Photovoltaic Systems Engineering Electronic Control Devices (ECDs) SEC598F17 Photovoltaic Systems Engineering Session 14 Electronic Control Devices (ECDs) Charge Controllers Inverters October 05, 2017

Session 13 content Charge Controllers Inverters Purpose, utility Operation, reliability, failure mechanisms

Learning Outcomes Introduction to the power electronics used in PV systems Recognition of the importance of controllers and inverters to the operation of certain PV systems

PV Systems – Charge Controllers Pulse Width Modulation (PWM) – Duty Cycle Vm v(t) Vavg ton toff time

PV Systems – Charge Controllers Pulse Width Modulation (PWM) – Duty Cycle

PV Systems – Charge Controllers Pulse Width Modulation (PWM) – Duty Cycle

PV Systems – DC-DC converters Boost converter The transfer characteristic is: en.wikipedia.org/wiki/Boost_converter

PV Systems – DC-DC converters Boost converter ON OFF

PV Systems – DC-DC converters Buck converter The transfer characteristic is: en.wikipedia.org/wiki/Buck_converter

PV Systems – DC-DC converters Buck converter

PV Systems – DC-DC converters Buck-Boost converter The transfer characteristic is: en.wikipedia.org/wiki/Buckboost_converter

PV Systems – DC-DC converters Buck-Boost converter

PV Systems – DC-DC converters Summary Boost Converter Buck Converter Buck-boost Converter

PV Systems – DC-DC converters Summary Boost Converter Toyota Prius LED Lamps Buck Converter Impedance matching Charge controllers Buck-boost Converter

PV Systems – Charge Controllers 12V, 24V, 48V 45A, 70A, 100A 1600W, 3200W www.morningstar.com

PV Systems – Charge Controllers Charge controller block diagram Isolation of PV array and battery Protection from overcharging Protection from deep discharging www.morningstar.com

PV Systems – Charge Controllers Charge controller operation www.morningstar.com

PV Systems - Maximum Power Point Tracking The PV system produces electrical power and is best utilized when the maximum power produced can be fully delivered to the electrical “load” – this can only happen when the power source and the power load “match” C.S.Solanki, Solar Photovoltaic Technology and Systems

PV Systems - MPPT Other representative electrical loads

PV Systems - MPPT An approach to assuring a better match is the use of Maximum Power Point Tracking (MPPT) – an electronic technique that moves the operating point along the maximum power hyperbola (I*V = constant) associated with the PV array until it intersects the electronic load IV characteristic

PV Systems - MPPT IMPPT Imp VMPPT Vmp

PV Systems - MPPT Imp IMPPT MPPT Vmp VMPPT

PV Systems - MPPT Perturb and Observe PV operating points from P&O algorithm N.Fermia et al., Power Electronics and Control Techniques for Maximum Harvesting in PV Systems

PV Systems - MPPT Perturb and Observe Time domain behavior N.Fermia et al., Power Electronics and Control Techniques for Maximum Harvesting in PV Systems

PV Systems - MPPT Perturb and Observe P&O flowchart

PV Systems - MPPT Perturb and Observe N.Fermia et al., Power Electronics and Control Techniques for Maximum Harvesting in PV Systems

PV Systems - Inverters The inverter is the essential electronic system that converts the DC electrical output from the PV array into the AC electrical input for the residence, national electrical grid, and so on INVERTER DC input AC output

PV Systems - Inverters Heart of the inverter – the “H-bridge”

PV Systems - Inverters The H-bridge in operation

PV Systems - Inverters The output of the inverter is controlled by pulse width modulation (PWM)

PV Systems - Inverters State of the Art Inverters: High efficiency – 98% or higher Dual independent MPPT systems Integrated DC disconnect and combiner inputs No fans or electrolytic capacitors

PV Systems - Inverters J.M.Jacob, Power Electronics: Principles and Applications