A motor starting method, system and terminal

Abstract

The present invention provides a motor starting method, system, and terminal, comprising the following steps: obtaining a motor starting instruction; determining whether the motor starting instruction is a quick start instruction; if so, executing a quick motor start; otherwise, executing a normal motor start. The motor starting method, system, and terminal of the present invention combine both quick and normal motor starting functions, meeting user needs in different scenarios. They use a variable switching frequency to start the motor, significantly reducing the motor starting time and ensuring the success rate and stability of the motor start. Furthermore, they introduce a temperature parameter to limit the maximum switching frequency, protecting the hardware.

Description

Technical Field

[0001] The present invention relates to the technical field of motor starting, and in particular to a motor starting method, system and terminal. Background Art

[0002] In some motor applications, the motor must reach its target speed very quickly to start. Typically, the magnitude of the motor's back EMF is proportional to the speed. Because the motor's speed is very low when it's stationary or just starting up, the back EMF is very small, making it impossible to determine the rotor position based on the back EMF signal. Only after the speed has sufficiently accelerated can the rotor position be estimated based on the back EMF before switching to closed-loop operation. Therefore, the long time required to identify the initial rotor position and accelerate the motor from zero speed is a major contributor to the time-consuming motor startup.

[0003] Due to cost and application environment constraints, many motor products lack position sensors, using sensorless control technology to control motor operation. Sensorless control algorithms are primarily categorized as high-frequency injection and back-EMF-based observers. Because sensorless control algorithms often incorporate a PI regulator, and the speed and accuracy of PI regulators conflict, it's impossible to quickly and accurately estimate the rotor position while maintaining constant sampling data and switching frequency. Consequently, the success rate and stability of motor startup cannot be guaranteed. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the present invention aims to provide a motor starting method, system, and terminal to address the technical problem of long motor starting times in the prior art. Compared to existing motor starting methods, the present invention provides both fast and normal motor starting functions, meeting user needs in different scenarios.

[0005] To achieve the above-mentioned and other related purposes, the present invention provides a motor starting method, system and terminal, comprising the following steps: obtaining a motor starting instruction; determining whether the motor starting instruction is a quick starting instruction; if so, executing a quick motor start; otherwise executing a normal motor start.

[0006] In one embodiment of the present invention, performing a fast motor start includes the following steps:

[0007] Setting the first switching frequency to the maximum switching frequency;

[0008] injecting a high frequency voltage based on the first switching frequency to determine a first position of a rotor of the motor;

[0009] operating the motor in a closed loop based on the first position of the rotor until a rotational speed of the rotor reaches a first speed threshold;

[0010] re-estimating the position of the rotor of the motor to determine a second position of the rotor of the motor;

[0011] operating the motor in a closed loop based on the second position of the rotor until the rotational speed of the rotor reaches a second speed threshold;

[0012] Switching the first switching frequency to a second switching frequency;

[0013] continuing to operate the motor in a closed loop based on the second switching frequency to adjust the rotational speed of the rotor until the rotational speed of the rotor reaches a third speed threshold;

[0014] Complete motor starting.

[0015] In one embodiment of the present invention, operating the motor in a closed loop based on the first position of the rotor until the rotational speed of the rotor reaches a first speed threshold includes adjusting the first switching frequency based on temperature; and adjusting the first switching frequency based on temperature includes the following steps:

[0016] Real-time collection of current temperature information of the switching devices of the motor's inverter or driver;

[0017] Get the limiting relationship between temperature and switching frequency;

[0018] The first switching frequency is adjusted based on the current temperature information of the switching device and the limiting relationship between the temperature and the switching frequency, and the adjusted first switching frequency is used as the switching frequency of subsequent closed-loop operation.

[0019] In one embodiment of the present invention, the limiting relationship between temperature and switching frequency is obtained using one or more of the following methods:

[0020] Obtain the limiting relationship between temperature and switching frequency through experiments;

[0021] Obtain the limiting relationship between temperature and switching frequency by estimating experimental results;

[0022] Consult the data sheet to obtain the limiting relationship between temperature and switching frequency.

[0023] In one embodiment of the present invention, adjusting the first switching frequency based on the current temperature information of the switching device and the limiting relationship between the temperature and the switching frequency, and using the adjusted first switching frequency as the switching frequency for subsequent closed-loop operation includes the following steps:

[0024] Finding the maximum switching frequency corresponding to the current temperature information of the switching device;

[0025] Determining whether the first switching frequency is greater than a maximum switching frequency corresponding to the current temperature information of the switching device;

[0026] If so, the maximum switching frequency corresponding to the current temperature information of the switching device is set as the first switching frequency; otherwise, the first switching frequency remains unchanged.

