How is cogging torque calculated?
How is cogging torque calculated?
There are several possible ways of measuring the cogging torque, for example, by using (a) conventional torque transducer; (b) strain gauge bridge based on the reaction torque on the stator; (c) torque observer based on the voltage and current measurements; (d) special torque transducer for cogging torque measurement.
What is meant by cogging torque?
Cogging torque of electrical motors is the torque due to the interaction between the permanent magnets of the rotor and the stator slots of a permanent magnet machine. It is also known as detent or no-current torque. Cogging torque is an undesirable component for the operation of such a motor.
What is cogging torque in BLDC motor?
The cogging torque is undesirable effect in the brushless dc (BLDC) motor, causing vibration and audible noises. It arises from the rotor permanent magnet interacting with the steel teeth on the stator. Therefore, this paper studies the various reduction methods of cogging torque when designing a BLDC motor.
What is cogging torque in Pmsm?
Cogging torque is the interaction between the flux of permanent magnets (PMs) and stator teeth. Another method to reduce cogging torque is performed by controlling energy in the PMSM . PMSM with skewed rotor is discussed for cogging torque reduction .
How do you reduce cogging torque?
The most effective way to reduce cogging torque is skewing of stator slots or rotor poles. It means skewing of one side of stator (rotor) core by few degrees in according to the other side of core (Fig. 7). The skewing allows to eliminate the cogging torque or to reduce it to minimum.
Is cogging torque bad?
COGGING torque is defined as the attraction/interaction of the magnetic poles (typically on the rotor) to the steel teeth (typically on the stator lamination) within an un-energized motor. Cogging is a “bad thing”; if the machine will not rotate, it is of no use for a process.
What is the effect of cogging torque?
The effect of cogging torque decreases the accuracy of the motor positioning at low speed, produces additional friction resistance, and to some extent, reduces the output power if the axial flux machine is applied as an electrical generator [8,9,10].
What is detent torque?
Detent torque is the amount of torque (the measured ability of a rotating element, as of a gear or shaft, to overcome turning resistance), that must be applied to overcome the static equilibrium of the motor when it is in an state of rest and unpowered.
How do you overcome cogging?
This problem can be easily solved by adopting several measures. These solutions are as follows: The number of slots in rotor should not be equal to the number of slots in the stator. Skewing of the rotor slots, that means the stack of the rotor is arranged in such a way that it angled with the axis of the rotation.
How do you stop cogging?
What are the options for eliminating cogging?
- Firstly, it has to be noted that sensorless motors are much more likely to have this issue than sensored motors.
- Switching to a brushless motor with more poles – the more poles a motor has the smoother it will perform at lower speeds (where most cogging occurs).
What is cogging how cogging effects can be reduced?
To reduce cogging in Iron Core linear motors, Tecnotion has taken two measures. First, the magnet plate is constructed with a skewed magnet arrangement that smooths out the movement of the iron core. Second, Tecnotion Iron Core motors use a proprietary coil laminate that is specifically designed to reduce cogging.
What is maximum holding torque?
The stepper motor holding torque refers to the maximum torque that the stepper motor can output when the motor’s phase windings pass the rated current and is in the static lock state. It is one of the most important parameters of a stepper motor.
What is cogging torque and what does it mean?
It is also known as detent or ‘no-current’ torque. This torque is position dependent and its periodicity per revolution depends on the number of magnetic poles and the number of teeth on the stator. Cogging torque is an undesirable component for the operation of such a motor. It is especially prominent at lower speeds,…
Why does a slotless magnet have no cogging torque?
Almost all the techniques used against to cogging torque also reduce the motor counter-electromotive force and so reduce the resultant running torque. A slotless and coreless permanent magnet motors does not have any cogging torque.
How is torque ripple measured in a motor?
A successful measurement requires a mechanical design with readily modeled dynamics, sensors with suitable band- width and resolution, a method of applying a smooth load to the motor, and a method for calibrating the measurement. This paper presents a thorough approach to the accurate measurement of torque ripple.
Is there torque ripple in permanent magnet motors?
This person is not on ResearchGate, or hasn’t claimed this research yet. Torque ripple in permanent-magnet synchronous motors is generally undesirable. Significant work has been done to minimize this torque, either by modifying the mechanical mo- tor design or by careful controller design.
How is cogging torque calculated? There are several possible ways of measuring the cogging torque, for example, by using (a) conventional torque transducer; (b) strain gauge bridge based on the reaction torque on the stator; (c) torque observer based on the voltage and current measurements; (d) special torque transducer for cogging torque measurement. What is…