Sensorless Control Scheme Research Articles

A Single-Stage Sensorless Control of a PV-Based Bore-Well Submersible BLDC Motor

Permanent magnet (PM) brushless dc (BLDC) motor-based photovoltaic water pumps are becoming popular in rural areas due to their higher efficiency and reliability compared to induction motor-based pumps. The water table level in these rural areas is typically more than 15 m. Hence, deep bore-well submersible motors are used for extracting potable water from the water table. The motor and controller are submerged in the water table, and have more temperature rise due to the poor ambience. Thus, control of a PM BLDC motor with hall-effect-based position sensors is unreliable in these environments due to the temperature sensitivity of the hall-effect sensors. In this paper, a single-stage sensorless control of a deep bore-well submersible ferrite PM BLDC motor drive is presented. A position sensorless control scheme is implemented to eliminate the use of hall sensors, thus improving reliability of the overall system. Furthermore, the challenges involved in the control of a deep bore-well submersible ferrite PM BLDC motor are elaborated. The prototype of a 1.5-kW submersible BLDC motor drive is fabricated and the experimental results are presented.

Improved rotor flux observer for sensorless control of PMSM with adaptive harmonic elimination and phase compensation

In this paper, a sensorless control strategy of a permanent magnet synchronous machine (PMSM) based on an improved rotor flux observer (IFO) is proposed. Due to the unknown integral initial value and the high harmonics caused by current sampling and inverter nonlinearities, the flux linkage estimated by traditional rotor flux observer may be inaccurate. In order to address these issues, a self-adaptive band-pass filter (SABPF) is designed to eliminate the DC component and high-frequency harmonics of the estimated equivalent rotor flux linkage. Furthermore, in order to avoid that the design of PI parameter is influenced by the amplitude of equivalent rotor flux linkage, an improved phase-locked loop (IPLL) is employed to obtain the rotor speed and to normalize the estimated equivalent rotor flux linkage. In addition, angle shift caused by an SABPF is compensated to improve the accuracy of the estimated flux linkage angle. Besides, the parameter robustness of this method is analyzed in detail. Finally, simulation and experimental results demonstrate the effectiveness and parameter robustness of the proposed method.

Sensorless control strategy of cooler for reduction dimensions and operating characteristic improvement in double three-phase inverter

The paper deals with the construction design, thermal simulation analysis and cooler control proposal of double three-phase inverter suitable for electric vehicles. It gives a discussion on basic mechanical design and electric topology, both having strong influence on electrothermal operability. The paper also presents the thermal analyses of the converter operated at specified loading profile and gives control possibilities. Finally, the paper presents the cooler control design and demonstrates its functionality. The paper also discusses its impact on the converter lifetime and implementation.

Force Sensorless Admittance Control With Neural Learning for Robots With Actuator Saturation

In this paper, we present a sensorless admittance control scheme for robotic manipulators to interact with unknown environments in the presence of actuator saturation. The external environment is defined as linear models with unknown dynamics. Using admittance control, the robotic manipulator is controlled to be compliant with external torque from the environment. The external torque acted on the end-effector is estimated by using a disturbance observer based on generalized momentum. The model uncertainties are solved by using radial basis neural networks (NNs). To guarantee the tracking performance and tackle the effect of actuator saturation, an adaptive NN controller integrating an auxiliary system is designed to handle the actuator saturation. By employing Lyapunov stability theory, the stability of the closed-loop system is achieved. The experiments on the Baxter robot are implemented to verify the effectiveness of the proposed method.

Position Sensorless Control of Switched Reluctance Motors Using Reference and Virtual Flux Linkage With One-Phase Current Sensor in Medium and High Speed

This paper presents a novel position sensorless control for 6/4 switched reluctance motors (SRMs) using only one-phase current sensor in medium and high speed. In order to eliminate phase voltage sensors, a virtual phase voltage is established to replace the real-time phase voltage in the whole conduction cycle, so as to calculate the phase flux linkage which is called virtual flux linkage. A nonlinear model is utilized to estimate the reference flux linkage-curve of any rotor position. With only one-phase current sensor, the determination of turn off angle position and phase commutation position is achieved by the comparison of reference flux linkage and virtual flux linkage. The speed estimation is performed by two reference flux linkage-current curves at particular rotor positions. Based on the obtained turn off pulse of the present phase and the turn on pulse of next phase, the remaining trigger pulse signals of three phases are derived from a delay-time strategy. The proposed scheme requires only one-phase current sensor, without any pulse injection or complicated decoupling algorithm, achieving a simple and cost-effective drive. Simulations and experiments are carried out on a 6/4-pole prototype SRM drive system to verify the correctness and effectiveness of the proposed sensorless control scheme.

