Method and system for detecting motor anomalies

Abstract

A method and system for detecting motor abnormalities. The method for detecting motor abnormalities includes generating, by a microcontroller, a quadrature current, calculating, using a low pass filter, an average current based on the quadrature current, generating, by the microcontroller, a ripple current, comparing the ripple current to the average current, determining whether the ripple current deviates from the average current by more than a predetermined threshold over a set period of time, and triggering an alarm signal when the ripple current deviates from the average current by more than the predetermined threshold over the set period of time.

Description

Technical Field

[0001] This invention relates to feedback control technology, and more particularly to a feedback control method and system for detecting motor malfunctions. Background Technology

[0002] Cooling fans are commonly used to cool electronic devices, thereby preventing them from overheating. For example, in data centers, fans play a crucial role in ensuring servers don't overheat. These cooling fans have diverse applications, including: installed inside tower and rack servers to cool internal components; chassis-mounted to cool blade servers and other electronic components within the chassis; rack-mounted to cool servers and other electronic components within racks; and as part of data center air conditioning systems for large-scale air handling. These cooling fans are essential for maintaining optimal computer system operation; ineffective cooling can lead to irreparable thermal damage to electronic equipment.

[0003] Prior art patents (e.g., U.S. Patent Nos. 6,400,113, 7,387,499, and 10,519,960) have disclosed techniques for monitoring, testing, and grouping fans with similar characteristics to identify cooling fans that are outside their operating range (e.g., revolutions per minute, RPM).

[0004] U.S. Patent No. 6,400,113, "APPARATUS AND METHOD FOR MONITORING FAN SPEEDSWITHIN A COMPUTING SYSTEM," describes an apparatus for monitoring fan speed within a computer system. This apparatus includes a tachometer that rotates with the fan, providing a speed signal with multiple pulses during each fan rotation. The speed signal is presented as a square wave signal, inverted between high and low levels as input to a signal generator. The square wave signal is input to multiple input ports of a microprocessor. These input ports are sampled sequentially, with a sampling frequency of at least two samples provided for each cycle of the fastest square wave signal. The transitions of each square wave signal within a predetermined time interval are detected and calculated. For each input port, the calculated number of transitions is compared to a stored acceptable value to determine whether the fan is operating within an acceptable speed range.

[0005] U.S. Patent No. 7,387,499, *SYSTEM AND METHOD FOR TESTING THE OPERATION OF A COOLING FAN*, describes a method for testing the operation of a cooling device in an information processing system. The method includes determining a first rotational speed of a fan used to operate the cooling device, wherein the first rotational speed is less than a maximum rotational speed of the fan. The method includes signaling the fan to rotate at the first rotational speed and detecting the current rotational speed of the fan. The method includes comparing the detected current fan speed with the first speed; if the detected current speed is substantially equal to or greater than the first speed, then the initialization process of the information processing system continues; if the detected current fan speed is less than the first speed, then further testing of the fan is performed.

[0006] U.S. Patent No. 10,519,960, "FAN FAILURE DETECTION AND REPORTING," relates to a system for detecting fan malfunctions and reporting groups of fans with similar characteristics. The system establishes one or more reference characteristics for a given fan group and identifies a tolerance metric for each reference characteristic. By monitoring and applying the tolerance metrics to the corresponding reference characteristics, the system identifies fans exhibiting performance characteristics exceeding those of the corresponding reference characteristics of their group as problematic fans and generates a notification message to confirm the identification of the problematic fan. The system monitors the fans during operation to confirm the fan characteristics used for grouping and identifying problematic fans. Therefore, the system can detect problematic fans even if it initially has limited or no knowledge of the fans.

[0007] However, the aforementioned existing technologies cannot detect signs of potential fan failure early enough when the fan is operating at a specified speed. To address this issue, the present invention proposes a method and apparatus capable of predicting potential fan failures in advance. Summary of the Invention

[0008] An embodiment provides a method for detecting motor malfunctions. The method includes generating an orthogonal current using a microcontroller, calculating an average current based on the orthogonal current using a low-pass filter, generating a ripple current using the microcontroller, comparing the ripple current with the average current, determining whether the ripple current deviates from the average current by more than a predetermined threshold within a set time period, and triggering an alarm signal when the ripple current deviates from the average current by more than the predetermined threshold within the set time period.

[0009] Another embodiment provides a motor control system. The motor control system includes: an inverter; a motor coupled to the inverter; a Clarke conversion module coupled to the inverter; a Parker conversion module coupled to the Clarke conversion module; a position and rate estimator coupled to the Parker conversion module; a low-pass filter coupled to the position and rate estimator; a first subtractor coupled to the position and rate estimator; a first proportional-integral controller coupled to the first subtractor; a second subtractor coupled to the first proportional-integral controller and the Parker conversion module; and a space vector pulse width modulation module coupled to the second proportional-integral controller, the position and rate estimator, and the inverter. The inverter generates a first phase current, a second phase current, and a third phase current based on an input voltage and a control signal. The motor drives a cooling fan based on the first phase current, the second phase current, and the third phase current. The Clarke conversion module generates a first stator current and a second stator current based on the first phase current and the second phase current through Clarke conversion. The Parker converter module generates DC current and quadrature current based on the rotor angle, the first stator current, and the second stator current via Parker conversion. The position and speed estimator generates a speed signal and the rotor angle based on the DC current and the quadrature current. The low-pass filter generates the average current of the motor based on the quadrature current. The first subtractor generates a first difference signal based on the control speed and the speed signal. The first proportional-integral controller generates a proportional-integral signal based on the first difference signal. The second subtractor generates a second difference signal based on the proportional-integral signal and the quadrature current. The second proportional-integral controller generates a duty cycle signal based on the second difference signal. The space vector pulse width modulation module generates the control signal for the inverter based on the duty cycle signal and the rotor angle. The low-pass filter generates a ripple current based on the average current and the quadrature current, and generates an alarm signal when the ripple current exceeds a predetermined deviation threshold. Attached Figure Description

[0010] Figure 1A , Figure 1B and Figure 1C This is a schematic diagram of a motor control system 1 according to an embodiment of the present invention.

