Starting control method of direct-current fan and related product

Abstract

The invention provides a starting control method of a direct-current fan and related products, and the starting control method comprises the steps: responding to a starting signal of the direct-current fan, and detecting an initial value of d-axis feedback current and an initial value of q-axis feedback current of a direct-current motor; d-axis target current and q-axis target current serve as control targets, and target control voltage of the direct current motor is calculated according to the initial values of the d-axis feedback current and the q-axis feedback current; obtaining an initial state of the direct current motor according to the target control voltage, wherein the initial state comprises an initial rotating speed, a rotor initial position and an initial rotating direction of the direct current motor; and determining a starting strategy of the direct-current fan according to the initial state, and controlling the direct-current fan to start according to the starting strategy. According to the technical scheme, the problems of high equipment cost and complex hardware structure of a direct current motor can be solved.

Description

Technical Field

[0001] This invention relates to the field of air conditioning equipment technology, and in particular to a start-up control method for a DC fan and related products. Background Technology

[0002] Currently, DC fans typically consist of a DC motor and fan blades connected to the DC motor drive. The common method for starting DC fans is a three-stage starting method. This method includes: first, pre-positioning the rotor of the DC motor in the DC fan to forcefully pull the rotor to a fixed angle; then, increasing the voltage of the DC motor to drive it to accelerate, which is an open-loop control of the DC motor; finally, after the DC motor accelerates to a certain speed, switching the open-loop control of the DC motor to closed-loop control to complete the start-up of the DC fan.

[0003] Before starting the DC fan, if the DC fan has an initial speed, for example, if the DC fan is installed on the outdoor unit of an air conditioning unit and the outdoor unit of the air conditioning unit has an initial speed due to factors such as typhoons, then it is necessary to first obtain the initial state of the DC fan, such as the initial position, initial speed and initial direction of the DC motor rotor in the DC fan, and then control the DC fan to start based on the initial state of the DC fan.

[0004] Therefore, to ensure the smooth startup of a DC fan, a hardware detection circuit needs to be installed in the DC fan to detect the initial rotor position, initial speed, and initial direction of the DC motor before startup. However, setting up a hardware detection circuit in a DC fan increases the equipment cost and the complexity of its hardware structure. Summary of the Invention

[0005] The purpose of this invention is to provide a starting control method and related products for DC fans, which solves the problems of high equipment cost and complex hardware structure of DC motors in the prior art.

[0006] Specifically, in a first aspect, the present invention provides a starting control method for a DC fan, wherein the DC fan includes a DC motor and fan blades, and the DC motor is driven and connected to the fan blades; the starting control method includes:

[0007] In response to the start signal of the DC fan, the initial values ​​of the d-axis feedback current and the q-axis feedback current of the DC motor are detected.

[0008] Obtain the d-axis target current and q-axis target current of the DC motor, and use the d-axis target current and q-axis target current as control targets. Calculate the target control voltage of the DC motor based on the initial values ​​of the d-axis feedback current and q-axis feedback current.

[0009] The initial state of the DC motor is obtained based on the target control voltage, and the initial state includes the initial speed, initial rotor position, and initial direction of rotation of the DC motor.

[0010] The startup strategy of the DC fan is determined based on the initial state, and the DC fan is started according to the startup strategy.

[0011] Further, obtaining the initial state of the DC motor based on the target control voltage includes:

[0012] Obtain the phase voltage timing sequence in the target control voltage;

[0013] The initial direction of rotation is determined as forward or reverse based on the phase voltage timing.

[0014] Furthermore, the step of determining whether the initial direction of rotation is forward or reverse based on the phase voltage timing includes:

[0015] Calculate the time sequence of the total characteristic value change of the target control voltage based on whether the voltage of each phase in the target control voltage is greater than zero.

[0016] The initial direction of rotation, whether forward or reverse, is determined based on the time sequence of changes in the total characteristic value.

[0017] Further, obtaining the initial state of the DC motor based on the target control voltage includes:

[0018] The amplitude of the target control voltage is obtained, and the initial rotational speed is determined based on the amplitude.

[0019] Further, determining the initial rotational speed based on the amplitude includes:

[0020] If the amplitude is less than the set amplitude threshold, the initial rotational speed is set to zero.

[0021] Further, obtaining the initial state of the DC motor based on the target control voltage includes:

[0022] Obtain the composite vector of the target control voltage, and determine the initial position of the rotor based on the direction of the composite vector.

[0023] Further, the step of obtaining the composite vector direction of the target control voltage and determining the initial position of the rotor based on the composite vector direction includes:

[0024] An inverse Park transformation is performed on the target control voltage to transform it from the dp coordinate system to the αβ coordinate system;

[0025] The target control voltage is phase-locked, and a PI calculation is performed based on the phase-locked target control voltage to obtain the initial position of the rotor.

[0026] Furthermore, before determining the startup strategy of the DC fan based on the initial state, the method further includes:

[0027] Determine whether the initial rotational speed is greater than the set upper limit threshold.

[0028] If so, the DC fan will not be started, and the d-axis feedback current and the q-axis feedback current will be continuously monitored.

