Single-period delay compensation method and device for magnetic suspension bearing switch power amplifier

Abstract

The invention belongs to the technical field of active magnetic suspension bearings, and discloses a single-cycle delay compensation method and device for a magnetic suspension bearing switch power amplifier, and the method comprises the steps: building a unipolar single-cycle control mathematical model, and calculating the duty ratio of a single cycle; setting a state switching criterion of a charging and discharging period, and judging a charging and discharging state of a single period; and establishing a linear duty ratio prediction model, calculating a linear derivation duty ratio dt and a calculation duty ratio dj to obtain a total duty ratio of a corresponding switch tube in a period, and outputting the total duty ratio to the corresponding switch tube. According to the method, target tracking can be achieved under the static condition, steady-state errors do not exist, and the problem that time delay exists in a traditional digital single-cycle control algorithm can be effectively solved under the dynamic condition.

Description

Technical Field

[0001] The present invention belongs to the technical field of active magnetic bearings, and particularly relates to a single-cycle delay compensation method and device for a magnetic bearing switching power amplifier. Background Art

[0002] When the rotor deviates due to external disturbances, the power amplifier needs to switch the current polarity and adjust the amplitude within microseconds, so that the direction of the electromagnetic force is opposite to the displacement deviation, forming a closed-loop suppression effect. This process requires the amplifier to have a high bandwidth to match the regulation frequency of the controller, and at the same time, it is necessary to ensure high linearity and low ripple of the current output to avoid high-frequency oscillations of the rotor caused by electromagnetic force pulsation.

[0003] At present, the mainstream scheme of the power amplifier adopts a full-bridge topology structure, realizes the output of positive and negative bus voltages through the symmetric design of the H-bridge, supports bidirectional continuous adjustment of the current, and the dynamic response time can be shortened to the microsecond level; it has 8 working modes, and the current ripple can be greatly reduced through the three-level modulation strategy. In addition, compared with the multi-bridge arm parallel topology, the system has higher reliability and is particularly suitable for fields with strict requirements on the failure rate. However, there are still problems that the system error cannot converge quickly and the response speed cannot be solved.

[0004] The Chinese patent publication number is CN118157526A, and the name of the patent application is a permanent magnet synchronous motor control method based on an improved linear hyperhelix. By establishing a two-phase stationary coordinate system, the stator current equation is obtained, the mechanical motion equation of the permanent magnet synchronous motor is established, the state variables of the permanent magnet synchronous motor system are defined, an integral sliding mode surface is established, and an approaching law speed controller is constructed. An improved linear hyperhelix sliding mode observer is established to estimate the back electromotive force, and the rotor speed and rotor position of the permanent magnet synchronous motor are calculated. This method is improved on the basis of the linear hyperhelix sliding mode observer. When the system error increases, the sliding mode gain can be adjusted according to the system error, and it can realize accurate estimation of the motor speed without using a low-pass filter and improve its anti-interference ability. However, this patent application cannot achieve rapid convergence of the system error and cannot solve the problem of slow response speed. Summary of the Invention

[0005] In order to overcome the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a single-cycle delay compensation method and device for a magnetic bearing switching power amplifier. Considering the coil resistance voltage drop, the digital single-cycle control algorithm is optimized, the mathematical model of the precise algorithm is clarified, the judgment criterion for the charge and discharge cycle is defined, the delay under the digital single-cycle control algorithm is estimated based on the control principle, a linear duty cycle prediction model is constructed, the duty cycle of the current cycle is predicted by extrapolating the duty cycles of the previous two cycles, and an equilibrium coefficient is introduced to optimize the prediction weight.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a single-cycle delay compensation method for a switched power amplifier of a magnetic levitation bearing, including the following steps: Collect circuit data, where the circuit data includes: coil current i0 at the initial moment of a single cycle, current reference value i ref , bus voltage U dc , period T s , load R, and inductance L; Establish a single-polarity single-cycle control mathematical model and calculate the duty cycle of a single cycle; Set the state switching criterion for the charge and discharge cycle and judge the charge and discharge state of a single cycle; Establish a linear duty cycle prediction model, and obtain the total duty cycle of the corresponding switch tube within the period by calculating the linearly derived duty cycle d t and the calculated duty cycle value d j , and output the total duty cycle to the corresponding switch tube.

