Francesco Parasiliti

Adaptive sliding mode observer for speed sensorless control of induction motors

This paper presents an adaptive sliding mode observer for speed sensorless field-oriented control of induction motors. The observer detects the rotor flux components in the two-phase stationary reference frame by the motor electrical equations. The motor speed is identified by an additional relation obtained by a Lyapunov function. The analytical development of the sliding observer and the speed identification algorithm is fully explained. Experimental results are presented, based on a TMS320F240 DSP controller implementation, showing the system performance with different observer gains and the influence of the motor parameters deviations.

Initial rotor position estimation method for PM motors

This paper presents a method to detect the rotor position of PM motors at standstill. It is suitable to avoid temporary reverse rotation or starting failure. The basic approach is the well-known method to estimate the rotor position by using the inductance variation as a function of the magnets position and the stator currents: a suitable sequence of voltage pulses is applied to the stator windings and the evaluation of the peak value of the current leads to the rotor position estimation. Actually, the current measurements show significant uncertainties which affect the rotor detection. In order to avoid these problems, the authors propose a novel procedure which combines an iterative sequence of voltage pulses with a fuzzy logic processing of the current responses and phase currents derivation based on the DC link current measurements. The proposed method has been implemented on a /spl mu/C DSP (TMS320F240). The obtained results confirm the effectiveness of the proposed solution. It is consistent with sensorless or nonabsolute position transducers drives, a wide range of motors and it does not require the knowledge of any of the motor parameters.

Real-time gain tuning of PI controllers for high-performance PMSM drives

In this paper, a new and practical real-time gain-tuning method for proportional plus integral (PI) controllers has been formulated and implemented, using the speed control of a permanent-magnet synchronous motor drive system as a testbed. While the novel strategy enhances the performance of traditional PI controller greatly and proves to be a completely model-free approach, it also preserves the simple structure and features of PI controllers. The essential idea is as follows: (1) according to the system dynamics to step variation, define a performance index to evaluate the system response; (2) based on the monotonous relationship between the performance index and an intermediate PI gain parameter, this latter parameter is estimated with a modified binary search algorithm in order to improve the performance index; and (3) finally, PI gains are calculated and renewed according to the estimated intermediate gain parameter. Experiments have been thoroughly carried out to test the proposed method under different conditions. Besides being simple and easy to implement for real-time applications, the proposed method also possesses features such as versatility, stability, and effectiveness.

Finite-Element-Based Multiobjective Design Optimization Procedure of Interior Permanent Magnet Synchronous Motors for Wide Constant-Power Region Operation

This paper proposes the design optimization procedure of three-phase interior permanent magnet (IPM) synchronous motors with minimum weight, maximum power output, and suitability for wide constant-power region operation. The particular rotor geometry of the IPM synchronous motor and the presence of several variables and constraints make the design problem very complicated. The authors propose to combine an accurate finite-element analysis with a multiobjective optimization procedure using a new algorithm belonging to the class of controlled random search algorithms. The optimization procedure has been employed to design two IPM motors for industrial application and a city electrical scooter. A prototype has been realized and tested. The comparison between the predicted and measured performances shows the reliability of the simulation results and the effectiveness, versatility, and robustness of the proposed procedure.

Multiobjective optimization techniques for the design of induction motors

This paper deals with the optimization problem of induction motor design. In order to tackle all the conflicting goals that define the problem, the use of multiobjective optimization is investigated. The numerical results show that the approach is viable.

Sensorless speed control of a PM synchronous motor by sliding mode observer

This paper presents a sensorless speed control of a permanent magnet synchronous motor using a sliding mode observer. A vector control strategy is considered, for a motor with sinusoidal flux distribution. The sliding mode observer detects the voltages induced by the magnet flux on the stator windings. These signals are used to calculate the rotor position and speed needed for vector control. Due to the sliding mode operation, filters are used to smooth the estimated variables. A speed-dependent compensation is also proposed, in order to achieve an accurate estimation of the rotor position. As the observed variables are not available below a limit frequency, an open loop starting procedure is implemented. The resulting observer has been fully analyzed by simulations, in order to test the performance both in steady-state and transient operations. Experimental results based on a DSP TMS320C50 controller are presented, showing the performance of the sensorless drive over a wide range of operating conditions.

Sensorless speed control of a PM synchronous motor based on sliding mode observer and extended Kalman filter

In this paper a method for rotor speed and position detection in permanent magnet synchronous motors is presented, suitable for applications where low speed and standstill operations are not required. The approach is based on the estimation of the motor back-EMF through a sliding mode observer and a cascaded Kalman filtering. Due to its characteristics, the technique can be applied to motors having distorted and whatever shaped back-EMF waveform. The equation error for the rotor position estimation is derived and discussed. Test results are presented, which show the system performance including start-up capability, which is one of the most critical conditions in back-EMF based sensorless schemes.

Low cost phase current sensing in DSP based AC drives

This paper presents the implementation of two techniques for phase current sensing based on a low cost last generation /spl mu/C DSP (TMS320F24x). The first one is based on the measurement of the current flowing in a shunt resistor put in the DC bus of the inverter, the second one is based on the measurement of the current flowing in shunt resistors put in series to the emitter of the IGBT for each lower leg of the inverter. The information provided by these sensors, together with the pulse width modulation (PWM) information, is used to reconstruct the motor phase currents. After a description of the two methods and the limitations they present, an application in case of an induction motor drive is illustrated in which the adjacent vector-space vector pulse width modulation (AV-SVPWM) technique is used to drive the inverter. Some aspects involving the non ideal behaviour of different parts of the system (presence of dead time, power switches driver delay, rise and settling time of the current, A/D conversion module sampling time) are investigated in details and the specific hardware implementation is discussed. Experimental results and comparisons between the two methods are presented.

Sensorless speed control of salient rotor PM synchronous motor based on high frequency signal injection and Kalman filter

The paper presents an approach to sensorless speed control of a salient rotor permanent magnet synchronous motor, based on a high frequency signal injection scheme improved by the use of Kalman filtering. The rotor position estimation error signal is extracted from both the d- and q-axis components of the high frequency current in the estimated rotor position reference frame. Then it is processed by a Kalman filter which yields position and speed estimates, based on a parameter independent mechanical model. The problem of carrier recovery is addressed and a simple but effective solution is presented and analysed. Realistic simulations accounting for the inaccuracy of the digital implementation are presented and discussed.

A comparative study of rotor flux estimation in induction motors with a nonlinear observer and the extended Kalman filter

The paper presents a comparison of performances and characteristics of a nonlinear observer and observation algorithms based on the Kalman filter for induction motor rotor flux estimation, inserted in a field oriented control scheme. The construction of the considered algorithms is described in detail, and the different design issues are explained. For fair comparison the same measurements are assumed available to both deterministic and stochastic estimators, and the same controller parameters are used in simulation. The performances of the estimators are compared either in terms of observation errors during transient and steady state operations either in terms of computational complexity in on-line implementation.<<ETX>>