Cycloconverter
Single-phase
Cycloconverter
Rectifier: From AC
Variable DC voltage.
Chopper: From constant DC voltage
Inverter: From DC
variable DC voltage.
variable magnitude and variable frequency
AC voltage.
There are ways to convert from AC
AC
• Two stages: AC to DC and then DC to AC.
• One stage: cycloconverter
Input: AC
(Constant V & f)
Cycloconverter
AC - AC
Output: AC
Adjustable Voltage with
Lower frequency
The ac power at one frequency is converted directly to another frequency generally
lower than the input supply frequency without any intermediate dc stage.
Applications: Cement mill drives, Ship propulsion drives, Rolling mill drives,
starting synchronous motors, etc.
Construction
A typical cycloconverter consists of one or more pairs of back-to-back connected controlled
rectifiers. By the controlled opening and closing of the thyristors, it is possible to fabricate
output voltage waveforms having a fundamental component of the desired output frequency.
Negative or N Converter:
generate negative cycle
Positive or P Converter:
generate positive cycle
Thyristor
π·π
π·π
π΅π
π΅π
π΅π
π΅π
L π½π³πππ
O
A
D
π½π πππππ
π·π
π·π
Cycloconverter types based on
the input and output phases
Single-phase to
single-phase
Bridge
Center tap
Three-phase to
Three-phase
Three
pulse
bridge
Six
pulse
bridge
Three-phase to
single-phase
Three
pulse
Six
pulse
Required
Operation Method
Magnitude of π½πππππ = Magnitude of π½ππππππ
π=
Firing angle πΆπ = π
πππ
ππ
ππππ = π. π ππππππ
π=π
n is the number of half supply cycle. It is integer.
Positive or P Converter
(working)
Negative or N Converter
(disabled or not working)
π·π & π·π πΆπ΅
π·π
π·π
L
O
A
D
π·π
π·π
For the first one cycle
and negative parts)
π΅π
π΅(positive
π
of
input voltage,
the
positive Converter operates
supplying current to the
load. In the next cycle, the
negative converter operates
supplying current to the load
in the reverse direction.
π΅π
π΅π
Operation Method
Note that when one of the converters operates
the other one is disabled, there is no current
circulating between the two rectifiers.
Positive or P Converter
(Working)
Negative or N Converter
(disabled or not working)
π·π & π·π πΆπ΅
π·π
π·π
L
O
A
D
π·π
π·π
π΅π
π΅π
π΅π
π΅π
Operation Method
π΅π & π΅π πΆπ΅
Positive or P Converter
(disabled or not working)
π·π
Negative or N Converter
(working)
π·π
L
O
A
D
π·π
π·π
π΅π
π΅π
π΅π
π΅π
Operation Method
π΅π & π΅π πΆπ΅
Positive or P Converter
(disabled or not working)
π·π
Negative or N Converter
(working)
π·π
L
O
A
D
π·π
π·π
π΅π
π΅π
π΅π
π΅π
πππππππ
π
ππ
N = πππ = ππ = π
π
πππππππ
Disadvantages:
N = 1,2,3,…
π
ππ
N = πππ = ππ = π
π
Single-phase to single-phase: Bridge
R- Load
Single-phase to single-phase: Bridge
π½π (πππ) =
ππ΅ π
ΰΆ± π½π πππ ππ π π
ππ
ππ
π΅ πΆπ·
πΆπ
=
=
ππ(πππ )
π½π
π
π½π
πππ π π
π
−
π
π
πππ π ππ
ππ −
π
π
π
πΆπ
π
π π
Zero
−
π
πππ ππΆπ
πΆπ −
π
π½π (πππ)
π°πΆ (πππ) =
πΉ
π·πππ = π°ππ(πππ) ∗ πΉ
Single-phase to single-phase: Bridge
Inductive load
RL - Load
π· πππππ ππ πππ πππππ
π½π (πππ) =
π· πππππ ππ πππππ
πππ ππΆπ
π
π
− πΆπ +
π
π
π
π½π
π½
π½
πΆπ
=
π·
π½π (πππ) =
π½π
π
π π
π½π
π·
π
πππ π ππ
ππ −
π
π
π
πΆπ
πππ π π·
π·−
π
−
πππ ππΆπ
πΆπ −
π
Single-phase to single-phase: Bridge
Inductive load
RL - Load
π°π (πππ) =
The rms value of the load current
πΉπ + πΏππ³
π°ππ (πππ) = π°π (πππ) =
The converter current
π°π (πππ) =
π½π(πππ)
π°ππ (πππ) + π°ππ΅ (πππ)
π°π (πππ) = π°π΅ (πππ)
π ∗ π°ππ΅ (πππ) π°π (πππ) = π π°π΅ (πππ) π°π΅ (πππ) =
π°π΅ (πππ) = π°π· (πππ)
π°π΅ (πππ) =
Thyristor current
π ∗ π°ππππ.
