Zero-crossing detection method and device for DC brushless motor and DC brushless motor

Abstract

The present invention relates to the field of voltage data processing, and in particular to a zero-crossing detection method, device, and DC brushless motor for a DC brushless motor. The zero-crossing detection method for a DC brushless motor comprises: obtaining the phase voltages of the three phases at preset intervals; determining a virtual midpoint voltage based on the phase voltages of the three phases and adjusting it based on historical data of the virtual midpoint voltage; determining a suspended phase based on the currents of the three phases, and determining the voltage variable of the suspended phase based on the voltage of the suspended phase; determining a hysteresis threshold based on a preset value; determining a target point based on the voltage variable of the suspended phase, the virtual midpoint voltage, the phase voltage of the suspended phase, and the hysteresis threshold; determining a zero-crossing point in the determined target point based on the commutation delay time; and updating the preset value based on the number of target points. The present invention solves the problem of insufficient accuracy of zero-crossing points in zero-crossing detection.

Description

Technical Field

[0001] The present invention relates to the field of voltage data processing, and in particular to a zero-crossing detection method and device for a direct current brushless motor and the direct current brushless motor. Background Art

[0002] Zero-point detection is an essential technology for sensorless control of brushless direct current (BLDC) motors. By precisely capturing the moment when the voltage signal on the motor's stator transitions from a high to a low level, the motor controller can accurately determine the position of the motor's rotor, thereby achieving precise control of the motor's motion.

[0003] For zero point detection, voltage data needs to be collected for detection. The current method is to perform high-frequency voltage sampling on the three phases of the DC brushless motor through a hardware circuit to obtain three-phase voltage data, and then perform software de-bouncing on the burrs of the obtained three-phase voltage data to obtain stable three-phase voltage data.

[0004] In this way, although the abnormal data caused by glitches is removed by software debouncing, the voltage data sampled from the suspended phase itself may have errors, especially when the DC brushless motor is in the acceleration stage. The accuracy of the voltage data of the suspended phase affects the accuracy of the zero crossing point and thus affects the smoothness of the commutation of the DC brushless motor. Therefore, there is a problem of insufficient accuracy of the zero crossing point in zero-crossing detection. Summary of the Invention

[0005] Based on this, it is necessary to provide a zero-crossing detection method and device for a brushless DC motor and a brushless DC motor to address the above problems.

[0006] The embodiment of the present invention is implemented as follows: a zero-crossing detection method for a brushless DC motor, the zero-crossing detection method for a brushless DC motor comprising:

[0007] S101, obtaining three-phase voltages at preset intervals;

[0008] S102, determining a virtual midpoint voltage according to the three-phase phase voltages and adjusting the virtual midpoint voltage according to historical data of the virtual midpoint voltage;

[0009] S103, determining a suspended phase according to the three-phase currents, and determining a voltage variable of the suspended phase according to the voltage of the suspended phase;

[0010] S104, determining a hysteresis threshold according to a preset value;

[0011] S105, determining a target point according to the voltage variable of the suspended phase, the virtual midpoint voltage, the phase voltage of the suspended phase, and the hysteresis threshold;

[0012] S106, determining a zero-crossing point from the determined target points according to the commutation delay time;

[0013] S107: Update the preset value according to the number of target points.

[0014] In one embodiment, the present invention provides a zero-crossing detection device for a brushless DC motor, the zero-crossing detection device for a brushless DC motor comprising:

[0015] A voltage acquisition module is used to obtain the three-phase voltages at preset intervals;

[0016] A midpoint determination module is used to determine a virtual midpoint voltage according to the three-phase phase voltages and adjust the virtual midpoint voltage according to historical data of the virtual midpoint voltage;

[0017] A rate determination module is used to determine the suspended phase according to the currents of the three phases, and to determine the voltage variable of the suspended phase according to the voltage of the suspended phase;

[0018] A threshold determination module, configured to determine a hysteresis threshold according to a preset value;

[0019] A target point determination module is used to determine the target point according to the voltage variable of the suspended phase, the virtual midpoint voltage, the phase voltage of the suspended phase and the hysteresis threshold;

[0020] A zero-crossing point determination module is used to determine a zero-crossing point in the determined target point according to the commutation delay time;

[0021] The preset value updating module is used to update the preset value according to the number of target points.

[0022] In one embodiment, the present invention provides a brushless DC motor, the brushless DC motor comprising a motor device and a control module for controlling the motor device;

[0023] The motor device is used to realize the rotation function to realize the function of a brushless DC motor;

[0024] The control module is used to execute the steps of the above-mentioned zero-crossing detection method for a brushless DC motor.

