Composite control structure based on repetitive control and iron loss test control system

Abstract

The present application relates to the technical field of repetitive control, in particular to a composite control structure based on repetitive control and an iron loss test control system. The composite control structure is connected in parallel with a PI controller and a repetitive controller, and controls the current according to a desired sinusoidal current signal and a load-side feedback current signal; and through a quasi-resonant controller combined with a PI controller based on a virtual axis, the third harmonic current of the fundamental wave in the load-side feedback current is suppressed, and finally the suppression effect of the harmonic in the load-side current is improved, so as to ensure the sinusoidal degree of the current. In the iron loss test control system, the composite control structure is used to ensure the measurement accuracy of the iron loss test control system.

Description

Technical Field

[0001] This invention relates to the field of repetitive control technology, specifically to a composite control structure based on repetitive control and an iron loss test control system. Background Technology

[0002] Repetitive control originates from the internal model principle in control theory, which states that if a stable closed-loop control system includes a mathematical model of the external input signal, the controlled output can track the reference signal without error. Since disturbances introduced by the dead zone and load in the system can be decomposed into a superposition of multiple harmonics, recurring within each fundamental cycle, adding an internal model to the system and designing a suitable compensator can suppress these disturbances. However, because the controlled system contains a dead zone and the load and current have a nonlinear relationship, if the system's output voltage is applied to the controlled object, the resulting current will have a high harmonic content and a high total harmonic distortion rate. Therefore, traditional single-structure repetitive controllers are not very effective at suppressing disturbances with high harmonic content. Summary of the Invention

[0003] In view of this, the present invention provides a composite control structure based on repetitive control and an iron loss test control system to solve the problem that the traditional single-structure repetitive controller has poor suppression effect on disturbance signals with high harmonic content.

[0004] According to a first aspect, embodiments of the present invention provide a composite control structure based on repetitive control, comprising: a repetitive controller, a first comparator, a first PI controller, a quasi-resonant controller, a second comparator, a first conversion module, a second PI controller, a second conversion module, and an adder, wherein,

[0005] The repetitive controller acquires the given current signal from the input side and the feedback current signal from the load side, generates a first difference signal through a first comparator, and generates a first voltage modulation signal based on the first difference signal.

[0006] The first PI controller is connected in parallel with the repetitive controller, and generates a second voltage modulation signal based on the first difference signal;

[0007] The quasi-resonant controller extracts the third harmonic current signal from the feedback current signal, transforms the third harmonic current signal through the first transformation module, and then generates a second difference signal based on the target harmonic current signal through the second comparator.

[0008] The second conversion module generates a third voltage modulation signal based on the second difference signal and controlled by the second PI controller.

[0009] The adder superimposes the first voltage modulation signal, the second voltage modulation signal, and the third voltage modulation signal to obtain the total voltage modulation signal, so as to suppress the disturbance signal generated by the controlled object and thereby improve the sinusoidal nature of the current in the load.

[0010] In one optional implementation, the first transformation module includes a phase shifter and a Park converter, wherein the phase shifter shifts the third harmonic current signal by a preset angle to generate a second current signal of the first axis, and the unshifted third harmonic current signal serves as the first current signal of the first axis; the Park converter transforms the first current signal and the second current signal to generate a third current signal of the second axis and a fourth current signal of the second axis.

[0011] In one alternative implementation, the second PI controller acquires a third difference signal between the third current signal and the first target harmonic current signal, and a fourth difference signal between the fourth current signal and the second target harmonic current signal.

[0012] In one optional implementation, the second conversion module includes a Park inverse converter, which inversely converts the first and second correction voltage signals processed by the second PI controller to generate a third voltage modulation signal.

[0013] In one optional implementation, the repetitive controller includes: a third comparator, a low-pass filter, a periodic delay element, and a compensator, wherein the low-pass filter is used to reduce the proportion of the previous cycle error in the current cycle control based on a first difference signal and a first control signal generated by combining the low-pass filter with the periodic delay element.

[0014] The third comparator generates a second control signal based on the first control signal and the first difference signal; the compensator receives the second control signal through a periodic delay element and performs compensation processing on the second control signal.

