Permanent magnet synchronous motor speed re-throw method based on zero current control

Abstract

The embodiment of the application relates to the control technical field of permanent magnet synchronous motors, and specifically provides a permanent magnet synchronous motor speed re-throw method based on zero current control, a computer readable storage medium and computer equipment, wherein the speed re-throw method comprises the following steps: a permanent magnet synchronous motor speed re-throw method is characterized in that the speed re-throw method comprises the following steps: the stator current of the permanent magnet synchronous motor is adjusted to zero, and the rotor position and speed information of the permanent magnet synchronous motor are preliminarily estimated; the electromagnetic torque of the permanent magnet synchronous motor is adjusted to zero, and the preliminarily estimated rotor position and speed are accurately estimated; according to the accurate estimation result of the rotor position and speed information, a position sensorless control strategy corresponding to the speed is adopted to complete the speed re-throw of the permanent magnet synchronous motor. Through the constitution, the accuracy of position information can be improved, and the current impact during the speed re-throw can be effectively inhibited.

Description

Technical Field

[0001] This invention relates to the field of control technology for permanent magnet synchronous motors, and specifically provides a method for re-suspension of a permanent magnet synchronous motor with speed based on zero-current control, a computer-readable storage medium, and a computer device. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) are widely used in rail transportation, electric vehicles, and industrial automation due to their advantages such as high efficiency, high power density, and low noise. However, high-performance control of PMSMs relies heavily on precise measurement of rotor position and speed. In certain applications, under specific operating conditions, PMSMs need to be able to quickly and smoothly resume normal operation after a power outage to ensure production continuity and system reliability. Specifically, the process of restarting a PMSM after a power outage during operation is called belt-speed re-start.

[0003] In traditional applications, position sensors such as photoelectric encoders or resolvers are typically used to obtain position information for vector control. The use of position sensors not only increases the system's size and cost but also reduces its reliability. Therefore, sensorless control of permanent magnet synchronous motors (PMSMs) has become a research hotspot in recent years. In sensorless control, achieving smooth and stable belt-speed re-start requires accurately obtaining the initial rotor position and speed. However, for sensorless control systems, the rotor position information of the PMSM before restart is unknown. Directly initiating a vector control scheme at this point may lead to problems such as low starting torque, reverse rotation, and overcurrent faults.

[0004] As an improvement, existing sensorless belt-speed re-start control methods mainly include back EMF detection, zero-current control, virtual resistance, and short-circuit current methods. The back EMF detection method requires an additional voltage sensor or sampling circuit. The zero-current control method uses a zero current command and estimates the rotor's initial position and speed by outputting voltage. Its advantage is rapid estimation of the rotor's initial value; however, since the estimate is calculated based on a momentary voltage command, the result fluctuates significantly. The virtual resistance method effectively avoids current surges during belt-speed re-start; however, because the resistance of the virtual resistor changes with the rotor speed, the position estimation accuracy is also affected by the speed. The short-circuit current method determines the motor's initial position information by analyzing the stator current response after repeatedly applying a zero-voltage vector to the motor. Therefore, the short-circuit current method has a fast convergence speed but poor parameter robustness and high sampling requirements. Summary of the Invention

[0005] The present invention aims to at least partially solve the above-mentioned technical problems and / or solve at least some of the above-mentioned technical problems. The present invention proposes a belt speed re-switching method for permanent magnet synchronous motors based on zero current control, which aims to ensure that the belt speed re-switching process of permanent magnet synchronous motors can be completed quickly within the full speed application range.

[0006] In a first aspect, the present invention provides a belt-speed re-start method for a permanent magnet synchronous motor based on zero-current control. This belt-speed re-start method includes the following steps: adjusting the stator current of the permanent magnet synchronous motor to zero, and initially estimating the rotor position and speed information of the permanent magnet synchronous motor; adjusting the electromagnetic torque of the permanent magnet synchronous motor to zero, and accurately estimating the initially estimated rotor position and speed; and, based on the accurate estimation result of the rotor position and speed information, using a sensorless control strategy corresponding to the speed to complete the belt-speed re-start of the permanent magnet synchronous motor.

[0007] In one possible implementation of the above-mentioned method for re-energizing a permanent magnet synchronous motor based on zero-current control, the step of "adjusting the stator current of the permanent magnet synchronous motor to zero and preliminarily estimating the rotor position and speed information of the permanent magnet synchronous motor" includes: adjusting the stator current of the permanent magnet synchronous motor to zero using a proportional-resonant (PR) controller; and extracting the rotor position and speed information of the permanent magnet synchronous motor using a phase-locked loop (PLL) detector to preliminarily estimate the rotor position and speed information.

