1. Photovoltaic Systems Engineering Electronic Control Devices (ECDs)
SEC598F17
Photovoltaic Systems Engineering
Session 13
Electronic Control Devices (ECDs)
Charge Controllers
Inverters
October 03, 2017

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

3. 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

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

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