Adaptive window opening method and system for three-phase sensorless AC motor

Abstract

The present invention relates to an adaptive window opening method and system for a three-phase sensorless AC motor, the method comprising the following steps: S100: after the rotation speed of the motor is stabilized, obtaining the window opening start angle and the window opening end angle of the current window opening phase; S200: before window opening, performing current zero crossing detection on the current window opening phase, and adjusting the window opening start angle of the next window opening phase according to the current zero crossing detection result, until the window opening start angle meets a first preset condition.

Description

Technical Field

[0001] The present invention relates to the technical field of three-phase inductive AC motors, and more specifically to an adaptive window opening method and system for a three-phase inductive AC motor. Background Art

[0002] In the existing closed-loop control technology of three-phase inductive AC motors, after the motor speed is stabilized, the drive of a certain phase is generally abandoned for a short time to make the phase coil present a high-impedance state (i.e., disconnected), and then the induced electromotive force (i.e., back electromotive force) of the phase is detected to determine the approximate information of the current position of the motor. Abandoning the drive of a certain phase is called windowing the phase. When opening the window, a common practice is to place the windowing start angle before the coil current passes through the zero point, that is, before the coil current passes through the zero point, artificially decay the current on the coil to zero, so that only the back electromotive force remains on the coil, and then determine the rotor position of the motor by detecting the zero point of the back electromotive force. After detecting the zero point of the back electromotive force, the phase of the window is reassigned with a specified drive angle (i.e., the current of the specified phase angle is re-introduced into the phase) for driving. The reassigned specified drive angle is the windowing end angle, and the difference between the windowing start angle and the windowing end angle is the windowing angle.

[0003] In the prior art, a fixed window opening angle (for example, 15 degrees) is usually selected. Since the inductance characteristics of coils of different models are different, the current decay time will also be different, and the time to detect the zero crossing point of the back electromotive force will also be different. For some motor models, the fixed window opening angle will be too large, resulting in a waste of drive angle and affecting the operating efficiency and performance of the motor. Summary of the invention

[0004] The object of the present invention is to provide an adaptive window opening method and system for a three-phase sensorless AC motor, which can adaptively adjust the size of the window opening angle to avoid waste of driving angle, thereby improving the operating efficiency and performance of the motor.

[0005] Based on the above purpose, the present invention provides an adaptive window opening method for a three-phase sensorless AC motor, which comprises the following steps:

[0006] S100: After the motor speed is stable, the window opening start angle and the window opening end angle of the current window opening phase are obtained;

[0007] S200: before windowing, perform current zero-crossing detection on the current windowing phase, and adjust the windowing start angle of the next windowing phase according to the current zero-crossing detection result until the windowing start angle meets the first preset condition.

[0008] Furthermore, step S200 specifically includes the following steps:

[0009] S210: before opening the window, perform current zero-crossing detection on the current window opening phase, and determine whether the current zero-crossing point appears before opening the window;

[0010] S220: If the current zero-crossing point does not appear before windowing, the windowing start angle of the next windowing phase is set to the windowing start angle of the current windowing phase plus the first preset threshold, and the windowing end angle of the next windowing phase is set to the windowing end angle of the current windowing phase; then after the windowing of the current windowing phase ends, the next windowing phase is used as the current windowing phase again, and the process returns to step S210;

[0011] S230: If the current zero-crossing point occurs before the window is opened, the phase angle of the driving current when the current crosses the zero-crossing point is obtained as the driving angle; and it is determined whether the difference between the window opening start angle of the current window opening phase and the driving angle when the current crosses the zero-crossing point exceeds a first preset threshold;

[0012] S240: If the first preset threshold is not exceeded, the first preset condition is satisfied, and the window opening start angle of the next window opening phase is set to be the same as the window opening start angle of the current window opening phase;

[0013] S250: If it exceeds the first preset threshold, the window opening starting angle of the next window opening phase is set to the driving angle when the current of the current window opening phase passes through the zero point, and the window opening ending angle of the next window opening phase is set to the window opening ending angle of the current window opening phase; then after the window opening of the current window opening phase ends, the next window opening phase is reset as the current window opening phase, and the process returns to step S210.

[0014] Furthermore, the method further comprises the following steps:

[0015] S300: After the first preset condition is met, a back electromotive force zero-crossing detection is performed on the current windowing phase, and a windowing end angle of the next windowing phase is adjusted according to the back electromotive force zero-crossing detection result to meet a second preset condition.

