Motor control method and device, motor driving circuit and electric equipment

Abstract

This application provides a motor control method, device, motor drive circuit, and electrical equipment. The method includes: determining whether the number of times the motor's overcurrent limiting frequency reduction is triggered within a first preset cycle is less than or equal to a first threshold; if the determination result is yes, then controlling the motor's operating frequency according to the motor's set operating program; if the determination result is no, then adjusting the motor's operating frequency according to the number of times the overcurrent limiting frequency reduction is triggered. This application avoids repeated frequency fluctuations in the motor, ensuring stable motor output power, improving production efficiency and energy efficiency, and enabling energy-saving effects for the motor and electrical equipment using the motor, such as inverter air conditioners, inverter refrigerators, and inverter washing machines. It also reduces the mechanical stress on the motor windings and bearings, slowing down aging.

Description

Technical Field

[0001] This application relates to the field of electronic power technology, and in particular to a motor control method, device, motor drive circuit and electrical equipment. Background Technology

[0002] In fields such as industrial automation, electric vehicles, intelligent manufacturing, and home appliances, motors are core power components, and their operational reliability and efficiency directly affect the overall system performance and energy consumption. With the rapid development of motor control technology, variable frequency drive systems have become the mainstream solution. One of their core functions is overload protection through real-time current monitoring, preventing motor damage due to current overload. In existing technologies, typical motor control systems (such as IGBT-based inverters or DSP controllers) generally employ a fixed threshold current limiting mechanism: when the motor current exceeds a preset current threshold, the system immediately triggers a "frequency reduction" operation, limiting or reducing the motor's operating frequency to reduce the load, which may be accompanied by an alarm or shutdown. While this design effectively improved motor safety in early applications, it also has significant drawbacks.

[0003] The current static protection strategy is based on triggering frequency reduction based on a single overcurrent event, without considering the frequency and cumulative nature of the triggering event. When the motor current fluctuates frequently, the overcurrent frequency reduction will be triggered frequently, which will cause the motor to repeatedly increase and decrease the frequency, resulting in sudden changes in the motor output power, reduced production efficiency and energy efficiency. At the same time, it will aggravate the mechanical stress of the motor windings and bearings and accelerate aging. Summary of the Invention

[0004] This application provides a motor control method, device, motor drive circuit, and electrical equipment to solve the problem in the prior art that frequent current fluctuations in the motor cause frequent triggering of overcurrent limiting frequency reduction, which in turn causes the motor to repeatedly increase and decrease frequency.

[0005] In a first aspect, this application provides a motor control method, the method comprising: Determine whether the number of times the motor's overcurrent limiting frequency reduction is triggered within the first preset cycle is less than or equal to the first threshold. If the judgment result is yes, then the operating frequency of the motor is controlled according to the motor's set operating program; If the judgment result is negative, the operating frequency of the motor is adjusted according to the number of times the overcurrent limiting frequency reduction is triggered.

[0006] In one possible implementation, adjusting the motor's operating frequency based on the number of times the overcurrent limiting frequency reduction is triggered includes: Determine the range in which the overcurrent limiting frequency reduction trigger count falls; If the number of times the overcurrent limiting frequency reduction is triggered is greater than the first threshold and less than or equal to the second threshold, the motor is controlled to reduce the frequency increase rate; wherein, the greater the number of times the overcurrent limiting frequency reduction is triggered, the lower the frequency increase rate. If the number of times the overcurrent limiting frequency reduction is triggered is greater than the second threshold and less than or equal to the third threshold, then the maximum operating frequency of the motor is reduced. If the number of times the overcurrent limiting frequency reduction is triggered is greater than the third threshold, the motor is controlled to maintain a safe operating frequency; wherein, the operating current of the motor at the safe operating frequency is lower than the current threshold that triggers the overcurrent limiting frequency reduction. The third threshold > the second threshold > the first threshold.

[0007] In one possible implementation, after controlling the maximum operating frequency of the motor to decrease, the method further includes: After the first preset duration, the operating frequency of the motor is controlled according to the set operating program of the motor; Determine whether the conditions for triggering overcurrent limiting frequency reduction are met, and whether the number of times the overcurrent limiting frequency reduction is triggered is greater than a fourth threshold; wherein, the fourth threshold > the third threshold > the second threshold > the first threshold; If the judgment result is yes, then the maximum carrier frequency is calculated based on the maximum junction temperature of the switching transistor in the power factor correction circuit, the case temperature of the switching transistor, and the thermal resistance of the switching transistor, and the carrier frequency of the motor is controlled to increase with the maximum carrier frequency as the upper limit; wherein, the greater the number of times the overcurrent limiting frequency reduction is triggered, the greater the carrier frequency; If the judgment result is negative, a re-judgment is triggered to determine whether the number of times the motor's overcurrent limiting frequency reduction is triggered within the first preset cycle is less than or equal to the first threshold. If the judgment result is positive, the operating frequency of the motor is controlled according to the motor's set operating program. If the judgment result is negative, the operating frequency of the motor is adjusted according to the number of times the overcurrent limiting frequency reduction is triggered.

[0008] In one possible implementation, after controlling the motor to maintain a safe operating frequency, the method further includes: Detect the operating parameters of the motor; Determine whether the operating parameters exhibit abnormal fluctuations; If so, a fault warning message will be displayed.

[0009] In one possible implementation, after controlling the motor to maintain a safe operating frequency, the method further includes: After the second preset duration, the operating frequency of the motor is controlled according to the set operating program of the motor; Determine whether the conditions for triggering overcurrent limiting frequency reduction are met, and whether the number of times the overcurrent limiting frequency reduction is triggered is greater than a fourth threshold; wherein, the fourth threshold > the third threshold > the second threshold > the first threshold; If the judgment result is yes, then the maximum carrier frequency is calculated based on the maximum junction temperature of the switching transistor in the power factor correction circuit, the case temperature of the switching transistor, and the thermal resistance of the switching transistor, and the carrier frequency of the motor is controlled to increase with the maximum carrier frequency as the upper limit; wherein, the greater the number of times the overcurrent limiting frequency reduction is triggered, the greater the carrier frequency; If the judgment result is negative, a re-judgment is triggered to determine whether the number of times the motor's overcurrent limiting frequency reduction is triggered within the first preset cycle is less than or equal to the first threshold. If the judgment result is positive, the operating frequency of the motor is controlled according to the motor's set operating program. If the judgment result is negative, the operating frequency of the motor is adjusted according to the number of times the overcurrent limiting frequency reduction is triggered.

[0010] In one possible implementation, the motor is connected to a power factor correction circuit, which includes an inductor, a switching transistor, and a diode, and also includes a spare inductor. A first terminal of the spare inductor is connected to the inductor, and a second terminal is connected to both the switching transistor and the diode of the power factor correction circuit. The method further includes: Detect the actual operating current value of the motor; Determine whether the difference between the actual operating current value and the current threshold is negative, and whether the absolute value of the difference is greater than a preset threshold. If the judgment result is yes, then the operating frequency of the motor is controlled according to the motor's set operating program; If the determination result is negative, then the backup inductor is connected to the power factor correction circuit.

[0011] In one possible implementation, the method further includes: Obtain the number of times the overcurrent limit frequency reduction is triggered within the second preset period; The current threshold for triggering overcurrent limit frequency reduction is adjusted according to the number of times the overcurrent limit frequency reduction is triggered within the second preset period; wherein, the more times the overcurrent limit frequency reduction is triggered within the second preset period, the lower the current threshold is.

[0012] In one possible implementation, the method further includes: Real-time detection of the actual operating current value of the motor; Determine whether the rate of change of the actual operating current value is greater than the preset rate of change, and whether the number of times the overcurrent limit frequency is reduced is greater than the second threshold. If so, the current threshold is increased and maintained for a third preset duration.

