Electronics Engineering Magazine

Showing posts with label Power-Electronics. Show all posts
Showing posts with label Power-Electronics. Show all posts

Wednesday, February 01, 2017

Desktop Power Supply Immunity

Make the desktop architecture like laptop with regards to Power Electronics. I think now RAM's consume lower power. So every Desktop can come with a Li-ion Backpack based on some standard. 10Ahr 12V Rechargeable Battery. The entire Motherboard works on the 12V DC supply that uses Float Charging from mains.

Power Electronics & Solar Energy

The supply to computer is always derived from battery, the battery being constantly replenished. The charger also supplies power to computer board over the battery itself. Many lighting/inverter systems use this. The SMPS now is only a intelligent charger. Other voltage levels with DC/DC converters from that 12V.

Desktop Power Supply Immunity

Advantage -

1 - A user can easily upgrade the 12 V bus, another 12 V battery with smart charger; gives a boost of backup time. Probably intelligent batteries can come with built in float chargers, so that they can they can be bussed to form a 12v Tiny power grid for home which includes solar cells.

2 - When just the backpack is used, power fails. Harddisk, Monitor etc. sent to standby, low power mode. CPU then goes to quiescent state. The RAM keeps all data intact but goes to a low power mode. Alternatively quickly write a RAM image on a Flash Layer Built over RAM.

This makes the PC Impervious to Power Supply or UPS or other problems. Moves the desktop system to a 12 V standard. Drives desktop PC development to more Power Efficient designs.

Switching Supplies and SMPS

Easy integration into automobiles, bus, etc which have DC grid. Remote areas where no power is there. This will ensure desktops have a role in the future.

The charger SMPS has 1A charging current for Battery and 3A max for Computer. Total 4A max. A SuperCap can be added parallel to the Battery for Extra Inertia.

When power fails, in few seconds the system goes to standby. No program need to be closed. When power is restored they system comes up with windows and programs in the same positions of the last frozen state.

When a UPS is used, the system does not go down at all. The UPS just consists of a 10A Charger and a 12V 20AHr Battery. If the house has a 24V DC bus which is battery supported too. Then this can be used. As 24V is being developed as a new standard for internal power distribution. EMerge Alliance. The PCs also can move to this manageable and safe standard for homes.

delabs - 2010

Wednesday, April 06, 2016

The MOSFET in Power Electronics

delabs Notes - In a Circuit Module, if all Power and Signal Polarities are reversed. All NPN to PNP, All N-Channel to P-Channel and Vice Versa. All Diodes and Caps too turned around. This Topsy Turvy or Mirror Design ought to work in Theory. It has worked for some circuits in practice too in my experience. ?

Some believe that N-Channel is more Robust than the P Type. In Bipolar Transistor NPN is more trusted for the final output stages. The NPN Transistor and N-Channel turn-on by a Positive control bias. It may be inappropriate to say this mosfet is NPN or PNP.

The MOSFET in Power Electronics

The traditional metal–oxide–semiconductor (MOS) structure is obtained by growing a layer of silicon dioxide (SiO2) on top of a silicon substrate and depositing a layer of metal or polycrystalline silicon (the latter is commonly used). As the silicon dioxide is a dielectric material, its structure is equivalent to a planar capacitor, with one of the electrodes replaced by a semiconductor.

If the MOSFET is an n-channel or nMOS FET, then the source and drain are "n+" regions and the body is a "p" region. If the MOSFET is a p-channel or pMOS FET, then the source and drain are "p+" regions and the body is a "n" region. The source is so named because it is the source of the charge carriers (electrons for n-channel, holes for p-channel) that flow through the channel; similarly, the drain is where the charge carriers leave the channel. MOSFET - Wikipedia

This application note discusses the breakdown voltage, on-resistance, transconductance, threshold voltage, diode forward voltage, power dissipation, dynamic characteristics, gate charge and dV/dt capability of the power MOSFET.
Application Note AN-1084 Power MOSFET Basics - IRF

A MOSFET is a transistor. It is a Metal Oxide Field Effect Transistor. Here are the symbols for FETs and MOSFETs: The MOSFET How the MOSFET works

The conductivity of the path from Source to drain is controlled by applying a voltage between the gate and the body of the semiconductor. N-channel enhancement MOSFET

See this simple circuit that explains everything
n-channel MOSFET switch - George Watson, Univ. of Delaware, 1996.

