The main purpose of the electrical power system is to transport and distribute energy generated by the central power plants in a safe and reliable manner to the customer premises. Most of the electrical equipment is e...The main purpose of the electrical power system is to transport and distribute energy generated by the central power plants in a safe and reliable manner to the customer premises. Most of the electrical equipment is exposed within the open which suggests they can be vulnerable to lightning strikes, road dwindling, windstorms, and a few engineering activities with the potential of causing different degrees of damage to the electrical equipment. One of the ways to guard the equipment is to deploy switching devices. However, the operations of most of these switching devices produce oscillatory transient in the electrical transmission and distribution systems which result in voltage, current, and frequency fluctuations in the load. This paper investigates the effect of switching devices on power quality and proposes a positive sequence voltage power transient suppression technique that can spontaneously improve the distorted voltage at the instant of capacitor switching using the capacitor line model as a case study. MATLAB/Simulink software was utilized for the analysis on an electrical network model with bus voltages of 69 kV/12.47 kV and 480 V. The results showed that, during switching operations, the positive sequence voltage power detector block produces ripple-free accurate results.展开更多
随着清洁能源规模的不断扩大,可平滑电能输出的混合储能系统(hybrid energy storage system,HESS)逐渐受到广泛关注。双有源桥可实现电气隔离和软开关,常应用于HESS中。为拓宽电压增益范围并降低储能装置侧电流纹波,文中提出一种基于电...随着清洁能源规模的不断扩大,可平滑电能输出的混合储能系统(hybrid energy storage system,HESS)逐渐受到广泛关注。双有源桥可实现电气隔离和软开关,常应用于HESS中。为拓宽电压增益范围并降低储能装置侧电流纹波,文中提出一种基于电流源型双向谐振变换器的HESS拓扑。首先,给出变换器的拓扑及等效电路,分析其开关模态和工作原理,推导出等效电路模型、电压增益表达式及低压侧电流纹波特性。在此基础上,提出一种解耦控制策略,通过调节各储能装置侧全桥的占空比独立控制超级电容和蓄电池的传输功率,并根据功率分配指令动态调整各端口功率占比。仿真结果表明,所提系统能实现各开关管的零电压开通(zero voltage switching,ZVS),在负载切换和功率指令变化时均表现出快速的动态响应和良好的稳定性。展开更多
由恒压/恒流式开关电源被广泛用于电池充电器中。但传统的电路设计需要使用许多元器件,不仅电路复杂,而且性能较差。介绍了一种专用的 LinkSwitch 系列恒压/恒流式单片开关电源,具有性能先进、电路简单、成本低廉等优点,适合构成4 W 以...由恒压/恒流式开关电源被广泛用于电池充电器中。但传统的电路设计需要使用许多元器件,不仅电路复杂,而且性能较差。介绍了一种专用的 LinkSwitch 系列恒压/恒流式单片开关电源,具有性能先进、电路简单、成本低廉等优点,适合构成4 W 以下的各种电池充电器或电源适配器。展开更多
High Speed Drilling Electrical Discharge Machining (HSDEDM) uses controlled electric sparks to erode the metal in a work-piece. Through the years, HSDEDM process has widely been used in high speed drilling and in manu...High Speed Drilling Electrical Discharge Machining (HSDEDM) uses controlled electric sparks to erode the metal in a work-piece. Through the years, HSDEDM process has widely been used in high speed drilling and in manufacturing large aspect ratio holes for hard-to-machine material. The power supplies of HSDEDM providing high power applica-tions can have different topologies. In this paper, a novel Pulsed-Width-Modulated (PWM) half-bridge HSDEDM power supply that achieves Zero-Voltage-Switching (ZVS) for switches and Zero-Current-Switching (ZCS) for the dis-charge gap has been developed. This power supply has excellent features that include minimal component count and inherent protection under short circuit conditions. This topology has an energy conservation feature and removes the need for output bulk capacitors and resistances. Energy used in the erosion process will be controlled by the switched IGBTs in the half-bridge network and be transferred to the gap between the tool and work-piece. The relative tool wear and machining speed of our proposed topology have been compared with that of a normal power supply with current limiting resistances.展开更多
