Control device, electric fan, and air conditioning device

Abstract

The invention provides a control device which is configured to control the rotating speed of a permanent magnet synchronous motor. The control device comprises a first controller which is configured to receive a target rotating speed and output a space vector based on a space vector algorithm according to a fed-back phase current, a real-time rotating speed and a phase angle of the permanent magnet synchronous motor; the second controller is configured to execute inversion control based on the space vector so as to generate a driving signal for driving the permanent magnet synchronous motor to operate according to a set target rotating speed; wherein the control frequency of the first controller is higher than that of the second controller; the invention further provides an electric fan and an air conditioning device. On one hand, the deviation between the output torque current and the effective torque current is reduced, on the other hand, the switching loss of the power device is effectively controlled, and the application reliability under the high-temperature working condition is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioning, and particularly to a control device, an electric fan, and an air conditioner. Background Art

[0002] A permanent magnet synchronous motor (PMSM) is a synchronous motor that uses permanent magnets as the excitation source. Its permanent magnets are usually permanent magnets or rare earth magnets, which can generate a strong magnetic field. Therefore, in a permanent magnet synchronous motor, no external excitation is required, which helps to improve efficiency and reduce energy consumption. Since no external excitation is required, a permanent magnet synchronous motor usually has high efficiency, especially in partial load and high-speed operation conditions. Due to its high efficiency, high power density, and precise control ability, the application of permanent magnet synchronous motors in air conditioners, especially in electric fans, is becoming more and more common.

[0003] A permanent magnet synchronous motor usually performs closed-loop control using two variables, namely rotor speed and current. For example, the solution disclosed in the Chinese patent application (CN101127500A): "A DC variable frequency controller for controlling the rotor speed of a permanent magnet synchronous motor, comprising: an input device for providing a reference speed setting value; a sampling device for sampling the phase current of the rotor of the permanent magnet synchronous motor; a first adjustment device for performing speed proportional integral adjustment on the speed setting value and the estimated speed; a first transformation device for performing a first transformation on the sampled phase current; a second transformation device for performing a second transformation on the current value after the first transformation; a second adjustment device for performing current proportional integral adjustment on the phase current; a third transformation device for performing an inverse transformation with the first and second transformation devices to obtain the three-phase voltage signal of the rotor; a third adjustment device for performing sine vector pulse width adjustment on the three-phase voltage signal of the rotor; a driving device for driving the permanent magnet synchronous motor to rotate according to the three-phase voltage signal after pulse width adjustment; a first reconstruction device for reconstructing the three-phase voltage signal after pulse width adjustment into a phase voltage; a sliding mode observer for generating an estimated value of the rotor position signal angle after dynamic compensation according to the reconstructed phase voltage and the current after the first transformation; a second reconstruction device for reconstructing the estimated value of the rotor position signal angle into the estimated speed of the rotor."

[0004] The technical solutions disclosed in the prior art are prone to problems such as excessive temperature rise, overload output of driving power devices, and overheating under high-speed and heavy-load operating conditions. Summary of the Invention

[0005] Aiming at the problems that a permanent magnet synchronous motor is prone to excessive temperature rise, overload output of driving power devices, overheating, etc. under high-speed and heavy-load conditions, the first aspect of this application designs and discloses a control device.

[0006] A control device configured to control the rotational speed of a permanent magnet synchronous motor; the control device includes a first controller configured to receive a target rotational speed and, based on the phase current, real-time rotational speed, and phase angle of the permanent magnet synchronous motor feedback, output a space vector based on a space vector algorithm; and a second controller configured to perform an inverter control based on the space vector to generate a drive signal for driving the permanent magnet synchronous motor to operate at a set target rotational speed; wherein the control frequency of the first controller is higher than that of the second controller.

[0007] In one or more embodiments of the present application, the first controller includes: a first control unit, which is a proportional-integral controller configured to generate a set current quadrature-axis component based on the deviation between the set target rotational speed and the real-time rotational speed; a second control unit, which is a proportional-integral controller configured to generate a voltage quadrature-axis component based on the deviation between the set current quadrature-axis component and the calculated real-time current quadrature-axis component; a third control unit, which is a proportional-integral controller configured to generate a voltage direct-axis component based on the deviation between the set current direct-axis component and the calculated real-time current direct-axis component; and a first calculation unit configured to perform a Revolutionary Park transformation based on the voltage quadrature-axis component and the voltage direct-axis component to output a space vector; wherein the set current direct-axis component is 0.

[0008] In one or more embodiments of the present application, the first controller further includes: a first sampling unit configured to sample the first phase current of the permanent magnet synchronous motor and sample the first phase angle with the moment when the clock in the first controller starts timing as the first current sampling point; a second sampling unit configured to sample the second phase current of the permanent magnet synchronous motor and sample the second phase angle with a moment after the clock in the first controller starts timing as the second current sampling point; and a second calculation unit configured to perform a Clark transformation and a Park transformation based on the first phase current and the first phase angle respectively to obtain a first real-time current quadrature-axis component and a first real-time current direct-axis component, and perform a Clark transformation and a Park transformation based on the second phase current and the second phase angle to obtain a second real-time current quadrature-axis component and a second real-time current direct-axis component.

[0009] In one or more embodiments of the present application, the first controller outputs a first space vector based on the first real-time current direct-axis component and the first real-time current quadrature-axis component, and outputs a second space vector based on the second real-time current direct-axis component and the second real-time current quadrature-axis component; the first controller estimates a first estimated rotational speed formed after performing a first inverter control based on the first space vector, and estimates a second estimated rotational speed formed after performing a second inverter control based on the second space vector; when the rotational speed deviation between the first estimated rotational speed and the second estimated rotational speed satisfies the set range, the first controller updates and takes the second phase angle as the phase angle of the current control cycle.

