Patent Grant
11539284
The present disclosure relates to the technical field of power electronics, in particular to a direct current (DC) conversion system and a control method thereof.
With the development of industry and the increase of electric equipment, the reliability of power supplies and the requirements of voltage and current have gradually increased. Due to the limitations of voltage and current stresses of power switching devices, a single power supply cannot meet application occasions with high voltage and high power. A Direct Current/Direct Current (DC/DC) combined conversion system having a high-voltage side in series and a low-voltage side in parallel can be adopted to distribute the power equally to each DC/DC unit and reduce voltage stress and current stress of each DC/DC unit. Therefore, it is possible to select low-voltage power switching devices with better performance. In addition, each DC/DC unit of the DC/DC combined conversion system has the advantages of modularization, short development cycle, easy expansion and redundancy design.
In a DC/DC combined conversion system with a high-voltage side in series and a low-voltage side in parallel, in order to ensure stable operation of the converter, it is necessary to ensure a voltage equalization (voltage balancing) on the series side and a current equalization (current balancing) on the parallel side. Especially when parameters of the DC/DC converter have a great impact on the voltage deviation, the voltage imbalance or the current imbalance is more serious, which will affect the selection of power switches, thermal design and the like, and reduce conversion system performance and reliability.
In summary, the voltage equalization and current equalization of the combined DC/DC conversion system needs a solution urgently.
It should be noted that the information disclosed in the above background section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute prior art known to those of ordinary skill in the art.
According to a first aspect of the present disclosure, a DC conversion system is provided, the DC conversion system includes: an input terminal and an output terminal; an upper power module group comprising an input terminal, an output terminal, and at least two first power modules, the input terminals of the at least two first power modules being connected in series, and the output terminals of the at least two first power modules being connected in parallel; a lower power module group comprising an input terminal, an output terminal, and at least two second power modules, the input terminals of the at least two second power modules being connected in series, and the output terminals of the at least two second power modules being connected in parallel; the input terminal of the upper power module group and the input terminal of the lower power module group being connected in series, and the output terminal of the upper power module group and the output terminal of the lower power module group being connected in parallel; a controller coupled to the upper power module group and the lower power module group, and configured to: receive an input voltage of respective input terminal of each of the first power modules and the second power modules, a current of the output terminal of the upper power module group defining a first output current, a current of the output terminal of the lower power module group defining a second output current, and a total output signal of the output terminal of the DC conversion system, and generate a modulation signal according to the input voltage of respective input terminal of each of the first power modules and the second power modules, the first output current, the second output current, and the total output signal, so as to control a power switch of each of the first power modules and the second power modules.
According to a second aspect of the present disclosure, a DC conversion system is provided, the DC conversion system includes an input terminal and an output terminal; an upper power module group comprising an input terminal, an output terminal, and at least two first power modules, the input terminals of the at least two first power modules being connected in series, and the output terminals of the at least two first power modules being connected in parallel; a lower power module group comprising an input terminal, an output terminal, and at least two second power modules, the input terminals of the at least two second power modules being connected in series, and the output terminals of the at least two second power modules being connected in parallel; the input terminal of the upper power module group and the input terminal of the lower power module group being connected in series, and the output terminal of the upper power module group and the output terminal of the lower power module group being connected in parallel; a controller coupled to the upper power module group and the lower power module group, and the controller is configured to: receive an input voltage of respective input terminal of each of the first power modules and the second power modules; a current of the output terminal of the upper power module group defining a first output current, a current of the output terminal of the lower power module group defining a second output current, a current of the output terminal of the DC conversion system defining a total output current, receive at least two of the first output current, the second output current, and the total output current; and generate a modulation signal according to at least two of the first output current, the second output current, and the total output current, as well as the input voltage of each of the first power modules and the second power modules, so as to control a power switch of each of the first power modules and the second power modules.