An AC Voltage Sensor-less Control Strategy for Ocean Ship Photovoltaic Grid-connected Inverter with LCL Filter

Che, Y.; Xue, S., and Wang, D., 2018. An AC voltage sensor-less control strategy for ocean ship photovoltaic grid-connected inverter with LCL filter. In: Liu, Z.L. and Mi, C. (eds.), Advances in Sustainable Port and Ocean Engineering. Journal of Coastal Research, Special Issue No. 83, pp. 109–115. Coconut Creek (Florida), ISSN 0749-0208.In the traditional controlling of PV inverter with LCL filter, an extra sensor is needed to detect the voltage of PoC (point of connection) and to restrain the inherent resonance in LCL filters, which increases the control costs and reduces the system reliability. This paper proposes an AC Voltage Sensor-less control strategy for ocean ship photovoltaic grid-connected inverter with LCL filter. Based on the droop control principle, the instantaneous reference voltage is obtained from active and reactive power. Besides, virtual impedance is added to suppress harmonic, which improves the quality of grid-connected current and the accuracy of power control. Simulation results show the feasibility and effectiveness of the proposed control strategy.

Sensorless control strategy of interior permanent magnet synchronous motor

Sensorless control strategy of interior permanent magnet synchronous motor

Design and performance analysis of an iterative flux sliding-mode observer for the sensorless control of PMSM drives

To improve the performance of permanent magnet synchronous motor (PMSM) drives, a sensorless control scheme based on a novel iterative flux sliding-mode observer (IFSMO) is proposed in this paper. Two major drawbacks of the conventional sliding-mode observer (SMO), namely, chattering phenomena and high-order harmonics, are discussed. These drawbacks affect the estimation accuracy of the SMO and reduce the control reliability of the system. To eliminate high-order harmonics, a flux SMO is designed by expanding the PMSM state equations with the PM flux. The flux SMO estimates the rotor speed and position using the flux linkage instead of back-EMF information. Moreover, to reduce the chattering in the estimation results, the proposed flux SMO is iteratively used in one current sampling period to adaptively adjust the observer gain. An overall PMSM sensorless control system based on the proposed IFSMO is designed, and an experimental platform using the TMS320F28335 digital signal processor (DSP) controller is built. The superior chattering reduction and harmonic suppression characteristics of the proposed IFSMO are experimentally validated, and the experimental results verify the feasibility of using the proposed IFSMO-based PMSM sensorless scheme in practical applications.

A Position Sensorless Control Strategy for the BLDCM Based on a Flux-Linkage Function

A novel sensorless control strategy for the brushless dc motor (BLDCM) is proposed in this paper. The proposed strategy is realized by employing new flux-linkage functions and can be applied to drive the sensorless BLDCM in the high-speed and low-speed ranges with highly accurate and reliable commutation. Another attractive feature is that the jumping edges of the flux-linkage functions are utilized to determine the commutation points, so there is no threshold needed as compared with other sensorless control methods. In addition, the three-phase current control method is adopted, and terminal voltages in flux-linkage function expressions can be easily obtained by calculation. By this way, the sample delay and the influence of the floating phase voltage can be eliminated, which can improve the accuracy and reliability of the sensorless control strategy. The effectiveness of the proposed strategy is verified by experimental results.

A Position Sensorless Control Strategy for SPMSM Based on an Improved Sliding Mode Observer

Due to chattering phenomenon, a low-pass filter (LPF) is commonly used to suppress chattering in conventional sliding mode observer (SMO). However, the phase lag caused by LPF will degrade the performance of sensorless control for SPMSM, especially in high-speed range. To solve this problem, an improved SMO (ISMO) is proposed in this paper, which adds the flux as a state variable based on conventional SMO. Then, the observer will filter out the chattering signal while observing the magnetic flux accurately.

HIGH INTEGRATION BRUSHLESS DC MOTOR CONTROL SCHEME FOR NEW ENERGY VEHICLES

With the factory to power consumption, efficiency, noise, electromagnetic compatibility requirements gradually increasing, brushless dc motor will be more and more widely applied in the new energy electric cars. The paper propose the improvement of the freescale to provide a high level of integration solutions - S12ZVM mixed-signal MCU series and introduce the detail sensorless brushless dc motor control scheme implementation. Based on the freescale semiconductor MC9S12ZVML128 dedicated to auto motor control chip, combining with the FreeMASTER monitoring software user interface, build high integration brushless dc motor control experimental platform. The experimental results show the applicability and advantage of S12ZVM series control scheme on the new energy automobile motor control.

