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Questions and Answers
What is the output voltage of the circuit in the first equation?
What is the value of I/01 in the given equation?
What is the design requirement for the output voltage ripple in Example 5.3?
What is the duty ratio of the buck converter in Example 5.3?
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What is the switching frequency assumed in Example 5.3?
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What is the minimum inductor size determined from in Example 5.3?
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What is the value of the inductor chosen in Example 5.3?
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What is the input voltage of the buck converter in Example 5.3?
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What is the load resistance of the buck converter in Example 5.3?
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What is the required output voltage of the buck converter in Example 5.3?
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Study Notes
DC-DC Converter (Chopper)
- A DC-DC converter is a power electronic circuit that converts a DC voltage to a different DC voltage level, often providing a regulated output.
- Applications include switched-mode power supply (SMPS), DC motor control, and battery chargers.
Main Types of Choppers
- Step-down DC-DC converter: output voltage is less than input voltage.
- Step-up DC-DC converter: output voltage is more than input voltage.
- Buck-Boost converter (Step-down/step-up converter): output voltage can be more or less than input voltage.
DC Chopper with Resistive Load
- A DC chopper with a resistive load consists of a DC input voltage source, a controllable switch, and a load resistance.
- The switch is operated with a duty ratio (D) defined as the ratio of the switch ON time to the sum of the ON and OFF times.
- Chopping period (T) = TON (ON time) + TOFF (OFF time).
- Chopping frequency (F) = 1/T.
Buck (Step-Down) Converter
- The input voltage is connected to a controllable semiconductor device that operates as a switch.
- The switch rapidly turns on and off, controlling the flow of current through the circuit.
- A diode is used to allow current to flow when the switch is off, providing a path for the inductor's energy to discharge.
Principle of Operation
- When the switch is turned on, the input voltage is connected to the inductor, causing the current to increase.
- When the switch is turned off, the inductor releases its energy, and the diode becomes forward-biased.
Steady-State Operation
- The net change in current through the inductor in one complete cycle is zero.
- The average inductor current must be the same as the average current in the load resistor.
Output Voltage Ripple
- The variation in output voltage, or ripple, is computed from the voltage-current relationship of the capacitor.
- The ripple factor can be reduced by increasing the switching frequency, inductor size, or capacitor size.
Continuous Current Mode (CCM) Operation
- Imin = 0 is the boundary between continuous and discontinuous current.
- To ensure continuous current, Imin ≥ 0, and L ≥ Lmin.
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Description
This quiz covers the basics of DC to DC converters, also known as choppers, which are power electronic circuits that convert a DC voltage to a different DC voltage level, often providing a regulated output.
