High-Speed BLDC Motors Research Articles

High speed BLDC motor for grid tied PV based EV system using hybrid PSO-spotted hyena optimized PI controller

High speed BLDC motor for grid tied PV based EV system using hybrid PSO-spotted hyena optimized PI controller

Badania przyczyn niepożądanej synchronizacji prędkości obrotowej silnika z częstotliwością modulacji PWM w układzie napędowym PM BLDC

In a drive system comprising a high-speed PM BLDC motor and an inverter implementing motor phases commutation and phase voltages PWM modulation, a spontaneous synchronisation between the PWM modulation frequency and the motor rotational speed may occur. The drive behaves like an unintended phase-locked loop. The effect distorts mechanical characteristic of the drive by introducing flat segments where the rotational speed remains constant despite changing load torque. It makes the speed-torque relationship discontinuous, nonlinear, and non-unique. The phenomenon is closely related to the problem of phase current and motor torque ripples. The paper presents experimental results recorded with a laboratory test bench for drives for electric power tools where the phenomenon of the parasitic speed locking has been observed. A root cause of this effect is discussed, and the mechanism of unwanted synchronisation is investigated. Several mitigation techniques are proposed and verified with computer simulations.

Analysis of losses in the high-speed PM BLDC motor with open slot stator core made of amorphous soft magnetic material

PurposeThe purpose of this paper is to verify results related to losses in the core of a brushless DC prototype motor, obtained using its computer FE models, by experimental tests on manufactured machines. The paper focuses on the comparison of losses in the core of a machine with a classical stator core made of an iron–silicon material (Fe–Si) and a new one made of a modern METGLAS material.Design/methodology/approachComputer models of the prototype motors were created using FEM. The designed machines were manufactured, and experimental tests were performed. To achieve high frequencies in rotating magnetic fields, motors with a stator to rotor pole ratio of 9/12 were built. Twin rotor approach was applied, as two identical rotors were built along the two geometrically identical stators made of different core materials.FindingsExperimental studies have shown the superiority of the METGLAS material over the classical Fe–Si material. Material parameters were measured directly on the prepared cores as library data used in the simulation may be incorrect due to technological processes during core production, which was also verified. Problems related to twin rotor approach have been identified. Solution to the problem has been suggested. Necessity of 3D FEM modelling was identified.Originality/valueThe main source of originality is that METGLAS material used in the prototype machines was developed and manufactured by the authors themselves. Original approach to core parameter evaluation based on simplified methodology has been suggested. Another original part is a simplified methodology applied to loss measurement during no-load test.

Variable speed reference control of a high‐speed BLDC motor for a blender machine

This study presents the design of a 2-pole high-speed BLDC motor for kitchen blenders and its control method with the aim to reduce the speed ripple that decreases the grinding performance in the high-speed region. In blender machines, the high pulsating load caused by the blending materials such as ice cubes acting on the grinding blade, create significant speed ripple in the constant power region. Because current and torque are limited to protect the drive, the actual motor torque cannot overcome the pulsated load if the speed reference is maintained. Therefore, the speed fluctuates, and the grinding performance is lowered. In the proposed variable speed reference control scheme, the speed command is continuously modified to overcome the maximum pulsating torque requirement which results in lower speed ripple. To achieve this, if the load torque suddenly increases, the current value is then set based on the maximum load and speed reference value is temporarily lowered. If then the load torque becomes lower than the actual torque, the previously set speed reference value is reused. The design result and grinding performance of the proposed control method are verified by simulations and experiments. Hard white beans are used for actual performance testing.

Safety Operation Area of Zero-Crossing Detection-Based Sensorless High-Speed BLDC Motor Drives

In the high-speed brushless dc drives, long commutation freewheeling duration will increase the difficulty of sensorless operation that is based on the back electromotive force (EMF) zero-crossing detection. In extreme cases when the freewheeling angle exceeds 30°, the zero crossing of back EMF will be undetectable, resulting in the failure of sensorless drives. As a result, the sensorless safety operation area (SOA) is limited by the long freewheeling angle issue. In this article, it is found that the pulsewidth modulation (PWM) patterns have a big influence on the freewheeling angle. Hence, in the first place, through analytical methods, the mechanism that how different PWM techniques affect the freewheeling angle is investigated. The PWM pattern resulting in a minimum freewheeling angle is identified. Furthermore, a method to predict the SOA is developed, which provides a theoretical way to verify whether the predesigned torque and speed area can be achieved with the given motor parameters. Finally, the theoretical analysis is verified by the simulation and experimental results.

