Constant air volume control method for multi-motor fan system with fault-tolerant characteristic

Abstract

The invention provides a multi-motor fan system constant air volume control method with a fault-tolerant characteristic, and relates to the field of multi-motor drive fan systems.In the method, a multi-motor fan system at least comprises two BLDC motors, each motor drives a wind wheel through current closed-loop control, and the multiple wind wheels are installed in an air duct in parallel; control currents of all the motors are controlled by the same microprocessor, the motors feed back rotating speed signals to the microprocessor in real time through encoders, and the microprocessor is used for receiving the rotating speed signals, calculating rotating speed errors of all the motors and sending current signal instructions; and the microprocessor adjusts driving current signals of the motors according to the rotating speed errors and adjusts the rotating speeds of the motors, so that the total air volume of the multi-motor fan system is controlled within a preset target value range. The system parameters can be automatically adjusted when the motor breaks down, stable output of the air volume is ensured, and therefore the reliability of the system is improved, and the maintenance cost is reduced.

Description

Technical Field

[0001] The present invention relates to the field of multi-motor driven fan systems, and in particular to a multi-motor fan system constant air volume control method with fault-tolerant characteristics. Background Art

[0002] In traditional single-fan systems, since the system relies only on a single motor to drive the wind wheel for air supply, once the motor fails, the system output air volume will drop sharply, resulting in failure to meet user needs. Especially in multi-motor fan systems, there is usually no fault-tolerant design for motor failures, and the existing motor fault diagnosis and fault-tolerant control methods mostly rely on additional sensors or fault diagnosis devices, which not only increases the cost of the system, but also increases the complexity of installation and maintenance. Therefore, how to solve the motor failure problem and improve the reliability and fault tolerance of the system without increasing the system cost is a technical problem that needs to be solved urgently in the industry. Summary of the invention

[0003] In view of this, the present invention proposes a constant air volume control method for a multi-motor fan system with fault-tolerant characteristics. The method does not require additional fault diagnosis devices, has a simple and efficient structure, and can automatically adjust system parameters when a motor fails to ensure stable output of air volume, thereby improving system reliability and reducing maintenance costs.

[0004] The present invention is implemented by the following technical solutions:

[0005] The present invention provides a method for controlling constant air volume of a multi-motor fan system with fault tolerance characteristics, the method comprising the following steps:

[0006] The multi-motor fan system includes at least two BLDC (Brushless Direct Current Motor) motors, each of which drives a wind wheel through current closed-loop control, and multiple wind wheels are installed in parallel in the air duct;

[0007] The control current of all motors is controlled by the same microprocessor. The motor feeds back the speed signal to the microprocessor in real time through the encoder. The microprocessor is used to receive the speed signal, calculate the speed error of each motor and send the current signal instruction.

[0008] The microprocessor adjusts the driving current signal of the motor according to the speed error, adjusts the motor speed, and controls the total air volume of the multi-motor fan system within a predetermined target value range.

[0009] As a further solution of the present invention, the BLDC motors included in the multi-motor fan system have the same specifications. When a motor fails, the microprocessor automatically adjusts the control current of the motor so that the total speed of the motor reaches the target total speed.

[0010] As a further solution of the present invention, the total motor speed is the sum of the motor speeds included in the motor-fan system; the speed error is the difference between the real-time total motor speed and the target total speed.

[0011] As a further solution of the present invention, the microprocessor is built with an adaptive fault-tolerant controller, and the adaptive fault-tolerant controller calculates a fault compensation gain based on real-time speed feedback information and a speed error.

[0012] As a further solution of the present invention, the calculation formula of the fault compensation gain is:

[0013]

[0014] Where i is the current signal command, is the fault compensation gain, b is the motor friction coefficient, J is the moment of inertia constant, k t is the electromagnetic torque constant, P is the positive gain constant, ω and They are the total motor speed and speed error respectively.

[0015] As a further solution of the present invention, the current signal instruction i is calculated in real time by an adaptive fault-tolerant controller stored inside the microprocessor, and the current signal instructions of multiple motors all come from the same microprocessor.

[0016] As a further solution of the present invention, the microprocessor acquires and monitors the speed information of each motor in real time to determine whether the motor fails.

