operation, continuous current in L, very low ripple in Vout, Vin is constant, and = + V out

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1 EE462L, Power Electronics, Test 2. Name You must show all work to receive credit. October 15, 2010 Problem 1. Boost Converter. Use the standard assumptions (i.e., lossless, steady-state Vout 1 operation, continuous current in L, very low ripple in Vout, Vin is constant, and = Vin 1 D i I L i d I out in V in L i C C + V out ). Operating Conditions: V = 40V, Vout = 80V, P = 100W, f = 100kHz, L = 100microH Carefully sketch two-cycles of operation on the voltage and current graphs provided for each of the following. Show the amp or volt values at corner points. Inductor current and capacitor current. Inductor voltage and capacitor voltage. Input current. Track power flow and confirm power balance by determining and plotting two-cycles of operation for each of the following on the power graph provided. Show values at the corner points. Power delivered by Vin Power absorbed by L Power absorbed by C Power absorved by Vout Page 1 of 3

2 EE462L, Power Electronics, Test 2. Name You must show all work to receive credit. October 15, 2010 Problem 1, cont. Show Y-Axis scale. Show corner points on all waveforms. Volts Periods Amps Volts Periods Watts Volts Periods Page 2 of 3

3 EE462L, Power Electronics, Test 2. Name You must show all work to receive credit. October 15, 2010 Problem 2. The measured I-V curve for a solar array at a given insolation level is shown below. If you connect the array through a boost converter to a 100Ω load, what value of D will provide maximum power to the load? Page 3 of 3

4 EE462L, Test 3. November 19, 2010 Test 3 is a lab practicum. There will be a sign-up sheet with 15-minute slots so that you and your newly-assigned partner can individually show your work and demonstrate your prowess in circuit understanding, scope use, and circuit testing to Dr. Grady. The 15-minute slots will be scattered over the period Monday, Nov. 22, through Thursday, Dec. 2. To get a good grade, it is essential that you rehearse and polish your presentation beforehand. Partners do not necessarily get the same grade, so both should be prepared to do the entire demonstration by themselves. Here are the steps: 1. Today, there is no locker change, but you ll get a new partner for Test 3. You ll be given a MOSFET firing circuit and PI controller previously built and tested by one or both of you. You ll also be given a PV isolation PC board, a PV chip, and a one of the buck converters. 2. Build the PV isolation board according to the 13_EE462L_PV_Isolator.pdf document on the web page. It is not necessary to perform the optional scope waveform checkout step. Instead, you can use 12Vdc on the input side of the PV chip to verify that the isolated output voltage makes sense. 3. Modify the PI controller as described on the front page of 13_EE462L_PV_Isolator.pdf. This means removing the voltage divider (100kΩ, 1.5kΩ, and ceramic capacitor). Solder the PV isolator s +/ outputs to the top(+) and bottom( ) nodes where the 1.5kΩ resistor was. 4. Wire together the buck converter, PI controller, PV isolator circuit, and 10Ω power resistor. Be sure to attach a 10µF high-frequency bipolar cap (the tall red caps) to the input terminals of the buck converter. For now, it is OK to use a (Variac+Transformer+DBR) as a 40V power source. But when you demonstrate your work for a grade, you will power up with a solar panel pair if at all possible. Even a cloudy day will provide the needed power. 5. Re-tune the PI Controller to provide regulated 13.8V to the 10Ω power resistor. Tuning includes D-limit, bump tests, proportional gain, and integrator time constant. 6. Make sure that your circuit is working properly and robustly before your time slot. Rehearse. Be sure to practice with a solar panel pair.

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