[0007] Optionally, the single-polarity single-cycle control mathematical model is: when i0 < iref, d = ; when i0 ≥ iref, d = ; where: L is the inductance of the magnetic levitation bearing coil; R is the resistance of the magnetic levitation bearing coil; i ref is the current given reference value; i0 is the initial value of the single-cycle coil feedback current; T s is the single-cycle duration, and U dc is the bus voltage.

[0008] Optionally, the state switching criterion for the charge and discharge cycle is: when i0 < , the coil should be in the charging state during this cycle; when i0 ≥ , the coil should be in the discharging state during this cycle; where i0 is the initial value of the single-cycle coil feedback current; i ref is the current given reference value; L is the inductance of the magnetic levitation bearing coil; R is the resistance of the magnetic levitation bearing coil; and T is the sampling period.

[0009] Optionally, the linear duty cycle prediction model is: ; in the formula: is the predicted duty cycle; the equalization coefficient a, 0.05 < a < 0.4; d t is the linearly derived duty cycle; d j is the calculated duty cycle value.

[0010] Optionally, the calculation formula for the linearly derived duty cycle d t is: ; in the formula: is the linearly derived duty cycle of the nth cycle; is the predicted duty ratio of the (n - 1)th cycle; is the predicted duty ratio of the (n - 2)th cycle.

[0011] Optionally, the formula for calculating the duty ratio value d j is: When i0 < , dj = ; When i0 ≥ , dj = ; In the formula: i0 is the initial value of the single - cycle coil feedback current; i ref is the current given reference value; L is the inductance of the magnetic levitation bearing coil; R is the resistance of the magnetic levitation bearing coil; T is the sampling period.

[0012] In a second aspect, the present invention provides a single - cycle delay compensation system for a magnetic levitation bearing switching power amplifier, including: A data acquisition module, configured to acquire circuit data, where the circuit data includes: the coil current i0 at the initial moment of a single cycle, the current reference value i ref , the bus voltage U dc , the period T s , the load R, and the inductance L; A model establishment module, configured to establish a unipolar single - cycle control mathematical model and calculate the duty ratio of a single cycle; A rule setting module, configured to set the state switching criterion for the charge - discharge cycle and judge the charge - discharge state of a single cycle; A prediction module, configured to establish a linear duty ratio prediction model, and obtain the total duty ratio of the corresponding switching tube within a cycle by calculating the linearly derived duty ratio d t and the calculated duty ratio value d j ; An output module, configured to output the total duty ratio to the corresponding switching tube.

[0013] In a third aspect, the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, where when the processor executes the computer program, the single - cycle delay compensation method for the magnetic levitation bearing switching power amplifier is implemented.

[0014] In a fourth aspect, the present invention provides a computer - readable storage medium, where the computer - readable storage medium stores a computer program, and when the computer program is executed by a processor, the single - cycle delay compensation method for the magnetic levitation bearing switching power amplifier is implemented.

[0015] Fifth aspect, the present invention provides a computer program product including a computer-readable medium, on which computer-readable program code is included, and the program code executes the single-cycle delay compensation method of the switched power amplifier for the magnetic levitation bearing.

[0016] Compared with the prior art, the present invention has the following beneficial effects: In view of the problems that the duty cycle definition of the charge and discharge cycles in the traditional digital single-cycle control algorithm is relatively cumbersome, the judgment criterion for the charge and discharge cycles is not accurate enough, and there is a delay in current tracking, the digital single-cycle control algorithm is optimized considering the coil resistance voltage drop, the mathematical model of the algorithm is refined, the judgment criterion for the charge and discharge cycles is clarified, the delay under the digital single-cycle control algorithm is estimated based on the control principle, a linear duty cycle prediction model is constructed, the duty cycle of the current cycle is predicted by extrapolating the duty cycles of the previous two cycles, and an equilibrium coefficient is introduced to optimize the prediction weight.

[0017] The present invention can achieve the tracking target under static conditions without steady-state error. Under dynamic conditions, the improved algorithm can effectively reduce the problem of time delay existing in the traditional digital single-cycle control algorithm. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the disclosure of the present invention in any way.

[0019] In the drawings: Figure 1 is a block diagram of the switched power amplifier control system for a single-degree-of-freedom magnetic levitation bearing.

