Method, device and equipment for determining short-circuit time of motor and medium

Abstract

The invention provides a motor short-circuit time determination method and device, equipment and a medium, and relates to the technical field of motor control. The method comprises the following steps: determining the safe short-circuit duration of the motor according to the electrical parameters of the motor; the electrical parameters at least comprise rated current; applying a zero voltage vector to the motor within the safe short circuit duration to realize three-phase short circuit, and detecting three-phase current of the motor when the short circuit is finished to obtain first sampling current; and correcting the safe short-circuit duration according to the first sampling current and the rated current to obtain a target short-circuit duration. According to the application, the safe short-circuit duration is corrected according to the sampled current after short circuit and the rated current, the target short-circuit duration is obtained, and the problem that zero voltage vector action time needs to be recalibrated for different motors can be solved.

Description

Technical Field

[0001] This invention belongs to the field of motor control technology, and particularly relates to a method, apparatus, device and medium for determining the short-circuit time of a motor. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) have shown great promise in the rail transit field due to their significant advantages such as high power density, high efficiency, and wide speed range. However, due to external environmental influences, problems frequently arise, such as the inability to lock the motor properly, leading to starting failures; abnormal shutdowns caused by increased bus voltage during startup; and even damage to internal circuit modules. Existing PMSM starting schemes typically obtain three-phase back EMF voltages by short-circuiting the motor. The current motor speed is calculated based on the detected back EMF voltages before switching to closed-loop operation mode.

[0003] However, existing solutions control the motor short-circuit time by manually setting the zero-voltage vector action time. Since different motors and speeds exhibit different current rise curves, the zero-voltage vector action time needs to be recalibrated for each motor. Summary of the Invention

[0004] This invention provides a method, apparatus, device, and medium for determining the short-circuit time of a motor, which can solve the problem of needing to recalibrate the zero-voltage vector action time for different motors.

[0005] In a first aspect, this application provides a method for determining the short-circuit time of a motor, the method comprising: The safe short-circuit duration of the motor is determined based on its electrical parameters; the electrical parameters include at least the rated current. A three-phase short circuit is achieved by applying a zero-voltage vector to the motor during the safe short circuit duration, and the three-phase current of the motor is detected at the end of the short circuit to obtain the first sampling current; The safe short-circuit duration is corrected based on the first sampled current and the rated current to obtain the target short-circuit duration.

[0006] Secondly, this application provides a device for determining the short-circuit time of a motor, the device comprising: The first duration determination module is used to determine the safe short-circuit duration of the motor based on the motor's electrical parameters; the electrical parameters include at least the rated current. The three-phase short-circuit module is used to apply a zero-voltage vector to the motor to achieve a three-phase short circuit during the safe short-circuit duration, and to detect the three-phase current of the motor at the end of the short circuit to obtain the first sampling current; The second duration determination module is used to correct the safe short-circuit duration based on the first sampled current and the rated current to obtain the target short-circuit duration.

[0007] Thirdly, this application provides an electronic device, including: a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the above-described method for determining the short-circuit time of a motor.

[0008] Fourthly, this application provides a readable storage medium that, when the instructions in the readable storage medium are executed by the processor of an electronic device, enables the electronic device to execute the above-described method for determining the short-circuit time of a motor.

[0009] Fifthly, embodiments of this application provide a computer program product, including a computer program that, when executed by a processor, implements the above-described method for determining the short-circuit time of a motor.

[0010] In summary, in this embodiment, the safe short-circuit duration is determined based on electrical parameters. Applying a zero-voltage vector to the motor within this safe short-circuit duration achieves a three-phase short circuit, preventing excessively long short-circuit times and thus avoiding damage to the motor's hardware, ensuring motor safety. Furthermore, the safe short-circuit duration is corrected based on the first sampled current and rated current after the short circuit to obtain the target short-circuit duration, i.e., the zero-voltage vector action time. Since the first sampled current differs for different motors and at different speeds, and the zero-voltage vector action time is obtained by correcting the safe short-circuit duration based on the sampled current after the short circuit, there is no need to recalibrate the zero-voltage vector action time. This simplifies the motor starting process and improves the flexibility of the motor control process. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a flowchart illustrating the steps of a method for determining the short-circuit time of a motor, as provided in an embodiment of this application.

[0013] Figure 2 This is a schematic diagram of a zero-voltage vector action front and rear bridge circuit provided in an embodiment of this application.

[0014] Figure 3 This is a flowchart illustrating the specific steps of a method for determining the short-circuit time of a motor, as provided in an embodiment of this application.

[0015] Figure 4 This is a schematic diagram illustrating the relationship between a short-circuit current vector and the initial position of a rotor, provided in an embodiment of this application.

[0016] Figure 5 This is a flowchart of another method for determining the short-circuit time of a motor provided in an embodiment of this application.

[0017] Figure 6 This is a structural diagram of a device for determining the short-circuit time of a motor provided in an embodiment of this application.

[0018] Figure 7 This is a structural diagram of an electronic device provided in an embodiment of this application.

[0019] Figure 8 This is a structural diagram of another electronic device provided in an embodiment of this application. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0022] In the description of this disclosure, unless otherwise stated, "multiple" means two or more, and other quantifiers are similar; "at least one," "one or more," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one 'a' can represent any number of 'a's; as another example, one or more of a, b, and c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple; "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, and B alone, where A and B can be singular or plural. The character " / " indicates that the preceding and following related objects are in an "or" relationship.

[0023] Although operations or steps are described in a specific order in the accompanying drawings in the embodiments of this disclosure, it should not be construed as requiring these operations or steps to be performed in the specific order or serial order shown, or requiring all of the shown operations or steps to be performed to obtain the desired result. In the embodiments of this disclosure, these operations or steps may be performed serially; they may be performed in parallel; or a portion of these operations or steps may be performed.

[0024] A permanent magnet synchronous motor (PMSM) is a type of motor that uses permanent magnets for excitation, and the rotor speed is synchronized with the rotational magnetic field speed of the stator. It is a core component in fields such as new energy vehicles and industrial servo systems. Composed of an iron core and three-phase windings, it generates a rotating magnetic field when AC current is applied. Permanent magnets (such as neodymium iron boron) are installed on the rotor, generating a magnetic field without additional power. The rotating magnetic field of the stator drives the magnetic field of the rotor's permanent magnets, ensuring that the rotor speed is exactly the same as the stator's magnetic field speed, eliminating any speed difference. PMSMs do not require excitation current for the rotor, reducing energy loss and typically resulting in higher operating efficiency than asynchronous motors. The high magnetic field strength of permanent magnets allows for greater power output in a smaller size and weight. Stable and precise speed control makes them ideal for applications requiring high speed and position precision, such as robots and precision machine tools. However, they require a high-precision controller (such as a frequency converter) for operation, and permanent magnets are relatively expensive; performance may be affected by high-temperature environments.

[0025] In applications such as wind power generation, permanent magnet synchronous motors (PMSMs) can be categorized into tailwind and headwind starts based on the wind direction during startup. When the wind blows from behind the blades (tailwind), the wind force drives the blades to rotate, generating auxiliary torque. This reduces the starting current and minimum torque required for the motor, allowing the controller to reduce the initial boost of the inverter's output frequency, thus achieving a smooth start. In headwinds, the wind blows from in front of the blades, generating resistance torque and increasing the starting load. The motor requires higher torque to generate sufficient electromagnetic torque to overcome this resistance. The controller must dynamically adjust the inverter's frequency and voltage to prevent rotor synchronization issues. In some sensorless headwind start-up schemes, the motor first enters a headwind reverse speed closed-loop control, setting a preset current threshold. Once the speed stabilizes, it enters a current closed-loop control. When the output current reaches the preset current threshold, the reduction controller adjusts the motor speed until it stops. After a stable stop, the motor restarts.

