Wide-range voltage regulation method of ISOP type SST based on module switching

Abstract

The invention relates to a wide-range voltage regulation method of an ISOP type SST based on module switching, the SST comprises a plurality of modules composed of Buck-Boost circuits and CLLC isolation resonant converters, and the method comprises the following steps: adopting a double closed-loop control mode of voltage outer loop control and current inner loop control to control the SST in a steady state; when the voltage of the port drops and the duty ratio of a switching tube of the buck-boost circuit in any running module is smaller than a preset duty ratio throw-out threshold value, the running module m with the largest number is thrown out, the input current of the module m is controlled to be reduced to 0, and a bypass switch of the module m is closed; and when the port voltage rises and the duty ratio of a switching tube of the buck-boost circuit in any running module is greater than a preset duty ratio input threshold, inputting the module s which is not operated and has the minimum number, turning on a bypass switch of the module s, and controlling the input current of the module s to rise from 0 to an expected value.

Description

Technical Field

[0001] The present invention relates to the technical field of power transmission and distribution, and in particular to a wide-range voltage regulation method of an ISOP type SST based on module switching. Background Art

[0002] Input series output parallel (ISOP) solid-state transformers (SSTs) are widely used in power distribution, energy storage and other fields. In scenarios with a large voltage conversion range, such as energy storage systems, the accompanying SST is required to have a wide range of voltage regulation functions.

[0003] There are currently two main solutions for wide-range voltage regulation using ISOP-type SST. The first solution is to use a circuit that can regulate voltage over a wide range as a module topology, such as dual active bridges, series resonance and other circuits, and use the voltage regulation capability of the topology itself for voltage regulation. The second solution is to use a two-stage conversion structure, with the first stage used for wide-range voltage regulation and the second stage used for isolation.

[0004] Compared with the second solution, the first solution has fewer stages and higher efficiency, but in order to enable the circuit to have a wide range of voltage regulation capabilities, the passive components of the circuit are larger and the control strategy is more complicated.

[0005] The second solution uses a simpler circuit for voltage regulation, which reduces the design difficulty and volume of the isolation stage, but will result in an additional level of conversion loss. Summary of the invention

[0006] In view of the problems of large loss and low efficiency in the second solution, the present invention provides a wide-range voltage regulation method of an ISOP type SST based on module switching, wherein the ISOP type SST includes a plurality of modules numbered in sequence, each module includes a Buck-Boost circuit and a CLLC isolated resonant converter, and each module is electrically connected to a bypass switch. The voltage regulation method includes:

[0007] A dual closed-loop control method of voltage outer loop control and current inner loop control is used to implement steady-state control of ISOP type SST, where the voltage outer loop control quantity is the port voltage, and the current inner loop control quantity is the input current of each module. By adjusting the port voltage, the reference value of the input current of each module in steady state is:

[0008]

[0009] In equation (1), I in_ref is the reference value of the input current of each module, K u_p is the voltage outer loop proportional coefficient, K u_i is the voltage outer loop integral coefficient, V p_ref is the port voltage reference value, V p is the port voltage sampling value, t is the device operation time;

[0010] The duty cycle of the switch of the buck-boost circuit in the jth module in steady state is:

[0011]

[0012] In equation (2), d j is the duty cycle of the buck-boost circuit in the jth module, K ji_p is the current loop proportional coefficient of the jth module, K ji_i is the current loop integral coefficient of the jth module, I in_ref is the reference value of the input current of each module, I j is the input current sampling value of the jth module, and t is the device operation time;

[0013] When the port voltage drops and the duty cycle of the switch tube of the buck-boost circuit in any operating module is less than the preset duty cycle output threshold, the execution module outputs the control mode. The specific operations are as follows:

[0014] Select a module m with the largest number in operation in the ISOP type SST, where m≤n, and n is the number of modules in the ISOP type SST. Keep the control strategy of modules 1 to m-1 unchanged. Obtain the reference value of the input current of modules 1 to m-1 by equation (1). Obtain the switch duty cycle of the buck-boost circuit of modules 1 to m-1 by equation (2). Use a single current loop control method to gradually reduce the reference value of the input current of the module m to be cast to 0, so that the switch duty cycle of the module m also gradually becomes 0. Close the bypass switch of the module m to disconnect the module m, and complete the casting operation of the module m.