[0017] As a further solution of the present invention, the microprocessor obtains the speed information including the speed error, motor rotational inertia, and electromagnetic torque constant parameters fed back by the motor in real time, and when the actual speed deviates from the target speed, it updates and adjusts the fault compensation gain in real time to compensate for motor failure or performance degradation.

[0018] As a further solution of the present invention, when the fault compensation gain is updated and adjusted in real time, the fault compensation gain according to Real-time update; where Q is the positive gain constant; is the fault compensation gain The derivative of The law of change.

[0019] As a further solution of the present invention, when the motor speed deviates from the target speed, the microprocessor determines that the motor has failed. The motor failure includes partial failure and complete failure. The failure type of the motor failure is determined by the electromagnetic torque constant attenuation factor α: the attenuation factor 0<α<1 represents partial failure of the motor; the attenuation factor α=0 represents complete failure of the motor; the attenuation factor α=1 represents normal operation of the motor.

[0020] Compared with the prior art, the present invention provides a method for controlling constant air volume of a multi-motor fan system with fault tolerance, which has the following beneficial effects:

[0021] 1. The present invention makes each BLDC motor into a current closed-loop control motor. Each motor feeds back real-time speed information to the microprocessor. The microprocessor calculates the fault compensation gain and the control current signal according to the fed-back speed information, and then sends the same current signal instruction to each motor to realize adaptive fault-tolerant control of multiple motors. The algorithm is simple in design and can effectively improve the reliability of the fan system and reduce maintenance costs.

[0022] 2. The present invention uses adaptive fault-tolerant control, and the system can automatically adjust the current and speed compensation when the motor partially fails, avoiding the impact on the system air volume after the motor completely fails. The intelligent compensation mechanism effectively delays the performance degradation of the motor, extends the service life of the motor and the entire fan system, and reduces the downtime and maintenance costs caused by hardware failures. When the motor fails or the performance decays, the fan system can automatically adjust the control strategy and compensate for the speed error caused by the failure in real time. Its fault-tolerant characteristics effectively improve the stability of the system. Even if an individual motor fails, the entire system can still maintain a constant air volume output, ensuring the high reliability of the fan system during long-term operation.

[0023] 3. Compared with the traditional method, the method of the present invention does not need to rely on additional hardware fault detection devices. The feedback information of the motor speed is monitored in real time by the microprocessor, the speed error is calculated, and the drive current is automatically adjusted according to the error change, thereby eliminating the need for complex fault detection modules or external sensors. The hardware design and system structure are simplified, and the equipment cost and maintenance difficulty are reduced. Since the control signals of all motors are calculated and sent by the same microprocessor, the system can automatically coordinate the working status of each motor based on the real-time speed feedback, ensure the synergy between the motors, and optimize the overall air volume control. This simplified control strategy reduces the complexity of the system, reduces the difficulty of developing the control algorithm, and enhances the flexibility and adaptability of the system.

[0024] 4. The present invention can dynamically adjust the fault compensation gain and drive current according to the feedback information and real-time changes of the motor speed to adapt to the performance changes of the motor. This adaptive control enables the system to maintain a stable air volume output when facing motor load fluctuations or changes in environmental conditions, thereby enhancing the system's response capability and reliability. By utilizing the existing motor speed feedback and microprocessor calculation compensation mechanism, the system does not need to add additional sensors or detection modules, making full use of existing hardware resources. This not only reduces system costs, but also reduces hardware failure rates and maintenance frequency, improving the economy and sustainability of the system.

[0025] 5. In the event of a motor failure or performance degradation, the fault compensation gain calculation formula and dynamic adjustment strategy of the present invention can accurately compensate for changes in air volume, thereby ensuring that the system air volume is always maintained at a predetermined target value. This high-precision control ensures that in the event of a fault, the air volume fluctuation of the fan system is minimal and the overall performance of the system is not significantly affected. The fault-tolerant control method of the present invention is not only applicable to conventional fan systems, but can also be widely used in various complex scenarios that require constant air volume, such as industrial ventilation, air conditioning systems, climate control and other fields. In the face of motor aging, load changes or other unexpected factors, the system can adaptively adjust to ensure continuous and stable air volume.

[0026] In summary, the multi-motor fan system constant air volume control method with fault-tolerant characteristics of the present invention, through an innovative adaptive fault-tolerant control algorithm, enables the system to still operate stably in the case of motor failure or performance degradation, and has the advantages of high reliability, low cost, and easy maintenance. This makes the present invention have broad application prospects and economic benefits in industry and other fields that require constant air volume.

