On-line minimum loss control strategy of IPMSM in torque-controlled application

An electrical losses (copper and iron losses) minimization control of interior permanent magnet synchronous motors is proposed in this paper. Until now a Look-up Table based maximum torque per armature current control strategy was proposed by authors. That is a control to minimize copper losses. Meanwhile, the efficiency deteriorates as a result that the iron losses increase sharply in high speed area. In this paper, a model considering iron losses is discussed and the relationship between the electrical losses and d-q axes current, motor torque, motor speed is clarified at first. Next, measurement experiments are made to prove that there is an optimal armature current phase which minimize the electrical losses for given motor speed and load torque. Then, an online loss minimization algorithm with steepest descent method (golden section method) is proposed. The electrical losses in i <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> = 0 control and loss minimization control are compared with experiment results. The effectiveness of the proposed control is verified by experiments.

This paper presents the experimental evaluation of a flux linkage-based inverter loss model embedded in a deadbeat-direct torque and flux control (DB-DTFC) that achieves desired torque and minimizes losses over each switching period. The optimal flux commands are selected from those that will achieve the desired torque by using embedded dynamic flux linkage-based loss models of the machine and inverter. The proposed inverter loss model is implemented in real-time on a flux weakening interior permanent magnet synchronous machine (FW-IPMSM) test bench and evaluated experimentally. The actual inverter losses are obtained by measuring the electrical power at three different points in the test bench. In order to evaluate the loss model, comparative evaluation of the actual inverter losses versus the estimated losses have been performed under both constant stator flux and dynamic flux trajectories. Finally, losses resulting from using different widely used loss minimizing control strategies are compared.

High-efficiency electric drive systems claim not only optimally designed electric machines but also efficiency-oriented control strategies. Taking machines and drives into synergetic consideration, this paper proposes a fresh particle crowd optimisation (FPCO) of efficiency-oriented control algorithm named maximum outer torque per ampere (MOPA) control and maximum efficiency per ampere (MEPA) control, aiming to maximise the efficiency of interior permanent magnet synchronous machines during operation. Difference from conventional id = 0 or maximum torque per ampere control, MOPA and MEPA fully consider the cross effect core loss, iron loss, supplementary loss and mechanical loss, from which the full-order loss model of interior permanent magnet synchronous motor (IPMSM) is built. In order to identify the accuracy of the efficiency-oriented control algorithm, the efficiency-oriented controlled system on based FPCO using non-singular terminal sliding (NTS) controller is built, on the base of this, the stabilisation of the current trajectory and the voltage vector from simulation and testing are inspected. After that, the higher effectiveness of MOPA and MEPA is proved through the operation experiment of IPMSM of which capacity is 82 kW.

In this paper, loss minimization control method of IPMSM based on approximate calculation is proposed. Firstly, according to the IPMSM mathematical model considering the equivalent iron loss, the loss minimization extreme value is solved by Lagrange equation, and the electromagnetic current variable is eliminated by the equivalent transformation method. Secondly, the relation of dq axis current is obtained by defining the virtual current. Considering the existence of the square term in the relation, a new approximate calculation method is proposed to eliminate the square term of the given current and obtain the dq axis current with the minimum loss. Finally, in order to further prove the performance of the proposed method, [Formula: see text] control, virtual current control method and torque approximation control method are analyzed and compared in MATLAB/SIMULINK. Simulation results show that the proposed control method is more perfect than the traditional virtual current method and has higher accuracy than the traditional approximate calculation method. Compared with the traditional three control methods, the total loss is reduced by 7.44% at least under rated working conditions.

In this paper, a linear torque control strategy is first proposed for interior permanent magnet synchronous motor drives to fully utilize the reluctance torque and simplify the controller design. The proposed linear torque control strategy also extends the existing maximum torque per ampere control in the constant torque limit region up to the entire field-weakening region. It is found that in an intermediate speed region, called partial field-weakening region, the existing maximum torque per ampere control can still be applied under lighter load condition. In addition, the proposed control can also achieve the objective of minimum copper loss (i.e., maximum torque per ampere) for the entire speed range. Sound theoretical basis is given in the context. Moreover, an adaptive limiter is proposed for efficiently implementing the proposed control strategy over the entire speed range. Finally, a prototype is also constructed by using a fixed-point DSP TMS320F240 and some experimental results are given to verify the validity of the proposed control strategy.

