Multiple Power Modules Research Articles

Research on Application of Three Closed-loop Autonomous Current Sharing Control Technology in Artillery Power System

The new artillery power system adopts the power supply mode of multiple power modules in parallel, which has the advantages of strong versatility, high power, high reliability, and low cost. The main difficulty lies in the current sharing of the power supply modules. Aiming at the shortcomings of traditional current sharing method such as low current sharing accuracy, poor dynamic response, poor output voltage stability, and low anti-interference ability, this article analyzes the necessity of parallel power supply current sharing and the principle of traditional average current sharing method, based on average current sharing method, a three-closed-loop autonomous current sharing control method is proposed, and a system model of power supply modules operating in parallel is established to realize the intelligent and autonomous average current distribution of power supply modules operating in parallel in the artillery power system to meet the power required by the load in the system. Through simulation analysis and prototype test, it is verified that the three closed-loop autonomous current sharing control has the advantages of high current sharing accuracy, fast dynamic response, good stability and strong robustness.

Localization of Oscillation Source in DC Distribution Network Based on Power Spectral Density

Direct current (DC) bus voltage stability is essential for the stable and reliable operation of a DC system. If an oscillation source can be quickly and accurately localized, the oscillation can be adequately eliminated. We propose a method based on the power spectral density for identifying the voltage oscillation source. Specifically, a DC distribution network model combined with the component connection method is developed, and the network is separated into multiple power modules. Compared with a conventional method, the proposed method does not require determining the model parameters of the entire power grid, which is typically challenging. Furthermore, combined with a novel judgment index, the oscillation source can be identified more intuitively and clearly to enhance the applicability to real power grids. The performance of the proposed method has been evaluated using the MATLAB/Simulink software and PLECS RT Box experimental platform. The simulation and experimental results verify that the proposed method can accurately identify oscillation sources in a DC distribution network.

Designof pulsed power supply for repetitive pulsed high magnetic field for water electrolysis.

A system based on a novel scheme for generating the repetitive pulsed high magnetic field (RPHMF) is developed and applied to enhance the performance of the NdFeB electrocatalyst in alkaline water electrolysis for the first time. In this system, the scheme for generating continuously high-frequency pulses depends on the cooperation of multiple power modules with a new structure. Multiple power modules are connected in parallel to energize the pulsed magnet, and each module is composed of two capacitor banks and a pulse transformer, which is used to realize the conversion of the energy between the two capacitor banks. As the residual energy in one capacitor is transferred to another, the energy required to be replenished for the next pulse reduces substantially. Then, the high repetition rate of the RPHMF can be achieved by discharging the capacitor banks of each module in sequence. The scheme has been validated by the experiment of a 2.4 T/12Hz prototype with only one power module. Simulation shows that the frequency of the RPHMF can be improved to 12*N Hz with N power modules, and a higher repetition rate of the RPHMF may bring new opportunities to the water electrolysis.

Parallel Control Method Based on the Consensus Algorithm for the Non-Isolated AC/DC Charging Module

A high-power charging station for electric vehicles usually adopts a parallel structure of multiple power modules. However, due to the parameter differences among power modules, a parallel system always has circulating current issues. This paper takes a non-isolated AC/DC charging module as the research object and proposes a current sharing control strategy for multiple power modules based on the consensus algorithm. By constructing a sparse communication network with the CAN (Controller Area Network) protocol and exchanging current information, accurate current sharing among power modules is realized. Firstly, the zero-sequence circulating current issue is analyzed through a parallel model of the three-phase rectifier, with an improved circulating current restraint strategy proposed based on the zero-sequence voltage compensation. Then, the principle of the consensus algorithm is explained, which is applied to the current sharing control of multiple power modules. Finally, the proposal is tested by the designed simulation and experimental cases. From the obtained results, it can be seen that the proposed control strategy can effectively realize accurate current sharing among multiple power modules and well restrain the zero-sequence circulating current at the input side.

Voltage and Power Balance Strategy without Communication for a Modular Solid State Transformer Based on Adaptive Droop Control

Solid State Transformers (SST) are attracting considerable attention due to their great application potential in future smart grids. It is an essential technology capable of promoting the modernization of the electric power distribution system and it is considered a key element for interfacing future microgrid systems to medium voltage utility grids, allowing plug-and-play integration with multiple renewable energy sources, storage devices and DC power systems. Its main advantages in relation to conventional transformers are substantial reduction of volume and weight, fault isolation capability, voltage regulation, harmonic filtering, reactive power compensation and power factor correction. A three-stage modular cascaded topology has been considered as an adequate candidate for the SST implementation, consisting of multiple power modules with input series and output parallel connection. The modular structure presents many advantages, e.g., redundancy, flexibility, lower current harmonic content and voltage stress on the power switches, however component tolerances and mismatches between modules can lead to DC link voltage imbalance and unequal power sharing that can damage the solid state transformer. This paper proposes a decentralized strategy based on adaptive droop control capable of promoting voltage and power balance among modules of a modular cascaded SST, without relying on a communication network. The behavior of the proposed strategy is assessed through a MATLAB/Simulink simulation model of an 100 kVA SST and shows that power and voltage balance are attained through inner power distribution of the SST modules, being transparent to elements connected to the transformer input and output ports. Besides that, real-time simulation results are presented to validate the proposed control strategies. The performance of embedded algorithms is evaluated by the implementation of the SST in a real-time simulation hardware, using a Digital Signal Processor (DSP) and high level programming.