[0026] In scenarios such as sensorless start-up, initial state identification, or bootstrap capacitor charging of permanent magnet synchronous motors, short-circuit current is needed to obtain motor state information. If the short-circuit time is too short, the current will not reach a sufficient amplitude, which will affect the sampling signal-to-noise ratio. If the short-circuit time is too long, the current may enter the nonlinear saturation region. Therefore, calculating the safe short-circuit duration can prevent excessive current from damaging devices or causing the motor to overheat while obtaining state information.

[0027] Existing solutions control motor short-circuit time by manually setting the zero-voltage vector action time. The zero-voltage vector action time refers to the duration for which a zero-voltage vector is applied in the three-phase bridge inverter driving the motor, causing a short circuit in the three-phase windings of the motor—the short-circuit duration mentioned in the embodiments of this application. Because different motors and speeds exhibit different current rise curves, the zero-voltage vector action time needs to be recalibrated for different motors. Therefore, it is difficult to meet the requirements for algorithm flexibility.

[0028] To address the aforementioned technical problems, embodiments of the present invention provide a method, apparatus, device, and medium for determining the short-circuit time of a motor. The flow rate limiting method provided in this application will be described in detail below with reference to the accompanying drawings and through specific embodiments and application scenarios.

[0029] Figure 1 This is a flowchart illustrating the steps of a method for determining the short-circuit time of a motor, as provided in an embodiment of this application. Figure 1 As shown, the method may include the following steps.

[0030] Step 101: Determine the safe short-circuit duration of the motor based on its electrical parameters.

[0031] In this embodiment, the electrical parameters include at least the rated current. The rated current is the maximum current the motor can withstand continuously.

[0032] In some embodiments, the electrical parameters further include: quadrature-axis inductance, direct-axis inductance, rotor flux linkage, and electrical angular velocity corresponding to the rated speed. The quadrature-axis (q-axis) is a spatial axis perpendicular to the axis of the rotor permanent magnet poles; the direct-axis (d-axis) is a spatial axis coinciding with the axis of the rotor permanent magnet poles; the rotor flux linkage is the total air gap flux generated by the permanent magnets on the motor rotor, reflecting the strength of the permanent magnet's magnetic field; the rated speed is the maximum mechanical speed specified in the motor design for long-term stable operation; and the electrical angular velocity is the rotational speed converted from mechanical speed to electrical angle.

[0033] In some embodiments, step 101 includes: inputting the rated current, quadrature shaft inductance, rotor flux linkage, and electric angular velocity corresponding to the rated speed into a preset safe short-circuit duration calculation formula to obtain the safe short-circuit duration of the motor.

[0034] Step 102: Apply a zero-voltage vector to the motor to achieve a three-phase short circuit within the safe short circuit duration, and detect the three-phase current of the motor at the end of the short circuit to obtain the first sampled current.

[0035] In this embodiment of the application, applying a zero voltage vector to the motor to achieve a three-phase short circuit can be achieved by applying a zero voltage vector to turn on all the switching transistors of the upper or lower bridge arm of the motor, so that the three-phase windings of the motor are short-circuited and the current can only circulate internally.

[0036] For example, see Figure 2 . Figure 2 This demonstrates the switching state changes of a three-phase bridge inverter before and after zero-voltage vector operation. Each phase of the three phases inside the permanent magnet synchronous motor is equivalent to a series branch of stator resistance and stator inductance, resulting in a three-phase bridge circuit. It represents the DC bus voltage, and C is the capacitor. , , It is a three-phase upper bridge arm. , , This is the lower arm of the three-phase bridge, where Rs and Ls are the stator resistance and stator inductance, respectively. Figure 2 It can be seen that after the vector voltage is applied, Figure 2 The lower bridge arm , , Conduction occurs, resulting in a three-phase short circuit.

[0037] Understandably, compared to actively injected voltage vector, the inverter in zero-voltage vector mode does not inject external voltage into the motor; the short-circuit current is determined solely by the back electromotive force of the rotor permanent magnets and the inductance and resistance characteristics of the windings. This passive short-circuit current signal can more accurately reflect the motor's rotational state. Furthermore, the current reaches its peak increase precisely at the end of the short circuit, resulting in the clearest signal that reflects the true short-circuit effect. Measuring the three-phase current at this point improves the accuracy of the first sampled current.

[0038] Step 103: Correct the safe short-circuit duration based on the first sampled current and the rated current to obtain the target short-circuit duration.

[0039] Understandably, the safe short-circuit duration is a theoretical safety value calculated based on electrical parameters such as the motor's rated current. This ensures the short-circuit current does not exceed the rated current, protecting the hardware. However, in practical applications, factors such as headwinds, power fluctuations, etc., can cause the theoretical safety value to lead to an excessively high or low current when short-circuiting the motor, potentially compromising motor safety. By dynamically adjusting the safe short-circuit duration using the first sampled current obtained in practice, we can ensure that the current signal from subsequent short-circuit sampling is sufficiently clear, facilitating the calculation of the initial speed and position, while also ensuring it does not exceed the motor's hardware safety threshold, thus optimizing the motor starting process.

[0040] In the embodiments of this application, a correction coefficient greater than 1 indicates an extension of the short-circuit duration, and a correction coefficient less than 1 indicates a shortening of the short-circuit duration.

[0041] In some embodiments, the effective value of the first sampled current is calculated; the target current is obtained based on the rated current and a preset weighting coefficient; a correction coefficient is obtained based on the ratio of the target current to the first sampled current; and the target short-circuit duration is obtained based on the product of the correction coefficient and the safe short-circuit duration.

[0042] In summary, in this embodiment, the safe short-circuit duration is determined based on electrical parameters. Within the safe short-circuit duration, a zero-voltage vector is applied to the motor to achieve a three-phase short circuit. This avoids excessively long short-circuit times, thereby preventing damage to the motor hardware and ensuring motor safety. Furthermore, the safe short-circuit duration is corrected based on the sampled current and rated current after the short circuit to obtain the target short-circuit duration. This eliminates the need to recalibrate the zero-voltage vector action time, simplifying the motor startup process and improving the flexibility of the motor control process.

[0043] Figure 3 This is a flowchart illustrating the specific steps of a method for determining the short-circuit time of a motor, as provided in an embodiment of this application. Figure 3 As shown, the method may include the following steps.

[0044] Step 201: Determine the safe short-circuit duration of the motor based on its electrical parameters.

[0045] The method for this step has been explained in step 101 above, and will not be repeated here.

[0046] In some embodiments, before step 201, the method for determining the short-circuit time of the motor may further include: initializing the motor in response to power-on; and, in response to a motor start command, pre-setting a charging time for charging the bootstrap capacitor using the short-circuit current generated by the motor rotation in each control cycle.

[0047] In one possible implementation, initializing the motor in response to power-on may include: configuring the analog-to-digital converter (ADC) trigger mode to software trigger mode and performing ADC calibration in response to motor power-on, and shutting down all arms of the three-phase bridge circuit. For example, a three-phase bridge circuit such as... Figure 2 As shown.

[0048] In one possible implementation, a preset charging time for charging the bootstrap capacitor using the short-circuit current generated by the motor rotation is included in each control cycle. This can include: in each pulse width modulation (PWM) control cycle, simultaneously switching the three lower bridge arms on and off, using the short-circuit current generated by the motor rotation to charge the bootstrap capacitor until the preset charging time has elapsed. For example, the PWM control cycle is Ts = 1 second (s), and the preset charging time is 200 milliseconds (ms).

[0049] In some embodiments, step 201 includes sub-steps 2011 to 2013.