[0010] In one or more embodiments of the present application, the second controller is configured to perform second inverter control based on the second space vector when the rotational speed deviation between the first estimated rotational speed and the second estimated rotational speed is within a set range, so as to generate a drive signal for driving the permanent magnet synchronous motor to operate at the second estimated rotational speed.

[0011] In one or more embodiments of the present application, the control frequency of the first controller is twice that of the second controller.

[0012] In one or more embodiments of the present application, the control device further includes a power device.

[0013] In one or more embodiments of the present application, the second controller further includes: a first generation unit configured to calculate energy loss based on the second real-time direct-axis current component and the second real-time quadrature-axis current component; a second generation unit configured to calculate power loss based on the thermal resistance of the power device and the set temperature rise; and an adjustment unit configured to calculate and adjust the switching frequency of the power device based on the linear relationship between the energy loss and the power loss.

[0014] In one or more embodiments of the present application, the energy loss is calculated by the following formula:

[0015]

[0016] Where A sw，X , B sw，X and C sw，X are fitting coefficients, which are constants; D sw，X is the correction coefficient of the test voltage U base , which is a constant; K sw，X is the temperature correction coefficient of the switching energy loss, which is a constant, U ce is the actual voltage borne by the power device, is the highest temperature of the power device; i d is the real-time direct-axis current component, i q is the real-time quadrature-axis current component.

[0017] In one or more embodiments of the present application, the power loss satisfies the following formula:

[0018] R th =ΔT / P sw，X

[0019] Where, R th is the thermal resistance, ΔT represents the set temperature rise, and P sw，X is the power loss;

[0020] The linear relationship between the energy loss and the power loss is expressed as:

[0021] P sw，x = f sw E sw，x

[0022] where f sw is the switching frequency of the power device.

[0023] The second aspect of the present application provides an electric fan, including a fan blade; a permanent magnet synchronous motor for driving the fan blade to rotate; and a control device, where the control device can control the rotational speed of the permanent magnet synchronous motor. The control device includes: a first controller configured to receive a target rotational speed and output a space vector based on a space vector algorithm according to the phase current, real-time rotational speed, and phase angle of the permanent magnet synchronous motor fed back; and a second controller configured to perform inverter control based on the space vector to generate a drive signal for driving the permanent magnet synchronous motor to operate at a set target rotational speed; wherein the control frequency of the first controller is higher than that of the second controller.

[0024] The second aspect of the present application provides an air conditioning device, including: an outdoor unit, where an outdoor fan is provided in the outdoor unit, and the outdoor fan includes a permanent magnet synchronous motor and a control device, and the control device can control the rotational speed of the permanent magnet synchronous motor; the control device includes: a first controller configured to receive a target rotational speed and output a space vector based on a space vector algorithm according to the phase current, real-time rotational speed, and phase angle of the permanent magnet synchronous motor fed back; and a second controller configured to perform inverter control based on the space vector to generate a drive signal for driving the permanent magnet synchronous motor to operate at a set target rotational speed; wherein the control frequency of the first controller is higher than that of the second controller.

[0025] The present application replaces the microcontroller or digital signal processor in the prior art with a first controller and a second controller. The first controller is configured to receive a target rotational speed and output a space vector based on a space vector algorithm according to the phase current, real-time rotational speed, and phase angle of the permanent magnet synchronous motor fed back; the second controller is configured to perform inverter control based on the space vector to generate a drive signal for driving the permanent magnet synchronous motor to operate at a set target rotational speed, that is, to further control the switching state of the power device. The permanent magnet synchronous motor responds to the control instruction to generate a corresponding mechanical torque and speed. The control frequency of the first controller is higher than that of the second controller. On the one hand, it reduces the deviation between the output torque current and the effective torque current, and on the other hand, it effectively controls the switching loss of the power device and improves the application reliability under high-temperature conditions.

[0026] After reading the specific embodiments of the present invention in conjunction with the accompanying drawings, other features and advantages of the present invention will become clearer. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0028] Figure 1 Structural schematic block diagram of one or more embodiments of the control device provided by the present invention;

[0029] Figure 2 Control logic schematic diagram of one or more embodiments of the control device provided by the present invention;

[0030] Figure 3 Structural schematic block diagram of the first controller in one or more embodiments of the control device provided by the present invention;

[0031] Figure 4 Structural schematic block diagram of the first controller in one or more embodiments of the control device provided by the present invention;

[0032] Figure 5 Flow chart of the first controller in one or more embodiments of the control device provided by the present invention;

[0033] Figure 6 Flow chart of the first controller in one or more embodiments of the control device provided by the present invention;

[0034] Figure 7 Schematic diagram of a permanent magnet synchronous motor moving in a circular trajectory in space;

[0035] Figure 8 Schematic diagram of spatial angle lag;

[0036] Figure 9 Flow chart of the first controller in one or more embodiments of the control device provided by the present invention;

[0037] Figure 10 Structural schematic block diagram of the second controller in one or more embodiments of the control device provided by the present invention;

[0038] Figure 11 Structural schematic diagram of the electric fan provided by the present invention;

[0039] Figure 12 Structural schematic diagram of the air conditioning device provided by the present invention;

[0040] Figure 13 Structural schematic diagram of the air conditioning device provided by the present invention;

[0041] In the figure: 1, control device; 10, first controller; 20, second controller; 101, first control unit; 102, second control unit; 103, third control unit; 104, first calculation unit; 105, first sampling unit; 106, second sampling unit; 107, second calculation unit; 201, first generation unit; 202, second generation unit; 203, adjustment unit; 2, permanent magnet synchronous motor; 3, fan blade; 4, air conditioning device; 41, outdoor unit; 42, indoor unit; 42-1, indoor unit; 42-2, indoor unit; 401, compressor; 402, outdoor heat exchanger; 403, outdoor fan; 404, throttling element; 405, indoor heat exchanger; 406, indoor fan. Detailed implementation manners

[0042] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0043] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present application.

