A motor control method, device, equipment and computer readable storage medium

Abstract

The application discloses a motor control method, device and equipment and a computer readable storage medium, belongs to the motor control field, and considers that the voltage integral value of a specified phase can be changed by adjusting the triggering moment of a thyristor, so as to adjust the current effective value of the specified phase. Therefore, in the application, when three-phase voltage is unbalanced, a phase with the minimum current effective value is taken as a reference phase, a triggering moment adjustment value is determined for a next thyristor to be triggered of each non-reference phase, the triggering moment adjustment value is superposed on the original triggering moment of the corresponding thyristor to be triggered to obtain a target triggering moment, and finally the thyristor to be triggered is triggered at the target triggering moment. Therefore, the voltage integral value of the non-reference phase in the next half current period is consistent with that of the reference phase, the balance of the three-phase current effective value is realized, the fluctuation of the motor torque is inhibited, and the service life of the motor and the user experience are improved.

Description

Technical Field

[0001] This invention relates to the field of motor control, and in particular to a motor control method. This invention also relates to a motor control device, equipment, and computer-readable storage medium. Background Technology

[0002] Ideally, the three-phase voltages of a three-phase asynchronous motor are balanced (symmetrical), which makes the effective values ​​of the three-phase currents equal and the torque of the motor relatively stable. However, the three-phase voltages of a three-phase asynchronous motor can be unbalanced. Once the three-phase voltages are unbalanced, it will lead to an imbalance between the effective values ​​of the three-phase currents, causing fluctuations in the motor torque, reducing the motor's lifespan and affecting the user experience.

[0003] Therefore, how to provide a solution to the above-mentioned technical problems is a problem that needs to be solved by those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide a motor control method, device, equipment, and computer-readable storage medium. By using the phase with the smallest effective current value as the reference phase and controlling the voltage integral value of the non-reference phase during the continuous current period to be equal to that of the reference phase, the effective current values ​​of the three phases are balanced, thereby reducing torque fluctuations, improving motor lifespan, and enhancing user experience.

[0005] To address the aforementioned technical problems, this invention provides a motor control method, applied to a controller for a three-phase asynchronous motor, comprising:

[0006] When the three-phase voltage of the three-phase asynchronous motor is unbalanced, the phase with the smallest effective current value is taken as the reference phase;

[0007] Using the target integral value equal to that of the reference phase as the objective, the trigger time adjustment value corresponding to each non-reference phase is determined respectively; wherein, the target integral value is: the voltage integral value during the current continuous period of the current half current cycle;

[0008] For each non-reference phase, the trigger time adjustment value corresponding to the non-reference phase is superimposed on the original trigger time of the next thyristor to be triggered to obtain the target trigger time;

[0009] At the target triggering time of the thyristor to be triggered, the thyristor in the non-reference phase is triggered.

[0010] On the other hand, for each non-reference phase, the method of superimposing the corresponding trigger time adjustment value of the non-reference phase on the original trigger time of the next thyristor to be triggered to obtain the target trigger time includes:

[0011] For each non-reference phase, the sum of the original turn-off angle of the next thyristor to be triggered and the triggering time adjustment value corresponding to the non-reference phase is taken as the target turn-off angle′ of the thyristor to be triggered.

[0012] The step of triggering the non-reference phase thyristor at the target triggering time includes:

[0013] At the target turn-off angle after the rising edge of the tube voltage drop of the thyristor to be triggered appears, the thyristor to be triggered in the non-reference phase is triggered.

[0014] On the other hand, determining the trigger time adjustment value corresponding to each non-reference phase, with the objective of equaling the target integral value of the reference phase, includes:

[0015] Using the goal of equalizing the first-segment integral value with the target integral value of the reference phase as the objective, the first-segment adjustment value′ corresponding to each non-reference phase is determined.

[0016] Taking the goal of equaling the latter part of the target integral value with the reference phase as the objective, the latter part adjustment value corresponding to each non-reference phase is determined respectively;

[0017] The sum of the front adjustment value and the rear adjustment value of a single non-reference phase is used as the trigger time adjustment value corresponding to the non-reference phase.

[0018] The target integral value is: the voltage integral value during the current continuous period of the current half-current cycle, and the target integral value is divided into the first integral value and the second integral value by the voltage zero crossing point.

[0019] On the other hand, after determining the front-end adjustment value for each non-reference phase by taking the goal of equaling the front-end integral value with the target integral value of the reference phase as the objective, the motor control method further includes:

[0020] Within the first half-current cycle of determining the three-phase voltage imbalance, the preceding adjustment value of a single non-reference phase is used as the initial adjustment value for the triggering time of the non-reference phase.

[0021] For each non-reference phase, the original triggering time of the initial thyristor to be triggered within the first half-current cycle of the three-phase voltage imbalance is determined, and the sum of the initial adjustment value of the triggering time corresponding to the non-reference phase is used as the target triggering time of the initial thyristor.