[0011] Figure 2 Figure 1 shows a flowchart of a method for predicting potential cooling fan failures implemented in a cooling fan control system.

[0012] Figure 3 This is a schematic diagram of the orthogonal current generated by the microcontroller during motor operation.

[0013] Figure 4 This is a schematic diagram of the average current generated by the low-pass filter based on the orthogonal current.

[0014] Figure 5This is a schematic diagram of the difference signal obtained by subtracting the average current from the orthogonal current.

[0015] Figure 6 This is a schematic diagram of the ripple current obtained after subsequent filtering of the difference signal.

[0016] [Symbol Explanation]

[0017] 1: Motor control system

[0018] 10: Motor

[0019] 20: Inverter

[0020] 100: Microcontroller

[0021] 102: First resistor

[0022] 103: Second resistor

[0023] 110: Memory

[0024] 120: First Subtractor

[0025] 125: First proportional-integral controller

[0026] 130: Second Subtractor

[0027] 140: Clark Conversion Module

[0028] 145: Second Proportional-Integral Controller

[0029] 150: Parker Conversion Module

[0030] 155: Low-pass filter

[0031] 160: Position and Rate Estimator

[0032] 170: Space Vector Pulse Width Modulation Module

[0033] 200: Method

[0034] S210~S260: Steps

[0035] I A I B I C Phase current

[0036] I α I β Stator current

[0037] I d DC current

[0038] I qOrthogonal currents

[0039] I avg Average current

[0040] I rp Ripple current

[0041] I ω Proportional-integral signal

[0042] θ r Rotor angle

[0043] ω c Control rate

[0044] ω r Rate signal

[0045] V IN Input voltage

[0046] Ve: Circuit voltage

[0047] Du: Duty cycle signal Detailed Implementation

[0048] This disclosure provides a detailed description of various embodiments. While specific implementation details are disclosed herein to facilitate a thorough understanding of this disclosure, those skilled in the art will understand that the invention may be implemented in other ways without having to follow all such details. In some cases, detailed descriptions of well-known methods, procedures, components, and circuits have been omitted to avoid obscuring this disclosure. It should be understood that the technical features described with respect to a single drawing may be implemented individually or in combination with other features.

[0049] Fans are commonly used to cool electronic devices, thereby preventing them from overheating. For example, in data centers, fans play a crucial role in ensuring servers do not overheat. These fans may include, but are not limited to, fans installed inside tower servers and rack servers to cool their internal components, chassis-mounted fans to cool blade servers and other electronic components housed in the chassis, rack-mounted fans to cool servers and other electronic components within racks, and large fans used as part of data center air conditioning and air handling systems.

[0050] In data centers, fans used to cool servers can be removed and replaced with other fans that have different characteristics. For example, a chassis-mounted fan with a maximum speed of 6000 RPM can be removed and replaced with a fan with a maximum speed of 8000 RPM. This ability to replace fans allows data center administrators to selectively install various types of fans (e.g., fans from different manufacturers, different models from the same manufacturer, and fans with different characteristics) based on factors such as cost and performance. Some designs may choose to install high-performance fans regardless of cost, while others may choose to install fans that are sufficient to meet the performance requirements for cooling servers while reducing costs.

[0051] Monitoring the performance of installed fans is essential for detecting fan malfunctions, especially for fans operating abnormally, suboptimally, below satisfactory standards, or with potential failure risks. This monitoring requirement is even more critical when the fans themselves do not have built-in diagnostic control units. In such environments, servers, chassis, racks, or data centers can house various types of fans, making it difficult for monitoring devices to determine the expected characteristics of the installed fans or fan groups. Without data on expected characteristics as a benchmark, it is difficult to confirm whether the fans are operating as intended.

[0052] This paper discloses a motor control system and a method for detecting motor anomalies to solve problems in traditional fan cooling systems. The system groups fans with similar characteristics and establishes reference characteristics for each fan (such as the input power and average current of the electric motor), as well as tolerances or thresholds for each reference characteristic. When a fan operates beyond the tolerance or threshold of the reference characteristic, the system generates an alarm signal.

[0053] Figure 1A , Figure 1B and Figure 1C This is a schematic diagram of a motor control system 1 according to an embodiment of the present invention. The motor control system 1 includes a microcontroller (MCU) 100 and a memory 110 coupled to each other. Figure 1B As shown, both operate together to provide control signals to inverter 20. The control algorithm used here is field-oriented control (FOC). Microcontroller 100 can generate a control rate ω for controlling motor 10. c (In the form of a signal).

[0054] Inverter 20 supplies power to motor 10 to drive the cooling fan. Inverter 20 generates phase current I of motor 10. A I B I C Phase current I A and I BThe coordinates are transformed by the Clarke transform module 140. This transformation converts the three-axis (two-dimensional coordinate system) to a two-axis system, generating the stator current I. α and I β .

[0055] When phase current At that time, we can obtain:

[0056] Stator current I α It can be represented as:

[0057] Stator current I β It can be represented as:

[0058]

[0059] Stator current I α and I β This is represented in a biaxial orthogonal system of the α-β axis system. These currents are further converted by the Parker conversion module 150 into another biaxial system that rotates with the rotor flux.