[0050] Step 2011: Calculate the product of the rated current and the quadrature-axis inductance to obtain the first product; Step 2012: Calculate the product of the electric angular velocity corresponding to the rated speed and the rotor flux linkage to obtain the second product; Step 2013: Calculate the ratio of the first product to the second product to obtain the safe short-circuit duration.

[0051] In this embodiment, the quadrature-axis inductance refers to the ability of the motor windings to impede current flow in the quadrature-axis (q-axis) direction. The first product is proportional to the safe short-circuit duration. The first product characterizes the total allowable current increase of the motor; the larger the quadrature-axis inductance, the slower the current increase and the longer the allowable short-circuit time.

[0052] In this embodiment, the flux linkage determines the increase rate of the short-circuit current. The back electromotive force, short-circuit current, and torque of the motor are all related to the electrical angular velocity, which is closer to the electrical characteristics of the motor than the mechanical rotational speed.

[0053] In this embodiment, the second product is inversely proportional to the safe short-circuit duration. The second product represents the driving force for the increase of the motor short-circuit current. The larger the product of the electrical angular velocity corresponding to the rated speed and the rotor flux linkage, the stronger the back electromotive force, the faster the short-circuit current increases, and the shorter the allowable short-circuit time.

[0054] It is understandable that the rated speed is the reference speed for the long-term stable operation of the motor. The safety time calculated based on the electrical angular velocity corresponding to the rated speed can ensure that the short-circuit current is still within the safe range when the motor is close to the rated operating state. If an electrical angular velocity other than the rated speed is selected, the safety time will be too large. When the actual speed of the motor is close to the rated value, the short-circuit current will quickly exceed the rated current due to the increase in speed, causing safety risks.

[0055] In one possible implementation, the safe short-circuit duration is calculated as follows: (1) In formula (1), It is the electrical angular velocity corresponding to the rated speed. It is the rated current. It is a q-axis inductor. It is rotor flux linkage. It is the safe short-circuit duration.

[0056] The above technical solution determines the safe short-circuit duration of the motor based on the rated current, quadrature shaft inductance, rotor flux linkage, and the electrical angular velocity corresponding to the rated speed. Since the rated current is the maximum current that the motor can withstand for a long time, and the rated speed is the highest mechanical speed specified in the motor design for long-term stable operation, the calculated safe short-circuit duration can avoid excessively long short-circuit times, thereby preventing damage to the motor hardware and ensuring the safety of the motor.

[0057] Step 202: Apply a zero-voltage vector to the motor to achieve a three-phase short circuit within the safe short circuit duration, and detect the three-phase current of the motor at the end of the short circuit to obtain the first sampled current.

[0058] The method for this step has been explained in step 102 above, and will not be repeated here.

[0059] Step 203: The first sampling current and the rated current are used to correct the safe short-circuit duration to obtain the target short-circuit duration.

[0060] The method for this step has been explained in step 103 above, and will not be repeated here.

[0061] In some embodiments, electrical step 203 includes sub-steps 2031 to 2034.

[0062] Sub-step 2031: Calculate the root mean square of the first sampling current to obtain the effective value of the first sampling current; Sub-step 2032: Determine the target value of the short-circuit current based on the preset weighting coefficients and rated current; Sub-step 2033: Calculate the ratio of the target value of the short-circuit current to the effective value of the first sampled current to obtain the correction coefficient; Sub-step 2034: Calculate the product of the correction factor and the safe short-circuit duration to obtain the target short-circuit duration.

[0063] In this embodiment, since the short-circuit current is a transient current that increases linearly with time, directly using the instantaneous value would be affected by the slight deviation in the sampling time. Calculating the effective value of the first sampled current, specifically the root mean square (RMS) value, can integrate the current characteristics of the short-circuit process, eliminate the interference of instantaneous current fluctuations, and more accurately reflect the actual intensity of the short-circuit current. In one possible implementation, the root mean square of the first sampled current is calculated using a mean square error formula, for example, as shown below: (2) In formula (2), This is the effective value of the three-phase current. , , These are the sampled three-phase short-circuit currents, representing the A, B, and C phase currents collected by the sensors, respectively.

[0064] In this embodiment, a preset weighting coefficient is used to adjust the target intensity of the short-circuit current, ensuring that it does not exceed the hardware safety limit while also guaranteeing that the current signal is sufficiently clear. The weighting coefficient is a constant greater than 0 and less than 1.

[0065] In practical applications, the weighting system can be calibrated based on a large number of experiments. For example, the weighting coefficient is 0.2.

[0066] In one possible implementation, ,in, This is the target value for the short-circuit current. That is the rated current.

[0067] In this embodiment, the correction coefficient is the ratio of the target value of the short-circuit current to the effective value of the first sampled current. This eliminates the need to remeasure the motor parameters, offsets the short-circuit duration deviation caused by motor parameter deviations, headwind and tailwind interference, etc., and improves the robustness of the solution.

[0068] In one possible implementation, the target short-circuit duration is calculated. as follows: (3) In formula (3), This is the effective value of the three-phase current. This is the target value for the short-circuit current. This represents the correction factor.

[0069] The above technical solution calculates the effective value of the first sampled current, which can eliminate instantaneous current fluctuations. The target value of the short-circuit current is calculated using a weighting coefficient. Since the target value of the short-circuit current is less than the rated current, a safety threshold, and the weighting coefficient can adjust the intensity of the short-circuit current, compared to directly using the rated current as the target value, it can prevent current over-limits caused by operating condition fluctuations and ensure that the current signal meets the identification requirements. A correction coefficient is obtained based on the ratio of the target current value to the effective value of the first sampled current. This correction coefficient can offset the short-circuit duration deviation caused by motor parameter deviations, headwind and tailwind interference, etc., thereby improving the accuracy of the target short-circuit duration.

[0070] Step 204: Perform multiple three-phase short circuits on the motor using the target short circuit duration and sample the current to obtain multiple sampled currents.

[0071] In some embodiments, step 204 includes sub-steps 2041 to 2045.

[0072] Sub-step 2041: Wait for the current to decay until the waiting time reaches the first decay time, and apply a zero voltage vector to the motor again within the target short circuit time to achieve a three-phase short circuit; Sub-step 2042: Detect the three-phase current of the motor at the end of the second short circuit to obtain the second sampled current; Sub-step 2043: Calculate the electrical angular velocity based on the second sampling current, and calculate the second decay time based on the electrical angular velocity and the preset motor rotation angle; Sub-step 2044: Wait for the current to decay until the waiting time reaches the second decay time, and apply zero voltage vector again within the target short circuit time to achieve three-phase short circuit; Sub-step 2045: After the third short circuit ends, detect the three-phase current of the motor to obtain the third sampling current.

[0073] In this embodiment of the application, the first attenuation duration is twice the safe short-circuit duration.

[0074] It should be noted that after a short circuit ends, residual current will remain in the motor windings. If a short circuit occurs again before the current has completely decayed, the two currents will overlap, leading to errors in the current sampled in the second sampling. Since the current decay rate is related to the rate of increase during a short circuit, setting the first decay time to twice the safe short circuit time ensures that the current decays to near zero, avoiding interference with the next sampling.

[0075] For example, the safe short-circuit duration is 0.02 seconds, and the first decay duration is 0.04 seconds.

[0076] In this embodiment of the application, the motor rotation angle can be set according to actual needs. For example, the motor rotation angle is 2 / 3π or 90 degrees electrical angle.

[0077] It's important to note that sufficient time needs to be allowed between the second and third short circuits for the motor to rotate a fixed angle. This ensures a significant change in the vector angle of the current during the two short circuits, allowing for accurate determination of the rotational direction. If the decay time is set arbitrarily, the motor's rotation angle will be uncertain, potentially resulting in a small vector angle difference and low directional accuracy.

