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1 Aug 2012

The basic concept behind thermoelectric (TE) technology is the Peltier effect—a phenomenon first discovered in the early 19th century. The Peltier effect occurs whenever electrical current flows through two dissimilar conductors. Depending on the direction of current flow, the junction of the two conductors will either absorb or release heat. Explaining the Peltier effect and its operation in thermoelectric devices, is a very challenging proposition. It ultimately keys on some very complex physics at the sub-atomic level. Here we will attempt to approach it from a conceptual perspective with the goal of giving readers an intuitive grasp of this technology (i.e., without getting too bogged down in the minutia). [via]

Peltiers FAQs - [Link]

27 Jul 2012

Don Scansen writes:

Ambient light, thermal gradients, vibration/motion, or electromagnetic radiation can be harvested to power electronic devices. At the same time, all energy-harvesting-based systems need energy storage for times when the energy cannot be harvested (e.g., at night for solar-powered systems). Rechargeable batteries ‒ known as “secondary” cells to differentiate them from “primary” or single-use cells ‒ are usually specified for this task. This article will examine the various secondary cell technologies available to energy harvesting system designers looking for a cost-effective and powerful battery solution.

Primary and secondary batteries contain the same basic structure of a cathode, an anode, an electrolyte for moving charge between the terminals, and a means to separate them. Secondary cells are distinguished by the type of rechargeable chemistry employed, such as nickel-cadmium or lithium-polymer, or solid-state thin film.

Storage Battery Solutions for Energy Harvesting Applications - [Link]

17 Jul 2012

Steven Keeping writes:

Stretching the power budget is a common challenge for design engineers developing battery-powered products. Consumers expect more functionality and longer run times from each new product iteration, but, because battery technology improves only very slowly, this is proving increasingly difficult.

Switching DC/DC converters help to improve battery life because their high efficiency helps minimize power consumption. However, efficiency is not constant across the output current range, tailing off markedly at low loads. This is particularly a problem for battery-powered devices that often spend long periods in “standby” or “sleep” modes. Such inefficient operation at low loads results in flawed battery life calculation, shorter product operational times, and disappointed consumers.

Techniques to Limit Switching DC/DC Converter Inefficiency During Low Loads - [Link]

29 Jun 2012

This is a dual-output switch mode power supply reference design based on the MAX17116. The part and reference circuit can provide both negative and positive supplies to AMOLED displays. [via]

The MAX17116 includes two current-mode 1.4MHz switch mode power-supply (SMPS) regulators for active-matrix organic light-emitting diode (AMOLED) displays. The positive supply is provided by a step-up regulator with a synchronous rectifier. The negative supply is provided by an inverting regulator with a synchronous rectifier.

Dual-output DC/DC power supply for AMOLED - [Link]

27 Jun 2012

Sam Davis writes:

Individual solar-panel systems produce dc power for remote applications while also storing energy in a rechargeable battery supported by a battery-charger IC.

In non-utility grid applications solar panels produce dc power for emergency roadside telephones, navigation buoys, and other remote loads. Virtually all 12-V-system solar panels comprise a series of photovoltaic cells that have a maximum output power of less than 25 W. In producing this power the solar-panel system uses a battery to provide power when the panel is “dark.” The rechargeable battery can supply power for long periods of time, requiring a charger that can properly operate a solar panel.

Meeting this need is Linear Technology’s LT3652 monolithic buck-charger IC, which operates with a single solar panel. The IC uses average-current-mode control-loop architecture to provide constant current/constant voltage (CC/CV) charge characteristics with a programmable charge current. The charger can be programmed to produce a 14.4-V float voltage. Housed in a 3- × 3-mm DFN-12 package, the IC can charge a variety of battery configurations, including up to three Li-Ion/Polymer cells in series, up to four Lithium Iron Phosphate (LiFePO4) cells in series, and sealed lead-acid batteries up to 14.4 V.

Power-Tracking Battery-Charger IC Supports Solar-Power Systems - [Link]

23 Jun 2012

Publitek European Ed writes:

Daylight harvesting is becoming increasingly important in the design and implementation of commercial lighting systems. Being able to integrate the natural light from windows with flexible, controllable sources of lighting helps improve the work environment and cut energy bills.

Being able to have closer control of the lighting systems in a commercial environment is a key element to this strategy and energy harvesting can play an important role. Being able to have flexible placement of control pads for a commercial lighting system is an important requirement as office space is regularly reconfigured as existing clients grow and change their requirements and new clients have new requirements.

Smart Lighting in the Enterprise - [Link]

17 May 2012

www.adafruit.com writes:

The design is based off of the EEVblog design shown on episode #102. The purpose of the device is for when you need a constant load to test things like power supplies, or batteries. No matter what the voltage coming out of the power supply, the constant current dummy load will adjust automatically to provide the same amount of current.

DIY Constant Current Dummy Load - [Link]

5 May 2012

TRACOPOWER launches the high performance TEN50 Series with 12 models providing 50W power in a 1”x 2”x 0.4 “ compact package.

Today already almost all of applications require a high efficiency of a voltage conversion. When we add to this requirement also saving of space and a galvanic isolation, we´ll get to widely used components – DC/DC modules.

The TEN 50 Series models feature a very high efficiency of up to 92%. Excellent efficiency is maintained in over a wide load range and no minimum load is required for an accurate output regulation. They are available in three basic groups – TEN 50-12xx, TEN 50-24xx a TEN 50-48xx with a wide input voltage range (2:1).

Low thermal losses and the use of highest grade components allow an operating temperature range of –40°C to +85°C while up to 55°C no forced air cooling is required. With an optional heat-sink this temperature can even be increased. An operation without a forced air cooling is possible even at higher temperatures – at an adequate power derating ( 2%/K above 55°C and 2,5%/K above 65°C). The TEN 50 Series comes with remote On/Off function and have an adjustable output voltage (± 10%). Protection against overload and short-circuit, very compact dimensions and a 1500VDC isolation enable usage of TEN 50 modules in virtually any power application.

50W DC/DC converters TRACOPOWER with the highest power density - [Link]

2 May 2012

Scrawny 500mA USB charger insufficient for your hunger for power? Try this 3.6 amp USB charger based on the LM2700 boost switch-mode IC. [via]

This design is inspired by the Minty Boost but it fixes some of the issues that I had with it. The Minty Boost is limited to 600mA due to the LT1302 chip. The Super Boost uses the LM2700 which can push up to 3.6A. This will enable i-devices to draw up to there maximum of 1A which will enable a faster recharge.

Super Boost 3.6A USB charger based on LM2700 - [Link]


6 Apr 2012

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]





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