[0016] Furthermore, step S300 specifically includes the following steps:

[0017] S310: After the first preset condition is met, performing back electromotive force zero-crossing detection on the current windowing phase, and determining whether the back electromotive force zero-crossing point of the current windowing phase is within the windowing range of the current windowing phase;

[0018] S320: If the back electromotive force zero-crossing point is not within the windowing range of the current windowing phase, the windowing end angle of the next windowing phase is adjusted to a preset value, and then after the windowing of the current windowing phase ends, the next windowing phase is used as the current windowing phase again, and the process returns to step S210;

[0019] S330: If the back electromotive force zero-crossing point is within the window opening range of the current window opening phase, determining whether the window opening end angle of the current window opening phase and the driving angle corresponding to the back electromotive force zero-crossing point of the current window opening phase exceed a second preset threshold;

[0020] S340: If the second preset threshold is not exceeded, the second preset condition is satisfied; the window opening end angle of the next window opening phase is set to be the same as the window opening end angle of the current window opening phase, and then after the window opening of the current window opening phase ends, the next window opening phase is used as the current window opening phase again, and the process returns to step S210;

[0021] S350: If it exceeds the second preset threshold, the window opening end angle of the next window opening phase is set to the window opening end angle of the current phase minus the second preset threshold, and then after the window opening of the current window opening phase ends, the next window opening phase is reset as the current window opening phase and the process returns to step S210.

[0022] Furthermore, the first preset threshold and the second preset threshold are both 1°.

[0023] Another aspect of the present invention provides an adaptive window opening system of a three-phase sensorless AC motor, comprising:

[0024] The acquisition module is used to obtain the window opening start angle and the window opening end angle of the current window opening phase after the motor speed is stable;

[0025] The first adjustment module is used to perform current zero-crossing detection on the current windowing phase before windowing, and adjust the windowing starting angle of the next windowing phase according to the current zero-crossing detection result until the windowing starting angle meets the first preset condition.

[0026] Further, before windowing, current zero crossing detection is performed on the current windowing phase, and the windowing start angle of the next windowing phase is adjusted according to the current zero crossing detection result until the windowing start angle meets the first preset condition, specifically including:

[0027] Before opening the window, the current zero-crossing detection is performed on the current windowing phase, and it is determined whether the current zero-crossing point occurs before the windowing;

[0028] If the current zero-crossing point does not appear before windowing, the windowing start angle of the next windowing phase is set to the windowing start angle of the current windowing phase plus the first preset threshold, and the windowing end angle of the next windowing phase is set to the windowing end angle of the current windowing phase; then, after the windowing of the current windowing phase ends, the next windowing phase is used again as the current windowing phase, and the current zero-crossing detection is performed on the current windowing phase again to determine whether the current zero-crossing point appears before windowing;

[0029] If the current zero-crossing point occurs before the window is opened, the phase angle of the driving current when the current crosses the zero point is obtained as the driving angle; and it is determined whether the difference between the window opening starting angle of the current window opening phase and the driving angle when the current crosses the zero point exceeds a first preset threshold;

[0030] If the first preset threshold is not exceeded, the first preset condition is satisfied, and the window opening start angle of the next window opening phase is set to be the same as the window opening start angle of the current window opening phase;

[0031] If it exceeds the first preset threshold, the window opening starting angle of the next window opening phase is set to the driving angle when the current of the current window opening phase passes through the zero point, and the window opening ending angle of the next window opening phase is set to the window opening ending angle of the current window opening phase; then after the window opening of the current window opening phase ends, the next window opening phase is re-used as the current window opening phase, and the current zero crossing detection is performed on the current window opening phase again to determine whether the current zero crossing point appears before the window opening.

[0032] Furthermore, the system also includes:

[0033] The second adjustment module is used to perform back electromotive force zero-crossing detection on the current windowing phase after the first preset condition is met, and adjust the windowing end angle of the next windowing phase according to the back electromotive force zero-crossing detection result to meet the second preset condition.

[0034] Further, after the first preset condition is met, back electromotive force zero crossing detection is performed on the current window opening phase, and the window opening end angle of the next window opening phase is adjusted according to the back electromotive force zero crossing detection result to meet the second preset condition, specifically including:

[0035] After the first preset condition is met, back electromotive force zero-crossing detection is performed on the current windowing phase, and it is determined whether the back electromotive force zero-crossing point of the current windowing phase is within the windowing range of the current windowing phase;

[0036] If the back electromotive force zero-crossing point is not within the windowing range of the current windowing phase, the windowing end angle of the next windowing phase is adjusted to a preset value, and then after the windowing of the current windowing phase ends, the next windowing phase is used again as the current windowing phase, and the current zero-crossing detection is performed again on the current windowing phase to determine whether the current zero-crossing point appears before the windowing;

[0037] If the back electromotive force zero-crossing point is within the window opening range of the current window opening phase, determining whether the window opening end angle of the current window opening phase and the driving angle corresponding to the back electromotive force zero-crossing point of the current window opening phase exceed a second preset threshold;

[0038] If the second preset threshold is not exceeded, the second preset condition is satisfied; the window opening end angle of the next window opening phase is set to be the same as the window opening end angle of the current window opening phase, and then after the window opening of the current window opening phase ends, the next window opening phase is used again as the current window opening phase, and the current zero crossing detection is performed on the current window opening phase again to determine whether the current zero crossing point appears before the window opening;

[0039] If it exceeds the second preset threshold, the window opening end angle of the next window opening phase is set to the window opening end angle of the current phase minus the second preset threshold. Then, after the window opening of the current window opening phase ends, the next window opening phase is re-used as the current window opening phase, and the current zero crossing detection is performed on the current window opening phase again to determine whether the current zero crossing point appears before the window opening.

