CN110277927B - Energy storage type multi-level converter topology and battery charge state regulation method - Google Patents

Abstract

The invention provides an energy storage type multi-level converter topology and a battery state of charge regulation method, and relates to the technical field of battery energy storage. The multi-level converter topology comprises a battery pack string formed by connecting 5 battery packs in series; 5 capacitors are connected in series to form a capacitor string; the battery pack string is connected with the capacitor string in parallel; each converter all includes 50 IGBT pipes and rather than anti-parallelly connected diodes, and 3 converters are connected with the positive negative pole parallel connection of battery group cluster. The IGBT gate pole of each converter has 6 different switch states according to different modulation strategies; meanwhile, the invention also provides a method for adjusting the battery charge state in the energy storage type multilevel converter topology by adjusting the duty ratio of the converter IGBT tube after compensation, so that the charge state of each battery pack is adjusted to be consistent. The topology and the method of the invention reduce the maximum energy loss of a single switch tube, improve the reliability of energy storage operation and greatly save the economic cost of an energy storage power station.

Description

An energy storage type multilevel converter topology and battery state of charge regulation method

technical field

The invention relates to the technical field of battery energy storage, in particular to an energy storage type multilevel converter topology and a battery state of charge regulation method.

Background technique

Battery energy storage technology is now widely used in many fields, from the integration of new energy generation to the grid to improve the reliability of power system operation, energy storage technology has played an irreplaceable role. Compared with traditional small and medium-scale battery energy storage, ultra-large-scale battery energy storage, With the advantages of sufficient peak shaving and valley filling capacity, and strong transient voltage support capability, some problems existing in ultra-large-scale battery energy storage at this stage have become the research hotspots of domestic and foreign university scholars.

The converters used in the ultra-large-scale battery energy storage power station are all high-power high-voltage converters. After receiving the control signal, the switch tube of the converter performs on and off actions, resulting in turn-on loss and turn-off loss. Since the switching frequency of switching devices is usually above the megahertz level, the power loss of switching devices cannot be ignored. A multilevel converter topology suitable for ultra-large-scale battery energy storage power stations.

In order to reduce the construction cost and maintenance cost of ultra-large-scale battery energy storage power stations, battery packs of different types and states of charge are often connected in series. If the battery pack is regulated by the state of charge, the capacity of all battery packs will be limited by the battery pack with the fastest capacity exhaustion, which greatly affects the reliability and economy of the energy storage power station. To this end, an effective method is required to adjust the state of charge of battery packs of different models and states of charge to be consistent.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to aim at the deficiencies of the above-mentioned prior art, and to provide an energy storage type multilevel converter topology and a battery state of charge control method, which can reduce the loss and loss of the converter of a super large-scale battery energy storage power station. Enhance the working economy and reliability of batteries in energy storage power stations;

In order to solve the above-mentioned technical problems, the technical solution adopted by the present invention is: on the one hand, the present invention provides an energy storage type multilevel converter topology, including 5 battery packs, 5 capacitors and 3 converters; The 5 battery packs are respectively battery pack 1, battery pack 2, battery pack 3, battery pack 4 and battery pack 5. The 5 battery packs are connected in series to form a battery pack string; The second capacitor, the third capacitor, the fourth capacitor and the fifth capacitor, five capacitors are connected in series to form a capacitor string; the battery string is connected to the capacitor in series and parallel, and the positive and negative electrodes of each battery group are connected to the corresponding positive and negative electrodes of the capacitor; so The three converters are respectively the first converter, the second converter and the third converter, and each converter includes 50 IGBT tubes and diodes connected in anti-parallel with them. The device is connected in parallel with the positive and negative poles of the battery string.

Preferably, the five battery packs are all formed by m*n single energy storage batteries in series and parallel.

Preferably, 50 IGBT tubes and their anti-parallel diodes in each converter are arranged in a 10x5 matrix, and follow the order from left to right and top to bottom, and the 50 IGBTs and their anti-parallel connection The diodes are marked as S _ij , where 1≤i≤10, 1≤j≤5, 10 IGBTs in each column are connected in series, that is, the emitter of the previous IGBT in the same column is connected to the collector of the next IGBT, the S ₃₁ The collector is connected to the lower port of the first capacitor, the collector of _S51 is connected to the lower port of the second capacitor, the collector of _S71 is connected to the lower port of the third capacitor, and the collector of ₅₉₁ is connected to the lower port of the fourth capacitor. ports are connected, the emitter of _S10,1 is connected to the lower port of the fifth capacitor; the collectors of _S11 , _S12 , _S13 , _S14 , _S15 are connected in parallel with the upper port of the first capacitor and the first port of the battery pack Positive connection, the emitters of _S11 , _S12 , _S13 , _S14 , _S15 are connected, the emitters of _S22 , _S23 , _S24 , _S25 are connected, the emitter of _S31 is connected with the emitter of _S32 , the emitters of _S33 , _S34 , _S35 are connected, the emitter of _{S42 is connected with the emitter of S43 ,} the emitter of _S44 is connected with the emitter of _S45 , the emitter of _S51 is connected with the emitter of _S52 The emitter of S ₅₃ is connected with the emitter of S ₅₄ , the emitter of S ₆₂ is connected with the emitter of S ₆₃ , the emitter of 5 ₆₄ is connected with the emitter of S ₆₅ , the emitter of S ₇₁ is connected with the emitter of S ₇₂ The emitters of _S73 , _S74 , and _S75 are connected, the emitters of _S82 , _S83 , _S84 , and _S85 are connected, and the emitters of _S91 , _S92 , _S93 , _S94 , and _S95 are connected. The poles are connected, and the emitters of S _10,1 , S _10,2 , S _10,3 , S _10,4 , and S _10,5 are connected in parallel with the negative pole of the fifth battery pack.

