The common motors, stepper motors, servo motors, and steering wheels mentioned here refer to DC micro motors, which are the most common types we encounter in daily life. An electric motor, also known as a "motor," is an electromagnetic induction device that converts or transmits electromagnetic energy based on the law of electromagnetic induction. In power circuits, an electric motor is represented by the letter "M" (formerly "D"). Its main function is to generate driving torque, serving as a power source for electrical appliances or various machines. A generator is represented by the letter "G" in circuit diagrams.
Ordinary motor
Ordinary motors are the most common type of motor we see in daily life, such as those found in electric toys and shavers. They are generally DC brushed motors. These motors are characterized by excessively high speed and low torque. They usually only have two pins. Connecting the positive and negative terminals of a battery to the two pins will make the motor rotate, and connecting the positive and negative terminals of the battery to the two pins in the opposite direction will cause the motor to rotate in the opposite direction.
Gear motor
A geared motor is simply a regular motor with a gearbox added, which reduces the speed and increases the torque, giving the regular motor a wider range of applications.
Stepper motor
A stepper motor is an open-loop control unit that converts electrical pulse signals into angular or linear displacement. Under non-overload conditions, the motor's speed and stopping position depend only on the frequency and number of pulse signals, and are unaffected by load changes. When the stepper driver receives a pulse signal, it drives the stepper motor to rotate a fixed angle in a set direction, called the "step angle." Its rotation occurs step by step at fixed angles. The angular displacement can be controlled by controlling the number of pulses, thus achieving accurate positioning; simultaneously, the motor's speed and acceleration can be controlled by controlling the pulse frequency, thus achieving speed regulation.
Servo
A servo motor mainly consists of a housing, circuit board, coreless motor, gears, and position detector. Its working principle is as follows: a receiver sends a signal to the servo motor, the IC on the circuit board determines the direction of rotation, and then drives the coreless motor to start rotating. Power is transmitted to the swing arm through the reduction gears. Simultaneously, the position detector sends back a signal to determine whether the desired position has been reached. The position detector is essentially a variable resistor; its resistance changes as the servo motor rotates, and the angle of rotation is determined by detecting the resistance value.
Specifications provided by servo manufacturers typically include basic information such as dimensions (mm), torque (kg/cm), speed (seconds/60°), test voltage (V), and weight (g). Torque is measured in kg/cm, meaning the weight (in kilograms) that can be lifted at a distance of 1 cm from the lever arm. This is the concept of lever arm; therefore, the longer the lever arm, the lower the torque. Speed is measured in sec/60°, meaning the time required for the servo to rotate 60°.
Servo motor
Servo motors, also known as actuator motors, are used as actuators in automatic control systems to convert received electrical signals into angular displacement or angular velocity output on the motor shaft. They are divided into two main categories: DC and AC servo motors. Their main characteristic is that they do not rotate when the signal voltage is zero, and their speed decreases uniformly as the torque increases.
Servo motors primarily rely on pulses for positioning. Essentially, a servo motor receives one pulse and rotates by the angle corresponding to that pulse, thus achieving displacement. Because servo motors themselves have the function of emitting pulses, they emit a corresponding number of pulses for each rotation angle. This creates a feedback loop, or closed loop, between the pulses received by the servo motor and the pulses emitted. In this way, the system knows how many pulses were sent to the servo motor and how many were received, enabling precise control of the motor's rotation and achieving accurate positioning down to 0.001mm.
Servo motors are divided into two main categories: AC servo motors and DC servo motors.
AC servo motors are divided into two categories: asynchronous AC servo motors and synchronous AC servo motors.
DC servo motors are divided into brushed and brushless motors. Brushed motors are low in cost, simple in structure, have high starting torque, wide speed range, and are easy to control. However, they require maintenance, which is inconvenient (replacing carbon brushes), generates electromagnetic interference, and has environmental requirements. Therefore, they can be used in cost-sensitive general industrial and civilian applications.
Gear motor principle
A geared motor, also known as a geared motor or a speed reducer, is a motor-driven closed-loop gear reduction device. It is a speed reduction transmission mechanism that integrates the motor and gearbox to reduce speed and increase torque to meet the needs of mechanical equipment.