[0040] Furthermore, the first preset threshold and the second preset threshold are both 1°.

[0041] The adaptive window opening method and system of the three-phase sensorless AC motor of the embodiment of the present invention can maximize the window opening starting angle and minimize the window opening ending angle, thereby making the window opening angle as small as possible, avoiding waste of driving angle, and thus improving the operating efficiency and performance of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A schematic diagram of the changes of coil current, coil voltage, shielding signal and control signal over time of a three-phase inductive AC motor after the window is opened according to an embodiment of the present invention;

[0043] Figure 2 is a flow chart of an adaptive window opening method for a three-phase sensorless AC motor according to an embodiment of the present invention;

[0044] Figure 3 Flow chart of step S200 of the adaptive window opening method for a three-phase sensorless AC motor according to an embodiment of the present invention;

[0045] Figure 4 Another flow chart of the adaptive window opening method of the three-phase sensorless AC motor according to an embodiment of the present invention;

[0046] Figure 5 for Figure 4 A flowchart of step S300 of the adaptive window opening method for a three-phase sensorless AC motor;

[0047] Figure 6 4 is a structural block diagram of an adaptive window opening method for a three-phase sensorless AC motor according to an embodiment of the present invention. DETAILED DESCRIPTION

[0048] The preferred embodiments of the present invention are given below in conjunction with the accompanying drawings and described in detail.

[0049] like Figure 1 As shown, during the operation of the three-phase inductive AC motor, each phase is controlled to be on and off by a control signal HR. When HR is 1 (i.e., high level), the phase is disconnected and switched to a high-resistance state to open the window. When HR is 0 (i.e., low level), the phase is turned on to drive the phase again. At the moment of window opening, the current Icoil on the coil of the phase will immediately decay to zero. However, since the coil has a certain inductance characteristic, the voltage across the coil will have a large fluctuation after the window opening. The amplitude of the voltage fluctuation depends on the coil inductance L and the current i on the coil just before the window opening. From the formula ΔV=L*di / dt, it can be seen that the larger the current on the coil before the window opening, the longer the duration of the voltage fluctuation across the coil caused by the current mutation. The voltage fluctuation is positive or negative, so the voltage fluctuation may make the voltage across the coil zero, that is, within a period of time after the window opening, the current mutation may This causes the voltage at both ends of the coil to cross zero, and this zero crossing point is not the zero crossing point of the back electromotive force that reflects the rotor position of the motor. If this zero crossing point is used as the zero crossing point of the back electromotive force and used to determine the position of the rotor, the position of the rotor will be inaccurate. Therefore, the voltage fluctuation caused by the current mutation will affect the detection of the back electromotive force. When detecting the back electromotive force after the window is opened, the voltage Vcoil detected during the voltage fluctuation time caused by the current mutation cannot be used. The Vcoil in this period will be shielded, and the voltage Vcoil can be used only after the voltage fluctuation time has passed. At this time, Vcoil is the back electromotive force, and the rotor position of the motor can be determined by detecting its zero crossing value. The shielding or use of Vcoil can be controlled by the shielding signal Shield. When Shield is 1 (high level), Vcoil can be shielded, and when Shield is 0 (low level), Vcoil can be used.

[0050] The window opening start angle is recorded as Angle_L, the window opening end angle is recorded as Angle_R, and the angle at which the voltage fluctuation caused by the current mutation ends (i.e., the shielding end angle) is recorded as Shield_angle. In the three-phase motor drive, the theoretical coil current zero-crossing point is at a phase angle of 30°. Therefore, in the prior art, the window opening start angle Angle_L is usually set to 25 degrees, the window opening end angle Angle_R is 40 degrees, and the shielding end angle Shield_angle is 32 degrees, that is, during the time corresponding to the drive angle changing from 25° to 32°, Vcoil will be shielded, and the back electromotive force zero-crossing during this period will be discarded; during the operation of the motor, the three phases of the motor will be cyclically opened in sequence according to the pre-set window opening sequence. When each phase is opened, the window opening start angle is 25 degrees and the window opening end angle is 40°. For example, the U phase is opened first, and when the phase angle of the drive current is 25°, the phase is disconnected for windowing, and then after the time corresponding to the drive angle of 7°, the back electromotive force is detected to be zero-crossing. After the back electromotive force is detected to be zero-crossing, the drive current of the phase will be re-assigned, and the phase angle of the drive current is 40°, and then the next window is opened, and the cycle is repeated. In the prior art, the window opening angle is fixed at 15°, which may cause a waste of driving angle and affect the operating efficiency and performance of the motor.