[0029] Furthermore, determining the startup strategy of the DC fan based on the initial state includes:

[0030] When the initial speed is less than the set lower speed threshold, the starting strategy is set to: sequentially perform rotor positioning, forward dragging and closed-loop control on the DC motor;

[0031] If the initial speed is greater than or equal to the set lower speed threshold, the speed threshold range in which the speed is located is obtained, and the starting strategy is determined based on the speed threshold range and the initial steering.

[0032] Further, determining the starting strategy based on the speed threshold range and the initial steering includes:

[0033] When the speed threshold range is greater than the set lower speed threshold and less than the first set speed threshold:

[0034] If the initial direction of rotation is positive, then the starting strategy is set as follows: the DC motor is sequentially positioned, driven in the forward direction, and controlled in a closed loop.

[0035] If the initial direction of rotation is reverse, the starting strategy is set to: sequentially drive the DC motor in reverse, drive it in the forward direction, and perform closed-loop control.

[0036] When the threshold range is greater than or equal to the first set speed threshold and less than the set speed upper limit threshold:

[0037] If the initial direction of rotation is positive, then the starting strategy is set to: perform closed-loop control on the DC motor;

[0038] If the initial direction of rotation is reverse, the starting strategy is set to: sequentially perform closed-loop deceleration, reverse drag, forward drag, and closed-loop control on the DC motor.

[0039] In a second aspect, the present invention also provides a DC fan system, comprising a DC motor, a fan blade, and a control device, wherein the DC motor is driven and connected to the fan blade; characterized in that the control device comprises a processor and a memory, wherein the memory stores an executable computer program, and the processor is used to execute the computer program to implement the steps of the start-up control method described above.

[0040] Thirdly, the present invention also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the startup control method described in any of the above claims.

[0041] Fourthly, the present invention also provides a computer-readable storage medium having an executable computer program stored thereon, wherein when the computer program is executed by a processor, it implements the steps of the startup control method described in any of the preceding claims.

[0042] The technical solution provided by this invention allows for the acquisition of a target control voltage based on the d-axis and q-axis feedback currents of the DC motor in the DC fan before startup, and the acquisition of the initial state of the DC motor based on this target control voltage. Since the technical solution provided by this invention eliminates the need for additional hardware detection circuits for detecting the DC motor in the DC fan, it reduces the cost and complexity of the hardware structure. Furthermore, the calculation of the initial state of the DC motor based on the target control voltage also improves the safety and reliability of the DC fan startup.

[0043] The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0044] The following sections will describe some specific embodiments of the invention in detail by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or portions. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0045] Figure 1 This is a schematic flowchart of a DC fan start-up control method according to an embodiment of the present invention;

[0046] Figure 2 This is a schematic diagram of the topology of a DC motor according to an embodiment of the present invention;

[0047] Figure 3 This is a schematic diagram of controlling a DC motor according to an embodiment of the present invention;

[0048] Figure 4 This is a schematic diagram of the target control voltage when the initial direction of rotation of a DC motor is positive, according to an embodiment of the present invention;

[0049] Figure 5 This is a schematic diagram of the target control voltage when the initial direction of rotation of a DC motor is reverse, according to an embodiment of the present invention;

[0050] Figure 6 This is a schematic flowchart illustrating the determination of whether the initial direction of rotation of a DC motor is forward or reverse, according to an embodiment of the present invention.

[0051] Figure 7 This is a schematic flowchart of obtaining the initial position of the rotor of a DC motor according to an embodiment of the present invention;

[0052] Figure 8 This is a schematic flowchart of a DC fan start-up control method according to an embodiment of the present invention;

[0053] Figure 9 This is a schematic diagram of a startup control strategy according to an embodiment of the present invention;

[0054] Figure 10 This is a schematic diagram of a control device in a DC fan according to an embodiment of the present invention;

[0055] Figure 11 This is a schematic diagram of a computer program product according to an embodiment of the present invention;

[0056] Figure 12 This is a schematic diagram of a computer-readable storage medium according to an embodiment of the present invention. Detailed Implementation

[0057] The following reference Figures 1 to 12This invention describes a DC fan start-up control method and related products according to embodiments of the present invention. In this description, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" and "second" may explicitly or implicitly include at least one of that feature, that is, include one or more of that feature. In the description of the present invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified. When a feature "includes or contains" one or more of the features it encompasses, unless otherwise specifically described, this indicates that other features are not excluded and may be further included.

[0058] In the description of this embodiment, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0059] Currently, there are three methods for obtaining the initial state of DC current in a DC fan, among which:

[0060] The first method involves adding extra hardware detection circuitry to the DC fan. This circuitry detects the back electromotive force (EMF) generated by the ambient wind driving the fan blades before startup, and uses this back EMF to calculate the initial speed of the DC motor. Based on this initial speed, the DC fan is then controlled to enter closed-loop operation mode. The disadvantage of this method is that it requires multiple additional hardware detection circuits, increasing the hardware complexity of the DC fan and raising equipment costs.

