Construction method of compensation parameter model, controller of PFC converter and control system

Abstract

The embodiment of the invention discloses a construction method of a compensation parameter model, a controller of a PFC converter and a control system, and the method comprises the steps: collecting a plurality of compensation signals outputted by a resonance control model under the condition that the AC input into the PFC converter uses different power grid parameters, so as to obtain at least one compensation signal group corresponding to each power grid parameter, the resonance control model is contained in a current loop used for controlling inductive current of a booster circuit in the PFC converter, and the resonance control model is used for compensating a control signal output by the proportional control model in the current loop; and fitting a preset target function group according to each power grid parameter and the corresponding compensation signal group to obtain a compensation parameter model, wherein the model is used for replacing the resonance control model to compensate the control signal output by the proportional control model according to the actual power grid parameter. By adopting the method, the technical problem that the calculation amount of the controller of the Boost PFC converter is increased when the resonance controller is used can be solved.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of power electronics technology, and in particular to a method for constructing a compensation parameter model, a controller and a control system of a PFC converter. Background Art

[0002] Boost power factor correction (PFC) converter (Boost PFC converter for short) is widely used in the connection between power grid and power load due to its advantages of small input current ripple and wide operating voltage range.

[0003] The controller of the Boost PFC converter usually includes an outer voltage loop and an inner current loop. The controller compares the DC voltage output by the Boost PFC converter with the given value of the voltage loop to obtain an error signal, and provides the error signal to the voltage controller in the voltage loop for voltage compensation. The output of the voltage loop is multiplied by the grid-side AC input voltage to generate a reference for the current loop. The current controller of the current loop adopts proportional control, which controls the input current (i.e., the inductor current in the Boost PFC converter). The value output by the controller is a pulse width modulation (PWM) duty cycle, which is used to control the switch in the Boost PFC converter to achieve the voltage and current of the grid-side AC in phase. Considering the cost and power density issues, the inductor in the Boost PFC converter adopts a magnetic powder core inductor. However, the strong soft magnetic characteristics of the magnetic powder core inductor will cause its inductance value to decrease nonlinearly with the increase of the current value. This nonlinear change characteristic will affect the stability margin of the control system, reduce the value range of the current controller gain, and thus reduce the control effect of the current loop on the current.

[0004] In the related art, in order to enhance the control effect of the current loop, a resonant controller is added to the current loop, and the resonant controller is used to compensate for the proportional control. However, after adding the resonant controller, the amount of calculation of the controller increases, which increases the control time of the controller, which is not conducive to the rapid control of the Boost PFC converter. Summary of the invention

[0005] The embodiments of the present application provide a method for constructing a compensation parameter model, a controller and a control system of a PFC converter to solve the technical problem in the related art that the amount of calculation of the controller of the Boost PFC converter increases when a resonant controller is used.

[0006] In a first aspect, an embodiment of the present application provides a method for constructing a compensation parameter model, the method comprising:

[0007] In the case where the alternating current input into the PFC converter uses different grid parameters, a plurality of compensation signals output by the resonant control model are collected, and a compensation signal group is obtained according to the plurality of compensation signals, each of the grid parameters corresponds to at least one compensation signal group, each of the compensation signal groups includes a plurality of compensation signals within a corresponding sampling period, the resonant control model is included in a current loop for controlling an inductor current of a boost circuit in the PFC converter, the current loop is located in a controller of the PFC converter, and the resonant control model is used to compensate for a control signal output by a proportional control model in the current loop;

[0008] The preset objective function group is fitted according to each of the grid parameters and the corresponding compensation signal group, and the fitted objective function group is used as a compensation parameter model. The compensation parameter model is used to replace the resonant control model in the current loop to compensate the control signal output by the proportional control model according to the actual grid parameters.

[0009] In a second aspect, an embodiment of the present application further provides a controller of a PFC converter, the controller comprising: a voltage loop, a current loop and a feedforward decoupling unit, the current loop and the feedforward decoupling unit are both two, each current loop corresponds to an inductor current of a boost circuit in the PFC converter, the PFC converter comprises a two-phase staggered parallel boost circuit, each current loop comprises a proportional control model, an adder and a compensation parameter model as described in the first aspect;

[0010] The voltage loop is used to obtain a given current according to the DC voltage output by the PFC converter and a given voltage of the voltage loop;

[0011] The proportional control model is used to obtain a first control signal according to the corresponding inductor current, the AC voltage of the AC power input into the PFC converter and the given current;

[0012] The compensation parameter model is used to obtain an actual compensation signal according to actual grid parameters of the alternating current input into the PFC converter, wherein the actual grid parameters include a current voltage amplitude and a current value of the alternating current;

[0013] The adder is used for adding the first control signal and the actual compensation signal to obtain a second control signal output by the current loop;

[0014] The feedforward decoupling unit is used to obtain a third control signal according to the second control signal, the AC voltage and the DC voltage, and the third control signal is used to control the PFC converter so that the voltage and current of the AC power input into the PFC converter have the same phase.

[0015] In a third aspect, an embodiment of the present application further provides a control system for a PFC converter, the control system comprising: a sampling circuit, a driving circuit, and the controller as described in the second aspect, the sampling circuit and the driving circuit are respectively connected to the controller and the PFC converter, and the PFC converter comprises a two-phase staggered parallel boost circuit;

[0016] The sampling circuit is used to collect the DC voltage output by the PFC converter, the inductor current in each of the boost circuits, and the AC voltage and current of the AC power input into the PFC converter;

[0017] The controller is used to obtain a third control signal according to the DC voltage, the inductor current in each of the boost circuits, and the AC voltage and current of the AC power input into the PFC converter;

[0018] The driving circuit is used to amplify the third control signal and control the PFC converter according to the amplified third control signal so that the voltage and current of the alternating current input into the PFC converter have the same phase.

[0019] In one embodiment of the present application, by collecting multiple compensation signals output by the resonant control model when the alternating current uses different grid parameters, and obtaining a compensation signal group corresponding to each grid parameter according to the multiple compensation signals, the preset target function group can be fitted according to each grid parameter and the corresponding compensation signal group to obtain a technical means of replacing the compensation parameter model of the resonant control model, which can solve the technical problem that the amount of calculation of the controller of the Boost PFC converter increases when the resonant controller is used. The resonant control model is replaced by the compensation parameter model, and the compensation parameter model is realized by the target function group, and the compensation signal can be determined in a data-driven manner. At this time, the compensation parameter model can have the compensation effect of the resonant control model, and can also simplify the amount of calculation and reduce the calculation time of the compensation signal. In addition, by constructing the compensation parameter model through the compensation signals corresponding to different grid parameters, the compensation parameter model can be applied to different external conditions, thereby enhancing the stability of the Boost PFC converter. Regardless of whether the external conditions change, better control can be performed, so that the grid-side current and voltage are quickly in phase, and the grid-side power quality is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a signal processing flow diagram of a double closed-loop control scheme in the related art;

[0021] Figure 2 A schematic diagram of modeling a current loop in related technology;

[0022] Figure 3The inductance-current relationship diagram of the magnetic powder core inductor and the air gap inductor in the related art;

[0023] Figure 4 A signal processing flow diagram of a current loop control solution in the related art;

[0024] Figure 5 A schematic diagram of modeling a resonant controller in related technology;

[0025] Figure 6 A flowchart of a method for constructing a compensation parameter model provided in one embodiment of the present application;

[0026] Figure 7 A circuit structure diagram of a Boost PFC converter provided in one embodiment of the present application;

[0027] Figure 8 A first signal simulation diagram of a compensation signal provided by an embodiment of the present application;

[0028] Fig. 9 A second signal simulation diagram of a compensation signal provided by an embodiment of the present application;

[0029] Fig.10 A third signal simulation diagram of a compensation signal provided by an embodiment of the present application;

[0030] Fig.11 A first signal simulation diagram of voltage and current provided by an embodiment of the present application;

[0031] Fig.12 A schematic diagram of harmonic content in a power grid provided in one embodiment of the present application;

[0032] Fig.13 A second signal simulation diagram of voltage and current provided by an embodiment of the present application;

[0033] Fig.14 A third signal simulation diagram of voltage and current provided by an embodiment of the present application;

[0034] Fig.15 A schematic diagram of a voltage and current valid range provided for an embodiment of the present application;

[0035] Fig.16 A signal processing flow chart of a current loop provided by an embodiment of the present application;

[0036] Fig.17 A schematic diagram of the structure of a controller of a PFC converter provided by an embodiment of the present application;

[0037] Fig.18A schematic diagram of the structure of a control system of a PFC converter provided by one embodiment of the present application;

[0038] Fig.19 A schematic diagram of the structure of a PFC converter and a control system provided in one embodiment of the present application. DETAILED DESCRIPTION

[0039] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are used to explain the present application, rather than to limit the present application. It should also be noted that, for ease of description, only the parts related to the present application, rather than all structures, are shown in the accompanying drawings.

