Experimental studies of rail grinding modes using a new high-speed electric drive

OBRABOTKAMETALLOV technology Vol. 26 No. 3 2024 voltage of increased frequency and ensures regulation of the grinding wheel speed, a synchronous motor with permanent magnets of high-speed design with a built-in magnetic field sensor is used as an electric motor, and the frequency converter has an increased carrier frequency and is equipped with high-speed digital control interfaces. The following advantages of using permanent magnets in the electric motor can be noted in the adopted concept of the new electric drive: Compactness (reduction of electric motor dimensions by almost 2 times in comparison with general industrial design with the same parameters); Smooth regulation of the electric motor shaft speed; Electric motor efficiency is up to 97 % and maximum specific performance. In accordance with the design documentation of JSC “Tayfun” a prototype rail-grinding high-speed electric drive was produced, containing a synchronous motor with permanent magnets as an electric motor (Fig. 3) with the following technical characteristics: – Rated power – 46.5 kW; – Nominal speed – 7,000 rpm; – Nominal parameters of supplying three-phase voltage – 380 V; 233.33 Hz; – Frequency converter power supply – three-phase input voltage 285–494 V, frequency 50 Hz; – Output voltage from the frequency converter – three-phase voltage up to 494 V with frequency up to 400 Hz; – Rated torque on the electric motor shaft – 63.4 N∙m; – Effective value of phase current – 100 A; – Efficiency – 96 %. In addition, the electric drive has the possibility of smooth adjustment of the motor shaft speed from 0 to 7,000 rpm. The frequency converter provides output power up to 105 kVA, has a carrier frequency of 8 kHz, withstands continuous current with an effective value of 100 A, is equipped with discrete and analogue inputs and outputs, as well as digital control interfaces Ethernet, RS-485 and CAN, and the CAN interface is high-speed and has a speed of 250 000 Baud. Starting, stopping, reversing, smooth motor speed control, overload, overheating and short-circuit protection are provided by the frequency converter. The new high-speed grinding electric motor produced by JSC “Typhoon” differs fundamentally from the one previously used on rail grinding trains in terms of weight and operating characteristics. In this connection it is required to specify its optimal modes of operation in terms of current loads, which will be determined by the force of grinding wheel pressing against the rail, provided by the appropriate pressure in the pneumatic system. Thus, the main purpose of the research was to set up a new high-speed electric drive and obtain data on its operation under conditions as close as possible to real operating modes. Research methodology Research tests of the high-speed electric drive were carried out on an experimental rail grinding unit (URSH) [15]. The URSH consists of a separate track section 100 m long, standard gauge 1,520 mm (Fig. 4, a), on which the rail grinding trolley moves (Fig. 4, b). The trolley is driven by a winch-type drive containing a motor, a gear (clutch, brake, single-reduction unit) and a single-layer coiled drum. A 200-kW diesel generator set is used as a power source. The operation of the URSH in the test mode is automatic, monitored by the control system and controlled from a personal computer. To investigate the grinding modes with the new high-speed grinding electric drive, it was mounted on the rail grinding unit URSH (Fig. 4, c, d). Fig. 3. High-speed electric motor produced by JSC “Typhoon”

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