[0027] In one embodiment of the present invention, switching the first switching frequency to the second switching frequency includes switching the first switching frequency to the second switching frequency according to the rotation time of the rotor; and switching the first switching frequency to the second switching frequency according to the rotation time of the rotor includes the following steps:

[0028] Counting the rotation time of the rotor;

[0029] When the rotation time of the rotor is greater than a preset time value, the first switching frequency is switched to a second switching frequency.

[0030] In one embodiment of the present invention, the second switching frequency is not greater than the first switching frequency, the third speed threshold is not less than the second speed threshold, and the second speed threshold is not less than the first speed threshold.

[0031] In one embodiment of the present invention, performing normal motor startup includes the following steps:

[0032] Setting the second switching frequency;

[0033] injecting a high frequency voltage based on the second switching frequency to determine a first position of a rotor of the motor;

[0034] operating the motor in a closed loop according to the first position of the rotor until a rotational speed of the rotor reaches a first speed threshold;

[0035] re-estimating the position of the rotor of the motor to determine a second position of the rotor of the motor;

[0036] operating the motor in a closed loop based on the second position of the rotor until the rotational speed of the rotor reaches a third speed threshold;

[0037] Complete motor start-up.

[0038] Correspondingly, the present invention provides a motor starting system, comprising:

[0039] Acquisition module, used to obtain motor start instructions;

[0040] a judging module, connected to the acquiring module, for judging whether the motor starting instruction is a quick starting instruction;

[0041] A starting module is connected to the judging module, and if the motor starting instruction is a quick starting instruction, a quick motor starting is performed; otherwise, a normal motor starting is performed.

[0042] Correspondingly, the present invention provides a motor starting terminal, comprising: a processor and a memory;

[0043] The memory is used to store computer programs;

[0044] The processor is configured to execute the computer program stored in the memory, so as to enable the terminal to execute any one of the above motor starting methods.

[0045] As described above, the motor starting method, system, and terminal of the present invention have the following beneficial effects:

[0046] (1) It takes into account both fast motor start and normal motor start functions, meeting the user's needs in different scenarios;

[0047] (2) The motor is started by using variable switching frequency, which significantly reduces the motor starting time and ensures the success rate and stability of the motor starting;

[0048] (3) The temperature parameter is introduced to limit the maximum switching frequency, thus protecting the hardware equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 Shown is a flow chart of a motor starting method according to an embodiment of the present invention.

[0050] Figure 2 FIG. 1 is a flowchart of a fast motor starting method according to an embodiment of the present invention.

[0051] Figure 3 FIG. 1 is a flowchart of a normal motor starting method in one embodiment of the present invention.

[0052] Figure 4 FIG. 1 is a schematic structural diagram of a motor starting system according to an embodiment of the present invention.

[0053] Figure 5 FIG. 1 is a schematic structural diagram of a motor starting terminal according to an embodiment of the present invention.

[0054] Component number description

[0055] 41 Get Module

[0056] 42 Judgment Module

[0057] 43 Startup Module

[0058] 51 processors

[0059] 52 Memory

[0060] S1~S4 Motor starting method steps

[0061] S31~S38 Quick Motor Startup Method Steps

[0062] S41~S46 Normal motor starting method steps DETAILED DESCRIPTION

[0063] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0064] It should be noted that the illustrations provided in the present invention are only schematic illustrations of the basic concept of the present invention. Therefore, the drawings only show components related to the present invention and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0065] In addition, in the present invention, descriptions such as "first" and "second" are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection of the present invention.

[0066] A permanent magnet synchronous motor (PMSM) consists of components such as a stator winding, a rotor, and end caps. Based on the location of the permanent magnets on the rotor, PMSMs can be categorized as surface-mounted PMSMs and internal PMSMs. Specifically, the permanent magnets of an internal PMSM are located inside the rotor, while those of a surface-mounted PMSM are located on the outer surface of the rotor core. This application uses an internal PMSM as an example to illustrate the motor starting method of the present invention.

[0067] like Figure 1 As shown, in one embodiment, the motor starting method of the present invention includes the following steps:

[0068] Step S1: Obtain a motor start instruction.

[0069] In one embodiment, the motor start instruction of the present invention is a fast motor start instruction or a normal motor start instruction. In one embodiment, the driver obtains the fast motor start instruction or the normal motor start instruction sent by the host computer through serial communication.

[0070] Step S2: Determine whether the motor start instruction is a quick start instruction.

[0071] In one embodiment, the present invention selects whether it is necessary to quickly start the motor based on the actual application scenario. For example, for a motor with a high-power load, it is necessary to obtain a normal motor start instruction to start the motor. Because the impact current at the moment of motor startup is several times or even more than ten times the normal rated current, as the speed increases, the current begins to slowly decrease until the speed rises to the normal range, and the current will drop to a normal level. Normally starting the motor can prevent the local insulation part from being broken down by the current due to excessive instantaneous current, thereby ensuring the service life of the motor. However, if the normal startup time of the motor is too long, it will not only increase the system loss, but also reduce the work efficiency. In order to effectively reduce the startup time of the motor, a fast motor start instruction can be obtained to start the motor. The present application takes into account both the fast motor startup and normal motor startup functions, meeting the user's usage needs in different scenarios.

