Akira Tanaka

Universal Sensorless Vector Control of Induction and Permanent-Magnet Synchronous Motors Considering Equivalent Iron Loss Resistance

This paper presents a novel encoder-less vector control strategy which is universally applicable to both induction motors (IMs) and permanent-magnet synchronous motors (PMSMs). A fast rotor flux linkage phase estimator using stator flux linkage information obtained by a high-precision approximation voltage integral with error compensation is shown. Using this estimator, the authors construct a unified position/speed sensorless vector control algorithm taking equivalent iron loss resistance into account. All electrical motor parameters used for the control can be measured from unified off-line tests. The proposed universal sensorless vector control is implemented on a 0.4-kW squirrel-cage IM, a 0.4-kW interior PMSM with concentrated winding, and a 0.3-kW surface PMSM with distributed winding. Experimental results of several driving tests demonstrate the validity of the proposed.

Hydroxylations of trichothecene rings in the biosynthesis of Fusarium trichothecenes: evolution of alternative pathways in the nivalenol chemotype

Fusarium sporotrichioides genes FsTri11, FsTri13, and FsTri1 encode cytochrome P450 monooxygenases (CYPs) responsible for hydroxylations at C-15, C-4, and C-8 of the trichothecene skeleton, respectively. However, the corresponding genes of nivalenol (NIV)-chemotype Fusarium graminearum remain to be functionally elucidated. In this study, we characterized the roles of these CYPs in NIV biosynthesis. Analyses of the metabolites of the F. graminearum Fgtri11- mutant, a disruptant of FgTri11 encoding isotrichodermin (ITD) C-15 hydroxylase, revealed a small amount of NIV-type trichothecenes suggesting that an alternative C-15 hydroxylase partially complemented FgTRI11p. In contrast, the C-7/C-8 hydroxylations depended solely on FgTRI1p, as suggested by the metabolite profiles of the Fgtri11- Fgtri1- double gene disruptant. Disruption of FgTri1 in both the wild-type and Fgtri13- mutant backgrounds revealed that FgTRI13p exhibits marginal activity toward calonectrin (CAL) and that it was the only C-4 hydroxylase. In addition, feeding experiments demonstrated that the C-4 hydroxylation of a 7-hydroxytrichothecene lacking C-8 ketone was extremely limited. The marginal activity of FgTRI13p toward CAL was advantageous for the C-7/C-8 hydroxylation steps in NIV biosynthesis, as transformation of a C-4 oxygenated trichothecene lacking C-7/C-8 modifications into NIV-type trichothecenes was quite inefficient. The significance of hydroxylation steps in the evolution of Fusarium trichothecenes is discussed.

Universal sensorless vector control of induction and permanent magnet synchronous motors considering equivalent iron loss resistance

This paper presents a novel encoder-less vector control strategy which is universally applicable to both induction motors (IM) and permanent magnet synchronous motors (PMSM). A fast rotor flux linkage phase estimator using stator flux linkage information obtained by a high-precision approximation voltage integral with error compensation is shown. Using this estimator, the authors construct a unified position/speed sensorless vector control algorithm taking equivalent iron loss resistance into account. All electrical motor parameters used for the control can be measured from unified off-line tests. The proposed universal sensorless vector control is implemented on a 0.4 kW squirrel-cage IM and a 0.4 kW interior PMSM with concentrated winding. Experimental results of several driving tests demonstrate the validity of the proposed.

Exploring an Artificial Metabolic Route in Fusarium sporotrichioides: Production and Characterization of 7-Hydroxy T-2 Toxin

An artificial metabolic route to an unnatural trichothecene was designed by taking advantage of the broad substrate specificities of the T-2 toxin biosynthetic enzymes of Fusarium sporotrichioides. By feeding 7-hydroxyisotrichodermin, a shunt pathway metabolite of F. graminearum, to a trichodiene synthase-deficient mutant of F. sporotrichioides, 7-hydroxy T-2 toxin (1) was obtained as the final metabolite. Such an approach may have future applications in the metabolic engineering of a variety of fungal secondary metabolites. The toxicity of 7-hydroxy T-2 toxin was 10 times lower than that of T-2 toxin in HL-60 cells.

A simple method for determining equivalent circuit parameters of double-cage induction motors from no-load and locked-rotor tests

This paper presents a simple method to determine equivalent circuit parameters of double-cage Induction Motors (IM). A new formula to calculate the equivalent circuit parameters of double-cage IM is proposed. The formula is very simple so as to be able to calculate by a calculator but can determine the parameters of outer- and inner-cages bars accurately. In addition it is possible to take magnetic saturation effect of closed-slot rotor into account. Since all equivalent circuit parameters of double-cage IM can be determined only from classical no-load and locked-rotor tests, the proposed method is suitable for utilizing as a standardized testing method for double-cage IMs. The validity of the proposed method is demonstrated by experimental results on two 5.5kW-200V-4P-22A-50Hz double-cage IMs; one is an IM with semi-closed-slot rotor, the other is an IM with closed-slot rotor.

Universal sensorless vector control applicable to line-start permanent magnet synchronous motors with damper winding

This paper proposes an improved Universal Sensorless Vector (USV) control which can drive not only induction motor and damperless Permanent Magnet Synchronous Motor (PMSM) but also Line-Start PMSM with damper winding (LS-PMSM) by a unified control algorithm without a position/speed sensor. The reason why the step-out problem occurs when the conventional USV control is employed to operate the LS-PMSM is investigated and clarified. As a result, it is found that, by only adding a low pass filter to the load angle calculator to suppress the high-frequency vibration of the estimated load angle, the step-out problem is completely removed and the USV control becomes applicable to the LS-PMSM. The validity of the proposed method is demonstrated with experimental results on a 0.5-kW, 4-pole, 1500-r/min LS-PMSM.

Maximum efficiency drives of Synchronous Reluctance Motors with on-line stator resistance estimator

A maximum efficiency control of Synchronous Reluctance Motor (SynRM) using a novel on-line stator resistance estimator is presented. The proposed stator estimator entails utilizing the nature that stator resistance variation affects the accuracy of stator-flux-estimation-based inductance estimation values, but does not affect the selection of stator current vector in the maximum efficiency control system of SynRM. The proposed maximum efficiency control is implemented on a 1.1kW flux barrier type SynRM having cross-magnetic saturation effect. To correctly estimate the stator resistance and to improve the performance of the maximum efficiency control system in low speed are discussed with experimental verifications.