Health monitor for electric motors

Abstract

A health monitoring circuit for an electric motor includes a plurality of sensors, a rectifier, a storage device, and a microprocessor. The plurality of sensors include a current transformer configured to be electromagnetically coupled to an electrical conductor that feeds a stator winding of the electric motor. The rectifier is coupled to the current transformer and configured to convert an AC signal generated by the current transformer into a DC signal to power the health monitoring circuit. The microprocessor is coupled to the storage device and the plurality of sensors. The microprocessor is configured to periodically collect stator current measurements from the current transformer and write the stator current measurements to the storage device.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. non-provisional patent application No. 16 / 055,846, filed on August 6, 2018, the entire disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] The field of the invention relates generally to a health monitor for an electric machine, and more particularly to a health monitoring circuit that measures the stator current of a motor or generator and harvests / harvests energy from the electromagnetic field generated by the stator current. Background Art

[0004] At least some motors include accelerometers and temperature sensors to periodically measure, for example, vibration and ambient temperature around the motor. Such measurements are useful for determining the amount of wear on the motor over time and the overall health of the motor. Some motors include piezoelectric accelerometers that measure vibration. Some motors include resistive temperature sensors (RTDs) embedded in the motor circuit to monitor temperature. Such sensors can be integrated into the motor and its housing, and are typically powered by a battery or independently of the motor itself. Some motors (e.g., electronically commutated motors) include current sensors integrated into a controller (e.g., a motor controller) to measure stator current to properly operate the motor. Other motors (e.g., induction motors) do not require measurement of stator current to operate. The data collected by the sensor can be used and stored locally on the motor, more specifically on a storage device integrated in the housing. Alternatively, the data collected by the sensor can be transmitted to a remote storage device, such as a mass storage device or a cloud server, using a wired or wireless communication device. However, it is desirable to improve the fidelity of motor health data without the need for complex modification costs. Summary of the invention

[0005] In one aspect, a health monitoring circuit for an electric motor includes a plurality of sensors, a rectifier, a storage device, and a microprocessor. The plurality of sensors include a current transformer configured to be electromagnetically coupled to an electrical conductor that feeds a stator winding of the electric motor. The rectifier is coupled to the current transformer and configured to convert an alternating current (AC) signal generated by the current transformer into a direct current (DC) signal to power the health monitoring circuit. The microprocessor is coupled to the storage device and the plurality of sensors. The microprocessor is configured to periodically collect stator current measurements from the current transformer and write the stator current measurements to the storage device.

[0006] On the other hand, the motor includes a rotor, a stator winding, and a health monitoring circuit. The rotor is configured to rotate relative to the stator winding. The stator winding is configured to be electromagnetically coupled to the rotor in response to a stator current conducted by the stator winding. The health monitoring circuit includes a plurality of sensors, a rectifier, a storage device, and a microprocessor. The plurality of sensors include a current transformer configured to be electromagnetically coupled to an electrical conductor that feeds the stator winding. The rectifier is coupled to the current transformer and is configured to convert an AC signal generated by the current transformer into a DC signal to power the health monitoring circuit. The microprocessor is coupled to the storage device and the plurality of sensors. The microprocessor is configured to periodically collect stator current measurements from the current transformer and write the stator current measurements to the storage device.

[0007] In yet another aspect, a method for monitoring the health of an electric machine includes conducting a stator current through a stator winding of the electric machine. The method includes electromagnetically coupling a current transformer to the stator winding. The method includes rectifying a current induced in a secondary winding of the current transformer into a DC signal and providing the DC signal to a component of a health monitoring circuit. The method includes periodically collecting, by a microprocessor, stator current measurements from the current transformer based on the current induced in the secondary winding. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a block diagram of an example motor with a health monitoring circuit;

[0009] Figure 2 is used for Figure 1 a schematic diagram of a health monitoring circuit for the motor shown; and

[0010] Figure 3 is a flow chart of an example method for monitoring motor health. DETAILED DESCRIPTION

