Power sharing control method of multi-module converter

Abstract

The invention provides a power sharing control method for a multi-module converter, and the method comprises the steps: obtaining a voltage observation value of a target multi-module converter and an actual input voltage of the target multi-module converter for calculation, and obtaining a control phase shift angle; obtaining a voltage observation value of the current sub-module and voltage observation values of all sub-modules adjacent to the current sub-module, performing calculation, obtaining a difference between an obtained voltage observation extreme value and the voltage observation value of the current sub-module, obtaining a compensation phase shift angle, performing superposition on the compensation phase shift angle and the control phase shift angle, and obtaining an input voltage control phase shift angle; calculating an output voltage value and an output voltage reference value of the target multi-module converter to obtain an output voltage control phase shift angle; and subtracting the output voltage control phase-shifting angle from the input voltage control phase-shifting angle to obtain a control phase-shifting angle of the target multi-module converter so as to perform power equalization on the target multi-module converter, thereby solving the problem of power imbalance caused by single-point fault risk and loop interference in centralized control.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronic converters, and in particular to a power sharing control method for a multi-module converter. Background Art

[0002] In high-power, high-input voltage DC microgrids and energy storage applications, multi-module DC-DC bidirectional isolation converters are often used to achieve intermediate power conversion. However, due to the different impedances and parameter mismatches between sub-module converters, power imbalance may occur, which in turn affects the efficiency of the entire system and the service life of the device.

[0003] To solve the problem of power imbalance, existing methods usually use centralized control to perform dual-loop control on input voltage and output voltage. However, this method has the risk of single-point failure. Once one of the converters fails, the entire system will collapse. At the same time, multiple loops will interfere with each other, and the power sharing effect will also be affected. Summary of the invention

[0004] The present invention provides a power sharing control method for a multi-module converter, the purpose of which is to solve the power imbalance problem caused by the risk of single-point failure and loop interference in centralized control.

[0005] In order to achieve the above object, the present invention provides a power sharing control method for a multi-module converter, comprising:

[0006] Step 1, obtaining a voltage observation value of a target multi-module converter, and calculating using the voltage observation value and an actual input voltage of the target multi-module converter to obtain a control phase shift angle;

[0007] Step 2, through the communication between submodules in the target multi-module converter, the voltage observation value of the current submodule and the voltage observation values ​​of all submodules adjacent to the current submodule are obtained and calculated to obtain the voltage observation extreme value corresponding to each voltage observation value;

[0008] Step 3, obtaining a compensation phase shift angle by subtracting the voltage observation extreme values ​​of all submodules adjacent to the current submodule from the voltage observation value of the current submodule;

[0009] Step 4, superimposing the control phase shift angle and the compensation phase shift angle to obtain the input voltage control phase shift angle;

[0010] Step 5, calculating the output voltage value and the output voltage reference value of the target multi-module converter to obtain the output voltage control phase shift angle;

[0011] Step 6: Subtract the output voltage control phase shift angle from the input voltage control phase shift angle to obtain the control phase shift angle of the target multi-module converter, so as to be used for power sharing of the target multi-module converter.

[0012] Specifically, the target multi-module converter is composed of multiple sub-modules communicating with each other, each of which includes:

[0013] Input capacitor, first switch tube, second switch tube, third switch tube, fourth switch tube, fifth switch tube, sixth switch tube, seventh switch tube, eighth switch tube, resonant inductor, transformer, load capacitor;