[0060] Parker converter module 150 based on stator current I α and I β and rotor angle θ r Generate DC current I d and orthogonal current I q Current I d and I q It can be represented by a two-axis orthogonal rotating coordinate system called the dq axis. Therefore, the current I d and I q It can be generated by the following equation:

[0061]

[0062]

[0063] In the above equation, the magnetic flux component of the current is related to the DC current I. d Consistent, while the torque component is related to the orthogonal current I. q Consistent. The rotor angle can be provided by the position and rate estimator 160.

[0064] Subtractor 120 subtracts the first speed from the control speed ω c The difference is subtracted to produce a first difference, which is then input to the proportional-integral (PI) controller 125, which in turn generates a proportional-integral signal I.ω Another subtractor 130 will convert the proportional-integral signal I... ω and orthogonal current I q The subtraction is performed, and then the second proportional-integral controller 145 obtains the output of the subtractor 130 to generate the duty cycle signal Du. Subsequently, the space vector pulse width modulation (SVPWM) module 170 can adjust the duty cycle signal Du and the rotor angle θ according to the duty cycle signal Du and the rotor angle θ. r Generate control signals for controlling inverter 20.

[0065] Therefore, the motor 10 can operate within a feedback loop control and based on the control rate ω. c The average speed of motor 10 is adjusted. Furthermore, the low-pass filter (LPF) 155 can utilize the quadrature current I. q To generate the average current I of motor 10 avg .

[0066] In some embodiments, the average current I of the motor 10 can be generated based on the input current of the inverter 20. avg The method. For example... Figure 1C As shown, resistors 102 and 103 form a voltage divider, used to adjust the voltage based on the input voltage V. IN The circuit generates voltage Ve. The input voltage V. IN (Also related to input power) can be applied to motor 10 via inverter 20. Circuit voltage Ve can be used to power microcontroller 100 and / or memory 110, both of which require lower voltages than motor 10. Memory 110 can be used to store system coefficients, such as various system voltages, currents, and thresholds.

[0067] The above values ​​or signals (e.g., θ) r I d I q I avg V IN ω r (etc.) can be in the form of voltage, current, analog signals, and / or digital signals. These signals can be set to appropriate values, and those skilled in the art can easily observe and adjust them accordingly.

[0068] In some embodiments, the system coefficients can be derived using the following methods:

[0069] The torque equations for permanent magnet synchronous motors can be divided into electrical torque equation (1) and mechanical torque equation (2):

[0070] (1)

[0071] (2)

[0072] in:

[0073] P is the number of rotor pole pairs (a constant).

[0074] L d The d-axis inductance (constant)

[0075] L q The q-axis inductance (constant)

[0076] I d d-axis current

[0077] I q q-axis current

[0078] λ m For permanent magnet flux linkage (constant)

[0079] J is the fan's moment of inertia (a constant).

[0080] α is angular acceleration

[0081] T is the motor drive torque, considering surface-mounted rotors and

[0082] but , can be represented as

[0083] T Load The air resistance plus frictional resistance can be expressed as:

[0084] K A This is the drag coefficient (constant).

[0085] B is the coefficient of friction (constant).

[0086] ω is the angular velocity of the fan; if the velocity is constant, then...

[0087] When considering the fan operating at a constant speed:

[0088]

[0089] (3)

[0090] Will and Substitute into equation (3):

[0091]

[0092]

[0093] (4)

[0094] The system coefficients in equation (4) are K1 and K2.

[0095] At high speeds, air resistance is much greater than frictional resistance, so the frictional resistance term can be ignored, resulting in:

[0096] (5)

[0097] The simplified system coefficient is K1.

[0098] In some embodiments, the values ​​of K1 and K2 can be obtained by measuring the motor input current and speed during steady-state operation and then performing curve fitting on the collected data.

[0099] The circuit configuration of the cooling fan control system 1 can be summarized as follows. The system includes an inverter 20, which converts the input voltage into a motor drive signal. A motor 10 coupled to the inverter 20 drives the cooling fan. The system also includes a series of signal processing modules: a Clarke conversion module 140 coupled to the inverter 20; a Parker conversion module 150 coupled to the Clarke conversion module 140; and a position and rate estimator 160 coupled to the Parker conversion module 150. The control section includes: a low-pass filter 155 and a first subtractor 120 both coupled to the position and rate estimator 160; a first proportional-integral controller 125 coupled to the first subtractor 120; a second subtractor 130 coupled to both the first proportional-integral controller 125 and the Parker conversion module 150; a second proportional-integral controller 145 coupled to the second subtractor 130; and a space vector pulse width modulation (SVPWM) module 170 coupled to the second proportional-integral controller 145, the position and rate estimator 160, and the inverter 20.

[0100] Inverter 20 is powered by input voltage V IN Power supply, used to supply power based on input voltage V IN The control signal generates phase current I A I B and I C Motor 10 is used based on phase current I A I B and I C Drives the cooling fan. The Clark conversion module 140 is used to adjust the phase current I... A and I B Stator current I is generated through Clark conversion. α and I β The Parker conversion module 150 is used to adjust the rotor angle θ. r Stator current I α and I β DC current I is generated through Parker converter.d and orthogonal current I q The position and rate estimator 160 is used based on the DC current I. d With orthogonal current I q Generate rate signal ω r With rotor angle θ r The low-pass filter 155 is used based on the quadrature current I. q The average current I generated by motor 10 avg Subtractor 120 is used to adjust the control rate ωc and the rate signal ω. r A first difference signal is generated. The first proportional-integral controller 125 is used to generate a proportional-integral signal I based on the first difference signal. ω Subtractor 130 is used to calculate the proportional-integral signal I. ω and orthogonal current I q A second difference signal is generated. The second proportional-integral controller 145 generates a duty cycle signal Du based on the second difference signal. The SVPWM module 170 generates a duty cycle signal Du based on the duty cycle signal Du and the rotor angle θ. r Generate control signals for inverter 20.

