Bipolar inverter system and dc resonant converter and current regulation method thereof

Abstract

The application provides a bipolar inverter system, a direct-current resonant converter and a current regulation method thereof. Since high-frequency ripples exist in the input and output of the direct-current resonant conversion circuit, the high-frequency ripples change along with the change of the PWM carrier, and the PWM carrier regulation of the direct-current resonant conversion circuit can change the capacitor voltage and the inductor voltage in the resonant cavity, and further change the current. Since the current of at least one direct-current resonant conversion circuit is greater than the preset current, the above regulation is performed on the corresponding resonant conversion circuit until the current of each direct-current resonant conversion circuit is less than or equal to the preset current, and the preset current is less than or equal to the maximum bearing current of the corresponding direct-current resonant conversion circuit, so that the method makes each resonant conversion circuit not overload, and the current regulation method of the direct-current resonant converter avoids the overload of the parallelly connected direct-current resonant conversion circuit.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and in particular to a bipolar inverter system, a DC resonant converter, and a current regulation method thereof. Background Technology

[0002] In a bipolar inverter system, the function of the DC-DC converter is to reverse the voltage polarity and simultaneously transfer power. Typically, the DC-DC converter is a DC-DC resonant converter consisting of a single DC-DC resonant converter circuit. (See also...) Figure 1 ( Figure 1 (This example only uses a three-level resonant converter circuit.)

[0003] When the power of the DC-DC converter is large, the DC-DC converter can be composed of multiple DC-DC resonant converter circuits connected in parallel, such as... Figure 2 ( Figure 2 (This is illustrated using a two-level resonant converter circuit as an example.) However, due to differences in the components of each branch, some resonant converter circuits may experience overload, potentially damaging them and affecting the normal operation of the DC-DC converter.

[0004] Therefore, how to avoid overload in parallel-connected DC resonant converter circuits is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] In view of this, the present invention provides a bipolar inverter system, a DC resonant converter, and a current regulation method thereof, so that the parallel-connected DC resonant converter circuit is overloaded.

[0006] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0007] This application provides a current regulation method for a DC-DC resonant converter, the DC-DC resonant converter comprising: at least two parallel-connected DC-DC resonant converter circuits; the current regulation method for the DC-DC resonant converter comprising:

[0008] Obtain the current on each of the DC resonant converter circuits;

[0009] PWM carrier modulation is applied to each DC resonant converter circuit whose own current is greater than its own preset current until the current on each DC resonant converter circuit is less than or equal to its own preset current.

[0010] The preset current is less than or equal to the maximum carrying current of the corresponding DC resonant converter circuit.

[0011] Optionally, PWM carrier modulation is applied to each of the DC resonant converter circuits whose own current is greater than their own preset current, until the current on each of the DC resonant converter circuits is less than or equal to its own preset current, including:

[0012] Determine whether the current on each of the DC resonant converter circuits is less than or equal to its own preset current;

[0013] If the current on at least one of the DC resonant converter circuits is greater than its own preset current, then PWM carrier adjustment is performed on the corresponding DC resonant converter circuit, and then the process returns to the step of determining whether the current on each DC resonant converter circuit is less than or equal to its own preset current.

[0014] If the current in each of the DC resonant converter circuits is less than or equal to its own preset current, then the current regulation of the DC resonant converter is completed.

[0015] Optionally, PWM carrier modulation is applied to each of the DC resonant converter circuits whose own current is greater than their own preset current, until the current on each of the DC resonant converter circuits is less than or equal to its own preset current, including:

[0016] The DC resonant converter circuits are cyclically adjusted until their own current is less than or equal to their own preset current.

[0017] After completing any adjustment in the cycle process, determine whether the current on each DC resonant converter circuit is less than or equal to its own preset current;

[0018] If the current in at least one of the DC resonant converter circuits is greater than its preset current, then the cyclic process continues.

[0019] If the current in each of the DC resonant converter circuits is less than or equal to its own preset current, then the current regulation of the DC resonant converter is completed.

