DC double closed-loop speed regulation system is a widely used, economical and applicable electric drive system.
It has the advantages of fast dynamic response and strong anti-interference ability. The feedback closed-loop control system has good anti-interference performance and can effectively suppress all disturbance effects on the forward channel of the feedback loop. The single closed-loop speed regulation system with speed negative feedback and PI regulator can realize the speed without static error while ensuring the stability of the system.
However, if the dynamic performance of the system is required, such as braking, small dynamic drop of sudden load, etc. It is difficult for a single closed-loop system to meet the requirements. This is mainly because in a single closed-loop system, the current or torque of the dynamic process cannot be completely controlled as required. In a single closed-loop system, only the current cut-off negative feedback link is specially used to control the current. However, it only limits the impact of current through strong negative feedback after exceeding the critical current Idcr value, and cannot perfectly control the dynamic waveform of current.
Schematic diagram of DC double closed-loop speed regulation system
What are the functions of two regulators in DC double closed-loop speed regulation system?
1, the role of speed regulator
(1) Make the rotation speed n change with the given voltage U*m, and when the deviation voltage is zero, the steady-state no static error will be realized.
(2) Anti-interference effect on load change.
(3) Its output limit determines the maximum allowable current.
2, the role of current regulator
(1) in the process of speed regulation, the current is changed with its given voltage u * i. ..
(2) It plays a timely anti-interference role when the grid voltage fluctuates.
(3) Ensure that the maximum allowable current is obtained when starting, so that the system can be started with maximum acceleration.
(4) When the motor is overloaded or even blocked, the maximum armature current is limited, thus playing the role of rapid safety protection. When the fault disappears, the system can automatically return to normal.
System parameter calculation