CN111245310A - Asynchronous starting permanent magnet synchronous motor quick starting method based on torque characteristics - Google Patents
Asynchronous starting permanent magnet synchronous motor quick starting method based on torque characteristics Download PDFInfo
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- 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
- H02P1/00—Arrangements for starting electric motors or dynamo-electric converters
- H02P1/16—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters
- H02P1/46—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters for starting an individual synchronous motor
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Abstract
The invention discloses a quick starting method of an asynchronous starting permanent magnet synchronous motor based on torque characteristics, which organically combines asynchronous self-starting with phase jump type maximum synchronous torque starting. According to the torque characteristics of the motor in the starting process, the maximum permanent magnet synchronous torque is utilized to make up the stage insufficient output of the asynchronous synthetic torque, and the purpose of outputting the maximum torque to start the motor is achieved. The starting method provided by the invention has the advantages that the maximum starting torque which can be provided by the motor under two starting modes of asynchronous starting and maximum synchronous torque starting is realized, the maximization of the starting torque of the motor is ensured, the starting time is shortened, the starting capability of the motor is improved, and the problems that the asynchronous starting permanent magnet synchronous motor fails to start or cannot involve synchronization in the later starting period due to overlarge power generation braking torque are effectively solved.
Description
Technical Field
The invention relates to the field of asynchronous starting permanent magnet synchronous motors, in particular to a quick starting method for ensuring the maximum torque starting of an asynchronous starting permanent magnet motor and shortening the starting time.
Background
When the asynchronous starting permanent magnet synchronous motor is started, the three-phase alternating current power supply can be directly connected for starting, and when the rotor of the asynchronous starting permanent magnet synchronous motor is driven to synchronous rotation speed and stably runs, the asynchronous starting permanent magnet synchronous motor has the advantages of high power factor, high efficiency and the like. Because of its convenient starting and energy saving, it is gradually replacing asynchronous AC motor in many application occasions. However, the asynchronous starting permanent magnet synchronous motor rotor is provided with both a cage bar or a conductive sleeve for starting and a permanent magnet, and the starting process is more complicated than that of a common induction motor. The resultant torque of the starting process is defined by the asynchronous torque TaGenerating braking torque TgReluctance negative sequence component torque TbAnd pulsating torque. In which the main driving action is exerted by asynchronous torque TaIn the later stage of the starting process, the asynchronous torque is reduced along with the reduction of the slip ratio, in addition, the magnitude of the power generation braking torque of the permanent magnet is firstly increased and then reduced along with the increase of the rotating speed of the motor, and in the asynchronous starting process, the resultant torque is reduced in a staged manner. The mutual restriction of various torques affects and the asynchronous torque and the synchronous torque of the motor cannot be sufficiently and effectively utilized. Especially, in some application occasions where the steady-state load torque is not large but the load moment of inertia is large, such as an asynchronous starting permanent magnet synchronous motor for chemical fiber machinery, a phenomenon of too long starting time can occur, and even a series of problems that the starting fails due to too large power generation braking torque or synchronization cannot be involved in later period occur.
The method for starting the mixed squirrel-cage rotor asynchronous starting permanent magnet synchronous motor adopts a △/Y switching method, is essentially a pressurized starting method, namely, an input voltage is increased in a starting stage, and the motor is switched to lower voltage for power supply after synchronization is drawn.
The method comprises the steps of controlling the excitation of a synchronous motor after asynchronous starting under the notice number CN 104767428B and controlling the excitation, detecting a synchronous motor starting sub-synchronization under the notice number CN109474211A, and controlling the excitation to be started under the notice number CN 105529966B. Although the start-up by the above-described starting methods is not affected by the synchronous braking torque, the synchronous braking torque is not sufficiently utilized during the start-up. And the starting methods are based on an electric excitation synchronous motor, and compared with a permanent magnet synchronous motor, the electric excitation synchronous motor has the advantages of large volume, complex components and limited application occasions. The patent of the three-stage brushless synchronous motor asynchronous starting control method and system with the publication number CN 108880363a adopts the power electronic device and the control system to realize the brushless electric excitation function on the basis of the electric excitation motor, so that the motor has higher reliability. However, the starting method still starts by using asynchronous torque generated by a motor rotor damping winding when the motor is started, and synchronous torque is not fully used.
The method adopts variable frequency starting, the starting time is greatly influenced by a frequency converter, and in addition, the maximum torque of the motor cannot be exerted in the variable frequency starting process.