[0020] Optionally, adjusting the DC resonant converter circuit to a state where its own current is less than or equal to its preset current includes:

[0021] Determine whether the current on the DC resonant converter circuit is less than or equal to its preset current;

[0022] If the current on the DC resonant converter circuit is greater than its own preset current, then PWM carrier adjustment is performed on the DC resonant converter circuit, and then the process returns to the step of determining whether the current on the DC resonant converter circuit is less than or equal to its own preset current.

[0023] If the current on the DC resonant converter circuit is less than or equal to its preset current, then the DC resonant converter circuit is adjusted to a state where its current is less than or equal to its preset current.

[0024] Optionally, the current in the DC resonant converter circuit can be characterized by the resonant current in the resonant cavity of the DC resonant converter circuit.

[0025] Optionally, if the structures of the DC resonant converter circuits are the same but their maximum carrying currents are different, then the preset currents are different and are respectively the maximum carrying currents.

[0026] Optionally, if all the DC resonant converter circuits have the same structure and their respective maximum carrying currents are the same, then the preset currents are the same, which are either the maximum carrying currents or the average value of the sum of the currents on each DC resonant converter circuit.

[0027] Optionally, PWM carrier modulation is performed on the DC resonant converter circuit, including:

[0028] Increase the phase difference between the PWM carrier signal of the DC resonant converter circuit and the previous PWM carrier signal; and / or,

[0029] Increase the frequency of the PWM carrier signal in all of the aforementioned DC resonant converter circuits;

[0030] The preceding PWM carrier signal is a PWM carrier signal whose phase leads that of the DC resonant converter circuit and is adjacent to it.

[0031] Optionally, increasing the phase difference between the PWM carrier signal of the DC resonant converter circuit and the previous PWM carrier signal includes:

[0032] Reduce the phase difference between the PWM carrier signal of each of the other DC resonant converter circuits and their respective preceding PWM carrier signal.

[0033] Optionally, the various currents of the DC resonant converter circuit are characterized by effective values, peak values, or average values.

[0034] A second aspect of this application provides a DC-DC resonant converter, comprising: a controller, at least two DC-DC resonant converter circuits, and at least two current sensors; wherein:

[0035] All of the DC resonant converter circuits are connected in parallel;

[0036] The current sensors are respectively installed at one end of the inductor or capacitor in the resonant cavity of each DC resonant converter circuit;

[0037] The controller is connected to the control terminal of each DC resonant converter circuit and the output terminal of each current sensor, respectively, and is used to execute the current regulation method of the DC resonant converter as described in any of the first aspects of this application.

[0038] Optionally, the DC resonant converter circuit is a two-level resonant converter circuit or a multi-level resonant converter circuit.

[0039] A third aspect of this application provides a bipolar inverter system, comprising: two DC-DC converters, two AC-DC converters, two capacitors, and a system controller; wherein:

[0040] The output of the master DC-DC converter is connected to the input of the slave DC-DC converter.

[0041] The positive output terminal of the main DC-DC converter is connected to the negative output terminal of the slave DC-DC converter in sequence through a first capacitor and a second capacitor.

[0042] The DC side terminals of the main AC converter are connected in parallel between the two ends of the first capacitor, and the DC side terminals of the slave AC converter are connected in parallel between the two ends of the second capacitor.

[0043] The DC-DC converter is a DC-DC resonant converter as described in any of the second aspects of this application;

[0044] The system controller is connected to the control terminals of two DC converters and two AC converters, respectively.

[0045] Optionally, the controller in the DC resonant converter is integrated into the system controller.

[0046] As can be seen from the above technical solution, the present invention provides a current regulation method for a DC resonant converter. This DC resonant converter includes at least two parallel-connected DC resonant converter circuits. Since high-frequency ripple exists in both the input and output of the DC resonant converter circuit, and this high-frequency ripple changes with the PWM carrier wave, adjusting the PWM carrier wave of the DC resonant converter circuit can change the capacitor voltage and inductor voltage in the resonant cavity of the DC resonant converter circuit, thereby changing the current in the DC resonant converter circuit. Furthermore, since this current regulation method adjusts the corresponding resonant converter circuit as described above when the current in at least one DC resonant converter circuit exceeds its own preset current, until the current in each DC resonant converter circuit is less than or equal to its respective preset current, this current regulation method ultimately ensures that the current in each DC resonant converter circuit is less than or equal to its respective preset current, and the corresponding preset current is less than or equal to the maximum carrying current of the corresponding DC resonant converter circuit. Therefore, this current regulation method can ensure that the current in each DC resonant converter circuit is less than or equal to its respective maximum carrying current, thus preventing overload of each resonant converter circuit. Therefore, the current regulation method for the DC resonant converter provided in this application can avoid overload of the parallel-connected DC resonant converter circuits. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0048] Figure 1 and Figure 2 These are schematic diagrams of two existing DC-DC resonant converters.