Preferably, the IGBT gate of each converter has 6 different switching states according to different modulation strategies, which are:

Switch state 1: _S65 , _S74 , _S75 , _S83 , _S84 , _S85 , _S92 , _S93 , _S94 , _S95 , _S10,1 , _S10,2 , _S10,3 , S _10,4 , _{S10 , IGBT No. 5 is turned on} , and the output current _{i p} of the _converter is S ₉₅ , S _10,1 , S _10,2 , S _10,3 , S _10,4 , S ₁₀ , any conduction path formed by No. 5 IGBT flows, S ₂₁ , S ₃₂ , S ₄₁ , S ₄₃ , S ₅₂ , _S54 , _S61 , _S63 , _S72 , _S81 IGBTs are turned on to form a blocking voltage, and the other IGBTs are turned off, and the output voltage of the converter is 0 at this time;

Switch state 2: S ₅₄ , S ₅₅ , S ₆₃ , S ₆₄ , S ₆₅ , S ₇₂ , S ₇₃ , S ₇₄ , S ₇₅ , S ₈₁ , S ₈₂ , S ₈₃ , S ₈₄ , S ₈₅ , S ₉₁ , S IGBTs ₉₂ , _S93 , _S94 , and S95 are turned on, and the output current i _p of the converter follows the steps of _S54 , _S55 , _S63 , _S64 , _S65 , _S72 , _S73 , _S74 , _{S 75} , S ₈₁ , S ₈₂ , S ₈₃ , S ₈₄ , S ₈₅ , S ₉₁ , S ₉₂ , S ₉₃ , S ₉₄ , S ₉₅ IGBTs form an arbitrary conduction path, S ₂₁ , S ₃₂ , S ₄₁ , The IGBTs S ₄₃ , S ₅₂ , S ₅₄ and S ₆₁ are turned on to form the blocking voltage, and the other IGBTs are turned off. At this time, the output voltage of the converter is V _dc /5, where V _dc is the two ends of the battery string Voltage;

Switch state 3: _S43 , _S44 , _S45 , _S52 , _S53 , _S54 , _S55 , _S61 , _S62 , _S63 , _S64 , _S65 , _S71 , _S72 , _S73 , S ₇₄ , S75, _S82 , _S83 , _S84 , _S85 IGBTs are turned on, and the output current i _p of the converter is along the lines of _S43 , _S44 , _S45 , _S52 , _S53 , _S54 , _{S 55} , _S61 , S62, _S63 , _S64 , _S65 , _S71 , _S72 , _S73 , _S74 , _S75 , _S82 , _S83 , _S84 , _{S85 IGBTs} form any conduction The path flows, S ₂₁ , S ₃₂ , S ₄₁ , and S ₉₁ IGBTs are turned on to form a blocking voltage, and the remaining IGBTs are turned off. At this time, the output voltage of the converter is 2V _dc /5;

Switch state 4: _S32 , _S33 , S34, _S35 , _S41 , _S42 , _S43 , _S44 , _S45 , _S51 , _S52 , _S53 , _S54 , _S55 , _S62 , _{S 63} , S ₆₄ , S ₆₅ , S ₇₃ , S ₇₄ , S ₇₅ IGBTs are turned on, and the output current i _p of the converter follows S ₃₂ , S ₃₃ , S ₃₄ , S ₃₅ , S ₄₁ , S ₄₂ , S ₄₃ , _S44 , _S45 , _S51 , _S52 , _S53 , _S54 , S55, _{S62, S63, S64, S65, S73 , S74 , S75 IGBTs form any} conduction The path flows, _S21 , _S71 , _S82 , _S91 IGBTs are turned on to form a blocking voltage, and the other IGBTs are turned off. At this time, the output voltage of the converter is 3V _dc /5;

Switch state 5: S ₂₁ , S ₂₂ , S ₂₃ , S ₂₄ , S ₂₅ , S ₃₁ , S ₃₂ , S ₃₃ , S ₃₄ , S ₃₅ , S ₄₂ , S ₄₃ , S ₄₄ , S ₄₅ , S ₅₃ , S IGBTs ₅₄ , S ₅₅ , S ₆₄ , and S ₆₅ are turned on, and the output current i _p of the converter follows the steps of S ₂₁ , S ₂₂ , S ₂₃ , S ₂₄ , S ₂₅ , S ₃₁ , S ₃₂ , S ₃₃ , S ₃₄ , S ₃₅ , S ₄₂ , S ₄₃ , S ₄₄ , S ₄₅ , S ₅₃ , S ₅₄ , S ₅₅ , S ₆₄ , S ₆₅ IGBTs form an arbitrary conduction path flow, S ₅₁ , S ₆₂ , S ₇₁ , The IGBTs _S73 , _S82 and _S91 are turned on to form the blocking voltage, and the other IGBTs are turned off. At this time, the output voltage of the converter is 4V _dc /5;

Switch state 6: _Su , S ₁₂ , S ₁₃ , S ₁₄ , S ₁₅ , S ₂₂ , S ₂₃ , S ₂₄ , S ₂₅ , S ₃₃ , S ₃₄ , S ₃₅ , S ₄₄ , S ₄₅ , S ₅₅ IGBTs On, the output current i _p of the converter is along S ₂₁ , S ₂₂ , S ₂₃ , S ₂₄ , S ₂₅ , S ₃₁ , S ₃₂ , S ₃₃ , S ₃₄ , S ₃₅ , S ₄₂ , S ₄₃ , S ₄₄ , S ₄₅ , S ₅₃ , S ₅₄ , S ₅₅ , S ₆₄ , S ₆₅ IGBTs form any conduction path to flow, S ₃₁ , S ₄₂ , S ₅₁ , S ₅₃ , S ₆₂ , S ₆₄ , S ₇₁ , The IGBTs S ₇₃ , S ₈₂ and S ₉₁ are turned on to form a blocking voltage, and the other IGBTs are turned off. At this time, the output voltage of the converter is V _dc .

On the other hand, the present invention also provides a method for regulating the state of charge of the battery in the energy storage type multilevel converter topology, the specific method being:

做差，并对差值ΔImb_soci′在PI调节器中进行调节，其中，i′＝2，3，…，5；Step 1: Calculate the state-of-charge imbalance Imb _soci' among the battery strings in the battery string, and compare it with the reference value

Make a difference, and adjust the difference ΔImb _soci' in the PI regulator, where i'=2,3,...,5;

Step 1.1: Calculate the output power P of the battery string, as shown in the following formula:

Among them, m is the modulation coefficient of the converter, I _rms is the effective value of the output currents of the three converters, and Φ is the phase shift angle of the reference phase voltage;

The common current i _com of the battery strings is obtained according to the output power P of the battery strings, as shown in the following formula:

Step 1.2: Calculate the DC regulation current I _i' according to the current flowing through each battery pack, where I _i' is the current between the connection point of the i'-1th battery pack and the i'th battery pack and the capacitor. When the current I ₂ is used, let the regulation current I ₃ =I ₄ =I ₅ =0. Similarly, when calculating other regulation currents, set the corresponding regulation current value to zero, then:

Among them, i _Batk is the current flowing through the kth battery pack, k=1, 2,..., 5;

Step 1.3: Calculate the calculated value Imb _soci' and the reference value of the unbalance of the state of charge among the battery packs according to the state of charge of each battery pack and the DC regulation current

Step 1.3.1: According to the state of charge SoC _k of each battery pack, calculate the calculated value Imb _soci' of the state of charge imbalance between the battery packs, as shown in the following formula:

