Control circuit, method, system, and readable storage medium for a multi-level converter

Abstract

The application discloses a kind of control circuit, method, system and readable storage medium of multistage converter, belong to power electronics field.The control circuit of the multistage converter overcomes the defects of previous power control in feedforward control, by the change value given by output current reference and power module current following characteristic, the calculation method of current feedforward control amount is proposed, the synchronous action of each power module of multistage converter is realized by feedforward control, when output power reduces, or output current changes quickly, feedforward control effect will not be obviously reduced, improve the existing feedforward control scheme, improve the dynamic response of multistage converter system in wider application occasion.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power electronics, and particularly relates to a control circuit, method, system and readable storage medium of a multi-stage converter. BACKGROUND

[0002] In order to meet the requirements of a wide input or output voltage range, high efficiency, high dynamic response and the like of the converter, the converter needs to be formed by two or more stages of topologies in series.

[0003] When the number of stages of the topology increases, the system order increases, thereby causing poor dynamic response of the converter. In order to solve this problem, power of a later stage of topology can be fed forward to an earlier stage of topology, so that the earlier stage and the later stage can change simultaneously when a change occurs at the output end, thereby improving the output response while maintaining the stability of the output voltage of the earlier stage.

[0004] In the existing feedforward control, most of them are power feedforward. The power feedforward can work in the steady state, thereby reducing the role of the controller of the earlier stage. However, when the output power decreases or the output current changes rapidly, the feedforward control function will be significantly reduced. Therefore, the existing control method cannot effectively perform feedforward control. SUMMARY

[0005] The main purpose of the present application is to provide a control circuit, method, system and readable storage medium of a multi-stage converter, which aims to solve the technical problem of how to improve the existing feedforward control scheme to improve the dynamic response of the converter system in a wider application occasion.

[0006] To achieve the above-mentioned purpose, the present application provides a control circuit of a multi-stage converter, which is applied to a multi-stage converter, the multi-stage converter comprising a plurality of power modules connected in series, and the control circuit of the multi-stage converter comprising at least one earlier stage control module and one last stage control module, wherein,

[0007] Each of the earlier stage control modules comprises a voltage outer loop control loop and a current inner loop control loop, the voltage outer loop control loop being configured to determine a reference current based on a voltage reference instruction of a bus capacitor corresponding to a current power module and a bus capacitor voltage;

[0008] The current inner loop control loop is configured to determine a first driving signal of the current power module according to the reference current, an output current of the current power module and an output current reference instruction of a last stage power module, the first driving signal being configured to control the current power module to maintain the stability of the bus capacitor voltage; wherein the last stage power module corresponds to the last stage control module.

[0009] The last-stage control module comprises a current control loop, which is configured to determine a second driving signal of the last-stage power module according to an output sampling current of the last-stage power module and an output current reference instruction, and the second driving signal is used to control the last-stage power module to dynamically adjust the output current of the last-stage power module.

[0010] Optionally, the voltage outer loop control loop comprises:

[0011] a voltage sampling circuit, configured to acquire and output the bus capacitor voltage;

[0012] a voltage controller, configured to determine the reference current based on a difference between the voltage reference instruction of the bus capacitor corresponding to the current power module and the bus capacitor voltage.

[0013] Optionally, the current inner loop control loop comprises:

[0014] a feedforward controller, configured to generate and output a feedforward output current according to the output current reference instruction of the last-stage power module;

[0015] a front-stage current controller, configured to determine the first driving signal;

[0016] a front-stage modulation module, configured to generate a first modulation signal according to the first driving signal and output the first modulation signal to the current power module;

[0017] a current sampling circuit, configured to acquire and output the output current of the current power module.

[0018] Optionally, the current control loop comprises:

[0019] a last-stage current controller, configured to determine the second driving signal;

[0020] a last-stage modulation module, configured to generate a second modulation signal according to the second driving signal and output the second modulation signal to the last-stage power module;

[0021] a last-stage sampling circuit, configured to acquire and output the output sampling current of the last-stage power module.

[0022] Optionally, the voltage outer loop control loop further comprises:

[0023] a first operation unit, an input end of the first operation unit being connected with an output end of the voltage sampling circuit, an output end of the first operation unit being connected with an input end of the voltage controller, the first operation unit being used for outputting a difference value between the voltage reference instruction and the bus capacitor voltage.