[0049] Figure 3 A flowchart illustrating one embodiment of the current regulation method for a DC resonant converter provided in this application.

[0050] Figure 4 This is a schematic diagram of the PWM carrier signal for an n-channel DC resonant converter circuit.

[0051] Figure 5 and Figure 6 These are schematic flowcharts illustrating two other implementations of the current regulation method for the DC resonant converter provided in the embodiments of this application.

[0052] Figure 7 A flowchart illustrating a specific example of a current regulation method for a DC-DC resonant converter provided in an embodiment of this application;

[0053] Figure 8 This is a schematic diagram of the structure of a DC-DC resonant converter provided in an embodiment of this application;

[0054] Figure 9 This is a schematic diagram of the structure of a bipolar inverter system provided in an embodiment of this application. Detailed Implementation

[0055] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0056] In this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0057] To prevent overload in parallel-connected DC-DC resonant converter circuits, embodiments of this application provide a current regulation method for a DC-DC resonant converter, wherein, as... Figure 2 As shown, the DC resonant converter includes at least two DC resonant converter circuits, all of which are connected in parallel.

[0058] The conditions can be: each DC resonant converter circuit has the same structure but different maximum current carrying capacity; or each DC resonant converter circuit has the same structure and the same maximum current carrying capacity. No specific limitation is made here, and it can be determined according to the specific situation. Both are within the protection scope of this application.

[0059] The specific process of the current regulation method for this DC resonant converter is as follows: Figure 3 As shown, the specific steps include:

[0060] S110: Obtain the current on each DC resonant converter circuit.

[0061] Typically, the current in a DC-DC resonant converter circuit is characterized by the resonant current in the resonant cavity. In practical applications, this includes, but is not limited to, the specific application; all such applications are within the scope of this application. The resonant cavity, for example... Figure 1 or Figure 2 As shown in 01.

[0062] Specifically, the resonant current can be sampled by placing a current sensor at one end of an inductor or capacitor in the resonant cavity; in practical applications, this is not limited to, but can be determined according to the specific circumstances, and all are within the protection scope of this application.

[0063] S120. PWM carrier adjustment is performed on each DC resonant converter circuit whose own current is greater than its own preset current until the current on each DC resonant converter circuit is less than or equal to its own preset current.

[0064] The preset current of each DC resonant converter circuit is set according to the maximum carrying current of each DC resonant converter circuit. Specifically, the preset current of each DC resonant converter circuit is set to be less than or equal to the maximum overload current of each DC resonant converter circuit.

[0065] PWM carrier modulation is the adjustment of the PWM carrier signal of a DC resonant converter circuit. For example, it can adjust the phase difference between the PWM carrier signals of two connected DC resonant converter circuits. The specific methods of PWM carrier modulation will be explained in detail below, and will not be repeated here.

[0066] Optionally, the various currents of the DC resonant converter circuit can be characterized by their effective values, peak values, or average values; no specific limitation is made here, and the choice can be made depending on the specific circumstances, all of which are within the scope of protection of this application.

[0067] Since high-frequency ripple exists in both the input and output of the DC-DC resonant converter circuit, PWM carrier modulation can change the capacitor voltage and inductor voltage in the resonant cavity, thereby changing the current in the DC-DC resonant converter circuit. Furthermore, since this current regulation method adjusts the corresponding resonant converter circuit as described above when the current in at least one DC-DC resonant converter circuit exceeds its own preset current, until the current in each DC-DC resonant converter circuit is less than or equal to its respective preset current, this current regulation method ultimately ensures that the current in each DC-DC resonant converter circuit is less than or equal to its respective preset current. Since the corresponding preset current is less than or equal to the maximum carrying current of the corresponding DC-DC resonant converter circuit, this current regulation method can guarantee that the current in each DC-DC resonant converter circuit is less than or equal to its respective maximum carrying current, thus preventing overload of any resonant converter circuit. Therefore, the current regulation method for the DC-DC resonant converter provided in this application can avoid overload of parallel-connected DC-DC resonant converter circuits.

