Angle switching and throttle control methods for sensorless operation of PMSM

Abstract

The application discloses a method for angle switching and handlebar control of PMSM sensorless operation, comprising the following steps: A) open-loop starting stage; B) transition process; C) reduction process; D) sliding mode observation stage. The application uses a transition process scheme based on current amplitude change, realizes angle transition according to the "torque-power angle self-balancing principle", can respond to various load conditions, and the speed will not fluctuate, improving the comfort of the electric vehicle; the angle range of the stator current vector i s of the motor in the self-stabilizing region is increased, the step-out phenomenon caused by the fluctuation of the sampling current in the single-resistance sampling case is avoided; it is more in line with the use scene and user habit of the electric vehicle; a position sensorless control scheme for PMSM full-speed domain operation can be realized, the purpose of reducing the cost of the control system and improving the reliability and robustness of the system is achieved, and the method has small calculation amount, and is convenient to realize and popularize and apply.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet synchronous motor technology, and in particular to a method for angle switching and throttle control in sensorless operation of a PMSM. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) possess advantages such as small size, high power density, high efficiency, simple structure, low noise, and fast dynamic response, making them widely used in various industrial fields. In practical applications, vector control is the most widely adopted control strategy for PMSM drive systems. However, to obtain accurate position information in real time, position detection devices such as Hall effect sensors or photoelectric encoders are typically installed in the motor. This undoubtedly increases the system's cost and complexity, and reduces its anti-interference capability and overall reliability. Therefore, low-cost, high-precision, and high-reliability sensorless control technology for PMSMs has become a research hotspot both domestically and internationally.

[0003] Sensorless control algorithms typically divide the motor's speed range into zero-low speed and medium-high speed stages for separate study. A common full-speed-range operation scheme uses open-loop I / F starting control at zero-low speed and a sliding mode observer for position estimation at medium-high speed, with a transition process required between the two methods.

[0004] The common transition method is to adjust the open-loop angle. With sliding mode estimation angle Weighting is applied to gradually shift the perspective from... Transition to .

[0005] Meanwhile, to maintain a constant speed, the current must be reduced accordingly based on the torque equation. However, the speed of the transient response requires repeated testing and adjustments under different load conditions, resulting in low versatility. Furthermore, when using single-resistor sampling, Fluctuations in shaft current can cause the motor to... and When the difference is not significant, the motor leaves the self-stabilizing region, which in turn causes the motor to lose synchronism.

[0006] After successfully switching to the sliding mode, the motor is typically controlled using either a current closed-loop or speed closed-loop control method. For electric vehicles, the question is how to use a throttle to control the motor, ensuring it suits the user's habits while also meeting speed regulation needs under different loads. Summary of the Invention

[0007] To address the shortcomings of the existing technology, this invention provides an angle switching and throttle control method for sensorless operation of PMSM, overcoming problems such as large speed fluctuations and easy step loss during the transition process under single-resistor sampling, and designing a suitable throttle control method according to the application scenario of electric vehicles.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] The angle switching and throttle control method for sensorless operation of PMSM includes the following steps:

[0010] A) Open-loop startup phase: Setting The given current amplitude of the shaft is , of which The shaft current amplitude is initially set, and then the system starts normally in open loop to the pre-set switching speed.

[0011] B) Transition process: Gradually decrease , so that the open-loop given angle Gradually approach the true angle, while comparing. Angle estimation with sliding mode observer Size;

[0012] C) Decrease process: Gradual decrease to ;

[0013] D) Sliding mode observation stage: Set according to the following formula :

[0014] .

[0015] Furthermore, in step A), The value is not set to 0.

[0016] Furthermore, in steps B) and C), to minimize the transition process, a method of first reducing... Further reduction This method aims to reduce current fluctuations caused by dq-axis coupling.

[0017] Furthermore, in step D), K takes the value [0,1]. This is the maximum q-axis voltage when the throttle is turned. This changes accordingly, thus achieving dynamic speed regulation.

[0018] Furthermore, in step D), after entering the sliding mode observation stage, the q-axis current loop is closed, and the current loop is directly used. control.

