Maximum Torque Per Ampere Strategy Research Articles

MTPA Control Method for MIDP SPMSM Drive System Using Angle Difference Controller and P&O Algorithm

This study presents a maximum torque per ampere (MTPA) control method for a mono inverter dual parallel (MIDP) surface-mounted permanent-magnet synchronous motor (SPMSM) drive system. The multimotor drive system has been extensively studied, because it can drive moreover two motors using only one inverter, reducing the costly power conversion circuit. However, existing studies concerning MIDP permanent-magnet synchronous motor drive systems focus on stabilizing the system, and studies regarding efficiency optimization are difficult to find. Some studies have shown the efficiency-optimizing method, but implementing is challenging because of the complicated calculations and algorithm. The proposed control method can achieve efficiency-optimizing operation using the angle difference controller. The angle difference controller controls the angle difference of two motors to an optimal value. Furthermore, the optimal angle difference of two motors can be easily obtained regardless of parameter errors, using the perturbation and observation algorithm. The proposed MTPA strategy is verified by performing simulations using <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">matlab</small> Simulink and applying the method to an actual MIDP SPMSM drive system.

Efficient Simplified Current Sensorless Dynamic Direct Voltage MTPA of Interior PMSM for Electric Vehicles Operation

In this paper, an energy efficiency improvement strategy is developed using a simplified current sensorless dynamic direct voltage maximum torque per ampere (MTPA) speed control method of interior permanent magnet synchronous motors (IPMSMs) for electric vehicle applications. Tracking the MTPA angle using a unique voltage amplitude without current sensing at any electric vehicle's speed yields minimum current/power consumption and high energy efficiency. These aims are achieved by considering the dynamic model of the motor that improves the controller reaction and accuracy during the transient states as contrary to the existing literature. Moreover, the simplified current sensorless dynamic direct voltage control (DDVC) technology contains a couple of control gains versus three times that with the classical MTPA Field-oriented control (FOC) method. Moreover, a comparative validation of the simplified current sensorless dynamic direct voltage MTPA methodology and the FOC strategy is executed. Experimental results with energy consumption measurements and energy efficiency study prove that the proposed simplified DDVC MTPA strategy is a promising alternative to the existing MTPA technologies of IPMSMs' drives as it preserves high energy efficiency during transient.

Maximum Torque per Ampere Strategy in IPM Drives for Electric Vehicles

Permanent magnet synchronous motors (PMSM) are known for their type whose magnets are located on the rotor surface and this motor type, which is called surface mounted magnet synchronous motors (SPM), generates torque due to the magnets mounted on the rotor. Based on torque equations, since there is only q axis current and value of magnetic flux linkage, the d axis current is kept at 0 and the torque is maximized and controlled, which is called I_d = 0 control technique. However, reluctance torque is generated in interior mounted permanent magnet synchronous motors (IPM) due to the inductance difference caused by the saliency in the rotors and by controlling the reluctance torque correctly, the efficiency of motor increases. For this reason, maximum torque per ampere (MTPA) strategy is applied in order to perform torque control efficiently in IPMs. In this study, the difference between the efficiency values was observed by simulating torque control in IPMs with the MTPA strategy instead of the conventionally used I_d = 0 control technique. As a result of the simulations, using the MTPA strategy instead of the conventional vector control technique in the drivers of the IPMs used in electric vehicle applications increases the efficiency of the system and extends drive range capacity by using the battery more efficiently.

MTPA Strategy for Direct Torque Control of Brushless DC Motor Drive

In this article, a high-performance maximum torque per Ampere (MTPA) control strategy is proposed for surface-mounted brushless dc (BLDC) motor drive. Most of published works in the literature have not considered the effect of iron loss branch. As will be demonstrated analytically, underestimating the iron loss in the control system of BLDC motor has two undesirable effects. First, it causes torque errors. Second, the MTPA fails to track the true minimum current for a desired torque. Therefore, the control system should compensate the effect of iron loss. This compensation is proposed to achieve by a direct torque control scheme to prevent internal current loops and feedforward compensations. In addition, the Lagrange's theorem is employed to derive an MTPA criterion. It is proven that forcing the criterion to zero guarantees realization of MTPA strategy. In order to reach these control objectives, a nonlinear control method is designed with two new output, corresponding to electromagnetic torque and the MTPA criterion. Performance of the proposed controller in realization of MTPA and minimization of torque ripple is justified in real-time through simulations and experiments on a 200 W outer rotor prototype.

Voltage Vector Directional Control for IPMSM Based on MTPA Strategy

Space vector pulse width modulation (SVPWM) is used in motor control because of its high dynamic response and flexible control. Maximum torque per ampere (MTPA) strategy has become the most commonly used choice for internal permanent magnet synchronous motor (IPMSM). However, complicated coordinate transformations are required in the usual SVPWM algorithm and the performance of the MTPA algorithm can be affected by the parameters variation. This paper proposes a voltage vector directional control (VVDC) method based on the MTPA strategy. The inverse Park transformation is avoided in the proposed control scheme. And the proposed algorithm not only is briefer and clearer in the sector judgment process but also has lesser calculation during the duty cycle generation. In order to realize the MTPA strategy, two voltage feedback closed loops are designed to compensate for the d -axis and q -axis currents. A simple and effective multi-parameter identification method is also presented to solve the parameters variation problem. The effectiveness of the proposed method is verified by simulation and experiments.