[0061] The second method involves injecting zero voltage before startup and determining the phase current of the DC motor by adjusting the duty cycle of the PWM (Pulse-Width Modulation) waves in the upper and lower bridge circuits of the three-phase arm bridge circuit. The initial speed and direction of the DC motor are then determined based on this phase current. The drawback of this method is that a high initial speed can lead to a large, uncontrollable phase current. Therefore, if the DC fan's initial speed is high due to external wind, or if a large back electromotive force is generated, short-circuiting the lower bridge circuit of the DC motor can increase the braking current and raise the DC bus voltage. Excessive DC bus voltage can damage the DC motor's power devices and bus capacitors, affecting the safety of the DC fan.

[0062] The third method, based on the FOC (Field Oriented Control) framework, adds a speed tracking unit and an acceleration adaptive control unit. This utilizes the acceleration from the acceleration adaptive control unit and the current speed command recorded when exiting the speed tracking unit to perform FOC field-oriented control, gradually approaching the target speed for the flyover start, ensuring the real-time operating speed of the permanent magnet synchronous motor equals the target speed. This method is suitable for situations where the DC fan has an initial speed before startup, but cannot control the smooth startup of a DC fan from a stationary state.

[0063] This invention provides a start-up control method for a DC fan. This start-up control method eliminates the need to detect the initial state of the DC motor through hardware devices, thereby reducing the equipment cost and hardware complexity of the DC fan and improving its safety and reliability.

[0064] Please see Figure 1 , Figure 1 The diagram shown is a schematic flowchart of a DC fan start-up control method in one embodiment of the present invention, wherein the DC fan includes a DC motor and fan blades, and the topology of the inverter in the DC motor is as follows. Figure 2 As shown, VT1, VT2, VT3, VT4, VT5, and VT6 are all power switching transistors connected to form a three-phase arm-bridge inverter circuit. VD1, VD2, VD3, VD4, VD5, and VD6 are freewheeling diodes. R1, R2, and R3 are resistors, C is the bus capacitor, and M is a DC motor, which can be a PMSM motor (Permanent-magnet Synchronous Motor). The DC fan can apply control voltage to the inverter to control the power switching transistors in the inverter, enabling the inverter to convert DC voltage into three-phase AC power to supply power to the DC motor.

[0065] The method for controlling the DC motor in this embodiment is as follows: Figure 3 As shown, the system first receives the target current Id_ref on the d-axis and the target current Iq_ref on the q-axis of the DC motor M. Then, it detects the feedback current generated by the DC motor M and performs a coordinate transformation to convert the feedback current to the αβ coordinate system. For example, the feedback current of the DC motor M includes phase a, phase b, and phase c feedback currents. The system can detect the phase a and phase b feedback currents and perform a coordinate transformation based on these currents to convert them to the αβ coordinate system. Next, the system uses a Parker transformation to convert the feedback current from the αβ coordinate system to the dq coordinate system to obtain the d-axis feedback current Id and the q-axis feedback current Iq of the DC motor.

[0066] Then, with the control objectives of controlling the d-axis feedback current Id of the DC motor to the d-axis target current Id_ref and the q-axis feedback current Iq to the q-axis target current Iq_ref, PI calculations are performed on the d-axis feedback current Id and the q-axis feedback current Iq of the DC motor to obtain the d-axis voltage Vd and the q-axis voltage Vq of the control voltage. The pre-start detection module can obtain the control voltage calculated based on the d-axis and q-axis feedback currents of the DC motor from the existing control module of the DC fan, and perform an integral calculation (i.e., 1 / s operation) based on this control voltage and the initial rotor position of the DC motor to obtain the rotor angle of the DC motor.

[0067] Next, the amplitude (Amp) and phase (Phase) of the control voltage are calculated. Based on these values ​​and the rotor angle (θ) of the DC motor M, a corresponding SVPWM (Space Vector Pulse Width Modulation) wave is generated. Finally, the generated SVPWM wave is used to control the power switches of the inverter in the DC motor, enabling the inverter to convert the DC voltage Udc into a three-phase AC voltage, which is then used to drive the DC motor M.

[0068] like Figure 1 As shown, the start-up control method for the DC fan in this embodiment includes the following steps:

[0069] Step S102: Determine if a start signal for a DC fan has been received;

[0070] If so, proceed to step S104;

[0071] Step S104: Detect the DC motor to obtain the initial values ​​of the feedback current of the DC motor on the d-axis and q-axis;

[0072] Step S106: Obtain the target current of the DC motor along the d-axis and the target current along the q-axis;

[0073] Step S108: Using the target current of the DC motor's d-axis and q-axis as control targets, calculate the target control voltage of the DC motor based on the initial values ​​of the DC motor's d-axis feedback current and q-axis feedback current, respectively.

[0074] Step S110: Obtain the initial state of the DC motor based on the target control voltage. The initial state includes the initial speed, initial rotor position, and initial direction of rotation of the DC motor.

[0075] Step S112: Obtain the starting control strategy of the DC motor based on the initial state of the DC motor, and control the DC fan to start according to the starting control strategy.

[0076] In step S102 above, the control device of the DC fan can determine whether the DC fan needs to be started based on the received start signal. For example, if the DC fan is the fan on the outdoor unit of an air conditioner, the control device of the DC fan can be the control device of the air conditioning equipment, and the start signal can be the air conditioning equipment start signal input by the user.

