Current derivative measurement using closed-loop Hall-effect current sensor

This paper discusses a method of the current derivative measurement using a standard closed-loop Hall-effect current sensor. The proposed method can operate with PWM-driven inverters and provides the estimation of motor-phase inductances required for an encoderless or self-sensing control. The method is based on the current transformation feature of the closed-loop sensor where a sensing inductor is connected in series with the measuring resistor. The voltage drop across the inductor is proportional to the current derivative. The experimental results are demonstrated that the measurement of the current derivative can be performed under a good accuracy, though the measurement should be executed while inverter is in the steady-state condition

Direct measurement of current derivative using a delta-sigma modulator for Sensorless Traction Motor Control

This paper discusses a new method of direct measurement of the current derivative applied to determine an electric motor inductance required for efficient and reliable control of sensorless AC electric drives. The method is based on the measurement of the voltage drop across a calibrated inductor implemented into the power circuit of the motor drive inverter. In order to increase accuracy and reduce transients and oscillations the measured voltage drop is processed using a delta-sigma modulator. The data stream generated by the modulator is then transferred to a microcontroller supported demodulation for further processing and filtering. The paper also presents the results of experimental investigations of three different shunt inductors. The results demonstrate a high accuracy and noise immunity of the proposed method

Real-time model of synchronous reluctance motor drive for laboratory based investigations

The Synchronous Reluctance Motor has received much attention in recent years as a very promising solution for electric drives in the near future. This paper presents a real-time model of the motor to be implemented into a software environment used for DSP control system development including debugging. The model is used in laboratory based investigations in academia in order to analyse the performance of electric drives based on a synchronous reluctance motor

A PWM Strategy for the Minimisation of Losses in a 3-level T-type Voltage Source Inverter

This paper discusses the approach for the witching loss minimisation in a 3-level inverter. It utilises a model predictive method which is used for evaluation of both the switching loss and voltage unbalance. The method is based on the cost functions implemented to provide simultaneous minimisation of loss and DC link voltage balance control. The simulation results shown that the total loss is reduced in 15% compared to a standard PWM strategy for a 3-level inverter operating at PWM frequency of 16 kHz

A method of determining the maximum performance torque-speed characteristic for an induction motor drive over its entire speed range

This paper discusses a simple and efficient method of determining the maximum performance torque-speed characteristic for an induction motor drive. The proposed method considers the voltage and current constraints of the inverter supply for the drive. The mathematical description of the motor in DQ reference frames was adapted to build a model applicable for numeric calculation. It has been shown that the torque-speed characteristic has 3 operating speed regions. The optimal relationship between the magnetisation and q-axis currents is derived for the third speed region. The model performs tracking of the magnetisation current in order to keep the output voltage and current under the limits of the inverter. In addition, the proposed model provides a method of calculation for the output power, the apparent power, the power factor and the efficiency vs speed. The proposed method is applicable for the analysis of the induction motor drive operating over its entire speed range

Comprehensive Peripheral Blood Immunoprofiling Reveals Five Immunotypes With Immunotherapy Response Characteristics in Patients With Cancer

The lack of comprehensive diagnostics and consensus analytical models for evaluating the status of a patient\u27s immune system has hindered a wider adoption of immunoprofiling for treatment monitoring and response prediction in cancer patients. To address this unmet need, we developed an immunoprofiling platform that uses multiparameter flow cytometry to characterize immune cell heterogeneity in the peripheral blood of healthy donors and patients with advanced cancers. Using unsupervised clustering, we identified five immunotypes with unique distributions of different cell types and gene expression profiles. An independent analysis of 17,800 open-source transcriptomes with the same approach corroborated these findings. Continuous immunotype-based signature scores were developed to correlate systemic immunity with patient responses to different cancer treatments, including immunotherapy, prognostically and predictively. Our approach and findings illustrate the potential utility of a simple blood test as a flexible tool for stratifying cancer patients into therapy response groups based on systemic immunoprofiling

Optimized Method for Speed Estimation Using Incremental Encoder

International Symposium on Power Electronics (Ee) (2017, Novi Sad, Serbia

Minimization and redistribution of switching losses using predictive PWM strategy in a voltage source inverter

International Workshop on Electric Drives: Optimization in Control of Electric Drives, IWED 2018 (25th. 2018. Rusia