来源：http://www.aoshangjk.com 发布时间：2019-07-15 浏览：次
As for the power expansion of the DC servo drive motor, which is often used in radar, when the antenna is light, the speed is slow and the driving power is small, it is usually tens of watts, and the DC power supply can be used to control the motor directly. When the demand for driving power is close to or above kilowatt, it is important to choose the driving plan, that is, to expand the armature current of DC motor, to describe the servo system. Currently, high-power DC power supply is mostly used: transistor power amplifier, thyristor power amplifier and motor expander, etc. There is less use of kilowatt-level transistor power amplifiers.
Thyristor technology has been rapidly developed and widely used in the 1960s and early 1970s. However, due to various reasons, such as reliability, many commodities have abandoned thyristor control. Current integrated drive modules are usually made of transistors or thyristors. The motor expander is the power amplifier equipment of the traditional DC servo motor. Because of its simple operation and strong operation, the current new type radar products are still available. The following is mainly to expand the motor as an example, and communication servo motor to compare its advantages and disadvantages.
Extension motors are often referred to as extenders, which usually use communication asynchronous induction motors to drive two-stage DC generators in series to complete DC control. Two sets of control windings, each set of input impedance is several thousand euros. If the input impedance is about 10 thousand euros in series, the servo motor is usually a complementary balanced symmetrical input. When the system input is not zero, its balance is broken, so that the extended motor has output signal. When the input current is more than ten to tens of milliamperes, the output voltage can reach more than 100 V and the current of several to tens of amperes can be directly connected to the armature winding of the DC servo motor. Its main drawbacks are large volume and weight, non-linearity, especially near zero point is not very good, which is about high demand system needs to be carefully dealt with.
Communication servo motors are equipped with special drivers, which are much smaller in size and weight than expansion motors of the same power. It relies on the switching circuit composed of internal transistors or thyristors. According to the photoelectric encoder or Hall device in the servo motor, the orientation of the rotor at that time can be judged. It decides that the three-phase a, B and C of the driving motor should be transported. As a result, its power war stability is excellent. So it's not like the special power amplifier circuit needed to operate the extended motor. This kind of motor is usually permanent magnet type, and the three-phase change of a, B and C triggered by the driver controls the change of the motor, so it is called communication servo motor. The control signal input by the driver can be either a pulse train or a DC voltage signal (usually (+10v), so it is also called a DC brushless motor.
Comparison of Two Kinds of Electric Machines
Simple experiments have been done to compare the two motors: the original DC error signal of the system is directly connected to the analog control input of the communication servo driver, and the communication servo motor and its driver are used to replace the original differential power amplifier, motor expander and DC servo motor, while some of the control and angle measuring elements remain unchanged. Simply compare the output characteristics of the two schemes.
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