[0015] In one alternative implementation, the compensator compensates for the second control signal using the following formula: C(z) = K r z k Where C(z) is the compensator, K r For the gain of the repetitive controller, z k As a leading element; the mathematical model of the repetitive controller is expressed by the following formula: Among them, G RC (z) is a repetitive controller, Q(z) is a low-pass filter, and z -N This is a periodic delay element.

[0016] In one alternative implementation, the transfer function of the first PI controller is expressed by the following formula: Among them, GPI (s) is the transfer function of the first PI controller, K P K is the proportional coefficient of the first PI controller. I The integral coefficient of the first PI controller.

[0017] In one alternative implementation, the quasi-resonant controller is expressed by the following formula: Among them, K q ω is the integral coefficient of the quasi-resonant controller. n It is the resonant frequency.

[0018] According to a second aspect, embodiments of the present invention also provide an iron loss testing and control system, comprising:

[0019] The iron loss test module includes: stator core and H-bridge inverter circuit;

[0020] The drive control module is connected to the iron loss test module;

[0021] The composite control structure in the first aspect or any embodiment of the first aspect is connected to the drive control module. The composite control structure is used to transmit the total voltage modulation signal it generates to the drive control module, and the drive control module then generates a voltage drive signal to drive the H-bridge inverter circuit to apply a control voltage to the load side.

[0022] In one alternative implementation, the stator core, with excitation coils wound around it, serves as the load of the iron loss test control system. The H-bridge inverter circuit is connected to the drive control module and is used to obtain voltage drive signals through the drive control module to apply voltage commands to the stator core, generate current signals on the load side, and reduce the total harmonic distortion rate in the load current.

[0023] The technical solution of this invention has the following advantages:

[0024] This invention discloses a composite control structure based on repetitive control and a control system for iron loss testing. This composite control structure uses a PI controller connected in parallel with a repetitive controller to control the current based on the desired sinusoidal current signal and the load-side feedback current signal. Furthermore, it uses a quasi-resonant controller combined with a virtual axis-based PI controller to suppress the third harmonic current of the fundamental wave in the load-side feedback current, ultimately improving the suppression effect on harmonics in the load-side current and ensuring the sinusoidal nature of the current. This composite control structure ensures the measurement accuracy of the iron loss testing control system. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the magnetic permeability versus magnetic field strength curve according to an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of a composite control structure based on repetitive control according to an embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of the repetitive controller structure according to an embodiment of the present invention;

[0029] Figure 4 This is a schematic diagram of a PI controller structure based on a repetitive controller according to an embodiment of the present invention;

[0030] Figure 5 This is a schematic diagram of the quasi-resonant controller and the PI controller based on the virtual axis system according to an embodiment of the present invention;

[0031] Figure 6 This is a schematic diagram of the iron loss test control system according to an embodiment of the present invention.

[0032] Figure label:

[0033] 20 - Repetitive controller; 21 - First comparator; 22 - First PI controller;

[0034] 23-Quasi-resonant controller; 24-Second comparator; 25-First conversion module;

[0035] 26-Second PI controller; 27-Second converter module; 28-Adder;

[0036] 201 - Third comparator; 202 - Low-pass filter; 203 - Periodic delay element;

[0037] 204 - Compensator; 251 - Phase Shifter; 252 - Park Converter;

[0038] 60 - Iron loss testing module; 61 - Drive control module; 62 - Composite control structure;

[0039] 601 - Load; 602 - H-bridge inverter circuit. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Permanent magnet synchronous motors (PMSMs) are widely used as drive motors in electric vehicles due to their small size, high efficiency, and high power density. To further improve the performance of PMSMs, research on their losses has become a hot topic. Stator core loss is one of the main sources of motor losses. Especially considering the problem of high stator core losses during manufacturing, detecting stator core losses before the motor is completed can save both time and cost.

[0042] To detect stator core losses, an excitation coil needs to be wound around a toroidal core. A sinusoidal current at a target frequency is applied to the coil, and the stator core losses under that magnetic field are measured based on the generated sinusoidal magnetic field. To ensure measurement accuracy, the sinusoidal current in the coil must have a certain degree of sinusoidality.

