Medium-high Speed Research Articles

Sensorless control in full speed domain of interior permanent magnet synchronous motor based on hybrid observer

Aiming at the problem that an Interior Permanent Magnet Synchronous Motor (IPMSM) cannot be smoothly started in zero-low speed range and smoothly transitioned to medium-high speed range by a single observer. This paper proposes a full-speed range control algorithm based on the fusion of pulsating high-frequency injection and back electromotive force (EMF) position error information. In the low-speed range or at start-up, a square-wave high-frequency signal is injected, and the obtained high-frequency current signal is processed to obtain the rotor position error information. The phase shift due to the introduction of a filter is reduced, which improves the control bandwidth and reduces the noise. To ensure smooth switching of the observer, the observer uses a dual second-order generalized integrator module to output the angular frequency in the low-speed range. A higher-order sliding mode observer based on an inverse EMF model obtains rotor position error information at high speeds. During switching, the rotor position information is processed by a fusion strategy, and the obtained hybrid information is fed into the system to improve the stability of the motor operation. A 0.2 kW IPMSM position sensorless vector control system verifies the algorithm’s accuracy.

A Reliable and Efficient I-f Startup Method of Sensorless Ultra-High-Speed SPMSM for Fuel Cell Air Compressors

Extended back electromotive force (EEMF)-based position sensorless field-oriented control (FOC) is widely utilized for ultra-high-speed surface-mounted permanent magnet synchronous motors (UHS-SPMSMs) driven fuel cell air compressors in medium-high speed applications. Unfortunately, the estimated position is imprecise due to too small EEMF under low speed operation. Hence, current-to-frequency (I-f) control is more suitable for startup. Conventional I-f methods rarely achieve the tradeoff between startup acceleration and load capacity, and the transition to sensorless FOC is mostly realized in the constant-speed stage, which is unacceptable for UHS-SPMSM considering the critical requirement of startup time. In this article, a new closed-loop I-f control approach is proposed to achieve fast and efficient startup. The frequency of reference current vector is corrected automatically based on the active power and the real-time motor torque, which contributes to damping effect for startup reliability. Moreover, an amplitude compensator of reference current vector is designed based on the reactive power, ensuring the maximum torque per ampere operation and higher efficiency. Furthermore, the speed PI controller is enhanced by variable bandwidth design for smoother sensorless transition. These theoretical advantages are validated through experiments with a 550 V, 35 kW UHS-SPMSM. The experimental results demonstrated the enhanced startup performance compared with conventional I-f control.

Rotor Speed and Position Estimation Analysis of Interior PMSM Machines in Low and Medium-High Speed Regions Adopting an Improved Flux Observer for Electric Vehicle Applications

This paper proposes a nonlinear flux linkage observer for the PMSM speed controls without motion sensors, introducing the deviation among the real stator flux linkage and an estimated stator flux linkage to suppress feedback and integral flux drift. In the position detection of an interior PMSM without a speed sensor, the traditional back EMF integration method uses a pure integrator, or LPF, to estimate the stator flux. Its inherent defects inevitably lead to inaccurate flux estimation, which directly affects the estimation of the motor mover position, resulting in the decline in motor control operation and the distortion of phase current. This paper uses an improved integrator with adaptive compensation. The projected value of the stator flux linkage has been derived from the estimated value of the rotor permanent magnetic flux linkage position angle and the algebraic model (m-model) of the stator flux linkage, along with a synchronous coordinate system. The IPMSM stator coil flux linkage obtained from the stator coil current and integral voltage models in the static coordinate system is compared to form a feedback closed-loop to suppress the integral drift, and using the cross-product approach of the actual and estimated flux linkage yields the projected value of the IPMSM rotor speed and position through a PLL. Compared with the existing motion-sensorless observers, the methodology proposed in this article is simple and exhibits better dynamic and static estimation performance. Extensive and comprehensive MATLAB computer simulation and experimental findings validate the proposed motion-sensorless control mechanism.

