Power Converters Division

Home Power Converters Division

Switch Mode Power Converter Lab (SMPCL)

Power converters for other applications
  1. Laser Diode Drivers
  2. Power Converters for Field Mapping of Quadrupole Magnets
  3. Magnet Power Converters for CUTE-FEL Beam Line and Photocathode Gun Based LINAC for BARC
  4. Sine Wave Current Source for Study of Superconducting Materials
  5. Development of two quadrant power converter for solenoid coil in atom cooling experiment
  6. A 25 kW/ 25 kHz Induction Heating Power Converter for MOVPE System
  7. Ultra-capacitor Charger Power Converter
  8. Development of High-Voltage DC Power Converter

Laser Diode Drivers

Current-sourcing power converters for driving various laser diodes in CW, pulsed or combined mode have been developed. Different techniques have been used for the development.

Another power converter has been developed to energize a string of four laser diodes (type TH-Q1201-A1) rated to deliver a rectangular current pulse of 0-80 A, with pulse width of 50-200 ms and pulse repetition rate 1 Hz to 1 kHz. It's a two-stage power converter of which the first stage is a two switch DC-DC forward converter switching at 100 kHz. In the second stage, a high-current MOSFET is used in linear mode. A 125 A/10 V CW/pulsed laser diode driver also follows this scheme.

A versatile laser diode driver power converter has been developed with varied operational requirements. The peculiarities of specifications are: wide range variation in pulse width (500 ns to CW), frequency (single-shot to 1 kHz) and output current (10 mA to 5 A). Moreover, it should also be possible to bias the pulse current to the diode by a DC current. High frequency switch-mode circuits are not used to develop the current sources since requirements of fast transient response and wide setting range of output current conflict. Instead, MOSFET operating in linear mode is used. However, a two-switch forward converter operating at 100 kHz is used at the front-end for AC-DC step-down conversion with output voltage regulation and input power-factor-correction. A microprocessor controlled front panel and RS232 interface provides individual control of each parameter while the backlit LCD display provides visual confirmation of operating parameters.

10V/80A pulsed laser diode driver
20V/5A pulsed/CW laser diode driver
10V/80A pulsed laser diode driver


20V/5A pulsed/CW laser diode driver


10V/125A pulsed/CW laser diode driver
10V/125A pulsed/CW laser diode driver


A 40 A, 2.5 V dc current controlled power converter has been developed for laser diode for laser marking system. The salient features of power converter are: small size, light weight, low cost, simple configuration, high reliability and ruggedness. It is based on two switch forward converter topology operating at 100 kHz. Design, fabrication, testing and qualification of the power converter have been completed. The power converter has been successfully integrated and tested with the laser marker system.

80A/6V laser diode power converter board
its integration in the laser marker system.
Photograph showing (a) the laser diode power converter board, and (b) its integration in the laser marker system.


Recently, an 80 A, 6 V dc current controlled power converter has also been developed for energizing laser diode for laser marking system. The scheme used is 2L-ISIPO (Interleaved Series Input Parallel Output Two Switch Forward Converter). The salient features of these power converters are: small size, light weight, low cost, simple configuration, high reliability and ruggedness. The power converter is developed using interleaved series input parallel output forward converter topology using MOSFETs operating at 100 kHz.

Photograph showing (a) 80A/6V laser diode power converter board, and (b) its integration in the laser marker system
Photograph showing (a) 80A/6V laser diode power converter board, and (b) its integration in the laser marker system
Photograph showing (a) 80A/6V laser diode power converter board, and (b) its integration in the laser marker system.


Power Converters for Field Mapping of Quadrupole Magnets

Two power converters have been developed for the field mapping of Indus-2 quadrupole magnets. Two mapping power converters, rated 170 A, 60 V, 50 ppm stability were needed for testing of quadrupole magnets, one was developed using a transistorized series pass scheme with a SCR bridge pre-regulator and the other using a high frequency resonant converter.

Transistor series pass type mapping converter
Transistor series pass type mapping converter

Resonant converter type mapping converter
Resonant converter type mapping converter


In addition to this, a high stability current-controlled dc power converter has also been developed to characterize the field quality of electromagnets. The power converter, which operates on 415 V - 50 Hz three-phase ac mains, is rated for 300 A, 60 V output with ± 20 ppm stability of the output current including ripple, regulation and drift. The power converter is based on full-bridge zero-voltage-switching (FBZVS) converter operating with phase-shifted pulse-width-modulation (PSPWM) at 25 kHz.

Photograph of  PSPWM based power converter
Photograph of PSPWM based power converter


Modular Magnet Power Converters for CUTE-FEL Beam Line and Photocathode Gun Based LINAC

DC current-controlled power converters are developed for application in CUTE-FEL beamline at BP&FEL Lab, RRCAT and photocathode gun based linac being set up at Radiation and Photochemistry Division, BARC. In all, 29 power converters for various magnets are developed. Power converter design is standardized for output ratings up to 20 A and 325 W on a standard 6U card with full-function feedback control and local-remote operation interface electronics on the same card. The power converter is an off-line SMPS circuit using two-switch forward converter, which is chosen in the reported application for its simple configuration, ruggedness, high efficiency and compact size. The specifications of magnet load and the power converter are summarized in the following table. Required output current stability is ±1000 ppm for all the converters. Although, terminal specifications are different for all magnets, required power converters are grouped into three ranges, namely, 12 A/3 V, 12 A/5 V and 12 A/26 V. Individual power converter cards can be configured for series-parallel operation to increase output power rating.

