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Step Motors FAQs

What is the difference between Unipolar and Bipolar motors?

A traditional unipolar wound motor has six lead wires. Each winding has a center tap. Unipolar wound motors are typically used in applications requiring high speed and high torque. A traditional bipolar wound motor has four lead wires. There is no center tap in each winding. Bipolar wound motors are typically used in applications required high torque at low speeds.

What is the difference between a closed loop stepper motor controller and an open loop stepper motor controller?

In an open loop stepper motor controller, there is no feedback going from the motor to the controller, so the controller cannot make any necessary adjustments. This type of controller is effective when the motor is bearing a constant load at a consistent speed, in which case few if any adjustments will ever be necessary. In applications with a variable load or speed, a closed loop motor controller, where feedback is sent back to the controller for adjustments, may be preferable. When an open loop controller is suitable, it is often preferable, in part because of its low cost and lack of complexity.

Can I run a traditional six leaded motor as a bipolar winding configuration (four lead wires)?

Yes. A six lead wire motor is able to run in a unipolar or bipolar winding configuration. You will see similar torque and speed output from traditional a six lead wire motor run in a bipolar wound configuration as you would see from running a four lead wire motor.

My stepper motor is running hot to the touch. Is there something wrong?

Stepper motors are designed to run hot. Our Hybrid stepper motors are rated to run in an ambient temperature range of 20 degrees C to 50 degrees C and can have a temperature rise of 80 degrees C. It is common for stepper motors to run hot because they are often driven at a constant current.

When should I use microstepping?

Typically microstepping is used in applications requiring the motor to operate at less than 700 PPS. At low pulse rates, stepper motors to less smooth and often vibrate.

How much torque safety margin should I use when sizing a stepper motor?

We recommend using a torque safety margin of 2 when sizing a stepper motor.

Brushless DC Motors FAQ

What is a brushless motor?

A Brushless DC (BLDC) motor is a rotating electric machine where the stator is a classic three-phase stator like that of an induction motor and the rotor has surface-mounted permanent magnets. In this respect, the BLDC motor is equivalent to a reversed DC commutator motor (or brush motor), in which the magnet rotates while the conductors remain stationary. In the DC commutator motor, the current polarity is altered by the commutator and brushes. On the contrary, in the Brushless DC motor, the polarity reversal is performed by power transistors switching in synchronization with the rotor position. Therefore, BLDC motors often incorporate either internal or external position sensors to sense the actual rotor position or the position can be detected without sensors. The BLDC motor is driven by rectangular voltage strokes coupled with the given rotor position. The generated stator flux interacts with the rotor flux, which is generated by a rotor magnet, defines the torque and thus speeds of the motor. The voltage strokes must be properly applied to the two phases of the three-phase winding system so that the angle between the stator flux and the rotor flux is kept close to 90° to get the maximum generated torque. Due to this fact, the motor requires electronic control for proper operation.

What are the advantages of using a brushless motor versus a brush style motor?

  • No brush noise, efficient, durable, robust, easy to cool

  • Linear current/torque

  • Synchronous speed control

  • Position and Speed Servo (open/closed loop)

  • Customizable Performance

  • Extended Life

  • How much life can I expect from a Brushless motor?

    The life expectations of a BLDC motor are dependent on the operating conditions and environment. Under “ideal” conditions, a BLDC motor-only will have minimal wear and will have a long life span. High radial and axial load will affect the life of the bearings, therefore, reducing life. For BLDC gear-motors, the gearing technology will determine life.

    How much power do I need to run the control?

    Obviously, the input power required is directly related to the output power requirement. Sizing a power supply is critical to ensure output power and wattages are achieved. As an example, our standard BLDC40SG01 motor with a 12VDC power supply, the nominal current rating is 25A for a total of 300W input. Assuming the motor is 80% efficient at this point, a minimum of 375 input watts is required to run the motor. This power level isn’t typical of all BLDC motors, but this example shows the electrical requirements for the circuit.

    How can I calculate my power needs?

    A simple formula can be used to roughly determine what is needed power-wise.

    Here’s an example:

    Motor Speed:3600 RPM
    Motor Torque:340 mNm = 48 inoz = 3 inlb
    Assumed Eff %:80 %
    Power Output:( Speed x Torque(inlb) ) / 84.5=>(3600 x 3 ) / 84.5=127 Watts Output
    Power Input:Watts Output / Assumed Eff%=>127 / 0.8=159 Watts Input (Required)
    Current Requirement:Watts Input / Voltage=>159 / 12=13.2 Amps (Minimum)

    What programmability features are there?

    Our standard product allows for custom velocity curves and current regulation. With more advanced programming, we can add braking torque, holding torque, alternate I/Os, extended temperature ranges, and stall detection. Each software request will be reviewed on an individual basis for feasibility and cost.

    Does the Brushless have any regulatory qualifications?

    None to date

    What environmental considerations are there?

    Typical environmental temps for the motor should be run in a low humidity environment with an ambient temperature range of –20 C to +50 C. BLDC motors do have IP ratings associated to them and limited customization can be done to increase the IP rating. If severe conditions require IP ratings of IP54 or higher, a customized motor construction is required to accommodate this need.

    What is the Wiring and Connection layout?

    For hall only motors, a five (5) wire connector is provided for hall effect connection and spade terminals on the rear of the motor are provided for ease of connection and current handling capability. We can vary our internal winding configuration from delta to ‘Y’ type connections depending on application needs.

    Are two power sources needed for integral control motors?

    Motors can be programmed to function with only one power source. This scheme would be a setup where on/off is the only requirement. Typically, motors that will speed regulate, will require two power sources. An input source (12 – 48 VDC) for main motor power, and a secondary source for logic and control inputs (5VDC).

  • How do I control speed and keep it constant?

    A sophisticated control system would be required to keep the speed regulated to a tight tolerance. Utilizing an encoder feedback, the customer’s control can monitor and adjust the 0-5VDC input can be controlled <1%. This will allow the closed loop speed regulation needed for tighter tolerance speed control. Current tolerance on speed regulation for standard integrated controls is <5%. Speed can be regulated over a range of torques. This is a key benefit when comparing BLDC to brush motors.

    What is the voltage range of the Brushless products?

    The integral control option for the 2.25” has a standard input voltage range of 12-48 VDC. If an external controller is used, customer’s controller will determine the voltage range of the motor. However, NMB BLDC motors do not accommodate high voltage inputs (<48VDC) due to IEC creepage and clearance requirements.

    Are there any noise benefits of a Brushless motor?

    Yes, with the elimination of brushes, BLDC motors can be regulated to slower operating speeds without sacrificing torque. Brushless motors can also utilize skewed magnets to reduce the effect of cogging.

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