Electronic temperature protection control method for direct current brushless motor

Abstract

The invention provides an electronic temperature protection control method for a direct current brushless motor, and relates to the technical field of motor control, and the method comprises the steps: temperature sampling: employing a controller or a motor internal sensor and a winding resistor to estimate and collect a temperature signal in real time; temperature filtering: eliminating noise interference by adopting mean value or Kalman filtering; temperature comparison: comparing the filtered temperature value with a preset multi-level threshold value (from one level to three levels); and protection control is carried out, and measures such as power reduction, current limiting or driving signal closing are taken according to the threshold exceeding degree. Through multi-point sampling, heat conduction installation, dynamic filtering parameter adaptation and threshold setting based on the insulation grade, the temperature monitoring precision and response speed are improved, the problems of response lag and cost of traditional hardware protection are avoided, dynamic and precise temperature protection of the motor is achieved in combination with a thermal response time constant and temperature change rate pre-judgment mechanism, and the reliability of the motor is improved. The service life of equipment is effectively prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control technology, and in particular to an electronic temperature protection control method for a brushless DC motor. Background Art

[0002] Amid the widespread use of brushless DC motors, controller and motor damage caused by overheating remains a persistent pain point in the industry. Traditional temperature protection technologies primarily rely on hardware protection measures, such as temperature switches. These solutions suffer from significant drawbacks: the mechanical response mechanism of temperature switches results in significant action delays, making it difficult to promptly capture rapid temperature rises within the motor. This lag in protection action can accelerate aging of the motor's insulation, especially under transient conditions such as sudden load increases. Hardware switches generally have low temperature measurement accuracy, providing only a switching signal that cannot accurately reflect the actual distribution of the motor's internal temperature field, easily leading to false operation or protection failure. Furthermore, independently configured temperature switches increase the hardware cost of the motor system and require additional circuit design, hindering the need for miniaturization and cost-effectiveness.

[0003] With the development of electronic control technology, temperature protection strategies based on software algorithms have gradually been applied, but existing solutions still have deep technical bottlenecks. In the temperature sampling process, most electronic control solutions use single-point temperature measurement and the sensor is not installed properly. The sensor is not tightly attached to the heat core through thermal conductive material, resulting in the temperature measurement signal seriously lagging behind the actual temperature change. At the same time, the non-uniformity of the temperature field inside the motor is ignored, and the single-point data cannot represent the overall temperature condition. When processing temperature signals, the fixed-parameter filtering algorithm is difficult to adapt to the thermal inertia differences of motors of different power. Small-power motors are prone to losing high-frequency temperature rise information due to excessive filtering, while high-power motors are prone to noise interference due to insufficient filtering. The temperature threshold setting generally relies on empirical values, and is not theoretically designed in combination with the motor insulation level and safety margin, making it impossible to achieve a dynamic balance between safety and operating efficiency.

[0004] More critically, existing electronic protection strategies lack a mechanism to predict temperature trends. They trigger protection based solely on the current temperature value, without incorporating a thermal response time constant to correct for conduction delays or monitoring the rate of temperature change to predict potential overheating risks. This can easily lead to delayed protection in extreme operating conditions, such as motor stalls. Furthermore, the adjustment range of multi-level protection measures lacks a dynamic adaptive mechanism, and the restart logic after shutdown fails to consider the stability of the thermal recovery process. This can cause frequent system starts and stops, further reducing equipment reliability. Summary of the Invention

[0005] In order to solve the technical problems in the prior art such as slow response, low precision and high cost of traditional hardware protection, as well as non-standard sampling methods, fixed filtering parameters, lack of theoretical basis for threshold setting, failure to predict temperature change trends, single protection adjustment mechanism and imperfect restart logic in electronic control solutions, the present invention provides a method for electronic temperature protection control of a brushless DC motor.

[0006] The technical solutions provided by the present invention are as follows:

[0007] The present invention provides a method for controlling electronic temperature protection of a brushless DC motor, comprising:

[0008] S1. Temperature sampling: Use the sensor on the controller, the temperature sensor embedded in the motor, or estimate the motor temperature through the motor winding resistance to collect the temperature signals of the controller and the motor in real time. The sensor includes NTC, PTC, thermistor or thermocouple.