[0020] Figure 2 is a schematic diagram of the topology of a single-phase full-bridge switched power amplifier; Figure 3 is a schematic diagram of the positive charging cycle of unipolar control; Figure 4 is a schematic diagram of the positive discharging cycle of unipolar control; Figure 5 is a schematic diagram of the full freewheeling cycle of unipolar control; Figure 6 is a schematic diagram of the delay of the tracking current; Figure 7 is a schematic diagram of the ideal situation of current tracking; Figure 8 is a schematic diagram of duty cycle prediction; Figure 9 is a schematic diagram of the actual current oscillation; Figure 10 is a schematic diagram of the actual current i of the single-cycle digital control algorithm based on duty cycle prediction and the actual current i0 of the traditional algorithm when tracking a step signal with an amplitude of 3A; Figure 11 It is a schematic diagram of the actual current i of a single - cycle digital control algorithm based on duty - cycle prediction and the actual current i0 of a traditional algorithm when tracking a step signal with an amplitude of 3A. Specific implementation manners

[0021] In order to enable those skilled in the art of the present technology to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0023] It should be noted that in the claims, any reference signs between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in the claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The present application can be implemented by means of hardware including several different elements and by means of a suitably programmed computer. In the unit claims listing several means, several of these means can be embodied by the same item of hardware. The use of the words first, second, and third, etc. does not denote any order. These words can be interpreted as names. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, "a plurality of" means two or more unless otherwise specifically defined. The present invention will be described in detail below in conjunction with the accompanying drawings.

[0024] A single - cycle delay compensation method for a switched - mode power amplifier of a magnetic levitation bearing in the present invention includes the following steps: Collect circuit data, where the circuit data includes: the coil current i0 at the initial moment of a single cycle, the current reference value i ref , and the bus voltage U dc, period T s , load R and inductance L; Establish a unipolar single-cycle control mathematical model and calculate the duty cycle of a single cycle; Set the state switching criterion for the charge and discharge cycle and judge the charge and discharge state of a single cycle; Establish a linear duty cycle prediction model and calculate the duty cycle d through linear derivation t and calculate the duty cycle value d j Obtain the total duty cycle of the corresponding switching tube within the period and output the total duty cycle to the corresponding switching tube.

[0025] Specifically, the actual current i in the detection and sampling coil is detected by a current sensor, and the result is subtracted from the reference current and input into the controller. The controller uses the single-cycle control principle according to the difference to calculate the conduction state and duty cycle of the four switching tubes, generate the PWM wave of the corresponding switching tube, and then output it to the switching tube in the magnetic bearing switch power amplifier.

[0026] In view of the problems that the definition of the duty cycle of the charge and discharge cycle in the traditional digital single-cycle control algorithm is relatively cumbersome, the judgment criterion of the charge and discharge cycle is not accurate enough, and there is a delay in current tracking, the digital single-cycle control algorithm is optimized considering the coil resistance voltage drop, the mathematical model of the algorithm is refined, the judgment criterion of the charge and discharge cycle is clarified, the delay under the digital single-cycle control algorithm is estimated based on the control principle, a linear duty cycle prediction model is constructed, the duty cycle of the current cycle is predicted by extrapolating the duty cycles of the previous two cycles, and an equilibrium coefficient is introduced to optimize the prediction weight.

[0027] The present invention can achieve the tracking target under static conditions without steady-state error. Under dynamic conditions, the improved algorithm can effectively reduce the problem of time delay existing in the traditional digital single-cycle control algorithm.

[0028] Embodiment 1 Figure 1 It is the control system framework diagram of a single-degree-of-freedom magnetic bearing switch power amplifier. This system is mainly composed of a controller, a switch power amplifier, and a current sensor. Among them, the current sensor is responsible for detecting and sampling the actual current in the coil, and the result is subtracted from the reference current and input into the controller. The controller uses the single-cycle control principle according to the interpolation to calculate the conduction timing and time of the four switching tubes, and then generates the corresponding switching signals. As the main circuit, the switch power amplifier will control the corresponding switching tubes according to these switching signals to achieve the dynamic regulation of the current in the magnetic suspension bearing coil.