The device and the method for improving the starting capability of the asynchronous starting permanent magnet motor have the publication number CN 108768218A, and the starting method is characterized in that the motor is quickly started by detecting a transient included angle between a magnetic field formed by a three-phase winding of a power voltage introduced into the asynchronous starting permanent magnet motor and a rotor permanent magnet magnetic field during starting and utilizing the permanent magnet torque at the starting moment of the asynchronous starting permanent magnet motor. The starting method only strengthens the torque at the starting moment, and various torque mutual restriction influences still occur due to the asynchronous magnetic fields of the stator and the rotor of the motor in the starting process. Similar to the above disadvantages, the asynchronous starting method of the half-magnetic-sheet permanent magnet synchronous motor of the publication No. CN 103580429B has the mutual influence of various torques during starting, and cannot fully exert the positive effects of various torques on starting.
Disclosure of Invention
Aiming at the defects that various torques in the starting mode of the existing asynchronous starting permanent magnet synchronous motor are mutually restricted and influenced and the asynchronous torque and the synchronous torque which can be provided by the motor cannot be effectively utilized for starting, the invention provides a method for realizing the quick starting of the motor by combining the asynchronous starting with the maximum synchronous torque starting according to the torque characteristics of the motor when the motor runs at different rotating speed stages and aiming at outputting the maximum torque.
In order to solve the technical problems, the invention adopts the following technical scheme:
a method for rapidly starting an asynchronous starting permanent magnet synchronous motor based on torque characteristics,
the topological structure of the starting system based on the quick starting method comprises the following steps: the control processing module, the dual-channel motor driving module, the change-over switch module, the asynchronous starting permanent magnet synchronous motor and the encoder thereof; the control processing module mainly comprises a main controller; the double-channel motor driving module comprises an asynchronous synthetic torque starting driving unit and a maximum synchronous torque starting driving unit; the change-over switch module comprises switches K1 and K2, wherein the switch K1 is connected with the asynchronous synthetic torque starting drive unit, and the switch K2 is connected with the maximum synchronous torque starting drive unit;
the quick starting method comprises the following steps:
when the motor needs to be started, the main controller controls the asynchronous synthetic torque starting drive unit to enable the asynchronous synthetic torque starting drive unit to output a power supply of the rated voltage and the rated frequency of the controlled motor, then the switch K2 is controlled to be switched off, K1 is switched on to supply power to the motor, and the asynchronous starting permanent magnet synchronous motor starts automatically under the rated voltage and the rated frequency, namely the speed is increased under the action of the asynchronous synthetic torque;
in the motor speed-up stage, the main controller calculates the motor speed n in real time according to the rotor position signal provided by the encoder, and converts the motor speed n into the corresponding slip ratio s (s is 1-n/n)0，n0Synchronous rotation speed of the motor), and further combining an asynchronous synthetic torque formula Tav(s) to calculate real-time torque of the motor in an asynchronous synthetic torque starting mode, and comparing the asynchronous synthetic torque Tav(s) of the motor with the maximum synchronous torque Tem maxThe size of (d);
the asynchronous synthesized torque formula: tav(s) ═ tc(s) + tg(s), wherein:
in the formula: m is the number of motor phases; p is the number of pole pairs of the motor; u is a power supply phase voltage; f is the power frequency; s is slip; r1And X1Respectively a stator winding resistor and a leakage reactance; r'2And X'2Respectively converting the resistance and reactance of the rotor; e0Is the no-load counter electromotive force, X, of the motordAnd XqThe reactance of the alternating and direct axes of the motor are respectively; c. C1To correct the coefficient, c1＝1+X1Xm, where Xm is the synchronous reactance;
the maximum synchronous torque of the motor can be obtained according to the following permanent magnet motor maximum synchronous torque formula and the specific parameters of the controlled motor:
wherein m is the number of motor phases, p is the number of motor pole pairs, psifFor each pole flux linkage of the permanent magnet rotor, U is a power phaseVoltage, XdAnd XqThe reactance of the alternating and direct axes of the motor, omega0Electric angular velocity, theta, corresponding to the rated speed of the motormaxThe torque angle is the corresponding torque angle when the motor has the maximum synchronous torque;