[0011] Embodiments of the health monitoring circuit described herein provide improved fidelity of motor health data without the expense of complex modifications. More specifically, the health monitoring circuit described herein includes multiple sensors for detecting operating parameters and environmental conditions of the motor, including current transformers. For example, the current transformer enables stator current measurement and energy harvesting to power the health monitoring circuit itself. The combination of operating parameters and environmental conditions (e.g., ambient temperature, ambient humidity, atmospheric pressure, and acceleration) with stator current measurements enables improved analysis and monitoring of electrical and mechanical degradation or "wear" experienced by the motor, and also enables inference of various aspects of the health of the mechanical load coupled to the motor and driven by the motor (for electric motors), or various aspects of the health of the machine coupled to the rotor and rotating the rotor (for generators). The current induced by the stator current in the current transformer can be rectified and applied directly to components of the health monitoring circuit, or to an energy storage device that powers at least the health monitoring circuit. The health monitoring circuit described herein may also include voltage regulation and distribution circuits for generating power and powering the components of the health monitoring circuit. The health monitoring circuits described herein may also include current sensing circuits that are capable of periodically collecting and storing stator current measurements (as well as other measurements of operating parameters and environmental conditions) controlled by a microprocessor or other suitable processing device. The health monitoring circuits described herein may also include a communication interface for transmitting the measurements to a remote device, such as a system controller or other suitable computing system. Such a communication interface may include one or more wired communication channels or wireless communication channels.

[0012] Figure 1 is a block diagram of an example electric machine 100 with a health monitoring circuit 102. The electric machine 100 is illustrated as an electric motor including a rotor 104 and a stator 106. The rotor 104 is configured to be coupled to a mechanical load 108. The mechanical load 108 may include, for example, a rotatable load such as a fan, wheel, blower, impeller, compressor, flywheel, transmission, or crankshaft, etc. The mechanical load 108 may also include a linear load such as a solenoid or a linear actuator, etc. In an alternative embodiment, the rotor 104 is configured to be coupled to a machine that rotates the rotor 104 to operate the electric machine 100 as a generator. Such a machine may include an internal combustion engine, a gas turbine, a wind turbine, a steam turbine, or any other suitable machine for rotating the rotor 104. Again referring to Figure 1 In an embodiment in which the electric machine 100 is an electric motor, the stator 106 typically includes one or more stator windings (not shown) that, when energized and conducting stator current, electromagnetically couple to the rotor 104 and cause the rotor 104 to rotate relative to the stator 106 about a longitudinal axis.

[0013] The motor 100 is provided with AC power by an AC power source 110. The AC power source 110 may include, for example, a power grid, a diesel generator, a wind turbine generator, or a turbine generator, or any other suitable AC power source. Alternatively, the AC power source 110 may alternatively include one or more DC power sources, the output of which is converted or "inverted" to AC power before being provided to the motor 100. In some embodiments, the AC power from the AC power source 110 can be applied directly to the stator 106. In alternative embodiments, the motor 100 can be supplied with AC or DC power, which is appropriately converted into AC and / or DC by the motor 100 itself. To this end, some embodiments of the motor 100 include a motor controller 112. In other embodiments, the motor controller 112 can be omitted.

[0014] The motor controller 112 typically includes one or more processors, one or more storage devices, and a drive circuit (none of which is shown). Typically, the drive circuit supplies power to the stator 106 of the motor 100 based on control signals received from the one or more processors. The drive circuit may include, for example, various power electronics for regulating the line frequency AC power provided to the stator winding of the motor 100 with a desired current (i.e., phase and amplitude and frequency). Such power electronics may include, for example, but are not limited to, one or more rectifier stages, power factor correction circuits (PFC), filters, transient protection circuits, electromotive force protection circuits, inverters, or power semiconductors. In certain embodiments, the motor controller 112 may include a communication interface (not shown). The communication interface may include one or more wired or wireless hardware interfaces, such as a universal serial bus (USB), RS232 or other serial bus, CAN bus, Ethernet, near field communication (NFC), WiFi, Bluetooth, or any other suitable digital or analog interface for establishing one or more communication channels between the motor controller 112 and the remote device 114. The remote device 114 may include a system controller, a smart phone, a personal computer, a mass storage system, a cloud server, or any other suitable computing system. The communication interface may include, for example, a wired communication channel 116 to the remote device 114 or an antenna 118 for establishing a wireless communication channel with the remote device 114. The communication interface also includes a software or firmware interface for receiving one or more control parameters and writing them to, for example, a memory. In some embodiments, the communication interface includes, for example, a software application programming interface for providing one or more parameters for operating the motor 100.