[0044] The terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, unless otherwise specified, the meaning of "plurality" is two or more.

[0045] In the description of the present application, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0046] In the present invention, unless otherwise clearly specified or limited, the first feature being "on" or "under" the second feature may include direct contact between the first and second features, or may include the first and second features not being in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the horizontal height of the first feature is less than that of the second feature.

[0047] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numerals and / or reference letters in different examples. Such repetition is for the purpose of simplification and clarity and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those of ordinary skill in the art may be aware of the application of other processes and / or the use of other materials.

[0048] Aiming at the problems that the permanent magnet synchronous motor is prone to over-temperature rise, output overload and over-temperature of the driving power device under high-speed and heavy-load conditions, a control device is designed and disclosed in the first aspect of the present application. The control device is configured to control the speed of the permanent magnet synchronous motor, as Figure 1 shown, the control device 1 includes a first controller 10 and a second controller 20, wherein the first controller 10 is configured to receive a target speed and output a space vector based on a space vector algorithm according to the phase current, real-time speed and phase angle of the permanent magnet synchronous motor fed back; the second controller 20 is configured to perform an inverter control based on the space vector to generate a driving signal for driving the permanent magnet synchronous motor to operate at a set target speed, wherein the control frequency of the first controller 10 is higher than that of the second controller 20.

[0049] Hereinafter, the technical effects of the control device 1 shown in Figure 1 will be introduced from the principle.

[0050] As Figure 2As shown, the permanent magnet synchronous motor (PMSM) adopts double - closed - loop control, that is, two closed - loop controls are carried out on the PMSM: the speed loop (speed closed - loop) and the current loop (current closed - loop). This control method can improve the performance and stability of the PMSM system. Among them, the current loop mainly controls the current of the PMSM to ensure that the current generated by the PMSM is consistent with the expected value. The current - loop control can make the motor maintain a stable current output when the load changes. The speed loop, based on the current control, controls the speed of the motor to reach the expected speed. The speed loop can adjust the output of the PMSM when affected by external disturbances or load changes to ensure the stable operation of the system. The double - closed - loop control is used to coordinate the current and speed simultaneously, so that the PMSM can maintain stable performance under different working conditions. In the existing technology, usually a micro - controller (MCU) or a digital signal processor (DSP) is used to execute control algorithms, process feedback signals, calculate control commands, and cooperate with other hardware modules to work.

[0051] The control frequency of the micro - controller or digital signal processor is directly related to the sampling frequency of the motor position detection. If the control frequency of the micro - controller or digital signal processor is low, it may lead to the failure to capture the accurate transformation of the position of the permanent magnet synchronous motor between two samplings, resulting in a position deviation. More specifically, the micro - controller or digital signal processor adjusts the output current according to the position error signal, which contains the current component (also called torque current) used to generate the motor output torque. However, due to the existence of the error signal, the adjusted circuit may not be completely used to generate effective mechanical torque. A part of the output current may be used to counteract the error rather than for actual mechanical work, resulting in a deviation between the output torque current and the effective torque current (the current component in the torque current that is actually used for mechanical work), and not directly converted into active mechanical work, but a part of the current used to counteract the system error, leading to an increase in the input current.

[0052] That is, when the control frequency of the micro - controller or digital signal processor is low, the detected position information deviates greatly from the true position information, resulting in a deviation between the output torque current and the effective torque current, thus causing an increase in the input current of the motor under the same load conditions.

[0053] The SVPWM (Space Vector Pulse Width Modulation) algorithm runs in a microcontroller or a digital signal processor. The goal of the SVPWM algorithm is to achieve precise control of a permanent magnet synchronous motor by adjusting the width and position of voltage vectors. Its basic idea is to simulate the amplitude and frequency of the desired output voltage through a space vector with a specific amplitude and direction. The microcontroller or digital signal processor calculates appropriate voltage vectors and then uses the SVPWM algorithm to convert these vectors into a pulse sequence. This pulse sequence controls the switching states of power devices (such as IGBTs or MOSFETs), thereby generating the required voltage vectors to drive the motor. That is, the higher the conduction frequency of the SVPWM output, the more losses will be caused to the power devices, which will further increase the temperature rise of the power devices and is not conducive to the reliability of the power devices.

[0054] In another aspect, the execution speed of the SVPWM algorithm is determined by the clock frequency of the microprocessor or digital signal processor. The microprocessor calculates the motor control instructions once per control cycle, and the reciprocal of the control cycle is the control frequency. The conduction frequency is the switching frequency of the motor power devices. In principle, it is an integer multiple of the control frequency of the SVPWM algorithm. If the control frequency of the microprocessor is high, the SVPWM algorithm can generate motor control instructions faster, thereby increasing the conduction frequency of the power devices. A higher conduction frequency will increase the switching losses of the power devices.

[0055] From the above analysis, it can be seen that when the control frequency of the microcontroller or digital signal processor is low, the deviation between the position information of the detection position and the true position information is large, resulting in the deviation between the output torque current and the effective torque current. As a result, under the same load conditions, the input current of the permanent magnet synchronous motor increases and the temperature rise increases. When the control frequency of the microcontroller or digital signal processor is high, the higher conduction frequency will also increase the switching losses of the power devices. In actual control, in order to consider factors such as system performance, power loss, and stability, it is only possible to balance control performance and power loss, and the best performance of the microcontroller or digital signal processor cannot be exerted.

