Large Phase Delay Research Articles

Phase Delays between Mouse Globus Pallidus Neurons Entrained by Common Oscillatory Drive Arise from Their Intrinsic Properties, Not Their Coupling.

A hallmark of Parkinson's disease is the appearance of correlated oscillatory discharge throughout the cortico-basal ganglia (BG) circuits. In the primate globus pallidus (GP), where the discharge of GP neurons is normally uncorrelated, pairs of GP neurons exhibit oscillatory spike correlations with a broad distribution of pairwise phase delays in experimental parkinsonism. The transition to oscillatory correlations is thought to indicate the collapse of the normally segregated information channels traversing the BG. The large phase delays are thought to reflect pathological changes in synaptic connectivity in the BG. Here we study the structure and phase delays of spike correlations measured from neurons in the mouse external GP (GPe) subjected to identical 1-100 Hz sinusoidal drive but recorded in separate experiments. First, we found that spectral modes of a GPe neuron's empirical instantaneous phase response curve (iPRC) elucidate at what phases of the oscillatory drive the GPe neuron locks when it is entrained and the distribution of phases at which it spikes when it is not. Then, we show that in this case the pairwise spike cross-correlation equals the cross-correlation function of these spike phase distributions. Finally, we show that the distribution of GPe phase delays arises from the diversity of iPRCs and is broadened when the neurons become entrained. Modeling GPe networks with realistic intranuclear connectivity demonstrates that the connectivity decorrelates GPe neurons without affecting phase delays. Thus, common oscillatory input gives rise to GPe correlations whose structure and pairwise phase delays reflect their intrinsic properties captured by their iPRCs.

O030 GABAA Receptor Expression in the Suprachiasmatic Nucleus under Different Light Conditions

Abstract Our research group has made inroads investigating the phase shifting effects of general anaesthesia (GA) on the circadian clock. Most clinical anaesthetics function by potentiating the effect of GABA on the GABA type A receptor (GABAARs). While the precise role of GABA in the suprachiasmatic nucleus (SCN) is still not fully understood, it has been implicated in circadian functions including photic entrainment and clock coupling. However, we have discovered that the expression of GABAARs in the central circadian clock remains poorly understood. To address this gap in knowledge, we examined the expression of GABAAR subunits α1, α5, β3, and γ2 in male (n = 80) and female (n = 82) C57Bl/6 mice under light-dark (LD) and constant darkness (DD) conditions (male, n = 95). Analysis of GABAAR subunit expression in the SCN was quantified by immunohistochemical analysis. Additionally, we investigated the time-dependent effects of isoflurane GA and light on GABAAR subunit expression in the SCN (male, n = 60). Our findings revealed rhythmic expression of GABAAR subunits in the mouse SCN under LD conditions which differed by sex, suggesting environmental light conditions may regulate GABAAR expression in the circadian clock in a sex-specific manner. In the SCN, γ2 subunit expression was increased following light and GA treatment compared to light-alone, while α1 subunit expression was increased at times of large behavioural phase delays. We conclude that the expression of GABAAR’s in the SCN is phase-dependent and may contribute to the time-dependent relationship between light and GA on the clock.

Speed Sensorless Control Method of Synchronous Reluctance Motor Based on Resonant Kalman Filter

When estimating the active back electromotive force (AEMF) of synchronous reluctance motor (SynRM) at medium and high speed, the traditional Kalman Filter (KF) will produce large phase delay due to the low-pass filter characteristics. A novel speed sensorless control scheme of SynRM based on resonant Kalman filter (RKF) is proposed in this paper. Firstly, the AEMF observer based on KF is designed and the bandwidth performance is analyzed. To solve the phase delay problem caused by KF, a generalized integral resonance perturbation estimator (GIRPE) is introduced to the framework of KF and the proposed RKF is formed. The estimation error of AEMF is compensated through GIRPE in the current error feedback loop of KF observer. In this way, the high-precision position estimation at high speed range is obtained. Finally, an improved dynamic position compensator (IDPC) is proposed to enhance the position estimation performance under dynamic case. The effectiveness of proposed scheme is validated at a 1.5kW SynRM drive, and the computational burden of the proposed method is assessed quantitatively.