如下公式所示：Step 1.3.2: Calculate the reference value of the state-of-charge imbalance between the battery packs according to the DC regulation current

As shown in the following formula:

Among them, s Laplace integral operator, Q _nom is the nominal capacity of each battery pack;

送入PI调节器中进行调节，PI调节器中比例系数K_p＝100，积分系数K_i＝1；Step 1.4: Put the difference

Send it into the PI regulator for adjustment, the proportional coefficient K _p =100 and the integral coefficient K _i =1 in the PI regulator;

Step 2: send the adjusted output of the PI regulator into the decoupling matrix R _4x4 , and after the output is decoupled by the decoupling matrix R _4x4 , the output compensation ω _i' between the i'th battery pack is obtained;

The decoupling matrix R _4x4 is shown in the following formula:

Step 3: Update the modulation parameters of each converter according to the output compensation ω _i' between each battery group, obtain the duty ratio of each converter to control the switch state in the converter, and then regulate the state of charge of each battery group, The specific method is:

Step 3.1: modify the modulation coefficient m of the converter according to the modification coefficient λ to obtain the modified modulation coefficient _m ^* ;

Step 3.1.1: Calculate the voltage bias parameter y _i′ between each battery group according to the voltage of each battery group, as shown in the following formula:

Wherein, Vi _' is the voltage across the i'th battery pack;

Step 3.1.2: Calculate the correction coefficient λ according to the voltage bias parameters between the battery packs, as shown in the following formula:

Step 3.1.3: Make the output voltage of each battery pack consistent, and simplify the correction coefficient λ, as shown in the following formula:

Step 3.1.4: Use the simplified correction coefficient λ to multiply the modulation coefficient m to obtain the modified modulation coefficient m ^* , as shown in the following formula:

Step 3.2: Calculate the duty cycle d _xy of the IGBT on each converter according to the modified modulation coefficient m ^* and the voltage electrical angle θ of the output a-phase of the converter, where 1≤x≤3, 1≤ y≤10;

Step 3.2.1: Multiply the sine function of the electrical angle θ of the output a-phase voltage by the modulation coefficient m ^* of the converter to obtain the duty cycle d ₁ of the first converter, and then phase-shift the sine function to obtain the second The duty cycles d ₂ , d ₃ of the converter and the third converter are as follows:

Step 3.2.2: Take the maximum value Max(d _x ) of the duty ratios of the three converters, and multiply the difference between the maximum value and the duty cycle of each converter by the coefficient k ₁ to obtain the The duty cycle d _x1 (θ) of the first IGBT is given by the following formula:

d _x1 (θ)=k ₁ *Max[d ₁ (θ), d ₂ (θ), d ₃ (θ)]-d _x (θ)

Wherein, k ₁ =1/2;

Step 3.2.3: Take the minimum value Min(d _x ) of the duty ratios of the three converters, and multiply the difference between the minimum value and the duty cycle of each converter by the coefficient k ₂ to obtain the The duty cycle d _{x of the tenth IGBT, 10} (θ);

d _{x, 10} (θ)=d _x (θ)-k ₂ *Min[d ₁ (θ), d ₂ (θ), d ₃ (θ)]

Wherein, k ₂ =1/2;

Step 3.2.4: Calculate the duty cycle of the second to ninth IGBTs on each converter, as shown in the following formula:

d _x2 (θ)=d _x3 (θ)=…=d _x9 (θ)=k ₃ (1-d _x1 (θ)-d _x10 (θ))

Wherein, k ₃ =1/4;

Step 3.3: Compensate the duty cycle d _xy of each converter according to the output compensation ω _i′ between the battery packs to obtain the compensated duty cycle d _xy ^* , the specific method is as follows:

Step 3.3.1: Calculate the compensation coefficient ρ ₁ according to the output compensation between the battery packs, multiply the duty cycle d _x1 (θ) of the first IGBT in the three converters by the compensation coefficient ρ ₁ to obtain the compensation coefficient ρ 1 . Empty ratio d _x1 ^* (θ), where:

ρ ₁ =1-ω ₂ -ω ₃ -ω ₄ -ω ₅

Step 3.3.2: Calculate the compensation coefficient ρ ₂ according to the output compensation between the battery packs, and multiply the duty cycle d _x,10 (θ) of the tenth IGBT in the three converters by the compensation coefficient ρ ₂ to obtain the compensation Duty cycle d _{x, 10} ^* (θ), where:

ρ ₂ =1+ω ₂ +ω ₃ +ω ₄ +ω ₅

Step 3.3.3: Multiply the output compensation ω _i′ between the battery packs by the difference between d _x1 (θ) and d _x10 (θ), and add the multiplication result to d _xp (θ) to obtain each converter The duty cycle d _xp ^* (θ) after the compensation of the second to ninth IGBTs on the device, where 2≤p≤9;

In step 3.4, the post-compensation duty ratio of each IGBT of each converter is used to regulate and control the energy storage of each battery group, so that the state of charge of each battery group is regulated to be consistent.

The beneficial effects of adopting the above technical solutions are as follows: a topology of an energy storage type multilevel converter and a method for regulating the state of charge of a battery provided by the present invention, using the topology structure, under the six switching states of the converter, The output current of the converter has various flow paths, which reduces the voltage stress of the switch tube, reduces the maximum energy loss of a single switch tube, and improves the reliability of energy storage operation. At the same time, the battery state of charge control method proposed for this topology structure calculates the output compensation value between the battery packs according to the unbalanced state of charge of the battery pack, and then adjusts the duty cycle of the converter to achieve a balanced battery pack state of charge. This is a method to balance the state of charge of each battery group by distributing the energy flow between each battery group, without adding additional energy loss, and greatly saving the economic cost of the energy storage power station.

Description of drawings

1 is a schematic diagram of a topology structure of an energy storage type multilevel converter according to an embodiment of the present invention;

2 is a topological structure diagram of a multilevel converter provided by an embodiment of the present invention;

3 is a state diagram of a switch tube when the multilevel converter provided by an embodiment of the present invention is in switch state 1;

FIG. 4 is a state diagram of a switch tube when the multilevel converter provided by an embodiment of the present invention is in switch state 2;

FIG. 5 is a state diagram of a switch tube when the multilevel converter provided by an embodiment of the present invention is in switch state 3;

FIG. 6 is a state diagram of a switch tube when the multilevel converter provided by an embodiment of the present invention is in switch state 4;

FIG. 7 is a state diagram of a switch tube when the multilevel converter provided by an embodiment of the present invention is in switch state 5;

FIG. 8 is a state diagram of a switch tube when the multilevel converter provided by an embodiment of the present invention is in switch state 6;

9 is a flowchart of a method for regulating the state of charge of a battery in an energy storage type multilevel converter topology according to an embodiment of the present invention;

FIG. 10 is a simulation diagram of the duty cycle after compensation of each IGBT of the converter provided by the embodiment of the present invention;

FIG. 11 is a simulation diagram of a battery state-of-charge regulation result in an energy-storage-type multilevel converter topology provided by an embodiment of the present invention.