[0024] Optionally, the current inner loop control loop further comprises:

[0025] a second operation unit, an input end of the second operation unit being connected with an output end of the voltage controller, an output end of the circuit sampling circuit and an output end of the feedforward controller, an output end of the second operation unit being connected with an input end of the front-stage current controller, the second operation unit being used for outputting a difference value between a reference input current and an output current of the current power module, wherein the reference input current is a superimposed value of the reference current and the feedforward output current.

[0026] Optionally, the circuit control loop further comprises:

[0027] a third operation unit, an input end of the third operation unit being connected with an output end of the final-stage sampling circuit, an output end of the third operation unit being connected with an input end of the final-stage current controller, the third operation unit being used for outputting a difference value between the output current reference instruction and the output sampling current.

[0028] In addition, to achieve the above-mentioned purpose, the application further provides a control system of a multi-stage converter, the control system of the multi-stage converter comprising: a multi-stage converter and a control circuit of the multi-stage converter as described above, wherein the multi-stage converter comprises power modules connected in series in multiple stages, and a bus capacitor is arranged between two adjacent power modules.

[0029] In addition, to achieve the above-mentioned purpose, the application further provides a control method of a multi-stage converter, the control method of the multi-stage converter being applied to the control system of the multi-stage converter as described above, the control method of the multi-stage converter comprising the following steps:

[0030] in the case that the working mode of the multi-stage converter is a current mode, the voltage reference instruction and the bus capacitor voltage of each bus capacitor in the multi-stage converter are respectively obtained through each voltage outer loop control loop;

[0031] the output sampling current and the output current reference instruction of the final-stage power module are obtained through the current control loop;

[0032] the reference current is determined based on the difference value between the voltage reference instruction and the bus capacitor voltage of the corresponding bus capacitor through the voltage outer loop control loop of the current power module, wherein the current power module is any power module in the multi-stage converter except the final-stage power module;

[0033] generate a first driving signal of the current power module according to the reference current, an output current of the current power module and the output current reference command through an inner loop control loop of the current power module; wherein the first driving signal is used to control the current power module to maintain stability of the bus capacitor voltage;

[0034] generate a second driving signal of the final-stage power module according to the output sampling current and the output current reference command through the current control loop; wherein the second driving signal is used to control the final-stage power module to dynamically adjust the output current of the final-stage power module.

[0035] In addition, to achieve the above object, the application further provides a computer readable storage medium, wherein the computer readable storage medium stores a control program of a multi-stage converter, and the control program of the multi-stage converter, when executed by a processor, implements the steps of the control method of the multi-stage converter.

[0036] The application provides a control circuit, method, system and readable storage medium of a multi-stage converter, wherein the control circuit of the multi-stage converter overcomes the defects of the previous power control in feedforward control, and a calculation method of a current feedforward control amount is provided through a given change value of an output current reference and a power module current following characteristic, so that the synchronous action of each power module of the multi-stage converter is realized through feedforward control, and the feedforward control effect does not decrease obviously when the output power decreases or the output current changes rapidly, the existing feedforward control scheme is improved, and the dynamic response of the multi-stage converter system in a wider application occasion is improved. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description only constitute some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the drawings shown.

[0038] Figure 1 a module schematic diagram of an embodiment of the control circuit of the multi-stage converter of the present application;

[0039] Figure 2 a two-stage converter system control block diagram in an embodiment of the control circuit of the multi-stage converter of the present application;

[0040] Figure 3 a schematic diagram of the relationship between the output current following and the output current reference command in an embodiment of the control circuit of the multi-stage converter of the present application;

[0041] Figure 4 The control block diagram of the multi-stage converter system in an embodiment of the control circuit of the multi-stage converter of the present application;

[0042] Figure 5 The terminal structure diagram of the multi-stage converter control system involved in the embodiment of the present application.

[0043] Figure 6 The flowchart of the control method of the multi-stage converter of the present application.

[0044] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0045] It should be understood that the specific embodiments described herein merely exemplify the present application and are not intended to limit the present application.

[0046] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0047] It should be noted that all the directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative position relationship, movement condition, etc. between the components in a certain posture (as shown in the drawings), and if the certain posture changes, the directional indications will also change accordingly.

[0048] In addition, the descriptions of “first”, “second” and the like in the present application are only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features with “first”, “second” can explicitly or implicitly include at least one of the features. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of those skilled in the art, and when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the protection scope of the present application.