[0072] Step S3: If yes, execute fast motor start.

[0073] like Figure 2 As shown, in one embodiment, performing a fast motor start includes the following steps:

[0074] S31 . Set the first switching frequency as the maximum switching frequency.

[0075] Specifically, this application uses the maximum switching frequency recommended by the datasheet as the first switching frequency. Experimental research has found that the switching frequency is proportional to the rotor position estimation time. That is, a high switching frequency can significantly reduce the time required for initial position estimation. Furthermore, a higher switching frequency reduces motor vibration, operating noise, and heat generation. However, a higher switching frequency also increases switching losses, and system efficiency decreases while maintaining constant output power. To ensure the overall operating efficiency of the motor, a higher switching frequency should be used during startup whenever possible.

[0076] S32 . Inject a high-frequency voltage based on the first switching frequency to determine a first position of the rotor of the motor.

[0077] When a motor is stationary, the initial rotor position is unknown. Starting a motor without an initial rotor position known can result in excessive starting current, failure to start, or even rotor reversal. Large errors in detecting the initial rotor position can directly affect the accuracy of rotor position estimation, leading to erratic motor operation and failure to operate normally. In one embodiment, the present application utilizes a high-frequency injection method to identify the initial rotor position of the motor, thereby improving the accuracy and reliability of rotor initial position identification. The essence of the high-frequency injection method is to utilize the modulation effect generated by the salient pole structure or salient pole effect of the motor rotor to identify the rotor position. However, the high-frequency injection method cannot identify the rotor magnetic polarity. If the magnetic polarity identification is misaligned, the rotor position will have a 180° phase deviation, resulting in motor startup failure and limiting the motor's load capacity. In one embodiment, the present application identifies the rotor magnetic polarity after determining the initial rotor position. The specific magnetic polarity determination method employed is a transient short pulse injection method or a second harmonic method based on the cross-saturation effect. In one embodiment, after determining the initial position and magnetic polarity of the rotor of the motor, the present application continues to inject a high-frequency voltage to determine the first position of the rotor of the motor.

[0078] S33 . Operating the motor in a closed loop based on the first position of the rotor of the motor until the rotation speed of the rotor reaches a first speed threshold.

[0079] In one embodiment, the present invention employs a first speed control system that operates the motor in a closed-loop manner based on a first position of the motor's rotor. Specifically, in the first speed control system, the rotor's rotational speed is fed back as an output to an input terminal for comparison with a given speed. The resulting deviation signal is used to adjust and control the motor's operating speed until the rotor's rotational speed reaches a first speed threshold. At a given speed, the first speed control system improves tracking and positioning accuracy, implements automatic acceleration control, and achieves higher operating speeds, more stable, and smoother rotational speeds than open-loop control, significantly improving motor performance.

[0080] In one embodiment, operating the motor in a closed loop based on the first position of the rotor until the speed of the rotor reaches a first speed threshold includes adjusting the first switching frequency based on temperature; and adjusting the first switching frequency based on temperature includes the following steps:

[0081] (1) Real-time acquisition of the current temperature information of the switching device of the motor inverter or driver. The switching device of the motor inverter or driver of the present application is an insulated gate bipolar transistor (IGBT), an intelligent power module (IPM), a metal oxide semiconductor field effect transistor (MOSFET), an integrated gate commutated thyristor (IGCT) or a power transistor (GTR). Different temperature measurement methods are used according to different types of switching devices. Specifically, for switching devices with temperature sensors, the current temperature information of the switching device can be directly obtained by using its temperature output function; for switching devices without temperature sensors, the current temperature information of the switching device can be indirectly obtained by using an external temperature acquisition circuit. In one embodiment, the switching device used in the present application is a MOSFET. Since there is no temperature sensor in the MOSFET, an external temperature acquisition circuit is required when acquiring the current temperature information of the MOSFET, wherein the temperature acquisition circuit includes at least a temperature sensitive resistor. When the temperature at the MOSFET acquisition point changes, the resistance of the MOSFET itself changes accordingly. The temperature value corresponding to the current resistance value can be calculated based on the conversion relationship between the resistance value and the temperature. The temperature value is the current temperature information of the MOSFET. In another embodiment of the present invention, when the switching device used is an IPM, the temperature output function of the IPM can be used to directly obtain the current temperature information of the IPM.

[0082] (2) Obtaining the limiting relationship between temperature and switching frequency. In one embodiment, obtaining the limiting relationship between temperature and switching frequency adopts one or more of the following methods:

[0083] Obtain the limiting relationship between temperature and switching frequency through experiments;

[0084] Obtain the limiting relationship between temperature and switching frequency by estimating experimental results;

[0085] Consult the data sheet to obtain the limiting relationship between temperature and switching frequency.

