Crash Course on Power Electronics

For mastering the Power Electronics Consruction Set component of OSE work - step one is an overview tutorial on power electronics. This means basic explanations of multi-puropose controllers and their connection to power-handling elements. This includes:

1. How to control current output from any AC or DC input
2. How to control voltage level coming out of any AC or DC input
3. Managing conversion from AC to DC for various purposes.

Explanations should include wiring for stock components, such as PWM signal generators, and corresponding power handling elements.

The above should address full modularity, and scalability. By modularity - we mean plugging in additional units for added power, or added voltage.

The practical tools should also be explained, in terms of open source software for:

1. Designing and modifying circuits
2. Generating fabrication files
3. Producing them/getting them produced

Thus, the above should cover conceptual and practical understanding of building, at all scales from watts to 500kW (the scale we deem sufficient on all counts for a full, resilient community):

1. Inverters
2. Converters
3. Charge controllers for various generators feeding a microgrid
4. Inverter welder power supplies
5. Welder power supplies.
6. Plasma cutter power supplies
7. Induction furnace power supplies
8. DC, AC, and stepper motor controllers
9. Battery chargers

The point is to start with conceptual understanding of an integrated framework for handling applied power electronics, and then moving to particular applications. If presented conceptually, in a modular, open source design fashion - with modules for functionality and for scalability - I don't see why a non-expert like myself cannot pick up on the material to be very proficient in creating/building real-world applications.

Specifically, here are some examples of the needs of OSE:

1. a low-cost, high-power windmill cannot be designed properly without mastery of power electronics for handling power that fluctuates widely.
2. Mastery of power electronics is essential for building a robust charge controller for a steam engine feeding a microgrid or a battery bank - especially if the steam engine is powered via fluctuating solar concentrator power

The end point of this is a Crash Course on Power Electronics, in the general framework of our approach to creating resilient communities.

Common Types of Power Circuits

Converters

Power converters are the most common type of power electronic circuits. Converters take electrical power in one form and reshape it into another. The following table shows the different conversions and the common circuits used.

Conversion	Common Circuits	Notes
AC to AC	Transformer	Transformers are used when the output frequency is the same as the input frequency. If the frequency needs to be changed, then a Rectifier-Inverter cascade needs to be used.
AC to DC	Rectifier	A rectifier alone will produce an unregulated DC voltage. Rectifiers are often followed by a DC to DC converter or other voltage regulator.
DC to DC	Switching Mode Converter	There are many ways of converting DC voltage, but Switching power supplies tend to be the most versatile and efficient.
DC to AC	Inverter

Efficiency is a key consideration with all converters. Power lost to inefficiency results in heat. This means that more expensive parts may be needed, more parts added for cooling systems, and an overall higher stress on the whole unit. Converter circuits will have a sweet spot where they are most efficient, and then efficiency will roll off as the operating point moves away from that spot. This can make it difficult to make a single unit that is capable of a wide range of operations.