π°π(πππ)
π
Output power
π
π°ππππ.π΅π (πππ) + π°ππππ.π΅π (πππ)
π°πππ.π΅π = π°πππ.π΅π = π°πππ.
π°π΅ (πππ) =
π°π(πππ)
= π π°πππ.
π·πππ = π½π(πππ) ∗ π°π πππ ∗ πππ ∅
π°π(πππ)
π°πππ. =
π
Single-phase to single-phase: Bridge (MATLAB: 4 Pulse gene.)
Periodic time of
the output wave:
π Τ ππ
Firing angle πΆπ = π
Single-phase to single-phase: Bridge (MATLAB: 4 Pulse gene.)
Firing angle πΆπ = π
πππππππ
πππππππ
πππππππ
πππππππ
Periodic = 1/ππ = 1/12.5 = 0.08
π
ππ
N = ππ =
= π (even number)
π
ππ
N = πππ = ππ = π
π
(even number)
ππ
ππ.π
Phase delay P12 = 0 Phase delay P34 = 0.01
Phase delay N12 = 0.04 Phase delay N34 = 0.05
Single-phase to single-phase: Bridge (MATLAB: 4 Pulse gene.)
Pulse is on
Output = 1
Single-phase to single-phase: Bridge (MATLAB: 4 Pulse gene.)
Single-phase to single-phase: Bridge (MATLAB: 4 Pulse gene.)
Firing angle πΆπ = π
Periodic = 1/ππ
= 1/10 = 0.1
πππ
ππ
N = π = ππ = π (ππ
π
ππππππ)
π
Phase delay P12 = 0
Phase delay P34 = 0.01
Phase delay N12 = 0.06
Phase delay N34 = 0.05
Single-phase to single-phase: Bridge (MATLAB: 4 Pulse gene.)
Periodic = 1/ππ
= 1/10 = 0.1
π
ππ
N = πππ = ππ = π (ππ
π
ππππππ)
π
Phase delay P12 = 0
Phase delay P34 = 0.01
Phase delay N12 = 0.05
Phase delay N34 = 0.06
Single-phase to single-phase: Bridge (MATLAB: 2 Pulse gene.)
Single-phase to single-phase: Bridge (MATLAB: 2 Pulse gene.)
Single-phase to single-phase: Bridge (MATLAB: 2 Pulse gene.)
Single-phase to single-phase: Bridge (MATLAB: 2 Pulse gene.)
Single-phase to single-phase: Bridge (MATLAB: 2 Pulse gene.)
Single-phase to single-phase: Bridge (MATLAB: 3 Pulse gene.)
π·π΅ππ
π·π΅ππ
π
ππ
π·π
Single-phase to single-phase: Bridge (MATLAB: 3 Pulse gene.)
Periodic = 1/ππ
= 1/10 = 0.1
πππ
N= π =
π
ππ
= π (ππ
π
ππππππ)
ππ
Disadvantages:
N = 1,2,3,…
Single-phase to single-phase: Bridge (MATLAB: 3 Pulse gene.)