[0014] The first end of the input capacitor in the first submodule is respectively connected to the positive end of the DC bus, the drain of the first switch tube, and the drain of the third switch tube. The second end of the input capacitor in the first submodule is respectively connected to the source of the second switch tube and the source of the fourth switch tube. The source of the first switch tube is connected to the drain of the second switch tube to form a first bridge arm. The midpoint of the first bridge arm is connected to the first end of the resonant inductor, and the second end of the resonant inductor is connected to the first end of the transformer. The source of the third switch tube is connected to the drain of the fourth switch tube to form a second bridge arm. The midpoint of the second bridge arm is connected to the second end of the transformer. The drain of the fifth switch tube is respectively connected to the drain of the seventh switch tube and the first end of the load capacitor. The source of the fifth switch tube is connected to the drain of the sixth switch tube to form a third bridge arm. The midpoint of the third bridge arm is connected to the fourth end of the transformer. The source of the sixth switch tube is connected to the source of the eighth switch tube and the second end of the load capacitor. The source of the seventh switch tube is connected to the drain of the eighth switch tube to form a fourth bridge arm. The midpoint of the fourth bridge arm is connected to the third end of the transformer.

[0015] The first end of the input capacitor in each submodule except the first submodule is connected to the second end of the input capacitor in the previous submodule;

[0016] The second end of the input capacitor in the last submodule is connected to the negative end of the DC bus;

[0017] The first ends of the load capacitors in all the submodules are connected to the positive terminal of the load, and the second ends of the load capacitors in all the submodules are connected to the negative terminal of the load.

[0018] More specifically, step 1 includes:

[0019] The voltage observation value of the target multi-module converter is obtained as follows:

[0020]

[0021] Among them, V ini (t) represents the input voltage of the ith submodule, V prei(t) represents the voltage observation value of the ith submodule, V prej (t) represents the voltage observation value of the jth submodule, a ij Represents the communication weight between submodules;

[0022] The calculation expression of the control phase shift angle is obtained by using the voltage observation value and the actual input voltage of the target multi-module converter:

[0023] d a =k ip (V prei -V ini )+k ii ∫(V prei -V ini )

[0024] Among them, d a represents the control phase shift angle, k ip represents the proportionality coefficient, k ii Represents the integral coefficient.

[0025] Furthermore, the voltage observation extreme values ​​corresponding to each voltage observation value include the voltage observation maximum value and the voltage observation minimum value, and the calculation expression is:

[0026]

[0027] Among them, V j represents the voltage observation value of the jth submodule adjacent to the current submodule, V maxj Indicates the maximum value of voltage observation, v minj Indicates the observed minimum voltage value.

[0028] More specifically, step 3 includes:

[0029] When the voltage observation value of the current submodule is less than the voltage observation values ​​of all the submodules adjacent to the current submodule, the voltage observation minimum value is subtracted from the voltage observation value of the current submodule to obtain the compensation phase shift angle:

[0030] d c =k×(V minj -V prei ), V prei <V j

[0031] When the voltage observation value of the current submodule is greater than the voltage observation values ​​of all the submodules adjacent to the current submodule, the voltage observation maximum value is subtracted from the voltage observation value of the current submodule to obtain the compensation phase shift angle:

[0032] d c =k×(V maxj -vprei ), V prei >V j

[0033] Where k represents the dynamic compensation coefficient, d c Indicates the compensation phase shift angle.

[0034] Furthermore, the control phase shift angle and the compensation phase shift angle are superimposed to obtain the input voltage control phase shift angle:

[0035] d1=d a +d c

[0036] Where d1 represents the input voltage control phase shift angle, d a represents the control phase shift angle, d c Indicates the compensation phase shift angle.

[0037] Specifically, the output voltage controller is:

[0038]

[0039] Where d2 represents the output voltage control phase shift angle, Represents the output voltage reference value of the target multi-module converter, V o represents the output voltage value of the target multi-module converter, k op Indicates the proportional coefficient of the output voltage control link, k oi Represents the integral coefficient of the output voltage control link.

[0040] Furthermore, the output voltage control phase shift angle is subtracted from the input voltage control phase shift angle to obtain the control phase shift angle of the target multi-module converter:

[0041] d=d2-d1

[0042] Wherein, d represents the control phase shift angle of the target multi-module converter, d2 represents the output voltage control phase shift angle, and d1 represents the input voltage control phase shift angle.

