F. Danang Wijaya

Battery state of charge estimation by using a combination of Coulomb Counting and dynamic model with adjusted gain

Majority of electric vehicles depend on batteries that require a Battery Management System (BMS). Increasing accuracy of State of charge (SoC) estimation was crucial. The uncomplicated method for SoC estimation is Coulomb Counting (CC), however it has drawback in information of previous SoC initial value and tolerate with error propagation. Dynamic model equipped with integral controller can increase accuracy of the CC method. In this paper adjusted gain of the integral controller is proposed to further improve performance of SOC estimation. The Li-ion battery was modelled using first order RC battery model. Least square method is used to determine parameter of battery model. The simulation results show that the combination of CC and dynamic model with fixed integral gain could increase accuracy of the CC algorithm approximately to 87%, and the mixed algorithm with adjusted integral gain could further increase it to around 89%.

Optimal configuration of PV-Wind turbine-grid-battery in low potency energy resources

As an increasing of load demand, scarcity of fossil fuel and green house effect, utilization of renewable energy resources such as solar and wind energy are done seriously. The problem rises when potency of them is far smaller than load demand and the high difference between wind velocity profile and solar radiant intensity and load profile is happened. Its make excess electricity to be higher so the electrical production cost to be higher too. The purpose of this research is designing optimal configuration of microgrid PV-Wind turbine-Grid-Battery through optimization of load capacity to reduce excess electricity. Some parameters of optimal configuration are used to evaluate them, namely electrical production cost, reliability, CO2 coming from life cycle assessment, area of installation and unemployment reduction. Software HOMER version 2.68 Beta from NREL is used to simulate alternative configuration of microgrid. The results show that distribution total load into some sub-microgrids gives the positive impact, namely smaller electrical production cost, higher reliability, minimum CO2, relative smaller area of installation and unemployment reduction.

Reducing induction motor starting current using magnetic energy recovery switch (MERS)

A high transient current occurring when starting up an induction motor can lead to voltage dip. This paper proposes a method of induction motor soft-starting by using magnetic energy recovery switch (MERS). The MERS is a series compensation device and is able to control motor terminal voltage. The design of MERS control system is described. The starting current produced can be controlled by setting up the MERS firing angle. Experimental results confirmed that starting current can be reduced by applying MERS in series with induction motor.

Six-step commutation with round robin state machine to alleviate error in hall-effect-sensor reading for BLDC motor control

Hall-effect sensors are commonly applied in brushless direct current (BLDC) motor control for rotor position detection. By knowing the exact position of the rotor, inverter could supply energy in synchronize to the BLDC motor state. As the motor is categorized as synchronous motor, those sensors are vital. Working out of synchronization not only makes drive system less efficient but also threaten the inverter as current requirement will be increased. Unfortunately, the sensor works in harsh environment where high current, high temperature, and high vibration are exist. Those conditions result in some incorrect position detections. In order to improve the hall-effect position accuracy, in this paper, a simple finite state machine (FSM) called round robin technique is implemented. This technique along with conventional R-C filter in the sensor line successfully suppresses error in the rotor position detection. This results in higher inverter reliability and smoother motor operation.

DC-DC converter as power supply of battery charger 100 V 300 W using 25 kHZ switching frequency

Dc-dc converter with full-bridge topology is the best option to use as power supply with high power and high voltage level. Full-bridge topology combines the voltage properties of half-bridge topology and the current properties of the push pull topology. It is an elaboration from buck converter topology with isolated transformer as galvanic isolation. The main components of the dc-dc convert full-bridge are inverter, high frequency transformer, high frequency rectifier and filter. The inverter is designed in a full-bridge topology that can transfer power greater than the half-bridge. Switching mode that used in this research is phase-shifted PWM ZVT. This switching mode will reduce the loss of switch. High frequency transformer is used to raise the level of output ac voltage from inverter that has a high frequency, the transformer also has smaller dimensions than a common transformer with the same capacity. Rectification of high frequency output transformer is done by a full-bridge rectifier using fast recovery diode. In this study, dc-dc converters used as a power supply for battery charger that is loaded with bulb lamps with 300 W power needed and also eight pieces of lead-acid batteries 12 V in series. The results showed that the efficiency of the converter dc-dc battery charger designed achieve efficiency about 95% for certain circumstances.