[0056] Based on the above problems, in Figure 1In the control device 1 shown, in the present application, the first controller 10 and the second controller 20 are used to replace the microcontroller or digital signal processor in the prior art. The first controller 10 is configured to receive the target speed and, based on the phase current, real-time speed, and phase angle of the feedback permanent magnet synchronous motor, output a space vector based on the space vector algorithm. The second controller 20 is configured to perform inverter control based on the space vector to generate a drive signal for driving the permanent magnet synchronous motor to operate at the set target speed, that is, further control the switching state of the power device. The permanent magnet synchronous motor responds to the control instruction to generate the corresponding mechanical torque and speed. The control frequency of the first controller 10 is higher than that of the second controller 20, which reduces the deviation between the output torque current and the effective torque current on the one hand and effectively controls the switching loss of the power device on the other hand, improving the application reliability under high-temperature conditions.

[0057] In one or more embodiments of the present application, the control frequency of the first controller 10 is twice that of the second controller 20. Both the first controller 10 and the second controller 20 can be microprocessors or other integrated circuits that can achieve the same function.

[0058] As Figure 2 and Figure 3 shown, the control device 1 provided by one or more embodiments of the present application uses the space vector algorithm. The first controller 10 includes a first control unit 101, a second control unit 102, and a third control unit 103.

[0059] The first control unit 101 is a proportional-integral controller (PI controller). The first control unit 101 is configured to generate a set current quadrature-axis component I q _Ref based on the deviation between the set target speed Speed_Ref and the real-time speed ω. The first control unit 101 is the controller in the speed loop and uses the error between the measured value and the expected value (target value) to generate a control instruction. In the embodiments as Figure 2 and Figure 3 shown, the speed loop and the current loop are cascade-controlled, and the output of the first control unit 101 represents the set current quadrature-axis component that needs to be applied to the permanent magnet synchronous motor.

[0060] The second control unit 102 is a proportional-integral controller (PI controller). The second control unit 102 is configured to generate a voltage quadrature-axis component V q based on the deviation between the set current quadrature-axis component I q and the calculated real-time current quadrature-axis component I q .

[0061] The third control unit 103 is a proportional-integral controller (PI controller). The third control unit 103 is configured to be based on the set current direct-axis component Id The deviation between _Ref and the calculated real-time direct-axis current component I d generates the direct-axis voltage component V d .

[0062] The second control unit 102 and the third control unit 103 can be regarded as the space vector control part, which converts the output of the speed loop into a current command. The calculated real-time quadrature-axis current component I q and the real-time direct-axis current component I d are implemented based on cascaded Clark transformation and Park transformation. During Clark transformation, three-phase signals, such as the three-phase currents I a , I b , I c in this application, are converted into two new coordinates, such as the αβ coordinate system. After transformation, I α and I β are obtained, that is, the three-phase AC signal is converted into a two-phase signal, making it easier for the control system to control current and voltage, and decomposing the motor control problem into independent axes, which is more convenient for torque and magnetic field control. Park transformation is performed after Clark transformation, which converts the current in the αβ coordinate system into the current in the dq coordinate system. The dq coordinate system is related to the motor rotor position, making it easier to control the motor. The phase angle θ is used in Park transformation and can be calculated by the common sensorless control algorithms in the prior art.

[0063] After the second control unit 102 and the third control unit 103 obtain the quadrature-axis voltage component V q and the direct-axis voltage component V d , a space vector is further output through the Rev Park transformation (Revolutionary Park transformation) in the first calculation unit 104. The RevPark transformation is used to convert the voltage command in the dq coordinate system into the voltage command in the αβ coordinate system, that is, to generate a space vector in the αβ coordinate system. After generating the space vector, the corresponding PWM signal is generated through the inverter to control the permanent magnet synchronous motor. The dq coordinate system is also called the dynamic coordinate system. The d axis corresponds to the magnetic axis where the current flows, and the q axis is perpendicular to the magnetic axis.

[0064] In one or more embodiments of this application, the target control of I d = 0 is adopted, that is, the control with the direct-axis current component being zero in the dq coordinate system, which is also called the direct-axis current-free control. The direct-axis current component is maintained at zero, so only the quadrature-axis current component for controlling the motor in the dq coordinate system needs to be concerned to achieve the required torque control. Since I d = 0, the direct-axis current component does not affect torque generation, and the system is more simplified.

[0065] Based on the first control unit 101, the second control unit 102, the third control unit 103, and the first calculation unit 104, the first controller 10 is further configured with a first sampling unit 105, a second sampling unit 106, and a second calculation unit 107, as Figure 4 shown.

[0066] The first sampling unit 105 is configured to sample the first-phase current of the permanent magnet synchronous motor and the first phase angle at the moment when the clock in the first controller 10 starts timing as the first current sampling point.

[0067] The second sampling unit 106 is configured to sample the second-phase current of the permanent magnet synchronous motor and the second phase angle at a moment after the clock in the first controller 10 starts timing as the second current sampling point.

[0068] The second calculation unit 107 is configured to perform Clark transformation and Park transformation based on the first-phase current and the first phase angle respectively to obtain the first real-time current quadrature-axis component and the first real-time current direct-axis component, and perform Clark transformation and Park transformation based on the second-phase current and the second phase angle to obtain the second real-time current quadrature-axis component and the second real-time current direct-axis component.

[0069] The first controller 10 outputs a first space vector based on the first real-time current direct-axis component and the first real-time current quadrature-axis component (as shown in step S101 in Figure 5 ), outputs a second space vector based on the second real-time current direct-axis component and the second real-time quadrature-axis component (as shown in step S102 in Figure 5 ), the first controller 10 estimates the first predicted speed formed after performing the first inverter control on the first space vector (as shown in step S103 in Figure 5 ), estimates the second predicted speed formed after performing the second inverter control on the second space vector (as shown in step S104 in Figure 5 ). When the speed deviation between the first predicted speed and the second predicted speed is within the set range (as shown in step S105 in Figure 5 ), the first controller 10 updates the second phase angle as the phase angle of the current control cycle (as shown in step S106 in Figure 5 ).

