DC conversion system and its control method

Abstract

The present invention provides a DC conversion system and a control method thereof, including: an upper power module group including at least two first power modules; a lower power module group including at least two second power modules; the input ends of the upper power module group and the lower power module group are connected in series, and the output ends of the upper power module group and the lower power module group are connected in parallel; a controller, coupled to the upper power module group and the lower power module group, the controller receives and generates a modulation signal based on the input voltage of each of the input ends of the first power modules and the second power modules, the first output current of the output end of the upper power module group, the second output current of the output end of the lower power module group, and a total output signal of the output end of the DC conversion system, so as to control the switches in each of the first power modules and the second power modules to act. The technical solution of the present invention can achieve voltage balance on the high-voltage series side of the DC conversion system.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and more particularly, to a DC conversion system and a control method thereof. Background Art

[0002] With the development of industry and the increase of electrical equipment, the requirements for the reliability of power supply and the voltage and current are gradually increasing. Due to the limitations of the voltage and current stresses of power switching devices, a single power supply cannot meet the application scenarios of high voltage and high power. By using a DC / DC (Direct Current / Direct Current) combined converter with series connection on the high voltage side and parallel connection on the low voltage side, the power can be evenly distributed to each DC / DC unit, reducing the voltage and current stresses of each unit, and thus better low-voltage power switching devices can be selected. In addition, each DC / DC unit of the DC / DC combined converter with series connection on the high voltage side and parallel connection on the low voltage side has modular characteristics, with a short development cycle and is easy to expand and design redundantly.

[0003] In a DC / DC combined converter system with series connection on the high voltage side and parallel connection on the low voltage side, to ensure the stable operation of the converter system, it is necessary to ensure the voltage balance on the series side and the current balance on the parallel side of the DC / DC units. Especially when the parameters of the DC conversion system have a great influence on the voltage deviation, the voltage imbalance is more serious, which will affect the selection of switching tubes and thermal design, etc., reducing the system performance and reliability. Therefore, corresponding voltage equalization measures need to be taken.

[0004] In a DC / DC combined converter system with series connection on the high voltage side, parallel connection on the low voltage side, and the midpoint of the high voltage side grounded in the related art, it is required that the voltages of the upper and lower parts of the midpoint are balanced. However, when the parameters of the DC / DC units in the upper and lower parts of the midpoint are different, for example, the number of units in the upper and lower parts of the midpoint is inconsistent, or the loads in the upper and lower parts of the midpoint are different, the voltage deviation will be large. In response to this situation, voltage equalization measures need to be taken to control the total output voltage, current or power of the system, and the output powers of the upper and lower busbars.

[0005] For a DC / DC combined converter system with series connection on the high voltage side, parallel connection on the low voltage side, and the midpoint of the high voltage side grounded, when performing voltage balance control of the upper and lower busbars, it is necessary to balance the powers of the DC / DC units corresponding to the upper and lower busbars respectively, that is, voltage equalization on the series side and current sharing on the parallel side. At the same time, the system is also required to be simple and easy to expand and design redundantly in order to improve the reliability of the entire system.

[0006] In existing voltage equalization schemes, a hardware voltage equalization circuit or software control for voltage equalization can be adopted. The hardware voltage equalization circuit is easy to implement when the number of series-parallel converters is small. However, in a medium-high voltage system, an increase in the number of series-parallel converters will inevitably increase the complexity of the system. The existing software voltage equalization control uniformly performs voltage equalization control on the DC / DC units of the entire bus. Therefore, it is only applicable to a system where the high-voltage side is not grounded at the midpoint, but it cannot ensure the voltage balance of the upper and lower buses in a midpoint-grounded system, nor can it ensure the voltage balance of the DC / DC units corresponding to the upper and lower buses respectively.

[0007] In summary, how to achieve voltage balance in a DC / DC combined converter system is a technical problem that urgently needs to be solved at present.

[0008] It should be noted that the information disclosed in the above background art section is only used to enhance the understanding of the background of the present disclosure. Therefore, it may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0009] The purpose of the present disclosure is to provide a DC conversion system and its control method, so as to at least to a certain extent achieve voltage balance in the DC conversion system.

[0010] According to a first aspect of the present invention, there is provided a DC conversion system, including: an input end, an output end; an upper power module group, including an input end, an output end and at least two first power modules, the input ends of the at least two first power modules are connected in series, and the output ends of the at least two first power modules are connected in parallel; a lower power module group, including an input end, an output end and at least two second power modules, the input ends of the at least two second power modules are connected in series, and the output ends of the at least two second power modules are connected in parallel; after the input ends of the upper power module group and the lower power module group are connected in series and then connected to the input end of the DC conversion system, and after the output ends of the upper power module group and the lower power module group are connected in parallel and then connected to the output end of the DC conversion system; a controller, coupled to the upper power module group and the lower power module group, the controller receives and generates a modulation signal according to the input voltage of each of the input ends of the first power modules and the second power modules, the first output current of the output end of the upper power module group, the second output current of the output end of the lower power module group, and a total output signal of the output end of the DC conversion system, so as to control the switches in each of the first power modules and the second power modules to act.

[0011] In some embodiments, the series connection point of the input end of the upper power module group and the input end of the lower power module group is grounded or connected to the voltage midpoint of the input end of the DC conversion system.

[0012] In some embodiments, the number of the first power modules is different from that of the second power modules.

[0013] In some embodiments, the total output signal includes at least one of the following: a total output voltage, a total output current, and a total output power.

[0014] In some embodiments, the controller includes a main controller and a plurality of local controllers. The main controller is coupled to the plurality of local controllers. The main controller is configured to generate a first control signal according to the first output current and the total output signal; generate a second control signal according to the second output current and the total output signal. Each of the plurality of local controllers is coupled to a corresponding one of the first power module and the second power module. Among them, each of the plurality of local controllers coupled to the first power module is configured to: receive the first control signal; receive the corresponding input voltage, and generate a corresponding third control signal according to the corresponding input voltage and a first input reference voltage; generate a corresponding first modulation signal according to the first control signal and the third control signal to control the switches in the corresponding first power module to act. Each of the plurality of local controllers coupled to the second power module is configured to: receive the second control signal; receive the corresponding input voltage, and generate a corresponding fourth control signal according to the corresponding input voltage and a second input reference voltage; generate a corresponding second modulation signal according to the second control signal and the fourth control signal to control the switches in the corresponding second power module to act.

[0015] In some embodiments, the main controller is configured to: generate a fifth control signal according to the total output signal and a total output reference signal; generate a sixth control signal according to the first output current and a first output reference current; and generate the first control signal according to the fifth control signal and the sixth control signal; generate a seventh control signal according to the total output signal and a total output reference signal; generate an eighth control signal according to the second output current and a second output reference current; and generate the second control signal according to the seventh control signal and the eighth control signal.

[0016] In some embodiments, the total output signal is a total output voltage; the main controller is configured to: generate a fifth control signal according to the total output voltage and the total output reference voltage; obtain a first output power according to the total output voltage and the first output current; generate a sixth control signal according to the first output power and the first output reference power; generate the first control signal according to the fifth control signal and the sixth control signal; generate a seventh control signal according to the total output voltage and the total output reference voltage; obtain a second output power according to the total output voltage and the second output current; generate an eighth control signal according to the second output power and the second output reference power; generate the second control signal according to the seventh control signal and the eighth control signal.

[0017] In some embodiments, the total output signal includes a total output voltage and a total output current; the main controller is configured to: generate a fifth control signal according to the total output current and the total output reference current; obtain a first output power according to the total output voltage and the first output current; generate a sixth control signal according to the first output power and the first output reference power; generate the first control signal according to the fifth control signal and the sixth control signal; generate a seventh control signal according to the total output current and the total output reference current; obtain a second output power according to the total output voltage and the second output current; generate an eighth control signal according to the second output power and the second output reference power; generate the second control signal according to the seventh control signal and the eighth control signal.

[0018] In some embodiments, the total output signal includes a total output voltage and a total output power; the main controller is configured to: generate a fifth control signal according to the total output power and the total output reference power; obtain a first output power according to the total output voltage and the first output current; generate a sixth control signal according to the first output power and the first output reference power; generate the first control signal according to the fifth control signal and the sixth control signal; generate a seventh control signal according to the total output power and the total output reference power; obtain a second output power according to the total output voltage and the second output current; generate an eighth control signal according to the second output power and the second output reference power; generate the second control signal according to the seventh control signal and the eighth control signal.

[0019] In some embodiments, the total output signal includes a total output voltage; the main controller is configured to: obtain a total output power according to the total output voltage, the first output current, and the second output current; generate a fifth control signal according to the total output power and the total output reference power; obtain a first output power according to the total output voltage and the first output current; generate a sixth control signal according to the first output power and the first output reference power; generate the first control signal according to the fifth control signal and the sixth control signal; generate a seventh control signal according to the total output power and the total output reference power; obtain a second output power according to the total output voltage and the second output current; generate an eighth control signal according to the second output power and the second output reference power; generate the second control signal according to the seventh control signal and the eighth control signal.

