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Общемосковский постоянный научный семинар «Теория автоматического управления и оптимизации»
13 сентября 2016 г., г. Москва, ИПУ РАН, комн. 433.
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[NEW RESULTS ON FORCED DYNAMICS CONTROL OF SERVODRIVES]
Jan Vittek
University of Zilina
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Аннотация:
A new approach to the control of a.c. drives emerging from previous research cooperation with Trapeznikov Institute of Control Sciences Moscow and University of East London is presented as ‘Forced Dynamics Control’. This new control method based on ‚feedback linearization‘ enables realization of a chosen form of a speed response transient during the time taken to reach a steady-state speed. The response can be chosen arbitrary and selected operational modes such as constant acceleration, constant jerk, and linear first order and second order dynamics are described as very common in practice. Advantages of the developed control method are further described as following Case Studies:
1. Combination of FDC with direct and indirect vector control
2. Exploitation of FDC for position control including Sliding Mode Control and Time Optimal Control
3. Exploitation of FDC for control of the drive with flexible coupling
4. Exploitation of FDC for energy near-optimal control.
The combination of ‘Forced Dynamics Control’ (FDC) and ‘Vector Control’ (VC) of a.c. drives is presented in Case Study 1. The developed control system employing induction motor respects ‘indirect vector control’ conditions and can operate with shaft position encoder or shaft sensorless. In this case only the stator currents are measured, the applied stator voltages being determined by the computed switching inverter algorithm and dc voltage measurement. Obtained experimental results for indirect VC of induction motor enabling prescribed speed response and respecting ‘FDC’ indicate good agreement with the theoretical predictions. As an extension of combined direct VC and FDC the speed control system for linear PMSM is shown.
Case Study 2 shows exploitation of FDC of drive’s speed for the design of position control. The position controller is of the cascade structure comprising an inner FDC speed control loop and an outer position control loop based on sliding mode control (SMC). To avoid control chattering the smoothing integrator is introduced into position control system. Final version of the SMC has the ‘signum function’ replaced by the high gain enabling rearrangement of the block diagram to avoid extra output derivative. Principles of FDC are used also to achieve nearly time optimal position control of the drives equipped with controllers enabling close following of time varying reference position inputs. Then the position response of a real time model of the closed-loop time optimal control system provides the reference input to the drive control loop. Experimental results confirmed the near time optimal behaviour of the drive.
Possibility to exploit FDC for control of the drive with significant vibration modes is presented in Case Study 3. To exploit the only position sensor on the motor side, all necessary control variables are estimated in observers based on rotor position and stator current measurements. Preliminary experimental results of the overall control system indicate the desired robustness.
In Case Study 4 FDC based control system is used for verification of energy expenditures of the two energy saving position control strategies, one as energy optimal and second one as energy near-optimal. Overall block diagram consists of energy saving profile generator, pre-compensator and position control system, which is capable of precise tracking of prescribed state-variables. Designed control strategies are derived for load with combined constant, linear and quadratic frictions or load torques and respect prescribed maneuver time while having defined acceleration profile to achieve the demanded position. Energy demands of both control strategies are verified and compared via simulations which confirmed possibility of achieving energy savings.
Язык доклада: английский
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