Detailed ways

The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and embodiments. The following examples are intended to illustrate the present invention, but not to limit the scope of the present invention.

In this embodiment, an energy storage type multilevel converter topology, as shown in FIG. 1 , includes 5 battery packs, 5 capacitors and 3 converters; the 5 battery packs are battery packs respectively 1. Battery pack 2, battery pack 3, battery pack 4 and battery pack 5, 5 battery packs are connected in series to form a battery pack string; 5 battery packs are formed by m*n single energy storage batteries in series and parallel. The five capacitors are respectively the first capacitor, the second capacitor, the third capacitor, the fourth capacitor and the fifth capacitor, and the five capacitors are connected in series to form a capacitor string; the battery string is connected in parallel with the capacitor series, and the positive The negative electrode is connected to the corresponding positive and negative electrodes of the capacitor; the three converters are the first converter, the second converter and the third converter respectively, and each converter includes 50 IGBT tubes and As shown in Figure 2, the three converters are connected in parallel with the positive and negative electrodes of the battery string.

The 50 IGBT tubes and their anti-parallel diodes in each converter are arranged in a 10x5 matrix distribution, and follow the order from left to right and top to bottom, and the 50 IGBTs and their anti-parallel diodes are marked as S _ij , where 1≤i≤10, 1≤j≤5, 10 IGBTs in each column are connected in series, that is, the emitter (E) of the previous IGBT in the same column is connected to the collector (C) of the next IGBT, The collector of _S31 is connected to the lower port of the first capacitor, the collector of S51 is connected to the lower port of the second capacitor, the collector of _S71 is connected to the lower port of the third _capacitor , the collector of _S91 is connected to the lower port of the fourth capacitor The lower ports of the capacitors are connected, the emitters of S ₁₀ and ₁ are connected to the lower ports of the fifth capacitor; the collectors of S ₁₁ , S ₁₂ , S ₁₃ , S ₁₄ and S ₁₅ are connected in parallel with the upper ports of the first capacitor and the battery The positive poles of group ₁ are connected, the emitters of _S11 , _S12 , _S13 , _S14 , and _S15 are connected, the emitters of _S22 , _S23 , _S24 , and _S25 are connected, and the emitter of S31 is connected to the emitter of _S32 . The emitter is connected, the emitter of _S33 , S34, S35 is connected, the emitter of _S42 is connected with the emitter of _S43 , the emitter of _S44 is connected with the _emitter of _S45 , the _emitter of _S51 is connected with S The emitter of ₅₂ is connected to the emitter of S ₅₃ , the emitter of S 53 is connected to the emitter of S ₅₄ , the emitter of S ₆₂ is connected to the emitter of S ₆₃ , the emitter of S ₆₄ is connected to the emitter of S ₆₅ , the emitter of S ₇₁ is connected to the emitter of S 65 Connected to the emitter of S72, connected to the emitter of _S73 , _S74 , _S75 , connected to the emitter of _S82 , _S83 , _S84 , _S85 , _S91 , _S92 , _S93 , _S94 , _S The emitters of ₉₅ are connected to each other, and the emitters of S _10,1 , S _10,2 , S _10,3 , S _10,4 , and S _10,5 are connected in parallel with the negative electrode of the fifth battery pack.

The IGBT gate (g) of each converter has 6 different switching states according to the corresponding modulation strategy, which are:

Switch state 1: As shown in Figure 3, _S65 , _S74 , _S75 , _S83 , _S84 , _S85 , _S92 , _S93 , _S94 , _S95 , _S10,1 , _S10,2 , S _10,3 , S 10, ₄ , S ₁₀ , IGBT No. 5 is turned on, and the output current i _p of the converter follows the steps of S ₆₅ , S ₇₄ , S ₇₅ , S ₈₃ , S ₈₄ , S ₈₅ , S ₉₂ , S ₉₃ , S ₉₄ , S ₉₅ , S _10,1 , S 10, 2 , S _10,3 , S ₁₀ , ₄ , S 10 , any conduction path formed by IGBT No. ₅ flows, S ₂₁ , S ₃₂ , S ₄₁ , _S43 , _S52 , _S54 , _S61 , _S63 , _S72 , _S81 IGBTs are turned on to form a blocking voltage, and the other IGBTs are turned off, and the output voltage of the converter is 0 at this time;

Switch state 2: As shown in Figure 4, S ₅₄ , S ₅₅ , S ₆₃ , S ₆₄ , S ₆₅ , S ₇₂ , S ₇₃ , S ₇₄ , S ₇₅ , S ₈₁ , S ₈₂ , S ₈₃ , S ₈₄ , S ₈₅ , S ₉₁ , S ₉₂ , S ₉₃ , S ₉₄ , S ₉₅ IGBTs are turned on, and the output current i _p of the converter follows S ₅₄ , S ₅₅ , S ₆₃ , S ₆₄ , S ₆₅ , S ₇₂ , S ₇₃ , _S74 , _S75 , _S81 , _S82 , _S83 , _S84 , _S85 , _S91 , _S92 , _S93 , _S94 , _S95 IGBTs form an arbitrary conduction path, _S21 , S ₃₂ , S ₄₁ , S ₄₃ , S ₅₂ , S ₅₄ , S ₆₁ IGBTs are turned on to form a blocking voltage, and other IGBTs are turned off. At this time, the output voltage of the converter is V _dc /5, where V _dc is the voltage across the battery string;

Switch state 3: As shown in Figure 5, S ₄₃ , S ₄₄ , S ₄₅ , S ₅₂ , S ₅₃ , S ₅₄ , S ₅₅ , S ₆₁ , S ₆₂ , S ₆₃ , S ₆₄ , S ₆₅ , S ₇₁ , S No. ₇₂ , _S73 , S74, _S75 , _S82 , _S83 , _S84 , _S85 IGBTs are turned on, and the output current i _p of the converter follows the steps of _S43 , _S44 , _S45 , _S52 , _{S 53} , _S54 , _S55 , _S61 , _S62 , _S63 , _S64 , _S65 , _S71 , _S72 , _S73 , _S74 , _S75 , _S82 , _S83 , _S84 , _S85 Any conduction path formed by the IGBT flows, the IGBTs S ₂₁ , S ₃₂ , S ₄₁ , and S ₉₁ are turned on to form the blocking voltage, and the other IGBTs are turned off. At this time, the output voltage of the converter is 2V _dc /5;