[0049] The embodiment of the present application provides a control circuit of a multi-stage converter, which refers to Figure 1 , Figure 1 The module diagram of the control circuit of the multi-stage converter of the present application.

[0050] In this embodiment, the control circuit of the multi-stage converter is applied to the multi-stage converter 10, which includes multiple power modules connected in series. The control circuit of the multi-stage converter includes at least one front-end control module 20 and one final-end control module 30, wherein...

[0051] Each of the aforementioned front-end control modules 20 includes a voltage outer loop control loop and a current inner loop control loop. The voltage outer loop control loop is used to determine a reference current based on the voltage reference command of the bus capacitor corresponding to the current power module and the bus capacitor voltage.

[0052] The current inner loop control circuit is used to determine the first drive signal of the current power module based on the reference current, the output current of the current power module and the output current reference command of the final stage power module. The first drive signal is used to control the current power module to maintain the stability of the bus capacitor voltage.

[0053] The final stage control module 30 includes a current control loop, used to determine a second drive signal for the final stage power module based on the output sampling current and the output current reference command of the final stage power module. The second drive signal is used to control the final stage power module to dynamically adjust the output current of the final stage power module.

[0054] It should be noted that, for ease of understanding, this embodiment also provides a detailed structural diagram of the control circuit of a multi-stage converter, referring to... Figure 2 , Figure 2 Taking a two-stage converter composed of two-stage topologies connected in series as an example, based on Figure 1 Control block diagram of the constructed two-stage converter system. Figure 2 In this diagram, power module M1 corresponds to the current power module, power module M2 corresponds to the final stage power module, and C is the bus capacitor between the power modules. Power modules M1 and M2 form a single-stage non-isolated or isolated converter topology composed of switching devices, inductors, capacitors, or transformers. When these two-stage converters operate in current mode, they are dynamically controlled using a front-end control module 20 and a final-stage control module 30. In this embodiment, the reference positive directions of voltage and current are set as follows: Figure 2 As shown by the middle arrow, set U in I in For the input voltage and current of the converter, U o I o I1 represents the output voltage and current of the converter, I2 represents the output current of power module M1, and I3 represents the output current of power module M2. c The output current is the bus capacitor C.

[0055] As an example, in this embodiment, the voltage outer loop control loop includes:

[0056] a voltage sampling circuit, configured to acquire and output the bus capacitor voltage U C ;

[0057] a voltage controller, configured to determine a voltage reference instruction U Cref of the bus capacitor corresponding to the current power module based on a difference between the bus capacitor voltage U C and the reference current I M1ref ;

[0058] a first operation unit 201, an input end of the first operation unit 201 being connected with an output end of the voltage sampling circuit, an output end of the first operation unit being connected with an input end of the voltage controller, the first operation unit being configured to output a difference between the voltage reference instruction U Cref and the bus capacitor voltage U C .

[0059] It should be noted that the voltage reference instruction U Cref is a preset value which can be modified artificially and can be modified according to actual requirements; Figure 2 In the circuit diagram, the symbol of the bulb represents an operation unit, which is used to represent that two or more signals are synthesized and outputted here. As can be seen, the first operation unit 201 contains a + sign at the position of the input U Cref , and contains a - sign at the position of the input U C , so the input of the voltage controller is U Cref -U C .

[0060] As an example, in the embodiment, the current inner loop control loop comprises:

[0061] a feedforward controller, configured to generate and output a feedforward output current I oref according to an output current reference instruction I FB of the last-stage power module;

[0062] a front-stage current controller, configured to determine the first driving signal;

[0063] a front-stage modulation module, configured to generate a first modulation signal according to the first driving signal, and output the first modulation signal to the current power module;

[0064] a current sampling circuit, configured to acquire and output an output current I1 of the current power module;

[0065] A second operation unit 202, an input end of the second operation unit 202 being connected with an output end of the voltage controller, an output end of the circuit sampling circuit and an output end of the feedforward controller, an output end of the second operation unit 202 being connected with an input end of the front-stage current controller, the second operation unit 202 being used for outputting a difference between a reference input current and an output current I1 of the current power module, wherein the reference input current is a superimposed value of the reference current I M1ref and the feedforward output current I FB .