[0051] Based on this, an embodiment of the present invention provides an adaptive window opening method for a three-phase sensorless AC motor, which dynamically adjusts the window opening starting angle and the window opening ending angle during the operation of the motor to make the window opening angle as small as possible, avoiding waste of driving angle, thereby improving the operating efficiency and performance of the motor.

[0052] like Figure 2 As shown, an embodiment of the present invention provides an adaptive window opening method for a three-phase sensorless AC motor, which includes the following steps:

[0053] S100: After the motor speed is stabilized, the window opening start angle and the window opening end angle of the current window opening phase are obtained.

[0054] The current window opening phase refers to the phase that currently needs to open the window. When the adaptive window opening method of the embodiment of the present invention is just run, the window opening start angle and the window opening end angle of the current window opening phase are both pre-set values, for example, the window opening start angle is 25°, and the window opening end angle is 40°; after running the adaptive window opening method of the embodiment of the present invention, the window opening start angle of the current window opening phase will be the adjusted angle.

[0055] S200: before window opening, perform current zero-crossing detection on the current window opening phase, and adjust the window opening starting angle of the next window opening phase according to the current zero-crossing detection result until the window opening starting angle meets the first preset condition.

[0056] The next windowing phase refers to the phase that needs to be windowed after the current windowing phase is completed.

[0057] like Figure 3 As shown, in some embodiments, step S200 specifically includes the following steps S210-S250:

[0058] S210: before opening the window, perform current zero-crossing detection on the current window opening phase, and determine whether the current zero-crossing point appears before opening the window.

[0059] When performing current zero-crossing detection, the existing current zero-crossing detection circuit can be used. When the current is detected to be 0 before the window is opened, it means that the current zero-crossing point occurs before the window is opened. When the current is not detected to be 0 before the window is opened, it means that the current zero-crossing point does not occur before the window is opened.

[0060] S220: If the current zero crossing point does not appear before window opening, the window opening starting angle of the next window opening phase is set to the window opening starting angle of the current window opening phase plus the first preset threshold, and the window opening ending angle of the next window opening phase is set to the window opening ending angle of the current window opening phase; then after the window opening of the current window opening phase ends, the next window opening phase is reset as the current window opening phase, and the process returns to step S210.

[0061] If the current zero crossing point does not appear before windowing, it means that the windowing starting angle is too small, and then the windowing starting angle of the next windowing phase needs to be increased, for example, by increasing the first preset threshold value. The first preset threshold value can be set according to actual needs, for example, 1°; the windowing ending angle of the next windowing phase remains unchanged, that is, the same as the windowing ending angle of the current windowing phase. The current windowing phase will be windowed at its windowing starting angle, and then after the back electromotive force is detected to cross zero after the windowing shielding angle, it will reopen the window, that is, reassign the phase drive current, and the phase angle of the reassigned drive current is the windowing ending angle; then the windowing of this phase ends, and the next windowing process is performed; then the adaptive windowing method of the present invention will re-detect the current zero crossing of the next windowing phase, and re-judge whether its current zero crossing point appears before windowing, that is, re-execute step S210 until the current zero crossing point appears before windowing.

[0062] S230: If the current zero point occurs before the window is opened, the phase angle of the driving current when the current passes through the zero point is obtained. For simplicity, the phase angle of the driving current is referred to as the driving angle below; and it is determined whether the difference between the window opening starting angle of the current window opening phase and the driving angle when the current passes through the zero point exceeds the first preset threshold.

[0063] If the current zero point occurs before the window is opened, it is necessary to obtain the driving angle when the current passes through the zero point and compare it with the window opening starting angle of the current window opening phase to determine whether the difference between the window opening starting angle of the current window opening phase and the driving angle when the current passes through the zero point exceeds the first preset threshold.

[0064] S240: If the first preset threshold is not exceeded, it means that the first preset condition is met, and the window opening start angle of the next window opening phase can be set to be the same as the window opening start angle of the current window opening phase.

[0065] If it does not exceed the first preset threshold, it means that the window opening starting angle of the current window opening phase is very close to the current zero crossing point, which meets the first preset condition and has been adjusted in place. Then the window opening starting angle of the next window opening phase can be set to the same as the window opening starting angle of the current window opening phase.

