Constant current modulation method for a modular cascaded constant current source

Abstract

The application discloses a constant-current modulation method of a modular cascade constant-current source, and belongs to the technical field of power electronic modulation. According to the method, N carrier signals with the same amplitude are grouped in a sliding manner according to an adjacent order, the carrier signals in each group are arranged in a horizontal direction with a phase shift, and the carrier signals between groups are arranged in a vertical direction in a layering manner; and a switching driving signal is generated after comparing a modulation wave with the carrier signals in each group. When a cascade module is out of phase, the remaining modules in a current group and corresponding modules in a next group are dynamically reorganized into a new group, the carrier signals are multiplexed and redistributed, and local rapid reconstruction is realized. While maintaining the advantages of reducing current ripple through carrier phase shift and reducing switching loss through carrier layering, the application solves the problem that existing composite modulation methods need global reconstruction and have large hardware overhead under a fault condition, significantly reduces the calculation complexity and resource demand of a control system, and improves the fault tolerance and lightness level of a power supply system.

Description

Technical Field

[0001] This application belongs to the field of power electronic modulation technology, specifically relating to a constant current modulation method for a modular cascaded constant current source. Background Technology

[0002] Cascaded high-voltage constant current power supplies are one of the important circuit topologies suitable for charging high-voltage pulse capacitors. In principle, this topology exhibits voltage source output characteristics and requires current modulation methods to achieve a constant output current, meaning the charging current does not change with the capacitance of the pulse capacitor or voltage variations during charging.

[0003] Currently, various technical solutions have been proposed for constant current modulation in cascaded constant current charging power supplies. For example, constant current control strategies using timing coding or timing reconstruction can achieve basic constant current functionality, but they suffer from problems such as large charging current ripple, difficulty in implementing automatic current closed-loop control, and high hardware resource requirements. Carrier phase-shift modulation can solve the problems of charging current ripple and automatic output current closed-loop control using carrier modulation technology, but the switching transistors of all cascaded modules are in a high-frequency switching state throughout the charging process, resulting in significant switching losses.

[0004] One existing technology, "A Carrier Stacking Modulation Method Based on Cascaded Constant Current Source Topology" (Publication No.: CN117937711A), applies carrier stacking modulation to a cascaded high-voltage constant current source. By enabling most of the cascaded modules to operate in diode freewheeling mode, it effectively reduces switching losses. However, due to the reduced equivalent switching frequency, the charging current ripple under this scheme is relatively large.

[0005] Another existing technology, "A Composite Constant Current Control Method Based on Cascaded Constant Current Source Topology" (Publication No.: CN118040859A), proposes a carrier phase-shifting-stacked composite modulation strategy. This strategy groups the carriers, arranging them in a stacked manner between groups and in a phase-shifting manner within groups, which can reduce switching losses while maintaining low current ripple. However, this strategy uses a static grouping method. When a module phase loss fault occurs in the cascaded constant current source, all carrier signals need to be globally reconstructed to regenerate the switching signals, consuming significant hardware resources and resulting in high implementation complexity.

[0006] It is evident that the current modulation method of the existing cascaded constant current source still suffers from high hardware overhead and complex reconfiguration in fault-tolerant processing under fault conditions. There is an urgent need for a modulation method that can balance low current ripple, low switching loss and low fault reconfiguration cost. Summary of the Invention

[0007] To address the aforementioned technical issues, this application provides a constant current modulation method for a modular cascaded constant current source. Utilizing pulse width modulation (PWM) technology, it achieves automatic closed-loop constant current modulation of the output current of the cascaded constant current charging power supply. Simultaneously, by enabling the reuse of carrier signals between adjacent groups, in the event of a phase loss fault, only the next-level module needs to be moved into the current group for local reconstruction, without the need for global reallocation of all carriers. This simplifies the power control system architecture and reduces the size and weight of the power supply.

[0008] To achieve the above objectives, this application adopts the following technical solution:

[0009] A constant current modulation method for a modular cascaded constant current source includes the following steps:

[0010] The number of carrier signals with the same amplitude is also N, determined by the total number of N stages of the cascaded modules in the cascaded constant current charging power supply. Each carrier signal corresponds to one stage of the cascaded module.

[0011] N carrier signals are grouped into x carrier groups in adjacent order, each containing y carrier signals, satisfying the relationship x=N-y+1, and there is overlap between the carrier groups so that the same carrier signal can be multiplexed by two adjacent carrier groups;

[0012] The y carrier signals in each carrier group are arranged in a horizontal phase-shifted manner, with the phase shift angles being integer multiples of 2π / y.

[0013] Two adjacent carrier groups are stacked vertically, with the vertical displacement being the carrier amplitude V. m 1 / y times;

[0014] Each carrier signal in all x carrier groups after arrangement is compared with the same modulation wave signal. Based on the comparison result, drive signals for the switching transistors in N cascaded modules are generated. The j-th carrier group is used to drive the j-th to j+y-1-th cascaded modules.