[0086] (3) Adjusting the first switching frequency based on the current temperature information of the switching device and the limiting relationship between the temperature and the switching frequency, and using the adjusted first switching frequency as the switching frequency for subsequent closed-loop operation. In one embodiment, adjusting the first switching frequency based on the current temperature information of the switching device and the limiting relationship between the temperature and the switching frequency includes the following steps:

[0087] Finding the maximum switching frequency corresponding to the current temperature information of the switching device;

[0088] Determining whether the first switching frequency is greater than a maximum switching frequency corresponding to the current temperature information of the switching device;

[0089] If so, the maximum switching frequency corresponding to the current temperature information of the switching device is set as the first switching frequency; otherwise, the first switching frequency remains unchanged.

[0090] By introducing the temperature parameter to limit the maximum switching frequency, the hardware device is prevented from being burned out due to excessive temperature.

[0091] S34 : Re-estimate the position of the rotor of the motor to determine a second position of the rotor of the motor.

[0092] When an electrical pulse is input into the stator winding, it generates a vector magnetic field. When the stator winding's vector magnetic field rotates by an angle, this magnetic field drives the rotor to rotate by an angle, ensuring that the rotor's magnetic field and the stator's magnetic field always align in direction. When the rotor rotates, it generates an induced electromotive force (EMF) in the stator winding, known as the back EMF.

[0093] When the rotor speed reaches a first speed threshold, the back EMF in the stator winding reaches a preset value. Based on this back EMF, the position of the motor's rotor can be estimated. In one embodiment, the present application employs a back EMF-based position sensorless control method to estimate the rotor position and determine the second position of the motor's rotor.

[0094] S35 . Operate the motor in a closed loop based on the second position of the rotor until the rotation speed of the rotor reaches a second speed threshold.

[0095] In one embodiment, the present invention adopts a second speed control system, which operates the motor in a closed loop based on the second position of the rotor. The specific execution steps are the same as those of the first speed control system in S33 and are not repeated here.

[0096] S36: Switch the first switching frequency to a second switching frequency.

[0097] In one embodiment, when the rotation speed of the rotor reaches a second speed threshold, the first switching frequency is switched to a second switching frequency.

[0098] In another embodiment, switching the first switching frequency to the second switching frequency includes switching the first switching frequency to the second switching frequency according to a rotation time of the rotor; and switching the first switching frequency to the second switching frequency according to the rotation time of the rotor includes the following steps:

[0099] Counting the rotation time of the rotor;

[0100] When the rotation time of the rotor is greater than a preset time value, the first switching frequency is switched to a second switching frequency.

[0101] Switching from the first switching frequency to the second switching frequency requires an intermediate transition process, otherwise the system is prone to loss of control. In one embodiment, the present application divides a plurality of intermediate switching frequencies at equal intervals between the first switching frequency and the second switching frequency. The first switching frequency is first switched to the intermediate switching frequency, and then switched from the intermediate switching frequency to the second switching frequency, thereby achieving a continuous switching from the first switching frequency to the second switching frequency from large to small. Using a variable switching frequency to start the motor not only reduces the motor startup time and improves the motor's operating efficiency, but also significantly improves the stability of the motor's operation.

[0102] S37 . Continue to operate the motor in a closed loop based on the second switching frequency to adjust the rotational speed of the rotor until the rotational speed of the rotor reaches a third speed threshold.

[0103] In one embodiment, the motor continues to operate in a closed loop based on the second switching frequency to adjust the speed of the rotor until the speed of the rotor reaches a third speed threshold. The specific execution steps are the same as S32 and S33 and are not repeated here.

[0104] In one embodiment, the second switching frequency is not greater than the first switching frequency, the third speed threshold is not less than the second speed threshold, and the second speed threshold is not less than the first speed threshold.

[0105] S38, complete motor start-up.

[0106] A high switching frequency is used during initial position identification and magnetic polarity determination. Once the motor is running stably, a variable switching frequency strategy is introduced to adjust the switching frequency. Although the switching frequency varies, the motor speed continues to increase until it reaches the third speed threshold, completing the motor startup.

[0107] Step S4: Otherwise, perform normal motor start-up.

[0108] like Figure 3 As shown, in one embodiment, performing normal motor startup includes the following steps:

[0109] S41, setting a second switching frequency;

[0110] S42, injecting a high-frequency voltage based on the second switching frequency to determine a first position of a rotor of the motor;

[0111] S43, operating the motor in a closed loop according to the first position of the rotor until the rotational speed of the rotor reaches a first speed threshold;

[0112] S44, re-estimating the position of the rotor of the motor to determine a second position of the rotor of the motor;

[0113] S45, operating the motor in a closed loop based on the second position of the rotor until the rotational speed of the rotor reaches a third speed threshold;

[0114] S46, complete motor start-up.