[0070] In addition, the second controller 20 is configured to perform the second inverter control based on the second space vector when the speed deviation between the first predicted speed and the second predicted speed is within the set range (as shown in step S201 in Figure 6 ), so as to generate a drive signal for driving the permanent magnet synchronous motor to operate at the second predicted speed (as shown in step S202 in Figure 6 ).

[0071] The following introduces from the principle as Figure 5 andFigure 6 The technical effect of the control flow shown

[0072] The voltage space vector can be expressed in the space state as:

[0073]

[0074] Wherein, represents the derivative of the voltage space vector, that is, the rate of change of the vector with time. The voltage space vector is usually used to represent the control target of a permanent magnet synchronous motor. U s represents the amplitude of the voltage space vector, indicating the magnitude of the voltage, e jθ represents the direction of the voltage vector, that is, the angle in the complex plane. The whole expression represents the change of the voltage space vector with time, its amplitude remains unchanged, and its direction rotates at a speed of θ (phase angle) with time, which is the synthesis of U in the αβ coordinate system α and U β obtained, and the voltage can also be denoted as V α and V β .

[0075] When the speed of the permanent magnet synchronous motor is stable, the back electromotive force remains constant, and the amplitude of the synthesized voltage space vector also remains unchanged, moving in a circular trajectory in space, as shown in Figure 7 . The back electromotive force is the voltage induced in the winding when the motor is running, and its magnitude is proportional to the speed of the motor. During stable operation, the back electromotive force usually remains relatively constant because the mechanical and electrical properties of the motor are balanced. If the amplitude of the synthesized voltage vector remains unchanged and the back electromotive force of the motor also remains stable, then in space, the operating point of the motor can form a circular trajectory, the direction of the synthesized voltage vector rotates at a constant speed, and at the same time the magnitude of the back electromotive force remains unchanged. Based on the fact that the back electromotive force amplitude remains constant when the motor speed is in a stable state, the amplitude of the synthesized voltage space vector also remains basically unchanged, and let its magnitude be U s .

[0076] Furthermore, it can be concluded that within two PWM switch operating cycles, the voltage amplitudes are the same, only the operating times of the front and back cycles will have an angular difference. As mentioned above, the back electromotive force is proportional to the speed of the motor. The magnitude and direction of the synthesized voltage vector are constant in the αβ coordinate system, and this synthesized voltage vector simulates the desired phase voltage. Within each PWM switch cycle, this synthesized voltage vector is decomposed into two parts, which are controlled by two half-bridge inverters respectively. Since the magnitude of the synthesized voltage vector is constant, the voltage amplitudes within two PWM switch cycles are the same. However, since the back electromotive force of the motor is related to the speed, the operating time of the phase voltage may have an angular difference within one electrical cycle of the motor, which means that during one revolution of the motor, the operating time of the phase voltage may be slightly different

[0077] Is expressed as the following formula:

[0078]

[0079] Obviously, the angular error is:

[0080] Δθ 1 = ωT s

[0081] Where T s is the control period of the first controller 10. It can be seen that as the control frequency increases, T s decreases, and the detection deviation of the motor position information shrinks.

[0082] The synthetic space vector of the permanent magnet synchronous motor, that is, the synthetic voltage vector u s , lags the ideal voltage by a certain angular deviation. The motor body is equivalent to an impedance element, and the lag of the applied voltage causes a certain angular lag in the applied current. The space vector algorithm synthesizes the ideal voltage vector, but due to the characteristics of the motor itself, the actual voltage vector may lag the ideal voltage in space, and the lag is caused by elements such as inductance and resistance inside the motor, and the current lags the voltage.

[0083] As Figure 8 shown, for the control of I d = 0, in the ideal case without considering the space lag, the current vector acting on the motor body by the positionless control algorithm is equal in magnitude and the same in phase as the quadrature-axis equivalent current (the projection of the motor current space vector in the quadrature-axis direction). However, in practical applications, the microprocessor chip processes data discretely and will buffer and run at least one control period.

[0084] In the control of the permanent magnet synchronous motor, the I d = 0 control means that by controlling the direct current axis current I d = 0 of the motor, the control of the motor torque and speed is realized. The current vectors I d 、I q of the motor and the direct and quadrature-axis equivalent currents I sd 、I sq are equal in magnitude and phase. This is because in the I d = 0 control, the direct current axis current I d of the motor is maintained at zero, so the motor current is mainly concentrated in the alternating current axis current I qAbove. In actual applications, since the data process of a microprocessor or other integrated circuits is usually discretized, that is, measurement and control calculations are performed according to a certain sampling period, this introduces a discrete element. Buffering the data for at least one control period is to ensure that there is enough data for the controller to perform calculations and controls within each control period, that is, to ensure that there is enough up-to-date data at the beginning of each cycle for the controller.

[0085] The current and voltage values of this time will act in the next control period. Therefore, the synthesized current vector will act on the motor body with a certain lag angle. At the same time, there is also a certain execution time delay Td from the analog-to-digital sampling signal to the algorithm estimation and finally to the SVPWM modulation output PWM drive signal. The superposition of these two delays causes the motor to lag, and the angle lag will have an adverse impact on the closed-loop control and the motor body.

[0086] When the permanent magnet synchronous motor operates in the low-speed region, the lag angle is relatively small (the phase difference between the space vector and the ideal vector), and the impact on the accuracy of the closed-loop control is small. This is because at low speeds, the dynamic response of the motor is usually relatively slow, which means that the change of the motor current is relatively slow, and the requirements for the rapid performance of the current and torque responses of the motor itself to the input changes of the controller are relatively low. At the same time, at low speeds, the requirements for the control loop bandwidth are relatively low, and the control system can respond more slowly to changes. Even if there is an angle lag, the control system may be able to adjust within the time of uniform speed and maintain relatively good performance at lower speeds.