[0066] It is to be noted that the output current reference instruction I oref of the final-stage power module is a preset value which can be modified artificially and is modified according to actual requirements; in the embodiment, the reference input current is set as I 1ref , and the output of the second operation unit 202, i.e. the input value of the front-stage current controller, is I 1ref -I1 or I M1ref +I FB -I1; the first driving signal is a duty cycle output by the front-stage current controller; and the front-stage modulation module corresponds to PWM (Pulse width modulation) modulation 1 on the left side in Figure 2 , the front-stage modulation module receives the duty cycle output by the front-stage current controller, generates a PWM signal (i.e. the first modulation signal) after pulse width modulation, and outputs the PWM signal to the power module M1 to drive the power switching device in the power module M1, so as to realize fast adjustment of the output power while maintaining the stability of the bus capacitor voltage C.

[0067] In the embodiment, the feedforward output current I FB is a feedforward current reference value of the output current I o of the final-stage power module during dynamic adjustment, and the derivation process is as follows:

[0068] In the embodiment, the output current reference instruction I oref of the converter adopts ramp control, and the adjustment step in a control period T is I oref_step , I oref_step can be set through a man-machine interface. Considering the sampling delay, control delay and the like, the output current I o follows the output current reference instruction I oref with a certain phase μT during dynamic adjustment, and can realize error-free tracking in a steady state, and a schematic diagram is shown in Figure 3 .

[0069] In this embodiment, an average periodic control method is used (i.e., the average value within one control cycle is used as the reference value or sampled value), and the current output current reference command is denoted as I. oref (nT) (where T is the control cycle of the current controller, and n is the control cycle count, which can take the value 1, 2, 3...n), let the current output current sampling value be I. o (nT), the current output current of power module M1 is I1(nT), and the output current of the bus capacitor is I. c The input current of power module M2 is I2(nT), and the influence of the input and output capacitances of power modules M1 and M2 is ignored.

[0070] In steady state (output current reference command I) oref unchanged, I o Zero-error follow output current reference command I oref ), satisfying I oref (nT)=I o (nT)=N*I 2( nT)=N*I1(nT), and I c (nT) = 0, where N is the gain between the output current and the input current of the subsequent power module M2.

[0071] In dynamic cases, I oref (nT-μ2T)=I o (nT)=N*I2(nT)(i.e., output current I o (nT) refers to the output current reference command I. oref (nT) is followed by a certain phase μ2T, where μ2 is a real number). Similarly, the output current I1(nT) of power module M1 is related to the output current sampling I. 1ref The relationship between (nT) satisfies I 1ref (nT-μ1T)=I1(nT). To improve the dynamic response speed of the output current, the currents of the preceding and following stages need to change synchronously, and it is also desirable that the bus capacitor voltage U... C If it remains unchanged, that is, the output current Ic(nT) of the bus capacitor is basically zero, then I oref (nT-μ2T)=I o (nT)=N*I2(nT)=N*I1(nT)=N*I 1ref (nT-μ1T).

[0072] During the dynamic process, the output current I o The change value ΔI in the next control cycle o (nT) can be the output current reference command I that lags behind the next control cycle by a phase of μ2. oref[(n+1)T-μ2T] and the output current reference command I that lags the current control cycle by a phase of μ2. oref The difference (nT-μ2T) can also be the product of the difference between the input current I2[(n+1)T] of the power module M2 in the next control cycle and the input current I2(nT) of the power module M2 in the current control cycle, multiplied by the gain N.

[0073] Similarly, the change ΔI1(nT) of the output current I1 of power module M1 in the next control cycle can be represented by the output current sample I1 that lags behind the next control cycle by a phase μ1. 1ref [(n+1)T-μ1T] and the output current sample I with a phase lag of μ1 compared to the current control cycle. 1ref The difference of (nT-μ1T) can also be the output current reference command I that lags behind the next control cycle by a phase of μ2. oref [(n+1)T-μ2T] and the output current reference command I that lags the current control cycle by a phase of μ2. oref The quotient is obtained by dividing the difference (nT-μ2T) by the gain N.

[0074] During dynamic adjustment, it is desirable to maintain a constant bus capacitor voltage; therefore, the current reference value I output by the voltage controller of power module M1 is... M1ref The current remains essentially unchanged. Therefore, the feedforward output current I in the current control cycle... FB (nT) can be the change in the output current I1 of power module M1 at a phase ahead of μ1 of the current control cycle, ΔI1(nT+μ1T), or the change in the input current I2 of power module M2 at a phase ahead of μ1 of the current control cycle, ΔI2(nT+μ1T).

