Environmental Engineering Reference
In-Depth Information
80 kW
80
V
system
for I
sys
= 250 A
70
60
50
40 kW
40
30
20
10 kW
10
3.5 kW
0
14 V (12 V)
Conventional
42 V (36 V)
Low power hybrid
150 V (144 V)
Mild hybrid
330 V (288 V)
Full hybrid
System voltage (V)
Figure 4.20 (a) Power throughput capability versus voltage and (b) cable size
In the US the National Electrical Code (NEC) article 625 defines all require-
ments for electric vehicle (PHEV, BEV) charging systems including cabling, con-
nectors, disconnects, equipment ratings, ventilation requirements of charging
equipment and much more - for example, the proper locations of charging equip-
ment, cables and ventilation system for residential garage charging station. Speci-
fically, the vehicle supply equipment cable must be type EV, EVJ, EVE, EVJE,
EVT or EVJT flexible cable. Article 400, Tables 400.4 and 400.5, of the NEC
provides detail on cable gauge (AWG), voltage class (
<
600 V to 2 kV), the type
insulation, outer covering, insulation thickness required and recommendation for
damp and wet locations.
4.3.1 Switch technology selection
Power electronic switching components are classified by process technology as
originating from two layer, three layer or four layer designs. The semiconductor
diode, for example, is a two layer planar device consisting of p-type and n-type
doped silicon formed by a diffusion process. Two layer devices have a single p-n
junction. Three layer planar devices include all the transistors in use today and have
two junctions. Current control is realized at the low voltage junction at which
carriers are injected into the device and output at a second, higher voltage, junction
at which the injected carriers are collected. Because of the vast difference in vol-
tage levels between the injecting and collecting junctions, for a given amount of
current, high power amplification occurs. Four layer, three junction, devices are
categorized as thyristors. 'Thyristor' is a name derived from early work on gas tube
Thyratron switching elements at the General Electric company in the 1920s that is
taken from the Greek Thyra for fire and tron for work. Thyristors are then 'thyra-
tron's' plus 'transistors'. Because there are two junctions from which carriers are
injected in thyristors, and a single high voltage collector junction, the devices have