[0115] Compared with the fast motor start-up, the normal motor start-up step lacks the process of adjusting the first switching frequency based on the current temperature information of the switching device and the limiting relationship between the temperature and the switching frequency, and switching the first switching frequency to the second switching frequency. The remaining execution steps are basically the same as S3 and will not be repeated here.

[0116] like Figure 4 As shown, in one embodiment, the motor starting system of the present invention includes:

[0117] The acquisition module 41 is used to acquire a motor start instruction.

[0118] In one embodiment, the motor start instruction of the present invention is a fast motor start instruction or a normal motor start instruction. In one embodiment, the driver obtains the fast motor start instruction or the normal motor start instruction sent by the host computer through serial communication.

[0119] The judging module 42 is connected to the acquiring module 41 and is used to judge whether the motor starting instruction is a quick starting instruction.

[0120] In one embodiment, the present invention selects whether it is necessary to quickly start the motor based on the actual application scenario. For example, for a motor with a high-power load, it is necessary to obtain a normal motor start instruction to start the motor. Because the impact current at the moment of motor startup is several times or even more than ten times the normal rated current, as the speed increases, the current begins to slowly decrease until the speed rises to the normal range, and the current will drop to a normal level. Normally starting the motor can prevent the local insulation part from being broken down by the current due to excessive instantaneous current, thereby ensuring the service life of the motor. However, if the normal startup time of the motor is too long, it will not only increase the system loss, but also reduce the work efficiency. In order to effectively reduce the startup time of the motor, a fast motor start instruction can be obtained to start the motor. The present application takes into account both the fast motor startup and normal motor startup functions, meeting the user's usage needs in different scenarios.

[0121] The starting module 43 is connected to the judging module 42 , and executes a quick motor start if the motor starting instruction is a quick start instruction; otherwise, executes a normal motor start.

[0122] like Figure 2 As shown, in one embodiment, performing a fast motor start includes the following steps:

[0123] S31 . Set the first switching frequency as the maximum switching frequency.

[0124] Specifically, this application uses the maximum switching frequency recommended by the data sheet as the first switching frequency. Experimental studies have found that the switching frequency is proportional to the rotor position estimation time, that is, a high switching frequency can significantly reduce the time required for initial position estimation, and the higher the switching frequency, the smaller the vibration of the motor, the lower the operating noise, and the lower the motor heat generation; but at the same time, the higher the switching frequency, the higher the frequency of the harmonic current, the greater the motor loss, and the lower the output power. In order to ensure the overall operating efficiency of the motor, a higher switching frequency should be used as much as possible during the startup phase, and a relatively low switching frequency should be used to stabilize the motor after startup is completed.

[0125] S32 . Inject a high-frequency voltage based on the first switching frequency to determine a first position of the rotor of the motor.

[0126] When a motor is stationary, the initial rotor position is unknown. Starting a motor without an initial rotor position known can result in excessive starting current, failure to start, or even rotor reversal. Large errors in detecting the initial rotor position can directly affect the accuracy of rotor position estimation, leading to erratic motor operation and failure to operate normally. In one embodiment, the present application utilizes a high-frequency injection method to identify the initial rotor position of the motor, thereby improving the accuracy and reliability of rotor initial position identification. The essence of the high-frequency injection method is to utilize the modulation effect generated by the salient pole structure or salient pole effect of the motor rotor to identify the rotor position. However, the high-frequency injection method cannot identify the rotor magnetic polarity. If the magnetic polarity identification is misaligned, the rotor position will have a 180° phase deviation, resulting in motor startup failure and limiting the motor's load capacity. In one embodiment, the present application identifies the rotor magnetic polarity after determining the initial rotor position. The specific magnetic polarity determination method employed is a transient short pulse injection method or a second harmonic method based on the cross-saturation effect. In one embodiment, after determining the initial position and magnetic polarity of the rotor of the motor, the present application continues to inject a high-frequency voltage to determine the first position of the rotor of the motor.

[0127] S33 . Operating the motor in a closed loop based on the first position of the rotor of the motor until the rotation speed of the rotor reaches a first speed threshold.

[0128] In one embodiment, the present invention employs a first speed control system that operates the motor in a closed-loop manner based on a first position of the motor's rotor. Specifically, in the first speed control system, the rotor's rotational speed is fed back as an output to an input terminal for comparison with a given speed. The resulting deviation signal is used to adjust and control the motor's operating speed until the rotor's rotational speed reaches a first speed threshold. At a given speed, the first speed control system improves tracking and positioning accuracy, implements automatic acceleration control, and achieves higher operating speeds, more stable, and smoother rotational speeds than open-loop control, significantly improving motor performance.

