Position sensorless single-phase brushless DC motor driving method and motor controller

Abstract

The present invention discloses a sensorless single-phase brushless DC motor drive method and motor controller. The drive method comprises: obtaining a first back-electromotive force (BEM) value based on all current values ​​within a preset sampling moment and a voltage reference value; obtaining a rotor position angle and rotor speed at the current sampling moment based on the first BEM value; generating a control signal based on a preset voltage duty cycle and rotor position angle, and sending the control signal to a motor driver to achieve drive control of the single-phase motor. The present invention first estimates the motor back-electromotive force value using the voltage reference value and the motor phase current to determine the current rotor position. Finally, combining the preset voltage duty cycle and rotor position, the control signal is generated to drive the motor, providing a sensorless single-phase motor drive system solution based on an estimator.

Description

Technical Field

[0001] The present invention relates to the technical field of single-phase brushless DC motors, and in particular to a position sensorless single-phase brushless DC motor driving method and a motor controller. Background Art

[0002] Due to their low cost, single-phase brushless DC motors are widely used in applications such as low-power fans and water pumps. Single-phase motors typically require a Hall effect sensor to sense the motor's rotor position. The controller then outputs the appropriate phase voltage based on this rotor position information for efficient motor control.

[0003] In the existing technology, the position sensorless driving method of a single-phase motor generally suspends the phase winding when the motor is in continuous flow during operation. By comparing the magnitudes of the two opposite back electromotive forces on the inverter, the zero-crossing point of the back electromotive force is determined, and then the rotor position is identified. However, this method relies on the voltage change of the suspended phase, and the generation of the suspended phase requires rapid continuous current; therefore, it is difficult to apply to control areas with high duty cycles. Summary of the Invention

[0004] The main purpose of the present invention is to provide a position sensorless single-phase brushless DC motor driving method and motor controller based on an estimator, aiming to solve the problem of position sensorless single-phase motor driving under high duty cycle.

[0005] To achieve the above objectives, the present invention proposes a method for driving a position sensorless single-phase brushless DC motor, which comprises:

[0006] Receiving a current value obtained by sampling a motor phase current, receiving a voltage reference value at a previous sampling moment, and obtaining a first back electromotive force value according to all current values ​​within a preset sampling moment and the voltage reference value;

[0007] Obtaining the rotor position angle and rotor speed at the current sampling moment according to the first back electromotive force value;

[0008] According to the preset voltage duty cycle and the rotor position angle, a voltage reference value and a control signal at the current sampling moment are generated, and the control signal is sent to the motor driver to realize the drive control of the single-phase motor.

[0009] Optionally, obtaining the first back electromotive force value according to all current values ​​within a preset sampling moment and the voltage reference value includes:

[0010] Inputting all current values ​​within a preset sampling moment and the voltage reference value into a preset back electromotive force estimation formula;

[0011] The first back electromotive force value is calculated using the preset back electromotive force estimation formula.

[0012] Optionally, the preset back electromotive force estimation formula is:

[0013]

[0014] Among them, e(t) is the first back electromotive force value at time t, is the estimation window corresponding to the preset sampling time, α is a preset parameter, i(t) is the current value at time t, and u(t) is the voltage reference value at time t.

[0015] Optionally, obtaining the rotor position angle and rotor speed at a current sampling moment according to the first back electromotive force value includes:

[0016] performing low-pass filtering on the first back electromotive force value to obtain a second back electromotive force value, and performing full-pass filtering on the second back electromotive force value to obtain a third back electromotive force value;

[0017] The second back electromotive force value and the third back electromotive force value are input into a phase-locked loop module to obtain a rotor position angle and a rotor speed.

[0018] Optionally, performing low-pass filtering on the first back electromotive force value to obtain a second back electromotive force value, and performing full-pass filtering on the second back electromotive force value to obtain a third back electromotive force value, further includes:

[0019] Get the rotor speed at the last sampling moment;

[0020] The cutoff frequency of the low-pass filter and the center frequency of the all-pass filter are determined according to the rotor speed at the last sampling moment.

[0021] Optionally, generating a voltage reference value and a control signal at a current sampling moment according to a preset voltage duty cycle and the rotor position angle includes:

[0022] Determining the voltage sector of the motor at the current moment according to the rotor position angle, the preset first switching angle, the preset second switching angle, the preset third switching angle, and the preset fourth switching angle;

[0023] The voltage reference value and control signal at the current moment are generated according to the preset voltage duty cycle, the voltage sector of the motor at the current moment, and the voltage sector of the motor at the previous moment.

[0024] Optionally, the position sensorless single-phase brushless DC motor driving method further includes:

[0025] The preset first switching angle, the second switching angle, the preset third switching angle and the preset fourth switching angle are determined according to the preset first freewheeling angle and the preset first commutation angle.