[0043] The above scheme of the present invention has the following beneficial effects:

[0044] The present invention obtains the voltage observation value of the target multi-module converter; uses the voltage observation value and the actual input voltage of the target multi-module converter to calculate and obtain the control phase shift angle; obtains the voltage observation value of the current submodule and the voltage observation values ​​of all submodules adjacent to the current submodule and calculates to obtain the voltage observation extreme value; subtracts the voltage observation extreme value from the voltage observation value of the current submodule to obtain the compensation phase shift angle and superimposes it with the control phase shift angle to obtain the input voltage control phase shift angle; calculates the output voltage value and the output voltage reference value of the target multi-module converter to obtain the output voltage control phase shift angle ; Subtract the output voltage control phase shift angle from the input voltage control phase shift angle to obtain the control phase shift angle of the target multi-module converter, which is used to share power equally for the target multi-module converter; Compared with the prior art, the present invention regards each sub-module in the target multi-module converter as an intelligent entity, and realizes quasi-global information sharing through communication between sub-modules in the target multi-module converter, thereby solving the single-point failure risk and loop interference problems in centralized control, and dynamically compensates the target multi-module converter through the input voltage control phase shift angle and the output voltage control phase shift angle to achieve power balancing regulation.

[0045] Other beneficial effects of the present invention will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic diagram of a flow chart of an embodiment of the present invention;

[0047] Figure 2 A control block diagram provided by an embodiment of the present invention;

[0048] Figure 3 A topological structure diagram of a submodule in an embodiment of the present invention;

[0049] Figure 4 The working waveform diagram of the submodule in the embodiment of the present invention;

[0050] Figure 5 A topological structure diagram of a multi-module converter according to an embodiment of the present invention;

[0051] Figure 6 A communication connection diagram of each submodule in the target multi-module converter;

[0052] Figure 7 It is the voltage waveform diagram of each submodule in steady-state operation;

[0053] Figure 8 The voltage waveform of each submodule when the load changes suddenly;

[0054] Fig. 9 It is the voltage waveform of each submodule when the input voltage changes suddenly. DETAILED DESCRIPTION

[0055] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0057] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a locking connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0059] In view of the existing problems, the present invention provides a power sharing control method for a multi-module converter.

[0060] like Figure 1 , Figure 2 As shown, an embodiment of the present invention provides a power sharing control method for a multi-module converter, comprising:

[0061] Step 1, obtaining a voltage observation value of a target multi-module converter, and calculating using the voltage observation value and an actual input voltage of the target multi-module converter to obtain a control phase shift angle;

[0062] Step 2, through the communication between submodules in the target multi-module converter, the voltage observation value of the current submodule and the voltage observation values ​​of all submodules adjacent to the current submodule are obtained and calculated to obtain the voltage observation extreme value corresponding to each voltage observation value;

[0063] Step 3, obtaining a compensation phase shift angle by subtracting the voltage observation extreme values ​​of all submodules adjacent to the current submodule from the voltage observation value of the current submodule;

[0064] Step 4, superimposing the control phase shift angle and the compensation phase shift angle to obtain the input voltage control phase shift angle;

[0065] Step 5, calculating the output voltage value and the output voltage reference value of the target multi-module converter to obtain the output voltage control phase shift angle;

[0066] Step 6: Subtract the output voltage control phase shift angle from the input voltage control phase shift angle to obtain the control phase shift angle of the target multi-module converter, so as to be used for power sharing of the target multi-module converter.