[0040] In power electronics technology, the grid-connected interface circuit is the bridge between the power grid and the power load. The AC input of the grid-connected interface circuit needs to follow the DC output. The grid-connected interface circuit is usually composed of nonlinear devices such as inductors, capacitors and switches. The control signal received by the grid-connected interface circuit (used to control the switch) is generally a nonlinear control signal. At this time, the control system that generates the control signal presents a strong nonlinear characteristic, causing the power grid to produce problems such as harmonic pollution and reactive power loss.

[0041] Power factor correction (PFC) technology can improve the power factor of the power grid, increase the power utilization rate of the power grid, and improve the shape of the grid-side current waveform. Therefore, in the relevant technology, PFC technology is applied to the grid-connected interface circuit, and a control system is used to control it so that the voltage and current on the grid side are in phase, thereby improving the power factor, reducing the harmonic content of the grid-side current, and improving the quality of the grid-side current waveform.

[0042] The boost PFC converter is one of the common PFC topologies. It is a circuit structure that applies PFC technology to the grid-connected interface circuit. This circuit structure is widely used due to its advantages of small input side current ripple and wide operating voltage range.

[0043] In the related art, in order to further reduce the ripple of the input side current, the interleaved parallel technology is adopted in the Boost PFC converter. At this time, the Boost PFC converter includes a two-phase interleaved parallel Boost circuit (i.e., two Boost circuits), each of which includes a corresponding inductor and is controlled by a corresponding switch tube.

[0044] For the Boost PFC converter using staggered parallel technology, the control system can output two control signals to control the two switch tubes in the Boost PFC converter respectively, thereby ensuring that the voltage and current on the grid side are in phase. The grid side can also be understood as the power grid side, which provides AC power to the Boost PFC converter. At this time, the voltage and current on the grid side can also be understood as the voltage and current of the AC power input to the Boost PFC converter.

[0045] The control system includes a controller and a peripheral signal conditioning circuit. The peripheral signal conditioning circuit includes a sampling circuit and a driving circuit. In some cases, the control system may also include a Boost PFC converter.

[0046] The sampling circuit is used to collect signals for use by the controller in the Boost PFC converter, for example, collecting the current of the inductor in the Boost circuit, the DC voltage output by the Boost PFC converter, and the voltage of the AC power input to the Boost PFC converter.

[0047] The controller is composed of one or more processors. Currently, the controller is described as being composed of one processor. The processor may be a processor that can run a computer program, such as a central processing unit (CPU) or a microcontroller unit (MCU). The controller is used to obtain a control signal for controlling the Boost PFC converter according to the input and output of the Boost PFC converter. When the Boost PFC converter is controlled based on the control signal, power factor correction can be achieved.

[0048] Currently, the controller uses a dual closed-loop control scheme. In the dual closed-loop control scheme, the outer loop is a voltage loop (i.e., a voltage loop), which is used to control the DC voltage output by the Boost PFC converter. The inner loop is a current loop (i.e., a current loop), which is used to control the inductor current of the Boost circuit. Currently, for a two-phase staggered parallel Boost circuit, the controller uses two current loops to control the two-phase inductor currents respectively.

[0049] Figure 1 This is a signal processing flow diagram of a dual closed-loop control solution in the related technology. Figure 1 Only the input signal is shown, and the signal acquisition process is not shown. Figure 1 , dual closed-loop control is achieved through a voltage loop 10 and two current loops 20 .

[0050] Figure 1 In, v refis the voltage loop given value (i.e. the voltage loop given value), and its specific construction method can refer to the existing construction method and will not be described separately at present. o I is the DC voltage output by the Boost PFC converter (currently recorded as DC voltage). ref is the current loop given value (i.e. the given value of the current loop). vp (z) is the voltage controller in the voltage loop. G ip (z) is the current controller in the current loop. It can be understood that G in the two current loops ip (z) are of the same type, but the coefficients used in the control process can be the same or different. D is the control signal output by the controller. Currently, D includes D1 and D2, which are control signals obtained based on two currents. ac is the voltage of the AC power input from the grid side (i.e. AC voltage). Lx is the current of the inductor in the corresponding Boost circuit, and x is 1 or 2 to represent the current of the inductor in the two Boost circuits respectively.

[0051] v o When the input voltage loop is filtered, it is first filtered by a filter, which is a low-pass filter used to suppress v o The voltage fluctuation in v ref The input voltage loop is subtracted from the DC voltage output by the filter to obtain an error signal. This error signal can reflect the difference between the actual DC voltage output by the Boost PFC converter and the given voltage (i.e., v ref ) between the two groups. vp (z) Perform voltage compensation based on the error signal so that v o As close to v as possible ref The voltage controller output I ref I is the DC current. ref It can be understood as the current value determined when the voltage controller performs voltage compensation.

[0052] Need to explain, I ref is the given value used by the two current loops. At present, since the processing flow of the two current loops is the same, the processing flow of the current loop is described by taking one current loop as an example. ip (z) Control the inductor current in the corresponding Boost circuit respectively. At this time, the current loop given value input in each current loop is I ref / 2.

[0053] In order to ensure that the voltage and current of the AC power on the grid side are in phase, v ac After the input current loop passes through the phase-locked loop, an AC voltage signal with a sinusoidal waveform is obtained. Figure 1 In the example, we write sin(θ) asref / 2 is multiplied by sin(θ) to obtain the given value of the AC current with a sinusoidal waveform. Figure 1 In the ref Since the current of the Boost circuit can only move in the forward direction, we can get i ref After that, to i ref The absolute value operation is performed to obtain all positive current given values. ref with i Lx (i L1 or L2 ) and subtract them to get G ip (z) is the input. ip (z) Perform current compensation according to the input signal and output a corresponding control signal, which is used to realize the control of i Lx control.

[0054] G ip The control signal output by (z) can be considered as the control signal output by the current loop. Then, the control signal is added with v o And v after taking the absolute value ac The difference between , to achieve feedforward control. It can be understood that v ac is the voltage of the alternating current, v o is a positive DC voltage, so for v ac Taking the absolute value will give the positive voltage. ac Take the absolute value and add it to v o The difference between the input voltage and the output voltage of the Boost PFC converter can reflect the difference between the input voltage and the output voltage. ip (z) After the output control signals are added, the difference can be added to the control signal, that is, feedforward control is achieved.

[0055] The signal obtained by feedforward control is compared with v o Divide to achieve decoupling, thereby ensuring that the output D is between 0 and 1. Wherein, D is the PWM duty cycle used to indicate whether the switch tube corresponding to the Boost circuit is turned on or off. It can be understood that two PWM duty cycles can be obtained based on the two current loops, so as to realize the control of the switch tubes of the two Boost circuits based on the two PWM duty cycles respectively.

[0056] The PWM duty cycle output by the controller is input to the driving circuit. The driving circuit is located between the controller and the Boost PFC converter, and is used to amplify the PWM duty cycle output by the controller so that the amplified PWM duty cycle is sufficient to drive the switch tube in the Boost PFC converter. The driving circuit includes two sub-circuits. The controller outputs two PWM duty cycles, and each PWM duty cycle is input to a sub-circuit. The two sub-circuits are respectively connected to the two switch tubes corresponding to the two Boost circuits to amplify the PWM duty cycle respectively so that the amplified PWM duty cycle drives the corresponding switch tube to turn on and off, thereby making the input v of the Boost PFC converter ac Follow output v o , and ensure that v ac and i ac In phase. ac is the AC current input to the Boost PFC converter. It can be understood that since the specific value of the PWM duty cycle output by the controller is related to v o and i Lx Therefore, when the Boost PFC converter controls the on and off of the switch tube according to the PWM duty cycle, it can also be considered as a o and i Lx Controlled.

[0057] In the related art, in order to improve the dynamic response speed of the current loop, the current loop adopts proportional control (i.e. PI control). At this time, G ip (z) can also be understood as a proportional controller. When a proportional controller is used, Figure 2 This is a schematic diagram of the modeling of the current loop in the related technology. Figure 2 A schematic diagram of a current loop modeling is shown in Figure 1. Figure 2 , k i Represents G ip (z) The scaling factor used, T s is the sampling period, L is the filter inductance, z=e -Ts·s , L(z-1) is the inductance representation in the discrete domain. The inductance output i Lx As the input of the current loop, to achieve closed-loop control of the current loop.

[0058] At this time, the transfer function used by the current loop is as follows:

[0059]

[0060] It can be understood that when the current loop is stable, the pole of the transfer function of the current loop should be in the left half plane of the coordinate system. At this time, in order to ensure the stability of the current loop, k is required i <L / T s , that is, k is limited iThe value conditions of .