[0009] S2, temperature filtering: filter the collected controller and motor temperature signals to eliminate noise interference and obtain accurate temperature values;

[0010] S3. Temperature comparison: Compare the filtered temperature value with a preset temperature threshold to determine whether the controller or motor is overheated. The preset temperature threshold is set to a multi-level threshold according to the actual application scenario and safety requirements;

[0011] S4, protection control: When the temperature of the controller or motor exceeds the preset temperature threshold, corresponding protection measures are taken, including reducing the motor power, reducing the motor speed, limiting the motor current or turning off the motor drive signal.

[0012] Furthermore, the temperature sampling step adopts one of the following three methods:

[0013] Method 1: Use the temperature sensor embedded in the motor to directly measure the internal temperature of the motor;

[0014] Method 2: By measuring the resistance of the motor winding, according to the relationship between the resistance of the motor winding and the temperature

[0015] R t =R0(1+αΔT)

[0016] Estimate the internal temperature of the motor, where R t is the winding resistance value at the current temperature, R0 is the winding resistance value at the reference temperature T0, α is the resistance temperature coefficient of the winding material, and ΔT is the difference between the current temperature and the reference temperature;

[0017] Method 3: Measure the controller temperature and motor winding current, and compare them with the preset temperature threshold through an algorithm.

[0018] Furthermore, the temperature filtering step uses a digital filtering algorithm to process the temperature signal, and the digital filtering algorithm includes mean filtering or Kalman filtering.

[0019] Furthermore, the preset temperature threshold includes three levels of thresholds:

[0020] Level 1 temperature threshold: When the temperature exceeds the level 1 threshold, the motor power or speed is reduced to slow down the temperature rise;

[0021] Secondary temperature threshold: When the temperature exceeds the secondary threshold, the motor current is limited to prevent overheating and damage;

[0022] Level 3 temperature threshold: When the temperature exceeds the level 3 threshold, the motor drive signal is turned off and the machine is forced to stop.

[0023] Furthermore, in the protection control step:

[0024] When the temperature exceeds the first level threshold, the motor power is reduced to 80% of the rated power or the speed is reduced to 90%;

[0025] When the temperature exceeds the secondary threshold, the motor current is limited to 70% of the rated current;

[0026] When the temperature exceeds the third threshold, the motor drive signal is turned off.

[0027] Furthermore, the temperature safety margin coefficient K is introduced into the temperature comparison step. t , through the formula

[0028] T margin =T threshold ×K t

[0029] Calculate the actual temperature threshold for triggering protection, where T threshold is the theoretical safety temperature threshold, K t The value range is 0.8-0.95.

[0030] Furthermore, the thermal response time constant τ is introduced into the temperature comparison step, and the formula

[0031]

[0032] Calculation, where C is the equivalent heat capacity of the motor system, R th is the thermal resistance, and P is the average power consumption, which is used to correct the response delay compensation.

[0033] Furthermore, the power adjustment range of the power reduction operation mode is calculated by the formula

[0034]

[0035] Calculate, where P nom is the rated power, T current is the current temperature, T1 is the first level threshold, T2 is the second level threshold, K p is the power adjustment coefficient, and its value range is 0.15-0.4.

[0036] Furthermore, the temperature change rate is calculated in the temperature comparison step:

[0037] The temperature change rate is based on the formula

[0038]

[0039] When the rate of change exceeds the preset threshold, the next level of protection is triggered in advance, where T previous is the temperature value of the previous sampling period, and Δt is the sampling period.

[0040] Furthermore, after the shutdown protection is triggered, the conditions for restarting the motor are:

[0041] The temperature drops below the first threshold T1 and lasts longer than

[0042]

[0043] K is the restart temperature recovery coefficient, which ranges from 0.3 to 0.6.

[0044] The beneficial effects brought about by the technical solution provided by the present invention include at least:

[0045] (1) In the present invention, by adopting multi-point temperature sampling combined with a tightly fitting installation method of thermal grease, and coordinating the mean filter and Kalman filter algorithm that can dynamically adjust the parameters according to the motor power, the acquisition accuracy and real-time performance of the temperature signal are significantly improved, and the problems of temperature measurement lag and signal distortion in the traditional solution are effectively solved, thereby realizing accurate monitoring of the motor temperature.

[0046] (2) In the present invention, with the help of a multi-level temperature threshold system based on the motor insulation level, and the introduction of a temperature safety margin coefficient for dynamic correction, the protection threshold can not only meet the safety requirements of different insulation materials such as F level and H level, but also avoid excessive protection affecting the operating efficiency, fundamentally solving the problem of imbalance between safety and efficiency caused by the empirical threshold setting in the prior art.