[0078] In one possible implementation, calculating the electrical angular velocity based on the second sampled current includes: calculating the root mean square of the second sampled current to obtain the effective value of the second sampled current; calculating the product of the quadrature-axis inductance and the effective value of the second sampled current; and dividing the product of the quadrature-axis inductance and the effective value of the second sampled current by a second product to obtain the electrical angular velocity corresponding to the second sampled current.

[0079] In one possible implementation, the electrical angular velocity corresponding to the second sampled current is calculated. As shown below: (4) In formula (5), This represents the electrical angular velocity corresponding to the second sampled current. This represents the effective value of the second sampled current.

[0080] In one possible implementation, the second decay duration is the ratio of the motor rotation angle to the electrical angular velocity corresponding to the second sampling current.

[0081] For example, calculate the second decay time. The formula is as follows: (5) In formula (5), .

[0082] In this embodiment, the second sampling current and the third sampling current correspond to two current signals after the motor has rotated a fixed angle. By comparing the vector angles of the second sampling current and the third sampling current, it is possible to determine whether the motor is rotating forward or backward, obtain the rotation direction, and then combine the third sampling current to calculate the initial position, thereby enabling sensorless start-up state identification.

[0083] The above technical solution firstly ensures that the residual current from the previous short circuit is completely attenuated by waiting for twice the safe short circuit duration, thus avoiding the impact of current superposition on the accuracy of the second sampling. Secondly, the second attenuation duration is calculated based on the electrical angular velocity to prevent the motor from rotating beyond the preset angle when the speed is high and insufficient when the speed is low, thus ensuring a stable angle difference. The same short circuit duration and sampling timing make the amplitude and phase characteristics of the three sampled currents comparable, providing accurate data for the subsequent state identification process.

[0084] Step 205: Determine the initial speed and initial position of the motor based on the vector characteristics and electrical parameters of multiple sampled currents.

[0085] In the embodiments of this application, the vector features include at least the vector angle and the electric angular velocity.

[0086] Among them, the vector angle of the sampling current represents the phase direction of the three-phase short-circuit current of the motor in the spatial coordinate system. The vector angle of the sampling current can be the angle between the current vector and the reference axis; the electrical angular velocity is the rotational speed that converts the mechanical speed into electrical angles.

[0087] In some embodiments, step 205 includes sub-steps 2051 to 2053.

[0088] Sub-step 2051: Determine the initial rotational speed based on the third sampling current, quadrature-axis inductance, and rotor flux linkage.

[0089] Sub-step 2052: Determine the direction of the initial rotational speed based on the vector angle difference between the second and third sampling currents.

[0090] Sub-step 2053: Determine the initial position of the motor based on the vector angle of the third sampled current, electrical parameters, the direct axis angle of the third sampled current, and the target short-circuit duration.

[0091] In this embodiment, the direct axis angle is the deviation angle of the vector angle of the third sampling current relative to the direct axis.

[0092] In this embodiment, a larger third sampling current indicates a stronger back electromotive force drive and a higher rotational speed; a larger quadrature-axis inductance indicates a slower current increase or a stronger magnetic field, resulting in a lower rotational speed for the same current. Therefore, the speed can be quantified by utilizing the amplitude of the third sampling current, the quadrature-axis inductance, and the rotor flux linkage.

[0093] In this embodiment, since the vector angle of the sampled current represents the phase direction of the three-phase short-circuit current of the motor in the spatial coordinate system, the direction of the initial speed is obtained by judging whether the motor is rotating forward or backward by the trend of the vector angle change corresponding to the sampled current of the two short circuits.

[0094] In one possible implementation, the vector angle difference between the second sampling current and the third sampling current can be obtained as follows: calculate the first vector angle corresponding to the second sampling current according to a preset vector angle calculation formula; calculate the second vector angle corresponding to the third sampling current according to the same formula; and use the angle difference between the second vector angle and the first vector angle as the vector angle difference between the second sampling current and the third sampling current.

[0095] For example, the preset formula for calculating the vector angle is shown below: (6) In formula (6), Represents a vector angle. , , These are the sampled three-phase short-circuit currents, representing the A, B, and C phase currents collected by the sensors, respectively.

[0096] In one possible implementation, the first vector angle corresponding to the second sampled current is calculated. The second vector angle corresponding to the third sampling current The vector angle difference between the second and third sampling currents .

[0097] In this embodiment, the electrical parameters also include direct-axis inductance. The direct axis (d-axis) is a spatial axis that coincides with the axis of the rotor permanent magnet's magnetic poles.

[0098] In this embodiment, the vector of the third sampling current reflects the phase of the third sampling current in space. The true position of the rotor is obtained by correcting the deviation between the current vector angle and the rotor magnetic pole axis (direct axis).

[0099] For example, see Figure 4 , Figure 4 The relationship between the short-circuit current vector and the initial rotor position is shown. It is the short-circuit current vector in Angles of the coordinate system It is the angle of the short-circuit current vector in the dq coordinate system. This is the initial position of the rotor. The dq coordinate system is a stationary coordinate system, with the α-axis coinciding with the axis of the motor's A-phase winding, and the β-axis perpendicular to the α-axis. The dq coordinate system is a rotating coordinate system that rotates synchronously with the rotor's permanent magnets, with the d-axis (direct axis) coinciding with the rotor's magnetic pole axis, and the q-axis (quadrature axis) perpendicular to the d-axis.

[0100] The above technical solution eliminates the need for a physical speed sensor. It calculates the initial motor speed using only the effective value of the short-circuit current and known motor parameters, which is beneficial for subsequent motor speed direction determination and starting strategy selection. Secondly, the initial speed direction is determined based on the vector angle difference between the second and third sampled currents. Since the direction is obtained using the vector angle difference between the two sampled currents, the influence of current amplitude fluctuations on the initial speed direction is avoided, resulting in strong anti-interference capability. Finally, a direct-axis angle correction is used to calculate the initial position, reducing position deviation and improving the accuracy of the initial position.

[0101] In some embodiments, sub-step 2053 includes sub-steps 20531 to 20533.

[0102] Sub-step 20531: Calculate the product of the quadrature-axis inductance and the effective value of the third sampling circuit to obtain the third product; Sub-step 20532: Calculate the product of the rotor flux linkage and the target short-circuit duration to obtain the fourth product; Sub-step 20533: Obtain the initial rotational speed based on the ratio of the third product to the fourth product.

[0103] In this embodiment, the product of the quadrature axis inductance and the effective value of the third sampling circuit is proportional to the initial rotational speed, and the product of the rotor flux linkage and the target short-circuit duration is inversely proportional to the initial rotational speed.

[0104] In this embodiment, the initial rotational speed is also the electrical angular velocity corresponding to the third sampling current.

[0105] In one possible implementation, the initial rotational speed is... The calculation method is as follows: (7) In formula (7), It is the electrical angular velocity corresponding to the rated speed. It is the rated current. It is a q-axis inductor. It is the effective value of the third sampling circuit. It is rotor flux linkage. The purpose is the short circuit duration.

[0106] The above technical solution eliminates the need for a physical speed sensor. It calculates the initial speed of the motor using only the effective value of the short-circuit current and known motor parameters, which is beneficial for subsequent motor speed direction determination and starting strategy selection.

[0107] In some embodiments, sub-step 2052 may include sub-steps 20521 to 20523.

[0108] Sub-step 20521: Perform angle transformation on the vector angle difference to obtain the standard angle within the preset standard range; Sub-step 20522: When the standard angle is greater than or equal to zero, determine the direction of the initial rotational speed as the positive direction; Sub-step 20523: When the standard angle is less than zero, determine the direction of the initial rotational speed as negative.

[0109] In the embodiments of this application, the preset standard range is greater than -π and less than or equal to π.