[0008] In one possible implementation of the above-mentioned method for speed-based re-starting of a permanent magnet synchronous motor based on zero-current control, the step of "adjusting the stator current of the permanent magnet synchronous motor to zero using a PR controller" includes: the voltage equation of the permanent magnet synchronous motor in the stationary coordinate system is:

[0009]

[0010] In the formula, u α and u β Let i be the voltage along the α-axis and β-axis of the stationary coordinate system, respectively. α and i β Let θ be the current along the α-axis and β-axis, respectively. r Indicates the rotor position, R s For the stator's resistance and inductance parameters L α L β and L αβ The relationship with the equivalent inductance of the dq axis is as follows:

[0011]

[0012] In the formula, L d L represents the d-axis equivalent inductance. q Indicates the q-axis equivalent inductance;

[0013] The voltage equation for the permanent magnet synchronous motor in the rotating coordinate system is as follows:

[0014]

[0015] In the formula, u sd and u sq The voltages along the d-axis and q-axis are respectively, i sd and i sq These are the d-axis and q-axis currents, respectively, ω r Let ψ be the rotor speed. m Let p be the flux linkage of a permanent magnet, and p be the differential operator.

[0016] The transfer function of the PR controller is:

[0017]

[0018] In the formula, ω c This is a non-ideal resonant frequency.

[0019] In one possible implementation of the above-mentioned method for speed-driven re-starting of a permanent magnet synchronous motor based on zero-current control, the step of "adjusting the electromagnetic torque of the permanent magnet synchronous motor to zero and accurately estimating the initially estimated rotor position and speed" includes: under the zero-current control strategy, the stator current is always equal to zero, at which point i sd =0,isq =0,i α =0,i β =0, substituting into the aforementioned formulas (1) and (3), we can obtain:

[0020]

[0021] Magnetic flux linkage and electromagnetic torque can be written in a rotating coordinate system as follows:

[0022]

[0023] When the reference voltages output by the PR controller are respectively and Based on formula (5), the voltage expression under zero current control can be calculated as follows:

[0024]

[0025] In the formula, The reference voltage for the α-axis is... This is the β-axis reference voltage. This is a preliminary estimate of the rotor phase. This is a preliminary estimate of the rotor speed.

[0026] In one possible implementation of the above-mentioned method for re-energizing a permanent magnet synchronous motor based on zero-current control, the step of "adjusting the electromagnetic torque of the permanent magnet synchronous motor to zero and accurately estimating the initially estimated rotor position and speed" includes: the electromagnetic torque equation of the permanent magnet synchronous motor in the rotating coordinate system is:

[0027]

[0028] In the formula, ψ d ,ψ q The flux linkages along the d-axis and q-axis are respectively, p n For extreme logarithms, T e Electromagnetic torque;

[0029] The electromagnetic torque depends on the stator current and the torque angle δ, so the equation for the electromagnetic torque can also be written in the following form:

[0030]

[0031] In the formula, I s Where L is the effective value of the stator phase current, r is the effective stator lamination length, and B is the air gap radius. m N represents the fundamental amplitude of the permanent magnet flux linkage. s This represents the number of turns in the phase coil;

[0032] Given that the electromagnetic torque command value is zero, the torque angle is close to zero, so equation (8) can be written as:

[0033] T e =k Te sinδ≈k Te δ (14)

[0034] In the formula, δ is the torque angle. When the observed rotor speed is greater than the actual speed, δ is greater than 0, and vice versa.

[0035] In one possible implementation of the above-mentioned method for re-energizing a permanent magnet synchronous motor based on zero-current control, the step of "completing the re-energizing of the permanent magnet synchronous motor using a sensorless control strategy corresponding to the rotational speed based on the accurate estimation of the rotor position and rotational speed information" includes: when the accurately estimated rotational speed of the permanent magnet synchronous motor is less than or equal to a first preset rotational speed, a first sensorless control strategy is used to complete the re-energizing of the permanent magnet synchronous motor; and / or when the accurately estimated rotational speed of the permanent magnet synchronous motor is greater than a second preset rotational speed, a second sensorless control strategy is used to complete the re-energizing of the permanent magnet synchronous motor; wherein the second preset rotational speed is greater than or equal to the first preset rotational speed.

[0036] In one possible implementation of the above-mentioned method for re-switching a permanent magnet synchronous motor with speed based on zero-current control, the first sensorless control strategy is a sensorless control strategy based on pulsating square wave injection; and / or the second sensorless control strategy is a sensorless control strategy based on a model reference adaptive observer.

[0037] In one possible implementation of the above-mentioned method for re-energizing a permanent magnet synchronous motor based on zero-current control, the step of "completing the re-energizing of the permanent magnet synchronous motor using a sensorless control strategy corresponding to the rotational speed based on the accurate estimation of the rotor position and speed information" includes: when the rotational speed of the permanent magnet synchronous motor is less than or equal to a first preset speed, a sensorless control strategy based on pulsating square wave injection is adopted, and the high-frequency pulse voltage signal for estimating the rotor reference frame is injected as follows:

[0038]

[0039] The high-frequency induced current in a stationary coordinate system caused by the components of a high-frequency pulse voltage signal can be expressed as:

[0040]

[0041] In the formula, θ rLet i be the rotor position, Δθ be the rotor position estimation error, and i be the rotor position. αh For the α-axis high-frequency induced current, i βh This refers to the high-frequency induced current along the β-axis.

