Patent ID: 12224693

DETAILED DESCRIPTION

Embodiments of the drive system include a motor controller for an electric motor. The motor controller includes an inverter configured to supply current to stator windings of the electric motor, a plurality of sensors configured to generate a sensor signal in response to detecting a parameter, the sensor signal representing a measured parameter, and a processor coupled in communication with the inverter and with the plurality of sensors. The processor is configured to transmit a control signal to the inverter to operate the electric motor at a first frequency. The processor is further configured, while transmitting the control signal or while idling, to receive the sensor signal from the plurality of sensors. The processor is further configured to determine a first fault condition is present at the electric motor based on the measured parameter represented by the sensor signal. For example, the processor may detect a short circuit, an overload, an open phase, a line overcurrent, an unexpected power factor, a motor type mismatch (e.g., between configuration for a permanent split capacitor or a brushless DC motor) or other faults of the electric motor based on data received from the plurality of sensors. Accordingly, faults within the drive system can be more easily and accurately attributed to a specific part of the system, such as the electric motor, motor controller, or external components such as a relay or a run capacitor. This enables operators to more quickly repair the drive system, decreasing the amount of time the drive system and associated systems (e.g., an HVAC system in which the drive system is installed) are inoperable due to such faults.

In some embodiments, the drive system is capable of supplying current to the electric motor directly from a line power source. In such embodiments, the processor is further configured to cease transmitting the control signal to the inverter that causes the inverter to operate the electric motor, and to close a contactor to electrically couple the electric motor directly to a line power source to operate the electric motor at a second frequency. In such embodiments, the processor is further configured to determine a fault condition is present in the contactor. For example, the processor may detect a failure to open, a failure to close, an unenergized relay coil, or other faults of the contactor based on data received from the plurality of sensors. Further, a fault may be detected on the run capacitor by monitoring power factor, and a fault may be detected at idle when the contactor has failed, for example, by becoming welded shut.

In some embodiments, the fault conditions that may be detected by the drive system include one or more of an inverter short circuit, a ground fault, an overload, a shorted contactor, an open contactor, or a damaged run capacitor. Additionally, the drive system may detect other fault conditions based on sensor measured parameters of the drive system.

FIG.1is a schematic diagram of a drive system100. Drive system100includes an electric motor102, a motor controller104, a contactor106, and a run capacitor108. Drive system100further includes a plurality of sensors, including a line current sensor110, a contactor voltage sensor112, a back electromagnetic force (EMF) voltage sensor114, inverter phase current sensors116, and a contactor current sensor118.

Electric motor102includes a stator and a rotor configured to rotate in response to current applied to windings of the stator. In certain embodiments, the rotor is coupled to and configured to turn, for example, a compressor or a fan of an HVAC system. In some embodiments, electric motor102is an induction motor, such as a permanent split capacitor (PSC) motor that includes a main winding120and a start winding122. As described in further detail below, current may be supplied to main winding120and start winding122by motor controller104or directly from a line power source124. The current signal provided to start winding122generally has a phase offset from that provided to main winding120, for example, by 90 degrees, which ensures the rotor rotates in a particular, desired direction upon a startup of electric motor102.

Motor controller104is electrically coupled to a line power source124and to electric motor102and is configured to supply current to the stator windings of electric motor102. In certain embodiments, motor controller104is electrically coupled to main winding120and to start winding122and is configured to supply current phases to main winding120and start winding122. In some embodiments, motor controller is configured to vary the frequency of the current signal provided to the stator windings, such that electric motor102may be controlled to operate according to a desired speed, torque, power, or other parameter. For example, in certain embodiments, motor controller104is coupled to a system controller (not shown) such as a thermostat that may instruct motor controller to operate according to different operating modes corresponding to different operating frequencies of electric motor102.

Contactor106is electrically coupled between the line power source124and the phases of main winding120, and includes a switch corresponding to each phase. In certain embodiments, an electromagnetic interference (EMI) filter or other protective devices may be coupled between contactor106and line power source124. In certain embodiments, contactor106is a relay. Alternatively, contactor106may be a solid state switch or another type of switching device. Contactor106is coupled in communication with motor controller104and configured to open or close in response to a control signal generated by motor controller104. When closed, contactor106connects the stator windings of electric motor102directly to the line power source124, enabling electric motor102to be supplied current directly through the line power source124. For example, motor controller104may be configured to operate in two modes. In the first mode (sometimes referred to herein as the “inverter mode”), motor controller104opens contactor106and supplies current to the stator windings using the inverter. In the second mode (sometimes referred to herein as the “direct line mode”), motor controller104closes contactor106and deactivates the inverter, so main winding120is supplied current directly from the line power source124, and start winding122is supplied current via run capacitor108to ensure the desired phase difference is maintained between main winding120and start winding122. In some embodiments, motor controller104generally operates in the inverter mode, and when motor controller104is commanded to operate electric motor102at a frequency within a threshold of the frequency of the line input, motor controller104operates in the direct line mode. Accordingly, drive system100may operate with increase energy efficiency when electric motor102operates at the line frequency.

