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multiple speed setting for an electric vehicle? Answered

suppose an Ev had to run on different speeds say 30 miles/hr and 40 miles/h and vice versa. So how will the the current and voltage changes according to this situation.
Say you have a 400w motor and torque is known already and is calculated according to the required acceleration.

In short if you have an Ev and u want to set the ev run on different speeds what are the quantities that have to be checked or monitored (current,voltage) and .If you move from 30 to 40 miles/h what will happen to the variables?

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steveastrouk
steveastrouk

8 years ago

In a PMDC motor output speed is proportional to applied voltage. There is no need for any deep calculation.

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Nr-Think different
Nr-Think different

Answer 8 years ago

heii thanks
But what will happen if it exceeds the rated voltage of motor,IF a motor is specified as 24v 400w then 24 v is the voltage @ which it give fine performance.So I hope it's peak performance will be at that time only. By increasing the voltage in order to increase speed if it exceeds rated voltage i guess it may have consequences,and what about finding at what voltage will it reach from 30-40 miles/hr.

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steveastrouk
steveastrouk

Answer 8 years ago

That's right, a motor delivers its RATED performance, but voltage is not the only critical parameter - you HAVE to know/measure current - since power = current x voltage and mechanical power= electrical power x efficiency.

So during the design stage you need to DECIDE what the maximum speed will be, and how much power it will take, and whether that needs a gear box.

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rickharris
rickharris

8 years ago

Your best bet is to get an operating graph from the motor manufacturers.