[0027] These and other aspects of the present invention will be more clearly understood in the following description of the embodiments. It should be understood that the above general description and the following detailed description are only exemplary and explanatory and cannot limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the following briefly introduces the drawings required for use in the exemplary embodiments or related technical descriptions. The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation to the present invention. In the drawings:

[0029] Figure 1 The figure is a schematic diagram of the implementation principle of the constant air volume control method of a multi-motor fan system with fault tolerance characteristics according to an embodiment of the present invention.

[0030] Figure 2 It is a schematic diagram of comparison curves between the total motor speed and the target total speed under various fault conditions in a constant air volume control method for a multi-motor fan system with fault tolerance characteristics in an embodiment of the present invention.

[0031] Figure 3 It is a schematic diagram of error curves between the total motor speed and the target total speed under various fault conditions in a constant air volume control method for a multi-motor fan system with fault tolerance characteristics in an embodiment of the present invention.

[0032] Figure 4 The present invention is a schematic diagram of the speed change curves of the two motors in a multi-motor fan system constant air volume control method with fault tolerance characteristics under various fault conditions according to an embodiment of the present invention.

[0033] Figure 5 It is a schematic diagram of the measured fitting curve of the motor speed and air volume of the fan system in the constant air volume control method of the multi-motor fan system with fault-tolerant characteristics in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0035] In some of the processes described in the specification and claims of the present invention and the above-mentioned figures, multiple operations that appear in a specific order are included, but it should be clearly understood that these operations may not be executed in the order in which they appear in this article or executed in parallel. The serial numbers of the operations, such as 101, 102, etc., are only used to distinguish between different operations, and the serial numbers themselves do not represent any execution order. In addition, these processes may include more or fewer operations, and these operations may be executed in sequence or in parallel. It should be noted that the descriptions of "first", "second", etc. in this article are used to distinguish different messages, devices, modules, etc., do not represent the order of precedence, and do not limit the "first" and "second" to be different types.

[0036] Since traditional multi-fan systems usually do not have a fault-tolerant design for motor failures, existing motor fault-tolerant control methods are mostly based on traditional fault detection and diagnosis technologies, requiring additional sensors or fault diagnosis devices, which greatly increases the cost of fan equipment and installation costs. The present invention proposes a constant air volume control method for a multi-motor fan system with fault-tolerant characteristics. The method does not require additional fault diagnosis devices, has a simple and efficient structure, and can automatically adjust system parameters when a motor fails to ensure stable output of air volume, thereby improving system reliability and reducing maintenance costs.

[0037] The following will be combined with the drawings in the exemplary embodiments of the present invention to clearly and completely describe the technical solutions in the exemplary embodiments of the present invention. Obviously, the exemplary embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0038] See also Figures 1 to 5 As shown, a method for controlling constant air volume of a multi-motor fan system with fault tolerance is provided in one embodiment of the present invention, comprising the following steps:

[0039] The multi-motor fan system includes at least two BLDC motors, each of which drives a wind wheel through current closed-loop control, and multiple wind wheels are installed in parallel in the air duct;

[0040] The control current of all motors is controlled by the same microprocessor. The motor feeds back the speed signal to the microprocessor in real time through the encoder. The microprocessor is used to receive the speed signal, calculate the speed error of each motor and send the current signal instruction.

[0041] The microprocessor adjusts the driving current signal of the motor according to the speed error, adjusts the motor speed, and controls the total air volume of the multi-motor fan system within a predetermined target value range.

[0042] In this embodiment, the BLDC motors included in the multi-motor fan system have the same specifications. When a motor fails, the microprocessor automatically adjusts the control current of the motor so that the total speed of the motor reaches the target total speed. The total speed of the motor is the sum of the speeds of the motors included in the motor fan system; the speed error is the difference between the real-time total speed of the motor and the target total speed.

[0043] In this embodiment, the microprocessor is built with an adaptive fault-tolerant controller, and the adaptive fault-tolerant controller calculates the fault compensation gain based on the real-time speed feedback information and the speed error, wherein the calculation formula of the fault compensation gain is:

[0044]

[0045] Where i is the current signal command, is the fault compensation gain, b is the motor friction coefficient, J is the moment of inertia constant, k t is the electromagnetic torque constant, P is the positive gain constant, ω and They are the total motor speed and speed error respectively.