[0042] When the speed of the permanent magnet synchronous motor is greater than the second preset speed, the speed and position of the rotor in the normal sensorless control strategy are estimated by activating the model reference adaptive observer:

[0043]

[0044] The speed adaptation mechanism is as follows:

[0045]

[0046] Technical effects:

[0047] It can be seen that the preferred embodiment of the present invention has the following advantages:

[0048] 1. Employing a zero-current control method based on a PR regulator can effectively avoid current surges during belt-speed re-start. Specifically, the current regulator is designed in a stationary coordinate system, thus eliminating the need for rotor position information. Compared to PI regulators, this method is more suitable for belt-speed re-start conditions of permanent magnet synchronous motors, enabling zero steady-state error voltage tracking at specific frequencies and providing better anti-interference capabilities.

[0049] 2. Positionless speed-driven re-switching of permanent magnet synchronous motors can be achieved without adding extra hardware, saving components and thus reducing costs.

[0050] 3. The belt-driven re-switching method does not require the use of parameters such as the rotor position information of the permanent magnet synchronous motor when approximating the rotor position information in the first step, thus having stronger parameter robustness.

[0051] 4. Compared with the traditional zero-current control method, this invention uses a PLL detector to extract rotor position and speed information from the output voltage of the PR regulator, which speeds up the convergence of rotor position and speed information and thus makes the estimation results smoother.

[0052] 5. The rotor position information optimization method based on zero torque control designed in this invention utilizes the characteristic that the torque angle is proportional to the output torque under zero torque control mode, so that the rotor position information output by the PR regulator is further converged to the actual value, thus further improving the estimation accuracy of rotor position information.

[0053] 6. Compared with the short-circuit current method, which requires multiple injections (applying a zero voltage vector to the motor), the rotor position detection method of the present invention can maintain high accuracy across the entire speed range of permanent magnet synchronous motors and can ensure rapid completion of the belt speed re-engagement process across the entire speed range.

[0054] In summary, in the preferred embodiment of the present invention, the belt speed re-switching method for permanent magnet synchronous motors based on zero-current control can improve the estimation accuracy and convergence speed of the rotor position information of the permanent magnet synchronous motor, effectively suppress the current surge during belt speed re-switching, and has stronger parameter robustness.

[0055] In a second aspect, the present invention provides a computer-readable storage medium including a memory adapted to store a plurality of program codes adapted to be loaded and executed by a processor to perform the belt-speed re-switching method for permanent magnet synchronous motors based on zero-current control as described in any of the preceding claims.

[0056] It is understood that the computer-readable storage medium has all the technical effects of the aforementioned zero-current control-based permanent magnet synchronous motor belt speed re-switching method, which will not be elaborated here.

[0057] Those skilled in the art will understand that all or part of the processes in the present invention's method for speed-based re-switching of a permanent magnet synchronous motor based on zero-current control can be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which includes, but is not limited to, program code for executing the aforementioned method for speed-based re-switching of a permanent magnet synchronous motor based on zero-current control. For ease of explanation, only the parts relevant to the present invention are shown. The computer program code can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable storage medium can include: any entity or device capable of carrying the computer program code, a medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory, a random access memory, an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc. It should be noted that the content contained in the computer-readable storage medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable storage medium does not include electrical carrier signals and telecommunication signals.

[0058] In a third aspect, the present invention provides a computer device including a memory and a processor, the memory being adapted to store a plurality of program codes, the program codes being adapted to be loaded and executed by the processor to perform the belt-speed re-switching method for permanent magnet synchronous motors based on zero-current control as described in any of the preceding claims.

[0059] It is understood that this device possesses all the technical effects of the aforementioned zero-current control-based permanent magnet synchronous motor belt-speed re-switching method, which will not be elaborated upon here. This device can be a computer-controlled device comprising various electronic devices.

[0060] The computer device may include a processor, memory, input / output interfaces, a communication interface, a display unit, and an input device. The processor, memory, and input / output interfaces are connected via a system bus, and the communication interface, display unit, and input device are also connected to the system bus via the input / output interfaces. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The input / output interfaces are used for exchanging information between the processor and external devices. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, NFC (Near Field Communication), or other technologies. When the computer program is executed by the processor, it implements a thermal management control method for a power battery. The display unit is used to form a visually visible image and may be a display screen, a projection device, or a virtual reality imaging device. The display screen can be an LCD screen or an e-ink screen. The input device of the computer device can be a touch layer covering the display screen, or buttons, trackballs, or touchpads set on the casing of the computer device, or external keyboards, touchpads, or mice, etc. Attached Figure Description

[0061] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings, in which:

[0062] Figure 1 This diagram illustrates a flow chart of a method for re-energizing a permanent magnet synchronous motor based on zero-current control according to an embodiment of the present invention.

[0063] Figure 2 This diagram shows a timeline of a belt-speed re-discharge method according to an embodiment of the present invention.

[0064] Figure 3 The logic block diagram of zero-current control based on the PR regulator is shown in the stationary coordinate system;

[0065] Figure 4 The diagram shows the low-pass filtering and normalization processing of the voltage signal.

[0066] Figure 5 The diagram shows the logic block diagram of the initial estimation of rotor position and speed information based on the PLL controller.

[0067] Figure 6 The normalized voltage phasor diagram is shown.

