Which is better, a hollow cup motor or a brushed motor?
Hollow cup motors and brushed motors are two widely used drive motors. Which type of drive motor is better?
Release time:
2021-08-24 17:31
Hollow cup motors and brushed motors are two widely used drive motors. Which drive motor is better? Below is a detailed introduction to the advantages and disadvantages of hollow cup motors and brushed motors.
Advantages of hollow cup motors:
1. High power density: Power density is the ratio of output power to weight or volume. Motors with copper plate coils are small in size and have good performance. Compared to traditional coils, the induction coils of copper plate coils are lighter. There is no winding and slotted silicon steel sheet, eliminating the eddy current and hysteresis losses they produce; the eddy current loss of copper plate coils is very small and easy to control, improving the efficiency of the motor and ensuring high output torque and output power.
2. High efficiency: The high efficiency of the motor is due to the absence of eddy current and hysteresis losses caused by winding and slotted silicon steel sheets; additionally, the resistance is small, reducing copper loss.
3. No torque lag: The copper plate coil method has no slotted silicon steel sheets, no hysteresis loss, and the absence of cogging effects reduces speed and torque fluctuations.
4. No cogging effect: The copper plate coil method has no slotted silicon steel sheets, which eliminates the cogging effect caused by the interaction between the slots and the magnets. The coils have a structure without a core, and all steel components either rotate together (for example, brushless motors) or remain completely stationary (for example, brushed motors), making cogging effects and torque lag phenomena significantly absent.
5. Low starting torque: With no hysteresis loss and no cogging effect, the starting torque is very low. At startup, the bearing load is usually the only obstacle. This method allows the wind turbine to have a very low starting wind speed.
6. No radial force between rotor and stator: Due to the absence of stationary silicon steel sheets, there is no radial magnetic force between the rotor and stator. This is especially important in critical applications, as the radial force between the rotor and stator can cause rotor instability. Reducing radial force will improve rotor stability.
7. Smooth speed curve, low noise: The absence of slotted silicon steel sheets reduces the harmonics of torque and voltage. Additionally, since there is no AC field inside the motor, there is no noise generated by AC. Only noise from bearings and airflow, as well as vibrations caused by non-sinusoidal currents, are present.
8. High-speed brushless coils: A low inductance value is necessary for high-speed operation. A low inductance value allows for a lower starting voltage. By increasing the number of poles and reducing the thickness of the casing, the smaller inductance value helps reduce the weight of the motor while also increasing power density.
9. Fast response brushed coils: The brushed motor with copper plate coils has a low inductance value, allowing for a quick response of current to voltage fluctuations. The rotor's moment of inertia is small, and the response speed of torque to current is comparable. Therefore, the rotor's acceleration is twice that of traditional motors.
Disadvantages of hollow cup motors: When a DC motor is in a stationary state, if one phase of the winding is cut off or the power supply is cut off and one phase is powered, the magnetic fields generated by the windings are equal in size but opposite in direction, resulting in a rotating magnetic field. The torque generated by them acting on the rotor is equal in size but opposite in direction, canceling each other out, resulting in zero starting torque, and the motor cannot start. This is a disadvantage of hollow cup reduction motors. The disadvantage of hollow cup reduction motors is a highly dangerous fault. First, we need to check if the DC motor is faulty, check if there are any open circuit switches in the power supply circuit, if there are any blown fuses, and then check if there is any interruption in the three-phase winding.
Advantages of brushed motors: Simple structure, brushed motors have a simple mechanism, easy to produce and process, convenient for maintenance, and easy to control; DC motors also have quick response, larger starting torque, and can provide rated torque from zero speed to rated speed. They run smoothly, with good starting and braking effects. Brushed motors are controlled by voltage regulation, so starting and braking are smooth, and they also run steadily at constant speed. Brushless motors are usually controlled by digital frequency conversion, first converting AC to DC, and then DC back to AC, controlling speed through frequency changes. Therefore, brushless motors run unstably during starting and braking, with significant vibrations, and only run smoothly at constant speed. High control precision, brushed motors are usually used with gearboxes and encoders, allowing for greater output power and higher control precision, which can reach 0.01 mm, almost allowing moving parts to stop at any desired position. All precision machine tools use DC motors for control precision.
Disadvantages of brushed motors: There is friction between the brushes and the commutator, leading to reduced efficiency, increased noise, and easy heating. The lifespan of brushed motors is several times shorter than that of brushless motors. Maintenance is troublesome, requiring constant replacement of brushes. Due to high resistance, efficiency is low, and output power is less. The friction between brushes and the commutator can cause sparks, leading to significant interference.
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Introduction to Micro DC Gear Motors Micro DC gear motors are a miniaturized motor system, typically consisting of a DC motor and a gearbox. Here are some related introductions to micro DC gear motors: DC Motor Section: Working Principle: The DC motor generates current by moving a conductive coil in a magnetic field, thus producing electromagnetic force to drive the motor's rotation. Structure: Micro DC motors usually adopt a separate structure, including an armature (rotating part) and an electromagnet (stator part). Types: Common types of DC motors include brushed DC motors and brushless DC motors. Brushed DC motors use brushes to connect to the armature, while brushless DC motors control current through an electronic speed controller, eliminating the need for brushes. Gearbox Section: Function: The gearbox is used to slow down the motor's output speed while increasing torque. This is crucial for applications requiring higher torque and lower speeds, such as robotic arms and camera gimbals. Structure: Gearboxes typically consist of gears that achieve the reduction ratio through different gear combinations. The reduction ratio is the ratio of input speed to output speed. Types: Common types of gearboxes include planetary gears, worm gears, and helical gears. Different types of gearboxes are suitable for different application scenarios. Applications: Micro DC gear motors are widely used in various fields, including consumer electronics (such as cameras and printers), medical devices, robotics, and automotive electronics. In these applications, micro DC gear motors are typically used to control precise movements, provide sufficient torque, and achieve efficient performance in limited spaces. Control and Drive: Micro DC gear motors usually require corresponding electronic speed controllers or controllers to precisely control rotation speed and direction. The control system can adjust the motor's output according to application needs, achieving precise position control and speed regulation. Performance Parameters: The performance parameters of micro DC gear motors include rated voltage, rated speed, rated torque, efficiency, etc. These parameters are crucial for selecting and designing motor systems. In summary, micro DC gear motors have been widely applied under the trends of miniaturization, precision, and efficiency, providing reliable driving force for many electric devices and systems.
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