[0046] In this embodiment, the current signal instruction i is calculated in real time by the adaptive fault-tolerant controller stored in the microprocessor, and the current signal instructions of multiple motors all come from the same microprocessor. The microprocessor obtains and monitors the speed information of each motor in real time to determine whether the motor has a fault.

[0047] Among them, the microprocessor obtains the speed information including the speed error, motor rotational inertia, and electromagnetic torque constant parameters fed back by the motor in real time. When the actual speed deviates from the target speed, it updates and adjusts the fault compensation gain in real time to compensate for motor failure or performance degradation.

[0048] When the fault compensation gain is updated and adjusted in real time, the fault compensation gain according to Real-time update; where Q is the positive gain constant; is the fault compensation gain The derivative of The law of change.

[0049] When the motor speed deviates from the target speed, the microprocessor determines that the motor has failed. Motor failures include partial failure and complete failure. The failure type of the motor failure is determined by the electromagnetic torque constant attenuation factor α: attenuation factor 0<α<1, representing partial failure of the motor; attenuation factor α=0 represents complete failure of the motor; attenuation factor α=1 represents normal operation of the motor.

[0050] In this embodiment, the torque fault refers to the attenuation of the electromagnetic torque constant due to aging of motor components and changes in ambient temperature and humidity.

[0051] like Figure 1 As shown, in one embodiment of the present invention, in a constant air volume control method for a multi-motor fan system with fault-tolerant characteristics, the multi-motor fan system uses two BLDC motors to drive two wind wheels respectively, and the two motors and wind wheels are installed in parallel in the same air duct, and partitions are installed between the two motors and the wind wheels to enhance safety and avoid mutual influence between the wind wheels.

[0052] The two motors are controlled by a control unit, which includes a power supply circuit, a parameter memory, a microprocessor and an inverter circuit. The power supply circuit supplies power to each circuit in the control unit; the parameter memory uses an EEPROM with an SPI interface to store system configuration parameters, including constants of the motor model (motor friction coefficient b, rotation inertia constant J, electromagnetic torque constant k t ) and control algorithm parameters (constant gains P and Q), the above control algorithm parameters are determined in advance when the system is established and stored in the EEPROM; the microprocessor (using STM32) receives the motor speed signal fed back by the encoder, and then calculates the current signal instruction of each motor according to the adaptive fault-tolerant controller stored in the microprocessor and sends it to the inverter circuit; the inverter circuit input end receives the current signal instruction from the microprocessor, and the output end is connected to the winding coil of the motor stator assembly to control the motor current.

[0053] In this example, when considering the adaptive fault-tolerant controller stored in the microprocessor: 1) it is able to calculate the current signal command for each motor so that the sum of the speeds of the two motors is equal to the expected speed; 2) when an unknown torque fault occurs in the motor, the calculated current command signal can respond immediately and still ensure that the sum of the speeds of the two motors is equal to the expected speed; 3) the unknown torque fault has an unknown attenuation factor and an unknown fault time; 4) in the event of a motor failure, at least one motor can operate.

[0054] The construction process of the adaptive fault-tolerant controller is as follows:

[0055] (1) Establishing mathematical model:

[0056]

[0057] Formula (1) and Formula (2) are the torque balance formulas of the two BLDC motors, where b is the motor friction coefficient, J is the rotational inertia constant, and k t is the electromagnetic torque constant, ω1 and ω2 are the speeds of the two motors respectively, are the speed acceleration of the two motors, i1 and i2 are the control currents of the two motors, 0≤α1 and α2≤1 are the electromagnetic torque attenuation factors, representing the degree of electromagnetic torque attenuation. When α1, α2=1, it means the motor is working normally; when 0<α1, α2<1, it means the motor is partially failed; when α1, α2=0, it means the motor is completely failed. Because the two motors have the same specifications and the same current signal instructions, we can add formula (1) and formula (2) to get the total speed response equation as follows:

[0058]

[0059] in represents the total speed acceleration of the motor, ω=ω1+ω2 represents the total speed of the motor, α=α1+α2, i=i1=i2.