[0047] (3) In the present invention, by introducing a thermal response time constant to correct the protection delay, combining the temperature change rate calculation to realize the temperature rise trend prediction, and coordinating the power reduction strategy dynamically adjusted according to the temperature deviation and the restart logic based on the thermal recovery characteristics, a full-process dynamic protection mechanism is constructed, which effectively solves the problems of protection action lag, false triggering and insufficient system stability in traditional solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0049] Figure 1 A schematic flow chart of a method for controlling electronic temperature protection of a brushless DC motor provided by an embodiment of the present invention;

[0050] Figure 2 A schematic diagram of a flow chart of directly measuring temperature using a sensor in a method for electronic temperature protection and control of a brushless DC motor provided by an embodiment of the present invention;

[0051] Figure 3 A schematic diagram of a flow chart of estimating temperature by winding resistance in a method for electronic temperature protection and control of a brushless DC motor provided by an embodiment of the present invention;

[0052] Figure 4 A schematic diagram of a flow chart of using a controller plus current algorithm to sample temperature in a method for electronic temperature protection and control of a brushless DC motor provided by an embodiment of the present invention;

[0053] Figure 5 The present invention provides a flow chart of the overall logic framework of temperature protection in a method for controlling electronic temperature protection of a brushless DC motor. DETAILED DESCRIPTION

[0054] The technical solution of the present invention is described below in conjunction with the accompanying drawings.

[0055] In the embodiments of the present invention, words such as "exemplarily" and "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as an "exemplary" in the present invention should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of the word "exemplary" is intended to present concepts in a concrete manner. Furthermore, in the embodiments of the present invention, "and / or" can mean both or either of the two.

[0056] In the embodiments of the present invention, the terms "image" and "picture" may be used interchangeably. It should be noted that, when the distinction between them is not emphasized, their intended meanings are the same. The terms "of," "corresponding," and "corresponding" may be used interchangeably. It should be noted that, when the distinction between them is not emphasized, their intended meanings are the same.

[0057] In the embodiments of the present invention, sometimes a subscript such as W1 may be mistakenly written as a non-subscript form such as W1. When the difference is not emphasized, the meanings to be expressed are the same.

[0058] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0059] Reference Manual Figure 1 , shows a flow chart of a DC brushless motor electronic temperature protection control method provided by an embodiment of the present invention.

[0060] An embodiment of the present invention provides a method for controlling electronic temperature protection of a brushless DC motor. The processing flow may include the following steps:

[0061] First, temperature sampling is performed, using sensors such as the Negative Temperature Coefficient (NTC), Positive Temperature Coefficient (PTC), thermistors, thermocouples, etc. on the controller, or temperature sensors embedded in the motor, or the motor winding resistance to estimate the motor temperature.

[0062] like Figure 2 Specifically, if a temperature sensor embedded inside the motor is used, a thermistor or thermocouple can be installed near the stator winding of the motor to directly measure the internal temperature of the motor.

[0063] Specifically, three NTC thermistors are embedded in the ends of the motor's stator windings, tightly secured with thermal grease (thickness ≤ 0.1mm). The sampling points are spaced ≥ 5cm apart and number at least three to obtain the average temperature field. The sensor probe must be fully embedded in the winding gap to eliminate air barriers, allowing for real-time acquisition of the motor's internal temperature signal and addressing the lag associated with single-point temperature measurement in existing technologies.

[0064] In one possible implementation, Figure 3 As shown in the figure, winding resistance measurement needs to be performed when the motor is cold (25℃±1℃) using the four-wire method to calibrate the reference resistance R0. When measuring in the hot state, it must be completed within 50ms after shutdown to reduce the impact of temperature decay on measurement accuracy.

[0065] Furthermore, if the winding resistance is used for estimation, the winding resistance value R at the current temperature must be measured first. t , then according to the formula R tIt is calculated as =R0(1+αΔT), where R0 is the winding resistance value at the reference temperature T0, α is the resistance temperature coefficient of the winding material (the temperature coefficient of the copper winding is 0.004 / °C), and ΔT is the difference between the current temperature and the reference temperature. The four-wire connection method eliminates the lead resistance error (≤0.1%), solves the problem of measurement distortion of the traditional two-wire method, and is applicable to the closed motor scenario where sensors cannot be installed.

[0066] If the third method is adopted, such as Figure 4 shown, it is necessary to measure the controller temperature value and the motor winding current value simultaneously, and compare them with the preset temperature threshold through a preset algorithm. The sampling frequency of the temperature needs to meet the real-time requirement to ensure timely acquisition of the temperature signal.