[0025] A zero-crossing detection method for a brushless DC motor provided by an embodiment of the present invention obtains three-phase phase voltages at preset intervals; determines a virtual midpoint voltage based on the three-phase phase voltages and adjusts it based on historical data of the virtual midpoint voltages; determines a suspended phase based on the three-phase currents and determines a voltage variable of the suspended phase based on the voltage of the suspended phase; determines a hysteresis threshold based on a preset value; determines a target point based on the voltage variable of the suspended phase, the virtual midpoint voltage, the phase voltage of the suspended phase, and the hysteresis threshold; determines a zero-crossing point from the determined target points based on a commutation delay time; and updates the preset value based on the number of target points. In this way, during the process of determining the zero-crossing point, the virtual midpoint voltage is first adjusted in real time, and then the hysteresis threshold is adjusted in real time. Reference data is adjusted before determining the zero-crossing point, thereby completing the adjustment of the zero-crossing point determined based on the virtual midpoint voltage and the hysteresis threshold to improve the accuracy of the zero-crossing point, thereby solving the problem of insufficient accuracy of the zero-crossing point in zero-crossing detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a flow chart of a zero-crossing detection method for a brushless DC motor in one embodiment;

[0027] Figure 2 This is a schematic diagram showing how the three-phase voltage changes with the electrical angle under ideal conditions;

[0028] Figure 3 This is a structural block diagram of a zero-crossing detection device for a brushless DC motor in one embodiment;

[0029] Figure 4 FIG. 4 is a block diagram of the internal structure of a control module in one embodiment. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0031] It is understood that the terms "first," "second," etc., used herein may be used to describe various elements, but unless otherwise specified, these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, a first xx script may be referred to as a second xx script, and similarly, a second xx script may be referred to as a first xx script without departing from the scope of the present invention.

[0032] like Figure 1 As shown, in one embodiment, a zero-crossing detection method for a brushless DC motor is proposed, which may specifically include the following steps:

[0033] S101, obtaining three-phase voltages at preset intervals;

[0034] S102, determining a virtual midpoint voltage according to the three-phase phase voltages and adjusting the virtual midpoint voltage according to historical data of the virtual midpoint voltage;

[0035] S103, determining a suspended phase according to the three-phase currents, and determining a voltage variable of the suspended phase according to the voltage of the suspended phase;

[0036] S104, determining a hysteresis threshold according to a preset value;

[0037] S105, determining a target point according to the voltage variable of the suspended phase, the virtual midpoint voltage, the phase voltage of the suspended phase, and the hysteresis threshold;

[0038] S106, determining a zero-crossing point from the determined target points according to the commutation delay time;

[0039] S107: Update the preset value according to the number of target points.

[0040] In this embodiment, the brushless DC motor has three phases U, V, and W, and each phase is provided with a corresponding voltage detection circuit to monitor and obtain the phase voltages of the three phases U, V, and W.

[0041] In this embodiment, the preset time is related to the rated speed and the number of pole pairs of the brushless DC motor. The greater the rated speed, the shorter the preset time should be set. Generally, it can be set to 1 ms or even less.

[0042] In this embodiment, the virtual midpoint voltage is a reference voltage generated by a three-phase resistor network circuit.

[0043] In this embodiment, the suspended phase is determined based on the current of the three phases. During the operation of the DC brushless motor, current will be input and output from two phases of the three phases. In theory, the phase without current is the suspended phase. However, due to the magnetic field, the suspended phase will also have an induced current, but the induced current is small, while the input current and output current are large, so it is easy to distinguish.

[0044] In this embodiment, the phase voltage of the suspended phase is the sum of the back electromotive force generated by the magnetic field and the noise. Although the noise is eliminated by circuits such as low-pass filtering, the determination of the zero-crossing point still requires further confirmation.

[0045] In this embodiment, the hysteresis threshold is used to set a tolerance interval for determining the target point. The target point can only be effectively determined if the tolerance interval is exceeded. The hysteresis threshold can reduce false determinations caused by noise.

[0046] In this embodiment, there may be multiple target points. This is because even if the hysteresis threshold is set as a tolerance interval, voltage fluctuations will still exist.

[0047] In this embodiment, the zero-crossing point does not necessarily have to be a specific target point; it can also be any point between two target points. The primary purpose of determining the zero-crossing point is to perform commutation. Therefore, it is only necessary to determine whether the electrical angle has rotated by 30° after the zero-crossing point is determined. If so, commutation is performed. Furthermore, to determine whether the electrical angle has rotated by 30°, the latest commutation delay time can be obtained from historical commutation delay times.

[0048] In this embodiment, the preset value updated in S107 is used in S104 of the next cycle.