According to a third aspect of the present disclosure, a control method for a DC conversion system is provided, the DC conversion system includes at least two first power modules, at least two second power modules, and a controller, and input terminals of the at least two first power modules being connected in series to form an upper power module group, input terminals of the at least two second power modules being connected in series to form a lower power module group, and output terminals of each of the first power modules and each of the second power modules being connected in parallel, the controller being coupled to each of the first power modules and the second power modules, and the control method includes: acquiring a respective input voltage of each of the first power modules and the second power modules; acquiring 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 of the output terminal of the DC conversion system; generating a modulation signal according to the input voltage of each of the first power modules and the second power modules, the first output current, the second output current, and the total output signal; according to the modulation signal, controlling a power switch of each of the first power modules and the second power modules.
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.
The drawings herein are incorporated into and constitute a part of the specification. The drawings show embodiments consistent with the present application, and are used to explain the principles of the application together with the specification. Obviously, the drawings in the following description are only some embodiments of the present disclosure. For those of ordinary skill in the art, without paying any creative work, other drawings can be obtained based on these drawings.
Example embodiments will now be described more fully with reference to the drawings. However, the example embodiments can be implemented in various forms, and should not be construed as being limited to the examples set forth herein; on the contrary, providing these embodiments makes the disclosure more comprehensive and complete, and fully conveys the concept of the example embodiments to those skilled in the art.
In addition, the features, structures, or characteristics described above may be combined in any suitable manner in one or more embodiments. In the description below, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solution of the present disclosure may be practiced without one or more of the specific details, or other methods, components, apparatus, steps and the like may be employed. In other instances, well-known methods, apparatus, implements or operations are not shown or described in detail to avoid obscuring various aspects of the present disclosure.
Some of the block diagrams shown in the figures are functional entities and do not necessarily correspond to physically or logically separate entities. These functional entities may be implemented in software, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and/or processor devices and/or microcontroller devices.
Flowcharts shown in the drawings are only exemplary illustrations, and it is not necessary to include all contents and operations/steps, or to be executed in an order described. For example, some of the operations/steps can also be decomposed, and some of the operations/steps can be merged or partially merged, so an order of actual execution may change according to actual situations.
In the existing DC/DC combined conversion system in which a plurality of DC/DC units are connected in series on high-voltage side and connected in parallel on low-voltage side as well as a neutral point of high-voltage side is grounded, it is required to have a balance between voltages of the upper and lower parts of the neutral point. However, since parameters of DC/DC units in the upper and lower parts are different, such as the numbers of the DC/DC units in the upper and lower parts is inconsistent, or loads of the upper and lower parts are different, the voltage deviation will be large. In this case, measures for the voltage equalization need to be taken to control total output voltage, total output current or total output power of the system, or to control respective output power of the upper and lower buses.
For the DC/DC combined conversion system in which the plurality of DC/DC units are connected in series on high-voltage side and connected in parallel on low-voltage side as well as the neutral point of high-voltage side is grounded, when a equalization control is performed to voltages of upper and lower buses, it is necessary to make power of respective DC/DC units corresponding to the upper and lower buses be balanced separately, that is, voltage equalization on series side and current equalization on parallel side. At the same time, the system needs to be simple, easy to realize expansion and redundancy, in order to improve the reliability of the entire system.
In the existing voltage equalization scheme, hardware measures and software measures can be used. The hardware voltage equalization circuit is easy to implement when the number of DC/DC units is small, but if the system is applied to a medium-voltage or a high-voltage scenario, the increase of the number of DC/DC units will inevitably increase the system complexity. The existing software voltage equalization control is to perform unified voltage equalization control on DC/DC units of the entire bus, therefore it is only suitable for systems in which there is no neutral point or the neutral point has not connected to the ground, but it cannot guarantee voltages of the upper and lower buses of the system having neutral point grounded are balanced, and cannot guarantee voltages of respective DC/DC units are balanced yet.
It is obvious that, occurrence of voltage imbalance in a DC/DC combined conversion system with a high-voltage side in series and a low-voltage side in parallel will affect the selection of power switches, thermal design and so on, and reduce performance and reliability of the converter system. In order to ensure stable operation of the converter system, it is necessary to ensure voltage equalization on series side and current equalization on parallel side of all DC/DC units in the combined conversion system.