[0015] In an alternative embodiment, the communication interface may be provided / implemented independently of the motor controller 112 such that it serves both the motor controller 112 and the health monitoring circuit 102. In another alternative embodiment, the communication interface may be integrated into the health monitoring circuit 102.

[0016] The motor 100 may include a housing within which the rotor 104 and the stator 106 are located. The motor 100 may also include an electrical housing or "conduit box" within which the various electrical components of the motor 100, such as the motor controller 112 and the health monitoring circuit 102, may be located.

[0017] Figure 2 is used for Figure 1 A schematic diagram of a health monitoring circuit 102 for an electric machine 100 is shown. Figure 2 It is further shown that the motor 100 is supplied with AC power from the AC power source 110 so that the motor 100, more specifically its rotor, operates the mechanical load 108. The health monitoring circuit 102 includes an energy storage device 202, a rectifier 204, a voltage regulator 206, a communication interface 208, a plurality of sensors 210, a microprocessor 212, a current sensing circuit 214, a storage device 216, and a current transformer 218. In some embodiments, the storage device 216 is provided inside the microprocessor 212, or is provided as a component of the microprocessor 212. In other embodiments, the storage device 216 is a component independent of the microprocessor 212.

[0018] The energy storage device 202 is configured to provide power to the health monitoring circuit 102. More specifically, to the extent that the rectifier 204, the voltage regulator 206, the communication interface 208, the sensor 210, the microprocessor 212, the current sensing circuit 214, the storage device 216, and the current transformer 218 require power to operate, such power is provided by the energy storage device 202. The energy storage device 202 may include, for example, one or more capacitors. In alternative embodiments, the energy storage device may include one or more batteries. In at least some embodiments, the current transformer 218 and the energy storage device 202 do not provide the precise and stable voltage required by many components of the health monitoring circuit 102. Therefore, the energy storage device 202 provides, for example, a DC voltage to the voltage regulator 206. In certain embodiments, the energy storage device 202 is omitted, and power is supplied directly from the current transformer 218, the rectifier 204, and the voltage regulator 206 to the health monitoring circuit 102. The voltage regulator 206 generates a stable DC voltage that can be used by the components of the health monitoring circuit 102. For example, in some embodiments, the voltage regulator 206 generates a regulated 3.3 volt DC supply. Alternatively, the voltage regulator 206 can generate a regulated 5 volt DC supply or any other suitable regulated voltage to operate the health monitoring circuit 102. The voltage regulator 206 provides a desired DC voltage on a DC bus 220 or "bus" that delivers the desired DC voltage to the various components of the health monitoring circuit 102.

[0019] The current transformer 218 is configured to be electromagnetically coupled to a stator winding 222 of the electric machine 100, which may include one or more stator windings. Figure 2 As shown, the current transformer 218 is configured to electromagnetically couple to an electrical conductor 224, bus or wire that provides or "feeds" the stator current to the stator winding 222 itself. The current conducted through the electrical conductor 224 is generally considered to be the stator current conducted through the stator winding 222 itself. The current transformer 218 generally includes a primary winding or "coil" and a secondary winding 226. For the purpose of current measurement, the conductor (i.e., the electrical conductor 224) - the current passing therethrough is measured - is considered to be the primary winding. In certain embodiments, when the current transformer 218 is "clamped" onto the electrical conductor 224 or "primary winding", the primary winding includes a single "turn". In an alternative embodiment, when an induction coil is used as the primary winding, the number of turns is simply calculated (as a ratio of the number of primary turns to the number of secondary turns) when using, measuring and interpreting / converting the current induced in the secondary winding 226.

[0020] The current transformer 218 is coupled to the energy storage device 202, for example, through the rectifier 204. When the stator current is conducted through the stator winding 222, an electromagnetic field is generated, which induces a current in the secondary winding 226, generating an AC signal, which is received by the rectifier 204 and converted or rectified into a DC signal for charging the energy storage device 202. In an alternative embodiment, the energy storage device 202 is omitted, and the DC signal generated by the rectifier 204 is directly provided to the components of the health monitoring circuit 202 or the voltage regulator 206. In addition to being able to extract energy from the electromagnetic field generated by the stator current, the induced AC signal is also measurable and represents a measurement of the stator current itself. The current sensing circuit 214 enables periodic polling or collection of stator current measurements from the current transformer 218. The current sensing circuit 214 includes, for example, amplifiers, switches, and other electronic components (not shown) to enable the collection of measurements. For example, in some embodiments, the current sensing circuit 214 includes a current sensing amplifier configured to detect a voltage in a current measurement circuit that is representative of the current induced in the secondary winding 226. The amplifier then generates and transmits an analog stator current measurement signal that is representative of the current induced in the secondary winding 226. In addition, the current sensing circuit 214 may include a switch coupled to the current transformer 218 and, when commutated, closes the current measurement circuit to enable collection of stator current measurements. The switch may be coupled to the current transformer 218 directly or indirectly. For example, the switch may be indirectly connected via one or more discrete electrical components (e.g., resistors, capacitors, inductors, etc.). The current measurement circuit may include, for example, a current sensing resistor across which the current sensing amplifier detects a voltage.

