Monday, November 2, 2009

Electronic Ballast Schematic Simulated

Electronic Ballast Output and Drive Waveforms (Torroid).

Electronic Ballast Output and Drive Waveforms (Torroid).

Electronic Ballast Output Waveforms

First is half bridge output and following is waveform across tube.






DC AC CFL Inverter Schematics

Battery powdred CFL Inverters are widly used in solar lighting emergency lighting and automobile lighting. The schematics we are working out is a popular DC AC inverter widly used in general battery powdered applications as well as used in Electronics Ballast where Line Voltage is Less(110V AC as in US). This basicaly push pull current fed parallel resonant self oscilating inverter. The inductor L1,L2 and reflected impedance of C1 forms LC tank circuit.
L4 will source current while giving maximum impedance to higher harmonics. R2, L5, L6 provides base drive. You can note primary rms voltage is 1.1 times of battery voltage because L4 act as boost inductor. Both switches are working in ZVS. Out put is pure sine wave. Load power dissipation is 9W. But Tank circulating power is arround 80W.

DC AC CFL Inverter Output Waveform

DC AC CFL Inverter Input Waveform 2

DC AC CFL Inverter Input Waveform 1

Sunday, August 23, 2009

Three phase six pulse converter

Three Phase Six Pulse Converter Controll Circuit

Circuit diagram of three phase six pulse converter with current and voltage feedback is given above. Out put stage is capable of driving 250 amps 1800V SCR. If we reduce gate series resistor to 22 ohm we can drive 800 amps SCR. This converter is well suited for power level upto 250 KW

Tripple Conversion UPS Charger

Charger Circuit

Tripple Conversion UPS Output Filter

Output RFI Filter

Tripple Conversion UPS Bias Supply

Bias Power Supply

Tripple Conversion UPS Controll Circuit

Cntroll Circuit

Tripple Conversion UPS Power Circuit

Power Circuit

Friday, June 12, 2009

Electronic Earth Leakage Circuit Breaker

Differential CT is used to sense earth leakage current. Out put current of Differiantial CT will be difference of Phase current and Neutral current divided by turns ratio. This current is fed to current to voltage converter. One variable resistor is provided in the fee back path to audjest sensitivity. This signal is full wave rectified and given to relay driving circuit with a small delay.

SCR is used as relay drive for latched operation. Push to on switch is used for resetting the circuit. Test switch is used to check the working of the circuit by creating a artificial leackage current of 20mA. Another good referance design from Fairchild Semiconductor

Sunday, June 7, 2009

Electronic Transformer

Matix converter can be used with a high frequency ac link to make low frequency transformer.

The circuit presented here uses MOSFET as switches and EE70 ferrite core transformer as AC link. Transformation ratio is directly prepotional to turns ratio of EE70. If EE 70 have 1:1 turns ratio the curcuit will act as 1:1 isolation transformer. The main adventage of this topology is its low frequency response. We can use this electronics transformer DC to 200Hz.




Saturday, June 6, 2009

Multi Level Inverter

Multi Level Inverters are used to produce fine pwm wave forms with muliple voltage steps. It uses one or more power sources and multiple power switches. Main adventage of multilevel inverter is low switching component at output which will reduce the output filter components.
Multilevel inverters have very low switching loss but conduction losses are high. Another adventage is reduced voltage requirment of switching devices. The circuit given below is a three level inverter.The power supply is + - 400V connected as dual polarity bus ie 800V. Four 600V IGBT switches are connected in series and center point is taken as output. The levels are defined by shifting triangle wave above and belo GND (0V). 6V amplitude 50 hz sinewave is the input signal which is reproduced as 385V at output.Out put pwm have three levels 0V +400V and

Circuit of Multi Level Inverter

Input Sine Wave and level shifted Triangle Wave

PWM gate waveforms

PWM Out Put and Final Out Put

Have nice day

Friday, March 27, 2009

Regenerative Loading of Inverters

This is the popular loading method for high power inverters. The inverter is configured as current mode inverter and referance sine wave is generated from utility.The referance amlitude is audjested for variying load.If we load 100KVA online ups full load we need only the power loss which will happen in UPS.Ie if efficiency of ups is 95% we need only 5KW from line to load full 100KW.

Sunday, March 8, 2009

Unipolar PWM

Uni Polar PWM

Basic circuit of unipolar sinewave PWM

sine wave referance triangle wave and PWM waveforms

sine triangle and output

Bipolar PWM

Following is the basic circuit of bipolar PWM and its waveforms
circuit diagram

Waveforms of this circuit

triangle wave sine wave and PWM output

PWM and Output
Sinewave triangle wave and output

Saturday, March 7, 2009

90V to 500V AC SMPS

here is the circuit of 90V to 500V ac input power supply with battery backup.

Or u can call dc UPS

Monday, February 9, 2009

Sunday, February 8, 2009

Active Power Factor Correction

Useful links on Active Power Factor Correction
Power Factor Correction Handbook
UC3854 Controlled Power Factor Correction Circuit Design
Optimizing Performance in UC3854 Power Factor Correction Applications
UC3854A and UC3854B Advanced Power Factor Correction Control ICs (Rev. A)
Improved Power MOSFETS Boost Efficiency IN A 3.5kw Single Phase PFC
Optimizing the Design of 3.5kw Single-MOSFET Power Factor Correctors

Solid State Servo Buck

Block Diagram of AC Static PWM Buck Automatic Voltage Regulator

Solid State Servo Boost

Block diagram of Static PWM boost servo stabilizer

Battery Powered CFL Inverter Flyback

Circuit of popular Battery powered CFL inverter using flyback out put stage.
It is the lowest component count and coast but will fail at no load (tube disconnected).

Thursday, February 5, 2009

DC AC CFL Inverter Push Pull

Parallel resonant current fed push pull inverter for battery powered lighting applications. It uses capacitor C3 for preheating and electrostatic shield for tube starting.


DC AC CFL Inverter with preheating

Parallel resonant current fed push pull inverter with preheated staring with out the help of electrostatic shield for battery powered lighting applications.No load protection is also  provided.

Wednesday, January 28, 2009

AC voltage sensing circuit

This circuit is used to sense ac line voltage with out using transformer and gives very low leackage current while circuit ground can be connected any potential.test