[0066] S250: If it exceeds the first preset threshold, the window opening starting angle of the next window opening phase is set to the driving angle when the current of the current window opening phase passes through the zero point, and the window opening ending angle of the next window opening phase is set to the window opening ending angle of the current window opening phase; then after the window opening of the current window opening phase ends, the next window opening phase is reset as the current window opening phase, and the process returns to step S210.

[0067] If it exceeds the first preset threshold, it means that the window opening start angle of the current window opening phase is too far from the driving angle when the current passes through zero, so it is necessary to set the window opening start angle of the next window opening phase to the driving angle when the current passes through zero, and set the window opening end angle of the next window opening phase to the window opening end angle of the current window opening phase, and then open the window at the updated window opening start angle the next time. Before opening the window for the next window opening phase, it is necessary to re-execute steps S210-S250 for the next window opening phase until the first preset condition is met.

[0068] Through step S200, the window opening starting angle can be increased as much as possible and adjusted to the first preset threshold after the driving angle when the current passes through the zero point. In this way, the window can be opened near the current zero point, reducing the current decay time, thereby reducing the shielding time and avoiding waste of the driving angle.

[0069] like Figure 4 As shown, in some embodiments, the adaptive window opening method of the three-phase sensorless AC motor may further include the following steps:

[0070] S300: After the first preset condition is met, a back electromotive force zero-crossing detection is performed on the current windowing phase, and the windowing end angle of the next windowing phase is adjusted according to the back electromotive force zero-crossing detection result to meet the second preset condition.

[0071] After the first preset condition is met, it means that the window opening start angle has been adjusted to the right position, so the window opening end angle can be adjusted. Figure 5 As shown, in some embodiments, step S300 specifically includes the following steps S310-S350:

[0072] S310: After the first preset condition is met, a back electromotive force zero-crossing detection is performed on the current windowing phase, and it is determined whether the back electromotive force zero-crossing point of the current windowing phase is within the windowing range of the current windowing phase.

[0073] The back electromotive force zero-crossing detection needs to be performed after the window is opened. When performing the back electromotive force zero-crossing detection, the existing back electromotive force zero-crossing detection circuit can be used for detection. If the back electromotive force is not detected to be zero-crossing during the window opening process (similar to the existing window opening method, the back electromotive force detected within the time between the window opening starting angle and the shielding angle will be shielded), it means that the back electromotive force is not within the window opening range of the current window opening phase; if the back electromotive force is detected to be zero-crossing during the window opening process, it means that the back electromotive force is within the window opening range of the current window opening phase.

[0074] S320: If the zero-crossing point of the back electromotive force is not within the windowing range of the current windowing phase, the windowing end angle of the next windowing phase is adjusted to a preset value, and then after the windowing of the current windowing phase ends, the next windowing phase is reset as the current windowing phase and the process returns to step S210.

[0075] If the zero-crossing point of the back electromotive force is not within the windowing range of the current windowing phase, it means that the windowing end angle of the current windowing phase is too small, and the windowing end angle of the next windowing phase needs to be set to the initial preset value (for example, 40°). Then, after the windowing of the current windowing phase ends, the next windowing phase is reset as the current windowing phase, and then return to step S210 to re-execute steps S210-S350.

[0076] S330: If the back electromotive force zero-crossing point is within the windowing range of the current windowing phase, determine whether the windowing end angle of the current windowing phase and the driving angle corresponding to the back electromotive force zero-crossing point of the current windowing phase exceed a second preset threshold.

[0077] If the back electromotive force zero-crossing point is within the windowing range of the current windowing phase, it is necessary to compare the windowing end angle of the current windowing phase with the driving angle corresponding to the back electromotive force zero-crossing point of the current windowing phase, and obtain the difference between the two, and then compare the difference with the second preset threshold to determine whether it exceeds the second preset threshold. The second preset threshold can be set as needed, for example, it can be 1°.

[0078] During the operation of the motor, the driving angle will increase by 1° at preset time intervals, so each degree of angle corresponds to a preset time. The driving angle corresponding to when the back electromotive force passes through zero can be obtained in the following way: calculate the time from the start of window opening to the detection of the back electromotive force passing through zero, and then infer the driving angle passed based on this time, and then add the window opening starting angle to the driving angle passed, which is the driving angle corresponding to when the back electromotive force passes through zero.

[0079] S340: If it does not exceed the second preset threshold, the second preset condition is met; the window opening end angle of the next window opening phase is set to be the same as the window opening end angle of the current window opening phase, and then after the window opening of the current window opening phase ends, the next window opening phase is reset as the current window opening phase, and the process returns to step S210.

[0080] If it does not exceed the second preset threshold, it means that the window opening end angle of the current phase has been adjusted in place and meets the second preset condition. The window opening end angle of the next window opening phase can be set to the same as the window opening end angle of the current window opening phase. Then, after the current window opening phase ends, the next window opening phase is used as the current window opening phase, and the process returns to step S210, and then steps S210-S350 are re-executed.

