Mission Profile Based Optimization of a Synchronous-Buck DC-DC Converter for a Wearable Power System

A Wearable Power System (WPS) is a portable fuel-to-electrical energy converter that is carried on the body and is able to supply an average of 20 W for 4 days and has a total weight of less than 4 kg. Due to limited total weight of the system, each system part must have the highest efficiency to weight ratio. This paper presents the optimization of a synchronous buck DC-DC converter that is used to regulate the variable power source to a constant 14 VDC for the load. Higher switching frequency leads to smaller components and low weight, but at the same time, to higher losses that are compensated through additional fuel weight. If low switching frequency is applied, the weight of the converter will increase due to a larger inductor, but the power losses will be lower. Therefore, an optimal switching frequency should exist that results in the total weight of the DC-DC converter and additional fuel being a minimum. The paper first explains the proposed solution for WPS, the load pattern that is used to test the system and then the algorithm that decides on the number of converters to be used and how to find the optimal switching frequency. Additionally, two prototypes have been constructed. First prototype has nominal power of 20 W and is used in the analysis regarding the optimal number of converters. The second one has rated power of 200 W and it is built to support the conclusions based on the optimization process

Real-time optimization of an active filter's performance

Recent advances in power electronics have meant that many loads now draw a distorted current from the power supply. For the same real power consumed, the apparent power for the distorted load is greater than the equivalent sinusoidal load. A real-time active filter optimization algorithm has been implemented in a TMS32OC30 DSP, with the aim of maximizing the monetary savings from active filtering by reducing the apparent power consumed at the point of supply. As the basis for this optimization a savings function which takes into account active filter efficiency, the cost of energy, and the supply and load current distortion before and after filtering, has been derived. A simplex optimization technique, which is able to find the optimum operating point even under varying load conditions, is used to maximize these energy savings

The steady-state performance of a controlled current active filter

An active filter that uses a high-frequency D-class asynchronous switching inverter for power system current distortion compensation is described. The distortion compensation technique involves deriving a signal corresponding to the distortion component of load current, and inverting and amplifying this signal for addition back to the supply current to cancel the load current distortion. A synthetic sinusoid is used to determine the distortion component in the time domain. Extensive computed and experimental results, illustrating the system’s steadystate performance and ability to reduce the current harmonic distortion components, are presented. An intelligent controller is proposed to maintain the active filter’s performance at the optimal operating point under varying load conditions

Design Of An Intelligent Controller For An Active Filter

A technique of achieving both active current distortion compensation and power factor correction is briefly described. The active filter has been evaluated using a single phase prototype circuit that provides up to 2 kVA of distortion compensation. There is an optimum operating range for the active filter which is determined by the choice of average switching frequency and inverter DC bus voltage. Experimental results, illustrate the filter's ability to reduce the current harmonic distortion components, are presented On the basis of these experimental results, the design of an intelligent controller, using a Texas Instruments TMS32OC30 Digital Signal Processor (DSP), for the active filter is proposed. Such an intelligent controller should be able to determine the most eficient average switching frequency and inverter DC bus voltage to achieve the required current distortion compensation and/or power factor correction

A controlled current inverter for active distortion compensation and power factor correction

A technique of achieving both active current distortion compensation and power factor correction is described. A signal corresponding to the phase corrected distortion component of load current is amplified by a high frequency asynchronous switching inverter for addition back to the supply current to cancel the load current distortion and to provide power factor correction Current distortion compensation and power factor correction can be provided either separately or combined to provide total compensation. Experimental results, illustrating the system's ability to reduce the current harmonic distortion components and provide power factor correction, are presented. The design of an intelligent controller, using a TMS32OC30 digital Signal processor, for the compensation system is also discussed

DC-Bus Signaling: A Distributed Control Strategy for a Hybrid Renewable Nanogrid

A dc nanogrid is a hybrid renewable system since renewable sources supply the average load demand, while storage and nonrenewable generation maintain the power balance in the presence of the stochastic renewable sources. The system is power electronic based, with converters being used to interface both the sources and loads to the system. The nanogrid is controlled using dc-bus signaling (DBS), a distributed control strategy in which the control nodes, the source/storage interface converters, induce voltage-level changes to communicate with the other control nodes. This paper explains the control structure required for the converters to permit the use of DBS, and explains a procedure for implementing a system-wide control law through independent control of the source/storage interface converters. Experimental results are presented to demonstrate the operation of this novel control strategy