[0029] The topology structure of the main power is selected as the single-phase full-bridge switch power amplifier topology. The full-bridge topology can achieve three-level control of the electromagnetic bearing, with small output ripple and good tracking performance. Its specific topology structure is as Figure 2As shown. The single-cycle control of the switched power amplifier for the magnetic levitation bearing is divided into two methods: bipolar control and unipolar control. There is no freewheeling process in bipolar control, the algorithm is relatively simple, the execution efficiency of the program is relatively high, but the output current ripple is relatively large; there is a freewheeling process in unipolar control, the switching loss of the system is small, and the output current ripple is also small.

[0030] The waveforms under the single-cycle unipolar algorithm control are as Figure 3 shown. From top to bottom, they are the trigger pulse of the switching period, the overlapping triangular wave, the conduction duty cycle waveform, and the current waveform in the coil. In the figure, T M is the switching period of the digital single-cycle control, T on is the duration of the positive conduction state in each cycle, d is the duty cycle of the coil conduction state, cnt is the peak value of the overlapping triangular wave, and i is the current in the control coil of the magnetic levitation bearing.

[0031] During the positive charging period of the single-cycle unipolar control, M4 is always on, and M1 and M2 are complementary on. When M1 is on, the voltage across the coil is a positive voltage and the current rises. When M2 is on, the voltage across the coil is 0, and the current slowly decreases due to the existence of the coil resistance.

[0032] When t0 < t < t1, the duty cycle waveform is 0, the coil is in the freewheeling state, the switching tubes M2 and M4 are on, and M 1, M3 is off. The state equation of the coil current is Equation 1 In the formula, L is the inductance of the magnetic levitation bearing coil; R is the resistance of the magnetic levitation bearing coil; i is the current in the magnetic levitation bearing coil.

[0033] Substitute , , and the coil current expression can be obtained as Equation 2 According to Taylor's formula, Equation 2 can be transformed into Equation 3 From Figure 3 it can be known that Equation 4 The current change from t0 to t1 is Equation 5 Substitute Equation 3 and Equation 4 into Equation 5, and we can get Equation 6 When t1 < t < t2, the duty cycle waveform is 1, the coil is in the positive conduction state, the switching tubes M1 and M4 are on, and M2 and M3 are off. The state equation of the coil current is Equation 7 In the equation, U dc is the DC bus voltage.

[0034] Substituting i(t1) = i1 and i(t2) = i2, the time-domain expression of the coil current can be obtained Equation 8 According to Taylor's formula, Equation 8 can be transformed into Equation 9 From Figure 3 it can be known that Equation 10 The current change from t1 to t2 is Equation 11 Substituting Equation 9 and Equation 10 into Equation 11, we can get Equation 12 When t2 < t < t3, the duty cycle waveform is 0, the coil is in the freewheeling state, the switching transistors M2 and M4 are conducting, and M1 and M3 are turned off. The working state is the same as that in the initial freewheeling stage. Then the current change from t2 to t3 is Equation 13 The total current change in the positive charging cycle of the single-cycle single-polarity control is Equation 14 If it is selected that the current i3 tracks the reference value i ref at the end of each cycle, then the current change within one cycle is Equation 15 Combining Equation 14 and Equation 15, we can get Equation 16 In the switching power amplifier system, the switching frequency is relatively high, the current change within each cycle is relatively small, and the current change in the freewheeling state is almost 0. Therefore, it can be considered that i0 and i1 are approximately equal, and i2 and i3 are approximately equal, that is Equation 17 Equation 18 Substituting Equation 17 and Equation 18 into Equation 16, we can get Equation 19 During the positive discharging cycle of the single-cycle single-polarity control, M2 is always conducting, and M3 and M4 conduct complementarily. When M4 is conducting, the voltage across the coil is 0, and the current slowly decreases due to the existence of the coil resistance. When M3 is conducting, the voltage across the coil is the reverse voltage, and the current decreases. The waveform under the single-cycle single-polarity algorithm control is as shown in Figure 4As shown. From top to bottom are the trigger pulse of the switching period, the overlapping triangular wave, the conduction duty cycle waveform, and the current waveform in the coil. In the figure, T s , T on , d, cnt, i are defined in the same way as the charging period.