[0101] The cooling fan control system 1 may further include a microcontroller 100 and a memory 110 coupled to the microcontroller 100. The microcontroller 100 can be used to generate a control rate ω. c The memory 110 can be used to store system coefficients, current thresholds, and / or maximum power.

[0102] In some embodiments, the cooling fan control system 1 includes a processing and storage subsystem, which includes a microcontroller 100 and a memory 110 communicatively coupled thereto. This configuration enables the system to control and monitor motor operation in real time while maintaining system parameters and operating thresholds.

[0103] The microcontroller 100 serves as the main processing unit of the cooling fan control system 1, executing the motor control algorithm. Specifically, the microcontroller 100 generates a control rate signal ω. c This signal defines the required operating speed of the motor. The microcontroller 100 can adjust this control speed signal ω according to various system conditions and operational requirements. c .

[0104] The memory 110 is operationally coupled to the microcontroller 100 and is used to store various types of operational data. The system coefficients stored in the memory relate to specific characteristics of the motor and fan components, including motor characteristics, fan design parameters, airflow drag factors, and speed-torque relationships. These coefficients are crucial for proper system operation and performance optimization.

[0105] The memory 110 further stores current thresholds to define the acceptable operating boundaries of the system. These include the normal operating current range, the maximum permissible current level, the current deviation threshold for fault detection, and time-dependent current monitoring parameters. These thresholds enable the system to maintain safe operation and detect potential anomalies.

[0106] In addition, memory 110 maintains maximum power parameters to establish system power consumption limits. These parameters include maximum input power thresholds, power consumption warning levels, power efficiency targets, and operating range boundaries. These power-related parameters ensure that the system operates effectively and safely within design specifications.

[0107] In some embodiments, the current threshold can be determined by the functional relationship between the system coefficient K1 and the rotational speed ω. Based on the system coefficient K1, the q-axis current required for the fan to operate at a specific constant speed ω can be calculated, and reasonable upper and lower current thresholds can be calculated using the following equations:

[0108]

[0109]

[0110] The tolerance error value x% can be set according to actual application requirements, and is generally set in the range of 5% to 20%.

[0111] In some embodiments, the maximum input power threshold can be derived from the motor input power equation:

[0112]

[0113] (6)

[0114] in:

[0115] Pe is the input motor power.

[0116] Re[] represents taking the real part of the result of the operation.

[0117] Motor drive voltage vector

[0118] The conjugate of the motor drive current vector

[0119] V d d-axis voltage

[0120] V q q-axis voltage

[0121] I d d-axis current

[0122] I q q-axis current

[0123] For surface-mounted permanent magnet synchronous motors (SPMSMs), when field weakening control is not used, I d Maintaining at 0. Therefore, equation (6) can be simplified to:

[0124] (7)

[0125] Input power can be calculated using equation (7). Maximum input power refers to the maximum input power required by the motor when it is operating at a constant angular velocity, and the maximum input power threshold can be calculated based on the motor's rated parameters and safety margin.

[0126] During operation, the microcontroller 100 continuously accesses the memory 110 to perform several key functions. The microcontroller retrieves stored parameters for comparison with real-time measurements, updates operating data based on the current system state, performs control calculations with reference to system coefficients, and accesses thresholds for fault detection. This continuous interaction between the microcontroller and the memory ensures optimal system performance and reliability.

[0127] The memory 110 can use various storage technologies to meet different operational needs. Non-volatile memory components are used to store permanent parameters that must be retained after the system is powered off. Random access memory provides high-speed storage of temporary operational data, while flash memory can store updatable system parameters that may need to be modified during system use.

[0128] In one embodiment of the present invention, the cooling fan control system 1 includes a voltage monitoring circuit for measuring and regulating the input voltage supplied to the motor. Specifically, the voltage monitoring circuit includes a first resistor 102 and a second resistor 103 connected in series between the input voltage node and the ground node, forming a voltage divider network. The connection point between the first resistor 102 and the second resistor 103 defines a measurement node for generating a voltage reading relative to the input voltage V. IN The circuit voltage Ve is proportional.

[0129] A voltage divider network can operate according to the following formula:

[0130]

[0131] Wherein, R1 is the resistance value of the first resistor 102, and R2 is the resistance value of the second resistor 103.

[0132] In some embodiments, the resistance values ​​of R1 and R2 can be selected such that when the input voltage V... INWhen the circuit voltage Ve varies within the expected operating range, it can remain within a predetermined range suitable for the input of the microcontroller 100. For example, when the input voltage V IN When at its expected maximum value, the circuit voltage Ve should not exceed the maximum permissible input voltage of the microcontroller 100.

[0133] Figure 2 A flowchart of a method 200 for predicting potential cooling fan failures implemented in a cooling fan control system 1. Method 200 includes the following steps:

[0134] S210: Microcontroller 100 based on phase current I A I B and I C Generates orthogonal current I q ;

[0135] S220: Low-pass filter 155 calculates the average current I based on the average speed of motor 10. avg ;

[0136] S230: Microcontroller 100 based on quadrature current I q and average current I avg Ripple current I rp ;

[0137] S240: Compare average current I avg With ripple current I rp ;

[0138] S250: Determine ripple current I rp Does it deviate from the average current I within the set time period? avg If the predetermined threshold is exceeded, proceed to step S270; otherwise, return to step S210.

