1、PDF外文：http:/ Maximum Efficiency Drives of Interior Permanent Magnet Synchronous Motor Considering Iron Loss and Cross-Magnetic Saturation John B. Adawey, Shu Yamamoto, Takashi Kano, and Takahiro Ara Department of Electrical Engineering, PolytechnicUniversity, Sagamihara, Kanagawa,
2、Japan Abstract- This paper covers the proposed method to maximize the driving efficiency for interior permanent magnet synchronous motors considering iron loss and cross-magnetic saturation effects. Using a simple repetition calculation method, the proposed method automatical
3、ly determines the optimum current command in real-time. This method not only maximizes the driving efficiency but also realizes high-precision torque control performance. The validity of this method is verified from experimental results. Index Term - Iron loss, magnetic saturation,
4、 maximum efficiency drive, optimum current command, torque control performance. I. INTRODUCTION Energy conservation is the primary goal and general objective of our latest research development in the field of electrical machines and system. From the perspective view of effective and efficient
5、utilization of electrical energy, an essential technological issue to consider is to drive the machine at its maximum efficiency. Permanent Magnet Synchronous Motors (PMSM) are widely used in hybrid electronic vehicles, robotics, servo system, and other high-performance industry applicat
6、ions. Maximum efficiency drives of PMSM can be realized by the loss minimization control strategies. Loss minimization controllers of IPMSMs are roughly divided into search controllers and loss-model based controllers. The former is the search control algorithm method 1-3 where the current command v
7、ector is generated so that input power is minimized. In this method, motor constants are unnecessary but the pulsation is superimposed to the d- and q-axis currents during steady-state conditions. On the other hand, the latter which is the loss-model control method 4-9 utilizes motor constants
8、 in the generation of the current command vector. This method is superior with regard to control stability and current pulsation reduction that s why it is more often used in industrial drive systems. The latter method is generally classified into the off-line and the on-line met
9、hods. In the off-line method, the current reference signal corresponding to each speed and torque that minimizes loss is calculated beforehand, and stored in the memory table of the Digital Signal Processor (DSP) to be used for vector control. In the on-line method, the current com
10、mand vector that achieves minimum loss is automatically calculated in real time in the DSP while it carries out control operations. The off-line method has the advantage of being able to use a concise algorithm, however preparation of the table data is somewhat a time
11、-consuming effort. The on-line method s control algorithm is more complex but does not have the above-mentioned weak points of the off-line method. In the on-line method, an often employed technique for generating the current command vector is to use the minimum loss conditio
12、nal expression derived from partial differentiation of the motor electrical loss equation with respect to the d-axis current 4-6. However in some IPMSMs, the inductance change caused by cross magnetization must be considered because it is necessary to accurately evaluate motor char
13、acteristics including the efficiency. In this case, a direct derivation of the conditional expression that considers minimum loss is extremely difficult because this expression is complicated. In other approach, a method that generates d- and q-axis current commands using a s
14、earch algorithm employing the bisection method is described in 9. However, magnetic saturation and iron loss are not considered, and linearity of torque control is not achieved. Thus, this paper presents a new loss-minimization vector-control method which can b
15、e applied to IPMSM having cross-magnetic saturation effect, and improves previous methods 10-12 to achieve real-time optimum current reference signal generation considering both iron loss and cross-magnetic saturation. The proposed method generates optimum d- and q-axis current com
16、mands by employing a real-time current lead angle calculation algorithm utilizing a simple repetition calculation method. The proposed method can not only maximize the driving efficiency but also realize the high-precision and accurate torque control performanc
17、e that considers both iron loss and cross-magnetic saturation. Experimental results of maximum-efficiency control on a 0.4kW-4P-1800(r/min) IPMSM with concentrated windings demonstrate the validity of the proposed method. II. D- AND Q-AXIS INDUCTANCES OF THE TESTED MACHINE Th
18、e tested machine in this study is a concentrated-winding IPMSM (0.4-kW, 1800-min-1, 4-poles, 6-slots). Fig. 1 shows the cross section of the rotor of the tested machine. Fig. 2 shows the measured d- and q-axis inductances Ld(id, iq) and Lq(id, iq) as a function of d- and q-axis currents determ
19、ined from previous research 13. From this figure, it is clearly seen that for Lq the influence of cross-magnetic saturation is small but for Ld the tendency of the inductance to decrease as id increases in flux-weakening zone. III. MAXIMUM EFFICIENCY VECTOR CONTROL METHOD A.
20、 The Repetition Calculation Method Fig. 3 shows the equivalent circuit diagram of IPMSM, where vd and vq are the voltages, iq and iq are the currents, imd and imq are the magnetization currents, and Ld, and Lq are the d- and q-axis inductances. Ra is stator winding re
21、sistance, re is the angular velocity, and Ke is the EMF constant. To accurately evaluate loss in this circuit, the core loss resistance Rc has been introduced. In this equivalent circuit, the equation for torque is, ()d q em d m q m qT p pi i iL L K （ 1） where p is the number of pole pairs. Equation (2) expresses the relation between the current lead angle (defined in Fig. 4) and magnetization currents imd and imq. tanimd imq （ 2）
