GKKA21216GO11 GKKAC7689 ABB

When the system is given zero,the speed regulator ASR and the current regulator ACR are locked to zero by the zero-speed blocking signal.At this time,the system mainly consists of the circulating current regulator ARR to form a cross-feedback constant current system.Due to the influence of the given circulating current,the two groups of thyristors are in the rectification state,the output voltages are equal in magnitude and opposite in polarity,the DC motor armature voltage is zero,the motor stops,and the output current flows through the two groups of thyristors to form a circulating current.The circulating current should not be too large,generally limited to about 5%of the rated current of the motor.When starting in the forward direction,with the increase of the speed signal Ugn,the blocking signal is released,the speed regulator ASR is output positive,and the motor runs in the forward direction.At this time,the positive group current feedback voltage+Ufi2 reflects the sum of the motor armature current and the circulating current;the reverse group current feedback voltage-Uril reflects the armature current,so the main current can be adjusted.However,the circulating current given signal-Ugih and the cross current feedback signal-Ufil added to the input end of the positive group circulating current regulator have little influence on this regulation process.The input voltage of the anti-group circulating current regulator is(+Uk)+(-Ugih)+(Ufi2).With the continuous increase of the armature current,when it reaches a certain level,the circulating current will disappear automatically,and the anti-group thyristor will enter the waiting state.Inverted state.The opposite is true when starting in reverse.In addition,the controllable circulating current reversible speed regulation system still has processes such as inverter braking,reverse braking and feedback braking when braking.Since the start-up process is also a process in which the circulating current is gradually reduced,the circulating current of the system reaches the maximum value when the motor stops.The circulating current helps the system to overcome the switching dead zone and improves the transition characteristics.

系统给定为零时，转速调节器ASR、电流调节器ACR被零速封锁信号锁零。此时，系统主要由环流调节器ARR组成交叉反馈的恒流系统。由于环流给定的影响，2组可控硅均处于整流状态，输出的电压大小相等、极性相反，直流电机电枢电压为零，电机停转，输出的电流流经2组可控硅形成环流。环流不宜过大，一般限制在电机额定电流的5%左右。正向启动时，随着转速信号Ugn的增大，封锁信号解除，转速调节器ASR输正，电机正向运行。此时，正组电流反馈电压+Ufi2反映电机电枢电流与环流电流之和;反组电流反馈电压-Uril反映了电枢电流，因此可以对主电流进行调节。而正组环流调节器输入端所加的环流给定信号-Ugih和交叉电流反馈信号-Ufil对这个调节过程影响极小。反组环流调节器的输入电压为(+Uk)+(-Ugih)+(Ufi2)，随着电枢电流的不断增大，当达到一定程度时，环流自动消失，反组可控硅进入待逆变状态。反向启动时情况相反。另外，可控环流可逆调速系统制动时仍然具有本桥逆变，反接制动和反馈制动等过程。由于启动过程也是环流逐渐减小的过程，因此，电机停转时，系统的环流达最大值。环流有助于系统越过切换死区，改善过渡特性。