CN115021628A - Motor starting method, system and terminal - Google Patents
Motor starting method, system and terminal Download PDFInfo
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- CN115021628A CN115021628A CN202210850948.0A CN202210850948A CN115021628A CN 115021628 A CN115021628 A CN 115021628A CN 202210850948 A CN202210850948 A CN 202210850948A CN 115021628 A CN115021628 A CN 115021628A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
- H02P6/20—Arrangements for starting
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
- H02P6/14—Electronic commutators
- H02P6/16—Circuit arrangements for detecting position
- H02P6/18—Circuit arrangements for detecting position without separate position detecting elements
- H02P6/182—Circuit arrangements for detecting position without separate position detecting elements using back-emf in windings
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
- H02P6/14—Electronic commutators
- H02P6/16—Circuit arrangements for detecting position
- H02P6/18—Circuit arrangements for detecting position without separate position detecting elements
- H02P6/183—Circuit arrangements for detecting position without separate position detecting elements using an injected high frequency signal
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P2207/00—Indexing scheme relating to controlling arrangements characterised by the type of motor
- H02P2207/05—Synchronous machines, e.g. with permanent magnets or DC excitation
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P80/00—Climate change mitigation technologies for sector-wide applications
- Y02P80/10—Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier
Abstract
The invention provides a motor starting method, a system and a terminal, comprising the following steps: acquiring a motor starting instruction; judging whether the motor starting instruction is a quick starting instruction or not; if so, executing the quick motor starting; otherwise, executing normal motor starting. The motor starting method, the system and the terminal have the advantages that two functions of quick motor starting and normal motor starting are considered, and the use requirements of users in different scenes are met; the motor is started by adopting the variable switching frequency, so that the starting time of the motor is obviously reduced, and the success rate and the stability of the starting of the motor are ensured; and the maximum switching frequency is limited by introducing temperature parameters, so that hardware equipment is protected.
Description
Technical Field
The invention relates to the technical field of motor starting, in particular to a motor starting method, a motor starting system and a motor starting terminal.
Background
In some motor product applications, the motor is required to reach a target speed in a short time to achieve start-up. Generally, the magnitude of the back emf of the motor is proportional to the rotational speed. Because the rotating speed of the motor is very low when the motor is static or just started, the counter electromotive force is very small, the position of the rotor cannot be determined according to the counter electromotive force signal, and the position of the rotor can be estimated based on the counter electromotive force after the rotating speed is accelerated to be large enough, and then the closed-loop operation state is switched. Therefore, the long time required for the initial position identification of the motor rotor and the zero low-speed acceleration of the motor is a main reason for the time consumption of the motor starting.
Due to the limitations of cost, application environment and the like, a plurality of motor products are not provided with position sensors, namely, the motor is controlled to operate by using a position sensor-free control technology. The control algorithm without the position sensor is mainly divided into a high-frequency injection method and an observer based on back electromotive force, and since the position sensor is generally provided with a PI (proportional integral) regulator, and the speed and the precision of the PI regulator are contradictory to each other, the position of a rotor cannot be quickly and accurately estimated on the premise that sampling data and switching frequency are not changed, and further the success rate and the stability of motor starting cannot be ensured.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a motor starting method, system and terminal, which are used to solve the technical problem of long motor starting time in the prior art. Compared with the existing motor starting method, the invention simultaneously considers two functions of quick motor starting and normal motor starting, and meets the use requirements of users in different scenes.
In order to achieve the above objects and other related objects, the present invention provides a motor starting method, system and terminal, including the steps of: acquiring a motor starting instruction; judging whether the motor starting instruction is a quick starting instruction or not; if so, executing the quick motor starting; otherwise, executing normal motor starting.
In one embodiment of the present invention, performing a fast motor start includes the steps of:
setting the first switching frequency as a maximum switching frequency;
injecting a high frequency voltage based on the first switching frequency to determine a first position of a rotor of the electric machine;
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;
re-estimating the position of the rotor of the electric machine to determine a second position of the rotor of the electric machine;
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;
and finishing the starting of the motor.
In one embodiment of the 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 comprises adjusting the first switching frequency according to a temperature; the adjusting the first switching frequency according to the temperature comprises the following steps:
acquiring current temperature information of a switching device of an inverter or a driver of a motor in real time;
acquiring a limit relation between temperature and switching frequency;
and adjusting the first switching frequency based on the current temperature information of the switching device and the limit relation between the temperature and the switching frequency, and taking the adjusted first switching frequency as the switching frequency of the subsequent closed-loop operation.
