A method for suppressing speed fluctuation, a method and device for optimizing phase shift angle

Abstract

The application discloses a rotating speed pulsation suppression method, a phase shift angle optimization method and device, according to the deviation between the set rotating speed and the actual rotating speed, the phase shift angle is optimized, the q-axis current instruction with the compressor rotating speed pulsation suppression function is generated through the optimal phase shift angle, the optimal phase shift angle can be searched on line without depending on the system model, the compressor rotating speed pulsation suppression is realized, and in the optimization process, the safety protection trigger is taken as the condition for reducing the phase shift angle search interval, the safety protection trigger is taken as the search exit condition, the optimization is ensured to be carried out in the verified safety interval, and the current divergence caused by the phase shift angle deviating from the safety range is avoided.

Description

Technical Field

[0001] This invention relates to a method for suppressing speed pulsation, a method and apparatus for optimizing phase shift angle, and belongs to the field of power electronics and motor drive technology. Background Technology

[0002] In a single mechanical cycle, the compressor sequentially undergoes three strokes: intake, compression, and exhaust. The periodic changes in the gas pressure inside the cylinder cause the load torque to fluctuate synchronously with the mechanical rotation angle, thus inducing periodic pulsations in speed. These speed pulsations not only cause significant vibration and noise and reduce system operating efficiency, but in severe cases, they can also accelerate mechanical fatigue and shorten the compressor's service life.

[0003] In conventional large electrolytic capacitor drive systems, there has been considerable research on compressor load pulsation suppression strategies. However, most existing methods are based on the premise that the DC bus voltage is basically stable, which is not applicable to scenarios without electrolytic capacitors where the bus voltage fluctuates significantly. In other words, they are not applicable to permanent magnet synchronous motor drive systems without electrolytic capacitors.

[0004] In the specific scenario of a compressor driven without electrolytic capacitors, the core idea of ​​existing solutions to address the motor mechanical frequency speed pulsation caused by compressor load torque fluctuations is to pre-calculate the amplitude and phase window of each harmonic of the speed pulsation offline, store them in a lookup table, and call the corresponding table entries using the mechanical angle signal as a synchronization reference during runtime. The harmonic components are then superimposed onto the torque or current command to suppress pulsation and reduce current peaks. However, in this solution, the optimal value of the phase shift angle in the compensation parameters depends on the specific operating conditions of the compressor and system parameters. Furthermore, this mapping relationship cannot be accurately obtained through modeling. The offline pre-calculated phase shift angle is unlikely to remain optimal under all operating conditions. If the phase shift angle is inappropriately chosen, it may not only fail to effectively suppress pulsation but may also lead to increased current or even current divergence. Summary of the Invention

[0005] This invention provides a method for suppressing rotational speed pulsation, a method and apparatus for optimizing phase shift angle, and solves the problems disclosed in the background art.

[0006] According to one aspect of this application, a method for suppressing speed pulsation is provided, comprising: Based on the deviation between the set rotational speed and the actual rotational speed, the phase shift angle is optimized, and the optimal modulation factor is generated based on the optimal phase shift angle. During the optimization process, safety protection triggering is used as a condition to narrow the phase shift angle search interval, and the feasible region of the phase shift angle is determined from the search interval. Safety protection triggering is used as a search exit condition, and the optimal phase shift angle is searched from the feasible region of the phase shift angle. Whether safety protection is triggered depends on the decreasing protection threshold during stable operation, J_filt, and J_fast. J_filt and J_fast are the slow and fast filtering results of J, respectively, where J is the sum of squares of the AC pulsation components extracted based on the deviation. Based on the output of the optimal modulation factor and power factor correction method, a q-axis current command is generated to suppress compressor speed pulsation.

[0007] Furthermore, using safety protection triggering as a condition for narrowing the phase shift angle search interval, the feasible region of the phase shift angle is determined from the preset phase shift angle search interval, including: 1) Control the phase shift angle to increase linearly from 0 to the upper limit of the phase shift angle search interval over time; 2) If the safety protection is triggered based on the decreasing protection threshold and J_fast, the phase angle search interval is narrowed, and the process returns to 1). If the safety protection is not triggered within the preset time T1, the most recently narrowed phase angle search interval is taken as the feasible region of the phase angle. The start time of the preset time T1 is the time when the most recently narrowed phase angle search interval was narrowed, and the end time is the current time. After the safety protection is triggered, the protection threshold is restored to the initial value.

[0008] Furthermore, using safety protection triggering as the search exit condition, the optimal phase shift angle is searched from the feasible region of the phase shift angle, including: The phase shift angle within the feasible region is evaluated point by point, and the phase shift angle corresponding to the minimum J_filt is selected as the current optimal phase shift angle. If the safety protection is triggered during the non-shielded period of the point-by-point evaluation process, the point-by-point evaluation is exited and the feasible region of the phase shift angle is redefined based on the decreasing protection threshold and J_fast. The shielded period is the preset duration T2 after the phase shift angle switch during the point-by-point evaluation process. No safety protection trigger judgment is performed during the shielded period. After the safety protection is triggered, the protection threshold is restored to the initial value.