[0022] At the target triggering time of the initial thyristor, the initial thyristor of the non-reference phase is triggered.

[0023] On the other hand, the provision that when the three-phase voltage of the three-phase asynchronous motor is unbalanced, the phase with the smallest effective current value is used as the reference phase includes:

[0024] When the complex voltage imbalance of the three-phase asynchronous motor is greater than a preset threshold, the phase with the smallest effective current value is taken as the reference phase.

[0025] On the other hand, the motor control method also includes:

[0026] If the current complex voltage imbalance is greater than the preset threshold, and there is a non-reference phase with a trigger time adjustment value of zero, then the alarm will be activated.

[0027] On the other hand, the provision that when the three-phase voltage of the three-phase asynchronous motor is unbalanced, the phase with the smallest effective current value is used as the reference phase includes:

[0028] During the soft start process, when the three-phase voltage of the three-phase asynchronous motor is unbalanced, the phase with the smallest effective voltage value or the phase with the smallest effective current value is used as the reference phase.

[0029] When the three-phase voltage of the three-phase asynchronous motor is unbalanced after startup, the phase with the smallest effective current value is used as the reference phase.

[0030] To address the aforementioned technical problems, the present invention also provides a motor control device, a controller applied to a three-phase asynchronous motor, comprising:

[0031] The first determining module is used to select the phase with the smallest effective current value as the reference phase when the three-phase voltage of the three-phase asynchronous motor is unbalanced.

[0032] The second determining module is used to determine the trigger time adjustment value corresponding to each non-reference phase, with the target integral value being equal to that of the reference phase as the target; wherein, the target integral value is: the voltage integral value during the current continuous period of the current half current cycle;

[0033] The calculation module is used to, for each non-reference phase, add the corresponding trigger time adjustment value of the non-reference phase to the original trigger time of the next thyristor to be triggered, so as to obtain the target trigger time;

[0034] An action module is used to trigger the non-reference phase thyristor at the target trigger time of the thyristor to be triggered.

[0035] To address the aforementioned technical problems, the present invention also provides a motor control device, comprising:

[0036] Memory, used to store computer programs;

[0037] A processor is used to implement the steps of the motor control method described above when executing the computer program.

[0038] To address the aforementioned technical problems, the present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the motor control method described above.

[0039] This invention provides a motor control method. Considering that adjusting the triggering time of a thyristor can change the voltage integral value of a specified phase, thereby adjusting the effective current value of that specified phase, this invention, when the three-phase voltage is unbalanced, uses the phase with the smallest effective current value as the reference phase. For each non-reference phase, a triggering time adjustment value is determined for the next thyristor to be triggered. This adjustment value is then superimposed on the original triggering time of the corresponding thyristor to obtain the target triggering time. Finally, the thyristor to be triggered is triggered at the target triggering time, ensuring that the voltage integral value of the non-reference phase in the next half-current cycle is consistent with that of the reference phase. This achieves a balance of the effective current values ​​of the three phases, suppresses motor torque fluctuations, and improves motor lifespan and user experience.

[0040] The present invention also provides a motor control device, equipment, and computer-readable storage medium, which have the same beneficial effects as the motor control method described above. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention, the relevant technologies and the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 A flowchart illustrating a motor control method provided by the present invention;

[0043] Figure 2 This is a schematic diagram of the soft starter main circuit.

[0044] Figure 3 This is a schematic diagram showing the electrical energy angle relationship of a three-phase asynchronous motor;

[0045] Figure 4 A logic diagram of a motor control method provided by the present invention;

[0046] Figure 5 A waveform diagram of the root mean square value of a three-phase current is provided for this invention.

[0047] Figure 6A schematic diagram illustrating the effect of motor control provided by the present invention.

[0048] Figure 7 A schematic diagram of the structure of a motor control device provided by the present invention;

[0049] Figure 8 This is a schematic diagram of the structure of a motor control device provided by the present invention. Detailed Implementation

[0050] The core of this invention is to provide a motor control method, device, equipment, and computer-readable storage medium. By using the phase with the smallest effective current value as the reference phase, and controlling the voltage integral value of the non-reference phase during the continuous current period to be equal to that of the reference phase, the effective values ​​of the three-phase current are balanced, thereby reducing torque fluctuations, improving motor lifespan, and enhancing user experience.