In an embodiment of the present invention, the restriction relationship between the temperature and the switching frequency is obtained by one or more of the following methods:
acquiring a limiting relation between temperature and switching frequency through experiments;
obtaining a limit relation between temperature and switching frequency by estimating an experimental result;
the limiting relationship of temperature and switching frequency is obtained by referring to a data manual.
In an 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 the subsequent closed-loop operation includes the following steps:
searching a maximum value of the switching frequency corresponding to the current temperature information of the switching device;
judging whether the first switching frequency is larger than the maximum value of the switching frequency corresponding to the current temperature information of the switching device or not;
if so, setting the maximum value of the switching frequency corresponding to the current temperature information of the switching device as a first switching frequency; otherwise the first switching frequency remains unchanged.
In an 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 a rotation time of the rotor; the switching the first switching frequency to the second switching frequency according to the rotation time of the rotor includes the steps of:
counting the rotation time of the rotor;
and when the rotation time of the rotor is greater than a preset time value, switching the first switching frequency to be a second switching frequency.
In an embodiment of the 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.
In one embodiment of the present invention, executing normal motor starting includes 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 electric machine;
the motor is operated in a closed loop according to the first position of the rotor until the rotating speed of the rotor reaches a first speed threshold value;
re-estimating the position of the rotor of the electric machine to determine a second position of the rotor of the electric machine;
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;
and finishing the starting of the motor.
Correspondingly, the invention provides a motor starting system, comprising:
the acquisition module is used for acquiring a motor starting instruction;
the judging module is connected with the acquiring module and is used for judging whether the motor starting instruction is a quick starting instruction or not;
the starting module is connected with the judging module, and if the motor starting instruction is a quick starting instruction, the quick motor starting is executed; otherwise, executing normal motor starting.
Correspondingly, the invention provides a motor starting terminal, which comprises: a processor and a memory;
the memory is used for storing a computer program;
the processor is configured to execute the computer program stored in the memory to cause the terminal to perform the motor starting method according to any one of claims 1 to 8.
As described above, the motor starting method, system and terminal of the present invention have the following beneficial effects:
(1) the two functions of quick motor starting and normal motor starting are considered, and the use requirements of users in different scenes are met;
(2) the motor is started by adopting the variable switching frequency, so that the starting time of the motor is obviously reduced, and the success rate and the stability of the starting of the motor are ensured;
(3) and the maximum switching frequency is limited by introducing temperature parameters, so that hardware equipment is protected.
Drawings
Fig. 1 is a flowchart illustrating a motor starting method according to an embodiment of the present invention.
Fig. 2 is a flow chart illustrating a fast motor starting method according to an embodiment of the present invention.
Fig. 3 is a flowchart illustrating a normal motor starting method according to an embodiment of the present invention.
Fig. 4 is a schematic structural diagram of a motor starting system according to an embodiment of the invention.
Fig. 5 is a schematic structural diagram of a motor start terminal according to an embodiment of the invention.
Description of the element reference numerals
41 acquisition module
42 judging module
43 starting module
51 processor
52 memory
S1-S4 motor starting method steps
S31-S38 quick motor starting method steps
S41-S46 normal motor starting method steps
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
It should be noted that the drawings provided in the present application are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the form, quantity and proportion of each component in actual implementation may be changed freely, and the layout of the components may be more complicated.
In addition, the descriptions related to "first", "second", etc. in the present invention are only for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.
The permanent magnet synchronous motor comprises a stator winding, a rotor, an end cover and the like, and can be divided into a surface-mounted permanent magnet synchronous motor and a built-in permanent magnet synchronous motor according to different positions of permanent magnets on the rotor. Specifically, the permanent magnet of the interior permanent magnet synchronous motor is positioned inside the rotor, and the permanent magnet of the surface-mounted permanent magnet synchronous motor is positioned on the outer surface of the rotor core. The motor starting method is described by taking an internal permanent magnet synchronous motor as an example.
As shown in fig. 1, in an embodiment, the motor starting method of the present invention includes the following steps:
and step S1, acquiring a motor starting instruction.
In an embodiment, the motor start command of the present invention is a fast motor start command or a normal motor start command. In an embodiment, the driver obtains the fast motor starting instruction or the normal motor starting instruction sent by the upper computer in a serial port communication mode.
And step S2, judging whether the motor starting instruction is a quick starting instruction.