[0061] In the related art, the inductor used for filtering in the Boost PFC converter (i.e., the inductor in the Boost circuit) is a magnetic powder core inductor. The magnetic powder core is a soft magnetic material. Compared with the traditional air gap inductor, the magnetic powder core inductor has a smaller volume and lower loss. Therefore, it has great advantages in converter cost and power density.

[0062] Figure 3 The inductance-current relationship diagram of magnetic powder core inductor and air gap inductor in the related technology. Figure 3 , the horizontal axis represents the current value of the inductor, and the vertical axis represents the inductance value. Figure 3 It can be seen that the strong soft magnetic characteristics of the magnetic powder core inductor will cause its inductance value to decrease nonlinearly with the increase of current. This nonlinear change characteristic will affect the stability margin of the control system of the Boost PFC converter (mainly for the controller), reduce the value range of the current controller gain, and thus reduce the control effect of the current controller on the current in the magnetic powder core inductor. In addition, when using proportional control, the bandwidth of the current controller is limited, resulting in poor steady-state and dynamic performance of the Boost PFC converter, and the current is prone to distortion. The distortion phenomenon becomes more serious as the power level increases.

[0063] In order to make up for the above technical defects and realize the steady-state tracking of the current without static error, both current loops can be set to use proportional resonance (PR) control, that is, resonant control in the current loop using proportional control. At this time, the current loop includes a current controller for realizing proportional control and a current controller for realizing resonant control. At present, the current controller for realizing proportional control is recorded as a proportional controller, and the current controller for realizing resonant control is recorded as a resonant controller.

[0064] Figure 4 Schematic diagram of the signal processing flow of a current loop control scheme in the related art. o 、v ac ,I ref 、i ref 、i Lx For the meaning of D, please refer to the above description. Figure 4 So Figure 1 Taking a current loop in as an example, the signal processing flow of the current loop after adding resonance control is described. Figure 1 The current loop shown, Figure 4 The current loop 20 in the embodiment adds a resonance control part 21. In this case, the current loop 20 includes the resonance control part 21 and the proportional control part 22. iR (z) is the resonant controller used in the resonant control part, G ip (z) is a proportional controller.k_P G ip (z) Output control signal. k_R G iR (z) Output control signal. Sign is the sign function.

[0065] In the resonance control section 21, input Sign(v ac ), where v ac When it is a positive number, Sign(v ac ) is positive, v ac When it is a negative number, Sign(v ac ) is negative. The input i Lx and Sign(v ac ) can be multiplied by i Lx The related AC current signal. ref The result of subtracting the AC current signal can reflect the given current value (I ref ) and the actual current value (i Lx ) error signal in the case of AC. After that, G iR (z) Resonance control is performed based on the result after subtraction, G iR The output of (z) is the same as Sign(v ac ) and we can get u k_R . will u k_P with u k_R After superposition, the control signal of the current loop output can be obtained. Figure 4 In the k After that, D can be obtained based on the feedforward decoupling. It can be understood that u k_R It can be considered as k_P At this time, when the control is performed based on D obtained after superposition compensation, i ac As close to the full barrel wave as possible, thus enhancing the current loop to i ac control effect.

[0066] When using proportional resonant control, Figure 5 is a modeling diagram of a resonant controller in the related art, where K r Represents G iR (z) resonance coefficient, ω c G iR (z) action band (i.e. compensation band), ω o is the resonant frequency, e i for i ref with i Lx The error signal between Figure 2 The meaning of s is the same as that of G. iR (z) The transfer function in the discrete domain is as follows, and z = e -Ts·s,

[0067]

[0068] in, b 11 =-b 12 , a 12 =1,

[0069] Although proportional resonant control can enhance the current tracking capability and improve the steady-state and dynamic performance of the controller, the parameters of the resonant controller are relatively complex, resulting in c When it is large, the amount of calculation of the controller is large. In addition, the anti-interference ability of the resonant control is poor. When the external conditions (such as the voltage or current of the AC power input to the Boost PFC converter) suddenly change, the dynamic performance of the Boost PFC converter will be affected.

[0070] Based on this, an embodiment of the present application provides a method for constructing a compensation parameter model, a controller, and a PFC control system. By constructing a compensation parameter model driven by data to replace the resonance control part to compensate the current control part, the operation time of the controller can be reduced, and the network-measured power quality can be improved without affecting the performance of the controller. Even if the external conditions suddenly change, it will not have a significant impact on the dynamic performance of the Boost PFC converter.

[0071] Among them, the compensation parameter model is a computer program model that implements multiple set functions. It is a data-driven model. The compensation parameter model can quickly compensate the control signal output by the proportional control part in the current loop according to the voltage and current of the alternating current input by the Boost PFC converter to ensure the control effect of the current loop.

[0072] Accurately constructing a compensation parameter model is an important condition for ensuring the current loop control effect. In the embodiment of the present application, how to accurately construct a compensation parameter model is described through a method for constructing a compensation parameter model.

[0073] The method for constructing the compensation parameter model can be performed by a device for constructing the compensation parameter model. The device for constructing the compensation parameter model can be composed of one physical entity or two or more physical entities. Currently, the device for constructing the compensation parameter model is a device with data processing and computing capabilities. For example, the device for constructing the compensation parameter model can be a processor running a computer programming program or an electronic device containing a processor (such as a laptop, a desktop computer, etc.).

[0074] In one embodiment, the controller of the Boost PFC converter can be used as a device for constructing the compensation parameter model. In this case, the compensation parameter model constructed by the controller can be used directly. In practical applications, the device for constructing the compensation parameter model can also be other devices independent of the controller. In this case, the compensation parameter model constructed by other devices needs to be first imported into the controller of the Boost PFC converter and then used by the controller.

[0075] When constructing the compensation parameter model, Figure 6 A flowchart of a method for constructing a compensation parameter model provided in one embodiment of the present application, referring to Figure 6 , the method for constructing the compensation parameter model includes steps 310 to 320:

[0076] Step 310: When the alternating current input into the PFC converter uses different grid parameters, multiple compensation signals output by the resonant control model are collected, and a compensation signal group is obtained according to the multiple compensation signals, each grid parameter has at least one corresponding compensation signal group, each compensation signal group includes multiple compensation signals within a corresponding sampling period, the resonant control model is included in a current loop for controlling the inductor current of the boost circuit in the PFC converter, the current loop is located in the controller of the PFC converter, and the resonant control model is used to compensate for the control signal output by the proportional control model in the current loop.

[0077] Currently, the PFC converter is a Boost PFC converter. Figure 7 A circuit diagram of a Boost PFC converter provided by an embodiment of the present application. Figure 7 The Boost PFC converter includes two-phase interleaved parallel boost circuits, which can also be referred to as Boost circuits. Each boost circuit includes an inductor. Figure 7 The two inductors included in the two boost circuits are denoted as L1 and L2 respectively, and the current flowing into L1 is the inductor current i L1 , the current flowing into L2 is the inductor current i L2 .v ac 、i ac and v o The meanings of can refer to those in the relevant technologies. o Indicates the load current used by the load, that is, the DC current output by the Boost PFC converter. ac It is a unidirectional AC voltage, v ac After passing through the rectifier bridge, it is used as the input voltage of the boost circuit. Figure 7 V in .

[0078] Each boost circuit is controlled by a corresponding switch. Figure 7In the figure, the switch connected to the boost circuit where L1 is located is marked as T1, and the switch connected to the boost circuit where L2 is located is marked as T2. T1 and T2 can be MOS tubes. By controlling the conduction and cutoff of T1 and T2, v ac and i ac In phase to achieve power factor correction function.

[0079] The controller of the PFC converter (also known as the controller of the Boost PFC converter) is used to obtain a control signal for controlling the Boost PFC converter according to the input, output and inductor current of the Boost PFC converter. When the Boost PFC converter is controlled based on the control signal, power factor correction can be achieved. Currently, the controller outputs two control signals, each of which is used to control a switch corresponding to a Boost circuit. For example, the two control signals are used to control Figure 7 The controller used in the embodiment is the same physical entity as the controller used in the related art, and both can be implemented by a processor. At this time, each function implemented by the controller is implemented by the processor running the corresponding program. When the processor has a storage function, the program run by the processor can be stored in the processor. When the processor does not have a storage function, the controller may also include a memory, in which the program for the processor to run is stored. It should be noted that in actual applications, in addition to implementing the control function of the controller through a program, a combination of software and hardware can also be used. For example, some functions in the controller are implemented by corresponding physical hardware.

