Application of CT DC Speed ​​Regulation System in Machine Tools

The DC speed control system of machine tool electrical appliances has experienced the comprehensive evaluation of the various systems of the CT system, the simulation V5 and the digital V5, and the Continental system to the current British CT system. See Table 1 for comparison. Excellent performance, overcoming the noise of the unit and the high failure rate of discrete components, easy to detect, the device is not easy to malfunction. Table 1 Comparison of several DC speed control systems. Motor generator set simulation V5 digital V5 Continental system CT system noise size failure rate is higher than High and low, low adjustability, high, high maintenance, low, high, high energy consumption, low performance, good performance, good 2CT system introduction. MENTOR is the latest series of DC motor speed control drives with modern level of micro-computerized industrial production produced by British CT Company. The product features control, monitoring, protection and serial communication features of the CT system as follows: The MENTOR system is equipped with a range of parameters to provide maximum adaptability to industrial applications. The parameter is programmed into the menu to form the most convenient way for the user to quickly and easily access the parameters. The various debugging parameters of the DC motor can accurately control the operation of the motor through the setting of more than 200 parameters in 16 menus. Due to the use of computer phase-locking technology, the safety symmetry of the pulse is guaranteed, which contributes to the stability of the system, especially the low-speed stability of the system, and has the capability of self-diagnosis and self-adaptation.
The fault indication is comprehensive and can accurately indicate the common faults such as armature overcurrent armature open circuit, excitation over current, demagnetization, feedback loss feedback polarity error in the peripheral circuit, and it is convenient for maintenance to find the fault point. The communication interface is a standard machine-machine interface. Configuration that allows PLC or computer control to form an automated system.
3 line connection DC motor must control the amount in the actual operation is the speed, output torque and steering, speed is proportional to the armature potential; torque is proportional to the armature current and flux, the steering is simply by the armature and excitation The relative polarity of the voltage is determined, so the two quantities of armature voltage and excitation voltage must be controlled. In machine tool applications, the motor is generally required to operate reversibly. MENTOR uses a four-quadrant anti-parallel four-quadrant (reversible) driver. This configuration does not need to be inverted. To the contactor, it can completely control the forward and reverse and positive and negative braking of the motor, overcome the disadvantage that the deceleration of the single-phase drive requires no control or linearity when the external circuit brake is applied. See Figure 3.1 for the basic wiring diagram of the CT system. In the pivot control, the AC input terminal L L3 and the control power source E Bu E3 must be in phase. The given signal is input by TB1-TB3, and the given voltage is regulated by a given potentiometer. The maximum reference value is 10V, and its power supply can be supplied internally or externally.
The power supply can be used as a given power supply for motor speed regulation, given by TB3 input.
Compared with the set value, the motor speed TB21 is controlled to run the TB31 one-one enable terminal.
When there is a fault in the periphery of the signal, the thyristor power supply is turned off.
3.2 Motor Excitation Control The MENTOR series main control board with excitation control software provides two optional maximum excitation current values, and the lower value is controlled by a programmable timer. The calculated current error obtained by the excitation current reference and the excitation current feedback phase is the input of the excitation current loop, and the output of the excitation current loop is the firing angle, which is controlled by the trigger angle limit. The field current reference is the output of the back EMF voltage loop and is limited by the programmable maximum and minimum field currents. The back EMF setting is the factor that determines the excitation current. When the calculated value of the back EMF is less than the set value, both the voltage loop output and the subsequent excitation current reference take the maximum value. When the calculated value of the back EMF is greater than the set value, the voltage loop reduces the excitation current given, and the back EMF is set to the set value. The magnetic flux of the motor is determined by the excitation current. If the excitation voltage is independent of the armature voltage, the speed is at full power. The base speed point provided by the armature voltage can be exceeded and the current becomes the maximum value. Since the torque is directly proportional to the magnetic flux, the maximum torque is reduced as the speed begins to increase from the field weakening.
4 Parameter setting 4.1 Armature current Reversible drive current limit According to the parameters 4. 05, 4.06, calculate the current limit proportional coefficient = motor full load current drive rated current 4.2 speed feedback when the input is ramped speed and hard speed timing, The two can be added or replaced. The selected speed reference is added to the speed offset and the result is given as the final speed. It deviates from the algebra and velocity of the velocity feedback. The speed deviation is formed by the PID action to form the speed loop output. The feedback form is determined by 3.12 and 3.13 (see Table 2). Table 2 Parameter Encoder Feedback Speedometer Feedback Voltage Feedback If armature voltage feedback is used, the maximum armature voltage value is used. The calibration of the armature voltage measurement value makes the maximum armature voltage corresponding to the speed feedback full scale. If the encoder or tachometer is used as the speed feedback, the armature voltage is continuously monitored. When the voltage value exceeds the armature voltage setting value. Generate a voltage clamp to prevent the armature voltage from exceeding the set value.
4.3 Armature voltage 15 setting.
4.4 Proportion of speed loop and current loop, integral coefficient Velocity loop ratio (P): Increasing the value of this parameter increases the damping of the system and speeds up the dynamic response of the system. For a certain load, too large a parameter will cause instability of the system.
Speed ​​loop integral (I): The integral gain factor is multiplied by the speed deviation to obtain a correction value. The correction value ensures that the speed is not increased when the steady state is increased. This parameter value increases the rate of speed recovery after the system is disturbed. If the parameter value is too large, the speed tends to oscillate instead of the ratio of the fast recovery current loop. The integral coefficient can be based on the motor nameplate parameters. The on-line debugging during the running process makes the motor running optimally. 4.5 Excitation current 13 Excitation permission, CT system It can also economically excite the two parameters of 6.15 and 612, allowing the drive to automatically select the maximum excitation current after stopping for a certain period of time to save energy and protect the motor from generating heat when the motor is not running.
5 fault monitoring If the drive fails, the index window will display trip, the data information will flash, the data window shows the English abbreviation of the cause of the fault, see Table 3, Table 3, abbreviated code, fault reason, armature overcurrent, overcurrent of armature circuit, instantaneous protection The action armature open-circuit feedback loses the speedometer or the encoder has no signal feedback. The polarity is wrong. The excitation power is lost. The excitation power supply circuit has no current.
Hardware failure Driver hardware failure Internal power failure One or more internal power supply overload phase loss or multi-phase power supply open u Heater overheating thermal resistance limit 6 Conclusion Through careful study of the CT system, master the CT DC speed control system Features In the actual use of the main equipment 10", 11", 190/320 and other trampolines in our branch, we have continuously revised the parameters of the CT DC speed control system and continuously improved the peripheral control circuit. The downtime rate of large-scale equipment of the branch has been declining year by year, meeting the needs of production and operation (received on December 26, 2003).

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