In one embodiment, the present invention selects whether to start the motor quickly based on the actual application. For example, for a motor with a high power load, a normal motor start command needs to be obtained to achieve the start of the motor. Because the impulse current at the moment of starting the motor is several times or even dozens of times of the normal rated current, the current starts to be slowly reduced along with the acceleration of the rotating speed, and the current cannot be reduced to the normal level until the rotating speed is increased to the normal range. The normal starting of the motor can prevent the local insulation part from being broken down by current due to the fact that the instantaneous current is too large, and therefore the service life of the motor is guaranteed. However, the motor is normally started for too long time, which not only increases the system loss, but also reduces the working efficiency. In order to effectively reduce the starting time of the motor, a quick motor starting instruction can be obtained to realize the starting of the motor. The motor starting method and the motor starting device have the advantages that two functions of quick motor starting and normal motor starting are considered, and the use requirements of users in different scenes are met.
And step S3, if yes, executing the quick motor starting.
As shown in fig. 2, in one embodiment, performing a fast motor start includes the following steps:
and S31, setting the first switching frequency as the maximum switching frequency.
Specifically, the application takes the maximum switching frequency recommended by the data manual as the first switching frequency. Experimental research shows that the switching frequency is in direct proportion to the position estimation time of the rotor, namely the high switching frequency can obviously reduce the time required by initial position estimation, and the higher the switching frequency is, the smaller the vibration of the motor is, the lower the running noise is, and the smaller the heating of the motor is; however, the higher the switching frequency, the higher the switching loss, and the lower the system efficiency under the premise of no change in output power. In order to guarantee the overall operation efficiency of the motor, a higher switching frequency is selected as far as possible in the starting stage.
And S32, injecting high-frequency voltage based on the first switching frequency to determine the first position of the rotor of the motor.
When the motor is at rest, the initial position of the rotor is not known. When the motor is started under the condition that the initial position of the rotor is unknown, the problems that the starting current of the motor is too large, the motor cannot be started, even the rotor rotates reversely and the like can be caused; if the initial position detection error of the rotor of the motor is large, the estimation precision of the position of the rotor can be directly influenced, so that the motor runs disorderly and cannot run normally. In one embodiment, the initial position of the motor rotor is identified by a high-frequency injection method, so that the accuracy and reliability of the identification of the initial position of the rotor are improved. The essence of the high frequency injection method is that the modulation effect generated by the salient pole structure or salient pole effect of the motor rotor is utilized to realize the identification of the rotor position. However, the high-frequency injection method cannot identify the polarity of the magnetic pole of the rotor, and if the polarity of the magnetic pole is identified and dislocated, the rotor position generates 180-degree phase deviation, so that the starting failure of the motor is caused, and the loading capacity of the motor is limited. In one embodiment, the method identifies the magnetic pole polarity of the rotor after determining the initial position of the rotor of the motor, and the specifically adopted magnetic pole polarity judgment method is a transient short pulse injection method or a second harmonic method based on a cross saturation effect. In one embodiment, after the initial position and the magnetic pole polarity of the rotor of the motor are determined, the high-frequency voltage is continuously injected to determine the first position of the rotor of the motor.
S33, the motor is operated in a closed loop mode based on the first position of the rotor of the motor until the rotating speed of the rotor reaches a first speed threshold value.
In one embodiment, the present invention employs a first speed control system that operates the motor in a closed loop based on a first position of a rotor of the motor. Specifically, in the first speed control system, the rotating speed of the rotor is fed back to the input end as an output quantity to be compared with a given speed, and the running speed of the motor is regulated and controlled by using the obtained deviation signal until the rotating speed of the rotor reaches a first speed threshold value. The first speed control system improves the tracking and positioning accuracy at a given speed, realizes automatic acceleration control, can obtain higher running speed, more stable and smoother rotating speed than open-loop control, and greatly improves the performance of the motor.
