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At present, auxiliary traction control system of most electric-wheel dump trucks in domestic market is driven by diesel engine to drive cooling fan to dissipate heat, the cooling power cannot be changed by frequency conversion, and the fuel consumption of diesel engine will increase under braking conditions. In addition, the traction strategy adopts the field orientation control, which has the problem of slow torque response under fast switching conditions.In this paper, an integrated main and auxiliary converter of high power electric-wheel dump truck is designed and its traction control system is investigated. In the vehicle traction control system, the main traction system adopts high performance direct torque control algorithm to drive two 960 kW induction motors. For the auxiliary traction system, it is controlled by DC/DC front-end with isolation transformer and then DC/AC back-end inverter. The back-end inverter guarantees stable operation of fan and pump loads in full frequency range. At present, the dump truck loaded with this integrated main and auxiliary traction system has been running stably for 3 571 h in Shanxi Pingsu Open-pit Coal Mine, with a cumulative travel distance of 31 632.4 km and a transportation volume of 1 445 276 tons in total, which shows that this traction system can work stably, reliably and efficiently.

This paper focuses on the development of an online method for diagnosing high-resistance connection (HRC) in delta-connected permanent magnet synchronous machine (PMSM) using zero-sequence current component (ZSCC). The development of this method begins with the establishment of the mathematic model of the PMSM with the HRC. Based on the model, a ZSCC-based method is proposed to diagnose the HRC. The fault indicator and angle differences are defined for fault diagnosis. To implement online diagnosis, an effective frequency tracking algorithm is applied. Finally, the fault diagnosis steps are presented. This method is capable of detecting the fault, evaluating the fault severity, and identifying the faulty phases. The simulation and experiment are carried out to verify the proposed method. Both the results show the validity of the proposed method, leading to the effective diagnosis of the HRC in the delta-connected PMSM. [ABSTRACT FROM AUTHOR]