Line current sensor110, contactor voltage sensor112, back EMF voltage sensor114, inverter phase current sensor116, and contactor current sensor118are each coupled in communication with motor controller104and configured to detect or measure a specific parameter and generate a signal (sometimes referred to herein as a “sensor signal”) representing the detected or measured parameter (sometimes referred to herein as “sensor data”).

Line current sensor110is configured to detect a line current at each phase of the line current input and transmit the detected line current to motor controller104. In some embodiments, line current sensor110is at least partially integrated into motor controller104. By detecting the line current, motor controller104is able to determine whether the current of the line power source124is within an appropriate range, for example, with respect to amplitude and phase, for operation of electric motor102when motor controller104is operating in the direct line mode. A phase difference of the detected current with respect to the AC line input voltage would indicate inadequate power factor and possible issues with the stator windings or run capacitor108.

Contactor voltage sensor112is configured to detect a voltage across contactor106representative of AC line input voltage and transmit the detected voltage to motor controller104. In some embodiments, contactor voltage sensor112is at least partially integrated into motor controller104.

Back EMF voltage sensor114is configured to detect a voltage of contactor106and transmit the detected voltage to motor controller104. In some embodiments, back EMF voltage sensor114is at least partially integrated into motor controller104At idle, voltage should be zero indicative contactor is indeed open. When operating in the direct line mode, a voltage should be present indicating contactor is indeed closed. Accordingly, by detecting the back EMF voltage, motor controller104is able to determine whether electric motor102is operating appropriately. For example, if motor controller104is operating electric motor102in the inverter mode or direct line mode, yet no back EMF voltage is present, motor controller104may determine another component of drive system100is not functioning properly or a fault condition is present. In some embodiments, motor controller104is configured to utilize a combination of data from different sensors to determine a specific fault condition. For example, when motor controller104is operating electric motor102in the direct line mode, motor controller104may utilize back EMF voltage sensor114to determine contactor106correctly closed as commanded. If contactor106is closed but no current flows, one pole of contactor106or the stator windings may be at issue. If current flows but the phase, and hence power factor, is inadequate for proper operation, the stator windings or run capacitor108may have failed. In some embodiments, further diagnostics may be performed after motor controller104returns to the inverter mode.

Inverter phase current sensor116is configured to detect a current of each phase of main winding120of electric motor102and transmit the detected current to motor controller104. In some embodiments, inverter phase current sensor116is at least partially integrated into motor controller104. By detecting the inverter phase current, motor controller104may determine, for example, whether electric motor102is operating appropriately when motor controller104is operating electric motor102in the inverter mode. For example, motor controller104may detect a short circuit or an open phase at electric motor102.

In some embodiments, based on sensor data received from, for example, line current sensor110or inverter phase current sensor116, motor controller104is configured to compute a power factor of electric motor102. Motor controller104may use the computed power factor to determine, for example, that run capacitor108or start winding126has failed.

Contactor current sensor118is configured to detect a current at, for example, a relay coil126of contactor106, and transmit the detected current to motor controller104. In some embodiments, contactor current sensor118is at least partially integrated into motor controller104. By detecting the current at contactor106, motor controller104is able to determine whether contactor106is operating appropriately according to the control command from motor controller104. For example, motor controller104may determine that relay coil126is not energizing properly to open or close contactor106in response to the contactor signal generated by motor controller104.

FIG.2is a schematic diagram of motor controller104. Motor controller104includes an EMI filter202, an inrush limiter204, a rectifier206, an inverter208, low voltage supply210, a processor212, a contactor controller214, and a temperature sensor216, a memory218, and an input/output (I/O) module220.

EMI filter202, inrush limiter204, and rectifier206are electrically coupled in parallel with the line power source124. EMI filter202is configured to filter undesired electromagnetic interference, and inrush limiter204limits a current at the power input of motor controller104, to protect components motor controller104from damage. Rectifier206converts an alternating current (AC) line input signal provided by line power source124to a direct current (DC) signal that powers inverter208, low voltage supply210, and other components of motor controller104.

Inverter208is electrically coupled to rectifier206and electric motor102(shown inFIG.1) and is configured to convert the DC signal generated by rectifier206to an AC signal suitable for supplying current to the stator windings of electric motor102. Inverter208includes a plurality of switches configured to operate in response to a control signal generated by processor212. Accordingly, inverter208may be operated to provide current to electric motor102at a demanded frequency, or to cease providing current to electric motor102when contactor106is closed and electric motor102is driven directly by the line power source124.