[0051] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] Please refer to Figure 1 , Figure 1 This is a flowchart illustrating a motor control method provided by the present invention. The motor control method is applied to a controller of a three-phase asynchronous motor and includes:

[0053] S101: When the three-phase voltage of a three-phase asynchronous motor is unbalanced, the phase with the smallest effective current value is used as the reference phase;

[0054] Specifically, considering the technical problems mentioned above, and considering that adjusting the triggering time of the thyristor can change the voltage integral value of a specified phase, thereby adjusting the effective current value of that specified phase, theoretically, the effective current values ​​of the three phases can be adjusted to a balanced state by adjusting the triggering time of the thyristor. However, considering that the turn-off angle is zero after the motor starts, it is impossible to increase the voltage integral value of the corresponding phase by advancing the triggering time of the thyristor. But, regardless of whether the motor is starting or after starting, the voltage integral value of the corresponding phase can be reduced by delaying the triggering time of the thyristor. Therefore, in this embodiment of the invention, when the three-phase voltage of the three-phase asynchronous motor is unbalanced, the phase with the smallest effective current value is used as the reference phase, and the triggering time of the thyristors of the non-reference phases (the other two phases) is delayed, so that the effective current values ​​of the three phases are equal. Therefore, in this step, the phase with the smallest effective current value can be used as the reference phase when the three-phase voltage of the three-phase asynchronous motor is unbalanced, so as to serve as the data basis for subsequent steps.

[0055] S102: Using the target integral value equal to that of the reference phase as the target, determine the trigger time adjustment value for each non-reference phase; where the target integral value is: the voltage integral value during the continuous current period of the current half-cycle.

[0056] Specifically, for a better explanation of the embodiments of the present invention, please refer to... Figures 2 to 4 , Figure 2 Figure 3 shows the structural diagram of the soft starter main circuit, and Figure 4 shows the schematic diagram of the electrical energy angle relationship of the three-phase asynchronous motor. Figure 4 This is a logic diagram of a motor control method provided by the present invention. Figure 2 In the soft-start main circuit, U A U B , and U C The voltages corresponding to phases A, B, and C are respectively controlled by the on / off switching of two thyristors on each phase, supplying the voltage of each phase to the motor. Figure 2 The 3M in this context can refer to a three-phase asynchronous motor. Figure 3 In this context, α represents the trigger thyristor angle delayed after the voltage crosses zero. The freewheeling angle is called the power angle; γ is the zero current time interval, called the turn-off angle; and θ is the current-carrying time interval, called the conduction angle. Figure 4 in, u a -u c The voltage waveforms for phases A, B, and C are shown below. a -i cThe figures show the current waveforms of phases A, B, and C. Multiple lowercase letters 't' with different subscripts represent different times, and each 'S' with a different subscript represents a different voltage integral. Ideally, the effective voltage values ​​of the three phases A, B, and C, which are 120 degrees out of phase, should be balanced (i.e., equal) during the continuous current period within half a current cycle. This ensures that the voltage integral values ​​of the three phases A, B, and C, which are 120 degrees out of phase, are equal during the continuous current period within half a current cycle. Figure 4 (S) A +S A- )=(S B +S B- )=(S C +S C- However, due to the voltage imbalance of the three-phase power grid, the effective voltage values ​​of the three phases may differ. This results in differences in the integral voltage values ​​of the three phases (A, B, and C) within the continuous current period of half a current cycle, even when the shut-off angle is adjusted using normal control methods. In other words, Figure 4 (S) A +S A- ), (S B +S B- ) and (S C +S C- The three phases are not equal. Therefore, this embodiment of the invention can identify a reference phase and then use the target integral value equal to that of the reference phase as the target. The trigger time adjustment value for each non-reference phase is determined accordingly. The purpose is to make the adjusted target integral value of the non-reference phase equal to the target integral value of the reference phase, thereby achieving a balance between the three-phase voltage integral values ​​and the effective values ​​of the three-phase currents. Here, the target integral value refers to the voltage integral value within the continuous current period of the current in the current half-cycle, for example... Figure 4 (S) A +S A- ), (S B +S B- ) and (S C +S C- This is the voltage integral value of the three-phase current during the continuous period within the current half-cycle.

[0057] In this embodiment of the invention, the triggering time refers to the moment when each thyristor is triggered to conduct, that is... Figure 4 The time when the current occurs, for example, t al With t a4 wait.

[0058] S103: For each non-reference phase, the trigger time adjustment value corresponding to the non-reference phase is superimposed on the original trigger time of the next thyristor to be triggered to obtain the target trigger time;

[0059] Specifically, when the three-phase voltages are symmetrical, the turn-off angle γ will decrease to zero at a certain rate, eventually resulting in continuous current and the end of the soft-start process. However, when the three-phase voltages are asymmetrical (i.e., unbalanced) (C... vuf (Complex Voltage Unbalance Factor) To ensure that the effective values ​​of the three-phase currents are equal, a trigger timing adjustment value Δγ needs to be superimposed on the original turn-off angle γ of the non-reference phase. The turn-off angle is γ + Δγ, where γ decreases with time, and Δγ changes with the three-phase unbalance. Δγ is the trigger timing adjustment value in this embodiment of the invention. If the soft start is completed but the three-phase voltage is still unbalanced, Δγ cannot be equal to zero. That is, during steady-state operation, the thyristor still has a certain turn-off angle, thus ensuring that the "energy" input to the three-phase winding terminals of the motor is equal as much as possible. The magnitude of Δγ depends on the three-phase unbalance. If the three-phase voltage becomes symmetrical at a certain moment, Δγ will immediately become zero.