[0077] In step S104 above, if the DC fan is in a windy environment, such as an air conditioner outdoor unit in a typhoon or other windy environment, the DC fan may be affected by the ambient wind and its speed may change. Since the DC fan is driven by a DC motor, the rotation of the fan blades will drive the rotor of the DC motor to rotate, and the rotation of the rotor will cause the DC motor to generate an electromotive force, which in turn generates a feedback current.

[0078] In this embodiment, before the DC fan is started, the initial values ​​of the feedback current of each phase of the DC motor are detected, and coordinate transformation calculations are performed based on the initial values ​​of the feedback current of each phase to obtain the initial values ​​of the d-axis feedback current and the initial values ​​of the q-axis feedback current of the DC motor.

[0079] In step S106 above, the target current of the d-axis and the target current of the DC motor are parameter values ​​input by the user or preset parameter values ​​stored in the DC motor.

[0080] In step S108 above, the target currents Id_ref and Iq_ref of the DC motor along the d-axis are used as control targets. PI calculations are performed based on the initial values ​​of the d-axis and q-axis feedback currents to obtain the corresponding target control voltages. These target control voltages include both the d-axis control voltage and the q-axis control voltage. In this embodiment, the values ​​of both the target currents Id_ref and Iq_ref along the d-axis are zero.

[0081] exist Figure 3 In the application scenario shown, the pre-start detection module can obtain the control voltage calculated based on the d-axis feedback current and q-axis feedback current of the DC motor from the existing DC fan control module, and use this control voltage as the target control voltage. Since the target control voltage can be obtained using the existing control algorithm of the DC fan in this embodiment, the complexity of DC fan control can be further reduced.

[0082] In step S110 above, the initial state of the DC motor obtained based on the target control voltage includes the initial speed of the DC motor, the initial rotor position, and the initial direction of rotation.

[0083] In this embodiment, multiple startup control strategies corresponding to initial states can be preset and stored. After obtaining the initial state of the DC fan, the stored data is queried according to the initial state of the DC motor to obtain the startup control strategy corresponding to the initial state of the DC motor.

[0084] Then, in step S112, the DC fan is controlled according to the startup control strategy to complete the startup of the DC fan.

[0085] In summary, this embodiment only requires the existing hardware structure of the DC fan to detect the initial values ​​of the d-axis and q-axis feedback currents through the DC fan's current detection circuit during startup. No additional hardware detection circuit is needed, thus reducing the cost and hardware complexity of the DC fan. Furthermore, this embodiment does not require injecting a zero-voltage vector before startup, preventing damage to power devices and bus capacitors due to excessive braking current at high fan speeds. Additionally, regardless of whether the DC fan is stationary or rotating before startup, this embodiment can acquire a startup control strategy corresponding to the initial state of the DC fan and control its startup, thereby improving the reliability of DC fan startup control.

[0086] In some embodiments of the present invention, the step S110 above, which obtains the initial state of the DC motor based on the acquired target control voltage, includes:

[0087] Obtain the phase voltage timing of the target control voltage, and determine whether the initial direction of the DC motor is forward or reverse based on the phase voltage timing of the target control voltage.

[0088] In this embodiment, the three-phase voltages in the target control voltage are denoted as phase a voltage Va, phase b voltage Vb, and phase c voltage Vc. The timing sequence of each phase voltage in the target control voltage refers to the order in which phase a, phase b, and phase c voltages change. When the rotor of the DC fan rotates in different directions, the resulting feedback current has different timing sequences. Correspondingly, the phase voltage timing sequence of the obtained wooden template control voltage will also be different. Therefore, the initial direction of rotation of the DC fan can be accurately determined based on the phase voltage timing sequence of the target control voltage.

[0089] by Figure 4 and Figure 5 Taking the scenario shown as an example, where Figure 4 This is a schematic diagram of the target control voltage obtained when the initial direction of the DC motor is positive, where the phase voltage sequence in the target control voltage is Va-Vb-Vc; Figure 5 This is a schematic diagram of the target control voltage obtained when the initial direction of rotation of the DC motor is reversed, where the phase voltage sequence of the target control voltage is Va-Vc-Vb.

[0090] Accordingly, in this embodiment, after obtaining the target control voltage, if the phase voltage sequence of the target control voltage is Va-Vb-Vc, it is determined that the initial direction of the DC fan is forward; if the phase voltage sequence of the target control voltage is Va-Vc-Vb, it is determined that the initial direction of the DC fan is reverse.

[0091] The technical solution of this embodiment can accurately determine whether the initial direction of the DC motor is forward or reverse based on the phase voltage timing of the target control voltage. This not only improves the accuracy of the initial direction of the DC motor but also reduces the complexity of the judgment and lowers the implementation difficulty of DC fan start-up control.

[0092] In some embodiments of the present invention, the method described above for determining whether the initial direction of the DC motor is forward or reverse based on the phase voltage timing of the target control voltage is as follows: Figure 6 As shown, it includes the following steps:

[0093] Step S112: Calculate the timing sequence of the total characteristic value change of the target control voltage based on whether the voltage of each phase in the target control voltage is greater than zero;

[0094] Step S114: Determine whether the initial direction of the DC motor is forward or reverse based on the timing of the change in the total characteristic value of the target control voltage.