The embodiments of the present disclosure provide a DC conversion system and a control method thereof, so as to realize voltage equalization of the DC conversion system.
The embodiment of the present disclosure provides a DC conversion system. The DC conversion system includes an input terminal and an output terminal; an upper power module group; a lower power module group; and a controller. The upper power module group includes an input terminal, an output terminal, and at least two first power modules. As shown in
In the embodiment of the present disclosure, by sampling the input voltage of each of the power modules, the respective output current of the upper and lower power module groups, and the total output signal of the DC conversion system, and performing a closed-loop control according to the sampling results, a equalization control method can be performed to each of the power modules.
In the following, the power modules include first power modules and second power modules.
As shown in
In the embodiment of the present disclosure, the series-connected node of the upper power module group and the lower power module group is grounded or connected with a voltage neutral point 0 of the input terminal of the DC conversion system. The neutral point of the power modules connected in series on high-voltage side is grounded with a low resistance, and then respective voltages-to-ground of upper and lower buses on high-voltage side of the DC conversion system are reduced to a half of a bus voltage, which can reduce a common-mode voltage-to-ground of each of the power modules. Since the technical solution of the embodiment of the present disclosure is to sample the input voltage of each of the power modules and the output currents of the upper and lower power module groups, and perform the closed-loop control according to the sampling results, so that the equalization control can be performed to each of the power modules accurately, which is not restricted by where the series-connected node of the upper power module group and the lower power module group is connected, such as connecting to the ground or connecting to the voltage neutral point of the input terminal of the DC conversion system, and can avoid the problems such as serious uneven power distribution of the upper and lower power module groups.
It is worth noting that, the embodiments of the present disclosure are all based on the high-voltage side being as input and the low-voltage side being as output, that is, based on input-series-output-parallel (ISOP), but the present disclosure is not limited to this. It is also applicable to a DC conversion system in which the high-voltage side is the output and the low-voltage side is the input, that is, input-parallel-output-series. The circuit structure shown in
In the embodiment of the present disclosure, the numbers of the first power modules and the second power modules may be the same or different. As shown in
As shown in
As shown in
It is worth noting that the local controller can be integrated with the corresponding power module, or can be set independently with the corresponding power module, and its specific form is not limited.
In this embodiment, the way of coupling between the main controller and the local controllers is not limited, and may be a direct connection, or a communication connection via optical fiber or wireless, etc. The present disclosure is not limited to this.
In addition, the DC conversion system may further include a plurality of input voltage sampling circuits, an output sampling circuit, and output current sampling circuits of the upper and lower power module groups. Each of the input voltage sampling circuits is used to collect or sample a capacitor voltage at the input terminal of a corresponding power module. The output sampling circuit is used to collect or sample one or more of the total output voltage, total output current or total output power of the output terminal of the DC conversion system. The output current sampling circuit of the upper power module group is used to sample the total current of the output terminal of the upper power module group, in which the parallel-connected output terminals of the m first power modules are defined as the output terminal of the upper power module group, namely the first output current Io_up, and the output current sampling circuit of the lower power module group is used to sample the total current of the output terminal of the lower power module group, in which the parallel-connected output terminals of the n second power modules are defined as the output terminal of the lower power module group, namely the second output current Io_dn.
As shown in
As shown in
In this embodiment, the first power module and the second power module may be a series or parallel combination of one or more DC/DC converters. As shown in
Referring to
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 according to the first output current Io_up and the first output reference current Io_up_ref. For example, a first output current deviation is obtained by calculating the difference between the first output reference current Io_up_ref and the first output current Io_up, and the first output current deviation is transmitted to an upper output control unit to generate the sixth control signal c6. It is worth noting that, the first output current Io_up and the first output reference current Io_up_ref can also be replaced with the first output power Po_up and the first output reference power Po_up_ref, wherein the first output power Po_up can be obtained by the calculation of the first output current Io_up and the total output voltage Vo, or it can be obtained directly by a power sampling circuit.