[0139] S260: Alarm signal triggered.

[0140] In the detailed process of step S210, the microcontroller 100 first measures the phase current I. A I B and I C Then, the phase current I is converted using a Clark converter. A I B and I C Converted to stator current I α and I β Specifically, the stator current I α equals I A The stator current I β Then by The calculation yielded the result. Next, the cooling fan control system 1 generated I via a Parker converter. q Its calculation formula is , where θ r This represents the rotor angle.

[0141] In step S220, the low-pass filter 155 processes the quadrature current I. q To calculate the average current I avg This process establishes a baseline signal for normal operating conditions, serving as a critical reference point for detecting any anomalies in the cooling fan control system 1. This baseline is continuously maintained and updated during normal operation to accommodate gradual changes in motor characteristics.

[0142] In step S230, the microcontroller 100 generates ripple current I through a series of processing steps. rp First, let's start with the orthogonal currents I. q Subtract the average current I from the middle avg To eliminate low-frequency components, another low-pass filter is used to remove high-frequency harmonics. This process separates the mechanical rotation frequency component, generating a ripple signal that effectively indicates changes in motor torque.

[0143] In step S240, the system retrieves the reference average current I from the memory. avg and with ripple current I rp Comparison. In step S250, the system evaluates the ripple current I. rp Check if the deviation exceeds a predetermined threshold within a set time period. This set time period helps avoid misjudgments due to transient fluctuations. If the deviation continues to exceed the set time period, an alarm phase is initiated; otherwise, the system returns to the monitoring phase.

[0144] In step S260, the system generates an alarm signal when it detects a persistent deviation, which can be transmitted to a remote monitoring system via a communication interface. This alarm indicates that the bearing of motor 10 may be experiencing an abnormal condition. This monitoring method is a non-invasive bearing condition monitoring technology, which can detect potential faults early without direct contact with the bearing, and has advantages over traditional vibration analysis methods.

[0145] Figure 3 This is a schematic diagram of the orthogonal current Iq generated by the microcontroller 100 during the operation of the motor 10. The orthogonal current Iq represents the torque-generating component of the motor current. This signal is obtained through the coordinate transformation of the phase current and can show the characteristic changes during motor operation.

[0146] like Figure 3 As shown, the orthogonal currents I q The waveform exhibits time-varying characteristics and amplitude modulation. These modulations originate from the electromagnetic interaction between the stator and rotor, as well as mechanical factors including bearing conditions. The diagram of the orthogonal current Iq signal shows low-frequency components related to the average operation of motor 10, and high-frequency components that may indicate mechanical abnormalities.

[0147] Orthogonal current I q This is the main input signal for the bearing fault detection program. This signal is processed by a low-pass filter 155 to generate an average current I. avg This establishes a baseline for normal operating conditions. The time-domain characteristics of orthogonal currents, including their amplitude variations and frequency components, can provide important information about the mechanical state of motor bearings.

[0148] In some embodiments, the microcontroller 100 continuously samples and processes this quadrature current I at a predetermined sampling rate. q This sampling rate is sufficient to extract the relevant mechanical frequency components. Signal processing maintains phase coherence and amplitude accuracy to facilitate accurate assessment of bearing condition. The characteristics of quadrature currents may vary depending on motor specifications, operating conditions, and bearing configuration; therefore, adaptive processing techniques are required to achieve optimal anomaly detection results.

[0149] Figure 4 The low-pass filter 155 is based on the quadrature current I q The average current I generated avg (Diagram showing the reference signal) Average current I avg This represents the average motor current characteristic under normal operating conditions, serving as a reference point for detecting bearing malfunctions. Average current I avg It can be achieved through the orthogonal current I q It is obtained by performing a low-pass filter operation, which effectively removes high-frequency components and preserves the basic operating characteristics of the motor.

[0150] like Figure 4 As shown, the average current I avg It presents a smooth waveform, extracting the fundamental low-frequency components of the motor's current consumption. Its characteristics reflect the motor's steady-state operation, including rated load conditions, basic mechanical resistance, and standard operating parameters. Average current I avg Its relatively stable characteristics provide a reliable benchmark for detecting deviations in motor operating behavior.

[0151] In some embodiments, the average current I avg Continuously updated and stored in memory 110, the system adapts to gradual changes in motor characteristics over time. This dynamic update mechanism ensures the detection system maintains sensitivity to sudden anomalies while adapting to normal wear and environmental changes. Average current I avg The temporal evolution may exhibit a gradual correction reflecting the natural aging of motor components, while maintaining sufficient stability as a reference for anomaly detection.

[0152] The low-pass filter 155 can be specially designed to extract the average current I. avgAt the same time, sufficient time-domain resolution is maintained to facilitate effective comparison with instantaneous motor current characteristics. The filtering operation is optimized to retain information relevant to bearing condition assessment while suppressing noise and transient changes that may lead to misjudgment.

[0153] Figure 5 Orthogonal current I q With average current I avg A schematic diagram of the difference signal obtained from the subtraction operation. This subtraction operation is a key signal processing step in the detection method, used to remove low-frequency components associated with normal motor operation.

[0154] like Figure 5 As shown, the difference signal represents the difference from the average current I. avg Subtract the orthogonal current I from the middle q The result is that variations deviating from established normal operating conditions are separated. This intermediate signal retains the mechanical frequency component and high-frequency harmonics that may indicate bearing abnormalities. The subtraction operation effectively eliminates the steady-state component of the motor current, enhancing the visibility of potential bearing-related anomalies.

