Description
COMPLETE POWER ELECTRONICS AND ALTERNATIVE ENERGY COURSE QUESTIONS WITH MULTISIM
Problems
Switch Characteristics
6-1
Locate a data sheet for a 1N4004 diode. Determine its average forward current, maximum forward voltage, and peak reverse voltage. Calculate the maximum power it must dissipate.
6-4
Design a switch using a Darlington pair to drive a 35 Ω load powered from a 24 Vdc supply. Determine the collector current, base current, base resistor, power delivered to the load, and the transistor power dissipation for a 75% duty cycle pulse.
6-6
Find a bipolar junction transistor with a maximum collector current of at least 9 A. From its data sheet determine the maximum collector-emitter voltage, worst case β (or hFE), worst case VCE, worst case VBE, and worst case switching time.
6-8
Design a switch using an IRF630 to drive a 25 Ω load powered from a 150 Vdc supply. Determine the drain current, required gate pulse amplitude, power delivered to the load, and the transistor power dissipation for a 80% duty cycle pulse, and the required heat sink maximum thermal resistance for TA = 60°C.
6-9
Locate a data sheet for an IRF630 MOSFET. Determine its maximum continuous drain current, maximum drain-to-source voltage, maximum gate-to-source voltage, junction-to-case thermal resistance, channel resistance at 100°C, gate-to-source voltage to drive it on, switching time, and gate capacitance.
6-10
Locate a data sheet for an IRFZ14 MOSFET. Determine its maximum continuous drain current, maximum drain-to-source voltage, maximum gate-to-source voltage, junction-to-case thermal resistance, channel resistance at 100°C, gate-to-source voltage to drive it on, switching time, and gate capacitance.
6-11
It is decided to use four IRF530s in parallel to drive a 35 Ω load from a 24 Vdc supply with a 75% duty cycle. Calculate the voltage drop across the paralleled transistors, and the power each transistor must dissipate. Is a heat sink needed? Prove your answer with a calculation.
6-18
In the circuit of Figure 6-31, transistors Q1 and Q4 are on and current flows as indicated. The load has a significant inductance. Explain, in detail how, and which Schottky diodes prevent the flyback when Q1 and Q4 are turned off.
Figure 6-31 ATTACHED
Problems
Thyristor Device Characteristics
Locate a full set of specifications for the Teccor S4006LS SCR and the Teccor Q4006LH triac. Use them to answer the following questions.
8-1
What is required to turn the Teccor S4006LS SCR on?
8-7
A 200 W light bulb is powered from a 120 Vrms line voltage, and is switched on and off with a S4006LS SCR.
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Explanation & Answer
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Running Head: POWER ELECTRONICS
Power Electronics
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Power Electronics 2
POWER ELECTRONICS
Question 6-1
As listed in the 1N4004 diode datasheet the ratings indicated shows
Average forward current If is 1A
The maximum forward Voltage Vf is 1.1V
And the peak reverse voltage Vr is 400V
Therefore, maximum power dissipation Pd= 3W
Question 6-4
The Voltage is distributed to two resistors at an equal value of R2-1K and R4-1K respectively
Consequently, the voltage across the resistor R4= 12 V
In addition the current to transistor base is
Base current = Ib=12/R3= 12mamps
The collector current which goes through the load resistance is
Rl = IC
=
24/35
Power Electronics 2
= 0.685 A
Power supplied to the load
P=VxI
= 24 x 0.685
= 16.44 W
The circuit diagram designed from the elements is shown below
Question 6-6
The conditions will be fulfilled by two BJT which are: 2N5684 and 2N3055.The two power BJT
have the capacity to handle a current of 15A for the (2N3055) and 50A for the (2N5684)
Power Electronics...