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Quality inverters incorporate either an AC Reactor or DC Reactor (choke). Their inclusion in the basic design of the inverter allows the design engineer to maximize the advantages of the choke. Their function is to reduce the current distortion caused by the input stage rectifiers by slowing the rate of change of current, and thus charging the internal capacitor at a slower rate over a longer time.
Some inverters allow aftermarket fitment of DC chokes but access to the DC bus is required. While it is easy to add AC chokes to the input stage, there is a disadvantage of voltage drop to the inverter that may have to be considered.
The Harmonic Distortion caused by an inverter is related to its size & load, choke size, and the supply network parameters.
With no AC Reactor or DC Choke, the harmonic distortion will be greater.
Some inverters allow aftermarket fitment of DC chokes but access to the DC bus is required. While it is easy to add AC chokes to the input stage, there is a disadvantage of voltage drop to the inverter that may have to be considered.
The Harmonic Distortion caused by an inverter is related to its size & load, choke size, and the supply network parameters.
With no AC Reactor or DC Choke, the harmonic distortion will be greater.
Tags: inverter, Accessories
From a manufacturing economics standpoint, there is often a trade off in the decision to add a DC bus choke or not based on its ability to reduce the DC bus ripple. This is because it can reduce the DC bus capacitance necessary to present a clean DC source to the transistors. For some frequency inverter manufacturers who have the internal capability to wind their own component chokes, this often represents a component cost benefit compared to buying capacitors from outside vendors and being more subject to market volatility. On the other hand if the inverter manufacturer IS also a manufacturer of capacitors, it works exactly the other way around.
I believe this is why we often see small component class drives being made without DC chokes primarily by companies, mostly in Asia, for whom capacitors are a very low cost commodity. When EU and US manufacturer make larger inverters, it's usually less expensive for them to wind chokes, but that option is often perceived to be too physically large for component class drives so they farm out their designs and production to Asian manufacturers. Ironically then, users will add an external AC reactor anyway, but fail to observe that the overall footprint is now larger than it would have been with a DC choke.
I believe this is why we often see small component class drives being made without DC chokes primarily by companies, mostly in Asia, for whom capacitors are a very low cost commodity. When EU and US manufacturer make larger inverters, it's usually less expensive for them to wind chokes, but that option is often perceived to be too physically large for component class drives so they farm out their designs and production to Asian manufacturers. Ironically then, users will add an external AC reactor anyway, but fail to observe that the overall footprint is now larger than it would have been with a DC choke.