[0110] In one possible implementation, the vector angle difference is transformed according to the angle unit into which it falls, to obtain a standard angle within a preset standard range.

[0111] In the embodiments of this application, the standard angle is the equivalent angle of the vector angle difference.

[0112] Understandably, the original calculated result of the vector angle difference between the second and third sampled currents may exceed the range of (-π, π], leading to confusion in direction determination. For example, if the motor rotates forward for multiple revolutions, the angle difference may be 450° (actually equivalent to 90°); if the motor rotates backward for multiple revolutions, the angle difference may be 450° (actually equivalent to -90°). Angle transformation can map the original angle difference to a preset standard range of (-π, π] by subtracting or adding π, eliminating the angle redundancy caused by multiple revolutions and preserving the true direction characteristics.

[0113] For example, for vector angle difference Perform angle transformation to obtain the standard angle within the preset standard range. As shown below: (8) In this embodiment of the application, when the standard angle is greater than or equal to zero, the vector angle corresponding to the third sampling current is explained. The vector angle is greater than or equal to the second sampling current. In other words, the current vector rotates counterclockwise with time, which is consistent with the forward rotation direction designed for the motor. Therefore, the initial speed direction is determined to be the positive direction.

[0114] In this embodiment, when the standard angle is less than zero, the vector angle corresponding to the third sampling current is explained. The vector angle less than the second sampling current In other words, the current vector rotates clockwise with time, which is opposite to the positive rotation direction designed for the motor. Therefore, the initial speed direction is determined to be negative.

[0115] In one possible implementation, the standard angle is obtained using the above formula (8), and then the initial rotational speed is obtained by combining it with formula (7). The initial rotational speed ω can be obtained as follows: (9) The above technical solution transforms the vector angle difference into a standard angle, eliminating redundant information in the vector angle difference and ensuring accurate determination of the actual rotation direction even if the motor rotates multiple times or the angle difference is too large. Furthermore, the direction of rotation is distinguished based on the positive or negative value of the standard angle. The process is simple and clear, improving the efficiency of direction identification during sensorless startup.

[0116] In some embodiments, sub-step 2053 may include sub-steps 20531 to 20534.

[0117] Sub-step 20531: Perform a Clarke transform on the instantaneous value of the third sampled current to obtain the third sampled current at... Current components in the coordinate system; Sub-step 20532: Calculate the vector angle of the third sampled current based on the current components; Sub-step 20533: Calculate the direct-axis angle based on the direct-axis inductance, quadrature-axis inductance, target short-circuit duration, and the electrical angular velocity corresponding to the third sampling current; Sub-step 20534: Subtract the vector angle of the third sampled current from the direct axis angle to obtain the initial position.

[0118] In the embodiments of this application, the time-varying three-phase alternating current is converted into a DC component in a stationary coordinate system, which is beneficial for quantifying the spatial phase characteristics of the current.

[0119] In one possible implementation, the second vector angle corresponding to the third sampling current is calculated according to a preset vector angle calculation formula. For example, the preset formula for calculating the vector angle is the formula (6) above.

[0120] In this embodiment, the direct axis angle is the deviation angle of the vector angle of the third sampling current relative to the direct axis (d-axis).

[0121] It should be noted that, due to the salient pole characteristics of the motor, the direct-axis inductance is different from the quadrature-axis inductance. The direction of the current vector will not completely coincide with the actual position of the rotor (d-axis direction). The direct-axis angle is used to quantify and correct the deviation between the direction of the current vector and the actual position of the rotor.

[0122] In one possible implementation, the direct axis angle is calculated. As shown below: (10) In formula (10), It represents the d-axis inductance, and |ω| represents the electrical angular velocity corresponding to the third sampled current, i.e., the magnitude of the initial rotational speed. It is the target short-circuit duration.

[0123] In one possible implementation, the initial position .

[0124] The above technical solution calculates the direct-axis angle based on motor parameters such as direct-axis inductance, quadrature-axis inductance, target short-circuit duration, and electrical angular velocity corresponding to the third sampling current. The vector angle of the third sampling current is then corrected using the direct-axis angle to obtain the initial position of the rotor. This ensures that the initial position of the rotor can be accurately located without physical sensors, providing a foundation for subsequent motor start-up control.

[0125] Step 206: Determine the motor start-up control strategy based on the initial speed and initial position of the motor.

[0126] In the embodiments of this application, the starting control strategy of the motor includes starting with the wind or starting against the wind.

[0127] In some embodiments, a motor start-up control strategy is determined based on the motor's initial speed, initial position, and a preset speed threshold.

[0128] The above technical solution involves performing multiple three-phase short circuits on the motor and sampling the current for a target short circuit duration. Multiple sampled currents are obtained, and the initial state is identified based on these sampled currents and electrical parameters. This allows for the determination of the motor's initial speed and initial position, as well as the determination of the motor's starting control strategy. Without the need for a physical speed sensor, sensorless motor starting can be achieved solely through the sampled currents obtained from multiple short circuits and the known electrical parameters, thus improving the control efficiency of motor starting.

[0129] In some embodiments, step 206 may include sub-steps 2061 to 2062.

[0130] Sub-step 2061: When the initial speed of the motor is less than or equal to the preset speed threshold, determine the starting control strategy, including braking, recharging, and starting after static positioning; Sub-step 2062: When the initial speed of the motor is greater than the speed threshold, determine the start-up control strategy, including setting the initial speed and initial position to the initial values ​​of the sensorless state observer, and executing the speed-current dual closed-loop operation strategy.

[0131] In this embodiment, the preset speed threshold is the critical speed value at which the motor's operating state transitions from open-loop to closed-loop. In one possible implementation, a preset rotational speed threshold is obtained based on the convergence of the observer.

[0132] In this embodiment of the application, braking can be achieved by injecting a braking current into the motor that is opposite to the direction of rotation, thereby offsetting inertia through electromagnetic torque and reducing the speed to 0.

[0133] In this embodiment, recharging can be achieved by injecting a short-time DC current into the motor windings via an inverter, utilizing the winding inductance to store energy, providing a stable magnetic field foundation for subsequent static positioning, and ensuring stable current signals during positioning.

[0134] In the embodiments of this application, static positioning followed by starting can be achieved by injecting current into the windings of a specific phase according to the initial position of the motor, so that the rotor magnetic poles (d-axis) are precisely aligned with the target angle (such as the α-axis) to complete the static positioning; after positioning, the torque current is gradually increased to smoothly transition from low speed to closed-loop control, avoiding starting shock.

[0135] It should be noted that the initial speed of the motor is less than or equal to the preset speed threshold. In certain situations, the motor may be in a low-speed reverse rotation or completely stationary state under headwind conditions. In this case, the back electromotive force is weak, and direct closed-loop control is prone to losing synchronization, requiring state adjustment first. Because the motor speed is too low, the short-circuit current is very small, and direct braking will not cause overcurrent. However, the low initial motor speed may prevent direct motor start-up, and the low signal-to-noise ratio leads to a large error in state estimation. Therefore, all lower bridge arms are opened to brake the motor, and then the bootstrap capacitor is recharged by injecting voltage. After static positioning, the motor is started.

[0136] In this embodiment, the speed-current dual closed-loop operation strategy is used to achieve closed-loop control of speed and current using proportional-integral regulators.

[0137] In one possible implementation, the speed-current dual closed-loop operation strategy includes: controlling the d-axis and q-axis currents through a proportional-integral (PI) regulator to enable the actual current to quickly track the given current and ensure stable torque output; and processing the difference between the target speed and the actual speed estimated by the observer through the PI regulator and outputting it as the given value of the q-axis current to achieve precise speed regulation.

