacent to the fan inlet (FI), and its positive port PX, located on the opposite side of the fan and downstream in terms of airflow direction, is in fluid communication with a reference location within or otherwise adjacent to the fan outlet FO of the monitored fan 160, to measure the differential pressure across fan 160. The airflow rate derived from the measured differential pressure across fan 160 using known airflow-pressure relationships for a particular fan 160 will depend on the number of active fans 160, i.e., the published airflow data for a single fan 160 multiplied by the number of active fans causing air movement. For each fan 160, the relationship between airflow and static pressure (“fan curve”) at a selected speed per minute of fan 160 is known and can be implemented in a lookup table (LUT) implemented by controller 170 or other parts of system S. Figure 3 Defined in an altitude or other stored data structure, the controller 170 can convert the sensed differential pressure (DP) across the fan 160 into an airflow rate caused by the fan 160 of a specific fan model. In one embodiment, multiple (e.g., 20 or more) coordinate pairs of input (pressure differential) and output (airflow rate) data points are used in a lookup table to approximate each specific fan curve of interest operating at one or more RPM speeds for the fan 160, with linear interpolation used for intermediate data points between coordinate pairs to obtain an error of <1% relative to consecutive fan curves. Each set of coordinate pairs stored in the lookup table (LUT) approximates a fan curve for a given fan RPM speed. The published and stored static pressure and airflow values ​​are typically based on ideal conditions, such as sea level and 20°C or similar so-called "standard air". The controller 170 can use the aforementioned altitude and temperature data to adjust the airflow data derived from the lookup table (LUT) to derive adjusted airflow data that compensates for reduced air mass that would move at higher altitudes and / or higher temperatures.

[0027] Figure 6As illustrated graphically, when the air filter AF of the enclosed cabinet C is clogged with dust and other contaminants, the airflow rate (shown as CFM on the Y-axis) through the cabinet space S caused by fan 160 decreases over time (shown as weeks on the X-axis). As described above, controller 170 derives the airflow rate based on the differential pressure data DX received from differential pressure sensor DP, using the fan curve stored in a lookup table LUT. As described above, controller 170 can adjust the derived airflow rate based on temperature data received from temperature sensor T and on altitude. As temperature and / or altitude increase and air density decreases, the mass of air moved by fan 160 decreases. In this case, the initially derived airflow rate is adjusted downward to compensate for the fact that less air mass is moved than expected under standard conditions.

[0028] The baseline airflow setpoint ASP1 is also selected and implemented by the controller 170 to represent an airflow magnitude that indicates the filter AF is sufficiently clogged and requires maintenance (replacement and / or cleaning) to remove the clogged contaminants. In one example, the baseline airflow setpoint SP1 is selected to meet at least 80% (e.g., 85% or 90%) of the filter clogging percentage. Therefore, when the controller 170 determines, based on the differential pressure signal DX, that an airflow magnitude equal to or less than the baseline airflow setpoint ASP1 satisfies or meets the setpoint, the controller 170 performs the additional actions described below to predict or indicate the need for filter maintenance (i.e., cleaning or replacement of the filter AF).

[0029] A baseline airflow setpoint ASP1 is selected and stored in controller 170 based on standard operating condition parameters of the motor drive unit 100, such as standard operating load range (power output range), standard ambient temperature range, standard air quality range in terms of particulate or other contaminant concentrations, and standard altitude range. The baseline airflow setpoint ASP1 is selected based on the minimum airflow required to cool the motor drive unit 100 under nominal (standard expected) operating conditions. Controller 170 may optionally adjust the baseline airflow setpoint ASP1 to a higher or lower size or level based on actual changes in one or more operating condition parameters, including: (i) operating load range (power output range); (ii) ambient temperature range; (iii) air quality range in terms of particulate or other contaminant concentrations; and (iv) altitude. The adjusted airflow setpoint ASP2 may be stored in controller 170 and used in place of the baseline airflow setpoint ASP1 for assessing and predicting clogging of the cabinet air filter AF. More specifically, when the less demanding operating conditions of the motor drive 100 allow less cooling airflow through the cabinet space CS, such as at least one of the following: (i) lower operating load; (ii) lower ambient temperature; (iii) lower altitude where the fan 160 moves air more efficiently, the airflow magnitude of the baseline airflow setpoint ASP1 is reduced (adjusted downwards) to obtain the adjusted airflow setpoint ASP2. Conversely, when the more demanding operating conditions of the motor drive 100 require more cooling airflow through the cabinet space CS, such as at least one of the following: (i) higher operating load; (ii) higher ambient temperature; (iii) higher altitude where the fan 160 moves air less efficiently, the magnitude of the baseline airflow setpoint ASP1 is increased (adjusted upwards) to obtain the adjusted airflow setpoint ASP2. Furthermore, the baseline airflow setpoint ASP1 can be adjusted based on ambient air quality in terms of particulate pollutant concentration to obtain a new adjusted airflow setpoint ASP2. When the motor drive 100 experiences operating conditions with lower air quality (more particles), the baseline airflow setpoint ASP1 is adjusted upwards (resulting in more frequent filter AF replacements) because the cleaning or replacement of the air filter AF should be performed and / or predicted earlier compared to the nominal (standard) operating conditions of the motor drive 100. It should also be noted that the adjusted airflow setpoint ASP2 is not necessarily static when the motor drive 100 operates under different load conditions and ambient air temperature conditions monitored by the controller 170, but can be dynamic and adjusted over time (e.g., each time the controller 170 derives an airflow magnitude reading / sample based on the differential pressure data DX).