[0043] An excitation coil is wound around a toroidal iron core, and a sinusoidal current is applied to the coil. The iron core and the coil under test can be regarded as a single inductor under test, and its equivalent inductance value is affected by the permeability of the soft magnetic material used in the iron core. Taking the commonly used soft magnetic material B30AV1500 as an example, its permeability versus magnetic field strength curve is shown below. Figure 1 As shown,

[0044] Because the permeability μ of soft magnetic materials decreases rapidly with increasing magnetic field strength H, the inductance L of the measured coil decreases. s The equivalent inductance decreases rapidly with increasing current amplitude, exhibiting a non-linear relationship with the current. Due to the presence of a dead zone in the system and the non-linear relationship between the load and current, the current generated by the inverter output voltage applied to the measured coil has a high harmonic content, resulting in a high total harmonic distortion (THD) rate. To ensure the sinusoidal nature of the current, a composite control structure based on repetitive control is proposed to reduce the THD rate.

[0045] According to embodiments of the present invention, a composite control structure based on repetitive control is provided, such as... Figure 2 As shown, the composite control structure includes: a repetitive controller 20, a first comparator 21, a first PI controller 22, a quasi-resonant controller 23, a second comparator 24, a first conversion module 25, a second PI controller 26, a second conversion module 27, and an adder 28.

[0046] The repetitive controller 20 acquires the given current signal from the input side and the feedback current signal from the load side, generates a first difference signal through the first comparator 21, and generates a first voltage modulation signal based on the first difference signal. The first PI controller 22 is connected in parallel with the repetitive controller 20 and generates a second voltage modulation signal based on the first difference signal. The quasi-resonant controller 23 extracts the third harmonic current signal from the feedback current signal, transforms the third harmonic current signal through the first conversion module 25, and then generates a second difference signal based on the target harmonic current signal through the second comparator 24. The second conversion module 27 generates a third voltage modulation signal based on the second difference signal and is controlled by the second PI controller 26. The adder 28 superimposes the first voltage modulation signal, the second voltage modulation signal, and the third voltage modulation signal to obtain a total voltage modulation signal to suppress the disturbance signal generated by the controlled object 29.

[0047] Specifically, the given current signal is a sinusoidal current signal given on the input side, and the feedback current signal is an AC signal fed back from the load side. Figure 2 In the middle, G RC (z) represents the repetitive controller 20, G PI (z) represents the first PI controller 22, G QR (z) is the quasi-resonant controller 23, i s_ref Given a sinusoidal current signal, i s U is the load-side feedback current, e is the first differential signal, and U is the load-side feedback current. PI_ref U is the second voltage modulation signal output by the first PI controller 22. RC_ref U is the first voltage modulation signal output by the repetitive controller 20. 3rd_ref It is the third voltage modulation signal for the third harmonic suppression voltage.

[0048] exist Figure 2 In this embodiment, the composite control structure based on repetitive control mainly includes two parts: one is a parallel PI controller and a repetitive controller, which control the current according to the desired sinusoidal current signal and the load-side feedback current signal; the other is a quasi-resonant controller combined with a virtual axis-based PI controller, which suppresses the third harmonic current of the fundamental wave in the load-side feedback current.

[0049] The specific control logic is as follows: use the desired sinusoidal current command i s_ref AC current i on the load side s The difference is calculated to obtain the first difference signal (current difference e). This first difference signal is used as the input to the PI controller to obtain the voltage modulation signal U output by the PI controller. PI_ref Simultaneously, the current difference is used as the input to the repetitive controller to obtain the voltage modulation signal U output by the repetitive controller. RC_ref The third harmonic component i in the AC current on the load side is extracted using a quasi-resonant controller.s_3rd , change i s_3rd As i α_3rd , for i s_3rd Phase shift of 90° yields i β_3rd , for i αβ_3rd Perform the Park transformation to obtain the current component i in the dq axis system. dq_3rd In the dq axis system, respectively, the desired current command i is... dq_ref The difference is calculated, and the difference is used to obtain a voltage signal u through a PI controller. dq_ref Then, the third harmonic compensation voltage modulation signal U is obtained through the inverse Park transform. 3rd_ref The voltage modulation signal U mentioned above PI_ref U RC_ref and U 3rd_ref The superimposed signals are used as the total voltage modulation signal.