[0009] Furthermore, after obtaining the current optimal phase shift angle, the optimal phase shift angle is locked until an external re-optimization signal is received or the safety protection is triggered based on the decreasing protection threshold and J_fast. The protection threshold is then restored to its initial value, and the feasible domain of the phase shift angle is redefined. The decreasing protection threshold is not less than the lower limit.

[0010] Furthermore, the formula for the protection threshold is: wd_threshold = wd_active_mean + K_wd × wd_base_std; where wd_threshold is the protection threshold, K_wd is a fixed multiple, wd_active_mean is a variable, the initial value of wd_active_mean is equal to wd_base_mean, and wd_base_mean and wd_base_std are respectively the mean value and standard deviation of J_fast when the phase shift angle is 0; the decreasing of the protection threshold refers to the decreasing of wd_active_mean, and the lower limit of the decrease of wd_active_mean is 0.4 times the initial value. When J_filt < wd_active_mean_0, wd_active_mean_1 = wd_active_mean_0 + α_r × (J_filt - wd_active_mean_0), where wd_active_mean_0 and wd_active_mean_1 are the variable before and after update respectively, and α_r is the tightening coefficient; when J_filt ≥ wd_active_mean_0, the variable remains unchanged.

[0011] Further, determining that the safety protection is triggered according to the decreasing protection threshold and J_fast includes: If the current J_fast exceeds the current protection threshold, the abnormal accumulated value is increased by a first abnormal value; If the current J_fast does not exceed the current protection threshold, the abnormal accumulated value is subtracted by a second abnormal value; wherein the second abnormal value is smaller than the first abnormal value; If the abnormal accumulated value reaches the accumulation upper limit, the safety protection is triggered; wherein after the safety protection is triggered, the abnormal accumulated value is reset to zero.

[0012] According to another aspect of the present application, a rotational speed ripple suppression apparatus is provided, comprising: A modulation factor generation module, configured to perform optimization on the phase shift angle according to the deviation between the set rotational speed and the actual rotational speed, and generate an optimal modulation factor according to the optimal phase shift angle; wherein in the optimization process, triggering of the safety protection is taken as a condition for narrowing the search interval of the phase shift angle, so as to determine a feasible region of the phase shift angle from the search interval of the phase shift angle; triggering of the safety protection is taken as a search exit condition, so as to search out the optimal phase shift angle from the feasible region of the phase shift angle; whether the safety protection is triggered is determined according to the decreasing protection threshold, J_filt and J_fast during stable operation; J_filt and J_fast are respectively the slow filtering result and the fast filtering result of J, and J is the sum of squares of the AC ripple components extracted according to the deviation; A command generation module, configured to generate a q-axis current command for suppressing the rotational speed ripple of the compressor according to the optimal modulation factor and the output of the power factor correction method.

[0013] According to another aspect of the present application, a phase shift angle optimization method is provided, comprising: The phase shift angle is optimized based on the deviation between the set speed and the actual speed. During the optimization process, safety protection triggering is used as a condition to narrow the phase shift angle search interval, determining the feasible region of the phase shift angle from the search interval. Safety protection triggering is also used as a search exit condition, searching for the optimal phase shift angle from the feasible region. Whether safety protection is triggered depends on the decreasing protection threshold during stable operation, J_filt, and J_fast. J_filt and J_fast are the slow and fast filtering results of J, respectively, where J is the sum of squares of the AC pulsation components extracted based on the deviation. The optimal phase shift angle obtained through optimization is used to generate a modulation factor, which, along with the output of a synchronized power factor correction method, generates a q-axis current command to suppress compressor speed pulsation.

[0014] According to another aspect of this application, a phase-shifting angle optimization device is provided, comprising: The optimization module optimizes the phase shift angle based on the deviation between the set speed and the actual speed. During optimization, safety protection triggering is used as a condition to narrow the phase shift angle search interval, determining the feasible region of the phase shift angle from the search interval. Safety protection triggering is also used as a search exit condition, searching for the optimal phase shift angle from the feasible region. Whether safety protection is triggered depends on the decreasing protection threshold during stable operation, J_filt, and J_fast. J_filt and J_fast are the slow and fast filtering results of J, respectively, where J is the sum of squares of the AC pulsation components extracted based on the deviation. The optimal phase shift angle obtained through optimization is used to generate a modulation factor. This modulation factor, along with the output of the synchronized power factor correction method, generates a q-axis current command to suppress compressor speed pulsation.

[0015] According to another aspect of this application, a computer-readable storage medium is provided that stores one or more programs, the one or more programs including instructions that, when executed by a computing device, cause the computing device to perform a method for suppressing rotational speed pulsations or a method for optimizing phase shift angles.

