Wai Man Ng

A Novel Passive Offline LED Driver With Long Lifetime

This paper describes a patent-pending passive offline light-emitting diode (LED) driver that has no controlled semiconductor switches, electrolytic capacitors, auxiliary power supply, and control board. It can provide a fairly smooth current from the ac mains to drive LED strings. The new circuit has the advantages of high input power factor, high energy efficiency and luminous efficacy, long lifetime, stable luminous output, and high robustness against extreme weather conditions. In addition, over 90% of the driver material is recyclable, leading to reduction of electronic waste. It is particularly suitable public LED lighting systems, such as road lighting systems. Experimental results based on a 50-W system are included in the paper to confirm the validity of the proposal. Due to the circuit simplicity, an energy efficiency exceeding 93.6% has been achieved.

Two- and Three-Dimensional Omnidirectional Wireless Power Transfer

Nonidentical current control methods for 2- and 3-D omnidirectional wireless power systems are described. The omnidirectional power transmitter enables ac magnetic flux to flow in all directions and coil receivers to pick up energy in any position in the proximity of the transmitter. It can be applied to wireless charging systems for low-power devices such as radio-frequency identification devices and sensors. Practical results on 2-D and 3-D systems have confirmed the omnidirectional power transfer capability.

Optimal operation of contactless transformers with resonance in secondary circuits

Contactless transformer is an essential element in inductive power transfer systems. To improve its efficiency performance, a resonant tank is normally formed at the secondary side by adding an external capacitor in series (SS) or in parallel (SP) with the secondary winding. In this paper, a mathematical analysis based on simplified circuit model is presented. It leads to the theory of the boundary frequency which can be used to determine the optimal operating range for SS and SP mode, respectively, from the efficiency point of view. Calculated and measured results have been given to verify the theory in a case study.

A novel passive off-line light-emitting diode (LED) driver with long lifetime

This paper describes a patent-pending passive offline LED driver that has no semiconductor switches, electrolytic capacitors, auxiliary power supply and control board. It can provide a fairly smooth current from the ac mains to drive LED strings. The new circuit has the advantages of high input power factor, high energy efficiency and luminous efficacy, long lifetime, stable luminous output and high robustness against extreme weather conditions. In addition, over 90% of the driver material is recyclable, leading to reduction of electronic waste. It is particularly suitable public LED lighting systems such as road lighting systems. Experimental results based on a 50W system are included in the paper to confirm the validity of the proposal. Due to the circuit simplicity, an energy efficiency exceeding 93.6% has been achieved.

Design of a Single Ultra-Low-Loss Magnetic Ballast for a Wide Range of T5 High-Efficiency Fluorescent Lamps

A patent-pending single design of an ultralow-loss (ULL) magnetic ballast for T5 high-efficient (T5-HE) fluorescent lamps rated from 14 to 35 W is presented. Based on the use of a nonlinear physical low-pressure discharge lamp model, it is discovered that the same set of ballast parameters can be chosen for operating T5-HE 14-, 21-, 28-, and 35-W lamps at their respective rated power at a mains voltage in the range of 220-240 V. With energy efficiency higher than and lifetime much longer than their electronic counterparts and being recyclable, the ULL ballasts offer a more environmentally friendly solution to T5-HE lamps than electronic ballasts. This single-ballast design offers great convenience to both ballast manufacturers and users, because only one product design can cover a range of the most popular T5-HE lamps. Both theoretical analysis and experimental results are included to confirm the validity of the proposal.

An Adaptive Observer-Based Switched Methodology for the Identification of a Perturbed Sinusoidal Signal: Theory and Experiments

This paper deals with a novel adaptive observer-based technique for estimating the amplitude, frequency, and phase of a single sinusoidal signal from a measurement affected by structured and unstructured disturbances. The structured disturbances are modeled as a time-polynomial so as to represent bias and drift phenomena typically present in applications, whereas the unstructured disturbances are modelled as bounded noise signals. The proposed estimation technique exploits a specific adaptive observer scheme equipped with a switching criterion allowing to properly address in a stable way poor excitation scenarios. The estimators stability properties are analyzed by input-to-state stability arguments. The practical characteristics of the proposed estimation approach are evaluated and compared with other existing tools by extensive simulation trials. Real experimental results are provided as well.

