Battery charger NG1
D01273-00
4
Operating principle
The battery charger considerably affects battery life and performances, which is the main part of every
electric vehicle.
A non controlled traditional battery charger (rectifier) provides a simple
direct AC/DC
conversion.
Disadvantages of this solution are:
•
Low efficiency
•
Large physical size
•
Long charge times
•
Charge depends on changes in the mains supply (with
overcharge danger in the final charge phase)
In modern battery chargers these disadvantages are solved with an
indirect AC/DC
conversion, by
passing through an intermediate DC/DC conversion.
This is the usual method of operation for the
SMPS (Switching Mode Power Supply) at
high power. This solution gives a good
performance for minimum costs and physical
dimensions using switches more faster and
powerful (modern technology).
The main advantages of this solution are:
•
High efficiency
•
Reduced dimensions
•
Short charge times
•
Charge independent from the changes of the mains supply
•
Electronic control that provides the desired charge curve
The advent of electrical problems (due to commutation) has imposed the introduction of adequate filtering
to satisfy requirements of EMC 89/336/EEC directive for electromagnetic compatibility.
Block
Diagram
STAGE
POWER
E
L
N
F1
F2
LOGIC
CONTROL
FILTER
FILTER
FILTER
RECTIFIER
RECTIFIER
RECTIFIER
AND
AND
AND
FILTER
FILTER
EMI
EMI
Battery
i
v
DC
AC
Battery
i
v
DC
DC
DC
AC
