Automatic control system not only in the rapid development of theory, but also in the application of its devices with each passing day. Modular, digital, high-precision, long-life devices every 3 to 5 years there are replacement products available. Traditional AC servo motor characteristics of soft, and the output characteristics of the servo motor is not a single value; stepper motor is generally open-loop control can not be accurately positioned, the motor itself also has a speed resonance zone, pwm speed control system on the position tracking performance is poor , Frequency control is simpler but accuracy is not enough sometimes. DC motor servo system is widely used in position servo system due to its excellent performance, but it also has some shortcomings such as complicated structure, prominent contradictions in the dead zone at ultra-low speed, and Commutation brushes can cause noise and maintenance problems. At present, the new type of permanent magnet AC servo motor is developed rapidly, especially from the square wave control to the sine wave control, the system performance is better, and its speed range is wide, especially the low speed is superior in performance. AC and DC servo motor system The following from the power-driven, performance, protection circuits, etc., described its and DC servo motor system of different characteristics. Power-driven For the power amplifier part of the drive motor of the DC servo system frequently used on the radar, when the antenna is light in weight and slow in rotation, and the driving power is small, it is generally several tens of watts, and the direct-current power supply can be used to control the motor directly. When the drive power requirements in the nearly kilowatts or kilowatts above, select the drive scheme, that is, to enlarge the DC motor armature current, is the design of an important part of the servo system. High-power DC power currently used are: transistor amplifier, thyristor amplifier and motor amplifier and so on. For kilowatt-class transistor amplifier use less. Thyristor technology in the early 1960s to early 1970s rapid development and widespread application, but due to various reasons at that time, such as reliability, many products to give up the SCR control. The current integrated driver modules are generally made of transistors or thyristors. Motor amplifier is the traditional DC servo motor amplifier device, because of its simple control, strong and durable, the current new models of radar products are still used. The following mainly to enlarge the motor, for example, and AC servo motor to compare their advantages and disadvantages. Amplifier motor often referred to as the amplifier, the general induction AC induction motor is connected in series with two DC generator, in order to achieve DC control. Two sets of control windings, the input impedance of each group is several thousands of ohms. If the input impedance of series connection is about 10 kilohms, the servo motor is generally balanced balanced input symmetrically. When the system input is not zero, the balance is broken, output signal. When the input current is more than a dozen to tens of milliamps when the output of up to 100v above the DC voltage and a few amperes to tens of security of the current directly connected to the DC servo motor armature winding. The main drawback is the volumetric weight, non-linearity, especially in the vicinity of zero is not very good, which requires careful handling of demanding systems. The AC servo motors are equipped with a special drive, which is much smaller than the volume and weight of the same magnification motor, which rely on the internal transistor or thyristor switch circuit, according to the servo motor photoelectric encoder or Hall device to determine The rotor's current position determines the status of the three motors a, b and c corresponding output, so its efficiency and stability are good. So unlike the control amplifier motor need to do a special amplifier circuit. This kind of motor is usually of permanent magnetic type. The current control motor with three-phase changes of a, b and c generated by the driver rotates. Therefore, it is called AC servo motor. The control signal input by the driver can be pulse train or DC voltage Signal (usually ± 10v), so it has also been called DC brushless motor. A simple test of two kinds of motor comparison A simple test of two kinds of motor comparison: As long as the system directly to the DC error signal directly connected to the AC servo drive analog control input, AC servo motor and its drive to replace the original differential amplifier, motor amplifier and DC Servo motor, and the control part and the angle components are unchanged, a simple comparison of the output characteristics of the two programs. Yi He Technology (Shenzhen) Co.,Ltd , https://www.ball-shootingmachine.com