[0026] Optionally, generating a voltage reference value and a control signal at a current moment according to a preset voltage duty cycle, a voltage sector of the motor at a current moment, and a voltage sector of the motor at a previous moment includes:

[0027] If the voltage sector of the motor at the current moment is the same as the voltage sector of the motor at the previous moment, the voltage reference value and the control signal at the current moment are generated according to the voltage sector of the motor at the current moment and the preset voltage duty cycle;

[0028] If the voltage sector of the motor at the current moment is different from the voltage sector of the motor at the previous moment, the voltage reference value and control signal at the current moment are generated according to the voltage sector of the motor at the current moment, the voltage sector of the motor at the previous moment, the preset voltage duty cycle, the rotor position angle at the previous moment and the rotor position angle at the current moment.

[0029] Optionally, generating a voltage reference value and a control signal at a current sampling moment according to a preset voltage duty cycle and the rotor position angle includes:

[0030] generating a sinusoidal voltage duty cycle according to the rotor position angle and a preset voltage duty cycle;

[0031] A control signal and a voltage reference value are generated according to the duty cycle of the sinusoidal voltage.

[0032] The present invention also proposes a motor controller, which is connected to a motor driver. The motor controller includes: a memory, a processor, and a motor driver program stored in the memory and runnable on the processor. The motor driver program is configured to implement the steps of the position sensorless single-phase brushless DC motor driving method.

[0033] The present invention discloses a method for driving a single-phase brushless DC motor without a position sensor and a motor controller. The method comprises: receiving a current value obtained by sampling a motor phase current, receiving a voltage reference value at a previous sampling moment, and obtaining a first back electromotive force value based on all current values ​​within a preset sampling moment and the voltage reference value; obtaining a rotor position angle and rotor speed at the current sampling moment based on the first back electromotive force value; generating a voltage reference value and a control signal at the current sampling moment based on a preset voltage duty cycle and the rotor position angle, and sending the control signal to a motor driver to achieve drive control of the single-phase motor. The method first obtains the back electromotive force value using the voltage reference value and the collected motor phase current, then low-pass filters and full-pass filters the back electromotive force value to obtain two orthogonal sinusoidal signals, which are then input into a phase-locked loop module to obtain the rotor position at the current moment. Finally, combined with the preset voltage duty cycle, a control signal is generated to achieve drive control of the motor, avoiding leaving the motor phase suspended and solving the problem of driving a single-phase motor without a position sensor at a high duty cycle. Furthermore, the proposed sensorless single-phase brushless DC motor drive method enables full-voltage duty cycle sensorless control. A robust back-EMF observer is developed that is insensitive to motor inductance and does not require permanent magnet flux parameters. An all-pass filter generates a real-time back-EMF signal delayed by 90°. Compared to array-based recording methods, this method offers improved dynamic response and enhances the drive system's rapidity. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0035] Figure 1 A schematic diagram of the steps of an embodiment of a method for driving a position sensorless single-phase brushless DC motor according to the present invention;

[0036] Figure 2 A schematic diagram of the steps of another embodiment of the method for driving a position sensorless single-phase brushless DC motor according to the present invention;

[0037] Figure 3 This is a first control block diagram of a motor control system according to an embodiment of a method for driving a position sensorless single-phase brushless DC motor of the present invention;

[0038] Figure 4The waveform diagram of the inverter first phase voltage, the inverter second phase voltage and the rotor position angle within one electrical cycle of the position sensorless single-phase brushless DC motor driving method of the present invention;

[0039] Figure 5 A schematic diagram of the steps of another embodiment of the method for driving a position sensorless single-phase brushless DC motor according to the present invention;

[0040] Figure 6 This is a second control block diagram of the motor control system of an embodiment of the position sensorless single-phase brushless DC motor driving method of the present invention;

[0041] Figure 7 This is a first principle diagram of a phase-locked loop according to an embodiment of a position sensorless single-phase brushless DC motor driving method of the present invention.

[0042] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0043] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0044] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0045] In the present invention, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can mean fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will be able to understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0046] In addition, in the present invention, descriptions such as "first" and "second" are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0047] Due to their low cost, single-phase brushless DC motors are widely used in applications such as low-power fans and water pumps. Single-phase motors typically require a Hall effect sensor to sense the motor's rotor position. The controller then outputs the appropriate phase voltage based on this rotor position information for efficient motor control.

[0048] The present invention proposes a method for driving a sensorless single-phase brushless DC motor, aiming to solve the problem of driving a sensorless single-phase motor under high duty cycle.

[0049] The method for driving a position sensorless single-phase brushless DC motor comprises:

[0050] Step S10: receiving a current value obtained by sampling the motor phase current, receiving a voltage reference value at a previous sampling moment, and obtaining a first back electromotive force value based on all current values ​​within a preset sampling moment and the voltage reference value;

[0051] Step S20: Obtain the rotor position angle and rotor speed at the current sampling moment according to the first back electromotive force value;

[0052] Step S30: Generate a voltage reference value and a control signal at the current sampling moment according to the preset voltage duty cycle and the rotor position angle, and send the control signal to the motor driver to realize drive control of the single-phase motor.

[0053] It's important to note that back electromotive force (BEMF) refers to the voltage induced in the stator windings of a motor due to rotor rotation during operation. Specifically, BEMF is the voltage signal generated when the stator cuts through the rotor's magnetic field during motor operation. By estimating BEMF, the actual rotor position and speed can be calculated, enabling precise motor control.