[0020] According to a second aspect of the present invention, a DC conversion system is provided, including: an input end, an output end; an upper power module group, including an input end, an output end, and at least two first power modules, the input ends of the at least two first power modules are connected in series, and the output ends of the at least two first power modules are connected in parallel; a lower power module group, including an input end, an output end, and at least two second power modules, the input ends of the at least two second power modules are connected in series, and the output ends of the at least two second power modules are connected in parallel; after the input end of the upper power module group and the input end of the lower power module group are connected in series, they are connected to the input end of the DC conversion system, and after the output end of the upper power module group and the output end of the lower power module group are connected in parallel, they are connected to the output end of the DC conversion system; a controller, coupled to the upper power module group and the lower power module group, the controller is configured to: receive the input voltage of each of the input ends of the first power module and the second power module; receive at least two of the first output current at the output end of the upper power module group, the second output current at the output end of the lower power module group, and the total output current at the output end of the DC conversion system; generate a modulation signal according to at least two of the first output current, the second output current, and the total output current, and the input voltage, so as to control the switches in each of the first power module and the second power module to act.

[0021] In some embodiments, the series connection point of the input end of the upper power module group and the input end of the lower power module group is grounded or connected to the voltage midpoint of the input end of the DC conversion system.

[0022] In some embodiments, the number of the first power modules is different from the number of the second power modules.

[0023] In some embodiments, the controller includes a main controller and a plurality of local controllers. The main controller is coupled to the plurality of local controllers. The main controller is configured to generate a ninth control signal based on the first output current and the first output reference current; generate a tenth control signal based on the second output current and the second output reference current. Each of the plurality of local controllers is coupled to a corresponding one of the first power module and the second power module. Among them, each of the plurality of local controllers coupled to the first power module is configured to: receive the ninth control signal; receive the corresponding input voltage, and generate a corresponding third control signal based on the corresponding input voltage and the first input reference voltage; generate a corresponding first modulation signal based on the ninth control signal and the third control signal to control the switches in the corresponding first power module to operate. Each of the plurality of local controllers coupled to the second power module is configured to: receive the tenth control signal; receive the corresponding input voltage, and generate a corresponding fourth control signal based on the corresponding input voltage and the second input reference voltage; generate a corresponding second modulation signal based on the tenth control signal and the fourth control signal to control the switches in the corresponding second power module to operate.

[0024] In some embodiments, the controller includes a main controller and a plurality of local controllers. The main controller is coupled to the plurality of local controllers. The main controller is configured to generate a ninth control signal based on the first output current and the first output reference current; generate a tenth control signal based on the total output current and the total output reference current. Each of the plurality of local controllers is coupled to a corresponding one of the first power module and the second power module. Among them, each of the plurality of local controllers coupled to the first power module is configured to: receive the ninth control signal; receive the corresponding input voltage, and generate a corresponding third control signal based on the corresponding input voltage and the first input reference voltage; generate a corresponding first modulation signal based on the ninth control signal and the third control signal to control the switches in the corresponding first power module to operate. Each of the plurality of local controllers coupled to the second power module is configured to: receive the tenth control signal; receive the corresponding input voltage, and generate a corresponding fourth control signal based on the corresponding input voltage and the second input reference voltage; generate a corresponding second modulation signal based on the tenth control signal and the fourth control signal to control the switches in the corresponding second power module to operate.

[0025] In some embodiments, the controller includes a main controller and multiple local controllers. The main controller is coupled to the multiple local controllers. The main controller is configured to generate a ninth control signal based on the total output current and the total output reference current; generate a tenth control signal based on the second output current and the second output reference current. Each of the multiple local controllers is coupled to a corresponding one of the first power module and the second power module. Among them, each of the multiple local controllers coupled to the first power module is configured to: receive the ninth control signal; receive the corresponding input voltage, and generate a corresponding third control signal based on the corresponding input voltage and the first input reference voltage; generate a corresponding first modulation signal based on the ninth control signal and the third control signal, for controlling the switches in the corresponding first power module to act. Each of the multiple local controllers coupled to the second power module is configured to: receive the tenth control signal; receive the corresponding input voltage, and generate a corresponding fourth control signal based on the corresponding input voltage and the second input reference voltage; generate a corresponding second modulation signal based on the tenth control signal and the fourth control signal, for controlling the switches in the corresponding second power module to act.

[0026] In some embodiments, the controller includes a main controller and multiple local controllers. The main controller is coupled to the multiple local controllers. The main controller is further configured to receive the total output voltage at the output end of the DC conversion system, and generate a ninth control signal and a tenth control signal based on at least two of the first output current, the second output current, and the total output current, and the total output voltage. Each of the multiple local controllers is coupled to a corresponding one of the first power module and the second power module. Among them, each of the multiple local controllers coupled to the first power module is configured to: receive the ninth control signal; receive the corresponding input voltage, and generate a corresponding third control signal based on the corresponding input voltage and the first input reference voltage; generate a corresponding first modulation signal based on the ninth control signal and the third control signal, for controlling the switches in the corresponding first power module to act. Each of the multiple local controllers coupled to the second power module is configured to: receive the tenth control signal; receive the corresponding input voltage, and generate a corresponding fourth control signal based on the corresponding input voltage and the second input reference voltage; generate a corresponding second modulation signal based on the tenth control signal and the fourth control signal, for controlling the switches in the corresponding second power module to act.

[0027] According to a third aspect of the present invention, there is provided a control method for a DC conversion system. The DC conversion system includes at least two first power modules, at least two second power modules, and a controller. The input ends of the at least two first power modules are connected in series to form an upper power module group, and the input ends of the at least two second power modules are connected in series to form a lower power module group. The output ends of each of the first power modules and each of the second power modules are connected in parallel. The controller is coupled to each of the first power modules and the second power modules. The control method includes: obtaining the input voltage of each of the first power modules and the second power modules; obtaining a first output current of the upper power module group, a second output current of the lower power module group, and a total output signal at the output end of the DC conversion system; generating a modulation signal based on the input voltage, the first output current, the second output current, and the total output signal; and controlling the switches in each of the first power modules and the second power modules to act according to the modulation signal.

[0028] In some embodiments, the total output signal includes at least one of the following: a total output voltage, a total output current, and a total output power.

[0029] In some embodiments, the step of generating a modulation signal based on the input voltage, the first output current, the second output current, and the total output signal includes: generating a fifth control signal based on the total output signal and a total output reference signal; generating a sixth control signal based on the first output current and a first output reference current; generating a corresponding third control signal based on the input voltage corresponding to each of the first power modules and a first input reference voltage; generating a corresponding first modulation signal based on the fifth control signal, the sixth control signal, and the third control signal; controlling the switches in the corresponding first power modules to act according to the first modulation signal; and generating a seventh control signal based on the total output signal and a total output reference signal; generating an eighth control signal based on the second output current and a second output reference current; generating a corresponding fourth control signal based on the input voltage corresponding to each of the second power modules and a second input reference voltage; generating a corresponding second modulation signal based on the seventh control signal, the eighth control signal, and the fourth control signal; and controlling the switches in the corresponding second power modules to act according to the second modulation signal.

[0030] In some embodiments, the total output signal is a total output voltage; the steps of generating a modulation signal according to the input voltage, the first output current, the second output current, and the total output signal include: generating a fifth control signal according to the total output voltage and the total output reference voltage; obtaining a first output power according to the total output voltage and the first output current; generating a sixth control signal according to the first output power and the first output reference power; generating a corresponding third control signal according to the input voltage and the first input reference voltage corresponding to each of the first power modules; generating a corresponding first modulation signal according to the fifth control signal, the sixth control signal, and the third control signal; controlling the switches in the corresponding first power modules to act according to the first modulation signal; and generating a seventh control signal according to the total output voltage and the total output reference voltage; obtaining a second output power according to the total output voltage and the second output current; generating an eighth control signal according to the second output power and the second output reference power; generating a corresponding fourth control signal according to the input voltage and the second input reference voltage corresponding to each of the second power modules; generating a corresponding second modulation signal according to the seventh control signal, the eighth control signal, and the fourth control signal; controlling the switches in the corresponding second power modules to act according to the second modulation signal.

[0031] In some embodiments, the total output signal includes a total output voltage and a total output current; the steps of generating a modulation signal according to the input voltage, the first output current, the second output current, and the total output signal include: generating a fifth control signal according to the total output current and the total output reference current; obtaining a first output power according to the total output voltage and the first output current; generating a sixth control signal according to the first output power and the first output reference power; generating a corresponding third control signal according to the input voltage and the first input reference voltage corresponding to each of the first power modules; generating a corresponding first modulation signal according to the fifth control signal, the sixth control signal, and the third control signal; controlling the switches in the corresponding first power modules to act according to the first modulation signal; and generating a seventh control signal according to the total output current and the total output reference current; obtaining a second output power according to the total output voltage and the second output current; generating an eighth control signal according to the second output power and the second output reference power; generating a corresponding fourth control signal according to the input voltage and the second input reference voltage corresponding to each of the second power modules; generating a corresponding second modulation signal according to the seventh control signal, the eighth control signal, and the fourth control signal; controlling the switches in the corresponding second power modules to act according to the second modulation signal.