[0068] Figure 7 A block diagram illustrating the optimization strategy for rotor position and speed based on zero-torque control is shown; and

[0069] Figure 8 A block diagram of a belt speed re-spinning method based on hybrid sensorless control is shown. Detailed Implementation

[0070] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0071] It should be noted that in the description of this invention, terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," indicating directional or positional relationships, are based on the directional or positional relationships shown in the accompanying drawings. These are merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0072] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "setting," and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection, an indirect connection through an intermediate medium, or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0073] Furthermore, to better illustrate the present invention, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced even without certain specific details. In some instances, sensorless control principles well-known to those skilled in the art are not described in detail, in order to highlight the main points of the present invention.

[0074] This invention provides a sensorless method for re-suspension of a permanent magnet synchronous motor (PMSM) across its full speed range, based on zero-current control. This method employs a zero-current control strategy using a PR regulator, effectively suppressing current surges during re-suspension. Since this method does not require the use of PMSM parameters (compared to existing zero-current control techniques), it exhibits stronger parameter robustness and faster convergence speed. As described below, it can essentially restore a freely running IPMSM to its normal state within 350ms.

[0075] Main reference Figure 1 In one possible implementation, the belt speed re-switching method based on zero-current control provided by the present invention includes the following steps:

[0076] S100. The stator current of the permanent magnet synchronous motor is adjusted to zero using a PR regulator, and the rotor position and speed information of the permanent magnet synchronous motor are extracted using a PLL to make a preliminary estimate of the rotor position and speed.

[0077] S200. Adjust the electromagnetic torque of the permanent magnet synchronous motor to zero, and use the zero torque control method to accurately estimate the initially estimated rotor position and speed.

[0078] S300. Based on the accurate estimation results of the rotor position and speed, a sensorless control strategy corresponding to the speed is adopted to complete the belt speed re-switching of the permanent magnet synchronous motor, thereby restoring the freely running permanent magnet synchronous motor to the normal sensorless control strategy.

[0079] Regarding the statement "using a sensorless control strategy corresponding to the specified rotational speed to complete the speed-up reactivation of the permanent magnet synchronous motor, thereby restoring the freely running permanent magnet synchronous motor to a normal sensorless control strategy," in one possible implementation, the present invention employs a hybrid sensorless control scheme to enable speed-up reactivation of the permanent magnet synchronous motor. For example, under low-speed conditions, a control strategy based on pulsating square-wave injection (PSWI) can be used. In this way, the high-frequency induced current can be separated from the stator current using the symmetry of the input signal, and the rotor speed and position can be obtained from the high-frequency induced current using a signal extraction method. Under medium- and high-speed conditions, a model reference adaptive system (MRAS) observer can be used to estimate the rotor speed and position for normal sensorless control. The mode selector can switch the sensorless control strategy based on the accurately estimated rotor speed, and a speed hysteresis loop is set during the switching process to ensure a smooth transition between the two control schemes. When the precisely estimated rotor speed is greater than the upper limit of the hysteresis switching threshold, a positionless control strategy based on the MRAS observer can be used. When the precisely estimated rotor speed is less than or equal to the lower limit of the hysteresis switching threshold, a positionless control strategy based on pulsating square wave injection can be used.

[0080] First, define the three-phase coordinate system, stationary coordinate system, and rotating coordinate system of the IPMSM. The three-phase coordinate system of the IPMSM consists of three coordinate axes with a phase difference of 120° (denoted as the A-axis, B-axis, and C-axis). The stationary coordinate system of the IPMSM (e.g., Figure 6 (As shown) The stationary coordinate system (α-axis and β-axis) does not change with time. The α-axis of the stationary coordinate system coincides with the A-axis in the three-phase coordinate system. The rotating coordinate system of the IPMSM is a time-rotating coordinate system. The d-axis and q-axis of the rotating coordinate system are perpendicular to each other. The angle between the d-axis of the rotating coordinate system and phase A of the three-phase coordinate system is the rotor position angle θ. r .

[0081] The voltage equation of IPMSM in the stationary coordinate system is:

[0082]

[0083] In the formula, u α and u β The voltages along the α and β axes are respectively, i α and i β Let θ be the current along the α-axis and β-axis, respectively. r Indicates the rotor position, R s For the stator resistance, inductance, and related parameters L... α Lβ and L αβ The relationship with the equivalent inductance of the dq axis is as follows:

[0084]

[0085] In the formula, L d L represents the d-axis equivalent inductance. q This represents the q-axis equivalent inductance.

[0086] The voltage equation of IPMSM in the rotating coordinate system is:

[0087]

[0088] In the formula, u sd and u sq The voltages along the d-axis and q-axis are respectively, i sd and i sq These are the d-axis and q-axis currents, respectively, ω r Let ψ be the rotor speed. m Let p be the flux linkage of the permanent magnet and p be the differential operator.

[0089] To reduce the current surge during belt-speed re-start, this invention employs a PR controller to regulate the stator current to zero. The transfer function of the non-ideal PR controller is as follows:

[0090]

[0091] In the formula, ω c This is a non-ideal resonant frequency.