[0075] From the above derivation, we can obtain the feedforward output current I of the current control cycle. FB (nT) can be the quotient ΔI, which is the change in output current during the current control cycle divided by the gain N. o (nT) / N can also be the output current reference command I for a control cycle that is μ1 phase ahead and μ2 phase behind the next control cycle. oref [(n+1)T+μ1T-μ2T] and the output current reference command I of the control cycle that is μ1 phase ahead and μ2 phase behind the current control cycle. oref The quotient is obtained by dividing the difference (nT+μ1T-μ2T) by the gain N.

[0076] From the above conclusions, it can be seen that when the output reference current increases, I... FB (nT)=I oref_step When the output reference current decreases, I FB (nT)=-I oref_step When the output reference current remains constant, IFB (nT) = 0; that is, feedforward instruction I FB (nT) is related to the change in the output reference current command, and the phase difference is μ1-μ2 control cycles.

[0077] As an example, in this embodiment, the current control loop includes:

[0078] A final-stage current controller, wherein the final-stage current controller is used to determine the second drive signal;

[0079] The final stage modulation module is used to generate a second modulation signal according to the second driving signal and output the second modulation signal to the final stage power module;

[0080] The final-stage sampling circuit is used to acquire and output the output sampling current I of the final-stage power module. o ;

[0081] The third arithmetic unit 301 has its input terminal connected to the output terminal of the final-stage sampling circuit, and its output terminal connected to the input terminal of the final-stage current controller. The third arithmetic unit 301 is used to output the output current reference command I. oref and output sampling current I o The difference.

[0082] It is understandable that the output of the third arithmetic unit 301, i.e. the input value of the final stage current controller, is I. oref -I o The second drive signal is the duty cycle output by the final stage current controller; the final stage modulation module corresponds to... Figure 2 The PWM modulation 2 on the right side of the middle section involves the final stage current controller outputting a duty cycle that is pulse-width modulated by the final stage modulation module to generate a pulse-width modulated signal (i.e., the second modulation signal). This pulse-width modulated signal is then output to the power module M2 to drive the power switching devices within the power module M2, thereby dynamically adjusting the output current I of the power module M2. o .

[0083] The system control block diagram of the multi-stage converter is as follows: Figure 4 As shown, Figure 4 Is Figure 2 The expansion based on this principle involves extending the two-stage converter into a multi-stage converter. For each additional power module and bus capacitor, a corresponding pre-stage control module is added for modulation. Figure 4 And the aforementioned current feedforward control quantity I FB The derivation steps show that, based on the output power module M mOutput current reference command I oref and current power module M k The output current following characteristic can be used to determine the current power module M. k (1<=k<=m-1, k is the power module M) k (where m is the sequence number of the power modules) The dynamic feedforward value to be superimposed for the current reference is:

[0084] I Mk_FB_ (nT)={I oref [(n+1)T+μ k T-μ m T]-I oref (nT+μ k T-μ m T)} / N;

[0085] In the above formula, m is the serial number of the output power module. This dynamic feedforward value can maintain the stability of the bus capacitor voltage between power modules, reduce over-adjustment during dynamic adjustment, and improve the control accuracy and dynamic response speed of the output current.

[0086] In this embodiment, a control circuit for a multi-stage converter is proposed. This control circuit overcomes the shortcomings of previous power control methods in terms of feedforward control. By referencing a given change value of the output current and the current following characteristics of the power modules, a method for calculating the feedforward control quantity of the circuit is proposed. Through feedforward control, the synchronous operation of each power module of the multi-stage converter is realized. When the output power decreases or the output current changes rapidly, the feedforward control effect will not be significantly reduced, thus improving the existing feedforward control scheme and enhancing the dynamic response of the multi-stage converter system in a wider range of applications.

[0087] This invention provides a control system for a multi-stage converter. The control system includes a multi-stage converter and a control circuit for the multi-stage converter as described above. The multi-stage converter includes multiple power modules connected in series, with a bus capacitor positioned between adjacent power modules. (Refer to...) Figure 5 , Figure 5 This is a schematic diagram of the terminal structure of the control system for the multi-stage converter involved in the embodiments of the present invention.

