Fehlertolerante Antriebsumrichter und deren Regelung
Zusammenfassung der Projektergebnisse
A typical modern industry drive consists of a power electronic converter, a digital controller for implementing the control algorithms, feedback sensors and motor. Several faults can affect the motor drive and a fault in any of the above will stop the drive running or at least it affects the drive performance. There are some critical applications like power plants, aerospace, railway locomotives, automobiles etc where the fault tolerant of the drive is very important. For interlinked production processes, as in modern industrial processing plants, a fault in a single drive can result in tremendous damages of materials and machines. Followup costs due to faults with drives in modern production plants can amount to huge sums. So the fault tolerance of adjustable speed drives is the area of great interest for modern drive solutions. In this research project, fault tolerant solutions to the different components of the drive are systematically developed and experimentally verified. Fault tolerant solutions to the, 1) Failure in the information processing (digital controller) 2) Power section (PWM inverter) 3) Feed back sensors ( position and current sensors) are presented. The validity of the proposed fault tolerant solutions are verified using the field oriented control (FOC) of a permanent magnet synchronous machine (PMSM). Fault tolerance concerning the digital controller is achieved based on the principles of triple modular redundancy. Three digital signal processors (DSPs) are used in parallel running the same control algorithm. The PWM output of all the three DSPs are voted out using a simple majority voting logic which is by itself fault tolerant. In order to keep all the three DSPs in time synchronism to each other, a serial communication is developed between the three processors, which will exchange timer values between all the three processors for synchronization. This communication is also used to exchange the control variables between the three processors such that there is synchronism in the control variables finally used for control computation. Connections between all the three processors are made such that there is no common point of failure in the system. Inverter fault tolerance is achieved by adding a redundant leg along with standard three legs of two level voltage source inverter (VSI). Faulted leg isolation and redundant leg insertion is done by using independent back to back connected thyristors. The proposed inverter provides tolerance to the both short circuit and open circuit faults of the switching devices. The post fault performance is same as the normal pre-fault operation and fault compensation is fast enough such that there is negligible disturbance in the drive operation. Fault detection algorithms are implemented in both the cases of position sensor failure and current sensors failure. Position sensorless control algorithm is used in case position sensor failure . Normally for FOC of PMSM with isolated neutral, two current sensors are sufficient. In case of failure in any of these two current sensors , a redundant current sensor measuring the third phase current is used in place of faulty current sensor. The whole fault tolerant system is developed based on the concept that only a single arbitrary fault occurs at any time. FOC of the PMSM implemented to test all the above fault tolerant solutions. In all the fault cases, the post fault performance is same as the pre-fault performance and during the fault detection and compensation there is negligible disturbance to the machine operation.
Projektbezogene Publikationen (Auswahl)
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“A Fault Tolerant Digital Controller for Power Electronic Applications”. In Conf. Rec. EPE 2009
R. R. Errabelli, P. Mutschler