[0087] When the speed gradually increases, the angle deviation will increase accordingly, and the deviation angle between the actual synthesized current vector and the ideal synthesized current vector will become larger and larger. The effective torque acting on the motor body generated by the synthesized current vector will be greatly reduced. As a result, under the condition of constant load, the motor current increases and the heating of the power device increases.

[0088] In the ideal state, the quadrature-axis current component I q is equal to the synthesized current vector I s , and from the electromagnetic torque formula, we can get:

[0089] T e = p n ψ f i s

[0090] T e is the electromagnetic torque, that is, the mechanical torque generated by the motor, p n is the number of pole pairs of the motor, ψ f is the permanent magnet flux, i s is the synthesized current vector. Considering the space angle lag, the component of the synthesized current vector i s on the quadrature axis q will no longer be is , accurately expressed as:

[0091] T e = p n ψ f i s cos(Δθ d )

[0092] Obviously, in the closed-loop control of the motor vector, the lag of the synthesized voltage vector angle will cause the electromagnetic torque of the motor to decrease.

[0093] As ω e rises, the larger the angle deviation, the more obvious the decrease in T e , and the weaker the load-carrying capacity. Therefore, at high speeds, reducing the motor lag angle is crucial for improving the output electromagnetic torque and load-carrying capacity performance of the motor.

[0094]

[0095] This formula represents the load torque T L of the motor, where T e is the electromagnetic torque, that is, the mechanical torque generated by the motor, J is the moment of inertia of the motor, p n is the number of pole pairs of the motor, ω is the rotational speed of the motor, and B is the damping coefficient of the motor.

[0096] In control, it is desired to minimize the angle lag based on the controller hardware limitations. Therefore, in this embodiment, the first controller 10 is configured with a first sampling unit 105, a second sampling unit 106, and a second calculation unit 107. The first sampling unit 105 samples the first-phase current and the first phase angle at the first current sampling point. This sampling point can obtain preliminary information about the motor state at the beginning of the control period, providing an initial state estimate for the controller. The second sampling unit 106 samples the second-phase current and the second phase angle at the second current sampling point. The second current sampling point is the sampling point at the middle of the control period. This sampling point is designed to obtain more motor state information within the control period. Since the change in the motor state may be more significant at the middle of the control period, sampling at the middle time can better balance the perception of the motor state and avoid information lag caused by over-relying on the sampling point at the beginning of the period. The second calculation unit 107 performs calculations respectively, and the first controller 10 estimates based on the two calculation results of the second calculation unit 107 respectively. If the speed deviation between the two estimated speeds is within the set range (a manually set value), it indicates that the two estimated speeds are both correct calculation results. The first controller 10 updates and takes the second phase angle as the phase angle of the current control period. Such a design is to obtain as new data as possible within the control period to reduce the angle lag, and at the same time, the state information of the motor in the first controller 10 can be updated more frequently, thereby improving the response speed of the system and reducing the response delay.

[0097] As Figure 9 shown, it is an overall flowchart of the control device 1, specifically including multiple steps:

[0098] Step S301: Trigger an interrupt and receive the target speed. The target speed can be input or generated by an algorithm.

[0099] Step S302: The first sampling unit 105 samples the trial speed, the first-phase current, and the first phase angle.

[0100] Step S303: The second calculation unit 107 obtains the first real-time current quadrature-axis component and the first real-time current direct-axis component based on the first-phase current and the first phase angle.

[0101] Step S304: The first control unit 101 generates the first set current quadrature-axis component based on the deviation between the set target speed and the real-time speed.

[0102] Step S305: The second control unit 102 generates the first voltage quadrature-axis component based on the deviation between the set current quadrature-axis component and the first real-time current quadrature-axis component.

[0103] Step S306: The third control unit 103 generates the first voltage direct-axis component based on the deviation between the set current direct-current component and the first real-time current direct-axis component.

[0104] Step S307: The first calculation unit 104 performs a Revolutionary Park transformation based on the first quadrature-axis voltage component and the first direct-axis voltage component to output a first space vector.

[0105] Step S308: Estimate a first estimated rotational speed formed after performing a first inverter control based on the first space vector.

[0106] Step S309: The second sampling unit 106 samples the real-time rotational speed, the second-phase current, and the second phase angle.

[0107] Step S310: The second calculation unit 107 obtains a second real-time quadrature-axis current component and a second real-time direct-axis current component based on the second-phase current and the second phase angle.

[0108] Step S311: The first control unit 101 generates a second set quadrature-axis current component based on the deviation between the set target rotational speed and the real-time rotational speed.

[0109] Step S312: The second control unit 102 generates a second quadrature-axis voltage component based on the deviation between the set quadrature-axis current component and the second real-time quadrature-axis current component.

[0110] Step S313: The third control unit 103 generates a second direct-axis voltage component based on the deviation between the set direct-axis current component and the second real-time direct-axis current component.

[0111] Step S314: The first calculation unit 104 performs a Revolutionary Park transformation based on the second quadrature-axis voltage component and the second direct-axis voltage component to output a second space vector.

[0112] Step S315: Estimate a second estimated rotational speed formed after performing a second inverter control based on the second space vector.

[0113] Step S316: Presume whether the rotational speed deviation between the first estimated rotational speed and the second estimated rotational speed is within the set range.

[0114] Step S317: Update the second phase angle as the phase angle for the current control period.

[0115] Step S318: Perform a second inverter control based on the second space vector to generate a drive signal for driving the permanent magnet synchronous motor to operate at the second estimated rotational speed.