[0054] The voltage equation of a brushless DC motor can be expressed as:

[0055] ,

[0056] Where u is the phase voltage, R is the resistance of the motor winding, i is the phase current, e is the back electromotive force, and L is the motor inductance.

[0057] It should be noted that the present invention implements the sampling of phase current through a current sampling module. Therefore, the current value obtained by sampling the motor phase current at the current sampling moment can be obtained through the current sampling module. It is easy to understand that the position sensorless single-phase brushless DC motor driving method of the present invention is applied to the motor controller, the phase current of the motor is an analog quantity, and the interval time between two adjacent sampling moments is affected by the operating frequency of the analog-to-digital converter in the motor controller or the current sampling module. Specifically, the operating frequency of the processor in the analog-to-digital converter affects the interval time. Considering that the level of the processor's operating frequency is generally greater than the kHz level, that is, the time interval is less than 1ms.

[0058] The operating state of a motor changes dynamically. Back EMF is the voltage generated by the motor during rotation and is closely related to the motor's speed and rotor position. Unlike multi-phase motors, single-phase motors only have one back EMF signal. Therefore, how to generate stable angle and speed signals from this back EMF signal becomes a difficult problem that needs to be solved. It should be noted that in position sensorless control methods, using the voltage reference value at the previous sampling moment can simplify the control algorithm, reduce reliance on real-time calculations, and reduce the computational burden. In addition, during the motor control process, current and voltage signals may be affected by noise. Using the voltage reference value at the previous sampling moment helps to obtain more stable results. In addition, the phase current value at the current sampling moment is the result of the phase voltage in the previous cycle, so using the voltage reference value at the previous sampling moment is reasonable. It should be noted that the preset sampling moment can be the current sampling moment, and the previous sampling moment is specifically the sampling moment before the preset sampling moment.

[0059] Obtaining a first back electromotive force value according to all current values ​​within a preset sampling moment and the voltage reference value includes:

[0060] Inputting all current values ​​within a preset sampling moment and the voltage reference value into a preset back electromotive force estimation formula;

[0061] The first back electromotive force value is calculated using the preset back electromotive force estimation formula.

[0062] The preset back electromotive force estimation formula is:

[0063]

[0064] Among them, e(t) is the first back electromotive force value at time t, is the estimated window length corresponding to the preset sampling time, =nT, usually the value of n can be selected from 3 to 50, T is the interval between adjacent sampling moments. α is a preset parameter, i(t) is the current value at time t, and u(t) is the voltage reference value at time t. and in <0, yes , .

[0065] It should be noted that the preset sampling moments are the first n sampling moments including the current sampling moment, and the value of n can usually be selected to be 3~50. α is a coefficient that makes u(t) and di(t) / dt at the same order of magnitude, which is determined by the designer. The above formula is a calculation formula for the continuous domain. The present invention does not give a specific calculation formula in the digital system. In practical applications, a variety of numerical methods can be used for discretization and the solution can be obtained based on the current value and voltage reference value within the preset sampling moment. There is no restriction here. It is worth noting that the current value and voltage reference value at a single moment may be affected by instantaneous fluctuations. The above calculation formula uses the result of integrating multiple current values ​​and voltage reference values, so it can greatly reduce the influence of white noise in the signal on the estimation result, and improve the estimation accuracy and anti-interference ability.

[0066] It's important to note that the voltage drop across the resistor is small when the motor is running, and the current is generally in phase with the back EMF. Therefore, the above equation ignores the effect of the voltage drop across the resistor. In practice, if the designer wishes to include the voltage drop across the resistor in the equation, simply replace u(t) with u(t)-Ri(t).

[0067] After obtaining the first back electromotive force value, the rotor position angle and the rotor speed at the current sampling moment are obtained according to the first back electromotive force value.

[0068] Back EMF is closely related to the rotor's speed and position. In sensorless control methods, back EMF is used as crucial information for inferring rotor position. Based on the known first back EMF value, the controller processes it to extract two stable, orthogonal sinusoidal signals. These processed signals more accurately reflect the current rotor position and speed.

[0069] Obtaining the rotor position angle and rotor speed at the current sampling moment according to the first back electromotive force value includes:

[0070] Step S210: low-pass filtering the first back electromotive force value to obtain a second back electromotive force value, and full-pass filtering the second back electromotive force value to obtain a third back electromotive force value;

[0071] Step S220: Input the second back electromotive force value and the third back electromotive force value into a phase-locked loop module to obtain a rotor position angle and a rotor speed.

[0072] It should be noted that in motor control, the back electromotive force signal may contain high-frequency noise (such as electrical interference, switching noise, etc.), which will have a negative impact on the subsequent control algorithm. In order to improve the signal based on a more real and stable signal, the first back electromotive force value is first low-pass filtered to filter out the high-frequency component and obtain the second back electromotive force. Since the phase-locked loop that tracks one sinusoidal wave signal is not as effective as the phase-locked loop that tracks two orthogonal sinusoidal signals, the present invention performs full-pass filtering on the second back electromotive force, and uses the characteristic of changing the phase of the signal without changing its amplitude to adjust the phase of the second back electromotive force signal to obtain a real-time signal that is delayed by 90° from the second back electromotive force, thereby improving the control accuracy. Compared with the recording array method, the dynamic response is high, which enhances the rapidity of the drive system.