[0015] Furthermore, the modulated wave signal is a control signal output by a dual closed-loop control system consisting of an outer voltage loop and an inner current loop, and its amplitude varies within the range of (0~). V m .

[0016] Furthermore, when the modulated wave signal is greater than or equal to a certain level of carrier signal, a high level is output as the pulse width modulation drive signal for the lower bridge arm of the insulated gate bipolar transistor in the corresponding cascaded module; when the modulated wave signal is less than a certain level of carrier signal, a low level is output as the pulse width modulation drive signal for the lower bridge arm of the insulated gate bipolar transistor in the corresponding cascaded module.

[0017] Furthermore, when the amplitude of the modulated wave signal is between 0 and V mDuring this period, the cascaded modules from level 1 to level y corresponding to the first carrier group are in modulation mode, while the remaining cascaded modules operate in diode freewheeling mode; when the amplitude of the modulated wave signal is at V... m / y to (1+1 / y)V m During this period, the cascaded modules from level 2 to level y+1 corresponding to the second carrier group are in a modulation state.

[0018] Furthermore, when a phase loss fault occurs in a cascaded module, the remaining cascaded modules in the modulation state corresponding to the current faulty carrier group are dynamically recombined with the cascaded modules corresponding to the next carrier group to form a new carrier group. The carrier signal is then redistributed to the recombined cascaded modules and compared with the modulation wave to generate a switching drive signal.

[0019] Furthermore, the horizontal phase-shifted arrangement of carrier signals within each carrier group increases the equivalent switching frequency to reduce charging current ripple; the vertical stacking arrangement between adjacent carrier groups reduces the number of cascaded modules in modulation state, thereby reducing the total switching loss of the system.

[0020] Furthermore, the modular cascaded constant current charging power supply includes a control system, a battery pack cascade module, thyristors, a current-limiting inductor, and a pulse capacitor; the battery pack cascade module is composed of N cascaded modules connected in series, and each cascaded module consists of a battery pack and two insulated-gate bipolar transistors connected in parallel.

[0021] Furthermore, the sliding grouping relationship x=N-y+1 allows adjacent carrier groups to naturally overlap on the carrier signal, so that when encountering fault reconstruction, only local adjustment of carrier allocation is required without global reallocation of all carrier signals.

[0022] Secondly, this application provides an electronic device, including: one or more processors; a memory for storing one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors implement the aforementioned constant current modulation method of a modular cascaded constant current source.

[0023] Thirdly, this application provides a computer-readable storage medium storing executable instructions thereon, which, when executed by a processor, enable the processor to implement the aforementioned constant current modulation method of a modular cascaded constant current source.

[0024] The beneficial effects of this application are as follows:

[0025] Reduced fault reconstruction complexity: This application employs carrier sliding grouping and cross-group multiplexing mechanisms. When a phase loss fault occurs in a cascaded module, only the next-level module needs to be moved into the current group for local reconstruction, without the need for global reallocation of all carrier signals. Compared to existing composite constant current control methods, this significantly reduces the hardware resource overhead and computational complexity of the control system under fault conditions.

[0026] Balancing low ripple and low loss: In this application, the intra-group carriers are arranged in a horizontal phase-shifting manner to maintain a high equivalent switching frequency and effectively reduce charging current ripple; the inter-group carriers are arranged in a vertical stacked manner, enabling most cascaded modules to operate in diode freewheeling mode, significantly reducing switching losses. It comprehensively inherits the advantages of both carrier phase-shifting and carrier stacking modulation methods.

[0027] Improving the system's lightweight level: Since the hardware resources required for fault reconstruction are reduced and the switching losses are reduced, which helps to simplify the thermal management system, this application is conducive to simplifying the controller architecture and reducing the size and weight of the heat dissipation system, thereby improving the overall lightweight level and fault tolerance performance of the cascaded constant current charging power supply. Attached Figure Description

[0028] Figure 1 A schematic diagram of the cascaded constant current charging power supply topology applicable to this application;

[0029] Figure 2 This is a modulation schematic diagram of a constant current modulation method for a modular cascaded constant current source according to this application. Detailed Implementation

[0030] The present application will be further described below with reference to the accompanying drawings and embodiments.