The purpose of a geared motor is to reduce speed.
The required speed, commonly referred to as output speed, is achieved by using a reduction gearbox to increase the motor's speed. ② Increase torque.
Under the same power conditions, the slower the output speed of a geared motor, the greater the torque, and vice versa. ③ Change the transmission direction.
For example, we can use two sector gears to transmit force vertically to another rotating shaft. ④ Clutch function.
We can achieve immediate braking upon power failure by adding a brake clutch.
Basic principle of stepper motor
Working principle:
Typically, the rotor of a stepper motor is a permanent magnet. When current flows through the stator windings, the stator windings generate a vector magnetic field. This magnetic field causes the rotor to rotate by an angle, aligning the direction of the rotor's magnetic field with that of the stator's magnetic field. When the stator's vector magnetic field rotates by an angle, the rotor also rotates by the same angle. Each input electrical pulse causes the motor to rotate one angle and move one step forward. Its output angular displacement is proportional to the number of input pulses, and its rotational speed is proportional to the pulse frequency. Changing the energizing sequence of the windings reverses the motor's rotation. Therefore, the rotation of a stepper motor can be controlled by adjusting the number and frequency of pulses and the energizing sequence of each phase winding.
Heating principle:
Most motors contain an iron core and winding coils. The windings have resistance, and when current flows through them, losses occur. The magnitude of these losses is proportional to the resistance and the square of the current; this is what we commonly call copper loss. If the current is not standard DC or a sine wave, harmonic losses will also occur. The iron core has hysteresis and eddy current effects, which also generate losses in an alternating magnetic field. The magnitude of these losses depends on the material, current, frequency, and voltage; this is called iron loss. Both copper and iron losses manifest as heat, thus affecting the motor's efficiency. Stepper motors generally prioritize positioning accuracy and torque output, resulting in relatively low efficiency, generally higher current, and higher harmonic content. The frequency of the alternating current also varies with the rotational speed. Therefore, stepper motors commonly experience heat generation, and this is more severe than with general AC motors.
Servo principle
A bias voltage is generated by the PWM wave entering the internal circuit, which triggers the motor to move the potentiometer through the reduction gear. When the voltage difference is zero, the motor stops, thus achieving the servo effect.
The PWM protocol for servos is the same, but the latest servos may use a different one.
The protocol is generally as follows: a high-level pulse width of 0.5ms to 2.5ms controls the servo motor to rotate through different angles.
Servo motor working principle
The working principle of a servo motor is relatively simple, yet it is highly efficient. The servo circuitry is built into the motor unit, which uses a flexible shaft, typically equipped with gears. Electrical signals control the motor and determine the amount of shaft movement. The internal setup of a servo motor is simple: a small DC motor, control circuitry, and a potentiometer. The DC motor is connected to a control wheel via gears; as the motor rotates, the resistance of the potentiometer changes, allowing the control circuitry to precisely adjust the motion and direction.
When the axis is in the correct (ideal) position, the motor stops receiving power. If the axis does not stop at the target position, the motor continues to run until it enters the correct direction. The target position is transmitted via a signal line using electrical pulses. Therefore, the motor speed is proportional to the actual and ideal position. As the motor approaches the desired position, it begins to rotate slowly, but when it reaches its maximum range, the speed is very fast. In other words, servo motors only need to complete the task as quickly as possible, making them highly efficient devices.
Hongfeida's main recommendation:
Honeywell thickness gauge spare parts / Schneider Electric LXM servo drives, BMX modules, 140/TSX modules / ABB DCS modules, robot spare parts, IGBT module boards, ABB tension sensors / Siemens Robicon series products, 7MB flue gas analyzers, 3UF motor protectors, 6AG wide-temperature series modules (recommended for project clients with longer lead times), 6FC5851 and 6FC5852 software / Rexroth servo drives and motors / FANUC servo drives and motors / Yaskawa servo drives and motors.
1. We undertake the renovation, design, installation, and commissioning of automated integrated systems such as PLC control cabinets, frequency converter cabinets, and medium and low voltage switchgear;
2. Repair: Servo drives, PLC modules, frequency converters, touch screens, DCS cards, etc.
3. Maintenance and parts replacement for KUKA robots.