[0081] S350: If it exceeds the second preset threshold, the window opening end angle of the next window opening phase is set to the window opening end angle of the current phase minus the second preset threshold. Then, after the window opening of the current window opening phase ends, the next window opening phase is reset as the current window opening phase and the process returns to step S210.

[0082] If it exceeds the second preset threshold, it means that the window opening end angle of the current window opening phase is too large and needs to be reduced. Therefore, the window opening end angle of the next window opening phase can be set to the window opening end angle of the current phase minus the second preset threshold. Then, after the window opening of the current window opening phase ends, the next window opening phase is reset as the current window opening phase and the process returns to step S210.

[0083] Through step S300, the window opening end angle can be adjusted to near the driving angle corresponding to the back electromotive force zero-crossing point, thereby minimizing the window opening end angle.

[0084] To sum up, the adaptive window opening method of the three-phase sensorless AC motor in the embodiment of the present invention can maximize the window opening starting angle through step S200, and minimize the window opening ending angle through step S300, thereby making the window opening angle as small as possible, avoiding waste of driving angle, and thus improving the operating efficiency and performance of the motor.

[0085] like Figure 6As shown, an embodiment of the present invention further provides an adaptive window opening system for a three-phase inductive AC motor, which includes an acquisition module 10 and a first adjustment module 20. The acquisition module 10 is used to obtain the window opening start angle and the window opening end angle of the current window opening phase after the motor speed is stabilized; the first adjustment module 20 is used to perform current zero crossing detection on the current window opening phase before window opening, and adjust the window opening start angle of the next window opening phase according to the current zero crossing detection result until the window opening start angle meets the first preset condition.

[0086] In some embodiments, the system may further include a second adjustment module 30, which is used to perform back electromotive force zero crossing detection on the current window opening phase after the first preset condition is met, and adjust the window opening end angle of the next window opening phase according to the back electromotive force zero crossing detection result to meet the second preset condition.

[0087] In some embodiments, before windowing, current zero crossing detection is performed on the current windowing phase, and the windowing start angle of the next windowing phase is adjusted according to the current zero crossing detection result until the windowing start angle meets the first preset condition, specifically including:

[0088] Before opening the window, the current zero-crossing detection is performed on the current windowing phase, and it is determined whether the current zero-crossing point occurs before the windowing;

[0089] If the current zero-crossing point does not appear before window opening, the window opening start angle of the next window opening phase is set to the window opening start angle of the current window opening phase plus the first preset threshold, and the window opening end angle of the next window opening phase is set to the window opening end angle of the current window opening phase; then after the window opening of the current window opening phase ends, the next window opening phase is used again as the current window opening phase, and the current zero-crossing detection is performed on the current window opening phase again to determine whether the current zero-crossing point appears before window opening;

[0090] If the current zero-crossing point occurs before the window is opened, the phase angle of the driving current when the current crosses the zero point is obtained as the driving angle; and it is determined whether the difference between the window opening starting angle of the current window opening phase and the driving angle when the current crosses the zero point exceeds a first preset threshold;

[0091] If the first preset threshold is not exceeded, the first preset condition is met, and the window opening start angle of the next window opening phase is set to be the same as the window opening start angle of the current window opening phase;

[0092] If it exceeds the first preset threshold, the window opening starting angle of the next window opening phase is set to the driving angle when the current of the current window opening phase passes through the zero point, and the window opening ending angle of the next window opening phase is set to the window opening ending angle of the current window opening phase; then after the window opening of the current window opening phase ends, the next window opening phase is used as the current window opening phase again, and the current zero crossing detection is performed on the current window opening phase again to determine whether the current zero crossing point appears before the window opening.

[0093] In some embodiments, after the first preset condition is met, the back electromotive force zero crossing detection is performed on the current windowing phase, and the windowing end angle of the next windowing phase is adjusted according to the back electromotive force zero crossing detection result to meet the second preset condition, specifically including:

[0094] After the first preset condition is met, a back electromotive force zero-crossing detection is performed on the current windowing phase, and it is determined whether the back electromotive force zero-crossing point of the current windowing phase is within the windowing range of the current windowing phase;

[0095] If the back electromotive force zero-crossing point is not within the windowing range of the current windowing phase, the windowing end angle of the next windowing phase is adjusted to a preset value, and then after the windowing of the current windowing phase ends, the next windowing phase is used again as the current windowing phase, and the current zero-crossing detection is performed on the current windowing phase again to determine whether the current zero-crossing point appears before the windowing;

[0096] If the back electromotive force zero-crossing point is within the windowing range of the current windowing phase, determine whether the windowing end angle of the current windowing phase and the driving angle corresponding to the back electromotive force zero-crossing point of the current windowing phase exceed a second preset threshold;

[0097] If the second preset threshold is not exceeded, the second preset condition is met; the window opening end angle of the next window opening phase is set to be the same as the window opening end angle of the current window opening phase, and then after the window opening of the current window opening phase ends, the next window opening phase is used again as the current window opening phase, and the current zero crossing detection is performed on the current window opening phase again to determine whether the current zero crossing point appears before the window opening;

[0098] If it exceeds the second preset threshold, the window opening end angle of the next window opening phase is set to the window opening end angle of the current phase minus the second preset threshold. Then, after the window opening of the current window opening phase ends, the next window opening phase is re-used as the current window opening phase, and the current zero crossing detection is performed on the current window opening phase again to determine whether the current zero crossing point appears before the window opening.