[0031] The constant current modulation method for a modular cascaded constant current source proposed in this application is applicable to cascaded constant current charging power supply topologies such as... Figure 1 As shown, it includes five parts: a control system 1, a battery pack cascade module 2, a thyristor 3 (i.e., SCR), a current-limiting inductor 4, and a pulse capacitor 5. The pulse capacitor 5 is the load component of the cascaded high-voltage constant current power supply. The high-voltage output terminal of the battery pack cascade module 2 is connected to one end of the thyristor 3, the other end of the thyristor 3 is connected to one end of the current-limiting inductor 4, the other end of the current-limiting inductor 4 is connected to the high-voltage terminal of the pulse capacitor 5, and the low-voltage terminal of the pulse capacitor 5 is connected to the low-voltage terminal of the battery pack cascade module 2. E1~E N For the battery pack in battery pack cascade module 2; L1~L N K is the equivalent inductance of the battery pack. 11 K 12 ~K N1 K N2The upper and lower bridge arms of the IGBT (Insulated Gate Bipolar Transistor) in each cascaded module 20; L is the loop current-limiting inductor 4; C is the pulse capacitor 5. The cascaded module 20 is composed of a battery pack and two IGBTs connected in parallel; N cascaded modules 20 are connected in series to form a battery pack cascade module 2.

[0032] The control system 1 mainly performs four functions: First, it outputs the control signal of the battery pack cascade module 2, which is connected to the drive terminal of the lower bridge arm of the IGBT in the battery pack cascade module 2 to control the timing of each stage of the battery pack being connected to the circuit; second, it outputs the turn-on signal for the thyristor 3, which is connected to the gate of the thyristor 3; third, it monitors the voltage across the pulse capacitor 5 in real time through a high-voltage divider connected across the pulse capacitor 5; and fourth, it detects the circuit current through a current transformer, which is fitted into the charging circuit.

[0033] A schematic diagram of the current modulation method is shown below. Figure 2 As shown in the diagram, in this modulation method, the carrier signal consists of N carriers with the same amplitude and a modulating wave, where N is the same as the circuit topology series. Each group has a y-phase carrier signal, and all carriers are divided into x groups during the charging process. The carrier signal corresponding to the switching transistor of each cascaded module will be used multiple times in adjacent different groups. The carrier signal between two adjacent groups is a carrier with the same amplitude displaced in the vertical direction. The carrier signals within a group are formed by carriers of the same amplitude offset horizontally at a certain angle. This angle is the carrier phase shift angle defined below. That is, carriers are stacked between groups and phase-shifted within groups. The modulated wave is a closed-loop control output signal with an amplitude equal to the carrier amplitude. The x groups of carrier waves are arranged and compared in real time with the same modulated wave. Based on the relationship between their magnitudes, the driving signal for the switching transistors of each cascaded module in the circuit topology is obtained, thereby achieving constant current output of the charging power supply. This modulation method can be called an improved carrier phase-shifting-stacking modulation method.

[0034] The working principle and process of this application are as follows:

[0035] First, determine the number of carrier waves based on the number of stages in the cascaded constant current charging power supply. The number of carrier waves is equal to the number of power supply stages, and we take N as the number of carrier waves.

[0036] Next, determine the number of groups x and the number of phases y in each group of the cascaded module 20 (each group has the same number of phases), where x = N - y + 1. The rule for determining the number of groups and phases is to maintain a small number of switching cycles and reduce switching losses while ensuring that the charging current ripple meets the requirements, thereby reducing the size and weight of the heat dissipation system.

[0037] Determine the amplitude of the carrier signal ;

[0038] Calculate the phase shift angle of the i-th phase carrier based on the number of phases y of each cascaded module group 20. , ;

[0039] Where i is 1, 2...y, corresponding to a certain cascade module 20 in x groups of cascade modules 20;

[0040] Then determine the vertical upward displacement of the j-th carrier signal based on the 1-th carrier signal. : ;

[0041] Where j is 1, 2...x, corresponding to a certain cascaded module 20;

[0042] The modulated wave signal D is the control signal output of the dual closed-loop control system consisting of an outer voltage loop and an inner current loop, and its range is (0~). V m .

[0043] Finally, each carrier signal is compared with the same modulated wave signal, and the switching signals of the lower IGBTs of each stage module are output. When the modulated wave signal is greater than or equal to a certain stage carrier signal, a high level is output as the PWM drive signal for that stage; when the modulated wave signal is less than a certain stage carrier signal, a low level is output as the PWM drive signal for that stage. Figure 2 As shown, when the modulation signal is in the range of 0~V m Between these points, the first to xth cascaded modules 20 in the cascaded constant current source are in modulation mode, while the other cascaded modules 20 operate in diode freewheeling mode. When the modulation signal is in... ~(1+ V m At this time, the second group of cascaded modules 20, i.e., the 2nd to (x+1)th cascaded modules 20, are in the modulation state, and so on until the charging is completed. When a cascaded module 20 in a certain group experiences a fault, the other cascaded modules 20 in that group that are in the modulation state will be regrouped with the next-level cascaded module 20 to form a new group for current modulation. The carrier signals of these cascaded modules are redistributed and then compared with the modulated wave to generate the IGBT switching signal. This modulation method uses carrier phase-shift modulation within the group, which effectively reduces charging current ripple; it uses carrier stacking modulation between groups, with most cascaded modules operating in diode freewheeling mode, thereby reducing switching losses; in the event of a fault, only the next-level cascaded module needs to be added to regroup and the carrier signal redistributed, reducing the computational load of the control system hardware. This allows constant current modulation to be achieved with fewer hardware resources and a simpler control architecture, reducing the complexity and weight of the power supply system.