[0155] In some embodiments, the subtraction procedure is processed in real-time by the microcontroller 100 to ensure precise timing alignment between the quadrature current and the average current, thereby improving the accuracy of anomaly detection. The resulting signal retains the dynamic characteristics of motor operation and highlights deviations from normal operating behavior. These intermediate signals serve as inputs to subsequent filtering operations, further enhancing the accuracy of bearing anomaly detection.

[0156] The amplitude and temporal characteristics of the difference signal provide crucial information about instantaneous deviations from normal motor operation. These deviations, after appropriate filtering and analysis, can serve as early indicators of developing bearing problems, enabling the system to take preventative measures before catastrophic failures occur. Signal processing parameters are specifically optimized to maintain sensitivity to bearing-related anomalies while mitigating the impact of normal operational variations.

[0157] Figure 6 The ripple current I obtained after subsequent filtering of the aforementioned difference signal rp Schematic diagram. This ripple current I rp Processed by microcontroller 100 through low-pass filter 155 The difference signal is used to effectively separate the mechanical rotation frequency component that is closely related to bearing condition assessment.

[0158] like Figure 6 As shown, the ripple current I rpThis represents the processed signal used for bearing anomaly detection. After removing the average current component, this additional filtering operation eliminates high-frequency harmonic components while preserving the frequency range associated with mechanical anomalies. The resulting waveform exhibits characteristics directly related to potential bearing irregularities, providing clear indicators for the detection system.

[0159] In some embodiments, the parameters of the low-pass filter are optimized to separate the frequency components best suited for bearing condition monitoring. The filtered ripple current I... rp It can be used as the primary measurement indicator and compared with a predetermined threshold. When the ripple current I... rp If the ripple current consistently exceeds a predetermined threshold within a set time period, the system will trigger an alarm signal. Additionally, the ripple current I... rp Its time-domain characteristics maintain sufficient accuracy, thus ensuring reliable detection of developing bearing problems.

[0160] Ripple current I rp The amplitude changes provide crucial information about the mechanical condition of the motor 10 bearing. When these changes consistently exceed a predetermined threshold within a set time period, the system alarm mechanism is triggered, indicating a potential bearing anomaly requiring attention. The filtered signal forms the basis of the system's non-invasive bearing condition monitoring method, which has advantages over traditional vibration analysis methods, enabling early detection of anomalies without direct contact with the bearing.

[0161] It is important to note that in brushless DC motors under field-oriented control (FOC), the quadrature current I... q This represents the torque-generating component of the motor current. Quadrature current I q There is a direct physical relationship between it and the mechanical operation of the motor. Specifically, the orthogonal current I q The current component that forms a 90-degree angle with the rotor magnetic field (hence the term "orthogonal") is the one that generates electromagnetic torque to drive the rotor's rotation. This characteristic makes the orthogonal current I... q This is particularly relevant in bearing testing because it is directly related to the motor's torque output. Any mechanical resistance or bearing friction requires additional torque to overcome, which manifests as an orthogonal current I. q Changes in bearing wear or abnormal conditions can cause these problems to occur in the orthogonal current I. q The phenomenon is manifested as ripples or other graphical forms, and variations in its frequency and amplitude can indicate specific types of bearing problems. Quadrature current I q It can capture the dynamic response of a motor to mechanical loads. Normal bearing operation produces a baseline characteristic graph; deviations from this graph may indicate an underlying bearing problem, thus reflecting changes in the mechanical state in real time. This fundamental physical relationship enables the orthogonal current I... qThis becomes an ideal parameter for non-invasive bearing monitoring. As described in this invention, by analyzing the orthogonal current I... q The graphs and changes can effectively detect early signs of bearing wear or damage.

[0162] The above embodiments represent a significant breakthrough in motor maintenance and monitoring technology, particularly in bearing anomaly detection. This innovative approach offers a non-invasive monitoring solution that utilizes existing current sensing infrastructure within the motor control system without direct contact with the bearing. Through precise signal processing techniques and current ripple analysis, the system can detect potential bearing problems without disassembly or the addition of sensors.

[0163] One of the major advantages of this invention is its early detection capability. The system continuously monitors the current ripple pattern during motor operation, enabling it to identify minute changes in bearing condition before catastrophic failures occur. This early warning capability is achieved through advanced signal processing technology, which effectively separates relevant frequency components while eliminating interference from normal operational variations. The system is highly adaptable, maintaining sensitivity to sudden anomalies as motor characteristics gradually change.

[0164] From a cost-effectiveness perspective, this invention fully utilizes existing motor control hardware, providing a highly effective monitoring solution without the need for expensive vibration analysis equipment. This significantly reduces implementation costs while still offering equivalent or superior monitoring capabilities. The system supports conditional maintenance scheduling, helping to optimize maintenance work, reduce unnecessary preventative maintenance activities, and effectively prevent sudden failures and emergency repairs. This proactive approach extends equipment life and minimizes maintenance costs and system downtime.

[0165] This invention offers significant operational benefits in practical applications. The system can continuously monitor its condition without interrupting normal operation and provides remote monitoring capabilities that improve maintenance efficiency. Its high compatibility with existing brushless DC motor control systems, as well as its scalability across different motor sizes and types, makes it particularly suitable for various applications such as cooling fans, pumps, and air conditioning systems. This adaptability further expands its application prospects in various industrial and commercial sectors.

[0166] This invention represents an innovative approach to motor maintenance technology, providing a practical and cost-effective solution that overcomes the limitations of traditional vibration analysis methods. By enabling predictive maintenance through non-invasive monitoring, the system not only helps optimize operational efficiency and reduce maintenance costs but also extends equipment lifespan. Combining sophisticated signal processing, early detection capabilities, and practical implementation methods, this technology makes a significant contribution to the fields of motor maintenance and reliability engineering.

