This paper introduces a DC-AC inverter design that operates stand alone to deliver power from solar photovoltaic (PV) to the load directly without going through the battery. In batteryless solar PV, the output voltage of solar PV always varies according to solar irradiation, temperature, so that it becomes a challenge in modelling DC-AC inverter with constant output voltage. The design consists of a boost converter, h-bridge switching and driver, and LC filter to generate sinusoidal ac voltage as output to load. To ensure a constant inverter output voltage, the design equipped by a close loop PI controller based on voltage control mode. The design modelled and simulated by PSIM. PV dc input was set variation according to the irradiation value (W/m2) and the output connected to a load that has rated voltage of 220 Vac and 3.4 A of nominal current. The results show that in the irradiation variation 600-1500 W/m2, the inverter was able to maintain the output voltage of 220 Vac ± 0.91%, 50 Hz which is still in the voltage range based on standard. The efficiency produced by DC-AC inverter 97.7 % at 600 W/m2 and 83.6 % at 1500 W/m2.
This paper discussed the influence of tightness or contacts pressure on copper busbar joints to determine changes in the value of the initial contact resistance and the maximum temperature at the joint due to high current load. The test sample was copper busbar 3 x 30 mm with configuration of bolted overlapping joint. Increasing contact pressure at the joint was measured to find out its effect on the value of contact resistance. The applied pressure was 6 to 36 MPa. Procedure of contact resistance measurement refer to the ASTM B539 standard using four-wire method. The sample subsequently loaded with the current of 350 A for 60 minutes and the maximum temperature at the joint was measured. The result showed that increasing contact pressure at the busbar joint will reduce the contact resistance and maximum temperature. The increase of contact pressure from 6 to 30 MPa causes decreasing contact resistance from 16 µΩ to 11 µΩ. Further increasing of contact pressure more than 30 MPa did not affect the contact resistance significantly. The lowest temperatur of busbar joint of 54°C was reached at a contact pressure of 36 Mpa.
Temperature is one of the parameters other than radiation that can affect the performance of photovoltaic (PV) in relation to the output power and efficiency. This paper discusses the design of the PV cooling system using waters pray that controlled automatically. The temperature of the PV on the sensor as input to the controller and the output is the switch settings to turn on/off the pump in spraying water to the surface of the PV panel with the intention that the PV is always maintained at normal temperatures. The system was tested simultaneously on 4 PV panels @ 100Wp by involving PV without a cooling system with the same capacity during the day and the result was compared. Based on the results of PV temperature measurements in relation to the output power shows that PV with a cooling system generates higher output power than PV without a cooling system. By taking into account the involvement of power consumed by the cooling system consists of a controller and pump, the efficiency of PV rises slightly to 1.07 times.
<p>One of the several failure cases in electric vehicle could be occured at the Lithium-ion (Li-ion) battery connectors when loaded by high current. This failure caused by bad contact of connectors so that the contact resistance increase and lead to high power losses, overheating, and it can even cause a fire hazard. This paper presents a thermal distributions of Li-ion battery connectors on different coating material in relation to the value of contact resistance. There were two test samples of modeled: copper connection without coating and copper connection with silver coating. Each sample was loaded by the DC current of 350A, and temperature at the connection was measured until steady state condition reached and simulated by Solidwork software. The results show that the temperature at the inside contact area was higher than the outside contact area of connection that appears caused by higher of the contact resistance. Both measurement and simulation results have same tendency that copper connection with silver coating having lower contact resistance, lower maximum temperature, and lower losses about 32 % than copper connection without coating. Silver coating can be considered as other alternative to prevent overheating, high losses, and failure in Li-ion battery connector.</p>
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