[0044] Secondly, this application provides an electronic device, including: one or more processors; a memory for storing one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors implement the aforementioned constant current modulation method of a modular cascaded constant current source.

[0045] Thirdly, this application provides a computer-readable storage medium storing executable instructions thereon, which, when executed by a processor, enable the processor to implement the aforementioned constant current modulation method of a modular cascaded constant current source.

[0046] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above descriptions are merely specific embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A constant current modulation method for a modular cascaded constant current source, characterized in that, include: The number of carrier signals with the same amplitude is also N, determined by the total number of N stages of the cascaded modules in the cascaded constant current charging power supply. Each carrier signal corresponds to one stage of the cascaded module. N carrier signals are grouped into x carrier groups in adjacent order, each containing y carrier signals, satisfying the relationship x=N-y+1, and there is overlap between the carrier groups so that the same carrier signal can be multiplexed by two adjacent carrier groups; The y carrier signals in each carrier group are arranged in a horizontal phase-shifted manner, with the phase shift angles being integer multiples of 2π / y. Two adjacent carrier groups are stacked vertically, with the vertical displacement being the carrier amplitude V. m 1 / y times; Each carrier signal in all x carrier groups after arrangement is compared with the same modulation wave signal. Based on the comparison result, drive signals for the switching transistors in N cascaded modules are generated. The j-th carrier group is used to drive the j-th to j+y-1-th cascaded modules. When a phase loss fault occurs in a cascaded module, the remaining cascaded modules in the modulation state corresponding to the current faulty carrier group are dynamically recombined with the cascaded modules corresponding to the next carrier group to form a new carrier group. The carrier signal is redistributed to the cascaded modules in the new carrier group and compared with the modulation wave signal to generate a switching drive signal.

2. The constant current modulation method for a modular cascaded constant current source according to claim 1, characterized in that, The modulated wave signal is a control signal output from a dual closed-loop control system consisting of an outer voltage loop and an inner current loop, and its amplitude varies within the range of (0~). V m .

3. The constant current modulation method for a modular cascaded constant current source according to claim 1, characterized in that, When the modulated wave signal is greater than or equal to a certain level of carrier signal, a high level is output as the pulse width modulation drive signal for the lower bridge arm of the insulated gate bipolar transistor in the corresponding cascaded module; when the modulated wave signal is less than a certain level of carrier signal, a low level is output as the pulse width modulation drive signal for the lower bridge arm of the insulated gate bipolar transistor in the corresponding cascaded module.

4. The constant current modulation method of a modular cascaded constant current source according to claim 1, characterized in that, When the amplitude of the modulating wave signal is between 0 and V m During this period, the cascaded modules from level 1 to level y corresponding to the first carrier group are in modulation mode, while the remaining cascaded modules operate in diode freewheeling mode; when the amplitude of the modulated wave signal is at V... m / y to (1+1 / y)V m During this period, the cascaded modules from level 2 to level y+1 corresponding to the second carrier group are in a modulation state.

5. The constant current modulation method for a modular cascaded constant current source according to claim 1, characterized in that, The horizontal phase-shifting arrangement of carrier signals within each carrier group increases the equivalent switching frequency to reduce charging current ripple; the vertical stacking arrangement between adjacent carrier groups reduces the number of cascaded modules in modulation state, thereby reducing the total switching loss of the system.

6. The constant current modulation method of a modular cascaded constant current source according to claim 1, characterized in that, The modular cascaded constant current charging power supply includes a control system, a battery pack cascade module, thyristors, a current-limiting inductor, and a pulse capacitor; the battery pack cascade module is composed of N cascaded modules connected in series, and each cascaded module consists of a battery pack and two insulated-gate bipolar transistors connected in parallel.

7. The constant current modulation method for a modular cascaded constant current source according to claim 1, characterized in that, The sliding grouping relationship x=N-y+1 allows adjacent carrier groups to naturally overlap on the carrier signal. When encountering fault reconstruction, only local adjustment of carrier allocation is required without global reallocation of all carrier signals.

8. An electronic device, characterized in that, include: One or more processors; Memory, used to store one or more programs; When one or more programs are executed by the one or more processors, the one or more processors implement the constant current modulation method of a modular cascaded constant current source as described in any one of claims 1-7.

9. A computer-readable storage medium, characterized in that, It stores executable instructions that, when executed by a processor, enable the processor to implement a constant current modulation method for a modular cascaded constant current source as described in any one of claims 1-7.

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