[0073] Figure 7 A schematic diagram of a phase-locked loop module is provided. represents the second back EMF, represents the third back EMF, θ r is the rotor angle reference value, is the estimated value of the rotor angle, K p is the proportional operation coefficient, K i is the integral operation coefficient. It is easy to get that ω r ψ f [cos( θ r )sin( )-sin( θ r )cos( )]=ω r ψ f sin( - θ r ), when sin( - θ r ) is a smaller number, sin( - θ r )= - θ r =Δ θ r Therefore, the input signal of this module contains the rotor position difference information. Designers can adjust K p With K iThe response speed of the phase-locked loop can be adjusted. As a common method for tracking phase in control systems, the phase-locked loop has a large amount of information on its control framework, design process, and parameter selection, so I will not elaborate on it here.

[0074] It should be noted that the speed of the motor may change during operation, which will affect the back electromotive force signal characteristics of the motor. In order to ensure that high-frequency noise can be effectively suppressed at different speeds while retaining useful signal components, the rotor position angle at the current sampling moment is obtained according to the first back electromotive force value, and further includes:

[0075] Get the rotor speed at the last sampling moment;

[0076] The cutoff frequency of the low-pass filter and the center frequency of the all-pass filter are determined according to the rotor speed at the last sampling moment.

[0077] It's easy to understand that changes in rotor speed cause the frequency components of the back-EMF signal to vary. If the filter's cutoff frequency is fixed, important signals may be filtered out or noise may not be effectively suppressed. Dynamically adjusting the cutoff frequency improves signal processing accuracy, ensuring accurate extraction of motor status information under varying operating conditions. By adjusting the filter's cutoff frequency based on rotor speed, high-frequency noise can be effectively suppressed while retaining useful signal components at varying speeds. The signal delay phase of an all-pass filter is closely related to its center frequency. Therefore, only when the rotor speed is accurate can the generation of a third back-EMF signal, which is delayed by 90° from the second, be guaranteed.

[0078] Step S30: Generate a voltage reference value and a control signal at the current sampling moment according to the preset voltage duty cycle and the rotor position angle, and send the control signal to the motor driver to realize drive control of the single-phase motor.

[0079] It should be noted that the preset voltage duty cycle refers to the parameter that characterizes the length of time that the voltage signal remains at a high level within an electrical cycle. The preset voltage duty cycle is used to control the motor's output power and speed and is typically set by the system designer based on the motor's characteristics and application requirements. In actual applications, the preset voltage duty cycle is directly derived from an external command duty cycle or generated from an external command speed via a speed loop. The rotor position angle represents the angular position of the motor rotor at the current moment.

[0080] It is worth noting that the present invention provides two PWM drive modes. The first is a square wave mode, in which the inverter applies a voltage corresponding to a preset voltage duty cycle to the first or second phase in different sectors. During the sector switching cycle, the voltage duty cycle corresponding to the preset voltage duty cycle and the rotor position angle is calculated and applied, thus achieving a single-phase brushless DC motor drive with constant frequency square wave control. The second is a sinusoidal wave mode, in which the controller calculates a real-time sinusoidal voltage duty cycle based on the rotor position angle and the preset voltage duty cycle, and applies a corresponding voltage to the first or second phase of the inverter according to the sinusoidal voltage duty cycle.

[0081] The present invention discloses a position sensorless single-phase brushless DC motor driving method and a motor controller, wherein the position sensorless single-phase brushless DC motor driving method includes: receiving a current value obtained by sampling the motor phase current, receiving a voltage reference value at a previous sampling moment, and obtaining a first back electromotive force value based on all current values ​​within a preset sampling moment and the voltage reference value; obtaining a rotor position angle and a rotor speed at the current sampling moment based on the first back electromotive force value; generating a voltage reference value and a control signal at the current sampling moment based on a preset voltage duty cycle and the rotor position angle, and sending the control signal to a motor driver to realize drive control of the single-phase motor. The present invention first obtains the back-electromotive force (BEMF) value using the voltage reference value and the collected motor phase current. The BEMF value is then low-pass filtered and full-pass filtered to obtain two orthogonal sinusoidal signals. These signals are then input into a phase-locked loop (PLL) module to obtain the rotor position at the current moment. Finally, a control signal is generated based on a preset voltage duty cycle to achieve drive control of the motor. This avoids leaving the motor phase suspended, solves the problem of driving a single-phase motor without a position sensor at a high duty cycle, and uses a motor model to construct an estimator, enabling high-performance control of a single-phase motor without a position sensor. Furthermore, the present invention proposes a method for driving a single-phase brushless DC motor without a position sensor, enabling full voltage duty cycle sensorless control. A robust BEMF observer is established, which is insensitive to motor inductance and does not require permanent magnet flux parameters. Through the full-pass filter, a real-time signal with a 90° delay in the BEMF signal is obtained. Compared to the array recording method, this method has a high dynamic response and enhances the speed of the drive system.