Efficient photonics beam forming system incorporating super structure fiber Bragg grating for application in Ku band

We propose and demonstrate a photonic true-time delay beamforming system for a 1 × 4 linear phased array antenna, operating in the Ku-band, based on superstructured fiber Bragg gratings (SFBGs) with linearly rising equivalent chirps. The proposed beam-forming network operates at 18 GHz frequency, which is theoretically analyzed and simplified by simulated results. The SFBG has a distinct number of gratings in each beamforming path, which provides a large and progressive phase delay. The advantage of the proposed technique can be found in terms of its wavelength tunable scheme making the system squint-free. The proposed architecture is a true time delay optical beam forming a network, which enables squint-free beam steering of radio frequency (RF) signals. In this study, a technique known as double sideband modulation of multiple wavelengths is utilized to investigate the reflection quality of SFBG at various chirp rates. Taking into account that each segment of FBG consists of 50, 60, 70, and 80 gratings and phase shift section samples of each segment, the overall length of the SFBGs is calculated to be 2 cm, 2.4 cm, 2.8 cm, 3.2 cm, respectively, are used for calculating group delay. An equation in a closed form representing the corresponding dispersion is derived. SFBG group delay response is analyzed theoretically with required simulation to investigate the reflectance characteristics. All simulation work for designing the beam forming system is done on Optisystem version 19 and designing of Super structure fiber Bragg grating Optigrating version 4.2. The optically process wavelengths are detected by high speed dedicated photo-detector (PD) and delay response is investigated through array factor of each antenna. Errors in the fabricated SFBGs' group delay responses are examined also.

0314 Late Evening Room Light and Sleep Restriction Reverses the Phase Advancing Effect of Bright Morning Light in Adolescents

Abstract Introduction Late bedtimes and sleep restriction are common during adolescence, particularly on school nights. We examined circadian phase advancing effects of bright morning light (ML) with increasing doses of evening room light exposure and sleep restriction due to late bedtimes. Methods Adolescents (n=38, 21 girls) aged 14.1 to 18.0 years completed a 14-day protocol during summer vacation. On days 1-7, they slept at home on individualized 10-h sleep/dark schedules. On days 8-14, they lived in the laboratory. On day 8, we measured their Dim Light Melatonin Onset (DLMO). On days 9 and 10, they were put to bed 1.5h (n=9), 3.0h (n=12), or 4.5h (n=8) later and kept awake in room light (104±11 lux at the angle of gaze). Wake time was unchanged; thus, sleep opportunity was shortened to 8.5h, 7h, and 5.5h, respectively. The fourth group (n=9) kept their baseline bedtime, were not exposed to any additional evening light (EL) and were not sleep restricted. On day 11, all groups were put to bed and awakened 1.5 h earlier and were exposed to intermittent bright ML (three 30-min exposures; 8599±885 lux). On each subsequent day (12 and 13), sleep and ML were advanced 1h. Thus, there were 3 days of a gradually advancing sleep schedule and bright ML. Final DLMO was measured on day 14. Results The 0h EL group showed a large DLMO advance (2.2±1.0 h), but the advance was reduced in the 1.5h EL group (0.5±0.6 h). DLMO delayed in the 3h EL group (-0.9±1.1 h). There was a large phase delay in the 4.5h EL group (-2.6±1.2 h). Phase shifts differed among all groups [F(3,34)=36.7, p<.001]. Conclusion Circadian rhythms of adolescents were advanced when they were exposed to bright ML and a gradually advancing sleep schedule, as shown in many studies of adults. However, when kept up later in ordinary room light, the same advancing sleep schedule and bright ML did not produce as much of an advance. Phase delay shifts occurred when bedtimes were 3h or 4.5h later. EL and sleep restriction can reverse the advancing effect of bright ML. Support (if any) R01 HL146772 (Crowley)

An ultrathin acoustic metasurface composed of an anisotropic three-component resonator

An ultrathin acoustic metasurface consisting of an anisotropic three-component resonator is proposed. The resonator can induce nondegenerate dipole resonances at the same resonant frequencies. A large phase delay can be obtained based on the resonance, which can be modulated by the direction of polarization. The anisotropic resonator can be regarded as an effective homogenous medium with an anisotropic mass density, and the phase change can also be attributed to the change of the effective material parameters. A good comparison between the results for the metasurface and its effective slab is obtained.