[0035] The waveforms under single-cycle single-polarity algorithm control are as Figure 3 shown. From top to bottom are the trigger pulse of the switching period, the overlapping triangular wave, the conduction duty cycle waveform, and the current waveform in the coil. In the figure, T M is the switching period of digital single-cycle control, T on is the duration of the forward conduction state in each period, d is the duty cycle of the coil conduction state, cnt is the peak value of the overlapping triangular wave, and i is the current in the magnetic levitation bearing control coil.

[0036] When t0 < t < t1, the duty cycle waveform is 0, the coil is in the freewheeling state, the switching tubes M2, M4 are on, and M1, M3 are off. The freewheeling state is the same as the freewheeling stage of the forward charging period, so the current change from t0 to t1 is Equation 20 When t1 < t < t2, the duty cycle waveform is 1, the coil is in the reverse conduction state, the switching tubes M2, M3 are on, and M1, M4 are off. The state equation of the coil current is Equation 21 Substituting i(t1) = i1 and i(t2) = i2, the time-domain expression of the coil current can be obtained Equation 22 According to Taylor's formula, Equation 22 can be transformed into Equation 23 From Figure 4 it can be seen that Equation 24 The current change from t1 to t2 is Equation 25 Substituting Equation 23 and Equation 24 into Equation 25, we can get Equation 26 When t2 < t < t3, the duty cycle waveform is 0, the coil is in the freewheeling state, the switching tubes M2, M4 are on, and M1, M3 are off. The working state is the same as the initial freewheeling stage, so the current change from t2 to t3 is Equation 27 The total current change in the forward charging period of single-cycle single-polarity control is Equation 28 If the current i3 is tracked to the reference value i at the end of each period ref , by combining Equation 28 and Equation 15, we can obtain Equation 29 Considering that the switching frequency in the switching power amplifier system is relatively high and the change in current within each period is relatively small, and the change in current during the freewheeling state is almost zero. Substituting Equation 17 and Equation 18 into Equation 29, we can obtain Equation 30 As can be seen from Equation (19) and Equation (30), at the initial moment of each period, only by sampling the initial value of the feedback current, the bus voltage value, and the reference current value can the conduction duty cycle of this period be directly calculated, so that the actual current at the end of each period tracks the reference current value.

[0037] Under the single-cycle digital control algorithm, i at the starting moment of each period ref and i0 determine whether this period is in the charging state or the discharging state, and then the control algorithm calculates the duty cycle according to i ref and i0 to control the conduction and turn-off of the switching tube. The traditional calculation method is to directly compare the magnitudes of i ref and i0 to determine the state of this period. However, due to the existence of the coil resistance, when the conduction duty cycle is 0, the current in the coil will freewheel from i0 to a fixed value i0 within one period * , as follows Figure 5 shown. Therefore, the judgment condition for the charge-discharge period is related to this fixed value i0 * .

[0038] When t0 < t < t1, the duty cycle waveform is 0, the coil is in the freewheeling state, and the state equation of the coil current is Equation 31 From Figure 5 we know Equation 32 Substituting into , , and combining with the Taylor formula, we calculate Equation 33 Then when i0 * < i ref , that is Equation 34 the coil should be in the charging state during this period; When i0 * > i ref , that is Equation 35 The coil should be in a discharging state during this period.

[0039] The mathematical model of the single-cycle single-polarity control algorithm is updated to Equation 36 According to the single-cycle control principle, the coil current of the magnetic levitation bearing is consistent with the starting given value at the end of the cycle, which causes the actual current to lag behind the given current, indicating that there is a delay in the switch power amplifier control system under digital single-cycle control. This delay seriously affects the performance of the power amplifier. It causes a time deviation in signal transmission, reduces indicators such as bandwidth and gain. Especially when processing high-frequency signals, the output signal is distorted, the frequency response deteriorates, and it is difficult to meet the high-precision requirements. Facing a rapidly changing input signal, the system response is sluggish, the dynamic performance declines, and overshoot and oscillation are likely to occur, affecting stability and reliability. Moreover, due to the delay, the power consumption of the power amplifier increases and the efficiency decreases, and it may also cause heating, threatening the stability and life of the system. When the degree of delay deepens, the stability of the system is more severely damaged. The phase lag and gain change weaken the stability margin, resulting in system oscillation and out-of-control, and ultimately leading to the instability of the magnetic levitation bearing control system. To solve these problems and expand the stability domain and enhance reliability, it is necessary to study the delay existing in the system. On the one hand, it is necessary to analyze the control algorithm to find out the key delay factors; on the other hand, it is necessary to establish an accurate compensation model to achieve efficient and stable operation.