A “Class-A2” Ultra-Low-Loss Magnetic Ballast for T5 Fluorescent Lamps—A New Trend for Sustainable Lighting Technology

The high-voltage and low-current features of T5 lamps imply that the copper and core losses of the magnetic ballast can be greatly reduced. This paper shows that magnetic ballasts for high-voltage T5 lamps are not only feasible but their luminous and ballast-loss performance can be better than those of the electronic ballasts. Contrary to common belief, high frequency operation of T5 28 W lamps increases the luminous efficacy by an average of 3.6% only (less than 5%). Practical implementation of an ultra-low-loss magnetic ballast system for T5 28 W lamps is presented. Its total system power is less than the 32 W upper limit specified for Class A2 of energy-efficient electronic ballast for T5 28 W lamps. High-luminous efficacy of 75.63-77.66 lm/W can be achieved. This important breakthrough has the potential of reversing the existing trend of using electronic ballasts as the energy-saving technology in lighting industry. With a better luminous efficacy, lower product and maintenance costs, much longer lifetime, and the use of recyclable metallic materials over its electronic counterparts, this patent-pending proposal provides a truly sustainable lighting solution to the lighting industry.

A single eco-friendly ultra-low-loss magnetic ballast design for a wide range of T5 high-efficient fluorescent lamps

A patent-pending single design of an ultra-low-loss (ULL) magnetic ballast for a T5 high-efficient (T5-HE) fluorescent lamps rated from 14W to 35W is presented. Based on the use of a non-linear physical low-pressure discharge lamp model, it is discovered that the same set of ballast parameters can be chosen for operating T5-HE 14, 21, 28 and 35W lamps at their respective rated power at a mains voltage of 220V–240V. With energy efficiency higher than and lifetime much longer than their electronic counterparts and being recyclable, the ULL ballasts offer a more environmentally-friendly solution to T5-HE lamps than electronic ballasts. This single ballast design offers great convenience to both ballast manufacturers and users because only one product design can cover a range of the most popular T5-HE lamps. Both theoretical analysis and experimental results are included to confirm the validity of the proposal.

A “Class-A2” ultra-low-loss magnetic ballast for T5 fluorescent lamps

This paper shows that magnetic ballasts for highvoltage T5 lamps are not only feasible but their luminous and ballast-loss performance can be better than those of electronic ballasts. A computer-aided design and practical implementation of an ultra-low-loss magnetic ballast system for T5 28W lamps is presented. The high-voltage & low-current features of T5 lamps imply that the copper and core losses of the magnetic ballast can be greatly reduced. Its total system power is 30W (with a ballast loss of only 2.42W) is less than the 32W upper limit specified for Class A2 of energy-efficient electronic ballast for T5 28W lamps. High luminous efficacy of 74.8 lumen/W can be achieved. This important breakthrough has the potential of reversing the existing trend of using electronic ballasts as the energy-saving technology in lighting industry. With a better luminous efficacy, lower product and maintenance costs, much longer lifetime and the use of recyclable metallic materials over its electronic counterparts, this patent-pending proposal provides a truly sustainable lighting solution to the lighting industry.

A Fast-Convergent Modulation Integral Observer for Online Detection of the Fundamental and Harmonics in Grid-Connected Power Electronics Systems

Harmonics detection is a critical element of active power filters. A previous review has shown that the recursive discrete Fourier transform and the instantaneous p-q theory are effective solutions to extracting power harmonics in single-phase and three-phase power systems, respectively. This paper presents the operating principle of a new modulation function integral observer algorithm that offers a fast solution for the extraction of the fundamental current and the total harmonic current when compared with existing methods. The proposed method can be applied to both single- and three-phase systems. The observer-based algorithm has an advantageous feature of being able to be tuned offline for a specific application, having fast convergence, and producing estimated fundamental component with high circularity. It has been tested with both simulations and practical experiments for extracting the total harmonic current in a highly efficient manner. The results have confirmed that the proposed tool offers a new and highly effective alternative for the smart grid industry.