[0082] refer to Figure 3 In order to facilitate the understanding of the present invention, an application example is proposed. Figure 3This is a control block diagram of a motor control system. The motor control system includes a motor, inverter, driver, current sampling module, and controller. The inverter is connected to a DC voltage source, which powers the entire system. The current sampling module collects the motor phase current and inputs it into the controller. The controller generates control logic based on the motor phase current and voltage, and sends this logic to the driver. The driver then drives the power devices to control the voltages of the inverter's first and second phases, ultimately achieving motor control.

[0083] The step of generating a voltage reference value and a control signal at a current sampling moment according to a preset voltage duty cycle and the rotor position angle includes:

[0084] Step S310: determining the voltage sector of the motor at the current moment according to the rotor position angle, the preset first switching angle, the preset second switching angle, the preset third switching angle, and the preset fourth switching angle;

[0085] Step S320 : Generate a voltage reference value and a control signal at the current moment according to a preset voltage duty cycle, the voltage sector of the motor at the current moment, and the voltage sector of the motor at the previous moment.

[0086] It's easy to understand that square-wave control of a single-phase motor involves multiple sectors, with different voltage sectors corresponding to different voltage application strategies. By selecting the appropriate drive strategy based on the rotor's voltage sector, the motor's energy loss can be effectively reduced. The present invention divides the entire electrical cycle into first, second, third, and fourth voltage sectors by presetting first, second, third, and fourth switching angles, corresponding to different motor operating phases, respectively.

[0087] Optionally, the division method of the voltage sectors and the angle regions corresponding to the voltage sectors will affect the motor control strategy. The position sensorless single-phase brushless DC motor driving method further includes:

[0088] Calculate a preset first switching angle, a second switching angle, a preset third switching angle, and a preset fourth switching angle according to the preset first freewheeling angle and the preset first commutation angle;

[0089] It should be noted that the freewheeling angle is the angle at which the current flows from the ground line after the motor completes driving one phase, pulling the lower bridges of both phases low. Setting the freewheeling angle ensures that the motor current is kept low when the next phase is driven, preventing energy in the motor's equivalent inductance from flowing into the bus and causing bus voltage overshoot. The commutation angle is the angle at which the motor switches between phases. The commutation angle determines the relative position of the motor current and back EMF during motor rotation, thereby achieving more efficient drive.

[0090] Specifically, the numerical relationships between the switching angles are as follows: the preset first switching angle is equal to the preset first commutation angle, the preset second switching angle is equal to 180 degrees plus the preset first commutation angle minus the preset first freewheeling angle, the preset third switching angle is equal to 180 degrees plus the preset first commutation angle, and the preset fourth switching angle is equal to 360 degrees plus the preset first commutation angle minus the preset first freewheeling angle.

[0091] It's easy to understand that this setting generates symmetrical voltage sectors, applying voltage to the inverter's first and second phases separately, with the same freewheeling time inserted between them. Adjusting the preset first commutation angle adjusts the relative position of the current and the motor's back EMF. Adjusting the preset first freewheeling angle also adjusts the motor's freewheeling time. It's worth noting that when the preset first commutation angle is set to a positive number, all sectors are shifted backward by a certain angle relative to the rotor position angle; when the preset first commutation angle is set to a negative number, all sectors are shifted forward by a certain angle relative to the rotor position angle. The preset first freewheeling angle and the preset first commutation angle are determined by the developer. The preset first freewheeling angle adjusts the length of the controller's freewheeling time. This value is typically increased at high speeds, and the user can set the specific value based on the application. The preset first commutation angle determines the commutation angle. This parameter can be adjusted by the user based on the current waveform or automatically adjusted by the controller.

[0092] The voltage sector of the motor at the current moment is determined based on the rotor position angle, the preset first switching angle, the preset second switching angle, the preset third switching angle and the preset fourth switching angle. Specifically, if the rotor position angle is greater than the preset first switching angle and less than the preset second switching angle, it is in the first voltage sector; if the rotor position angle is greater than the preset second switching angle and less than the preset third switching angle, it is in the second voltage sector; if the rotor position angle is greater than the preset third switching angle and less than the preset fourth switching angle, it is in the third voltage sector; if the rotor position angle is greater than the preset fourth switching angle and less than the preset first switching angle, it is in the fourth voltage sector.

[0093] It's easy to understand that due to the periodic step nature of angles, the greater than and less than relationships mentioned above are not absolute. For example, 350° is less than 360°, and 360° equals 0°, so 350° is less than 0°. This means that when determining the size of an angle, we need to consider its position within the overall angle range. We determine the relative lead and lag of the angle, rather than directly comparing its absolute size.

[0094] The voltage sector of the motor at the current moment is determined based on the rotor position angle, the preset first switching angle, the preset second switching angle, the preset third switching angle, and the preset fourth switching angle; and the voltage sector of the motor rotor is determined specifically based on a comparison between the rotor position angle and the preset first switching angle, the preset second switching angle, the preset third switching angle, and the preset fourth switching angle. It should be noted that the specific values ​​of the preset first switching angle, the preset second switching angle, the preset third switching angle, and the preset fourth switching angle can be independently set by R&D personnel, or can be determined based on the numerical relationship between the aforementioned switching angles.