[0040] In the single-cycle control of the magnetic levitation switch power amplifier, to compensate for the delay of the switch power amplifier control system of the magnetic levitation bearing, the primary task is to clarify the delay existing in the system. In the case of digital single-cycle control, the delay of this system mainly includes the delay of AD conversion, the delay of algorithm calculation, the delay caused by the control algorithm, and the delay of the circuit. Among them, the delay T caused by the control algorithm c far exceeds the other three parts. Because it is set that the current should track the reference value i at the end of each cycle ref , so the delay caused by the control algorithm is equal to the switching period, that is, T c = T s .

[0041] The delay caused by the single-cycle control algorithm is equal to the switching period, that is, T c = T s , and the schematic diagram is as follows Figure 6 as shown. The figure shows the current waveform of the single-cycle control tracking a sine signal. i ref represents the given current waveform, i represents the actual current waveform, and i1 represents the fundamental wave of the actual current waveform i.

[0042] The duty cycle predictive control linearly derives the duty cycle d of the current cycle using the coil conduction duty cycles of the previous two cycles t, to compensate for the delay of the control loop. However, it is impossible for the predicted duty cycle to be exactly the same as the ideal duty cycle in this period. Therefore, the duty cycle d calculated from the reference current and the actual current in this period should also be added. j , to make up for the problem of insufficient accuracy of the predicted duty cycle. In this way, the total predicted duty cycle is Equation 37 In this way, the predicted duty cycle includes two parts. One part is d linearly derived from the duty cycles of the previous two periods t , mainly used to compensate for the delay. The other part is the duty cycle value d calculated from the difference between the reference current and the actual current , mainly used to make up for the prediction difference in the previous period. In ideal prediction, the calculated duty cycle value d j should be as small as possible, indicating that the derived duty cycle d j is relatively accurate. In this way, if the predicted duty cycle t is equal to the ideal duty cycle, the delay of the system control loop can be completely compensated. The ideal schematic diagram is as follows shown. Figure 7 d t is linearly derived from the duty cycles of the previous two periods. However, whether it is the coil conduction duty cycle during the discharge period or the charging period, it is between 0 and 1, and the numerical value of the duty cycle cannot distinguish whether the coil is in the charging period or the discharge period. It is necessary to perform positive and negative conversion on the conduction duty cycle to distinguish the charge and discharge states of the coil. Define as the linear conduction duty cycle of the coil. When in the forward charging state , it is a positive value from 0 to 1; when in the forward discharge state , it is a negative value from -1 to 0. In this way, The expression of Equation 38 When the linear conduction duty cycle of the coil in a period is -1, the coil is in the full discharge state; when the linear conduction duty cycle of the coil in a period is greater than -1 and less than 0, the coil is in the partial discharge state in this period, and the current change amount decreases with the decrease of ; when the linear conduction duty cycle of the coil in a period is 0, the coil is in the full freewheeling state; when the linear conduction duty cycle of the coil in a period is greater than 0 and less than 1, the coil is in the partial charging state in this period, and the current change amount increases with the increase of ; when the linear conduction duty cycle of the coil in a period is 1, the coil is in the full charging state. Since the current change amount during the freewheeling state of the coil in each period is small and can be ignored compared with the charge and discharge current change amounts, it can be considered that the coil current change amount is proportional to the linear conduction duty cycle. ​

[0043] In this way, the duty cycle d is calculated j The relationship with the duty cycle of the coil's linear conduction should be Equation 39 Next, linear extrapolation is used to predict the duty cycle of the nth cycle, and the schematic diagram of the method is as shown Figure 8 as follows

[0044] Ts is the system switching period and also the sampling period. Let the duty cycle of the coil's linear conduction in the (n - 2)th cycle be , and let the duty cycle of the coil's linear conduction in the (n - 1)th cycle be . Using the linear extrapolation method, predict the duty cycle d of the coil's conduction in the nth cycle t n to satisfy Equation 40 That is Equation 41 In practice, if the predicted part d of the predicted duty cycle is not restricted, the actual current will oscillate around the reference current, as shown t above Figure 9 as follows

