Power Balance of Starting Process for Pipe Belt Conveyor Based on Master-Slave Control
An output power imbalance usually occurs in the driving motor of pipe belt conveyor due to the load disturbance and a variety of environmental interferences. This paper focuses on the operating condition of pipe belt conveyor where the head and tail with inclined angle are equipped with a motor separately. The discrete element method is used to propose a discrete model of the pipe belt conveyor, and its simulation model is established in the AMESim. According to the direct torque control method for the three-phase asynchronous motor, the principles for controlling the balance of dual-motor power are analyzed. A master-slave control strategy is proposed, where the master motor is controlled using a speed-given strategy and the slave motor is controlled using a torque-given strategy. A simulation model is built for the dual-motor driven system in the MATLAB-Simulink. After establishing a correlation between parameters through VS2010, a joint simulation model was established for the control system of the pipe belt conveyor. Simulation analysis and field test of the starting process are performed. Results of comparison with the traditional master-slave control strategy demonstrate the ability of the proposed method to balance the master-slave motor power of the pipe belt conveyor more effectively.
Active Fault Tolerance Control Based on Consistent Matrix for Multimotor Synchronous System
This paper presents an active fault-tolerant method to mitigate sensor failures in multimotor synchronous control. First, inspired by the construction of the coupling matrix in complex network synchronous output, a consistent matrix is designed based on structural redundancy in synchronous control. This consistent matrix has two advantages: one is that it can reflect different sensor output similarities and the other one is that it can detect, locate, and estimate the sensor fault. Then, the fault information is integrated into the design of tolerance control with an improved mean feedback mechanism. The proposed method is suitable for both single and multiple fault situations, and its effectiveness is finally verified by both MATLAB simulation and the ABB semiphysical experimental platform.
Ocean thermal energy conversion: The promise of a clean future
Due to the world's heavy dependence on fossil fuels for electricity, pollution and global warming is on the rise. However, numerous countries are still relying on diesel generators as their main source of energy. There is a lack of practical alternative energy source that can meet the global energy demand without posing any threat to the natural environment. Ocean Thermal Energy Conversion (OTEC) is a concept that has the potential to address this growing issue. It is basically a mechanism that exploits the temperature difference between warm surface seawater and cold deep ocean water, to produce electricity. Although OTEC has a low energy density, the thermal energy in the ocean is vastly abundant. OTEC development has been dormant for a long time since it was first proposed in 1881. However, it has now regained recognition worldwide as a realistic solution to our world energy issue. Instead of having a great potential for power generation, it also carries the ability to produce high value products from the large volume of Deep Sea Water (DSW) that can be released as byproducts of OTEC plant operation. These products can hold a very profitable place in industries such as pharmaceutical, food, cosmetics and mineral water production. Further research on ocean current and DSW properties can someday lead to the commercial used of OTEC. This paper is a review of the basic concept, present status and future prospects of OTEC around the world.