[0067] Most preferably, the target multi-module converter is composed of a plurality of sub-modules communicating with each other, each sub-module being Figure 3 As shown, all include:

[0068] Input Capacitor C in , a first switch tube S1, a second switch tube S2, a third switch tube S3, a fourth switch tube S4, a fifth switch tube S5, a sixth switch tube S6, a seventh switch tube S7, an eighth switch tube S8, a resonant inductor L1, a transformer, and a load capacitor C o ;

[0069] The input capacitor C in the first submodule in The first end of the first submodule is connected to the positive end of the DC bus, the drain of the first switch tube S1, and the drain of the third switch tube S3. in The second end of is connected to the source of the second switch tube S2 and the source of the fourth switch tube S4 respectively, the source of the first switch tube S1 is connected to the drain of the second switch tube S2 to form a first bridge arm, the midpoint of the first bridge arm is connected to the first end of the resonant inductor L1, the second end of the resonant inductor L1 is connected to the first end of the transformer, the source of the third switch tube S3 is connected to the drain of the fourth switch tube S4 to form a second bridge arm, the midpoint of the second bridge arm is connected to the second end of the transformer, the drain of the fifth switch tube S5 is connected to the drain of the seventh switch tube S7 and the load capacitor C o The source of the fifth switch tube S5 is connected to the drain of the sixth switch tube S6 to form a third bridge arm. The midpoint of the third bridge arm is connected to the fourth end of the transformer. The source of the sixth switch tube S6 is connected to the source of the eighth switch tube S8 and the load capacitor C o The source of the seventh switch tube S7 and the drain of the eighth switch tube S8 are connected to form a fourth bridge arm, and the midpoint of the fourth bridge arm is connected to the third end of the transformer;

[0070] The input capacitor C in each submodule except the first submodule m The first end is connected to the input capacitor C in the previous submodule. m The second end of the connection;

[0071] The input capacitor C in the last submodule m The second end is connected to the negative end of the DC bus;

[0072] The load capacitance C of all submodules o The first end of each submodule is connected to the positive terminal of the load. The load capacitor C o The second ends of the capacitors are connected to the negative terminal of the load.

[0073] It should be noted that the submodule is a dual-active full-bridge converter. During operation, the number of submodules can be increased or decreased according to actual needs, and plug-and-play can be achieved.

[0074] The dual-active full-bridge converter adopts single-phase shift control. The upper and lower switches of each bridge arm of the primary and secondary full-bridge circuits are complementary and turned on, with a duty cycle of 50%. The driving signals of the two diagonally opposite switches in each full-bridge circuit are the same, that is, they are turned on and off at the same time. That is, by controlling the midpoint voltage v of the two bridge arms of the primary and secondary full-bridge circuits AB and v CD The size of the phase shift angle between them is used to control the direction and size of power transfer, thereby generating corresponding PWM signals to control each switch tube. The working waveform is as follows Figure 4 As shown, the phase shift angle is d.

[0075] The target multi-module converter provided in the embodiment of the present invention is an input parallel output parallel (ISOP) DC-DC converter. When it works in a steady state, the input current and output voltage of each submodule are the same. In order to prove that as long as the input voltage between each module is balanced, the power sharing between modules can be achieved, the power relationship of each submodule is constructed as follows:

[0076]

[0077] Among them, V in1 、V in2 、V inN Respectively represent the input voltage of the 1st, 2nd, and Nth submodules, I in1 ,I in2 ,I inN Respectively represent the input current of the 1st, 2nd, and Nth submodules, P in1 , P in2 , P inNRespectively represent the input power of the 1st, 2nd, and Nth submodules, I o1 ,I o2 ,I oN Respectively represent the output current of the 1st, 2nd, and Nth submodules, P o1 , P o2 , P oN Respectively represent the output power of the 1st, 2nd, and Nth submodules, V o Represents the output voltage of each submodule. When V in1 =V in2 =V inN When o1 =I o2 =I oN At this time, since the outputs are connected in parallel in the ISOP structure, power sharing among multiple modules can be achieved.

