1.13.2. Parallel connection of double three-phase bridge rectifiers
Conditions: α=0, Ld=∞, La=0
A B C
Ld
Rd
Id
i||1A
еdII
5|
3|
1|
i|2A
i||1C
i|1A
i||1AC
↑
i1A
I
II
i||2A
6|
4|
2|
5||
2||
6||
3||
4||
1||
Lур
еdI
Figure 1.44
Line voltages of transformer are displaced on 30 degrees due to connection of transformers of the first bridge - Y/Y, the second - ∆/Y.
The principle of operation is similar to double three-phase star with the current-balancing reactor (CBR). CBR takes up a difference of variable components ed1 and ed11.
0
0
ud
ud
0
uk
еd
ud
edI
edII
Figure 1.45
For double three-phase bridge with CBR
Hence, typical power CBR is insignificant.
Average value of the rectified voltage is
Instantaneous voltage by the current-balancing reactor is
Frequency of a voltage by the current-balancing reactor
.
Instantaneous voltage by an output of the circuit
.
Frequency of a load voltage
.
Midvalue of a load current
,
where
- average value of a rectifier current complete sets I
and set II
accordingly.
Construction of a current i1A
is similar to construction the primary current for 2 series bridges,
but instead of Id
will be
.
It is expedient to apply this set for the high current load.
1.14 Operation of the rectifier with opposite- emf
This operation of rectifier circuits meets in electrochemistry, the electric drive. For example: electrolyte pots, accumulators, DC-motors. The main feature of such consumers - presence own EMF Ео witch is directed against Ud.
TP
e2
i1
id
iV1
Ud
VD2
Rd
о ~ U1 о
Ld
VD1
Eo
- +
Figure 1.46
1.14.1. Operation of the half-wave rectifier with center tap with opposite- emf and active load
Conditions:
U
i
i
е2b
е2а
iV1
ud=ed
id
λ
λ
d,
id
Figure 1.47
Id flows only then, when Ud > Eo
This current is intermittent.
Average rectified current
Average current through the thyristor
.
RMF value of a current through the thyristor and a secondary winding of the transformer
RMS value of a current through a primary winding of the transformer
.
The peak-inverse voltage
.