Medium Voltage Variable Frequency Drive with Artificial Intelligence

Abstract

A variable frequency drive system, comprising: a power converter having a plurality of power units supplying power to one or more output phases, each power unit having a plurality of switching devices including semiconductor switches; a plurality of sensors for monitoring values of the power converter; and a control system in communication with the power converter and controlling the operation of the plurality of power units, the control system including a processor configured by executable instructions to: access a first reduced-order model of the power converter; receive values provided by the plurality of sensors; analyze the values in combination with the first reduced-order model to determine one or more operating modes; and output the one or more determined operating modes of the power converter.

Description

[0001] Background

[0002] 1. Field

[0003] Aspects of the present disclosure generally relate to a drive system with artificial intelligence, and more particularly, to a control system and a control method for a drive system, such as a medium voltage variable frequency drive. Throughout the specification, the terms "drive", "drive system", "converter", and "power supply" may be used interchangeably.

[0004] 2. Description of Related Art

[0005] Multiple medium voltage (MV) variable frequency drives, such as multiple multilevel power converters, are used in applications of medium voltage alternating current (AC) drives, flexible AC transmission systems (FACTS), and high voltage direct current (HVDC) transmission systems because a single power semiconductor device cannot handle high voltages. A multilevel power converter generally includes multiple power units for each phase, and each power unit includes an inverter circuit having semiconductor switches that can change the voltage output of each unit.

[0006] An example of a multilevel power converter is a cascaded H-bridge converter system having multiple H-bridge units as described, for example, in U.S. Patent No. 5,625,545 to Hammond, the content of which is hereby incorporated by reference in its entirety. Another example of a multilevel power converter is a modular multilevel converter system having multiple M2C or M2LC subsystems.

[0007] A medium voltage drive includes a digital control system for a specific purpose. The digital control system splits the commands and states of the control loop, the power unit control information, and the tasks of the external communication interface into three independent components. The three independent main components are a control processor / host central processing unit for control loop commands, states, and non-drive interfaces, a field programmable gate array (FPGA) for power unit control and communication, and an electronically programmable logic device (EPLD) for external communication. The main components need dedicated data buses on a printed circuit board (PCB) so that the main components can exchange information between them for the drive system to operate successfully.

[0008] Summary

[0009] Briefly, aspects of the present disclosure relate to a drive system, which is embodied as a medium voltage variable frequency drive, for example, and more particularly, to a control system and a control method for a drive system.

[0010] A first aspect of the present disclosure provides a variable frequency drive system, comprising: a power converter including a plurality of power units supplying power to one or more output phases, each power unit including a plurality of switching devices including semiconductor switches; a plurality of sensors for monitoring values of the power converter; and a control system in communication with the power converter and controlling the operation of the plurality of power units, the control system including at least one processor configured by executable instructions to: access a first reduced-order model of the power converter; receive values provided by the plurality of sensors; analyze the values in combination with the first reduced-order model to determine one or more operating modes; and output one or more determined operating modes of the power converter.

[0011] A second aspect of the present disclosure provides a method for controlling a variable frequency drive, comprising by operating at least one processor: accessing a reduced-order model of a power converter; receiving sensor values of the power converter provided by sensors; analyzing the sensor values in combination with the reduced-order model to determine an operating mode of the power converter; and outputting the operating mode.

[0012] A third aspect of the present disclosure provides a non-transitory computer-readable medium encoded with processor-executable instructions that, when executed by at least one processor, cause the at least one processor to perform a method for controlling a variable frequency drive as described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A schematic diagram illustrating a known basic configuration of a cascaded H-bridge converter system according to an exemplary embodiment disclosed herein.

[0014] Figure 2 A schematic diagram illustrating an additional known basic configuration of a cascaded H-bridge converter system according to an exemplary embodiment disclosed herein.

[0015] Figure 3 A schematic diagram illustrating a drive system according to an exemplary embodiment disclosed herein.

[0016] Figure 4 A schematic diagram illustrating a drive system with a control system according to an exemplary embodiment of the present disclosure.

[0017] Figure 5 A schematic diagram illustrating a control system utilizing a reduced-order model according to an exemplary embodiment of the present disclosure.

[0018] Figure 6 A flowchart illustrating a method for controlling a variable frequency drive according to an exemplary embodiment of the present disclosure.

[0019] DETAILED DESCRIPTION

[0020] To facilitate an understanding of the embodiments, principles, and features of the present invention, the following will be described with reference to the implementation in illustrative embodiments. In particular, it is described in the context of a control system for a variable frequency drive, particularly a medium voltage (MV) variable frequency drive, which includes a multi-cell power supply, such as a modular multilevel converter system and a cascaded H-bridge converter system. However, embodiments of the present invention are not limited to use in the described apparatus or method.

[0021] As used herein, "medium voltage" is a voltage greater than about 690V and less than about 69KV, while "low voltage" is a voltage less than about 690V. Those of ordinary skill in the art will understand that other voltage levels may be designated as "medium voltage" and "low voltage". For example, in some embodiments, "medium voltage" may be a voltage between about 3kV and about 69kV, and "low voltage" may be a voltage less than about 3kV.

[0022] The components and materials constituting the various embodiments described hereinafter are intended to be illustrative and not restrictive. Many suitable components and materials performing the same or similar functions as the materials described herein are intended to be included within the scope of the embodiments of the present invention.