[0095] In step S112 above, at a certain moment, if one phase voltage of the target control voltage is greater than zero, the single-phase characteristic value of that phase voltage at that moment is recorded as 1; if one phase voltage of the target control voltage is less than zero, the single-phase characteristic value of that phase voltage at that moment is recorded as 0.

[0096] Suppose that at a certain moment, the single-phase characteristic change value of phase a voltage is TempA, the single-phase characteristic change value of phase b voltage is TempB, and the single-phase characteristic change value of phase c voltage is TempC. Then, the total characteristic value Temp of the target control voltage at that moment is:

[0097] Temp=TempA+2×TempB+4×TempC

[0098] In this embodiment, the total characteristic value of the target control voltage can be continuously detected and calculated according to the above method to obtain multiple consecutive total characteristic values ​​of the target control voltage. By arranging these multiple total characteristic values ​​in chronological order, the time sequence of the change of the total characteristic value of the target control voltage can be obtained.

[0099] In step 114 above, after obtaining the total characteristic value change sequence of the target control voltage, the initial direction of the DC motor is determined to be forward or reverse based on the order of change of the total characteristic value in the total characteristic value change sequence.

[0100] Therefore, if the total characteristic value of the target control voltage changes in a cycle of 6→4→5→1→3→2, then the initial direction of the DC motor is determined to be positive.

[0101] Conversely, if the total characteristic value of the target control voltage changes in a cycle of 6→2→3→1→5→4, then the initial direction of the DC motor is determined to be reverse.

[0102] The technical solution of this embodiment provides an implementation method for determining the initial direction of rotation of a DC motor based on the phase voltage timing of the target control voltage. This method can calculate the total characteristic value change timing of the target control voltage based on whether each phase voltage in the target control voltage is greater than 0, and can accurately and quickly determine the initial direction of rotation of the DC fan based on the total characteristic value change timing, thereby reducing the difficulty of starting control of the DC fan.

[0103] In some embodiments of the present invention, the step S110 above, which obtains the initial state of the DC motor based on the acquired target control voltage, includes:

[0104] Calculate the magnitude of the target control voltage, and determine the initial speed of the DC motor based on the magnitude of the target control voltage.

[0105] In this embodiment, the target control voltage amplitude is set to V. amp The d-axis voltage of the target control voltage is V. dmu The q-axis voltage is V qmu The magnitude V of the target control voltage can then be calculated using the following formula. amp :

[0106]

[0107] Since a higher initial speed of a DC motor results in a larger feedback current, and consequently a larger calculated target control voltage amplitude, this embodiment first establishes a preset relationship model to characterize the positive correlation between the initial speed of the DC motor and the corresponding control voltage amplitude. For example, multiple initial speeds of the DC motor and the corresponding control voltage amplitudes can be pre-obtained. Then, curve fitting is performed based on each initial speed and each control voltage amplitude, and the fitted curve is used as the preset relationship model. After calculating the target control voltage amplitude V of the DC motor... amp Then, based on this amplitude V amp Based on the established preset relationship model, the initial speed of the DC motor is determined.

[0108] The technical solution of this embodiment can accurately and quickly calculate the initial speed of the DC motor based on the amplitude of the target control voltage. This not only improves the accuracy of the obtained initial state of the DC fan, but also reduces the complexity of the acquisition process.

[0109] In some embodiments of the present invention, after calculating the amplitude of the target control voltage, the method for determining the initial speed of the DC motor based on the amplitude of the target control voltage includes:

[0110] Determine whether the amplitude of the target control voltage is less than the set lower limit threshold.

[0111] If so, set the initial speed of the DC motor to zero.

[0112] In this embodiment, when the amplitude of the target control voltage is less than the set lower limit threshold, it can be assumed that the initial speed of the DC fan is very small and will not affect the start-up of the DC fan. Therefore, when the amplitude of the target control voltage is less than the set lower limit threshold, it is determined that the DC fan is in a stationary state, and the initial speed of the DC fan is set to zero, so as to control the start-up of the DC fan according to the start-up strategy when the DC fan is stationary.

[0113] The technical solution of this embodiment can reduce the complexity of calculating the initial speed of the DC motor when the amplitude of the target control voltage is less than the set lower limit threshold, thereby reducing the complexity of starting control of the DC fan.

[0114] In some embodiments of the present invention, the method for obtaining the initial state of the DC motor based on the obtained control voltage of the DC motor in step S110 above includes:

[0115] Obtain the direction of the composite vector of the target control voltage, and determine the initial position of the DC motor rotor based on the direction of the composite vector.

[0116] Since the d-axis feedback current and q-axis feedback current of the DC motor are different when the rotor is in different initial positions in the DC fan, the direction of the composite vector of the target control voltage is also different. Therefore, the initial position of the DC motor rotor can be determined according to the direction of the composite vector of the target control voltage.

[0117] The technical solution of this embodiment can accurately obtain the initial position of the DC motor rotor based on the direction of the composite vector of the target control voltage, thereby improving the reliability and ease of implementation of the DC fan start-up control.

[0118] In some embodiments of the present invention, the method for determining the rotor position of a DC motor based on the composite vector direction of the target control voltage includes:

[0119] First, an inverse Park transformation is performed on the target control voltage to transform it from the dp coordinate system to the αβ coordinate system;

[0120] Then, phase-locked voltage is applied to the target control voltage, and PI calculation is performed based on the phase-locked target control voltage to obtain the rotor position of the DC motor.