Design of a Program-Controlled Precise Synchronous Triggering System Applied to Pulsed High Magnetic Field Facility

Recently, a Program-controlled Synchronous Triggering System (PSTS) is developed at Wuhan National High Magnetic Field Center. The designed system could generate triggering signal for thirteen power modules and eight magnets distributed in different experiment stations. By generating precise and synchronous triggering signals required for the facility, the multiple power modules could be discharged synchronously or in a preset time sequence. The PSTS is composed of triggering signal generator, fiber converter, expanded cell, and local sequence generator. The triggering signal generator, isolated from local device, is applied for sequential control of multi-module in the facility. The signal transmission is realized by optical fiber. A Digital Signal Processor (DSP) with specific type of TMS320F2812 is employed to design the triggering signal generator. The parameters of triggering channels and time-delay with the accuracy of 1 us could be configured through human machine interface. Local sequence generator unit is integrated in the local control unit on the basis of a Complex Programmable Logic Device (CPLD) with specific type of EPM7128. Local sequence generator is responsible for producing the time sequence signals to control and record the waveform of each power module, as well as the triggering signal waveform modulation for thyristor through expanded cell. Based on the designed system, the pulsed high magnetic field facility could be operated effectively. The test result illustrates that the system is of high performance.

An integrated methodology for multiobjective optimal component placement and heat sink sizing

The advances in power electronics packaging resulting from the integration of various high power devices into single programmable blocks are projected to significantly increase heat dissipation rates up to 2-3 W/mm/sup 2/ within the next decade. Conventional thermal management schemes such as air-cooled heat sinks are inadequate at these high power levels, requiring the use of forced liquid cooled heat sinks, or cold plates. A primary issue concerning the thermal-packaging designers today is the selection of a suitable cold plate and the optimum placement of components on it. This paper focuses on a methodology for selection of cold plates and the optimal placement of power modules on them. The basis of the methodology is the integration of computationally efficient reduced or "compact" thermal models within a genetic algorithm based multiobjective optimization framework. This methodology is used to optimize the placement of multiple power modules on a cold plate. It is also extended to perform a tradeoff analysis between multiple competing objectives for cold plate selection. Compact thermal models for power electronics and heat sinks are developed, validated, and integrated within the optimization framework. The effectiveness of the methodology as a rapid scouting tool to arrive at an optimum tradeoff solution set for further analysis by detailed numerical simulation is discussed. The methodology is general in the sense that it allows for incorporation of changes in optimization criteria or improvements in the heat transfer solver.

Compact Thermosyphon Using Refrigerant Flow Control. (Improvement of Heat Transfer Characteristics in the Cooling Unit with Multiple Power Modules Vertically Mounted)

In a compact closed two-phase loop thermosyphon which consists of a multiradiator and a refrigerant bath with multiple power modules mounted vertically, the heat radiation performance deteriorates as the refrigerant bath becomes thinner. We have found that this is because the return condensate is blocked by the back flow of the bubble in the return path when the heat load decreases and increases sharply. We have also improved the heat radiation performance by providing an adiabatic path between the boiling area and the return path.

Compact Thermosyphon with Refrigerant Flow Control. Improvement of Heat Transfer Characteristics in the Cooling Unit with Multiple Power Modules Mounted Vertically.

In a compact closed two-phase loop thermosyphon which consists of a multi-radiator and a refrigerant bath with multiple power modules mounted vertically the heat radiation performance deteriorates as the refrigerant bath becomes thinner. We have found that this is because the return condensate is blocked by the backflow of the bubble in the return path when the heat load decreases and increases sharply. We have also improved the heat radiation performance by providing an adiabatic path between the boiling area and the return path.

A dish-Stirling solar-thermal power system

This paper presents results of a preliminary design/economic study of a first-generation point focusing distributed receiver solar-thermal electric system optimized for application to industrial and small community power plants at power levels up to 10 MWe. Power conversion is provided by small Stirling cycle engines mounted at the focus of paraboloidal solar concentrators. The output of multiple power modules (concentrator, receiver, engine, and electric generator) is collected by means of a conventional electrical system and interfaced with a utility grid. Based on the United Stirling P-75 engine, a 1 MWe system employing mass-produced components (100,000 modules/year) could produce electricity at costs competitive with those projected for electricity generated by more conventional means, e.g. with fossil fuels.