[0099] In some embodiments, the first preset threshold and the second preset threshold are both 1°.

[0100] The adaptive window opening system of the three-phase sensorless AC motor in the embodiment of the present invention can maximize the window opening starting angle through the first adjustment module 20, and minimize the window opening ending angle through the second adjustment module 30, thereby making the window opening angle as small as possible, avoiding waste of driving angle, and thus improving the operating efficiency and performance of the motor.

[0101] The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. The above embodiment of the present invention can also be modified in various ways. That is, all simple, equivalent changes and modifications made according to the claims and the description of the present invention fall within the scope of protection of the claims of the present invention. The contents not described in detail in the present invention are all conventional technical contents.

Claims

1. An adaptive window opening method for a three-phase sensorless AC motor, characterized in that: The following steps are involved: S100: After the motor speed is stable, the window opening start angle and the window opening end angle of the current window opening phase are obtained; S200: before windowing, perform current zero-crossing detection on the current windowing phase, and adjust the windowing start angle of the next windowing phase according to the current zero-crossing detection result until the windowing start angle meets the first preset condition.

2. The adaptive window opening method of the three-phase inductive AC motor according to claim 1 is characterized in that: Step S200 specifically includes the following steps: S210: before opening the window, perform current zero-crossing detection on the current window opening phase, and determine whether the current zero-crossing point appears before opening the window; S220: If the current zero-crossing point does not appear before windowing, the windowing start angle of the next windowing phase is set to the windowing start angle of the current windowing phase plus the first preset threshold, and the windowing end angle of the next windowing phase is set to the windowing end angle of the current windowing phase; then after the windowing of the current windowing phase ends, the next windowing phase is used as the current windowing phase again, and the process returns to step S210; S230: If the current zero-crossing point occurs before the window is opened, the phase angle of the driving current when the current crosses the zero-crossing point is obtained as the driving angle; and it is determined whether the difference between the window opening start angle of the current window opening phase and the driving angle when the current crosses the zero-crossing point exceeds a first preset threshold; S240: If the first preset threshold is not exceeded, the first preset condition is satisfied, and the window opening start angle of the next window opening phase is set to be the same as the window opening start angle of the current window opening phase; S250: If it exceeds the first preset threshold, the window opening starting angle of the next window opening phase is set to the driving angle when the current of the current window opening phase passes through the zero point, and the window opening ending angle of the next window opening phase is set to the window opening ending angle of the current window opening phase; then after the window opening of the current window opening phase ends, the next window opening phase is reset as the current window opening phase, and the process returns to step S210.

3. The adaptive window opening method of the three-phase inductive AC motor according to claim 2 is characterized in that: The following steps are also included: S300: After the first preset condition is met, a back electromotive force zero-crossing detection is performed on the current windowing phase, and a windowing end angle of the next windowing phase is adjusted according to the back electromotive force zero-crossing detection result to meet a second preset condition.

4. The adaptive window opening method of the three-phase inductive AC motor according to claim 3 is characterized in that: Step S300 specifically includes the following steps: S310: After the first preset condition is met, performing back electromotive force zero-crossing detection on the current windowing phase, and determining whether the back electromotive force zero-crossing point of the current windowing phase is within the windowing range of the current windowing phase; S320: If the back electromotive force zero-crossing point is not within the windowing range of the current windowing phase, the windowing end angle of the next windowing phase is adjusted to a preset value, and then after the windowing of the current windowing phase ends, the next windowing phase is used as the current windowing phase again, and the process returns to step S210; S330: If the back electromotive force zero-crossing point is within the window opening range of the current window opening phase, determining whether the window opening end angle of the current window opening phase and the driving angle corresponding to the back electromotive force zero-crossing point of the current window opening phase exceed a second preset threshold; S340: If the second preset threshold is not exceeded, the second preset condition is satisfied; the window opening end angle of the next window opening phase is set to be the same as the window opening end angle of the current window opening phase, and then after the window opening of the current window opening phase ends, the next window opening phase is used as the current window opening phase again, and the process returns to step S210; S350: If it exceeds the second preset threshold, the window opening end angle of the next window opening phase is set to the window opening end angle of the current phase minus the second preset threshold, and then after the window opening of the current window opening phase ends, the next window opening phase is reset as the current window opening phase and the process returns to step S210.