[0080] The controller used when constructing the compensation parameter model can refer to the controller with added resonance control in the related technology. At this time, the signal processing flow of the current loop in the controller can refer to Figure 4 . That is based on Figure 4 The current loop shown in the figure is used to construct a compensation parameter model suitable for the current loop. At present, the proportional control part 22 of the controller is recorded as a proportional control model, and the resonant control part 21 is recorded as a resonant control model. Both the proportional control model and the resonant control model can be implemented by corresponding programs. The specific processing process of the current loop can be referred to in the relevant technology for Figure 4 The description of is not repeated here.

[0081] It can be understood that the currently constructed compensation parameter model is mainly used to compensate for the large amount of calculation and insufficient anti-interference ability when using the resonant control model, and the compensation parameter model has the same function as the resonant control model, both of which are used to compensate the control signal output by the proportional control model to achieve the control of the Boost PFC converter. Therefore, the compensation parameter model can be constructed in combination with the actual situation of the power grid and the control signal output when the resonant control model is compensated, so that the compensation parameter model can achieve the same compensation effect as the resonant control model, that is, under the same conditions, the control signal output by the compensation parameter model is the same as or close enough to the control signal output by the resonant control model.

[0082] Based on this, when constructing the compensation parameter model in the embodiment, the control signal output by the resonance control model is first collected. Currently, since the control signal is used to compensate the control signal output by the proportional control model, the control signal output by the resonance control model is recorded as a compensation signal for easy distinction. A compensation signal can also be understood as a specific value corresponding to a sampling point. Among them, the means of collecting the compensation signal can refer to the existing means and will not be described separately at present.

[0083] In order to make the compensation parameter model suitable for the situation where the external conditions suddenly change, multiple power grid parameters are set for the Boost PFC converter in advance, and a compensation parameter model suitable for different external conditions is constructed based on the multiple power grid parameters. Among them, the external conditions can also be understood as the parameters of the alternating current (i.e., the grid-side alternating current) input to the Boost PFC converter, such as the alternating current voltage, current, etc. In one embodiment, the power grid parameters include the voltage amplitude and current value of the alternating current. At present, the current of the alternating current is also constantly changing, so the current value in the power grid parameters can also be understood as the current amplitude of the alternating current. The number of power grid parameters can be set according to actual needs, and the embodiment does not limit this.

[0084] Every time the grid parameters of the AC power input to the Boost PFC converter are changed, the compensation signal output by the resonant control model is collected, that is, the Figure 4 u k_R. In one embodiment, multiple compensation signals are collected under each power grid parameter, and a compensation signal group is obtained based on the multiple compensation signals. At this time, each power grid parameter has a corresponding compensation signal group, and the number of compensation signal groups corresponding to each power grid parameter can be one or more. Each compensation signal group corresponds to a sampling period. The time length corresponding to the sampling period is equal to the time length corresponding to the current period. Among them, the current period can be understood as the period of the inductor current under AC, and the current period is half of the period of AC. The period of AC can also be understood as the AC voltage period, which is the sum of the time of one positive flow and one reverse flow in AC. For example, the period of AC is a period of 50Hz, that is, 0.02s, then the current period is a period of 100Hz, that is, 0.01s, and the number of compensation signals contained in each compensation signal group is the same, and the number is related to the sampling frequency and the sampling period. For example, the sampling period is a period of 100Hz and the sampling frequency is 40kHz, then a compensation signal group contains 400 compensation signals.

[0085] Since the magnitude and direction of the alternating current are constantly changing, there is distortion at the zero-crossing point (i.e., the moment when the current is 0), which will cause the compensation signal of the resonant control model to be greatly reduced at the moment corresponding to the zero-crossing point (i.e., the moment when a current cycle begins), which will increase the difficulty of fitting the compensation parameter model later. For example, Figure 8 This is a first signal simulation diagram of a compensation signal provided by an embodiment of the present application, wherein the signal corresponding to PR1 and the signal corresponding to PR2 represent the compensation signals output by the two resonance control models respectively. Figure 8 Taking 400 compensation signals sampled in one sampling period as an example, the horizontal axis X represents the position of the compensation signal in one sampling period, that is, the position range of X is 1 to 400, and the position of the compensation signal is related to the collection order of the compensation signal. The vertical axis Y represents the specific value of the compensation signal. Figure 8 In this example, a current cycle is taken as a sampling cycle. At this time, Figure 8 It can be seen that at the beginning of a current cycle, the compensation signal suddenly drops due to the current zero-crossing distortion. At this time, if the current cycle is used as the sampling cycle, the first few compensation signals in each compensation signal group obtained by sampling will all have sudden drops. In order to avoid the influence of the sudden drop of the compensation signal on the compensation parameter model constructed subsequently, in one embodiment, collecting multiple compensation signals output by the resonant control model in step 310 can specifically include: starting to collect multiple compensation signals output by the resonant control model after a set number of compensation signals have passed after the beginning of a current cycle, and the time length of the current cycle and the sampling cycle are equal.

[0086] In a current cycle, there is first a small amount of compensation signal with a sudden drop, and then there is no normal compensation signal. In this way, when a current cycle starts, according to the currently used sampling frequency, a set number of compensation signals are skipped first to skip the sudden drop compensation signal, and then the compensation signal is collected again, that is, the sampling cycle begins. Among them, the set number can be set according to the actual situation, and the duration corresponding to the set number of compensation signals is approximately equal to the duration of the sudden drop compensation signal. For example, Figure 8 In the compensation signal shown, the number is set to 75, that is, the sudden drop compensation signal is about 75 beats (equivalent to about 75 sampling points). Therefore, when a current cycle starts, after 75 compensation signals are skipped according to the current sampling frequency, that is, after 75 sampling points are delayed, the compensation signal is collected from the 76th sampling point, that is, a sampling cycle begins. After that, the collected 400 compensation signals are used as the compensation signal obtained in one sampling cycle. At this time, Fig. 9 A second signal simulation diagram of a compensation signal provided by an embodiment of the present application is shown in FIG. Figure 8 Based on the compensation signal shown, after a delay of 75 beats, 400 compensation signals are collected in one sampling period. Figure 8 , Fig. 9 There is basically no sudden drop in the compensation signal, which is more conducive to the construction of the subsequent compensation parameter model.

[0087] For a power grid parameter, if compensation signals of multiple current cycles are required, it is possible to delay the set number of compensation signals only after the first current cycle and start collecting the compensation signals. At this time, since each current cycle is continuous, the subsequent current cycles are also delayed synchronously.

[0088] After the compensation signal group is obtained, a compensation parameter model may be constructed based on each grid parameter and the corresponding compensation signal group, that is, step 320 is executed.

[0089] Step 320, fit the preset objective function group according to each grid parameter and the corresponding compensation signal group, and use the fitted objective function group as the compensation parameter model, which is used to replace the resonant control model in the current loop to compensate the control signal output by the proportional control model according to the actual grid parameter.

[0090] In the embodiment, the compensation parameter model is composed of a plurality of pre-set functions. Currently, the plurality of functions constituting the compensation parameter model are recorded as an objective function group. The input of the objective function group as a whole is the power grid parameter, and the output is the compensation signal to be output under the power grid parameter. Currently, the objective function group is fitted using the compensation signal group collected in the above steps and the corresponding power grid parameters.

[0091] In an optional manner, when each power grid parameter corresponds to a compensation signal group, each power grid parameter and the corresponding compensation signal group are used as a group of input and output, and the objective function group is fitted based on each group of input and output. When each power grid parameter corresponds to multiple compensation signal groups, a group of compensation signal groups for fitting is first obtained based on the multiple compensation signal groups, and then each power grid parameter and the corresponding compensation signal group for fitting are used as a group of input and output, and the objective function group is fitted based on each group of input and output.

[0092] The types of functions included in the objective function group are not currently limited, and only need to satisfy the requirement of being able to accurately output compensation signals according to the power grid parameters.

[0093] In one embodiment, the objective function group includes a function for illustrating the relationship between each compensation signal in the compensation signal group corresponding to the power grid parameter. Currently, the function is recorded as the first objective function. The independent variable of the first objective function is the position of the compensation signal in the compensation signal group, and the dependent variable is the compensation signal. At this time, the first objective function can be obtained by fitting each compensation signal in the compensation signal group and the position of the compensation signal, and each power grid parameter used in the above steps corresponds to a first objective function, and the values ​​of the coefficients used in these first objective functions are different. When the corresponding power grid parameters are input into the Boost PFC converter, the compensation signal corresponding to the sampling point at each position in the sampling period can be determined by the first objective function, that is, the compensation signal to be output at each sampling moment. The fitting process can be considered as a process of obtaining the value of the coefficient used in the first objective function based on the independent variable and the dependent variable.

