If you ask a designer why he has chosen a stepping driver and the motor associated for a given application, chances are that the answer will be something about “high precision of movement with high torque at low speeds for a low price “ or “open loop positioning”.
A BLDC motor has high torque at lower speeds but needs to be associated with a speed reducer. The stepping motor solution has the advantage to provide high torque performances at low speed and also an accurate positioning without expensive position sensors, speed reducer (direct drive) and feedback loops.
Furthermore, a speed reducer can be noisy and decreases the motor movement accuracy.
In addition, the holding torque of a stepper motor at low-speed is much more important than the torque of a BLDC in most of the cases. Due to their construction (windings), the motors can have a high torque and withstand a strong current. In return, the EMF is much more important: reaching very high speeds with a stepper is difficult. One can consider that a stepper motor is comparable to a BLDC with the advantages of integrated electromagnetic reducer but without the disadvantages!
Why a Micro Stepping Motor ?
Stepper motors are incremental motion machines, and as such they tend to be noisy and are prone to behave erratically under certain conditions. This is the case when the stepping rate enters in resonance mode with a mechanical or electro-mechanical system. Although the angular increments are small, the positioning resolution is restricted to a determined number of discrete points.
Our micro stepping control technology associated to hybrid stepper motor has a well-balanced current control and very low harmonic distortion. The resulting waveforms are hardly distinguishable from true sine or cosine signals up to 50 increments for an electrical angle of n/2 radians.
Our first generation of micro stepping SIMPA, Microsimpa, MI452, and MI907operates in open loops and meets these characteristics.
Moreover, the hybrid stepper motor technology NEXEYA uses, is characterized by its particular design including: - A significant number of pairs of poles with 200 defined mechanical positions offering an exceptional angular rigidity, - A precision of 10.000 positions per revolution thanks to an internal position interpolation, - A motor torque which is held in a stationary position, - A rustic construction well adapted to harsh condition.
Why an amplifier associated to stepping and micro stepping controllers ?
Micro stepping amplifiers offer the guarantee to have a safe, smooth and quiet movement at the right power. Our amplifiers MI45x and MI90x Series are perfectly adapted to drive any bipolar stepper motor in association with most of standard axes controllers.
Why associate the Self-commutated operation mode to a micro stepping operation motor ?
In control operation mode, each micro step precision depends on the incremental encoder used.Errors in the current orienting can occur for high numbers of micro steps.
In order to avoid losing micro steps, NEXEYA associate a self- commutated operation mode to its micro stepping solutions DMAC and BMAC.
This solution has the advantage of allowing a continued control feedback loop for the position, the speed and the torque every 20 µs without any compensation (Even after a power failure). The motor becomes a high dynamic servo drive, insensitive to the load parameters variations and external disturbance.
3-AXIS CNC DMAC® DRILLING SOLUTION
- Enhanced muti-axis interpolation. - PC software tools with G-code interpreter. - Smart sequencer for PLC-like functions. - High torque stepper motors with patented Autocommutation ( Self-commutated operation mode )