Reduction of Rotor Harmonic Eddy-Current Loss of High-Speed PM BLDC Motors by Using a Split-Phase Winding Method

Low-order harmonic currents in high-speed permanent magnet brushless dc (PM BLDC) motors cause large rotor eddy-current loss, resulting in high temperature rise and even overheating in the rotors, thus their application in the field of high-speed drive is limited. The rotor eddy-current loss can be reduced by using a split-phase winding method. In this paper, various time–space orders of harmonic eddy-current losses in the rotors of the PM motors with and without split-phase winding are quantified. The calculated results indicate that the rotor harmonic eddy-current losses generated by the low-order harmonic currents, which inherently exist in PM BLDC motors, are greatly reduced. Furthermore, associated with the characteristics of harmonic currents of PM BLDC motors, the mechanism of drastically reducing the rotor harmonic eddy-current loss of high-speed PM motors by using the split-phase winding method is revealed and experimentally validated.

A Sensorless Commutation Error Correction Method for High-Speed BLDC Motors Based on Phase Current Integration

Inaccurate commutation in brushless dc motor (BLDCM) will induce current harmonic and increase motor loss, which reduce motor efficiency. Meanwhile, for the sensorless BLDCM, the motor commutation is seriously affected by detection errors and calculation errors, which are caused by the nonideal conditions and the parameters variation. In this paper, a novel commutation error correction method is proposed to determine optimal commutation instant for the sensorless high-speed BLDCM. First, the relationship between commutation error and motor phase current is analyzed. According to this relationship, an initial commutation error can be calculated and compensated in one conduction interval. Then, online commutation corrections are performed to compensate for the residual error in following conduction intervals. The correction accuracy of commutation instant is determined by the phase current integral difference. This method is insensitive to motor parameters and back electromotive force waveform. Therefore, the commutation error is effectively eliminated in the whole speed range. Finally, the feasibility and effectiveness of the proposed method are evaluated by experimental results.

A Lag Angle Compensation Strategy of Phase Current for High-Speed BLDC Motors

For brushless dc motor operating at ideal commutation point, the angle of the phase current vector will lag behind that of the back electromotive force (EMF) vector due to the motor phase inductance. The lag angle increases the root-mean-square (rms) value of phase current under a certain average torque output, which results in more heat and less efficiency, especially at high rotational velocity. The principle that the angle of ideal current vector is equal to that of the back EMF vector at the center of a conduction sector is analyzed. A novel advance compensation method for commutation point is proposed based on the principle. The advance angle is calculated in real time according to the phase current, the inductance, and the flux linkage established by the magnet of the motor. By conducting the voltage vector of voltage source inverter before the ideal commutation point in advance, the lag of the phase current would be eliminated. Thereby, the rms value of the phase current is reduced. Finally, both simulation and experiments verify the effectiveness of the proposed method.

Sensorless High-Precision Position Correction Strategy for a 100 kW@20 000 r/min BLDC Motor With Low Stator Inductance

This paper focuses on the sensorless high-precision position correction strategy for a 100 kW@20 000 r/min brushless dc (BLdc) motor with low stator inductance (0.051 mH). Two key points related to the sensorless were studied. The one is the rotor position detection with high-frequency interference. The other one is the commutation compensation for the high-speed BLdc motor with low stator inductance in whole speed range. In order to filter out the high-frequency interference, the main factors, which that can influence the rotor position detection and the commutation accuracy were analyzed. In order to compensate the commutation error in high-precision and whole speed range, the relationship between the commutation error angle and the phase current deviation was derived. It is noted that the commutation time and the phase current error can exactly reflect the commutation error angle. Then, a novel sensorless high-precision position correction strategy based on the uncommutation current was proposed. Finally, the experiment platform based on a 100 kW@20 000 r/min BLdc motor was built, and the validity and efficiency of the proposed strategy were proved.

