What is the role of a DC link capacitor in inverter systems?

Before diving into the calculations, it is important to understand the role of a DC link capacitor in inverter systems. The primary function of a DC link capacitor is to smooth out the DC bus voltage between the rectifier and inverter stages, which helps in reducing voltage ripple and preventing voltage spikes.

What is a DC link?

A DC link is a connection which connects a rectifier and an inverter. These links are found in converter circuits and in VFD circuits. The AC supply of a specific frequency is converted into DC. This DC, in turn, is converted into AC voltage. The DC link is the connection between these two circuits.

What is a DC link circuit?

DC Link is a connection between a rectifier and an inverter. It acts as energy storage device between two stages. DC Link circuits are found in converter circuits or variable frequency drives (VFD).

What is a DC link capacitor?

The AC supply of a specific frequency is converted into DC. This DC, in turn, is converted into AC voltage. The DC link is the connection between these two circuits. The DC link usually has a capacitor known as the DC link Capacitor. This capacitor is connected in parallel between the positive and the negative conductors.

Why does a DC link capacitor have a ripple current ICAP?

We may infer from Figure 2 that the DC link capacitor’s AC ripple current Icap arises from two main contributors: (1) the incoming current from the energy source and (2) the current drawn by the inverter. Capacitors cannot pass DC current; thus, DC current only flows from the source to the inverter, bypassing the capacitor.

How do I choose the right capacitor for my inverter?

In practice, selecting the right capacitor for your inverter involves more than just calculating the required capacitance. Other factors to consider include: - Voltage Rating: The capacitor must have a voltage rating higher than the DC link voltage to prevent breakdown.