[0021] The current sensing circuit 214 is connected to the microprocessor 212. The microprocessor 212 includes one or more processing devices connected to a storage device 216. The storage device 216 stores, for example, computer executable instructions or program codes, and measurements collected from the current transformer 218 and other sensors 210. The microprocessor 212 is configured by accessing and executing computer executable instructions or program codes stored in the storage device 216. Alternatively, the microprocessor 212 can be configured by similarly accessing program codes or firmware stored in a read-only memory (ROM), a random access memory (RAM), or any other suitable program code storage medium. The microprocessor 212 is configured to control the switch by sending a control signal to the switch within the current sensing circuit 214 so that the switch is commutated, thereby enabling the collection of stator current measurements. In some embodiments, the microprocessor 212 is configured to generate and transmit a control signal so that the switch is commutated at a sampling frequency selected at least as the frequency of the stator current supplied to the stator winding, thereby enabling the collection of stator current measurements once per cycle of the AC power supplied to the stator winding. For example, in one embodiment, the AC signal provided to the stator windings may be a common standard frequency of 50 Hz or 60 Hz. In alternative embodiments, the sampling frequency at which the microprocessor 212 collects stator current measurements may be greater or less than once per AC cycle.

[0022] The microprocessor 212 is coupled to the sensor 210 and is configured to periodically collect measurements from the sensor 210. In some embodiments, the sensor 210 may include an ambient temperature sensor, an ambient humidity sensor, an atmospheric pressure sensor, or an acceleration sensor, such as a micro-electromechanical system three-axis accelerometer. In addition to the current transformer 218, the sensor 210 may also include one or more current sensors. The sensor 210 may include any other type of sensor or device for collecting analog or digital data from the motor 100. The sensor 210 is configured to monitor various operating parameters and environmental conditions of or around the motor 100. The sensor 210 may further enable monitoring of various operating parameters of the mechanical load 108, particularly when combined with stator current measurements collected from the current transformer 218. At least some of the sensors 210 may be mounted on the motor 100, or, for example, on the motor controller 112, and transmit the measurement data back to the microprocessor 212.

[0023] The microprocessor 212 is coupled to a storage device 216 and is configured to write measurements from the current transformer 218 and the sensor 210 to the storage device 216. In some embodiments, the storage device 216 is a separate component from the microprocessor 212. In alternative embodiments, the storage device 216 is implemented / configured as a component within the microprocessor 212. In some embodiments, the microprocessor 212 is also coupled to the communication interface 208. The communication interface 208 may include one or more wired or wireless hardware interfaces, such as a universal serial bus (USB), RS232 or other serial bus, CAN bus, Ethernet, near field communication (NFC), WiFi, Bluetooth, Xbee, Zigbee, DigiMesh (digital mesh), cellular, radio frequency, or a plurality of hardware interfaces for communicating between the health monitoring circuit 102 and, for example, a remote device 114 (e.g., Figure 1 In some embodiments, the communication channels 228 may be continuous or persistent communication channels, or alternatively, temporary or transient communication channels that are established when the remote device 114 is within range or available for connection with the communication interface 208. The communication interface 208 may include, for example, a wired connection 116 to the remote device 114 or a wireless connection for connecting to the remote device 114 (all within the range of the wireless device 114). Figure 1 2 (shown in FIG. 2 ) to establish a wireless communication channel with antenna 118. Communication interface 208 also includes a software or firmware interface for receiving one or more requests to read, for example, measurement data from storage device 216. In some embodiments, communication interface 208 may include, for example, a software application programming interface (API) for writing program code to storage device 216 or reading measurement data from storage device 216.