[0068] It is worth noting that in the current regulation method of the DC resonant converter provided in this application, PWM carrier regulation is performed on each DC resonant converter circuit whose own current is greater than its own preset current. This can reduce the ripple in the output of the DC resonant converter, thereby reducing the cost of the output capacitor in the DC resonant converter and thus reducing the overall cost of the DC resonant converter.

[0069] Another embodiment of this application provides two specific implementations of the preset current, as detailed below:

[0070] The first implementation method is only applicable to situations where the structures of each DC resonant converter circuit are the same but their maximum carrying currents are different. Specifically, the preset currents of each DC resonant converter circuit are different, namely, the maximum overload current of each DC resonant converter circuit.

[0071] The second implementation method is applicable to situations where the structures of each DC resonant converter circuit are the same and their maximum carrying currents are also the same. Specifically, the preset circuits of each DC resonant converter circuit are the same, which are: the maximum carrying current of the DC resonant converter circuit, or the average value of the sum of the currents on the DC resonant converter circuit.

[0072] When the preset circuits of each DC resonant converter are the same and are all the average value of the sum of the currents on the DC resonant converter, the current regulation method of the DC resonant converter provided in this embodiment can ultimately achieve current sharing of each DC resonant converter connected in parallel, thereby improving the service life of each DC resonant converter connected in parallel, and further protecting each DC resonant converter connected in parallel. Therefore, this embodiment is the preferred embodiment in practical applications.

[0073] The above are only two implementation methods for preset current. In practical applications, there are other methods, including but not limited to these. No specific limitation is made here. The specific method can be determined according to the specific situation. All of them are within the protection scope of this application.

[0074] Another embodiment of this application provides three implementation methods for PWM carrier modulation of a DC resonant converter circuit, as detailed below:

[0075] The first implementation method is as follows: increase the phase difference between the PWM carrier signal of the DC resonant converter circuit and the previous PWM carrier signal; wherein, the previous PWM carrier signal is a PWM carrier signal whose phase leads the PWM carrier signal of the DC resonant converter circuit and is adjacent to it.

[0076] like Figure 4 As shown, PWM1, PWM2, ..., PWMn are the PWM carrier signals of the first, second, ..., nth DC resonant converter circuits, respectively. θ1 is the phase difference between PWM1 and PWMn, and θ2 is the phase difference between PWM2 and PWM1. n Let θn be the phase difference between PWMn and PWMn-1, where θ1 + θ2 + ... + θn-1 n =2π.

[0077] Optionally, the phase difference between the PWM carrier signal of the DC resonant converter circuit and the previous PWM carrier signal can be directly increased, or the phase difference between the PWM carrier signal of each other DC resonant converter circuit and their respective previous PWM carrier signal can be decreased. In practical applications, this includes, but is not limited to, the specific choice here, depending on the specific circumstances, and all are within the scope of protection of this application.

[0078] The second implementation method is to increase the frequency of the PWM carrier signal of the entire DC resonant converter circuit.

[0079] The third implementation method is to increase both the phase difference between the PWM carrier signal of the DC resonant converter circuit and the previous PWM carrier signal, and to increase the frequency of the PWM carrier signal of the entire DC resonant converter circuit.

[0080] It should be noted that the adjustment amount used in the above three implementation methods is very small, so the soft switching characteristics of the switching transistor can be achieved, thereby further reducing losses.

[0081] The above are only three implementation methods for PWM carrier regulation of DC resonant converter circuit. In practical applications, there are other methods, including but not limited to these. No specific limitation is made here. The specific method can be determined according to the specific situation. All of them are within the protection scope of this application.