[0060] Specifically, based on the above principles, in this step, for each non-reference phase, the sum of the original trigger time of the next thyristor to be triggered and the corresponding trigger time adjustment value of the non-reference phase can be used as the target trigger time of the thyristor to be triggered. For example, in... Figure 4 In (S) A1 +S A1- ), (S B1 +S B1- ) and (S C1 +S C1- During this half-current cycle, the trigger timing adjustment value for the non-reference phase can be calculated. This adjustment value is then superimposed on the trigger timing of the thyristor in the next half-current cycle. For example, for phase C, the trigger timing adjustment value can be calculated in (S... A1 +S A1- ), (S B1 +S B1- ) and (S C1 +S C1- The trigger timing adjustment value obtained during this half-current cycle is superimposed on S. C2- The original triggering time of this thyristor is t. c11 t after adding the trigger time adjustment value c11 Become t c12 This ensures that the target integral values ​​of the three phases are equal and the effective current values ​​are equal in the next half current cycle. Therefore, in this step, for each non-reference phase, the original triggering time of the next thyristor to be triggered is superimposed with the corresponding triggering time adjustment value of the non-reference phase to obtain the target triggering time, which is then used as the data basis for subsequent steps.

[0061] S104: At the target triggering time of the thyristor to be triggered, trigger the thyristor in the non-reference phase.

[0062] Specifically, after obtaining the target triggering time of the next thyristor to be triggered for each non-reference phase, the thyristor to be triggered in the non-reference phase can be triggered at the target triggering time of the thyristor to be triggered, so that the target integral values ​​of the three phases are equal and the effective current values ​​are also equal.

[0063] This invention provides a motor control method. Considering that adjusting the triggering time of a thyristor can change the voltage integral value of a specified phase, thereby adjusting the effective current value of that specified phase, this invention, when the three-phase voltage is unbalanced, uses the phase with the smallest effective current value as the reference phase. For each non-reference phase, a triggering time adjustment value is determined for the next thyristor to be triggered. This adjustment value is then superimposed on the original triggering time of the corresponding thyristor to obtain the target triggering time. Finally, the thyristor to be triggered is triggered at the target triggering time, ensuring that the voltage integral value of the non-reference phase in the next half-current cycle is consistent with that of the reference phase. This achieves a balance of the effective current values ​​of the three phases, suppresses motor torque fluctuations, and improves motor lifespan and user experience.

[0064] Based on the above embodiments:

[0065] As an optional embodiment, for each non-reference phase, the corresponding trigger time adjustment value of the non-reference phase is superimposed on the original trigger time of the next thyristor to be triggered to obtain the target trigger time, including:

[0066] For each non-reference phase, the sum of the original turn-off angle of the next thyristor to be triggered and the adjustment value of the triggering time corresponding to the non-reference phase is used as the target turn-off angle of the thyristor to be triggered.

[0067] At the target triggering time of the thyristor to be triggered, the thyristors to be triggered that are not referenced include:

[0068] At the target turn-off angle after the rising edge of the tube voltage drop of the thyristor to be triggered appears, the thyristor to be triggered in the non-reference phase is triggered.

[0069] Specifically, based on the principle described above, in this embodiment of the invention, for each non-reference phase, the sum of the original turn-off angle of the next thyristor to be triggered and the corresponding trigger time adjustment value can be used as the target turn-off angle (i.e., the trigger time adjustment value) of the thyristor to be triggered.

[0070] For details, please refer to Figure 3The motor control method in this embodiment of the invention uses the current zero-crossing point as the reference point, i.e., time t2. Using t2 as the timing start point, a delay of γ angle is applied after the phase transition to trigger the thyristor. Since the motor is an inductive load, the current exhibits "inertia," and the current will repeatedly cross the zero axis near the end of the motor's freewheeling. Judging the end of the freewheeling based solely on the current value would be inaccurate. Therefore, the rising edge of the thyristor's voltage drop is selected as the current zero-crossing point. Using this point as the reference point, a certain delay (γ+Δγ) is applied after the phase transition to trigger the thyristor. This directly controls the thyristor's turn-off time; this triggering method is called turn-off angle control.

[0071] As an optional embodiment, taking the target integral value equal to that of the reference phase as the objective, the trigger time adjustment value corresponding to each non-reference phase is determined as follows:

[0072] The goal is to make the first-segment integral value equal to the target integral value of the reference phase, and the first-segment adjustment value is determined for each non-reference phase.

