Steve Taranovich writes:
Home energy systems based on renewable sources, such as solar and wind power, are becoming more popular among consumers and will gain increasing support from governmental bodies.
In this article, the power inverter will be discussed in the context of solar energy, especially as it relates to the latest, low power microinverter architectures that make the most sense in converting a photovoltaic (PV) panel’s DC output to an AC signal for residential use.
Microinverters are installed on each individual PV panel and typically handle 300 W. Microinverters provide the benefit of scalability for those who want to start small, yet have full DC/AC conversion with maximum power point tracking (MPPT). Many people want to put their excess power back onto the power grid, which will speed up the return on investment (ROI) time and ultimately could lead to freedom from grid reliance. The technology that will enable ubiquitous architectures like this on our roof is getting closer.
An Engineer’s Guide to Power Inverters for Solar Energy Harvesting - [Link]
Ivan Sergeev writes:
This project was used as a wireless light dimmer, but in principle can be used to dim resistive loads and wirelessly turn on/off loads. The current code includes a routine to dim a light bulb in a “heartbeat” pattern, with the heartbeat frequency remotely adjustable.
The top left of the schematic shows the wall outlet (US 120VAC) being stepped down with a small transformer, then full rectified and regulated. This powers the entire board from the wall. The top right shows a microcontroller, ATmega48, its programming header, and a UART connection to the microcontroller (for debugging). The bottom right shows the XBee and its basic voltage regulation (it’s 3.3V), as well as an LED that indicates when the XBee is connected.
Wireless TRIAC dimmer - [Link]
Ivan Sergeev writes:
A switched capacitor / charge pump boost converter works by repeatedly charging a flying capacitor to an input voltage source and then stacking it on top of the input voltage source. This is achieved in the ideal schematic above by closing alternate switch pairs SW1/SW4 and SW3/SW2. When SW1/SW4 are closed, C1 is charged to voltage source V1. When SW3/SW2 are closed, C1 is stacked on top of voltage source V1. After some start up time, the big hold-up capacitor C2 is charged to 2*V1, and the load R sees roughly 2*V1 provided that it does not pull the charge out of C2 faster than it is replenished.
Discrete Switched Capacitor Boost Converter - [Link]
This reference design from Maxim is a current controlled boost driver designed for long strings of LEDs. Driving many LEDs in series has advantages over driving them in parallel. In a parallel configuration each LED will need it’s own current limiting resistor or current control, while the series LEDs make use of a single current controlled power supply. The driver must support the combined voltage of all the LEDs in the string. The reference design can supply up to 100 volts, which translates to around 30 LEDs.
App note: Current controlled boost driver for long LED strings - [Link]
Open EVSE is a Open Source Hardware/Software for charging an Electric Vehicle using the standard J1772 protocol. J1772 is used in the latest generation of EVs such as the Nissan Leaf, Plug in Prius and the Chevy Volt.
Open Electric Vehicle Supply Equipment (EVSE) - [Link]
Don Scansen writes:
Untapped energy surrounds us. Transducers to convert various energy sources into electricity that can be put to useful work are relatively straightforward to understand and implement. However, harvestable energy sources are intermittent, or at least very inconsistent, in terms of output. Many can provide only a few microwatts. Putting these very low energy sources to use requires efficient charge control electronics designed for low power.
In terms of performance, one of the most attractive energy harvesting power management ICs (PMIC) on the market is the MAX17710G+T from Maxim, which was designed from the ground up for energy harvesting and extracting the greatest amount of energy possible from the transducer element. As a result, it offers class-leading performance for this application. The PMIC allows very simple, low-cost solutions for battery charging and protection. The MAX17710G+T will provide good battery charging performance for a wide range of ambient sources and conditions. Useful power is extracted from levels as low as 1 µW and 0.8 V. Coupled to a very small form factor MEC (micro energy cell), it is a powerful combination for a broad range of energy harvesting applications.
A Hands-on Look at the Maxim MAX17710 Energy Harvesting PMIC - [Link]
This is an app note from Maxim describing how to protect your Lithium Ion batteries from reverse insertion into the charger. The circuit is a Li-Ion battery charger with an added analog comparator designed to detect when then battery is inserted the wrong way and disconnect it from the charger. [via]
Combining a linear-mode single-cell lithium-ion battery charger (MAX1551) with a comparator (MAX9001) and n-channel FET adds a layer of reverse-battery protection that protects a single cell lithium-ion battery charger and battery from damage due to backwards insertion
Protect your batteries from reverse insertion - [Link]
In 2010 Maxim acquired Teridian Semiconductor to create a device portfolio for Smart Metering applications. Recently a new device was added, the 78M6631, which is a highly integrated three-phase power measurement and monitoring system-on-chip (SoC) with a 10 MHz 8051-compatible processor core. Designed for a wide variety of applications requiring three-phase power and quality measurements, it is available with preloaded firmware that supports both delta and wye (Y or star) three-phase configurations. [via]
3-Phase Power Monitor on a Chip - [Link]
Paul Asselin has written a description of his design of a USB Lithium Polymer battery charger – [via]
I wanted to build a cheap USB LiPo charger and didn’t like the unavailability nor the price of the Maxim’s MAX1555. Searching for something better, I stumbled upon the Microchip MCP73831. It is still way too expensive in single quantities but there ain’t too many options.
The board is intentionally small and has a status LED. There really isn’t much more to it, it’s a single purpose device and just does the job. It is proudly Open Source Hardware.
Here is a simple programmable load. It’s basically a constant current sink that is controlled through a pot. The current is sunk through a high power FET which needs to be cooled to function properly – [via]
Here’s a link to a *really* simple linear constant current sink i put together
This design is about as simple as it gets. . .multi-turn pot controlled and readout done by a voltmeter:) The good news is that it works quite well for moderate loads. It was put together to regulate current flowing through a copper electroplating tank. Due to the monstrous Pentium II (or maybe III?) heat sink, it isn’t noticeably warm when eating 9A of current.
Simple analog programmable load - [Link]