Switch state 4: As shown in Figure 6, S ₃₂ , S ₃₃ , S ₃₄ , S ₃₅ , S ₄₁ , S ₄₂ , S ₄₃ , S ₄₄ , S ₄₅ , S ₅₁ , S ₅₂ , S ₅₃ , S ₅₄ , S ₅₅ , S ₆₂ , S ₆₃ , S ₆₄ , S ₆₅ , S ₇₃ , S ₇₄ , S ₇₅ IGBTs are turned on, and the output current i _p of the converter follows S ₃₂ , S ₃₃ , S ₃₄ , S ₃₅ , S ₄₁ , _S42 , _S43 , _S44 , _S45 , _S51 , _S52 , _S53 , _S54 , _S55 , _S62 , _S63 , _S64 , _S65 , _S73 , _S74 , _S75 Any conduction path formed by the IGBT flows, the IGBTs S ₂₁ , S ₇₁ , S ₈₂ and S ₉₁ are turned on to form the blocking voltage, and the other IGBTs are turned off. At this time, the output voltage of the converter is 3V _dc /5;

Switch state 5: As shown in Figure 7, S ₂₁ , S ₂₂ , S ₂₃ , S ₂₄ , S ₂₅ , S ₃₁ , S ₃₂ , S ₃₃ , S ₃₄ , S ₃₅ , S ₄₂ , S ₄₃ , S ₄₄ , S ₄₅ , S ₅₃ , S ₅₄ , S ₅₅ , S ₆₄ , S ₆₅ IGBTs are turned on, and the output current i _p of the converter follows S ₂₁ , S ₂₂ , S ₂₃ , S ₂₄ , S ₂₅ , S ₃₁ , S ₃₂ , S ₃₃ , S ₃₄ , S ₃₅ , S ₄₂ , S ₄₃ , S ₄₄ , S ₄₅ , S ₅₃ , S ₅₄ , S ₅₅ , S ₆₄ , S ₆₅ IGBTs form an arbitrary conduction path to flow, S ₅₁ , IGBTs S ₆₂ , S ₇₁ , S ₇₃ , S ₈₂ and S ₉₁ are turned on to form a blocking voltage, and the other IGBTs are turned off. At this time, the output voltage of the converter is 4V _dc /5;

Switch state 6: As shown in Figure 8, S ₁₁ , S ₁₂ , S ₁₃ , S ₁₄ , S ₁₅ , S ₂₂ , S ₂₃ , S ₂₄ , S ₂₅ , S ₃₃ , S ₃₄ , S ₃₅ , S ₄₄ , S ₄₅ , S ₅₅ IGBT is turned on, and the output current i _p of the converter follows S ₂₁ , S ₂₂ , S ₂₃ , S ₂₄ , S ₂₅ , S ₃₁ , S ₃₂ , S ₃₃ , S ₃₄ , S ₃₅ , S ₄₂ , S ₄₃ , S ₄₄ , S ₄₅ , S ₅₃ , S ₅₄ , S ₅₅ , S ₆₄ , and S ₆₅ IGBTs form an arbitrary conduction path to flow, S ₃₁ , S ₄₂ , S ₅₁ , S ₅₃ , S ₆₂ , IGBTs S ₆₄ , S ₇₁ , S ₇₃ , S ₈₂ , and S ₉₁ are turned on to form a blocking voltage, and the other IGBTs are turned off. At this time, the output voltage of the converter is V _dc .

A method for regulating the state of charge of a battery in an energy storage multilevel converter topology is shown in Figure 9. The specific method is as follows:

做差，并对差值ΔImb_soci′在PI调节器中进行调节，其中，i′＝2，3，…，5；Step 1: Calculate the state-of-charge imbalance Imb _soci' among the battery strings in the battery string, and compare it with the reference value

Make a difference, and adjust the difference ΔImb _soci' in the PI regulator, where i'=2,3,...,5;

Step 1.1: Calculate the output power P of the battery string, as shown in the following formula:

Among them, m is the modulation coefficient of the converter, I _rms is the effective value of the output currents of the three converters, and Φ is the phase shift angle of the reference phase voltage;

The common current i _com of the battery strings is obtained according to the output power P of the battery strings, as shown in the following formula:

Step 1.2: Calculate the DC regulation current I _i' according to the current flowing through each battery pack, where I _i' is the current between the connection point of the i'-1th battery pack and the i'th battery pack and the capacitor. When the current I ₂ is used, let the regulation current I ₃ =I ₄ =I ₅ =0. Similarly, when calculating other regulation currents, set the corresponding regulation current value to zero, then:

Among them, i _Batk is the current flowing through the kth battery pack, k=1, 2,..., 5;

Step 1.3: Calculate the calculated value Imb _soci' and the reference value of the unbalance of the state of charge among the battery packs according to the state of charge of each battery pack and the DC regulation current

Step 1.3.1: According to the state of charge SoC _k of each battery pack, calculate the calculated value Imb _soci' of the state of charge imbalance between the battery packs, as shown in the following formula:

如下公式所示：Step 1.3.2: Calculate the reference value of the state-of-charge imbalance between the battery packs according to the DC regulation current

As shown in the following formula:

Among them, s Laplace integral operator, Q _nom is the nominal capacity of each battery pack;

送入PI调节器中进行调节，PI调节器中比例系数K_p＝100，积分系数K_i＝1；Step 1.4: Put the difference

Send it into the PI regulator for adjustment, the proportional coefficient K _p =100 and the integral coefficient K _i =1 in the PI regulator;

Step 2: send the adjusted output of the PI regulator into the decoupling matrix R _4x4 , and after the output is decoupled by the decoupling matrix R _4x4 , the output compensation ω _i' between the i'th battery pack is obtained;

The decoupling matrix R _4x4 is shown in the following formula:

Step 3: Update the modulation parameters of each converter according to the output compensation ω _i' between each battery group, obtain the duty ratio of each converter to control the switch state in the converter, and then regulate the state of charge of each battery group, The specific method is:

Step 3.1: modify the modulation coefficient m of the converter according to the modification coefficient λ to obtain the modified modulation coefficient m ^* ;

Step 3.1.1: Calculate the voltage bias parameter y _i′ between each battery group according to the voltage of each battery group, as shown in the following formula:

Wherein, Vi _' is the voltage across the i'th battery pack;