[0030] Controller 170 implements a predictive maintenance method for the enclosed air filter AF by first determining the initial airflow A1 within the enclosed cabinet space CS with a new (clean / unclogged) air filter AF. During operation of the motor drive unit 100, when the differential pressure increases over time (and the airflow decreases over time) due to clogging of the air filter AF, controller 170 periodically calculates new airflow values ​​A2, A3, ... An based on differential pressure sensor data DX. Airflow values ​​A1, ... An are stored and monitored by controller 170. The interval at which differential pressure is sampled and used to derive airflow can be selected and changed based on ambient air quality (i.e., the expected or actual particulate concentration in the ambient air). Each airflow value A1, ... An can be based on a single differential pressure measurement or a minimum number of measurements averaged over a selected time period, such as the average of 24 measurements acquired hourly throughout the day, the average of 7 measurements acquired daily throughout the week, or some other average. A series of airflow values ​​A1, ..., An define the actual airflow trend of the motor drive 100 over several weeks (or other units, such as days, hours, minutes, months, etc.). The controller 170 periodically extrapolates the airflow trend AT to obtain the expected airflow trend AT′ as shown by the dashed line. In one example, the controller 170 performs linear extrapolation to obtain the expected airflow trend AT′. Various extrapolation methods, such as linear or nonlinear rate-of-change extrapolation of the actual airflow trend AT, may be used alternatively or additionally without departing from the scope and intent of this disclosure to obtain the expected airflow trend AT′. Figure 6 The curved predicted airflow trend curve AT″ is shown. The controller 170 also derives the predicted end-of-life parameter EOL of the air filter AF based on the expected intersection of the predicted airflow trend AT′ (or the predicted airflow trend curve AT″ as shown at EOL″) with the baseline setpoint ASP1 or the adjusted airflow setpoint ASP2 (if the adjusted setpoint ASP2 is used instead of the baseline airflow setpoint ASP1). The end-of-life event parameter EOL can be expressed as a future time unit starting from the current time, such as several minutes, hours, days, weeks, months, etc. Figure 6This is shown as "Remaining Operating Time" RR (also shown at RR' in the expected airflow trend AT'). In this sense, the end-of-life event EOL or EOL' can be used to determine the expected future time when air filter maintenance is required. Controller 170 also determines when the airflow trend AT intersects (is equal to) the baseline airflow setpoint ASP1 or the adjusted airflow setpoint ASP2 (if the adjusted airflow setpoint ASP2 is used instead of the baseline airflow setpoint ASP1)—this indicates that the setpoint has been met or satisfied, and the actual end-of-life event of the air filter AF has occurred. In either case, controller 170 outputs the expected end-of-life EOL event or the actual end-of-life EOL event to the user of the motor drive unit using any known output device (e.g., human / machine interface (HMI) device 106, wired or wireless network interface device 108, and / or other output devices). The event can be determined based on a future date or several future hours. The estimated End-of-Life (EOL) time is displayed to the user in hours, days, or other time units, or in another format. The controller 170 may activate audible and / or visual alarms at the predetermined remaining operating time (RR) before the filter AF must be cleaned or replaced, and / or at the actual time when the filter AF must be cleaned or replaced. The remaining operating time (RR) is equal to the X-axis distance (time) between the current time and the expected intersection of the predicted airflow trend AT′ and the baseline airflow setpoint ASP1 or the adjusted airflow setpoint ASP2. In one implementation, the controller outputs a lower-level visual or audible warning for predicted future filter end-of-life events and a more severe visual or audible warning when the filter's EOL has been reached, allowing the user to assess the severity of filter clogging based on the severity of the warnings output by the controller 170.

