Initial positioning method of permanent magnet synchronous motor for driving antenna

Abstract

The invention discloses an initial positioning method of a permanent magnet synchronous motor for driving an antenna, and relates to the technical field of antenna system motor driving control. According to the method, the rated voltage and the rated current of the permanent magnet synchronous motor are firstly obtained, the winding excitation voltage is iteratively applied, and a proper initial positioning voltage value is selected, so that the problem of motor winding damage caused by overcurrent in the rotor positioning process of a conventional voltage open-loop positioning method is effectively solved; initial positioning of the permanent magnet synchronous motor of the driving antenna is reliably achieved, meanwhile, through two-step rotor position positioning, the problem that rotor positioning is not in place is effectively avoided, and the method has the advantages of being simple, convenient, practical and reliable in engineering practice.

Description

Technical Field

[0001] The invention relates to the technical field of motor drive control of an antenna system, and in particular to an initial positioning method of a permanent magnet synchronous motor for driving an antenna. Background Art

[0002] With the development of microelectronics technology, power electronics technology, computer technology and modern control technology, the manufacturing process level of permanent magnet motors has been continuously improved. As an important driving component, permanent magnet synchronous motor systems have been widely used in satellite communication systems due to their excellent performance, gradually replacing brushed DC motors.

[0003] Permanent magnet synchronous motors can use a variety of feedback forms, among which incremental encoders are currently the most commonly used feedback form for permanent magnet synchronous motors. When a permanent magnet synchronous motor using incremental encoder feedback is initialized, it is necessary to first determine the initial angular position of the rotor. Currently, there are two methods for determining the initial position of the rotor: current closed-loop positioning and voltage open-loop positioning. Both methods have the following problems:

[0004] a) There are problems with the current closed-loop positioning method: it is implemented by dq-axis current closed-loop regulation using magnetic field positioning. When using dq-axis current closed-loop positioning, it is necessary to obtain the motor winding parameters (resistance, inductance, etc.), and determine the current controller parameters based on the motor winding parameters to ensure that the current closed loop can be reliably implemented. When the motor winding parameters are unknown, an identification algorithm is required to obtain the motor winding parameters, and the premise for the application of the identification algorithm is to complete the initial positioning of the motor. Therefore, when the motor winding parameters are unknown, the current closed-loop motor initialization positioning is used to form an interlocking relationship with the motor parameter identification. From the above analysis, the current closed-loop positioning method has certain limitations.

[0005] b) Problems with the voltage open-loop positioning method: With the conventional voltage open-loop positioning method, the rated voltage is directly applied to the motor winding. However, during the motor positioning process, the motor speed is low, and the motor back electromotive force is correspondingly small. If the rated motor voltage or an arbitrary value is directly applied, the motor winding current will far exceed the rated current, which may easily cause damage to the motor winding, or fail to drive the antenna load to the desired positioning point. This positioning method does not require obtaining the motor winding parameters (resistance, inductance, etc.), but there is a problem that the overcurrent generated by applying the rated voltage will cause damage to the motor winding, or that applying an arbitrary voltage will fail to drive the antenna load to the desired positioning point. Summary of the invention

[0006] In view of this, the present invention proposes an initial positioning method for a permanent magnet synchronous motor driving an antenna. The present invention does not need to obtain motor winding parameters, and by iteratively applying winding excitation voltage and selecting a suitable initial positioning voltage value, effectively solves the motor winding damage caused by overcurrent in the rotor positioning process of the conventional voltage open-loop positioning method, reliably realizes the initial positioning of the permanent magnet synchronous motor driving the antenna, and at the same time, through two-step rotor position positioning, effectively avoids the problem of rotor positioning failure, and has the advantages of simplicity, practicality and reliability in engineering practice.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A method for initial positioning of a permanent magnet synchronous motor driving an antenna comprises the following steps:

[0009] Step 1: Obtain the rated voltage U of the permanent magnet synchronous motor according to the nameplate information of the permanent magnet synchronous motor. N With rated current I N ;

[0010] Step 2: Set the two-phase rotating coordinate system voltage U of the permanent magnet synchronous motor d =0,U q =0.1U N ; and the initial positioning angle of the rotor of the permanent magnet synchronous motor is set to θ, where θ is an arbitrary value;

[0011] Step 3: Convert the two-phase rotating coordinate system voltage U d with U q Converted to two-phase stationary coordinate system voltage U α with U β :