[0032] In some embodiments, the total output signal includes a total output voltage and a total output power; the step of generating a modulation signal based on the input voltage, the first output current, the second output current, and the total output signal includes: generating a fifth control signal based on the total output power and the total output reference power; obtaining a first output power based on the total output voltage and the first output current; generating a sixth control signal based on the first output power and the first output reference power; generating a corresponding third control signal based on the input voltage corresponding to each first power module and the first input reference voltage; generating a corresponding first modulation signal based on the fifth control signal, the sixth control signal, and the third control signal; controlling the switch in the corresponding first power module to act according to the first modulation signal; and generating a seventh control signal based on the total output power and the total output reference power; obtaining a second output power based on the total output voltage and the second output current; generating an eighth control signal based on the second output power and the second output reference power; generating a corresponding fourth control signal based on the input voltage corresponding to each second power module and the second input reference voltage; generating a corresponding second modulation signal based on the seventh control signal, the eighth control signal, and the fourth control signal; controlling the switch in the corresponding second power module to act according to the second modulation signal.

[0033] In some embodiments, the total output signal is a total output voltage; the step of generating a modulation signal based on the input voltage, the first output current, the second output current, and the total output signal includes: obtaining a total output power based on the total output voltage, the first output current, and the second output current; generating a fifth control signal based on the total output power and the total output reference power; obtaining a first output power based on the total output voltage and the first output current; generating a sixth control signal based on the first output power and the first output reference power; generating a corresponding third control signal based on the input voltage corresponding to each first power module and the first input reference voltage; generating a corresponding first modulation signal based on the fifth control signal, the sixth control signal, and the third control signal; controlling the switch in the corresponding first power module to act according to the first modulation signal; and generating a seventh control signal based on the total output power and the total output reference power; obtaining a second output power based on the total output voltage and the second output current; generating an eighth control signal based on the second output power and the second output reference power; generating a corresponding fourth control signal based on the input voltage corresponding to each second power module and the second input reference voltage; generating a corresponding second modulation signal based on the seventh control signal, the eighth control signal, and the fourth control signal; controlling the switch in the corresponding second power module to act according to the second modulation signal.

[0034] In some embodiments, the first input reference voltage and the second input reference voltage are not equal.

[0035] In some embodiments, when the difference between the corresponding input voltage and the corresponding input reference voltage is greater than a first threshold or less than a second threshold, a voltage equalization control unit adjusts the third control signal or the fourth control signal; when the difference is less than or equal to the first threshold and greater than or equal to the second threshold, the voltage equalization control unit maintains the corresponding third control signal or fourth control signal.

[0036] In some embodiments, the first threshold is greater than or equal to the second threshold.

[0037] In the DC conversion system and its control method according to the embodiments of the present invention, the input ends of the upper power module group and the lower power module group are connected in series, and the output ends are connected in parallel. The controller controls the switch to act according to the input voltage at the input end of each power module and the output current at the output ends of the upper and lower power module groups, so as to achieve voltage equalization of the input voltage of each power module and current equalization of the output current.

[0038] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings herein are incorporated into the specification and form a part of the specification, showing embodiments consistent with the present disclosure, and are used together with the specification to explain the principles of the present disclosure. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts.

[0040] Figure 1 Schematically showing a circuit structure diagram of a DC conversion system according to an embodiment of the present invention;

[0041] Figure 2 Schematically showing a control structure diagram of a DC conversion system according to an embodiment of the present invention;

[0042] Figure 3 Schematically showing a schematic diagram of the connection relationship of a controller according to an embodiment of the present invention;

[0043] Figure 4 Schematically showing a structural diagram of a power module according to an embodiment of the present invention;

[0044] Figure 5a Schematically showing a schematic diagram of the signal processing process of an upper power module group according to an embodiment of the present invention;

[0045] Figure 5b Schematic diagram showing the signal processing process of the lower power module group according to an embodiment of the present invention;

[0046] Figure 6 Schematic diagram showing the signal processing process of the DC conversion system according to another embodiment of the present invention;

[0047] Figure 7 Schematic diagram showing the control structure of the DC conversion system according to another embodiment of the present invention;

[0048] Figure 8 Schematic diagram showing the signal processing process of the DC conversion system according to still another embodiment of the present invention;

[0049] Figure 9 Schematic diagram showing the signal processing process of the DC conversion system according to still another embodiment of the present invention;

[0050] Figure 10 Schematic diagram showing the signal processing process of the DC conversion system according to still another embodiment of the present invention;

[0051] Figure 11 Schematic diagram showing the signal processing process of the DC conversion system according to still another embodiment of the present invention;

[0052] Figure 12 Schematic diagram showing the parallel connection of the DC conversion system according to an embodiment of the present invention;

[0053] Figure 13 Schematic diagram showing the voltage equalization control effect according to an embodiment of the present invention;

[0054] Figure 14 Flowchart showing the control method of the DC conversion system according to an embodiment of the present invention;

[0055] Figure 15 Flowchart showing the steps of generating a modulation signal according to an embodiment of the present invention. Detailed implementation manners

[0056] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this invention will be more complete and comprehensive, and will fully convey the concept of the example embodiments to those skilled in the art.

[0057] In addition, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of the embodiments of the present invention. However, those skilled in the art will realize that the technical solutions of the present invention may be practiced without one or more of the specific details, or other methods, components, devices, steps, etc. may be adopted. In other cases, well-known methods, devices, implementations, or operations are not shown or described in detail to avoid obscuring aspects of the present invention.

[0058] The block diagrams shown in the drawings are only functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities may be implemented in software form, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and / or processor devices and / or microcontroller devices.

[0059] The flowcharts shown in the drawings are only illustrative and do not necessarily include all the contents and operations / steps, nor are they necessarily executed in the described order. For example, some operations / steps may be decomposed, while some operations / steps may be combined or partially combined, so the actual execution order may be changed according to the actual situation.

[0060] In the related art, in a high-voltage side series and low-voltage side parallel DC / DC combined converter system, the occurrence of voltage imbalance will affect the selection of switching tubes and thermal design, etc., reducing the system performance and reliability. To ensure the stable operation of the converter system, it is necessary to ensure the voltage balance on the series side and the current balance on the parallel side of each DC / DC unit.

[0061] Embodiments of the present invention provide a DC conversion system and its control method to achieve voltage balance of the DC conversion system.

[0062] Embodiments of the present invention provide a DC conversion system, including: an input end, an output end; an upper power module group, including an input end, an output end, and at least two first power modules. As Figure 1 shown, the first power module 211, the first power module 212, and the first power module 213 constitute the upper power module group, where the input ends of each first power module are connected in series, and the output ends are connected in parallel; a lower power module group, including an input end, an output end, and at least two second power modules. As Figure 1As shown, the second power modules 221, 222, and 223 form a lower power module group. Among them, the input ends of each second power module are connected in series, and the output ends are connected in parallel. After the input ends of the upper power module group and the lower power module group are connected in series, they are respectively connected to the input ends P and N of the DC conversion system. After the output ends of the upper power module group and the lower power module group are connected in parallel, they are connected to the output end of the DC conversion system. A controller (not shown in the figure) is coupled to the upper power module group and the lower power module group. The controller receives and generates a modulation signal based on the input voltage of each input end of the first power module and the second power module, the first output current Io_up of the output end of the upper power module group, the second output current Io_dn of the output end of the lower power module group, and a total output signal of the output end of the DC conversion system, so as to control the switches in each first power module and second power module to act. Among them, the total output signal can be one, two, or three of the total output voltage Vout, the total output current Io, and the total output power Po.

[0063] In the embodiment of the present invention, by sampling the input voltage of each power module, the output currents of the upper and lower power module groups respectively, and the total output signal of the DC conversion system, and performing closed-loop control according to the sampling results, the balance control of each power module can be accurately performed.

[0064] Here and hereinafter, the power module includes the first power module and the second power module.

[0065] As Figure 2 shown, in the embodiment of the present invention, the input voltages of the input ends of the first power module and the second power module are the voltages of the capacitors Cin1_1, Cin1_2,..., Cin1_m respectively connected in parallel with each first power module, and the voltages of the capacitors Cin2_1, Cin2_2,..., Cin2_n respectively connected in parallel with each second power module.

[0066] In the embodiment of the present invention, the series connection point of the upper power module group and the lower power module group is grounded or connected to the voltage midpoint O of the input end of the DC conversion system. By grounding the midpoint of the power modules connected in series on the high-voltage side with a low resistance, the voltages of the upper and lower busbars of the high-voltage side of the DC conversion system with respect to the ground are reduced to half of the entire busbar voltage, and the common-mode voltage of each power module with respect to the ground can be reduced. Since the technical solution of the embodiment of the present invention is to sample the input voltage of each power module and the output currents of the upper and lower power module groups respectively, and perform closed-loop control according to the sampling results, the balance control of each power module can be accurately performed, without being limited by whether the connection point of the upper power module group and the lower power module group is grounded or connected to the voltage midpoint of the input end of the DC conversion system, and the problem of serious unequal power distribution between the upper and lower power module groups can be avoided.

