In the second example, I understand that there is no need to set off with commas the adverb “generally,” but what about “in general” in the first example? I know that both “generally” and “in general” mean the same, but I am tempted to set off “in general” with commas.
I hope that somebody can help me clarify this matter. Thanks in advance!
Sadly, I am not an expert in comma usage. I think you have to separate generally or in general with a comma when it is placed at the beginning of a sentence.
Generally, the core controller torque is written as Q = Qi + Qc.
In general, the core controller torque is written as Q = Qi + Qc.
When an introductory adverbial element seems to modify the entire sentence and not just the verb or some single element in the rest of the sentence, put a comma after it.
Fortunately, no one in the bridal party was in that car.
Sadly, the old church was completely destroyed.
On the other hand, someone obviously was badly injured.
grammar.ccc.commnet.edu/grammar/commas_intro.htm
Thank you, Milanya. I understand what you mean. But I am still confused on how to deal with my given examples. I hope that somebody can shed light on this. Thanks once again. 
Could we use “in general” in the middle of the sentence? Or we always place it at the beginning?
Yes, we could.