Slide 1: Single-Phase Diode Rectifier Bridge Large capacitor at the dc output for filtering and energy storage Slide 2: Diode-Rectifier Bridge Analysis Two simple (idealized) cases to begin with Slide 3: Waveforms with a purely resistive load and a purely dc current at the output In both cases, the dc-side voltage waveform is the same Slide 4: Diode-Rectifier Bridge Input Current Idealized case with a purely dc output current Slide 5: Diode-Rectifier Bridge Analysis with AC-Side Inductance Output current is assumed to be purely dc Slide 6: Effect of DC-Side Current on THD, PF and DPF Very high THD at low current values Slide 7: Diode-Rectifier with a Capacitor Filter Power electronics load is represented by an equivalent load resistance Slide 8: Diode-Bridge Rectifier: Waveforms Analysis using PSpice Slide 9: Analysis using PSpice Input Line-Current Distortion Slide 10: Line-Voltage Distortion PCC is the point of common coupling Slide 11: Distortion in voltage supplied to other loads Line-Voltage Distortion Slide 12: Three-Phase, Full-Bridge Rectifier Commonly used Slide 13: Three-Phase, Full-Bridge Rectifier: Redrawn Two groups with three diodes each Slide 14: Three-Phase, Full-Bridge Rectifier Waveforms Output current is assumed to be dc Slide 15: Three-Phase, Full-Bridge Rectifier: Input Line-Current Assuming output current to be purely dc and zero ac-side inductance Slide 16: Three-Phase, Full-Bridge Rectifier Including the ac-side inductance Slide 17: Rectifier with a Large Filter Capacitor Output voltage is assumed to be purely dc Slide 18: Three-Phase, Full-Bridge Rectifier THD, PF and DPF as functions of load current Slide 19: Harmonic Guidelines: IEEE 519 commonly used for specifying limits on the input current distortion Slide 20: B. Hysteresis (Bang-bang) PWM (1) Three-phase inverter for hysteresis Current Control Fig. 8 Three-phase inverter for hysteresis current control. 15 Slide 21: II. PWM METHODS
B. Hysteresis (Bang-bang) PWM (2) Hysteresis Current Controller Fig. 9 Hysteresis current controller at Phase “a”. 16 Slide 22: II. PWM METHODS
B. Hysteresis (Bang-bang) PWM (3) Characteristics of hysteresis Current Control Advantages Drawbacks 17 Excellent dynamic response Low cost and easy implementation Large current ripple in steady-state Variation of switching frequency No intercommunication between each hysterisis controller of three phases
and hence no strategy to generate zero-voltage vectors.
As a result, the switching frequency increases at lower modulation index and
the signal will leave the hysteresis band whenever the zero vector is turned on. The modulation process generates subharmonic components