[0016] The beneficial effects achieved by this invention are as follows: Based on the deviation between the set speed and the actual speed, this invention optimizes the phase shift angle and generates a q-axis current command to suppress compressor speed pulsation through the optimal phase shift angle. It can search for the optimal phase shift angle online without relying on the system model to achieve compressor speed pulsation suppression. Furthermore, during the optimization process, safety protection triggering is used as a condition to narrow the phase shift angle search range and as a search exit condition, ensuring that the optimization is carried out within the verified safe range and that current divergence will not occur due to the phase shift angle deviating from the safe range. Attached Figure Description

[0017] Figure 1 The flowchart shows a method for suppressing rotational speed pulsation. Figure 2 A flowchart for generating modulation factors; Figure 3 An architecture diagram for the optimization process; Figure 4 This is a state transition process; Figure 5 A flowchart for determining the optimal phase shift angle; Figure 6 This is a block diagram illustrating the overall principle of the parallel implementation of the speed pulsation suppression method and the power factor correction method; Figure 7 The waveform diagram shows the phase shift angle optimization process. Figure 8 A thumbnail of an electrical waveform; Figure 9 This is an enlarged view of the locked state of the electrical waveform; Figure 10 This is a block diagram of a device for suppressing speed pulsation. Detailed Implementation

[0018] 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, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0019] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application.

[0020] At the same time, it should be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn according to actual scale.

[0021] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0022] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0023] It should be noted that similar symbols and letters in the accompanying drawings represent similar items; therefore, once an item is defined in one accompanying drawing, it does not need to be discussed further in subsequent accompanying drawings.

[0024] Furthermore, in the description of the embodiments of this application, the terms "first," "second," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance. Therefore, features defined with "first" or "second" may explicitly or implicitly include one or more features.

[0025] See Figure 1 , Figure 1 This is a flowchart illustrating a method for suppressing speed pulsation according to an embodiment of this application. Specifically, it is a method for suppressing compressor speed pulsation in a capacitor-free permanent magnet synchronous motor drive system. The method may include at least the following steps: Step 1: Optimize the phase shift angle based on the deviation between the set rotational speed and the actual rotational speed, and generate the optimal modulation factor based on the optimal phase shift angle. During the optimization process, safety protection triggering is used as a condition to narrow the phase shift angle search interval, determining the feasible region of the phase shift angle from the search interval. Safety protection triggering is used as a search exit condition, searching for the optimal phase shift angle from the feasible region. Whether safety protection is triggered depends on the decreasing protection threshold during stable operation, J_filt, and J_fast. J_filt and J_fast are the slow and fast filtering results of J, respectively, where J is the sum of squares of the AC pulsation components extracted based on the deviation.

[0026] It should be noted that the process of step 1 can be found in [reference needed]. Figure 2 The deviation n between the set rotational speed and the actual rotational speed err First, a notch filter removes the 100Hz component (i.e., removes the residual grid frequency in the rotational speed signal). Then, a frequency adaptive extraction unit locks the mechanical frequency ω. m It also extracts the AC pulsation component at that frequency; wherein, the frequency adaptive extraction unit can adopt SOGI-FLL, and FLL automatically tracks ω that changes with rotational speed. m Without needing to know the pulsation frequency in advance, SOGI outputs AC pulsation components, specifically a pair of orthogonal components v. α and v β (v) α Track input, v β (A 90° lag orthogonal signal). Based on orthogonal component v α and v β Perform phase shift angle optimization based on v α v β The phase shift operation is performed with the optimal phase shift angle φ, and the formula can be expressed as: sin(ω m ·t +φ) = v α ·cosφ - v β• sinφ; The result after the phase shift operation is sequentially amplified proportionally and then incremented by 1 (since the coefficient here is multiplied by the output of the speed loop, it must be incremented by 1 to ensure that the average value of the iq command before and after multiplying by the modulation factor remains unchanged) to generate the modulation factor, which can be expressed by the formula: i q _factor = 1 + K·sin(ω m ·t + φ), where K is the magnification factor.

[0027] It should be noted that, see Figure 3 In the optimization process, there are two independent processes: the security protection process and the search process. The security protection process is the security protection trigger judgment process, and the search process is the process of searching for the optimal phase shift angle from the phase shift angle search range. The security protection process is continuously effective during the search process. In this independent architecture, the security protection process does not participate in the search, and the search does not handle security logic. Compared with the approach of embedding protection into the search process, it is still effective when the state changes or parameters change.

[0028] The two independent processes described above share the same metric, differing only in their filtering time constants for different purposes; specifically, SOGI-FLL locks ω. m After, v α and v β It can directly form a cost function Reflecting ω m The energy of the pulsating component at the frequency is filtered by two time constants for J (see Table 1 for filtering data) to obtain J_filt and J_fast. Security protection and search are then performed based on J_filt and J_fast.

[0029] Table 1 Filtering Data Table

[0030] In some embodiments, the formula for the protection threshold can be expressed as: wd_threshold = wd_active_mean + K_wd × wd_base_std; wherein wd_threshold is the protection threshold, K_wd is a fixed multiple, which can generally be 2, wd_base_std is the standard deviation of J_fast when the phase shift angle is 0 (in rad), and both K_wd and wd_base_std are fixed values, so the variation of the protection threshold is completely driven by the unidirectional decrease of wd_active_mean, that is, the decrease of the protection threshold corresponds to the decrease of wd_active_mean; wd_active_mean is a variable, the initial value of wd_active_mean is equal to wd_base_mean, and wd_base_mean is the mean value of J_fast when the phase shift angle is 0.