[0092] Under the zero-current control strategy, the stator current is always equal to 0. At this time, i sd =0,i sq =0,i α =0,i β =0, substituting it into formulas (1) and (3), we can obtain:

[0093]

[0094]

[0095] Magnetic flux linkage and electromagnetic torque can be written in a rotating coordinate system as follows:

[0096]

[0097] When the reference voltages output by the PR controller are respectively and Based on the aforementioned formula (5), the voltage expression under zero current control can be calculated as follows:

[0098]

[0099] In the formula, The reference voltage for the α-axis is... This is the β-axis reference voltage. This is a preliminary estimate of the rotor phase. This is a preliminary estimate of the rotor speed (the superscript "^" for a variable indicates the estimated value of that variable).

[0100] In one possible implementation, to obtain a more accurate estimate of the rotor position, a low-pass filter is used to suppress high-frequency noise present in the output voltage. For example, the transfer function of the low-pass filter is:

[0101]

[0102] In the formula, f L This is the cutoff frequency of the low-pass filter.

[0103] In one possible implementation, in order to estimate rotor position information using the same control parameters across the entire speed range, the amplitude of the output voltage signal needs to be normalized as follows:

[0104]

[0105] In the formula, This is the filtered α-axis output voltage. This is the filtered β-axis output voltage. The normalized α-axis output voltage, This is the normalized β-axis output voltage.

[0106] Theoretically, the rotor position information can be directly estimated using equation (11) by employing the arctangent method based on equation (8):

[0107]

[0108] However, in practical applications, even after filtering the estimation results, significant fluctuations still occur. To obtain a smoother rotor position, this invention uses a phase-locked loop (PLL) controller circuit to extract rotor position and speed information.

[0109] It should be noted that a phase-locked loop (PLL) controller, as a feedback control system, is characterized by using an externally input reference signal to control the frequency and phase of the internal oscillation signal, thereby achieving automatic tracking of the output signal frequency to the input signal frequency. It is typically used in closed-loop tracking circuits. The PLL controller's workflow is as follows: the output signal is fed back to the input terminal, and after loop adjustment, the output angular frequency is made equal to the input frequency, and the phase difference between the input and output signals remains constant, thus achieving phase locking.

[0110] like Figure 5 As shown, the voltage signal after normalization and filtering can be used for preliminary estimation of rotor position and speed information. Among them, The normalized α-axis output voltage, This is the normalized β-axis output voltage. After Park transformation, the output is the normalized q-axis and d-axis voltage reference values. and The d-axis voltage reference value is considered For error signals, Each through the proportional link k p_pll and the integral stage k p_pll / s. Where, k p_pll This is an important parameter used to adjust the response of the PLL control loop, mainly used to adjust the amplification of the error signal in order to achieve rapid correction of phase or frequency errors. p_pll In a phase-locked loop (PLL), the phase or frequency error is integrated to gradually eliminate the steady-state error, allowing the error to approach zero when the system reaches stability, thus maintaining precise phase locking. The PI controller adjusts the frequency and phase of its output signal based on the filtered error signal, thereby ensuring that the output signal frequency matches the input signal frequency. The voltage vector position θ is determined by integrating the output frequency. v Then, the rotor position and speed are extracted from it according to equation (18).

[0111] The electromagnetic torque equation of IPMSM in a rotating coordinate system is:

[0112]

[0113] In the formula, ψ d ,ψ q The flux linkages along the d-axis and q-axis are respectively, p n For extreme logarithms, T e It is electromagnetic torque.

[0114] The electromagnetic torque depends on the stator current and the torque angle δ, so the equation for the electromagnetic torque can also be written in the following form:

[0115]

[0116] In the formula, I s Where L is the effective value of the stator phase current, r is the effective stator lamination length, and B is the air gap radius. m N represents the fundamental amplitude of the permanent magnet flux linkage. s This represents the number of turns of the phase coil.

[0117] Given that the electromagnetic torque command value is zero, the torque angle is close to zero, so equation (8) can be written as:

[0118] T e =k Te sinδ≈k Te δ (14)

[0119] In the formula, δ is the torque angle. When the observed rotor speed is greater than the actual speed, δ is greater than 0; otherwise, δ is less than 0. Therefore, based on the observed rotor speed and torque closed-loop control, the estimated rotor speed can be precisely converged to the actual speed. And to ensure that the estimated position of the rotor converges precisely to the actual position.

[0120] When switching to the normal sensorless control scheme, the mode selector can switch the sensorless control strategy based on the rotor's estimated speed (accurate estimation result), and ensure a smooth transition between the two sensorless control strategies by setting a speed hysteresis during the switching process. For example, when the rotor's estimated speed is less than or equal to the lower limit of the hysteresis switching threshold (when the IPMSM is in the low-speed range), a PSWI-based sensorless control strategy can be used. When the rotor's estimated speed is greater than the upper limit of the hysteresis switching threshold (when the IPMSM is in the medium-high speed range), the rotor's speed and position information in the normal sensorless control scheme can be estimated by activating the MRAS observer.