[0167] In this specification and the scope of the claims, the terminology used is for the purpose of describing specific embodiments of the invention only and should not be construed as limiting the scope of the invention. Unless the context clearly indicates otherwise, the singular forms "a," "the," etc., used in this specification and the scope of the claims should be understood to include their plural forms as well.

[0168] As used herein, the term “and / or” should be interpreted as encompassing any single item or any combination of the listed items. Specifically, when expressions such as “A and / or B” are used, they should be understood to include: (1) A only; (2) B only; and (3) both A and B.

[0169] Furthermore, when the terms "comprising," "including," or "having" are used herein, they should be understood as indicating the presence of the stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof. In other words, these terms should be interpreted as introducing an open-ended enumeration, not a closed-ended enumeration.

[0170] In this document, the terms “coupled,” “connected,” and “electrically connected” are used interchangeably and should be broadly understood to indicate the state of electrical and / or electronic connection. These terms should not be interpreted restrictively but should encompass all forms of electrical or electronic connection. Furthermore, the term “communication” as used in this invention should be understood as a broad concept. Specifically, when describing “communication” between a first entity and a second entity, this means that the first entity is sending and / or receiving signals to and / or from the second entity electrically (via wired or wireless media). These signals may include, but are not limited to, voice information, image information, control information, or any combination thereof. It is worth noting that the above definition of “communication” is not limited by signal type and can apply to both analog and digital signals. In other words, any transmission or reception of electrical messages, regardless of their specific form, should be considered within the scope of “communication” as described in this invention.

[0171] The ordinal numbers such as "first" and "second" are used in this specification and claims to distinguish multiple elements with similar names. These ordinal numbers do not imply any inherent order, priority, or chronological order in the manufacturing process, nor do they imply any functional relationship between the elements. These ordinal numbers serve only as a means of identification to uniquely identify and distinguish multiple instances of elements with the same name or description.

[0172] The directional terms used in this embodiment, such as up, down, left, right, upper side, lower side, front, or rear, refer to the directions shown in the accompanying drawings. Therefore, the directional terms used in this disclosure are for illustrative purposes only and are not intended to limit the scope of this disclosure. It should be noted that the elements specifically described or indicated herein may exist in various forms to those skilled in the art.

[0173] In this specification and claims, terms of approximation such as "substantially," "approximately," "roughly," "essentially," "almost," and "about" are used to indicate variations in precision, manufacturing tolerances, measurement accuracy, environmental conditions, and inherent material properties that may affect the described features or characteristics. These variations may range from ±20% in more lenient applications to more stringent tolerances of ±10%, ±5%, ±3%, ±2%, ±1%, or ±0.5% in more precise embodiments. In any given context, the specific degree of variation covered by these approximations depends on the nature of the described elements, relationships, or parameters, the technical requirements of the particular embodiment, and the understanding of those skilled in the art.

[0174] The illustrative elements, logic, logic blocks, modules, circuits, operations, and algorithm steps described in the various embodiments of the present invention can be implemented by electronic hardware, firmware, software, or any combination thereof. The functional interchangeability of hardware, firmware, and software has been generally described in the various illustrative elements, modules, and circuits described above. The choice of a specific implementation will depend on the constraints of the particular application and the overall system design.

[0175] The hardware and data processing apparatus used to implement the various illustrative components, logic, logic blocks, modules, and circuits described herein may include, but are not limited to: general-purpose single-chip or multi-chip processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices (PLDs), discrete gate or transistor logic, discrete hardware components, or any combination thereof. This hardware and apparatus shall be configured to perform the functions described herein. A general-purpose processor may be a microprocessor, or any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors working in conjunction with a DSP core, or any other such configuration. In some embodiments, specific functions may be performed by dedicated circuitry to optimize performance.

[0176] As previously described, certain aspects of the present invention can be implemented in software. For example, the various functions of the components, or the various blocks or steps of the methods, operations, programs, or algorithms, can be implemented as non-transitory processor-executable instructions or computer-executable instructions in one or more computer program modules. These instructions can be encoded on one or more processor-readable or computer-readable storage media for execution by or control of the operation of a data processing apparatus (including the apparatus components described herein). Such storage media may include, but are not limited to: random-access memory (RAM), read-only memory (ROM), electrically-erasable programmable read-only memory (EEPROM), hard disk storage, optical disk storage, magnetic disk storage, or other magnetic storage devices, or any other medium capable of storing program code in the form of instructions or data structures. Any combination of these storage media should also be considered within the scope of protection of the present invention.

[0177] In the description of the embodiments, the various illustrative elements, logic, logic blocks, modules, circuits, operations, and algorithm steps can be implemented using electronic hardware, firmware, software, or a combination thereof. The functional interchangeability of hardware, firmware, and software has been generally illustrated in the various illustrative elements, modules, circuits, and steps described above. Whether such functionality is implemented via hardware, firmware, or software depends on the specific application and the constraints of the overall system design.

[0178] Some embodiments may include additional features not specifically described herein, while other embodiments may not include undisclosed elements. In other words, undisclosed elements may be selectively omitted. It should be emphasized that the omission of undisclosed elements should be considered as one possible implementation of the invention, rather than a limitation. This allows the invention to be adapted to different application scenarios and technical requirements.