[0013] In one possible implementation, the method further includes: Calculate the average number of triggers within the third preset period to obtain the base frequency; A preset coefficient is calculated based on the current overcurrent limit frequency reduction trigger frequency and the reference frequency; wherein, the preset coefficient = current overcurrent limit frequency reduction trigger frequency / reference frequency; If the preset coefficient is greater than 1, then the first threshold, the second threshold, the third threshold and the fourth threshold are all lowered. If the preset coefficient is equal to 1, then the first threshold, the second threshold, the third threshold, and the fourth threshold are kept unchanged; If the preset coefficient is less than 1, then the first threshold, the second threshold, the third threshold and the fourth threshold are all adjusted upwards.

[0014] Secondly, this application provides a motor control device for use with a motor having a power factor correction circuit, the device comprising: The judgment module is used to determine whether the number of times the motor's overcurrent limiting frequency reduction is triggered within the first preset period is less than or equal to the first threshold. The first control module is used to control the operating frequency of the motor according to the motor's set operating program when the number of overcurrent frequency reduction triggers is less than or equal to a first threshold. The second control module is used to adjust the operating frequency of the motor according to the number of times the overcurrent limiting frequency reduction is triggered when the number of triggers exceeds the first threshold.

[0015] Thirdly, a motor drive circuit is provided, including a power factor correction circuit, wherein the power factor correction circuit includes an inductor, a switching transistor, and a diode, and further includes: A spare inductor, the first end of which is connected to the inductor, and the second end of which is connected to the switching transistor and the diode of the power factor correction circuit, respectively; The first switch is connected in parallel with the backup inductor; The second switch is connected in series with the backup inductor.

[0016] In one possible implementation, the motor drive circuit further includes: A buffer capacitor, the first end of which is connected between the positive output terminal of the rectifier and the inductor, and the second end of which is connected to the negative output terminal of the rectifier; A buffer resistor, the first end of which is connected to the negative output terminal of the rectifier and the second end of the buffer capacitor, and the second end of which is grounded.

[0017] Fourthly, an electrical device is provided, including a motor and the aforementioned motor drive circuit.

[0018] In one possible implementation, the electrical equipment includes at least one of the following: Inverter air conditioners, inverter refrigerators, and inverter washing machines.

[0019] Fifthly, this application provides an electronic device, including: a processor and a memory, wherein the processor is configured to execute a motor control program stored in the memory to implement the above-described motor control method.

[0020] Sixthly, this application provides a storage medium storing one or more programs that can be executed by one or more processors to implement the above-described motor control method.

[0021] Compared with the prior art, the above-mentioned technical solution provided in this application has the following advantages: First, it is determined whether the number of times the overcurrent limiting frequency reduction of the motor is triggered within the first preset cycle is less than or equal to the first threshold. If the number of triggers is less than or equal to the first threshold, it indicates that it is a normal overcurrent trigger. Then, the operating frequency of the motor is controlled according to the motor's set operating program to ensure normal operation of the motor. If frequent current fluctuations cause frequent triggers of the overcurrent limiting frequency reduction, the operating frequency of the motor is adjusted according to the number of triggers of the overcurrent limiting frequency reduction. By increasing the frequency adjustment scheme when the current fluctuates frequently, the frequency of the motor can be avoided from repeatedly rising and falling, so that the output power of the motor is stable, improving production efficiency and energy efficiency. This makes the motor and the electrical equipment using the motor, such as variable frequency air conditioners, variable frequency refrigerators, and variable frequency washing machines, have energy-saving effects. At the same time, it reduces the mechanical stress of the motor windings and bearings and slows down aging. Attached Figure Description

[0022] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0025] Figure 1 A flowchart of a motor control method provided in an embodiment of this application; Figure 2 A flowchart of a motor control method provided in another embodiment of this application; Figure 3 This is a structural diagram of a motor control device according to an embodiment of the present invention; Figure 4 This is a structural diagram of the motor drive circuit provided in an embodiment of this application; Figure 5 This is a structural diagram of a motor drive circuit provided in another embodiment of this application; Figure 6 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0028] Example 1 To address the technical problem in existing technologies where frequent fluctuations in motor current lead to frequent triggering of the overcurrent limit frequency reduction mechanism, resulting in repeated frequency increases and decreases in the motor, this embodiment provides a motor control method. When the number of overcurrent limit frequency reduction triggers is high, the operating frequency of the motor is adjusted according to the number of triggers. This avoids frequent triggering of the overcurrent limit frequency reduction mechanism, thereby preventing repeated frequency increases and decreases in the motor's frequency. This stabilizes the motor's output power, improves production efficiency and energy efficiency, and enables energy-saving effects for the motor and the electrical equipment using it, such as inverter air conditioners, inverter refrigerators, and inverter washing machines. Simultaneously, it reduces the mechanical stress on the motor windings and bearings, slowing down aging.

[0029] Figure 1 This is a flowchart illustrating an embodiment of a motor control method provided in this application. Figure 1 As shown, the method includes the following steps: S101, determine whether the number of times the motor's overcurrent limiting frequency reduction is triggered within the first preset period is less than or equal to the first threshold; if the determination result is yes, then execute step S102; if the determination result is no, then execute step S103.

[0030] Within the first preset period T1 time (e.g., 2 hours), the number of times the motor's overcurrent limit frequency reduction is triggered is obtained. If the number of triggers is less than or equal to the first threshold, it indicates that the overcurrent trigger is normal. If the number of triggers is greater than the first threshold, it indicates that the current fluctuates frequently, causing the overcurrent limit frequency reduction to trigger frequently.

[0031] S102 controls the operating frequency of the motor according to the motor's set operating program.

[0032] If it is a normal overcurrent trigger, the motor is running normally. You only need to control the motor frequency to increase or decrease according to the motor's set operating program to ensure the motor runs normally.

[0033] S103 adjusts the motor's operating frequency based on the number of times the overcurrent limiting frequency reduction is triggered.

[0034] If frequent current fluctuations cause the overcurrent limit frequency reduction to be triggered frequently, the motor's operating frequency needs to be adjusted according to the number of times the overcurrent limit frequency reduction is triggered in order to avoid repeated increases and decreases in the motor frequency.

[0035] The motor control method in this embodiment first determines whether the number of times the motor's overcurrent limiting frequency reduction is triggered within a first preset cycle is less than or equal to a first threshold. If the number of triggers is less than or equal to the first threshold, it indicates a normal overcurrent trigger. Then, the motor's operating frequency is controlled according to the motor's set operating program to ensure normal motor operation. If frequent current fluctuations cause frequent overcurrent limiting frequency reduction triggers, the motor's operating frequency is adjusted according to the number of overcurrent limiting frequency reduction triggers. By increasing the frequency adjustment scheme when the current fluctuates frequently, the motor's frequency can be prevented from repeatedly rising and falling, thus stabilizing the motor's output power, improving production efficiency and energy efficiency, and enabling the motor and the electrical equipment using the motor, such as variable frequency air conditioners, variable frequency refrigerators, and variable frequency washing machines, to have energy-saving effects. At the same time, it reduces the mechanical stress on the motor windings and bearings, slowing down aging.

[0036] Example 2 The more times the overcurrent-limited frequency reduction triggers, the more frequent the current fluctuations, and the stricter the frequency limit for the motor should be. To match the motor frequency control strategy with the number of overcurrent-limited frequency reduction triggers and improve frequency control effectiveness, the motor's operating frequency is adjusted based on the number of overcurrent-limited frequency reduction triggers. This includes: determining the range of overcurrent-limited frequency reduction triggers; if the number of overcurrent-limited frequency reduction triggers is greater than the first threshold and less than or equal to the second threshold, it indicates that although the current fluctuation is abnormal, the frequency is low, and the frequency can continue to increase. The motor's frequency increase rate is then reduced to prevent excessively rapid frequency fluctuations. Among these, overcurrent... The more times the frequency reduction limit is triggered, the lower the frequency increase rate. If the number of times the overcurrent frequency reduction limit is triggered is greater than the second threshold and less than or equal to the third threshold, it indicates that the overcurrent frequency reduction limit is triggered frequently. The maximum operating frequency of the motor is reduced to allow the motor to quickly reach the maximum operating frequency and then maintain it to avoid further frequency increase. If the number of times the overcurrent frequency reduction limit is triggered is greater than the third threshold, it indicates that the overcurrent frequency reduction limit is triggered very frequently. The motor is controlled to maintain a safe operating frequency. At the safe operating frequency, the operating current of the motor is lower than the current threshold that triggers the overcurrent frequency reduction limit, so that the overcurrent frequency reduction limit is no longer triggered.

