Electronics; Rectifiers And Battery Chargers - B Flashcards
What is a rectifier?
Device that changes AC to DC
What are the two main categories of rectifiers?
Half-wave
Full-wave
What is the difference between a half-wave rectifier and a full-wave rectifier?
Half-wave = every second ac alternation is applied to the load
Full-wave = every ac alternation applied to the load
What does a single phase half wave recifier consist of and how is it connected with respect to the load?
One diode. In series with the load.
When is the diode of a single phase half wave recifier reverse-biased?
During the second alternation.
When will a voltage appear across the load in a single phase half wave rectifier installation?
When the diode is forward biased and current is flowing.
What is the voltage across the diode when it is reverse-biased? (Open switch)
Equal to the supply voltage
What is the voltage across a forward-biased diode?
Near 0 (closed switch) equal to the barrier potential of the diode.
What is the average voltage value (dc voltage value) of a single phase half wave recifier?
31.8% of the peak voltage. (1/pi)
What kind of dc voltage is produced by a single-phase half wave recifier?
Pulsating DC
What kind of frequency is produced by pulsating DC?
Ripple frequency
What kind of rectification is provided by a centre-tapped transformer with two diodes?
Full-wave rectification
How does the polarity of the load change as supply polarity changes, in a centre tapped full wave rectified circuit?
It does not change.
What is the conversion factor for a single-phase full-wave rectifier?
0.637 of the peak value of the rectifier voltage
What are the equations for V(dc) for:
1) single phase half wave
2) single phase full wave
1) V(dc) = V(peak) × (1/pi)
2) V(dc) = V(peak) × (2/pi)
How do you determine centre-tapped secondary voltage given primary voltage and a transformer ratio?
(V(primary rms)/xfmer ratio)/2
How do you find average load voltage for a load connected to a single-phase centre-tapped full-wave recified circuit?
V(dc) = (V(L1 or L2-N) ÷ 0.707) × (2/pi)
The product of ‘peak of the voltage applied to the load at any given time (half of secondary)’ and 2/pi
What is the ripple frequency of the load voltage in a full-wave rectified circuit? Illustrate this using a waveform diagram.
Two times the supply frequency
What is the most commonly used single-phase rectifier?
Single-phase full-wave bridge recifiers.
How many diodes are used in a single-phase full-wave bridge rectifier?
4
For a single phase full wave bridge rectifier, if current through the load is from C to D and is positive on the 1st alternation, what would the polarity be from C to D on the second alternation?
Also positive
What is the first step in finding average load voltage?
Find V peak (of the voltage the load sees)
How would you expect the result of V(dc) calculations to differ between single-phase full-wave bridge rectifier and single-phase centre-tapped full wave rectifier?
Bridge would be larger as Vpeak is based off full secondary voltage as opposed to half (centre-tapped) secondary voltage.
What is the equation used to find average load voltage in a single-phase full-wave bridge rectifier circuit?
V(dc) = V(peak) × (2/pi)