[0121] Main reference Figure 1 and Figure 2 In one specific implementation, the belt-speed re-start method for permanent magnet synchronous motors based on zero-current control includes the following three steps:

[0122] S1. Use a PR controller to adjust the stator current to zero, and then make a preliminary estimate of the rotor position and speed information based on the PLL controller;

[0123] S2. Adjust the electromagnetic torque to zero, and accurately estimate the rotor position and speed based on the torque angle.

[0124] As in this example;

[0125] S3. The mode selector selects a suitable positionless control algorithm based on the motor speed. Based on the hybrid sensorless solution, it restores the freely running motor to the normal sensorless control strategy, realizing belt speed re-start.

[0126] Reference Figure 2 In this example, the current is controlled to zero at 100 seconds; at 250 seconds, the system switches to torque fine-tuning to obtain more accurate position information; and at 350 ms, it switches to the normal sensorless control scheme. Therefore, the freely running IPMSM can be quickly restored to normal operation within 350 ms.

[0127] The following section will elaborate on the three-step method for achieving belt-speed re-start of a permanent magnet synchronous motor.

[0128] I. Zero-current control of the stator based on a PR controller:

[0129] The transfer function of an ideal PR controller can be written as:

[0130]

[0131] In the formula, K p and K i The controller represents the proportional and integral gain of the PR controller, ω. n This is the ideal resonant frequency.

[0132] It can be seen that since the gain of the PR regulator is infinite at the ideal resonant frequency, an ideal PR regulator can achieve zero steady-state error tracking of the stator current. However, under high gain conditions, the system is more susceptible to noise, which poses a challenge to system stability. To address this issue, a non-ideal PR controller is used in this invention, with the following transfer function:

[0133]

[0134] In the formula, ω c This is a non-ideal resonant frequency.

[0135] like Figure 3 As shown, The reference current for the α-axis is... The reference current for the β-axis is... The reference voltage for the α-axis is... θ is the reference voltage along the β axis. V Let be the phase of the output voltage. The phase is set to 0 to ensure that the dynamic stator current is zero and the output voltage phase θ is zero. V Reference voltage Calculated using the following formula:

[0136]

[0137] When the stator current is 0, the inverter's output voltage is synchronized with the electromotive force of the IPMSM. The stator voltage of the IPMSM is consistent with the inverter's output reference voltage. Based on the aforementioned formula (5), the reference voltages can be calculated respectively. and speed The relationship between them:

[0138]

[0139] In the formula, This is a preliminary estimate of the rotor phase. This is a preliminary estimate of the rotor speed.

[0140] Wherein, the output voltage phase θ V It contains the rotor's speed and position information, specifically:

[0141]

[0142] Theoretically, the rotor position can be directly estimated using formulas (17), (19), and (20). However, in practical applications, even after filtering the estimation results, significant fluctuations still occur. To obtain a smoother initial rotor position and more accurate estimation results, this invention employs a PLL-based rotor position and speed observer. For example, when the stator current is adjusted to zero, the phase-locked loop observer immediately begins to function.

[0143] A phase-locked loop (PLL) is used to extract the initial velocity and position information of the rotor. The normalized αβ-axis output voltage is transformed by Park into a normalized dq-axis voltage reference value. Each through the proportional gain function k p_pll and integral controller k p_pll The rotor speed is determined by a proportional-integral filter on the output signal, and the voltage vector position θ is obtained by integrating the speed. v Then, the rotor position information is extracted using formula (19). At the same time, by adjusting the input voltage signal, the extraction result can be made smoother.

[0144] To obtain a smooth voltage for the phase-locked loop observer, a low-pass filter is used to suppress high-frequency noise in the output voltage signal. Its transfer function is:

[0145]

[0146] In the formula, f L This is the cutoff frequency of the low-pass filter.

[0147] like Figure 4 As shown, in order to estimate rotor position information using the same control parameters across the entire speed range, the amplitude of the output voltage signal needs to be normalized.

[0148]

[0149] Based on the PR controller, the stator current is adjusted to zero. At this time, the normalized voltage... and The equations in a rotating reference frame can be expressed as:

[0150]

[0151] When the belt speed re-start method is activated for 50ms, the initial values ​​of the rotor speed and position are extracted from the output value of the PR-based regulator to accelerate the convergence speed of the observer.

[0152] II. Optimization and estimation of rotor position and speed based on zero torque control

[0153] The torque estimate for IPMSM is:

[0154]

[0155] In the formula, This is an estimated value for electromagnetic torque. This is the estimated value of the d-axis flux linkage. This is the estimated value for the q-axis flux linkage.

[0156] According to formula (7), the magnetic flux linkage is:

[0157]

[0158] like Figure 7 As shown, when the torque is set to 0, the torque angle is also close to 0. According to formula (8), the electromagnetic torque in the dq rotating coordinate system can be described as follows:

[0159] T e =k Te sinδ≈k Te δ (26)

[0160] in δ is the torque angle. When the observed rotor speed is greater than the actual speed, δ is greater than 0, and vice versa. Therefore, based on the observed speed and torque closed-loop control, the estimated position can be accurately converged to the actual position.