[0037] If the current fluctuation ends after the maximum operating frequency of the motor is reduced, the motor should be controlled to return to the set operating program as soon as possible to improve the motor's efficiency. If the current fluctuation is still relatively large, or even if the operating current increases further due to the aforementioned frequency increase operation, leading to more frequent overcurrent limit frequency reduction triggering, then new methods are needed, such as increasing the carrier frequency, to control the operating current. Therefore, after the maximum operating frequency of the motor is reduced, the above method also includes: after a first preset time, controlling the motor's operating frequency according to the motor's set operating program; determining whether the overcurrent limit frequency reduction triggering is satisfied, and whether the number of overcurrent limit frequency reduction triggering times is greater than the fourth threshold. If the judgment result is yes, the maximum carrier frequency is calculated based on the maximum junction temperature, the case temperature, and the thermal resistance of the switching transistor in the power factor correction circuit, and the carrier frequency of the motor is increased with the maximum carrier frequency as the upper limit; wherein, the greater the number of overcurrent limiting frequency reduction triggers, the greater the carrier frequency; if the judgment result is no, a re-judgment is triggered to determine whether the number of overcurrent limiting frequency reduction triggers of the motor within the first preset period is less than or equal to the first threshold; if the judgment result is yes, the operating frequency of the motor is controlled according to the motor's set operating program; if the judgment result is no, the operating frequency of the motor is adjusted according to the number of overcurrent limiting frequency reduction triggers.

[0038] Calculating the maximum carrier frequency requires combining thermal and electrical models and involves two steps: Step 1: Derive the maximum allowable power loss from the junction temperature formula. The junction temperature-case temperature formula (the relationship between device case temperature and junction temperature) is a fundamental formula for thermal management, used to calculate the junction temperature of semiconductor switching transistors (such as IGBTs and MOSFETs).

[0039] Junction temperature (unit: °C); : Device case temperature (unit: °C); Total power dissipation (W). : Thermal resistance from junction to case temperature (unit: °C / W); When the junction temperature reaches the maximum allowable value At that time, the corresponding power loss is:

[0040] : Maximum junction temperature as stated in the device datasheet (e.g., the maximum junction temperature of an IGBT is typically 150°C). Device housing temperature (must be measured). Thermal resistance (must be obtained from the device datasheet, e.g., 1.5℃ / W); Step 2: Convert to maximum carrier frequency Power loss Mainly due to switching losses Generation (dominated at high frequencies):

[0041] k: Switching loss coefficient (unit: W / Hz), which needs to be obtained from device data or experiments. k depends on device type, voltage, current, gate drive, etc. Therefore, the maximum carrier frequency is .

[0042] The number of overcurrent limiting frequency reduction triggers serves as a potential fault indicator, yet existing systems do not incorporate it into their control logic. For example, if the number of triggers exceeds a threshold within a short period, it may indicate a problem with internal motor components or drive board devices. However, traditional systems only record events without dynamically adjusting protection strategies, leading to motor burnout and increased annual failure rates. In this application, to identify the fault source causing abnormal current fluctuations as early as possible and to alert the user, the method further includes: detecting the motor's operating parameters; determining whether the operating parameters exhibit abnormal fluctuations; and if so, providing a fault warning.

[0043] If the current fluctuation ends after the motor is kept at a safe operating frequency, the motor should be controlled to return to the set operating program as soon as possible to improve motor efficiency. If the current fluctuation is still relatively large, or even increases further than before the motor was kept at a safe operating frequency, thus causing the overcurrent limit frequency reduction triggering more frequently, then new methods are needed, such as increasing the carrier frequency, to control the operating current and keep the motor at a safe operating frequency. The above method also includes: after a second preset time, controlling the motor's operating frequency according to the motor's set operating program; determining whether the overcurrent limit frequency reduction triggering is satisfied, and whether the number of overcurrent limit frequency reduction triggering times is greater than a fourth threshold; if the determination is... If the result is yes, the maximum carrier frequency is calculated based on the maximum junction temperature of the switching transistor in the power factor correction circuit, the casing temperature of the switching transistor, and the thermal resistance of the switching transistor. The carrier frequency of the motor is then increased with the maximum carrier frequency as the upper limit. The higher the number of overcurrent limiting frequency reduction triggers, the higher the carrier frequency. If the result is no, a re-evaluation is triggered to determine whether the number of overcurrent limiting frequency reduction triggers within the first preset period is less than or equal to the first threshold. If the result is yes, the motor's operating frequency is controlled according to the motor's set operating program. If the result is no, the motor's operating frequency is adjusted according to the number of overcurrent limiting frequency reduction triggers.

[0044] The fourth threshold is greater than the third threshold, which is greater than the second threshold, which is greater than the first threshold.

[0045] The core characteristic of an inductor is its ability to impede changes in current, a phenomenon determined by Lenz's law. When the current increases, the inductor generates an induced electromotive force (EMF) in the opposite direction to the current, attempting to suppress the current increase; when the current decreases, the induced EMF is in the same direction as the current, impeding the current decrease. This characteristic is similar to an "inertial element" in a circuit, preventing current changes from occurring instantaneously, thus creating an impediment to the current. Therefore, if the inductance value in the power factor correction circuit increases, it will suppress the increase in current. To further suppress the increase in the motor's operating current, the method further includes: detecting the actual operating current value of the motor; determining whether the difference between the actual operating current value and the current threshold is negative, and the absolute value of the difference is greater than a preset threshold; that is, the actual operating current value has a certain gap from the current threshold. If the determination result is yes, then the motor's operating frequency is controlled according to the motor's set operating program; if the determination result is no, then a backup inductor is connected to the power factor correction circuit; wherein, the first end of the backup inductor is connected to the inductor of the power factor correction circuit, and its second end is connected to the switching transistor and diode of the power factor correction circuit, respectively. The operation of detecting the actual operating current value of the motor and controlling whether the backup inductor is connected based on the actual operating current value can be performed after the operation of increasing the carrier frequency, or it can be performed simultaneously with the operation of increasing the carrier frequency.

[0046] To avoid frequent triggering, some systems use a conservative high current threshold (e.g., 150% of rated current). While this reduces the number of frequency throttling events, it sacrifices the motor's performance potential under high loads, resulting in energy waste. Conversely, if the threshold is too low (e.g., 110% of rated current), it can lead to over-triggering and reduce system robustness. Currently, there is a lack of adaptive optimization mechanisms based on historical triggering data. To address these issues, the above method also includes: obtaining the number of overcurrent-limited frequency throttling triggers within a second preset period; adjusting the current threshold for triggering overcurrent-limited frequency throttling based on the number of overcurrent-limited frequency throttling triggers within the second preset period; wherein, the more overcurrent-limited frequency throttling triggers within the second preset period, the lower the current threshold. A higher number of overcurrent-limited frequency throttling triggers within the second preset period indicates more severe current fluctuations. A lower trigger count allows for a larger operating current, while a higher trigger count requires stricter control of the motor's operating current. Lowering the current threshold allows for overcurrent-limited frequency throttling to be triggered at relatively small currents, and multiple triggers will force the motor into a safe frequency range, ensuring safer operation and reducing the risk of malfunctions, shutdowns, or compressor damage.