In this paper, analysis, design and implementation of non-isolated soft-switching bidirectional DC-DC converter with an active switch are described. The proposed topology gives the output voltage as twice as the input...In this paper, analysis, design and implementation of non-isolated soft-switching bidirectional DC-DC converter with an active switch are described. The proposed topology gives the output voltage as twice as the input voltage and enhances the efficiency up to 94.5% and 92.9% for boost and buck mode operation by proper selection of the duty cycle. Soft switching can be achieved at both steps up and step down operating modes. Small signal analysis based on state space averaging and transfer functions have been presented in detail for the proposed converter. Finally, the feasibility of the desired converter is confirmed to mat lab simulation and investigational results.展开更多
文摘The main purpose of the electrical power system is to transport and distribute energy generated by the central power plants in a safe and reliable manner to the customer premises. Most of the electrical equipment is exposed within the open which suggests they can be vulnerable to lightning strikes, road dwindling, windstorms, and a few engineering activities with the potential of causing different degrees of damage to the electrical equipment. One of the ways to guard the equipment is to deploy switching devices. However, the operations of most of these switching devices produce oscillatory transient in the electrical transmission and distribution systems which result in voltage, current, and frequency fluctuations in the load. This paper investigates the effect of switching devices on power quality and proposes a positive sequence voltage power transient suppression technique that can spontaneously improve the distorted voltage at the instant of capacitor switching using the capacitor line model as a case study. MATLAB/Simulink software was utilized for the analysis on an electrical network model with bus voltages of 69 kV/12.47 kV and 480 V. The results showed that, during switching operations, the positive sequence voltage power detector block produces ripple-free accurate results.
文摘随着清洁能源规模的不断扩大,可平滑电能输出的混合储能系统(hybrid energy storage system,HESS)逐渐受到广泛关注。双有源桥可实现电气隔离和软开关,常应用于HESS中。为拓宽电压增益范围并降低储能装置侧电流纹波,文中提出一种基于电流源型双向谐振变换器的HESS拓扑。首先,给出变换器的拓扑及等效电路,分析其开关模态和工作原理,推导出等效电路模型、电压增益表达式及低压侧电流纹波特性。在此基础上,提出一种解耦控制策略,通过调节各储能装置侧全桥的占空比独立控制超级电容和蓄电池的传输功率,并根据功率分配指令动态调整各端口功率占比。仿真结果表明,所提系统能实现各开关管的零电压开通(zero voltage switching,ZVS),在负载切换和功率指令变化时均表现出快速的动态响应和良好的稳定性。
文摘High Speed Drilling Electrical Discharge Machining (HSDEDM) uses controlled electric sparks to erode the metal in a work-piece. Through the years, HSDEDM process has widely been used in high speed drilling and in manufacturing large aspect ratio holes for hard-to-machine material. The power supplies of HSDEDM providing high power applica-tions can have different topologies. In this paper, a novel Pulsed-Width-Modulated (PWM) half-bridge HSDEDM power supply that achieves Zero-Voltage-Switching (ZVS) for switches and Zero-Current-Switching (ZCS) for the dis-charge gap has been developed. This power supply has excellent features that include minimal component count and inherent protection under short circuit conditions. This topology has an energy conservation feature and removes the need for output bulk capacitors and resistances. Energy used in the erosion process will be controlled by the switched IGBTs in the half-bridge network and be transferred to the gap between the tool and work-piece. The relative tool wear and machining speed of our proposed topology have been compared with that of a normal power supply with current limiting resistances.
文摘In this paper, analysis, design and implementation of non-isolated soft-switching bidirectional DC-DC converter with an active switch are described. The proposed topology gives the output voltage as twice as the input voltage and enhances the efficiency up to 94.5% and 92.9% for boost and buck mode operation by proper selection of the duty cycle. Soft switching can be achieved at both steps up and step down operating modes. Small signal analysis based on state space averaging and transfer functions have been presented in detail for the proposed converter. Finally, the feasibility of the desired converter is confirmed to mat lab simulation and investigational results.