[0161] III. Switching to a normal sensorless control scheme

[0162] In rail transit traction systems, IPMSMs have a wide speed range, and a single sensorless control strategy cannot guarantee stable operation across the entire speed range. Therefore, this invention employs a hybrid sensorless control strategy combining a MRAS observer and pulsating square wave injection for subsequent normal sensorless operation. Other signal injection-based or model-based sensorless control strategies are also applicable for normal sensorless operation. Specifically, in the aforementioned hybrid sensorless scheme, a hybrid sensorless control strategy combining a MRAS observer and pulsating square wave injection can be used. However, the sensorless control strategy at medium and high speeds can be replaced by any other model-based sensorless control strategy, and the sensorless control strategy at low speeds can be replaced by any other signal injection-based control strategy. The mode selector determines the rotor speed based on the estimated speed. Switching to a positionless control strategy, switching control schemes as follows Figure 8 As shown, specifically, a speed hysteresis loop is set during the switching process to ensure a smooth transition between the two sensorless control strategies. For example, in this case, when... When a positionless control strategy based on an MRAS observer is selected, when At that time, a positionless control strategy based on pulsating square wave injection is selected, where ω th_H It is the upper limit of the hysteresis switching threshold, and is ω th_L The lower limit of the hysteresis switching threshold is explained in detail below for the sensorless control scheme in this example.

[0163] In the case where the IPMSM is in the low-speed range, a sensorless control strategy based on PSWI is adopted, and the high-frequency pulse voltage signal injected to estimate the rotor reference frame is:

[0164]

[0165] When the IPMSM is in the low-speed range, the high-frequency induced current caused by the high-frequency pulse voltage signal component in the stationary coordinate system can be expressed as:

[0166]

[0167] In the formula, θ r Let i be the rotor position, Δθ be the rotor position estimation error, and i be the rotor position. αh For the α-axis high-frequency induced current, i βh This is the β-axis high-frequency induced current. Utilizing the symmetry of the input signal, the stator current can be decomposed into a high-frequency induced current i. αh and i βh Then, the rotor speed and position information are further extracted.

[0168] When the IPMSM is in the medium to high speed range, the mode selector estimates the rotor speed and position in the normal sensorless control strategy by activating the MRAS observer:

[0169]

[0170] As mentioned earlier, adding a superscript ^ to a parameter indicates an estimated value for that parameter.

[0171]

[0172] Referring to Popov's superstability theory, the velocity adaptation mechanism is as follows:

[0173]

[0174] As can be seen, in the preferred embodiment of the present invention, compared with the existing belt-speed re-start method, it has a faster convergence speed and higher estimation accuracy in rotor position estimation. Furthermore, the zero-current control method based on the PR regulator can effectively suppress current surges during re-start, and does not require motor parameters in the regulator design process, exhibiting strong parameter robustness. In addition, the present invention can quickly achieve belt-speed re-start of the PMSM across the entire speed range.

[0175] It should be noted that although the steps in the above embodiments are described in a specific order, those skilled in the art will understand that in order to achieve the effects of the present invention, different steps do not necessarily have to be executed in such an order. They can be executed simultaneously or in other orders, and some steps can be added, replaced or omitted.

[0176] It should be noted that although the above-described method for speed-driven re-switching of a permanent magnet synchronous motor based on zero-current control has been used as an example, those skilled in the art will understand that the present invention is not limited thereto. In fact, users can flexibly adjust the relevant steps and parameters according to actual application scenarios and other factors.

[0177] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A method for re-energizing a permanent magnet synchronous motor based on zero-current control, characterized in that, The belt-speed re-sponse method includes the following steps: Adjusting the stator current of the permanent magnet synchronous motor to zero, and initially estimating the rotor position and speed information of the permanent magnet synchronous motor; including: The stator current of the permanent magnet synchronous motor is adjusted to zero using a PR controller; The rotor position and speed information of the permanent magnet synchronous motor are extracted using a phase-locked loop detector to make a preliminary estimate of the rotor position and speed information; The electromagnetic torque of the permanent magnet synchronous motor is adjusted to zero, and the initially estimated rotor position and speed are precisely estimated; specifically, this includes: Based on the preliminary estimation results of the rotor position and speed information, the estimated values ​​of electromagnetic torque and magnetic flux are calculated. The electromagnetic torque estimate of the permanent magnet synchronous motor is used as the input of the closed-loop control, and the output of the closed-loop control is added to the initially estimated speed information to obtain the accurately estimated speed information, and then the accurately estimated rotor position is obtained. Based on the accurate estimation results of the rotor position and speed information, a sensorless control strategy corresponding to the speed is adopted to complete the belt-speed re-start of the permanent magnet synchronous motor.