[0047] In order to control the reduction of the maximum operating frequency of the motor or to control the motor to maintain a safe operating frequency, there are already control measures for abnormal current fluctuations. In order to avoid triggering the frequency reduction limit again in the above process, the current threshold for triggering the overcurrent frequency reduction limit can be temporarily increased. Therefore, the above method also includes: real-time detection of the actual operating current value of the motor; determining whether the rate of change of the actual operating current value is greater than the preset rate of change and the number of overcurrent frequency reduction limits is greater than the second threshold; if so, the control current threshold is increased and maintained for a third preset duration, which is a short time, such as 50 milliseconds.

[0048] When the trigger count is low, the trigger count threshold can be set higher, resulting in a later timing for entering the operation of controlling the motor operating frequency based on the trigger count. When the trigger count is high, the trigger count threshold needs to be lowered, resulting in an earlier timing for entering the operation of controlling the motor operating frequency based on the trigger count. Therefore, the above method also includes: calculating the average trigger count within the third preset cycle to obtain the reference frequency; calculating a preset coefficient based on the trigger frequency of the current overcurrent limit frequency reduction and the reference frequency; wherein, the preset coefficient = the trigger frequency of the current overcurrent limit frequency reduction / the reference frequency; if the preset coefficient is greater than 1, then the first, second, third, and fourth thresholds are all lowered; if the preset coefficient is equal to 1, then the first, second, third, and fourth thresholds remain unchanged; if the preset coefficient is less than 1, then the first, second, third, and fourth thresholds are all raised. The higher the average trigger count within the third preset cycle, the more severe the current fluctuation. After lowering the trigger count threshold, a smaller number of triggers will force entry into the frequency control program, which can ensure a more reliable operation and reduce the possibility of malfunctions, shutdowns, or compressor damage.

[0049] Example 3 This embodiment provides another motor control method. Figure 2 A flowchart of a motor control method provided in another embodiment of this application is shown below. Figure 2 As shown, the motor control method includes: S1, detect the number of times the overcurrent limiting frequency reduction is triggered within the first preset period and determine the range of the number of triggers; if the number of triggers X ≤ the first threshold X1, then execute step S2; if the first threshold X1 < the number of triggers X ≤ the second threshold X2, then execute step S3; if the second threshold X2 < the number of triggers X ≤ the third threshold X3, then execute step S4; if the third threshold X3 < the number of triggers X ≤ the fourth threshold X4, then execute step S5.

[0050] S2 controls the motor to increase or decrease frequency according to the set operating program.

[0051] S3 controls the motor's frequency ramp-up speed to decrease.

[0052] This includes: if X1 < trigger count X ≤ Xa, then execute step S31; if Xa < trigger count X ≤ Xb, then execute step S32; if Xb < trigger count X ≤ X2, then execute step S33.

[0053] S31 controls the frequency ramping speed to be reduced to half of the original speed.

[0054] S32 controls the frequency upsampling speed to be reduced to 1 / 4 of the original speed.

[0055] S33 controls the frequency upsampling speed to be reduced to 1 / 8 of the original.

[0056] S4 controls the maximum operating frequency of the motor to decrease.

[0057] S5 controls the motor to lock at a safe operating frequency.

[0058] S6, resume frequency increase / decrease according to the set running program.

[0059] According to the system's first preset period T1 (e.g., T1=2h), when the number of overcurrent limit frequency reduction triggers is ≤X1 (e.g., X1=5), the unit operates normally, and its control method is to normally set the frequency reduction rate and the target frequency increase. When X1 < the number of overcurrent limit frequency reduction triggers ≤ the second threshold X2 (e.g., X2=8), the compressor frequency increase rate can be appropriately reduced. When X1 < the number of overcurrent limit frequency reduction triggers X ≤ Xa, the unit's frequency increase rate is reduced to 0.5 times the original logic setting to reduce the frequency of fault protection caused by the operating current approaching the frequency reduction current threshold and current fluctuations during frequency increase operation. Similarly, when the number of overcurrent limit frequency reduction triggers Xa < the number of overcurrent limit frequency reduction triggers X ≤ Xb, the unit's frequency increase rate is reduced to 0.25 times the original logic setting; when Xb < the number of overcurrent limit frequency reduction triggers X ≤ X2, the unit's frequency increase rate is reduced to 0.125 times the original logic setting, and so on. When the second threshold X2 < the number of overcurrent-limited frequency reduction triggers X ≤ the third threshold X3 (e.g., X3=10), the compressor's maximum operating frequency can be directly reduced to a stable operating frequency (at which frequency there is a significant difference between the actual operating current and the frequency reduction trigger current threshold). When the third threshold X3 < the number of overcurrent-limited frequency reduction triggers X ≤ the fourth threshold X4 (e.g., X4=12), the motor's operating frequency can be directly locked at a safe operating frequency. Unlike the former, this directly adjusts the operating frequency to a safe operating frequency, rather than simply reducing the maximum operating frequency. Using the number of overcurrent-limited frequency reduction triggers as a control variable to propose a dynamic protection control strategy for motor operation can reduce problems such as repeated frequency increases and decreases in the motor system, sudden changes in output power, and reduced production efficiency, thereby improving control stability.

[0060] S7. Determine whether the overcurrent limiting frequency reduction is triggered and the number of times the overcurrent limiting frequency reduction is triggered X is greater than the fourth threshold X4. If yes, proceed to step S8; otherwise, return to step S1.

[0061] S8 calculates the maximum carrier frequency based on the maximum junction temperature and case temperature of the switching transistor in the power factor correction circuit and the thermal resistance of the switching transistor, and controls the increase of the motor's carrier frequency with the maximum carrier frequency as the upper limit.

[0062] This includes: if X4 < number of triggers X ≤ fifth threshold X5, then execute step S81; if X5 < number of triggers X ≤ sixth threshold X6, then execute step S82; if X6 < number of triggers X ≤ seventh threshold X7, then execute step S83.

[0063] S81, increase the carrier frequency to K1.

[0064] S82, increase the carrier frequency to K2.

[0065] S83, increase the carrier frequency to K3.

[0066] After reducing the maximum operating frequency or operating stably at the safe operating frequency for a period of time (first preset duration N1=0.5h, second preset duration N2=1h), the frequency will continue to be increased or decreased according to the fixed operating procedure. If the overcurrent limit frequency reduction phenomenon reappears after the frequency increase or decrease action is resumed, the carrier frequency switching mode will be entered. First, the maximum carrier frequency of the unit needs to be calculated in advance based on the junction temperature and shell temperature data returned by the temperature sensor, and the carrier switching is performed within a certain carrier variation range. When X4 < the number of overcurrent limit frequency reduction triggers X ≤ the fifth threshold X5 (e.g., X7=13), the carrier frequency can be appropriately switched to K1 to control the carrier frequency to increase and reduce the actual operating current. Similarly, when X5 < the number of overcurrent limit frequency reduction triggers X ≤ the sixth threshold X6, the carrier frequency of the motor is increased to K2; when X6 < the number of overcurrent limit frequency reduction triggers X ≤ the seventh threshold X7, the carrier frequency of the unit is increased to K3 (maximum carrier frequency), and so on. The maximum carrier frequency is calculated by combining the junction temperature and case temperature formulas with the power loss model and device parameters. The carrier frequency switching is adjusted with the maximum carrier frequency as the upper limit, which is used for step carrier modulation control during motor operation.

[0067] Calculating the maximum carrier frequency requires combining thermal and electrical models and involves two steps: Step 1: Derive the maximum allowable power loss from the junction temperature formula. The junction temperature-case temperature formula (the relationship between device case temperature and junction temperature) is a fundamental formula for thermal management, used to calculate the junction temperature of semiconductor switching transistors (such as IGBTs and MOSFETs) in power factor correction circuits. ; Junction temperature (unit: °C); : Device case temperature (unit: °C); Total power dissipation (W). : Thermal resistance from junction to case temperature (unit: °C / W); When the junction temperature reaches the maximum allowable value At that time, the corresponding power loss is:

[0068] Maximum junction temperature as stated in the device datasheet (e.g., 150°C for IGBTs). Device housing temperature (must be measured). Thermal resistance (must be obtained from the device datasheet, e.g., 1.5℃ / W); Step 2: Convert to maximum carrier frequency Power loss Mainly due to switching losses Generation (dominated at high frequencies):

[0069] k: Switching loss coefficient (unit: W / Hz), which needs to be obtained from device data or experiments. k depends on device type, voltage, current, gate drive, etc. Therefore, the maximum carrier frequency is .