[0049] In this embodiment, if Figure 2 As shown, for the V phase, when the electrical angle is 4π / 6, it is a zero crossing point. At this time, after π / 6 (that is, 5π / 6), the phase is changed. After the phase change, the suspended phase changes from the V phase to the U phase. At this time, the current will be input and output in the V phase and the W phase.

[0050] A zero-crossing detection method for a brushless DC motor provided by an embodiment of the present invention obtains three-phase phase voltages at preset intervals; determines a virtual midpoint voltage based on the three-phase phase voltages and adjusts it based on historical data of the virtual midpoint voltages; determines a suspended phase based on the three-phase currents and determines a voltage variable of the suspended phase based on the voltage of the suspended phase; determines a hysteresis threshold based on a preset value; determines a target point based on the voltage variable of the suspended phase, the virtual midpoint voltage, the phase voltage of the suspended phase, and the hysteresis threshold; determines a zero-crossing point from the determined target points based on a commutation delay time; and updates the preset value based on the number of target points. In this way, during the process of determining the zero-crossing point, the virtual midpoint voltage is first adjusted in real time, and then the hysteresis threshold is adjusted in real time. Reference data is adjusted before determining the zero-crossing point, thereby completing the adjustment of the zero-crossing point determined based on the virtual midpoint voltage and the hysteresis threshold to improve the accuracy of the zero-crossing point, thereby solving the problem of insufficient accuracy of the zero-crossing point in zero-crossing detection.

[0051] In one embodiment, determining the virtual midpoint voltage according to the three-phase phase voltages and adjusting the virtual midpoint voltage according to historical data of the virtual midpoint voltage includes:

[0052] Depend on Determine the current virtual midpoint voltage V N ;

[0053] Get the current virtual midpoint voltage V N a first preset number of previous virtual midpoint voltages;

[0054] Depend on Get the deviation value;

[0055] Determine whether the deviation value is within the preset range. If so, The current virtual midpoint voltage V N Adjust, if not, according to the current virtual midpoint voltage V N The first preset number of virtual midpoint voltages before the current virtual midpoint voltage V N Make adjustments;

[0056] Among them, V U is the phase voltage of phase U, V V is the phase voltage of phase V, V W is the phase voltage of phase W, n is the first preset number, i is the sequence number of the first preset number of virtual midpoint voltages, V i is the i-th virtual mid-point voltage among the first preset number of virtual mid-point voltages.

[0057] In this embodiment, the current virtual midpoint voltage V is obtained. N The first preset number of virtual midpoint voltages is to obtain the latest historical data of the virtual midpoint voltage, and the number is the first preset number.

[0058] In this embodiment, the first preset number can be set to 10 or more. If the number of virtual midpoint voltages in the historical data is less than the first preset number, then n can be recorded as the number of virtual midpoint voltages in the historical data.

[0059] In this embodiment, if the deviation value is within the preset range, it indicates that the brushless DC motor has passed the stage of rapid speed increase and entered the stable period. At this time, it is only necessary to adjust the virtual midpoint voltage V N Since the deviation value can only be positive, the preset range can be set to 0 to 5% of the total.

[0060] In one embodiment, the current virtual midpoint voltage V N The first preset number of virtual midpoint voltages before the current virtual midpoint voltage V N Make adjustments, including:

[0061] Depend on Determine the current virtual midpoint voltage V N The change rate corresponding to the previous virtual midpoint voltage;

[0062] The acceleration model is obtained by linear fitting according to the change rate corresponding to the virtual midpoint voltage, and the value of k in the acceleration model is obtained by fitting the parameters using the least square method;

[0063] according to Determine the current virtual midpoint voltage V N The estimated value of V x ;

[0064] according to The current virtual midpoint voltage V N Make adjustments;

[0065] Wherein, n is the first preset number, i is the sequence number of the first preset number of virtual midpoint voltages, V i is the i-th virtual midpoint voltage in the first preset number of virtual midpoint voltages, t is the preset time, V n is the nth virtual midpoint voltage among the first preset number of virtual midpoint voltages, V n-1 is the n-1th virtual midpoint voltage among the first preset number of virtual midpoint voltages, a n V n is a change rate corresponding to the nth virtual mid-point voltage among the first preset number of virtual mid-point voltages.

[0066] In this embodiment, the change rate corresponding to the virtual midpoint voltage refers to the acceleration of the voltage change between two adjacent time points, and the interval between the two adjacent time points is the preset time.

[0067] In this embodiment, when i is n, V i+1 It's V N .

[0068] In this embodiment, the current virtual midpoint voltage V N The change rate corresponding to the previous virtual midpoint voltage is represented by a1, a2...a n So the acceleration model can be expressed in a i It is represented in a two-dimensional coordinate system with time as the horizontal axis and time as the vertical axis.