Periodic = 1/ππ
= 1/10 = 0.1
πππ
N= π =
π
ππ
= π (ππ
π
ππππππ)
ππ
Disadvantages:
N = 1,2,3,…
Single-phase to single-phase:
Center tap
Single-phase to single-phase: Center tap (step down)
πππ = ππ π―π, ππππ = ππ π―π
ππππ π → π
π·π π’π¬ π¨π§
π·π
ππππ π
→ ππ
π·π ππ ππ
π·π
π·π
Single-phase to single-phase: Center tap (step down)
π΅π
ππππ ππ
ππ ππ
→ π΅π
ππππ ππ
ππ ππ
→ π΅π
π΅π
π΅π
Single-phase to single-phase: Center tap (step down)
Single-phase to single-phase: Center tap (step down)
π·π → π·π → π΅π → π΅π
π·π
π·π
π΅π
π΅π
π·π
Single-phase to single-phase: Center tap (step up)
πππ = ππ π―π,
π¨π ππππ → π·π
π¨π π
Τπ → π΅π
ππππ = πππ π―π
π·π
π·π
π΅π
Single-phase to single-phase: Center tap (step up)
πππ = ππ π―π,
π·π
π¨π π
→ π·π
π¨π ππ
Τπ → π΅π
ππππ = πππ π―π
π·π
π΅π
π΅π
π·π
π·π π΅π
Single-phase to single-phase: Center tap (step up)
Single-phase to single-phase: Center tap (step up)
π·π → π΅π → π·π → π΅π
π·π
π΅π
π·π
π΅π
π·π
Single-phase to single-phase: Problems
(Center tap)
Solution
Single-phase to single-phase: Problems
(a)
π
ππππ
π
= ππ = π. ππ
Single-phase to single-phase: Problems
(b)
(c)
(d)
Single-phase to single-phase: Problems
(d) Input power factor when the harmonic content take in consideration
Solution
(a)
Single-phase to single-phase: Problems
π·π
(a)
π·π
π΅π
π΅π
π
ππππ
π
= ππ.π = π. ππ
π·π
Single-phase to single-phase: Problems
(b)
π°π =
πππ. π
= ππ. π π¨
π. ππ
π°π(πππ)
π°πππ. =
= π. ππ π
π
(c)
π°ππ = π°π = ππ. π π¨
π½π¨ππππππ = π¬ × π°ππ = πππ × ππ. π = ππππ π½π¨
π·π = π¬π × π°π ππ¨π¬ π½ = πππ. π × ππ. π × ππ¨π¬ ππ = ππππ πΎ
Single-phase to single-phase: Problems
π·. πππ =
π·πΆ
ππππ
=
= π. ππππ
π½π¨
ππππ
(d)
This proves that the harmonic content in the output voltage reduces the
power-factor.
Single-phase to single-phase: Analysis
when p-converter operating alone, the output voltage is positive half-cycles with
average output voltage πππ1 = πππ πππ πΌ . Also when n-converter operating alone,
the output voltage is negative half-cycles with average output voltage
πππ2 = −πππ πππ πΌ = −πππ1
π»ππππ π―πππππππ
π½ = π½ππππ
. + π½ππππ. + π½π
π
π―πππππππ ↑ → ππππ
. ↓ → π»π―π« ↑ → π·. π ↓
In order to reduce the harmonic and increase the fundamental
component, Lookup table for P converter , and lookup table for N
converter are used to apply different angle
Single-phase to single-phase: : Analysis
Single-phase to single-phase: : Analysis
Single-phase to single-phase: : Analysis
900
360
900
360
Single-phase to single-phase: : Analysis
0
270 90
00 1260
Single-phase to single-phase: Problems
Single-phase to single-phase cycloconverter “ Bridge type” with input
voltage 220 V, input frequency 50 Hz, and the output frequency is 12.5
Hz. The firing angle of P converter and N converter equal 36 and 90,
respectively . The load is resistance and it equals 10 ohm.
(a) Calculate the rms of the output voltage and the current.
(b) Sketch the input and output voltage waveforms
© If the different fringing angle technique is used, where the firing
angles of π12 , π34 , π12 , πππ π34 πππ’ππ 27, 72, zero, and 126,
respectively. Calculate the rms output voltage and current.