Improved hydrodynamic pulsation models for the pulsating extreme helium star V652 Herculis

ABSTRACT New non-linear hydrodynamic models have been constructed to simulate the radial pulsations observed in the extreme helium star V652 Her. These use a finer zoning to allow higher radial resolution than in previous simulations. Models incorporate updated OPAL and OP opacity tables and adopt a composition based on the best atmospheric analyses to date. Key pulsation properties including period, velocity amplitude, and shock acceleration are examined as a function of the mean stellar parameters (mass, luminosity, and effective temperature). The new models confirm that, for large amplitude pulsations, a strong shock develops at minimum radius, and is associated with a large phase delay between maximum brightness and minimum radius. Using the observed pulsation period to constrain parameter space in one dimension, other pulsation properties are used to constrain the model space further, and to critically discuss observational measurements. Similar models may be useful for the interpretation of other blue large amplitude pulsators, which may also exhibit pulsation-driven shocks.

The Effects of General Anaesthesia and Light on Behavioural Rhythms and GABAA Receptor Subunit Expression in the Mouse SCN

General anaesthesia (GA) is known to affect the circadian clock. However, the mechanisms that underlie GA-induced shifting of the clock are less well understood. Activation of γ-aminobutyric acid (GABA)-type A receptors (GABAAR) in the suprachiasmatic nucleus (SCN) can phase shift the clock and thus GABA and its receptors represent a putative pathway via which GA exerts its effect on the clock. Here, we investigated the concurrent effects of the inhalational anaesthetic, isoflurane, and light, on mouse behavioural locomotor rhythms and on α1, β3, and γ2 GABAAR subunit expression in the SCN of the mouse brain. Behavioural phase shifts elicited by exposure of mice to four hours of GA (2% isoflurane) and light (400 lux) (n = 60) were determined by recording running wheel activity rhythms in constant conditions (DD). Full phase response curves for the effects of GA + light on behavioural rhythms show that phase shifts persist in anaesthetized mice exposed to light. Daily variation was detected in all three GABAAR subunits in LD 12:12. The γ2 subunit expression was significantly increased following GA in DD (compared to light alone) at times of large behavioural phase delays. We conclude that the phase shifting effect of light on the mouse clock is not blocked by GA administration, and that γ2 may potentially be involved in the phase shifting effect of GA on the clock. Further analysis of GABAAR subunit expression in the SCN will be necessary to confirm its role.

Investigation of the Kerr effect on polarised light

A constructed Kerr cell with brass electrodes and liquid nitrobenzene was used for studying the Kerr effect on polarised light. Laser light was plane polarised and passed through an energised Kerr cell. The plane polarised light after travelling a path length equal to the cell electrode length in a birefringent medium, suffered optical retardance before passing through an analyser which then transmitted light of certain intensity to a photodiode. Data used were generated from experiments and theoretical considerations using Kerr’s law and Malus’ law. With crossed Polaroids, the Kerr cell behaved as an electro-optic shutter and the maximum light intensity transmitted rose steadily with increased phase difference to about 0.82. With parallel Polaroids, the maximum light intensity transmitted was higher and found to be 0.89 at zero phase difference. This value indicates a large phase delay and decreased to a non-zero value. At maximum electric field intensity, a ‘climbing’ of the nitrobenzene on the Kerr cell walls and electrodes was observed with more nitrobenzene attracted to the anode. The effect suspected to be of electrostatic origin may have been driven by the predominant ions in the nitrobenzene. Furthermore, the higher level of the nitrobenzene meniscus at the anode probably suggests that while the cathode injected carriers of negative charge into the liquid the injection of carriers from the anode was weaker. For better results, attention should be given to Polaroid quality, the purity of the liquid nitrobenzene and the length of the electrodes used.

In situ near-field microwave characterization and quantitative evaluation of phase change inclusion in honeycomb composites

Inclusions are common threats for honeycomb composites. Conventional non-destructive testing (NDT) methods mainly focused on inclusions in a specific phase state, while little attention has been paid to phase change inclusions under different service conditions. Herein, we conducted in situ detections of a phase change paraffin inclusion in honeycomb sandwich panels at different temperatures with a near-field microwave method. The scanning amplitude and phase images of subwavelength core cells and inclusions were obtained with super-resolution. The paraffin inclusion (melting point, 58°C) was characterized with a large amplitude decrease and phase delay in both the solid and liquid phases. Besides, the liquid paraffin inclusion at 100°C presented a whole shift of amplitude increase and phase decrease relative to the solid phase at 20°C. The boundaries of the phase change inclusion were accurately characterized using a characteristic peak method (CPM) with relative errors less than 0.5%. In summary, the near-field microwave method is feasible and effective for super-resolution detection and quantitative evaluation of phase change inclusions under varied service conditions.