[0067] Among them, in the embodiments given in the present invention, they are all based on the high voltage side being the input and the low voltage side being the output, that is, on the basis of Input-Series-Output-Parallel (ISOP). However, the technical solution of the present invention is not limited to this, and it is equally applicable to a DC conversion system where the high voltage side is the output and the low voltage side is the input, that is, input parallel output series. As Figure 2 The circuit structure shown is the circuit structure of a DC conversion system with the high voltage side in series and the low voltage side in parallel.

[0068] In the embodiments of the present invention, the number of the first power modules and the second power modules may be the same or different. As Figure 2 shown, the upper power module group includes m first power modules, and the lower power module group includes n second power modules, where both m and n are natural numbers greater than or equal to 2. Among them, m may be equal to n or not equal to n. When the number of the first power modules and the second power modules is different, since the technical solution of the embodiments of the present invention samples the input voltage of each power module and performs closed-loop control according to the sampling result, the balance control of each power module can be accurately performed, without being limited by the number of the first power modules and the second power modules.

[0069] As Figure 2 shown, the output terminals of the m first power modules in the upper power module group are connected in parallel and respectively connected to the positive and negative poles of the output terminal of the DC conversion system; the output terminals of the n second power modules in the lower power module group are connected in parallel and respectively connected to the positive and negative poles of the output terminal of the DC conversion system; it should be noted that the output capacitor (not shown in the figure) may be a capacitor connected in parallel to the output terminal of the DC conversion system, or a capacitor may be connected in parallel to the output terminal of each power module, and the form is not limited.

[0070] As Figure 2As shown, the controller includes a main controller 310 and multiple local controllers. Each of the multiple local controllers is coupled to a corresponding one of the first power module and the second power module. In this embodiment, local controller 331 is coupled to first power module 311, local controller 332 is coupled to first power module 312, local controller 341 is coupled to second power module 321, and local controller 342 is coupled to second power module 322. The main controller 310 is coupled to the multiple local controllers. The main controller is configured to generate a first control signal c1 based on the first output current Io_up and the total output signal; generate a second control signal c2 based on the second output current Io_dn and the total output signal. Among them, multiple local controllers coupled to the first power module, such as local controller 331 and local controller 332, are each configured to: receive the first control signal c1; receive the input voltage of the corresponding first power module, and generate a corresponding third control signal c3 based on the corresponding input voltage and the first input reference voltage; generate a corresponding first modulation signal based on the first control signal c1 and the third control signal c3 to control the switches in the corresponding first power module to act. Multiple local controllers 341 and 342 coupled to the second power module are each configured to: receive the second control signal c2; receive the input voltage of the corresponding second power module, and generate a corresponding fourth control signal c4 based on the corresponding input voltage and the second input reference voltage; generate a corresponding second modulation signal based on the second control signal c2 and the fourth control signal c4 to control the switches in the corresponding second power module to act.

[0071] It should be noted that the local controller can be integrated with the corresponding power module or can be separately and independently arranged from the corresponding power module, and its specific form is not limited.

[0072] In this embodiment, the manner in which the main controller and the local controllers are coupled is not limited. It can be a direct connection or a communication connection through optical fiber or wireless means, etc. The present invention is not limited thereto.

[0073] In addition, the DC conversion system may further include multiple input voltage sampling circuits, an output sampling circuit, and output current sampling circuits for the upper and lower power module groups. Each input voltage sampling circuit is used to collect the capacitor voltage at the input end of a corresponding power module. The output sampling circuit is used to collect one or more of the total output voltage, total output current, or total output power at the output end of the DC conversion system. The output current sampling circuits for the upper and lower power module groups respectively sample the total current after the outputs of the m first power modules corresponding to the upper power module group are connected in parallel, that is, the first output current Io_up, and the total current after the outputs of the n second power modules corresponding to the lower power module group are connected in parallel, that is, the second output current Io_dn.

[0074] Such asFigure 3 As shown, the local controllers corresponding to the m first power modules and the n second power modules upload the sampled input voltages Vin1_k and Vin2_k to the main controller. The main controller calculates the first input reference voltage Vin_up_ref_k and the second input reference voltage Vin_dn_ref_k based on these input voltages and in combination with different application scenarios, and then sends them to the corresponding local controllers. Here and hereinafter, k is a natural number, representing the k-th first power module or the k-th second power module. In addition, the input reference voltages can also be calculated according to the voltage value at the input end of the DC conversion system. It should be noted that the input reference voltages corresponding to the m + n power modules can be the same or different.

[0075] As Figure 2 and Figure 3 shown, the local controller generates the corresponding first modulation signal Driver_up_k and the second modulation signal Driver_dn_k to control the switches in the corresponding first power module and second power module to act respectively.

[0076] In this embodiment, the first power module and the second power module can be a series-parallel combination of one or more DC / DC converters. As Figure 4 shown, the first power module or the second power module can be a combined structure of two or more LLC resonant converters. In this embodiment, the input ends of the two LLC resonant converters are connected in series and the output ends are connected in parallel; in other embodiments, the two LLC resonant converters can also be connected in parallel at the input ends, connected in parallel at the output ends or other connection methods, and the present invention is not limited thereto.

[0077] Please refer to Figure 5a and Figure 5b As Figure 5aAs shown, for the control of the upper power module group, the main controller receives the total output signal of the DC conversion system. At the same time, the main controller can generate a total output reference signal, and then generate a fifth control signal c5 based on the total output signal and the total output reference signal. Specifically, by subtracting the total output reference signal from the total output signal, a total output deviation signal is obtained. This total output deviation signal passes through a total output control unit to generate the fifth control signal c5. It should be noted that the total output signal can be the total output voltage Vo, the total output current Io, or the total output power Po, and the corresponding total output reference signals are the total output reference voltage Vo_ref, the total output reference current Io_ref, or the total output reference power Po_ref respectively. Among them, the total output current Io can be obtained by calculating the first output current Io_up and the second output current Io_dn, or can be directly obtained by sampling; the total output power Po can be obtained by calculating the total output voltage Vo and the total output current Io, or can be directly obtained by sampling. This patent is not limited thereto.

[0078] In this embodiment, the main controller is also used to receive the first output current Io_up. At the same time, the main controller can generate a first output reference current Io_up_ref, and then generate a sixth control signal c6 based on the first output current Io_up and the first output reference current Io_up_ref. Specifically, by subtracting the first output current Io_up from the first output reference current Io_up_ref, a first output current deviation is obtained. This first output current deviation passes through the upper output control unit to generate the sixth control signal c6. It should be noted that the first output current Io_up and the first output reference current Io_up_ref can also be replaced by the first output power Po_up and the first output reference power Po_up_ref. Among them, the first output power Po_up can be obtained by calculating the first output current Io_up and the total output voltage Vo, or can be directly obtained by sampling.

[0079] The main controller further generates a first control signal c1 based on the fifth control signal c5 and the sixth control signal c6, and distributes the first control signal c1 to the local controllers corresponding to each first power module respectively.

[0080] Each local controller is respectively used to receive the input voltage Vin1_k of the corresponding first power module, and obtain the third control signal c3 according to the input voltage Vin1_k and the corresponding first input reference voltage Vin_up_ref_k. Specifically, the difference between the input voltage Vin1_k and the first input reference voltage Vin_up_ref_k is input to the corresponding voltage sharing control unit, and the voltage sharing control unit outputs the third control signal c3. Finally, the local controller generates a first modulation signal according to the third control signal c3 and the first control signal c1, which is used to control the switches in the corresponding first power module to act.

[0081] Similarly, as Figure 5b shown, for the control of the lower power module group, it is basically the same as the control method of the upper power module group. The main controller receives the total output signal of the DC conversion system. At the same time, the main controller can generate a total output reference signal, and then generate the seventh control signal c7 according to the total output signal and the total output reference signal. It should be noted that the total output signal can be the total output voltage Vo, the total output current Io or the total output power Po, and the corresponding total output reference signals are the total output reference voltage Vo_ref, the total output reference current Io_ref or the total output reference power Po_ref respectively. Among them, the total output current Io can be obtained by operating the first output current Io_up and the second output current Io_dn, or can be directly obtained by sampling; the total output power Po can be obtained by operating the total output voltage Vo and the total output current Io, or can be directly obtained by sampling. This patent is not limited thereto.

[0082] It should be noted that the fifth control signal c5 and the seventh control signal c7 can be the same signal or different signals. Among them, when the same total output control unit is used in the upper power module group and the lower power module group, the fifth control signal c5 and the seventh control unit c7 are the same signal; when the upper power module group and the lower power module group are controlled according to different total output signals, that is, different total output control units are used, the fifth control signal c5 and the seventh control signal c7 are different signals.

[0083] The main controller is also used to receive the second output current Io_dn. Meanwhile, the main controller can generate a second output reference current Io_dn_ref, and then generate an eighth control signal c8 based on the second output current Io_dn and the second output reference current Io_dn_ref. It should be noted that the second output current Io_dn and the second output reference current Io_dn_ref can also be replaced by a second output power Po_dn and a second output reference power Po_dn_ref. Among them, the second output power Po_dn can be obtained through the operation of the second output current Io_dn and the total output voltage Vo, or can be directly obtained through sampling.

