System dynamic model and charging control of lead-acid battery for stand-alone solar PV system
- New Energy Center, Department of Mechanical Engineering, National Taiwan University, Taipei (China)
The lead-acid battery which is widely used in stand-alone solar system is easily damaged by a poor charging control which causes overcharging. The battery charging control is thus usually designed to stop charging after the overcharge point. This will reduce the storage energy capacity and reduce the service time in electricity supply. The design of charging control system however requires a good understanding of the system dynamic behaviour of the battery first. In the present study, a first-order system dynamics model of lead-acid battery at different operating points near the overcharge voltage was derived experimentally, from which a charging control system based on PI algorithm was developed using PWM charging technique. The feedback control system for battery charging after the overcharge point (14 V) was designed to compromise between the set-point response and the disturbance rejection. The experimental results show that the control system can suppress the battery voltage overshoot within 0.1 V when the solar irradiation is suddenly changed from 337 to 843 W/m{sup 2}. A long-term outdoor test for a solar LED lighting system shows that the battery voltage never exceeded 14.1 V for the set point 14 V and the control system can prevent the battery from overcharging. The test result also indicates that the control system is able to increase the charged energy by 78%, as compared to the case that the charging stops after the overcharge point (14 V). (author)
- OSTI ID:
- 21318383
- Journal Information:
- Solar Energy, Vol. 84, Issue 5; Other Information: Elsevier Ltd. All rights reserved; ISSN 0038-092X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
14 SOLAR ENERGY
LEAD-ACID BATTERIES
CONTROL SYSTEMS
CONTROL
BATTERY CHARGING
ELECTRIC POTENTIAL
LIGHTING SYSTEMS
SOLAR ENERGY
ALGORITHMS
SIMULATION
AVAILABILITY
CAPACITY
DESIGN
FEEDBACK
CHEMICAL REACTION KINETICS
SOLAR BATTERY CHARGERS
Stand-alone solar systems
Battery charge control