Buck Rectifier a transformerless solution for front-end rectification, which is particularly suitable for traction applications, requiring high voltages to be stepped down to appropriate dc voltage. The proposed topology is based on pulse width modulation buck rectifier (current source inverter topology) and is capable of rectification and stepping down of single-phase ac supply, in a single stage.
Buck Rectifier A new control scheme is proposed to achieve constant dc output voltage and sinusoidal source current, irrespective of large ripples in the dc inductor current. Buck Rectifier The proposed scheme is configured in single-loop voltage control mode. The relevant small-signal model is derived from the large-signal model using multi order decomposition.
Buck Rectifier An elaborate procedure of dc filter design is discussed, for circuit operation with minimum energy storage. All analytical results are validated by numerical simulation for sinusoidal and distorted source voltage. Experimental verification is achieved through a 1.2-kW grid-connected laboratory prototype.
- Buck rectifier (BR)
- Single-loop control
- Single phase
Fig. 1. Basic BR circuit.
EXPECTED SIMULATION RESULTS:
Fig. 2. (a) Simulation results: Steady-state operation. vs (160 V/div); is (5 A/div); idc (5 A/div); vo (160 V/div); time (5 ms/div). (b) Harmonic spectrum of is (percentage of fundamental).
Fig. 3. (a) Simulation results: Steady-state operation at boundary condition. vs (160 V/div); is (5 A/div); idc (5 A/div); is1 (5 A/div); time (5 ms/div). (b) Harmonic spectrum of is (percentage of rated fundamental).
Fig. 4. Simulation results: Dynamic performance with step change in vo reference. idc (8 A/div); v∗ o (25 V/div); vo (25 V/div); time (40 ms/div).
Fig. 5. Simulation results: Dynamic performance with step change in vs. vs (200 V/div); is (10 A/div); idc (5 A/div); vo (100 V/div); time (20 ms/div).
Fig. 6. Simulation results with distorted source. (a) vs (120 V/div); is (5 A/div); time (5 ms/div). (b) Harmonic spectrum of is (percentage of fundamental).
Buck Rectifier a single-loop control scheme for single-phase BR has been presented. A nonlinear modulation scheme is proposed, and its effect is analyzed using a multi order system decomposition. The effectiveness of the proposed scheme is proved by simulation and experimental results.
Buck Rectifier From experimental results, it is clear that the proposed control scheme is capable of maintaining sinusoidal source current and near-UPF operation with optimum filter volume, even under distorted grid conditions. Generalized design of the dc inductor, which is the most critical element, is presented in detail.
Buck Rectifier Since source current wave shape is maintained despite ripples in dc current, requirement of an inner current loop is rendered superfluous. Apart from justifying the single-loop control scheme, this also entails greatly simplified controller design and realization.
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