Machine Parameter-Independent Maximum Torque Per Ampere Control for Dual Three-Phase PMSMs

This article proposes a novel dual dc injection-based maximum torque per ampere (MTPA) control algorithm for dual three-phase permanent magnet synchronous machines (PMSMs). The proposed analytical model takes magnetic saturation and temperature effects into account for achieving optimal current angle. In taking consideration of the two effects, a set of small currents are injected in the harmonic plane rather than the fundamental subspace, namely DQ 2, which does not interfere with average torque output. In such a way, a novel torque model only involving the command currents and voltages is derived to avoid machine parameters. Furthermore, an MTPA indicator is constructed by the proposed torque to current model to seek the MTPA angle, in which the optimal current angle is found when the indicator magnitude reaches the maximum. In particular, the gradient descent algorithm is employed to ensure the adaptivity and robustness of MTPA control, which offers high real-time capability, low computational cost and low complexity. The experiments validate the proposed MTPA strategy under various load, speed and temperature conditions.

Design, Analysis and Model Predictive Control of an Axial Field Switched-Flux Permanent Magnet Machine for Electric Vehicle/Hybrid Electric Vehicle Applications

In this paper, an axial field switched-flux permanent magnet (AFSFPM) machine with stator-PM, which has a high power/torque density and efficiency feature as well as shorter axial length, is designed, analyzed and controlled. The topology, operating principle and design procedure of the AFSFPM machine are labored and discussed. The electromagnetic performance, including the flux linkage, back-EMF, cogging torque, winding inductance and field-control capability, are studied based on 3-D finite-element analysis (FEA). In order to investigate the operating performance of the machine in the whole speed range, a continuous-control-set model predictive control (MPC) method for the AFSFPM machine is proposed. Based on the stage control targets, the maximum torque per ampere (MTPA) and maximum output power flux-weakening strategies are presented in constant torque and constant power regions, respectively. Finally, a prototype of AFSFPM machine has been manufactured and experimentally evaluated and the results show that the MTPA strategy increases the load capability and the flux-weakening strategy broadens the constant power operation range. Moreover, the anti-load-disturbance capacity and dynamic response performance are improved under the MPC method. As a result, the proposed AFSFPM machine drive system is excellent alternative for electrical vehicles (EVs) or hybrid EVs (HEVs).

Experimental sensorless control for IPMSM by using integral backstepping strategy and adaptive high gain observer

In this paper a robust sensorless control for an Interior Permanent Magnet Synchronous Motor (IPMSM) is designed. The proposed control strategy uses a backstepping controller, whose robustness is improved by using integral actions added at each step of the original algorithm, and by a Maximum-Torque-Per-Ampere strategy (MTPA) to improve its energy efficient operation. Furthermore, to implement this controller in the framework of the mechanical sensorless control from the only measurements of the currents and voltages, an adaptive interconnected high gain observer is developed for estimating the rotor speed, the position and the load torque. Moreover, sufficient conditions are given to ensure the practical stability of the Observer-Controller system even if bounded uncertainties occur. Finally, the performance and the effectiveness of the designed method are tested experimentally throw a significant benchmark including different speed references and with significant robustness tests. A comparative evaluation of the computational effort of our scheme with respect to classical motor control is given.

Online MTPA Control Approach for Synchronous Reluctance Motor Drives Based on Emotional Controller

In this paper, speed and torque control modes (SCM and TCM) of synchronous reluctance motor (SynRM) drives are proposed based on emotional controllers and space vector modulation under an automatic search of the maximum-torque-per-ampere (MTPA) strategy. Furthermore, in order to achieve an MTPA strategy at any operating condition, after recognition of transient state by two new indicators, a search algorithm changes the stator flux magnitude automatically. The indicators operate based on slip effect generated at transient conditions in a SynRM with cage. The performance of the proposed controller is compared with an optimized conventional PI controller under different operating conditions. Simulation and experimental results demonstrate the benefits of the proposed approach. This structure shows superiority of the proposed method, such as fast dynamic, simple implementation and robustness to parameter variations and external disturbances in both TCM and SCM. In addition, the proposed MTPA strategy shows a reliable and fast response to operating point change.

Robust adaptive high order sliding-mode optimum controller for sensorless interior permanent magnet synchronous motors

In this paper, a robust nonlinear controller for sensorless interior permanent magnet synchronous motors (IPMSM) is designed to track a desired reference which is computed by using a maximum-torque-per-ampere strategy (MTPA). The proposed controller ensures finite-time convergence of sliding variables despite parameter uncertainties and unknown load torque. Furthermore, from the measurement of the currents and the voltages, a new analysis of the observability property is developed. Then, an adaptive interconnected observer is designed to estimate the angular velocity, the position, the load torque and the stator resistance. Using a Lyapunov approach, an analysis of the closed-loop system stability is given. Simulation results are presented to confirm the effectiveness of the proposed method.

Optimum torque sensorless HOSM controller for IPMSM via adaptive interconnected observer

In this paper, a nonlinear high order sliding mode (HOSM) controller and an adaptive interconnected observer for sensorless interior permanent magnet synchronous motors (IPMSM) are designed. A maximum-torque-per-ampere strategy (MTPA) is used to compute direct rotor current reference. The high order sliding mode controller is designed in order to ensure finite-time convergence of sliding variables and its high order time derivatives despite parameter uncertainties and unknown load torque. The adaptive interconnected observer estimates the currents, the angular velocity, the position, the load torque and the stator resistance. By Lyapunov theory, the observer-controller stability is proved. Simulation results confirm the effectiveness of the proposed method.