[0015] When the port voltage rises and the duty cycle of the switch tube of the buck-boost circuit in any operating module is detected to be greater than the preset duty cycle input threshold, the execution module enters the control mode. The specific operations are as follows:

[0016] Select a module s with the smallest number that is not in operation in the ISOP type SST, and open the bypass switch of the module s to make the module s pass. The reference value of the input current of each module that was in operation before the module s was put into operation is continued to be obtained by equation (1), and the duty cycle of the switch tube of the buck-boost circuit in each module is obtained by equation (2). The single current loop control method is used to control the reference value of the input current of the module s to be put into operation to gradually increase from 0 to the input current reference value I controlled by the port voltage. in ref, the duty cycle of the switch tube of the buck-boost circuit of module s gradually increases from 0 to the expected value, completing the input operation of the module s.

[0017] Beneficial effects:

[0018] The present invention provides a wide-range voltage regulation method for ISOP type SST based on module switching, which puts modules in or out according to the port voltage. When the port voltage is low, some modules are cut off to reduce losses; when the port voltage is high, modules are put into operation to ensure a sufficient voltage regulation range and enable the modules to operate at a higher efficiency point. The module switching method in the present invention will not have an impact on the system voltage and current. Therefore, the wide-range voltage regulation method provided by the present invention can not only use a simpler circuit for voltage regulation, reducing the design difficulty and volume of the isolation stage, but also reduce losses and improve efficiency, solving the problems of high losses and low efficiency in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the circuit topology diagram of ISOP type SST;

[0020] Figure 2 This is the system steady-state control block diagram;

[0021] Figure 3 This is the system control block diagram when the module is removed;

[0022] Figure 4 The control block diagram of the module to be removed when the module is removed;

[0023] Figure 5 Schematic diagram of the phase shift angle when the module is removed;

[0024] Figure 6 This is the system control block diagram when the module is put into use;

[0025] Figure 7 The control block diagram of the module is put into operation when the module is put into operation;

[0026] Figure 8 This is a schematic diagram of the phase shift angle when the module is put into operation;

[0027] Fig. 9 This is the simulation result diagram of working condition 1;

[0028] Fig.10 This is the simulation result diagram of working condition 2;

[0029] Fig.11 A schematic flow chart of a wide-range voltage regulation method of an ISOP-type SST based on module switching provided by the present invention. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not 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.

[0031] The following is combined with Figure 1-11 To illustrate a wide range voltage regulation method of ISOP type SST based on module switching provided by the present invention.

[0032] Figure 1 The circuit topology diagram of ISOP type SST is shown in Figure 1. Figure 1 It can be seen that the ISOP type SST includes a plurality of modules numbered in sequence, each module includes a Buck-Boost circuit and a CLLC isolated resonant converter, and each module is electrically connected to a bypass switch.

[0033] The core contents of the wide-range voltage regulation method of the ISOP type SST based on module switching include the following: Step S1: adopting a dual closed-loop control method of voltage outer loop control and current inner loop control to implement steady-state control of the ISOP type SST, wherein the voltage outer loop control quantity is the port voltage, and the current inner loop control quantity is the input current of each module; Step S2: when it is detected that the port voltage drops and the duty cycle of the switch tube in any operating module is less than the preset duty cycle switching threshold, the module switching control mode is executed, the module m with the largest number being operated is switched, the input current of the control module m is reduced to 0, and the bypass switch of the module m is closed; Step S3: when it is detected that the port voltage rises and the duty cycle of the switch tube in any operating module is greater than the preset duty cycle switching threshold, the module switching control mode is executed, the module s with the smallest number that is not in operation is switched, the bypass switch of the module s is opened, and the input current of the control module s is increased from 0 to the expected value.

[0034] The following is a detailed description of step S1-3.