[0078] Specifically, step 1 includes:

[0079] The voltage observation value of the target multi-module converter is obtained as follows:

[0080]

[0081] Among them, V ini (t) represents the input voltage of the ith dual-active full-bridge converter submodule, V prei (t) represents the voltage observation value of the i-th dual-active full-bridge converter submodule, V prej (t) represents the voltage observation value of the jth dual-active full-bridge converter submodule, a ij Represents the communication weight between submodules;

[0082] The calculation expression of the control phase shift angle is obtained by using the voltage observation value and the actual input voltage of the target multi-module converter:

[0083] d a =k ip (V prei -V ini )+k ii ∫(V prei -V ini ) (3)

[0084] Among them, d a represents the control phase shift angle, k ip represents the proportionality coefficient, k ii Represents the integral coefficient.

[0085] The embodiment of the present invention designs an average voltage observer based on a consistency algorithm, and obtains the voltage observation value of the target multi-module converter through the average voltage observer. In steady state, the voltage observation value output by the average voltage observer eventually converges to the average value of the input voltages of all sub-modules, and the expression is:

[0086]

[0087] Where N represents the number of submodules.

[0088] In the embodiment of the present invention, the voltage observation value and the actual input voltage of the target multi-module converter are used to calculate and obtain the control phase shift angle based on the designed input voltage sharing controller, and the input voltage sharing controller is d a =k ip (V prei -V ini )+k ii ∫(V prei -V ini ), k ip represents the proportional coefficient of the input voltage sharing controller, k ii Represents the integral coefficient of the input voltage sharing controller.

[0089] In the embodiment of the present invention, the ith submodule can obtain the voltage observation values ​​of all its adjacent submodules through communication between submodules, which is recorded as V j , j = 1, 2, ..., n, n is the number of adjacent submodules;

[0090] Then, the current voltage observation value of the i-th submodule and the extreme value of the voltage observation value of the adjacent submodule are calculated by the following formula and the expression of the average voltage observer.

[0091] Specifically, the voltage observation extreme values ​​corresponding to each voltage observation value include the voltage observation maximum value and the voltage observation minimum value, and the calculation expression is:

[0092]

[0093] Among them, V j represents the voltage observation value of the jth submodule adjacent to the current submodule, V maxj Indicates the maximum value of voltage observation, V minj Indicates the observed minimum voltage value.

[0094] In order to prevent the large oscillation caused by excessive compensation amount and deterioration of the converter dynamic control process, the embodiment of the present invention proposes to make a difference between the voltage observation maximum or minimum value of all submodules adjacent to the i-th submodule and the voltage observation value of the i-th submodule to find the minimum compensation amount for each control cycle. The specific process is as follows:

[0095] When the voltage observation value of the current submodule is less than the voltage observation values ​​of all the submodules adjacent to the current submodule, the voltage observation minimum value is subtracted from the voltage observation value of the current submodule to obtain the compensation phase shift angle:

[0096] d c =k×(V minj -V prei ), V prei <V j (6)

[0097] When the voltage observation value of the current submodule is greater than the voltage observation values ​​of all the submodules adjacent to the current submodule, the voltage observation maximum value is subtracted from the voltage observation value of the current submodule to obtain the compensation phase shift angle:

[0098] d c =k×(V maxj -V prei ), V prei >V j (7)

[0099] Where k represents the dynamic compensation coefficient, d c Indicates the compensation phase shift angle.

[0100] In summary, the expression of compensation phase shift angle is:

[0101]

[0102] Specifically, the control phase shift angle and the compensation phase shift angle are superimposed to obtain the input voltage control phase shift angle:

[0103] d1=d a +d c (9)

[0104] Where d1 represents the input voltage control phase shift angle, d a represents the control phase shift angle, d c Indicates the compensation phase shift angle.

[0105] In addition, in order to ensure the stability of the output voltage, an output voltage controller needs to be designed to ensure that the output voltage is stable at the expected value.

[0106] Specifically, the output voltage control phase shift angle is calculated by the output voltage controller, and the expression of the output voltage controller is:

[0107]

[0108] Where d2 represents the output voltage control phase shift angle, Represents the output voltage reference value of the target multi-module converter, Vo represents the output voltage value of the target multi-module converter, k op Indicates the proportional coefficient of the output voltage control link, k oi Represents the integral coefficient of the output voltage control link.