[0060] In this embodiment, a fault compensation gain parameter is set make In the formula, It is an intermediate variable introduced to facilitate the design. Its mathematical meaning is the current signal command required when the motor is not faulty. Substituting the fault compensation gain parameter into formula (3), the new response equation can be obtained as follows:

[0061]

[0062] in represents the estimation error of λ; where λ represents the attenuation degree of electromagnetic torque of the two motors. When the true value of λ can be accurately estimated, It approaches 0, thus eliminating the electromagnetic torque constant attenuation factor in formula (4) Implement fault compensation.

[0063] An adaptive fault-tolerant controller is established based on the mathematical model: The control currents of the two motors are in Indicates the difference between the actual total speed of the motor and the expected target speed, ω ref represents the expected target speed; the parameter according to Updated in real time.

[0064] In this embodiment, the fault tolerance capability of the adaptive fault-tolerant controller is mainly due to the fault compensation gain parameter In formula (4), parameter λ reflects the motor fault condition, and the adaptive update parameter Can make It approaches to 0, thereby eliminating the influence of motor fault on the controller, so that the designed current signal instruction can still ensure that the total speed of the motor meets the expected speed.

[0065] The system closed-loop signal used in the whole calculation process of the adaptive fault-tolerant controller is only the feedback speed signal ω, and other parameters are measured and stored in the memory when the fan system is established. Therefore, the control algorithm provided by the present invention does not require additional fault detection devices and air flow meters. The experimental verification is as follows:

[0066] Assuming the expected speed is 500 rad / s, the electromagnetic torque constant of the motor model used is k t =0.05, the friction coefficient is b=0.01, and the moment of inertia is J=0.01. In order to better verify the performance of the adaptive fault-tolerant controller, four fault conditions were set at the 5th, 10th, 15th, and 20th seconds in the experiment:

[0067] 1) One motor fails by 20% (i.e. the attenuation factor is 0.8), and the other motor works normally;

[0068] 2) One motor fails completely, while the other motor works normally;

[0069] 3) One motor fails by 20% and the other motor fails by 30%;

[0070] 4) One motor fails completely and the other motor fails 30%.

[0071] In the experiment, the controller gain is set to P = 1, Q = 0.000001. The simulation results are shown in Figure 2 , Figure 3 , Figure 4 As shown by Figure 2 and Figure 3 It can be seen that whenever a fault occurs, the total speed of the motor changes due to the sudden fault, and then quickly tracks to the expected speed, proving that the control method provided by the present invention can ensure the stability of the fan system speed, and thus ensure the stable output of air volume.

[0072] Depend on Figure 4It can be seen that at the 5th second of the experiment, one motor failed by 20%, and the speed dropped. At the same time, the other motor working normally increased the speed accordingly under the action of the controller to compensate for the speed drop caused by the failure; at the 10th second of the experiment, one motor failed completely, and the speed dropped to 0rad / s. The other motor working normally immediately increased the speed to 500rad / s, ensuring that the total speed output met expectations; at the 15th second of the experiment, both motors failed partially. At this time, the two motors allocated the speed according to the degree of failure, and the total speed was still maintained at 500rad / s; at the 20th second of the experiment, one motor failed completely, and the speed dropped to 0rad / s. The other motor partially failed, and the controller ensured that its speed reached the target speed by increasing the current command signal. Therefore, the controller provided by the present invention can adapt to a variety of motor failure conditions.

[0073] Figure 5 This is the fitting curve of motor speed and air volume under the same static pressure in the fan system. It can be seen that the air volume is proportional to the motor speed, which means that as long as the motor speed can be stably output, the system air volume can be stably output.

[0074] The present invention can dynamically adjust the fault compensation gain and drive current according to the feedback information and real-time changes of the motor speed to adapt to the performance changes of the motor. This adaptive control enables the system to maintain a stable air volume output when facing motor load fluctuations or changes in environmental conditions, thereby enhancing the system's coping ability and reliability. By utilizing the existing motor speed feedback and microprocessor calculation compensation mechanism, the system does not need to add additional sensors or detection modules, making full use of existing hardware resources. This not only reduces system costs, but also reduces hardware failure rates and maintenance frequency, improving the economy and sustainability of the system.