[0095] The method generates a voltage reference value and a control signal at the current moment based on a preset voltage duty cycle, the voltage sector in which the motor is located at the current moment, and the voltage sector in which the motor was located at the previous moment, including: if the motor is in the first voltage sector at the current moment, a preset voltage duty cycle is applied to the first phase of the inverter, the lower bridge of the second phase of the inverter is turned on, and the voltage reference value is the preset voltage duty cycle multiplied by the bus voltage; if the motor is in the second voltage sector at the current moment, the lower bridge of the first phase of the inverter and the lower bridge of the second phase of the inverter are turned on, and the voltage reference value is zero; if the motor is in the third voltage sector at the current moment, a preset voltage duty cycle is applied to the second phase of the inverter, the lower bridge of the first phase of the inverter is turned on, and the voltage reference value is the preset voltage duty cycle multiplied by the negative of the bus voltage; if the motor is in the fourth voltage sector at the current moment, the lower bridge of the first phase of the inverter and the lower bridge of the second phase of the inverter are turned on, and the voltage reference value is zero.

[0096] It's easy to understand that square-wave control of a single-phase motor operates in multiple sectors, with different voltage sectors corresponding to different voltage application strategies. By selecting the appropriate drive strategy based on the rotor's voltage sector, motor energy loss can be effectively reduced. Different voltage sectors have varying current and voltage requirements during motor operation. A well-defined motor control strategy tailored to each voltage sector ensures optimal motor operation, improving overall energy efficiency.

[0097] In each voltage sector, the motor's drive method and voltage reference value vary. By matching the rotor position angle with the preset voltage sector, the voltage applied to the motor and the corresponding control strategy can be determined at that position. Combined with the preset voltage duty cycle, the voltage reference value and control signal for the current sampling moment are generated. Specifically, after determining the voltage duty cycle and voltage sector, the control system calculates the voltage reference value to be output at the current rotor position. The voltage reference value is obtained by multiplying the preset voltage duty cycle by the bus voltage. The control signal is an instruction to the motor driver, determining the actual operating state of the motor. It should be explained that this sensorless single-phase brushless DC motor drive method is applied to a motor controller. The motor controller is connected to the motor via a motor driver, which is in turn connected to the motor. The motor controller controls the motor driver by sending control signals to the motor driver to achieve drive control of the single-phase motor.

[0098] Optionally, to ensure smooth motor operation and control accuracy when the motor rotor switches between different voltage sectors, the present invention proposes a transition carrier voltage duty cycle. In single-phase motor control, changes in the rotor position angle may cause voltage sector switching. When switching between voltage sectors, the carrier's first portion corresponds to the previous voltage sector, while the second portion corresponds to the next. In this case, the transition carrier voltage duty cycle is introduced to combine the voltage vectors of the two voltage sectors into one through calculation, accurately outputting the desired voltage and achieving high-performance, stable control.

[0099] In one embodiment of the present invention, generating a voltage reference value and a control signal at a current sampling moment according to a preset voltage duty cycle and the rotor position angle includes:

[0100] Determining the voltage sector of the motor at the current moment according to the rotor position angle, the preset first switching angle, the preset second switching angle, the preset third switching angle, and the preset fourth switching angle;

[0101] The voltage reference value and control signal at the current moment are generated according to the preset voltage duty cycle, the voltage sector of the motor at the current moment, and the voltage sector of the motor at the previous moment.

[0102] Specifically, as the motor rotor rotates, the voltage sectors in which the rotor is located at the current moment and the previous moment may be the same or different.

[0103] If the voltage sector of the motor at the current moment is the same as the voltage sector of the motor at the previous moment, the voltage reference value and the control signal at the current moment are generated according to the voltage sector of the motor at the current moment and the preset voltage duty cycle;

[0104] If the voltage sector of the motor at the current moment is different from the voltage sector of the motor at the previous moment, the voltage reference value and control signal at the current moment are generated according to the voltage sector of the motor at the current moment, the voltage sector of the motor at the previous moment, the preset voltage duty cycle, the rotor position angle at the previous moment and the rotor position angle at the current moment.

[0105] It is particularly pointed out that at each sampling moment, it is determined whether the voltage sector in which the motor rotor is located is the same as the voltage sector in which the motor rotor was located at the previous moment, and then corresponding measures are taken according to different situations.

[0106] Reference Figure 4 , Figure 4 The first phase voltage U1 of the inverter, the second phase voltage U2 of the inverter and the rotor position angle in one electrical cycle θ 1 waveform. To preset the first switching angle, To preset the second switching angle, To preset the third switching angle, In the first sector, U1 is a voltage with a preset voltage duty cycle, in the third sector, U2 is a voltage with a preset voltage duty cycle, and in the second and fourth voltage sectors, U1 and U2 are both zero.