Power Converters for Photo-Cathode-Gun Based Linac for Chemistry Group in BARC rated for 12 A, 25 V (max), ± 500 ppm, 9 nos., based on similar standardized 6U design using two switch forward converter, have been developed.

Magnet

Power Converter

Qty

A

V

Big QP

12

5

2

SC Big QP

12

3

8

Small QP

12

5

5

SC Small QP

12

3

5

Separate SC

12

3

8

EA Magnet

12

26

1

QP: Quadrupole magnet; SC: Steering coil; EA: Energy analyzer


Photographs of power converter card and rack
Photographs of power converter card and rack


Sine Wave Current Source for Study of Superconducting Materials

A variable frequency ac current source is required to generate an alternating magnetic field of about 1 to 2 Oersted to study the response of various magnetic and superconducting materials at various frequencies. The current source is rated to provide the load a constant sinusoidal current at the output with the peak current and voltage ratings of 100 mA, 63 V respectively and frequency ranging from 1 Hz to 100 kHz. It is based on improved Howland current source and is developed using APEX PA 85 power operational amplifier. The current source can be operated with local as well as remote reference source with 1 V of peak reference voltage corresponding to peak output current of 100 mA.

Photograph showing the developed current source
Photograph showing the developed current source


Development of two quadrant power converter for solenoid coil in atom cooling experiment

A 50 A, ±226 V current regulated bipolar power converter has been developed at SMPCL, PCD, RRCAT to energize the solenoid coil in atom cooling experiment. It is based on two quadrant switch mode converter topology operating at 25 kHz. Specialty of this converter lies in its ability to generate fast rising and falling current patterns at inductive load in the output with rise and fall times of the order of 1 ms each. This is achieved by incorporating a feed forward loop in the control circuit along with the feedback control scheme. The feed forward loop is designed so that it operates only during rising and falling durations of the output currents by responding to a calibrated remote reference. Various protection features like over current, over voltage, over temperature, IGBT faults and MPCB interlock have been incorporated in design to trip the converter in case of faults.

Photograph showing the developed current source
Photograph of power converter front panel


Development of two quadrant power converter for solenoid coil in atom cooling experiment

A 25 kW/ 25 kHz power converter for MOVPE system in SSLD, RRCAT has been developed based on a novel high-frequency LCL-T resonant inverter. It is required to heat graphite susceptor to 1200 °C. The scheme offers many advantages over conventional series resonant and parallel resonant scheme. The converter offers high current gain, which in turn reduces the current rating of the secondary winding of matching transformer and the feeder to coil. Coil current is constant irrespective of changes in effective load resistance due to temperature or work-piece change. Transformer design is further simplified since its turns ratio is no longer dependent of the Q of the resonant network.

Two-stage conversion strategy is adopted for the development of the induction heating power converter. The first stage is a dc-dc buck converter with lossless turn-on and turn-off snubbers and the second stage is the free-running LCL-T resonant inverter. Phase-locked-loop is implemented to track the resonant frequency. The power converter is housed in standard 24 U rack. The following figures show photographs of the power converter, which has been tested in the lab to heat graphite susceptor in air to 1200 °C.

Photograph of the power converter tested to heat graphite suseptor to 1200 °C
Photograph of the power converter tested to heat graphite suseptor to 1200 °C


Photograph of the graphite susceptor inside the induction heating coil heated to 1200 &degC
Photograph of the graphite susceptor inside the induction heating coil heated to 1200 °C


Ultra-capacitor Charger Power Converter

A compact, scalable, standard 4U card sized constant-current Ultra Capacitor Charger (UCC) using high frequency, soft-switching resonant converter has been developed. Ultracapacitors, also known as Supercapacitors, offer many advantages over batteries such as large number of charge-discharge cycles, low ESR, high efficiency, high power density and low heating. Therefore, ultracapacitors are being increasingly used in portable electrical and electronic devices and transportation in conjunction with batteries. It is hoped that in near future, automotive industry will deploy ultracapacitors as a replacement for batteries. Another advantage of ultracapacitor is its ability of being charged quickly.

The power converter is an inherent current source with passive output voltage clamping capable of direct parallel operation (to increase output current) without any current sharing control. Required control and interface is simple and therefore rugged for industrial application. The developed charger has been designed for ± 48 V DC input, 10 A output current, 15 V maximum charging voltage and tested with 58 F ultracapacitor. The same card can easily be re-configured for other specific application requirements.

Photograph of ultra-capacitor charger
Photograph of ultra-capacitor charger
Photograph of ultra-capacitor charger


Development of High-Voltage DC Power Converter

A crowbar-less high voltage DC power converter of 20 kV / 1 A output rating has been developed using LCL-T resonant converter, which exhibits constant-voltage to constant-current conversion characteristics, which in turn is advantageous for phase-shifted parallel operation of modules without any need for current equalization feedback control and safe operation under arcing and partial discharges. The power converter is designed to be a three-phase LCL-T resonant converter which is free-running at constant (resonant) frequency. The output is controlled by controlling the input dc voltage of the resonant converter using another front-end DC-DC converter. The power converter has been tested to 20 kV successfully and under simulated arcing conditions. The performance is in conformance with the analytical predictions.

Photographs of the high voltage power converter
Photographs of the high voltage power converter
Photographs of the high voltage power converter

Best viewed in 1024x768 resolution