[0088] like Figure 5As shown, the control system of the multi-stage converter may further include: a processor 1001, such as a central processing unit (CPU), a communication bus 1002, a user interface 1003, a network interface 1004, and a memory 1005. The communication bus 1002 is used to enable communication between these components. The user interface 1003 may include a display screen or an input unit such as a keyboard; optionally, the user interface 1003 may also include a standard wired interface or a wireless interface. The network interface 1004 may optionally include a standard wired interface or a wireless interface (such as a Wi-Fi interface). The memory 1005 may be a high-speed random access memory (RAM) or a stable non-volatile memory (NVM), such as a disk drive. The memory 1005 may also optionally be a storage device independent of the aforementioned processor 1001.

[0089] Those skilled in the art will understand that Figure 5 The structure of the control system for the multi-stage converter shown in the figure does not constitute a limitation on the control system for the multi-stage converter. It may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0090] like Figure 5 As shown, the memory 1005, which serves as a computer storage medium, may include an operating system, a data storage module, a network communication module, a user interface module, and a control program for a multi-stage converter.

[0091] exist Figure 5 In the terminal shown, the network interface 1004 is mainly used for data communication with other devices; the user interface 1003 is mainly used for data interaction with the user; the processor 1001 and the memory 1005 in the terminal of this embodiment can be set in the terminal, and the terminal calls the control program of the multi-stage converter stored in the memory 1005 through the processor 1001 and executes the control method of the multi-stage converter provided in this embodiment.

[0092] This invention provides a control method for a multi-stage converter, referring to... Figure 6 , Figure 6 This is a flowchart illustrating an embodiment of a control method for a multi-stage converter according to the present invention.

[0093] In this embodiment, the control method for the multi-stage converter includes:

[0094] Step S10: When the multi-stage converter is operating in current mode, the voltage reference command and bus capacitor voltage of each bus capacitor in the multi-stage converter are obtained through each voltage outer loop control loop.

[0095] Step S20: Obtain the output sampling current and output current reference command of the final stage power module through the current control loop;

[0096] Step S30: Determine the reference current based on the voltage reference command of the corresponding bus capacitor and the difference between the bus capacitor voltage through the voltage outer loop control loop of the current power module; wherein, the current power module is any power module in the multi-stage converter except the final stage power module;

[0097] Step S40: The current inner loop control loop of the current power module generates a first drive signal for the current power module based on the reference current, the output current of the current power module, and the output current reference command; wherein, the first drive signal is used to control the current power module to maintain the stability of the bus capacitor voltage;

[0098] Step S50: The current control loop generates a second drive signal for the final stage power module based on the output sampling current and the output current reference command; wherein the second drive signal is used to control the final stage power module to dynamically adjust the output current of the final stage power module.

[0099] This embodiment corresponds to Figure 1 In this embodiment of the method, the operating mode of the control circuit of the multi-stage converter is switched and the control module is configured to enable the current feedforward control in the above embodiment. This overcomes the defects of the previous power feedforward control. By referencing the given change value of the output current and the current following characteristics of the power module, a method for calculating the circuit feedforward control quantity is designed. The synchronous operation of each power module of the multi-stage converter is realized through feedforward control. When the output power decreases or the output current changes rapidly, the feedforward control effect will not be significantly reduced. This improves the existing feedforward control scheme and enhances the dynamic response of the multi-stage converter system in a wider range of applications.

[0100] Furthermore, embodiments of the present invention also propose a computer-readable storage medium storing a control program for a multi-stage converter. When the control program for the multi-stage converter is executed by a processor, it performs the following operations:

[0101] Switch the operating mode of the multi-stage converter to current mode;

[0102] Configure a front-stage control module for the front-stage power module and a rear-stage control module for the rear-stage power module;

[0103] The output power of the front-end power module is dynamically adjusted based on the front-end control module, and the bus capacitor voltage U is maintained. c It is in a stable state;

[0104] The output current I of the downstream power module is dynamically adjusted based on the downstream control module. o .

[0105] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0106] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0107] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0108] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A control circuit for a multi-stage converter, applied to a multi-stage converter, the multi-stage converter comprising multiple power modules connected in series, characterized in that, The control circuit of the multi-stage converter includes: at least one front-end control module and one final-end control module, wherein... Each of the aforementioned front-end control modules includes a voltage outer loop control loop and a current inner loop control loop. The voltage outer loop control loop is used to determine a reference current based on the voltage reference command of the bus capacitor corresponding to the current power module and the bus capacitor voltage. The current inner loop control circuit is used to determine the first drive signal of the current power module based on the reference current, the output current of the current power module, and the output current reference command of the final stage power module. The first drive signal is used to control the current power module to maintain the stability of the bus capacitor voltage. The final stage power module corresponds to the final stage control module. The final stage control module includes a current control loop, which is used to determine a second drive signal for the final stage power module based on the output sampling current and the output current reference command of the final stage power module. The second drive signal is used to control the final stage power module to dynamically adjust the output current of the final stage power module.