Three types of 1.5 kW wheel-in-IPMSMs (interior permanent magnet synchronous motors) with minor modifications have been manufactured in trial for one-person ride micro-mover use, aiming at easiness in use and high efficiency in applications. Their characteristics have been evaluated comparatively based on the d-q equivalent circuits in which the variable iron loss resistance is particularly taken into account by defining an expression as an approximate function of rotating speed, r.m.s. current and its leading angle. A series of measurement of machine parameters including inductances and iron loss resistance has been carried out to compare the motors quantitatively in detail each other. It has been proved that the proposed procedures are effective for precise comparative evaluation taking the iron loss effect into account.

In order to improve the performance, efficiency and reliability of the interior permanent magnet synchronous motor (IPMSM) drive, a set of control strategies are developed for wide speed range operation. A rotor flux oriented vector control with model reference adaptive system (MRAS) based rotor position/speed estimation is employed as the basic control strategy for IPMSM drive. A control strategy named maximum torque per ampere (MTPA) is applied to minimize the motor current magnitude during low speed operation. While an over-modulation method is employed to enhance the voltage transfer ratio of PWM inverter and the output torque capability of IPMSM during high speed operation, and flux weakening control is developed for high speed stable operation of IPMSM drive. Furthermore, phase current reconstruction under overmodulation is taken into account, which lowers the system cost and expands the working range of PWM inverter fed IPMSM motor drives. The issue of seamless switching from MTPA during low speed range to conventional field-weakening control during high speed range is also discussed. Simulation and experimental results demonstrate the feasibility and effectiveness of these control strategies, which realizes the high performance operation of IPMSM drive in wide speed range.

The interior permanent magnet synchronous motors (IPMSMs) are extensively applied in the field of new energy vehicles due to their high-power density and excellent performance control. However, the iron loss has a significant impact on their performance. This study conducts an optimization analysis on the processing technology of silicon steel sheets and motor structure, targeting the reduction of iron loss and the improvement of the motor’s integrated efficiency. Firstly, the influences of two iron core processing technologies on iron loss, namely gluing and welding, are compared. Through experimental tests, it is found that the iron loss density of the gluing process is lower than that of the welding process, and as the magnetic flux density increases, the difference between the two is expanding. Therefore, the iron loss test data from the adhesive process are employed to develop a variable-coefficient iron loss model, enabling precise calculation of the motor’s iron loss. On this basis, aiming at the problem of excessive iron loss of the motor, a novel topological structure of the stator and rotor is proposed. With the optimization goal of reducing the motor iron loss and taking the connection port of the air magnetic isolation slot and the gap of the stator module as the optimization variables, the optimized design of the IPMSM with low iron loss is achieved based on the Taguchi method. After optimization, the stator iron loss decreases by 13.60%, the rotor iron loss decreases by 20.14%, and the total iron loss is reduced by 15.34%. The optimization scheme takes into account both the electromagnetic performance and the process feasibility, it offers technical backing for the high-efficiency operation of new energy vehicle drive motors.

This paper investigates the iron loss and torque characteristics of inverter-fed spoke type interior permanent magnet synchronous motor (IPMSM) optimized for sinusoidal distributed back-EMF. First of all, an optimal design procedure is introduced to effectively optimize the rotor pole surface to reduce the distortion of back-EMF in the spoke type IPMSM. Then, the finite element method (FEM) results for our optimized model and a circuit/control simulator for vector control are linked to analyze the nonlinearity of the motor and the control property of the motor drive.

Nowadays doubly fed induction generator (DFIG) is the mainly used generator in wind power generation, and several efforts are being made to tackle the issues related to their high production costs. In order to solve this problem, this work presents an optimized control strategy that seeks to mitigate the electrical losses inside the generator. The control strategy is based on the optimal reactive power sharing between the rotor and stator circuits of the generator connected to a back-to-back power electronic converter (PEC). In this paper the iron losses, which are traditionally ignored in machine models and vector controls, are considered to achieve better performance. Moreover, since the loss minimisation strategy requires different converter operation points, a numerical model for calculating the semiconductor power losses is shown to evaluate whether this strategy compromises the system losses. Simulation results for a 7.5 kW DFIG show the amount of power saved when the loss minimisation control is applied.