[0031] In cases where rack C includes multiple fans 160, it may sometimes be necessary to adjust the differential pressure data DX based on the location (across which fan 160) where the differential pressure sensor DP senses the air pressure, to compensate for possible variations. As described above, in some embodiments, the negative port NX is located in or connected via a conduit to the fan inlet FI of one of the fans 160. Figure 3The diagram shows the main fan 160'. When the main fan 160' is inactive (does not move air), the measured / sensed air pressure difference data DX can be adjusted to compensate for the fact that when the main fan 160' is inactive, the air pressure difference across the inactive main fan 160' measured by the differential pressure sensor DP will actually be the vacuum pressure within the rack space CS (the air pressure difference between the internal rack space CS and the ambient atmosphere outside the drive unit rack C), which will be a lower value (smaller air pressure difference) compared to the air pressure difference sensed when the main fan 160' is active. Specifically, when the main fan 160' is not running, the air pressure difference across the fan sensed by the sensor DP is reduced by the fan compensation amount or value P. hood When the main fan 160' is active (moving air) and when the main fan 160' is inactive (not moving air) while other fans 160 are active, the compensation amount / value P can be determined for the drive unit cabinet C based on sensing and comparing the air pressure difference DX using sensor DP. hood The size of the pressure difference is equal to the fan compensation value P, calculated by comparing the sensed air pressure when the main fan is active at 160° (higher pressure difference) with the sensed air pressure when the main fan is inactive at 160° (lower pressure difference). hood According to one embodiment of the present invention, if the air pressure difference DX is measured when the main fan 160' is not in operation, the air pressure difference DX sensed by the sensor DP is adjusted upward to equal the compensation value P. hood The amount is used to obtain the adjusted pressure difference DX′, such that DX′=DX+P hood In this case, the controller 170 uses the adjusted pressure difference value DX′ to derive the aforementioned pressure difference trends PT, PT′ and airflow trends AT, AT′.

[0032] Figure 7A and Figure 7B (Collectively referred to as Figure 7) provides a flowchart illustrating an example of an airflow health prediction and maintenance system and method according to an embodiment of the present invention. The method can be implemented by a controller 170 or another microprocessor-based system. Step Z1 determines whether one or more of the fans 160 are operable to cool the system 100. If not, step Z1 is repeated. If yes, step Z2 determines whether the main fan 160', across which a differential pressure sensor DP is mounted, is active. If step Z2 determines that the main fan 160' is active, then in step Z3a, the airflow magnitude is derived according to a lookup table LUT based on the differential pressure data DX and the number of active fans 160. Furthermore, in step Z3b, if the stored differential pressure data DX is available from previous readings when the main fan 160' is inactive, the differential pressure compensation value P is calculated. hoodIt is also calculated and stored as described above. If step Z2 determines that the main fan 160' is not active, then step Z3c is based on the adjusted air pressure difference data DX' (as described above, DX' = DX + P). hood Furthermore, the airflow magnitude is derived from the number of fans 160 that move the air during the activity, based on a lookup table (LUT).

[0033] Following step Z3 (either steps Z3a and Z3b or only step Z3c, as the case may be), step Z4 compensates for the airflow magnitude derived in step Z3 based on the altitude of the motor drive unit 100 and also based on the temperature of the air entering the fan inlet FI of at least one of the fans 160, assuming that the mass of air moved by the fans 160 will decrease at higher altitudes or at higher temperatures. This means that in step Z4, the airflow magnitude derived in step Z3 based on standard air will be adjusted (reduced) according to the increased altitude and / or increased temperature to obtain the true airflow magnitude.

[0034] Step Z5, comprising steps Z5a and Z5b, is performed to select a baseline airflow setpoint ASP1 and adjust ASP1 to obtain an adjusted airflow setpoint ASP2. Specifically, step Z5a is performed to determine the baseline airflow setpoint ASP1 and adjust it based on temperature and altitude to arrive at the adjusted airflow setpoint ASP2. In step Z5b, the adjusted airflow setpoint ASP2 is stored in memory, and a counter is incremented to track the number of airflow measurements obtained. Step Z5 may include additional compensations, such as adjustments to the baseline airflow setpoint ASP1 based on the operating load of the drive unit 100.