[0069] In this embodiment, ,in, is the recursive voltage change rate, which is eliminated during the transformation process, specifically expressed as ; is the recursive change rate, which is eliminated during the variation process, specifically: , so .

[0070] In one embodiment, determining the voltage variable of the suspended phase according to the voltage of the suspended phase includes:

[0071] Get the latest phase voltage u1 of the suspended phase and the previous phase voltage u2 of the latest phase voltage;

[0072] Depend on Get the voltage variable of the suspended phase.

[0073] In this embodiment, the previous phase voltage u2 of the latest phase voltage is the latest phase voltage u1 of the suspended phase at the previous preset time.

[0074] In one embodiment, determining the hysteresis threshold according to a preset value includes:

[0075] Determine whether a preset value exists. If not, measure the noise peak-to-peak value u3 using an oscilloscope.

[0076] Depend on Obtaining a preset value and setting the preset value as a hysteresis threshold;

[0077] If there is a preset value, the preset value is set as the hysteresis threshold;

[0078] Where a is the preset coefficient.

[0079] In this embodiment, a can be set to 1.5 or higher. When setting the hysteresis threshold by oscilloscope measurement, a 50% safety margin is generally reserved.

[0080] In this embodiment, the specific steps of the oscilloscope measurement method are: connecting the oscilloscope probe to the suspended phase voltage detection point (such as the comparator input terminal); running the DC brushless motor at no load and observing the signal waveform; and measuring the peak-to-peak value of the noise u3.

[0081] In one embodiment, determining the target point according to the voltage variable of the suspended phase, the virtual midpoint voltage, the phase voltage of the suspended phase, and the hysteresis threshold includes:

[0082] Determine whether the phase voltage of the suspended phase is equal to the sum of the virtual midpoint voltage and the hysteresis threshold. If so, determine whether the voltage variable of the suspended phase is within a first preset range. If so, determine the electrical angle corresponding to the phase voltage of the suspended phase that is equal to the sum of the virtual midpoint voltage and the hysteresis threshold as the target point.

[0083] If the voltage variable of the suspended phase is not within the first preset range, determining whether the voltage variable of the suspended phase is within the second preset range; if so, determining the electrical angle corresponding to the phase voltage of the suspended phase that is equal to the sum of the virtual midpoint voltage and the hysteresis threshold as the target point; if not, no operation is performed;

[0084] If the phase voltage of the floating phase is not equal to the sum of the virtual neutral voltage and the hysteresis threshold, no action is performed.

[0085] In this embodiment, ideally, the phase voltage of the suspended phase is considered to have reached the zero crossing point when it equals the virtual midpoint voltage. However, the phase voltage of the suspended phase actually fluctuates. Therefore, the phase voltage of the suspended phase must effectively exceed the tolerance range of the virtual midpoint voltage. That is, the phase voltage of the suspended phase is considered to have reached the zero crossing point only when it equals the sum of the virtual midpoint voltage and the hysteresis threshold. However, if a sudden change such as a glitch occurs, the phase voltage of the suspended phase may also exceed the tolerance range of the virtual midpoint voltage. Therefore, it is necessary to determine whether the voltage variable of the suspended phase is within the first preset range.

[0086] In this embodiment, the voltage variable d of the suspended phase in the process from the zero crossing point to the electrical angle rotation of 30° in the historical data is obtained. The first preset range can be set to be between 0.5d and 1.5d. The second preset range is opposite to the first preset range and can be set to be between -0.5d and -1.5d.

[0087] In one embodiment, determining whether there is a commutation delay time, and if so, obtaining a second preset number of commutation delay times;

[0088] Depend on Estimate the next commutation delay time T x ;

[0089] according to Get the estimated electrical angle at the commutation moment;

[0090] The target point closest to the estimated electrical angle is determined as the zero-crossing point;

[0091] If there is no commutation delay time, the middle value between the first target point and the last target point is determined as the zero crossing point;

[0092] Wherein, m is the value of the second preset number, T m is the mth commutation delay time, T y is the moment corresponding to the last zero crossing point, and P is the number of pole pairs of the brushless DC motor.

[0093] In this embodiment, the second preset number may be set to 4. If the number of commutation delay times in the historical data has not yet reached 4, it is considered that there is no commutation delay time.

[0094] In this embodiment, after the zero-crossing point is detected, a delay of 30° electrical angle is required before commutation. The time taken for the delay of 30° electrical angle is the commutation delay time.

[0095] In this embodiment, the current zero-crossing point is still in the process of being determined, while the previous zero-crossing point has been determined, so the corresponding time is also clear.

[0096] In this embodiment, the interval between the two zero crossing points is 60 degrees in electrical angle, and Tx It is the time it takes to delay 30° electrical angle, so we use . , f is the fundamental frequency of the back electromotive force, specifically . is the real-time speed.