2. The control circuit of the multi-stage converter as described in claim 1, characterized in that, The voltage outer loop control circuit includes: A voltage sampling circuit, which is used to acquire and output the bus capacitor voltage; A voltage controller is used to determine the reference current based on the voltage reference command of the bus capacitor corresponding to the current power module and the difference between the bus capacitor voltage.

3. The control circuit of the multi-stage converter as described in claim 1, characterized in that, The current inner loop control circuit includes: The feedforward controller is used to generate and output a feedforward output current according to the output current reference command of the final stage power module; A front-end current controller, wherein the front-end current controller is used to determine the first drive signal; A pre-amplifier modulation module is configured to generate a first modulation signal based on the first drive signal and output the first modulation signal to the current power module. A current sampling circuit is used to acquire and output the output current of the current power module.

4. The control circuit of the multi-stage converter as described in claim 1, characterized in that, The current control loop includes: A final-stage current controller, wherein the final-stage current controller is used to determine the second drive signal; The final stage modulation module is used to generate a second modulation signal according to the second driving signal and output the second modulation signal to the final stage power module; The final stage sampling circuit is used to acquire and output the output sampling current of the final stage power module.

5. The control circuit of the multi-stage converter as described in claim 2, characterized in that, The voltage outer loop control circuit also includes: The first arithmetic unit has its input terminal connected to the output terminal of the voltage sampling circuit and its output terminal connected to the input terminal of the voltage controller. The first arithmetic unit is used to output the difference between the voltage reference command and the bus capacitor voltage.

6. The control circuit of the multi-stage converter as described in claim 3, characterized in that, The inner current control loop also includes: The second arithmetic unit has its input terminal connected to the output terminal of the voltage outer loop control loop, the output terminal of the current sampling circuit, and the output terminal of the feedforward controller. The output terminal of the second arithmetic unit is connected to the input terminal of the front-stage current controller. The second arithmetic unit is used to output the difference between the reference input current and the output current of the current power module, wherein the reference input current is the superposition value of the reference current and the feedforward output current.

7. The control circuit of the multi-stage converter as described in claim 4, characterized in that, The current control loop also includes: The third arithmetic unit has its input terminal connected to the output terminal of the final stage sampling circuit, and its output terminal connected to the input terminal of the final stage current controller. The third arithmetic unit is used to output the difference between the output current reference command and the output sampling current.

8. A control system for a multi-stage converter, characterized in that, The control system of the multi-stage converter includes: a multi-stage converter and a control circuit for the multi-stage converter as described in any one of claims 1-7, wherein the multi-stage converter includes multiple power modules connected in series, and a bus capacitor is provided between two adjacent power modules.

9. A control method for a multi-stage converter, characterized in that, The control method for the multi-stage converter is applied to the control system of the multi-stage converter as described in claim 8, and the control method for the multi-stage converter includes the following steps: When the multi-stage converter operates in current mode, the voltage reference command and bus capacitor voltage of each bus capacitor in the multi-stage converter are obtained through each voltage outer loop control loop. The output sampling current and output current reference command of the final stage power module are obtained through the current control loop; The reference current is determined by the voltage outer loop control loop of the current power module based on the voltage reference command of the corresponding bus capacitor and the difference between the bus capacitor voltage; wherein, the current power module is any power module in the multi-stage converter except the final stage power module; The current inner loop control circuit of the current power module generates a first drive signal for the current power module based on the reference current, the output current of the current power module, and the output current reference command; wherein, the first drive signal is used to control the current power module to maintain the stability of the bus capacitor voltage; The current control loop generates a second drive signal for the final stage power module based on the output sampling current and the output current reference command; wherein the second drive signal is used to control the final stage power module to dynamically adjust the output current of the final stage power module.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a control program for a multi-stage converter, which, when executed by a processor, implements the steps of the control method for the multi-stage converter as described in claim 9.

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