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Performance of Single-phase, half-wave controlled rectifiers

Performance of Single-phase, half-wave controlled rectifiers with pure resistive load ( For α=π/2)
{V_{dc\left( m \right)}} = \frac{{{V_m}}}{{2\pi }} = 0.1592{V_m}
{I_{dc}} = \frac{{{V_{dc}}}}{R} = \frac{{0.1592{V_m}}}{R}
{V_{rms}} = \frac{{{V_m}}}{2}\left( {\frac{1}{{\sqrt 2 }}} \right) = 0.3536{V_m}
{I_{rms}} = \frac{{{V_{rms}}}}{R} = \frac{{0.3536{V_m}}}{R}
{P_{dc}} = {V_{dc}}{I_{dc}} = \frac{{{{(0.1592{V_m})}^2}}}{R}
{P_{ac}} = {V_{rms}}{I_{rms}} = \frac{{{{(0.3536{V_m})}^2}}}{R}
Half Controlled Rectifier with R Load
a. SCR supplying a passive load. b. Voltage and current waveforms
Figure a. SCR supplying a passive load. b. Voltage and current waveforms.
Here, we have assumed delay angle (α) of 90 deg. The fundamental component of input current lags behind the input voltage, both P and Q flow from AC side to load or DC side. The displacement PF decreases as we delay the triggering pulse. If SCR is triggered ar 0 deg, no Q is absorbed.
Half Controlled Rectifier with RL Load
Half Controlled Rectifier with RL Load
Average Load/Output Voltage
{V_0} = \frac{1}{{2\pi }}\int_\alpha ^\beta  {\sqrt 2 V\sin \theta d\theta }
         = \frac{V}{{2\pi }}\left( {\cos \alpha  + \cos \beta } \right)
Average Load/Output Current
{I_0} = \frac{{{V_0}}}{Z}
Single-phase, half-wave controlled rectifiers with Inductive load
Single-phase, half-wave controlled rectifiers with Inductive load Role of free-wheeling diode
To avoid negative voltage when inductive load involved.
Role of free-wheeling diode area A = area B
During α < ωt < π:
vL + vR = vo
During π < wt < 2π+α:
vL + vR = 0
i ≥ 0 (exp decay)
i(t) is expressed in two separate equations.
Single-phase, half-wave controlled rectifiers with Internal DC Voltage
Single-phase, half-wave controlled rectifiers with Internal DC Voltage
Thyristor based Rectifiers and Inverters (1-phase)
a. SCR supplying an active load. b. Voltage and current waveforms Fig a. SCR supplying an active load. b. Voltage and current waveforms.
a. Line commutated inverter. b. Voltage and current waveforms.
Fig a. Line commutated inverter. b. Voltage and current waveforms.
previous Performance Parameters of Rectifiers (Input AC side)
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