[0012]

[0013] Step 4: Convert the two-phase stationary coordinate system voltage U α with U β Converted to three-phase stationary coordinate system voltage U a , U b with U c :

[0014]

[0015] Step 5: Use SVPWM for vector modulation and convert the three-phase stationary coordinate system voltage U a , U b with U c Output to permanent magnet synchronous motor;

[0016] Step 6: Collect the three-phase current value I of the permanent magnet synchronous motor through the current sensor a ,Ib with I c , and the three-phase current value I a ,I b with I c The maximum value among the absolute values ​​of is recorded as I x :

[0017] I x =Max(|I a |、|I b |、|I c |);

[0018] Step 7, judgment I x <n*I N Is it true? If I x <n*I N If established, then let U d =0,U q =m*U q ; and continue to step 3; if I x <n*I N If it does not hold, then let U d =0,U q =Min(U q , U N ), and execute step 8; where 1 <n<2,1<m<1.2;

[0019] Step 8, setting the rotor secondary positioning angle of the permanent magnet synchronous motor to θ+90° or θ-90°;

[0020] Step 9, execute steps 3 and 4 to convert the two-phase rotating coordinate system voltage U d with U q Converted to three-phase stationary coordinate system voltage U a , U b with U c SVPWM is used for vector modulation, and the three-phase stationary reference system voltage U is converted according to the inverter circuit. a , U b with U c Output to the permanent magnet synchronous motor to complete the initial positioning of the permanent magnet synchronous motor.

[0021] Due to the adoption of the above technical solution, the beneficial effects of the present invention compared with the prior art are:

[0022] 1. The present invention does not need to obtain the motor winding parameters. By iteratively applying the winding excitation voltage and selecting a suitable initial positioning voltage value, it effectively solves the motor winding damage caused by overcurrent in the rotor positioning process of the conventional voltage open-loop positioning method, and reliably realizes the initial positioning of the permanent magnet synchronous motor driving the antenna.

[0023] 2. The present invention uses two-step rotor position positioning to effectively avoid the problem of inadequate rotor positioning, and has the advantages of being simple, practical and reliable in engineering practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 1 is a diagram showing the conversion relationship between voltage variables of a three-phase stationary coordinate system, a two-phase stationary coordinate system and a two-phase rotating coordinate system in an embodiment of the present invention.

[0025] Figure 2 4 is a system structure diagram of a permanent magnet synchronous motor in an embodiment of the present invention.

[0026] Figure 3 The figure is a flow chart of an initial positioning method of a permanent magnet synchronous motor driving an antenna in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0028] An initial positioning method for a permanent magnet synchronous motor driving an antenna, such as Figure 3 As shown, the following steps are included;

[0029] Step 1: Obtain the rated voltage U of the permanent magnet synchronous motor according to the nameplate information of the permanent magnet synchronous motor. N With rated current I N ;

[0030] Step 2: Set the two-phase rotating coordinate system voltage U of the permanent magnet synchronous motor d =0,U q =0.1U N ; and the initial positioning angle of the rotor of the permanent magnet synchronous motor is set to θ, where θ is an arbitrary value;

[0031] Specifically, in this embodiment, θ=-180°;

[0032] Step 3: Convert the two-phase rotating coordinate system voltage U d with U q Converted to two-phase stationary coordinate system voltage U α with U β :

[0033]

[0034] Step 4: Convert the two-phase stationary coordinate system voltage U α with U β Converted to three-phase stationary coordinate system voltage U a , U b with U c :

[0035]

[0036] Specifically, Figure 1 As shown, it is the conversion relationship between the two-phase rotating coordinate system, the two-phase stationary coordinate system and the three-phase stationary coordinate system; wherein, the two-phase rotating coordinate system is the dq coordinate system in the figure, the two-phase stationary coordinate system is the αβ coordinate system in the figure, and the three-phase stationary coordinate system is the abc coordinate system in the figure;

[0037] Step 5: Use SVPWM for vector modulation and convert the three-phase stationary coordinate system voltage U a , U b with U c Output to permanent magnet synchronous motor;

[0038] Specifically, Figure 2 As shown, SVPWM is used to modulate the bus DC voltage to obtain pulse quantities PWM1-PWM6. The pulse quantity modulates the DC bus, and the DC is modulated through the inverter circuit. The inverter circuit outputs a three-phase stationary coordinate system voltage U a , U b with U c , three-phase stationary coordinate system voltage U a , U b with U c Connected to the permanent magnet synchronous motor, thereby driving the permanent magnet synchronous motor to operate.