2. The method for re-energizing a permanent magnet synchronous motor based on zero-current control according to claim 1, characterized in that, The phrase "using a PR controller to adjust the stator current of the permanent magnet synchronous motor to zero" refers to... include: The voltage equation of the permanent magnet synchronous motor in the stationary coordinate system is as follows: (1) In the formula, and They are respectively stationary coordinate systems shaft and Voltage of the shaft, and They are respectively shaft and shaft current, Indicates the rotor position. For stator resistance and inductance parameters , and and dq The relationship between the shaft equivalent inductances is as follows: (2) In the formula, L d express d Shaft equivalent inductance, L q express q Shaft equivalent inductance; The voltage equation for the permanent magnet synchronous motor in the rotating coordinate system is as follows: (3) In the formula, and They are respectively d shaft and q shaft voltage, and They are respectively d shaft and q shaft current, For rotor speed, It is a permanent magnet flux linkage. p It is a differential operator; The transfer function of the PR controller is: (4) In the formula, It is a non-ideal resonant frequency. For the ideal resonant frequency, K p and K i The controllers represent the proportional and integral gains of the PR controller, respectively.

3. The method for re-energizing a permanent magnet synchronous motor based on zero-current control according to claim 2, characterized in that, The phrase "adjusting the electromagnetic torque of the permanent magnet synchronous motor to zero, and accurately estimating the initially estimated rotor position and speed" includes: Under the zero-current control strategy, the stator current is always equal to zero. , , , Substituting into the aforementioned formulas (1) and (3), we can obtain: (5) (6) Magnetic flux linkage and electromagnetic torque can be written in a rotating coordinate system as follows: (7) When the reference voltages output by the PR controller are respectively and Based on formula (5), the voltage expression under zero current control can be calculated as follows: (8) In the formula, for Shaft reference voltage, for Shaft reference voltage, This is a preliminary estimate of the rotor phase. This is a preliminary estimate of the rotor speed.

4. The method for re-energizing a permanent magnet synchronous motor based on zero-current control according to claim 3, wherein "adjusting the electromagnetic torque of the permanent magnet synchronous motor to zero and accurately estimating the initially estimated rotor position and speed" includes: The electromagnetic torque equation of a permanent magnet synchronous motor in a rotating coordinate system is: (12) In the formula, , They are respectively d shaft and q Axial magnetic flux, For extreme logarithms, T e Electromagnetic torque; The electromagnetic torque depends on the stator current and torque angle. δ Therefore, the equation for electromagnetic torque can also be written in the following form: (13) In the formula, I s This represents the effective value of the stator phase current. L For the effective stator lamination length, r Where is the air gap radius, B m This represents the fundamental amplitude of the permanent magnet flux linkage. N s This represents the number of turns in the phase coil; Given that the electromagnetic torque command value is zero, the torque angle is close to zero, so equation (13) can be written as: (14) In the formula, , δ The torque angle is the angle at which the observed rotor speed is greater than the actual speed. δ Greater than 0, otherwise δ Less than 0.

5. The method for re-energizing a permanent magnet synchronous motor based on zero-current control according to claim 2, characterized in that, The phrase "based on the precise estimation results of the rotor position and speed information, employing a sensorless control strategy corresponding to the speed to complete the belt-speed re-engagement of the permanent magnet synchronous motor" includes: When the precisely estimated rotational speed of the permanent magnet synchronous motor is less than or equal to a first preset rotational speed, a first sensorless control strategy is employed to complete the re-energization of the permanent magnet synchronous motor; and / or When the speed of the permanent magnet synchronous motor is more than the second preset speed, the second sensorless control strategy is adopted to complete the speed-up re-engagement of the permanent magnet synchronous motor. Wherein, the second preset speed is greater than or equal to the first preset speed.

6. The method for re-energizing a permanent magnet synchronous motor based on zero-current control according to claim 5, characterized in that, The first sensorless control strategy is a sensorless control strategy based on pulsed square wave injection; and / or The second sensorless control strategy is the sensorless control strategy of the model reference adaptive observer.

7. The method for re-energizing a permanent magnet synchronous motor based on zero-current control according to claim 6, characterized in that, The phrase "based on the precise estimation results of the rotor position and speed information, employing a sensorless control strategy corresponding to the speed to complete the belt-speed re-engagement of the permanent magnet synchronous motor" includes: When the speed of the permanent magnet synchronous motor is less than or equal to the first preset speed, a sensorless control strategy based on pulsating square wave injection is adopted. The high-frequency pulse voltage signal injected to estimate the rotor reference frame is: (27) The high-frequency induced current in a stationary coordinate system caused by the components of a high-frequency pulse voltage signal can be expressed as: (28) In the formula, For rotor position, To estimate the rotor position error, for High-frequency induced current on the shaft for High-frequency induced current in the shaft; When the speed of the permanent magnet synchronous motor is greater than the second preset speed, the speed and position of the rotor in the normal sensorless control strategy are estimated by activating the model reference adaptive observer: (29) , , , , ， ， ， ， . (30) The speed adaptation mechanism is as follows: (31)。 8. A computer-readable storage medium comprising a memory adapted to store a plurality of program codes, characterized in that, The program code is adapted to be loaded and run by a processor to perform the belt-speed re-switching method for permanent magnet synchronous motors based on zero-current control as described in any one of claims 1 to 7.

9. A computer device, the device comprising a memory and a processor, the memory being adapted to store a plurality of program codes, characterized in that, The program code is adapted to be loaded and run by the processor to perform the belt-speed re-switching method for permanent magnet synchronous motors based on zero-current control as described in any one of claims 1 to 7.

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