5. The adaptive window opening method of a three-phase sensorless AC motor according to claim 4, characterized in that: The first preset threshold and the second preset threshold are both 1°.

6. An adaptive window opening system of a three-phase sensorless AC motor, characterized in that: include: The acquisition module is used to obtain the window opening start angle and the window opening end angle of the current window opening phase after the motor speed is stable; The first adjustment module is used to perform current zero-crossing detection on the current windowing phase before windowing, and adjust the windowing starting angle of the next windowing phase according to the current zero-crossing detection result until the windowing starting angle meets the first preset condition.

7. The adaptive window opening system of the three-phase inductive AC motor according to claim 6, characterized in that: Before windowing, current zero-crossing detection is performed on the current windowing phase, and the windowing start angle of the next windowing phase is adjusted according to the current zero-crossing detection result until the windowing start angle meets the first preset condition, specifically including: Before opening the window, the current zero-crossing detection is performed on the current windowing phase, and it is determined whether the current zero-crossing point occurs before the windowing; If the current zero-crossing point does not appear before windowing, the windowing start angle of the next windowing phase is set to the windowing start angle of the current windowing phase plus the first preset threshold, and the windowing end angle of the next windowing phase is set to the windowing end angle of the current windowing phase; then, after the windowing of the current windowing phase ends, the next windowing phase is used again as the current windowing phase, and the current zero-crossing detection is performed on the current windowing phase again to determine whether the current zero-crossing point appears before windowing; If the current zero-crossing point occurs before the window is opened, the phase angle of the driving current when the current crosses the zero point is obtained as the driving angle; and it is determined whether the difference between the window opening starting angle of the current window opening phase and the driving angle when the current crosses the zero point exceeds a first preset threshold; If the first preset threshold is not exceeded, the first preset condition is satisfied, and the window opening start angle of the next window opening phase is set to be the same as the window opening start angle of the current window opening phase; If it exceeds the first preset threshold, the window opening starting angle of the next window opening phase is set to the driving angle when the current of the current window opening phase passes through the zero point, and the window opening ending angle of the next window opening phase is set to the window opening ending angle of the current window opening phase; then after the window opening of the current window opening phase ends, the next window opening phase is re-used as the current window opening phase, and the current zero crossing detection is performed on the current window opening phase again to determine whether the current zero crossing point appears before the window opening.

8. The adaptive window opening system of the three-phase inductive AC motor according to claim 7, characterized in that: Also includes: The second adjustment module is used to perform back electromotive force zero-crossing detection on the current windowing phase after the first preset condition is met, and adjust the windowing end angle of the next windowing phase according to the back electromotive force zero-crossing detection result to meet the second preset condition.

9. The adaptive window opening system of the three-phase inductive AC motor according to claim 8, characterized in that: After the first preset condition is met, the back electromotive force zero crossing detection is performed on the current window opening phase, and the window opening end angle of the next window opening phase is adjusted according to the back electromotive force zero crossing detection result to meet the second preset condition, specifically including: After the first preset condition is met, back electromotive force zero-crossing detection is performed on the current windowing phase, and it is determined whether the back electromotive force zero-crossing point of the current windowing phase is within the windowing range of the current windowing phase; If the back electromotive force zero-crossing point is not within the windowing range of the current windowing phase, the windowing end angle of the next windowing phase is adjusted to a preset value, and then after the windowing of the current windowing phase ends, the next windowing phase is used again as the current windowing phase, and the current zero-crossing detection is performed again on the current windowing phase to determine whether the current zero-crossing point appears before the windowing; If the back electromotive force zero-crossing point is within the window opening range of the current window opening phase, determining whether the window opening end angle of the current window opening phase and the driving angle corresponding to the back electromotive force zero-crossing point of the current window opening phase exceed a second preset threshold; If the second preset threshold is not exceeded, the second preset condition is satisfied; the window opening end angle of the next window opening phase is set to be the same as the window opening end angle of the current window opening phase, and then after the window opening of the current window opening phase ends, the next window opening phase is used again as the current window opening phase, and the current zero crossing detection is performed on the current window opening phase again to determine whether the current zero crossing point appears before the window opening; If it exceeds the second preset threshold, the window opening end angle of the next window opening phase is set to the window opening end angle of the current phase minus the second preset threshold. Then, after the window opening of the current window opening phase ends, the next window opening phase is re-used as the current window opening phase, and the current zero crossing detection is performed on the current window opening phase again to determine whether the current zero crossing point appears before the window opening.

10. The adaptive window opening system of the three-phase sensorless AC motor according to claim 9, characterized in that: The first preset threshold and the second preset threshold are both 1°.

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