Radial Displacement Sensorless Control in Full Speed Range of Single-Winding Bearingless Flux-Switching Permanent Magnet Motor

It is a key to realizing stable suspension operation of bearingless motor that the rotor radial displacement information is acquired accurately. Sensor applications are sensitive to environments, limiting to scenarios, and increasing costs. Herein, a radial displacement sensorless control method in the full speed range for single-winding bearingless flux-switching permanent magnet motor is proposed. First, an eccentric modulation function is presented, and the flux linkage equation of each winding with rotor eccentricity is derived based on the air-gap magnetic field modulation theory. Therein, the phase inductance and flux are functions of the rotor displacement. Second, the bias-flux equations of the symmetric windings are deduced, and the rotor displacement observer of the medium-high speed is established based on the bias-flux amplitude. Due to flux information being difficult to extract at low speed, the high-frequency current signal is injected into the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d_T</i> -axis of the torque plane. The rotor displacement observer of the zero-low speed is established based on the high-frequency bias-induced EMF amplitude. Besides, a novel smooth switching process is designed. Finally, the observers are analyzed, and the radial displacement sensorless control strategy is built. The experimental results verified the validity of the proposed method.

Exploration of the intelligent control system of autonomous vehicles based on edge computing.

The development of science and technology continues to promote the progress of society. The current intelligence and automation technology has become widely used in society. To this end, this study proposes a vehicle intelligent control system based on edge computing and deep learning to promote the far-reaching development of intelligent technology and automation technology. First, control algorithms are used to design a switch control strategy combining accelerator and brake. Second, a fuzzy control algorithm based on vehicle tracking and trajectory deviation is designed to enhance the vehicle's stability during steering. A Convolutional Neural Network (CNN) is used to recognize the car's surroundings as it drives. In addition, accelerator and brake controllers and vehicle tracking and trajectory deviation controllers are connected to the vehicle's wiring. Then, the data transmission function based on edge computing is applied to the vehicle's intelligent control system. Finally, trajectory tracking and emergency braking experiments are carried out on the control system to verify the practicability and reliability of the method and the effectiveness of CNN. The simulation experiments are carried out on two states of medium speed and high speed to verify the effectiveness of the longitudinal anti-collision system of the test vehicle when the target vehicle suddenly decelerates. The results demonstrate that the driving speed of the experimental vehicle is set to 50km/h, the distance between the experimental vehicle and the target vehicle is 40m, and the target vehicle in front drives at a constant speed of 50km/h. The target vehicle in front of the car suddenly decelerates in 5 seconds, and the speed drops to 0 after 5 seconds. The actual distance between the experimental vehicle and the target vehicle is very close to the expected safe space, and the experimental vehicle is in a safe state during this process. When the experimental vehicle starts to decelerate, the experimental vehicle adopts emergency deceleration to ensure a safe distance between the two vehicles. At this time, the car enters the second-level early warning state, but driving safety can still be guaranteed. It is advisable to maintain low-speed emergency braking in this state. This study provides creative research ideas for the follow-up research on the intelligent control system of uncrewed vehicles and contributes to the development of intelligence and automation technology.

Application Research of Pulse Vibration High-Frequency Voltage Injection Method Without Speed Sensor in New Energy Vehicles

The high-frequency voltage injection method of pulse vibration in the range of zero/low speed to medium-high speed has to be demonstrated for new energy vehicles., because it is very necessary and necessary to control the safety performance of the whole vehicle without speed sensor. The permanent magnet synchronous motor starts slowly to circle when the clean - energy vehicle cranked, and the correctness of the rotor’s startup position identification is significant. In order to achieve high-performance control of permanent magnet synchronous motor without speed sensor, this paper focuses mainly on how to estimate the rotor position of permanent magnet synchronous motor by amplifying the mathematical model of the motor. The high-frequency mathematical model of the permanent magnet synchronous motor’s voltage parameters are attained in the process of maintaining the motor’s preoperational position to address the problem of self-adaptability between the injected voltage and the likely phase current. The initial position identification of the rotor of a permanent magnet synchronous motor can be achieved by optimizing the adaptive method, and the pulse vibration highfrequency voltage anesthetic method also shows better efficiency and safety when the motor achieves a stable start and has sound output torque. The struggling to retain adaptive measurement device vibration high frequency voltage injection approaches is used by the light-duty low-speed new energy vehicle, which may minimize the mechanical speed sensor after becoming damaged, save the cost and improve the compactness of the electric vehicle space design, which is conducive to solving the situation of energy shortage in my country and alleviating environmental pollution. This is in line with the future development concept of society.