[0023] Figure 1 and Figure 2 respectively illustrate schematic diagrams of a known multi-cell power supply 10, particularly a cascaded H-bridge converter system, which receives three-phase power from an alternating current (AC) source and delivers power to a load 12, such as a three-phase AC motor.

[0024] Referring to Figure 1 , the multi-cell power supply 10 includes a transformer 14, a power circuit 16, and a controller 18, which is also referred to herein as a control system. The transformer 14 includes a primary winding that energizes nine secondary windings, and the power circuit 16 includes a plurality of printed circuit board (PCB) power units 26, which are simply referred to herein as power units 26, and are operatively coupled to the secondary windings of the transformer 14, respectively. Since the power supply 10 includes nine secondary windings and the power units 26 are operatively coupled to each secondary winding, the power supply 10 includes nine power units 26. Of course, the power supply 10 may include more or fewer than nine power units 26 and / or more or fewer than nine secondary windings, depending on the type of the power supply 10 and / or the type of the load 12 coupled to the power supply 10.

[0025] The power unit 26 can be rated for a lower voltage and is configured to provide a medium voltage output to the load 12. Each output phase A, B, C of the power circuit 16 is powered by a set of power units 26 connected in series. The outputs of the power units 26 are coupled in series in the first phase group 30, the second phase group 32, and the third phase group 34. Each phase output voltage is the sum of the output voltages of the power units 26 in the corresponding phase groups 30, 32, and 34. For example, the first phase group 30 includes power units 26 labeled A1, A2, and A3, where the phase output voltage of output phase A is the sum of the output voltages of power units A1, A2, and A3. This also applies to output phase B and power units B1, B2, B3, and output phase C and power units C1, C2, C3. In this regard, the power circuit 16 uses power units 26 rated for a lower voltage to provide a medium voltage output to the load 12, and these power units rated for a lower voltage include components rated for a lower voltage standard. Each power unit 26 is coupled to the controller 18, for example, via an optical fiber communication link, and the controller can use current feedback and voltage feedback to control the operation of the power unit 26.

[0026] As Figure 2 illustrated, the multi-unit power supply 10 includes a three-phase AC power supply 20, a power circuit 16, and a controller 18. The three-phase AC power supply 20 includes two diode bridges 22, each diode bridge is connected to the secondary winding of the power converter transformer 24 on the AC voltage side and is electrically connected in series on the DC (direct current) voltage side. Positive and negative DC voltage buses are provided for the parallel connection of these phase groups. The power circuit 16 includes power units 28, and these power units are coupled to the DC voltage buses created by the power supply 20. The power units 28 are, for example, rated for a lower voltage and are configured to provide a medium voltage output to the load 12. Although the load 12 can be illustrated as being within the multi-unit power supply 10, the load 12 is not part of the multi-unit power supply 10. Instead, as Figure 1 more clearly shown, the load 12 is separated from the multi-unit power supply 10 and is connected to the multi-unit power supply 10.

[0027] Each output phase A, B, C of the power circuit 16 is powered by a set of power units 28 connected in series, that is, with reference to output phases A, B, C, these power units are labeled A1 - A4, B1 - B4, and C1 - C4. The power units 28 are coupled in series in the first phase group 30, the second phase group 32, and the third phase group 34. As previously referenced Figure 1As described, each phase output voltage is the sum of the output voltages of the power cells 28 in phase groups 30, 32, and 34. The power circuit 16 uses power cells 28 rated for a lower voltage to provide a medium voltage output to the load 12, and these power cells rated for a lower voltage include components rated for a lower voltage standard. Each power cell 28 is coupled to the controller 18, for example, via one or more fiber optic communication links, and the controller can use current feedback and voltage feedback to control the operation of the power cell 28.

[0028] It should be noted that in Figure 1 and Figure 2 , the number of power cells 26, 28 in each phase group 30, 32, 34 can be between 2 and 12 to provide different medium voltage outputs according to the requirements of the load 12. As previously mentioned, in Figure 1 's embodiment, the number of secondary windings of the transformer 14 matches the number of power cells 26. In Figure 2 's embodiment, the number of diode bridges and secondary windings of the transformer can vary from 1 to 6 to allow for harmonic elimination on the primary side of the transformer 24. Those of ordinary skill in the art will understand that additional numbers of units and diode bridges can be used according to the application, and the configurations shown and described herein are intended to be exemplary in nature.

[0029] Figure 3 Illustrates a schematic diagram of a drive system 300 that includes a cascaded H-bridge multilevel converter 310 having a seven-level topology, including three phases, each phase having three power cells. According to one aspect of the present disclosure, the drive system additionally includes a control system 400. An example of the cascaded H-bridge multilevel converter 310 is the PerfectHarmony driver manufactured by Siemens Industry, Inc.

[0030] In Figure 3 's example, the system 300 is a medium voltage drive that includes a three-phase power supply that provides a power input 302 via lines L1, L2, and L3. The multilevel converter 310 is connected to the AC power input 302 and generates a three-phase AC power supply as an output 303 via output phases A, B, and C. The AC output 303 can be connected to a load 320, which in this example includes an electric motor. The electric motor 320 can be operated by controlling the frequency and / or amplitude of the output voltage generated by the multilevel converter 310.

[0031] Each phase of the multilevel converter 310 includes a corresponding phase arm, and the phase arm is formed by a plurality of power cells 312 arranged in a cascaded manner. In Figure 1In the example, phase legs Leg A and Leg B are each formed by the same number (i.e., three) of power units 312, which are connected in series. Each power unit 312 in a phase is connected to the power input 302 via respective input lines L1, L2, and L3. The power to the input lines L1, L2, and L3 can be provided, for example, by a polyphase winding transformer.