[0070] S9 detects the actual operating current value of the motor.

[0071] S10, determine whether the difference between the actual operating current value and the current threshold is negative and the absolute value of the difference is greater than the preset threshold; if yes, proceed to step S11; if no, proceed to step S121.

[0072] S11 controls the operating frequency of the motor according to the motor's set operating program.

[0073] S12 controls the connection of the backup inductor to reduce the operating current.

[0074] After adjusting the carrier frequency, continue to monitor the actual operating current of the motor. If the actual operating current is still close to the frequency reduction limit current value, then connect the backup inductor; otherwise, normal and stable operation is sufficient. Using the backup inductor to control the stable operation of the motor system allows for timely connection of the backup inductor when the actual current feedback value remains excessively high during motor operation, achieving a better adaptive optimization mechanism.

[0075] S13 detects the motor's operating parameters.

[0076] S14, determine whether there are abnormal fluctuations in the operating parameters; if yes, proceed to step S15; if no, proceed to step S16.

[0077] S15 indicates a fault warning message.

[0078] S16, Exit fault detection.

[0079] When the third threshold X3 < the number of overcurrent frequency throttling triggers X ≤ the fourth threshold X4, the system detects whether there are any abnormalities or fluctuations in the values ​​of various key operating parameters of the motor, and promptly feeds back any abnormalities to the display terminal to provide fault warning information, thereby improving the timeliness of fault diagnosis and reducing the actual failure rate. Using the number of overcurrent frequency throttling triggers as a potential fault indicator improves fault prediction capabilities, allowing for early fault warnings when the frequency throttling limit is repeatedly triggered, preventing actual fault triggers from increasing the failure rate.

[0080] To avoid frequent triggering, some systems adopt a conservative high current threshold (e.g., 150% of rated current). While this reduces the number of frequency reductions, it sacrifices the motor's performance potential under high loads, resulting in energy waste. Conversely, if the threshold is too low (e.g., 110% of rated current), it will lead to over-triggering and reduce system robustness. Currently, there is a lack of adaptive optimization mechanisms based on historical triggering data. To address the above issues, the motor control method in this embodiment further includes: obtaining the number of overcurrent-limited frequency reduction triggers within a second preset period (e.g., 12 hours); adjusting the current threshold for triggering overcurrent-limited frequency reduction based on the number of overcurrent-limited frequency reduction triggers within the second preset period; wherein, the more overcurrent-limited frequency reduction triggers within the second preset period, the lower the current threshold. The more times the overcurrent limit frequency reduction is triggered within the second preset cycle, the more severe the current fluctuation. When the number of triggers is low, the operating current can be larger. When the number of triggers is high, the operating current of the motor needs to be more strictly controlled. After lowering the above current threshold, the overcurrent limit frequency reduction will be triggered at a smaller current. After multiple triggers, it will be forced into the safe frequency range, which can make its operation more reliable and reduce the possibility of failure shutdown or damage to the compressor.

[0081] In order to control the reduction of the maximum operating frequency of the motor or to control the motor to maintain a safe operating frequency, there are already control measures for abnormal current fluctuations. In order to avoid triggering the frequency reduction limit again in the above process, the current threshold for triggering the overcurrent frequency reduction limit can be temporarily increased. Therefore, the above method also includes: real-time detection of the actual operating current value of the motor; determining whether the rate of change of the actual operating current value is greater than the preset rate of change and the number of overcurrent frequency reduction limits is greater than the second threshold; if so, the control current threshold is increased and maintained for a third preset duration, which is a short time, such as 50 milliseconds.

[0082] When the number of triggers is low, the trigger threshold can be set higher, so that the timing for controlling the motor operating frequency based on the number of triggers is later; when the number of triggers is high, the trigger threshold needs to be lowered, so that the timing for controlling the motor operating frequency based on the number of triggers is earlier. Therefore, the above method also includes: calculating the average number of triggers within a third preset period (e.g., 24 hours) to obtain the reference frequency; calculating a preset coefficient based on the trigger frequency of the current overcurrent limit frequency reduction and the reference frequency; wherein, the preset coefficient = the trigger frequency of the current overcurrent limit frequency reduction / the reference frequency; if the preset coefficient is greater than 1 (e.g., 1.2), then the first threshold, the second threshold, the third threshold, and the fourth threshold are all lowered; if the preset coefficient is equal to 1, then the first threshold, the second threshold, the third threshold, and the fourth threshold remain unchanged; if the preset coefficient is less than 1 (e.g., 0.8), then the first threshold, the second threshold, the third threshold, and the fourth threshold are all raised. The higher the average number of triggers within the third preset cycle, the more severe the current fluctuation. After lowering the above trigger number threshold, the frequency control program will be forcibly entered after a smaller number of triggers, which can make the operation process more reliable and reduce the possibility of failure shutdown or compressor damage.

[0083] The core of the motor control method in this embodiment lies in using the number of overcurrent limiting frequency reduction triggers as a dynamic control input to construct an adaptive model of "number of triggers - threshold - frequency". The system records trigger events in real time through an embedded counter and dynamically adjusts the current limit threshold, trigger number threshold, and frequency increase / decrease adjustment control strategy based on the cumulative number of triggers. Simultaneously, the maximum carrier frequency is calculated based on the junction temperature, case temperature, and power loss formulas, and further range-based carrier switching adjustment is performed to reduce the operating current. A backup inductor can also be added to the system and connected when needed to adjust the actual operating current, thereby achieving a highly robust, low-fault trigger control mode. In summary, the motor control method in this embodiment mainly includes three aspects: 1. By dynamically adjusting the motor operating frequency based on the number of overcurrent limiting frequency reduction triggers during actual operation, the operating current range is stably controlled. When the operating current is continuously too high or the load and operating conditions fluctuate, frequently triggering overcurrent limiting frequency reduction, the dynamic adjustment of the frequency increase rate and adaptive frequency directly limits the frequency, avoiding repeated frequency increases / decreases in the motor system and improving system reliability. 2. The number of overcurrent throttling triggers is used as a key fault prediction indicator. When the overcurrent throttling occurs frequently in a short period, motor operating parameters are monitored and faults are diagnosed to provide early warning. Anomalies in various parameters are investigated to reduce the increased failure rate caused by actual fault-triggered protection, thus reducing the number of downtimes during actual customer use and improving customer satisfaction. 3. The maximum carrier frequency that the driving device can withstand is calculated by combining temperature sampling, thermal models, and electrical models. Then, based on the detected number of overcurrent throttling triggers, step-by-step carrier frequency adjustment is implemented to achieve range-adaptive carrier switching. 4. The power factor correction circuit of the motor drive circuit adopts a dual-inductor mode with one backup and one standby. A standby inductor is set up, and during load operation, the actual operating current value determines whether to connect the standby inductor. Unlike using a single inductor, this method can dynamically adjust the actual current magnitude. Unlike directly using a large inductor, a small inductor has a cost advantage, and the standby inductor is not normally connected to the circuit, extending its service life.

