Changbao Zheng

Solar street lamp system using GPRS and ZIGBEE technology

The solar street lamp system using GPRS and ZIGBEE technology is designed in this paper. The street lamp management system is composed of GPRS wireless mobile network and ZIGBEE short-distance wireless network. Users can view the real-time parameters of street lamps on the computer (or mobile phone), and at the same time, can also set up some working parameters (e.g., working mode, voltage of turning on the light, load current, etc.) through the computer (or mobile phone). This streetlight system realizes automatic monitoring and control of various parameters of street lamps. It has the advantages of remote real-time monitoring, ease of maintenance, and so on. It will have broad prospects for potential applications and commercial markets.

Design of photovoltaic MPPT controller using interleaving parallel buck circuit

A photovoltaic controller is a converter which can transform the energy generated by photovoltaic cells and control the battery charging and discharging. The maximum power point tracking (MPPT) technology can maximize the efficiency of photovoltaic cell and effectively improve the efficiency of photovoltaic power generation system. The single-phase buck circuit is often used in a MPPT controller, which has some shortcomings such as large output current ripple, poor stability of output power, and so on. Therefore, the topological structure of two-phase interleaved parallel buck circuit is proposed in this paper. Experimental results show that ripples of output voltage and current are greatly reduced, the stability of power output is good, and it is more suitable for the MPPT photovoltaic controller.

Experimental research on the performance of ultracapacitor in EVs's application

Ultracapacitor is widely used in EVs for its high performance such as high power density, long cycle life and wide working temperature. However, the frequent use and variation of the operating temperature will affect the performance parameters of ultracapacitor and the variation trend of the ultracapacitors performance in this situation is always different from it is in normal operate situation. Meanwhile, the variation rules of the ultracapacitors performance directly affect the accurate estimate of the state of energy storage and the safety of energy storage system. Research on the variation rules of ultracapacitors performance parameters based on the practical application of EV is presented in this paper. According to the classic equivalent circuit, four different test methods are experimented. Then, the identification of these experimental parameters are carried out with each adapted tests and the variation rules of the performance parameters are also discussed. Finally, the general variation rules of the performance parameters are obtained.

Junction temperature acquiring system of the 3L-ANPC inverter based on labview

The three-level active-neutral-point-clamped (3L-ANPC) inverter is used to solve the problem of uneven loss distribution in the three-level neutral-point-clamped (3L-NPC) inverter. Labview is widely used for industrial monitoring. As a common industrial bus, RS485 is used to connect and control several devices. MLX906I4 is an infrared thermometer for non-contact temperature measurement. In this paper, firstly, the topology and total loss of the 3L-ANPC inverter is analyzed. Secondly, a temperature acquiring system consists of a lower system and PC computer has been built. The lower system is composed of four MLX906I4 chips and one AT89S52 MCU, while the software in PC is developed by Labview. The communication between PC and the lower system is realized by RS485 bus. Experimental results are compared with those of junction temperature measurements with an infrared camera. The comparison of results validates the accuracy and validity of this temperature acquiring system.

Fault tolerant control for a five-phase permanent magnet synchronous machine driving system

In this paper, an open-circuit fault tolerant strategy for a five-phase permanent magnet synchronous machine (PMSM) is proposed based on the theory of keeping the magneto-motive force constant under both healthy and faulty conditions. According to the principle, the corresponding modified current vectors of healthy windings under three different open-circuit faults are derived, respectively. Then, Both the finite element analysis-based predictions for the five-phase PMSM machine and Matlab/Simulink-based simulation for the whole driving system verify the effectiveness of the fault tolerant strategies under each open-circuit fault. Finally, a 5kW five-phase PMSM prototyped machine is manufactured and a DSP-based driving system is set up to verify the strategies.

Design of high-power buck-boost LED constant current drive circuit

Buck-boost constant current driving circuit is a flexible LED driving power supply, which can work properly in two modes of buck boost and boost. Buck-boost LED constant current drive circuit can adjust the operating mode according to vatiation of the load current to ensure that the output current is constant. The buck and boost topology structure is adopted as the main circuit of the drive circuit. The driving current of the experimental prototype is 2.5A and the output power is up to 30W. After a long time load test, the experimental results show that the designed circuit can work stably.

Study of predictive direct power control for three-level NPC converter

Based on the theoretical model of three-level converters, a mathematical model of the predictive active power and reactive power control is deduced. Relationship of both active power and reactive power with voltage vectors is analyzed from an instantaneous power perspective. Influence and tendency caused by voltage space vectors on the active power and reactive power are described in detail. Because different voltage vectors have different effects on the neutral point potential, the cost function related to the power error and neutral point potential control is constructed. According to the cost function, the optimum voltage vector sequence is determined. Correctness and feasibility of the predictive direct power control is verified through simulation and experiments.

Cascaded H-bridge multilevel converter for grid connection of photovoltaic system

This paper describes the characteristics of cascaded converter and details the work of cascaded H-bridge multilevel converter which use phase shifted carriers pulse width modulation. Use cascaded H-bridge multilevel converter instead of ordinary inverter, we can get a photovoltaic power generation system which has a multilevel output voltage. The PV system can be high-voltage grid, thus eliminating a lot of step-up device. It has higher safety and the risk of the short circuit of the direct-current is greatly reduced. So it has been widely used in medium and high power applications. At last, a simulation is performed to test the model, and the conclusion shows its correctness and validity.

Voltage differential feedback control for three-phase PV inverter based on repetitive control

Voltage differential feedback control system based on repetitive control is proposed in this paper. The scheme, which can improve the dynamic characteristic and steady state performance by Capacitor voltage as outer loop while its differential as inner loop without current sensor, is achieved on a three-phase PV inverter with TMS320F2808. Two different control strategies, traditional and repetitive control , have been applied in three-phase PV inverter platform. The experiment results indicate repetitive control system has a faster dynamic response and a more accurate output regulation than those of traditional one.

Electro-thermal loss analysis of the 3L-ANPC converter

The three-level active-neutral-point-clamped (3L-ANPC) voltage source converter (VSC) is used to overcome the uneven loss distribution. In 3L-ANPC VSC the dissipation in the power device is typically characterized by Sinusoidal Pulse Width Modulation (SPWM). The junction temperature and the load current of an actual power converter system are detected to calculate the power loss. This paper, firstly, calculates the total power losses under different power factor angle and modulation depth. Secondly, the thermal resistance and the thermal capacitance of various elements from datasheet are used to express the thermal network. The thermal network is used to estimate each power device junction temperature, and to analyze transient thermal distribution. The results of calculation are compared with that of junction temperature measurements with an infrared camera. Experimental results validate the improvement of the unequal distribution using 3L-ANPC.