In this slide we describe about parallel inverter, its circuit diagrams, working When SCR 1 is turned off the capacitor will discharge through SCR2, inductor L, waveform is not depend on load, as it does in series inverter. To study V-I characteristics of SCR and measure latching and holding currents. 2. To study MOSFET/IGBT based single-phase series-resonant inverter. To study The anode and cathode are connected to main source through the load. Single-phase Half and Full bridge Inverter, Pulse Width Modulated (PWM) technique for voltage The device behaves as if two diodes are connected in series with reverse . applied and also a large anode current flowing through the SCR.
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The source supply the load intermittently only during positive half cycle. Therefore source should have a high harmonic content.
Singal Phase Half Bridge Inverter
The maximum load current depends on the load resistance. Therefore, output regulation of the inverter is poor. The drawbacks 1 and 5 can be removed by modifications of the circuit.
Series inverter using scr has two mutually coupled and exactly similar inductors L1 and L2.
This voltage induced across L1 will add to the capacitor voltage in reverse biasing Th2. The circuit conditions and analysis is exactly the same as incase of simple inverter. The advantage in having two inductors is that Th2 can be turned on even before Th1 has turned off.
Thus the series inverter using scr frequency can be adjusted to a higher value because time Toff in fig 2 can be eliminated, In fig 1 this action results in short circuit is avoided because of the presence series inverter using scr inductors L1 and L2.
ELECTRICAL ENGINEERING: single phase series and parallel invertor(power electronics)
Therefore, a voltage equal to capacitor voltage minus the voltage across load will appear across L2 since L1 is mutually coupled with L2 the same voltage will be induced across L1 also, thus the cathode of Th1 will be raised to a higher series inverter using scr than the anode and Th1 will be turned off.
A similar action will reverse bias Th2 at the end of negative cycle and turn it off. Thus the time interval Toff can be avoided giving a higher output frequency. Fig 4 shows a further improvement in the series inverter. This circuit uses two mutually coupled inductors and two capacitors.
In this circuit power is drawn from the source series inverter using scr during both half cycles. Thus the intermittent operation of battery is avoided. Assume that initial charge across C2 is Ec with polarity as shown.
The nature of the load current is alternating as there is underdamped circuit of series inverter using scr commutating components.
The SCR T1 automatically turns off at point a because the load current becomes zero. The load current becomes zero after it becomes maximum in the negative direction.
This way cycle repeat after it complete one turns. The positive AC output voltage half cycle generates due to DC voltage source whereas negative half cycle generates due to capacitor.
The time duration ab and cd must be greater than the SCR specific turn off time and it is called as dead zone. Limitations of series inverter The limitation of series inverter is as given below. The load current flows only during positive half cycle from supply source.
Series inverter using scr rating of commutating components should high because the load current flows through it.