[0073] Using the goal of equalizing the latter part of the target integral value with that of the reference phase as the objective, the latter part adjustment value′ corresponding to each non-reference phase is determined.

[0074] The sum of the front and back adjustment values ​​of a single non-reference phase is used as the trigger timing adjustment value for the non-reference phase.

[0075] The target integral value is the voltage integral value during the current continuous period of the current half-current cycle. The target integral value is divided into the first integral value and the second integral value by the voltage zero crossing point.

[0076] Specifically, in Figure 4 In this process, when the three-phase voltage is unbalanced, the unbalanced voltage is integrated within the continuous current period (conduction angle) of half a current cycle. This integration is represented by "area". Using the "area" of the phase with the smallest voltage amplitude as a reference, the "areas" of the two phases with larger voltage amplitudes are adjusted. Utilizing the principle of "equal areas", the thyristor turn-off angle adjustment Δγ of the non-reference phase is calculated. This ensures that the energy received by the three-phase windings is approximately equal, indirectly improving the motor's torque and speed. Assume that phase A has the smallest voltage amplitude and the three-phase voltage frequencies are the same. The following explanation uses phase A as a reference and adjusts phase C as an example to illustrate the adjustment process; the adjustment process for phase B is the same as for phase C.

[0077] Among them, when the voltage is balanced, the integral value S of the three-phase voltage is... x (x = A, B, C, A-, B-, C-) should be approximately equal. For phase AC, S x for:

[0078]

[0079]

[0080] When the power supply voltage is balanced, we have approximately S A ≈S C S A -≈S C- S A +S A- ≈S C +S C- Furthermore, the effective values ​​of the AC two-phase currents are equal.

[0081] Specifically, when the power supply voltage is unbalanced (phase A amplitude voltage is at its minimum), i.e., |u C |>|u A If the ramp trigger signals of the six thyristors (the normal turn-off angle will continuously decrease, linearly decreasing to zero in a ramp-like manner) decrease at the same rate, then throughout the entire startup process, regardless of whether the current is continuous or not, there will always be a S C >S A S C- >S A- Because the motor is a symmetrical load, when the voltage at the motor terminals is not equal, the winding currents will naturally be unequal, and the main rotating magnetic field will not be circular, which will cause torque fluctuations.

[0082] At the moment when voltage imbalance is detected (at (S) A +S A- ), (S B +S B- ) and (S C +S C- In the next cycle of this cycle, the positive and negative "areas" of phase A voltage are used as a reference (S). A1， S A1- (As a known value), adjust the C-related break-angle slope trigger signal ( Figure 4 The dashed line in the middle indicates the starting point for adjusting the C-phase trigger signal.

[0083] Adjusting the signal involves three steps:

[0084] (1) Step 1: Let S C1 =S A1 (in ), calculate the shut-off angle adjustment Δt1 = tc7 - tc6 corresponding to the positive "area", which is the "taking the first segment integral value in the target integral value of the reference phase as the target, and determine the first segment adjustment value corresponding to each non-reference phase respectively".

[0085] (2) Second step: Let S C1 -=S A1 -(in ), calculate the shut-off angle adjustment Δt2 = tc10 - tc9 corresponding to the negative "area", which is the "taking the latter part of the target integral value with the reference phase as the target, and determine the latter part adjustment value corresponding to each non-reference phase respectively".

[0086] (3) Third step: Let Δt = Δt1 + Δt2. For thyristor VT2 in the negative half-cycle of phase C (i.e., the next thyristor to be triggered), the original triggering was t 11 The time was postponed to t 12 The time delay is Δt, which is the sum of the front and back adjustment values ​​of a single non-reference phase, as mentioned earlier, used as the trigger time adjustment value corresponding to the non-reference phase.

[0087] The thyristor VT5 of the C-phase positive half-cycle is adjusted using a similar method. Originally, the triggering time was delayed from t13 to t14. This method is used to adjust it for each subsequent cycle. Since the C-phase voltage amplitude is relatively large, delaying the thyristor triggering ensures that the root mean square value of the AC-phase current is consistent, reducing torque fluctuations.

[0088] The calculation methods for Δt1 and Δt2 are as follows:

[0089] Calculation of Δt1. In practical engineering applications, the feasibility of the algorithm must also be considered. Here, the method for calculating Δt1 is given. Because phase A leads phase C, before the thyristor trigger signal of phase C arrives, the "area" S... A1 It can be calculated in advance. But The lower bound of integration is unknown, u c (t) is unknown, and Δt1 must be calculated before tc6. It's impractical to calculate future adjustment values ​​using unknown quantities, as these are values ​​for a "future" time. Here, although the three-phase voltage amplitudes differ, the voltage waveform remains symmetrical within half a cycle, allowing the "right-side area" S of the half-cycle to be considered. C1 pass (k is an odd number) The axisymmetric aspect is the "left side area", that is, the tc4 to tc5 interval of phase C.