(III) when the main controller detects that the asynchronous synthetic torque Tav(s) is less than the maximum synchronous torque Tem maxAnd then the main controller records the rotating speed of the motor at the moment and converts the rotating speed into the corresponding electrical angular velocity omega, and then the maximum synchronous torque T of the motor under the electrical angular velocity omega is calculated by combining the maximum synchronous torque formula of the permanent magnet motorem maxThe corresponding torque angle theta 'controls the maximum synchronous torque to start the driving unit, so that the driving unit outputs a power supply which has a stator voltage phase with the torque angle theta' from the rotor magnetic pole position provided by the encoder at the moment, and controls the switch K1 to be switched off, so that the K2 is switched on to supply power to the motor; the main controller calculates the electrical angular velocity of the motor in real time through the rotor position signal provided by the encoder at the stage, and solves and maintains the maximum synchronous torque Tem maxThe required torque angle theta between the stator and the rotor is not changed, and the maximum synchronous torque is controlled to start the driving unit to cut off and jump the voltage phase of the stator, so that the phase of the output voltage and the magnetic pole of the rotor can always meet the requirement of Tem maxA constant torque angle theta to ensure T during the motor speed-up processem maxConstant; because the phase switching jump makes the period smaller and the frequency increased, the motor is ensured to be in the maximum synchronous torque Tem maxRaising the speed under the action of the force;
(IV) the main controller detects the rotating speed of the motor in real time at the starting stage of the maximum synchronous torque and calculates the real-time asynchronous synthetic torque Tav(s) of the motor and the maximum synchronous torque T by the methodem maxComparing;
(V) the main controller detects that the asynchronous synthetic torque Tav(s) is larger than the maximum synchronous torque Tem maxWhen the motor is started, a rotor magnetic pole position signal provided by the encoder is recorded, the asynchronous synthetic torque starting driving unit is controlled to output a power supply with the same phase of the rotor magnetic pole position at the moment and the rated voltage and the rated frequency, and then the switch K2 is controlled to be switched off, K1 is switched off, and power is supplied to the motor; the motor is started again under the action of the asynchronous synthetic torque;
sixthly, the main controller compares the asynchronous synthetic torque Tav(s) with the maximum synchronous torque T of the motor in real time in the starting stage of the motorem maxAccording to the principle, the sizes of the two groups of the Chinese characters are switched with each other; when the motor reaches the synchronous speed, the main controller controls the asynchronous synthetic torque starting drive unit to output a power supply of the rated voltage and the rated frequency of the controlled motor, and controls the switch K2 to disconnect the K1 and close the power supply to the motor, so that the motor stably runs in the rated state, and the starting process is finished.
The maximum synchronous torque starting mode is realized by adopting the phase cutting jump of the driving voltage; the phase cutting jump is realized by controlling the on-off of a power electronic switch device in the maximum synchronous torque starting drive unit through the main controller; the maximum synchronous torque starting drive circuit is composed of three-phase circuits, each phase is composed of multiple voltage sources with different phases, each path is switched on and off by a power electronic switching device, and the main controller controls the switching-on and switching-off of the switching device in each phase according to the required phase to realize the jump of the phase.
In all the asynchronous synthetic torque starting stages, the main controller controls the asynchronous synthetic torque starting drive unit to output a power supply with the rated frequency of the controlled motor but higher than the rated voltage, so that the asynchronous synthetic torque Tav(s) of the motor is increased.
Determining the functional relation between U and s when the asynchronous synthetic torque Tav(s) of the motor is kept constant in the speed-up process according to the relation between the voltage U and the slip ratio s in the asynchronous synthetic torque Tav(s) of the motor; and then in all the asynchronous synthetic torque starting stages, the main controller controls the asynchronous synthetic torque starting driving unit according to the functional relation of the U and the s and by combining the real-time slip rate s of the motor, so that the asynchronous synthetic torque starting driving unit outputs a power supply of a driving voltage U corresponding to the slip rate s to supply power to the motor.
Determining the functional relation between f and s when the asynchronous synthetic torque Tav(s) of the motor is constant in the speed-up process according to the relation between the frequency f and the slip ratio s in the asynchronous synthetic torque Tav(s) of the motor; in all the starting stages of the asynchronous synthetic torque, the main controller controls the asynchronous synthetic torque starting driving unit according to the functional relation between f and s and by combining the real-time slip rate s of the motor, so that the power supply with the driving frequency f corresponding to the output slip rate s supplies power to the motor.