[0035] Combine first Figure 1The circuit structure of the ISOP type SST mentioned in the present invention is briefly introduced. It is composed of n modules and adopts the structure of input series output parallel (ISOP). Each module includes two parts: the first part is a Buck-Boost circuit composed of a half-bridge, and the two switch tubes S1 and S2 are complementary to each other and are responsible for voltage regulation. The modulation method of carrier phase shift is adopted between the multiple Buck-Boost circuits in series, and the equivalent switching frequency is relatively high, so the volume of the filter inductor can be significantly reduced. Its duty cycle is defined as the proportion of the opening time of the upper tube S1 in the dotted frame A in the carrier cycle. The second part is the CLLC isolated resonant converter. Switches Q2, Q3, Q5, and Q8 are turned on synchronously, and switches Q1, Q4, Q6, and Q7 are turned on synchronously. The two sets of switches have the same conduction time per cycle, and the phase difference is 180 degrees. The duty cycle is defined as the proportion of the switch conduction time in the carrier cycle. The CLLC isolated resonant converter sends the input DC voltage to the opposite side of the transformer in a 1:1 manner. Both sides of the isolation transformer are full-bridge circuits. The full-bridges on both sides are switched synchronously and work at the resonant voltage point to achieve the conversion from DC / AC to AC / DC. This topology is only regulated by the Buck-Boost circuit, and the CLLC does not need to perform wide-range voltage regulation. Therefore, the CLLC resonant parameters are easy to design, the frequency range is narrow, it can operate at the optimal working point, and the control is simple.

[0036] The series buck-boost in the ISOP type SST involved in the present invention uses voltage and current dual closed-loop control, and the CLLC isolated resonant converter always operates at a fixed frequency and a fixed duty cycle (50%) at the resonant operating point.

[0037] Figure 2 This is the buck-boost control block diagram in steady state. Figure 1 The voltage and current variables that need to be sampled by the control method of the present invention are marked in FIG. 1 , where Vb is the bus voltage, Vp is the port voltage, I1 is the input current of the first module, I2 is the input current of the second module, I3 is the input current of the third module, and so on. n is the input current of the nth module. Each module 1-n adopts a sawtooth carrier staggered phase modulation method.

[0038] In step S1, a dual closed-loop control method of voltage outer loop control and current inner loop control is used to implement steady-state control of the ISOP type SST, wherein the voltage outer loop control quantity is the port voltage, and the current inner loop control quantity is the input current of each module. By adjusting the port voltage, the reference value of the input current of each module in the steady state is:

[0039]

[0040] In equation (1), I in_ref is the reference value of the input current of each module, Ku_p is the voltage outer loop proportional coefficient, K u_i is the voltage outer loop integral coefficient, V p_ref is the port voltage reference value, i.e. the desired steady-state port voltage value, V p is the sampling value of the port voltage, and t is the device operation time.

[0041] In addition, by adjusting the port voltage, the duty cycle of the switch tube of the buck-boost circuit in the jth module operating in a steady state needs to be:

[0042]

[0043] In equation (2), d j is the duty cycle of the buck-boost circuit in the jth module, K ji_p is the current loop proportional coefficient of the jth module, K ji_i is the current loop integral coefficient of the jth module, I in_ref is the reference value of the input current of each module, I j is the input current sampling value of the jth module, and t is the device operation time.

[0044] In steady state, balanced control of port voltage and module power and current is achieved.

[0045] In step S2, when it is detected that the port voltage drops and the duty cycle of the switch tube of the buck-boost circuit in any operating module is less than the preset duty cycle output threshold, the execution module outputs the control mode, and the specific operations are as follows:

[0046] Select the largest running module m in the ISOP type SST, m≤n, n is the number of modules in the ISOP type SST, keep the control strategy of the running modules 1 to module m-1 unchanged, obtain the reference value of the input current of modules 1 to module m-1 by equation (1), obtain the switch duty cycle of the buck-boost circuit of modules 1 to module m-1 by equation (2), use the single current loop control method to control the reference value of the input current of the module m to be cast so that it gradually decreases to 0, so that the switch duty cycle of the buck-boost circuit in the module m also gradually becomes 0, close the bypass switch of the module m to disconnect the module m, and complete the casting operation of the module m.

[0047] Specifically, when the port voltage drops, the input current reference value I of each module operating under the steady-state control strategy described in step S1 is in_refThe duty cycle of the switch tubes in the buck-boost circuits of the running modules will gradually decrease. When the duty cycle of the switch tubes in the buck-boost circuits of any running module is lower than the preset duty cycle output threshold, the module output control mode is entered. The setting range of the duty cycle output threshold is 0-1.