[0097] In this embodiment, it should be noted that the electrical angle ranges from 0 to 360°. Therefore, if the estimated electrical angle exceeds 360°, 360° needs to be subtracted from the estimated electrical angle to keep it within the electrical angle range.

[0098] In one embodiment, updating the preset value according to the number of target points includes:

[0099] S801, determine whether the number of target points is greater than a third preset number, if so, according to Update the preset value;

[0100] S802: If the number of target points is less than or equal to the third preset number, determine whether the number of target points is less than the fourth preset number. If so, Update the preset value, if not, do not update the preset value;

[0101] S803, setting the preset value of the completed update as the hysteresis threshold;

[0102] S804, determining a target point based on the voltage variable of the suspended phase, the virtual midpoint voltage, the phase voltage of the suspended phase, and the hysteresis threshold;

[0103] S805, determining whether the number of target points is between the third preset number and the fourth preset number; if not, re-execute S801-S804 until the number of target points is between the third preset number and the fourth preset number;

[0104] Wherein, c is the preset value before updating.

[0105] In this embodiment, the third preset number can be set to 10. The fourth preset number can be set to any value between 2 and 5. The third preset number and the fourth preset value can generally be determined based on historical data. An area where the number of target points is concentrated in the historical data is obtained, and the upper limit of the concentrated area is determined as the third preset number, and the lower limit is determined as the fourth preset number.

[0106] In this embodiment, if the number of target points is between the third and fourth preset numbers, the preset value is set normally and does not need to be changed. If the number of target points is greater than the third preset number, the preset value is set too low and needs to be increased. If the number of target points is less than the fourth preset number, the preset value is set too high and needs to be reduced.

[0107] In this embodiment, the purpose of S803 and S804 is to determine whether the preset value is updated, and has nothing to do with determining the zero crossing point. At this time, the voltage variable of the suspended phase, the virtual midpoint voltage, the phase voltage of the suspended phase and the hysteresis threshold used in S804 are consistent with the data in S103, and are data within the same preset time, and do not involve the processing of new data within the next preset time.

[0108] like Figure 3 As shown, in one embodiment, a zero-crossing detection device for a brushless DC motor is provided, which may specifically include:

[0109] A voltage acquisition module is used to obtain the three-phase voltages at preset intervals;

[0110] A midpoint determination module is used to determine a virtual midpoint voltage according to the three-phase phase voltages and adjust the virtual midpoint voltage according to historical data of the virtual midpoint voltage;

[0111] A rate determination module is used to determine the suspended phase according to the currents of the three phases, and to determine the voltage variable of the suspended phase according to the voltage of the suspended phase;

[0112] A threshold determination module, configured to determine a hysteresis threshold according to a preset value;

[0113] A target point determination module is used to determine the target point according to the voltage variable of the suspended phase, the virtual midpoint voltage, the phase voltage of the suspended phase and the hysteresis threshold;

[0114] A zero-crossing point determination module is used to determine a zero-crossing point in the determined target point according to the commutation delay time;

[0115] The preset value updating module is used to update the preset value according to the number of target points.

[0116] In this embodiment, the modules of the zero-crossing detection device for a brushless DC motor are modularized in the method part of the present invention. For the detailed explanation of each module, please refer to the corresponding content of the method part of the present invention, and the embodiments of the present invention will not be repeated here.

[0117] In one embodiment, a brushless DC motor is provided, which may specifically include: a motor device and a control module for controlling the motor device;

[0118] The motor device is used to realize the rotation function to realize the function of a brushless DC motor;

[0119] The control module is used to execute the steps of the above-mentioned zero-crossing detection method for a brushless DC motor.

[0120] In this embodiment, the motor module includes a stator, a rotor, a position sensor, an electronic commutator, etc.

[0121] In this embodiment, the brushless DC motor further includes a mechanical support module and a heat dissipation module.

[0122] A brushless DC motor provided by an embodiment of the present invention obtains three-phase phase voltages at preset intervals; determines a virtual midpoint voltage based on the three-phase phase voltages and adjusts it based on historical data of the virtual midpoint voltages; determines a suspended phase based on the three-phase currents and determines a voltage variable of the suspended phase based on the voltage of the suspended phase; determines a hysteresis threshold based on a preset value; determines a target point based on the voltage variable of the suspended phase, the virtual midpoint voltage, the phase voltage of the suspended phase, and the hysteresis threshold; determines a zero-crossing point from the determined target points based on a commutation delay time; and updates the preset value based on the number of target points. In this way, during the process of determining the zero-crossing point, the virtual midpoint voltage is first adjusted in real time, and then the hysteresis threshold is adjusted in real time. Reference data is adjusted before determining the zero-crossing point, thereby completing the adjustment of the zero-crossing point determined based on the virtual midpoint voltage and the hysteresis threshold to improve the accuracy of the zero-crossing point, thereby solving the problem of insufficient accuracy of the zero-crossing point in zero-crossing detection.