[0031] When J_filt < wd_active_mean_0: wd_active_mean_1 = wd_active_mean_0 + α_r × (J_filt - wd_active_mean_0); wd_active_mean_0 and wd_active_mean_1 are the variable before update and the variable after update respectively, α_r is the tightening coefficient, with a typical value of 0.001; when J_filt ≥ wd_active_mean_0, the variable remains unchanged.

[0032] This decreasing protection threshold has a natural ability to distinguish between short-term disturbances and continuous divergence during the phase shift angle stabilization stage. When the system is subjected to a short-term disturbance, J_filt temporarily rises above wd_active_mean, the decrease is automatically suspended, and the protection threshold remains at the current level; after the disturbance subsides, that is, J_filt falls back, the decrease resumes.

[0033] It should be noted that wd_active_mean does not keep decreasing all the time, and there is a certain lower limit, which is generally defined as 0.4 times the initial value. Without a lower limit, after long-term decrease, wd_active_mean will approach the steady-state J_filt, and the protection threshold margin will only remain K_wd × wd_base_std. However, wd_base_std is collected under the condition of φ=0, which cannot accurately reflect the noise level of J_fast when φ>0, and the margin mismatch will cause normal J_fast fluctuations to penetrate the protection threshold, while 0.4 × wd_base_mean reserves the minimum margin related to the initialization baseline for the decrease.

[0034] In some embodiments, determining whether to trigger security protection based on a decreasing protection threshold and J_fast may specifically include: if the current J_fast exceeds the current protection threshold, the abnormal accumulation value is increased by a first abnormal value; if the current J_fast does not exceed the current protection threshold, the abnormal accumulation value is decreased by a second abnormal value; wherein the second abnormal value is less than the first abnormal value; if the abnormal accumulation value reaches the accumulation limit, security protection is triggered; wherein, after triggering security protection, the abnormal accumulation value is cleared to zero.

[0035] It should be noted that the second outlier can be 0.5, the first outlier can be 1, the maximum accumulation can be 4, and the outlier accumulation value can be defined as hit_counter. When the current protection threshold is exceeded, hit_counter is incremented by 1, and when the current protection threshold is not exceeded, hit_counter is decremented by 0.5.

[0036] Taking a single isolated noise spike as an example: 0 → (exceeds +1) → 1 → (not exceeding -0.5) → 0.5 → (not exceeding -0.5) → 0, returning to zero does not trigger safety protection. Taking continuous divergence as an example: 0 → (exceeds +1) → 1 → (exceeds +1) → 2 → (exceeds +1) → 3 → (exceeds +1) → 4, reaching the upper limit triggers safety protection.

[0037] Here, slow decay ensures that spikes are tolerated, fast accumulation ensures that divergence is captured in time, and the upper limit of accumulation of 4 balances response speed and tolerance for short-term fluctuations.

[0038] In some embodiments, safety protection triggering is used as a condition for narrowing the phase shift angle search interval, and the feasible region of the phase shift angle is determined from the preset phase shift angle search interval, i.e. Figure 3 The specific process of boundary probing can include: 1) Control the phase shift angle φ to increase linearly from 0 to the upper limit of the phase shift angle search interval over time.

[0039] It should be noted that the range of the phase shift angle search interval can be [0, φ_bound]. The initial phase shift angle φ is 0. After φ increases linearly with time to φ_bound (i.e., the upper limit), it stabilizes and triggers the protection threshold to decrease.

[0040] 2) If the safety protection is triggered based on the decreasing protection threshold and J_fast, the phase angle search interval is narrowed, and the process returns to 1). If the safety protection is not triggered within the preset time period T1, the most recently narrowed phase angle search interval is taken as the feasible region of the phase angle. The start time of the preset time period T1 is the time when the most recently narrowed phase angle search interval was narrowed, and the end time is the current time. The specific length of the preset time period T1 needs to be manually set according to the actual situation. After the safety protection is triggered, the protection threshold is restored to the initial value.

[0041] It should be noted that if the safety protection is triggered, the phase shift angle search range is reduced with fixed compensation. Specifically, the upper limit of the phase shift angle search range can be reduced, the phase shift angle is restored to 0, the protection threshold is restored to the initial value and maintained for 200ms, and then it switches to step 1).

[0042] For ease of explanation, we define states -1, 0, and 4. State -1 is initialization, where the suppression path is in place, φ is 0, and the baseline of the cost function is collected, i.e., the initial value of the protection threshold is collected. State 0 is boundary probing, where φ increases linearly over time to φ_bound and remains within the safe boundary. The protection threshold continuously decreases, and we monitor enable_opt (an identifier used to exit the boundary probing phase; initially enable_opt = 0, and if it jumps to 1, it enters the next phase, i.e., ...). Figure 3 (Point-by-point evaluation phase); State 4 is the recovery state, at which point φ returns to 0, waits for J to return to the baseline (i.e. the protection threshold returns to the initial value) and holds for 200ms before returning to the boundary probe.

