Rule-based Fault Diagnosis of Hall Sensors and Fault-tolerant Control of PMSM

Hall sensor is widely used for estimating rotor phase of permanent magnet synchronous motor(PMSM). And rotor position is an essential parameter of PMSM control algorithm, hence it is very dangerous if Hall senor faults occur. But there is scarcely any research focusing on fault diagnosis and fault-tolerant control of Hall sensor used in PMSM. From this standpoint, the Hall sensor faults which may occur during the PMSM operating are theoretically analyzed. According to the analysis results, the fault diagnosis algorithm of Hall sensor, which is based on three rules, is proposed to classify the fault phenomena accurately. The rotor phase estimation algorithms, based on one or two Hall sensor(s), are initialized to engender the fault-tolerant control algorithm. The fault diagnosis algorithm can detect 60 Hall fault phenomena in total as well as all detections can be fulfilled in 1/138 rotor rotation period. The fault-tolerant control algorithm can achieve a smooth torque production which means the same control effect as normal control mode (with three Hall sensors). Finally, the PMSM bench test verifies the accuracy and rapidity of fault diagnosis and fault-tolerant control strategies. The fault diagnosis algorithm can detect all Hall sensor faults promptly and fault-tolerant control algorithm allows the PMSM to face failure conditions of one or two Hall sensor(s). In addition, the transitions between health-control and fault-tolerant control conditions are smooth without any additional noise and harshness. Proposed algorithms can deal with the Hall sensor faults of PMSM in real applications, and can be provided to realize the fault diagnosis and fault-tolerant control of PMSM.

Flash flood simulation and valve behavior of Mytilus galloprovincialis measured with Hall sensors

Mussels close their shell as a protective strategy and the quantification of this behavioral marker may represent an alarm signal when they are exposed to environmental stressors.In the present study,we investigated the ability of the Mediterranean mussel Mytilus galloprovincialis to recover and then the resilience or inertia of valve activity after a pulsing exposition to diverse levels of salinity(5,10,20,and 35 PSU as reference value).The trial simulated an event of drastic and sudden reduction of seawater salinity thus mimicking an event of flash flood from intense rain.Valve gaping and movements were measured in continuous cycle for 10 days using a customized magnetoelectric device which uses Hall sensors.Results showed that under normal conditions of salinity(35 PSU),the general pattern of valve movements was a continuously open state with sporadic spikes indicating a closing motion.At salinity of 5,PSU mussels reacted by closing their valves,leading to a 77%mortality on the 4th day.At salinity of 10,PSU animals were observed with closed valves for the entire duration of the exposure and no mortality occurred,they showed a significant reduction in the valve activity once the reference value of salinity was reestablished.In contrast,salinity of 20 PSU did not trigger a significant behavioral response.Interestingly,there no define rhythms of valve movements were recorded during salinity challenges.

Modelling and fabrication of wide temperature range Al_(0.24)Ga_(0.76)As/GaAs Hall magnetic sensors

Silicon Hall-effect sensors have been widely used in industry and research fields due to their straightforward fabrication process and CMOS compatibility.However,as their material property limitations,technicians usually implement complex CMOS circuits to improve the sensors’performance including temperature drift and offset compensation for fitting tough situation,but it is no doubt that it increases the design complexity and the sensor area.Gallium arsenide(GaAs)is a superior material of Hall-effect device because of its large mobility and stable temperature characteristics.Concerning there is no specified modelling of GaAs Hall-effect device,this paper investigated its modelling by using finite element method(FEM)software Silvaco TCAD®to help and guide GaAs Hall-effect device fabrication.The modeled sensor has been fabricated and its experimental results are in agreement with the simulation results.Comparing to our previous silicon Hall-effect sensor,the GaAs Hall-effect sensor demonstrates potential and reliable benchmark for the future Hall magnetic sensor developments.

Driving and Braking Control of PM Synchronous Motor Based on Low-resolution Hall Sensor for Battery Electric Vehicle