[0024] In certain embodiments, the health monitoring circuit 102 may also include a backup battery (not shown) that provides power to components of the health monitoring circuit 102 when the motor 100 is not powered or when any of the energy storage device 202, rectifier 204, voltage regulator 206, or current transformer 218 fails.

[0025] Figure 33 is a flow chart of an example method 300 for monitoring the health of an electric machine, such as an electric machine 100 connected to a mechanical load 108, such as an electric motor. In an alternative embodiment, the method 300 monitors the health of an electric machine. The method 300 includes supplying 310 a stator current to a stator winding 222 of the electric machine 100. The stator current conducted by the stator winding 222, more specifically through an electrical conductor 224 feeding the stator winding 222, electromagnetically couples 320 a current transformer 218 to the stator winding 222, more specifically to the electrical conductor 224 feeding the stator winding 222. The stator current induces a current in a secondary winding 226 of the current transformer 218. The induced current is used to charge 330 an energy storage device 202. The induced current, which is typically an AC signal, may be rectified into a DC signal, which is provided to the energy storage device 202. Energy storage device 202 then provides a DC signal to voltage regulator 206 , which regulates the desired DC voltage supplied to various components of health monitoring circuit 102 , including, for example, microprocessor 212 , sensor 210 , communication interface 208 , and storage device 216 .

[0026] Based on the current induced in the secondary winding 226, the microprocessor 212 periodically collects 340 stator current measurements from the current transformer 218. The microprocessor 212 also periodically collects measurements from the sensor 210 and writes the measurements from the sensor 210 and the current transformer 218 to the storage device 216. In some embodiments, the microprocessor 212 periodically collects 340 stator current measurements by sending a control signal to a switch in the current sensing circuit 214. The switch is switched to close a current measurement circuit in the current sensing circuit, which may include, for example, a current sensing resistor or other suitable current sensing device. The method 300 may further include detecting a voltage in the current measurement circuit, the voltage being representative of the current induced in the secondary winding 226. This detection may be performed by an amplifier, such as a current sense amplifier, which then transmits an analog stator current measurement signal to the microprocessor 212 , which analog stator current measurement signal represents the current induced in the secondary winding and further represents the stator current conducted through the electrical conductor 224 and the stator winding 222 .

[0027] In certain embodiments, microprocessor 212 periodically collects 340 stator current measurements by generating control signals to commutate switches within current sensing circuit 214 at a sampling frequency that is at least the frequency of the stator current supplied to stator winding 222 .

[0028] 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 effects may include at least one of the following: (a) enabling stator current measurement on a motor; (b) enabling modification of the motor to add stator current measurement using a current transformer that can be "clamped" onto a stator winding or an electrical conductor feeding the stator winding; (c) enabling measurement of additional operating parameters and environmental conditions, including ambient temperature, acceleration, ambient humidity, and atmospheric pressure; (d) improving health monitoring by increasing the sampling frequency, increasing the measurable parameters, and combining the measured data with stator current measurements to improve data collection fidelity; (e) harvesting energy from a current transformer that enables stator current measurement to power a health monitoring circuit; (f) enabling periodic measurement of the stator current by storing energy extracted from the electromagnetic field generated by the current transformer from the stator current to further enable alternating cycles of charging and measuring; and (g) enabling the motor to operate as a sensor for monitoring operating parameters or environmental conditions of a mechanical load coupled to the motor.

[0029] In the foregoing description and the following claims, reference is made to a number of terms having the following meanings.

[0030] As used herein, an element or step recited in the singular and beginning with the word "a" or "an" should be understood not to exclude a plurality of elements or steps, unless such exclusion is explicitly stated. In addition, reference to "an exemplary embodiment" or "an embodiment" of the present disclosure is not intended to be interpreted as excluding the existence of additional embodiments that also include the described features.

[0031] “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.

[0032] Approximate language used throughout the specification and claims may be used to modify any quantitative representation that is permissible to vary without causing a change in the basic function to which it is associated. Therefore, values ​​modified by one or more terms such as "approximately," "approximately," and "substantially" are not limited to the exact values ​​specified. In at least some cases, approximate language may correspond to the precision of an instrument used to measure a value. Here, and throughout the specification and claims, range limitations may be combined or interchanged. Unless the context or language indicates otherwise, these ranges are identified and include all subranges contained therein.