[0109] Specifically, the output voltage control phase shift angle is subtracted from the input voltage control phase shift angle to obtain the control phase shift angle of the target multi-module converter:

[0110] d=d2-d1 (11)

[0111] Wherein, d represents the control phase shift angle of the target multi-module converter, d2 represents the output voltage control phase shift angle, and d1 represents the input voltage control phase shift angle.

[0112] According to the above control method, the embodiment of the present invention uses Matlab / Simulink simulation software to build a target multi-module converter consisting of three dual-active full-bridge converter sub-modules to verify the proposed method. The topology diagram is shown in FIG. Figure 5 As shown, the first end of the input capacitor in submodule 1 is respectively connected to the positive end of the DC bus, the drain of the first switch tube, and the drain of the third switch tube, the second end of the input capacitor in submodule 1 is respectively connected to the source of the second switch tube and the source of the fourth switch tube, the source of the first switch tube is connected to the drain of the second switch tube to form a first bridge arm, the midpoint of the first bridge arm is connected to the first end of the resonant inductor, the second end of the resonant inductor is connected to the first end of the transformer, the source of the third switch tube is connected to the drain of the fourth switch tube to form a second bridge arm, the midpoint of the second bridge arm is connected to the second end of the transformer, the drain of the fifth switch tube is respectively connected to the drain of the seventh switch tube and the first end of the load capacitor, and the fifth switch tube The source of the sixth switch tube is connected to the drain of the sixth switch tube to form a third bridge arm, the midpoint of the third bridge arm is connected to the fourth end of the transformer, the source of the sixth switch tube is connected to the source of the eighth switch tube and the second end of the load capacitor, the source of the seventh switch tube is connected to the drain of the eighth switch tube to form a fourth bridge arm, and the midpoint of the fourth bridge arm is connected to the third end of the transformer; the first end of the input capacitor in submodule 2 is connected to the second end of the input capacitor in submodule 1; the second end of the input capacitor in submodule 3 is connected to the negative end of the DC bus; the first end of the load capacitor in submodules 1, 2, and 3 is connected to the positive end of the load, and the second end of the load capacitor in submodules 1, 2, and 3 is connected to the negative end of the load, and the communication connection is as follows Figure 6 The basic parameters are shown in Table 1 below:

[0113] Table 1

[0114] symbol parameter Numeric <![CDATA[V in ]]> Total input voltage 600V <![CDATA[V o ]]> Output voltage 100V <![CDATA[f S ]]> Switching frequency 100kHz K Turns ratio 2∶1 <![CDATA[P o ]]> Rated Power 100W

[0115] 1. Steady-state operation

[0116] According to the above description, when the input voltage is evenly divided, the function can be evenly divided. Therefore, it is possible to determine whether the power is evenly divided by observing whether the input voltages of the three submodules are evenly divided in steady state.

[0117] In order to verify whether the proposed control method can ensure power sharing in steady state, the proposed control method is applied to the target multi-module converter built with Matlab / Simulink simulation software. The experimental results are shown in Figure 2. Figure 7 As shown, from Figure 7 (a) It can be seen that when the proposed control method intervenes, the target multi-module converter responds quickly and adjusts, and the input voltage is evenly divided among the three modules in a very short time, and there is almost no error, which shows that the proposed method has good steady-state performance and dynamic performance. Figure 7 (b) It can be seen that the output voltage is also adjusted to the reference value of 100V. Combining the two figures, it can be seen that the proposed control method achieves good power sharing performance.

[0118] 2. Load Sudden Change

[0119] like Figure 8 The power sharing performance of the proposed method is demonstrated when the load changes suddenly. Figure 8 In (a), the load switches from 20Ω to 10Ω at 0.04s. It can be seen that the system responds quickly and completes the input voltage equalization adjustment with minimal overshoot. Figure 8 In (b), the load is switched from 10Ω to 20Ω. Figure 8 (a) is similar, and input voltage equalization is achieved with extremely small overshoot and adjustment time, that is, power equalization is achieved.

