Yongling Fu

Flux-Weakening Control of Nonsalient Pole PMSM Having Large Winding Inductance, Accounting for Resistive Voltage Drop and Inverter Nonlinearities

This paper proposes an improved flux-weakening control method to improve the drive performance of nonsalient pole permanent magnet synchronous motors having large winding inductance and consequently an infinite constant power speed ratio. The proposed method consists of two parts. The first part utilizes the voltage differences between the input and output of a minimum-magnitude-error over-modulation block to modify the d-axis current references. The second part uses the compensated q-axis voltage, in which the resistive voltage drop and the distorted voltage due to inverter nonlinearities are taken into account, to detect the maximum torque per voltage (MTPV) line. Under the MTPV condition, a PI controller with a low-pass filter is presented to modify the q-axis current reference. With these two parts, the bus voltage utilization in the proposed method is close to the six-step operation and the actual current trajectory approaches the ideal MTPV line. As a result, the drive performance in the whole flux-weakening region is optimized in terms of maximizing the output torque/power. The method also shows a good performance in transient response. Effectiveness and superiorities of the proposed method are verified by experimental results.

Optimization of the control strategy for EHA-VPVM system

Aiming at the problem that different sections of the flight profile have different requirements on dynamic response and energy loss, by adjusting the rotating speed in steady state and the matrix R to make the system meet the requirement is put forward. The EHA-VPVM is modeled and simulated in the Matlab/Simulink and AMESim software. The simulation results show that the dynamic response and energy loss of system are determined by rotating speed in steady-state and the weighting coefficients of the displacement and the rotating speed of pump in the matrix R. The dynamic response becomes faster as the steady-state rotating speed increases, but the energy loss becomes more. It would improve the dynamic response when reducing the weighting coefficient of displacement in matrix R appropriately.

Active disturbance rejection control for the airborne pmsm in direct drive ema application

Compared with the general ball screw electromechanical actuators (EMAs), direct drive EMAs have several attractive advantages such as more reliable, efficient, accurate, and integrated due to the elimination of the intermediate gear boxes. However, the direct drive structure brings challenges to the servo control of the permanent magnetic synchronous motors (PMSMs) which are widely used in EMAs. Aiming at improving the performance of the PMSM servo system, such as wide speed range and outstanding load disturbance-rejection ability, a novel active disturbance rejection control (ADRC) is presented in this paper. To begin with, as a technique for estimating and compensating uncertainties, characteristics, and principles of the ADRC strategy are introduced in detail by comparing with PID and several advanced control strategies. Then, based on the PMSM model in d-q frame, an ADRC controller for the d-axis current is designed to implement the rotor flux linkage oriented vector control. Finally, ADRC controllers for the position and q-axis current are designed to complete the position servo control. Simulation results verify that the ADRC-based PMSM servo system is fast, precise, of no overshoot and strongly robust to load disturbance. Therefore, the ADRC strategy is feasible in the PMSM servo control and this provides necessary technical support to the direct drive EMA, which is one of the enabling technologies for the all-electric aircraft (AEA).

Green light enhances growth, photosynthetic pigments and CO2 assimilation efficiency of lettuce as revealed by ‘knock out’ of the 480–560 nm spectral waveband

Adding green component to growth light had a profound effect on biomass accumulation in lettuce. However, conflicting views on photosynthetic efficiency of green light, which have been reported, might occur due to nonuniform light sources used in previous studies. In an attempt to reveal plausible mechanisms underlying the differential photosynthetic and developmental responses to green light, we established a new way of light treatment modeled according to the principle of gene “knock out”. Lettuce (Lactuca sativa L. var. youmaicai) was grown under two different light spectra, including a wide spectrum of light-emitting diode (LED) light (CK) and a wide spectrum LED light lacking green (480–560 nm) (LG). Total PPFD was approximately 100 µmol(photon) m−2 s−1 for each light source. As compared to lettuce grown under CK, shoot dry mass, photosynthetic pigment contents, total chlorophyll to carotenoids ratio, absorptance of PPFD, and CO2 assimilation showed a remarkable decrease under LG, although specific leaf area did not show significant difference. Furthermore, plants grown under LG showed significantly lower stomatal conductance, intercellular CO2 concentration, and transpiration compared with CK. The plants under CK exhibited significantly higher intrinsic quantum efficiency, respiration rate, saturation irradiance, and obviously lower compensation irradiance. Finally, we showed that the maximum ribulose-1,5-bisphosphate-saturated rate of carboxylation, the maximum rate of electron transport, and rate of triosephosphate utilization were significantly reduced by LG. These results highlighted the influence of green light on photosynthetic responses under the conditions used in this study. Adding green component (480–560 nm) to growth light affected biomass accumulation of lettuce in controllable environments, such as plant factory and Bioregenerative Life Support System.