[0107] When switching from the first voltage sector to the second voltage sector, the voltage duty cycle of the transition carrier is calculated as follows:

[0108]

[0109] in, is the voltage duty cycle when the first voltage sector switches to the second voltage sector, is the preset voltage duty cycle, θ 1(k+1) like Figure 4 Where is the rotor position angle at the last sampling moment of the first voltage sector, θ 1(k+2) like Figure 4 Where is the rotor position angle at the first sampling moment of the second voltage sector.

[0110] When switching from the second voltage sector to the third voltage sector, the voltage duty cycle of the transition carrier is calculated by the following formula:

[0111]

[0112] in, is the voltage duty cycle when the second voltage sector switches to the third voltage sector, θ 1(k+4) like Figure 4Where is the rotor position angle at the last sampling moment of the second voltage sector, θ 1(k+5) like Figure 4 Where is the rotor position angle at the first sampling moment of the third voltage sector.

[0113] Similarly, the voltage duty cycle calculation formula of the transition carrier switching from the third voltage sector to the fourth voltage sector is similar to the voltage duty cycle calculation formula of the transition carrier switching from the first voltage sector to the second voltage sector; the voltage duty cycle calculation formula of the transition carrier switching from the fourth voltage sector to the first voltage sector is similar to the voltage duty cycle calculation formula of the transition carrier switching from the second voltage sector to the third voltage sector, so it will not be repeated here.

[0114] It is easy to understand that the voltage reference value and the control signal need to be matched according to the sectors crossed. For example, when the voltage sector switches from the first voltage sector to the second voltage sector, the duty is applied to the first phase of the inverter. 12 The voltage duty cycle is 100%, the second phase lower bridge of the inverter is turned on, and the voltage reference value is Duty 12 Multiply by the bus voltage; when the voltage sector switches from the second voltage sector to the third voltage sector, apply Duty to the second phase of the inverter 23 The voltage duty cycle is 100%, the first phase lower bridge of the inverter is turned on, and the voltage reference value is Duty 23 Multiply by the opposite number of the bus voltage. When the voltage sector is switched from the third voltage sector to the fourth voltage sector and when the voltage sector is switched from the fourth voltage sector to the first voltage sector, the situation is as follows: Figure 4 As shown, no further details are given here.

[0115] The above describes a method for generating a voltage reference value and a control signal in a square wave drive mode. In one embodiment of the present invention, the estimator in the controller of the present invention can also be used in a sinusoidal-wave driven, position-sensorless, single-phase DC brushless motor drive system. The method of generating a voltage reference value and a control signal at the current sampling moment based on a preset voltage duty cycle and the rotor position angle includes:

[0116] generating a sinusoidal voltage duty cycle according to the rotor position angle and a preset voltage duty cycle;

[0117] A control signal and a voltage reference value are generated according to the duty cycle of the sinusoidal voltage.

[0118] Specifically, the sinusoidal voltage duty cycle is calculated according to a sinusoidal voltage duty cycle generation formula;

[0119] The sinusoidal voltage duty cycle generation formula is:

[0120]

[0121] Among them, Dutysin(k) is the duty cycle of the sinusoidal voltage at time k, θ 1(k) is the rotor position angle at time k, and Δθ is the angular offset.

[0122] It's easy to understand that this equation generates a sinusoidal voltage duty cycle signal. By adjusting the preset voltage duty cycle, the amplitude of the sinusoidal signal can be adjusted, thereby adjusting the motor current. By adjusting the angle offset, the phase of the sinusoidal signal can be adjusted, thereby adjusting the phase relationship between the motor current and the motor's back EMF. The angle offset can be adjusted by the user based on the control waveform, or automatically by the program using a designed algorithm.

[0123] A control signal and a voltage reference value are generated based on the voltage duty cycle, and the control signal is sent to the motor driver to control the drive of the single-phase motor. When the sinusoidal voltage duty cycle is positive, the corresponding voltage duty cycle is applied to the first phase of the inverter. When the sinusoidal voltage duty cycle is negative, the corresponding voltage duty cycle is applied to the second phase of the inverter. The voltage reference value is the product of the sinusoidal voltage duty cycle and the bus voltage.

[0124] It's easy to understand that the estimator provided by the present invention can also be used in single-phase motor drive systems driven by sinusoidal waves. While the maximum motor output power is lower when using sinusoidal wave control than when using square wave control, it offers certain advantages in terms of motor vibration and noise, and has therefore been adopted in a significant number of practical products. Furthermore, the estimator proposed by the present invention only requires the motor's current value and voltage reference value to estimate the motor's rotor position and speed. Therefore, it is not limited to the two voltage drive modes mentioned above but can be applied to any drive mode that can perform current sampling.

[0125] Reference Figure 6 , Figure 6 The motor control system topology shown only places sampling resistors on the busbar branches, making it impossible to sample current during freewheeling. The aforementioned sensorless single-phase brushless DC motor control technology can also be applied to this topology. When using square wave control, since phase current cannot be sampled during freewheeling, the preset freewheeling angle should be set to zero or a very small value. This approximates that the motor phase current does not change during the freewheeling time. When using sinusoidal wave control, since the motor drive signal is a sinusoidal voltage signal, phase current flows through the sampling resistors on the busbar branches during every carrier cycle. Therefore, sampling issues do not arise and the system can be used directly.