[0129] In one embodiment, operating the motor in a closed loop based on the first position of the rotor until the speed of the rotor reaches a first speed threshold includes adjusting the first switching frequency based on temperature; and adjusting the first switching frequency based on temperature includes the following steps:

[0130] (1) Real-time acquisition of the current temperature information of the switching device of the motor inverter or driver. The switching device of the motor inverter or driver of the present application is an insulated gate bipolar transistor (IGBT), an intelligent power module (IPM), a metal oxide semiconductor field effect transistor (MOSFET), an integrated gate commutated thyristor (IGCT) or a power transistor (GTR). Different temperature measurement methods are used according to different types of switching devices. Specifically, for switching devices with temperature sensors, the current temperature information of the switching device can be directly obtained by using its temperature output function; for switching devices without temperature sensors, the current temperature information of the switching device can be indirectly obtained by using an external temperature acquisition circuit. In one embodiment, the switching device used in the present application is a MOSFET. Since there is no temperature sensor in the MOSFET, an external temperature acquisition circuit is required when acquiring the current temperature information of the MOSFET, wherein the temperature acquisition circuit includes at least a temperature sensitive resistor. When the temperature at the MOSFET acquisition point changes, the resistance of the MOSFET itself changes accordingly. The temperature value corresponding to the current resistance value can be calculated based on the conversion relationship between the resistance value and the temperature. The temperature value is the current temperature information of the MOSFET. In another embodiment of the present invention, when the switching device used is an IPM, the temperature output function of the IPM can be used to directly obtain the current temperature information of the IPM.

[0131] (2) Obtaining the limiting relationship between temperature and switching frequency. In one embodiment, obtaining the limiting relationship between temperature and switching frequency adopts one or more of the following methods:

[0132] Obtain the limiting relationship between temperature and switching frequency through experiments;

[0133] Obtain the limiting relationship between temperature and switching frequency by estimating experimental results;

[0134] Consult the data sheet to obtain the limiting relationship between temperature and switching frequency.

[0135] (3) Adjusting the first switching frequency based on the current temperature information of the switching device and the limiting relationship between the temperature and the switching frequency, and using the adjusted first switching frequency as the switching frequency for subsequent closed-loop operation. In one embodiment, adjusting the first switching frequency based on the current temperature information of the switching device and the limiting relationship between the temperature and the switching frequency includes the following steps:

[0136] Finding the maximum switching frequency corresponding to the current temperature information of the switching device;

[0137] Determining whether the first switching frequency is greater than a maximum switching frequency corresponding to the current temperature information of the switching device;

[0138] If so, the maximum switching frequency corresponding to the current temperature information of the switching device is set as the first switching frequency; otherwise, the first switching frequency remains unchanged.

[0139] By introducing the temperature parameter to limit the maximum switching frequency, the hardware device is prevented from being burned out due to excessive temperature.

[0140] S34 : Re-estimate the position of the rotor of the motor to determine a second position of the rotor of the motor.

[0141] When an electrical pulse is input into the stator winding, it generates a vector magnetic field. When the stator winding's vector magnetic field rotates by an angle, this magnetic field drives the rotor to rotate by an angle, ensuring that the rotor's magnetic field and the stator's magnetic field always align in direction. When the rotor rotates, it generates an induced electromotive force (EMF) in the stator winding, known as the back EMF.

[0142] When the rotor speed reaches a first speed threshold, the back EMF in the stator winding reaches a preset value. Based on this back EMF, the position of the motor's rotor can be estimated. In one embodiment, the present application employs a back EMF-based position sensorless control method to estimate the rotor position and determine the second position of the motor's rotor.

[0143] S35 . Operate the motor in a closed loop based on the second position of the rotor until the rotation speed of the rotor reaches a second speed threshold.

[0144] In one embodiment, the present invention adopts a second speed control system, which operates the motor in a closed loop based on the second position of the rotor. The specific execution steps are the same as those of the first speed control system in S33 and are not repeated here.

[0145] S36: Switch the first switching frequency to a second switching frequency.

[0146] In one embodiment, when the rotation speed of the rotor reaches a second speed threshold, the first switching frequency is switched to a second switching frequency.

[0147] In another embodiment, switching the first switching frequency to the second switching frequency includes switching the first switching frequency to the second switching frequency according to a rotation time of the rotor; and switching the first switching frequency to the second switching frequency according to the rotation time of the rotor includes the following steps:

[0148] Counting the rotation time of the rotor;

[0149] When the rotation time of the rotor is greater than a preset time value, the first switching frequency is switched to a second switching frequency.

[0150] Switching from the first switching frequency to the second switching frequency requires an intermediate transition process, otherwise the system is prone to loss of control. In one embodiment, the present application divides a plurality of intermediate switching frequencies at equal intervals between the first switching frequency and the second switching frequency. The first switching frequency is first switched to the intermediate switching frequency, and then switched from the intermediate switching frequency to the second switching frequency, thereby achieving a continuous switching from the first switching frequency to the second switching frequency from large to small. Using a variable switching frequency to start the motor not only reduces the motor startup time and improves the motor's operating efficiency, but also significantly improves the stability of the motor's operation.

