1 the introduction

Single-phase bridge Rectifier circuit (Rectifier) especially controlled Rectifier circuit is relatively important in the power electronic technology, is applied more widely circuit, not only applied to general industrial, also widely used in transportation, electric power systems, communications systems, energy systems, and other fields. For single phase bridge rectifier circuit parameters and load with different properties related to the work of comparative analysis and research have very strong realistic meaning, not only is an important part of power electronic circuit theory learning, but also of prediction and the practical application of engineering practice.

Single-phase bridge type 2 half controlled rectifier circuit

In figure 1 VT1 and VT2 is trigger pulse phase difference each 180? Thyristor, VD1 and VD2 for rectifier diode, is composed of the four components of single-phase bridge type half controlled rectifier circuit. Resistance R and inductance L as the load, if the assumption that the inductance L is enough big, namely omega acuity R L, because the inductance current cannot mutation, can think of load current remain constant throughout the working process of the steady state value. Due to the characteristics of the bridge structure, as long as the thyristor conduction, the load is always coupled with the forward voltage, and load current is always single direction flow, so the bridge half controlled rectifier circuit can only work in the first quadrant, because L p R omega, so no matter why control Angle alpha value, the change of the load current id is very small.

Figure 1 single phase bridge type half controlled rectifier circuit principle

In u2 is half cycle, triggering Angle alpha inflicts on thyristor VT1 trigger pulse, u2 VT1 and VD4 supply power to the load. U2, the zero passage becomes negative, due to the inductance current no longer flows through the transformer secondary winding, but by the VT1 and VD2 stream. At this stage if ignore the state of device pressure drop the load of negative pressure drop ud will not happen. U2 negative half cycle triggering Angle alpha moments, VT2 and VD3 trigger conduction, at the same time pressuring VT1 reverse voltage and shut off, u2 VT2 and VD3 supply power to the load. U2 zero change timing, VD4 conduction, VD3 shut off. VT1 and VD4 stream, load pressure drop ud to zero again.

Based on the above analysis, to find out the output load voltage average value is:

（1）

Alpha Angle of phase shift in the range of 180 °. The average of the output current for:

（2）

The average current through the thyristor is only half of the average output dc, namely:

（3）

RMS current through the thyristor:

（4）

Single-phase bridge type half controlled rectifier circuit simulation model is shown in figure 2.

Figure 2 single-phase bridge type half controlled rectifier circuit simulation model

(1) with pure resistive load

The corresponding parameter Settings: (1) U = 100 v ac voltage source parameters, f = 50 hz; (2) the thyristor parameters Rn = 0.001 Ω, Lon = 0 h, Vf = 0.8 V, the Rs = 10 Ω, Cs = 250 e - 6 f; (3) R = 10 Ω load parameters, L = 0 h, C = inf. (4) pulse generator trigger signal amplitude of the 1, 2 to 5 v, period of 0.02 s (that is, the frequency of 50 hz) and pulse width of 2.

Set the trigger signal to 1 in the early phase of 0 s (namely 0?) , trigger signal in the early phase of 2 to 0.01 s (180?) , the simulation results are shown in figure 3 (a); Set the trigger signal 1 in the early phase of 0.0025 s (45?) , trigger signal in the early phase of 2 to 0.0125 s (225?) , the simulation results are shown in figure 3 (b).