[0084] The main controller further generates a second control signal c2 based on the seventh control signal c7 and the eighth control signal c8, and distributes the second control signal c2 to the local controllers corresponding to each second power module respectively. Each local controller is used to receive the input voltage Vin2_k of the corresponding second power module, and obtain a fourth control signal c4 based on the input voltage Vin2_k and the corresponding second input reference voltage Vin_dn_ref_k. Finally, the local controller generates a second modulation signal based on the fourth control signal c4 and the second control signal c2 to control the switches in the corresponding second power module to act.

[0085] Among them, the above first to eighth control signals (i.e., c1 - c8) can be frequency signals, duty cycle signals or other forms of signals, which are not limited in the present invention.

[0086] Among them, the first output reference power Po_up_ref, the second output reference power Po_dn_ref, the first output reference current Io_up_ref, and the second output reference current Io_dn_ref can all be determined according to the output capabilities or requirements of the upper and lower power module groups. They can each be 1 / 2 of the total output power or total output current of the DC conversion system, or can be calculated according to the output power or output current that each actual power module needs to bear.

[0087] In the embodiments of the present invention, there can be various distribution methods for the signal processing processes completed by the main controller and the local controller respectively, such as Figure 5a and Figure 5b In the embodiments shown, the total output control, the upper output control, and the lower output control are all completed in the main controller, and the main controller distributes the generated first control signal c1 and second control signal c2 to the corresponding local controllers. In other embodiments, at least one of the total output control, the upper output control, and the lower output control can also be completed by the local controller, such as Figure 6As shown, the main controller can calculate the total output deviation signals (such as Vo_error, Io_error, Po_error) based on the total output signals (such as Vo, Io, Po) and the total output reference signals (such as Vo_ref, Io_ref, Po_ref), and send the total output deviation signals to each local controller; at the same time, the main controller calculates the first output current deviation Io_up_error (or the first output power deviation Po_up_error) based on the first output current Io_up (or the first output power Po_up) and the first output reference current Io_up_ref (or the first output reference power Po_up_ref), and calculates the second output current deviation Io_dn_error (or the second output power deviation Po_dn_error) based on the second output current Io_dn (or the second output power Po_dn) and the second output reference current Io_dn_ref (or the second output reference power Po_dn_ref), and then sends the first output current deviation Io_up_error and the second output current deviation Io_dn_error to the local controller corresponding to the first power module and the local controller corresponding to the second power module respectively. Finally, the corresponding local controller completes the total output control, the upper output control, the lower output control, and the equalizing control, and generates the corresponding modulation signals to control the switches in the first power module or the second power module to act.

[0088] Further, in some other embodiments, the main controller can also be omitted, and only the local controller is used to complete the above control functions, such as Figure 7 In the DC conversion system shown, m + n local controllers 1020 corresponding to m + n power modules 1010 are connected through a competitive master-slave communication bus (Communication Bus). This solution can reduce the number of controllers and improve the system reliability. When the system runs, one local controller needs to be selected from the m + n local controllers as the host to complete the main control function, and the other local controllers are used as slaves. The host can be freely switched according to the actual situation, which has good redundancy.

[0089] Figures 8 to 10 respectively are Figure 7 Specific embodiments of the competitive master-slave control scheme shown, such as Figure 8As shown in the figure, assume that one of the local controllers in the upper power module group competes to become the host. The host receives the total output voltage Vo, and based on the total output voltage Vo and the total output reference voltage Vo_ref, obtains the total output voltage control signal Vo_Ctrl and issues it to each slave (i.e., other local controllers). The host also has an input reference voltage generation module (Vin_ref Generator) and an output reference current generation module (Io_ref Generator). Among them, the input reference voltage generation module respectively generates the first input reference voltage Vin_up_ref_k and the second input reference voltage Vin_dn_ref_k based on the input voltages of each power module and the power module operating state information obtained, and sends them to the corresponding slaves in the upper and lower power module groups respectively. Each slave obtains the voltage equalization control signal Vin1_Ctrl_k or Vin2_Ctrl_k based on the input reference voltage Vin_up_ref_k or Vin_dn_ref_k and its own actual input voltage Vin1_k or Vin2_k.

[0090] The output reference current generation module generates the first output reference current Io_up_ref_k corresponding to the first power module and the second output reference current Io_dn_ref_k corresponding to the second power module based on the output currents of the upper and lower power module groups and the module operating state information obtained, and sends them to the corresponding slaves in the upper and lower power module groups respectively. Each slave obtains the output current control signal Io1_Ctrl_k or Io2_Ctrl_k based on the first output reference current Io_up_ref_k or the second output reference current Io_dn_ref_k and the actual output current Io1_k or Io2_k, and based on the obtained voltage equalization control signal Vin1_Ctrl_k (or Vin2_Ctrl_k), output current control signal Io1_Ctrl_k (or Io2_Ctrl_k), and total output voltage control signal Vo_Ctrl, finally generates the first modulation signal (or the second modulation signal) to control the switches in the corresponding first power module (or second power module) to act.

[0091] In this master-slave scheme, the host is not limited to its location. It may be the local controller corresponding to a certain first power module in the upper power module group or the local controller corresponding to a certain second power module in the lower power module group. Once the host fails, the master-slave competition mechanism is activated, and a new local controller takes over the host's position and undertakes the host's work. In addition, the input reference voltage and the output reference current may be the same or may not be completely the same.

[0092] As Figure 9 shown, the host can issue the total output voltage Vo sampled by it to each slave, as Figure 10As shown, the total output voltage deviation Vo_error obtained from the total output voltage and the total output reference voltage can also be sent to each slave device. Each slave device independently performs total output voltage control to obtain a total output voltage control signal Vo_Ctrl, and then combines the voltage sharing control signal Vin1_Ctrl_k (or Vin2_Ctrl_k) and the output current control signal Io1_Ctrl_k (or Io2_Ctrl_k) obtained by each local controller to obtain a first modulation signal (or a second modulation signal).

[0093] In a DC conversion system provided by another embodiment of the present invention, the circuit structure is similar to that of the DC conversion system in the embodiment as Figure 1 shown. The difference is that, as Figure 11 shown, the controller in the embodiment of the present invention is configured to: receive the input voltage at the input end of each first power module and second power module; receive at least two of the first output current at the output end of the upper power module group, the second output current at the output end of the lower power module group, and the total output current at the output end of the DC conversion system; generate a modulation signal according to at least two of the first output current, the second output current, and the total output current, and the input voltage, so as to control the switches in each first power module and second power module to act.

[0094] In the embodiment of the present invention, the series connection point of the input ends of the upper power module group and the lower power module group is grounded or connected to the voltage midpoint of the input end of the DC conversion system. Wherein, the number of the first power modules and the second power modules may be the same or different.

[0095] In the embodiment of the present invention, according to different sampling signals, the main controller may adopt different control strategies. Specifically, as Figure 11 shown, the processes of generating the ninth control signal and the tenth control signal are different.

[0096] As Figure 11In the illustrated embodiment, the controller receives and generates corresponding modulation signals based on the first output current Io_up, the second output current Io_dn, and the input voltages Vin1_k or Vin2_k of each power module. Specifically, the controller includes a main controller and a plurality of local controllers. The main controller is coupled to the plurality of local controllers. The main controller is configured to generate a ninth control signal c9 according to the first output current Io_up and the first output reference current Io_up_ref; generate a tenth control signal c10 according to the second output current Io_dn and the second output reference current Io_dn_ref; Each of the plurality of local controllers is coupled to a corresponding one of the first power module and the second power module. Among them, each of the plurality of local controllers coupled to the first power module is configured to: receive the ninth control signal c9; receive the corresponding input voltage Vin1_k, and generate a corresponding third control signal c3 according to the corresponding input voltage Vin1_k and the first input reference voltage Vin_up_ref_k; generate a corresponding first modulation signal according to the ninth control signal c9 and the third control signal c3 to control the switches in the corresponding first power module to act. Each of the plurality of local controllers coupled to the second power module is configured to: receive the tenth control signal c10; receive the corresponding input voltage Vin2_k, and generate a corresponding fourth control signal c4 according to the corresponding input voltage Vin2_k and the second input reference voltage Vin_dn_ref_k; generate a corresponding second modulation signal according to the tenth control signal c10 and the fourth control signal c4 to control the switches in the corresponding second power module to act.

[0097] It should be noted that in other embodiments, the main controller may also generate the ninth control signal c9 according to the first output current Io_up and the first output reference current Io_up_ref, and generate the tenth control signal c10 according to the total output current Io and the total output reference current Io_ref; the main controller may also generate the ninth control signal c9 according to the total output current Io and the total output reference current Io_ref, and generate the tenth control signal c10 according to the second output current Io_dn and the second output reference current Io_dn_ref. Furthermore, the ninth control signal c9 is sent to each local controller corresponding to the first power module; the tenth control signal c10 is sent to each local controller corresponding to the second power module.

[0098] In the embodiments of the present invention, the process of generating the ninth control signal c9 and the tenth control signal c10 can also be completed in each local controller, and the master controller is only used to generate each reference signal (i.e., the first output reference current, the second output reference current, the total output reference current, the first input reference voltage, the second input reference voltage, etc.), and then send it to the local controller corresponding to each power module; or, the master controller is only used to calculate the first output current deviation, the second output current deviation, or the total output current deviation, etc., and then send it to the corresponding local controller. In short, the functions completed by the master controller and the local controller can be arbitrarily allocated, and the present invention does not limit this.