[0090] Let S C1 =S A1 Calculate tc5-tc4, then tc5-tc4=tc8-tc7, therefore Δt1=0.5Ts-tc6-(tc5-t4), T s This refers to the voltage period.

[0091] Calculation of Δt2: The value of Δt2 is used at time t11, let S C1- =S A1-Calculate tc9 (upper limit of integration). The unadjusted freewheeling angle tc10 of the C-phase thyristor can be directly read, so Δt2 = tc10 - tc9 can be directly calculated.

[0092] Specifically, the above describes the method for adjusting the turn-off angle of the thyristor in phase C with phase A as a reference. The adjustment method for phase B is the same as that for phase C.

[0093] As an optional embodiment, after determining the first-stage adjustment value corresponding to each non-reference phase, with the goal of equaling the first-stage integral value of the target integral value with respect to the reference phase, the motor control method further includes:

[0094] In the first half-current cycle of determining three-phase voltage imbalance, the adjustment value of the first half of a single non-reference phase is used as the initial adjustment value of the trigger moment corresponding to the non-reference phase.

[0095] For each non-reference phase, the original triggering time of the initial thyristor to be triggered within the first half-current cycle of the three-phase voltage imbalance is determined, and the sum of the initial adjustment value of the triggering time corresponding to the non-reference phase is used as the target triggering time of the initial thyristor.

[0096] At the target triggering moment of the initial thyristor, the initial thyristor of the non-reference phase is triggered.

[0097] For details, please refer to Figure 4 As can be seen, assuming the three-phase voltage imbalance is determined within the voltage cycle to the left of the dashed line at the starting point of the ramp trigger signal correction, then the right side of the dashed line represents the first adjustment cycle. Since the motor control method described earlier uses the trigger timing adjustment value calculated in the first half-current cycle to adjust the trigger timing of the thyristors to be triggered in the next half-current cycle, the first adjustment cycle to be adjusted on the right side of the dashed line cannot completely obtain the trigger timing adjustment value (i.e., the sum of the front and rear adjustment values) based on the voltage integral data of the previous half-current cycle. However, the front-end adjustment value can be calculated using the data from the first half-current cycle. Therefore, in order to adjust the trigger timing of the thyristors to be triggered in the non-reference phase within the first half-current cycle... In this embodiment of the invention, the adjustment value of the first half-current cycle after the three-phase voltage imbalance is determined can be used as the initial adjustment value of the triggering time of a single non-reference phase within the first half-current cycle after the three-phase voltage imbalance is determined. Then, for each non-reference phase, the sum of the original triggering time of the initial thyristor to be triggered within the first half-current cycle after the three-phase voltage imbalance is determined and the initial adjustment value of the triggering time of the non-reference phase is used as the target triggering time of the initial thyristor. At the target triggering time of the initial thyristor, the initial thyristor of the non-reference phase is triggered. This can achieve adjustment of the first thyristor to be triggered after the three-phase voltage imbalance is determined, thereby better achieving the balance of the effective value of the three-phase current and suppressing torque fluctuations.

[0098] As an optional embodiment, when the three-phase voltage of a three-phase asynchronous motor is unbalanced, the phase with the smallest effective current value is used as the reference phase, including:

[0099] When the complex voltage imbalance of a three-phase asynchronous motor exceeds a preset threshold, the phase with the smallest effective current value is used as the reference phase.

[0100] Specifically, considering that the three-phase voltage imbalance can be quickly and accurately determined by the complex voltage imbalance, in this embodiment of the invention, when the complex voltage imbalance of the three-phase asynchronous motor is greater than a preset threshold, the phase with the smallest effective current value can be used as the reference phase.

[0101] The preset threshold can be set independently, and this embodiment of the invention does not limit it.

[0102] As an optional embodiment, the motor control method further includes:

[0103] If the current complex voltage imbalance is greater than the preset threshold, and there is a non-reference phase with an adjustment value of zero at the trigger moment, the alarm will be triggered.

[0104] Specifically, considering that the trigger timing adjustment value of the non-reference phase should theoretically be greater than zero under the condition of three-phase voltage imbalance, in this embodiment of the invention, if there is a non-reference phase with a trigger timing adjustment value of zero when the current complex voltage imbalance is greater than a preset threshold, the alarm will be triggered so that the staff can promptly detect the abnormality and make adjustments, thereby improving the reliability of the control.

[0105] The alarm can be of various types, such as a buzzer, and this embodiment of the invention does not limit the types.

[0106] As an optional embodiment, when the three-phase voltage of a three-phase asynchronous motor is unbalanced, the phase with the smallest effective current value is used as the reference phase, including:

[0107] When the three-phase voltage of a three-phase asynchronous motor is unbalanced during soft start-up, the phase with the smallest effective voltage value or the phase with the smallest effective current value is used as the reference phase.

