This teardown article will delve into the architectural design and components of a solar inverter card starting from the Solar panel DC inputs and working our way through the DC to AC conversion process to the AC output that is sent out to the power grid. We will show what features need to be implemented into such a design to meet various safety and other performance standards as well as stringent power company demands upon the signal that is put onto their grid.
Teardown: The power inverter – from sunlight to power grid - [Link]
Bryon Moyer writes:
The development of wireless sensing technology has made possible tasks that would have been unthinkable in years past. Sensors can be installed where it is impractical or impossible to run a communication wire; their ability to communicate wirelessly, as long as they are within range of a hub, means that it is possible to gather data in places or situations that were previously inaccessible.
The inability to run a communication wire to the sensor also means no power line as well. Sensors need power both to sense and to communicate, so that has typically meant using a primary battery. While you would presumably select a battery with as long a life as possible, the battery is still unlikely to outlast the life of the sensor, meaning that someone will have to go out and replace the battery at some point – which can be expensive.
Managing the Energy and Lifetimes of Thin-Film Batteries - [Link]
This is a simple li-ion charger without a dedicated li-ion charger IC. This circuit can be used to efficiently and intelligently charge any single cell Li-ion battery pack like mobile battery, digicam battery, etc.
- Charging via mini-USB connector which is very common.
- Charging status display by LED
- Simple circuit by using opamp, resistor, and not by any complex dedicated IC or micro-controller.
- Charges completely drained (0V) battery packs.
- Max charging current 500mA (limited by USB supply), depending on battery.
Simple USB DIY Li-ion battery charger - [Link]
Planning on powering that next über-low-power board of yours from a measly CR2032 coin cell? Read this app note to understand exactly what the limitations of coin cells are: [via]
When designing a small wireless sensor node to be powered by the popular CR2032 coin cell, some sources claim there is a 15mA “limit” and that drawing more current is not possible or will “damage” the battery. This may give the impression that at 15mA everything works perfectly and battery capacity is great, while at 16mA nothing works. There is little public information available to explain why such a limit exists (if it indeed does exist), and little information explaining why 15mA would be a “magic number”.
Understanding Coin Cell Limitations - [Link]
The TPS92510 by Texas Instruments is a 1.5-A constant current DC/DC buck converter with a combo of frequency synchronization, pulse-width modulation (PWM) dimming and thermal foldback firsts. Used with the WEBENCH LED Architect, users rapidly design a power management circuit to drive a string of up to 17 high-brightness LEDs at up to 97% power efficiency in automotive, industrial, and general lighting applications.
The TPS92510 operates with fixed frequency by using its internally generated clock or via synchronization to an external PWM clock source. Thermal foldback ensures light output remains even in an LED over-temperature condition, adding safety. [via]
- 3.5-V to 60-V input voltage operating range supports a wide variety of DC LED lighting applications, including area and street lighting.
- Fixed switching frequency range from 100 kHz to 2.5 MHz can be synchronized to optimize for efficiency or solution size.
- LED thermal foldback with external negative temperature coefficient (NTC) protects LED array from over-temperature while maintaining reduced light output.
- Dedicated PWM dimming input from 100 Hz to 1 kHz adjusts LED brightness without color shift or perceivable flicker.
Buck converter drives high-brightness LEDs - [Link]
Carolyn Mathas writes:
The LT3763 by Linear Technology is a synchronous buck LED driver controller that delivers more than 300W of LED power. With an input voltage range of 6V to 60V, it targets such applications as automotive, industrial and architectural lighting. Output voltage from 0V to 55V enables it to driver LEDs in a single string. The driver features input and output current monitors and limiting and accurate input and output voltage regulation.
Buck LED driver delivers 300W of power - [Link]
LT series LED drivers with 10-100W power represent a complete solution with wide possibilities of control. Exceptionally narrow and slim design, remained even at high-power versions, provides a high flexibility of use.