[0179] Although the various features described in this invention may be described within the context of a single embodiment, it should be understood that these features can be combined or separated in various ways to constitute different implementations. Features described in a single embodiment may be integrated into a comprehensive embodiment, implemented separately in multiple independent embodiments, or implemented in any suitable sub-combination. Therefore, the scope of the claims of this invention may include combinations of all features, sub-combinations after removing one or more features, and variations or modifications of these sub-combinations. This flexible structure is intended to provide comprehensive protection and allow for technological development, enabling the invention to adapt to different application needs and technical conditions. The scope of protection of this invention should include, but is not limited to, the explicitly described embodiments, but should also cover all variations, modifications, and sub-combinations consistent with the basic principles of this invention.

[0180] The order of operations described in the various embodiments of the present invention, as illustrated in the accompanying drawings, should not be construed as a restrictive order of execution. The order of these operations can be adjusted according to specific implementations to achieve the desired result without performing all illustrated operations. The scope of the invention also includes inserting additional operations (not illustrated) between the illustrated operations. For example, one or more additional operations may be performed before, after, or simultaneously with any illustrated operation.

[0181] In some implementations, multiplexing or parallel processing techniques may be employed to improve efficiency. Furthermore, the separation of the various system components described in this specification should not be construed as requiring such a division in all implementations. Instead, the described program components and systems may be integrated into a single software suite or multiple software suites depending on specific needs.

[0182] It should be specifically noted that the various schematic diagrams (including but not limited to component diagrams) discussed herein are provided for illustrative purposes only and are not drawn to scale. These diagrams are intended to aid in understanding various aspects of the invention and should not be construed as limiting the scope of the invention.

[0183] Those skilled in the art will readily understand various modifications to the embodiments described herein, and the general principles defined herein can also be applied to other embodiments without departing from the spirit or scope of this document. Therefore, the claims are not limited to the embodiments described herein, but should be given the broadest scope consistent with this document, the principles stated herein, and the novel features disclosed herein.

[0184] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made in accordance with the claims of the present invention shall be within the scope of the present invention.

Claims

1. A method for detecting abnormal conditions of a motor, comprising: Orthogonal currents are generated by a microcontroller; The average current is calculated based on this orthogonal current using a low-pass filter; The ripple current is generated by this microcontroller; Compare the ripple current with the average current; Determine whether the ripple current deviates from the average current by more than a predetermined threshold within a set time period; and An alarm signal is triggered when the ripple current deviates from the average current by more than the predetermined threshold within the set time period.

2. The method of claim 1, wherein generating the orthogonal current comprises: Measure the phase current of the motor; The Clarke transform is used to convert this phase current into a two-phase current; and Use the Park transform to convert the biphase current into the quadrature current.

3. The method of claim 2, wherein the Parker conversion generates the orthogonal current based on the rotor angle.

4. The method of claim 1, wherein generating the ripple current comprises: Subtract the average current from the orthogonal current to eliminate low-frequency components and obtain the intermediate current; and The intermediate current is filtered to eliminate high-frequency components.

5. The method of claim 1, wherein the average current is updated during normal operation of the motor.

6. The method of claim 1 further includes transmitting the alarm signal to a remote monitoring system via a communication interface.

7. The method of claim 1, wherein the motor comprises a brushless DC motor controlled by a field-guided control algorithm.

8. The method of claim 1, wherein calculating the average current includes filtering the quadrature current through the low-pass filter to eliminate high-frequency components.

9. The method of claim 1, wherein determining whether the ripple current deviates from the average current includes monitoring the amplitude change of the ripple current.

10. The method of claim 1, wherein the motor operates within a feedback loop control to adjust the motor speed based on a rate control signal.

11. A motor control system, comprising: An inverter is used to generate first-phase current, second-phase current and third-phase current based on input voltage and multiple control signals; A motor, coupled to the inverter, is used to drive a cooling fan according to the first phase current, the second phase current and the third phase current; The Clarke transform module, coupled to the inverter, is used to generate a first stator current and a second stator current based on the first phase current and the second phase current through Clarke transformation. The Park transform module, coupled to the Clark transform module, is used to generate DC current and quadrature current based on the rotor angle, the first stator current and the second stator current through the Park transform. A position and rate estimator, coupled to the Parker conversion module, is used to generate a rate signal and a rotor angle based on the DC current and the quadrature current. A low-pass filter, coupled to the position and speed estimator, is used to generate the average current of the motor based on the orthogonal current; A first subtractor, coupled to the position and the rate estimator, is used to generate a first difference signal based on the control rate and the rate signal. A first proportional-integral (PI) controller, coupled to the first subtractor, is used to generate a proportional-integral signal based on the first difference signal; The second subtractor is coupled to the first proportional-integral controller and the Parker conversion module to generate a second difference signal based on the proportional-integral signal and the quadrature current. A second proportional-integral controller is coupled to the second subtractor to generate a duty cycle signal based on the second difference signal; A space vector pulse width modulation (SVPWM) module, coupled to the second proportional-integral controller, the position and rate estimator, and the inverter, is used to generate the plurality of control signals for the inverter based on the duty cycle signal and the rotor angle. in: The low-pass filter generates ripple current based on the average current and the quadrature current; and An alarm signal is generated when the ripple current exceeds a predetermined deviation threshold.

12. The motor control system of claim 11, further comprising: A microcontroller is used to generate this control rate; and A memory, coupled to the microcontroller, is used to store system coefficients, the predetermined deviation threshold, and / or maximum power.

13. The motor control system of claim 11, further comprising: The first resistor and the second resistor are connected in series to form a voltage divider, wherein the voltage divider generates the circuit voltage based on the input voltage.

14. The motor control system of claim 11, wherein the motor comprises a brushless DC motor.

15. The motor control system of claim 11, wherein the rate signal and the average current are averaged over a predetermined time period during which the control rate remains constant.

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