Sensorless control on a dual-fed flux modulated electric motor

This paper proposes the operation principle and a new flux estimation method for sensorless control strategy for the dual-fed flux modulated electric motor (DFFM). The DFFM is designed based on the flux modulation theory, it includes two stator windings and one rotor which simplify the mechanical structure. The rotor has only modulation iron and no permanent magnets on it, so there is no cogging torque problem in this motor. With adjustment of the outer and inner stator flux rotating frequency and amplitude, different rotation speed and torque of the sandwiched rotor can be gained for the DFFM. Furthermore, an improved flux estimation based sensorless control strategy is performed on the proposed machine to fit the two winding set control situation. The startup and performance of the proposed control strategy is verified by the simulation and experiments.

Sensorless Control Scheme of IPMSMs Using HF Orthogonal Square-Wave Voltage Injection Into a Stationary Reference Frame

This paper proposes a new sensorless control scheme of interior permanent magnet synchronous motors (IPMSMs) using high-frequency (HF) orthogonal square-wave voltage injection into a stationary reference frame (SRF). This method is an improvement on the conventional HF rotating sinusoidal voltage injection into the SRF. First, discrete sequences of the HF currents are applied to establish the whole signal process. Then, a position estimation method without low-pass filters is proposed, and the phase shifts caused by high-pass filters are also reduced. Therefore, the proposed sensorless control method would not be adversely affected by digital filters, which can solve the common drawbacks of the current SRF-based injection methods. Furthermore, the digital delay in drive systems is considered, and its negative influence can be eliminated as well. The sensorless control method is verified by experiments on a 2.2-kW IPMSM drive platform.

Low-Cost Position Sensorless Speed Control of PMSM Drive Using Four-Switch Inverter

A low-cost position sensorless speed control method for permanent magnet synchronous motors (PMSMs) is proposed using a space vector PWM based four-switch three-phase (FSTP) inverter. The stator feedforward d q -axes voltages are obtained for the position sensorless PMSM drive. The q-axis current controller output with a first order low-pass filter formulates the rotor speed estimation algorithm in a closed-loop fashion similar to PLL (Phase Lock Loop) and the output of the d-axis current controller acts as the derivative representation in the stator feedforward voltage equation. The proposed method is quite insensitive to multiple simultaneous parameter variations such as rotor flux linkage and stator resistance due to the dynamic effects of the PI current regulator outputs that are used in the stator feedforward voltages with a proper value of K gain in the q-axis stator voltage equation. The feasibility and effectiveness of the proposed position sensorless speed control scheme for the PMSM drive using an FSTP inverter are verified by simulation and experimental studies.

Sensorless Control Strategy for IPMSM to Reduce Audible Noise by Variable Frequency Current Injection

High-frequency (HF) signal injection is widely used in sensorless control schemes to drive interior permanent-magnet synchronous motors at low speeds, acquiring a good dynamic and a steady performance. However, the audible noise created by the injected HF signal is an obvious defect and restricts its application. In this paper, a variable frequency current injection method is proposed to reduce the noise. First, the theoretical basis of the variable frequency signal injection is analyzed and the demand from the injected signal is proposed. Second, a modified resonant controller is applied to realize the variable current injection and provide a zero steady-state control error. A linear active disturbance rejection controller that contains a resonant observer is applied to realize the q -axis current control and acquire rotor position information. Third, a sweep-frequency switching strategy is proposed to disperse harmonic energy. The energy of injected HF current is further extended by the proposed method when compared to the random switching method. Finally, the related experimental results are presented to verify the sensorless control method proposed.

Hybrid field oriented and direct torque control for sensorless BLDC motors used in aerial drones

In this study, a sensorless hybrid control scheme for brushless direct current (BLDC) motors for use in multirotor aerial vehicles is introduced. In such applications, the control scheme must satisfy high-performance demands for a wide range of rotor speeds and must be robust to motor parameter uncertainties and measurement noise. The proposed controller combines field-oriented control (FOC) and direct torque control (DTC) techniques to take benefit of the advantages offered by each of these techniques individually. Simulation results demonstrate the effectiveness of the proposed control scheme over a wide range of rotor speeds as well as good robustness against parameter uncertainties within -5to + 10% for inductance and -5to + 5% for resistance parameters. The proposed hybrid controller is robust also against noise in voltage and current measurements. In order to verify the results from simulation, the proposed hybrid controller is implemented in hardware using the TI C2000 Piccolo Launchpad and TI BOOSTXL-DRV8305EVM BoosterPack. Testing is done with a Bull Running motor typically used in aerial drones. Testing experiments demonstrate that the hybrid controller reduces the rotor speed ripple when compared to DTC while operating in steady-state mode and decreases the response time to desired speed changes when compared to FOC.