[0121] In this embodiment, the calculation formula used in the inverse Parker transformation of the target control voltage is as follows:

[0122] V α =V′ q cosθ+V′ d sinθ

[0123] V β =-V′ q sinθ+V′ d cosθ

[0124] Where V α Let V be the voltage of the target control voltage on the α-axis in the αβ coordinate system. α Let V′ be the voltage of the target control voltage on the β axis in the αβ coordinate system. qLet V′ be the voltage on the q-axis of the target control voltage in the dq coordinate system. d Let V be the target control voltage along the d-axis in the dq coordinate system.

[0125] During the phase-locking process of the target control voltage described above, the phase-locked voltage err is calculated using the following formula:

[0126] err = -V α sinθ-V α cosθ

[0127] The speed of the DC motor is obtained by performing a PI calculation on err, and the rotor position θ' of the DC motor is obtained by integrating the speed. Figure 7 As shown, the calculation formula used when performing PI operation on err is:

[0128] P(k)=K p ×err(k)

[0129] I(k)=I(k-1)+K i ×err(k)

[0130] w(k)=P(k)+I(k)

[0131] Where err(k) represents the phase-locked voltage at the k-th iteration during the PI operation on the phase-locked voltage err, P(k) is the proportional term obtained at the k-th iteration during the PI operation on err, I(k) is the integral term obtained at the k-th iteration during the PI operation on err, w(k) is the DC motor speed obtained at the k-th iteration during the PI operation, and K... p This is the proportionality coefficient. After obtaining the speed of the DC motor, the rotor stroke of the DC motor can be obtained by integrating this speed. Then, based on the initial rotor position and rotor stroke of the DC motor, the rotor position of the DC motor can be calculated.

[0132] In the technical solution of this embodiment, after performing an inverse Parker transformation on the target control voltage of the DC motor during the process of obtaining the rotor position of the DC motor, the target control voltage is phase-locked, thus ensuring the accuracy of the obtained initial rotor position of the DC motor.

[0133] In some embodiments of the present invention, before obtaining the starting control strategy of the DC motor based on the initial state of the DC motor in step S120, the method further includes:

[0134] Determine whether the initial speed of the DC motor is greater than the set upper speed threshold.

[0135] If so, the DC fan will not be started, and the feedback current of the DC fan will be continuously monitored.

[0136] In this embodiment, if the initial speed of the DC motor is greater than the set upper speed threshold, it can be determined that the speed of the DC fan is too high to facilitate start-up control. Therefore, to improve the safety of the DC motor, before obtaining the start-up control strategy for the DC fan, this embodiment first determines whether the initial speed of the DC fan is greater than the set upper speed threshold. If the initial speed of the DC fan is greater than the set upper speed threshold, the DC fan is not started, and the feedback current of the DC fan is continuously monitored so that the DC motor can be started only when the initial speed of the DC motor is less than the set upper speed threshold.

[0137] In one embodiment of the present invention, the step S110 above, determining the start-up strategy of the DC fan based on the initial state of the DC fan, includes:

[0138] Determine whether the initial rotation of the DC motor is less than the set lower speed threshold.

[0139] If so, the start-up control strategy for the DC fan is determined to include: sequentially performing rotor positioning, forward drive, and closed-loop control on the DC motor;

[0140] If not, obtain the speed threshold range where the initial speed of the DC motor is located, and obtain the start-up control strategy of the DC fan by combining the speed threshold range and the initial direction of rotation of the DC fan.

[0141] In this embodiment, rotor positioning and forward driving of the DC motor are part of open-loop control. Rotor positioning involves inputting a fixed vector current into the DC motor to drag its rotor to a fixed angle. For example, the d-axis or q-axis of the DC motor can be positioned at a corresponding fixed angle by dragging the rotor. After rotor positioning, the DC motor speed is increased to drive it forward. Once the motor speed reaches the set speed, closed-loop control of the DC motor is initiated.

[0142] The technical solution of this embodiment allows the three-stage control method to be directly used as the start-up control strategy for DC fans when the initial rotation of the DC motor is less than the set lower speed threshold, thereby reducing the complexity of DC fan start-up control.

[0143] In some embodiments of the present invention, the method for obtaining the start-up control strategy of the DC fan based on the threshold range of the initial speed of the DC motor and the initial direction of rotation of the DC fan includes:

[0144] If the initial speed of the DC motor falls within a speed threshold range that is greater than the set lower speed threshold and less than the first set speed threshold, then it is further determined whether the initial direction of the DC motor is forward or reverse.

[0145] If it is positive, the starting control strategy of the DC fan includes: sequentially performing rotor positioning, positive drive and closed-loop starting control of the DC motor;

[0146] If it is the reverse direction, the starting control strategy of the DC fan includes: sequentially driving the DC motor in the reverse direction, driving it in the forward direction, and controlling the start-up in a closed loop.

[0147] If the initial speed of the DC motor falls within a speed threshold range that is greater than or equal to the first set speed threshold and less than the set upper speed threshold, then it is further determined whether the initial direction of the DC motor is forward or reverse.