[0032] The power units 312 of the three phases are respectively labeled as unit A1 to unit A3, unit B1 to unit B3, and unit C1 to unit C3. Each power unit 312 responds to a control signal from the control system 400, which includes, for example, a pulse width modulation (PWM) signal to change the voltage level and / or frequency output, thereby resulting in a multi-level voltage waveform for each phase. The power unit 312 generally includes a power semiconductor switching device, passive components (inductors, capacitors), a control circuit, a processor, an interface, and other components for communicating with the control system 400, i.e., the power unit 312 operates based on signals from the control system 400.

[0033] Each of the power units 312 includes a single-phase inverter circuit, which is connected to an independent direct current (DC) source that is generated by rectifying the AC power input for each power unit 312 via the input lines L1, L2, and L3. In this example, the rectification is performed by diode rectifiers 313a-f, which are arranged in a bridge rectifier configuration. This example also uses a filter circuit, which includes, for example, a capacitor 314, for smoothing the voltage ripple from the rectified DC power.

[0034] The inverter circuit of each unit 312 includes power semiconductor switching devices 315a-d, which are arranged in an H-bridge (also known as a full bridge) configuration. The switching devices 315a-d can include, for example, but are not limited to, power transistors such as insulated gate bipolar transistors (IGBTs). The switching devices 315a, 15b are connected to the unit output line 316a, while the switching devices 315c, 315d are connected to the unit output line 316b. The transistors 315a-d receive pulse width modulation signals, for example, in the form of pulse width modulation signals as gate input signals 318 controlled by the control system 400 based on pulse width modulation. The control system 400 selects any one of the transistors 315a or 315b to conduct through the first switch arm 317a, and selects any one of the transistors 315c or 315d to conduct through the second switch arm 317b, which will allow power to be transferred to the load 320 through the lines 316a or 316b respectively. In other words, the switching event of the switch arm 317a triggered by the controller causes one of the transistors 315a, 315b to be in the on state and the other to be in the off state. Similarly, the switching event of the switch arm 317b triggered by the controller causes one of the transistors 315c, 315d to be in the on state and the other to be in the off state. In the illustrated embodiment, the switch arms 317a, 317b of a single unit 312 are simply referred to as switch arm A and switch arm B of that single unit 312.

[0035] Although each of the power units 312 is included in the medium voltage device driver 300, its internal can be constructed for low voltage standards. For example, each power unit 312 can have a rating of 600 volts. Therefore, the maximum voltage level that can be output by each of the power units 312 is approximately 600 VDC. Depending on which transistor conducts, the output voltage on the unit output lines 316a, 316b of each power unit 312 can be either polarity or zero. Therefore, each power unit 312 can have three output states: +600 VDC, -600 VDC, or zero VDC. Due to the series connection between the three power units 312 in each phase output line, for example, units A1, A2, A3 to output phase A, a maximum output voltage amplitude of approximately 1800 VDC can be generated for the corresponding phase output line. Each power unit 312 can operate independently of other power units. Therefore, at least seven voltage levels per phase can be provided to the motor 320. The approximations of these line-neutral voltage states include + / -1800 VDC, + / -1200 VDC, + / -600 VDC, and zero VDC.

[0036] The electric motor 320 can include any type of AC motor, such as synchronous, asynchronous, permanent magnet motors, and can be rated for low voltage, medium voltage, or high voltage. For example, medium voltage AC motors, such as those used in industrial process control, can operate in the range of 4.16 kV to 13.8 kV. Larger or smaller voltages can be used. More than one electric motor 320 can be connected. Other loads can be used instead of or in addition to the electric motor 320. The electric motor 320 responds to the voltage applied by the multi-level converter on three phases to increase, decrease, or maintain a speed or position, for example.

[0037] Figure 4 A schematic diagram of a drive system 450 with a control system 400 according to an exemplary embodiment of the present disclosure is illustrated.

[0038] As previously described, for example, with reference to Figure 1 and Figure 2 , the drive system 450 (such as a medium voltage variable frequency drive) generally includes a power transformer 460, a power (electronic) converter 470, a control system 400 (also referred to herein as a controller 400), and one or more cooling components 480. The one or more cooling components 480 can be configured as air-cooled components, water-cooled components, or a combination of both. The power transformer 460 converts an input medium voltage, for example, between 1 kV - 33 kV, to an available voltage for the power converter 470, such as an available voltage of 480 V - 1500 V. The power converter 470 utilizes rectification and inversion stages to convert the secondary side voltage from the power transformer 460 in order to provide a variable frequency, for example, between 0 Hz – 500 Hz, and a variable voltage, for example, between 0 V - 14.4 kV, at the output. In one embodiment, the power converter 470 can include multiple power units as previously described. The controller 400 of the drive system 450 regulates and controls the operation of the drive components through a data connection (such as a data bus 402) to provide a desired frequency and voltage at the output based on commands, for example, commands previously stored in the controller 400 or commands received from an external control system (such as a customer control system). Additionally, the controller 400 performs drive protection functions and provides the drive status to the customer or user of the drive system 450.