Power supplies for LED lighting (so called drivers) are available from many producers, in a various qualitative level. Why to decide just for the LT series from German company Friwo? Here are few reasons:
- precise design, safe operation and a long lifetime
- voltage and current regulation in one device
- high efficiency and a possibility of dimming in a range of 0-100% directly via a CTRL pin
- modules are available in 10-100W power, with a possibility of customization by laser directly at production also available a module for dimming – so called DIMMbox, further expanding possibilities of control (switch, 1-10V, DALI) and with a possibility of synchronization with up to 1000 slave units
- very small cross section of modules (21x30mm, resp. 24x30mm at LT100) – applicable even in very tiny conditions
Wide control possibilities of LT series modules are perhaps the most interesting. Modules contain a galvanically isolated CTRL input, by which it is possible to switch on/ off the module without disconnecting from 230V mains. CTRL pin also serves for regulation of an output current. For this purpose, only one resistor (or a potentiometer) is necessary – connected between SEC+ and CTRL pins, with a value counted by a simple formula in the datasheet. The output current can also be controlled by an external voltage in the range of 0-1,8V connected to SEC- and CTRL, as well as by means of a PWM TTL (0/5V).
Further possibilities of control are provided by a standalone additional module DIMMbox. DIMMbox operates as an (almost) lossless PWM regulator with a MOSFET switched at f=600Hz. DIMM-BOX connected to any series LT driver enables to regulate an output current in a range of 10-100% or 0% (OFF) via a usual switch (switch-dimm“ mode), via a linear voltage 1-10V and also a DALI interface. DIMMbox tests after switching on, which of three methods of control is used and consequently accepts only signals from a given input – until switching off the module. DIMMboxes can be connected through SYNC inputs, ensuring the same level of dimming for all modules. Enclosed pictures will provide you the best idea about possibilities of connection.
Friwo drivers not only drive your LEDs but even control them - [Link]
Steven Keeping writes:
Lithium-ion (Li-ion) batteries have become popular for portable electronics such as laptop computers and smart phones because they boast the highest energy density (capacity per unit volume) of any commercial battery technology. Other benefits include thousands of recharges and no occurrence of the “memory effect” that plagued early nickel cadmium (NiCd) rechargeable cells.
However, it has been a tough design challenge to get the technology to where it is today. Lithium is a highly reactive material that can, for example, burst into flames if it comes into contact with water. Engineers and scientists have worked hard to develop novel compounds that can leverage the advantages of lithium while producing inexpensive, reliable, and safe batteries.
A Designer’s Guide to Lithium Battery Charging - [Link]
Computer Precision for Power Tools @ NYTimes.com – [via]
WOODWORKING is a tricky skill to master. Students learn to measure carefully before they reach for a saw, and to cut as true to the design as hand and eye allow. But, even so, precise cutting is a painstaking job, full of pitfalls and mismatched moldings.
Alec Rivers, a Ph.D. student at M.I.T., guides a cutting tool through wood by watching a computer screen.
Now computers and their tireless calculations may bolster the skills of many people who want to create well-cut picture frames, inlays or furniture but lack the dexterity.
Alec Rivers, a Ph.D. student at the Massachusetts Institute of Technology, and colleagues have created a prototype for a compact, computerized addition to power tools that automatically performs precision measuring and cutting.
The system, which has a tiny camera, motors and a video screen, takes part of the pain out of woodworking, by using what Mr. Rivers calls “tool GPS.”
Computer Precision for Power Tools - [Link]
Stephen Evanczuk writes:
Energy-microharvesting applications such as wireless sensor nodes require periodic bursts of power well beyond that available in steady state from most ambient sources. In this respect, supercapacitors offer performance characteristics that are well suited for energy-harvesting environments. By combining supercapacitors with appropriate power and charge management circuitry, and using specialized devices from manufacturers including Linear Technology, Maxim Integrated Products, and Texas Instruments, engineers can exploit microharvesting techniques in applications with demanding peak power requirements.
Power Management ICs Simplify Integration of Supercapacitors in Energy Microharvesting Designs - [Link]