A Comparison Research on Sliding Mode Observation Methods for SPMSM in Sensorless Environment of Medium-to-High Speed

Aiming at sensorless control system of surface attached permanent magnet synchronous motor (SPMSP), three observation algorithms proposed in recent years to estimate rotor position and speed under medium-high speed operation were introduced in this paper. The working principles, advantages and disadvantages of these algorithms such as the Extended Kalman filter algorithm (EKF), Model Reference Adaptive System (MRAS) and Sliding Mode Observer (SMO) were compared, and the applicability of these three algorithms on SPMSP at present was compared and summarized. Furthermore, a sensorless control strategy based on improved SMO was designed to ensure sensorless control effect under medium-high speed operation of SPMSM.

An Efficient and Robust I-f Control of Sensorless IPMSM With Large Startup Torque Based on Current Vector Angle Controller

Interior permanent magnet synchronous motor (IPMSM) with back electromotive-force (EMF) based sensorless field-oriented control (FOC) is widely used in medium-high speed applications. Unfortunately, the back EMF is too small to be estimated accurately during low speed operation. Hence, the current-frequency ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I–f</i> ) control with controllable current vector is used for startup. However, the conventional <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I–f</i> control is hard to realize the tradeoff between startup speed and load capacity, suffering high-acceleration and high-load startup failure. In this article, a current vector angle controller for sensorless IPMSM startup is proposed to adjust speed-up-stage current acceleration and constant-speed-stage current amplitude with load automatically. The proposed angle controller guarantees the current vector angle close to the maximum torque per ampere angle, which contributes to large startup torque, high operating efficiency and smooth transition from <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I–f</i> startup to sensorless FOC. Furthermore, the robustness against parameters variation of angle controller is evaluated quantitatively. These theoretical advantages are verified in experiments with a 380 V, 1.5 kW IPMSM. In particular, the experimental results demonstrate that the proposed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I–f</i> control realizes full-load startup even with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\rm{ \pm }}$</tex-math></inline-formula> 50% flux linkage and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\rm{ \pm }}$</tex-math></inline-formula> 30% inductance variation. Furthermore, the startup acceleration auto-adjusts with load to reconcile startup speed and load capacity.

Sensibilization of a motorcycle simulator to the effects of the roll motion: Modelling and experimental validation

When riding a motorcycle, the applied steering torque and the lateral rider body movement influence its trajectory. Reproducing the effect of body and motorcycle roll on a simulator would improve its realism. However, this goal is still challenging, especially on low-complexity simulators such as the MOVING simulator of the University of Florence. In order to achieve this result, this study defined a control logic to introduce steering effects linked with the mockup passive inclination operated by the rider. The logic computed a roll-related steering input consisting of equivalent steering torque. This contribution was added to that the rider exerted on the handlebar. A validation test with participants revealed improvements over the baseline, roll-insensitive approach, especially in stationary and medium-high speed manoeuvres. Interestingly, the riders unconsciously tended to use larger mockup roll angles as the roll sensitivity increased. The logic was optimised for stationary manoeuvres; however, the subjective feedback provided by the participants indicated a good level of riding realism also during transients. This simple and effective logic opens the way for new methodologies to improve the realism of motorcycle simulators, encouraging their development and use.

