Variable pulse width systems, sometimes called electronic pulse forming networks, are fairly flexible. They can accommodate a variety of lamps and operating conditions. The system has to be designed to sustain the maximum anticipated operating conditions driving both cost and size.
Key design elements include:
Average power/Charging rate
Lamp simmer power requirement
The values can be calculated by knowing the details of the maximum operating conditions:
Energy to the lamp per pulse
Pulse width range
Maximum Repetition rate and/or duty cycle
One critical operating point is maximum energy at the minimum pulse width. This along with the impedance of the lamp allows the calculation of the maximum voltage needed across the energy storage capacitors.
It is important not to over spec the operating voltage for long pulse width systems. The amount of capacitance in a fixed volume is related to the voltage rating of the capacitor. We use 77 mm diameter, 130 mm tall capacitors in our systems. In this package a 250 V cap has 15,000 µF of capacitance, a 550 V cap has a capacitance of 4,300 µF.
Fixed pulse width systems are designed for a specific lamp. A variable pulse width system can accommodate lamps with a variety of K0 or impedance value.
Unlike a SCR switched fixed PFN where the energy is forced through the lamp, an IGBT switched system turns on and off the flow of energy. The peak current and pulse rise time are determined by the voltage across the capacitor bank and the impedance of the lamp. The lamp impedance typically will be specified by the lamp manufacture; it can also be calculated from the lamp geometry:
Independent of the K0 the arc length and fill pressure of the lamp determine how much power is required to simmer the lamp. AMI offers 28 W and 60 W flashlamp simmer supplies.
Please contact AMI to discuss your application or if you have any questions. For More Information:
Catalog page: AMI’s Pulsed Flashlamp Controllers
Blog Post: FLASH LAMP CONTROLLER FOR SOLID STATE LASERS