Deriving Power Electronics from Transistors and Microcontrollers

Introduction

With the principle of Part Count Reduction within OSE's Module Based Design approach - we are interested in using this principle to facilitate the design of electronic circuits, and in particular, power electronic circuits.

With low cost microcontrollers (700 Mhz Pi Zero is $5) and transistors (IGBTs are $1/kW of power handling) - we can design low cost power electronics. Let's look at how this can be done for simple learning circuits which can serve as a basis of robust industrial applications. These examples show the limits of power for various devices.

Inverter

• 10kW direct solar power inverter case using Arduino and IGBTs for $25. Inverter at 120V for regular loads such as power tools.
• Start with 1kW of PV for test, then move to 10kW.
• 10kW case is scalable to 100kW
• Slide 12 of Open_Source_PV_System#Initial shows max power point - current at about 9A and voltage at 31V - for PV panels.

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1kW-10kW

• 4 PV panels in series at 120VDC. 9A.
• Arduino produces a square wave at 60 Hz at 50% duty cycle
• Inversion occurs through an H bridge
• Cost: [4] $4 for IGBTs (18kW continuous) [1]
• Gate drivers - Arduino doesn't have enough juice to power IGBT gate efficiently - [4] $1 - [2]

10kW-100kW

• Let's see cost of 54kW -
• At 240V - need strings of 8 solar panels in series
• Protection - 225 amp circuit breaker - $75[3]
• 54kW for the above
• Inversion - Just scale the IGBTs above. Use 3 instead of 1 for
• For 54kW - switching and controller cost is $75 for DC source. Rest is safety and cooling.