The invention has the beneficial effects that:
the invention utilizes the influence of the action of the power generation braking torque and the reluctance negative sequence component torque and the obvious reduction of the asynchronous torque along with the reduction of the slip ratio in the later starting period in the starting process of the asynchronous starting permanent magnet synchronous motor, and the phenomenon that the synthesized total average torque is less than the maximum permanent magnet synchronous torque in stages can occur. When the composite starting torque of the asynchronous starting is larger than the maximum synchronous torque of the motor, the motor is started by using the composite starting torque of the asynchronous starting. When the resultant starting torque of the asynchronous starting is smaller than the maximum synchronous torque, the starting is switched to the maximum synchronous torque starting using the electric machine. In the asynchronous starting process, two starting modes are alternately switched according to the specific starting torque characteristics of the motor, so that the starting torque of the asynchronous starting permanent magnet synchronous motor can be ensured to be the maximum of the asynchronous torque and the synchronous torque in the starting process, the starting torque is maximized, the starting capability and the pull-in synchronization capability of the motor are improved, the starting time is shortened, and the stable starting is realized.
In the starting process of the motor, the two starting methods are organically combined according to the specific torque characteristics of the controlled motor, so that the asynchronous synthetic torque and the maximum synchronous torque are mutually compensated, and the starting torque is maximized.
The invention adopts a phase jump type maximum synchronous torque starting method at the maximum synchronous torque starting stage, and the method ensures Tem maxOn the basis of constant, the rotating speed of the motor is detected in real time and the maximum synchronous torque T is solved and maintainedem maxThe torque angle theta between the stator and the rotor required by invariance can be kept to meet T between the output voltage phase and the rotor magnetic pole through the cutting jump of the stator voltage phaseem maxA constant torque angle theta to ensure T during the motor speed-up processem maxAnd the constant starting effect is achieved by phase cutting off and jumping, the period is reduced, the frequency is increased, and the rotating speed of the motor is rapidly increased.
Description of the drawings:
FIG. 1 is a schematic of the topology of the present invention;
FIG. 2 is a schematic diagram of a handover principle;
FIG. 3 shows an embodiment: the principle and schematic diagram of realizing quick start by alternately switching two torques without adjusting voltage and frequency;
fig. 4 shows a second embodiment: boosting, and reducing the number of starting mode switching points;
fig. 5 shows a third embodiment: regulating voltage and keeping a principle schematic diagram of quick and stable starting;
fig. 6 shows a fourth embodiment: the principle schematic diagram of frequency modulation maintaining quick and stable starting;
FIG. 7 is a schematic diagram of the phase cut jump principle;
fig. 8 is a graph of expected effects.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings.
The first embodiment is as follows:
as shown in fig. 1, 2, 3, 7 and 8, a method for fast starting an asynchronous starting permanent magnet synchronous motor based on torque characteristics, the fast starting method based on a starting topology structure comprises: the control processing module, the dual-channel motor driving module, the change-over switch module, the asynchronous starting permanent magnet synchronous motor and the encoder thereof; the control processing module mainly comprises a main controller, the dual-channel motor driving module comprises an asynchronous synthetic torque starting driving unit and a maximum synchronous torque starting driving unit, and the change-over switch module comprises switches K1 and K2, wherein the switch K1 is connected with the asynchronous synthetic torque starting driving unit, and the switch K2 is connected with the maximum synchronous torque starting driving unit;
the quick starting method comprises the following steps:
when the motor needs to be started, the main controller controls the asynchronous synthetic torque starting drive unit to enable the asynchronous synthetic torque starting drive unit to output a power supply of the rated voltage and the rated frequency of the controlled motor, then the switch K2 is controlled to be switched off, K1 is switched on to supply power to the motor, and the asynchronous starting permanent magnet synchronous motor starts automatically under the rated voltage and the rated frequency, namely the speed is increased under the action of the asynchronous synthetic torque;
(II) in the motor speed-up stage, the main controller is in real timeThe motor speed n is calculated according to the rotor position signal provided by the encoder and converted into a corresponding slip s (s is 1-n/n)0，n0Synchronous rotation speed of the motor), and further combining an asynchronous synthetic torque formula Tav(s) to calculate real-time torque of the motor in an asynchronous synthetic torque starting mode, and comparing the asynchronous synthetic torque Tav(s) of the motor with the maximum synchronous torque Tem maxThe size of (d);