[0084] In actual motor drive system operation, sudden changes in motor load and operating conditions are inevitable, causing short-term fluctuations in the input current or load current of the motor system. By dynamically adjusting the overcurrent limiting frequency derating rate and threshold (e.g., increasing or keeping the threshold unchanged when the number of triggers is low, decreasing the threshold when the number of triggers is high; increasing or keeping the frequency increase / decrease rate when the number of triggers is low, decreasing the frequency increase / decrease rate when the number of triggers is high), the system effectively reduces unnecessary frequency limiting operations and avoids frequent power surges caused by instantaneous load fluctuations or other sudden events. Simultaneously, based on the cumulative statistics of the frequency limiting trigger count, the system automatically identifies potential fault symptoms (such as component damage, winding short circuits, or abnormal loads), triggering maintenance alarms in advance to prevent minor problems from escalating into serious faults, achieving early fault prediction and preventative maintenance. Furthermore, by dynamically adjusting the operating frequency to suppress the accumulation of mechanical stress caused by frequent frequency increases / decreases (such as winding vibration and bearing wear), the system significantly reduces the rate of motor aging, extends motor life, and reduces maintenance costs. The adaptive mechanism optimizes the operating frequency and current threshold within safe boundaries, ensuring fault protection performance (avoiding the risk of burnout) while releasing high-load performance potential. Furthermore, it does not rely on external sensors or complex algorithms; it only uses an embedded counter to count the number of triggers, reducing hardware costs and control complexity while enhancing system robustness and adaptability.

[0085] Example 4 This embodiment provides a motor control device applied to a motor with a power factor correction circuit. Figure 3 This is a structural diagram of a motor control device according to an embodiment of the present invention, as shown below. Figure 3 As shown, the control device includes: The judgment module 10 is used to determine whether the number of times the motor's overcurrent limiting frequency reduction is triggered within the first preset period is less than or equal to the first threshold.

[0086] Within the first preset period T1 time (e.g., 2 hours), the number of times the motor's overcurrent limit frequency reduction is triggered is obtained. If the number of triggers is less than or equal to the first threshold, it indicates that the overcurrent trigger is normal. If the number of triggers is greater than the first threshold, it indicates that the current fluctuates frequently, causing the overcurrent limit frequency reduction to trigger frequently.

[0087] The first control module 20 is used to control the operating frequency of the motor according to the motor's set operating program when the number of overcurrent frequency reduction triggers is less than or equal to a first threshold.

[0088] If it is a normal overcurrent trigger, the motor is running normally. You only need to control the motor frequency to increase or decrease according to the motor's set operating program to ensure the motor runs normally.

[0089] The second control module 30 is used to adjust the operating frequency of the motor according to the number of times the overcurrent limiting frequency reduction is triggered when the number of triggers exceeds the first threshold.

[0090] If frequent current fluctuations cause the overcurrent limit frequency reduction to be triggered frequently, the motor's operating frequency needs to be adjusted according to the number of times the overcurrent limit frequency reduction is triggered in order to avoid repeated increases and decreases in the motor frequency.

[0091] In this embodiment, the motor control device first determines, through the judgment module 10, whether the number of times the motor's overcurrent limiting frequency reduction is triggered within a first preset cycle is less than or equal to a first threshold. If the number of triggers is less than or equal to the first threshold, it indicates a normal overcurrent trigger. The first control module 20 then controls the motor's operating frequency according to the motor's set operating program to ensure normal motor operation. If frequent current fluctuations cause frequent overcurrent limiting frequency reduction triggers, the second control module 30 adjusts the motor's operating frequency based on the number of overcurrent limiting frequency reduction triggers. By adding a frequency adjustment scheme for frequent current fluctuations, the motor's frequency can be prevented from repeatedly rising and falling, resulting in stable motor output power, improved production efficiency and energy efficiency, and energy-saving effects for the motor and the electrical equipment using the motor, such as inverter air conditioners, inverter refrigerators, and inverter washing machines. Simultaneously, it reduces the mechanical stress on the motor windings and bearings, slowing down aging.

[0092] The more times the overcurrent limiting frequency reduction is triggered, the more frequent the current fluctuations, and the stricter the frequency restriction on the motor should be. To match the motor frequency control strategy with the number of overcurrent limiting frequency reduction triggers and improve the frequency control effect, the second control module 30 is specifically used to: determine the range of the overcurrent limiting frequency reduction trigger count; if the overcurrent limiting frequency reduction trigger count is greater than the first threshold and less than or equal to the second threshold, it indicates that although the current fluctuation is abnormal, the frequency is low, and the frequency can continue to increase. The second control module 30 controls the motor to reduce the frequency increase rate to avoid excessively rapid frequency fluctuations; wherein, the greater the number of overcurrent limiting frequency reduction triggers... The lower the frequency increase rate, the more frequent the overcurrent limiting frequency reduction triggers. If the number of overcurrent limiting frequency reduction triggers is greater than the second threshold and less than or equal to the third threshold, it indicates that the overcurrent limiting frequency reduction triggers frequently. The second control module 30 controls the maximum operating frequency of the motor to decrease so that the motor can quickly reach the maximum operating frequency and then maintain it at the maximum operating frequency to avoid further frequency increase. If the number of overcurrent limiting frequency reduction triggers is greater than the third threshold, it indicates that the overcurrent limiting frequency reduction triggers very frequently. The second control module 30 controls the motor to maintain it at a safe operating frequency. At the safe operating frequency, the operating current of the motor is lower than the current threshold that triggers the overcurrent limiting frequency reduction, so that the overcurrent limiting frequency reduction is no longer triggered.

[0093] If the current fluctuation ends after the maximum operating frequency of the motor is reduced, the motor should be controlled to return to the set operating program as soon as possible to improve the motor's efficiency. If the current fluctuation is still relatively large, or even if the operating current increases further due to the aforementioned frequency increase operation, leading to more frequent overcurrent limit frequency reduction triggering, then new methods are needed, such as increasing the carrier frequency, to control the operating current. Therefore, after the second control module 30 controls the maximum operating frequency of the motor to decrease, it is also used for: after a first preset time, controlling the operating frequency of the motor according to the set operating program of the motor; determining whether the overcurrent limit frequency reduction triggering is satisfied, and whether the number of overcurrent limit frequency reduction triggering times is greater than the first preset time. Four thresholds; if the judgment result is yes, the maximum carrier frequency is calculated based on the maximum junction temperature of the switching transistor in the power factor correction circuit, the casing temperature of the switching transistor, and the thermal resistance of the switching transistor, and the carrier frequency of the motor is controlled to increase with the maximum carrier frequency as the upper limit; wherein, the greater the number of overcurrent limiting frequency reduction triggers, the greater the carrier frequency; if the judgment result is no, a re-judgment is triggered to determine whether the number of overcurrent limiting frequency reduction triggers of the motor within the first preset period is less than or equal to the first threshold; if the judgment result is yes, the operating frequency of the motor is controlled according to the motor's set operating program; if the judgment result is no, the operating frequency of the motor is adjusted according to the number of overcurrent limiting frequency reduction triggers.

[0094] The number of overcurrent limiting frequency reduction triggers serves as a potential fault indicator, yet existing systems do not incorporate it into their control logic. For example, if the number of triggers exceeds a threshold within a short period, it may indicate a problem with the motor's internal components or the drive board. However, traditional systems only record events without dynamically adjusting protection strategies, leading to motor burnout and increased annual failure rates. In this application, to identify the source of faults causing abnormal current fluctuations as early as possible and alert the user, the aforementioned motor control device further includes a fault detection module (not shown in the figure), used to detect the motor's operating parameters after maintaining the motor at a safe operating frequency; determine whether abnormal fluctuations in the operating parameters occur; and if so, provide a fault warning message.