[0050] Specifically, repetitive control originates from the internal model principle in control theory, which states that if a stable closed-loop control system includes a mathematical model of the external input signal, the controlled output can track the reference signal without error. Since the disturbance signals introduced by the dead zone and load in the system can be decomposed into the superposition of multiple harmonics, which recur in each fundamental frequency cycle, the disturbance signals can be suppressed by adding an internal model to the system and designing a suitable compensator.

[0051] The mathematical model of the sine function is:

[0052]

[0053] Where, ω e Since the angular frequency of the sinusoidal signal is periodic, it can be represented by the following internal mode form;

[0054]

[0055] In equation (2) above, L is the period of the given signal, and its discrete domain can be expressed as:

[0056]

[0057] In equation (3), N is the number of samplings in one fundamental frequency period, z -N Let be the z-transform operator; Equation (3) is the idealized integral without steady-state error.

[0058] In one alternative implementation, the mathematical model of the repetitive controller is expressed by the following formula:

[0059]

[0060] Among them, G RC (z) is a repetitive controller, Q(z) is a low-pass filter, and z -NThis is a periodic delay element. Equation (4) can be considered as an improved internal model. Q(z) can be a low-pass filter or a constant slightly less than 1 to weaken the integration effect.

[0061] In one alternative implementation, such as Figure 3 As shown, the repetitive controller 20 includes: a third comparator 201, a low-pass filter 202, a period delay element 203, and a compensator 204, wherein,

[0062] The low-pass filter 202 is based on the first difference signal and the first control signal generated by the combination of the low-pass filter 202 and the period delay element 203, which is used to reduce the proportion of the previous cycle error in the current cycle control.

[0063] The third comparator 201 generates a second control signal based on the first control signal and the first difference signal; the compensator 204 receives the second control signal through the period delay element 203 and performs compensation processing on the second control signal.

[0064] In one alternative implementation, the compensator compensates the second control signal using the following formula:

[0065] C(z)=K r z k (5)

[0066] Where C(z) is the compensator, K r For the gain of the repetitive controller, z k This is an advanced stage.

[0067] exist Figure 3 The diagram below shows the structure of repetitive control, where i s_ref Given a sinusoidal current signal, i s The actual feedback current is given, e is the first difference signal, and z is the actual feedback current. -N For periodic delay elements, C(z) is the compensator of the repetitive control loop, and P(z) is the controlled object.

[0068] In equation (5), K r The gain for repetitive control is used to control the intensity of the added compensation; in practical engineering applications, it is usually taken as a positive constant less than 1. A larger value for K is chosen. r This will reduce the steady-state error but weaken the system stability; therefore, a smaller K should be chosen. r It will increase system error, but at the same time it will improve the stability and robustness of the system.

[0069] Based on the structure of the repetitive controller described above, a PI controller connected in parallel with the repetitive controller is further designed.

[0070] Repetitive control, due to the introduction of a periodic delay element, results in significant control lag and slow dynamic response. To improve the system's dynamic response, a control structure combining a PI controller and repetitive control in parallel is considered. For example... Figure 4 This is a schematic diagram of a PI parallel repetitive controller. The PI controller is... Figure 2 The first PI controller in the system.

[0071] In one alternative implementation, the transfer function of the first PI controller is expressed by the following formula:

[0072]

[0073] Among them, G PI (s) is the transfer function of the first PI controller, K P K is the proportional coefficient of the first PI controller. I The integral coefficient of the first PI controller.

[0074] The discretized form of equation (6) is shown in the following formula;

[0075]

[0076] Considering that the first PI controller and the repetitive controller are connected in parallel and do not affect each other, the PI controller and the controlled object can achieve zero-pole cancellation to obtain K. P / K I =L / R, ignoring the inverter model, the open-loop transfer function is as shown in the following formula;

[0077]

[0078] Therefore, the closed-loop transfer function is expressed by the following formula;

[0079]

[0080] Then the closed-loop bandwidth f of the system z This can be expressed by the following formula;

[0081]

[0082] According to K P / K I =L / R and the following formula yields the PI controller parameters;

[0083] In engineering practice, the closed-loop bandwidth is often taken as 1.1 to 1.4 times the open-loop cutoff frequency, while the open-loop cutoff frequency should not be greater than 1 / 10 of the switching frequency in order to suppress switching noise.