[0067] Specifically, the winding current is collected by the ACS758 Hall current sensor, and the controller temperature is obtained in real time by cooperating with the temperature measurement module of the STM32 controller, and then input into the preset algorithm to be compared with the multi-level temperature threshold. This method does not require additional sensors, indirectly estimates the motor temperature rise through the current-temperature mapping relationship, and the sampling frequency can reach 2.4MSPS, meeting the high-frequency transient temperature measurement requirements.

[0068] After completing the temperature sampling, temperature filtering is performed on the collected controller and motor temperature signals. Digital filtering algorithms such as mean filtering or Kalman filtering can be used. Taking mean filtering as an example, the temperature values of continuous n sampling points can be selected, and their average value is calculated as the filtered temperature value. The value of n can be determined according to the actual noise level; if Kalman filtering is adopted, a state space model of the motor system needs to be established, and the temperature state is optimally estimated through the prediction and update steps to suppress high-frequency noise and low-frequency drift and improve the accuracy of the temperature signal.

[0069] Furthermore, in the temperature filtering step, the sampling points n of mean filtering need to be determined according to the motor power: for motors with a rated power ≤1kW, n is taken as 8 - 16 to suppress switching noise; for motors with a power >10kW, due to large thermal inertia, n is taken as 32 - 64 to effectively smooth the temperature fluctuation. In actual applications, the value of n can be adjusted by observing the fluctuation amplitude of the temperature curve. When the fluctuation amplitude exceeds 0.5°C, increase n until the fluctuation ≤0.3°C to ensure the filtering effect. For Kalman filtering, the process noise covariance matrix Q needs to be set according to the motor thermal response time constant τ. For example, when τ = 100s, Q can be set as to balance the filtering accuracy and response speed and avoid over-filtering or noise residue.

[0070] Then, temperature comparison is carried out, and the filtered temperature value is dynamically compared with the preset set of temperature thresholds. The preset set of temperature thresholds includes the first-level temperature threshold T1, the second-level temperature threshold T2, and the third-level temperature threshold T3, and T1 < T2 < T3. When setting the thresholds, a temperature safety margin coefficient K is introduced t, through the formula

[0071] T margin =T threshold ×K t

[0072] Calculate the temperature safety margin, where T threshold is the theoretical safety temperature threshold of the motor system, K t The value range is 0.8-0.95, and the actual temperature threshold for triggering protection is T threshold -K t ×T threshold .

[0073] Furthermore, when the temperature threshold is preset, the theoretical safety temperature threshold T threshold It should be determined according to the insulation grade of the motor: T for F-class insulation (temperature resistance 155℃) threshold Take 124℃ and keep 20% safety margin; for H-class insulation (temperature resistance 180℃), take 135℃, and the temperature safety margin coefficient K t Initially set to 0.85, debug until the trigger temperature deviation is ≤3%. This setting method is necessary for threshold setting. Failure to do so will result in no standard for protection threshold setting, which may cause insulation damage or frequent protection.

[0074] At the same time, the thermal response time constant τ is introduced, which is calculated as follows:

[0075]

[0076] Where C is the equivalent thermal capacity of the motor system, R th is the thermal resistance of the motor system, P is the average power consumption of the motor during operation, and τ is used to correct the response delay compensation during the temperature comparison process. During the comparison process, the temperature change rate must also be calculated according to the formula

[0077]

[0078] Evaluate the temperature rise rate, where T previous is the temperature value of the previous sampling period, Δt is the sampling period, and when the rate of change exceeds the preset rate threshold, the next level of protection measures is triggered in advance.

[0079] When the controller or motor temperature exceeds the preset temperature threshold, the protection control steps are executed. Figure 5As shown, the filtered temperature value is first monitored, the temperature change rate is calculated, and the thermal response time constant is read. A multi-level threshold judgment is then performed, and protective measures such as shutdown, current limiting, and power reduction are implemented based on the temperature exceeding different thresholds. Finally, the restart condition after shutdown is explained: the temperature must drop below the first threshold for a duration exceeding the delay calculated from the thermal response time constant and the restart temperature recovery coefficient. The figure also demonstrates dynamic correction mechanisms such as temperature safety margin calculation and early protection triggering, achieving more precise temperature protection through the triple judgment conditions.