The application of co-simulation based on AMESim and Matlab in electro-hydraulic servo system

The structure and operating principle of Electro-hydraulic servo system were described, and the Co-Simulation based on AMESim and Matlab was performed. Furthermore, aiming at the problem that construction of an accurate model of an Electro-hydraulic servo system based on traditional linear methods remains a difficult task due to its nonlinear characteristics including flow/pressure relation, etc, the paper proposed a data-driven control method based on the model-free adaptive control. The simulation results show that the model-free adaptive control method satisfies the performance of servo control system, and provides the electro-hydraulic servo control system with new ideas and new methods.

Research on Anti-Control of Missile Electro-Hydraulic Actuator Using Active Disturbance Rejection Control Method

Nowadays, the electro-hydraulic actuator plays an important role in some modern tactical missiles. High power, great robustness and high tracking precision are the most significant demands for the missile actuator. Therefore an advanced method of active disturbance rejection control (ADRC) is presented aiming at the dynamics of the system are highly nonlinear and have large extent of model uncertainties, such as tremendous changes in load. Firstly, a novel ADRC controller is designed for estimating and compensating disturbance based on the mathematical model of missile electro-hydraulic actuator. Then, the influence of rudder load on the system performance is analyzed in this paper. Simulation results show that the ADRC control approach can decrease the tracking error and enhance the robustness of missile electro-hydraulic actuator system when the rudder load changed tremendously. But the phenomenon of Anti-Control has disadvantageous effect on the transition period of actuator loop and evenly causes the system divergence.

Research on the controller of the digital cabin pressure regulating system based on the fuzzy gain scheduling

Based on the cabin pressure regulating system characters of the nonlinear, larger inertia and time varying parameter, the arithmetic of fuzzy gain scheduling was proposed in this paper. The control parameters can be optimized globally using the controller based on the fuzzy gain scheduling because the fuzzy inference was used to changes the parameters of the controller online to adapt the change of work point according to the output error and error change rate. When deciding the membership functions of P and I, the system response will become better in the premises of system stable if the exponent function was introduced. The simulation results show that cabin pressure and pressure rate of change meet the needs of a certain type of aircraft environmental control system specifications, and the effectiveness of the new control strategy proposed in this paper was proved.

Comparison of drive performance of PM synchronous machine fed by inverters with different PWM strategies in constant torque and constant power regions

Constant torque and constant power operation performance of permanent-magnet synchronous motors, particularly in the constant power region, not only depends on the flux-weakening control schemes but also relies on the PWM strategies. In this paper, the hysteresis control and SVPWM (including linear and over-modulation) are considered due to their popularity. An improved current regulated delta modulation (CRDM) is developed to improve the performance in both constant torque and constant power regions. The analyses, verified experimentally, show that the improved CRDM strategy demonstrates an improved torque capability which is nearly the same as SVPWM in the constant torque region, and an enlarged speed range compared with hysteresis control.

Application of heat pipe technology in the design of hydraulic motor pump

The hydraulic motor pump is a kind of new integrated hydraulic power unit, but it has a serious problem of heat dissipation when its used in closed hydraulic system and other special applications. Firstly this paper introduces the heat pipe technology into the design of the hydraulic motor pump to solve the heat dissipation problem. Afterwards we design a heat pipe radiator integrated with the back cover according to the new internal gear hydraulic pump motor. Finally we simulate the temperature field through ANSYS. The simulation results show that the heat pipe radiator can take the heat generated by the hydraulic motor pump effectively. It can greatly reduce the temperature of the oil in hydraulic motor pump and make the oil in the hydraulic motor pump at a low level. In addition it also helps reducing the temperature gradient. In conclusion, this paper demonstrates the feasibility and efficiency of heat pipe technology for heat dissipation of hydraulic motor pump.

ADR algorithm applied in electro-hydraulic servo system

Electro-hydraulic servo system due to its unique characteristics of fast response, wide range of speed, big load stiffness, strong resistance to electro-magnetic interference, large power output, light weight, etc. is applied in various industries. It is hard to build its accurate models due to nonlinear effects in order that conventional algorithms based on accurate models are ineffective to compensate disturbance. Hence, ADR (Active Disturbance Rejection) algorithm is adopted to further improve control precision of electro-hydraulic servo system, in which comprehensive disturbance instead of nonlinear effects was observed and compensated in real-time. Through simulation research by building system models with disturbance and comparing different simulation results, the parameters of ADR algorithm were tuned. Experiments with well tuned parameters of ADR algorithm were carried out to verify the validity of the algorithm on tri-axial electro-hydraulic compound flight simulator table middle-axis driven by electro-hydraulic servo system. Experimental results show that a high dynamic tracking performance is achieved based on ADR algorithm and robustness of ADR algorithm is strong. Thus, ADR algorithm can be used in practical control system.