[0116] The control device 1 further includes a power device. The SVPWM algorithm converts the space vector into a pulse sequence, and the pulse sequence controls the switching state of the power device, thereby driving the motor to operate. As Figure 10As shown, the second controller 20 further includes a first generating unit 201, a second generating unit 202, and an adjusting unit 203. The first generating unit 201 is configured to calculate the energy loss based on the second real-time direct-axis current component and the second real-time quadrature-axis current component. The second generating unit 202 is configured to calculate the power loss based on the thermal resistance of the integrated power module and the set temperature rise. The adjusting unit 203 calculates and adjusts the switching frequency of the power device based on the linear relationship between the energy loss and the power loss.

[0117] Among them, the energy loss is calculated by the following formula:

[0118]

[0119] Where:

[0120] A sw，X 、B sw，X and C sw，X are fitting coefficients, which are constants; D sw，X is the correction coefficient of the test voltage U base ; K sw，X is the temperature correction coefficient of the switching energy loss. The above coefficients can all be obtained by fitting methods under experimental conditions and stored in the form of constants for further calling;

[0121] That is, the current in the direct and quadrature axis coordinate systems, i d is the real-time direct-axis current component, and i q is the real-time quadrature-axis current component;

[0122] In one or more embodiments of the present application, that is, the current components on the direct axis and the quadrature axis obtained according to the second sampling point, that is, the second real-time quadrature-axis current component and the second real-time quadrature-axis current component

[0123] U ce is the actual voltage borne by the power device, is the highest temperature of the power device; usually provided by the component application manufacturer, for example, recorded in the device specification sheet, data manual or technical document provided by the manufacturer.

[0124] The power loss satisfies the following formula:

[0125] R th =ΔT / P sw，X

[0126] Among them, R th is the thermal resistance, ΔT represents the set temperature rise, and P sw，X is the power loss;

[0127] The linear relationship between energy loss and power loss is expressed as:

[0128] P sw，X = f sw E sw，X

[0129] where f sw is the switching frequency of the power device.

[0130] When the set temperature increase is constant (for example, it can be a desired set value), the corresponding power loss can be deduced, and further the ideal switching frequency can be determined. Through the design of the second controller 20, by monitoring the energy loss and power loss of the power device, the heat of the device can be managed more effectively. By adjusting the switching frequency of the power device, it helps to adapt to different working conditions and improve the dynamic response performance. The adjustment of the adjustment unit 203 is carried out on the premise of maintaining the stability of the permanent magnet synchronous motor, and for example, it can be selectively executed only in the state of high-temperature operation.

[0131] As Figure 11 shown, the second aspect of the present application provides an electric fan. The electric fan includes a fan blade 3, a permanent magnet synchronous motor 2, and a control device 1. The control device 1 includes: a first controller 10 configured to receive a target speed and output a space vector based on a space vector algorithm according to the phase current, real-time speed, and phase angle of the permanent magnet synchronous motor 2 fed back; a second controller 20 configured to perform inverter control based on the space vector to generate a drive signal for driving the permanent magnet synchronous motor 2 to operate at a set target speed; wherein, the control frequency of the first controller 10 is higher than the control frequency of the second controller 20. For the specific structures of the first controller 10 and the second controller 20, refer to the detailed description of the above embodiments and will not be elaborated here.

[0132] As Figure 12 and Figure 13 shown, the third aspect of the present application provides an air conditioning device including an outdoor unit. An outdoor fan 403 is provided in the outdoor unit, and the outdoor fan 403 includes a permanent magnet synchronous motor 2 and a control device 1. The control device 1 can control the speed of the permanent magnet synchronous motor 2. The control device 1 includes: a first controller 10 configured to receive a target speed and output a space vector based on a space vector algorithm according to the phase current, real-time speed, and phase angle of the permanent magnet synchronous motor 2 fed back; a second controller 20 configured to perform inverter control based on the space vector to generate a drive signal for driving the permanent magnet synchronous motor 2 to operate at a set target speed; wherein, the control frequency of the first controller 10 is higher than the control frequency of the second controller 20. For the specific structures of the first controller 10 and the second controller 20, refer to the detailed description of the above embodiments and will not be elaborated here.

[0133] In this application, the air conditioner 4 performs the refrigeration cycle of the air conditioner 4 by using a compressor 401, a condenser, an expansion valve 404, and an evaporator. The refrigeration cycle includes a series of processes involving compression, condensation, expansion, and evaporation to cool or heat the indoor space.

[0134] The low-temperature and low-pressure refrigerant enters the compressor 401, and the compressor 401 compresses the refrigerant gas into a high-temperature and high-pressure state and discharges the compressed refrigerant gas. The discharged refrigerant gas flows into the condenser. The condenser condenses the compressed refrigerant into a liquid phase, and heat is released to the surrounding environment through the condensation process.

[0135] The expansion valve 404 expands the high-temperature and high-pressure liquid-phase refrigerant formed by condensation in the condenser into a low-pressure liquid-phase refrigerant. The evaporator evaporates the refrigerant expanded in the expansion valve 404 and returns the refrigerant gas in the low-temperature and low-pressure state to the compressor 401. The evaporator can achieve a refrigeration effect by using the latent heat of evaporation of the refrigerant to exchange heat with the material to be cooled. Throughout the cycle, the air conditioner 4 can adjust the temperature of the indoor space.

[0136] The outdoor unit 41 of the air conditioner 4 refers to the part of the refrigeration cycle including the compressor 401 and the outdoor heat exchanger 402. The indoor unit 42 of the air conditioner 4 includes an indoor heat exchanger 405, and the expansion valve 404 can be provided in the indoor unit or the outdoor unit 41. An indoor blower 406 is also provided in the indoor unit 42.