the asynchronous synthesized torque formula: tav(s) ═ tc(s) + tg(s), wherein:
in the formula: m is the number of motor phases; p is the number of pole pairs of the motor; u is a power supply phase voltage; f is the power frequency; s is slip; r1And X1Respectively a stator winding resistor and a leakage reactance; r'2And X'2Respectively converting the resistance and reactance of the rotor; e0Is the no-load counter electromotive force, X, of the motordAnd XqThe reactance of the alternating and direct axes of the motor are respectively; c. C1To correct the coefficient, c1＝1+X1Xm, where Xm is the synchronous reactance (note: this part is a function corresponding to the curve in the control processing module in FIG. 1, which is an inherent characteristic of the controlled motor);
the maximum synchronous torque of the motor can be obtained according to the following permanent magnet motor maximum synchronous torque formula and the specific parameters of the controlled motor:
wherein m is the number of motor phases, p is the number of motor pole pairs, psifFor each pole flux linkage of the permanent magnet rotor, U is the power phase voltage, XdAnd XqThe reactance of the alternating and direct axes of the motor, omega0Electric angular velocity, theta, corresponding to the rated speed of the motormaxAt the maximum synchronous torque of the motorA corresponding torque angle;
(III) when the main controller detects that the asynchronous synthetic torque Tav(s) is less than the maximum synchronous torque Tem maxAnd then the main controller records the rotating speed of the motor at the moment and converts the rotating speed into the corresponding electrical angular velocity omega, and then the maximum synchronous torque T of the motor under the electrical angular velocity omega is calculated by combining the maximum synchronous torque formula of the permanent magnet motorem maxThe corresponding torque angle theta 'controls the maximum synchronous torque to start the driving unit, so that the driving unit outputs a power supply which has a stator voltage phase with the torque angle theta' from the rotor magnetic pole position provided by the encoder at the moment, and controls the switch K1 to be switched off, so that the K2 is switched on to supply power to the motor; the main controller calculates the electrical angular velocity of the motor in real time through the rotor position signal provided by the encoder at the stage, and solves and maintains the maximum synchronous torque Tem maxThe required torque angle theta between the stator and the rotor is not changed, and the maximum synchronous torque is controlled to start the driving unit to cut off and jump the voltage phase of the stator, so that the phase of the output voltage and the magnetic pole of the rotor can always meet the requirement of Tem maxA constant torque angle theta to ensure T during the motor speed-up processem maxIs constant. Because the phase switching jump makes the period smaller and the frequency increased, the motor is ensured to be in the maximum synchronous torque Tem maxRaising the speed under the action of the force;
(IV) the main controller detects the rotating speed of the motor in real time at the starting stage of the maximum synchronous torque and calculates the real-time asynchronous synthetic torque Tav(s) of the motor and the maximum synchronous torque T by the methodem maxComparing;
(V) the main controller detects that the asynchronous synthetic torque Tav(s) is larger than the maximum synchronous torque Tem maxWhen the motor is started, a rotor magnetic pole position signal provided by the encoder is recorded, the asynchronous synthetic torque starting driving unit is controlled to output a power supply with the same phase of the rotor magnetic pole position at the moment and the rated voltage and the rated frequency, and then the switch K2 is controlled to be switched off, K1 is switched off, and power is supplied to the motor; the motor is started again under the action of the asynchronous synthetic torque;
sixthly, the main controller compares the asynchronous synthetic torque Tav(s) with the maximum synchronous torque T of the motor in real time in the starting stage of the motorem maxAccording to the principle, the sizes of the two groups of the Chinese characters are switched with each other; toWhen the motor reaches the synchronous speed, the main controller controls the asynchronous synthetic torque starting drive unit to output a power supply of the rated voltage and the rated frequency of the controlled motor, and controls the switch K2 to disconnect the K1 and close the power supply to the motor, so that the motor stably runs in the rated state, and the starting process is finished.
The maximum synchronous torque starting mode is realized by cutting off and jumping of the phase of the driving voltage; the phase cutting jump is realized by controlling the on-off of a power electronic switch device in the maximum synchronous torque starting drive unit through the main controller; the maximum synchronous torque starting drive circuit is composed of three-phase circuits, each phase is composed of multiple voltage sources with different phases, each path is switched on and off by a power electronic switching device, and the main controller controls the switching-on and switching-off of the switching device in each phase according to the required phase to realize the jump of the phase.