[0082] Another embodiment of this application provides one implementation of step S120, the specific process of which is as follows: Figure 5 As shown, the specific steps include:

[0083] S210. Determine whether the current on each DC resonant converter circuit is less than or equal to its own preset current.

[0084] If the current in at least one DC resonant converter circuit is greater than its own preset current, then step S220 is executed, and after step S220, the process returns to execute step S210; if the current in each DC resonant converter circuit is less than or equal to its own preset current, then the current regulation of the DC resonant converter is completed.

[0085] S220, Perform PWM carrier adjustment on the corresponding DC resonant converter circuit.

[0086] This embodiment also provides another implementation of step S120, the specific process of which is as follows: Figure 6 As shown, the specific steps include:

[0087] S310, cyclically adjusts each DC resonant converter circuit to a state where its own current is less than or equal to its own preset current.

[0088] One example is adjusting the DC resonant converter circuit to a state where its own current is less than or equal to its preset current (see the detailed process). Figure 7 Specifically:

[0089] Determine whether the current in the DC resonant converter circuit is less than or equal to its preset current.

[0090] If the current in the DC resonant converter circuit is greater than its own preset current, then the DC resonant converter circuit is PWM carrier adjusted, and then the process returns to the step of checking whether the current in the DC resonant converter circuit is less than or equal to its own preset current; if the current in the DC resonant converter circuit is less than or equal to its own preset current, then the process of adjusting the DC resonant converter circuit to a state where its own current is less than or equal to its own preset current is completed.

[0091] S320. After completing any adjustment in the cyclic process, determine whether the current on each DC resonant converter circuit is less than or equal to its own preset current.

[0092] If the current in at least one DC resonant converter circuit is greater than its own preset current, the above cycle process continues; if the current in each DC resonant converter circuit is less than or equal to its own preset current, the current regulation of the DC resonant converter is completed.

[0093] The above are only two specific implementations of step S120. In practical applications, there are other implementations, including but not limited to these. No specific limitation is made here. The implementation can be determined according to the specific circumstances, and all are within the protection scope of this application.

[0094] The following describes in detail the current regulation method of the DC resonant converter provided in this application, taking a DC resonant converter including three parallel-connected DC resonant converter circuits and step S120 using the second implementation method in the above embodiments as an example. The specific process is as follows: Figure 7 ( Figure 7 Taking step S470, which involves judging the current in the third DC resonant converter circuit, as an example, the specific steps are as follows:

[0095] S110: Obtain the current on each DC resonant converter circuit.

[0096] S410. Determine whether the current on the first DC resonant converter circuit is less than or equal to its own preset current.

[0097] If the current in the first DC resonant converter circuit is greater than its own preset current, then step S420 is executed; if the current in the first DC resonant converter circuit is less than or equal to its own preset current, then step S430 is executed.

[0098] S420, Perform PWM carrier adjustment on the first DC resonant converter circuit.

[0099] S430: Determine whether the current on the second DC resonant converter circuit is less than or equal to its own preset current.

[0100] If the current in the second DC resonant converter circuit is greater than its own preset current, then step S440 is executed; if the current in the second DC resonant converter circuit is less than or equal to its own preset current, then step S450 is executed.

[0101] S440, Perform PWM carrier adjustment on the second DC resonant converter circuit.

[0102] S450: Determine whether the current on the third DC resonant converter circuit is less than or equal to its own preset current.

[0103] If the current in the third DC resonant converter circuit is greater than its preset current, then proceed to step S460; if the current in the third DC resonant converter circuit is less than or equal to its preset current, then proceed to step S470.

[0104] S460, PWM carrier adjustment is performed on the third DC resonant converter circuit.

[0105] S470. Determine whether the current on each DC resonant converter circuit is less than or equal to its own preset current.

[0106] If the current in at least one DC resonant converter circuit is greater than its own preset current, then return to step S410; if the current in each DC resonant converter circuit is less than or equal to its own preset current, then the current regulation of the DC resonant converter is completed.