[0019] Furthermore, the first 10% of the throttle opening is selected as the dead zone. When k=0.1, it corresponds to the switching speed of the motor, and when k=1, it corresponds to the maximum speed of the motor under the current load.

[0020] Furthermore, in step B), if If the condition for switching is met, then the value at this time is recorded as 0. for ,make This completes the transition angle switch.

[0021] Compared with the prior art, the advantages of the present invention are:

[0022] 1. Using a transition process scheme based on current amplitude change, the angle transition is achieved according to the "torque-power angle self-balancing principle", which can respond to various load conditions and the speed will not fluctuate, thus improving the comfort of electric vehicles.

[0023] 2. Open-loop start-up command The set value is not 0, which increases the stator current vector when the motor is in the self-stabilizing region. The angle range avoids the loss of synchronization caused by sampling current fluctuations in the case of single-resistor sampling;

[0024] 3. During the sliding mode observation phase, ensure the throttle opening corresponds to... This method of controlling the motor is more in line with the usage scenarios and user habits of electric vehicles;

[0025] 4. According to the transient process method and throttle control method disclosed in this invention, a sensorless control scheme for full-speed operation of PMSM can be realized, thereby reducing the cost of the control system and improving the reliability and robustness of the system. Moreover, the method has a small computational load and is easy to implement and promote. Attached Figure Description

[0026] Figure 1 This is a system structure block diagram of the angle switching and throttle control method for sensorless operation of PMSM proposed in this invention;

[0027] Figure 2 This is a schematic diagram of the ideal transition process for a surface-mount PMSM.

[0028] Figure 3 This is a schematic diagram of the ideal embedded PMSM transition process;

[0029] Figure 4 This is a schematic diagram of the transient process of a surface-mount PMSM under single-resistor sampling.

[0030] Figure 5 This is a schematic diagram of the transition process method described in this invention;

[0031] Figure 6 The throttle opening and the present invention The corresponding curve. Detailed Implementation

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1:

[0034] The angle switching and throttle control method for sensorless operation of PMSM includes the following steps:

[0035] A) Open-loop startup phase: Setting The given current amplitude of the shaft is , of which The shaft current amplitude is initially set, and then the system starts normally in open loop to the pre-set switching speed. The setting is not 0;

[0036] B) Transition process: Gradually decrease , so that the open-loop given angle Gradually approach the true angle, while comparing. Angle estimation with sliding mode observer The size, where if If the condition for switching is met, then the value at this time is recorded as 0. for ,make This completes the transition angle switch;

[0037] C) Decrease process: Gradual decrease to ;

[0038] D) Sliding mode observation stage: Set according to the following formula :

[0039] ;

[0040] To minimize the transition process, a method of first lowering is adopted. Further reduction This method aims to reduce current fluctuations caused by dq-axis coupling, where K takes values ​​of [0,1]. This is the maximum q-axis voltage when the throttle is turned. This leads to changes, enabling dynamic speed regulation. Furthermore, upon entering the sliding mode observation phase, the q-axis current loop is closed, and direct speed adjustment is employed. Control is performed by selecting the first 10% of the throttle opening as the dead zone. When k=0.1, it corresponds to the switching speed of the motor, and when k=1, it corresponds to the maximum speed of the motor under the current load.

[0041] likeFigure 1 As shown, the open-loop control system of the permanent magnet synchronous motor consists of the permanent magnet synchronous motor, drive circuit, current controller, and SVPWM module. Because it is sensorless control, there are no position and speed detection devices. During operation, the current amplitude is first set by the current amplitude setpoint module. and When the open-loop given speed When the switching speed is reached, a transition process begins, ultimately achieving the switching of angle and speed.