[0075] In the event of a motor failure or performance degradation, the fault compensation gain calculation formula and dynamic adjustment strategy of the present invention can accurately compensate for changes in air volume, thereby ensuring that the system air volume is always maintained at a predetermined target value. This high-precision control ensures that in the event of a fault, the air volume fluctuation of the fan system is minimal and the overall performance of the system is not significantly affected. The fault-tolerant control method of the present invention is not only applicable to conventional fan systems, but can also be widely used in various complex scenarios that require constant air volume, such as industrial ventilation, air conditioning systems, climate control and other fields. In the face of motor aging, load changes or other unexpected factors, the system can adaptively adjust to ensure that the air volume remains stable.

[0076] In summary, the multi-motor fan system constant air volume control method with fault-tolerant characteristics of the present invention, through an innovative adaptive fault-tolerant control algorithm, enables the system to still operate stably in the case of motor failure or performance degradation, and has the advantages of high reliability, low cost, and easy maintenance. This makes the present invention have broad application prospects and economic benefits in industry and other fields that require constant air volume.

[0077] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for controlling constant air volume of a multi-motor fan system with fault tolerance, characterized in that: The method comprises the following steps: The multi-motor fan system includes at least two BLDC motors, each of which drives a wind wheel through current closed-loop control, and multiple wind wheels are installed in parallel in the air duct; The control current of all motors is controlled by the same microprocessor. The motor feeds back the speed signal to the microprocessor in real time through the encoder. The microprocessor is used to receive the speed signal, calculate the speed error of each motor and send the current signal instruction. The microprocessor adjusts the driving current signal of the motor according to the speed error, adjusts the motor speed, and controls the total air volume of the multi-motor fan system within a predetermined target value range.

2. The method for controlling constant air volume of a multi-motor fan system with fault tolerance characteristics as claimed in claim 1, characterized in that: The BLDC motors included in the multi-motor fan system have the same specifications. When a motor fails, the control current of the motor is automatically adjusted by the microprocessor so that the total speed of the motor reaches the target total speed.

3. The method for controlling constant air volume of a multi-motor fan system with fault tolerance characteristics as claimed in claim 2, characterized in that: The total motor speed is the sum of the motor speeds included in the motor fan system; the speed error is the difference between the real-time total motor speed and the target total speed.

4. The method for controlling constant air volume of a multi-motor fan system with fault tolerance characteristics as claimed in claim 1, characterized in that: The microprocessor is equipped with an adaptive fault-tolerant controller, which calculates a fault compensation gain based on real-time rotation speed feedback information and rotation speed error.

5. The method for controlling constant air volume of a multi-motor fan system with fault tolerance characteristics as claimed in claim 4, characterized in that: The calculation formula of fault compensation gain is: Where i is the current signal command, is the fault compensation gain, b is the motor friction coefficient, J is the moment of inertia constant, k t is the electromagnetic torque constant, P is the positive gain constant, ω and They are the total motor speed and speed error respectively.

6. The method for controlling constant air volume of a multi-motor fan system with fault tolerance characteristics as claimed in claim 4, characterized in that: The current signal instruction i is calculated in real time by an adaptive fault-tolerant controller stored inside the microprocessor, and the current signal instructions of multiple motors all come from the same microprocessor.

7. The method for controlling constant air volume of a multi-motor fan system with fault tolerance characteristics as claimed in claim 1, characterized in that: The microprocessor acquires and monitors the speed information of each motor in real time to determine whether the motor has a fault.

8. The method for controlling constant air volume of a multi-motor fan system with fault tolerance characteristics as claimed in claim 7, characterized in that: The microprocessor obtains speed information including speed error, motor rotational inertia, and electromagnetic torque constant parameters fed back by the motor in real time. When the actual speed deviates from the target speed, it updates and adjusts the fault compensation gain in real time to compensate for motor failure or performance degradation.

9. The method for controlling constant air volume of a multi-motor fan system with fault tolerance characteristics as claimed in claim 8, characterized in that: When the fault compensation gain is updated and adjusted in real time, the fault compensation gain according to Real-time update; where Q is the positive gain constant; is the fault compensation gain The derivative of The law of change.

10. The method for controlling constant air volume of a multi-motor fan system with fault tolerance characteristics as claimed in claim 7, characterized in that: When the motor speed deviates from the target speed, the microprocessor determines that the motor has failed. Motor failure includes partial failure and complete failure. The failure type of the motor failure is determined by the electromagnetic torque constant attenuation factor α: the attenuation factor 0<α<1 represents partial failure of the motor; Attenuation factor α = 0 represents complete motor failure; The attenuation factor α=1 represents normal operation of the motor.

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