[0099] Moreover, in some other embodiments, the master controller can be cancelled. The local controllers in the upper and lower power module groups respectively determine one of the local controllers as the master and the other local controllers as the slaves through the master-slave competition mechanism. The generation of the ninth control signal c9 and the tenth control signal c10 is respectively completed by the corresponding master. Then, the master in the power module group sends the ninth control signal c9 or the tenth control signal c10 to each slave in the same power module group, and then generates the corresponding first modulation signal and second modulation signal.

[0100] In an embodiment of the present invention, the second control strategy is to generate a modulation signal based on at least two of the first output current, the second output current, and the total output current, as well as the total output voltage and the input voltage of each power module. Specifically, taking the sampled currents as the first output current Io_up and the second output current Io_dn as an example, the controller includes a main controller and multiple local controllers. The main controller is coupled to the multiple local controllers. The main controller is configured to calculate the first output power Po_up based on the first output current Io_up and the total output voltage Vo, and generate a ninth control signal c9 based on the first output power Po_up and the first output reference power Po_up_ref. At the same time, calculate the second output power Po_dn based on the second output current Io_dn and the total output voltage Vo, and generate a tenth control signal c10 based on the second output power Po_dn and the second output reference power Po_dn_ref. The multiple local controllers are respectively coupled to one of the first power module and the second power module. Among them, the multiple local controllers coupled to the first power module are each configured to: receive the ninth control signal c9; receive the corresponding input voltage Vin1_k, and generate a corresponding third control signal c3 based on the corresponding input voltage Vin1_k and the first input reference voltage Vin_up_ref_k; generate a corresponding first modulation signal based on the ninth control signal c9 and the third control signal c3 to control the switches in the corresponding first power module to act. The multiple local controllers coupled to the second power module are each configured to: receive the tenth control signal c10; receive the corresponding input voltage Vin2_k, and generate a corresponding fourth control signal c4 based on the corresponding input voltage Vin2_k and the second input reference voltage Vin_dn_ref_k; generate a corresponding second modulation signal based on the tenth control signal c10 and the fourth control signal c4 to control the switches in the corresponding second power module to act.

[0101] As Figure 12 shown, when the output ends of three ISOP DC conversion systems are connected in parallel to jointly bear the same load 910, if the second power module 930 corresponding to one of the DC conversion systems fails and must be completely removed, it is not necessary to remove the first power module 920 in the power module group of this DC conversion system together. Instead, within the power and current range that the power module can withstand, readjust the power or current distribution of the power modules in other online DC conversion systems to ensure that although the output power or current of each power module in the upper and lower power module groups is inconsistent, the voltage at its input end is still balanced.

[0102] As Figure 13As shown, in this embodiment, the input voltage of the first power module is Vin1, and the input voltage of the second power module is Vin2. The corresponding input reference voltages are both Vin_ref. During the voltage equalization control, a voltage equalization threshold value (i.e., the first threshold and the second threshold) is added as needed. When Vin_ref - Vin1 is greater than the first threshold or less than the second threshold, the corresponding voltage equalization loop takes effect; conversely, when Vin_ref - Vin1 is between the first threshold and the second threshold, the voltage equalization loop does not take effect. Similarly, the method for adding the voltage equalization threshold value for the input voltage Vin2 of the second power module is the same. Among them, the first threshold is greater than or equal to the second threshold.

[0103] As Figure 14 shown, an embodiment of the present invention provides a control method for a DC conversion system. The DC conversion system includes at least two first power modules, at least two second power modules, and a controller. The input ends of the at least two first power modules are connected in series and the output ends are connected in parallel to form an upper power module group. The input ends of the at least two second power modules are connected in series and the output ends are connected in parallel to form a lower power module group. The controller is respectively connected to each first power module and second power module. The control method includes:

[0104] Step S1310, obtaining the respective input voltages of the first power module and the second power module, the first output current of the upper power module group, the second output current of the lower power module group, and a total output signal at the system output end.

[0105] Step S1320, generating a modulation signal according to the respective input voltages, the first output current, the second output current, and the total output signal of the first power module and the second power module, and controlling the switches in each first power module and second power module to act according to the modulation signal.

[0106] The total output signal can be one, two, or three of the following signals: a total output voltage, a total output current, and a total output power.

[0107] Specifically, as Figure 15 shown, in step S1320, the steps of generating the modulation signal include:

[0108] Step S1321, generating a fifth control signal according to the total output signal and the total output reference signal.

[0109] Step S1322, generating a sixth control signal according to the first output current and the first output reference current.

[0110] Step S1323, receiving the input voltage of the corresponding first power module, and generating a corresponding third control signal according to the corresponding input voltage and the first input reference voltage.

[0111] Step S1324: Generate a corresponding first modulation signal according to the fifth control signal, the sixth control signal, and the third control signal, and control the switches in the corresponding first power module to act according to the first modulation signal.

[0112] Step S1325: Generate a seventh control signal according to the total output signal and the total output reference signal.

[0113] Step S1326: Generate an eighth control signal according to the second output current and the second output reference current.

[0114] Step S1327: Receive the input voltage of the corresponding second power module, and generate a corresponding fourth control signal according to the corresponding input voltage and the second input reference voltage.

[0115] Step S1328: Generate a corresponding second modulation signal according to the seventh control signal, the eighth control signal, and the fourth control signal, and control the switches in the corresponding second power module to act according to the second modulation signal.

[0116] Among them, the fifth control signal and the seventh control signal can be the same signal or different signals.

[0117] According to the type of the total output signal, different control strategies can be adopted, that is, the processes of generating the fifth control signal, the sixth control signal, the seventh control signal, and the eighth control signal in Step S1321, Step S1322, Step S1325, and Step S1326 are different. The specific situations are described in detail as follows:

[0118] When the total output signal is a total output voltage, Step S1321 may include: generating a fifth control signal according to the total output voltage and the total output reference voltage; Step S1322 may include: obtaining a first output power according to the total output voltage and the first output current; generating a sixth control signal according to the first output power and the first output reference power. Step S1325 may include: generating a seventh control signal according to the total output voltage and the total output reference voltage; Step S1326 may include: obtaining a second output power according to the total output voltage and the second output current; generating an eighth control signal according to the second output power and the second output reference power.

[0119] When the total output signal includes a total output voltage and a total output current, step S1321 may include: generating a fifth control signal according to the total output current and the total output reference current; step S1322 may include: obtaining a first output power according to the total output voltage and the first output current; generating a sixth control signal according to the first output power and the first output reference power. Step S1325 may include: generating a seventh control signal according to the total output current and the total output reference current; step S1326 may include: obtaining a second output power according to the total output voltage and the second output current; generating an eighth control signal according to the second output power and the second output reference power.

[0120] When the total output signal includes a total output voltage and a total output power, step S1321 may include: generating a fifth control signal according to the total output power and the total output reference power; step S1322 may include: obtaining a first output power according to the total output voltage and the first output current; generating a sixth control signal according to the first output power and the first output reference power. Step S1325 may include: generating a seventh control signal according to the total output power and the total output reference power; step S1326 may include: obtaining a second output power according to the total output voltage and the second output current; generating an eighth control signal according to the second output power and the second output reference power.

[0121] When the total output signal is a total output voltage, step S1321 may include: obtaining a total output power according to the total output voltage, the first output current and the second output current; generating a fifth control signal according to the total output power and the total output reference power; step S1322 may include: obtaining a first output power according to the total output voltage and the first output current; generating a sixth control signal according to the first output power and the first output reference power. Step S1325 may include: generating a seventh control signal according to the total output power obtained in step S1321 and the total output reference power; step S1326 may include: obtaining a second output power according to the total output voltage and the second output current; generating an eighth control signal according to the second output power and the second output reference power.

[0122] Similarly, in the above steps, the first input reference voltage and the second input reference voltage may be equal or unequal.

[0123] When the difference between the corresponding input voltage and the input reference voltage is greater than the first threshold or less than the second threshold, a voltage equalization control unit adjusts the third control signal or the fourth control signal; when the difference is not greater than the first threshold and not less than the second threshold, the voltage equalization control unit maintains the corresponding third control signal or fourth control signal. Here, the first threshold is greater than or equal to the second threshold.

[0124] In the embodiment of the present invention, the control algorithm solves the problem of unbalanced series voltages on the high-voltage side of the DC conversion system without adding a hardware voltage equalization circuit, which has a relatively low cost. Moreover, through input voltage control and upper and lower bus output power control, when there is a connection from the midpoint of the bus in the ISOP DC conversion system, it is ensured that the input voltages of the series-connected power modules are equalized and the upper and lower bus output powers are distributed according to the reference. In addition, the number of power modules in the DC conversion system in the embodiment of the present invention can be flexibly changed according to the application scenario, and has strong scalability.

[0125] In addition, in the embodiment of the present invention, the series midpoint on the high-voltage side of the ISOP DC conversion system is connected to the ground or the midpoint of the DC bus, which can reduce the voltage of each power module to the ground and can also provide more flexible load-carrying capacity and improve system reliability.