Wednesday, March 02, 2016

Power Electronics Design Methods

I first saw this practically in the Orthodox Cherokee SMPS. This is where we differentiate from Engineered Products and just Mass Production without following standards. The Cherokee SMPS was a work of art, perfect in all respects.

The Copper Desert or Isolation Land

There is a No Man's Land in PCB. Any good power electronics designer should/will know. Product Safety and HV Isolation, Quality and Reliability all depend on this.

High Energy Circuits

Power Electronics Design Methods

These things don't come overnight, it is a culture, learning, experience and integrity of some of these American Firms. Reliability and Product safety are important. Every human values his life very much. A manufacturer too should appreciate this.

Coming back to isolation, Keep in mind creepage distance, High energy circuits and Low voltage circuits should have clear isolation, use the best insulation. Fire and shock hazard. Mains HV transitions, spikes.

Regulated High Voltage Power Supply

Power supply faces all these, even other areas where a Human Life or Property can be endangered.

HV High Voltage Reliability and Safety

Use a Servo Stabilizer or CVT Constant Voltage Transformer or at least an Isolation Transformer. The First Defense form HV Surges, Spikes.

High Voltage Polyester & Polypropylene Metallized Capacitors in Stepdown Supplies should be Fire Retardant & Self Healing with a MOV too.

Saturday, October 18, 2014

Power Electronics and Mains Power

Updated pages, and integrated new pages with some explanations. These are related to mains power and power electronics.

Power and Energy - Mains Voltage and Power Circuits

Electrical Power can be used for most anything. It also can be stored and used later using Batteries. Alternative Energy Solutions like Solar, Wind and Tidal are providing new sources of Energy.

Fossil Fuels are running out and we have to become more energy efficient. Notebooks and Tablets are fast replacing desktop computers. Network servers and Cloud Solutions still use more power than needed. We have to use power for Productive and Creative activities.

Wastage of too much power leaves a mark, a carbon footprint, we also should shift to the low safe voltage standard of 24V. This will make conversion and distribution safe and solar energy friendly.

Power Electronics & Energy Systems

Power Electronics & Energy Systems

Tables related to Power Electronics

Discrete devices and other circuits

Friday, October 17, 2014

Electromagnetic Relays and SSR

Electromagnetic Relays - 
Electromagnetic Relay
NO - Normally Open
when the relay is not energized or activated, this terminal is open-circuit.

NC - Normally Closed
when the relay is not energized or activated, this terminal is closed circuit.

COM - The Common
Center Terminal in relays. This is the center terminal that closes circuit with NC-NO.

The terminals are potential free and floating and are insulated from the control signals or coil windings by many kilo volts. Many provide visible isolation. These terms apply to SSR or Big Contacters too.
Solid State Relays -

These designs were improvements i made on the Application Notes of Motorola Semiconductor (freescale) and Thomson CSF (stmicro) Thyristor Data. The parts are still available, now made by other firms. You can also find similar equivalents.

Solid State Relays - SSR

Solid State Relays - SSR

They are called SSR as there are made of semiconductors and have no moving parts to wear out. They do generate heat depending on load and switching. Thyristors are used in most as they are rugged, mosfets and IGBT may also be used for various applications.

In this section you will find SSR designs and PCB layouts which you can study. These were made and sold by me years ago. So the PCB layouts have gone thru some revisions and they worked quite well.
Applications -

Many machines and equipment use some SSRs in their products which may need replacement. So the SSR is not only sold to OEMs but also to Service-Maintenance Market. These are also modified as Output Modules for digital outputs coming from embedded systems or Computers.

