Why you really need to use a Clipper with MPPT for Wind

When the MidNite Classic MPPT Charge Controller (CC) is used for Wind, (or any other MPPT charge controller for wind), one thing you need to watch out for is as the batteries get charged (Absorb or Float voltage regulation), or, the CC bumps up against its current limit, and the wind gets going good, (in this case, around 50 MPH), there is usually one thing that happens... The CC lets the voltage of the wind turbine rise as high as it needs to in order to keep the battery voltage from going above the set-point OR to keep the battery current below the current limit. One could short out the turbine, but at high wind speeds this can possibly harm the turbine windings because they heat up and the turbine may not come to a halt.

A clipper can PWM or semi-short the turbine after a wind gust and bring the turbine voltage down below the maximum operating voltage (in this case, 250 Volts DC), and the CC can resume operation. Note, in this video, the 24V battery has gone into Absorb (30 volts or so) and the turbine voltage went above 250 Volts and turned off to protect the Classic (the "HyperVoc" zone). What happened here, but was not caught on camera, was that the wind turbine voltage went above 250 Volts and possibly over 300 volts. What we would rather have done is for a clipper to keep the voltage from going this high, and hopefully kept it below 250V. But, unloaded, even if the available power from the turbine is not enough to current-limit or Absorb/Float voltage limit, the free-wheeling voltage can still become higher than the operating voltage and there is nothing the CC itself can do about this.
For the Absorb/Float case, and the CC is NOT current limiting, more load diversion or current required from the battery side can help to keep the turbine underneath the HyperVoc voltage zone and in the range of operation and so be kept under control by the CC.

This is where a Clipper will become necessary.

A Clipper can also keep you from waking up in the middle of the night because your wind turbine is screaming "load me !"

Category:

Science & Technology

Tags:

• mppt
• wind
• turbine
• hypervoc
• over
• voltage

[k7iq]

This one is a high voltage Bergey XL.1  The newer ones will not be quite this high of voltage but should limit themselves to something just over 250 Volts or so.

[Fearlessthinker]

There are currently no products for MPPT for wind turbines, especially for GTI applications. Will your "wind-friendly" MS CC be offered in a version that provides GTI or allows use with an off-the-shelf "cheap" GTI? I think the market is huge for this.

[helloman1976]

What wind turbine are you using that is producing 300V?