[0123] Figure 4 FIG. 1 shows an internal structure diagram of a control module in an embodiment. Figure 4 As shown, the control module includes a processor, a memory, a network interface, an input device and a display screen connected via a system bus. The memory includes a non-volatile storage medium and an internal memory. The non-volatile storage medium of the control module stores an operating system and may also store a computer program. When the computer program is executed by the processor, the processor may implement a zero-crossing detection method for a brushless DC motor provided in an embodiment of the present invention. The internal memory may also store a computer program. When the computer program is executed by the processor, the processor may implement a zero-crossing detection method for a brushless DC motor provided in an embodiment of the present invention. The display screen of the control module may be a liquid crystal display or an electronic ink display screen, and the input device of the control module may be a touch layer covering the display screen, or a button, trackball or touchpad provided on the housing of the control module, or an external keyboard, touchpad or mouse.

[0124] Those skilled in the art will understand that Figure 4 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present invention, and does not constitute a limitation on the control module to which the solution of the present invention is applied. The specific control module may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0125] In one embodiment, a zero-crossing detection device for a brushless DC motor provided by an embodiment of the present invention can be implemented in the form of a computer program. The computer program can be used in Figure 4 The memory of the control module can store various program modules constituting the zero-crossing detection device for the brushless DC motor, such as: Figure 3 The computer program consisting of the voltage acquisition module, midpoint determination module, rate determination module, threshold determination module, target point determination module, zero-crossing point determination module, and preset value update module shown in the figure enables the processor to execute the steps of the zero-crossing detection method for a brushless DC motor according to various embodiments of the present invention described in this specification.

[0126] For example, Figure 4 The control module shown can be Figure 3 The voltage acquisition module in the zero-crossing detection device for a brushless DC motor shown in the figure executes step S101; the control module can execute step S102 by determining the midpoint module; the control module can execute step S103 by determining the rate module; the control module can execute step S104 by determining the threshold module; the control module can execute step S105 by determining the target point module; the control module can execute step S106 by determining the zero-crossing point module; and the control module can execute step S107 by updating the preset value module.

[0127] In one embodiment, a control module is provided. The control module includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the following steps are implemented:

[0128] S101, obtaining three-phase voltages at preset intervals;

[0129] S102, determining a virtual midpoint voltage according to the three-phase phase voltages and adjusting the virtual midpoint voltage according to historical data of the virtual midpoint voltage;

[0130] S103, determining a suspended phase according to the three-phase currents, and determining a voltage variable of the suspended phase according to the voltage of the suspended phase;

[0131] S104, determining a hysteresis threshold according to a preset value;

[0132] S105, determining a target point according to the voltage variable of the suspended phase, the virtual midpoint voltage, the phase voltage of the suspended phase, and the hysteresis threshold;

[0133] S106, determining a zero-crossing point from the determined target points according to the commutation delay time;

[0134] S107: Update the preset value according to the number of target points.

[0135] In one embodiment, a computer-readable storage medium is provided. The computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the processor performs the following steps:

[0136] S101, obtaining three-phase voltages at preset intervals;

[0137] S102, determining a virtual midpoint voltage according to the three-phase phase voltages and adjusting the virtual midpoint voltage according to historical data of the virtual midpoint voltage;

[0138] S103, determining a suspended phase according to the three-phase currents, and determining a voltage variable of the suspended phase according to the voltage of the suspended phase;

[0139] S104, determining a hysteresis threshold according to a preset value;

[0140] S105, determining a target point according to the voltage variable of the suspended phase, the virtual midpoint voltage, the phase voltage of the suspended phase, and the hysteresis threshold;

[0141] S106, determining a zero-crossing point from the determined target points according to the commutation delay time;

[0142] S107: Update the preset value according to the number of target points.

[0143] It should be understood that, although the various steps in the flow chart of each embodiment of the present invention are shown in sequence according to the indication of the arrows, these steps are not necessarily performed in sequence according to the order indicated by the arrows. Unless otherwise specified herein, the execution of these steps is not strictly limited in order, and these steps can be performed in other orders. Moreover, at least a portion of the steps in each embodiment may include a plurality of sub-steps or a plurality of stages, and these sub-steps or stages are not necessarily performed at the same time, but can be performed at different times, and the execution order of these sub-steps or stages is not necessarily performed in sequence, but can be performed in turn or alternately with at least a portion of other steps or sub-steps or stages of other steps.