[0148] If it is positive, the start-up control strategy for the DC fan includes: closed-loop control of the DC motor;

[0149] If it is the reverse direction, the starting control strategy of the DC fan includes: sequentially performing closed-loop speed reduction, reverse drive, forward drive, and closed-loop control on the DC motor.

[0150] The aforementioned reverse drive of the DC fan refers to inputting current into the DC motor to reduce its speed, thus facilitating forward drive. The aforementioned closed-loop speed reduction of the DC motor refers to braking the DC motor through closed-loop control to reduce the reverse speed of the DC fan.

[0151] The technical solution of this embodiment can quickly determine the start-up control strategy of a DC fan based on the speed threshold range in which the initial speed of the DC motor is located and the initial direction of the DC motor when the initial speed of the DC motor is greater than the set lower speed threshold and less than the set upper speed threshold, thereby improving the reliability of the start-up control of the DC fan.

[0152] In some embodiments of the present invention, the start-up control method for the DC fan is as follows: Figure 8 As shown, it includes the following steps:

[0153] Step S202: Determine if a start signal for the DC fan has been received;

[0154] If so, proceed to step S204;

[0155] Step S204: Detect the DC motor to obtain the initial values ​​of the feedback current of the DC motor on the d-axis and q-axis;

[0156] Step S206: Obtain the target current of the DC motor along the d-axis and the target current along the q-axis;

[0157] Step S208: Using the target current of the DC motor's d-axis and q-axis as control targets, calculate the target control voltage of the DC motor based on the initial values ​​of the DC motor's d-axis feedback current and q-axis feedback current, respectively.

[0158] Step S210: Obtain the initial direction of rotation, initial speed, and initial rotor position of the DC motor based on the target control voltage phase voltage timing, amplitude, and composite vector direction, respectively;

[0159] Step S212: Determine whether the initial speed of the DC motor is greater than the set upper speed threshold;

[0160] If yes, proceed to step S214; otherwise, proceed to step S216.

[0161] Step S214: Do not start the DC fan, and continuously monitor the d-axis feedback current and q-axis feedback current of the DC motor;

[0162] Step S216: Determine whether the initial speed of the DC motor is less than the set lower speed threshold.

[0163] If yes, proceed to step S218; otherwise, proceed to step S220.

[0164] Step S218: Determine the start-up control strategy for the DC fan, which includes: sequentially performing rotor positioning, forward drive, and closed-loop control on the DC motor;

[0165] Step S220: Obtain the speed threshold range where the initial speed of the DC motor is located, and obtain the start-up control strategy of the DC fan by combining the speed threshold range with the initial direction of the DC fan.

[0166] The starting control strategy for the DC fan obtained through the technical solution of this embodiment is as follows: Figure 9 As shown.

[0167] Step S224: Control the DC fan to start according to the obtained start-up control strategy.

[0168] The startup control method provided in this embodiment can not only solve the problems of high equipment cost and complex hardware structure of DC fans, but also improve the accuracy of the initial state calculation of DC fans, thereby improving the reliability of DC fan startup control.

[0169] In some embodiments of the present invention, an air-cooled unit is also provided, comprising a compressor, a controller, and multiple fixed-frequency fans, wherein the multiple fixed-frequency fans are arranged in a preset distribution pattern. The controller includes a processor 32 and a memory 30, such as... Figure 10As shown, the memory 30 stores an executable computer program 11, and the processor executes the computer program 11 to implement the steps of the DC fan start-up control method in any of the above embodiments.

[0170] The flowcharts provided in the above embodiments are not intended to indicate that the operations of the method will be performed in any particular order, or that all operations of the method are included in all every case. Furthermore, the method may include additional operations. Within the scope of the technical concept provided by the methods of these embodiments, additional variations can be made to the above methods.

[0171] It should be understood that in some embodiments, the components may be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods may be implemented using software or firmware stored in memory and executed by a suitable instruction execution system.

[0172] This embodiment also provides a computer program product 10 and a computer-readable storage medium 20. Figure 11 This is a schematic diagram of a computer program product 10 according to an embodiment of the present invention. Figure 12 This is a schematic diagram of a computer-readable storage medium 20 according to an embodiment of the present invention. The computer program product 10 includes a computer program 11, which, when executed by a processor 32, implements the steps of the start-up control method for any of the aforementioned DC fans. The computer-readable storage medium 20 stores the aforementioned computer program 11 thereon, which, when executed by the processor 32, implements the steps of the start-up control method for any of the aforementioned DC fans.

[0173] The computer program 11 used to perform the operations of this invention may be assembly instructions, Instruction Set Architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, status setting data, integrated circuit configuration data, or source code or object code written in any combination of one or more programming languages ​​and procedural programming languages. The computer program 11 may execute entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the latter case, the remote computer may be connected to the user's computer via any type of network, including a Local Area Network (LAN) or Wide Area Network (WAN), or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, to perform aspects of this invention, electronic circuits, including, for example, programmable logic circuits, Field-Programmable Gate Arrays (FPGAs), or Programmable Logic Arrays (PLAs), may execute computer-readable program instructions using status information from computer-readable program instructions to personalize the electronic circuits.

[0174] For the purposes of this embodiment, computer program product 10 is a related product that includes computer program 11.