A Sensorless Control Strategy of Injecting HF Voltage Into d-Axis for IPMSM in Full Speed Range

This article presents a sensorless control strategy by injecting high-frequency (HF) voltage into the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> -axis for the interior permanent magnet synchronous motor (IPMSM) in the full speed range. The defined quadratic virtual back electromotive force model can be adopted in the full speed range, and thus, there is no need to design a transition algorithm from the zero–low speed to the medium–high speed. Besides, the accurate model of IPMSM is applied to eliminate the error caused by ignoring the stator resistance. Furthermore, the estimation error caused by the filter and system delay during demodulating the HF current in the conventional HF voltage injection method is avoided. Compared with the method of injecting HF voltage into the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> -axis, the proposed method has smaller torque ripple and smaller injected voltage. The effectiveness of the proposed method is verified by experimental results.

Potential of emission reduction of a turbo-charged non-road diesel engine without aftertreatment under multiple operating scenarios

In this study, the bench test of a non-road diesel engine was conducted under universal conditions, non-road steady-state cycle (NRSC) and non-road transient cycle (NRTC). To reduce the raw emissions of the tested non-road diesel engine, some improvement measures, such as pre-injection, smoke limit, and intake throttle degree control strategy, were applied to the optimized engine. The experiment results showed that particulate matter (PM) emissions are reduced significantly at medium-high speed and low load. The maximum and average proportion of PM emissions reduction at 0–30% load and 1400–2200 r/min are 68.4% and 47.5%, respectively. However, the optimized nitrogen oxide (NOx) emissions are higher than that of the original engine, particularly under low load working conditions. Nevertheless, at medium-high speed and load, NOx emissions of the optimized engine were reduced. PM and NOx emissions decreased by 12.3% and 2.4%, respectively, under NRSC. Under NRTC, PM and NOx emissions decreased by 5.2% and 5.5%, respectively. Unburned hydrocarbon (HC) and carbon monoxide (CO) were always maintained at extremely low emission levels. Furthermore, the fuel consumption almost remained constant under all operating conditions. Thus, this study demonstrates the emission reduction potential in non-road diesel engines without considerable payment.

Comparison of Gait variables and Relative Risk of Falls According to Walking Speed During Flat and Obstacles Walking of Fallers and Non-Fallers in Korean Elderly Women

PURPOSE: The purpose of this study was to compare the gait variables and the relative risk of falling between elderly Korean women that fall and do not fall based on the walking speed during flat walking and in the presence of obstacles.METHODS: The study included 148 women, aged 65 years or older (22 fallers, aged 75.05±5.38 years; 126 non-fallers, aged 71.80±5.14 years). The gait variables were measured in a space of 9 m×1 m, and obstacle walking was measured while crossing obstacles measuring, 5 cm and 30 cm. A t-test, correlation analysis, and logistic regression analysis were performed to compare the gait variables to determine if there was a fall and to analyze the relationship and the risk ratio of a fall at a walking speed.RESULTS: Out of 148 participants, 22 participants (14.9%), fell while walking. During flat ground walking, right step length (p&lt;.01) left step length (p&lt;.05), and stride lengths (p&lt;.01) were smaller in the faller group, while the stance phase (p&lt;.01) and double-support time ratio (p&lt;.05) were smaller in the non-faller group. In obstacle walking, slower walking speeds were observed for the 5-cm obstacles (p&lt;.01) and 30-cm obstacles (p&lt;.05) in the faller group. For the low-speed and medium-high speed groups, the odds ratio of the fall experience was 2.844 (1.125-7.191) (p&lt;.05) for flat gait, 3.585 (1.354-9.491) (p&lt;.05) for the 5 cm obstacle, and 4.877 (1.731-13.742) (p&lt;.01) for the 30 cm obstacle. As the height of the obstacle increased, the fall odds ratio increased.CONCLUSIONS: In the faller group, the step and stride lengths were smaller during flat walking, and the walking speed of the obstacles was low. The low-speed group had a high falling experience odds ratio, and as the height of the obstacle increased, the falling experience odds ratio increased.