[0144] Those skilled in the art will appreciate that all or part of the processes in the above-described method embodiments can be implemented by instructing the relevant hardware through a computer program. The program can be stored in a non-volatile computer-readable storage medium. When executed, the program can include the processes of the above-described method embodiments. Any reference to memory, storage, database, or other media used in the various embodiments provided herein may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct RAMbus dynamic RAM (DRDRAM), and RAMbus dynamic RAM (RDRAM).

[0145] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0146] The above-described embodiments merely illustrate several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

Claims

1. A zero-crossing detection method for a brushless DC motor, characterized in that: The zero-crossing detection method for the brushless DC motor comprises: S101, obtaining three-phase voltages at preset intervals; S102, determining a virtual midpoint voltage according to the three-phase phase voltages and adjusting the virtual midpoint voltage according to historical data of the virtual midpoint voltage; S103, determining a suspended phase according to the three-phase currents, and determining a voltage variable of the suspended phase according to the voltage of the suspended phase; S104, determining a hysteresis threshold according to a preset value; S105, determining a target point according to the voltage variable of the suspended phase, the virtual midpoint voltage, the phase voltage of the suspended phase, and the hysteresis threshold; S106, determining a zero-crossing point from the determined target points according to the commutation delay time; S107, updating the preset value according to the number of target points; Determining the virtual midpoint voltage according to the three-phase phase voltages and adjusting the virtual midpoint voltage according to historical data of the virtual midpoint voltage includes: Depend on Determine the current virtual midpoint voltage V N ; Get the current virtual midpoint voltage V N a first preset number of previous virtual midpoint voltages; Depend on Get the deviation value; Determine whether the deviation value is within the preset range. If so, The current virtual midpoint voltage V N Adjust, if not, according to the current virtual midpoint voltage V N The first preset number of virtual midpoint voltages before the current virtual midpoint voltage V N Make adjustments; Among them, V U is the phase voltage of phase U, V V is the phase voltage of phase V, V W is the phase voltage of phase W, n is the first preset number, i is the sequence number of the first preset number of virtual midpoint voltages, V i is the i-th virtual midpoint voltage among the first preset number of virtual midpoint voltages; The step of determining the target point according to the voltage variable of the suspended phase, the virtual midpoint voltage, the phase voltage of the suspended phase, and the hysteresis threshold comprises: Determine whether the phase voltage of the suspended phase is equal to the sum of the virtual midpoint voltage and the hysteresis threshold. If so, determine whether the voltage variable of the suspended phase is within a first preset range. If so, determine the electrical angle corresponding to the phase voltage of the suspended phase that is equal to the sum of the virtual midpoint voltage and the hysteresis threshold as the target point. If the voltage variable of the suspended phase is not within the first preset range, determining whether the voltage variable of the suspended phase is within the second preset range; if so, determining the electrical angle corresponding to the phase voltage of the suspended phase that is equal to the sum of the virtual midpoint voltage and the hysteresis threshold as the target point; if not, no operation is performed; If the phase voltage of the floating phase is not equal to the sum of the virtual neutral voltage and the hysteresis threshold, no action is performed.

2. The zero-crossing detection method for a brushless DC motor according to claim 1, wherein: According to the current virtual midpoint voltage V N The first preset number of virtual midpoint voltages before the current virtual midpoint voltage V N Make adjustments, including: Depend on Determine the current virtual midpoint voltage V N The change rate corresponding to the previous virtual midpoint voltage; The acceleration model is obtained by linear fitting according to the change rate corresponding to the virtual midpoint voltage, and the value of k in the acceleration model is obtained by fitting the parameters using the least square method; according to Determine the current virtual midpoint voltage V N The estimated value of V x ; according to The current virtual midpoint voltage V N Make adjustments; Wherein, n is the first preset number, i is the sequence number of the first preset number of virtual midpoint voltages, V i is the i-th virtual midpoint voltage in the first preset number of virtual midpoint voltages, t is the preset time, V n is the nth virtual midpoint voltage among the first preset number of virtual midpoint voltages, V n-1 is the n-1th virtual midpoint voltage among the first preset number of virtual midpoint voltages, a n V n is a change rate corresponding to the nth virtual mid-point voltage among the first preset number of virtual mid-point voltages.

3. The zero-crossing detection method for a brushless DC motor according to claim 1, wherein: Determining the voltage variable of the suspended phase according to the voltage of the suspended phase includes: Get the latest phase voltage u1 of the suspended phase and the previous phase voltage u2 of the latest phase voltage; Depend on Get the voltage variable of the suspended phase.