The main controller further generates the first control signal c1 according to the fifth control signal c5 and the sixth control signal c6, and respectively sends the first control signal c1 to a local controller corresponding to each first power module.
Each of the local controllers is used to receive an input voltage Vin1_k of a corresponding first power module, and obtain a third control signal c3 according to the input voltage Vin1_k and a corresponding first input reference voltage Vin_up_ref k. For example, the difference between the input voltage Vin1_k and the first input reference voltage Vin_up_ref k is input to a corresponding voltage equalization control unit, and the voltage equalization 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, and the first modulation signal is used to control the power switch in the corresponding first power module, that is, the first modulation signal can be converted to a driving signal so as to drive the power switch of the corresponding first power module on or off.
Similarly, as shown in
It is worth noting that the fifth control signal c5 and the seventh control signal c7 can be the same signal or different signals. Where, when the upper power module group and the lower power module group both use a same total output control unit, the fifth control signal c5 and the seventh control unit c7 are the same signal; and 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.
The main controller is also used to receive the second output current Io_dn. At the same time, the main controller can generate a second output reference current Io_dn_ref, and then generate an eighth control signal c8 according to the second output current Io_dn and the second output reference current Io_dn_ref. It is worth noting that the second output current Io_dn and the second output reference current Io_dn_ref can also be replaced with the second output power Po_dn and the second output reference power Po_dn_ref, wherein the second output power Po_dn can be obtained by the calculation of the second output current Io_dn and the total output voltage Vo, or it can be obtained directly by a power sampling circuit.
The main controller further generates the second control signal c2 according to the seventh control signal c7 and the eighth control signal c8, and respectively sends the second control signal c2 to a local controller corresponding to each second power module. Each of the local controllers is configured to respectively receive the input voltage Vin2_k of the corresponding second power module, and obtain the fourth control signal c4 according to the input voltage Vin2_k and a corresponding second input reference voltage Vin_dn_ref_k. Finally, the local controller generates a second modulation signal according to the fourth control signal c4 and the second control signal c2, and the second modulation signal is used to control the power switch in the corresponding second power module, that is, the first modulation signal can be converted to a driving signal so as to drive the power switch of the corresponding second power module on or off.
In the embodiment, the above-mentioned first to eighth control signals (i.e., c1-c8) may be frequency signals, duty cycle signals or other forms of signals, and the present disclosure is not limited.
In the embodiment, 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 output capabilities or requirements of the upper and lower power module groups, and each can be ½ of the total output power or the total output current of the DC conversion system, or can also be calculated based on the output power or output current that each of the actual power modules needs to bear.
In the embodiment of the present disclosure, a signal processing process completed respectively by the main controller and the local controllers includes various kinds of ways for distribution. In the embodiment shown in
Further, in some other embodiments, the main controller can also be omitted, and the above-mentioned control functions can be completed only by the local controllers. In the DC conversion system as shown in
The output reference current generation module generates a first output reference current Io_up_ref_k corresponding to the first power modules and a second output reference current Io_dn_ref_k corresponding to the second power modules, based on the obtained output currents and module operating status of the upper and lower power module groups, and sends the first output reference current Io_up_ref_k and the second output reference current Io_dn_ref_k to respective slaves corresponding to the upper and lower power module groups. Each of the slaves obtains the output current control signal Io1_Ctrl_k or Io2_Ctrl_k according to the first output reference current Io_up_ref_k or the second output reference current Io_dn_ref k, the actual output current Io1_k or Io2_k, and finally generates a first modulation signal (or a second modulation signal) according to the obtained voltage equalization control signal Vin1_Ctrl_k (or Vin2_Ctrl_k), the output current control signal Io1_Ctrl_k (or Io2_Ctrl_k) and the total output voltage control signal Vo_Ctrl, so as to control the power switch in the corresponding first power module (or the second power module).