[0043] See Figure 4 and Figure 5 The boundary probing process can be as follows: In state 0, φ increases linearly with time to φ_bound and then runs stably. The protection threshold begins to decrease. If safety protection is triggered, φ_bound decreases by a fixed step (usually 0.03 rad) and enters the recovery state (i.e., state 4). After the recovery state ends, it returns to state 0 and repeats the boundary probing process with a new phase shift angle search interval until φ_bound stabilizes and no longer triggers safety protection. This value is the safe operating boundary. Then, enable_opt is switched to 1 to enter the next stage.

[0044] During the boundary trial phase, immediately after initialization, wd_active_mean = wd_base_mean and has not yet decreased; the protection is equivalent to a fixed threshold. After φ rises to φ_bound, the system stabilizes, and the protection threshold is gradually lowered, becoming increasingly sensitive to progressive anomalies. The convergence speed of subsequent boundary trials also accelerates. After triggering the safety protection, φ_bound decreases in equal steps, ensuring consistent contraction amplitude and preventing insufficient contraction when φ is small. The significance of resetting wd_active_mean is that before triggering, wd_active_mean had already decreased unidirectionally for a period under the previous φ_bound, reflecting the steady-state cost level at that specific φ value. After triggering, φ_bound decreases, and the system operates at different φ values, corresponding to changes in the J level. The object calibrated by the original wd_active_mean no longer exists, and continuing to use it is meaningless. Resetting it to wd_base_mean ensures that the new round of boundary trials starts from a common initialization baseline, guaranteeing the validity of the threshold reference. By repeatedly "testing-triggering-reducing-retrying", the upper limit of the safety that the system can withstand is determined, that is, the feasible domain of the phase shift angle is determined.

[0045] In some embodiments, a safety protection trigger is used as the search exit condition to search for the optimal phase shift angle from the feasible region of the phase shift angle, i.e. Figure 3 The specific process of point-by-point evaluation may include: The phase shift angle within the feasible region is evaluated point by point, and the phase shift angle corresponding to the minimum J_filt is selected as the current optimal phase shift angle. If the safety protection is triggered during the non-shielded period of the point-by-point evaluation process, the point-by-point evaluation is exited and the feasible region of the phase shift angle is redefined based on the decreasing protection threshold and J_fast. The shielded period is the preset duration T2 after the phase shift angle switch during the point-by-point evaluation process. No safety protection trigger judgment is performed during the shielded period. After the safety protection is triggered, the protection threshold is restored to the initial value.

[0046] For ease of explanation, we define state 1; state 1 is a point-by-point evaluation, in which we scan step by step from the upper limit of the feasible region of the phase shift angle toward 0, evaluate J_filt at each point, and record the optimal value.

[0047] When enable_opt=1 is detected, the system switches from state 0 to state 1. See [link / description]. Figure 4 and Figure 5The point-by-point evaluation process can be as follows: scan progressively from the upper limit of the feasible region of the phase shift angle towards 0. For each phase shift angle, skip the transients (i.e., J_filt) of the first 1000 sampling periods, and then continuously collect 2000 J_filt samples. Calculate the mean as the cost of that phase shift angle. If the cost of the current phase shift angle is less than the historical best cost × 0.98 (introducing a 2% improvement threshold to avoid false updates caused by noise), then update the optimal record. After the scan is completed, the optimal phase shift angle can be obtained. If safety protection is triggered during the non-shielded period of the point-by-point evaluation process, the point-by-point evaluation is exited, and the process enters the recovery state (i.e., state 4). After the recovery state ends, boundary exploration is performed again (i.e., state 0), that is, the feasible region of the phase shift angle is redefined.

[0048] The safety protection process also includes a shielding mechanism. Specifically, during the point-by-point evaluation phase, a 200ms judgment shielding window is set whenever the phase angle switches, during which anomaly judgment is paused and hit_counter is cleared. This mechanism prevents current surges caused by transient phase angle switching from being misjudged as divergence.

[0049] It should be noted that after determining the optimal phase shift angle, the next step is to lock the optimal phase shift angle, that is... Figure 3 The lock φ_best is maintained until an external re-optimization signal is received or the safety protection is triggered based on the decreasing protection threshold and J_fast. The protection threshold is then restored to its initial value, and the feasible domain of the phase shift angle is redefined. The decreasing protection threshold is not less than the lower limit.

[0050] For ease of explanation, we define state 2; state 2 is optimal phase angle locking, where the phase angle is locked at φ_best, and it continues to run, with the protection threshold continuing to decrease. After point-by-point evaluation, it enters state 2, where φ remains at φ_best, and the protection threshold continues to decrease. If enable_opt is pulled low (i.e., an external re-optimization signal is received) or if safety protection is triggered based on the decreasing protection threshold and J_fast, the active mean is reset to the baseline mean (i.e., the protection threshold is restored to its initial value), and it returns to boundary probing (i.e., state 0).

[0051] In the above optimization process, the protection threshold decreases unidirectionally. A fixed baseline is used during initialization, and the threshold gradually approaches the actual operating level after the system stabilizes. The decreasing direction is unidirectional to avoid the protection threshold relaxing due to noise fluctuations. When triggering safety protection judgment, asymmetric judgment is adopted. Noise spikes are gradually digested by attenuation of -0.5, and continuous anomalies are quickly captured by accumulation of +1. The point-by-point evaluation stage is combined with a 200ms shielding window after φ switching to further reduce false triggering of transient impacts.

