Meaning of 甜-Z (Z is the upper-case English letter) This is apparently a jargon engineering term for something to do with frequency (Hz). 

I'm guessing it might be something to do with resonance ("sweet spot"?) but I've not run into it, and neither have the two native Mandarin-speaking engineers I've asked.
甜Z is likely the result of imperfect OCR (optical character recognition) for "5Hz". The machine probably sees "5H" as "甜".

It's usually seen in Google's OCR for Chinese patents. If you need to search for original patent text for clarification, you can go to  http://epub.sipo.gov.cn/gjcx.jsp and search the title.