[0033] 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, such as "processing device", "computing device" and "controller" are not limited to those integrated circuits referred to as computers in the art, but broadly refer to processors, processing devices, controllers, general-purpose central processing units (CPUs), graphics processing units (GPUs), microcontrollers, microcomputers, programmable logic controllers (PLCs), reduced instruction set computers (RISC) processors, field programmable gate arrays (FPGAs), digital signal processing devices (DSPs), application-specific integrated circuits (ASICs), and other programmable circuits or processing devices capable of performing the functions described herein, and these terms are used interchangeably herein. The above embodiments are merely examples and are therefore not intended to limit the definitions or meanings of the terms processor, processing device, and related terms in any way.

[0034] In the embodiments described herein, memory may include, but is not limited to, non-transitory computer-readable media, such as flash memory, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), and non-volatile random access memory (NVRAM). As used herein, the term "non-transitory computer-readable medium" is intended to represent any tangible computer-readable medium, including but not limited to non-transitory computer storage devices, including but not limited to volatile and non-volatile media, and removable and non-removable media, such as firmware, physical and virtual memory, CD-ROM, DVD, and any other digital source, such as a network or the Internet, and digital means to be developed, with the only exception of temporary propagation signals. Alternatively, a floppy disk, a compact disk read-only memory (CD-ROM), a magneto-optical disk (MOD), a digital versatile disk (DVD), or any other computer-based device implemented in any method or technology may be used for short-term and long-term storage of information, such as computer-readable instructions, data structures, program modules and submodules, or other data. Thus, the methods described herein may be encoded as executable instructions, such as "software" and "firmware," contained in a non-transitory computer-readable medium. Furthermore, as used herein, the terms "software" and "firmware" are interchangeable and include any computer program stored in a memory and executed by a personal computer, workstation, client, and server. When executed by a processor, such instructions cause the processor to perform at least a portion of the methods described herein.

[0035] Furthermore, in the embodiments described herein, the additional input channels may be, but are not limited to, computer peripherals associated with an operator interface, such as a mouse and keyboard. Alternatively, other computer peripherals may also be used, including, for example, but not limited to, scanners. Furthermore, in exemplary embodiments, the additional output channels may include, but are not limited to, an operator interface monitor.

[0036] 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 or separately from other components and / or steps described herein.

[0037] Although specific features of various embodiments of the present disclosure may be shown in some drawings and not in other drawings, this is only for convenience. According to the principles of the present disclosure, any feature of the drawings may be referenced and / or claimed in combination with any feature of any other drawings.

[0038] This written description uses examples to provide details about 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 device or system and performing any combined method. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. These other examples are intended to fall 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 that do not differ substantially from the literal language of the claims.

Claims

1. A health monitoring circuit for a motor, the health monitoring circuit comprising: a plurality of sensors, the plurality of sensors including a current transformer configured to be electromagnetically coupled to an electrical conductor feeding a stator winding of the electric machine; wherein, The current transformer is capable of measuring the stator current conducted through the stator winding; a rectifier coupled to the current transformer and configured to convert an alternating current (AC) signal generated by the current transformer into a direct current (DC) signal to power the health monitoring circuit; Storage devices; and a microprocessor coupled to the memory device and the plurality of sensors, the microprocessor configured to collect stator current measurements at least once per cycle of the AC signal supplied to the stator windings before switching to powering the health monitoring circuit by controlling alternation between a first period of powering the health monitoring circuit and a second period of receiving stator current measurements at a sampling frequency that is at least the frequency of the AC signal conducted by the stator windings; periodically receiving stator current measurements from the current transformer, and The periodically received stator current measurements are written to the storage device.

2. The health monitoring circuit according to claim 1, wherein: The microprocessor is also configured to periodically receive measurements from the plurality of sensors and write the measurements to the memory device.

3. The health monitoring circuit of claim 1 , further comprising a current sensing circuit, the current sensing circuit comprising an amplifier configured to generate an analog stator current measurement signal representative of the current induced in the secondary winding of the current transformer.

4. The health monitoring circuit of claim 1 further comprising a current sensing circuit comprising a switch coupled to the current transformer and the microprocessor, the microprocessor being configured to control the switch so as to enable periodic receipt of stator current measurements from the current transformer.