In one embodiment, 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 comprises adjusting the first switching frequency as a function of temperature; the adjusting the first switching frequency according to the temperature comprises the following steps:
(1) the current temperature information of a switching device of an inverter or a driver of the motor is collected in real time. The switching device of the inverter or driver of the motor 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). According to different types of the switching devices, different temperature measuring methods are correspondingly adopted. Specifically, for a switching device with a temperature sensor, the current temperature information of the switching device can be directly obtained by utilizing the temperature output function of the switching device; for a switching device without a temperature sensor, the current temperature information of the switching device can be indirectly acquired by utilizing an external temperature acquisition circuit. In an embodiment, the switch device adopted in the present application is an MOSFET, and since there is no temperature sensor in the MOSFET, a temperature acquisition circuit needs to be externally provided when acquiring the current temperature information of the MOSFET, wherein the temperature acquisition circuit at least includes a temperature sensitive resistor. When the temperature of the MOSFET acquisition point changes, the resistance value of the MOSFET changes correspondingly, and the temperature value corresponding to the current resistance value can be calculated according to the conversion relation between the resistance value and the temperature, wherein the temperature value is the current temperature information of the MOSFET. In another embodiment of the present invention, when the adopted switching device is an IPM, the current temperature information of the IPM can be directly obtained by using the temperature output function thereof.
(2) The limiting relationship of temperature and switching frequency is obtained. In one embodiment, the limit relationship between the temperature and the switching frequency is obtained by one or more of the following methods:
obtaining a limit relation between temperature and switching frequency through experiments;
obtaining a limit relation between temperature and switching frequency by estimating an experimental result;
the limiting relationship of temperature and switching frequency is obtained by referring to a data manual.
(3) And adjusting the first switching frequency based on the current temperature information of the switching device and the limit relation between the temperature and the switching frequency, and taking the adjusted first switching frequency as the switching frequency of the subsequent closed-loop operation. In one embodiment, adjusting the first switching frequency based on the current temperature information of the switching device and the limit relationship between the temperature and the switching frequency comprises:
searching a maximum value of the switching frequency corresponding to the current temperature information of the switching device;
judging whether the first switching frequency is larger than the maximum value of the switching frequency corresponding to the current temperature information of the switching device or not;
if so, setting the maximum value of the switching frequency corresponding to the current temperature information of the switching device as a first switching frequency; otherwise the first switching frequency remains unchanged.
The maximum switching frequency is limited by introducing a temperature parameter, so that hardware equipment is prevented from being burnt out due to overhigh temperature.
And S34, re-estimating the position of the rotor of the motor to determine a second position of the rotor of the motor.
When an electric pulse is input into the stator winding, the stator winding can generate a vector magnetic field, and when the vector magnetic field of the stator winding rotates for an angle, the magnetic field can drive the rotor to rotate for an angle, so that the directions of a pair of magnetic fields of the rotor and the magnetic field of the stator are always kept consistent. When the rotor rotates, an induced potential, i.e., a back-emf, is generated in the stator windings.
When the rotational speed of the rotor reaches a first speed threshold value, the back emf in the stator windings reaches a preset value, on the basis of which the position of the rotor of the electrical machine can be estimated. In one embodiment, the present application uses a back emf-based position sensorless control to estimate the rotor position to determine the second position of the rotor of the electric machine.
And S35, the motor is operated in a closed loop mode based on the second position of the rotor until the rotating speed of the rotor reaches a second speed threshold value.
In an embodiment, the second speed control system is adopted in the present invention, and the second speed control system operates the motor in a closed loop based on the second position of the rotor, and the specific steps are the same as the first speed control system in S33, which are not described herein again.
And S36, switching the first switching frequency to be a second switching frequency.
In an embodiment, when the rotation speed of the rotor reaches the second speed threshold, the first switching frequency is switched to the second switching frequency.
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; the switching the first switching frequency to the second switching frequency according to the rotation time of the rotor includes the steps of:
counting the rotation time of the rotor;
and when the rotation time of the rotor is greater than a preset time value, switching the first switching frequency to a second switching frequency.
And an intermediate transition process is needed for switching the first switching frequency to the second switching frequency, otherwise, the system is easy to lose control. In an embodiment, the present application divides a plurality of intermediate switching frequencies at equal intervals between a first switching frequency and a second switching frequency, and switches the first switching frequency to the intermediate switching frequency first, and then switches the intermediate switching frequency to the second switching frequency, so as to realize continuous switching from the first switching frequency to the second switching frequency from large to small. The motor is started by adopting the variable switching frequency, so that the starting time of the motor is shortened, the running efficiency of the motor is improved, and the running stability of the motor is obviously improved.
And S37, continuing to operate the motor in a closed loop mode based on the second switching frequency to adjust the rotating speed of the rotor until the rotating speed of the rotor reaches a third speed threshold value.
In an embodiment, the motor continues to operate in the closed loop based on the second switching frequency to adjust the rotation speed of the rotor until the rotation speed of the rotor reaches the third speed threshold, which is the same as steps S32 and S33, and is not described herein again.
In an 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.
And S38, finishing the motor starting.