[0120] 3. Input voltage changes suddenly

[0121] exist Fig. 9 When the total input voltage suddenly changes from 600V to 630V, the waveform of the input voltage of each submodule is as follows Fig. 9 (a), and then recover from 630V to 600V. The waveform of the input voltage of each submodule is as follows: Fig. 9 As shown in (b), under the proposed control method, the input voltage allocated to each module also changes suddenly, and finally the input voltage is evenly distributed, that is, the power is evenly distributed.

[0122] The embodiment of the present invention obtains the voltage observation value of the target multi-module converter; uses the voltage observation value and the actual input voltage of the target multi-module converter to calculate and obtain the control phase shift angle; obtains the voltage observation value of the current submodule and the voltage observation values ​​of all submodules adjacent to the current submodule and calculates to obtain the voltage observation extreme value; subtracts the voltage observation extreme value from the voltage observation value of the current submodule to obtain the compensation phase shift angle and superimposes it with the control phase shift angle to obtain the input voltage control phase shift angle; calculates the output voltage value and the output voltage reference value of the target multi-module converter to obtain the output voltage control phase shift angle ; Subtract the output voltage control phase shift angle from the input voltage control phase shift angle to obtain the control phase shift angle of the target multi-module converter, which is used to share power equally for the target multi-module converter; Compared with the prior art, the embodiment of the present invention regards each sub-module in the target multi-module converter as an intelligent entity, and realizes quasi-global information sharing through communication between sub-modules in the target multi-module converter, thereby solving the single-point failure risk and loop interference problems in centralized control, and dynamically compensates the target multi-module converter through the input voltage control phase shift angle and the output voltage control phase shift angle to achieve power balancing regulation.

[0123] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A power sharing control method for a multi-module converter, characterized in that: include: Step 1, obtaining a voltage observation value of a target multi-module converter, and using the voltage observation value and an actual input voltage of the target multi-module converter to perform calculation to obtain a control phase shift angle; Step 2, through the communication between submodules in the target multi-module converter, the voltage observation value of the current submodule and the voltage observation values ​​of all submodules adjacent to the current submodule are obtained and calculated to obtain the voltage observation extreme value corresponding to each voltage observation value; Step 3, obtaining a compensation phase shift angle by subtracting the voltage observation extreme values ​​of all submodules adjacent to the current submodule from the voltage observation value of the current submodule; Step 4, superimposing the control phase shift angle and the compensation phase shift angle to obtain an input voltage control phase shift angle; Step 5, calculating the output voltage value and the output voltage reference value of the target multi-module converter to obtain an output voltage control phase shift angle; Step 6: Subtract the output voltage control phase shift angle from the input voltage control phase shift angle to obtain the control phase shift angle of the target multi-module converter, so as to perform power sharing on the target multi-module converter.