Low voltage supply210is electrically coupled to rectifier206and is configured to supply power to low power components of motor controller104, such as processor212, contactor controller214, and temperature sensor216, memory218, and I/O module220. In some alternative embodiments, rather than being coupled to rectifier206, low voltage supply may include a battery or connection to an external power source.

Processor212is coupled in communication with inverter208and is configured to generate a control signal to control the switches of inverter208based on an operating command. For example, processor212may be in communication with an external system controller configured to transmit commands to processor212to operate electric motor102according to a desired speed, frequency, power, or other operating parameter.

Contactor controller214is coupled in communication with contactor106and processor212and is configured to control contactor106based on control signals received from processor212. For example, contactor controller214may generate a signal that causes contactor106to open or close, such as a current signal that activates a relay winding of contactor106.

Temperature sensor216is coupled in communication with processor212and is configured to detect an ambient temperature at one or more locations within drive system100or a temperature of one or more components within drive system100and transmit the detected temperature to processor212. In some embodiments, temperature sensor216is at least partially integrated into processor212. By detecting the temperature at one or more locations within drive system100, processor212is able to determine whether a fault condition is present, for example, if a measured ambient temperature falls outside a threshold range of expected temperatures. In some embodiments, temperature sensor216is configured to detect a temperature of components in addition to those of drive system100. For example, when drive system100is installed in an HVAC system, temperature sensor216may detect a temperature of air moving through the HVAC system, which may enable processor212to determine whether components of the HVAC system, such as the compressor, are functioning properly.

In some embodiments, motor controller104further includes memory218coupled in communication with processor212. In some such embodiments, memory218is configured to store instructions that may be read and executed by processor212. In some such embodiments, processor212is configured to store sensor data and diagnostic data such as fault records in memory218.

In some embodiments, motor controller104further includes I/O module220coupled in communications with processor212. In such embodiments, I/O module220is configured to communicate with devices external to drive system100, for example, using wired or wireless communication. For example, processor212may receive, via I/O module220, commands from a system controller such as a thermostat or an application executing on a device such as a smart phone, tablet computer, or personal computer. In some such embodiments, processor212is further configured to transmit data to the external devices, such alerts, sensor data, diagnostic data, or fault data indicating components of drive system100that have potentially failed.

FIG.3is a flowchart illustrating an exemplary method300for operating a drive system such as drive system100(shown inFIG.1). In some embodiments, method300is performed by motor controller104(shown inFIG.1), for example, using processor212(shown inFIG.2).

Motor controller,104, in a first mode opens302contactor106coupled in communication with the processor212. Contactor106is electrically coupled between line power source124and electric motor102.

Motor controller104, in the first mode, transmits304a control signal to inverter208coupled in communication with processor212. Inverter208is configured to supply current to stator windings of electric motor102. The control signal causes inverter208to operate electric motor102at a first frequency.

Motor controller104, in a second mode, ceases306to transmit the control signal to inverter208to operate electric motor102.

Motor controller104, in the second mode, closes308contactor106to electrically couple electric motor102directly to line power source128to operate electric motor102at a second frequency. In some such embodiments, electric motor102includes main winding120and start winding122electrically coupled to inverter208, and motor controller104couples start winding122to line power source124run capacitor108when contactor106is closed.

Motor controller104, receives310a sensor signal from a plurality of sensors coupled in communication with processor212. The plurality of sensors is configured to generate a sensor signal in response to detecting a parameter. In some embodiments, the plurality of sensors includes one of more of line current sensor110, contactor voltage sensor112, a back EMF voltage sensor114, inverter phase current sensors116, contactor current sensor118, or temperature sensor216.

Motor controller104determines312, when operating in the first mode, a first fault condition is present at electric motor102based on the measured parameter represented by the sensor signal. In some embodiments, motor controller104ceases transmitting the control signal to inverter208to operate electric motor102in response to determining the first fault condition is present at electric motor102. Similarly, in some embodiments, motor controller104determines, when operating in the second mode, a second fault condition is present at the contactor based on the sensor signal. In some embodiments, motor controller104determines a fault condition is present when motor controller104is idling, contactor106is open, and current is not supplied to electric motor102.

FIG.4is a schematic diagram of another exemplary drive system400. Drive system400includes electric motor102and motor controller104, which generally function as described with respect toFIG.1. In the embodiment depicted inFIG.4, electric motor102is a brushless DC (BLDC) motor that includes a plurality of BLDC stator windings402, to which motor controller104may supply pulses of current. Inverter phase current sensors116may detect a current at each BLDC stator winding402. In some embodiments, motor controller104is configured to determine a motor type of motor104. For example, if motor controller104is initially configured to supply current to a PSC motor, such as that depicted inFIG.1, and sensor data received form inverter phase current sensors116indicate that motor controller102is in fact coupled to a BLDC motor, such as that depicted inFIG.4, motor controller102may, for example, determine that a fault condition is present and deactivate. In some such embodiments, motor controller104is configured to detect the motor type of electric motor102and automatically adjust to supply current suitable for operation of the detected motor type. While stator windings402are depicted as independent inFIG.4, in some embodiments, stator windings402may be connected at some point, such as, for example, three-phase Y-connected windings.