[0094] At present, since a first objective function is only applicable to one power grid parameter, and in actual application, the power grid parameter input to the Boost PFC converter is variable, in order to be applicable to various changing power grid parameters, the objective function group also includes a function for explaining the relationship between the power grid parameter and the coefficient used in the first objective function. At present, the function is recorded as the second objective function, wherein the number of the second objective function can be determined according to the coefficient used in the first objective function. In the embodiment, for the convenience of distinction, the coefficients included in the first objective function are recorded as the first coefficients, and the coefficients included in the second objective function are recorded as the second coefficients. Each first coefficient corresponds to a second objective function. At this time, the power grid parameters used in the above steps are used as independent variables, and the specific values ​​of the corresponding first coefficients in the first objective function corresponding to each power grid parameter are used as dependent variables. By fitting the second objective function, the value of the second coefficient in the second objective function can be obtained. At this time, based on the second objective function, the specific values ​​of the first coefficients under different power grid parameters can be determined, and then the value of the compensation signal to be output is determined based on the first objective function using the first coefficient. The fitted second objective functions and the first objective function can be used as a compensation parameter model. The second coefficient of each second objective function in the compensation parameter model has a specific value, and the value of each first coefficient in the first objective function needs to be determined by the second objective function.

[0095] The specific fitting process of the first objective function and the second objective function is described below. At this time, the objective function group includes the first objective function and multiple second objective functions, each first coefficient in the first objective function corresponds to a second objective function, and step 320 can specifically include steps 321-323:

[0096] Step 321: Fit the first objective function according to the compensation signal group corresponding to each grid parameter to determine the coefficient value corresponding to the first coefficient in the first objective function under each grid parameter.

[0097] The first objective function belongs to a univariate nonlinear regression model. The regression model studies the relationship between the dependent variable (target) and the independent variable (predictor). Currently, according to the changing trend of the compensation signal within a sampling period, a suitable regression model is selected as the first objective function. In one embodiment, according to the changing trend of the compensation signal in each compensation signal group, the Fourier function (i.e., Fourier series) is selected as the regression model. Among them, the formula of the Fourier function is as follows:

[0098]

[0099] Among them, x is the independent variable of the Fourier function, y is the dependent variable of the Fourier function, corresponding to the current usage scenario, x is the position of the compensation signal in the compensation signal group, and y is the specific value of the compensation signal. For example, 400 compensation signals are collected in one sampling period, then the value range of x is 1 to 400, and y is the specific value of the collected compensation signal. m represents the harmonic order of the Fourier model, i represents the i-th harmonic, 1≤i≤m, a0, a i and b i is the parameter of the regression model. In the embodiment, combined with the actual fitting effect, the first-order Fourier function (i.e., the first-order Fourier series) is selected as the first objective function, i.e., m=1. At this time, the formula of the first-order Fourier function is as follows:

[0100] f (x)=a0+a1cos(ωx)+b1sin(ωx) (4)

[0101] At this time, f(x) represents the compensation signal, x represents the position of the compensation signal in the compensation signal group, and a0, a1, b1 and ω can all be considered as the first coefficient used in the first objective function.

[0102] In one embodiment, when fitting a first-order Fourier function, the least square method can be used to obtain the specific value of each first coefficient, that is, the coefficient value. Among them, the least square method is a more commonly used calculation method and is not described separately at present. In practical applications, other methods can also be used to obtain the specific value of each first coefficient.

[0103] Exemplarily, when each power grid parameter corresponds to a compensation signal group, each compensation signal in the compensation signal group is used as f(x) in formula (4), and the position of each compensation signal in the compensation signal group is used as x in formula (4). The coefficient values ​​of a0, a1, b1 and ω can be obtained by fitting using the least squares method. Then, the first-order Fourier function corresponding to each power grid parameter is obtained.

[0104] When each power grid parameter corresponds to multiple compensation signal groups, it is necessary to first obtain a compensation signal group for fitting based on the multiple compensation signal groups, and then obtain the first-order Fourier function corresponding to each power grid parameter based on the compensation signal group for fitting. At present, it is taken as an example that each power grid parameter corresponds to multiple compensation signal groups. At this time, step 321 can specifically include 3211-step 3212:

[0105] Step 3211: Determine a target compensation signal group corresponding to each power grid parameter according to multiple compensation signal groups corresponding to each power grid parameter.

[0106] Among them, the number of compensation signal groups corresponding to each grid parameter is the same, and the specific number can be set according to the actual situation. At present, it is described by taking 50 groups of compensation signals corresponding to each grid parameter as an example, that is, after the AC power input by the Boost PFC converter uses one grid parameter, 50 compensation signal groups are collected in 50 sampling cycles, and then, after using another grid parameter at the home point, 50 compensation signal groups are continued to be collected in 50 sampling cycles, and so on, until each grid parameter has 50 compensation signal groups.

[0107] The target compensation signal group can be considered as a compensation signal group for fitting, and the target compensation signal is the compensation signal contained in the target compensation signal group. Each power grid parameter has a corresponding target compensation signal group. In one embodiment, the target compensation signal group is obtained by calculating the average value of the compensation signal group. At this time, step 3211 can be specifically as follows: calculate the average value of each compensation signal with the same position between each compensation signal group corresponding to the power grid parameter, and use the average value as the target compensation signal at the corresponding position. Each target compensation signal constitutes a target compensation signal group corresponding to the power grid parameter, and each power grid parameter has a corresponding target compensation signal group.

[0108] At present, it is taken as an example that each compensation signal group contains 400 compensation signals, and each power grid parameter corresponds to 50 compensation signal groups. For a power grid parameter, the compensation signals at the same position in the corresponding 50 compensation signal groups are averaged, and the average value is used as the target compensation signal corresponding to the position in the target compensation signal group. At this time, the calculation formula of the target compensation signal is as follows:

[0109]

[0110] Wherein, J represents the total number of compensation signal groups corresponding to the power grid parameters. Currently, J=50, j represents the jth compensation signal group currently in use, 1≤j≤50. x is the position of the compensation signal. When the compensation signal group contains 400 compensation signals, the range of x is [1,400]. xj represents the compensation signal at the xth position in the jth compensation signal group. x represents the target compensation signal at the xth position in the target compensation signal group. Based on formula (5), the target compensation signal corresponding to each position in the target compensation signal group can be obtained. For example, the average value of 50 compensation signals corresponding to the first position in the 50 compensation signal groups is used as the target compensation signal at the first position in the target compensation signal group. By analogy, the target compensation signal group can be obtained. It can be understood that under each power grid parameter, the corresponding target compensation signal group can be obtained using formula (5).

[0111] Currently, the root mean square error can be used to evaluate the target compensation signal group. The root mean square error is calculated as follows:

[0112]

[0113] Wherein, Re represents the calculated root mean square error, n represents the number of target compensation signals in the target compensation signal group, i represents the position of the target compensation signal, represents the target compensation signal at the i-th position, y i Represents the compensation signal at the i-th position. It can be understood that each current power grid parameter corresponds to multiple compensation signal groups, so there is a root mean square error between each compensation signal group and the target compensation signal group. For example, the power grid parameter corresponds to 50 compensation signal groups, so 50 root mean square errors can be obtained based on the 50 compensation signal groups and the target compensation signal group. If the values ​​of the 50 root mean square errors are relatively small, it means that the error between the target compensation signal and the compensation signal is small, and it can be used to fit the first objective function. At present, after calculating the root mean square error, the root mean square error is much less than 2, so it means that the target compensation signal is valid.

[0114] Step 3212: Use the target compensation signal in the target compensation signal group as the dependent variable of the first objective function, use the position of the target compensation signal in the target compensation signal group as the independent variable of the first objective function, and fit the first objective function to determine the coefficient value corresponding to the first coefficient in the first objective function under each power grid parameter.

[0115] Currently, when the target compensation signal group fitting formula (4) is used, f(x) represents the target compensation signal at position x in the target compensation signal group, and x represents the position of the target compensation signal in the target compensation signal group. Substituting each target compensation signal and the corresponding position in the target compensation signal group into formula (4) and fitting, the specific values ​​of a0, a1, b1 and ω can be obtained.

[0116] For example, the voltage amplitude of the grid parameters input to the Boost PFC converter is 100V, the current value is 8A, the sampling period is 100Hz, the sampling frequency is 40kHz, and 50 compensation signal groups are sampled for each resonant control model in the two current loops. At this time, the two first objective functions obtained by fitting are:

[0117]

[0118]

[0119] PR1 and PR2 correspond to the resonant control models in the two current loops respectively. Fig.10A third signal simulation diagram of a compensation signal provided by an embodiment of the present application is Fig. 9 The figure shows a simulation diagram of the compensation signal output within a sampling period by two first objective functions fitted under the grid parameters corresponding to the compensation signal. Fig.10 In , the abscissa x represents the position of the compensation signal in a sampling period, and the ordinate f(x) represents the specific value of the compensation signal. Fig.10 The compensation signal shown is Fig. 9 The compensation signals shown are similar. Therefore, it can be considered that under the same grid parameters, the compensation signal output by the first objective function is highly similar to the compensation signal output by the resonant control model, that is, the compensation signal output by the first objective function can achieve the compensation effect of the resonant control model, which means that the first objective function can compensate for the proportional control model and improve the current zero-crossing distortion.