[0107] Another embodiment of this application provides a DC resonant converter, the specific structure of which is as follows: Figure 8 ( Figure 8 In China only Figure 2 As shown in the diagram (based on the existing structure), it specifically includes: a controller 10, at least two DC resonant converter circuits, and at least two current sensors 20; the connection relationships between the components are as follows:

[0108] All DC resonant converter circuits are connected in parallel; current sensors 20 are correspondingly installed at one end of the inductor or capacitor in the resonant cavity of each DC resonant converter circuit; wherein, 01 in the DC resonant converter circuit is its resonant cavity.

[0109] The controller 10 is connected to the control terminal of each DC resonant converter circuit and the output terminal of each current sensor 20, respectively, and is used to execute the current regulation method of the DC resonant converter provided in the above embodiment.

[0110] Optionally, the DC resonant converter circuit can be a multi-level resonant converter circuit, see [reference needed]. Figure 1 ( Figure 1 (This example only uses a three-level resonant converter circuit; it can also be a two-level resonant converter circuit, such as...) Figure 2 As shown; in practical applications, including but not limited to this, no specific limitation is made here, and it can be determined according to the specific situation, all of which are within the protection scope of this application; wherein, the two-level resonant conversion circuit, i.e., its inverter circuit, is a two-level inverter circuit, and the multi-level resonant conversion circuit, i.e., its inverter circuit, is a multi-level inverter circuit.

[0111] Another embodiment of this application provides a bipolar inverter system, the specific structure of which is as follows: Figure 9 As shown, it specifically includes: two DC converters, two AC converters, two capacitors, and a system controller (not shown). Figure 9 (as shown in the figure); wherein, the DC converter 200 is the DC resonant converter provided in the above embodiment.

[0112] The specific connection relationships between the various components are as follows:

[0113] The input terminal of the main DC-DC converter 100 is connected to the photovoltaic string, and the output terminal of the main DC-DC converter 100 is connected to the input terminal of the slave DC-DC converter 200. The positive output terminal of the main DC-DC converter 100 is connected to the negative output terminal of the slave DC-DC converter 200 in sequence through the first capacitor C1 and the second capacitor C2.

[0114] The DC side terminals of the main AC converter 300 are connected in parallel between the two ends of the first capacitor C1, and the DC side terminals of the slave AC converter 400 are connected in parallel between the two ends of the second capacitor C2; the main AC converter 300 and the slave AC converter 400 are communicatively connected; the system controller is connected to the control terminals of the two DC converters and the two AC converters respectively.

[0115] Optionally, the controller in the DC resonant converter is integrated into the system controller; in practical applications, this is not limited to, but is determined according to the specific circumstances, and is within the scope of protection of this application.

[0116] The features described above in the disclosed embodiments can be substituted or combined with each other, enabling those skilled in the art to implement or use this application. The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention's technical solutions still fall within the protection scope of the present invention.

Claims

1. A current regulation method for a DC resonant converter, characterized in that, The DC-DC resonant converter includes: at least two parallel-connected DC-DC resonant converter circuits; the current regulation method of the DC-DC resonant converter includes: Obtain the current on each of the DC resonant converter circuits; PWM carrier modulation is applied to each of the DC resonant converter circuits whose own current is greater than its own preset current until the current on each of the DC resonant converter circuits is less than or equal to its own preset current. The preset current is less than or equal to the maximum carrying current of the corresponding DC resonant converter circuit; The PWM carrier modulation of the DC resonant converter circuit includes: Increase the phase difference between the PWM carrier signal of the DC resonant converter circuit and the previous PWM carrier signal; and / or, Increase the frequency of the PWM carrier signal in all of the aforementioned DC resonant converter circuits; The preceding PWM carrier signal is a PWM carrier signal whose phase leads that of the DC resonant converter circuit and is adjacent to it.

2. The current regulation method for a DC resonant converter according to claim 1, characterized in that, PWM carrier modulation is applied to each of the DC resonant converter circuits whose own current is greater than its own preset current until the current on each of the DC resonant converter circuits is less than or equal to its own preset current, including: Determine whether the current on each of the DC resonant converter circuits is less than or equal to its own preset current; If the current on at least one of the DC resonant converter circuits is greater than its own preset current, then PWM carrier adjustment is performed on the corresponding DC resonant converter circuit, and then the process returns to the step of determining whether the current on each DC resonant converter circuit is less than or equal to its own preset current. If the current in each of the DC resonant converter circuits is less than or equal to its own preset current, then the current regulation of the DC resonant converter is completed.