(d) If the different fringing angle technique is used, where the firing
angles of π12 , π34 , π12 , πππ π34 πππ’ππ 27, 72, zero, and 90,
respectively. Calculate the rms output voltage and current.
Solution
Single-phase to single-phase: Problems
(a)
π½π (πππ) =
ππ΅ π
ΰΆ± π½π πππ ππ π π
ππ
ππ
π΅ πΆπ·
π½π (πππ) =
π
π
π
π ∗ ΰΆ± π½π πππ ππ π π
ππ + π ∗ ΰΆ± π½π πππ ππ π π
ππ
π
∗π
ππ
ππ
π½π (πππ) =
π½ππ π
ππππππ
π
ππππππ
∗ ππ −
+ ∗ ππ −
π
∗π π
π
π
π
ππ
ππ
π
π½π (πππ) =
π½ππ
π
∗π
π
ππ
ππππ ∗ ππ
π
ππππ ∗ ππ
π
−
+
+ π
−
+
ππ
π
π
π
π
π½π (πππ) = πππ π
π
∗π
ππ
ππππ ∗ ππ
π
ππππ ∗ ππ
π
−
+
+ π
−
+
ππ
π
π
π
Single-phase to single-phase: Problems
π½π (πππ) = πππ π
(b)
π
π
∗π
π
−
ππ
ππππ ∗ ππ
π
ππππ ∗ ππ
+
+ π
−
+
ππ
π
π
π
= πππ. π π½
Single-phase to single-phase: Problems
(c)
π
π½π (πππ) =
π
π
∗π
π
ΰΆ± π½π πππ ππ π π
ππ + ΰΆ± π½π πππ ππ π π
ππ +
ππ
π
ππ
π
ΰΆ± π½π πππ ππ π π
ππ + ΰΆ±
π
π½π (πππ) = πππ π
π
π
∗π
= 184.7 V
π½π πππ ππ π π
ππ
πππ
ππ
ππππ ∗ ππ
ππ
ππππ ∗ ππ
+
+ π
−
+
+
ππ
π
ππ. π
π
ππππ ∗ π
ππ
ππππ ∗ πππ
π
−π +
+ π
−
+
π
π. πππ
π
π
−
Single-phase to single-phase: Problems
Single-phase to single-phase: Problems
Single-phase to single-phase: Problems
(d)
π
π½π (πππ) =
π
π
∗π
π
ΰΆ± π½π πππ ππ π π
ππ + ΰΆ± π½π πππ ππ π π
ππ +
ππ
ππ
π
ΰΆ± π½π πππ ππ π π
ππ + ΰΆ± π½π πππ ππ π π
ππ
π
π½π (πππ) = πππ π
π
π
∗π
= 195.8 V
π
ππ
ππ
ππππ ∗ ππ
ππ
ππππ ∗ ππ
π
−
+
+ π
−
+
+
ππ
π
ππ. π
π
ππππ ∗ π
π
ππππ ∗ ππ
π
−π +
+ π
−
+
π
π
π
Single-phase to single-phase: Problems
Alpha = 27,72,0,90
(d)
Single-phase to single-phase: Application
Single-phase to single-phase: Application
Single-phase to single-phase: Application
Single-phase to single-phase: Application
REFERENCES
1
“Power electronics devices, circuits, and applications” Muhammad H. Rashid
(4th edition)
2
“SPEED CONTROL OF SINGLE AND THREE PHASE INDUCTION MOTOR USING FULL
BRIDGE CYCLOCONVERTER” 2018 IEEE conference
3
https://www.youtube.com/watch?v=ia21tsfasnc&t=2448s
4
https://www.youtube.com/watch?v=l4CfEB61fMc&list=PLgwJf8NK2e5Lyu3Hj_EJms-boPTpRbpn
5
https://www.youtube.com/watch?v=LudX641uR4g&list=PLSWRPBzGkib8X_Kd71
mlqrKLtJKhQqwYO&index=3
5
https://www.youtube.com/watch?v=d6GJ1svbP9I&t=3s
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