Power electronics lesson plan
Advanced: switches, inductors and heat: buck and boost converters from loose parts, PWM, MOSFET drivers, H bridges, efficiency, and a regulated supply you set from its formula.
Objectives and materials
By the end, students can
- Step voltage down and up with a switch, an inductor, a diode and a capacitor.
- PWM, gate drive, and four switches around a motor.
- Where the lost watts go, and linear against switching.
- A regulated supply, set to the volt and signed off.
Materials for the whole unit
- Arduino Uno R3
- Battery: AA, coin cell, LiPo
- Capacitor
- D4184 dual MOSFET switch module
- DC jack and adapter
- DC motor
- DC voltage source
- Diode
- DRV8871 motor driver
- Filament lamp
- Full-size breadboard
- Function generator
- Half breadboard
- Inductor
- IRF520 MOSFET module
- LED
- LM2596 buck converter module
- LM317 regulator
- MOSFET
- Multimeter x 2
- Potentiometer
- Resistor x 2
- Slide switch
- Voltage regulator
Every part is already on the simulator’s bench, so there is nothing to buy or hand out. The counts are the most any one lesson uses, if you build it on real breadboards too.
Converters
Step voltage down and up with a switch, an inductor, a diode and a capacitor.
| Lesson | Time | What students do |
|---|---|---|
| The buck converterA buck converter from loose parts: a MOSFET switching 12 V twenty thousand times a second, an inductor, a diode and a capacitor, and why its output is the duty cycle times the input. | 30 min |
|
| The boost converterThe same four parts rearranged so the output climbs above the input: an inductor that kicks, a diode that catches the kick, and Vout = Vin / (1 - duty). | 30 min |
|
Materials
- Capacitor
- DC voltage source
- Diode
- Function generator
- Inductor
- MOSFET
- Multimeter
- Resistor
Check for understanding
Each student finishes "The boost converter" on their own, without opening the hints. The simulator checks 5 of its 5 steps as they go.
Then ask each one to explain, in a sentence or two, the last thing it asked of them: "Never run a boost with no load".
Switching
PWM, gate drive, and four switches around a motor.
| Lesson | Time | What students do |
|---|---|---|
| PWM and duty cycleA lamp dimmed by switching it fully on and fully off a thousand times a second: duty, frequency, the average a meter reads, and how analogWrite does the same thing. | 35 min |
|
| MOSFET driversTwo MOSFET boards on one pin: why the IRF520 module is only partly on from 5 V and off from 3.3 V, what a logic-level gate is, and what a gate driver is for. | 30 min |
|
| H bridges and current limitsFour switches around a motor: forward, reverse, brake and coast on a DRV8871, why two switches on one side must never close together, and how the chip's current limit is set. | 35 min |
|
Materials
- Arduino Uno R3
- Battery: AA, coin cell, LiPo
- D4184 dual MOSFET switch module
- DC motor
- DC voltage source
- DRV8871 motor driver
- Filament lamp
- Full-size breadboard
- Function generator
- IRF520 MOSFET module
- MOSFET
- Multimeter x 2
- Resistor x 2
- Slide switch
Check for understanding
Each student finishes "H bridges and current limits" on their own, without opening the hints. The simulator checks 6 of its 6 steps as they go.
Then ask each one to explain, in a sentence or two, the last thing it asked of them: "Coast".
Heat
Where the lost watts go, and linear against switching.
| Lesson | Time | What students do |
|---|---|---|
| Heat and efficiencyThe same 5 V made two ways from 12 V: a 7805 that burns the difference as heat and an LM2596 that switches, measured with two ammeters, and the heatsink math that decides which you need. | 35 min |
|
Materials
- DC voltage source
- LM2596 buck converter module
- Multimeter x 2
- Resistor x 2
- Voltage regulator
Check for understanding
Each student finishes "Heat and efficiency" on their own, without opening the hints. The simulator checks 6 of its 6 steps as they go.
Then ask each one to explain, in a sentence or two, the last thing it asked of them: "Linear or switching?".
Boss project
A regulated supply, set to the volt and signed off.
| Lesson | Time | What students do |
|---|---|---|
| Boss: a regulated supplySet an LM317 adjustable supply to exact voltages from its formula, find its dropout, prove it regulates when the input changes, and work out its heat. | 35 min |
|
Materials
- DC jack and adapter
- Half breadboard
- LED
- LM317 regulator
- Potentiometer
- Resistor x 2
Check for understanding
Each student finishes "Boss: a regulated supply" on their own, without opening the hints. The simulator checks 6 of its 6 steps as they go.
Then ask each one to explain, in a sentence or two, the last thing it asked of them: "Sign it off".
Teach this unit as a class
Start a class from this course and its 7 lessons are assigned in one go, in order. Students join with a six-character code or printed login cards, and each one’s work comes back to you.
The class tools are free for 30 days for one class of up to 20 students, with no card. The lessons themselves are free either way.