[0042] like Figure 2 As shown, the transient process of an ideal surface-mounted permanent magnet synchronous motor is because... Therefore, the stator current vector exist During the descent, due to the "torque-power angle self-balancing principle", It will gradually decrease. As it gradually approaches the q-axis, the torque equation of the surface-mount motor is:

[0043]

[0044] in, For extreme logarithms, As shown in the above equation, to ensure stable torque and speed during the transition process, (The text abruptly ends here, suggesting an incomplete sentence or a missing section.) Constant, that is Figure 2 middle The dashed line represents the stator current vector. The line gradually transitions along the dashed line until it coincides with the q-axis and stops. At this point, the torque-to-current ratio reaches its maximum. Therefore, only when... The motor is in the self-stabilizing region only when it is in the first quadrant.

[0045] The analysis of embedded permanent magnet synchronous motors is different, because... Its torque equation is:

[0046] in, For shaft inductance, For q-axis inductance, such as Figure 3 As shown, due to the presence of reluctance torque, The dashed line became a curve. At the maximum torque-to-current ratio, Its position is not on the q-axis, but on... At the point of tangency between the dashed line and the current circle. Therefore, as long as When the motor is located to the right of the tangent point or in the first quadrant, it will be in the self-stabilizing region.

[0047] Because the sampling accuracy of a single resistor is poor, the i obtained after reconstructing the three-phase current is... s Both amplitude and angle fluctuate, therefore the actual... It is not a definite vector but a sector, such as Figure 4 As shown, during the transition process When the axial direction approaches the q-axis, once If the sector region is outside the first quadrant, the motor will leave the self-stabilizing region, resulting in loss of synchronization and switching failure.

[0048] To address the issues arising from single-resistor sampling, the open-loop stage... Set as 0.3 times, making When the q-axis and the q-axis are nearly coincident, The sector-shaped region it is located in is still in the first quadrant, such as Figure 5 As shown, due to With the addition of [something], the stator current vector [is affected]. , No longer with The axes coincide, but are located at shaft and Between axes. This makes when The q-axis coincides with the q-axis, that is... At this point, the motor remains in the self-stabilizing region and will not lose steps. The transition process is completed smoothly, and the motor then enters the sliding mode observation stage.

[0049] Figure 6 This indicates that after entering the sliding mode observation stage, the throttle opening and The corresponding relationship is as follows. It can be seen that when the throttle opening is less than 10%, it is a dead zone. When the throttle opening is 10%-100%, From the corresponding linearly rising to It is important to note that The larger the value, the more the motor operates when switching speeds. The larger it is, the more it corresponds to The larger it gets, the bigger it becomes.

[0050] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A method for angle switching and throttle control in sensorless operation of a PMSM, characterized in that, Includes the following steps: A) Open-loop startup phase: Setting The given current amplitude of the shaft is , of which The shaft current amplitude is initially set, and then the system starts normally in open loop to the pre-set switching speed. B) Transition process: Gradually decrease , so that the open-loop given angle Gradually approach the true angle, while comparing. Angle estimation with sliding mode observer Size; C) Decrease process: Gradual decrease to ; D) Sliding mode observation stage: Set according to the following formula : ； Where K takes the value [0,1]. This is the maximum q-axis voltage when the throttle is turned. This changes accordingly, thereby achieving dynamic speed regulation. The first 10% of the throttle opening is selected as the dead zone. When K=0.1, it corresponds to the switching speed of the motor. When K=1, it corresponds to the maximum speed of the motor under the current load. To meet the switchable conditions .

2. The angle switching and throttle control method for sensorless operation of a PMSM as described in claim 1, characterized in that, In step A), The value is not set to 0.

3. The angle switching and throttle control method for sensorless operation of a PMSM as described in claim 1, characterized in that, In steps B) and C), to minimize the transition process, a method of first reducing... Further reduction This method aims to reduce current fluctuations caused by dq-axis coupling.

4. The angle switching and throttle control method for sensorless operation of a PMSM as described in claim 1, characterized in that, After entering the sliding mode observation stage in step D), the q-axis current loop is closed, and the current loop is directly used. control.

5. The angle switching and throttle control method for sensorless operation of a PMSM as described in claim 1, characterized in that, If in step B) If the condition for switching is met, then the value at this time is recorded as 0. for ,make This completes the transition angle switch.

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