The high switching frequency is used during initial position identification and magnetic pole polarity judgment, and once the motor stably runs, a variable switching frequency strategy is introduced to adjust the switching frequency. At this time, although the value of the switching frequency varies, the rotation speed of the motor continues to increase until reaching the third speed threshold, and the motor start is completed.
And step S4, otherwise, executing normal motor starting.
As shown in fig. 3, in one embodiment, performing a normal motor start includes the following steps:
s41, setting a second switching frequency;
s42, injecting high-frequency voltage based on the second switching frequency to determine a first position of a rotor of the motor;
s43, operating the motor in a closed loop according to the first position of the rotor until the rotating speed of the rotor reaches a first speed threshold value;
s44, re-estimating the position of the rotor of the motor to determine a second position of the rotor of the motor;
s45, the motor is operated in a closed loop mode based on the second position of the rotor until the rotating speed of the rotor reaches a third speed threshold value;
and S46, finishing the motor starting.
Compared with the fast motor starting, the normal motor starting step lacks a process of adjusting the first switching frequency based on the current temperature information of the switching device and the limiting relation between the temperature and the switching frequency, and switching the first switching frequency to be the second switching frequency, and other execution steps are basically the same as S3, and are not repeated here.
As shown in fig. 4, in one embodiment, the motor starting system of the present invention includes:
and the obtaining module 41 is used for obtaining a motor starting instruction.
In an embodiment, the motor start command of the present invention is a fast motor start command or a normal motor start command. In an embodiment, the driver obtains the fast motor starting instruction or the normal motor starting instruction sent by the upper computer in a serial port communication mode.
And the judging module 42, where the judging module 42 is connected to the obtaining module 41, and is configured to judge whether the motor starting instruction is a quick starting instruction.
In one embodiment, the present invention selects whether to start the motor quickly based on the actual application. For example, for a motor with a high power load, a normal motor start command needs to be obtained to achieve the start of the motor. Because the impulse current at the moment of starting the motor is several times or even dozens of times of the normal rated current, the current starts to be slowly reduced along with the acceleration of the rotating speed, and the current cannot be reduced to the normal level until the rotating speed is increased to the normal range. The normal starting of the motor can prevent the local insulation part from being broken down by current due to the fact that the instantaneous current is too large, and therefore the service life of the motor is guaranteed. However, the motor is normally started for too long time, which not only increases the system loss, but also reduces the working efficiency. In order to effectively reduce the starting time of the motor, a quick motor starting instruction can be obtained to realize the starting of the motor. The motor starting method and the motor starting device have the advantages that two functions of quick motor starting and normal motor starting are considered, and the use requirements of users in different scenes are met.
The starting module 43, the starting module 43 is connected to the judging module 42, and if the motor starting instruction is a quick starting instruction, the quick motor starting is executed; otherwise, executing normal motor starting.
As shown in fig. 2, in one embodiment, performing a fast motor start includes the following steps:
and S31, setting the first switching frequency as the maximum switching frequency.
Specifically, the application takes the maximum switching frequency recommended by the data manual as the first switching frequency. Experimental research shows that the switching frequency is in direct proportion to the position estimation time of the rotor, namely the high switching frequency can obviously reduce the time required by initial position estimation, and the higher the switching frequency is, the smaller the vibration of the motor is, the lower the running noise is, and the smaller the heating of the motor is; but simultaneously, the higher the switching frequency is, the higher the frequency of the harmonic current is, the larger the motor loss is, and the smaller the output power is. In order to guarantee the overall operation efficiency of the motor, a high switching frequency is selected as far as possible in the starting stage, and a relatively low switching frequency is selected to stably operate the motor after the starting is finished.
And S32, injecting high-frequency voltage based on the first switching frequency to determine the first position of the rotor of the motor.
When the motor is at rest, the initial position of the rotor is not known. When the motor is started under the condition that the initial position of the rotor is unknown, the problems that the starting current of the motor is too large, the motor cannot be started, even the rotor rotates reversely and the like can be caused; if the initial position detection error of the rotor of the motor is large, the estimation precision of the position of the rotor can be directly influenced, so that the motor runs disorderly and cannot run normally. In one embodiment, the initial position of the motor rotor is identified by a high-frequency injection method, so that the accuracy and reliability of the identification of the initial position of the rotor are improved. The essence of the high frequency injection method is that the modulation effect generated by the salient pole structure or salient pole effect of the motor rotor is utilized to realize the identification of the rotor position. However, the high-frequency injection method cannot identify the polarity of the magnetic pole of the rotor, and if the polarity of the magnetic pole is identified and dislocated, the rotor position generates 180-degree phase deviation, so that the starting failure of the motor is caused, and the loading capacity of the motor is limited. In one embodiment, the method identifies the magnetic pole polarity of the rotor after determining the initial position of the rotor of the motor, and the specifically adopted magnetic pole polarity judgment method is a transient short pulse injection method or a second harmonic method based on a cross saturation effect. In one embodiment, after the initial position and the magnetic pole polarity of the rotor of the motor are determined, the high-frequency voltage is continuously injected to determine the first position of the rotor of the motor.