[0126] In the DC conversion system and its control method in the embodiment of the present invention, the input ends of the upper power module group and the lower power module group are connected in series, and the output ends are connected in parallel. The controller controls the switches inside each power module to act according to the input voltage at the input end of each power module and the output currents at the output ends of the upper and lower power module groups, and can realize voltage equalization of the input voltage of each power module and current equalization control of the output current.

[0127] Those skilled in the art will readily conceive of other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present invention, which follow the general principles of the present invention and include known common knowledge or conventional technical means in the technical field not disclosed by the present invention. The specification and embodiments are only to be regarded as exemplary, and the true scope and spirit of the present invention are pointed out by the following claims.

[0128] It should be understood that the present invention is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present invention is only limited by the appended claims.

Claims

1. A DC conversion system, characterized in that, it includes: an input end and an output end; an upper power module group, including an input end, an output end and at least two first power modules, the input ends of the at least two first power modules are connected in series, and the output ends of the at least two first power modules are connected in parallel; a lower power module group, including an input end, an output end and at least two second power modules, the input ends of the at least two second power modules are connected in series, and the output ends of the at least two second power modules are connected in parallel; after the input ends of the upper power module group and the lower power module group are connected in series, they are connected to the input end of the DC conversion system, and after the output ends of the upper power module group and the lower power module group are connected in parallel, they are connected to the output end of the DC conversion system; a controller, coupled to the upper power module group and the lower power module group, the controller receives and generates a modulation signal based on the input voltage of each of the input ends of the first power module and the second power module, the first output current of the output end of the upper power module group, the second output current of the output end of the lower power module group, and a total output signal of the output end of the DC conversion system, so as to control the switches in each of the first power module and the second power module to act; the series connection point of the input end of the upper power module group and the input end of the lower power module group is grounded or connected to the voltage midpoint of the input end of the DC conversion system.

2. The DC conversion system according to claim 1, characterized in that, the number of the first power modules is different from that of the second power modules.

3. The DC conversion system according to claim 1, characterized in that, the total output signal includes at least one of the following: a total output voltage, a total output current, a total output power.

4. The DC conversion system according to claim 1, characterized in that, the controller includes a main controller and a plurality of local controllers, the main controller is coupled to the plurality of local controllers, and the main controller is used to generate a first control signal according to the first output current and the total output signal; generate a second control signal according to the second output current and the total output signal; the plurality of local controllers are respectively coupled to a corresponding one of the first power modules and the second power modules, wherein, the plurality of local controllers coupled to the first power modules are respectively used to: receive the first control signal; receive the corresponding input voltage, and generate a corresponding third control signal according to the corresponding input voltage and a first input reference voltage; generate a corresponding first modulation signal according to the first control signal and the third control signal, so as to control the switches in the corresponding first power module to act; the plurality of local controllers coupled to the second power modules are respectively used to: receive the second control signal; receive the corresponding input voltage, and generate a corresponding fourth control signal according to the corresponding input voltage and a second input reference voltage; Generate a corresponding second modulation signal according to the second control signal and the fourth control signal to control the switches in the corresponding second power module to actuate.

5. The DC conversion system according to claim 4, wherein, the main controller is configured to: generate a fifth control signal according to the total output signal and the total output reference signal; generate a sixth control signal according to the first output current and the first output reference current; and generate the first control signal according to the fifth control signal and the sixth control signal; generate a seventh control signal according to the total output signal and the total output reference signal; generate an eighth control signal according to the second output current and the second output reference current; and generate the second control signal according to the seventh control signal and the eighth control signal.

6. The DC conversion system according to claim 4, wherein, the total output signal is a total output voltage; the main controller is configured to: generate a fifth control signal according to the total output voltage and the total output reference voltage; obtain a first output power according to the total output voltage and the first output current; generate a sixth control signal according to the first output power and the first output reference power; generate the first control signal according to the fifth control signal and the sixth control signal; generate a seventh control signal according to the total output voltage and the total output reference voltage; obtain a second output power according to the total output voltage and the second output current; generate an eighth control signal according to the second output power and the second output reference power; generate the second control signal according to the seventh control signal and the eighth control signal.

7. The DC conversion system according to claim 4, wherein, the total output signal includes a total output voltage and a total output current; the main controller is configured to: generate a fifth control signal according to the total output current and the total output reference current; obtain a first output power according to the total output voltage and the first output current; generate a sixth control signal according to the first output power and the first output reference power; generate the first control signal according to the fifth control signal and the sixth control signal; generate a seventh control signal according to the total output current and the total output reference current; obtain a second output power according to the total output voltage and the second output current; generate an eighth control signal according to the second output power and the second output reference power; generate the second control signal according to the seventh control signal and the eighth control signal.

8. The DC conversion system according to claim 4, wherein, the total output signal includes a total output voltage and a total output power; the main controller is configured to: generate a fifth control signal according to the total output power and the total output reference power; obtain a first output power according to the total output voltage and the first output current; generate a sixth control signal according to the first output power and the first output reference power; Generate the first control signal according to the fifth control signal and the sixth control signal; Generate a seventh control signal according to the total output power and the total output reference power; Obtain a second output power according to the total output voltage and the second output current; Generate an eighth control signal according to the second output power and the second output reference power; Generate the second control signal according to the seventh control signal and the eighth control signal.

9. The DC conversion system according to claim 4, wherein, the total output signal includes a total output voltage; the main controller is configured to: Obtain the total output power according to the total output voltage, the first output current, and the second output current; generate a fifth control signal according to the total output power and the total output reference power; Obtain a first output power according to the total output voltage and the first output current; generate a sixth control signal according to the first output power and the first output reference power; Generate the first control signal according to the fifth control signal and the sixth control signal; Generate a seventh control signal according to the total output power and the total output reference power; Obtain a second output power according to the total output voltage and the second output current; Generate an eighth control signal according to the second output power and the second output reference power; Generate the second control signal according to the seventh control signal and the eighth control signal.

10. A DC conversion system, wherein, comprises: an input end, an output end; an upper power module group, including an input end, an output end, and at least two first power modules, the input ends of the at least two first power modules are connected in series, and the output ends of the at least two first power modules are connected in parallel; a lower power module group, including an input end, an output end, and at least two second power modules, the input ends of the at least two second power modules are connected in series, and the output ends of the at least two second power modules are connected in parallel; after the input end of the upper power module group and the input end of the lower power module group are connected in series, they are connected to the input end of the DC conversion system, and after the output end of the upper power module group and the output end of the lower power module group are connected in parallel, they are connected to the output end of the DC conversion system; a controller, coupled to the upper power module group and the lower power module group, the controller is configured to: Receive the input voltage of each of the input ends of the first power modules and the second power modules; Receive at least two of the first output current at the output end of the upper power module group, the second output current at the output end of the lower power module group, and the total output current at the output end of the DC conversion system; Generate a modulation signal according to at least two of the first output current, the second output current, and the total output current, and the input voltage, to control the switches in each of the first power modules and the second power modules to act; The series connection point of the input end of the upper power module group and the input end of the lower power module group is grounded or connected to the voltage midpoint of the input end of the DC conversion system.

11. The DC conversion system according to claim 10, characterized in that, the number of the first power modules is different from that of the second power modules.

12. The DC conversion system according to claim 10, characterized in that, the controller includes a main controller and a plurality of local controllers, the main controller is coupled to the plurality of local controllers, and the main controller is configured to generate a ninth control signal according to the first output current and the first output reference current; generate a tenth control signal according to the second output current and the second output reference current; each of the plurality of local controllers is coupled to a corresponding one of the first power module and the second power module, wherein each of the plurality of local controllers coupled to the first power module is configured to: receive the ninth control signal; receive the corresponding input voltage, and generate a corresponding third control signal according to the corresponding input voltage and the first input reference voltage; generate a corresponding first modulation signal according to the ninth control signal and the third control signal, so as to control the switches in the corresponding first power module to act; each of the plurality of local controllers coupled to the second power module is configured to: receive the tenth control signal; receive the corresponding input voltage, and generate a corresponding fourth control signal according to the corresponding input voltage and the second input reference voltage; generate a corresponding second modulation signal according to the tenth control signal and the fourth control signal, so as to control the switches in the corresponding second power module to act.

13. The DC conversion system according to claim 10, characterized in that, the controller includes a main controller and a plurality of local controllers, the main controller is coupled to the plurality of local controllers, and the main controller is configured to generate a ninth control signal according to the first output current and the first output reference current; generate a tenth control signal according to the total output current and the total output reference current; each of the plurality of local controllers is coupled to a corresponding one of the first power module and the second power module, wherein each of the plurality of local controllers coupled to the first power module is configured to: receive the ninth control signal; receive the corresponding input voltage, and generate a corresponding third control signal according to the corresponding input voltage and the first input reference voltage; generate a corresponding first modulation signal according to the ninth control signal and the third control signal, so as to control the switches in the corresponding first power module to act; each of the plurality of local controllers coupled to the second power module is configured to: receive the tenth control signal; receive the corresponding input voltage, and generate a corresponding fourth control signal according to the corresponding input voltage and the second input reference voltage; generate a corresponding second modulation signal according to the tenth control signal and the fourth control signal, so as to control the switches in the corresponding second power module to act.