[0108] When the three-phase voltage of a three-phase asynchronous motor is unbalanced after startup, the phase with the smallest effective current value is used as the reference phase.

[0109] Specifically, considering that during soft start-up, the relationship between the effective values ​​of the three-phase voltages and the effective values ​​of the three-phase currents remains consistent, but after start-up, if voltage imbalance still exists, the relationship between the effective values ​​of the three-phase voltages and the effective values ​​of the three-phase currents may differ, the phase with the smallest effective current value can be used as the reference phase after start-up, while during start-up, either the phase with the smallest effective voltage value or the phase with the smallest effective current value can be used as the reference phase, further improving the reliability of motor control.

[0110] Specifically, the control effect of the motor control method was also verified in the embodiments of the present invention. Please refer to [link / reference]. Figure 5 , Figure 5 This invention provides a waveform diagram of the root mean square value of a three-phase current, where i... x_rms (x = A, B, C) represents the waveform of the root mean square (RMS) value of the single-phase current. The aforementioned adjustment scheme is implemented starting at 1.5 seconds. Before 1.5 seconds, the difference in the RMS values ​​of the three-phase currents is significant, with the RMS values ​​ordered as B > C > A. From 1.5 seconds to 3.5 seconds, the aforementioned control scheme can make the RMS values ​​of the three-phase currents almost equal. However, after startup, a three-phase voltage imbalance still exists, i.e. Figure 5 In the period after 3.5s, without the above control scheme, the root mean square values ​​of the three-phase currents show significant differences. The order of the root mean square values ​​of the three-phase currents is: B > A > C. At this time, the phase with the smallest effective voltage value may still be phase A, but the phase with the smallest effective current value is phase C. Therefore, in this embodiment of the invention, the phase with the smallest effective current value can be used as the reference phase after startup.

[0111] Specifically, to better verify the control effect of this motor control method, please refer to... Figure 6 , Figure 6 This is a schematic diagram illustrating the effect of motor control provided by the present invention. Figure 6The upper part shows the waveform of the rotor speed of the three-phase asynchronous motor, and the lower part shows the waveform of the electromagnetic torque. For the rotor speed, the normal speed waveform is the rotor speed waveform when the three-phase voltage is balanced, and the speed waveform is relatively smooth. However, when the three-phase voltage is unbalanced, the rotor speed waveform is in the form of "unadjusted speed," with significant fluctuations. After the control process described in the embodiment of this invention, the adjusted speed waveform is obtained, which closely matches the normal speed waveform. For the electromagnetic torque, the normal torque waveform is the electromagnetic torque waveform when the three-phase voltage is balanced, and the electromagnetic torque fluctuation is small. However, when the three-phase voltage is unbalanced, the electromagnetic torque waveform is in the form of "unadjusted torque," with steady-state fluctuations reaching 3800 Nm, indicating significant electromagnetic torque fluctuations. After the control process described in the embodiment of this invention, the adjusted torque waveform is obtained, which closely matches the normal torque waveform, with steady-state fluctuations as low as 2560 Nm.

[0112] Please refer to Figure 7 , Figure 7 This is a schematic diagram of a motor control device provided by the present invention. The motor control device is applied to a controller of a three-phase asynchronous motor and includes:

[0113] The first determining module 71 is used to select the phase with the smallest effective current value as the reference phase when the three-phase voltage of the three-phase asynchronous motor is unbalanced.

[0114] The second determining module 72 is used to determine the trigger time adjustment value for each non-reference phase, taking the target integral value equal to the reference phase as the target; wherein, the target integral value is: the voltage integral value during the current continuous period of the current half current cycle.

[0115] Calculation module 73 is used to superimpose the corresponding trigger time adjustment value of the non-reference phase onto the original trigger time of the next thyristor to be triggered for each non-reference phase, so as to obtain the target trigger time.

[0116] Action module 74 is used to trigger the non-reference phase thyristor at the target trigger time of the thyristor to be triggered.

[0117] For a description of the motor control device provided in the embodiments of the present invention, please refer to the foregoing embodiments of the motor control method; the embodiments of the present invention will not be repeated here.

[0118] Please refer to Figure 8 , Figure 8 This invention provides a schematic diagram of the structure of a motor control device, which includes:

[0119] Memory 81 is used to store computer programs;

[0120] The processor 82 is used to execute computer programs to implement the steps of the motor control method as described in the foregoing embodiments.

[0121] For a description of the motor control device provided in the embodiments of the present invention, please refer to the foregoing embodiments of the motor control method; the embodiments of the present invention will not be repeated here.

[0122] The present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the motor control method as described in the foregoing embodiments.

[0123] For a description of the computer-readable storage medium provided in the embodiments of the present invention, please refer to the foregoing embodiments of the motor control method; the embodiments of the present invention will not be repeated here.