S33, the motor is operated in a closed loop mode based on the first position of the rotor of the motor until the rotating speed of the rotor reaches a first speed threshold value.
In one embodiment, the present invention employs a first speed control system that operates the motor in a closed loop based on a first position of a rotor of the motor. Specifically, in the first speed control system, the rotating speed of the rotor is fed back to the input end as an output quantity to be compared with a given speed, and the running speed of the motor is regulated and controlled by using the obtained deviation signal until the rotating speed of the rotor reaches a first speed threshold value. The first speed control system improves the tracking and positioning accuracy at a given speed, realizes automatic acceleration control, can obtain higher running speed, more stable and smoother rotating speed than open-loop control, and greatly improves the performance of the motor.
In one embodiment, closed-loop operating the motor based on the first position of the rotor until the rotational speed of the rotor reaches a first speed threshold comprises adjusting the first switching frequency as a function of temperature; the adjusting the first switching frequency according to the temperature comprises the following steps:
(1) the current temperature information of a switching device of an inverter or a driver of the motor is collected in real time. The switching device of the inverter or the driver of the motor 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). According to different types of the switching devices, different temperature measuring methods are correspondingly adopted. Specifically, for a switching device with a temperature sensor, the current temperature information of the switching device can be directly obtained by utilizing the temperature output function of the switching device; for a switching device without a temperature sensor, the current temperature information of the switching device can be indirectly acquired by utilizing an external temperature acquisition circuit. In an embodiment, the switch device adopted in the present application is an MOSFET, and since there is no temperature sensor in the MOSFET, a temperature acquisition circuit needs to be externally provided when acquiring the current temperature information of the MOSFET, wherein the temperature acquisition circuit at least includes a temperature sensitive resistor. When the temperature of the MOSFET acquisition point changes, the self resistance value of the MOSFET changes correspondingly, and the temperature value corresponding to the current resistance value can be calculated according to the conversion relation between the resistance value and the temperature, wherein the temperature value is the current temperature information of the MOSFET. In another embodiment of the present invention, when the adopted switch device is an IPM, the current temperature information of the IPM can be directly obtained by using the temperature output function thereof.
(2) The limiting relationship of temperature and switching frequency is obtained. In one embodiment, the limit relationship between the temperature and the switching frequency is obtained by one or more of the following methods:
acquiring a limiting relation between temperature and switching frequency through experiments;
obtaining a limit relation between temperature and switching frequency by estimating an experimental result;
the limiting relationship of temperature and switching frequency is obtained by referring to a data manual.
(3) And adjusting the first switching frequency based on the current temperature information of the switching device and the limit relation between the temperature and the switching frequency, and taking the adjusted first switching frequency as the switching frequency of the 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 comprises:
searching a maximum value of the switching frequency corresponding to the current temperature information of the switching device;
judging whether the first switching frequency is larger than the maximum value of the switching frequency corresponding to the current temperature information of the switching device or not;
if so, setting the maximum value of the switching frequency corresponding to the current temperature information of the switching device as a first switching frequency; otherwise the first switching frequency remains unchanged.
The maximum switching frequency is limited by introducing a temperature parameter, so that hardware equipment is prevented from being burnt out due to overhigh temperature.
And S34, re-estimating the position of the rotor of the motor to determine a second position of the rotor of the motor.
When an electric pulse is input into the stator winding, the stator winding can generate a vector magnetic field, and when the vector magnetic field of the stator winding rotates for an angle, the magnetic field can drive the rotor to rotate for an angle, so that the directions of a pair of magnetic fields of the rotor and the magnetic field of the stator are always kept consistent. When the rotor rotates, an induced potential, i.e., a back-emf, is generated in the stator windings.