Step 3.1.2: Calculate the correction coefficient λ according to the voltage bias parameters between the battery packs, as shown in the following formula:

Step 3.1.3: Make the output voltage of each battery pack consistent, and simplify the correction coefficient λ, as shown in the following formula:

Step 3.1.4: Use the simplified correction coefficient λ to multiply the modulation coefficient m to obtain the modified modulation coefficient m ^* , as shown in the following formula:

Step 3.2: Calculate the duty cycle d _xy of the IGBT on each converter according to the modified modulation coefficient m ^* and the voltage electrical angle θ of the output a-phase of the converter, where 1≤x≤3, 1≤ y≤10;

Step 3.2.1: Multiply the sine function of the electrical angle θ of the output a-phase voltage by the modulation coefficient m ^* of the converter to obtain the duty cycle d ₁ of the first converter, and then phase-shift the sine function to obtain the second The duty cycles d ₂ , d ₃ of the converter and the third converter are as follows:

Step 3.2.2: Take the maximum value Max(d _x ) of the duty ratios of the three converters, and multiply the difference between the maximum value and the duty cycle of each converter by the coefficient k ₁ to obtain the The duty cycle d _x1 (θ) of the first IGBT is given by the following formula:

d _x1 (θ)=k ₁ *Max[d ₁ (θ), d ₂ (θ), d ₃ (θ)]-d _x (θ)

Wherein, k ₁ =1/2;

Step 3.2.3: Take the minimum value Min(d _x ) of the duty ratios of the three converters, and multiply the difference between the minimum value and the duty cycle of each converter by the coefficient k ₂ to obtain the The duty cycle d _{x of the tenth IGBT, 10} (θ);

d _{x, 10} (θ)=d _x (θ)-k ₂ *Min[d ₁ (θ), d ₂ (θ), d ₃ (θ)]

Wherein, k ₂ =1/2;

Step 3.2.4: Calculate the duty cycle of the second to ninth IGBTs on each converter, as shown in the following formula:

d _x2 (θ)=d _x3 (θ)=…=d _x9 (θ)=k ₃ (1-d _x1 (θ)-d _x10 (θ))

Wherein, k ₃ =1/4;

Step 3.3: Compensate the duty cycle d _xy of each converter according to the output compensation ω _i′ between the battery packs to obtain the compensated duty cycle d _xy ^* , the specific method is as follows:

Step 3.3.1: Calculate the compensation coefficient ρ ₁ according to the output compensation between the battery packs, multiply the duty cycle d _x1 (θ) of the first IGBT in the three converters by the compensation coefficient ρ ₁ to obtain the compensation coefficient ρ 1 . Empty ratio d _x1 ^* (θ), where:

ρ ₁ =1-ω ₂ -ω ₃ -ω ₄ -ω ₅

Step 3.3.2: Calculate the compensation coefficient ρ ₂ according to the output compensation between the battery packs, and multiply the duty cycle d _x,10 (θ) of the tenth IGBT in the three converters by the compensation coefficient ρ ₂ to obtain the compensation Duty cycle d _x10 ^* (θ), where:

ρ ₂ =1+ω ₂ +ω ₃ +ω ₄ +ω ₅

Step 3.3.3: Multiply the output compensation ω _i′ between each battery pack by the difference between d _x1 (θ) and d _{x, 10} (θ), and add the multiplication result to d _xp (θ) to obtain each Duty cycle d _xp ^* (θ) of the second to ninth IGBTs on the converter after compensation, where 2≤p≤9;

In step 3.4, the post-compensation duty ratio of each IGBT of each converter is used to regulate and control the energy storage of each battery group, so that the state of charge of each battery group is regulated to be consistent.

In this embodiment, the simulation of the duty cycle of each IGBT of the converter after compensation is shown in Fig. 10, and the energy storage of each battery group is regulated by using the duty cycle of each IGBT of each converter after compensation, so that each battery group is The state of charge was regulated to a consistent result as shown in Figure 11.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that it can still be The technical solutions described in the foregoing embodiments are modified, or some or all of the technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions depart from the scope defined by the claims of the present invention.

Claims (9)