[0084] Furthermore, based on the parallel PI controller to repetitive controller, considering that the disturbances introduced by the dead zone and load in the system ultimately exist in the form of 3rd, 5th and 7th harmonics, with the 3rd harmonic having the highest content, a quasi-resonant controller is proposed to filter out harmonics of specific frequencies.

[0085] In one alternative implementation, the quasi-resonant controller is expressed by the following formula:

[0086]

[0087] Among them, K q ω is the integral coefficient of the quasi-resonant controller. n It is the resonant frequency.

[0088] The discretization equation of the quasi-resonant controller is obtained by discretizing equation (11) using the Tustin method (discretization transformation algorithm), as shown in the following formula;

[0089]

[0090] After extracting specific frequency harmonics using a quasi-resonant controller, a second PI controller is used to obtain the correction voltage corresponding to the harmonic current. Since the second PI controller can achieve zero steady-state error regulation of DC current, this embodiment uses a virtual axis-based method to obtain the DC current components in the rotating coordinate system and then controls them separately.

[0091] In one alternative implementation, such as Figure 5 As shown, the first transformation module 25 includes a phase shifter 251 and a Park converter 252. The phase shifter 251 shifts the third harmonic current signal by a preset angle to generate a second current signal of the first axis, and the unshifted third harmonic current signal serves as the first current signal of the first axis. The Park converter transforms the first current signal and the second current signal to generate a third current signal of the second axis and a fourth current signal of the second axis.

[0092] In one alternative implementation, in Figure 5 In the process, the second PI controller generates a first correction voltage based on the third difference signal between the third current signal and the first target harmonic current signal, and generates a second correction voltage based on the fourth difference signal between the fourth current signal and the second target harmonic current signal.

[0093] Specifically, in Figure 5 In this diagram, the first axis system is the α-β axis system, and the second axis system is the dq axis system. The first current signal is i. α_3rd The second current signal is i β_3rd The third current signal is i d_3rd The fourth current signal is iq_3rd The preset angle is 90°. The first target harmonic current signal is i. d_ref The second target harmonic current signal is i q_ref .

[0094] In one optional implementation, the second conversion module 27 includes a Park inverse converter 271, which inversely converts the first and second correction voltage signals generated by the second PI controller to generate a third voltage modulation signal.

[0095] exist Figure 5 The diagram below shows the structure of a virtual axis PI control system. In the diagram, G... PI (z) is a PI controller, G QR (z) is a quasi-resonant controller, i s For the load-side feedback current, i s_3rd For the third harmonic of the fundamental wave, i αβ_3rd Let i be the third harmonic current in the α-β axis system. dq_3rd Let i be the third harmonic current in the dq axis system. dq_ref For the current command in the dq axis system, U 3rd_ref It is a third harmonic suppression voltage modulation signal.

[0096] Specifically, a specific frequency harmonic current is obtained through a quasi-resonant controller, and the orthogonal current component is obtained by phase shifting the harmonic current by 90°. The DC current component i is then obtained through Park transform. d and i q The reference current value in the dq axis system is set to zero. The current error is then processed by a PI controller and inversely transformed by Park to obtain U. 3rd_ref , will U 3rd_ref The correction of specific frequency harmonic currents is achieved by superimposing the voltage command. The current difference is obtained from the desired sinusoidal current command and the feedback current. The current difference is passed through a parallel PI controller and repetitive control to obtain the command voltage command. At the same time, a quasi-resonant controller is used to extract the specific frequency harmonics in the feedback current and obtain the correction voltage through PI control based on a virtual axis system. The command voltage and the correction voltage are superimposed and applied to the controlled object.

[0097] The transfer function of the quasi-resonant controller is shown in the following formula. In order to flawlessly follow a harmonic signal of a specific frequency, the specific frequency is taken as the λ frequency, and the fundamental frequency is ω. e , then ω n =λω e Substituting into equation (11), we obtain the following formula;

[0098]

[0099] The amplitude expression is shown in the following formula;

[0100]

[0101] With the fundamental frequency signal amplitude less than X e Using this as a standard, we can obtain K. q The range of values ​​for is shown in the following formula;

[0102]

[0103] The composite control structure based on repetitive control in this embodiment controls the current by connecting a PI controller and a repetitive controller in parallel, based on the desired sinusoidal current signal and the load-side feedback current signal; and by combining a quasi-resonant controller with a virtual axis-based PI controller, the third harmonic current of the fundamental wave in the load-side feedback current is suppressed, which ultimately improves the suppression effect on the harmonic components in the load-side current, thereby ensuring the sinusoidality of the current.