[0048] Figure 3 The block diagram of the module control when the module is not put into operation during the module output control. After entering the module output control, select the largest running module m in the ISOP type SST, m≤n, n is the number of modules in the ISOP type SST, and put the mth module into operation. For the convenience of description, it is assumed that the numbers of the running modules are sequential numbers. The control strategy of the running modules 1 to module m-1 remains unchanged, and the reference value I of the input current of modules 1 to module m-1 is still obtained by equation (1): in ref :

[0049]

[0050] In equation (1), I in_ref is the reference value of the input current of each module, K u_p is the voltage outer loop proportional coefficient, K u_i is the voltage outer loop integral coefficient, V p_ref is the port voltage reference value, i.e. the desired steady-state port voltage value, V p is the sampling value of the port voltage, and t is the device operation time.

[0051] Still from equation (2), the duty cycle of the switch in the jth buck-boost circuit in module 1 to module m-1 is obtained as:

[0052]

[0053] In equation (2), d j is the duty cycle of the buck-boost circuit in the jth module, K ji_p is the current loop proportional coefficient of the jth module, K ji_i is the current loop integral coefficient of the jth module, I in_ref is the reference value of the input current of each module, I j is the input current sampling value of the jth module, and t is the device operation time.

[0054] Figure 4 The control block diagram of the module to be cast is module m. The reference value of the input current of the cast module m is controlled by a single current loop control method so that it gradually decreases to 0. The time when the module casting control mode is entered is recorded as t cut, the input current of the module m to be cast is recorded as I m_tcut After entering the output control process of module m, the input current I of control module m m_tcut Gradually decreases to 0, the reference value of the input current I during the output control process of module m mcut_ref for:

[0055] I mcut_ref =I m_tcut -K d (tt cut ) (3)

[0056] Among them I mcut_ref is the reference value of the input current of the module m, I m_tcut is the input current of the module m, K d is the reference value drop rate of the input current of the module m being cast, in A / s, t cut is the moment to enter the module output control mode, and t is the device operation time.

[0057] In the process of executing the module output control mode, the switch duty cycle of the buck-boost circuit in the output module m is calculated by the following formula:

[0058]

[0059] where d m is the duty cycle of the buck-boost circuit in module m, K mi_p is the current loop proportional coefficient of module m, K mi_i is the current loop integral coefficient of module m, I mcut_ref is the reference value of the input current of module m, I m is the input current sampling value of module m, and t is the device operation time.

[0060] As the input current I of module m m_tc Gradually decreases to 0, the duty cycle of the switch tube of the buck-boost circuit in the module m will also decrease to 0, and the duty cycle of the CLLC isolated resonant converter will also gradually decrease to 0. At this time, the bypass switch of the module m is closed to disconnect the module m. When the input currents of each operating module are the same, the output operation of the module m is completed, and the number of operating modules is reduced by 1.

[0061] Continue to detect the port voltage and the duty cycle of the switch tube of the buck-boost circuit in each operating module. If the port voltage drops and the duty cycle of the switch tube of the buck-boost circuit in any operating module is less than the preset duty cycle output threshold, repeat step S2 to output the m-1th module until the port voltage drops and the duty cycle of the switch tube of the buck-boost circuit in any operating module is less than the preset duty cycle output threshold.

[0062] In step S3, when it is detected that the port voltage rises and the duty cycle of the switch tube of the buck-boost circuit in any operating module is greater than the preset duty cycle input threshold, the execution module is put into the control mode, and the specific operations are as follows:

[0063] A module s with the smallest number that is not in operation in the ISOP type SST is selected, and the bypass switch of the module s is turned on to make the module s pass. Even if the module s is electrically connected to the ISOP type SST, the reference value of the input current of each module that is in operation before the module s is put into operation continues to be obtained by equation (1), and the duty cycle of the switch tube of the buck-boost circuit in each operating module is obtained by equation (2). The single current loop control method is used to control the reference value of the input current of the module s that is put into operation to gradually increase from 0 to the input current reference value I controlled by the port voltage. in_ref , the duty cycle of the switch tube of the buck-boost circuit of module s gradually increases from 0 to the expected value, completing the input operation of the module s. At this time, the input current of each operating module is the same.

[0064] Specifically, when the port voltage rises, the input current reference value I of each module operating under the steady-state control strategy described in step S1 is in_ref The duty cycle of the switch tube of the buck-boost circuit in each running module will gradually increase, and when the duty cycle of the switch tube of the buck-boost circuit in any running module is greater than the preset duty cycle input threshold, the module input control mode is entered. The setting range of the duty cycle input threshold is 0-1, and the duty cycle input threshold is greater than the duty cycle output threshold.