[0045] This phenomenon occurs because the unconstrained dt may cause overcompensation or undercompensation in the control loop, thus leading to unstable and oscillatory behavior during the current tracking process

[0046] To alleviate this problem, it is crucial to impose appropriate constraints on the predicted duty cycle d t to ensure that it remains within a reasonable range and meets the stability requirements of the system. This method helps to maintain smooth current tracking and prevent adverse oscillation conditions. An equilibrium coefficient a is introduced to solve the over-reliance on the derivation part d of the predicted duty cycle . According to multiple verifications through simulation, the equilibrium coefficient a is generally more suitable to be taken between 0.05 - 0.4. The formula for the updated predicted duty cycle t is as follows Equation 42 Embodiment 2 Perform a simulation analysis on a single-cycle control delay compensation method of the present invention. Table 1 shows the specific parameters of the power amplifier

[0047] Table 1

[0048] To verify the superiority of the single-cycle digital control algorithm based on duty cycle prediction, a step signal simulation with an amplitude of 3A was given. The result is as follows Figure 10 In the figure, iref represents the given current, i represents the actual current of the single-cycle digital control algorithm based on duty cycle prediction, and i0 represents the actual current of the traditional algorithm; Tracking simulation analysis was carried out under a sine signal with an amplitude of 3A and a frequency of 500Hz. As shown in the following figure Figure 11 In the figure, iref represents the given current, i represents the actual current of the single-cycle digital control algorithm based on duty cycle prediction, and i0 represents the actual current of the traditional algorithm.

[0049] Compared with the traditional single-cycle digital control algorithm, the improved single-cycle algorithm has the following advantages: 1) The tracking target can be achieved under static conditions without steady-state error.

[0050] 2) Under dynamic conditions, the improved algorithm can effectively reduce the problem of time delay existing in the traditional digital single-cycle control algorithm.

[0051] Example 3 Based on the method of Example 1, a single-cycle delay compensation system for the switched power amplifier of a magnetic levitation bearing is disclosed, including: A data acquisition module for collecting circuit data, where the circuit data includes: the coil current i0 at the initial moment of a single cycle, the current reference value i ref , the bus voltage U dc , the period T s , the load R and the inductor L; A model establishment module for establishing a unipolar single-cycle control mathematical model and calculating the duty cycle of a single cycle; A rule setting module for setting the state switching criterion of the charge and discharge cycle and judging the charge and discharge state of a single cycle; A prediction module for establishing a linear duty cycle prediction model and obtaining the total duty cycle of the corresponding switch tube within the period by calculating the linearly derived duty cycle d t and calculating the duty cycle value d j ; An output module for outputting the total duty cycle to the corresponding switch tube.

[0052] Example 4 The purpose of this example is to provide an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the single-cycle delay compensation method for the switched power amplifier of the magnetic levitation bearing is implemented.

[0053] Example 5 The purpose of this embodiment is to provide a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements the single-cycle delay compensation method for the switched power amplifier of the magnetic levitation bearing.

[0054] Embodiment 6 The purpose of this embodiment is to provide a computer program product including a computer-readable medium, on which computer-readable program code is included. The program code executes the single-cycle delay compensation method for the switched power amplifier of the magnetic levitation bearing.

[0055] The steps involved in the devices in the above Embodiments 3, 4, 5, and 6 correspond to those in Method Embodiment 1. For specific implementation manners, reference may be made to the relevant description part of Embodiment 1.

[0056] Those skilled in the art of this technology should understand that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memories, CD-ROMs, optical memories, etc.) containing computer-usable program code. The present application is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram can be implemented by computer program instructions, and the combination of the flows and / or blocks in the flowchart and / or block diagram can also be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for implementing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks. These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device, and the instruction device implements the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks. These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus, causing a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, so that the instructions executed on the computer or other programmable apparatus provide steps for implementing the functions specified in one process or a plurality of processes and / or blocks Figure 1 one process or a plurality of processes and / or blocks Figure 1 or steps for implementing the functions specified in one block or a plurality of blocks.

[0057] In the above embodiments, the working mode or control mode involved, unless otherwise specified, is the conventional working mode or control mode in the art.

[0058] Although the preferred embodiments of the present application have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications falling within the scope of the present application. Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Other modifications or equivalent replacements made by those of ordinary skill in the art to the technical solutions of the present invention should be covered within the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solutions of the present invention.

