The focus of this paper is on a simple half-bridge converter that performs power factor correction (PFC) using current sensorless control. Current sensors increase cost, auxiliary power required, conduction losses, and volume of the PFC converter. Moreover, measurement of high frequency current is demanding, especially in cost-sensitive applications. The PFC converter proposed combines simple half-bridge topology and improved current sensorless-control algorithm that takes into account conduction losses. These losses influence volt-second balance in the input inductor and result in distorted grid current shape. Their effect is especially evident in half-bridge converter, where input inductor operates with high voltage swing. The current sensorless control method proposed compensates this influence and allows achieving sinusoidal current shape. First, the phenomenon of current distortion was shown with numerical simulation in PSIM package. Experimental prototype rated for 350 W power was built to verify theoretical and simulation results. Experimental results are in good agreement with those obtained with simulation and theoretically. The PFC converter proposed features low cost of realization and can be used in consumer equipment for connection to the grid. accordance with real transistor parameters (Table II), the difference is only 24 ns that is 0.06% of switching period that is less than precision of the PWM module utilized in the experiments and thus can be neglected. The diode reverse recovery losses are not influencing volt-second balance of the inductor, but are a matter of capacitor discharge currents, and consequently can be neglected. Figure 7. Simulation results considering conduction losses: (a) light load condition-IM = 0.3 A; THD(Ic) = 91.2%; THD(Ig) = 2.9%; and (b) high load condition-IM =;4 A; THD(Ic) = 12.2%; THD(Ig) = 0.6%.Figure 8. Simulation results without consideration of conduction losses: (a) light load condition-IM = 0.3 A; THD(Ic) = 93.2%; THD(Ig) = 3.2%; and (b) high load condition-IM = 4 A; THD(Ic) = 48.5%; THD(Ig) = 37.4%.

-Electrical grid modernization concept promotes the use of DC subgrids in order to improve efficiency, minimizing energy conversion count in the source-to-load chain. The present paper discusses an average current sensorless control algorithm for proposed bidirectional AC/DC converter, which is based on a dual half-bridge topology with common neutral wire that is not commutating during converter operation. The proposed current sensorless control algorithm has been obtained analytically for rectification, grid-tied and stand-alone inverter modes. The average value of inductor current tracks the reference current signal with constant switching frequency. Two control functions for inductor's discontinuous and continuous current modes have been defined for each of the operation modes, and a sensorless transition between DCM and CCM modes has been stated. The proposed sensorless control algorithm has been also adapted for use with LCL input filter. The results of simulation in the PSIM software approved the analytical model, keeping the average inductor current to follow the reference value in inductor discontinuous and continuous conduction modes. Experimental investigation of the proposed current control algorithm provided similar results confirming the discussed theory.

The current control is becoming a challenging task for switched mode power supplies, while current sensorless control solutions can avoid the instantaneous current measurements that has been applied for mostly used power factor correction topologies. However, multilevel type of converters haven't been considered to use with current sensorless control (CSC). Hereby, the CSC is applied to three level neutral point clamped converter, where special volt-second balance is applied to inductor in order to keep average inductor's current value to track the reference signal during both discontinuous and continuous current modes. The explanation of post-fitting and pre-fitting current trajectories is done that are necessary for proper transition between voltage levels. Experimental results have confirmed the theoretical model. Keywords-sensorless control; current control; pulse width modulation inverters978-1-4799-6301-0/15/$31.00 ©2015 IEEE

Abstract. An increased number of distributed small generators connected to the power grid allows higher total efficiency and higher stability of electrical power supply by exporting energy to the grid to be achieved during peak demand hours. On the other hand, it poses new challenges in structuring and developing the control approaches for these distributed energy resources. This paper proposes an improved method of real-time power balancing targeted to reaching long-term energy management objectives. The novel long-term energy management technique is proposed, that is based on load categorization and regulation of energy consumption by regulating electricity price function estimated with the proposed mathematical model. The method was evaluated by a Lab-VIEW model by simulating various types of loads. The price function for the defined energy generation pattern from renewable energy sources was obtained.Keywords: Intelligent Distribution Grid, Nanogrid, Energy Management, Instantaneous Power Balancing, Short-Term Energy Management, Pricing. IntroductionThe dynamic of worldwide installed power utilizing renewable energy sources (RES) is increasing year by year [1], showing global awareness of climate change and the footprint of human behavior on the nature: like mining activities that change the landscape and damages caused by oil plants. Another problem is related to the total effectiveness of energy from the primary fuel. It relates to the total system efficiency of energy delivery to the end-user from a mining site, which includes energy losses at middle stages, like use of energy at the mining stage, energy conversion losses, transmission (mechanical and electrical) losses, as well as end-device efficiency. Consequently, locally generated energy (especially from renewable energy sources) is preferable because it excludes most of the mentioned losses. As more distributed small generators are connected to the power grid, higher total efficiency and higher stability of electrical power supply by exporting energy to the grid during peak demand hours. On the other hand, it poses new challenges in structuring and developing the control approaches for these distributed energy resources.