[0138] It should be noted that if the initial speed of the motor is greater than the speed threshold, it means that the motor has been blown by the wind, the back electromotive force is strong, the signal-to-noise ratio of the current signal is high, and it can directly enter closed-loop control. The initial speed and initial position obtained in the previous steps are used as the initial input values ​​of the sensorless state observer.

[0139] Through the above technical solution, different starting strategies are adopted according to the magnitude of the initial speed. When the initial speed is less than or equal to the preset speed threshold, braking operation is performed to eliminate reverse speed, recharging solves the problem of low signal-to-noise ratio of current signal, and static positioning ensures that the rotor magnetic poles are precisely aligned with the target angle to avoid starting step loss due to initial position deviation. When the initial speed is greater than the speed threshold, the speed-current dual closed-loop operation strategy is used to quickly respond to speed commands and improve the efficiency of motor starting.

[0140] In summary, in this embodiment, firstly, a weighted coefficient is used to calculate the target value of the short-circuit current. Based on the ratio of the target current value to the effective value of the first sampled current, a correction coefficient is obtained, which reduces errors and improves the accuracy of the target short-circuit duration. Secondly, sampling the same short-circuit duration and sampling timing ensures the comparability of the amplitude and phase characteristics of the three sampled currents, providing accurate data for subsequent state identification processes. Thirdly, without the need for a physical speed sensor, the initial speed, direction, and initial position of the motor are calculated solely based on the effective value of the short-circuit current and known motor parameters, providing a foundation for subsequent motor start-up control. Finally, different start-up strategies are adopted based on the initial speed. When the initial speed is less than or equal to a preset speed threshold, a braking operation is performed to eliminate reverse speed, recharging addresses the low signal-to-noise ratio of the current signal, and static positioning ensures precise alignment of the rotor magnetic poles with the target angle, avoiding start-up step loss due to initial position deviation. When the initial speed is greater than the speed threshold, a speed-current dual closed-loop operation strategy is used to quickly respond to speed commands, improving motor start-up efficiency.

[0141] Figure 5 This is a flowchart illustrating the steps of another method for determining the short-circuit time of a motor provided in an embodiment of this application, as follows: Figure 5 As shown, the method may include the following steps.

[0142] Step 301: Initialize the motor after powering on.

[0143] Step 302: Determine if a startup command has been received. If yes, proceed to step 303; otherwise, the process ends.

[0144] Step 303: Charge the bootstrap capacitor using the short-circuit current.

[0145] Step 304: Calculate the duration of the safety circuit based on the motor's electrical parameters.

[0146] Step 305: Apply the first zero voltage vector and sample the first current.

[0147] Step 306: Calculate the target short-circuit duration based on the first sampled current and the target current.

[0148] Step 307: Wait for the current to decay.

[0149] Step 308: Apply a second zero-voltage vector and sample to obtain the second sampled current.

[0150] Step 309: Wait for the current to decay.

[0151] Step 310: Apply the third zero-voltage vector and sample the third sampling current.

[0152] Step 311: Estimate the initial position and initial speed of the motor.

[0153] Step 312: Determine if the rotational speed is greater than the preset rotational speed threshold. If yes, proceed to step 313; otherwise, proceed to step 314.

[0154] Step 313: Set the initial values ​​of the observer and execute the dual closed-loop operation strategy.

[0155] Step 314: Brake, charge using voltage injection method, and start after static positioning.

[0156] In summary, in this embodiment, the zero-voltage vector action time is automatically configured according to the motor parameters. The entire start-up process with and against the wind does not require any parameter calibration, reducing human intervention, improving the flexibility and reliability of the algorithm, and preventing problems such as large calculation errors or overcurrent caused by short circuit time that is too short or too long.

[0157] Figure 6 This is a block diagram of a device for determining the short-circuit time of a motor, as provided in an embodiment of this application. Figure 6 As shown, the device 400 for determining the short-circuit time of the motor includes the following modules.

[0158] The first duration determination module 401 is used to determine the safe short-circuit duration of the motor based on the motor's electrical parameters; the electrical parameters include at least the rated current. The three-phase short-circuit module 402 is used to apply a zero-voltage vector to the motor to achieve a three-phase short circuit during the safe short-circuit duration, and to detect the three-phase current of the motor at the end of the short circuit to obtain the first sampling current. The second duration determination module 403 is used to correct the safe short-circuit duration based on the first sampled current and the rated current to obtain the target short-circuit duration.

[0159] Optionally, the electrical parameters also include quadrature-axis inductance, rotor flux linkage, and electrical angular velocity corresponding to the rated speed. The first duration determination module 401 includes: The first product calculation submodule is used to calculate the product of the rated current and the quadrature axis inductance to obtain the first product; The second product calculation submodule is used to calculate the product of the electric angular velocity corresponding to the rated speed and the rotor flux linkage to obtain the second product; The first duration calculation submodule is used to calculate the ratio of the first product to the second product to obtain the safe short-circuit duration.

[0160] Optionally, the second duration determination module 403 includes: The current RMS value calculation submodule is used to calculate the root mean square of the first sampled current to obtain the RMS value of the first sampled current; The target current calculation submodule is used to determine the target value of the short-circuit current based on the preset weighting coefficients and the rated current. The first coefficient calculation submodule is used to calculate the ratio of the short-circuit current target value to the effective value of the first sampled current to obtain the correction coefficient; The target short-circuit duration calculation submodule is used to calculate the product of the correction factor and the safe short-circuit duration to obtain the target short-circuit duration.

[0161] Optionally, the device 400 for determining the motor short-circuit time further includes: The short-circuit sampling module is used to perform multiple three-phase short circuits on the motor with a target short-circuit duration and sample the current to obtain multiple sampled currents. The parameter determination module is used to determine the initial speed and initial position of the motor based on the vector characteristics and electrical parameters of multiple sampled currents; the vector characteristics include at least the vector angle and the electrical angular velocity; The motor starting module is used to determine the motor starting control strategy based on the motor's initial speed and initial position.

[0162] Optional, short-circuit sampling module, including: The first short-circuit submodule is used to wait for the current to decay until the waiting time reaches the first decay time, and then apply a zero voltage vector to the motor again within the target short-circuit time to achieve a three-phase short circuit; the first decay time is twice the safe short-circuit time. The three-phase current of the motor is detected at the end of the second short circuit to obtain the second sampled current; The first sampling submodule is used to calculate the electrical angular velocity based on the second sampling current, and to calculate the second decay time based on the electrical angular velocity and the preset motor rotation angle. The second short-circuit submodule is used to wait for the current to decay until the waiting time reaches the second decay time, and then apply a zero voltage vector again within the target short-circuit time to achieve a three-phase short circuit. The second sampling submodule is used to detect the three-phase current of the motor after the third short circuit ends, and obtain the third sampling current.

[0163] Optionally, electrical parameters also include quadrature-axis inductance and rotor flux linkage. The parameter determination module includes: The speed determination submodule is used to determine the initial speed based on the third sampling current, quadrature-axis inductance, and rotor flux linkage. The rotational speed direction determination submodule is used to determine the direction of the initial rotational speed based on the vector angle difference between the second and third sampled currents. The position determination submodule is used to determine the initial position of the motor based on the vector angle of the third sampled current, electrical parameters, the direct axis angle of the third sampled current, and the target short-circuit duration; the direct axis angle is the deviation angle of the vector angle of the third sampled current relative to the direct axis.

[0164] Optional, the rotational speed determination submodule includes: The first product calculation unit is used to calculate the product of the quadrature axis inductance and the effective value of the third sampling circuit to obtain the third product; The second product calculation unit is used to calculate the product of the rotor flux and the target short-circuit duration to obtain the fourth product; The rotational speed calculation unit is used to obtain the initial rotational speed based on the ratio of the third product to the fourth product.