[0124] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section. It should also be noted that in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, 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 a..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0125] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A motor control method, characterized in that, Controllers used in three-phase asynchronous motors include: When the three-phase voltage of the three-phase asynchronous motor is unbalanced, the phase with the smallest effective current value is taken as the reference phase; Taking the first-segment integral value equal to the target integral value of the reference phase as the target, the first-segment adjustment value corresponding to each non-reference phase is determined respectively; Taking the goal of equaling the latter part of the target integral value with the reference phase as the objective, the latter part adjustment value corresponding to each non-reference phase is determined respectively; The sum of the front-end adjustment value and the back-end adjustment value of a single non-reference phase is used as the trigger time adjustment value corresponding to the non-reference phase; wherein, the target integral value is: the voltage integral value during the current continuous period of the current half current cycle, and the target integral value is divided into the front-end integral value and the back-end integral value by the voltage zero crossing point. For each non-reference phase, the trigger time adjustment value corresponding to the non-reference phase is superimposed on the original trigger time of the next thyristor to be triggered to obtain the target trigger time; At the target triggering time of the thyristor to be triggered, the thyristor in the non-reference phase is triggered.

2. The motor control method according to claim 1, characterized in that, For each non-reference phase, the target trigger time is obtained by superimposing the corresponding trigger time adjustment value of the non-reference phase on the original trigger time of the next thyristor to be triggered, including: For each non-reference phase, the sum of the original turn-off angle of the next thyristor to be triggered and the adjustment value of the triggering time corresponding to the non-reference phase is taken as the target turn-off angle of the thyristor to be triggered. The step of triggering the non-reference phase thyristor at the target triggering time includes: At the target turn-off angle after the rising edge of the tube voltage drop of the thyristor to be triggered appears, the thyristor to be triggered in the non-reference phase is triggered.

3. The motor control method according to claim 2, characterized in that, After determining the front-end adjustment value for each non-reference phase after setting the target integral value equal to the first-end integral value of the reference phase as the objective, the motor control method further includes: Within the first half-current cycle of determining the three-phase voltage imbalance, the preceding adjustment value of a single non-reference phase is used as the initial adjustment value for the triggering time of the non-reference phase. For each non-reference phase, the original triggering time of the initial thyristor to be triggered within the first half-current cycle of the three-phase voltage imbalance is determined, and the sum of the initial adjustment value of the triggering time corresponding to the non-reference phase is used as the target triggering time of the initial thyristor. At the target triggering time of the initial thyristor, the initial thyristor of the non-reference phase is triggered.

4. The motor control method according to claim 1, characterized in that, When the three-phase voltage of the three-phase asynchronous motor is unbalanced, the phase with the smallest effective current value is used as the reference phase, including: When the complex voltage imbalance of the three-phase asynchronous motor is greater than a preset threshold, the phase with the smallest effective current value is taken as the reference phase.

5. The motor control method according to claim 4, characterized in that, The motor control method also includes: If the current complex voltage imbalance is greater than the preset threshold, and there is a non-reference phase with a trigger time adjustment value of zero, then the alarm will be activated.

6. The motor control method according to any one of claims 1 to 5, characterized in that, When the three-phase voltage of the three-phase asynchronous motor is unbalanced, the phase with the smallest effective current value is used as the reference phase, including: During the soft start process, when the three-phase voltage of the three-phase asynchronous motor is unbalanced, the phase with the smallest effective voltage value or the phase with the smallest effective current value is used as the reference phase. When the three-phase voltage of the three-phase asynchronous motor is unbalanced after startup, the phase with the smallest effective current value is used as the reference phase.

7. A motor control device, characterized in that, Controllers used in three-phase asynchronous motors include: The first determining module is used to select the phase with the smallest effective current value as the reference phase when the three-phase voltage of the three-phase asynchronous motor is unbalanced. The second determining module is used to determine the front-end adjustment value corresponding to each non-reference phase, taking the equality of the front-end integral value with the target integral value of the reference phase as the target; and to determine the back-end adjustment value corresponding to each non-reference phase, taking the equality of the back-end integral value with the target integral value of the reference phase as the target; and to take the sum of the front-end adjustment value and the back-end adjustment value of a single non-reference phase as the trigger time adjustment value corresponding to the non-reference phase; wherein, the target integral value is: the voltage integral value during the current continuous period of the current half-current cycle, and the target integral value is divided into the front-end integral value and the back-end integral value by the voltage zero crossing point; The calculation module is used to, for each non-reference phase, add the corresponding trigger time adjustment value of the non-reference phase to the original trigger time of the next thyristor to be triggered, so as to obtain the target trigger time; An action module is used to trigger the non-reference phase thyristor at the target trigger time of the thyristor to be triggered.

8. A motor control device, characterized in that, include: Memory, used to store computer programs; A processor for executing the computer program to implement the steps of the motor control method as described in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of the motor control method as described in any one of claims 1 to 6.

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