[0065] Select a module s with the smallest number that is not in operation in the ISOP type SST, and open the bypass switch of the module s to enable the module s to pass, that is, the module s is electrically connected to the ISOP type SST. After that, the CLLC isolated resonant converter in the module s starts to operate, and its duty cycle slowly increases to 50%; after the duty cycle of the CLLC isolated resonant converter reaches 50%, the module enters the module input control mode.

[0066] Figure 6The system control block diagram is shown below, when the module is put into control, the module 1 to module m are running. In the process of executing the module put into control mode, the reference value of the input current of each module running before putting into module s is still obtained by equation (1):

[0067]

[0068] In equation (1), I in_ref is the reference value of the input current of each module, K u_p is the voltage outer loop proportional coefficient, K u_i is the voltage outer loop integral coefficient, V p_ref is the port voltage reference value, i.e. the desired steady-state port voltage value, V p is the sampling value of the port voltage, and t is the device operation time.

[0069] And, the duty cycle of the switch of the buck-boost circuit in each module is obtained by equation (2):

[0070]

[0071] In equation (2), d j is the duty cycle of the buck-boost circuit in the jth module, K ji_p is the current loop proportional coefficient of the jth module, K ji_i is the current loop integral coefficient of the jth module, I in_ref is the reference value of the input current of each module, I j is the input current sampling value of the jth module, and t is the device operation time.

[0072] Figure 7 This is the control block diagram of module m+1 after module s is put into operation. In the process of executing the module input control mode, a single current loop control method is adopted, and the switch duty cycle of the buck-boost circuit in the put-in module s is calculated by the following formula:

[0073]

[0074] where d s is the duty cycle of the buck-boost circuit in module s, K si_p K is the current loop proportional coefficient of module s. si_i is the current loop integral coefficient of module m, I scut_ref is the reference value of the input current of module s, I s is the input current sampling value of module s, and t is the device operation time.

[0075] In the process of executing the module into control mode, the reference value of the input current of module s increases from 0 to the reference value I of the input current of each module under the control of the port voltage. in_ref The reference value of the input current of module s is:

[0076]

[0077] Among them I scut_ref is the reference value of the input current of module s, K put It is the rising rate of the reference value of the input current when the module s is put into operation, in A / s, t put is the start time of module s, t is the device operation time, I in_ref It is the reference value of the input current of each module.

[0078] When the input current reference value of module s rises to the input current reference value I of each operating module under port voltage control in_re , and the duty cycle of the switch tube of the buck-boost circuit of module s becomes 50%, completing the input operation of module s, and the number of running modules increases by 1.

[0079] Continue to detect the port voltage and the duty cycle of the switch tube of the buck-boost circuit in each operating module. If the port voltage rises and the duty cycle of the switch tube of the buck-boost circuit in any operating module is greater than the preset duty cycle input threshold, repeat step S3 and put the m+2th module into operation until the port voltage rises and the duty cycle of the switch tube of the buck-boost circuit in any operating module is greater than the preset duty cycle input threshold.

[0080] Since each module in the present invention adopts a sawtooth carrier phase-shifting modulation method, it is necessary to control the change of the carrier phase of each module in the process of module output and module input to meet the requirement of continuing to work in the sawtooth carrier phase-shifting modulation method.

[0081] In step S1, each module is in steady-state operation. At this time, when there are m (m≤n) modules in operation, the carrier phase α of the jth module is j is the initial lag phase:

[0082]

[0083] where α j is the carrier phase of the jth module, m is the number of modules in operation, and Ts is the carrier period value.

[0084] Figure 5The schematic diagram of phase shift angle change control when the module is cast. In the process of casting the module, the phase shift angle of each running module is controlled to change synchronously with the decrease of the input current of module m. In the process of casting module m, the phase shift angle change of the jth module in the running modules 1 to module m is:

[0085]

[0086] where α jc is the phase shift angle change of the jth module from module 1 to module m, T s is the carrier cycle value, m is the number of modules running before module m is launched;

[0087] The carrier phase shift angle of the jth module is controlled as follows:

[0088]

[0089] where α j is the carrier phase shift angle of the jth module, T s is the carrier cycle value, m is the number of modules running before the module m is launched, I m is the input current sampling value of module m, I m_tcu is the input current of module m at the time of entering the output module m, α jc is the phase shift angle change of the jth module from module 1 to module m.

