Problems with controlling the torque of induction motor, considering the use of this drive in order to control the hydraulic drive power unit parameters (with constant displacement pump). In analyzed system, a Direct Torque Control method (DTC) and fuzzy PI type controller were used. Inverter-fed drive system with 2,2 kW ac motor was subjected to laboratory tests.
ANALYSIS OF THE DTC METHOD APPLIED TO PRESSURE AND FLOW CONTROL IN A HYDRAULIC SYSTEM
Problems of induction motor torque control were analyzed, taking into account the use of this drive to control the parameters of a hydraulic power unit with a fixed displacement pump. In the analyzed system, a Direct Torque Control (DTC) method and a fuzzy PI-type controller were used. Laboratory tests were performed on a drive system with a 2.2 kW motor powered by a voltage inverter.
1. INTRODUCTION
Controlling the torque or force of a hydraulic system requires using a control element that enables changing the working fluid pressure. This element is usually a pressure reducing or overflow valve. Throttling control systems are characterized by low efficiency, which limits their range of application to low-power applications. Particularly low efficiency is a feature of systems with a serial location of the throttling element. In all these cases, energy loss occurs, which increases the operating costs of the hydraulic system.
There are unique correlations (nearly proportional) between the force of the actuator piston rod or the torque of the hydraulic motor shaft and the pressure. These relations can be used for the appropriate control of the electric motor torque driving the constant displacement pump. (…)
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