Light Has Diverse Spatiotemporal Molecular Changes in the Mouse Suprachiasmatic Nucleus.

To be physiologically relevant, the period of the central circadian pacemaker, located in the suprachiasmatic nucleus (SCN), has to match the solar day in a process known as circadian photoentrainment. However, little is known about the spatiotemporal molecular changes that occur in the SCN in response to light. In this study, we sought to systematically characterize the circadian and light effects on activity-dependent markers of transcriptional (cFos), translational (pS6), and epigenetic (pH3) activities in the mouse SCN. To investigate circadian versus light influences on these molecular responses, we harvested brains from adult wild-type mice in darkness at different circadian times (CT) or from mice exposed to a 15-min light pulse at the middle of the subjective day (CT6, no phase shifts), early subjective night (CT14, large phase delays), or late subjective night (CT22, small phase advances). We found that cFos and pS6 exhibited rhythmic circadian expression in the SCN with distinct spatial rhythms, whereas pH3 expression was undetectable at all circadian phases. cFos rhythms were largely limited to the SCN shell, whereas pS6 rhythms encompassed the entire SCN. pH3, pS6, and cFos showed gating in response to light; however, we were surprised to find that the expression levels of these markers were not higher at phases when larger phase shifts are observed behaviorally (CT14 versus CT22). We then used animals lacking melanopsin (melanopsin knockout [MKO]), which show deficits in phase delays, to further investigate whether changes in these molecular markers correspond to behavioral phase shifts. Surprisingly, only pS6 showed deficits in MKOs at CT14. Therefore, our previous understanding of the molecular pathways that lead to circadian photoentrainment needs to be revised.

Human circadian phase-response curves for exercise.

Key points Exercise elicits circadian phase‐shifting effects, but additional information is needed.The phase–response curve describing the magnitude and direction of circadian rhythm phase shifts, depending on the time of the zeigeber (time cue) stimulus, is the most fundamental chronobiological tool for alleviating circadian misalignment and related morbidity.Fifty‐one older and 48 young adults followed a circadian rhythms measurement protocol for up to 5.5 days, and performed 1 h of moderate treadmill exercise for 3 consecutive days at one of eight times of the day/night.Temporal changes in the phase of 6‐sulphatoxymelatonin (aMT6s) were measured from evening onset, cosine acrophase, morning offset and duration of excretion. Significant phase–response curves were established for aMT6 onset and acrophase with large phase delays from 7:00 pm to 10:00 pm and large phase advances at both 7:00 am and from 1:00 pm to 4:00 pm. Delays or advances would be desired, for example, for adjustment to westward or eastward air travel, respectively.Along with known synergism with bright light, the above PRCs with a second phase advance region (afternoon) could support both practical and clinical applications. Although bright light is regarded as the primary circadian zeitgeber, its limitations support exploring alternative zeitgebers. Exercise elicits significant circadian phase‐shifting effects, but fundamental information regarding these effects is needed. The primary aim of the present study was to establish phase–response curves (PRCs) documenting the size and direction of phase shifts in relation to the circadian time of exercise. Aerobically fit older (n = 51; 59–75 years) and young adults (n = 48; 18–30 years) followed a 90 min laboratory ultrashort sleep–wake cycle (60 min wake/30 min sleep) for up to 5½ days. At the same clock time on three consecutive days, each participant performed 60 min of moderate treadmill exercise (65–75% of heart rate reserve) at one of eight times of day/night. To describe PRCs, phase shifts were measured for the cosine‐fitted acrophase of urinary 6‐sulphatoxymelatonin (aMT6s), as well as for the evening rise, morning decline and change in duration of aMT6s excretion. Significant PRCs were found for aMT6s acrophase, onset and duration, with peak phase advances corresponding to clock times of 7:00 am and from 1:00 pm to 4:00 pm, delays from 7:00 pm to 10:00 pm, and minimal shifts around 4:00 pm and 2:00 am. There were no significant age or sex differences. The amplitudes of the aMT6s onset and acrophase PRCs are comparable to expectations for bright light of equal duration. The phase advance to afternoon exercise and the exercise‐induced PRC for change in aMT6s duration are novel findings. The results support further research exploring additive phase‐shifting effects of bright light and exercise and health benefits.