[0090] Figure 7 The diagram is a schematic diagram of the phase shift angle change when the module is put into operation. During the process of putting module s into operation, the phase shift angles of each module in control operation change synchronously with the increase of the input current of module s. The input current of module s will gradually increase to the input current reference value I in_ref When module s is put into operation, the phase shift angle change of the jth module among the modules running from 1 to m+1 is:

[0091]

[0092] where α jp is the phase shift angle change of the jth module, T s is the carrier cycle value, and m is the number of modules running before module s is put into operation.

[0093] The carrier lag angle of the jth module is controlled as follows:

[0094]

[0095] where α j is the carrier lag angle of the jth module, t s is the carrier cycle value, m is the number of modules running before module s is put into operation, I sis the input current sampling value of module s, I in_ref is the reference value of the input current of each module, α jp is the phase shift angle change of the jth module.

[0096] It can be seen from equations (9) and (11) that the carrier phase shift angle of the module in the output process and the carrier lag angle of the input process are both related to the input current of the module, and the switch duty cycle of the buck-boost circuit of the module is also related to the input current of the module. Therefore, the carrier phase shift angle and carrier lag angle of the control module can be controlled while controlling the switch duty cycle of the buck-boost circuit of the module.

[0097] In addition, the voltage outer loop proportional coefficient, voltage outer loop integral coefficient, current loop proportional coefficient, and current loop integral coefficient mentioned here are all fixed values, which can be obtained through existing technologies, and their specific values ​​are determined based on actual needs.

[0098] In order to further illustrate the effectiveness of the voltage regulation method proposed in the present invention, the method is verified under different working conditions below.

[0099] Simulation case 1:

[0100] The circuit and control parameters in simulation condition 1 are listed in Table 1. In condition 1, the number of system modules is 3, the bus voltage is 400V, and the output duty cycle threshold is 60%. At this time, the port voltage reference drops to 700V and the port load current is 55A. When the duty cycle drops to 60%, the system enters the module output control. The simulation results are shown in Fig. 9 The port voltage change rate during the casting process is <2%.

[0101] Table 1 Parameters of working condition 1

[0102]

[0103] Simulation case 2:

[0104] The circuit and control parameters in simulation condition 2 are listed in Table 2. In condition 2, the number of system modules is 3, the bus voltage is 400V, and the input duty cycle threshold is 90%. At this time, the port voltage reference is increased to 700V, and the port load current is 55A. When the duty cycle increases to 90%, the system enters the module input control. The simulation results are shown in Fig.10 . The port voltage change rate during the input process is <2%.

[0105] Table 2 Parameters of working condition 2

[0106]

[0107] The above content is a further detailed description of the present invention in combination with specific implementation methods. It cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, some simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the scope of protection determined by the claims submitted for the present invention.

Claims

1. A wide range voltage regulation method of an ISOP type SST based on module switching, the ISOP type SST comprising a plurality of modules numbered in sequence, each module comprising a Buck-Boost circuit and a CLLC isolated resonant converter, each module being electrically connected to a bypass switch, the voltage regulation method comprising: A dual closed-loop control method of voltage outer loop control and current inner loop control is used to implement steady-state control of ISOP type SST, where the voltage outer loop control quantity is the port voltage, and the current inner loop control quantity is the input current of each module. By adjusting the port voltage, the reference value of the input current of each module in steady state is: In equation (1), I in_ref is the reference value of the input current of each module, K u_p is the voltage outer loop proportional coefficient, K u_i is the voltage outer loop integral coefficient, V p_ref is the port voltage reference value, V p is the sampling value of the port voltage, t is the device operation time; The duty cycle of the switch of the buck-boost circuit in the jth module operating in steady state is: In equation (2), d j is the duty cycle of the buck-boost circuit in the jth module, K ji_p is the current loop proportional coefficient of the jth module, K ji_i is the current loop integral coefficient of the jth module, I in_ref is the reference value of the input current of each module, I j is the input current sampling value of the jth module, and t is the device operation time; When the port voltage drops and the duty cycle of the switch tube of the buck-boost circuit in any operating module is less than the preset duty cycle output threshold, the execution module outputs the control mode. The specific operations are as follows: Select a module m with the largest number in operation in the ISOP type SST, where m≤n, and n is the number of modules in the ISOP type SST. Keep the control strategy of the operating modules 1 to m-1 unchanged. Obtain the reference value of the input current of modules 1 to m-1 by equation (1). Obtain the switch duty cycle of the buck-boost circuit of modules 1 to m-1 by equation (2). Use a single current loop control method to gradually reduce the reference value of the input current of the module m to be cast to 0, so that the switch duty cycle of the module m also gradually becomes 0. Close the bypass switch of the module m to disconnect the module m, and complete the casting operation of the module m. When the port voltage rises and the duty cycle of the switch tube of the buck-boost circuit in any operating module is detected to be greater than the preset duty cycle input threshold, the execution module enters the control mode. The specific operations are as follows: Select a module s with the smallest number that is not in operation in the ISOP type SST, and open the bypass switch of the module s to make the module s pass. The reference value of the input current of each module that was in operation before the module s was put into operation is continued to be obtained by equation (1), and the duty cycle of the switch tube of the buck-boost circuit in each module is obtained by equation (2). The single current loop control method is used to control the reference value of the input current of the module s to be put into operation to gradually increase from 0 to the input current reference value I controlled by the port voltage. inref , the duty cycle of the switch tube of the buck-boost circuit of module s gradually increases from 0 to the expected value, completing the input operation of the module s.