1. an energy storage type multilevel converter topology, it is characterized in that: comprise 5 battery packs, 5 capacitors and 3 converters; Described 5 battery packs are respectively battery pack one, battery pack two , battery pack three, battery pack four and battery pack five, five battery packs are connected in series to form a battery pack string; the five capacitors are the first capacitor, the second capacitor, the third capacitor, the fourth capacitor and the fifth capacitor, 5 capacitors are connected in series to form a capacitor string; the battery string is connected in parallel with the capacitor series, and the positive and negative electrodes of each battery group are connected with the corresponding positive and negative electrodes of the capacitor; the three converters are the first converter, the third Two converters and a third converter, each converter includes 50 IGBT tubes and diodes connected in anti-parallel with them, and the three converters are connected in parallel with the positive and negative poles of the battery string; The 50 IGBT tubes and their anti-parallel diodes in each converter are arranged in a 10x5 matrix distribution, and follow the order from left to right and top to bottom, and the 50 IGBTs and their anti-parallel diodes are marked as S _ij , where _1≤i≤10 , 1≤j≤5, 10 IGBTs in each column are connected in series, that is, the emitter of the previous IGBT in the same column is connected to the collector of the next IGBT, and the collector of S31 is connected to The lower port of the first capacitor is connected, the collector of _S51 is connected to the lower port of the second capacitor, the collector of _S71 is connected to the lower port of the third capacitor, the collector of _S91 is connected to the lower port of the fourth capacitor, The emitter of _S10,1 is connected to the lower port of the fifth capacitor; the collectors of _S11 , _S12 , _S13 , _S14 , _S15 are connected in parallel with the upper port of the first capacitor and the positive electrode of the battery pack 1, The emitters of S ₁₁ , S ₁₂ , S ₁₃ , S ₁₄ , and S ₁₅ are connected, the emitters of S ₂₂ , S ₂₃ , S ₂₄ , and S ₂₅ are connected, the emitter of S ₃₁ is connected to the emitter of S ₃₂ , and the S ₃₃ , the emitters of _S34 and _S35 are connected, the emitter of _{S42 is connected with the emitter of S43 ,} the emitter of _S44 is connected with the emitter of _S45 , the emitter of _S51 is connected with the emitter of _S52 , The _emitter of _S53 is connected with the emitter of _S54 , the emitter of _S62 is connected with the emitter of _S63 , the emitter of _S64 is connected with the emitter of _S65 , the emitter of _S71 is connected with the emitter of S72 Connected, the emitters of _S73 , _S74 , _S75 are connected, the emitters of _S82 , _S83 , _S84 , _S85 are connected, the emitters of _S91 , _S92 , _S93 , _S94 , _S95 are connected, The emitters of S _10,1 , S _10,2 , S _10,3 , S _10,4 and S _10,5 are connected in parallel with the negative electrode of the fifth battery group. 2 . The energy storage type multilevel converter topology according to claim 1 , wherein the five battery packs are formed by m*n single energy storage batteries in series and parallel. 3 . 3. a kind of energy storage type multilevel converter topology according to claim 2, is characterized in that: the IGBT gate of described each converter has 6 kinds of different switching states according to different modulation strategies, They are: Switch state 1: _S65 , _S74 , _S75 , _S83 , _S84 , _S85 , _S92 , _S93 , _S94 , _S95 , _S10,1 , _S10,2 , _S10,3 , S _10,4 , _{S10 , IGBT No. 5 is turned on} , and the output current _{i p} of the _converter is S ₉₅ , S _10,1 , S _10,2 , S _10,3 , S _10,4 , S ₁₀ , any conduction path formed by No. 5 IGBT flows, S ₂₁ , S ₃₂ , S ₄₁ , S ₄₃ , S ₅₂ , _S54 , _S61 , _S63 , _S72 , _S81 IGBTs are turned on to form a blocking voltage, and the other IGBTs are turned off, and the output voltage of the converter is 0 at this time; Switch state 2: S ₅₄ , S ₅₅ , S ₆₃ , S ₆₄ , S ₆₅ , S ₇₂ , S ₇₃ , S ₇₄ , S ₇₅ , S ₈₁ , S ₈₂ , S ₈₃ , S ₈₄ , S ₈₅ , S ₉₁ , S IGBTs ₉₂ , _S93 , _S94 , and S95 are turned on, and the output current i _p of the converter follows the steps of _S54 , _S55 , _S63 , _S64 , _S65 , _S72 , _S73 , _S74 , _{S 75} , S ₈₁ , S ₈₂ , S ₈₃ , S ₈₄ , S ₈₅ , S ₉₁ , S ₉₂ , S ₉₃ , S ₉₄ , S ₉₅ IGBTs form an arbitrary conduction path, S ₂₁ , S ₃₂ , S ₄₁ , The IGBTs S ₄₃ , S ₅₂ , S ₅₄ and S ₆₁ are turned on to form the blocking voltage, and the other IGBTs are turned off. At this time, the output voltage of the converter is V _dc /5, where V _dc is the two ends of the battery string Voltage; Switch state 3: _S43 , _S44 , _S45 , _S52 , _S53 , _S54 , _S55 , _S61 , _S62 , _S63 , _S64 , _S65 , _S71 , _S72 , _S73 , S ₇₄ , S75, _S82 , _S83 , _S84 , _S85 IGBTs are turned on, and the output current i _p of the converter is along the lines of _S43 , _S44 , _S45 , _S52 , _S53 , _S54 , _{S 55} , _S61 , S62, _S63 , _S64 , _S65 , _S71 , _S72 , _S73 , _S74 , _S75 , _S82 , _S83 , _S84 , _{S85 IGBTs} form any conduction The path flows, S ₂₁ , S ₃₂ , S ₄₁ , and S ₉₁ IGBTs are turned on to form a blocking voltage, and the remaining IGBTs are turned off. At this time, the output voltage of the converter is 2V _dc /5; Switch state 4: _S32 , _S33 , S34, _S35 , _S41 , _S42 , _S43 , _S44 , _S45 , _S51 , _S52 , _S53 , _S54 , _S55 , _S62 , _{S 63} , S ₆₄ , S ₆₅ , S ₇₃ , S ₇₄ , S ₇₅ IGBTs are turned on, and the output current i _p of the converter follows S ₃₂ , S ₃₃ , S ₃₄ , S ₃₅ , S ₄₁ , S ₄₂ , S ₄₃ , _S44 , _S45 , _S51 , _S52 , _S53 , _S54 , S55, _{S62, S63, S64, S65, S73 , S74 , S75 IGBTs form any} conduction The path flows, _S21 , _S71 , _S82 , _S91 IGBTs are turned on to form a blocking voltage, and the other IGBTs are turned off. At this time, the output voltage of the converter is 3V _dc /5; Switch state 5: S ₂₁ , S ₂₂ , S ₂₃ , S ₂₄ , S ₂₅ , S ₃₁ , S ₃₂ , S ₃₃ , S ₃₄ , S ₃₅ , S ₄₂ , S ₄₃ , S ₄₄ , S ₄₅ , S ₅₃ , S IGBTs ₅₄ , S ₅₅ , S ₆₄ , and S ₆₅ are turned on, and the output current i _p of the converter follows the steps of S ₂₁ , S ₂₂ , S ₂₃ , S ₂₄ , S ₂₅ , S ₃₁ , S ₃₂ , S ₃₃ , S ₃₄ , S ₃₅ , S ₄₂ , S ₄₃ , S ₄₄ , S ₄₅ , S ₅₃ , S ₅₄ , S ₅₅ , S ₆₄ , S ₆₅ IGBTs form an arbitrary conduction path flow, S ₅₁ , S ₆₂ , S ₇₁ , The IGBTs _S73 , _S82 and _S91 are turned on to form the blocking voltage, and the other IGBTs are turned off. At this time, the output voltage of the converter is 4V _dc /5; Switch state 6: S ₁₁ , S ₁₂ , S ₁₃ , S ₁₄ , S ₁₅ , S ₂₂ , S ₂₃ , S ₂₄ , S ₂₅ , S ₃₃ , S ₃₄ , S ₃₅ , S ₄₄ , S ₄₅ , S ₅₅ IGBTs On, the output current i _p of the converter is along S ₂₁ , S ₂₂ , S ₂₃ , S ₂₄ , S ₂₅ , S ₃₁ , S ₃₂ , S ₃₃ , S ₃₄ , S ₃₅ , S ₄₂ , S ₄₃ , S ₄₄ , S ₄₅ , S ₅₃ , S ₅₄ , S ₅₅ , S ₆₄ , S ₆₅ IGBTs form any conduction path to flow, S ₃₁ , S ₄₂ , S ₅₁ , S ₅₃ , S ₆₂ , S ₆₄ , S ₇₁ , The IGBTs S ₇₃ , S ₈₂ and S ₉₁ are turned on to form a blocking voltage, and the other IGBTs are turned off. At this time, the output voltage of the converter is V _dc . 4. a kind of regulation method of battery state of charge, based on a kind of energy storage type multilevel converter topology described in claim 3, it is characterized in that: comprise the following steps: Step 1: Calculate the state-of-charge imbalance Imb _soci' among the battery strings in the battery string, and compare it with the reference value