[0126] The present invention also proposes a motor controller, which is connected to a motor driver. The motor controller includes: a memory, a processor, and a motor driver program stored in the memory and runnable on the processor. The motor driver program is configured to implement the steps of the position sensorless single-phase brushless DC motor driving method.

[0127] The specific steps of the position sensorless single-phase brushless DC motor driving method refer to the above embodiments. Since the motor controller adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here.

[0128] The above descriptions are merely optional embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present description and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for driving a position sensorless single-phase brushless DC motor, characterized in that: The method for driving a position sensorless single-phase brushless DC motor comprises: Receiving a current value obtained by sampling a motor phase current, receiving a voltage reference value at a previous sampling moment, and obtaining a first back electromotive force value according to all current values ​​within a preset sampling moment and the voltage reference value; Obtaining the rotor position angle and rotor speed at the current sampling moment according to the first back electromotive force value; Generate a voltage reference value and a control signal at the current sampling moment according to a preset voltage duty cycle and the rotor position angle, and send the control signal to the motor driver to realize drive control of the single-phase motor; Obtaining a first back electromotive force value according to all current values ​​within a preset sampling moment and the voltage reference value includes: Inputting all current values ​​within a preset sampling moment and the voltage reference value into a preset back electromotive force estimation formula; Calculating a first back electromotive force value using the preset back electromotive force estimation formula; The preset back electromotive force estimation formula is: Among them, e(t) is the first back electromotive force value at time t, is the estimation window corresponding to the preset sampling time, α is a preset parameter, i(t) is the current value at time t, and u(t) is the voltage reference value at time t.

2. The method for driving a position sensorless single-phase brushless DC motor according to claim 1, wherein: Obtaining the rotor position angle and the rotor speed at the current sampling moment according to the first back electromotive force value includes: performing low-pass filtering on the first back electromotive force value to obtain a second back electromotive force value, and performing full-pass filtering on the second back electromotive force value to obtain a third back electromotive force value; The second back electromotive force value and the third back electromotive force value are input into a phase-locked loop module to obtain a rotor position angle and a rotor speed.

3. The method for driving a position sensorless single-phase brushless DC motor according to claim 2, wherein: The method of low-pass filtering the first back electromotive force value to obtain a second back electromotive force value, and full-pass filtering the second back electromotive force value to obtain a third back electromotive force value, further includes: Get the rotor speed at the last sampling moment; The cutoff frequency of the low-pass filter and the center frequency of the all-pass filter are determined according to the rotor speed at the last sampling moment.

4. The method for driving a position sensorless single-phase brushless DC motor as claimed in claim 1, wherein: The step of generating a voltage reference value and a control signal at a current sampling moment according to a preset voltage duty cycle and the rotor position angle includes: Determining the voltage sector of the motor at the current moment according to the rotor position angle, the preset first switching angle, the preset second switching angle, the preset third switching angle, and the preset fourth switching angle; The voltage reference value and control signal at the current moment are generated according to the preset voltage duty cycle, the voltage sector of the motor at the current moment, and the voltage sector of the motor at the previous moment.

5. The method for driving a position sensorless single-phase brushless DC motor according to claim 4, wherein: The position sensorless single-phase brushless DC motor driving method further includes: The preset first switching angle, the second switching angle, the preset third switching angle and the preset fourth switching angle are determined according to the preset first freewheeling angle and the preset first commutation angle.

6. The method for driving a position sensorless single-phase brushless DC motor as claimed in claim 4, wherein: The method of generating a voltage reference value and a control signal at a current moment according to a preset voltage duty cycle, a voltage sector of the motor at a current moment, and a voltage sector of the motor at a previous moment includes: If the voltage sector of the motor at the current moment is the same as the voltage sector of the motor at the previous moment, the voltage reference value and the control signal at the current moment are generated according to the voltage sector of the motor at the current moment and the preset voltage duty cycle; If the voltage sector of the motor at the current moment is different from the voltage sector of the motor at the previous moment, the voltage reference value and control signal at the current moment are generated according to the voltage sector of the motor at the current moment, the voltage sector of the motor at the previous moment, the preset voltage duty cycle, the rotor position angle at the previous moment and the rotor position angle at the current moment.

7. The method for driving a position sensorless single-phase brushless DC motor according to claim 1, wherein: The step of generating a voltage reference value and a control signal at a current sampling moment according to a preset voltage duty cycle and the rotor position angle includes: generating a sinusoidal voltage duty cycle according to the rotor position angle and a preset voltage duty cycle; A control signal and a voltage reference value are generated according to the duty cycle of the sinusoidal voltage.

8. A motor controller, characterized in that: The motor controller is connected to the motor driver, and the motor controller includes: a memory, a processor, and a motor driver program stored in the memory and executable on the processor, wherein the motor driver program is configured to implement the steps of the position sensorless single-phase brushless DC motor driving method according to any one of claims 1 to 7.

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