The invention adopts a phase jump type maximum synchronous torque starting method at the maximum synchronous torque starting stage, and the method ensures Tem maxOn the basis of constant, the rotating speed of the motor is detected in real time and the maximum synchronous torque T is solved and maintainedem maxThe torque angle theta between the stator and the rotor required by invariance can be kept to meet T between the output voltage phase and the rotor magnetic pole through the cutting jump of the stator voltage phaseem maxA constant torque angle theta to ensure T during the motor speed-up processem maxAnd the constant starting effect is achieved by phase cutting off and jumping, the period is reduced, the frequency is increased, and the rotating speed of the motor is rapidly increased.
The starting topological structure combines asynchronous starting and maximum synchronous torque starting, utilizes permanent magnet synchronous torque to make up for the stage insufficient output of asynchronous synthetic torque according to the torque characteristics of the motor in the asynchronous starting process, and achieves the purpose of outputting the maximum torque to start the motor quickly. In the starting process of the asynchronous starting permanent magnet synchronous motor, the condition that the synthetic starting torque is less than the maximum synchronous torque in a staged manner can occur under the influence of the power generation braking torque and the reluctance negative sequence component torque.
The invention is based on the influence that the asynchronous torque is obviously reduced along with the reduction of slip ratio under the action of the power generation braking torque and the magnetic resistance negative sequence component torque and the asynchronous torque at the later stage of starting in the starting process of the asynchronous starting permanent magnet synchronous motor, and the phenomenon that the synthesized total average torque is less than the maximum permanent magnet synchronous torque in stages can occur. When the composite starting torque of the asynchronous starting is larger than the maximum synchronous torque of the motor, the motor is started by using the composite starting torque of the asynchronous starting. When the resultant starting torque of the asynchronous starting is smaller than the maximum synchronous torque, the starting is switched to the maximum synchronous torque starting using the electric machine. In the asynchronous starting process, two starting modes are alternately switched according to the specific starting torque characteristics of the motor, so that the starting torque of the asynchronous starting permanent magnet synchronous motor can be ensured to be the maximum of the asynchronous torque and the synchronous torque in the starting process, the starting torque is maximized, the starting capability and the pull-in synchronization capability of the motor are improved, the starting time is shortened, and the stable starting is realized.
The quick starting method of the invention combines the maximum value of the starting torque provided by the asynchronous starting method and the maximum synchronous torque starting method, ensures the maximization of the starting torque of the motor, shortens the starting time, and effectively avoids the problems that the asynchronous starting permanent magnet synchronous motor fails to start or cannot involve in synchronization in the later starting period due to the overlarge power generation braking torque.
In the starting process of the motor, the two starting methods are organically combined according to the specific torque characteristics of the controlled motor, so that the asynchronous synthetic torque and the maximum synchronous torque are mutually compensated, and the starting torque is maximized. The embodiment does not adjust the voltage irregular frequency, and realizes quick start by alternately switching two torques.
Example two:
as shown in fig. 4, in this embodiment, on the basis of the first embodiment, in all the asynchronous synthesized torque starting stages, the main controller controls the asynchronous synthesized torque starting driving unit to output a power supply with the rated frequency of the controlled motor but higher than the rated voltage, so as to increase the asynchronous synthesized torque tav(s) of the motor (the principle is that the asynchronous torque is proportional to the voltage), further increase the torque during the starting process, and reduce the number of starting mode switching points. After the motor is started, the asynchronous synthetic torque starting drive unit outputs a power supply of rated voltage and frequency of the controlled motor, so that the motor can stably run in a rated state.
Embodiments reduce the number of regulation switching points by boosting.
The embodiment realizes further improvement of the starting torque of the motor and shortening of the starting time.
Example three:
as shown in fig. 5, in this embodiment, according to the relationship between the voltage U and the slip s in the asynchronous synthesized torque tav(s) of the motor, the functional relationship between U and s when the asynchronous synthesized torque tav(s) of the motor is constant in the speed increasing process is determined. On the basis of the first embodiment, in all the starting stages of the asynchronous synthetic torque, the main controller controls the starting driving unit of the asynchronous synthetic torque according to the slip ratio of the motor, so that the power supply of the driving voltage U corresponding to the real-time slip ratio in the starting process is output to supply power to the motor, the asynchronous synthetic torque of the motor is ensured to be constant under different slip ratios, and stable and quick starting is realized.
The embodiment realizes the improvement of the starting torque, ensures the smoothness of the starting torque and further improves the starting performance.