[0039] For the operation of the drive system 450, the control system 400 (also referred to herein as the main control system or the central control system 400) includes a field programmable gate array (FPGA), a control processor in communication with the FPGA, an electronically programmable logic device (EPLD), and a host. The main control system 400 also includes a parallel bus, and the FPGA, the EPLD, and the host are respectively connected to the parallel bus. According to different embodiments, the FPGA is based on RAM and is configured to communicate with one or more digital-to-analog converters (DACs), one or more analog-to-digital converters (ADCs), a power unit bypass system, multiple power units, an encoder, one or more input / output interfaces, and an internal network. Further details of the known functions and elements of the control system 400 are not described further herein.

[0040] In addition, the drive system 450 includes a plurality of sensors 490 (only schematically and centrally shown for the system 450) to monitor various characteristics and values of the drive system 450. For example, the sensors 490 include sensors for measuring and monitoring the input voltage, output voltage, input current, output current, internal temperature of the transformer 460 and / or the power converter 470 and / or the cooling component 480 of the power converter 470. The addition of sensors 490 for monitoring the coolant flow rate and coolant pressure drop between the cooling outlet and inlet of the cooling component 480 and the addition of sensors 490 for monitoring the vibration of the drive system 450, such as the vibration of the transformer 460 or the power converter 470, allow the acquisition of information and data that can be used to provide predictive maintenance capabilities and diagnostic capabilities. The sensors 490 provide sensor data, such as values and / or measurements of temperature, vibration, current, and voltage, to the control system 400 via the data bus 402.

[0041] In addition, the drive system 450 includes one or more reduced-order models 440 received and stored by the controller 400. The reduced-order model 440 (also referred to as ROM) can be defined as a simplification of a high-fidelity dynamic model that retains the basic behavior and dominant effects, with the aim of reducing the solution time or storage capacity required for a more complex model. The drive system 450 can include, for example, a ROM of the power converter 470 and / or a ROM of the transformer 460.

[0042] Using multiple sensors 490 and one or more reduced-order models (ROMs) 440, drive system 450 provides an improved control system 400 and an improved control method. The improved drive system 450 includes artificial intelligence capabilities. Such artificial intelligence capabilities can include, for example, self-learning capabilities, predictive maintenance capabilities, and mobile application (also referred to as "mobile app") capabilities. Accordingly, controller 400 includes a self-learning module 410, a preventive maintenance module 420, and a mobile application module 430. The self-learning module 410 and the preventive maintenance module 420 are configured to be connected to a communication network, such as an intranet (of a drive vendor or drive customer), the Internet, Ethernet, etc., for data mining, data clustering analysis, etc. The mobile application module 430 is configured to be connected to a mobile device 432, such as a smart phone or a tablet computer, so that if such a capability is enabled by a customer or user of the drive system 450, the control system 400 can receive inputs, such as commands, from the module 430 via the mobile application of the mobile device 432. Generally, the mobile device application 430 can be used to obtain current performance data, maintenance data, while the main control of the drive operation will still reside in the main control logic of the controller 400. For example, the preventive maintenance module 420 and the mobile application module 430 allow additional applications, such as customer-specific applications, to be added or loaded to the controller 400, and these customer-specific applications provide post-processing of drive data independent of the control process executed by the control system 450. In another example, for instance, after a customer or user later purchases a software upgrade, additional applications or control features can be remotely (e.g., wirelessly) loaded, added, and / or enabled by the drive vendor.

[0043] Using modules 410, 420, 430, sensor values provided by sensors 490 and ROM 440; drive system 450 provides an adaptive response to allow for optimal operation of drive system 450, preventive maintenance of various components of drive system 450; and obtaining data mining tools and large data analysis. The improved drive system 450 and controller 400 will be described in more detail with reference to the following drawings.

[0044] Figure 5 A schematic diagram illustrating a control system 400 utilizing a reduced-order model (ROM) according to an exemplary embodiment of the present disclosure.

[0045] Figure 5Schematically illustrates the transformer 460, the power converter 470, and the cooling component 480 of the drive system. The control system 400 (or simply referred to as the controller 400) includes a plurality of components, which includes a first reduced-order model ROM-1 and a second reduced-order model ROM-2. In addition, the controller 400 includes at least one processor 412, such as a central computing unit (CPU), which executes computer-readable instructions. Here, the controller 400 may also be referred to as the central controller 400 of the drive system 450.

[0046] The transformer 460, the power converter 470, and the cooling component include a plurality of sensors. For example, the power converter 470 includes a radiator sensor 472 for measuring the internal relevant temperature of the radiator and an airflow sensor 474 for measuring the internal relevant airflow of the power converter 470. In addition, the power converter 470 is configured to monitor and evaluate the actual power consumed inside the semiconductor switch and / or to monitor the temperature of the capacitor, for example, the power consumed inside the capacitor.

[0047] The transformer 460 may include a sensor 462 for measuring the temperature at a predetermined position on the secondary winding of the transformer 460 and a sensor 464 for measuring the temperature of the iron core of the transformer 460. For the purpose of arc fault detection, the transformer 460 may further include an optical sensor 466 located at the primary winding.

[0048] The cooling component 480 may include a sensor 482 for monitoring the coolant flow rate and the coolant pressure drop between the coolant outlet and the coolant inlet.

[0049] The drive system 450 further includes one or more vibration sensors 452, which are used to monitor the vibrations of the components of the drive system 450, such as the transformer 460, the power converter 470, and the cooling component 480, to determine the mechanical conditions requiring maintenance.