In the competitive master-slave solution, the master is not limited to its location, it may be a local controller corresponding to a certain first power module of the upper power module group, or a local controller corresponding to a certain second power module of the lower power module group. Once the master has failed, the competitive master-slave mechanism is activated, and another local controller takes over the positon of the master and becomes a new master. In addition, the input reference voltage and the output reference current may be the same or not exactly the same.
As shown in
In the DC conversion system provided by another embodiment of the present disclosure, the circuit structure is similar to that of the DC conversion system in the embodiment shown in
In the embodiment of the present disclosure, a series-connected point of the input terminal of the upper power module group and the input terminal of the lower power module group is grounded or connected to the voltage neutral point of the input terminal of the DC conversion system. The number of the first power modules and the number of the second power modules may be the same or different.
In the embodiment of the present disclosure, the main controller may adopt different control strategies according to different sampling signals. For example, as shown in
In the embodiment shown in
It is worth noting 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 can 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 respective local controllers corresponding to the first power modules; and the tenth control signal c10 is sent to respective local controllers corresponding to the second power modules.
In the embodiment of the present disclosure, the process of generating the ninth control signal c9 and the tenth control signal c10 can also be completed in respective local controller, and the main controller is only used to generate respective 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 the reference signal to the respective local controller of each of the power modules. Alternatively, the main 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 the first output current deviation, the second output current deviation or the total output current deviation to the corresponding local controller. In short, the functions performed respectively by the main controller and the local controller can be arbitrarily allocated, and the present disclosure is not limited to this.
Moreover, in other embodiments, the main controller can be eliminated, and the local controllers in the upper and lower power module groups respectively determine one of its local controllers as a corresponding master through the competitive master-slave mechanism, and the rest other local controllers are determined as slaves. The ninth control signal c9 and the tenth control signal c10 are generated by the corresponding master respectively, and then the ninth control signal c9 or the tenth control signal c10 is sent to the slaves in the corresponding power module group by the master inside the same power module group, and then is used to generate a corresponding first modulation signal and second modulation signal.
In the embodiment of the present disclosure, the second control strategy is to generate a modulation signal, according to 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 respective input voltage of each of the power modules. For example, taking that the sampled currents are the first output current Io_up and the second output current Io_dn as an example, the controller includes a main controller and a plurality of local controllers, and the main controller is coupled to the plurality of local controllers. The main controller is configured to: calculate a first output power Po_up according to the first output current Io_up and the total output voltage Vo, and generate a ninth control signal c9 according to the first output power Po_up and a first output reference power Po_up_ref. At the same time, the main controller calculates a second output power Po_dn according to the second output current Io_dn and the total output voltage Vo, and generate a tenth control signal c10 according to the second output power Po_dn and a second output reference power Po_dn_ref. The plurality of local controllers are each 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 each used 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; and generate a corresponding first modulation signal according to the ninth control signal c9 and the third control signal c3, so as to control the power switch in the corresponding first power module. Similarly, each of the plurality of local controllers coupled to the second power modules is used 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; and generate a corresponding second modulation signal according to the tenth control signal c10 and the fourth control signal c4, so as to control the power switch in the corresponding second power module.
As shown in
As shown in
As shown in
At step S1310, acquiring respective input voltages of the first power modules and the second power modules, 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 of the output terminal of the conversion system.
At step S1320, generating a modulation signal according to the respective input voltage of the first power modules and the second power modules, the first output current, the second output current, and the total output signal, and controlling power switch in each of the first power modules and the second power modules according to the modulation signal.
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.
For example, as shown in
At step S1321, generating a fifth control signal according to the total output signal and a total output reference signal.
At step S1322, generating a sixth control signal according to the first output current and a first output reference current.
At step S1323, receiving the input voltage of the respective first power module, and generating a corresponding third control signal according to the input voltage and a first input reference voltage.
At step S1324, generating a corresponding first modulation signal according to the fifth control signal, the sixth control signal and the third control signal, and controlling a power switch in the corresponding first power module according to the first modulation signal.
At step S1325, generating a seventh control signal according to the total output signal and the total output reference signal.
At step S1326, generating an eighth control signal according to the second output current and the second output reference current.