Resolvers are normally employed for rotor positioning in motors for electric vehicles, but resolvers are expensive and vulnerable to vibrations. Hall sensors have the advantages of low cost and high reliability, but the positioning accuracy is low. Motors with Hall sensors are typically controlled by six-step commutation algorithm, which brings high torque ripple. This paper studies the high-performance driving and braking control of the in-wheel permanent magnetic synchronous motor （PMSM） based on low-resolution Hall sensors. Field oriented control （FOC） based on Hall-effect sensors is developed to reduce the torque ripple. The positioning accuracy of the Hall sensors is improved by interpolation between two consecutive Hall signals using the estimated motor speed. The position error from the misalignment of the Hall sensors is compensated by the precise calibration of Hall transition timing. The braking control algorithms based on six-step commutation and FOC are studied. Two variants of the six-step commutation braking control, namely, half-bridge commutation and full-bridge commutation, are discussed and compared, which shows that the full-bridge commutation could better explore the potential of the back electro-motive forces （EMF）, thus can deliver higher efficiency and smaller current ripple. The FOC braking is analyzed with the phasor diagrams. At a given motor speed, the motor turns from the regenerative braking mode into the plug braking mode if the braking torque exceeds a certain limit, which is proportional to the motor speed. Tests in the dynamometer show that a smooth control could be realized by FOC driving control and the highest efficiency and the smallest current ripple could be achieved by FOC braking control, compared to six-step commutation braking control. Therefore, FOC braking is selected as the braking control algorithm for electric vehicles. The proposed research ensures a good motor control performance while maintaining low cost and high reliability.

Research of the Phase Sensitive Detection Property of Magnetic Sensor Based on Hall Effect

Aim to detect the characteristic weak magnetic field signal against the strong noises background. Methods In combination with a low-pass-filter, the correlation output of magne-* tic sensors between the magnetic field and reference current was utilized to provide a DC output voltage proportional to the applied magnetic induction, computer simulation was* done to investigate the correlation output of the Hall-effect sensors. Results Some analysis results concerning the noise property, harmonic supppression and the sensitivity were given. Conclsion The minimum detection signal of the equipment evolved from the mentioned cor-* relation theory can be 10-6 T. In addition to the DC output, such sensors can also measure the phase of the detected magnetic induction and has good harmonic suppression as well as* noise elimination.

An integrated front-end vertical hall magnetic sensor fabricated in 0.18μm low-voltage CMOS technology

An integrated front-end vertical CMOS Hall magnetic sensor is proposed for the in-plane magnetic field measure-ment.To improve the magnetic sensitivity and to obtain low offset,a fully symmetric vertical Hall device(FSVHD)has been op-timized with a minimum size design.A new four-phase spinning current modulation associated with a correlated double sampling(CDS)demodulation technique has been further applied to compensate for the offset and also to provide a linear Hall output voltage.The vertical Hall sensor chip has been manufactured in a 0.18μm low-voltage CMOS technology and it occu-pies an area of 1.54 mm2.The experimental results show in the magnetic field range from-200 to 200 mT,the entire vertical Hall sensor performs with the linearity of 99.9%and the system magnetic sensitivity of 1.22 V/T and the residual offset of 60μT.Meanwhile,it consumes 4.5 mW at a 3.3 V supply voltage.The proposed vertical Hall sensor is very suitable for the low-cost sys-tem-on-chip(SOC)implementation of 2D or 3D magnetic microsystems.

THREE-PHASE BRIDGE INVERTER FOR 9kW DOUBLY SALIENT PERMANENT MAGNET MOTOR

The three-phase bridge inverter is used as the converter topology in the power controller for a 9 kW doubly salient permanent magnet （DSPM） motor. Compared with common three-phase bridge inverters, the proposed inverter works under more complicated conditions with different principles for special winding back EMFs, position signals of hall sensors, and the given mode of switches. The ideal steady driving principles of the inverter for the motor are given. The working state with asymmetric winding back EMFs, inaccurate position signals of hall sensors, and the changing input voltage is analyzed. Finally, experimental results vertify that the given anal ysis is correct.

Research of EDM Spark Locations in Die-sinking

Detection of 2-dimention spark locations by electromagnetic detection method in electrical discharge machining (EDM) is studied. The method, which is applied and investigated, is based on the fact that the release of energy from a spark is transformed into electromagnetic wave around the workpiece. A new sensor system composed of high precision linear Hall components and cubic ferrite is used to detect the intensity of magnetic field. Relation equation between the output of the sensor system and 2-dimention spark locations experiment under a spiculate electrode is introduced, and its diagram of curve is drawn. As a result, the information that can be achieved by detecting spark’s location gives new possibilities for an extended analysis of the EDM-process.

Design of Remote Control System of Intelligent Community Based on Embedded Web Server

A multichannel remote control system for imelligent community based on the STC89C54 chip was designed with the technique of embedded Web server. The control system can monitor 255 signals and eight control signals of one node at the same time, and can be connected to the internet by the TCP/IP protocol. So the field control information can be shown dynamically in a remote computer by way of web pages. The system has high convenience and friendly monitoring interface, then especially is fit for the large conamunity and storage that need multipoint monitoring and frequent switching door.