[0050] In an exemplary embodiment, the drive system 450 includes a first reduced-order model ROM-1, which is a computationally-derived computational fluid dynamics (CFD) reduced-order model of the power converter 470. The reduced-order model ROM-1 of the power converter 470 is essentially a multi-dimensional response surface. It can have multiple inputs and multiple outputs. For example, the ROM-1 for the power converter 470 can have 3 (three) inputs and any number of outputs, depending on the semiconductor devices used. The inputs to be considered can be the ambient temperature, the air flow rate, and the dissipation power ratio. The outputs can include the junction temperatures of all the individual transistors within the semiconductor switches, such as insulated gate bipolar transistors (IGBTs). Since the IGBTs can be different, the number of individual transistors varies internally, typically between 4 and 12. The temperature of the heat sink at a fixed location within the power converter 470 associated with an actual measurement device (thermal probe) can also be included in the output set.

[0051] ROM-1 can be obtained through complex CFD software simulations. The input parameters (primarily the air flow rate and the dissipation power ratio) are varied and given several fixed values, such as 5 (five) fixed values for the air flow rate and 5 (five) fixed values for the dissipation power. Thus, using 5 power values and 5 air flow values, a total of 5 * 5 = 25 simulations are provided. For each simulation, all the output values are recorded in ROM-1. The end result of this process is a multi-dimensional look-up table, as described above, which has 3 (three) inputs and a variable number of output temperatures. It may not be necessary to run ROM-1 at different values of the input ambient temperature, since the effect of this parameter is mainly to scale the output temperatures up and down.

[0052] ROM-1 can be included in the system-level simulation software such that when the inputs vary within the simulation range, the outputs will be continuously available due to interpolation between the simulation points. For example, linear or spline interpolation can be used.

[0053] ROM-1 is loaded and stored in the drive control memory 414, which can be a memory external to the controller 400 or a memory internal to the controller 400.

[0054] In an exemplary embodiment, at least one processor 412 is configured by executable instructions to: access or receive a first reduced-order model ROM-1 to receive sensor values provided by a plurality of sensors 452, 462, 464, 472, 474, 482, 484; analyze the sensor values in combination with ROM-1 to determine one or more operating modes 416; and output one or more of the determined operating modes 416. For analyzing the sensor values in combination with the first reduced-order model ROM-1, for example, it includes inputting the sensor values into ROM-1, performing the calculations of ROM-1, and obtaining the output value of ROM-1 based on the actual sensor values used as input values. The analysis may also include comparing the sensor values with certain values of the first reduced-order model ROM-1 without performing / executing a full simulation of ROM-1.

[0055] The operating mode 416 used herein may include an operating mode describing the current state of the system 450, for example, including the temperature at certain locations, especially detecting hot spots of the system 450. Such detected hot spots may trigger an alarm issued by the control system 400. The operating mode 416 may also include a modified operating mode proposed by the control system 400, for example, in order to improve the efficiency of the system 450 or reduce the cost of operating the system 450.

[0056] The operating mode 416 determined by the control system 400 may include, for example, a modified operating mode of the power converter and / or a modified operating mode of the cooling component 480. For example, the modified operating mode 416 of the power converter 470 includes modifying the output voltage by increasing or decreasing the output voltage based on the analyzed sensor values and the reduced-order model ROM-1. For example, if the evaluated air flow rate and dissipated power ratio in the semiconductor switch are lower than the corresponding calculated values in the first reduced-order model ROM-1, the operation of the power converter 470 may be changed such that the power converter 470 outputs more voltage and / or the cooling of the power converter 470 by the cooling component 480 may be reduced. Conversely, when it is evaluated that the sensor value is higher than the corresponding calculated temperature value in ROM-1, the operation may be changed such that the power converter 470 outputs less voltage and / or the cooling of the power converter 470 by the cooling component 480 may be increased.

[0057] For example, by accessing ROM-1 through at least one processor 412, based on actual inputs such as the actual power consumed inside the IGBT (which is a value that the power converter 470 can continuously evaluate) and the air flow measured by the sensor 474, certain temperatures at selected locations inside the IGBT of the power converter 470 are evaluated. The output value of such an IGBT location (actually a hot spot) can be retrieved and an alarm can be issued if necessary.

[0058] In additional embodiments, if desired, the temperature(s) of the capacitor(s) of power converter 470 may also be monitored by one or more sensors and included in the first reduced-order model ROM-1 to monitor and evaluate the temperature(s) of the capacitor(s). In such a case, the capacitor input may be the input current and dissipation rate of the capacitor, where the output may be the hot spot temperature.

[0059] As previously described, controller 400 includes the self-learning capabilities of self-learning module 410. Thus, in additional embodiments of the present disclosure, control system 400, including at least one processor 412, is further configured to: compare the actual temperature measured by heat sink sensor 472 with the calculated temperature of the heat sink included in the first reduced-order model ROM-1; and if a difference has been determined to exist between the actual temperature value and the calculated temperature value, update the first reduced-order model ROM-1 with the actual temperature of the heat sink. The algorithm for correcting or updating the temperature value is ultimately responsible for updating the first reduced-order model ROM-1 when necessary through an intelligent controller, such as a neural network or a fuzzy controller. Thus, the accuracy of the electronic component is improved through the self-learning capabilities that can be used to reliably estimate the lifespan of the electronic component.

[0060] In additional exemplary embodiments, drive system 450 includes an additional reduced-order model. For example, drive system 450 may include a second reduced-order model ROM-2 of transformer 460, which is loaded and stored in memory 414. Control system 400, including at least one processor 412, is also configured by executable instructions to: receive the second reduced-order model (ROM-2) of transformer 460; receive the values of sensors 462, 464 associated with the transformer; and analyze the sensor values in combination with the second reduced-order model ROM-2 to determine one or more operating modes 416.