[0104] Based on the same concept, this embodiment also provides an iron loss testing and control system, such as... Figure 6 As shown, it includes: an iron loss testing module 60, a drive control module 61, and the composite control structure 62 in the above embodiment. The iron loss testing module 60 is connected to the drive control module 61. The composite control structure 62 is used to transmit the total voltage modulation signal it generates to the drive control module 61. The drive control module 61 then generates a voltage drive signal to drive the H-bridge inverter circuit to apply a control voltage to the load side.

[0105] In one optional embodiment, the iron loss test module 60 includes a stator core (load 601) and an H-bridge inverter circuit 602. The stator core, with an excitation coil wound around it, serves as the load of the iron loss test control system. It is connected to a drive control module 61, which acquires a voltage drive signal to apply a voltage command to the stator core, generating a sinusoidal current signal on the load side and reducing the total harmonic distortion (THD) in the load current. Figure 6 This is a schematic diagram of an application scenario based on a composite control structure. The area within the dashed box in the diagram represents a single-phase full-bridge inverter circuit, also known as an H-bridge inverter circuit 602. RC (z) is a repetitive controller, G PI (z) is the first PI controller, G QR (z) is a quasi-resonant controller, i s_ref Given a sinusoidal current signal, i s Here, e is the load-side feedback current, and i is the first differential signal. s_3rd For the third harmonic of the fundamental wave, i αβ_3rd Let i be the third harmonic current in the α-β axis system. dq_3rd Let i be the third harmonic current in the dq axis system. dq_ref For the current command in the dq axis system, udq_ref For voltage commands in the dq axis system, U 3rd_ref U is a third harmonic suppression voltage modulation signal. PI_ref U is the voltage modulation signal output by the PI controller. RC_ref The repetitive controller outputs a voltage modulation signal.

[0106] The specific control logic is as follows: use the desired sinusoidal current command i s_ref AC current i on the load side s The difference is calculated to obtain the current difference value e. This current difference value e is used as the input to the PI controller to obtain the voltage modulation signal U output by the PI controller. PI_ref Simultaneously, the current difference is used as the input to the repetitive controller to obtain the voltage modulation signal U output by the repetitive controller. RC_ref The third harmonic component i in the AC current on the load side is extracted using a quasi-resonant controller. s_3rd , change i s_3rd As i α_3rd , for i s_3rd Phase shift of 90° yields i β_3rd , for i αβ_3rd Perform the Park transformation to obtain the current component i in the dq axis system. dq_3rd In the dq axis system, respectively, the desired current command i is... dq_ref The difference is calculated, and the difference is used to obtain a voltage signal u through a PI controller. dq_ref Then, the third harmonic compensation voltage modulation signal U is obtained through the inverse Park transform. 3rd_ref The voltage modulation signal U mentioned above PI_ref U RC_ref and U 3rd_ref The signals are superimposed and used as input to the drive control module (SPWM module) to obtain the switching transistor drive signal output by the SPWM module.

[0107] The composite control structure generates a total voltage modulation signal and transmits it to the drive control module. The drive control module generates a voltage drive signal and transmits it to the H-bridge inverter circuit. The H-bridge inverter circuit generates a given voltage signal and applies it to the stator core, causing a sinusoidal current signal to be generated on the load side. This improves the suppression effect on harmonics in the load side current and reduces the total harmonic distortion of the load current.

[0108] The iron loss test control system in this embodiment applies a composite control structure to a specific iron loss test control system to test the stator core loss. It controls the current based on the desired sinusoidal current signal and the load-side feedback current signal by connecting a PI controller and a repetitive controller in parallel. Furthermore, it suppresses the third harmonic current of the fundamental wave in the load-side feedback current by combining a quasi-resonant controller with a virtual axis-based PI controller, thereby ensuring the measurement accuracy of the iron loss test control system.

