What is the difference between holding and detent torque?

What is the difference between holding and detent torque?

Holding torque is typically higher than running torque, and is limited primarily by the maximum current the motor can withstand. From a practical standpoint, holding torque is the sum of the magnetic force exerted by the coils to hold the motor’s current position, plus the detent torque.

What causes detent torque?

It is also known as Restraining torque and is produced in the rotor of the permanent magnet motor. The detent torque exists because of the residual magnetism in the Permanent magnetic material used for the construction of the rotor of the motor. It is produced when the stator coils are not energised.

Does microstepping increase torque?

There is no loss of torque by increasing the microstepping. Period. So crank up the microstepping and enjoy the smoother ride! If you find your maximum velocity is now lower than you require, then either reduce the microstepping or get a better stepper controller board which can handle the higher frequency requirement.

What is holding torque of motor?

If external force is applied to a stepping motor when it is stopped but energized, the attractive force generated between the rotor and stator works to maintain the stop position of the motor. This torque of withstanding the external force is called the holding torque.

What is the effect of cogging torque?

Cogging torque is an undesirable component for the operation of such a motor. It is especially prominent at lower speeds, with the symptom of jerkiness. Cogging torque results in torque as well as speed ripple; however, at high speed the motor moment of inertia filters out the effect of cogging torque.

Do servos have holding torque?

Unlike stepper motors, they do not have holding torque per se. The combination of speed and torque enables servo motors to deliver better acceleration than stepper motors. They also deliver improved positioning accuracy as a result of closed-loop operation.

Can DC motor hold torque?

Normal DC motors and servo motors do not have much torque at low speeds. Suitable for applications with high holding torque. Stepper motors can be easily controlled with microcontrollers such as the ATmega chips that are readily available on Arduino development boards.

Does microstepping reduce holding torque?

In any case, it wreaks havoc with overall accuracy. Some manufacturers fabricate microstepping versions of their motors. Their aim typically is to reduce the detent torque, usually at the expense of holding torque, so the torque-versus-rotor position is closer to a sine wave.

Why does detent torque have to be overcome?

Because detent torque has to be overcome before the motor will move, it reduces the ideal torque the motor can produce when it’s running. The amount of power the motor needs to produce to overcome the detent torque is proportional to the motor’s speed.

How is detent torque measured in a DC motor?

One involves cogging torque measurement of a DC motor structure of various schemes, and the other entails advanced rotor design for decreasing the detent torque in a three-phase hybrid stepping motor. A. Cogging-torque Tester Our cogging/detent tester has the configuration shown in Fig. 3.

How much detent torque does a permanent magnet have?

It usually averages between 5 to 20% of the holding torque. In two stepper motors, the permanent magnet and the hybrid, both produce detent torque, but the variable reluctance stepper motor does not. This is because of the difference in design between the variable reluctance motor and the permanent magnet and hybrid motors.

Why is detent torque used in a wristwatch?

In the stepping motor used in a wristwatch, the no-current torque is used for ‘detenting’ or holding the arm at a fixed position, which is why it is traditionally called the detent torque. In most conventional and brushless DC servomotors, however, this sort of torque is undesirable since it causes speed ripples or cogging motions.