[0061] The second reduced-order model ROM-2 is obtained through a calculated hydrodynamic simulation, which includes a plurality of input parameters and a plurality of output parameters. Since transformers 460 can vary widely depending on how they are constructed, there may be a separate reduced-order model ROM-2 for each transformer design. The input quantities may be the power losses assumed to be evenly distributed across the phases of the transformer (typically three phases) and the airflow through each phase leg. The output quantities may be the temperatures at key locations on the secondary winding and at at least one location on the core of transformer 460. It should be noted that drive system 450 may include additional reduced-order models in addition to the first and second reduced-order models ROM-1, ROM-2.

[0062] In one embodiment, data from various sensors 452, 462, 464, 472, 474, 482, the outputs from the controller 400 and the prediction algorithms and reduced-order models ROM-1, ROM-2, such as the output operating mode 416, can be continuously collected and retrieved. For example, the drive system 450 includes a connection interface to an external storage medium 418. This connection can be, for example, an external network, such as the Internet, an intranet, or an Ethernet for a user (such as a customer or a supplier) of the drive system 450. The collected and retrieved data can be post-processed to obtain more information, thereby improving the performance of the driver and the system, running learning algorithms, and predicting long-term effects.

[0063] The drive system 450, particularly the control system 400, is further configured to include mobile application capabilities using the mobile application module 430 to allow a user, such as a customer of the drive system 450, to access the data resident on the drive system 450 and run mobile applications that generate customer-specific outputs. Such mobile applications are provided on a handheld device, such as a smart phone, a tablet computer, or a similar device, which allows the user to move around freely without being tethered by a cable. Using such a mobile application, the user / customer can modify or adjust the operation of the drive system 450, for example, to run the drive system 450 more efficiently. For example, the control system 400 can analyze various sensor values in view of the reduced-order models ROM-1, ROM-2 and can determine that the cooling component 480 can provide more cooling than actually needed based on the temperature in the evaluated power converter 470. The user / customer can reduce the cooling of the cooling component 480 through the mobile application and the mobile application module 430. Thus, certain features of the drive system 450 can be remotely enabled using the mobile application module 430.

[0064] In a further exemplary embodiment of the present disclosure, each power unit 312 of the power converter 470 (see Figure 1 , Figure 2 or Figure 3 ) includes local control circuits 476a......476n (only schematically shown) in communication with the control system 400. In addition, each power unit 312 can respectively include local sensors, where each local control circuit 476i......476n collects the sensor values of the local sensors and can locally evaluate the sensor values and / or can transmit the sensor values to the central control system 400 for evaluation. The local sensors can provide vibration values, arc detection values, temperature values, air flow values, etc. By providing local sensors and local control circuits 476a......476n, "distributed intelligence" is provided, and the operating state and mode of a single power unit 312 can be monitored and determined more accurately.

[0065] For example, each local control circuit 476a......476n includes at least one processor configured by executable instructions to calculate the life of the power electronic components of each power unit 312 based on vibration values, arc detection values, temperature values, and air flow values.

[0066] Vibration monitoring allows, for example, the central control unit 400 to determine, based on data provided by local vibration sensors, whether there is a mechanical condition that requires maintenance. Arc detection values provided by local arc sensors, such as those configured as optical sensors, can provide information about internal faults that may not be visible to the central control unit 400. The output of the local air flow sensors can be used to determine whether there is sufficient air flow for each power unit 312 and to predict the temperature of each local radiator. As previously described, local temperature sensors provide local temperature values that are used to calculate the CFDROM of the power converter 470. Using the environmental conditions of each power unit 312, such as temperature, air flow, power output, etc., the life of the power electronic components can be predicted.

[0067] Data received from various sensors, outputs from the drive control system 400 and from the power units 312, as well as outputs from the prediction algorithms and ROM-1, ROM-2, can be used by the drive system 450 to adjust for changing conditions, such as air filter blockage or coolant pipe blockage, hotter or colder ambient temperatures, or other feedback from the power units. As previously described, such an adaptive response can include changing the speed of the cooling fans and / or cooling pumps, and / or removing, i.e., bypassing, a power unit based on the operating conditions of a particular power unit.

[0068] Figure 6 Flowchart 600 of a method for controlling a variable frequency drive 450 in accordance with an exemplary embodiment of the present disclosure is illustrated.

[0069] Now referring to Figure 6 , a method 600 facilitating control functions is illustrated. While the method is described as a series of actions performed in sequence, it should be understood that the method can be unrestricted by the order of the sequence. For example, unless otherwise stated, some actions can occur in a different order than that described herein. Additionally, in some cases, one action may occur concurrently with another action. Further, in some instances, not all actions may be required to implement the method described herein.

[0070] The method can start at 602 and can include an action 604 of accessing the reduced-order models ROM-1, ROM-2 of the power converter 470, and an action 606 of receiving sensor values of the power converter 470 provided by the sensors 490. The method can further include an action 608 of analyzing the sensor values in combination with the reduced-order models ROM-1, ROM-2 to determine the operating mode 416 of the power converter 470. Additionally, the method can include an action 610 of outputting the operating mode 416. At 612, the method can end.

[0071] It should be understood that such a described method 600 can include additional actions and / or alternative actions corresponding to the previously described features regarding the drive system 450 (see Figure 4 and Figure 5 ).