At step S1327, receiving the input voltage of the respective second power module, and generating a corresponding fourth control signal according to the input voltage and a second input reference voltage.
At step S1328, generating a corresponding second modulation signal according to the seventh control signal, the eighth control signal, and the fourth control signal, and controlling a power switch in the corresponding second power module according to the second modulation signal.
In the embodiment, the fifth control signal and the seventh control signal may be the same signal, or may be different signals.
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 and step S1325 and step S1326 are different. The details are as follows.
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 a total output reference voltage; step S1322 may include: obtaining a first output power according to the total output voltage and the first output current; and generating a sixth control signal according to the first output power and a first output reference power; step S1325 may include: generating a seventh control signal according to the total output voltage and a total output reference voltage; step S1326 may include: obtaining a second output power according to the total output voltage and the second output current; and generating an eighth control signal according to the second output power and a second output reference power.
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 a total output reference current; step S1322 may include: obtaining a first output power according to the total output voltage and the first output current; and 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; and generating an eighth control signal according to the second output power and a second output reference power.
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 a total output reference power; step S1322 may include: obtaining a first output power according to the total output voltage and the first output current; and generating a sixth control signal according to the first output power and a 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; and generating an eighth control signal according to the second output power and the second output reference power.
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; and 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; and generating a sixth control signal according to the first output power and a 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; and generating an eighth control signal according to the second output power and the second output reference power.
Similarly, in the above steps, the first input reference voltage and the second input reference voltage may be equal or not equal.
When a difference between the corresponding input voltage and the input reference voltage is greater than a first threshold or less than a second threshold, the third control signal or the fourth control signal is adjusted by a voltage equalization control unit; when the difference is not greater than (i.e. less than or equal to) the first threshold and not less than (i.e. greater than or equal to) the second threshold, the voltage equalization control unit maintains the corresponding third control signal or fourth control signal. Herein, the first threshold is greater than or equal to the second threshold.
The embodiment of the present disclosure solves the problem of unbalanced series voltage on the high-voltage side of the DC conversion system by using a control algorithm, which does not need to add a hardware voltage equalization circuit, and therefore has a low cost. In addition, by using the output power control of the upper and lower buses and the input voltage control, the following advantages are realized, in the case that the series neutral point of the ISOP DC conversion system is connected to the ground or connected to the voltage midpoint, it is ensured that the input voltages of the power modules connected in series are equalized and the output power of the upper and lower buses are distributed according to the reference. In addition, the number of power modules of the DC conversion system in the embodiment of the present disclosure can be flexibly changed based on the application condition, therefore having strong scalability.
In addition, in the embodiment of the present disclosure, the series neutral point of the high-voltage side of the ISOP DC conversion system is connected to the ground or connected to the neutral point of the DC bus, which can reduce the voltage-to-ground of each power module and also provide more flexible load-carrying capacity and improved system reliability.
In the DC conversion system and the control method thereof according to the embodiments of the present disclosure, the input terminals of the upper power module group and the lower power module group are connected in series and the output terminals the upper power module group and the lower power module group are connected in parallel. The controller controls the internal power switch of each of power modules to operate, based on the input voltage of the input terminal of each of power modules, and the output currents of the output terminals of the upper and lower power module groups, which can realize the voltage balance control of the respective input voltages of the power modules and the current balance control of the output currents.
After considering the specification and practicing the invention disclosed herein, those skilled in the art will easily think of other embodiments of the present disclosure. This application is intended to cover any variations, uses, or adaptive changes of the present disclosure. These variations, uses, or adaptive changes follow the general principles of the present disclosure and include common knowledge or conventional technical means in the technical field not disclosed by the present disclosure. The description and the embodiments are regarded as exemplary only, and the true scope and spirit of the present disclosure are pointed out by the following claims.
It should be understood that the present disclosure is not limited to the precise structure 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 disclosure is only limited by the appended claims.
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| 202010489095.3 | Jun 2020 | CN | national |
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| 20210376732 A1 | Dec 2021 | US |