[0151] S37 . Continue to operate the motor in a closed loop based on the second switching frequency to adjust the rotational speed of the rotor until the rotational speed of the rotor reaches a third speed threshold.

[0152] In one embodiment, the motor continues to operate in a closed loop based on the second switching frequency to adjust the speed of the rotor until the speed of the rotor reaches a third speed threshold. The specific execution steps are the same as S32 and S33 and are not repeated here.

[0153] In one embodiment, the second switching frequency is not greater than the first switching frequency, the third speed threshold is not less than the second speed threshold, and the second speed threshold is not less than the first speed threshold.

[0154] S38, complete motor start-up.

[0155] A high switching frequency is used during initial position identification and magnetic polarity determination. Once the motor is running stably, a variable switching frequency strategy is introduced to adjust the switching frequency. Although the switching frequency varies, the motor speed continues to increase until it reaches the third speed threshold, completing the motor startup.

[0156] like Figure 3 As shown, in one embodiment, performing normal motor startup includes the following steps:

[0157] S41, setting a second switching frequency;

[0158] S42: injecting a high-frequency voltage based on the second switching frequency to determine a first position of a rotor of the motor;

[0159] S43, operating the motor in a closed loop according to the first position of the rotor until the rotational speed of the rotor reaches a first speed threshold;

[0160] S44, re-estimating the position of the rotor of the motor to determine a second position of the rotor of the motor;

[0161] S45, operating the motor in a closed loop based on the second position of the rotor until the rotational speed of the rotor reaches a third speed threshold;

[0162] S46, complete motor start-up.

[0163] Compared with the fast motor start-up, the normal motor start-up step lacks the process of adjusting the first switching frequency based on the current temperature information of the switching device and the limiting relationship between the temperature and the switching frequency, and switching the first switching frequency to the second switching frequency. The remaining execution steps are basically the same as S3 and will not be repeated here.

[0164] It should be understood that the division of the modules described above is merely a division of logical functions. In actual implementation, they may be fully or partially integrated into a single physical entity or physically separated. Furthermore, these modules may be implemented entirely as software invoked by a processing element, or entirely as hardware. Alternatively, some modules may be implemented as software invoked by a processing element, while others may be implemented as hardware. For example, module x may be a separate processing element, or integrated into a chip of the aforementioned device. Furthermore, it may be stored in the form of program code in the memory of the aforementioned device, invoked by a processing element of the aforementioned device to perform the functions of module x. The implementation of other modules is similar. Furthermore, these modules may be fully or partially integrated or implemented independently. The processing element described herein may be an integrated circuit with signal processing capabilities. During implementation, the steps of the above method or the modules described above may be performed by hardware integrated logic circuits within the processor element or by software instructions.

[0165] For example, the above modules can be one or more integrated circuits configured to implement the above methods, such as one or more application-specific integrated circuits (ASICs), one or more digital signal processors (DSPs), or one or more field programmable gate arrays (FPGAs). For another example, when a module is implemented by scheduling program code through a processing element, the processing element can be a general-purpose processor, such as a central processing unit (CPU) or other processor that can call program code. For another example, these modules can be integrated together and implemented in the form of a system-on-a-chip (SOC).

[0166] like Figure 5 As shown, in one embodiment of the present invention, the motor starting terminal of the present invention further includes a processor 51 and a memory 52 .

[0167] The memory 52 is used to store computer programs;

[0168] The memory 52 includes various media capable of storing program codes, such as ROM, RAM, magnetic disk, USB flash drive, memory card or optical disk.

[0169] The processor 51 is configured to execute the computer program stored in the memory, so that the terminal executes the motor starting method.

[0170] Preferably, the processor 51 can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0171] In summary, the motor starting method, system, and terminal of the present invention combine both rapid and normal motor starting functions, meeting user needs in various scenarios. The use of variable switching frequency to start the motor significantly reduces the motor starting time, ensuring the success rate and stability of motor starting. The introduction of a temperature parameter to limit the maximum switching frequency protects hardware devices. Therefore, the present invention effectively overcomes the shortcomings of the existing technology and has high industrial application value.