Claims

1. A single-cycle delay compensation method for a switched power amplifier of a magnetic levitation bearing, characterized in that, Including the following steps: Collect circuit data, where the circuit data includes: coil current i0 at the initial moment of a single cycle, current reference value i ref , bus voltage U dc , period T s , load R, and inductor L; Establish a unipolar single-cycle control mathematical model and calculate the duty cycle of a single cycle; Set the state switching criterion for the charge and discharge cycle and judge the charge and discharge state of a single cycle; Build a linear duty cycle prediction model, and calculate the linearly derived duty cycle d t and calculate the duty cycle value d j Obtain the total duty cycle of the corresponding switching transistor within the period, and output the total duty cycle to the corresponding switching transistor.

2. The single-cycle delay compensation method for a switched power amplifier of a magnetic levitation bearing according to claim 1, wherein The unipolar single-cycle control mathematical model is: when i0 < iref, d = ; when i0 ≥ iref, d = ; where: L is the inductance of the magnetic levitation bearing coil; R is the resistance of the magnetic levitation bearing coil; i ref is the current given reference value; i0 is the initial value of the single-cycle coil feedback current; T s is the single-cycle duration, U dc is the bus voltage.

3. A single-cycle delay compensation method for a switched power amplifier of a magnetic levitation bearing, as claimed in claim 1, wherein The state switching criterion for the charge and discharge cycle is: when i0 < , the coil should be in the charging state during this cycle; when i0 ≥ , the coil should be in the discharging state during this cycle; where i0 is the initial value of the single-cycle coil feedback current; i ref is the current given reference value; L is the inductance of the magnetic levitation bearing coil; R is the resistance of the magnetic levitation bearing coil; T is the sampling period.

4. A single-cycle delay compensation method for a switched power amplifier of a magnetic levitation bearing, characterized in that, The linear duty cycle prediction model is as follows: ; where: is the predicted duty cycle; Balancing coefficient a, 0.05 < a < 0.4; d t is the linearly derived duty cycle; d j is the calculated duty cycle value.

5. A single-cycle delay compensation method for a switched power amplifier of a magnetic levitation bearing, characterized in that, The linear derivation duty cycle d t has the following calculation formula: ; where: is the duty cycle of the n-cycle linear derivation; is the predicted duty cycle of the (n - 1)th cycle; is the predicted duty cycle of the (n - 2)th cycle.

6. A single-cycle delay compensation method for a switched power amplifier of a magnetic levitation bearing, characterized in that, The calculation of the duty cycle ratio d j is given by the formula: When i0 < , dj = ; When i0 ≥ , dj = ; where: i0 is the initial value of the single-period coil feedback current; i ref is the current reference value; L is the inductance of the magnetic levitation bearing coil; R is the resistance of the magnetic levitation bearing coil; T is the sampling period.

7. A single-cycle delay compensation system for a switched power amplifier of a magnetic levitation bearing, characterized in that, Including: A data acquisition module, which is used to acquire circuit data, and the circuit data includes: coil current i0 at the initial moment of a single cycle, current reference value i ref , bus voltage U dc , period T s , load R, and inductance L; A model establishment module for establishing a unipolar single-cycle control mathematical model and calculating the duty cycle of a single cycle; A rule setting module for setting the state switching criterion for the charge and discharge cycle and judging the charge and discharge state of a single cycle; A prediction module, which is used to establish a linear duty cycle prediction model, and obtain the total duty cycle of the corresponding switching tube within a period by calculating the linearly derived duty cycle d t and calculating the duty cycle value d j ​ An output module for outputting the total duty cycle to the corresponding switching tube.

8. An electronic device, characterized in that, Including a memory, a processor, and a computer program stored in the memory and executable on the processor, and when the processor executes the computer program, it implements the single-cycle delay compensation method of the switched power amplifier of the magnetic levitation bearing according to any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, and when the computer program is executed by the processor, it implements the single-cycle delay compensation method of the switched power amplifier of the magnetic levitation bearing according to any one of claims 1-6.

10. A computer program product comprising a computer-readable medium, characterized in that, On the computer-readable medium, there is included computer-readable program code, and the program code executes the single-cycle delay compensation method of the switched power amplifier of the magnetic levitation bearing according to any one of claims 1-6.

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