Entrainment of the Circadian Clock of the Enteric Bacterium <i>Klebsiella aerogenes</i> by Temperature Cycles

We have previously shown that the gastrointestinal bacterium, Klebsiella (nee Enterobacter) aerogenes, expresses an endogenously generated and temperature-compensated circadian rhythm in swarming motility and gene expression. As a human gastrointestinal commensal, we hypothesized that this circadian rhythm may be synchronized/entrained in vivo by the daily rhythm in body temperature (TB). Cultures of K. aerogenes transformed to express a plasmid containing luxCDABE with a MotA promoter exhibited rhythms in bioluminescence and in spatial distribution on the culture dish with a circadian period (τ). To determine entrainment, cultures were exposed to temperature cycles of 1o (35oC-36oC) or 3oC (34oC-37oC) in amplitude and cycles with varying periods (T cycles) of T=22 hours, T=24 hours, or T=28 hours. Bacteria entrained to all 3 T cycles at both temperature amplitudes with stable phase relationships (Ψ) to the Zeitgebers. To better understand the nature of this entrainment, a phase response curve (PRC) was constructed in response to 1 hr. pulses of 3oC increase in temperature (34oC-37oC) at different circadian phases (Φ) of the bioluminescence rhythm. A very high amplitude PRC, with small phase shifts (ΔΦ) during subjective day, large phase delays (-ΔΦ) during early subjective night, and large phase advances (+ΔΦ) during late subjective night was constructed, explaining the entrainment patterns of these bacteria. A phase transition curve (PTC) revealed a Type 0 PRC. To determine whether spatial patterns of bioluminescence rhythms contributed to the overall circadian organization of K. aerogenes, cultures were imaged for 2.5 days in a cooled CCD camera system, revealing a spatiotemporal pattern the circadian rhythmicity. These data are consistent with the hypothesis that the K. aerogenes circadian clock entrains to its host via detection of and phase-shifting to the daily pattern of TB.

Explaining negative refraction without negative refractive indices.

Negative refraction through a triangular prism may be explained without assigning a negative refractive index to the prism by using array theory. For the case of a beam incident upon the wedge, the array theory accurately predicts the beam transmission angle through the prism and provides an estimate of the frequency interval at which negative refraction occurs. The hypotenuse of the prism has a staircase shape because it is built of cubic unit cells. The large phase delay imparted by each unit cell, combined with the staircase shape of the hypotenuse, creates the necessary conditions for negative refraction. Full-wave simulations using the finite-difference time-domain method show that array theory accurately predicts the beam transmission angle.

A Nonadaptive Window-Based PLL for Single-Phase Applications

The rectangular window filter, typically known as the moving average filter (MAF), is a quasi-ideal low-pass filter that has found wide application in designing advanced single-phase phase-locked loops (PLLs). Most often, the MAF is employed as an in-loop filter within the control loop of the single-phase PLL. The in-loop MAF, however, causes a large phase delay and, hence, makes the PLL dynamic response slow. Recently, using MAFs as a prefilter/quadrature signal generator (QSG) before the PLL input has been suggested. As the MAFs are outside the PLL control loop, the problem of slow dynamic response is avoided. Nevertheless, the PLL implementation complexity considerably increases as MAFs are frequency-adaptive and, therefore, they require an additional frequency detector for estimating the grid frequency. To reduce the implementation complexity while maintaining a good performance, using a nonadaptive MAF-based QSG with some error compensators is suggested in this letter. The effectiveness of the resultant PLL, which is briefly called the nonadaptive MAF-based PLL, is verified using experimental results.

On-Demand Aerodynamics in Integrally Actuated Membranes with Feedback Control

This paper is a numerical investigation on model reduction and control system design of integrally actuated membrane wings. A high-fidelity electroaeromechanical model is used for the simulation of the dynamic fluid–structure interaction between a low-Reynolds-number flow and a dielectric elastomeric wing. Two reduced-order models with different levels of complexity are then derived. They are based on the projection of the full-order discretization of fluid and structure on modal shapes obtained from eigenvalue analysis and proper orthogonal decomposition. The low-order systems are then used for the design of proportional–integral–derivative and linear–quadratic–Gaussian feedback schemes to control wing lift. When implemented in the full-order model, closed-loop dynamics are in very good agreement with the reduced-order model for both tracking and gust rejection, demonstrating the suitability of the approach. The control laws selected in this work were found to be effective only for low-frequency disturbances due to the large phase delay introduced by the fluid convective time scales, but results demonstrate the potential for the aerodynamic control of membrane wings in outdoor flight using dielectric elastomers.