[0035] Following step Z5, step Z6 determines whether the number of airflow measurements is equal to or greater than the required minimum operating time (e.g., the minimum number of measurement samples to be acquired within a selected number of days or more X), and if so, performs step Z7, which includes the following steps Z7a, Z7b, and Z7c:

[0036] Z7a - Averages the airflow measurement data to obtain airflow values ​​A1, ..., An, and also averages all adjusted airflow setpoints ASP2 associated with the airflow sample data to obtain the current adjusted airflow setpoint ASP2.

[0037] Z7b - Based on real-world data, using linear, linear rate of change, non-linear rate of change, or as mentioned above. Figure 6 The other extrapolation methods described above predict (extrapolate) the updated airflow trend AT to derive the expected airflow trend AT′; and,

[0038] Z7c - Find the intersection of the expected airflow trend AT′ and the adjusted airflow setpoint ASP2 to find the end-of-life event EOL, and estimate the remaining running time RR, which is the time between the current time and the end-of-life event EOL.

[0039] Alternatively, if step Z6 determines that more airflow magnitude measurements are needed before averaging to calculate the next airflow value A1, ..., An, then a delay timer step Z8 is implemented to delay for a selected amount of time (e.g., 15 minutes) before control returns to step Z1 to repeat the process to obtain another airflow magnitude measurement.

[0040] Various embodiments have been described in the foregoing specification with reference to the accompanying drawings. However, it will be apparent that various modifications and alterations can be made thereto, and additional embodiments can be implemented, without departing from the broader scope of the invention as set forth in the appended claims. Therefore, the specification and drawings are to be considered illustrative rather than restrictive.

Claims

1. An airflow health prediction and maintenance system for a motor drive device, the system comprising: A differential pressure sensor senses the pressure difference between a sensing position within the enclosed cabinet space of the motor drive device and a reference position outside the enclosed cabinet space, wherein the pressure difference represents the vacuum pressure inside the enclosed cabinet space. The electronic control system is configured as follows: The selection indicates that the airflow through the enclosed cabinet space has reached a set point associated with the need to perform air filter maintenance, the air filter being configured to filter the air flowing into the enclosed cabinet space; The differential pressure sensor periodically obtains differential pressure measurements and generates a real trend comprising a series of values, wherein each value in the real trend is derived from one or more of the differential pressure measurements. Based on the series of values ​​representing the actual trend, the actual trend is predicted to arrive at the predicted trend; and The predicted trend is compared with the setpoint to predict a life-end event, which is used to determine the predicted time when air filter maintenance is required, wherein the life-end event is based on the predicted intersection of the predicted trend and the setpoint.

2. The airflow health prediction and maintenance system according to claim 1, wherein, The system includes at least one fan for guiding the airflow.

3. The airflow health prediction and maintenance system according to claim 2, wherein: The setpoint includes a pressure difference setpoint defined based on the pressure difference between the enclosed cabinet space and the reference position; and The actual trend includes the actual pressure difference trend, and for the actual pressure difference trend, the series of values ​​includes a series of pressure difference values ​​derived from the pressure difference measurements.

4. The airflow health prediction and maintenance system according to claim 3, wherein, The electronic control system is also configured to output warnings related to the end-of-life event to at least one of: (i) a human-machine interface; and (ii) a network interface.

5. The airflow health prediction and maintenance system according to claim 4, wherein, The electronic control system is also configured to adjust the differential pressure setpoint based on at least one of the following: (i) the operating load associated with the motor drive; (ii) the temperature of the ambient atmosphere surrounding the motor drive; (iii) the air quality in terms of the concentration of particulate matter or other pollutants in the ambient atmosphere; and (iv) the altitude of the motor drive.

6. The airflow health prediction and maintenance system of claim 1 further includes an absolute pressure sensor for sensing the atmospheric pressure of the ambient atmosphere surrounding the motor drive device.

7. The airflow health prediction and maintenance system according to claim 1 further includes: At least one fan directs airflow through the enclosed cabinet space by moving air from the fan inlet of the at least one fan to the fan outlet of the at least one fan, wherein the sensing position and the reference position are located on opposite sides of the fan inlet and the fan outlet of the at least one fan, respectively, such that the air pressure difference measurement is obtained across the at least one fan.