[0137] The indoor heat exchanger 405 and the outdoor heat exchanger 402 serve as condensers or evaporators. When the indoor heat exchanger 405 serves as a condenser, the air conditioner 4 serves as a heater in the heating mode. When the indoor heat exchanger 405 serves as an evaporator, the air conditioner 4 serves as a cooler in the cooling mode.

[0138] With the same configuration, multiple indoor units can also be provided in the air conditioner, as Figure 13 shown by the indoor unit 42-1 and the indoor unit 42-2.

[0139] In the description of the above embodiments, specific features, structures, materials, or characteristics can be combined in a suitable manner in any one or more embodiments or examples.

[0140] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A control device configured to control the rotational speed of a permanent magnet synchronous motor; Characterized in that, it includes: A first controller configured to receive a target rotational speed and output a space vector based on a space vector algorithm according to the phase current, real-time rotational speed, and phase angle of the permanent magnet synchronous motor fed back; and A second controller configured to perform inverter control based on the space vector to generate a drive signal for driving the permanent magnet synchronous motor to operate at a set target rotational speed; wherein, the control frequency of the first controller is higher than that of the second controller.

2. The control device according to claim 1, characterized in that: The first controller includes: A first control unit, which is a proportional-integral controller configured to generate a set current quadrature axis component based on the deviation between the set target rotational speed and the real-time rotational speed; A second control unit, which is a proportional-integral controller configured to generate a voltage quadrature axis component based on the deviation between the set current quadrature axis component and the calculated real-time current quadrature axis component; A third control unit, which is a proportional-integral controller configured to generate a voltage direct axis component based on the deviation between the set current direct axis component and the calculated real-time current direct axis component; and A first calculation unit configured to perform a Revolutionary Park transformation based on the voltage quadrature axis component and the voltage direct axis component to output the space vector; wherein, the set current direct axis component is 0.

3. The control device according to claim 1, characterized in that: The first controller further includes: A first sampling unit configured to sample the first phase current of the permanent magnet synchronous motor and sample the first phase angle with the moment when the clock in the first controller starts timing as the first current sampling point; A second sampling unit configured to sample the second phase current of the permanent magnet synchronous motor and sample the second phase angle with a moment after the clock in the first controller starts timing as the second current sampling point; and A second calculation unit configured to perform Clark transformation and Park transformation based on the first phase current and the first phase angle respectively to obtain a first real-time current quadrature axis component and a first real-time current direct axis component, and perform Clark transformation and Park transformation based on the second phase current and the second phase angle to obtain a second real-time current quadrature axis component and a second real-time current direct axis component; The first controller outputs a first space vector based on the first real-time current direct axis component and the first real-time current quadrature axis component, and outputs a second space vector based on the second real-time current direct axis component and the second real-time current quadrature axis component; the first controller estimates a first estimated rotational speed formed after performing first inverter control based on the first space vector, and estimates a second estimated rotational speed formed after performing second inverter control based on the second space vector; when the rotational speed deviation between the first estimated rotational speed and the second estimated rotational speed is within a set range, the first controller updates and uses the second phase angle as the phase angle of the current control cycle.

4. The control device according to claim 3, characterized in that: The second controller is configured to perform second inverter control based on the second space vector when the rotational speed deviation between the first estimated rotational speed and the second estimated rotational speed meets the set range, so as to generate a drive signal for driving the permanent magnet synchronous motor to operate at the second estimated rotational speed.

5. The control device according to any one of claims 1 to 4, wherein: The control frequency of the first controller is twice that of the second controller.

6. The control device according to claim 1, wherein: It further includes a power device; The second controller further includes: A first generating unit configured to calculate energy loss based on the real-time direct-axis component of current and the real-time quadrature-axis component of current; A second generating unit configured to calculate power loss based on the thermal resistance of the power device and the set temperature rise; and An adjusting unit configured to calculate and adjust the switching frequency of the power device based on the linear relationship between the energy loss and the power loss.

7. The control device according to claim 6, wherein: The energy loss is calculated by the following formula: Where A sw，X , B sw，X and C sw，X are fitting coefficients; D sw，X is the correction coefficient of the test voltage U base ; K sw，X is the temperature correction coefficient of the switching energy loss, and all are constants; U ce is the actual voltage borne by the power device, is the maximum temperature of the power device; i d is the direct-axis component of the real-time current, and i q is the quadrature-axis component of the real-time current.

8. The control device according to claim 7, wherein: The power loss satisfies the following formula: R th = ΔT / P sw，X Among them, R th is the thermal resistance, ΔT represents the set temperature increase, and P sw，X is the power loss; The linear relationship between the energy loss and the power loss is expressed as: P sw，X = f sw E sw，X where f sw is the switching frequency of the power device.

9. An electric fan, including: A fan blade; A permanent magnet synchronous motor for driving the fan blade to rotate; and A control device that can control the rotational speed of the permanent magnet synchronous motor; wherein the control device includes: A first controller configured to receive a target rotational speed, and based on the phase current, real-time rotational speed, and phase angle of the permanent magnet synchronous motor fed back, output a space vector based on a space vector algorithm; and A second controller configured to perform inverter control based on the space vector to generate a drive signal for driving the permanent magnet synchronous motor to operate at a set target rotational speed; wherein the control frequency of the first controller is higher than that of the second controller.

10. An air conditioning device, including: An outdoor unit, in which an outdoor fan is provided, and the outdoor fan includes a permanent magnet synchronous motor and a control device that can control the rotational speed of the permanent magnet synchronous motor; wherein the control device includes: A first controller configured to receive a target rotational speed, and based on the phase current, real-time rotational speed, and phase angle of the permanent magnet synchronous motor fed back, output a space vector based on a space vector algorithm; and A second controller configured to perform inverter control based on the space vector to generate a drive signal for driving the permanent magnet synchronous motor to operate at a set target rotational speed; wherein the control frequency of the first controller is higher than that of the second controller.

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