Method for controlling a three-phase Vienna rectifier
A method for controlling a three-phase Vienna rectifier, including a plurality of controlled power switches, each associated with an electrical phase; the method including: transforming three provided reference line voltages into three phase voltages; calculating a homopolar component to be injected according to the sign of the phase voltage values and to the average value of the phase currents of the three-phase Vienna rectifier; calculating “modulating” values for each phase of the three-phase Vienna rectifier according to the calculated homopolar component to be injected and the three phase voltages; and generating six signals for switching the controlled power switches, according to the sign of the phase currents of the three-phase Vienna rectifier and the “modulating” values that were calculated.
1. A method for controlling a three-phase Vienna rectifier, comprising a plurality of controlled power switches (Sa, Sb, Sc) that are each associated with one electrical phase; the method comprising:
transforming three supplied setpoint phase-phase voltages (U*ab, U*bc, U*ac) into three phase-neutral voltages (v*a, v*b, v*c);
calculating a homopolar component (f(3wt)) to be injected according to the values and the signs of the phase-neutral voltages (v*a, v*b, v*c) and the average values of phase currents (ia, ib, ic) of the three-phase Vienna rectifier;
calculating a modulant value (mod*a, mod*b, mod*c) for each phase of the three-phase Vienna rectifier according to the calculated homopolar component (f(3wt)) to be injected and the three phase-neutral voltages (v*a, v*b, v*c); and
generating six signals for switching the controlled power switches (Sa, Sb, Sc) according to the sign of the phase currents (ia, ib, ic) of the three-phase Vienna rectifier and the calculated modulant values (mod*a, mod*b, mod*c).
2. The method as claimed in claim 1 , wherein the calculating the homopolar component (f(3wt)) comprises applying the following equation:
f
(
3
wt
)
=
v
z
*
=
σ
a
.
(
v
a
*
×
〈
i
a
〉
)
+
σ
b
.
(
v
b
*
×
〈
i
b
〉
)
+
σ
c
.
(
v
c
*
×
〈
i
c
〉
)
-
(
σ
a
.
〈
i
a
〉
+
σ
b
.
〈
i
b
〉
+
σ
c
.
〈
i
c
〉
)
wherein σ x=a,b,c =sign (v x=a,b,c *) according to the values from the following table:
Condition
σ a
σ b
σ c
ν a * ≥ 0, ν b * < 0 and ν c * < 0
+
−
−
ν a * ≥ 0, ν b * < 0 and ν c * < 0
+
+
−
ν a * ≥ 0, ν b * < 0 and ν c * < 0
−
+
−
ν a * ≥ 0, ν b * < 0 and ν c * < 0
−
+
+
ν a * ≥ 0, ν b * < 0 and ν c * < 0
−
−
+
ν a * ≥ 0, ν b * < 0 and ν c * < 0
+
−
+.
3. The method as claimed in claim 1 , wherein each modulant value (mod*a, mod*b, mod*c) is calculated by adding the homopolar component (f(3wt)) to the associated phase-neutral voltage (v*a, v*b, v*c).
4. The method as claimed in claim 1 , wherein the generating the six signals for switching the controlled power switches (Sa, Sb, Sc) comprises comparing the modulant values (mod*a, mod*b, mod*c) with two high-frequency carriers that are synchronized and in phase with one another.
5. The method as claimed in claim 4 , wherein, for each phase of the Vienna rectifier, when the phase current is positive, the modulant associated with the phase is compared with a symmetrical triangle-wave signal varying between 0 and +1.
6. The method as claimed in claim 4 , wherein, for each phase of the Vienna rectifier, when the phase current is negative, the modulant associated with the phase is compared with a symmetrical triangle-wave signal varying between −1 and 0.
7. A device for controlling a three-phase Vienna rectifier comprising:
means for implementing the method as claimed in claim 1 .