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What causes an inrush current in a rectifier?
Rectifiers and ac-dc power supplies employ large bulk capacitors. During power-up, these capacitors require a large amount of current to charge up, resulting in a large inrush current. This inrush current creates limitations in the operation of power devices and interference of those devices with the power line and circuit breakers.
Why does the rectified voltage drop after a load?
Rectified voltage slightly drops after the load is connected due to the limited output power of the isolation transformer used during the test. The blue line depicts line current and the red line depicts the load voltage. The system is verified to provide 2.5-A output current at full load at normal operation.
How is the inrush transient current mitigated in a circuit?
Another method used to suppress the inrush transient current is to trigger the system at a phase angle that is different from the supply voltage source. The concept behind this technique is to trigger the circuit at the specific phase at which the transient response of the circuit would be minimized.
How does the inrush current affect the power system?
This inrush current creates limitations in the operation of power devices and interference of those devices with the power line and circuit breakers. It also affects the reliability of the power system due to overstress caused by instantaneous but huge surge in initial current at power up.
How does an inrush current control device work?
However, thanks to a unique control algorithm, an innovative inrush-current control device helps mitigate the ensuing problems. Rectifiers and ac-dc power supplies employ large bulk capacitors.
How does a capacitor affect the inrush current?
Capacitor C is charged N cycles to the voltage value proportional to the input-line voltage. Another variable to control inrush current is LC time constant. Capacitor C value depends on desired ripple value. After selecting the capacitor C value, the designer can decrease peak inrush current by increasing inductance L.
What’s the highest possible inrush current in a circuit?
A circuit that normally draws 1A from the mains may easily draw 50 to 100 times that when power is applied, depending on the supply voltage, wiring and other factors. With AC powered equipment, the highest possible inrush current also depends on the exact time the load is switched on.
How is inrush current limiting used in switching power supply?
Application: Inrush current limiting in a switching power supply Various switch-mode power supplies (SMPS) – which are small, lightweight, and high-performance – are often used as power supplies of electronic devices. At the time of powering on an SMPS, the device is charged with an inrush current with a high peak to charge a smoothing capacitor.
What happens if the inrush current is too big?
If the inrush current is too large (where the power supply sunk too much energy in a short period of time), components in the power supply, such as fuse and rectifier diodes, might be damaged.
Which is the best circuit to limit inrush?
The three types of inrush-limiting circuits designers use most are a negative temperature coefficient (NTC) thermistor, a relay, and a MOSFET bypass circuit. NTC thermistor An effective way to cut down the inrush current is to increase the resistance on the capacitor-charging path – inserting a resistor like that shown in Figure 3.