Low-cost Hall Effect Sensors Research Articles

Permanent Magnet Synchronous Machine Torque Estimation Using Low Cost Hall-Effect Sensors

Torque measurement/estimation in permanent magnet synchronous machines (PMSMs) is required in a large variety of applications. Direct torque measurement by means of torque transducers is typically limited to laboratory applications due to cost, reliability, and room concerns. Alternatively, torque can be estimated. Torque estimation methods require accurate knowledge of machine parameters. Injection of a high frequency (HF) signal in the stator via inverter has been shown to be a viable option for online machine parameters identification in PMSMs. However, this introduces concerns on the performance of the machine due to the noise, vibration, and additional losses produced by the HF signal. This article proposes a torque estimation method for PMSMs using low cost Hall-effect sensors. The method is based on the dependency of the leakage flux complex vector due to interaction between permanent magnet flux and stator coil flux and does not interfere with the drive operation of the machine.

Resolver Emulation for PMSMs Using Low Cost Hall-Effect Sensors

Control of permanent magnet synchronous machines (PMSMs) requires absolute rotor position measurement/estimation, as well as the magnet polarity detection for the machine start-up, encoders/resolvers being normally used for this purpose. However, these sensors can account for a large portion of the overall drive cost, and require additional room and cabling, therefore penalizing the size and reliability of the drive. This article proposes a method to emulate a resolver in machines using low cost Hall-effect sensors. The proposed Hall-effect resolver system is a new type of angular position sensor for PMSMs. This allows to control machines which do not include a resolver from inverters which require a resolver signal to operate.

Real-Time Wireless, Contactless, and Coreless Monitoring of the Current Distribution in Substation Conductors for Fault Diagnosis

Parallel conductors are found in electrical transmission and distribution systems including large ampacity feeders or loads. However, current unbalance often occurs, especially in alternating current systems. This non-regular current distribution causes overheating and premature aging, facilitating the occurrence of failures. Therefore, a fault diagnosis system is a must, which can be performed by monitoring in real time the individual currents flowing through the conductors. In this paper, a setup, including three parallel aluminum conductors of large cross-section, a spacer, and two terminal substation connectors, is analyzed. A real-time, wireless, coreless, and contactless system based on three low-cost Hall effect sensors is proposed, which is also easy to install. The experimental results, which include 14 cases comprising 13 fault modes and a well-installed set, prove the suitability and potential of the proposed approach since it allows a correct real-time detection of all analyzed faulty conditions as well as the detection of currents exceeding the thermal rating of the conductors.

Permanent Magnet Temperature Estimation in PM Synchronous Motors Using Low-Cost Hall Effect Sensors

Knowledge of the permanent magnet (PM) temperature in PM synchronous machines (PMSMs) is of great importance both for control and monitoring purposes. Increase in PM temperature during motor operation can degrade the magnetic flux strength and consequently the machine's torque production capability, and can also cause irreversible demagnetization of the PM. Direct measurement of the PM temperature is not viable in practice due to both cost and reliability issues. Indirect PM temperature estimation methods recently studied require knowledge of thermal or electrical model parameters or can have undesired effects on motor operation. In this paper, the feasibility of using low-cost Hall-effect sensors for PM temperature estimation is investigated. Hall sensors are present for detecting the initial position of the rotor in majority of PMSM applications for which incremental encoders are used for control. The proposed method can, therefore, be implemented with low or no additional cost. Experimental results on two interior PMSMs show that the method is capable of providing noninvasive estimation of the PM temperature without a priori motor parameter information for monitoring and protection against excessive increase in temperature.