Power Electronics Lab Experiments

Study of Single Phase Cycloconverter with Lamp and motor Load

Nov 27 2023

Aim:

Study of Single Phase Cycloconverter with Lamp and motor Load.

Apparatus Required:

High Voltage Power Electronics Lab
4mm Patch Cords
Product Tutorials

Circuit Diagram

Single Phase Cycloconverter with Lamp Load

Single Phase Cycloconverter with motor load

Procedure:

Make sure that there is no connection on the Work Bench initially.

Switch on the three phase MCB of back panel.
Red, Yellow and Blue indicator glow at front panel.
Connect +12V, +5V, and ground (GND) and connect 18-0-18 at cycloconverter firing circuit from single phase low voltage power supply.
Use SCR1, SCR4, SCR2 and SCR5 and construct single phase cycloconverter configuration.
Connect the cathode of SCR1 to anode of SCR4 and connect the anode of SCR1 to cathode of SCR4.
Connect the cathode of SCR2 to anode of SCR5 and connect the anode of SCR2 to cathode of SCR5.
Connect the cathode of SCR1 to cathode of SCR2.
Connect the one terminal of load from load assembly to common cathode terminal of SCR1 and SCR2 and connect other terminal of load from load assembly to center tapped transformer output neutral (0) terminal from Single Phase Supply.
Connect 115V terminal from single phase supply to anode of SCR1 or cathode of SCR4.
Connect another 115V terminal from single phase supply to anode of SCR2 or cathode of SCR5.
Connect gate pulse G1 at gate (G) of SCR1 and connect K1 at cathode of SCR1 from cycloconverter firing circuit.
Connect gate pulse G3 at gate (G) of SCR4 and connect K3 at cathode of SCR4 from cycloconverter firing circuit
Connect gate pulse G2 at gate (G) of SCR2 and connect K2 at cathode of SCR2 from cycloconverter firing circuit
Connect gate pulse G4 at gate (G) of SCR5 and connect K4 at cathode of SCR5 from cycloconverter firing circuit.
Verify the connections before switch on the MCB of single phase supply.
Connect BNC to BNC cable at CH1 of oscilloscope to output of Power Scope A.
Connect input of Power Scope A to the load.
Switch of ATT of A is x 100 position and switch of coupling of A is AC position.
Connect the Lamp at the Load.
Switch on MCB of single phase supply and observe the output waveform of Load terminal on the oscilloscope.
Connect the AC voltmeter at the load and measure the output AC voltage across the load.
Observe the output waveform at the load as shown in figure.

Observation table:

With Ramp Comparator Firing Circuit: R

R Load:

Firing angle(α)	Time Period(ms)	Frequency	V_rms(Theoretical)	V_rms(Practical)	V_avg(Theoretical)	V_avg(Practical)
32.4	1.8	16.67	112.911	1.25	0	-8.82
64.8	3.6	16.67	100.428	111.6	0	10.6
90	5	16.67	81.317	97.4	0	-12.9
117	6.6	16.67	52.147	76	0	-10.9

RL load:

Firing angle(α)	V_avg(Theoretical)	V_avg(Practical)	V_rms(Theoretical)	V_rms(Practical)	β(ms)	Frequency
30	0	-7.51	115	124	11.6	16.67
90	0	-8.97	107.65	105	12.2	16.67
170	0	-13.9	108.686	80.2	12.6	16.67

With Cycloconverter Firing Circuit: R load:

Firing angle(α)	Time Period(ms)	Frequency	V_rms(Theoretical)	V_rms(Practical)	V_avg(Theoretical)	V_avg(Practical)
60	3.4	16.67	103.14	115	0	-3.18
90	5	16.67	81.317	95.2	0	-1.67
108	6	16.67	63.66	78.9	0	-2.94
117	6.6	16.67	54.09	68	0	-1.02

RL load:

Firing angle(α)	β(ms)	Frequency	V_rms(Theoretical)	V_rms(Practical)	V_avg(Theoretical)	V_avg(Practical)
32.4	21.6	50	115.72	121	0	-10.2
60	230.4	50	110.79	119	0	-9.5
90	230.4	50	90.818	105	0	-8.49
117	230.4	50	67.538	16.9	0	-4.15

Equations:

R Load

V_rms = V_s[1/π[(π-α) + sin2α/2]] ^1/2

RL Load

Experimental Waveforms:

R load:

RL load:

Conclusion:By varying the firing angle control potentiometer of ramp comparator firing circuit, output voltage across the loads, their waveform for single phase Cycloconverter controller with R and RL Loads was observed.