[0080] Specifically, if the temperature exceeds the first-level threshold T1, the power reduction operation mode is triggered and the motor power is adjusted to P1% of the rated power (P1∈[60,85]). The specific adjustment range is determined by the formula

[0081]

[0082] Calculate, where P now is the rated power of the motor, T current is the current effective temperature, K p is the power adjustment coefficient (range 0.15-0.4).

[0083] Furthermore, in the protection control, power reduction is achieved by modifying the PWM duty cycle, keeping the 16kHz frequency unchanged; current limiting adopts Hall current sensor sampling, and the PID parameter is initially set to K p =0.5~1.0, T i =50~100ms, T d = 5 to 10 ms. This hardware implementation is necessary to implement protection measures. Lack of this will result in abnormal power regulation or current limit deviation exceeding ±10% of the rated current.

[0084] If the secondary threshold T2 is exceeded, the current limiting mode is triggered, limiting the motor current to I1% of the rated current (I1∈[50,75]); if the tertiary threshold T3 is exceeded, the shutdown protection mode is triggered, cutting off the motor drive signal. After the shutdown protection is triggered, the condition for restarting the motor is that the effective temperature signal drops below the primary threshold T1 and the duration exceeds the restart delay time.

[0085]

[0086] where K r is the restart temperature recovery coefficient (range 0.3-0.6).

[0087] During the entire control process, the controller is responsible for collecting and processing temperature signals, performing filtering, comparison, and temperature change rate calculations; the power regulation module performs graded control on the motor operating parameters based on the comparison results. The sampling frequency f of the temperature sensitive element must meet

[0088]

[0089] where τ s The minimum thermal time constant of the motor system is used to ensure the validity of the sampling signal. When implementing, it is necessary to reasonably set the values ​​of various parameters according to the specific model and application scenario of the motor, such as the model selection of the NTC (Negative Temperature Coefficient) sensor, the thermal resistance R th The actual measured value of the temperature and the calculation basis of the equivalent heat capacity C are used to ensure the accuracy and effectiveness of the electronic temperature protection control method. The controller can adopt a hardware architecture with an integrated microprocessor.

[0090] Furthermore, during parameter tuning, the thermal response time constant τ must be determined through steady-state thermal testing, and after tuning is complete, at least three temperature-rise cycle tests must be performed. This tuning process is essential for verifying the reliability of the solution; without it, the repeatability and stability of the protection strategy cannot be ensured.

[0091] Real-time processing of temperature signals is achieved through a preset program algorithm. For example, the analog signal output by the sensor is sampled by the ADC module of the microprocessor, and the mean filter or Kalman filter algorithm is executed by the built-in digital signal processing unit. The temperature threshold comparison and change rate calculation are completed by the logic operation unit, and finally the action of the power regulation module is controlled through the PWM (Pulse Width Modulation) output port.

[0092] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0093] (1) In the present invention, by adopting multi-point temperature sampling combined with a tightly fitting installation method of thermal grease, and coordinating the mean filter and Kalman filter algorithm that can dynamically adjust the parameters according to the motor power, the acquisition accuracy and real-time performance of the temperature signal are significantly improved, and the problems of temperature measurement lag and signal distortion in the traditional solution are effectively solved, thereby realizing accurate monitoring of the motor temperature.

[0094] (2) In the present invention, with the help of a multi-level temperature threshold system based on the motor insulation level, and the introduction of a temperature safety margin coefficient for dynamic correction, the protection threshold can not only meet the safety requirements of different insulation materials such as F level and H level, but also avoid excessive protection affecting the operating efficiency, fundamentally solving the problem of imbalance between safety and efficiency caused by the empirical threshold setting in the prior art.

[0095] (3) In the present invention, by introducing a thermal response time constant to correct the protection delay, combining the temperature change rate calculation to realize the temperature rise trend prediction, and coordinating the power reduction strategy dynamically adjusted according to the temperature deviation and the restart logic based on the thermal recovery characteristics, a full-process dynamic protection mechanism is constructed, which effectively solves the problems of protection action lag, false triggering and insufficient system stability in traditional solutions.

[0096] The above content is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

[0097] There are a few points to note:

[0098] (1) The drawings of the embodiments of the present invention only relate to the structures related to the embodiments of the present invention. Other structures may refer to conventional designs.

[0099] (2) For the sake of clarity, the thickness of layers or regions in the drawings used to describe the embodiments of the present invention are exaggerated or reduced, that is, these drawings are not drawn to scale. It is understood that when an element such as a layer, film, region, or substrate is referred to as being "on" or "under" another element, the element may be "directly" "on" or "under" the other element or intervening elements may be present.

