Lab 3 Boost Experiment

docx

School

University of Florida *

*We aren’t endorsed by this school

Course

5317C

Subject

Electrical Engineering

Date

Dec 6, 2023

Type

docx

Pages

Uploaded by MajorRiverApe25

Lab 3: Boost Experiment 1 Outcomes: Students should understand the mechanism of the difference between theoretical and measured duty cycle. Students should be able to identify the conduction mode of a converter based on observation and measurement of the inductor current ripple. Pre-Lab: Review pages from text book starting on Page 119 for review on DCM of the boost topology (or pages 26 and 27 of Experimental Book - Boost.pdf) before answering. 1. What do CCM and DCM mean? Discontinuous Conduction Mode Continuous Conduction Mode 2. How can you tell when a converter is operating in DCM? (From the waveform of the switch node voltage and the inductor current) A converter operates in Continuous Conduction Mode (CCM) when the inductor current never falls below zero, as evidenced by the current waveform remaining above the null value at all times. Additionally, the absence of sharp drops followed by immediate rises in the switch node voltage waveform indicates that the current is never discontinuous. Should these conditions not be met, and the current does drop to zero, the converter would then be operating in Discontinuous Conduction Mode (DCM). 3. What is the condition for DCM? (About the relation between the load current and I dcm ) Iout<Idcm Set-up:

1. Set up jumpers as shown below: 2. Make the wire connections for power input and load output. 3. Set up oscilloscope to measure voltages and currents: a. Ch1 - measures switch node voltage at TP10 referencing to TP14. b. Ch2 - measures output voltages at TP12 referencing to TP14. c. Ch3 - measure inductor current at R11 with current probe. 4. Adjust the power source voltage to 10V and the load current to 0.2A. Observe the current ripple and switch-node voltage waveform. Take a picture of the waveform. [Insert your waveform image here] 5. According to the V in and I Load in following tables, conduct the experiment. Calculate the theoretical duty cycle and predict the conduction mode by comparing I Load and I dcm (refer to the formula in question 1). Then measure the real duty cycle and the real conduction mode. Fill them in the following 2 tables. Duty Cycle I Load = 0.2A I Load =1.0A D th (1) D meas (2) D th (1) D meas (2) V in =10V 0.583 0.585 0.583 0.585 V in =16V 0.333 0.27 0.333 0.27 (1): Theoretical duty cycle. (2): Measured duty cycle.

Conduction Mode I Load = 0.2A I Load =1.0A CCM/DCM th (3) CCM/DCM ex (4) CCM/DCM th (3) CCM/DCM ex (4) V in =10V DCM CCM CCM CCM V in =16V DCM DCM CCM CCM (3): Theoretical expectation. (4): Experimental result. Vg = 10 V fs = 500 KHz L = 10 µH, Dth = 0.583, Idcm = 0.24 A Vg = 16 V fs = 500 KHz L = 10 µH, Dth = 0.333, Idcm = 0.35 A If Iout > Idcm CCM, If Iout < Idcm DCM V = 10 V Iout = 1 A Idcm = 0.24 CCM V = 10 V Iout = 0.2 A Idcm = 0.24 DCM V = 16 V Iout = 1 A Idcm = 0. 35 CCM V = 16 V Iout = 0.2 A Idcm = 0.35 DCM Post - Lab Questions: 1. In the theory section of the TI Manual the following is stated: Using unit analysis, prove that this formula makes sense. A s s V L f M M V A I s out cm      * * 1 2 ) 1 ( ) ( 3 d 2. Is the measured duty cycle higher or lower than the calculated one? Why? When the Vin=10V and the Vin=16V, the duty cycle that has been measured aligns closely with the theoretical duty cycle derived from calculations, confirming that the observed outcomes are consistent with the anticipated results. The variations could be because of the environment that is not ideal because of phones and computers, the produce some interferences. 3. Does your expectation about conduction mode match with the experimental result? If it does not, do you have any idea about the reason? For Vin = 16 V the conduction mode for, I = 0.2 match with the expectation mode (DCM) because the Iout<Idcm and for I = 1 match with the expectation mode (CCM) because Iout>Idcm.

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

For Vin = 10V the conduction mode for I = 1 match with the expectation mode (CCM) because the Iout>Idcm, and for I = 0.2 doesn’t match with the expectation mode (DCM), because theoretically Idcm = 0.24 and Iout = 0.2, so Iout < Idcm and conduction mode should be DCM. But because in the inductor current waveform of the lab, it would not happen. 4. The boost converter in this lab used a MOSFET to replace the diode (the D shown below). What is the advantage? Note: the schematic of the boost converter in this lab is on page 20 of Experimental Book - Boost.pdf . With the mosfet, the current that pass it can be positive on-state current and can also conduct negative current in some circumstances. So, it reduces conduction losses.