When the speed of the rotor reaches a first speed threshold, the back emf in the stator windings reaches a preset value, on the basis of which the position of the rotor of the electrical machine can be estimated. In one embodiment, the present application uses a back emf-based position sensorless control to estimate the rotor position to determine the second position of the rotor of the electric machine.
And S35, the motor is operated in a closed loop mode based on the second position of the rotor until the rotating speed of the rotor reaches a second speed threshold value.
In an embodiment, the second speed control system is adopted in the present invention, and the second speed control system operates the motor in a closed loop based on the second position of the rotor, and the specific steps are the same as the first speed control system in S33, which are not described herein again.
And S36, switching the first switching frequency to be a second switching frequency.
In an embodiment, when the rotation speed of the rotor reaches the second speed threshold, the first switching frequency is switched to the second switching frequency.
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; the switching the first switching frequency to the second switching frequency according to the rotation time of the rotor includes the steps of:
counting the rotation time of the rotor;
and when the rotation time of the rotor is greater than a preset time value, switching the first switching frequency to be a second switching frequency.
And an intermediate transition process is needed for switching the first switching frequency to the second switching frequency, otherwise, the system is easy to lose control. In an embodiment, the present application divides a plurality of intermediate switching frequencies at equal intervals between a first switching frequency and a second switching frequency, and switches the first switching frequency to the intermediate switching frequency first, and then switches the intermediate switching frequency to the second switching frequency, so as to realize continuous switching from the first switching frequency to the second switching frequency from large to small. The motor is started by adopting the variable switching frequency, so that the starting time of the motor is shortened, the running efficiency of the motor is improved, and the running stability of the motor is obviously improved.
And S37, continuing to operate the motor in a closed loop mode based on the second switching frequency to adjust the rotating speed of the rotor until the rotating speed of the rotor reaches a third speed threshold value.
In an embodiment, the motor continues to operate in the closed loop based on the second switching frequency to adjust the rotation speed of the rotor until the rotation speed of the rotor reaches the third speed threshold, which is the same as steps S32 and S33, and is not described herein again.
In an 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.
And S38, finishing the motor starting.
The high switching frequency is used during initial position identification and magnetic pole polarity judgment, and once the motor stably runs, a variable switching frequency strategy is introduced to adjust the switching frequency. At this time, although the value of the switching frequency varies, the rotation speed of the motor continues to increase until reaching the third speed threshold, and the motor start is completed.
As shown in fig. 3, in one embodiment, performing a normal motor start includes the following steps:
s41, setting a second switching frequency;
s42, injecting high-frequency voltage based on the second switching frequency to determine a first position of a rotor of the motor;
s43, operating the motor in a closed loop according to the first position of the rotor until the rotating speed of the rotor reaches a first speed threshold value;
s44, re-estimating the position of the rotor of the motor to determine a second position of the rotor of the motor;
s45, the motor is operated in a closed loop mode based on the second position of the rotor until the rotating speed of the rotor reaches a third speed threshold value;
and S46, finishing the motor starting.
Compared with the fast motor starting, the normal motor starting step lacks a process of adjusting the first switching frequency based on the current temperature information of the switching device and the limiting relation between the temperature and the switching frequency, and switching the first switching frequency to be the second switching frequency, and other execution steps are basically the same as S3, and are not repeated here.
It should be noted that the above division of each module is only a division of a logic function, and the actual implementation may be wholly or partially integrated into one physical entity, or may be physically separated. And these modules can all be implemented in the form of software invoked by a processing element; or may be implemented entirely in hardware; and part of the modules can be realized in the form of calling software by the processing element, and part of the modules can be realized in the form of hardware. For example, the x module may be a processing element that is set up separately, or may be implemented by being integrated in a chip of the apparatus, or may be stored in a memory of the apparatus in the form of program code, and the function of the x module may be called and executed by a processing element of the apparatus. Other modules are implemented similarly. In addition, all or part of the modules can be integrated together or can be independently realized. The processing element described herein may be an integrated circuit having signal processing capabilities. In implementation, each step of the above method or each module above may be implemented by an integrated logic circuit of hardware in a processor element or an instruction in the form of software.
For example, the above modules may be one or more integrated circuits configured to implement the above methods, such as: one or more Application Specific Integrated Circuits (ASICs), or one or more microprocessors (DSPs), or one or more Field Programmable Gate Arrays (FPGAs), etc. For another example, when one of the above modules is implemented in the form of a processing element scheduler code, the processing element may be a general-purpose processor, such as a Central Processing Unit (CPU) or other processor capable of calling program code. For another example, these modules may be integrated together and implemented in the form of a system-on-a-chip (SOC).
