Adriano Faggion

Predicted and measured errors in estimating rotor position by signal injection for salient-pole PM synchronous motors

The paper deals with the sensorless control of salient-pole Permanent Magnet (PM) synchronous motor drives, using a high frequency injected voltage for estimating the electrical angular position of the rotor. A high frequency speed-dependent ellipse rotating voltage vector is injected to the motor. It generates a high frequency current vector in the estimated synchronous reference frame, that contains information on actual rotor position. This type of estimation technique exploits the anisotropy of the rotor and gives an estimation that is not affected by rotor speed. A recent aspect of the topic intensively investigated is the behaviour of different rotor geometries when subjected to high frequency rotor position estimations and, consequently, the design of sensorless oriented configurations. The reasons of these studies arise from the iron saturation which occurs in the rotor and that modifies and can even cancel rotor saliency and introduces a cross coupling (cross-saturation) between d- and q-axis. This paper experiments the behaviour of two of the principal sensorless oriented rotor configurations and compare the experimental results with those predicted by the finite element simulations carried out during the motor design, in order to validate prediction tools and find out new design hints.

IPM Machine Drive Design and Tests for an Integrated Starter-Alternator Application

This paper deals with an integrated starter-alternator (ISA) drive which exhibits a high torque for the engine start, a wide constant-power speed range for the engine speedup, and a high-speed generator mode operation for electric energy generation. Peculiarities of this ISA drive are thus its flux-weakening capability and the possibility to large torque overload at low speed. The focus on the design, analysis, and test of an interior permanent-magnet motor and drive for a prototype of ISA is given in this paper. In details, this paper reports on the design of stator and rotor geometries, the results of finite-element computations, the description of control system, and the experimental results of prototype tests.

IPM Machine Drive Design and Tests for an Integrated Starter–Alternator Application

This paper deals with an integrated starter-alternator (ISA) drive which exhibits a high torque for the engine start, a wide constant-power speed range for the engine speedup, and a high-speed generator mode operation for electric energy generation. Peculiarities of this ISA drive are thus its flux-weakening capability and the possibility to large torque overload at low speed. The focus on the design, analysis, and test of an interior permanent-magnet motor and drive for a prototype of ISA is given in this paper. In details, this paper reports on the design of stator and rotor geometries, the results of finite-element computations, the description of control system, and the experimental results of prototype tests.

Sensorless Rotor Position Detection Capability of a Dual Three-Phase Fractional-Slot IPM Machine

The interest for fractional-slot permanent-magnet (PM) synchronous machines has been more and more increasing in recent years. Particularly attractive is the interior PM (IPM) machine, since it is characterized by two torque components: the PM torque and the reluctance torque. Owing to this feature, the IPM machine is able to operate under flux-weakening conditions, as required by many applications, such as automotive, machine tools, washing machines, and so on. Another feature is that the rotor position can be detected without sensor even at zero speed, by means of techniques based on high-frequency signal injection. The aim of this paper is to investigate the torque components and the sensorless position detection capability of an IPM dual three-phase machine equipped with two fractional-slot windings. These two windings are designed to be supplied by two separate converters, yielding an increase of the fault-tolerant capability of the machine. The analysis and the tests deal with the capability of the machine when it operates under healthy as well as faulty conditions, i.e., when the supply of one three-phase winding set is switched off and only one winding continues to be supplied.

Sensorless Capability of Fractional-Slot Surface-Mounted PM Motors

This paper investigates the capability of sensorless rotor position detection by means of injection of a high-frequency (HF) signal of fractional-slot surface-mounted permanent-magnet (PM) motors. In order to create an HF anisotropy, such motors are characterized by the presence of a ring around each pole. For the sake of completeness, different windings are considered: a distributed coil winding and a concentrated coil winding. The effect of eddy currents in the magnets, due to the HF signal, is also considered. The effect of the slot opening is also taken into consideration. Finally, the comparison with two different PM rotor topologies is addressed: an interior PM motor and an INSET motor.

Outer-rotor ringed-pole SPM starter-alternator suited for sensorless drives

The paper proposes a new outer-rotor configuration for an SPM starter alternator suited to be incorporated in a sensorless drive. To this aim, the rotor has a ringed-pole structure that has been already demonstrated to be adequate for zero and low speed sensorless position detection by a signal injection technique. The paper presents the machine description and modeling, the design of the sensorless drive control, predicted performance by simulations, measures on the motor, and preliminary drive performance test results.

Ringed-pole permanent magnet synchronous motor for position sensorless drives

The paper deals with a new configuration of SPM motor, in which a turn has been wound around each pole in order to modify the direct axes flux linkage dynamics while preserving the quadrature axis one, thus creating a rotor dynamic anisotropy. Consequently, the motor can be used in a position sensorless control drive which exploits the anisotropic rotor features by high frequency injected signals. In the paper, a complete description of the machine is reported together with the main equations that describes the motor dynamics. Expected drive performance is validated by simulation and experimental results.

Ringed-Pole Permanent-Magnet Synchronous Motor for Position Sensorless Drives

A new configuration of surface-mounted permanent-magnet motor in which a copper turn has been wound around each pole is investigated. The purpose is to modify the high frequency direct axis inductance, without affecting the quadrature axis one, creating a rotor high frequency anisotropy. Therefore, position sensorless control technique exploiting the anisotropic rotor features by injecting high frequency signals can be used. After describing the machine structure, the main equations dealing with the rotor dynamic anisotropy are identified. The sensorless control technique is then discussed and expected drive sensorless performance is validated by simulation and experimental results.

A ringed-pole SPM motor for sensorless drives - electromagnetic analysis, prototyping and tests

A turn wound around each pole of an SPM motor allows the direct axis flux linkage dynamics to be modified while preserving the quadrature axis one. Thus, a rotor dynamic anisotropy is created. Consequently, the motor can be used in a position sensorless control which exploits the anisotropic rotor features by high frequency injected signals. The model of the machine is described in the paper, and the main equations describing the motor dynamics are reported. Simulations, design hints and experimental results are reported so as to validate the proposed new rotor structure.

Analysis and experimental tests of the sensorless capability of a fractional-slot inset PM motor

The sensorless techniques based on high frequency signal injection to determine the rotor position is applied to an inset permanent magnet (PM) motor, whose rotor is characterized by a thin iron tooth between each couple of permanent magnet. These rotor teeth yield the rotor to be anisotropic, so as its position can be detectable. The inset PM motor considered in this paper is characterized by a fractional-slot stator, that is, by a fractional number of slots per pole and per phase. Such a solution is commonly used when a surface-mounted PM machine is considered, since it exhibits a higher torque density. A 12-slot 10-pole inset PM motor is investigated as far as its self-sensing capability. Both finite element analysis and experimental measurements are presented, showing a satisfactory agreement. It is shown that the prototype of inset PM motor available in laboratory exhibits a good capability to be controlled by sensorless techniques. However, a negative effect is recognized by a non-negligible ripple of torque and flux linkages. They impact on the dynamic performance of the PM motor drive.