Teaching the large synchronous generator dynamic model under unbalanced steady-state operation

This paper presents an attractive approach for teaching the large three-phase synchronous generator under unbalanced steady-state condition of the 500 kV EHV Jawa-Madura-Bali (or Jamali) system to which it is connected using Matlabs Graphical User Interface (GUI) capability. Whereas two unbalanced steady-state conditions of the grid are obtained by setting all of IBTs (or inter bus transformers), the Jamalis grid loads, into load imbalance of 5% and 10%. The main motivation for such a study is to develop user-friendly software for better teaching the behavior of the generator which is connected to the grid when unbalanced loads are present. An example is given to demonstrate the usefulness of the developed tool.

Design optimization of Quasi-flat linear PM generator for wave energy converter in south coast of Java using flower pollination algorithm

South coast of Java has been highly preferred as the placement location of wave energy converter, due to its relatively huge energy potential. Furthermore, linear permanent magnet generator (LPMG) has became one of the popular methods to convert wave energy to electrical energy. Based on the shape of stator core, there are several models of LPMG. Quasi-flat LPMG is one of them, which has rectangular stator core shape. In this paper, the quasi-flat LPMG would be designed and optimized. The design considered wave characteristics in the south coast of Java. Meanwhile, the optimization was performed to minimize resulted copper loss for equal output power. To achieve the optimization goal, flower pollination algorithm (FPA) was used. This algorithm continuously adjusts several geometrical parameter of the LPMG by certain mechanism until the objective function is met. The results showed that the optimization could reduce the resulted copper loss of about 71.95%. It also increased the electrical efficiency from 83.2% to 95.28%.

Cost-based power distribution optimization scheduling in microgrid

Renewable energy is one of the solutions of energy limitation problem in the world. It often works with some independent plants of renewable energy that work together under the circumstances of center control. The renewable energy system (RES) such as photovoltaic (PV), wind turbine (WT) has a serious lack of stability power output or uncertain power. Because of that, the microgrid system (MGs) is built to optimize the power flow and minimize the impact of energy fluctuation. Not only about the power flow, but also the cost analysis is important in order to find the optimized power resource combination to reduce cost. This paper proposes a cost-based power distribution scheduling optimization in a microgrid. The power resource conducted from PVs, WT, biomass, and storage system performed by 0–1 Knapsack problem formula. In order to find the optimized cost, genetic algorithm (GA) is used. The output shows the optimized cost, output power which depends on energy load and true power resource combination of microgrid scheduling.

Simulation of modified tubular linear permanent magnet generator for wave energy conversion in Indonesia

Conventional tubular linear permanent magnet generator (LPMG) is composed of permanent magnets which are placed in translator, and stator which is made of iron. However, this topology suffers from the relatively huge cogging force due to the interaction between the magnet and the iron, also a large core losses from hysteresis and eddy current. To reduce the force and the losses, modified design of LPMG was proposed by reducing the iron proportion of the stator. The modified tubular LPMG would be applied for 1 kWp wave energy power plant in the south coast of Java, Indonesia. The reduction of the iron was then compensated by increasing number of stator winding turn to maintain the output power as desired. Resulted design was then simulated by using finite element magnetic software of FEMM to check the output values based on magnetic flux distribution. The results of the simulation showed that the modified design needs 11.4% more stator winding turns to produce equal power. However, the cogging force and the mechanical loss decreases by 24.7%. The design also reduces 57.2% of both hysteresis loss and eddy current loss, and 57.1% of weight.

Comparison of two high frequency transformer designs to achieve zero voltage switching in a 311/100 v 1 kW phase-shifted full-bridge DC-DC converter

In this study, two high frequency transformer designs have been made in order to achieve zero voltage switching (ZVS) condition in a phase-shifted full-bridge inverter for dc-dc converter from 311 V input to 100 V output. One transformer was implemented using conventional winding technique while the second transformer was using interleaved technique. Simulation has shown that the second transformer gives the best result. Efficiency of up to 94% with full load regulation of 92% is achievable. This result can be achieved by adding external inductance of 26 μH.