K.W. Eric Cheng

General study for design the HID ballasts

High-intensity discharge (HID) lighting lamp systems are widely used in applications that can provide a high light levels are desired for large areas, such as vehicle headlight, industrial and street lighting. Similar to fluorescent lighting systems, all HID lighting systems require a ballast to operate. Traditionally, magnetic ballast designs were the only choice available for HID lighting systems. Today, high-efficiency electronic HID ballasts are available that provide improved lighting quality and reduce lighting electricity use by 10 to 30 percent. The purpose of this paper is to identify requirements of the ballast interface from the perspective of the HID lamp. This study will generally brief the starting, run-up, and steady state operation of HID lamps on electronics ballasts.

Variable Gain Intelligent Control of Multi-motor Synchronization System

Multi-motor synchronization control (MSC) is a key issue in industrial production. Based on the conventional PID algorithmic, a variable gain intelligence control scheme is proposed in this paper. Consequently, this new idea was implemented by PLC controller in the stretch tension & synchronization control system of a wide-fabric heating-shaping machine. Such a system has perfect characteristics, e.g. rapid response, overshoot-less and no steady-state errors. In addition, easy programming, simple wiring and strong anti-jamming ability lead to a stable operating performance. The proposed scheme can be widely used in electrical motor synchronization control demands arising from the spinnery, paper mill and mechanical production lines.

Shunt Active Power Filter - SIMULINK Simulation and DSP-based Hardware Realization

Active power filter (APF) is one of the effective means for harmonic current compensation in power grid. This paper focuses theoretical topics on a three-phase four-wire shunt active power filter (SAPF) system, covers operation principle, harmonic current detection, structure of main circuit, control of the DC voltage and compensating current. The overall system has been modeled using MATLAB/Simulink, and simulation results have shown that the structure is reasonable. Besides, the SAPF control systems hardware is realized based on DSP and MCU.

An adaptive modulation scheme for fundamental frequency switched multilevel inverter with unbalanced and varying voltage sources

Stepped modulation operates at fundamental frequency allows the use of low speed switching devices and mitigates the switching loss and EMI concerns suffered by many other hard-switched inverters adopting carrier-based pulse-width modulation (PWM) such as space vector PWM and sinusoidal PWM. Half-height (HH) method is one of the simplest ways to compute switching angles of stepped sinusoidal output. Similar approaches have been utilized in digital-analog signal conversion and synthesis. However, there is limited research on HH-based modulation for power inverters. In this paper, a computational modulation scheme based on HH method was studied. The proposed modulation scheme is capable for real-time computation with most present microprocessors. This paper will demonstrate the implementation of the proposed modulation scheme at balanced voltage and the techniques of adaption to varying and unbalanced sources. Capability of having minimum total harmonic distortion (THD) under equal voltage sources of HH method was verified. The performance of the proposed modulation scheme was examined using numeric calculation and simulation with a 7-level cascade H-bridge inverter and the results are presented.

High frequency AC auxiliary power source for future vehicles

High frequency AC power distribution system have been discussed for a few decades now. It finds applications in computer power supplies, aerospace power, lighting systems, micro grid and telecommunication equipment. This paper applies the high frequency AC power distribution system into a commercial vehicle. Prototype of a high frequency AC power source, rated at 500 VA with distribution frequency of 50 kHz, to be employed in a future vehicle for auxiliary power supply is designed and presented in the paper. DC voltage to the HF inverter is fed from a front-end hard switched boost converter. The converter-inverter systems performance is evaluated from the obtained simulation and preliminary experimental results.

Switched-capacitor multilevel inverters for high frequency AC microgrids

This paper proposes a novel topology of a switched-capacitor multilevel inverter for high frequency AC microgrids. It employs multiple DC sources which make it ideal to be employed in renewable energy sources based AC microgrids. With the proliferation in renewable energy based solar and wind farms, such multi-input topologies gain tremendous potential. Switched-capacitor based DC-DC converter in the front end produces multiple levels at the DC bus. Further, the H-bridge inverter obtains corresponding bipolar levels and a zero level at the output. The problem of capacitor voltage balancing is inherently solved as the capacitors are charged to the input voltage every cycle. Working principle and primary analysis of the topology are presented. Simulation outcomes are validated with experimental results at different distribution frequencies and power levels.

Ideas for future electric aircraft system

This design paper proposes few improvements on the existing electrical network in the aircraft system. It also suggests improvement in the starter circuitry by introducing super capacitors to reduce the number of batteries onboard to ensure improved safety and reliability. It proposes higher frequency of power distribution owing to several benefits. There are several advantages of high frequency AC power distribution over conventional DC distribution and low frequency AC power distribution. This paper explores the idea of employing switched capacitor and switched inductor converters to design multi-level inverters for high frequency AC power supplies for power distribution.

Bootstrap gate driver and output filter of an SC-based multilevel inverter for aircraft APU

The objective of this paper is to propose a gate drive circuit and an output filter of a switched-capacitor-based multilevel inverter for aircraft APU. With the bootstrap methodology, only one voltage source is required to power the gate driver of all switches used in the multilevel inverter. With the LC filter, this inverter is capable of providing a pure sinusoidal output voltage waveform. Finally, the performance of the proposed multilevel inverter is evaluated with simulation results and experimental results of an eleven-level prototype inverter.

The study of distributed EV charging station based on network

In order to reduce carbon emission, the world wide is developing novel electrical vehicle (EV) application. The battery and charging technology development is the most difficult breakthrough for EV promotion, wherein the design of convenient and reasonable charging station is critical to implement a sound charging system. This paper firstly introduces the development of Hongkong local charging station, and then proposes the distributed charging station network based on communication hierarchy. Finally, the state of charging (SoC) evaluation based on hybrid mode is presented. The deployment of charging station network testified distributed charging station network can effectively provide electricity to EV and centralized monitor the charging state. In the future, the proposed charging station network will has a broad application in Hong Kong market.

Some considerations of arc protection and breaker design for high frequency AC power distribution systems

High frequency power distribution already has a numerous applications in electric vehicle, renewable energy microgird, and telecommunication system. In order to propel high frequency power distribution into larger power grade, an effective ac arc protection scheme is significant for safety and reliability. However, almost all of the studies of arc fault are focused on dc or low frequency ac (LFAC). This paper presents protection scheme and examines electrical characteristics for high frequency arc fault. Meanwhile, high frequency breaker is examined with ZCS feature, and residual current devices (RCD) design is explored for high frequency power distribution as well. First, the location of arc fault detector (AFD) and interrupting devices (ID) is studied from system level; and the single phase arc grounding fault is analyzed for high frequency sinusoidal waveforms. Second, zero-current-switching (ZCS) feature of high frequency breaker is discussed from monitor circuit and breaker circuit. Third, trigger deficiency of high frequency RCD is demonstrated and corresponding solution is examined. Lastly, the simulation results further testify the effectiveness of theoretical analysis.