[0165] Optional, the rotational speed direction determination submodule includes: An angle transformation unit is used to transform the vector angle difference to obtain a standard angle within a preset standard range; the preset standard range is greater than -π and less than or equal to π. The first direction determination unit is used to determine the direction of the initial rotational speed as the positive direction when the standard angle is greater than or equal to zero. The second direction determination unit is used to determine the direction of the initial rotational speed as negative when the standard angle is less than zero.

[0166] Optionally, electrical parameters also include direct-axis inductance, and the location determination submodule setting includes: The current component calculation unit is used to perform Clarke transformation on the instantaneous value of the third sampled current to obtain the current component of the third sampled current in the α-β coordinate system. The vector angle calculation unit is used to calculate the vector angle of the third sampled current based on the current components. The direct-axis angle calculation unit is used to calculate the direct-axis angle based on the direct-axis inductance, quadrature-axis inductance, target short-circuit duration, and the electrical angular velocity corresponding to the third sampling current. The initial position calculation unit is used to calculate the difference between the vector angle and the direct axis angle of the third sampled current to obtain the initial position.

[0167] Optional, the motor starting module includes: The first motor start submodule is used to determine the start control strategy, including braking, recharging, and starting after static positioning, when the initial speed of the motor is less than or equal to a preset speed threshold. The second motor start-up submodule is used to determine the start-up control strategy when the initial speed of the motor is greater than the speed threshold. This strategy includes setting the initial speed and initial position to the initial values ​​of the sensorless state observer and executing the speed-current dual closed-loop operation strategy. The speed-current dual closed-loop operation strategy is used to achieve closed-loop control of speed and current using proportional-integral regulators.

[0168] As the device embodiment is basically similar to the method embodiment, the description is relatively simple, and relevant parts can be found in the description of the method embodiment.

[0169] Figure 7 This is a structural diagram of a device for determining the short-circuit time of a motor provided in an embodiment of this application. The device 400 for determining the short-circuit time of a motor may include the following modules.

[0170] Reference Figure 7 The electronic device 600 may include one or more of the following components: processing component 602, memory 604, power supply component 606, multimedia component 608, audio component 610, input / output (I / O) interface 612, sensor component 616, and communication component 616.

[0171] Processing component 602 typically controls the overall operation of electronic device 600, such as operations associated with display, telephone calls, data communication, camera operation, and recording operations. Processing component 602 may include one or more processors 620 to execute instructions to perform all or part of the steps of the methods described above. Furthermore, processing component 602 may include one or more modules to facilitate interaction between processing component 602 and other components. For example, processing component 602 may include a multimedia module to facilitate interaction between multimedia component 608 and processing component 602.

[0172] Memory 604 is used to store various types of data to support the operation of electronic device 600. Examples of this data include instructions for any application or method operating on electronic device 600, contact data, phonebook data, messages, pictures, multimedia, etc. Memory 604 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0173] Power supply component 606 provides power to various components of electronic device 600. Power supply component 606 may include a power management system, one or more power supplies, and other components associated with generating, managing, and distributing power to electronic device 600.

[0174] Multimedia component 608 includes an interface that provides an output interface between electronic device 600 and user. In some embodiments, the interface may include a liquid crystal display (LCD) and a touch panel (TP). If the interface includes a touch panel, the interface may be implemented as a touchscreen to receive input signals from the user. The touch panel includes one or more touch sensors to sense touches, swipes, and gestures on the touch panel. The touch sensors may not only sense the boundaries of touch or swipe actions but also detect the duration and pressure associated with the touch or swipe operation. In some embodiments, multimedia component 608 includes a front-facing camera and / or a rear-facing camera. When electronic device 600 is in an operating mode, such as shooting mode or multimedia mode, the front-facing camera and / or rear-facing camera may receive external multimedia data. Each front-facing camera and rear-facing camera may be a fixed optical lens system or have focal length and optical zoom capabilities.

[0175] Audio component 610 is used to output and / or input audio signals. For example, audio component 610 includes a microphone (MIC) used to receive external audio signals when electronic device 600 is in an operating mode, such as call mode, recording mode, and voice recognition mode. The received audio signals may be further stored in memory 606 or transmitted via communication component 616. In some embodiments, audio component 610 also includes a speaker for outputting audio signals.

[0176] Input / output (I / O) interface 612 provides an interface between processing component 602 and peripheral interface modules, such as keyboards, click wheels, buttons, etc. These buttons may include, but are not limited to, home buttons, volume buttons, power buttons, and lock buttons.

[0177] Sensor assembly 616 includes one or more sensors for providing state assessments of various aspects of electronic device 600. For example, sensor assembly 616 can detect the on / off state of electronic device 600, the relative positioning of components such as the display and keypad of electronic device 600, changes in position of electronic device 600 or a component of electronic device 600, the presence or absence of user contact with electronic device 600, orientation or acceleration / deceleration of electronic device 600, and temperature changes of electronic device 600. Sensor assembly 616 may include a proximity sensor configured to detect the presence of nearby objects without any physical contact. Sensor assembly 616 may also include a light sensor, such as a CMOS or CCD image sensor, for use in imaging applications. In some embodiments, sensor assembly 616 may also include an accelerometer, gyroscope, magnetometer, pressure sensor, or temperature sensor.

[0178] Communication component 616 facilitates wired or wireless communication between electronic device 600 and other devices. Electronic device 600 can access wireless networks based on communication standards, such as WiFi, carrier networks (such as 2G, 3G, 6G, or 5G), or combinations thereof. In one exemplary embodiment, communication component 616 receives broadcast signals or broadcast-related information from an external broadcast management system via a broadcast channel. In one exemplary embodiment, communication component 616 also includes a near-field communication (NFC) module to facilitate short-range communication. For example, the NFC module may be implemented based on radio frequency identification (RFID) technology, Infrared Data Association (IrDA) technology, ultra-wideband (UWB) technology, Bluetooth (BT) technology, and other technologies.

[0179] In an exemplary embodiment, the electronic device 600 may be implemented by one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors, or other electronic components to implement a method for determining the short-circuit time of a motor provided in this application embodiment.

[0180] In an exemplary embodiment, a non-transitory computer-readable storage medium including instructions is also provided, such as a memory 604 including instructions, which can be executed by a processor 620 of an electronic device 600 to perform the above-described method. For example, the non-transitory storage medium may be a ROM, random access memory (RAM), CD-ROM, magnetic tape, floppy disk, and optical data storage device, etc.

[0181] Figure 8 This is a block diagram of an electronic device 700 according to another embodiment of the present invention. For example, the electronic device 700 may be provided as a server. See also... Figure 8 The electronic device 700 includes a processing component 722, which further includes one or more processors, and memory resources represented by a memory 732 for storing instructions, such as application programs, that can be executed by the processing component 722. The application programs stored in the memory 732 may include one or more modules, each corresponding to a set of instructions. Furthermore, the processing component 722 is configured to execute instructions to perform a method for determining the short-circuit time of a motor provided in embodiments of this application.

[0182] Electronic device 700 may also include a power supply component 726 configured to perform power management of electronic device 700, a wired or wireless network interface 750 configured to connect electronic device 700 to a network, and an input / output (I / O) interface 758. Electronic device 700 may operate on an operating system stored in memory 732, such as Windows Server™, Mac OS X™, Unix™, Linux™, Free BSD™, or similar.

[0183] In embodiments of this application, memory 732 can be used to store software programs and various data. Memory 732 may primarily include a first storage area for storing programs or instructions and a second storage area for storing data. The first storage area may store the operating system, applications or instructions required for at least one function (such as sound playback, image playback, etc.). Furthermore, memory 732 may include volatile memory or non-volatile memory, or both. The non-volatile memory may be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. Volatile memory can be random access memory (RAM), static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDRSDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct memory bus RAM (DRRAM). The memory 732 in the embodiments of this application includes, but is not limited to, these and any other suitable types of memory.