공극 비대칭에 따른 고속 단상 BLDC 전동기 설계

본 논문은 단상 전동기의 단점인 효율 및 기동특성을 고려하여 청소기에 적합한 고속 단상 BLDC(Brushless DC) 전동기의 설계를 목표로 한다. 단상 BLDC 전동기의 필수 조건인 기동토크 발생을 위해 비대칭 공극을 적용하였다. 무 부하 조건에서 비대칭 비율 정도에 따른 단상 BLDC 전동기의 코깅 토크와 역기전력의 크기 변화와 위상 차이를 분석하였다. 실제 부하 조건에서 단상 BLDC 전동기의 효율을 확인하기 위하여 단상 풀브릿지 인버터의 진상각 제어를 사용하였으며, 비대칭 비율과 진상각 크기에 따른 효율 특성의 비교를 통해 최적 모델을 선정하였다. 본 논문에서는 비대칭 비율에 따른 역기전력 위상 차이가 단상 BLDC 전동기에 미치는 영향을 시뮬레이션을 통해 분석하고, 청소기의 부하 조건에서 효율을 극대화할 수 있도록 고속 단상 BLDC 전동기를 설계하였다.

High-Precision Sensorless Drive for High-Speed BLDC Motors Based on the Virtual Third Harmonic Back-EMF

In order to improve the performance of the high-speed brushless direct current motor drives, a novel high-precision sensorless drive has been developed. It is well known that the inevitable voltage pulses, which are generated during the commutation periods, will impact the rotor position detecting accuracy, and further impact the performance of the overall sensorless drive, especially in the higher speed range or under the heavier load conditions. For this reason, the active compensation method based on the virtual third harmonic back electromotive force incorporating the SFF-SOGI-PLL (synchronic-frequency filter incorporating the second-order generalized integrator based phase-locked loop) is proposed to precise detect the commutation points for sensorless drive. An experimental driveline system used for testing the electrical performance of the developed magnetically suspended motor is built. The mathematical analysis and the comparable experimental results have been shown to validate the effectiveness of the proposed sensorless drive algorithm.

High-Speed BLDC Motor Design for Suction Fan and Impact on the Loss caused by Core Welding

This paper deals with the effects of welding, which is done to fix the stator stack, on a motor in case of fabricating a prototype motor that is manufactured in a small quantity. In the case of a small motor, the stator is designed and fabricated with the segmented core as a way to raise the fill factor of winding wire to the utmost within a limited size. In case of fabrication by welding both inside and outside of the stator in order to fix the segmented-core stator, the effects of stack are ignored, and the eddy current loss occurs. This paper performed the no-load test on an IPM-type BLDC motor for driving the suction fan of a vacuum cleaner, which was manufactured by using a segmented-core stator. As a result of the test, it was found that input power more than expected was supplied. To analyze the effects of welding by using the finite element analysis method and verify them experimentally, a stator was re-manufactured by bonding, and input power supplied during the no-load test was compared.

Self-Correction of Commutation Point for High-Speed Sensorless BLDC Motor With Low Inductance and Nonideal Back EMF

This paper presents a novel self-correction method of commutation point for high-speed sensorless brushless dc motors with low inductance and nonideal back electromotive force (EMF) in order to achieve low steady-state loss of magnetically suspended control moment gyro. The commutation point before correction is obtained by detecting the phase of EMF zero-crossing point and then delaying 30 electrical degrees. Since the speed variation is small between adjacent commutation points, the difference of the nonenergized phase's terminal voltage between the beginning and the end of commutation is mainly related to the commutation error. A novel control method based on model-free adaptive control is proposed, and the delay degree is corrected by the controller in real time. Both the simulation and experimental results show that the proposed correction method can achieve ideal commutation effect within the entire operating speed range.