[0052] Step 2: Based on the output of the optimal modulation factor and power factor correction method, generate the q-axis current command to suppress compressor speed pulsation.

[0053] The above method optimizes the phase shift angle based on the deviation between the set speed and the actual speed. It generates a q-axis current command to suppress compressor speed pulsation using the optimal phase shift angle. This method can search for the optimal phase shift angle online without relying on the system model, thereby suppressing compressor speed pulsation. Furthermore, during the optimization process, safety protection triggering is used as a condition to narrow the phase shift angle search range and as a condition to exit the search. This ensures that the optimization is carried out within the verified safe range and that current divergence does not occur due to the phase shift angle deviating from the safe range.

[0054] For implementation of the above method, please refer to Figure 6 , Figure 6 There are two paths. One is the power factor correction path, which implements a power factor correction method by multiplying the speed loop PI output (i.e., the speed regulator output) by sin²(θg), where θg is the grid phase, so that the q-axis current envelope follows the grid voltage waveform, thereby improving the input power factor. This path is a prerequisite for the above method. The second path is the speed ripple suppression path, which uses the modulation factor i obtained in step 1. q _factor( Figure 6 The part marked in the image is the compensation coefficient generator, which multiplies iq_factor by the output of the power factor correction path (i... q _base) obtains the q-axis current command used to suppress compressor speed pulsation.

[0055] See Figures 7-9 , Figure 7 This is a waveform diagram of an adaptive phase shift angle optimization process. Figure 8 for Figure 7 The electrical waveform diagram for the same process is shown below, where udc is the bus voltage, ig is the grid-side current, iq is the motor q-axis current feedback value, ia is the motor phase current, and n is the actual mechanical speed of the motor rotor. Figure 9 for Figure 8 Enlarged view from 59.80s to 60s.

[0056] The motor starts at 0s, with a set speed of 1200rpm. The set speed is reached at 2.5s. At 5s, compressor speed pulsation suppression is activated (the phase shift angle remains at 0). Between 5s and 7.5s, the proportional gain K increases linearly from 0 to 0.75 over time. During this process, both J_filt and J_fast show a decreasing trend (the speed error gradually decreases). At 10s, the first stage of phase shift angle optimization begins, i.e., determining the feasible region. It first enters state -1, acquiring the baseline of the cost function, which is completed after 250ms, and then enters state 0, where φ increases to φ_bound. Subsequently, the first safety protection is triggered, entering state 4, where the phase shift angle returns to 0. After 200ms, it enters state 0 again. This process is repeated multiple times to finally determine the feasible region of φ. At 40s, enable_opt jumps to 1, entering state 1, where φ decreases to 0. During this process, J_filt continuously increases, so φ_bound at this point is the optimal phase shift angle. It then enters state 2, where φ returns to φ_bound. wd_threshold remains at zero for 0-10.25s (algorithm is running but state machine is not activated, safety protection is offline). Around 10.25s, baseline acquisition is completed, entering state 0, safety protection is activated, and the protection threshold steps to the baseline level, subsequently decreasing unidirectionally as the system stabilizes. Each time safety protection is triggered, state 4 is entered, safety protection is deactivated, the protection threshold drops sharply to zero, and after 200ms recovery, state 0 is returned, safety protection is reactivated, and the protection threshold steps up again. The entire process of determining the feasible region follows a cycle of "deactivation → activation / stepping → downslope → triggering / deactivation → recovery → reactivation." During point-by-point evaluation, the threshold remains flat without tightening, and decreases again after locking in the optimal value.

[0057] See Figure 10 , Figure 10 This is a block diagram of a speed pulsation suppression device provided in an embodiment of this application. The device is a virtual device and may include a modulation factor generation module and an instruction generation module. When executing the above suppression method, it can: The modulation factor generation module optimizes the phase shift angle based on the deviation between the set rotational speed and the actual rotational speed, and generates the optimal modulation factor based on the optimal phase shift angle. During the optimization process, safety protection triggering is used as a condition to narrow the phase shift angle search interval, determining the feasible region of the phase shift angle from the search interval. Safety protection triggering is used as a search exit condition, searching for the optimal phase shift angle from the feasible region. Whether safety protection is triggered depends on the decreasing protection threshold during stable operation, J_filt, and J_fast. J_filt and J_fast are the slow and fast filtering results of J, respectively, where J is the sum of squares of the AC pulsation components extracted based on the deviation.

[0058] The instruction generation module generates a q-axis current instruction to suppress compressor speed pulsation based on the output of the optimal modulation factor and power factor correction method.

[0059] The aforementioned device optimizes the phase shift angle based on the deviation between the set speed and the actual speed. It generates a q-axis current command to suppress compressor speed pulsation using the optimal phase shift angle. It can search for the optimal phase shift angle online without relying on the system model to suppress compressor speed pulsation. Furthermore, during the optimization process, safety protection triggering is used as a condition to narrow the phase shift angle search range, and safety protection triggering is used as a condition to exit the search. This ensures that the optimization is carried out within the verified safe range and that current divergence will not occur due to the phase shift angle deviating from the safe range.