[0120] Currently, the first objective function can be verified by the simulated waveform of the alternating current input into the Boost PFC converter and the total harmonic distortion (THD) of the current. At this time, the grid parameters of the alternating current input into the Boost PFC converter are the grid parameters corresponding to the first objective function, that is, the voltage amplitude and current value of the input alternating current are the voltage amplitude and current value corresponding to the first objective function. After that, the first objective function is used to replace the corresponding resonant control model in the controller. At this time, the resonant control models in the two current loops are replaced with the corresponding first objective function. It can be understood that the current external conditions (that is, the grid parameters) are fixed, so the coefficient value of the first coefficient in the first objective function is also fixed. At this time, the input of the first objective function is the position of the current sampling moment in the adoption cycle, and the output is the corresponding compensation signal. For example, Fig.11 A first signal simulation diagram of voltage and current provided for an embodiment of the present application is a simulation diagram of the voltage signal and current signal of the grid-side AC power obtained by replacing the resonant control models in the two current loops with formula (7) and formula (8) respectively when the voltage amplitude in the grid parameters is 100V and the current value is 8A. Fig.11 The voltage waveform shown is 0.1 times the voltage waveform of the AC power on the grid side ( Fig.11 0.1vac in the figure) to facilitate observation of the phase of the voltage and current waveforms. After the first objective function starts to output the compensation signal, the voltage and current waveforms ( Fig.11 The phase problem of the waveform after the dotted line indicating the addition of compensation) has been improved, that is, the phase of the voltage waveform and the current waveform are closer, achieving the same phase of the grid-side power grid and the current. Fig.12 A schematic diagram of harmonic content in a power grid provided in an embodiment of the present application shows Fig.11 The harmonic content of the AC power in the power grid shown is given by Fig.12It can be seen that the current THD in the power grid is only 0.72%, indicating that the harmonic content in the power grid is small and the power quality of the power grid is high. Therefore, it is proved that the first objective function is effective.

[0121] Optionally, each time a grid parameter is changed, a corresponding first objective function may be constructed, and after obtaining the first objective functions corresponding to all preset grid parameters, step 322 is executed. Alternatively, each time a grid parameter is changed, a corresponding plurality of compensation signal groups are collected, and after all preset grid parameters are used, the first objective functions corresponding to each grid parameter are obtained based on the plurality of compensation signal groups, and step 322 is executed.

[0122] Step 322: Fit the second objective function according to each grid parameter and the coefficient value of the first coefficient under each grid parameter to determine the coefficient value of the second coefficient in the second objective function.

[0123] At present, each first objective function obtained by fitting can only effectively compensate the proportional control model when the corresponding power grid parameters are input to the Boost PFC converter. That is, the coefficient value of the first coefficient in the first objective function determined by fitting cannot be applied to the changing power grid parameters. Therefore, a corresponding second objective function is designed for each first coefficient. At this time, the second objective function can be considered to be the first coefficient in the first objective function. The second objective function belongs to a multivariate nonlinear regression model. At present, after taking the power grid parameters as independent variables, combined with the actual fitting effect (i.e., the changing trend of the coefficient value of the first coefficient), a binary high-order polynomial is selected as the multivariate nonlinear regression model. It can be understood that when there are multiple second objective functions, the quadratic high-order polynomials used by each second objective function are different to ensure a fitting effect that is closer to the actual situation.

[0124] In one embodiment, when the first objective function is a first-order Fourier function (i.e., formula (4)), four second objective functions are designed for the first coefficients a0, a1, b1, and ω, respectively. Currently, the formulas of the four second objective functions are as follows:

[0125]

[0126] Among them, u represents the voltage amplitude of the AC power in the power grid parameters (i.e., v ac The voltage amplitude), i represents the current value of the alternating current in the power grid parameters (i.e., i ac The current amplitude), a0, a1, b1 and ω are the first coefficients used in the first objective function, m 01 、m 02 、m 03 、m 04 、m 05 and m 06 are the second coefficients used in the second objective function corresponding to a0, m11 、m 12 、m 13 、m 14 、m 15 and m 16 are the second coefficients used in the second objective function corresponding to a1, m 21 、m 22 、m 23 、m 24 、m 25 and m 26 are the second coefficients used in the second objective function corresponding to b1, m 31 、m 32 、m 33 、m 34 、m 35 、m 36 、m 37 、m 38 and m 39 Both are the second coefficients used in the second objective function corresponding to ω.

[0127] In formula (9), u and i are the independent variables of each second objective function, and the coefficient value of the corresponding first coefficient is the dependent variable of the second objective function. Based on each grid parameter and the coefficient value of the corresponding first coefficient in the corresponding first objective function, the second objective function corresponding to the first coefficient is fitted to obtain the coefficient value of each second coefficient in the second objective function.

[0128] At present, with a sampling period of 100 Hz and a sampling frequency of 40 kHz, 50 compensation signal groups are sampled for each resonant control model in the two current loops, and the first objective function under different grid parameters is fitted. After fitting the above four second objective functions based on the coefficient value of the first coefficient in the first objective function and the corresponding grid parameters, the specific coefficient values ​​of each second coefficient are shown in Table 1:

[0129] Table 1

[0130]

[0131] Table 1, PR1 and PR2 correspond to the resonant control models in the two current loops, respectively, and their corresponding coefficient values ​​are respectively applicable to the second objective functions used in the two current loops.

[0132] Step 323: Use the first objective function and each of the fitted second objective functions as compensation parameter models.

[0133] The second objective functions and the first objective function obtained by the above fitting can form the compensation parameter model currently constructed and used in the controller of the Boost PFC converter. The second coefficient in each second objective function in the compensation parameter model currently used adopts the coefficient value determined in the above steps, and the first coefficient in the first objective function in the compensation parameter model has no fixed coefficient value. The coefficient value used by the first objective function when determining the compensation signal is determined by the corresponding second objective function.

[0134] The verification process of the effectiveness of the compensation parameter model is described below. The compensation parameter model constructed above replaces the corresponding resonance control model in the controller. After that, the grid parameters are changed so that the compensation parameter model outputs the corresponding compensation signal under different grid parameters. By observing the voltage of the grid-measured AC power (i.e., v ac ) and current (i ac ), determine the performance of the compensation parameter model. Fig.13 A second signal simulation diagram of voltage and current provided for an embodiment of the present application shows the voltage waveform and current waveform of the AC power when a controller using a compensation parameter model controls the Boost PFC converter when the current of the network-measured AC power changes suddenly. Fig.13 The voltage waveform shown is 0.2 times the voltage waveform of the AC power on the grid side ( Fig.13 The mark is 0.2v ac ) to observe the phase of voltage and current waveforms. Fig.13 It can be seen that the phases of the voltage and current on the grid side are basically the same, and when the AC current suddenly changes, the controller can quickly adjust the current to a stable state, so that a high-quality current waveform can be maintained before and after the current suddenly changes. Fig.14 A third signal simulation diagram of voltage and current is provided for an embodiment of the present application, which shows the voltage waveform and current waveform of the AC power when the voltage of the network-measured AC power changes suddenly and the controller using the compensation parameter model controls the Boost PFC converter. Fig.14 The voltage waveform shown is 0.15 times the voltage waveform of the grid-side AC power ( Fig.14 The mark is 0.15v ac ) to observe the phase of voltage and current waveforms. Fig.14 It can be seen that the phases of the voltage and current on the grid side are basically the same, and when the voltage of the AC power changes suddenly, the controller can quickly adjust the voltage to a stable state, so that a high-quality voltage waveform can be maintained before and after the voltage changes suddenly. At this time, no matter whether the voltage or current of the AC power on the grid side changes, the voltage and current can be kept in phase and a high-quality waveform can be guaranteed, which further indicates that the compensation parameter model has high anti-interference ability.

[0135] The following describes the effective range of the controller using the compensation parameter model, the controller using the resonant parameter model, and the controller using only the proportional control model instead of the two models. Currently, when the controller is controlling under different grid parameters, if the current THD of the AC power on the grid side is less than 3% (i.e., the harmonic content is small), it means that the controller is effective. At this time, when the compensation parameter model, the resonant control model, and the proportional control model are used for control, the range of the voltage and current on the grid side when the control is effective is as follows: Fig.15 Based on Fig.15 It can be seen that the effective control interval (i.e., the area surrounded by the lines representing PR) is the largest when the resonant control model is used, the effective control interval (i.e., the area surrounded by the lines representing P) is the smallest when only the proportional control model is used, and the effective control interval (i.e., the area surrounded by the lines representing Data) when the resonant control model is used is between the two. Fig.15 It can be seen that, since the compensation parameter model fitting process properly ignores the sudden compensation signal when the current passes through the zero point distortion, the control effect of the compensation parameter model is better than that of the resonant control model at a small voltage level. At this time, although the effective control interval when using the compensation parameter model is smaller than the effective control interval when using the resonant control model, it can also meet the application requirements of the Boost PFC converter.

