Droop control using three-phase full-bridge inverter overall system structure shown in Figure
2.1
FIG. Main power circuit is a three-phase full-bridge
Topology,
V
dc
DC input voltage, then the midpoint of the bridge arm
LC
filter,
L
c
To ensure that the inverter output is inductive and external connections
Inductance; inverter output voltage filter capacitor terminal voltage
v
o
Three-phase filter inductor current
i
L
Flows into the micro-grid inverter bus
Output current
i
o
. Loop power control system includes voltage and current bicyclic ring in two parts. Power loop controller sampling
Obtain inverter output voltage
v
o
And output current
i
o
, Calculated inverter output active power
P
And reactive power
Q
,then
according to
P-f
And
Q-V
Droop characteristic equation, the inner controller generates a reference voltage
*
o
v
; Inner loop controller uses voltage and current double
Closed-loop control, the reference voltage
*
o
v
And the output voltage feedback
v
o
After the voltage regulator loop, generating a reference current loop
*
L
i
This reference
Test and filter inductor current feedback
i
L
After current loop regulator to generate six-way
PWM
Drive signal inverter bridge arm switch
Off. As can be seen the system voltage and current double closed-loop design goal is to make a good showing inverter output voltage source external characteristics, electrical
Pressure-loop control of the inverter output voltage can quickly and accurately track the power ring generated reference voltage for a given current control further
Improve the dynamic response characteristics of the system