Selecting and Applying DC Link Bus Capacitors for Inverter
Capacitors cannot pass DC current; thus, DC current only flows from the source to the inverter, bypassing the capacitor.
Of course, capacitors cannot pass dc current; thus, dc current only flows from the source to the inverter, bypassing the capacitor. Power factor correction (PFC) in the converter and/or regenerative energy flow in certain inverter topologies can complicate matters.
Consider the following hypothesis about the current drawn by the inverter from the capacitor: For a given ac RMS value and pulse duty, the dielectric loss component of the dc link capacitor is a strong function of the inverter switching frequency and current pulse spacing, but not of the exact pulse shape.
Like batteries, inverter capacitors also have two electrodes. Inside the capacitor, the two electrodes are connected to two metal plates separated by a dielectric. The dielectric can be air, paper, plastic, or any other substance that does not conduct electricity and prevents the two metal poles from coming into contact with each other.
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.
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