[0095] If the current fluctuation ends after the motor is maintained at a safe operating frequency, the motor should be controlled to return to the set operating program as soon as possible to improve motor efficiency. If the current fluctuation is still relatively large, or even increases further than before maintaining the safe operating frequency, thus causing the overcurrent limit frequency reduction triggering more frequently, new methods are needed, such as increasing the carrier frequency, to control the operating current. After the second control module 30 controls the motor to maintain a safe operating frequency, it is also used to: after a second preset time, control the motor's operating frequency according to the motor's set operating program; determine whether the overcurrent limit frequency reduction triggering is satisfied, and whether the number of overcurrent limit frequency reduction triggering times is greater than the fourth threshold; such as If the judgment result is yes, then the maximum carrier frequency is calculated based on the maximum junction temperature of the switching transistor in the power factor correction circuit, the casing temperature of the switching transistor, and the thermal resistance of the switching transistor, and the carrier frequency of the motor is controlled to increase with the maximum carrier frequency as the upper limit; wherein, the greater the number of overcurrent limiting frequency reduction triggers, the greater the carrier frequency; if the judgment result is no, then a re-judgment is triggered to determine whether the number of overcurrent limiting frequency reduction triggers of the motor within the first preset period is less than or equal to the first threshold; if the judgment result is yes, then the operating frequency of the motor is controlled according to the motor's set operating program; if the judgment result is no, then the operating frequency of the motor is adjusted according to the number of overcurrent limiting frequency reduction triggers.

[0096] The fourth threshold is greater than the third threshold, which is greater than the second threshold, which is greater than the first threshold.

[0097] The core characteristic of an inductor is its ability to impede changes in current, a phenomenon determined by Lenz's law. When the current increases, the inductor generates an induced electromotive force (EMF) in the opposite direction to the current, attempting to suppress the rise in current; when the current decreases, the induced EMF moves in the same direction as the current, impeding the fall in current. This characteristic is similar to an "inertial element" in a circuit, preventing current changes from occurring instantaneously and thus creating a resistance to current. Therefore, if the inductance value in the power factor correction circuit increases, it will suppress the increase in current. To further suppress the increase in motor operating current, the second control module 30 is also used to: detect the actual operating current value of the motor; determine whether the difference between the actual operating current value and the current threshold is negative, and the absolute value of the difference is greater than a preset threshold; that is, the actual operating current value and the current threshold have a certain gap. If the determination result is yes, the first control module 20 controls the motor's operating frequency according to the motor's set operating program; if the determination result is no, the second control module 30 controls the backup inductor to connect to the power factor correction circuit. The first end of the backup inductor is connected to the inductor of the power factor correction circuit, and its second end is connected to the switching transistor and diode of the power factor correction circuit, respectively. The operation of detecting the actual operating current value of the motor and controlling whether the backup inductor is connected based on the actual operating current value can be performed after the above-mentioned operation of increasing the carrier frequency, or simultaneously with the operation of increasing the carrier frequency.

[0098] To avoid frequent triggering, some systems adopt a conservative high current threshold (e.g., 150% of rated current). While this reduces the number of frequency throttling events, it sacrifices the motor's performance potential under high loads, resulting in energy waste. Conversely, if the threshold is too low (e.g., 110% of rated current), it will lead to over-triggering and reduce system robustness. Currently, there is a lack of adaptive optimization mechanisms based on historical triggering data. To address the above issues, the second control module 30 is also used to: obtain the number of overcurrent-limited frequency throttling triggers within a second preset period; and adjust the current threshold for triggering overcurrent-limited frequency throttling based on the number of overcurrent-limited frequency throttling triggers within the second preset period. The more overcurrent-limited frequency throttling triggers within the second preset period, the lower the current threshold. A higher number of overcurrent-limited frequency throttling triggers within the second preset period indicates more severe current fluctuations. A lower trigger count allows for a larger operating current, while a higher trigger count requires stricter control of the motor's operating current. Lowering the current threshold allows for overcurrent-limited frequency throttling to be triggered at smaller currents, and multiple triggers will force the motor into a safe frequency range, ensuring safer operation and reducing the risk of malfunctions, shutdowns, or compressor damage.

[0099] In order to control the motor to reduce the maximum operating frequency or to keep the motor at a safe operating frequency, there are already control measures for abnormal current fluctuations. In order to avoid triggering frequency reduction again in the above process, the current threshold for triggering overcurrent frequency reduction can be temporarily increased. Therefore, the second control module 30 is also used to: detect the actual operating current value of the motor in real time; determine whether the rate of change of the actual operating current value is greater than the preset rate of change and the number of overcurrent frequency reductions is greater than the second threshold; if so, the control current threshold is increased and maintained for a third preset duration, which is a relatively short time.

[0100] When the trigger count is low, the trigger count threshold can be set higher, resulting in a later timing for entering the operation of controlling the motor operating frequency based on the trigger count. When the trigger count is high, the trigger count threshold needs to be lowered, resulting in an earlier timing for entering the operation of controlling the motor operating frequency based on the trigger count. Therefore, the second control module 30 is also used to: calculate the average trigger count within the third preset period to obtain the reference frequency; calculate the preset coefficient based on the trigger frequency of the current overcurrent limit frequency reduction and the reference frequency; wherein, the preset coefficient = the trigger frequency of the current overcurrent limit frequency reduction / the reference frequency; if the preset coefficient is greater than 1, the first threshold, second threshold, third threshold, and fourth threshold are all lowered; if the preset coefficient is equal to 1, the first threshold, second threshold, third threshold, and fourth threshold remain unchanged; if the preset coefficient is less than 1, the first threshold, second threshold, third threshold, and fourth threshold are all raised. The higher the average trigger count within the third preset period, the more severe the current fluctuation. After lowering the trigger count threshold, a smaller trigger count will force entry into the frequency control program, which can ensure a more reliable operation and reduce the possibility of malfunction shutdowns or compressor damage.

[0101] Example 5 This embodiment provides a motor drive circuit, including a power factor correction circuit. Figure 4 A structural diagram of the motor drive circuit provided in the embodiments of this application is shown below. Figure 4 As shown, the power factor correction circuit includes an inductor L1, a switch Q1, and a diode D1. It also includes a backup inductor L2, whose first terminal is connected to the inductor L1 in the power factor correction circuit, and whose second terminal is connected to both the switch Q1 and the diode D1 in the power factor correction circuit. A first switch S1 is connected in parallel with the backup inductor L2; a second switch S2 is connected in series with the backup inductor L2. When the first switch S1 is opened and the second switch S2 is closed, the backup inductor L2 is connected to the circuit, increasing the total inductance and suppressing current increase. When the first switch S1 is closed and the second switch S2 is open, the backup inductor L2 is not connected to the circuit, and only the inductor L1 is connected. A temperature sensor is placed near the switch Q1 to detect the device housing temperature and calculate the maximum carrier frequency.

[0102] Figure 5 A structural diagram of the motor drive circuit provided in the embodiments of this application is shown below. Figure 5 As shown, it also includes: a buffer capacitor C1, whose first end is connected between the positive output terminal of the rectifier and the inductor, and whose second end is connected to the negative output terminal of the rectifier; and a buffer resistor R1, whose first end is connected to both the negative output terminal of the rectifier and the second end of the buffer capacitor C1, and whose second end is grounded. The buffer capacitor C1 and the buffer resistor R1 form a current buffer circuit, which can achieve a fast response of 10μs and buffer the current in the circuit.

[0103] Example 6 This embodiment provides an electrical device, including a motor, and also includes the motor drive circuit described in the above embodiment.

[0104] In some embodiments of the present invention, the above-mentioned electrical equipment includes at least one of the following: variable frequency air conditioner, variable frequency refrigerator, and variable frequency washing machine.

[0105] Example 7 This embodiment provides an electronic device, characterized in that it includes a processor and a memory, wherein the processor is used to execute a motor control program stored in the memory to implement the motor control method of the above embodiment.

[0106] Figure 6 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application, such as... Figure 6 As shown in the figure, this application provides a device including a processor 111, a communication interface 112, a memory 113, and a communication bus 114, wherein the processor 111, the communication interface 112, and the memory 113 communicate with each other through the communication bus 114. Memory 113 is used to store computer programs; In one embodiment of this application, the processor 111, when executing the program stored in the memory 113, implements the motor control method provided in any of the foregoing method embodiments.

[0107] Example 8 This application also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the motor control method provided in any of the foregoing method embodiments.

