Direct drive motors , short for direct-drive electric motors, primarily refer to motors that drive loads without the need for a transmission device. Because direct drive motors avoid the use of transmission devices such as belts, which are often the components with the highest failure rate in the system, systems using direct drive motors should technically have a lower failure rate. Mechanical systems using transmission devices (such as reduction gears, pulleys, etc.), like crushers, often have complex structures, large sizes, increased weight, and bring various problems related to system operating costs, noise, and transmission efficiency. The advent of direct drive motors has made drive devices more compact, lighter, and easier to control. Based on their manufacturing principles, direct drive motors can be mainly divided into two categories: torque motors and linear motors.
( 1 ) Torque Motor. The working principle of a DC torque motor is the same as that of a regular DC motor, but the difference lies in its structure. In order to generate large torque and low speed under a certain volume and armature voltage, a DC torque motor is generally made into a flat structure, with the ratio of armature length to diameter generally around 0.2 and a large number of pole pairs. In order to reduce the fluctuation of torque and speed, a large number of slots and commutator segments are selected. Permanent magnets are usually used to generate the magnetic field. The stator is a slotted ring made of soft magnetic material. The wedges in the slots are made of copper plates and also serve as commutator segments. The two ends of the slot wedges extend out of the slot, one end is used for armature winding connection, and the other end is arranged into a ring commutator. All parts of the rotor are cast as a whole by high-temperature epoxy resin.
AC torque motors are divided into single-phase and three-phase types, derived from the basic series of single-phase and three-phase induction motors, respectively. Their structure and mounting dimensions are consistent with the basic series. The difference lies in the fact that their rotor bars are typically made of materials with higher resistivity, such as brass, pure copper, and aluminum-manganese alloy. The rotor resistance is much higher than that of ordinary induction motors, resulting in significantly different mechanical characteristics.
( 2 ) Crusher, linear motor. A linear motor is a transmission device that directly converts electrical energy into linear motion mechanical energy by expanding a closed magnetic field into an open magnetic field, without the need for any intermediate conversion mechanism. The structure of a linear motor can be regarded as a rotary motor cut radially and the circumference of the motor unfolded into a straight line. The stator is equivalent to the primary of the linear motor, and the rotor is equivalent to the secondary of the linear motor. When current flows through the primary, a traveling wave magnetic field is generated in the air gap between the primary and secondary. Under the action of the traveling wave magnetic field and the secondary permanent magnet, a driving force is generated, thereby realizing the linear motion of the moving parts.
Direct drive motor applications
The most common application related to daily life is the washing machine, which is a new technology (or concept) that has been widely promoted by major washing machine manufacturers in recent years. This technology does not use a belt to connect the washing machine's drum and drive motor.
Direct drive motors are suitable for all types of washing machines, and their main advantages include quiet operation, energy saving, smooth operation, and powerful performance.
