The fault phenomena of fluorescent lamps are investigated by observing the operations in the last period of the life cycle. Accordingly, fault detecting and protection circuits are designed. Before coming to the life-end, the lamps can be started up, but are operated abnormally. A ruddy glow may occur at one end of the cathode filaments and an unstable arc may happen to the lamp. Obviously, the light efficiency becomes relatively low. The arc instability eventually results in a totally damaged fluorescent lamp. It is found that both waveforms of the lamp voltage and the lamp current are asymmetrical and have unequal positive and negative peak values. The asymmetry is more significant for the lamp voltage. In addition, a dc component is present in the lamp voltage. Based on these investigated results, the detection and protection circuits are designed for high-frequency electronic ballasts under dimming operations as well at the rated power. The experiments show that the detection and protection circuits can work effectively.

The metal halide lamp has become an attractive lighting source because of its compact size, good color rendering, long lamp life, and high luminous efficacy. As a member of high-intensity discharge lamps, it has a negative incremental resistance, which claims the necessity of a ballast circuitry. Similar to other gas discharge lamps, the operating performance can be further improved when driven by a high-frequency electronic ballast. However, there are some obstacles in ballasting the metal halide lamp with the high-frequency inverter. For a cold lamp, an ignition voltage up to several kVs is required for breaking down the electrodes during starting period. The breakdown voltage and the equivalent lamp resistance may vary from time to time and lamp to lamp, and is sensitive to the used time. Furthermore, the ignition voltage for restarting a hot lamp can be ten times that for a cold lamp. On the other hand, the lamp driven by a high-frequency electronic ballast may suffer from acoustic resonance. All these make it difficult in the design of an electronic ballast, especially for the applications with hot restarting. In this dissertation, the operating characteristics for both starting transient and steady-state of the metal halide lamp are first investigated. Then, a simple method by measuring the lamp voltage is proposed to detect the happening of acoustic resonance. Based on the investigated results, several electronic ballasts are designed for driving metal halide lamps with capabilities of wide input voltage range, high input power factor, hot restarting, fast transition. In addition, an inverter circuit is configured for ballasting multiple lamps. A buck-boost power-factor-correction circuit is integrated into the load resonant inverter to achieve a high power factor, fast transition, and constant power operation. The extremely high ignition voltage for hot restarting is generated by an auxiliary ignitor. The electronic ballast is precisely operated at the specific frequency at which acoustic resonance will not occur. In addition to these features, a protection circuit is included to prevent from high voltage and/or current stresses on circuit components in case that the lamp fails to be started up or comes to the end of its life-time. For the ballast with multiple lamps, the load circuits with abnormal lamps can be isolated from the others which are under normal operation. Prototypes of the proposed circuits are built and tested. Experimental results present the satisfactory performances.

Energy Harvesting from Exercise Machines (EHFEM) is an ongoing project pursuing alternate forms of sustainable energy for Cal Poly State University. The EHFEM project seeks to acquire user-generated DC power from exercise machines and sell that energy back to the local grid as AC power. The end goal of the EHFEM project aims to integrate a final design with existing elliptical fitness trainers for student and faculty use in Cal Poly’s Recreational Center. This report examines whether including the DC-DC converter in the EHFEM setup produces AC power to the electric grid more efficiently and consistently than an EHFEM system that excludes a DC-DC converter. The project integrates an overvoltage protection circuit, a DC-DC converter, and a DC-AC microinverter with an available elliptical trainer modified to include an energy converting circuit. The initial expectation was that a DC-DC converter would increase, when averaged over time, the overall energy conversion efficiency of the EHFEM system, and provide a stable voltage and current level for the microinverter to convert DC power into AC power. In actuality, while including a DC-DC converter in a test setup allows the EHFEM system to function with less frequent interruptions, this occurs at the cost of lower efficiency. Testing demonstrates the EHFEM project can convert user-generated DC mechanical power into usable AC electrical power. Retrofitting existing equipment with the EHFEM project can reduce Cal Poly’s energy cost.

Electronics for automotive needs to be able to handle different situations that can occur on the power line, such as high voltage transients. ISO16750 and ISO-7637 describes different pulses and tests a system needs to be able to handle. This report compares three different protection circuits that can output +5V and +12V built for low power devices. The circuits use different techniques for protection, one that uses TVS diodes, another that uses a voltage regulator IC with built in protection. The last protection uses P-channel MOSFET’s for protection. The circuits are compared against protection, price and leakage current. The most relevant transients to test a system against are decided to be pulse1, pulse 2a and load dump. A pulse generator consisting of a pulse shaping network and a common drain amplifier is used to create the test pulses. The result shows that all the circuits could protect against pulse 2a and load dump. However, all the circuits did fail against pulse 1 due to an undersized diode for negative voltage protection. The leakage current did not exceed 4µA for two of the circuits in the temperature interval of -40°C to +100°C. All the circuits started to have high leakage current when the temperature got up to +150°C. The price for the circuits didn’t differ that much, all the circuits cost below 3 US-dollar per circuit when making 10 000 circuits. The conclusions that could be made of the results are that all the circuits could protect against pulse 1, pulse 2a and load dump if correct diode is used for negative voltage protection. The protection that builds on Pchannel MOSFET’s should be the best choice for low power devices due to its low leakage current and potential for low cost. The disadvantage is the complexity and number of components needed for the circuit. The TVS diodes should be used if low complexity and low number of components is preferred. The disadvantage is that TVS diodes gets hot if a load dump is applied and the interval between stand-off voltage and maximum clamping voltage is quite high. The study also shows that there are cheaper solutions than using TVS diodes.