[0072] For example, the method 600 can include an action of comparing the actual values measured by the sensors 490 with the calculated values included in the reduced-order models ROM-1, ROM-2, and can include an action of updating the reduced-order models ROM-1, ROM-2 with the actual values when a difference between the actual values and the calculated values is determined.

[0073] Furthermore, the method 600 can further include an action of obtaining the reduced-order models ROM-1, ROM-2 of the power converter 470 through a calculated hydrodynamic simulation including a plurality of input parameters and a plurality of output parameters, where the plurality of output parameters include the calculated junction temperatures of individual transistors of the switching devices 315a-d of the power unit 312.

[0074] In another example, the method 600 can include an action of accessing a second reduced-order model ROM-2 of the transformer 460, an action of receiving sensor values of the transformer 460 provided by the sensors 490, an action of analyzing the sensor values in combination with the second reduced-order model ROM-2 to determine the operating mode 416 of the transformer 460, and an action of outputting the operating mode 416.

[0075] The method can further include an action of communicating with the local control circuits 476 of the power unit 312, each local control circuit 476 collecting sensor values of the local sensors of the power unit 312, and an action of analyzing 630 the sensor values in combination with the first reduced-order model ROM-1 to determine the operating mode 416 of the power converter 470.

[0076] It should be understood that the actions associated with the methods, features, and functions described above (other than any described manual actions) can be performed by one or more data processing systems, such as a central control system 400, through the operation of at least one processor 412. As used herein, a processor corresponds to any electronic device configured to process data through hardware circuits, software, and / or firmware. For example, the processors described herein can correspond to one or more (or a combination) of a microprocessor, a CPU, or any other integrated circuit (IC) or other type of circuit capable of processing data in a data processing system. As discussed previously, the described / claimed processor 412 configured to perform a specific described / claimed process or function can correspond to a CPU that executes computer / processor-executable instructions stored in a memory in the form of software and / or firmware to perform such a described / claimed process or function. However, it should also be understood that such a processor can correspond to an IC hardwired to a processing circuit (e.g., an FPGA or ASIC integrated circuit) to perform such a described / claimed process or function.

[0077] Furthermore, it should be understood that the described or claimed processor configured to perform a specific described / claimed process or function can correspond to a combination of the processor 412 and executable instructions (e.g., software / firmware applications) loaded / installed into a memory (volatile and / or non-volatile), which are currently being executed and / or are executable by the processor 412 to cause the processor 412 to perform the described / claimed process or function. Thus, a processor that has its power turned off or is executing other software but has the described software can also correspond to the described / claimed processor configured to perform the specific processes and functions described herein, the described software being installed on an operatively connected data memory (such as on a hard disk or SSD) in a manner set to be executed by the processor (when initiated by a user, hardware, and / or other software).

[0078] In addition, it should be understood that a reference to "a processor" can include multiple physical processors or cores configured to perform the functions described herein. Furthermore, it should be understood that a data processing system can also be referred to as a controller that operatively controls at least one operation.

[0079] Equally importantly, it should be noted that although the present disclosure includes a description in the context of a full - fledged system and / or a series of operations, those skilled in the art will understand that at least a portion of the mechanisms and / or the described operations of the present disclosure can be distributed in the form of computer / processor - executable instructions (e.g., software and / or firmware instructions) that are included in a data storage, which corresponds to a non - transitory machine - available, computer - available, or computer - readable medium in any of various forms. The computer / processor - executable instructions can include routines, sub - routines, programs, applications, modules, libraries, and / or the like. In addition, it should be understood that the computer / processor - executable instructions can correspond to and / or can be generated from source code, bytecode, runtime code, machine code, assembly language, Java, JavaScript, Python, Julia, C, C#, C++, or any other form of code that can be programmed / configured to cause at least one processor to perform the actions and features described herein. Further still, the results of the described / claimed processes or functions can be stored in a computer - readable medium, displayed on a display device, etc.

Claims

1. A variable frequency drive system (450), the variable frequency drive system comprising: A power converter (310, 470), the power converter including a plurality of power units (312) that supply power to one or more output phases (A, B, C), each power unit (312) including a plurality of switching devices (315a-d) that include semiconductor switches; A plurality of sensors (490), the sensors being used to monitor values of the power converter (310, 470); And A control system (400), the control system being in communication with the power converter (310, 470) and controlling the operation of the plurality of power units (312), the control system (400) including at least one processor (412), the at least one processor being configured by executable instructions to: Access a first reduced-order model (ROM-1) of the power converter (310, 470); Receive values provided by the plurality of sensors (490); Analyze the values in combination with the first reduced-order model (ROM-1) to determine one or more operating modes (416); And Output one or more determined operating modes (416) of the power converter (310, 470).

2. The variable frequency drive system (450) according to claim 1, wherein, The plurality of sensors (490) provide internal temperature values of the semiconductor switches of the power converter (470).

3. The variable frequency drive system (450) according to claim 1, wherein, The plurality of sensors (490) include a radiator sensor (472) for measuring the internal temperature of the radiator and an air flow sensor (474) for measuring the internal air flow of the power converter (470).

4. The variable frequency drive system (450) according to any one of claims 1 to 3, wherein, The plurality of sensors (490) provide temperature values of the capacitors of the power converter (470).

