DC Servo Motor Speed Control

- Oct 26, 2017-

DC Servo Motor Speed Control

DC servo motor have fast response, low speed stability, wide speed range and other characteristics,which is often used to follow-up system that need to achieve accurate speed control and position control.It is widely used in the industrial,national defense and civil areas,especially in the artillery stability system,carrier platform,radar antenna,robot control and other occasions.Although the development of AC servo motor is very rapid,but in these areas is difficult to replace the DC servo motor.

The traditional DC speed control system includes two feedback loops,namely,speed loop and current loop,using speed 

tachometer,current sensor (Hall device) and analog electronic circuit to achieve the speed closed-loop control.Modern  digital DC servo control uses high-speed digital signal processor (DSP),directly take sample from the speed and current signal,through the software to achieve digital comparison, digital adjustment operations (digital filtering),digital pulse width modulation and other functions,finally achieve precise control of speed.Compared with the two,the analog speed control system has the advantages of simple structure,low cost and high reliability,but the debugging is more complicated because the modification of the circuit parameters often requires hardware modification.The digital speed control system is complex and costly,but speed adjustment precision is very high,the debugging process is also easier,the performance of the speed control system can be controlled by software.

The following describes a method,between the analog speed and digital speed,that is,using programmable analog devices

(ISPPAC10) to achieve analog speed control system,the system circuit parameters can be adjusted by software,and can simulate

established System model.Using this method improve a CCD camera automatic zoom system the original DC governor,and achieve good results.

The analog speed control system is usually composed of two closed-loop,the speed closed loop and the current closed loop,

in order to enable the two to coordinate with each other,play a role,set up two regulators in the system,respectively adjust the speed and current.The two feedback closed loop structure use a ring with a ring of nested structure,which is the so-called double closed-loop speed control system.It has a dynamic response fast,anti-interference ability and so on,thus get widely used.

In the debugging process of the analog speed control system,due to the motor parameters or load mechanical properties with theoretical values are quite different,often need to replace the R, C and other components to change the circuit parameters to obtain the expected dynamic performance indicators,it is very troublesome.If use the programmable analog devices to constitute the regulator circuit,system parameters such as gain, bandwidth and even circuit structure can be modified by software,debugging is very convenient.

Programmable analog devices can be easily designed and simulate circuits.With its to design simulation speed circuit,the circuit parameters,the structure can be adjusted by software,make the debugging process become very simple.It should be noted that this type of device operating voltage is generally not more than 5V.

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