[0136] After obtaining the compensation parameter model, the compensation parameter model can be used to replace the resonance coefficient model in the current loop. At this time, both current loops in the controller use the compensation parameter model. The signal processing flow of one current loop is as follows: Fig.16 Compared to Figure 4 The current loop shown, Fig.16 There is no resonance control part 21, but a compensation parameter model 23 is constructed instead. At this time, resonance control is no longer used, but data driving.

[0137] Afterwards, the controller using the compensation parameter model can be used to control the Boost PFC converter.

[0138] In the above, by collecting multiple compensation signals output by the resonant control model when the alternating current uses different grid parameters, and obtaining the compensation signal group corresponding to each grid parameter according to the multiple compensation signals, the preset target function group can be fitted according to each grid parameter and the corresponding compensation signal group to obtain the technical means of replacing the compensation parameter model of the resonant control model, which can solve the technical problem that the amount of calculation of the controller of the Boost PFC converter increases when the resonant controller is used. The resonant control model is replaced by the compensation parameter model, and the compensation parameter model is realized by the target function group, so that the compensation signal can be determined in a data-driven manner. At this time, the compensation parameter model can not only have the compensation effect of the resonant control model, but also simplify the amount of calculation and reduce the calculation time of the compensation signal. Moreover, by constructing the compensation parameter model through the compensation signals corresponding to different grid parameters, the compensation parameter model can be applied to different external conditions, which enhances the stability of the Boost PFC converter. Regardless of whether the external conditions change, better control can be performed, so that the grid-side current and voltage are quickly in phase, and the grid-side power quality is improved. In addition, setting a reasonable first target function and a second target function can simplify the calculation process on the basis of ensuring the compensation effect. In addition, delay processing is performed when collecting compensation signals to avoid the influence of zero-crossing distortion of grid-side current on the fitting objective function and ensure the compensation effect of the compensation parameter model. In addition, each grid parameter corresponds to multiple compensation signal groups. After that, the target compensation signal group for fitting is obtained based on multiple compensation signal groups, which can make the signal used for fitting better reflect the compensation signal that should be obtained under the grid parameters and avoid the influence of a sudden change of a compensation signal on the accuracy of fitting.

[0139] In one embodiment of the present application, a controller of a PFC converter (ie, a Boost PFC converter) is also provided. Fig.17 A schematic diagram of the structure of a controller of a PFC converter provided by an embodiment of the present application. Fig.17 The controller includes a voltage loop 41, a current loop 42 and a feedforward decoupling unit 43. There are two current loops 42 and two feedforward decoupling units 43. Each current loop 42 corresponds to the inductor current of a boost circuit in the PFC converter. The PFC converter includes a two-phase staggered parallel boost circuit. Each current loop includes a proportional control model 421, an adder 423 and the aforementioned compensation parameter model 422.

[0140] The voltage loop 41 is used to obtain a given current according to the DC voltage output by the PFC converter and a given voltage of the voltage loop.

[0141] The proportional control model 421 is used to obtain a first control signal according to the corresponding inductor current, the AC voltage of the AC power input into the PFC converter, and a given current.

[0142] The compensation parameter model 422 is used to obtain an actual compensation signal according to actual grid parameters of the AC power input into the PFC converter. The actual grid parameters include the current voltage amplitude and current value of the AC power.

[0143] The adder 423 is used for adding the first control signal and the actual compensation signal to obtain a second control signal output by the current loop.

[0144] The feedforward decoupling unit 43 is used to obtain a third control signal according to the second control signal, the AC voltage and the DC voltage, and the third control signal is used to control the PFC converter so that the voltage and current of the AC power input into the PFC converter have the same phase.

[0145] For example, the signal processing flow of the voltage loop 41 can refer to Figure 1 The signal processing flow of the medium voltage loop 10 is not described separately at present.

[0146] The signal processing flow of each current loop 42 can be referred to Fig.16 The signal processing flow of the current loop in FIG. 4 is shown in FIG. 4 . Figure 1 , Figure 4 and Fig.16 The signal processing flow in is not described separately at present. At present, the control signal output by the current loop 42 is recorded as the first control signal.

[0147] The objective function group included in the compensation parameter model 422 can be referred to Fig.16 The target function group of the compensation parameter model 23 in the compensation parameter model 422. At this time, the specific value of the second coefficient of each second target function can be referred to Table 1. The voltage amplitude and current value input by the compensation parameter model 422 can be based on Fig.16 The "amplitude obtaining" module in the current loop is determined, that is, the current loop may also include an amplitude obtaining module. After the amplitude obtaining module receives the voltage and current of the alternating current, it can output the voltage amplitude and current value. The implementation method of this module can adopt the existing implementation method, which is not described separately at present. The module can be implemented by a corresponding program. In addition, the compensation parameter model 422 can also input the position x corresponding to the current sampling moment in the current sampling period (that is, the position of the compensation signal in the compensation signal group). x can be determined according to the sampling period, the sampling frequency and the number of current samplings (or time). x can be directly input into the compensation parameter model 422 after being determined by the controller. At this time, the controller may also include a position determination module connected to the compensation parameter models in the two current loops. The position determination module can be implemented by a corresponding program. At this time, the position control module can input the x determined each time into the compensation parameter model 422.

[0148] Afterwards, the compensation parameter model 422 can determine the coefficient values ​​of each first coefficient in the first objective function according to the voltage amplitude and the current value, and then output the compensation signal according to the first objective function and the x value. Currently, the power grid parameters used in the application process of the compensation parameter model 244 are recorded as actual power grid parameters, and the output compensation signal is recorded as actual compensation signal.

[0149] In addition, the current loop also includes an adder 423, which is used to add the actual compensation signal and the first control signal output by the current loop to obtain the control signal output by the current loop 42. At present, the control signal output by the current loop 42 is recorded as the second control signal (corresponding to Fig.16 u k ).

[0150] The signal processing flow of the feedforward decoupling unit 43 can be referred to Fig.16 The signal processing flow 50 in the figure is the same as the feedforward decoupling processing flow of the controller in the related art, and is not described separately at present. Each current loop 42 corresponds to a feedforward decoupling unit 43, which is used to receive the second control signal output by the corresponding current loop 42, and according to the second control signal, the AC voltage (v ac ) and DC voltage (v o ) obtains a control signal representing the PWM duty cycle. Currently, the control signal is recorded as a third control signal. It can be understood that the two feedforward decoupling units 43 output two third control signals, and the two third control signals are respectively used to control the cutoff and conduction of switches corresponding to the two boost circuits in the PFC converter, so that the voltage and current of the alternating current input into the PFC converter have the same phase.

[0151] As mentioned above, after the controller of the PFC converter uses the compensation parameter model, it not only has the compensation effect of the resonant control model, but also can simplify the amount of calculation, reduce the calculation time of the compensation signal, and can be applied to different external conditions, thereby enhancing the stability of the Boost PFC converter. Regardless of whether the external conditions change, better control can be performed, so that the grid-side current and voltage are quickly in phase, thereby improving the grid-side power quality.

[0152] In one embodiment of the present application, a control system of a PPFC converter (ie, a Boost PFC converter) is also provided. Fig.18 A schematic diagram of a control system for a PFC converter provided by an embodiment of the present application. Fig.18 The control system 60 includes a sampling circuit 61, a driving circuit 62 and the aforementioned controller 63. The sampling circuit 61 and the driving circuit 62 are respectively connected to the controller and the PFC converter 70. The PFC converter 70 includes a two-phase staggered parallel boost circuit.

[0153] The sampling circuit 61 is used to collect the DC voltage output by the PFC converter, the inductor current in each boost circuit, and the AC voltage and current of the AC power input into the PFC converter.

[0154] The controller 63 is used to obtain a third control signal according to the DC voltage, the inductor current in each boost circuit, and the AC voltage and current of the AC power input into the PFC converter.

[0155] The driving circuit 62 is used to amplify the third control signal and control the PFC converter according to the amplified third control signal so that the voltage and current of the AC power input into the PFC converter have the same phase.

[0156] Currently, the circuit structures of the sampling circuit 61 and the driving circuit 62 are not limited, and reference may be made to the sampling circuit and the driving circuit used in the related art, and the sampling circuit 61 and the driving circuit 62 have the same functions as the sampling circuit and the driving circuit in the related art.

