Switching Power Supply

How to do inrush current testing with a small AC source?
Switching power supply, one of the most common types of rectified loads, uses the power conversion technology to turn switching transistor on and off rapidly to provide regulated voltage. Examples are personal computer chargers, cell phone adaptor and uninterruptible power supply (UPS), which employ pulse-width modulation (PWM) controller ICs and MOSFET. With the continuous improvement and innovation in technology, switching power supplies have been widely applied in multiple industries due to its compact and lightweight characteristics and high efficiency. It is one of the key components that contributing to the rapid development of modern electronic industry.
When powering up a switching power supply or a rectified load, an instantaneous high input current will be drawn to charge the capacitors. This turn-on inrush current can be as high as several times or over 10 times the steady state current. If the turn-on angle of input voltage is 90 or 270 degree, the inrush current will start at its peak value. To power up the switch mode power supply during development, verification or production stage, a programmable AC power source with a high output current becomes essential. This leads users to select an AC source with much higher output power than switching power supply’s rated power, and it increases the costs of experiments and productions. Sometimes these high power AC sources also require larger footprint.

Preen’s AFV-P series, high performance programmable AC power source, provides standard inrush current capability up to 4.5 times of output rated current (Irms) and optional 9 times inrush capability, which makes the AFV-P series the industry-leading AC source that delivers the highest peak current with the smallest output power. It is an ideal AC power source for high inrush current drawn by the switching power supplies and helps users to effectively save the cost and space. Moreover, the users can set the start and end angle with the AFV-P series to simulate the maximum peak current (Ipeak) at the initial power-on stage to ensure product reliability at different input conditions.
Using AFV-P-1250 model as an example, the graph below is the turn-on waveform of a switching power supply with start angle at 90 degrees.
  Features of AFV-P Series
  • 2U/4U
    Compact Sizes 2U : 600VA / 1250VA / 2500VA 4U : 5000VA
  • 4.5 times
    High Inrush Current  Ideal for inrush current: capable to deliver up to 4.5 times of peak current
  • ≦0.3%
    Low THD Total Harmonic Distortion is only under 0.3 % when output power is under 100 Hz
  • AC&DC Output
    AC source with DC output One machine with AC Output and DC Output to extend more applications
  • 0-310V
    Wide Output Wide output Voltage and Frequency ranges.
  • ≦300uS
    High Slew Rate  The slew rate less than 300 µs from 0~90% output voltage

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