8. The airflow health prediction and maintenance system according to claim 7, wherein: The setpoints include airflow setpoints defined based on the airflow rate through the enclosed cabinet space; and The series of values ​​for the actual trend includes a series of airflow values ​​that define the actual airflow trend, wherein each of the series of airflow values ​​is derived from one or more of the pressure difference measurements.

9. The airflow health prediction and maintenance system according to claim 8, wherein, The electronic control system is also configured to: The predicted trend is compared with the setpoint to determine the lifespan termination event when the predicted trend equals the airflow setpoint.

10. The airflow health prediction and maintenance system according to claim 9, wherein, The electronic control system is configured to output an alarm to at least one of the following: (i) a human-machine interface; and (ii) a network interface, the alarm providing information about the expected timing of the end-of-life event.

11. The airflow health prediction and maintenance system according to claim 10, wherein, The electronic control system is also configured to adjust the airflow setpoint based on at least one of the following: (i) the operating load associated with the motor drive; (ii) the temperature of the ambient atmosphere surrounding the motor drive; (iii) the air quality in terms of the concentration of particulate matter or other pollutants in the ambient atmosphere; and (iv) the altitude of the motor drive.

12. The airflow health prediction and maintenance system according to claim 11, wherein, The at least one fan includes a plurality of fans, one of which is a main fan, and wherein the differential pressure sensor senses a measurement of the air pressure difference across the main fan between the fan inlet and the fan outlet of the main fan.

13. The airflow health prediction and maintenance system according to claim 12, wherein, When the air pressure difference measurement is acquired while the main fan is inactive and at least one of the other fans is active, the electronic control system adds a selected compensation amount to the air pressure difference measurement.

14. The airflow health prediction and maintenance system according to claim 13, wherein, The selected compensation amount is related to the difference in air pressure sensed by the differential pressure sensor when the main fan is active compared to when the main fan is inactive.

15. The airflow health prediction and maintenance system according to claim 7, wherein, The at least one fan includes a plurality of fans, one of which is a main fan, and wherein the differential pressure sensor senses a measurement of the air pressure difference across the main fan between the fan inlet and the fan outlet of the main fan.

16. A method for predictive maintenance of airflow health in a motor drive device, the method comprising: Operate a fan to direct airflow through the enclosed space of the cabinet of the motor drive unit, wherein the airflow enters the enclosed space through at least one air filter; A differential pressure sensor senses the air pressure difference generated by the fan between a sensing position communicating with the enclosed space and a reference position outside the enclosed space to obtain a differential pressure measurement representing the vacuum pressure inside the enclosed space; and At least one of the following: (i) Compare the measured differential pressure value with a differential pressure setpoint and predict when maintenance of the at least one air filter will be required; and (ii) Calculate the flow rate of the airflow based on the air pressure difference measurement, and compare the flow rate of the airflow with the airflow flow rate set value to predict when the at least one air filter will need to be maintained.

17. The method for predicting and maintaining airflow health according to claim 16, the method further comprising: The actual trend of generating pressure difference values, wherein each of the pressure difference values ​​is derived from at least one of the pressure difference measurements; Extrapolate the actual trend of the pressure difference to derive the predicted trend of the pressure difference; and The predicted trend of the air pressure difference is compared with the air pressure difference setpoint to predict the end-of-life event of the at least one air filter.

18. The method for predicting and maintaining airflow health according to claim 17, further comprising: The differential pressure setpoint is periodically and dynamically adjusted based on at least one of the following: (i) the operating load of the motor drive device; (ii) The ambient temperature surrounding the motor drive device; The altitude of the motor drive device described in (iii).

19. The method for predicting and maintaining airflow health according to claim 16, the method further comprising: The actual trend of generating airflow flow values, wherein each of the airflow flow values ​​is derived based on at least one of the air pressure difference measurements; Extrapolate the actual trend of the airflow rate value to derive the predicted trend of the airflow rate; and The predicted trend of airflow rate is compared with the airflow rate setpoint to predict the end-of-life event of the at least one air filter.

20. The method for predicting and maintaining airflow health according to claim 19, further comprising: The airflow setpoint is periodically and dynamically adjusted based on at least one of the following: (i) the operating load of the motor drive device; (ii) The ambient temperature surrounding the motor drive device; The altitude of the motor drive device described in (iii).

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