Example four:
as shown in fig. 6, in this embodiment, according to the relationship between the frequency f and the slip ratio s in the asynchronous synthesized torque tav(s) of the motor, the functional relationship between f and s when the asynchronous synthesized torque tav(s) is constant in the speed increasing process of the motor is determined. On the basis of the first embodiment, in all the starting stages of the asynchronous synthetic torque, the main controller controls the starting driving unit of the asynchronous synthetic torque according to the slip ratio of the motor, so that the power supply with the corresponding driving frequency f under the real-time slip ratio in the starting process is output to supply power to the motor, the asynchronous synthetic torque of the motor is ensured to be kept constant under different slip ratios, and stable and quick starting is realized.
The embodiment realizes the improvement of the starting torque, ensures the smoothness of the starting torque and further improves the starting performance.
Although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that: modifications and equivalents may be made thereto without departing from the spirit and scope of the invention and it is intended to cover in the claims the invention as defined in the appended claims.
In the description of the present invention, it is to be understood that the terms "front", "back", "upper", "lower", "left", "right", "middle" and "one", etc., indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, but do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the scope of the present invention.
Claims (5)
1. A quick starting method of an asynchronous starting permanent magnet synchronous motor based on torque characteristics is characterized by comprising the following steps:
the topological structure of the starting system based on the quick starting method comprises the following steps: the control processing module, the dual-channel motor driving module, the change-over switch module, the asynchronous starting permanent magnet synchronous motor and the encoder thereof; the control processing module mainly comprises a main controller; the double-channel motor driving module comprises an asynchronous synthetic torque starting driving unit and a maximum synchronous torque starting driving unit; the change-over switch module comprises switches K1 and K2, wherein the switch K1 is connected with the asynchronous synthetic torque starting drive unit, and the switch K2 is connected with the maximum synchronous torque starting drive unit;
the quick starting method comprises the following steps:
when the motor needs to be started, the main controller controls the asynchronous synthetic torque starting drive unit to enable the asynchronous synthetic torque starting drive unit to output a power supply of the rated voltage and the rated frequency of the controlled motor, then the switch K2 is controlled to be switched off, K1 is switched on to supply power to the motor, and the asynchronous starting permanent magnet synchronous motor starts automatically under the rated voltage and the rated frequency, namely the speed is increased under the action of the asynchronous synthetic torque;
in the motor speed-up stage, the main controller calculates the motor speed n in real time according to the rotor position signal provided by the encoder, and converts the motor speed n into the corresponding slip ratio s (s is 1-n/n)0，n0Synchronous speed of the motor) and further combined with asynchronous synthesisCalculating real-time torque of the motor in an asynchronous synthetic torque starting mode by using a torque formula Tav(s), and comparing the asynchronous synthetic torque Tav(s) with the maximum synchronous torque TemmaxThe size of (d);
the asynchronous synthesized torque formula: tav(s) ═ tc(s) + tg(s), wherein:
in the formula: m is the number of motor phases; p is the number of pole pairs of the motor; u is a power supply phase voltage; f is the power frequency; s is slip; r1And X1Respectively a stator winding resistor and a leakage reactance; r'2And X'2Respectively converting the resistance and reactance of the rotor; e0Is the no-load counter electromotive force, X, of the motordAnd XqThe reactance of the alternating and direct axes of the motor are respectively; c. C1To correct the coefficient, c1＝1+X1Xm, where Xm is the synchronous reactance;
the maximum synchronous torque of the motor can be obtained according to the following permanent magnet motor maximum synchronous torque formula and the specific parameters of the controlled motor:
wherein m is the number of motor phases, p is the number of motor pole pairs, psifFor each pole flux linkage of the permanent magnet rotor, U is the power phase voltage, XdAnd XqThe reactance of the alternating and direct axes of the motor, omega0Electric angular velocity, theta, corresponding to the rated speed of the motormaxThe torque angle is the corresponding torque angle when the motor has the maximum synchronous torque;
