Abstract
A large number of permanent magnet synchronous motors (PMSMs) are used to drive coal conveyer belts in coal enterprises. Sensorless energy conservation control has important economic value for these enterprises. The key problem of sensorless energy conservation control for PMSMs is how to decompose the stator current through estimating the rotor position and speed accurately. Then a double closed loop control for stator current and speed is formed to make the stator current drive the motor as an entire torque current. In this paper, the proposed startup estimation algorithm can utilize the current model of PMSM as reference model to estimate the rotor speed and position in the startup stages. It is not dependent on the back electromotive force (EMF) which is used by the general estimation algorithm. However, the resistance will change with the temperature shift of stator windings, and these changes will cause the reference current model to be inaccurate and influence the rotor speed and position estimation precision. Thus, startup estimation algorithm switches to the proposed operation estimation algorithm which is based on the robust sliding mode theory and is not dependent on the motor parameters. The advantages of startup estimation algorithm and operation estimation algorithm are combined to form a hybrid observer. This hybrid observer realizes the accurate estimation of the rotor speed and position from start-up to operation. The stator current is precisely decomposed. The excitation current is controlled to 0. Meanwhile, the double closed-loop control of current and speed is achieved. The stator current is as entire torque current to drive motor. The closed-loop control, which is based on the proposed rotor position and speed estimation algorithm, achieve the most efficient conversion of electrical energy.
Highlights
The permanent magnet synchronous motor (PMSM) is widely applied in industrial fields, such as electric vehicles, elevators, and other high-power transmission systems [1,2] because of its high power factor and high energy density
In order to ensure the high control performance of PMSMs, a double closed loop control for stator current and speed is adopted to make the stator current drive the motor as an entire torque current
This paper proposes a startup estimation algorithm, which is based on a PMSM current model and is independent on the back-electromotive force (EMF) signal, to estimate the rotor speed and position at the startup stage
Summary
The permanent magnet synchronous motor (PMSM) is widely applied in industrial fields, such as electric vehicles, elevators, and other high-power transmission systems [1,2] because of its high power factor and high energy density. In a coal mine enterprise, are a large number of PMSMs are used to drive coal conveyer belts. With the general driven method for PMSM, the current of PMSM needs to exceed the 50% rated current to meet the torque requirement with a full load coal. 1.5 times the rated current to produce the rated torque by the normal method, and 50% of the energy is wasted. This will seriously affect the economic benefits of the coal enterprise
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