[0184] The processor may include one or more processing units; optionally, the processor integrates an application processor and a modem processor, wherein the application processor mainly handles operations related to the operating system, user interface, and applications, while the modem processor mainly handles wireless communication signals, such as a baseband processor. It is understood that the aforementioned modem processor may also not be integrated into the processor.

[0185] This application also provides a readable storage medium storing a program or instructions. When the program or instructions are executed by a processor, they implement the various processes of the above-described method for determining the short-circuit time of a motor and achieve the same technical effect. To avoid repetition, they will not be described again here.

[0186] The processor is the processor in the electronic device described in the above embodiments. The readable storage medium includes computer-readable storage media, such as computer read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk.

[0187] This application provides a computer program product, which is stored in a storage medium and executed by at least one processor to implement the various processes of the above-described method for determining the short-circuit time of a motor, and can achieve the same technical effect. To avoid repetition, it will not be described again here.

[0188] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0189] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the related technology, can be embodied in the form of a computer software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0190] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A method of determining a short circuit time of an electric machine, characterized in that The method comprises: determining a safe short-circuit duration of the motor according to electrical parameters of the motor; the electrical parameters at least include a rated current; applying a zero voltage vector to the motor within the safe short-circuit duration to realize three-phase short-circuit, and detecting three-phase currents of the motor at the end of the short-circuit to obtain first sampled currents; correcting the safe short-circuit duration according to the first sampled currents and the rated current to obtain a target short-circuit duration.

2. The method of claim 1, wherein, The electrical parameters further include a quadrature-axis inductance, a rotor flux and an electrical angular velocity corresponding to a rated rotating speed, and the determining of the safe short-circuit duration of the motor according to the electrical parameters of the motor comprises: calculating a product of the rated current and the quadrature-axis inductance to obtain a first product; calculating a product of the electrical angular velocity corresponding to the rated rotating speed and the rotor flux to obtain a second product; calculating a ratio of the first product to the second product to obtain the safe short-circuit duration.

3. The method of claim 1, wherein, The correcting of the safe short-circuit duration according to the first sampled currents and the rated current to obtain the target short-circuit duration comprises: calculating a root mean square of the first sampled currents to obtain an effective value of the first sampled currents; determining a short-circuit current target value according to a preset weight coefficient and the rated current; calculating a ratio of the short-circuit current target value to the effective value of the first sampled currents to obtain a correction coefficient; calculating a product of the correction coefficient and the safe short-circuit duration to obtain the target short-circuit duration.

4. The method of claim 1, wherein, After the correcting of the safe short-circuit duration according to the first sampled currents and the rated current to obtain the target short-circuit duration, the method further comprises: applying the target short-circuit duration to the motor for multiple times of three-phase short-circuit and sampling currents to obtain multiple sampled currents; determining an initial rotating speed and an initial position of the motor according to vector features of the multiple sampled currents and the electrical parameters; the vector features at least include a vector angle and an electrical angular velocity; determining a starting control strategy of the motor according to the initial rotating speed and the initial position of the motor.

5. The method of claim 4, wherein, The applying of the target short-circuit duration to the motor for multiple times of short-circuit and the detecting of the currents of the motor to obtain the multiple sampled currents comprises: waiting for current decay until a waiting duration reaches a first decay duration, and then applying a zero voltage vector to the motor within the target short-circuit duration to realize three-phase short-circuit again; the first decay duration is twice the safe short-circuit duration; detecting the three-phase currents of the motor at the end of the short-circuit to obtain second sampled currents; calculating an electrical angular velocity according to the second sampled currents, and calculating a second decay duration according to the electrical angular velocity and a preset motor rotating angle; waiting for current decay until a waiting duration reaches the second decay duration, and then applying a zero voltage vector to the motor within the target short-circuit duration to realize three-phase short-circuit again; detecting the three-phase currents of the motor after the short-circuit to obtain third sampled currents.

6. The method of claim 5, wherein, The electrical parameters further include a quadrature-axis inductance and a rotor flux, and the determining of the initial rotating speed and the initial position of the motor according to the vector features of the multiple sampled currents and the electrical parameters comprises: determine the initial speed according to the third sampling current, the quadrature axis inductance and the rotor flux linkage; determine the direction of the initial speed according to the vector angle difference between the second sampling current and the third sampling current; determine the initial position of the motor according to the vector angle of the third sampling current, the electrical parameter, the direct axis angle of the third sampling current and the target short-circuit time length; the direct axis angle is the deviation angle of the vector angle of the third sampling current relative to the direct axis.

7. The method of claim 6, wherein, The method for determining the initial speed according to the third sampling current, the quadrature axis inductance and the rotor flux linkage comprises: calculating the product of the quadrature axis inductance and the effective value of the third sampling circuit to obtain a third product; calculating the product of the rotor flux linkage and the target short-circuit time length to obtain a fourth product; obtaining the size of the initial speed according to the ratio of the third product to the fourth product.

8. The method of claim 6, wherein, The method for determining the direction of the initial speed according to the vector angle difference between the second sampling current and the third sampling current comprises: performing angle transformation on the vector angle difference to obtain a standard angle in a preset standard range; the preset standard range is greater than -pi and less than or equal to pi; in the case that the standard angle is greater than or equal to zero, determining that the direction of the initial speed is a positive direction; in the case that the standard angle is less than zero, determining that the direction of the initial speed is a negative direction.

9. The method of claim 6, wherein, The electrical parameter further comprises a direct axis inductance, and the method for determining the initial position of the motor according to the vector angle of the third sampling current, the electrical parameter, the direct axis angle of the third sampling current and the target short-circuit time length comprises: performing Clark transformation on the instantaneous value of the third sampling current to obtain the current component of the third sampling current in an alpha-beta coordinate system; calculating the vector angle of the third sampling current according to the current component; calculating the direct axis angle according to the direct axis inductance, the quadrature axis inductance, the target short-circuit time length and the corresponding electrical angular velocity of the third sampling current; obtaining the initial position by subtracting the vector angle of the third sampling current from the direct axis angle.

10. The method of claim 5, wherein, The method for determining the start control strategy of the motor according to the initial speed of the motor and the initial position comprises: in the case that the initial speed of the motor is less than or equal to a preset speed threshold, determining that the start control strategy comprises braking, recharging and starting after static positioning; in the case that the initial speed of the motor is greater than the speed threshold, determining that the start control strategy comprises setting the initial speed and the initial position as the initial value of a non-inductive state observer and executing a speed-current double closed loop operation strategy, which is used for realizing closed loop control on speed and current by using proportional integral adjustor.

11. An apparatus for determining a short circuit time of an electric machine, characterized in that The device comprises: a first time length determination module configured to determine the safe short-circuit time length of the motor according to the electrical parameter of the motor; the electrical parameter at least comprises a rated current; The three-phase short-circuit module is configured to apply a zero voltage vector to the motor to realize three-phase short-circuit within the safe short-circuit duration, and detect three-phase currents of the motor at the end of the short-circuit to obtain first sampling currents. The second duration determining module is configured to correct the safe short-circuit duration according to the first sampling currents and the rated currents to obtain a target short-circuit duration.

12. An electronic device, comprising: The method comprises: A processor, a memory, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the method for determining the short-circuit duration of the motor according to any one of claims 1 to 10 is implemented.

13. A readable storage medium, characterized by, When the instructions or transactions in the storage medium are executed by the processor of the electronic device, the electronic device can execute the method for determining the short-circuit duration of the motor according to any one of claims 1 to 10.

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