The methods and systems described herein may be implemented using computer programming or engineering techniques including computer software, firmware, hardware or any combination or subset thereof, wherein the technical effect may include at least one of: (a) enabling a motor controller coupled to an electric motor to identify a fault condition in the electric motor using one or more sensors; (b) enabling a motor controller coupled to an electric motor and configured to drive the electric motor using an inverter in a first mode and directly via a line power source in a second mode by closing a contactor coupled between the electric motor and the line power input to identify a fault condition in the contactor using one or more sensors; (c) enabling a motor controller to identify a fault condition in a run capacitor of an electric motor by computing a power factor of the electric motor; and (d) decreasing time required to repair an inoperable drive system by identifying one or more components of the drive system that have failed.

In the foregoing specification and the claims that follow, a number of terms are referenced that have the following meanings.

As used herein, an element or step recited in the singular and preceded with the word “a” or “an” should be understood as not excluding plural elements or steps, unless such exclusion is explicitly recited. Furthermore, references to “example implementation” or “one implementation” of the present disclosure are not intended to be interpreted as excluding the existence of additional implementations that also incorporate the recited features.

“Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not.

Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about,” “approximately,” and “substantially,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here, and throughout the specification and claims, range limitations may be combined or interchanged. Such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise.

Disjunctive language such as the phrase “at least one of X, Y, or Z,” unless specifically stated otherwise, is generally understood within the context as used to state that an item, term, etc., may be either X, Y, or Z, or any combination thereof (e.g., X, Y, and/or Z). Thus, such disjunctive language is not generally intended to, and should not, imply that certain embodiments require at least one of X, at least one of Y, or at least one of Z to each be present. Additionally, conjunctive language such as the phrase “at least one of X, Y, and Z,” unless specifically stated otherwise, should also be understood to mean X, Y, Z, or any combination thereof, including “X, Y, and/or Z.”

Some embodiments involve the use of one or more electronic processing or computing devices. As used herein, the terms “processor” and “computer” and related terms, e.g., “processing device,” “computing device,” and “controller” are not limited to just those integrated circuits referred to in the art as a computer, but broadly refers to a processor, a processing device, a controller, a general purpose central processing unit (CPU), a graphics processing unit (GPU), a microcontroller, a microcomputer, a programmable logic controller (PLC), a reduced instruction set computer (RISC) processor, a field programmable gate array (FPGA), a digital signal processing (DSP) device, an application specific integrated circuit (ASIC), and other programmable circuits or processing devices capable of executing the functions described herein, and these terms are used interchangeably herein. The above embodiments are examples only, and thus are not intended to limit in any way the definition or meaning of the terms processor, processing device, and related terms.

In the embodiments described herein, memory may include, but is not limited to, a non-transitory computer-readable medium, such as flash memory, a random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), and non-volatile RAM (NVRAM). As used herein, the term “non-transitory computer-readable media” is intended to be representative of any tangible, computer-readable media, including, without limitation, non-transitory computer storage devices, including, without limitation, volatile and non-volatile media, and removable and non-removable media such as a firmware, physical and virtual storage, CD-ROMs, DVDs, and any other digital source such as a network or the Internet, as well as yet to be developed digital means, with the sole exception being a transitory, propagating signal. Alternatively, a floppy disk, a compact disc-read only memory (CD-ROM), a magneto-optical disk (MOD), a digital versatile disc (DVD), or any other computer-based device implemented in any method or technology for short-term and long-term storage of information, such as, computer-readable instructions, data structures, program modules and sub-modules, or other data may also be used. Therefore, the methods described herein may be encoded as executable instructions, e.g., “software” and “firmware,” embodied in a non-transitory computer-readable medium. Further, as used herein, the terms “software” and “firmware” are interchangeable, and include any computer program stored in memory for execution by personal computers, workstations, clients and servers. Such instructions, when executed by a processor, cause the processor to perform at least a portion of the methods described herein.

Also, in the embodiments described herein, additional input channels may be, but are not limited to, computer peripherals associated with an operator interface such as a mouse and a keyboard. Alternatively, other computer peripherals may also be used that may include, for example, but not be limited to, a scanner. Furthermore, in the exemplary embodiment, additional output channels may include, but not be limited to, an operator interface monitor.

The systems and methods described herein are not limited to the specific embodiments described herein, but rather, components of the systems and/or steps of the methods may be utilized independently and separately from other components and/or steps described herein.

Although specific features of various embodiments of the disclosure may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the disclosure, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.

This written description uses examples to provide details on the disclosure, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.