[0108] The device embodiments described above are merely illustrative. The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0109] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented using software plus a general-purpose hardware platform, or of course, using hardware. Based on this understanding, the above technical solutions, in essence or the parts that contribute to the related technology, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0110] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0111] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A motor control method, characterized in that, The method includes: Determine whether the number of times the motor's overcurrent limiting frequency reduction is triggered within the first preset cycle is less than or equal to the first threshold. If the judgment result is yes, then the operating frequency of the motor is controlled according to the motor's set operating program; If the judgment result is negative, the operating frequency of the motor is adjusted according to the number of times the overcurrent limiting frequency reduction is triggered.

2. The method according to claim 1, characterized in that, The step of adjusting the motor's operating frequency based on the number of times the overcurrent limiting frequency reduction is triggered includes: Determine the range in which the overcurrent limiting frequency reduction trigger count falls; If the number of times the overcurrent limiting frequency reduction is triggered is greater than the first threshold and less than or equal to the second threshold, the motor is controlled to reduce the frequency increase rate; wherein, the greater the number of times the overcurrent limiting frequency reduction is triggered, the lower the frequency increase rate. If the number of times the overcurrent limiting frequency reduction is triggered is greater than the second threshold and less than or equal to the third threshold, then the maximum operating frequency of the motor is reduced. If the number of times the overcurrent limiting frequency reduction is triggered is greater than the third threshold, the motor is controlled to maintain a safe operating frequency; wherein, the operating current of the motor at the safe operating frequency is lower than the current threshold that triggers the overcurrent limiting frequency reduction. Wherein, the third threshold > the second threshold > the first threshold.

3. The method according to claim 2, characterized in that, After controlling the maximum operating frequency of the motor to decrease, the method further includes: After the first preset duration, the operating frequency of the motor is controlled according to the set operating program of the motor; Determine whether the conditions for triggering overcurrent limiting frequency reduction are met, and whether the number of times the overcurrent limiting frequency reduction is triggered is greater than a fourth threshold; wherein, the fourth threshold > the third threshold > the second threshold > the first threshold; If the judgment result is yes, then the maximum carrier frequency is calculated based on the maximum junction temperature of the switching transistor in the power factor correction circuit, the case temperature of the switching transistor, and the thermal resistance of the switching transistor, and the carrier frequency of the motor is controlled to increase with the maximum carrier frequency as the upper limit; wherein, the greater the number of times the overcurrent limiting frequency reduction is triggered, the greater the carrier frequency; If the judgment result is negative, a re-judgment is triggered to determine whether the number of times the motor's overcurrent limiting frequency reduction is triggered within the first preset cycle is less than or equal to the first threshold. If the judgment result is positive, the operating frequency of the motor is controlled according to the motor's set operating program. If the judgment result is negative, the operating frequency of the motor is adjusted according to the number of times the overcurrent limiting frequency reduction is triggered.

4. The method according to claim 2, characterized in that, After controlling the motor to maintain a safe operating frequency, the method further includes: Detect the operating parameters of the motor; Determine whether the operating parameters exhibit abnormal fluctuations; If so, a fault warning message will be displayed.

5. The method according to claim 2, characterized in that, After controlling the motor to maintain a safe operating frequency, the method further includes: After the second preset duration, the operating frequency of the motor is controlled according to the set operating program of the motor; Determine whether the conditions for triggering overcurrent limiting frequency reduction are met, and whether the number of times the overcurrent limiting frequency reduction is triggered is greater than a fourth threshold; wherein, the fourth threshold > the third threshold > the second threshold > the first threshold; If the judgment result is yes, then the maximum carrier frequency is calculated based on the maximum junction temperature of the switching transistor in the power factor correction circuit, the case temperature of the switching transistor, and the thermal resistance of the switching transistor, and the carrier frequency of the motor is controlled to increase with the maximum carrier frequency as the upper limit; wherein, the greater the number of times the overcurrent limiting frequency reduction is triggered, the greater the carrier frequency; If the judgment result is negative, a re-judgment is triggered to determine whether the number of times the motor's overcurrent limiting frequency reduction is triggered within the first preset cycle is less than or equal to the first threshold. If the judgment result is positive, the operating frequency of the motor is controlled according to the motor's set operating program. If the judgment result is negative, the operating frequency of the motor is adjusted according to the number of times the overcurrent limiting frequency reduction is triggered.

6. The method according to claim 1, wherein the motor is connected to a power factor correction circuit, the power factor correction circuit comprising an inductor, a switching transistor, and a diode, and further comprising a spare inductor, wherein a first terminal of the spare inductor is connected to the inductor, and a second terminal is respectively connected to the switching transistor and the diode of the power factor correction circuit, characterized in that, The method further includes: Detect the actual operating current value of the motor; Determine whether the difference between the actual operating current value and the current threshold is negative, and whether the absolute value of the difference is greater than a preset threshold. If the judgment result is yes, then the operating frequency of the motor is controlled according to the motor's set operating program; If the determination result is negative, then the backup inductor is connected to the power factor correction circuit.

7. The method according to claim 1, characterized in that, The method further includes: Obtain the number of times the overcurrent limit frequency reduction is triggered within the second preset period; The current threshold for triggering overcurrent limit frequency reduction is adjusted according to the number of times the overcurrent limit frequency reduction is triggered within the second preset period; wherein, the more times the overcurrent limit frequency reduction is triggered within the second preset period, the lower the current threshold is.

8. The method according to claim 1, characterized in that, The method further includes: Real-time detection of the actual operating current value of the motor; Determine whether the rate of change of the actual operating current value is greater than the preset rate of change, and whether the number of times the overcurrent limit frequency is reduced is greater than the second threshold. If so, the current threshold is increased and maintained for a third preset duration.

9. The method according to claim 3, characterized in that, The method further includes: Calculate the average number of triggers within the third preset period to obtain the base frequency; A preset coefficient is calculated based on the current overcurrent limit frequency reduction trigger frequency and the reference frequency; wherein, the preset coefficient = current overcurrent limit frequency reduction trigger frequency / reference frequency; If the preset coefficient is greater than 1, then the first threshold, the second threshold, the third threshold and the fourth threshold are all lowered. If the preset coefficient is equal to 1, then the first threshold, the second threshold, the third threshold, and the fourth threshold are kept unchanged; If the preset coefficient is less than 1, then the first threshold, the second threshold, the third threshold and the fourth threshold are all adjusted upwards.

10. A motor control device, applied to a motor having a power factor correction circuit, characterized in that, The device includes: The judgment module is used to determine whether the number of times the motor's overcurrent limiting frequency reduction is triggered within the first preset period is less than or equal to the first threshold. The first control module is used to control the operating frequency of the motor according to the motor's set operating program when the number of overcurrent frequency reduction triggers is less than or equal to a first threshold. The second control module is used to adjust the operating frequency of the motor according to the number of times the overcurrent limiting frequency reduction is triggered when the number of triggers exceeds the first threshold.

11. A motor drive circuit, comprising a power factor correction circuit, wherein the power factor correction circuit includes an inductor, a switching transistor, and a diode, characterized in that, Also includes: A spare inductor, the first end of which is connected to the inductor, and the second end of which is connected to the switching transistor and the diode of the power factor correction circuit, respectively; The first switch is connected in parallel with the backup inductor; The second switch is connected in series with the backup inductor.

12. The motor drive circuit according to claim 11, characterized in that, Also includes: A buffer capacitor, the first end of which is connected between the positive output terminal of the rectifier and the inductor, and the second end of which is connected to the negative output terminal of the rectifier; A buffer resistor, the first end of which is connected to the negative output terminal of the rectifier and the second end of the buffer capacitor, and the second end of which is grounded.

13. An electrical appliance, comprising a motor, characterized in that, It also includes the motor drive circuit as described in claim 11 or 12.

14. An electronic device, characterized in that, include: A processor and a memory, the processor being configured to execute a motor control program stored in the memory to implement the motor control method according to any one of claims 1-9.

15. A storage medium, characterized in that, The storage medium stores one or more programs, which can be executed by one or more processors to implement the motor control method according to any one of claims 1-9.

Images