5. The variable frequency drive system (450) according to any one of claims 1 to 3, wherein, The first reduced-order model (ROM-1) is obtained by a computed hydrodynamic simulation, the computed hydrodynamic simulation including a plurality of input parameters and a plurality of output parameters, wherein the plurality of output parameters include the computed junction temperatures of individual transistors of the switching devices (315a-d) of the power units (312) and the computed temperature of the radiator of the power converter (470).

6. The variable frequency drive system (450) according to claim 5, wherein, The control system (400) including at least one processor (412) is further configured by executable instructions to: Compare the actual temperature measured by the radiator sensor (472) with the computed temperature of the radiator included in the first reduced-order model (ROM-1); And If it is determined that there is a difference between the actual temperature value and the computed temperature value, update the first reduced-order model (ROM-1) with the actual temperature of the radiator.

7. The variable frequency drive system (450) according to any one of claims 1 to 3 further includes a cooling component (480) for cooling the power converter (470), wherein, The plurality of sensors (490) further include a sensor (482) for monitoring the coolant flow rate and coolant pressure drop between the coolant outlet and the coolant inlet.

8. The variable frequency drive system (450) according to any one of claims 1 to 3, wherein, The plurality of sensors (490) further include a vibration sensor (452), the vibration sensor being used to monitor the vibration of components of the drive system (450) to determine a mechanical condition that requires maintenance.

9. The variable frequency drive system (450) according to any one of claims 1 to 3, the variable frequency drive system further comprising a transformer (460) operably coupled to the power converter (470) and providing an isolation voltage to a plurality of power units (312), Among them, A control system (400) including at least one processor (412) is further configured by executable instructions to: Access a second reduced-order model (ROM-2) of the transformer (460); And Analyze values in combination with the second reduced-order model (ROM-2) to determine one or more operating modes (416).

10. The variable frequency drive system (450) according to claim 9, wherein, The second reduced-order model (ROM-2) is obtained by a computed hydrodynamic simulation, the computed hydrodynamic simulation including a plurality of input parameters and a plurality of output parameters, wherein the plurality of output parameters include computed temperatures at predetermined locations on the core and secondary winding of the transformer (460).

11. The variable frequency drive system (450) according to any one of claims 1 to 3, wherein, One or more operating modes (4161) include states of the drive system, the drive system including hot spots, and wherein one or more operating modes (416) include modified operating modes of the cooling component (480) and / or modified operating modes of the power converter (470), wherein the output voltage of the power converter (470) is increased or decreased.

12. The variable frequency drive system (450) according to any one of claims 1 to 3, wherein, Each power unit (312) includes a local sensor and a local control circuit in communication with the control system (400), wherein each local control circuit collects sensor values of the local sensor and transmits the sensor values to the control system (400) for evaluation.

13. The variable frequency drive system (450) according to claim 12, wherein, The local sensor provides vibration values, arc detection values, temperature values, and air flow values.

14. The variable frequency drive system (450) according to claim 13, wherein, Each local control circuit includes at least one processor configured by executable instructions to calculate the life of the power electronic components of each power unit (312) based on vibration values, arc detection values, temperature values, and air flow values.

15. The variable frequency drive system (450) according to any one of claims 1 to 3, wherein, The control system (450) further includes a preventive maintenance module (420) and a mobile application module (430), the preventive maintenance module and the mobile application module allowing additional applications to be added or loaded to the control system (450), the additional applications providing post-processing of drive data independent of the control process executed by the control system (450).

16. The variable frequency drive system (450) according to claim 15, wherein, The preventive maintenance module (420) and the mobile application module (430) are configured such that additional applications or control features can be added, loaded, or enabled remotely.

17. A method (600) for controlling a variable frequency drive (450), the method comprising, by operating at least one processor (412): Accessing (610) a first reduced-order model (ROM-1) of the power converter (310, 470); Receiving (620) sensor values of the power converter (310, 470) provided by a sensor (490); Analyzing (630) the sensor values in combination with the first reduced-order model (ROM-1) to determine an operating mode (416) of the power converter (310, 470); and Outputting (640) the operating mode (416).

18. The method (600) according to claim 17, the method further comprising: comparing an actual value measured by a sensor (490) with a calculated value included in a reduced-order model (ROM-1, ROM-2); and when it is determined that there is a difference between the actual value and the calculated value, updating the reduced-order model (ROM-1, ROM-2) with the actual value.

19. The method according to claim 17, the method further comprising: obtaining a reduced-order model (ROM-1, ROM-2) of a power converter (310, 470) through a calculated hydrodynamic simulation including a plurality of input parameters and a plurality of output parameters, wherein the plurality of output parameters includes the calculated junction temperature of a single transistor of a switching device (315a-d) of a power unit (312).

20. The method according to any one of claims 17 to 19, the method further comprising: accessing (610) a second reduced-order model (ROM-2) of a transformer (460); and receiving (620) a sensor value of the transformer (460) provided by a sensor (490); analyzing (630) the sensor value in combination with the second reduced-order model (ROM-2) to determine an operating mode (416) of the transformer (460); and outputting (640) the operating mode (416).

21. The method (600) according to claim 18, the method further comprising: communicating with a local control circuit (476) of a power unit (312), each local control circuit (476) collecting sensor values of local sensors of the power unit (312), and analyzing (630) the sensor values in combination with a first reduced-order model (ROM-1) to determine an operating mode (416) of the power converter (310, 470).

22. A non-transitory computer-readable medium having processor-executable instructions encoded thereon, which when executed by at least one processor (412), cause the at least one processor (412) to perform the method for controlling a variable frequency drive (450) according to any one of claims 17 to 21 above.

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