1. Photovoltaic Systems Engineering Session 10
SEC598F18
Photovoltaic Systems Engineering
Session 10
Electronic Control Devices (ECDs), Part 1
Charge Controllers
October 01, 2018

2. Session 10 content Charge Controllers Purpose, utility
Operation, reliability, failure mechanisms

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

4. PV Systems - Batteries Lead Acid Battery
Lead acid batteries are less prone to electrolysis and sulfation if the charging protocol does not employ a constant rate. The optimized charging profile looks like this:
This current profile
is produced by a
“charge controller”

5. PV Systems – Charge Controllers
A simplified version of a “stand-alone” system
that transfers DC electrical energy to a storage device

6. PV Systems – Charge Controllers
The charge controller is an essential electronic component in any PV system that employs battery storage
The charge controller carries out some important functions:
It accepts the DC power from the PV array
It directs the DC power to the battery array matching the optimal charging procedure, as needed
It directs the DC power to the inverter for the AC standby loads or grid connection, or to DC electrical loads

7. PV Systems – Charge Controllers
These features must be met in the choice of charge controller:
Its DC output must match the battery array voltage
Its DC output must normally supply enough current to recharge the battery array in one day
Its DC current directed to the inverter must not exceed the allowable inverter input
There are quite a few Charge Controller manufacturers with very high quality products

8. PV Systems – Charge Controllers
Pulse Width Modulation (PWM)
An electronic technique that is used to:
switch from an input dc voltage at one level to an output level at another level, as in DC power supplies
carry out the ‘perturb and observe’ process to find the maximum power point
generate time dependent voltages that closely approximate sinusoidal or other waveforms

9. PV Systems – Charge Controllers
Pulse Width Modulation (PWM)
AC-DC
converter
DC-DC
switching
power
supply ac
line
voltage
rectifier

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

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

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

13. PV Systems – DC-DC converters
Boost converter ON
OFF

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

15. PV Systems – DC-DC converters
Buck converter

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

17. PV Systems – DC-DC converters
Buck-Boost converter

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

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

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

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

22. PV Systems – Charge Controllers
Charge controller operation

23. 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