[0109] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A composite control structure based on repetitive control, characterized in that, include: The system comprises a repetitive controller, a first comparator, a first PI controller, a quasi-resonant controller, a second comparator, a first conversion module, a second PI controller, a second conversion module, and an adder, wherein... The repetitive controller acquires the given current signal from the input side and the feedback current signal from the load side, generates a first difference signal through a first comparator, and generates a first voltage modulation signal based on the first difference signal. The first PI controller is connected in parallel with the repetitive controller, and generates a second voltage modulation signal based on the first difference signal; The quasi-resonant controller extracts the third harmonic current signal from the feedback current signal, transforms the third harmonic current signal through the first transformation module, and then generates a second difference signal based on the target harmonic current signal through the second comparator. The second conversion module generates a third voltage modulation signal based on the second difference signal and controlled by the second PI controller; The adder superimposes the first voltage modulation signal, the second voltage modulation signal, and the third voltage modulation signal to obtain a total voltage modulation signal, thereby suppressing the disturbance signal generated by the controlled object and improving the sinusoidal nature of the current in the load.

2. The composite control structure according to claim 1, characterized in that, The first transformation module includes: a phase shifter and a Parker converter, wherein, The phase shifter shifts the third harmonic current signal by a preset angle to generate a second current signal for the first axis, and the unshifted third harmonic current signal serves as the first current signal for the first axis. The Park converter transforms the first current signal and the second current signal to generate a third current signal for the second axis and a fourth current signal for the second axis.

3. The composite control structure according to claim 2, characterized in that, The second PI controller generates a first correction voltage based on a third difference signal between the third current signal and the first target harmonic current signal, and generates a second correction voltage based on a fourth difference signal between the fourth current signal and the second target harmonic current signal.

4. The composite control structure according to claim 3, characterized in that, The second conversion module includes a Park inverse converter, which inversely converts the first correction voltage signal and the second correction voltage signal generated by the second PI controller to generate the third voltage modulation signal.

5. The composite control structure according to claim 1, characterized in that, The repetition controller includes: a third comparator, a low-pass filter, a period delay element, and a compensator, wherein... The low-pass filter is based on the first difference signal and the first control signal generated by combining the low-pass filter with the period delay element, and is used to reduce the proportion of the previous cycle error in the current cycle control. The third comparator generates a second control signal based on the first control signal and the first difference signal; The compensator receives the second control signal through the periodic delay element and performs compensation processing on the second control signal.

6. The composite control structure according to claim 5, characterized in that, The compensator compensates for the second control signal using the following formula: C(z) = K r z k Wherein, C(z) is the compensator, and K... r The gain of the repetitive controller, z k This is an advanced stage; The mathematical model of the repetitive controller is expressed by the following formula: Wherein, the G RC (z) is the repetitive controller, Q(z) is the low-pass filter, and z -N This refers to the periodic delay element.

7. The composite control structure according to claim 1, characterized in that, The transfer function of the first PI controller is expressed by the following formula: Among them, G PI (s) is the transfer function of the first PI controller, K P K is the proportional coefficient of the first PI controller. I is the integral coefficient of the first PI controller.

8. The composite control structure according to claim 1, characterized in that, The quasi-resonant controller is expressed by the following formula: Among them, K q ω is the integral coefficient of the quasi-resonant controller. n It is the resonant frequency.

9. A metal loss testing and control system, characterized in that, include: The iron loss test module includes: stator core and H-bridge inverter circuit; The drive control module is connected to the iron loss test module; The composite control structure according to any one of claims 1 to 8 is connected to the drive control module. The composite control structure is used to transmit the total voltage modulation signal it generates to the drive control module, and the drive control module then generates a voltage drive signal to drive the H-bridge inverter circuit to apply a control voltage to the load side.

10. The iron loss testing and control system according to claim 9, characterized in that, The stator core is wound with an excitation coil, which serves as the load of the iron loss test control system. The H-bridge inverter circuit is connected to the drive control module and is used to obtain the voltage drive signal through the drive control module to apply a voltage command to the stator core, generate a current signal on the load side, and reduce the total harmonic distortion rate in the load current.

Images