Ni Ronggang

Analysis of 3D static temperature field of water cooling induction motor in mini electric vehicle

In this paper, the finite element model of the three-dimensional steady-state temperature field for a miniature water-cooled induction motor was established. The effective thermal conductivity was introduced to simplify the complex heat transfer process in the air gap. The heat losses of various parts of the motor were calculated, as well as the chassis water jacket heat exchange coefficient based on the similarity criterion of fluid. By three-dimensional finite element simulation, the three-dimensional steady-state temperature field distribution under rated load and the temperature field distribution under various flow rates were obtained. The simulation results showed that the highest temperature rising is located in the rotor, the temperature difference between the rotor core and the rotor bar is small, the highest temperature appears at the axial center of the motors rotor bar, the temperature rising of the stator winding is higher than that of the stator yoke, the lowest temperature rising occurs at the motor case, the change of flow rate has more effects on stator yoke and motor case, little effect on stator winding and the rotor. Under turbulent flow, the decrease of the motor temperature rising is very small with the increasing of the flow velocity. Experiments were conducted on a 34V, 4kW mini-electric-vehicle-used induction motor to measure the temperature of the stator windings, the winding ends and the stator yoke department under rated load and various flow rates. The numerical simulation results are consistent with the experimental results.

Active flux based full-order discrete-time sliding mode observer for position sensorless IPMSM drives

To improve the control performance of the position sensorless interior permanent magnet synchronous motor (IPMSM) drives, an active flux model based full-order discrete-time sliding mode observer (DT-SMO) is proposed. Bearing in mind the modeling uncertainties and external disturbances, the observer design and the stability analysis are given. To reduce the inherent chattering problem of the sliding mode control, the sigmoid function is used. To enhance the position estimation accuracy, the quadrature phase-locked loop (PLL) is adopted to track the position information form the equivalent back electromotive force (EMF) obtained through DT-SMO. Experiments on a 2.2kW sensorless IPMSM vector controlled drive have been carried out to verify the proposed scheme.

Improved model predictive control for H-bridge cascaded STATCOM

H-bridge cascaded static synchronous compensator (STATCOM) is often used to compensate the harmonic and reactive current derived from non-linear load. In order to improve the performance of STATCOM, an improved model predictive control (MPC) method is put forward in this paper. In the proposed MPC, the difference equations which are derived from the transfer functions of controlling variables and controlled variables in STATCOM are used as the predictive control model, the error between the output of STATCOM and predictive model is used to design feedback correction controller and rolling optimization controller. Meanwhile, the introduced repetitive controller is used to eliminate the inherent steady error. The actual H-bridge cascaded STATCOM is constructed and a series of verification tests are executed. The experimental results prove that the output voltage and current of H-bridge cascaded STATCOM with the proposed MPC have smaller distortion and better sinusoidal shape than those of the traditional Proportion Integral (PI) control. Moreover, the performance of H-bridge cascaded STATCOM is great in high power experiment.