[0039] Step 6: Collect the three-phase current value I of the permanent magnet synchronous motor through the current sensor a ,I b with I c , and the three-phase current value I a ,I b with I c The maximum value among the absolute values ​​of is recorded as I x :

[0040] I x =Max(|I a |、|I b |、|I c |);

[0041] Max() means selecting the maximum value;

[0042] Step 7, judgment I x <n*I N Is it true? If I x <n*I N If established, then let U d =0,U q =m*U q ; and continue to step 3; if I x <n*I N If it does not hold, then let Ud =0,U q =Min(U q , U N ), and execute step 8; where 1 <n<2,1<m<1.2;

[0043] Specifically, in this embodiment, n=1.2, m=1.1; Min() indicates selecting the minimum value;

[0044] Step 8, setting the rotor secondary positioning angle of the permanent magnet synchronous motor to θ+90° or θ-90°;

[0045] Specifically, in this embodiment, the rotor secondary positioning angle is set to -90°;

[0046] Step 9, execute steps 3 and 4 to convert the two-phase rotating coordinate system voltage U d with U q Converted to three-phase stationary coordinate system voltage U a , U b with U c SVPWM is used for vector modulation, and the three-phase stationary reference system voltage U is converted according to the inverter circuit. a , U b with U c Output to the permanent magnet synchronous motor to complete the initial positioning of the permanent magnet synchronous motor.

[0047] In summary, the present invention does not need to obtain the motor winding parameters. By iteratively applying the winding excitation voltage and selecting a suitable initial positioning voltage value, it effectively solves the motor winding damage caused by overcurrent in the rotor positioning process of the conventional voltage open-loop positioning method, and reliably realizes the initial positioning of the permanent magnet synchronous motor driving the antenna. At the same time, through two-step rotor position positioning, the problem of inadequate rotor positioning is effectively avoided. It has the advantages of simplicity, practicality and reliability in engineering practice.

[0048] Those skilled in the art will appreciate that the embodiments described are intended to help readers understand the principles of the present invention, and should be understood that the scope of protection of the present invention is not limited to the embodiments described. For those skilled in the art, the present invention may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for initial positioning of a permanent magnet synchronous motor driving an antenna, characterized in that: The steps include: Step 1: Obtain the rated voltage U of the permanent magnet synchronous motor according to the nameplate information of the permanent magnet synchronous motor. N With rated current I N ; Step 2: Set the two-phase rotating coordinate system voltage U of the permanent magnet synchronous motor d =0,U q =0.1U N ; and the initial positioning angle of the rotor of the permanent magnet synchronous motor is set to θ, where θ is an arbitrary value; Step 3: Convert the two-phase rotating coordinate system voltage U d with U q Converted to two-phase stationary coordinate system voltage U α with U β : Step 4: Convert the two-phase stationary coordinate system voltage U α with U β Converted to three-phase stationary coordinate system voltage U a , U b with U c : Step 5: Use SVPWM for vector modulation and convert the three-phase stationary coordinate system voltage U a , U b with U c Output to permanent magnet synchronous motor; Step 6: Collect the three-phase current value I of the permanent magnet synchronous motor through the current sensor a ,I b with I c , and the three-phase current value I a ,I b with I c The maximum value among the absolute values ​​of is recorded as I x : I x =Max(|I a |、|I b |、|I c |); Step 7, judgment I x <n*I N Is it true? If I x <n*I N If established, then let U d =0,U q =m*U q ; and proceed to step 3; If I x <n*I N If it does not hold, then let U d =0,U q =Min(U q , U N ), and execute step 8; where 1 <n<2,1<m<1.2; Step 8, setting the rotor secondary positioning angle of the permanent magnet synchronous motor to θ+90° or θ-90°; Step 9, execute steps 3 and 4 to convert the two-phase rotating coordinate system voltage U d with U q Converted to three-phase stationary coordinate system voltage U a , U b with U c SVPWM is used for vector modulation, and the three-phase stationary reference system voltage U is converted according to the inverter circuit. a , U b with U c Output to the permanent magnet synchronous motor to complete the initial positioning of the permanent magnet synchronous motor.

Images