[0157] It can be understood that the driving circuit 62 receives two third control signals, and the two third control signals are used to control the switches of the two Boost circuits. Fig.19 A schematic diagram of a PFC converter and control system provided by an embodiment of the present application. Fig.19 The circuit structure of the PFC converter 70 adopts Figure 7 The circuit structure diagram shown in FIG. 6 shows a sampling circuit 61 that collects the voltage (v ac ), current (i ac ), two inductor currents (i L1 and i L2 ) and DC voltage (v o ), after which the controller 63 outputs two third control signals (i.e., control signals D) according to the signals collected by the sampling circuit 61. The implementation process of the controller 63 can refer to the aforementioned content. The driving circuit 62 outputs PWM signals for turning on and off the switches T1 and T2 according to the two third control signals. Among them, the PWM1 signal is used to control the switch T1, and the PWM2 signal is used to control the switch T2.

[0158] As mentioned above, after the compensation parameter model is used in the control system of the PFC converter, it not only has the compensation effect of the resonant control model, but also can simplify the amount of calculation, reduce the calculation time of the compensation signal, and can be applied to different external conditions, thereby enhancing the stability of the Boost PFC converter. Regardless of whether the external conditions change, better control can be performed, so that the grid-side current and voltage are quickly in phase, thereby improving the grid-side power quality.

[0159] An embodiment of the present application further provides a device for constructing a compensation parameter model, which can execute a method for constructing a compensation parameter model. The device can be the aforementioned controller or other devices integrated with a processor.

[0160] One embodiment of the present application also provides a storage medium containing computer executable instructions, which, when executed by a processor of a compensation parameter model construction device, are used to perform relevant operations in the compensation parameter model construction method provided in any embodiment of the present application, and have corresponding functions and beneficial effects.

[0161] Those skilled in the art should understand that the embodiments of the present application may be provided as methods, systems, or computer program products.

[0162] Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may take the form of a computer program product implemented 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. The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the functions in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be stored in a computer-readable memory that can guide a computer or other programmable data processing device to work in a specific way, so that the instructions stored in the computer-readable memory produce a product including an instruction device, which implements the functions specified in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide for implementing the process in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0163] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0164] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0165] Note that the above are only preferred embodiments of the present application and the technical principles used. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present application. Therefore, although the present application is described in more detail through the above embodiments, the present application is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present application, and the scope of the present application is determined by the scope of the appended claims.

Claims

1. A method for constructing a compensation parameter model, characterized in that: include: In the case where the alternating current input into the PFC converter uses different grid parameters, a plurality of compensation signals output by the resonant control model are collected, and a compensation signal group is obtained according to the plurality of compensation signals, each of the grid parameters corresponds to at least one compensation signal group, each of the compensation signal groups includes a plurality of compensation signals within a corresponding sampling period, the resonant control model is included in a current loop for controlling an inductor current of a boost circuit in the PFC converter, the current loop is located in a controller of the PFC converter, and the resonant control model is used to compensate for a control signal output by a proportional control model in the current loop; The preset objective function group is fitted according to each of the grid parameters and the corresponding compensation signal group, and the fitted objective function group is used as a compensation parameter model. The compensation parameter model is used to replace the resonant control model in the current loop to compensate the control signal output by the proportional control model according to the actual grid parameters.

2. The construction method according to claim 1, characterized in that: The objective function group includes a first objective function and a plurality of second objective functions, and each first coefficient in the first objective function corresponds to a second objective function; The step of fitting a preset objective function group according to each of the grid parameters and the corresponding compensation signal group, and using the fitted objective function group as a compensation parameter model, comprises: Fitting the first objective function according to the compensation signal group corresponding to each of the grid parameters to determine the coefficient value corresponding to the first coefficient in the first objective function under each of the grid parameters; Fitting the second objective function according to each of the grid parameters and the coefficient value of the first coefficient under each of the grid parameters to determine the coefficient value of the second coefficient in the second objective function; The first objective function and each of the fitted second objective functions are used as compensation parameter models.

3. The construction method according to claim 2, characterized in that: Each of the power grid parameters corresponds to a plurality of compensation signal groups, The fitting of the first objective function according to the compensation signal group corresponding to each of the grid parameters to determine the coefficient value corresponding to the first coefficient in the first objective function under each of the grid parameters includes: Determine a target compensation signal group corresponding to each of the power grid parameters according to the plurality of compensation signal groups corresponding to each of the power grid parameters; The target compensation signal in the target compensation signal group is used as the dependent variable of the first objective function, and the position of the target compensation signal in the target compensation signal group is used as the independent variable of the first objective function. The first objective function is fitted to determine the coefficient value corresponding to the first coefficient in the first objective function under each of the power grid parameters.

4. The construction method according to claim 2, characterized in that: Each grid parameter includes a voltage amplitude and a current value of the alternating current.

5. The construction method according to claim 4, characterized in that: The first objective function is a first-order Fourier function, and the second objective function is a binary high-order polynomial.

6. The construction method according to claim 5, characterized in that: The formula of the first-order Fourier function is as follows: f(x)=a0+a1cos(ωx)+b1sin(ωx) Wherein, f(x) represents the target compensation signal, x represents the position of the target compensation signal in the target compensation signal group, and a0, a1, b1 and ω are all first coefficients used in the first objective function.

7. The construction method according to claim 6, characterized in that: There are four second objective functions, and the formulas of the four second objective functions are as follows: Wherein, u represents the voltage amplitude of the alternating current in the power grid parameter, i represents the current value of the alternating current in the power grid parameter, a0, a1, b1 and ω are all the first coefficients used in the first objective function, m 01 、m 02 、m 03 、m 04 、m 05 and m 06 are the second coefficients used in the second objective function corresponding to a0, m 11 、m 12 、m 13 、m 14 、m 15 and m 16 are the second coefficients used in the second objective function corresponding to a1, m 21 、m 22 、m 23 、m 24 、m 25 and m 26 are the second coefficients used in the second objective function corresponding to b1, m 31 、m 32 、m 33 、m 34 、m 35 、m 36 、m 37 、m 38 and m 39 Both are the second coefficients used in the second objective function corresponding to ω.

8. The construction method according to claim 3, characterized in that: The step of determining a target compensation signal group corresponding to each of the power grid parameters according to the plurality of compensation signal groups corresponding to each of the power grid parameters comprises: Calculate the average value of each compensation signal with the same position between each compensation signal group corresponding to the power grid parameter, and use the average value as the target compensation signal at the corresponding position. Each of the target compensation signals constitutes a target compensation signal group corresponding to the power grid parameter, and each of the power grid parameters has a corresponding target compensation signal group.

9. The construction method according to claim 1, characterized in that: The collecting of multiple compensation signals output by the resonance control model includes: After a set number of compensation signals have passed since the start of a current cycle, the multiple compensation signals output by the resonance control model are collected, and the time length of the current cycle and the sampling cycle are equal.

10. A controller for a PFC converter, characterized in that: The controller comprises: a voltage loop, a current loop and a feedforward decoupling unit, the current loop and the feedforward decoupling unit are both two, each current loop corresponds to the inductor current of a boost circuit in the PFC converter, the PFC converter comprises a two-phase staggered parallel boost circuit, and each current loop comprises a proportional control model, an adder and a compensation parameter model as claimed in any one of claims 1 to 9; The voltage loop is used to obtain a given current according to the DC voltage output by the PFC converter and a given voltage of the voltage loop; The proportional control model is used to obtain a first control signal according to the corresponding inductor current, the AC voltage of the AC power input into the PFC converter and the given current; The compensation parameter model is used to obtain an actual compensation signal according to actual grid parameters of the alternating current input into the PFC converter, wherein the actual grid parameters include a current voltage amplitude and a current value of the alternating current; The adder is used for adding the first control signal and the actual compensation signal to obtain a second control signal output by the current loop; The feedforward decoupling unit is used to obtain a third control signal according to the second control signal, the AC voltage and the DC voltage, and the third control signal is used to control the PFC converter so that the voltage and current of the AC power input into the PFC converter have the same phase.

11. A control system for a PFC converter, characterized in that: The PFC control system comprises: a sampling circuit, a driving circuit and the controller according to claim 10, wherein the sampling circuit and the driving circuit are respectively connected to the controller and the PFC converter, and the PFC converter comprises a two-phase staggered parallel boost circuit; The sampling circuit is used to collect the DC voltage output by the PFC converter, the inductor current in each of the boost circuits, and the AC voltage and current of the AC power input into the PFC converter; The controller is used to obtain a third control signal according to the DC voltage, the inductor current in each of the boost circuits, and the AC voltage and current of the AC power input into the PFC converter; The driving circuit is used to amplify the third control signal and control the PFC converter according to the amplified third control signal so that the voltage and current of the alternating current input into the PFC converter have the same phase.

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