2. A wide range voltage regulation method of ISOP type SST based on module switching according to claim 1, characterized in that: In the process of executing the module output control mode, the switch duty cycle of the buck-boost circuit in the output module m is calculated by the following formula: where d m is the duty cycle of the buck-boost circuit in module m, K mi_p K is the current loop proportional coefficient of module m. mi_i is the current loop integral coefficient of module m, I mcut_ref is the reference value of the input current of module m, I m is the input current sampling value of module m, and t is the device operation time.

3. A wide range voltage regulation method of ISOP type SST based on module switching according to claim 1, characterized in that: In the process of executing the module input control mode, the switch duty cycle of the buck-boost circuit in the module s is calculated by the following formula: where d s is the duty cycle of the buck-boost circuit in module s, K si_p K is the current loop proportional coefficient of module s. si_i is the current loop integral coefficient of module m, I scut_ref is the reference value of the input current of module s, I s is the input current sampling value of module s, and t is the device operation time.

4. A wide range voltage regulation method of ISOP type SST based on module switching according to claim 3, characterized in that: When executing the module into control mode, the reference value of the input current of module s is: Among them I scut_ref is the reference value of the input current of module s, K put It is the rising rate of the input current reference value when the module s is put into operation, in A / s, t put is the start time of module s, t is the device operation time, I in_ref It is the reference value of the input current of each module.

5. A wide range voltage regulation method of ISOP type SST based on module switching according to claim 1, characterized in that: Each module adopts a sawtooth carrier phase-shifted modulation method.

6. A wide range voltage regulation method of ISOP type SST based on module switching according to claim 5, characterized in that: In the process of casting module m, the phase shift angle change of the jth module from the running modules 1 to module m is: where α jc is the phase shift angle change of the jth module from module 1 to module m, T s is the carrier cycle value, m is the number of modules running before module m is launched; The carrier phase shift angle of the jth module is controlled as follows: where α j is the carrier phase shift angle of the jth module, T s is the carrier cycle value, m is the number of modules running before the module m is launched, I m is the input current sampling value of module m, I m_tcut is the input current of module m at the time of entering the output module m, α jc is the phase shift angle change of the jth module from module 1 to module m.

7. A wide range voltage regulation method of ISOP type SST based on module switching according to claim 5, characterized in that: In the process of putting module s into operation, the phase shift angle change of the jth module among the modules running from 1 to m+1 is: where α jp is the phase shift angle change of the jth module, T s is the carrier cycle value, m is the number of modules running before module s is put into operation; The carrier lag angle of the jth module is controlled as follows: where α j is the carrier lag angle of the jth module, T s is the carrier cycle value, m is the number of modules running before module s is put into operation, I s is the input current sampling value of module s, I in_ref is the reference value of the input current of each module, α jp is the phase shift angle change of the jth module.

8. A wide range voltage regulation method of ISOP type SST based on module switching according to claim 1, characterized in that: The duty cycle input threshold is greater than the duty cycle output threshold.

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