As shown in fig. 5, in an embodiment of the present invention, the motor starting terminal of the present invention further includes a processor 51 and a memory 52.
The memory 52 is used for storing computer programs;
the memory 52 includes: various media that can store program codes, such as ROM, RAM, magnetic disk, U-disk, memory card, or optical disk.
The processor 51 is configured to execute the computer program stored in the memory, so as to enable the terminal to execute the motor starting method.
Preferably, the Processor 51 may be a general-purpose Processor, including a Central Processing Unit (CPU), a Network Processor (NP), and the like; the Integrated Circuit may also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic device, or discrete hardware components.
In conclusion, the motor starting method, the system and the terminal have two functions of quick motor starting and normal motor starting, and meet the use requirements of users in different scenes; the motor is started by adopting the variable switching frequency, so that the starting time of the motor is obviously reduced, and the success rate and the stability of the starting of the motor are ensured; and the maximum switching frequency is limited by introducing temperature parameters, so that hardware equipment is protected. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (10)
1. A method of starting a motor, comprising the steps of:
acquiring a motor starting instruction;
judging whether the motor starting instruction is a quick starting instruction or not;
if so, executing the quick motor starting; otherwise, executing normal motor starting.
2. A motor starting method according to claim 1, characterized in that performing a fast motor start comprises the steps of:
setting the first switching frequency as a maximum switching frequency;
injecting a high frequency voltage based on the first switching frequency to determine a first position of a rotor of the electric machine;
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;
re-estimating the position of the rotor of the electric machine to determine a second position of the rotor of the electric machine;
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;
and finishing the starting of the motor.
3. The motor starting method of claim 2 wherein 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 comprises adjusting the first switching frequency as a function of temperature; the adjusting the first switching frequency according to the temperature comprises the following steps:
acquiring current temperature information of a switching device of an inverter or a driver of a motor in real time;
acquiring a limit relation between temperature and switching frequency;
and adjusting the first switching frequency based on the current temperature information of the switching device and the limit relation between the temperature and the switching frequency, and taking the adjusted first switching frequency as the switching frequency of the subsequent closed-loop operation.
4. A method for starting a motor according to claim 3, characterized in that the limiting relationship between temperature and switching frequency is obtained in one or more of the following ways:
acquiring a limiting relation between temperature and switching frequency through experiments;
obtaining a limit relation between temperature and switching frequency by estimating an experimental result;
the limiting relationship of temperature and switching frequency is obtained by referring to a data manual.
5. A motor starting method according to claim 3, characterized in that adjusting said first switching frequency based on the current temperature information of said switching device and said limiting relation of temperature and switching frequency comprises the steps of:
searching a maximum value of the switching frequency corresponding to the current temperature information of the switching device;
judging whether the first switching frequency is larger than the maximum value of the switching frequency corresponding to the current temperature information of the switching device or not;
if so, setting the maximum value of the switching frequency corresponding to the current temperature information of the switching device as a first switching frequency; otherwise the first switching frequency remains unchanged.
6. The motor starting method according to claim 2, wherein switching the first switching frequency to the second switching frequency comprises switching the first switching frequency to the second switching frequency according to a rotation time of a rotor; the switching the first switching frequency to the second switching frequency according to the rotation time of the rotor includes the steps of:
counting the rotation time of the rotor;
and when the rotation time of the rotor is greater than a preset time value, switching the first switching frequency to be a second switching frequency.
7. A motor start method according to claim 2, characterized in that 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.
8. A motor starting method according to claim 1, characterized in that performing a normal motor start comprises the steps of:
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 electric machine;
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;
re-estimating the position of the rotor of the electric machine to determine a second position of the rotor of the electric machine;
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;
and finishing the starting of the motor.
9. A motor starting system, comprising:
the acquisition module is used for acquiring a motor starting instruction;
the judging module is connected with the acquiring module and is used for judging whether the motor starting instruction is a quick starting instruction or not;
the starting module is connected with the judging module, and if the motor starting instruction is a quick starting instruction, quick motor starting is executed; otherwise, executing normal motor starting.
10. A motor start terminal, comprising: a processor and a memory;
the memory is used for storing a computer program;
the processor is configured to execute the computer program stored in the memory to cause the terminal to perform the motor starting method according to any one of claims 1 to 8.
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| CN202210850948.0A CN115021628A (en) | 2022-07-19 | 2022-07-19 | Motor starting method, system and terminal |
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