(III) when the main controller detects that the asynchronous synthetic torque Tav(s) is less than the maximum synchronous torque TemmaxAnd then the main controller records the rotating speed of the motor at the moment and converts the rotating speed into the corresponding electrical angular speed omega so as to combine the maximum synchronous rotation of the permanent magnet motorThe torque formula calculates the maximum synchronous torque T of the motor under the electrical angular velocity omegaemmaxThe corresponding torque angle theta 'controls the maximum synchronous torque to start the driving unit, so that the driving unit outputs a power supply which has a stator voltage phase with the torque angle theta' from the rotor magnetic pole position provided by the encoder at the moment, and controls the switch K1 to be switched off, so that the K2 is switched on to supply power to the motor; the main controller calculates the electrical angular velocity of the motor in real time through the rotor position signal provided by the encoder at the stage, and solves and maintains the maximum synchronous torque TemmaxThe required torque angle theta between the stator and the rotor is not changed, and the maximum synchronous torque is controlled to start the driving unit to cut off and jump the voltage phase of the stator, so that the phase of the output voltage and the magnetic pole of the rotor can always meet the requirement of TemmaxA constant torque angle theta to ensure T during the motor speed-up processemmaxConstant; because the phase switching jump makes the period smaller and the frequency increased, the motor is ensured to be in the maximum synchronous torque TemmaxRaising the speed under the action of the force;
(IV) the main controller detects the rotating speed of the motor in real time at the starting stage of the maximum synchronous torque and calculates the real-time asynchronous synthetic torque Tav(s) of the motor and the maximum synchronous torque T by the methodemmaxComparing;
(V) the main controller detects that the asynchronous synthetic torque Tav(s) is larger than the maximum synchronous torque TemmaxWhen the motor is started, a rotor magnetic pole position signal provided by the encoder is recorded, the asynchronous synthetic torque starting driving unit is controlled to output a power supply with the same phase of the rotor magnetic pole position at the moment and the rated voltage and the rated frequency, and then the switch K2 is controlled to be switched off, K1 is switched off, and power is supplied to the motor; the motor is started again under the action of the asynchronous synthetic torque;
sixthly, the main controller compares the asynchronous synthetic torque Tav(s) with the maximum synchronous torque T of the motor in real time in the starting stage of the motoremmaxAccording to the principle, the sizes of the two groups of the Chinese characters are switched with each other; when the motor reaches the synchronous speed, the main controller controls the asynchronous synthetic torque starting drive unit to output a power supply of the rated voltage and the rated frequency of the controlled motor, and controls the switch K2 to disconnect the K1 and close the power supply to the motor, so that the motor stably runs in the rated state, and the starting process is finished.
2. The method for rapidly starting an asynchronously started permanent magnet synchronous motor according to claim 1, wherein: the maximum synchronous torque starting mode is realized by adopting the phase cutting jump of the driving voltage; the phase cutting jump is realized by controlling the on-off of a power electronic switch device in the maximum synchronous torque starting drive unit through the main controller; the maximum synchronous torque starting drive circuit is composed of three-phase circuits, each phase is composed of multiple voltage sources with different phases, each path is switched on and off by a power electronic switching device, and the main controller controls the switching-on and switching-off of the switching device in each phase according to the required phase to realize the jump of the phase.
3. The rapid starting method of an asynchronously started permanent magnet synchronous motor according to claim 1 or 2, characterized in that: in all the asynchronous synthetic torque starting stages, the main controller controls the asynchronous synthetic torque starting drive unit to output a power supply with the rated frequency of the controlled motor but higher than the rated voltage, so that the asynchronous synthetic torque Tav(s) of the motor is increased.
4. The rapid starting method of an asynchronously started permanent magnet synchronous motor according to claim 1 or 2, characterized in that: determining the functional relation between U and s when the asynchronous synthetic torque Tav(s) of the motor is kept constant in the speed-up process according to the relation between the voltage U and the slip ratio s in the asynchronous synthetic torque Tav(s) of the motor; and then in all the asynchronous synthetic torque starting stages, the main controller controls the asynchronous synthetic torque starting driving unit according to the functional relation of the U and the s and by combining the real-time slip rate s of the motor, so that the asynchronous synthetic torque starting driving unit outputs a power supply of a driving voltage U corresponding to the slip rate s to supply power to the motor.
5. The rapid starting method of an asynchronously started permanent magnet synchronous motor according to claim 1 or 2, characterized in that: determining the functional relation between f and s when the asynchronous synthetic torque Tav(s) of the motor is constant in the speed-up process according to the relation between the frequency f and the slip ratio s in the asynchronous synthetic torque Tav(s) of the motor; in all the starting stages of the asynchronous synthetic torque, the main controller controls the asynchronous synthetic torque starting driving unit according to the functional relation between f and s and by combining the real-time slip rate s of the motor, so that the power supply with the driving frequency f corresponding to the output slip rate s supplies power to the motor.
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