Vacuum cleaner motors need to be capable of providing high power and high efficiency during high-speed (e.g. 50,000 r/min) operations. Because of this, interior permanent magnet synchronous motors (IPMSM), while highly efficient under general operating conditions, are not normally considered suitable for use in vacuum cleaners because of their tendency to suffer from severe iron loss during high speed operations. These losses have a severe negative impact on motor efficiency. In this research, we examine efforts to reduce iron loss during high-speed IPMSM operations. It is expected that the iron loss of slotless IPMSM operating at high speeds can be greatly decreased because there are no teeth in the area where the magnetic flux density is high. Performance comparisons between slotless IPMSM and conventional IPMSM (which utilize distributed windings) are then performed.

This paper presents a new method by using the Artificial Neural Networks (ANNs) for estimating the parameters of the machine which achieving the optimal efficiency of the Synchronous Reluctance Motor (SynRM). This model take into consideration the magnetic saturation, cross-coupling and iron losses. With Finite Element Analysis (FEA), the characteristics of the SynRM including inductances and iron loss resistance are determined. Because of the non-linear characteristics, an ANN is trained to obtain the d-q inductances and the iron loss resistance from Id, Iq currents and rotor speed. After learning process, an analytical expression of the optimal currents is given thanks to Lagrange optimization. Therefore, the optimal currents will be obtained online in real time. This method can be achieved with maximum efficiency and high-precision torque control. Simulation and experimental results are presented to confirm the validity of the proposed method.

This paper proposes a high-precision mathematical modeling scheme for interior permanent magnet synchronous motors (IPMSMs), which gives full consideration to the saturation and cross-coupling influence based on the finite element analysis (FEA). Firstly, the IPMSM model is built in ANSYS/Maxwell to acquire the variable stator inductance and flux linkage parameters under various kinds of working conditions. Secondly, the obtained d-axis inductance, q-axis inductance, and rotor flux linkage are further calculated, processed, and pre-stored in three two-dimensional (2-D) look- up-tables (LUTs). Thirdly, the IPMSM model is built in MATLAB/Simulink based on three established tables. Finally, by looking up the three tables according to the real-time d-axis and q-axis currents, the IPMSM system can be simulated under different working conditions for various control methods. With the developed high-precision FEA-based mathematical modeling scheme, the simulation results will be more accurate and the simulation process will be more efficient with significant time savings and better dynamic performance. To validate the effectiveness of the proposed modeling scheme, a Space Vector Pulse Width Modulation (SVPWM) control system with maximum torque per ampere (MTPA) and flux-weakening (FW) control as well as feed-forward decoupling control is built based on a 15kW IPMSM prototype.

This paper develops a genetic-PI based controller for interior permanent magnet synchronous motor (IPMSM) drive. An artificial neural network (ANN) is used for on-line tuning of the PI controller. Genetic algorithm (GA) has been used in this work in order to obtain the optimized values of the PI controller parameters for precise speed control under different operating conditions over wide speed range. The performance index which has been utilized as GA objective function is zero steady-state error, minimum speed deviation, and minimum settling time of the IPMSM drive. The optimal behavior of drive can be achieved by considering two control strategics: maximum torque per ampere (MTPA) control strategy in constant torque region and flux-weakening control strategy in constant power region. In developing the proposed controller, the PI controller parameters are optimized by GA at all operating conditions, in a closed loop vector control scheme. By obtaining the parameters at a number of points in the possible operating region, a look-up table approach has been completed. Then an ANN is trained by this look-up table. Ultimately, the well-trained ANN is utilized for on-line tuning of the PI controller parameters to ensure optimum drive performance under different disturbances and operating conditions over wide speed range.

[abstFig src='/00280005/03.jpg' width='300' text='Speed impact on minimum total loss control' ] Increasing motor operating efficiency potentially reduces energy consumption and radiator requirements. In some applications, the motor’s operating efficiency may even be the most important factor to be considered. The model-based minimum total loss control (MTLC) we proposed could potentially improve motor efficiency by taking copper and iron loss into account based on the motor model, finding the minimum power point, and enabling the permanent magnet synchronous motor achieve optimal efficiency at different speeds. Copper loss under MTLC increased less than the maximum torque per ampere (MTPA), but iron loss under MTLC was much lower than MTPA, reducing total loss. MTLC reduced total loss by adjusting the relation between copper and iron loss using a demagnetization current. Analysis and simulation results show that our proposal improved the efficiency of the permanent magnet synchronous motor effectively, making it easy to implement in practical control with little calculation.