Sumate Naetiladdanon

A variable-frequency asymmetrical voltage-cancellation control of series resonant inverters in domestic induction cooking

The variable-frequency asymmetrical voltage-cancellation (VFAVC) control is proposed in this paper to control the output power for a series resonant load with a full-bridge inverter for home appliance as induction cooking. The asymmetrical voltage-cancellation is used for controlling the output power. With the low quality factor loads, a fixed-frequency control might lead to non-zero-voltage-switching (NON-ZVS) operation. The proposed control strategy ensures the ZVS operation for switching loss reduction by varying the switching frequency slightly higher than the resonant frequency. By using the ZVS constant, the new control strategy is proposed by varying the switching frequency according to the output power. Moreover, this proposed control can improve the overall efficiency of inverter system. The experimental results are given in this paper to verify the proposed control method.

A dual output series resonant inverter with improved asymmetrical voltage-cancellation control for induction cooking appliance

This paper presents a dual output full-bridge series resonant inverter with improved asymmetrical voltage-cancellation control for induction cooking appliance. The proposed control scheme can adjust the output power separately, and achieves the zero-voltage switching (ZVS) condition with improved efficiency. A laboratory prototype has been implemented on a DSPIC2010 controller. The experimental results are presented to validate the proposed control scheme.

Automatic Fluorescent Lamp Detection Technique for Electronic Ballasts

Due to the variation of fluorescent lamp power rating and types, the specified ballast could be used to meet the appropriate operating power. Generally, electronic ballast drives fluorescent lamp with fixed operating frequency. Such method can be used for only the designed lamp type and power rating. An operation of this type of ballast with mismatch lamp will cause damage on the lamp and/or ballast. This paper presents an Automatic Fluorescent Lamp Detection for Electronic Ballasts. This proposed method enables the ballast to determine the connected lamps power rating and drive the lamp with proper operating frequency. The experimental results show 100% accuracy on the 3 power rated T8 lamps which are 18 watt, 32 watt and 36 watt.

A Study of Effects of Stochastic Wind Power and Load to Power System Stability Using Stochastic Stability Analysis Method

The stochastic stability analysis method is proposed in this paper to investigate the small signal stability (SSS) of the single machine infinite bus power system. An induction generator wind turbine model is examined including frequency dependent load. The first integral energy function method is applied based on Lyapunovs stability and the theory of stochastic stability. This proposed method can investigate effects of stochastic wind power and load quantitatively while the general deterministic methods cannot.

Automatic fluorescent lamp detection for electronic ballasts based on operating frequency and phase shift compensation

Generally, an electronic ballast drives a fluorescent lamp at fixed operating frequency or by regulating the lamp current. Such methods can be used for the designed lamp type and power rating. This paper presents an automatic fluorescent lamp detection for electronic ballasts based on operating frequency and phase shift compensation. The classification of lamp power rating is based on the possibility weight distribution of the lamp operating frequency. Moreover, the phase shift compensation is also included in the detection algorithm in order to address the variations of the resonant circuit parameters. The results from simulation and experiment verify that an electronic ballast with the proposed detection algorithm can automatically detect and drive the fluorescent lamp at the correct lamp power rating.

LCCL series resonant inverter for ultrasonic dispersion system with resonant frequency tracking and asymmetrical voltage cancellation control

This paper presents a high efficiency LCCL series resonant inverter for ultrasonic dispersion system with resonant frequency tracking and asymmetrical voltage cancellation control. With the proposed control, the operating frequency of the inverter is automatically adjusted to track the resonant frequency under load parameter variation due to surrounding condition. The zero-voltage switching (ZVS) is maintained throughout the operation. The output power is controlled using the asymmetrical voltage cancellation (AVC) technique. A full-bridge hardware prototype is constructed and the control algorithm is implemented using an STM32F4 microcontroller. Computer simulation and hardware experiment are provided at an operating frequency range of 37-42 kHz and the output power of 30-125 W.

Steady-State Analysis of ZVS and NON-ZVS Full- Bridge Inverters with Asymmetrical Control for Induction Heating Applications

This paper presents a steady-state operation analysis of full-bridge series-resonant inverters focusing on the distorted load current due to low-quality-factor resonant circuits in induction heating and other applications. The regions of operation based on the zero-voltage switching (ZVS) and non-zero-voltage switching (NON-ZVS) operations of the asymmetrical voltage-cancellation control technique are identified. The effects of a distorted load current under a wide range of output powers are also analyzed for achieving a precise ZVS operating region. An experimental study is performed with a 1kW prototype. Simulation and experimental studies have confirmed the validity of the proposed method. An efficiency comparison between the variable frequency method and the conventional fixed-frequency method is provided.

Voltage Sag Compensation Performance by DSTATCOM with Series Inductor and Energy Storage

In this paper, the voltage sag compensation performance by distribution static synchronous compensator (DSTATCOM) is presented. The DSTATCOM injects the current into the system so that the load voltage can be instantaneously compensated. The three types of current injection schemes are described. The voltage sag compensation capability by DSTATCOM with different configurations is explained and analyzed. Simulation results confirmed that DSTATCOM system with additional series inductor and energy storage can improve voltage sag compensation performance and reduce the compensator rating as well.

A power control of three-phase converter with AVFSVC control for high-power induction heating applications

This paper presents a three-phase output power control scheme of an induction heating (IH) system using an automatic variable-frequency symmetrical voltage-cancellation (AVFSVC) control technique. The power control is based on the instantaneous output power, filtered and compared with a reference value. The phase angle a is automatically varied depending on the power requirements where the low-power operation is achievable. The high power inverter is operated under zero voltage switching (ZVS) condition by a phase locked loop (PLL) control for maximum overall system efficiency and low switching loss. Calculation and Simulation results are provided in the paper to validate the proposed control method with the output power ranging from 0.024 to 15.63 kW under 15.03 to 16.67 kHz operation frequency.

Design considerations of DSTATCOM for voltage sag compensation without interaction

DSTATCOM can compensate voltage sags by injecting the reactive power into the distribution system; however, the false compensation due to the interaction with system could occur. In this paper, the design considerations of DSTATCOM for voltage sag compensation have been studied. The voltage sag compensation performance with different current injection schemes is briefly explained and the interaction is described. Then, the design of DSTATCOM system and controller for voltage sag compensation is proposed. Simulation results confirmed that the proper design of DSTATCOM system can achieve the good voltage sag compensation performance without interaction with the system.