Circadian rhythms of European and African-Americans after a large delay of sleep as in jet lag and night work.

Jet travel and night shift work produce large changes in when people sleep, work and eat; a challenge that was not encountered during most of our evolution. Successful adaptation would require the internal, master, circadian clock to make large phase shifts to reduce the circadian misalignment between circadian rhythms and the times for sleep, work and meals. We compared African-Americans and non-Hispanic European-Americans in how much their circadian clocks shifted after a 9 hour phase delay of the light/dark, sleep/wake and meal schedule, which has similarities to flying west or sleeping in the daytime after night shifts. We also measured their free-running circadian periods using a forced desynchrony protocol with a 5-h day. European-Americans had longer free-running periods and larger phase delays than African-Americans. Correlations (among all subjects, just African-Americans and just European-Americans) showed that longer circadian periods were associated with larger phase delays. Larger phase delays, facilitated by longer circadian periods, reduce jet lag after westward travel and make it easier to work night shifts and sleep during the daytime after night work. On the other hand, a shorter circadian period, which makes one more of a morning-type person, is better for most people given our early-bird dominated society.

Phase imaging using focused polycapillary optics

Conventional radiographic techniques depend on attenuation, which provides low contrast between soft tissues. However, X rays can accumulate large differential phase delays even in weakly absorbing materials. This can produce significantly higher contrast. One technique for taking advantage of phase effects, propagation-based phase imaging, can yield marked edge enhancement but requires spatially coherent intense sources. Microfocus sources have sizes on the order of tens of microns but necessarily are low power and hence require long exposures. In this project, X-ray optical and computational techniques were explored to develop both edge-enhancement and phase imaging using a large spot conventional source. A polycapillary optic was employed to create a small secondary source from a large spot rotating anode X-ray generator. The secondary spot created by the focusing polycapillary optic was 114 µm ± 50 µm. Images of a 1.6 mm polyethylene rod were taken at varying distances from the optic. Edge enhancement was observed with a maximum edge-enhancement-to-noise ratio of 6.5. Insect images were also acquired and analyzed. Phase reconstructions were computed using two different approaches, weak attenuation and phase attenuation duality. Pure phase images were successfully reconstructed from the phase contrast images by employing the weak attenuation model.

Dual Metamaterial With Large Birefringence

Strong birefringence and a large phase delay are highly desirable for high-efficiency and compact wave plates. In order to enhance the phase delay, we combine a semiconductor metamaterial (SMM) and split-ring resonators (SRRs) into a novel dual metamaterial, which exhibits two types of resonance response, i.e., one type is mainly induced by the SMM for one polarization component of the incident wave, and the other is mainly induced by the SRRs for the other orthogonal polarization component. The unique resonance characteristics lead to large birefringence and, hence, a considerable phase delay, enabling the realization of a very compact quarter-wave plate in the middle-infrared spectrum. The concept of the dual metamaterial has the potential for developing ultracompact high-performance microoptical/nanooptical components.

Sensorless Drive for High-Speed Brushless DC Motor Based on the Virtual Neutral Voltage

The brushless dc (BLDC) motor can be driven by either pulse-width modulation (PWM) or pulse-amplitude modulation (PAM) techniques. Unfortunately, neither of them can be the most suitable method for the high-speed BLDC motor in the wide speed range, so a hybrid drive method combining PWM and PAM is first introduced. Then, this paper proposes a new sensorless control method based on the virtual neutral voltage for high-speed BLDC motor to suit for this hybrid drive method. In order to obtain the commutation signals from this seriously unclear voltage signal due to the commutation notches and electromagnetic interference, a low-pass filter with super low cutoff frequency is employed at the price of a large phase delay. Meanwhile, a novel sensorless control method based on the transition between “90–α” and “150–α” is introduced to handle the severe phase delay. At last, the feasibility and effectiveness of the proposed drive method and the sensorless control method are verified by several experiment results.