Wednesday, October 15, 2014

Power Electronics Section

Here are power supply, inverter, drives, chargers and high current equipment diagrams and links. There are Mosfet and Thyristor circuits too.

Power Electronics Section

Power Supplies, Inverters, UPS, Chargers, Electro Plating, Precision Welding-erosion, Coating Metals and many other Processes are made of high current circuits. Even in measurement of parameters like Micro-Ohm high currents are involved. Electronic Circuits are required in such products to give control to time, current, frequency and voltage in order to accomplish with the required precision a process or job.

Power Electronics Section - delabs
In any power equipment, efficiency and reduction of bulk is crucial so SMPS and high frequency control is an important part of this domain. These products also generate EMI-RFI. Product Safety Study is also vital.

The Power Circuits Section has been updated.

Monday, August 06, 2012

Front End Security for SMPS

Now we have smps in most everything. AC Adapters and CFL lamps and many Home Consumer Electronics. The Failures of these units are on the rise. The Cooper transformers are out, but the SMPS reliability is falling.

Designing and manufacturing a SMPS facing a 230V input constantly, is not easy. You cannot Mutz your way in this, in a cost-cutting spree of this Vital Organ, just to have a competitive advantage of 'a lower cost product' (read cheap).

Now 230 V AC 50 Hz is not what you think it has, it has EMI-RFI, Inductive Kickback Spikes from the neighborhood, resonating and ringing with the RLC network that your home wiring forms. Lightning and Atmospheric Static that may strike at the weakest part on the SMPS. Wrong wiring, 3 phase mess ups. short circuits, falling tree branches, thunderstorm. Your SMPS is facing the Real Harsh Cruel world and the best part, they left off the Security Department to keep costs low. The critters in the box get zapped for no fault of theirs.

Front End Security for SMPS

There is one difficult way out of this, we move to a 24V DC standard within the house, it is safe and the Box outside the house faces all the Electrical Environment Variables and Unpredictability. This box that charges the battery and steps down the mains voltage can be protected well. Protection on this one unit, protects all the equipment in the Home or office. This is the Civilized way electricity should be used in Homes and Offices. Easy to integrate with Alternative energy. Factories can have all the High Voltage they want.

When a good technical collaborator is involved, quality is given due respect, the products are affordable yet robust. Some firms cut off vital circuitry (these happen in mechanical, electrical and chemical field too) to keep the product cost low. These products will work well in a Mains conditioned environment which is only affordable in some companies and never at homes.

The Security system consists of something that a Surge Protector from Belkin has. Let us see the traditional way, We need Gas Discharge Tube Lightning Arrestors. Then Varistors, Thermistors, X and Y caps and the Common Mode Choke Coils. A high voltage and high current fast acting fuse or trip circuit. Overrating of Mosfet and caps that face the high voltages. Using HV Back-to-Back zeners with fuses. Snubber Plastic HV self healing caps and Fast Switching diodes to absorb the inductive spikes.

Do it within the budget you have. SMPS should withstand 1.2KV microsecond pulses. 600V millisecond pulses and 400V for a few seconds. 300V AC for many minutes. Else let us go 24V Standard.

Other Protection devices your house or lab may needs to have. CVT - Constant Voltage Transformer, 1:1 Isolation Transformer, Servo Motorized Auto-transformer Stabilizer, Earth Leakage Circuit Breaker, HV-Relay Trip Circuit, Overload Current Relay Trip Circuit, MCB, Switched Triac or Relay, Copper Transformer Stabilizer with Layer or Layer Primary Insulation to protect against high voltage. This transformer should have earth shield, guarded terminals, primary windings should not slip layers, Vacuum Impregnated. 

May the Earth be good to you ! - Means - the earthing in your Home of Office should be excellent and do not compromise on Wiring Insulation and Switchgear. Let the wires outside have concrete gutters which are closed so that water or rodents do not get to the cables.

Read more at my Power Electronics Section