3. The current regulation method for a DC resonant converter according to claim 1, characterized in that, PWM carrier modulation is applied to each of the DC resonant converter circuits whose own current is greater than its own preset current until the current on each of the DC resonant converter circuits is less than or equal to its own preset current, including: The DC resonant converter circuits are cyclically adjusted until their own current is less than or equal to their own preset current. After completing any adjustment in the cycle process, determine whether the current on each DC resonant converter circuit is less than or equal to its own preset current; If the current in at least one of the DC resonant converter circuits is greater than its preset current, then the cyclic process continues. If the current in each of the DC resonant converter circuits is less than or equal to its own preset current, then the current regulation of the DC resonant converter is completed.

4. The current regulation method for a DC resonant converter according to claim 3, characterized in that, Adjusting the DC resonant converter circuit to a state where its own current is less than or equal to its preset current includes: Determine whether the current on the DC resonant converter circuit is less than or equal to its preset current; If the current on the DC resonant converter circuit is greater than its own preset current, then PWM carrier adjustment is performed on the DC resonant converter circuit, and then the process returns to the step of determining whether the current on the DC resonant converter circuit is less than or equal to its own preset current. If the current on the DC resonant converter circuit is less than or equal to its preset current, then the DC resonant converter circuit is adjusted to a state where its current is less than or equal to its preset current.

5. The current regulation method for a DC resonant converter according to any one of claims 1 to 4, characterized in that, The resonant current on the resonant cavity in the DC resonant converter circuit is used to characterize the current in the DC resonant converter circuit.

6. The current regulation method for a DC resonant converter according to any one of claims 1 to 4, characterized in that, If the structures of the DC resonant converter circuits are the same but their maximum carrying currents are different, then the preset currents are different and are respectively the maximum carrying currents.

7. The current regulation method for a DC resonant converter according to any one of claims 1 to 4, characterized in that, If all the DC resonant converter circuits have the same structure and their respective maximum carrying currents are the same, then the preset currents are the same, which are either the maximum carrying currents or the average value of the sum of the currents on each DC resonant converter circuit.

8. The current regulation method for a DC resonant converter according to claim 1, characterized in that, Increasing the phase difference between the PWM carrier signal of the DC resonant converter circuit and the previous PWM carrier signal includes: Reduce the phase difference between the PWM carrier signal of each of the other DC resonant converter circuits and their respective preceding PWM carrier signal.

9. The current regulation method for a DC resonant converter according to any one of claims 1 to 4, characterized in that, All currents in the DC resonant converter circuit are characterized by effective value, peak value, or average value.

10. A DC resonant converter, characterized in that, include: The controller, at least two DC-DC resonant converter circuits, and at least two current sensors; wherein: All of the DC resonant converter circuits are connected in parallel; The current sensors are respectively installed at one end of the inductor or capacitor in the resonant cavity of each DC resonant converter circuit; The controller is connected to the control terminal of each DC resonant converter circuit and the output terminal of each current sensor, and is used to execute the current regulation method of the DC resonant converter as described in any one of claims 1 to 9.

11. The DC-DC resonant converter according to claim 10, characterized in that, The DC resonant converter circuit is a two-level resonant converter circuit or a multi-level resonant converter circuit.

12. A bipolar inverter system, characterized in that, include: Two DC-DC converters, two AC-DC converters, two capacitors, and a system controller; wherein: The output of the master DC-DC converter is connected to the input of the slave DC-DC converter. The positive output terminal of the main DC-DC converter is connected to the negative output terminal of the slave DC-DC converter in sequence through a first capacitor and a second capacitor. The two terminals of the DC side of the main AC converter are connected in parallel between the two ends of the first capacitor, and the two terminals of the DC side of the AC converter are connected in parallel between the two ends of the second capacitor. The DC-DC converter is the DC-DC resonant converter as described in claim 10 or 11; The system controller is connected to the control terminals of two DC converters and two AC converters, respectively.

13. The bipolar inverter system according to claim 12, characterized in that, The controller in the DC resonant converter is integrated into the system controller.

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