Make the difference, and adjust the difference ΔImb _soci' in the PI regulator, where i'=2,3,...,5; Step 1.1: Calculate the output power P of the battery string, as shown in the following formula:

Among them, m is the modulation coefficient of the converter, I _rms is the effective value of the output currents of the three converters, and Φ is the phase shift angle of the reference phase voltage; The common current i _com of the battery strings is obtained according to the output power P of the battery strings, as shown in the following formula:

Step 1.2: Calculate the DC regulation current I _i' according to the current flowing through each battery pack, where I _i' is the current between the connection point of the i'-1th battery pack and the i'th battery pack and the capacitor. When the current I ₂ is used, let the regulation current I ₃ =I ₄ =I ₅ =0. Similarly, when calculating other regulation currents, set the corresponding regulation current value to zero, then:

Among them, i _Batk is the current flowing through the kth battery pack, k=1,2,...,5; Step 1.3: Calculate the calculated value Imb _soci' and the reference value of the unbalance of the state of charge among the battery packs according to the state of charge of each battery pack and the DC regulation current

Step 1.4: Put the difference

Send it into the PI regulator for adjustment, the proportional coefficient K _p =100 and the integral coefficient K _i =1 in the PI regulator; Step 2: send the adjusted output of the PI regulator into the decoupling matrix R _4x4 , and after the output is decoupled by the decoupling matrix R _4x4 , the output compensation ω _i' between the i'th battery pack is obtained; Step 3: Update the modulation parameters of each converter according to the output compensation ω _i' between each battery group, obtain the duty ratio of each converter to control the switch state in the converter, and then regulate the state of charge of each battery group, The specific method is: Step 3.1: modify the modulation coefficient m of the converter according to the modification coefficient λ to obtain the modified modulation coefficient m ^* ; Step 3.2: Calculate the duty cycle d _xy of the IGBT on each converter according to the modified modulation coefficient m ^* and the voltage electrical angle θ of the output a-phase of the converter, where 1≤x≤3, 1≤ y≤10; Step 3.3: Compensate the duty cycle d _xy of each converter according to the output compensation ω _i' between the battery packs, and obtain the compensated duty cycle d _xy ^* ; In step 3.4, the post-compensation duty ratio of each IGBT of each converter is used to regulate and control the energy storage of each battery group, so that the state of charge of each battery group is regulated to be consistent. 5. a kind of regulation method of battery state of charge according to claim 4, is characterized in that: the concrete method of described step 1.3 is: Step 1.3.1: According to the state of charge SoC _k of each battery pack, calculate the calculated value Imb _soci' of the state of charge imbalance between the battery packs, as shown in the following formula:

Step 1.3.2: Calculate the reference value of the state-of-charge imbalance between the battery packs according to the DC regulation current

As shown in the following formula:

Among them, s Laplace integral operator, Q _nom is the nominal capacity of each battery pack. 6. The method for regulating and controlling the state of charge of a battery according to claim 4, wherein: the decoupling matrix R _4x4 described in step 2 is shown in the following formula:

7. The method for regulating the state of charge of a battery according to claim 6, wherein the specific method of the step 3.1 is: Step 3.1.1: Calculate the voltage bias parameter y _i′ between each battery group according to the voltage of each battery group, as shown in the following formula:

Wherein, Vi _' is the voltage across the i'th battery pack; Step 3.1.2: Calculate the correction coefficient λ according to the voltage bias parameters between the battery packs, as shown in the following formula:

Step 3.1.3: Make the output voltage of each battery pack consistent, and simplify the correction coefficient λ, as shown in the following formula:

Step 3.1.4: Use the simplified correction coefficient λ to multiply the modulation coefficient m to obtain the modified modulation coefficient m ^* , as shown in the following formula:

8. The method for regulating the state of charge of a battery according to claim 7, wherein the specific method of the step 3.2 is: Step 3.2.1: Multiply the sine function of the electrical angle θ of the output a-phase voltage by the modulation coefficient m ^* of the converter to obtain the duty cycle d ₁ of the first converter, and then phase-shift the sine function to obtain the second The duty cycles d ₂ , d ₃ of the converter and the third converter are as follows:

Step 3.2.2: Take the maximum value Max(d _x ) of the duty ratios of the three converters, and multiply the difference between the maximum value and the duty cycle of each converter by the coefficient k ₁ to obtain the The duty cycle d _x1 (θ) of the first IGBT is given by the following formula: d _x1 (θ)=k ₁ *Max[d ₁ (θ), d ₂ (θ), d ₃ (θ)]-d _x (θ) Wherein, k ₁ =1/2; Step 3.2.3: Take the minimum value Min(d _x ) of the duty ratios of the three converters, and multiply the difference between the minimum value and the duty cycle of each converter by the coefficient k ₂ to obtain the The duty cycle of the tenth IGBT d _x,10 (θ); d _x,10 (θ)=d _x (θ)-k ₂ *Min[d ₁ (θ), d ₂ (θ), d ₃ (θ)] Wherein, k ₂ =1/2; Step 3.2.4: Calculate the duty cycle of the second to ninth IGBTs on each converter, as shown in the following formula: d _x2 (θ)=d _x3 (θ)=…=d _x9 (θ)=k ₃ (1-d _x1 (θ)-d _x10 (θ)) where k ₃ =1/4. 9. The method for regulating the state of charge of a battery according to claim 8, wherein the specific method of the step 3.3 is: Step 3.3.1: Calculate the compensation coefficient ρ ₁ according to the output compensation between the battery packs, multiply the duty cycle d _x1 (θ) of the first IGBT in the three converters by the compensation coefficient ρ ₁ to obtain the compensation coefficient ρ 1 . Empty ratio d _x1 ^* (θ), where: ρ ₁ =1-ω ₂ -ω ₃ -ω ₄ -ω ₅ Step 3.3.2: Calculate the compensation coefficient ρ ₂ according to the output compensation between the battery packs, and multiply the duty cycle d _x,10 (θ) of the tenth IGBT in the three converters by the compensation coefficient ρ ₂ to obtain the compensation Duty cycle d _x10 ^* (θ), where: ρ ₂ =1+ω ₂ +ω ₃ +ω ₄ +ω ₅ Step 3.3.3: Multiply the output compensation ω _i′ between each battery pack by the difference between d _x1 (θ) and d _x,10 (θ), and add the multiplication result to d _xp (θ) to obtain each The post-compensated duty cycles of the second to ninth IGBTs on the converter are d _xp ^* (θ), where 2≤p≤9.

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