[0060] This application also relates to a phase shift angle optimization method, which is the optimization part of the above-mentioned suppression method. The method may include at least: optimizing the phase shift angle based on the deviation between the set speed and the actual speed; wherein, during the optimization process, safety protection triggering is used as a condition to narrow the phase shift angle search interval, and a feasible region of the phase shift angle is determined from the phase shift angle search interval; safety protection triggering is used as a search exit condition, and the optimal phase shift angle is searched from the feasible region of the phase shift angle; whether safety protection is triggered is based on a protection threshold decreasing during stable operation, J_filt, and J_fast; J_filt and J_fast are the slow filtering result and fast filtering result of J, respectively, and J is the sum of squares of the AC pulsation components extracted based on the deviation; the optimal phase shift angle obtained by optimization is used to generate a modulation factor, and the modulation factor is used with the output of the synchronous power factor correction method to generate a q-axis current command to suppress compressor speed pulsation.

[0061] The above method optimizes the phase shift angle based on the deviation between the set speed and the actual speed. It generates a q-axis current command to suppress compressor speed pulsation using the optimal phase shift angle. This method can search for the optimal phase shift angle online without relying on the system model, thereby suppressing compressor speed pulsation. Furthermore, during the optimization process, safety protection triggering is used as a condition to narrow the phase shift angle search range and as a condition to exit the search. This ensures that the optimization is carried out within the verified safe range and that current divergence does not occur due to the phase shift angle deviating from the safe range.

[0062] This application also relates to a phase shift angle optimization device, which is a virtual device. The device may include an optimization module, which, when executing the above-described optimization method, can: The optimization module optimizes the phase shift angle based on the deviation between the set speed and the actual speed. During optimization, safety protection triggering is used as a condition to narrow the phase shift angle search interval, determining the feasible region of the phase shift angle from the search interval. Safety protection triggering is also used as a search exit condition, searching for the optimal phase shift angle from the feasible region. Whether safety protection is triggered depends on the decreasing protection threshold during stable operation, J_filt, and J_fast. J_filt and J_fast are the slow and fast filtering results of J, respectively, where J is the sum of squares of the AC pulsation components extracted based on the deviation. The optimal phase shift angle obtained through optimization is used to generate a modulation factor. This modulation factor, along with the output of the synchronized power factor correction method, generates a q-axis current command to suppress compressor speed pulsation.

[0063] The aforementioned device optimizes the phase shift angle based on the deviation between the set speed and the actual speed. It generates a q-axis current command to suppress compressor speed pulsation using the optimal phase shift angle. It can search for the optimal phase shift angle online without relying on the system model to suppress compressor speed pulsation. Furthermore, during the optimization process, safety protection triggering is used as a condition to narrow the phase shift angle search range, and safety protection triggering is used as a condition to exit the search. This ensures that the optimization is carried out within the verified safe range and that current divergence will not occur due to the phase shift angle deviating from the safe range.

[0064] This application also relates to a computer-readable storage medium that stores one or more programs, the one or more programs including instructions that, when executed by a computing device, cause the computing device to perform a method for suppressing rotational speed pulsations or a method for optimizing phase angles.

[0065] This application also relates to a computer device including one or more processors and one or more memories, wherein one or more programs are stored in one or more memories and configured to be executed by one or more processors, and the one or more programs include instructions for performing a method for suppressing speed pulsation or a method for optimizing phase angle.

[0066] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0067] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0068] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0069] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0070] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of the claims of the present invention pending approval.

Claims

1. A method for suppressing rotational speed pulsation, characterized in that, include: Based on the deviation between the set rotational speed and the actual rotational speed, the phase shift angle is optimized, and the optimal modulation factor is generated based on the optimal phase shift angle. During the optimization process, safety protection triggering is used as a condition to narrow the phase shift angle search interval, and the feasible region of the phase shift angle is determined from the search interval. Safety protection triggering is used as a search exit condition, and the optimal phase shift angle is searched from the feasible region of the phase shift angle. Whether safety protection is triggered depends on the decreasing protection threshold, J_filt, and J_fast. J_filt and J_fast are the slow and fast filtering results of J, respectively, where J is the sum of squares of the AC pulsation components extracted based on the deviation. Based on the output of the optimal modulation factor and power factor correction method, a q-axis current command is generated that suppresses compressor speed pulsation.

2. The method according to claim 1, characterized in that, Using safety protection triggering as a condition to narrow down the phase shift angle search interval, the feasible region of the phase shift angle is determined from the preset phase shift angle search interval, including: 1) Control the phase shift angle to increase linearly from 0 to the upper limit of the phase shift angle search interval over time; 2) If the safety protection is triggered based on the decreasing protection threshold and J_fast, the phase angle search interval is narrowed, and the process returns to 1). If the safety protection is not triggered within the preset time T1, the most recently narrowed phase angle search interval is taken as the feasible region of the phase angle. The start time of the preset time T1 is the time when the most recently narrowed phase angle search interval was narrowed, and the end time is the current time. After the safety protection is triggered, the protection threshold is restored to the initial value.