5. The health monitoring circuit according to claim 4, wherein: The microprocessor is further configured to control the switches so that the stator current measurements are collected at the sampling frequency which is at least the frequency of the AC signal conducted by the stator windings.

6. The health monitoring circuit according to claim 1 further includes an energy storage device coupled to the rectifier, wherein the energy storage device is configured to be charged in response to the DC signal provided by the rectifier and further power the health monitoring circuit.

7. The health monitoring circuit according to claim 1 further includes a voltage regulator coupled to the rectifier, wherein the voltage regulator is configured to adjust the DC signal provided by the rectifier to a desired DC voltage, which is to be supplied to at least the microprocessor and the storage device.

8. A motor comprising: Rotor; a stator winding relative to which the rotor rotates, the stator winding being configured to electromagnetically couple to the rotor in response to a stator current conducted by the stator winding; and A health monitoring circuit, the health monitoring circuit comprising: a plurality of sensors, the plurality of sensors including a current transformer configured to be electromagnetically coupled to an electrical conductor feeding the stator winding; wherein the current transformer is capable of measuring the stator current; a rectifier coupled to the current transformer and configured to convert an alternating current (AC) signal generated by the current transformer into a direct current (DC) signal to power the health monitoring circuit; storage devices; and a microprocessor coupled to the memory device and the plurality of sensors, the microprocessor configured to collect stator current measurements at least once per cycle of the AC signal supplied to the stator windings before switching to powering the health monitoring circuit by controlling alternation between a first period of powering the health monitoring circuit and a second period of receiving stator current measurements at a sampling frequency that is at least the frequency of the AC signal conducted by the stator windings; periodically receiving stator current measurements from the current transformer, and The periodically received stator current measurements are written to the storage device.

9. The electric machine of claim 8, further comprising a communication interface coupled to the microprocessor and configured to transmit at least the stator current measurement to a remote device using at least one of a wired communication channel and a wireless communication channel.

10. The electric machine of claim 8, further comprising an energy storage device coupled to the rectifier and configured to be charged in response to the DC signal provided by the rectifier and to further power the health monitoring circuit.

11. The electric machine according to claim 8, wherein: The plurality of sensors also includes an atmospheric pressure sensor.

12. The electric machine according to claim 8, wherein: The plurality of sensors also includes an ambient humidity sensor.

13. The electric machine of claim 8, further comprising a backup battery configured to power the health monitoring circuit.

14. The electric machine according to claim 8, further comprising: a housing in which the rotor and the stator are located; and An electrical housing is coupled to the housing, and the health monitoring circuit is located within the electrical housing.

15. A method for monitoring the health of a motor using a health monitoring circuit, the method comprising: Conducting stator current through the stator windings of the motor; A current transformer is electromagnetically coupled to an electrical conductor that feeds the stator winding; wherein, The current transformer is capable of measuring the stator current conducted through the stator winding; rectifying the current induced in the secondary winding of the current transformer into a direct current (DC) signal and providing the DC signal to the components of the health monitoring circuit; as well as Stator current measurements are periodically received from the current transformer by a microprocessor in the following manner: that is, by controlling the alternation between a first time period for powering the health monitoring circuit and a second time period for receiving the stator current measurements at a sampling frequency that is at least the frequency of the AC signal conducted by the stator windings, so as to collect the stator current measurements at least once per cycle of the AC signal supplied to the stator windings before switching to powering the health monitoring circuit.

16. The method of claim 15, further comprising periodically receiving, by the microprocessor, measurements from a plurality of sensors including the current transformer and writing the measurements to a storage device.

17. The method according to claim 15, wherein: Periodically receiving stator current measurements includes: The microprocessor sends a control signal to the switch; commutating the switch to close the current measurement circuit based on the control signal; detecting, by an amplifier, a voltage in the current measurement circuit, the voltage being representative of the current induced in the secondary winding of the current transformer; and An analog stator current measurement signal representative of the current induced in the secondary winding of the current transformer is sent to the microprocessor.

18. The method according to claim 17, wherein: Periodically receiving stator current measurements also includes generating a control signal by the microprocessor to commutate the switch at the sampling frequency.

19. The method of claim 15, further comprising charging an energy storage device using the DC signal, and powering the health monitoring circuit from the energy storage device.

20. The method according to claim 15, further comprising: providing a DC signal to a voltage regulator; and A desired DC voltage is regulated and supplied to at least a microprocessor.

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