[0172] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A motor starting method, characterized in that: The following steps are involved: Get the motor start command; Determining whether the motor start instruction is a quick start instruction; If yes, a fast motor start is performed; Otherwise, perform normal motor start; Performing a fast motor start involves the following steps: Setting the first switching frequency to the maximum switching frequency; injecting a high frequency voltage based on the first switching frequency to determine a first position of a rotor of the motor; operating the motor in a closed loop based on the first position of the rotor until a rotational speed of the rotor reaches a first speed threshold; re-estimating the position of the rotor of the motor to determine a second position of the rotor of the motor; operating the motor in a closed loop based on the second position of the rotor until the rotational speed of the rotor reaches a second speed threshold; Switching the first switching frequency to a second switching frequency; continuing to operate the motor in a closed loop based on the second switching frequency to adjust the rotational speed of the rotor until the rotational speed of the rotor reaches a third speed threshold; Complete motor start-up; The second switching frequency is not greater than the first switching frequency, the third speed threshold is not less than the second speed threshold, and the second speed threshold is not less than the first speed threshold; Performing a normal motor start involves the following steps: Setting a second switching frequency; injecting a high frequency voltage based on the second switching frequency to determine a first position of a rotor of the motor; operating the motor in a closed loop based on the first position of the rotor until a rotational speed of the rotor reaches a first speed threshold; re-estimating the position of the rotor of the motor to determine a second position of the rotor of the motor; operating the motor in a closed loop based on the second position of the rotor until a rotational speed of the rotor reaches a third speed threshold; Complete motor start-up.

2. The motor starting method according to claim 1, characterized in that: Operating the motor in a closed loop based on the first position of the rotor until the speed of the rotor reaches a first speed threshold includes adjusting the first switching frequency according to temperature; and adjusting the first switching frequency according to temperature includes the following steps: Real-time collection of current temperature information of the switching devices of the motor's inverter or driver; Get the limiting relationship between temperature and switching frequency; The first switching frequency is adjusted based on the current temperature information of the switching device and the limiting relationship between the temperature and the switching frequency, and the adjusted first switching frequency is used as the switching frequency of subsequent closed-loop operation.

3. The motor starting method according to claim 2, characterized in that: To obtain the limiting relationship between temperature and switching frequency, use one or more of the following methods: Obtain the limiting relationship between temperature and switching frequency through experiments; Obtain the limiting relationship between temperature and switching frequency by estimating experimental results; Consult the data sheet to obtain the limiting relationship between temperature and switching frequency.

4. The motor starting method according to claim 2, characterized in that: Adjusting the first switching frequency based on the current temperature information of the switching device and the limiting relationship between the temperature and the switching frequency comprises the following steps: Finding the maximum switching frequency corresponding to the current temperature information of the switching device; Determining whether the first switching frequency is greater than a maximum switching frequency corresponding to the current temperature information of the switching device; If so, the maximum switching frequency corresponding to the current temperature information of the switching device is set as the first switching frequency; otherwise, the first switching frequency remains unchanged.

5. The motor starting method according to claim 1, characterized in that: Switching the first switching frequency to the second switching frequency includes switching the first switching frequency to the second switching frequency according to the rotation time of the rotor; switching the first switching frequency to the second switching frequency according to the rotation time of the rotor includes the following steps: Counting the rotation time of the rotor; When the rotation time of the rotor is greater than a preset time value, the first switching frequency is switched to a second switching frequency.

6. A motor starting system, characterized in that: include: Acquisition module, used to obtain motor start instructions; a judging module, connected to the acquiring module, for judging whether the motor starting instruction is a quick starting instruction; A starting module, the starting module is connected to the judging module, and executes a fast motor start if the motor starting instruction is a fast starting instruction; Otherwise, perform normal motor start; Performing a fast motor start involves the following steps: Setting the first switching frequency to the maximum switching frequency; injecting a high frequency voltage based on the first switching frequency to determine a first position of a rotor of the motor; operating the motor in a closed loop based on the first position of the rotor until a rotational speed of the rotor reaches a first speed threshold; re-estimating the position of the rotor of the motor to determine a second position of the rotor of the motor; operating the motor in a closed loop based on the second position of the rotor until a rotational speed of the rotor reaches a second speed threshold; Switching the first switching frequency to a second switching frequency; continuing to operate the motor in a closed loop based on the second switching frequency to adjust the rotational speed of the rotor until the rotational speed of the rotor reaches a third speed threshold; Complete motor start-up; The second switching frequency is not greater than the first switching frequency, the third speed threshold is not less than the second speed threshold, and the second speed threshold is not less than the first speed threshold; Performing a normal motor start involves the following steps: Setting the second switching frequency; injecting a high frequency voltage based on the second switching frequency to determine a first position of a rotor of the motor; operating the motor in a closed loop based on the first position of the rotor until a rotational speed of the rotor reaches a first speed threshold; re-estimating the position of the rotor of the motor to determine a second position of the rotor of the motor; operating the motor in a closed loop based on the second position of the rotor until the rotational speed of the rotor reaches a third speed threshold; Complete motor start-up.

7. A motor starting terminal, characterized in that: include: processor and memory; The memory is used to store computer programs; The processor is configured to execute the computer program stored in the memory, so as to enable the terminal to execute the motor starting method according to any one of claims 1 to 5.

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