11/23/2023 0 Comments 2 phase to 3 phase converterMid-point converter requires six SCRs and bridge converter also requires six SCRs. Mid-point converter requires two SCRs and bridge converter requires four SCR: Suitable for low current rating applications. Uniform loading occurs if used for high power D.C. Non-uniform loading occurs if used for high power D.C. motor performance is superior as compared to single-phase converter fed. motor performance is not better if fed from single-phase converter.Īs the load current is continuous, D.C. load.įiltering requirement for smoothing out load current is more.ĭue to presence of large ripple frequency, filtering requirement for smoothing out the load current is reduced.ĭ.C. converters are preferred for high power D.C. \ Difference between 3 Phase Converter and 1 Phase Converter Single-Phase Converters This mode of operation is very similar to previous two modes. Since the conduction of thyristor T 2 continues upto 9π /6 + α, even negative voltage reaches to load (as commutation does not take place at ωt = π due to stored energy in inductive load).Īt instant ωt = (9π /6 + α) or (330° + α), the SCR T 3 is triggered, the line voltage V CN appears across the load. The load voltage is equal to phase voltage V BN i.e. But due to stored energy in inductive load, the thyristor T 1 continues to conduct in negative half cycle for some period.Īt instant ωt = (5π /6 + α) or (150° + α), SCR T 2 is triggered, the load current immediately transferred from T 1 to T 2. The conducting thyristor T 1 try to turn-off due to reverse voltage appeared across the thyristor T 1. After some time at ωt = π, the supply voltage V AN goes through zero, and after π it becomes negative. In this mode of operation, the load voltage V 0 and load current I 0 both positive, so the inductive load will store energy. As the SCR T 1 is turned ON, the conducting thyristor T 2 is turned OFF due to line commutation. ![]() The thyristor acts as a mechanical switch and V 0 is same as V AN. The operation of three-phase half-wave controlled converter with R L load consists of three modes:Īt instant ωt = (π/6 + α) or 30° + α, the SCR T 1 triggered, the phase voltage V AN reaches to the load. Since there are three voltage pulses, NP for each phase is displaced by 120°. ![]() Therefore, the NP (neutral point) for phase A, B and C are ωt = π /6, 5 π /6 and 9 π /6 respectively. Unlike the reference point of α, being the zero-crossover instant for single-phase system, here the reference or neutral point NP is the crossover point of voltage value of two phases as shown in Fig. The average output voltage is controlled with the help of firing angle (α), from positive maximum to zero. 2: Input, output voltage and current waveforms of three-phase half-wave controlled converter with RL load. The load is connected between common cathode point of the three SCRs i.e. Three phases V AN, V BN and V CN are applied for SCRs T 1, T 2 and T 3 respectively. The conduction period for each SCR is 2π/3 radians or 120°. This circuit provides the load current i 0 is ripple free and continuous. ![]() 1 shows the circuit diagram of three-phase half wave controlled converter with highly inductive load. 1: Circuit diagram of three-phase half-wave controlled converter with highly inductive load.įig. Three-Phase Half-Wave Controlled Converter (With Highly Inductive Load)įig. Three-phase converters are mainly classified into three classes like single-phase converters (rectifiers).įull-wave converters are further classified into two classes: output is suitable for large power DC loads. The average output voltage of 3 phase converter provides higher and hence its D.C. For the large power, variable speed drives, the 3 Phase AC to DC converters are extensively used.
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