4. The zero-crossing detection method for a brushless DC motor according to claim 1, wherein: Determining the hysteresis threshold according to the preset value includes: Determine whether a preset value exists. If not, measure the noise peak-to-peak value u3 using an oscilloscope. Depend on Obtaining a preset value and setting the preset value as a hysteresis threshold; If there is a preset value, the preset value is set as the hysteresis threshold; Where a is the preset coefficient.

5. The zero-crossing detection method for a brushless DC motor according to claim 1, wherein: Determining a zero-crossing point from the determined target point according to the commutation delay time includes: Determine whether there is a commutation delay time, and if so, obtain a second preset number of commutation delay times; Depend on Estimate the next commutation delay time T x ; according to Get the estimated electrical angle at the commutation moment; The target point closest to the estimated electrical angle is determined as the zero-crossing point; If there is no commutation delay time, the middle value between the first target point and the last target point is determined as the zero crossing point; Wherein, m is the value of the second preset number, T m is the mth commutation delay time, T y is the moment corresponding to the last zero crossing point, and P is the number of pole pairs of the brushless DC motor.

6. The zero-crossing detection method for a brushless DC motor according to claim 1, wherein: The updating of the preset value according to the number of target points includes: S801, determine whether the number of target points is greater than a third preset number, if so, according to Update the preset value; S802: If the number of target points is less than or equal to the third preset number, determine whether the number of target points is less than the fourth preset number. If so, Update the preset value, if not, do not update the preset value; S803, setting the preset value of the completed update as the hysteresis threshold; S804, determining a target point based on the voltage variable of the suspended phase, the virtual midpoint voltage, the phase voltage of the suspended phase, and the hysteresis threshold; S805, determining whether the number of target points is between the third preset number and the fourth preset number; if not, re-execute S801-S804 until the number of target points is between the third preset number and the fourth preset number; Wherein, c is the preset value before updating.

7. A zero-crossing detection device for a brushless DC motor, characterized in that: The zero-crossing detection device for the brushless DC motor comprises: A voltage acquisition module is used to obtain the three-phase voltages at preset intervals; A midpoint determination module is used to determine a virtual midpoint voltage according to the three-phase phase voltages and adjust the virtual midpoint voltage according to historical data of the virtual midpoint voltage; A rate determination module is used to determine the suspended phase according to the currents of the three phases, and to determine the voltage variable of the suspended phase according to the voltage of the suspended phase; A threshold determination module, configured to determine a hysteresis threshold according to a preset value; A target point determination module is used to determine the target point according to the voltage variable of the suspended phase, the virtual midpoint voltage, the phase voltage of the suspended phase and the hysteresis threshold; A zero-crossing point determination module is used to determine a zero-crossing point in the determined target point according to the commutation delay time; The preset value updating module is used to update the preset value according to the number of target points; Determining the virtual midpoint voltage according to the three-phase phase voltages and adjusting the virtual midpoint voltage according to historical data of the virtual midpoint voltage includes: Depend on Determine the current virtual midpoint voltage V N ; Get the current virtual midpoint voltage V N a first preset number of previous virtual midpoint voltages; Depend on Get the deviation value; Determine whether the deviation value is within the preset range. If so, The current virtual midpoint voltage V N Adjust, if not, according to the current virtual midpoint voltage V N The first preset number of virtual midpoint voltages before the current virtual midpoint voltage V N Make adjustments; Among them, V U is the phase voltage of phase U, V V is the phase voltage of phase V, V W is the phase voltage of phase W, n is the first preset number, i is the sequence number of the first preset number of virtual midpoint voltages, V i is the i-th virtual midpoint voltage among the first preset number of virtual midpoint voltages; The step of determining the target point according to the voltage variable of the suspended phase, the virtual midpoint voltage, the phase voltage of the suspended phase, and the hysteresis threshold comprises: Determine whether the phase voltage of the suspended phase is equal to the sum of the virtual midpoint voltage and the hysteresis threshold. If so, determine whether the voltage variable of the suspended phase is within a first preset range. If so, determine the electrical angle corresponding to the phase voltage of the suspended phase that is equal to the sum of the virtual midpoint voltage and the hysteresis threshold as the target point. If the voltage variable of the suspended phase is not within the first preset range, determining whether the voltage variable of the suspended phase is within the second preset range; if so, determining the electrical angle corresponding to the phase voltage of the suspended phase that is equal to the sum of the virtual midpoint voltage and the hysteresis threshold as the target point; if not, no operation is performed; If the phase voltage of the floating phase is not equal to the sum of the virtual neutral voltage and the hysteresis threshold, no action is performed.

8. A brushless DC motor, characterized in that: The brushless DC motor includes a motor device and a control module for controlling the motor device; The motor device is used to realize the rotation function to realize the function of a brushless DC motor; The control module is used to execute the steps of the zero-crossing detection method for a brushless DC motor according to any one of claims 1 to 6.

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