[0100] (3) In the absence of conflict, the embodiments of the present invention and the features therein may be combined with each other to form new embodiments.

[0101] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for controlling electronic temperature protection of a brushless DC motor, characterized in that: include: S1. Temperature sampling: Use the sensor on the controller, the temperature sensor embedded in the motor, or estimate the motor temperature through the motor winding resistance to collect the temperature signals of the controller and the motor in real time. The sensor includes NTC, PTC, thermistor or thermocouple. S2, temperature filtering: filter the collected controller and motor temperature signals to eliminate noise interference and obtain accurate temperature values; S3. Temperature comparison: Compare the filtered temperature value with a preset temperature threshold to determine whether the controller or motor is overheated. The preset temperature threshold is set to a multi-level threshold according to the actual application scenario and safety requirements; S4, protection control: When the temperature of the controller or motor exceeds the preset temperature threshold, corresponding protection measures are taken, including reducing the motor power, reducing the motor speed, limiting the motor current or turning off the motor drive signal.

2. A brushless DC motor electronic temperature protection control method according to claim 1, characterized in that: The temperature sampling step adopts one of the following three methods: Method 1: Use the temperature sensor embedded in the motor to directly measure the internal temperature of the motor; Method 2: By measuring the resistance value of the motor winding, according to the relationship between the motor winding resistance and temperature R t =R0(1+αΔT) Estimate the internal temperature of the motor, where R t is the winding resistance value at the current temperature, R0 is the winding resistance value at the reference temperature T0, α is the resistance temperature coefficient of the winding material, and ΔT is the difference between the current temperature and the reference temperature; Method 3: Measure the controller temperature and motor winding current, and compare them with the preset temperature threshold through an algorithm.

3. The electronic temperature protection control method for a brushless DC motor according to claim 1, characterized in that: include: The temperature filtering step uses a digital filtering algorithm to process the temperature signal, and the digital filtering algorithm includes mean filtering or Kalman filtering.

4. The electronic temperature protection control method for a brushless DC motor according to claim 1, characterized in that: The preset temperature threshold includes three levels of thresholds: Level 1 temperature threshold: When the temperature exceeds the level 1 threshold, the motor power or speed is reduced to slow down the temperature rise; Secondary temperature threshold: When the temperature exceeds the secondary threshold, the motor current is limited to prevent overheating and damage; Level 3 temperature threshold: When the temperature exceeds the level 3 threshold, the motor drive signal is turned off and the machine is forced to stop.

5. The electronic temperature protection control method for a brushless DC motor according to claim 4, characterized in that: In the protection control step: When the temperature exceeds the first level threshold, the motor power is reduced to 80% of the rated power or the speed is reduced to 90%; When the temperature exceeds the secondary threshold, the motor current is limited to 70% of the rated current; When the temperature exceeds the third threshold, the motor drive signal is turned off.

6. The electronic temperature protection control method for a brushless DC motor according to claim 1, characterized in that: include: The temperature safety margin coefficient K is introduced into the temperature comparison step. t , through the formula T margin =T threshold ×K t Calculate the actual temperature threshold for triggering protection, where T threshold is the theoretical safety temperature threshold, K t The value range is 0.8-0.

95.

7. The electronic temperature protection control method for a brushless DC motor according to claim 1, characterized in that: include: The thermal response time constant τ is introduced into the temperature comparison step, and is expressed by the formula Calculation, where C is the equivalent heat capacity of the motor system, R th is the thermal resistance, and P is the average power consumption, which is used to correct the response delay compensation.

8. The electronic temperature protection control method for a brushless DC motor according to claim 4, characterized in that: include: The power adjustment range of the power reduction operation mode is calculated by the formula Calculate, where P nom is the rated power, T current is the current temperature, T1 is the first level threshold, T2 is the second level threshold, K p It is the power adjustment coefficient, and its value range is 0.15-0.

4.

9. The electronic temperature protection control method for a brushless DC motor according to claim 1, characterized in that: Calculate the temperature change rate in the temperature comparison step: The temperature change rate is based on the formula When the rate of change exceeds the preset threshold, the next level of protection is triggered in advance, where T previous is the temperature value of the previous sampling period, and Δt is the sampling period.

10. The electronic temperature protection control method for a brushless DC motor according to claim 4, characterized in that: After the shutdown protection is triggered, the conditions for restarting the motor are: The temperature drops below the first threshold T1 and lasts longer than where K r It is the restart temperature recovery coefficient, and its value range is 0.3-0.6.

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