2. The power sharing control method of a multi-module converter according to claim 1, characterized in that: The target multi-module converter is composed of a plurality of sub-modules communicating with each other, each of which comprises: Input capacitor, first switch tube, second switch tube, third switch tube, fourth switch tube, fifth switch tube, sixth switch tube, seventh switch tube, eighth switch tube, resonant inductor, transformer, load capacitor; The first end of the input capacitor in the first submodule is respectively connected to the positive end of the DC bus, the drain of the first switch tube, and the drain of the third switch tube, the second end of the input capacitor in the first submodule is respectively connected to the source of the second switch tube and the source of the fourth switch tube, the source of the first switch tube is connected to the drain of the second switch tube to form a first bridge arm, the midpoint of the first bridge arm is connected to the first end of the resonant inductor, the second end of the resonant inductor is connected to the first end of the transformer, the source of the third switch tube is connected to the drain of the fourth switch tube to form a second a bridge arm, wherein the midpoint of the second bridge arm is connected to the second end of the transformer, the drain of the fifth switch tube is respectively connected to the drain of the seventh switch tube and the first end of the load capacitor, the source of the fifth switch tube is connected to the drain of the sixth switch tube to form a third bridge arm, the midpoint of the third bridge arm is connected to the fourth end of the transformer, the source of the sixth switch tube is connected to the source of the eighth switch tube and the second end of the load capacitor, the source of the seventh switch tube is connected to the drain of the eighth switch tube to form a fourth bridge arm, and the midpoint of the fourth bridge arm is connected to the third end of the transformer; The first end of the input capacitor in each submodule except the first submodule is connected to the second end of the input capacitor in the previous submodule; The second end of the input capacitor in the last submodule is connected to the negative terminal of the DC bus; The first ends of the load capacitors in all the submodules are connected to the positive terminal of the load, and the second ends of the load capacitors in all the submodules are connected to the negative terminal of the load.

3. The power sharing control method of a multi-module converter according to claim 2, characterized in that: The step 1 comprises: The voltage observation value of the target multi-module converter is obtained as follows: Among them, V ini (t) represents the input voltage of the ith submodule, V prei (t) represents the voltage observation value of the i-th submodule, V prej (t) represents the voltage observation value of the jth submodule, a ij Represents the communication weight between submodules; The voltage observation value and the actual input voltage of the target multi-module converter are used to calculate, and the calculation expression of the control phase shift angle is obtained as follows: d a =k ip (V prei -V ini )+k ii ∫(V prei -V ini ) Among them, d a represents the control phase shift angle, k ip represents the proportionality coefficient, k ii Represents the integral coefficient.

4. The power sharing control method of a multi-module converter according to claim 3, characterized in that: The voltage observation extreme values ​​corresponding to each voltage observation value include the voltage observation maximum value and the voltage observation minimum value, and the calculation expression is: Among them, V j represents the voltage observation value of the jth submodule adjacent to the current submodule, V maxj Indicates the maximum value of voltage observation, V minj Indicates the observed minimum voltage value.

5. The power sharing control method of a multi-module converter according to claim 4, characterized in that: The step 3 comprises: When the voltage observation value of the current submodule is less than the voltage observation values ​​of all the submodules adjacent to the current submodule, the voltage observation minimum value is subtracted from the voltage observation value of the current submodule to obtain the compensation phase shift angle: d c =k×(V minj -V prei ),V prei <V j When the voltage observation value of the current submodule is greater than the voltage observation values ​​of all the submodules adjacent to the current submodule, the voltage observation maximum value is subtracted from the voltage observation value of the current submodule to obtain the compensation phase shift angle: d c =k×(V maxj -V prei ),V prei >V j Where k represents the dynamic compensation coefficient, d c Indicates the compensation phase shift angle.

6. The power sharing control method of a multi-module converter according to claim 5, characterized in that: The control phase shift angle is superimposed on the compensation phase shift angle to obtain the input voltage control phase shift angle: d1=d a +d c Where d1 represents the input voltage control phase shift angle, d a represents the control phase shift angle, d c Indicates the compensation phase shift angle.

7. The power sharing control method of a multi-module converter according to claim 6, characterized in that: The output voltage control phase shift angle is: Where d2 represents the output voltage control phase shift angle, Represents the output voltage reference value of the target multi-module converter, V o represents the output voltage value of the target multi-module converter, k op Indicates the proportional coefficient of the output voltage control link, k oi Represents the integral coefficient of the output voltage control link.

8. The power sharing control method of a multi-module converter according to claim 7, characterized in that: The output voltage control phase shift angle is subtracted from the input voltage control phase shift angle to obtain the control phase shift angle of the target multi-module converter: d=d2-d1 Wherein, d represents the control phase shift angle of the target module converter, d2 represents the output voltage control phase shift angle, and d1 represents the input voltage control phase shift angle.

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