3. The method according to claim 1, characterized in that, Using safety protection triggering as the search exit condition, the optimal phase shift angle is searched from the feasible region of the phase shift angle, including: The phase shift angle within the feasible region is evaluated point by point, and the phase shift angle corresponding to the minimum J_filt is selected as the current optimal phase shift angle. If the safety protection is triggered during the non-shielded period of the point-by-point evaluation process, the point-by-point evaluation is exited and the feasible region of the phase shift angle is redefined based on the decreasing protection threshold and J_fast. The shielded period is the preset duration T2 after the phase shift angle switch during the point-by-point evaluation process. No safety protection trigger judgment is performed during the shielded period. After the safety protection is triggered, the protection threshold is restored to the initial value.

4. The method according to claim 2, characterized in that, After obtaining the current optimal phase shift angle, the process also includes locking the optimal phase shift angle until an external re-optimization signal is received or the safety protection is triggered based on the decreasing protection threshold and J_fast. In this case, the protection threshold is controlled to return to its initial value, and the feasible domain of the phase shift angle is redefined. The decreasing protection threshold is not less than the lower limit.

5. The method according to any one of claims 2 to 4, characterized in that, The formula for the protection threshold is: wd_threshold = wd_active_mean + K_wd × wd_base_std; where wd_threshold is the protection threshold, K_wd is a fixed multiple, wd_active_mean is a variable whose initial value is equal to wd_base_mean, and wd_base_mean and wd_base_std are respectively the mean value and standard deviation of J_fast when the phase shift angle is 0; the decrement of the protection threshold refers to the decrement of wd_active_mean, and the lower limit of the decrement of wd_active_mean is 0.4 times the initial value. When J_filt < wd_active_mean_0, wd_active_mean_1 = wd_active_mean_0 + α_r × (J_filt - wd_active_mean_0), where wd_active_mean_0 and wd_active_mean_1 are respectively the variable before and after update, and α_r is the tightening coefficient; when J_filt ≥ wd_active_mean_0, the variable remains unchanged.

6. The method according to any one of claims 2 to 4, characterized in that, Determining that safety protection is triggered according to the decremented protection threshold and J_fast, comprising: if the current J_fast exceeds the current protection threshold, increasing the abnormal accumulated value by a first abnormal value; if the current J_fast does not exceed the current protection threshold, subtracting a second abnormal value from the abnormal accumulated value; wherein the second abnormal value is less than the first abnormal value; if the abnormal accumulated value reaches an accumulation upper limit, triggering the safety protection; wherein after the safety protection is triggered, the abnormal accumulated value is reset to zero.

7. A device for suppressing rotational speed pulsation, characterized in that, comprising: a modulation factor generation module, configured to optimize a phase shift angle according to the deviation between a set rotation speed and an actual rotation speed, and generate an optimal modulation factor according to the optimal phase shift angle; wherein in the optimization process, taking the triggering of safety protection as a condition for narrowing the phase shift angle search interval, a feasible region of the phase shift angle is determined from the phase shift angle search interval; taking the triggering of safety protection as a search exit condition, the optimal phase shift angle is searched out from the feasible region of the phase shift angle; whether the safety protection is triggered is determined according to the decremented protection threshold during stable operation, J_filt and J_fast; J_filt and J_fast are respectively the slow filtering result and fast filtering result of J, where J is the sum of squares of the AC pulsating components extracted according to the deviation; a command generation module, configured to generate a q-axis current command for suppressing compressor rotation speed pulsation according to the optimal modulation factor and the output of a power factor correction method.

8. A phase-shift angle optimization method, characterized in that, comprising: The phase shift angle is optimized based on the deviation between the set speed and the actual speed. During the optimization process, safety protection triggering is used as a condition to narrow the phase shift angle search interval, determining the feasible region of the phase shift angle from the search interval. Safety protection triggering is also used as a search exit condition, searching for the optimal phase shift angle from the feasible region. Whether safety protection is triggered depends on the decreasing protection threshold during stable operation, J_filt, and J_fast. J_filt and J_fast are the slow and fast filtering results of J, respectively, where J is the sum of squares of the AC pulsation components extracted based on the deviation. The optimal phase shift angle obtained through optimization is used to generate a modulation factor, which, along with the output of a synchronized power factor correction method, generates a q-axis current command to suppress compressor speed pulsation.

9. A phase-shifting angle optimization device, characterized in that, include: The optimization module optimizes the phase shift angle based on the deviation between the set speed and the actual speed. During optimization, safety protection triggering is used as a condition to narrow the phase shift angle search interval, determining the feasible region of the phase shift angle from the search interval. Safety protection triggering is also used as a search exit condition, searching for the optimal phase shift angle from the feasible region. Whether safety protection is triggered depends on the decreasing protection threshold during stable operation, J_filt, and J_fast. J_filt and J_fast are the slow and fast filtering results of J, respectively, where J is the sum of squares of the AC pulsation components extracted based on the deviation. The optimal phase shift angle obtained through optimization is used to generate a modulation factor. This modulation factor, along with the output of the synchronized power factor correction method, generates a q-axis current command to suppress compressor speed pulsation.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores one or more programs, the one or more programs including instructions that, when executed by a computing device, cause the computing device to perform the method of any one of claims 1 to 6, 8.

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