Sensorless Control of Standalone Brushless Doubly Fed Induction Generator Feeding Unbalanced Loads in a Ship Shaft Power Generation System

The standalone brushless doubly fed induction generator (BDFIG) has demonstrated excellent energy-saving performance in ship shaft power generation applications. As a standalone system, it exhibits unbalanced terminal voltages and poor performance under unbalanced loads. However, the existing control scheme of grid-connected BDFIGs cannot be directly applied to stabilize the amplitude and frequency of terminal voltage when the rotor speed and electrical load vary. This paper presents a new sensorless control scheme for the standalone BDFIG under unbalanced load conditions in the ship shaft power generation system. A second-order generalized integrator-based quadrature signal generator is introduced to realize the rotor speed observer for the standalone BDFIG feeding unbalanced loads. The compensation method of negative-sequence power winding voltage is proposed to eliminate the negative-sequence component of the unbalanced power winding voltage. Comprehensive experiments are carried out on a prototype BDFIG with and without the compensation of negative-sequence power winding voltage. The good performance of the proposed sensorless control scheme is verified by the experimental test results.

Improved Nonlinear Flux Observer-Based Second-Order SOIFO for PMSM Sensorless Control

The conventional rotor flux estimation method has issues of dc offset and harmonics, which are caused by initial rotor flux, detection errors, etc. To eliminate these defects, one improved nonlinear flux observer is proposed for sensorless control of permanent magnet synchronous machine (PMSM). First, the rotor position estimation method based on PMSM rotor flux observation is studied. Meanwhile, the limitations of the traditional rotor flux estimators, i.e., the saturation of pure integrator, phase shift, and amplitude attenuation of a low-pass filter are analyzed. Then, two novel flux observers, second-order generalized integral flux observer (SOIFO) and second-order SOIFO, are designed for the rotor flux estimation of PMSM. Based on second-order generalized integrator (SOGI) structure, the SOIFO can limit the dc component to a certain value. Furthermore, the second-order SOIFO is developed from the SOGI, which is characterized with effective dc and harmonics attenuation capability. With the second-order SOIFO, even without magnitude and phase compensation, the dc offset and harmonics of estimated rotor flux could be well eliminated. Therefore, the speed and rotor position can be estimated accurately. All the performances of the four methods are analyzed by transfer functions and Bode diagrams. Finally, the new sensorless control strategy is validated by comprehensive experimental results.

An Improved Position-Sensorless Control Method at Low Speed for PMSM Based on High-Frequency Signal Injection into a Rotating Reference Frame

In this paper, a novel sensorless control strategy with the injection of a high-frequency pulsating sinusoidal voltage into a rotating reference frame for a surface-mounted permanent magnet synchronous motor (SPMSM) is proposed. Conventional schemes may face the problems of applying to the motor with no obvious salient pole effect, and the effect of filter on the bandwidth of the system. Different from the conventional schemes, the new proposed strategy injects a high-frequency pulsating sinusoidal voltage signal is injected into the estimate d-q rotating reference frame, and the rotor position information is obtained from the response of injected high-frequency current signal in the $\alpha $ - $\beta $ stationary reference frame other than the d-q rotating reference frame,which can avoid failure of applying to the SPMSM with no obvious salient pole effect. With this approach, band-pass filter, which is necessary in the conventional sensorless control, is removed to simplify the control structure and improve the system dynamic control performance. Therefore, this paper proposes a simple structure, which modulates the high-frequency current signal directly and only passes through the low-pass filter to obtain the estimated rotor position angle. Finally, the feasibility of the improved high-frequency pulsating sinusoidal voltage injection control method is verified by simulation and experiment.

MRAS speed observer for sensorless adaptive intelligent backstepping controller of induction machines

In this paper, a sensorless adaptive neuro-fuzzy backstepping control scheme is developed for induction machines with unknown model, uncertain load-torque and nonlinear friction where the speed is obtained using the model reference adaptive system (MRAS). Neurofuzzy systems are used to online approximate the uncertain nonlinearities and an adaptive backstepping technique is employed to systematically construct the control law. The MRAS observer is based on two different models, one that is speed independent (reference model) and another that is speed dependent (adjustable model). The speed is estimated via the outputs of the two models. The proposed sensorless controller guarantees the tracking errors converge to a small neighbourhood of the origin and the boundedness of all closed-loop signals what demonstrate the effectiveness of the proposed approach.