# higher voltage > means better torque? in stepper motors

#### whescker

Joined Jul 13, 2022
2
Hi, I'm working with stepper motors and I have a question. I have found that if I use a higher voltage switching source, I get better torques from the motor. why is this?

#### BobTPH

Joined Jun 5, 2013
8,137
Higher voltage means higher current means more magnetic attraction means more torque.

When stepping quickly, the coil inductance can keep the current from getting anywhere near the DC current. A stepper driver will use a higher voltage and monitor the current to keep it at the rated current.

#### Papabravo

Joined Feb 24, 2006
20,621
Hi, I'm working with stepper motors and I have a question. I have found that if I use a higher voltage switching source, I get better torques from the motor. why is this?
Not necessarily. It does mean faster current rise time. There is an inverse relationship between speed and torque. The faster you try to make one move the less torque you are getting. There are also a pair of resonances that you must avoid. The lower frequency one is a mechanical one, and occurs at about 200 Hz. give or take. The higher frequency one is an electrical one and occurs at about 5kHz give or take. This is the one where the torque essentially drops to zero or so close to zero as to not be worth mentioning.

Last edited:

Joined Jul 18, 2013
28,066
When using steppers, they should be operating at the Exact plate current throughout the rpm range in order to maintain torque.
Not higher or lower.
Modern drives use a much higher drive voltage in order to maintain this current as the inductive effect changes with RPM.

#### Papabravo

Joined Feb 24, 2006
20,621
When using steppers, they should be operating at the Exact plate current throughout the rpm range in order to maintain torque.
Not higher or lower.
Modern drives use a much higher drive voltage in order to maintain this current as the inductive effect changes with RPM.
Subject of course to the proviso that the current is not required to rise instantaneously from 0 to the plate current but follows the actual L/R time constant of the circuit.