[0175] For the purposes of this embodiment, the computer-readable storage medium 20 is a tangible device capable of holding and storing a computer program 11. It can be any device capable of containing, storing, communicating, propagating, or transmitting the computer program 11 for use by or in conjunction with an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable storage medium 20 include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable optical disc read-only memory (CD-ROM), digital versatile disc (DVD), memory stick, floppy disk, mechanical encoding device, and any suitable combination thereof.

[0176] Therefore, those skilled in the art should recognize that although numerous exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications conforming to the principles of the present invention can be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Thus, the scope of the present invention should be understood and construed as covering all such other variations or modifications.

Claims

1. A method for starting and controlling a DC fan, wherein the DC fan includes a DC motor and fan blades, and the DC motor is connected to the fan blades in a driving manner; characterized in that, The startup control method includes: In response to the start signal of the DC fan, the initial values ​​of the d-axis feedback current and the q-axis feedback current of the DC motor are detected. Obtain the d-axis target current and q-axis target current of the DC motor, and use the d-axis target current and q-axis target current as control targets. Calculate the target control voltage of the DC motor based on the initial values ​​of the d-axis feedback current and q-axis feedback current. The initial state of the DC motor is obtained based on the target control voltage, and the initial state includes the initial speed, initial rotor position, and initial direction of rotation of the DC motor. The startup strategy of the DC fan is determined based on the initial state, and the DC fan is started according to the startup strategy.

2. The start-up control method according to claim 1, characterized in that, The step of obtaining the initial state of the DC motor based on the target control voltage includes: Obtain the phase voltage timing sequence in the target control voltage; The initial direction of rotation is determined as forward or reverse based on the phase voltage timing.

3. The start-up control method according to claim 2, characterized in that, The method of determining whether the initial direction of rotation is forward or reverse based on the phase voltage timing includes: Calculate the time sequence of the total characteristic value change of the target control voltage based on whether the voltage of each phase in the target control voltage is greater than zero. The initial direction of rotation, whether forward or reverse, is determined based on the time sequence of changes in the total characteristic value.

4. The start-up control method according to claim 1, characterized in that, The step of obtaining the initial state of the DC motor based on the target control voltage includes: The amplitude of the target control voltage is obtained, and the initial rotational speed is determined based on the amplitude.

5. The start-up control method according to claim 4, characterized in that, Determining the initial rotational speed based on the amplitude includes: If the amplitude is less than the set amplitude threshold, the initial rotational speed is set to zero.

6. The start-up control method according to claim 1, characterized in that, The step of obtaining the initial state of the DC motor based on the target control voltage includes: Obtain the composite vector of the target control voltage, and determine the initial position of the rotor based on the direction of the composite vector.

7. The start-up control method according to claim 6, characterized in that, The step of obtaining the composite vector direction of the target control voltage and determining the initial position of the rotor based on the composite vector direction includes: An inverse Park transformation is performed on the target control voltage to transform it from the dp coordinate system to the αβ coordinate system; The target control voltage is phase-locked, and a PI calculation is performed based on the phase-locked target control voltage to obtain the initial position of the rotor.

8. The start-up control method according to claim 1, characterized in that, Before determining the startup strategy of the DC fan based on the initial state, the method further includes: Determine whether the initial rotational speed is greater than the set upper limit threshold. If so, the DC fan will not be started, and the d-axis feedback current and the q-axis feedback current will be continuously monitored.

9. The start-up control method according to claim 1, characterized in that, The method of determining the start-up strategy of the DC fan based on the initial state includes: When the initial speed is less than the set lower speed threshold, the starting strategy is set to: sequentially perform rotor positioning, forward dragging and closed-loop control on the DC motor; If the initial speed is greater than or equal to the set lower speed threshold, the speed threshold range in which the speed is located is obtained, and the starting strategy is determined based on the speed threshold range and the initial steering.

10. The start-up control method according to claim 9, characterized in that, Determining the starting strategy based on the speed threshold range and the initial steering includes: When the speed threshold range is greater than the set lower speed threshold and less than the first set speed threshold: If the initial direction of rotation is positive, then the starting strategy is set as follows: the DC motor is sequentially positioned, driven in the forward direction, and controlled in a closed loop. If the initial direction of rotation is reverse, the starting strategy is set to: sequentially drive the DC motor in reverse, drive it in the forward direction, and perform closed-loop control. When the threshold range is greater than or equal to the first set speed threshold and less than the set speed upper limit threshold: If the initial direction of rotation is positive, then the starting strategy is set to: perform closed-loop control on the DC motor; If the initial direction of rotation is reverse, the starting strategy is set to: sequentially perform closed-loop deceleration, reverse drag, forward drag, and closed-loop control on the DC motor.

11. A DC fan system comprising a DC motor, fan blades, and a control device, wherein the DC motor is driven by the fan blades; characterized in that, The control device includes a processor and a memory, wherein the memory stores an executable computer program, and the processor executes the computer program to implement the steps of the startup control method as described in any one of claims 1-10.

12. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the startup control method as described in any one of claims 1-10.

13. A computer-readable storage medium, characterized in that, It stores an executable computer program, which, when executed by a processor, implements the steps of the startup control method as described in any one of claims 1-10.

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