Implementation of a MFAC based position sensorless drive for high speed BLDC motors with nonideal back EMF

In order to improve the reliability and reduce power consumption of the high speed BLDC motor system, this paper presents a model free adaptive control (MFAC) based position sensorless drive with only a dc-link current sensor. The initial commutation points are obtained by detecting the phase of EMF zero-crossing point and then delaying 30 electrical degrees. According to the commutation error caused by the low pass filter (LPF) and other factors, the relationship between commutation error angle and dc-link current is analyzed, a corresponding MFAC based control method is proposed, and the commutation error can be corrected by the controller in real time. Both the simulation and experimental results show that the proposed correction method can achieve ideal commutation effect within the entire operating speed range.

Position Sensorless Control Without Phase Shifter for High-Speed BLDC Motors With Low Inductance and Nonideal Back EMF

This paper presents a novel method for position sensorless control of high-speed brushless DC motors with low inductance and nonideal back electromotive force (EMF) in order to improve the reliability of the motor system of a magnetically suspended control moment gyro for space application. The commutation angle error of the traditional line-to-line voltage zero-crossing points detection method is analyzed. Based on the characteristics measurement of the nonideal back EMF, a two-stage commutation error compensation method is proposed to achieve the high-reliable and high-accurate commutation in the operating speed region of the proposed sensorless control process. The commutation angle error is compensated by the transformative line voltages, the hysteresis comparators, and the appropriate design of the low-pass filters in the low-speed and high-speed region, respectively. High-precision commutations are achieved especially in the high-speed region to decrease the motor loss in steady state. The simulated and experimental results show that the proposed method can achieve an effective compensation effect in the whole operating speed region.

A Novel Speed Measurement Method for a High-Speed BLDC Motor Based on the Signals From the Rotor Position Sensor

The paper presents a digital algorithm of a speed control block for a dc brushless motor and a method for measuring the motor's rotational speed based on the signals from the rotor's position sensor. The proposed method allows an increase in the measurement frequency (six measurements per rotation for a two-pole motor or 12 measurements for a four-pole motor) and the measurement results are not affected by the misalignment mounting of the sensor. The paper describes a conceptual structure of a series PI controller.

Bezczujnikowe sterowanie silnika wysokoobrotowego PM BLDC przy pomocy metody bazującej na napięciach międzyfazowych

The paper presents a sensorless control method based on phase-to-phase voltages of a high-speed PM BLDC motor. In addition, the paper compares this method with other sensorless control methods considering the possibilities of implementation in a high-speed motor. In particular, also highlighted the possibility of implementation depending on the commutation angle. (Sensorless control of high-speed PM BLDC motor using method based on phase-to-phase voltages).

Core Loss Calculation in Step Magnetic of High-Speed Motor Stator

According to the reduction for efficiency of high-speed permanent magnet brushless DC motor (High-speed PM BLDC motor) by core loss of stator in the design process, the accurate calculation for stator core loss is very important.2-D finite element method is used to analyze the alternating magnetic field and magnetic field of the stator core of which a rotational speed of 27000rpm high-speed BLDC motor. Harmonic analysis is used for the step magnetic field of high-speed BLDC motor, Based on the model of Bertotti iron loss calculation, superposition of various frequency loss will be calculated, the calculation accuracy was validate to increase.

Design and Analysis of a High-Speed Brushless DC Motor for Centrifugal Compressor

This paper describes the design and analysis of a high-speed and high-power density BLDC motor for a 50-kW, 70 000-rpm class centrifugal compressor. Design criteria and power loss analysis of the high-speed machine structure are described by analytical method, and the results are validated by finite element method. And then, the prototype machine has been fabricated and tested. The experimental results confirmed the validity of the proposed design and analysis scheme of the high-speed BLDC motor

Study of Retaining Sleeve and Conductive Shield and Their Influence on Rotor Loss in High-Speed PM BLDC Motors

Rotor eddy-current loss is usually significant in high-speed permanent magnet brushless dc (PM BLDC) motors. On the other hand, the rotor is usually protected with a nonmagnetic retaining sleeve. The influence of the conductivity of the retaining sleeve on the rotor eddy-current loss is analyzed in this paper. Furthermore, utility of a conductive copper shield between the sleeve and magnets is demonstrated. Although eddy current is induced in the copper shield, causing additional loss, its magnetic field can smooth the varying field in the rotor and reduce the overall eddy-current loss dramatically. The relationship between the thickness of copper shield and the rotor eddy-current loss is also examined