14. The DC conversion system according to claim 10, characterized in that, the controller includes a main controller and a plurality of local controllers, The master controller is coupled to the plurality of local controllers, and the master controller is configured to generate a ninth control signal according to the total output current and the total output reference current; Generate a tenth control signal according to the second output current and the second output reference current; The plurality of local controllers are respectively coupled to a corresponding one of the first power module and the second power module, wherein each of the plurality of local controllers coupled to the first power module is configured to: Receive the ninth control signal; Receive the corresponding input voltage, and generate a corresponding third control signal according to the corresponding input voltage and the first input reference voltage; Generate a corresponding first modulation signal according to the ninth control signal and the third control signal, so as to control the switches in the corresponding first power module to act; Each of the plurality of local controllers coupled to the second power module is configured to: Receive the tenth control signal; Receive the corresponding input voltage, and generate a corresponding fourth control signal according to the corresponding input voltage and the second input reference voltage; Generate a corresponding second modulation signal according to the tenth control signal and the fourth control signal, so as to control the switches in the corresponding second power module to act.

15. The DC conversion system according to claim 10, wherein, The controller includes a main controller and a plurality of local controllers, The master controller is coupled to the plurality of local controllers, and the master controller is further configured to receive the total output voltage at the output end of the DC conversion system, and generate a ninth control signal and a tenth control signal according to at least two of the first output current, the second output current and the total output current, and the total output voltage; The plurality of local controllers are respectively coupled to a corresponding one of the first power module and the second power module, wherein each of the plurality of local controllers coupled to the first power module is configured to: Receive the ninth control signal; Receive the corresponding input voltage, and generate a corresponding third control signal according to the corresponding input voltage and the first input reference voltage; Generate a corresponding first modulation signal according to the ninth control signal and the third control signal, so as to control the switches in the corresponding first power module to act; Each of the plurality of local controllers coupled to the second power module is configured to: Receive the tenth control signal; Receive the corresponding input voltage, and generate a corresponding fourth control signal according to the corresponding input voltage and the second input reference voltage; Generate a corresponding second modulation signal according to the tenth control signal and the fourth control signal, so as to control the switches in the corresponding second power module to act.

16. A control method for a DC conversion system, wherein, The DC conversion system includes at least two first power modules, at least two second power modules, and a controller. The input ends of the at least two first power modules are connected in series to form an upper power module group, and the input ends of the at least two second power modules are connected in series to form a lower power module group. The output ends of each of the first power modules and each of the second power modules are connected in parallel. The controller is coupled to each of the first power modules and the second power modules. The control method includes: Obtaining the respective input voltages of each of the first power modules and the second power modules; Obtaining a first output current of the upper power module group, a second output current of the lower power module group, and a total output signal at the output end of the DC conversion system; Generating a modulation signal based on the input voltage, the first output current, the second output current, and the total output signal; Controlling the switches in each of the first power modules and the second power modules to act according to the modulation signal; The series connection point of the input ends of the upper power module group and the input ends of the lower power module group is grounded or connected to the voltage midpoint of the input end of the DC conversion system.

17. According to the control method described in claim 16, characterized in that, The total output signal includes at least one of the following: A total output voltage, a total output current, a total output power.

18. According to the control method described in claim 16, characterized in that, The step of generating a modulation signal based on the input voltage, the first output current, the second output current, and the total output signal includes: Generating a fifth control signal based on the total output signal and a total output reference signal; Generating a sixth control signal based on the first output current and a first output reference current; Generating a corresponding third control signal based on the input voltage corresponding to each of the first power modules and a first input reference voltage; Generating a corresponding first modulation signal based on the fifth control signal, the sixth control signal, and the third control signal; controlling the switches in the corresponding first power modules to act according to the first modulation signal; and, Generating a seventh control signal based on the total output signal and a total output reference signal; Generating an eighth control signal based on the second output current and a second output reference current; Generating a corresponding fourth control signal based on the input voltage corresponding to each of the second power modules and a second input reference voltage; Generating a corresponding second modulation signal based on the seventh control signal, the eighth control signal, and the fourth control signal; controlling the switches in the corresponding second power modules to act according to the second modulation signal.

19. According to the control method described in claim 16, characterized in that, The total output signal is a total output voltage; the step of generating a modulation signal based on the input voltage, the first output current, the second output current, and the total output signal includes: Generating a fifth control signal based on the total output voltage and a total output reference voltage; Obtain a first output power based on the total output voltage and the first output current; generate a sixth control signal based on the first output power and a first output reference power; Generate corresponding third control signals according to the input voltage corresponding to each of the first power modules and a first input reference voltage; Generate corresponding first modulation signals according to the fifth control signal, the sixth control signal, and the third control signals; control the switches in the corresponding first power modules to act according to the first modulation signals; and, Generate a seventh control signal based on the total output voltage and a total output reference voltage; Obtain a second output power based on the total output voltage and the second output current; generate an eighth control signal based on the second output power and a second output reference power; Generate corresponding fourth control signals according to the input voltage corresponding to each of the second power modules and a second input reference voltage; Generate corresponding second modulation signals according to the seventh control signal, the eighth control signal, and the fourth control signals; control the switches in the corresponding second power modules to act according to the second modulation signals.

20. The control method according to claim 16, characterized in that the total output signal includes a total output voltage and a total output current; the step of generating a modulation signal according to the input voltage, the first output current, the second output current, and the total output signal includes: Generate a fifth control signal based on the total output current and a total output reference current; Obtain a first output power based on the total output voltage and the first output current; generate a sixth control signal based on the first output power and a first output reference power; Generate corresponding third control signals according to the input voltage corresponding to each of the first power modules and a first input reference voltage; Generate corresponding first modulation signals according to the fifth control signal, the sixth control signal, and the third control signals; control the switches in the corresponding first power modules to act according to the first modulation signals; and, Generate a seventh control signal based on the total output current and a total output reference current; Obtain a second output power based on the total output voltage and the second output current; generate an eighth control signal based on the second output power and a second output reference power; Generate corresponding fourth control signals according to the input voltage corresponding to each of the second power modules and a second input reference voltage; Generate corresponding second modulation signals according to the seventh control signal, the eighth control signal, and the fourth control signals; control the switches in the corresponding second power modules to act according to the second modulation signals.

21. The control method according to claim 16, characterized in that the total output signal includes a total output voltage and a total output power; the step of generating a modulation signal according to the input voltage, the first output current, the second output current, and the total output signal includes: Generate a fifth control signal based on the total output power and a total output reference power; Obtain a first output power based on the total output voltage and the first output current; generate a sixth control signal based on the first output power and a first output reference power; Generate a corresponding third control signal based on the input voltage corresponding to each of the first power modules and a first input reference voltage; Generate a corresponding first modulation signal based on the fifth control signal, the sixth control signal, and the third control signal; control the switches in the corresponding first power modules to act according to the first modulation signal; and, Generate a seventh control signal based on the total output power and a total output reference power; Obtain a second output power based on the total output voltage and the second output current; generate an eighth control signal based on the second output power and a second output reference power; Generate a corresponding fourth control signal based on the input voltage corresponding to each of the second power modules and a second input reference voltage; Generate a corresponding second modulation signal based on the seventh control signal, the eighth control signal, and the fourth control signal; control the switches in the corresponding second power modules to act according to the second modulation signal.

22. The control method according to claim 16, wherein, the total output signal is a total output voltage; The steps of generating a modulation signal based on the input voltage, the first output current, the second output current, and the total output signal include: Obtain a total output power based on the total output voltage, the first output current, and the second output current; generate a fifth control signal based on the total output power and a total output reference power; Obtain a first output power based on the total output voltage and the first output current; generate a sixth control signal based on the first output power and a first output reference power; Generate a corresponding third control signal based on the input voltage corresponding to each of the first power modules and a first input reference voltage; Generate a corresponding first modulation signal based on the fifth control signal, the sixth control signal, and the third control signal; control the switches in the corresponding first power modules to act according to the first modulation signal; and, Generate a seventh control signal based on the total output power and a total output reference power; Obtain a second output power based on the total output voltage and the second output current; generate an eighth control signal based on the second output power and a second output reference power; Generate a corresponding fourth control signal based on the input voltage corresponding to each of the second power modules and a second input reference voltage; Generate a corresponding second modulation signal based on the seventh control signal, the eighth control signal, and the fourth control signal; control the switches in the corresponding second power modules to act according to the second modulation signal.

23. The control method according to any one of claims 18 to 22, wherein, the first input reference voltage and the second input reference voltage are not equal.

24. The control method according to any one of claims 18 to 22, wherein, When the difference between the corresponding input voltage and the corresponding input reference voltage is greater than a first threshold or less than a second threshold, a voltage equalization control unit adjusts the third control signal or the fourth control signal; When the difference is less than or equal to the first threshold and greater than or equal to the second threshold, the voltage equalization control unit maintains the corresponding third control signal or fourth control signal.

25. The control method according to claim 24, wherein, the first threshold is greater than or equal to the second threshold.

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