Research on vehicle adaptive cruise control based on BP neural network working condition recognition

To solve the problems of the vehicle following model mismatch under different driving conditions and poor vehicle following performance, this paper proposes an adaptive cruise control system based on BP neural network to identify different driving conditions. Firstly, eight typical driving cycles are selected as samples, which are redivided into low-speed mode and medium high-speed mode. According to the selected characteristic parameters and re-division of driving mode, a new BP neural network structure is designed. Secondly, the characteristic parameter values are calculated by using the characteristic parameters, and the characteristic parameters are normalized. The working condition recognition model is obtained by training the normalized data values. Finally, according to the classification of working conditions, the fuzzy control upper control algorithm and the MPC upper control algorithm for medium-high speed conditions are designed respectively. Based on the above control algorithms, the joint simulation is carried out with Car-Sim and MATLAB/Simulink. The simulation results show that the low-speed fuzzy logic algorithm and the medium high-speed MPC algorithm proposed in this paper can make the vehicle have a better following performance and comfort.

Study on cutting force of reaming porcine bone and substitute bone.

Accurate mechanical feedback systems are critical to the successful implementation of virtual and robotic surgical assistant systems. Experimental measurements of reaming force could further our understanding of the cancellous bone reaming process during hip arthroplasty to help develop surgical simulators with realistic force effects and improve the protection mechanism of robot-assisted surgical systems. In this study, reaming experiments with natural bone (porcine femur) and a bone substitute (polyurethane blocks) were performed on a CNC lathe. This paper proposes using the maximum reaming force of the steady reaming stage to represent the force characteristic. The reaming force is biased to one side in the overlap direction and the maximum reaming force will vary when the reamer is not coincident with the long axis of the bone. The diameter of the reamer has the greatest influence on reaming force, which clearly increases with increasing reamer diameter. During operation, a medium rotation speed and high feed speed can reduce the reaming force. After cutting, the morphology of the cut surface is not flat, but arc-shaped, which will have a significant impact on implantation of the femoral prosthesis. In in vitro cutting experiments, polyurethane blocks can be used as a substitute for cancellous bone.

Experimental Investigation of Combustion Characteristics on Opposed Piston Two-Stroke Gasoline Direct Injection Engine

The combustion characteristics of an opposed-piston two-stroke gasoline engine are investigated with experiment. The energy conversion and exergy destruction are analyzed and the organization method of the combustion process is summarized. The effects of phase difference, scavenging pressure, injection timing, ignition timing, and dual spark plug ignition scheme on the combustion process and engine performance are discussed, respectively. The heat release rate of the opposed-piston two-stroke gasoline engine is consistent with the conventional gasoline engine. With the increase of opposed-piston motion phase difference, the scavenging efficiency decreases and overmuch residual exhaust gas is not beneficial to the combustion process. Meanwhile, the faster relative velocity of the opposed-piston near the inner dead center enhances the cylinder working volume change rate, which leads to the rapid decline of in-cylinder pressure and temperature. The 15 °CA of opposed-piston motion phase difference improves the scavenging and combustion process effectively. When scavenging pressure is 0.12 MPa, the scavenging efficiency and heat release rate are improved at medium-high speed conditions. With the delay of injection timing, the flame developing period decreases gradually, and the rapid burning period decreases and then increases. The rapid burning period may reach the minimum value when the injection advance angle is 100 °CA. With the delay of ignition timing, the flame developing period increases gradually, and the rapid combustion period decreases and then increases. The rapid combustion period may reach the minimum value when the ignition advance angle is 20 °CA. Notably, the flat-top piston structure should be matched with the dual spark plug, which the ignition advance angle is 20 °CA at medium-high load conditions.

Exploration on Matching Characteristics of Slip and Turns of Multistage Synchronous Induction Coilgun

Synchronous induction coilgun (SICG) has received tremendous attention in the military and civilian fields, which can be attributed to their inherent excellent noncontact linear propulsion characteristics. Theoretically, the ferromagnetic projectile can be launched at hyper-speed by multistage coil relay propulsion. However, the consensus of the SICG on low-speed and large-load propulsion has made its medium-high speed launch a controversial topic, hampered in part by lack of in-depth exploration of simulation model. Based on the previous work, this article focuses on the matching characteristics of slip and turns in order to obtain more reasonable parameter design strategy for the high-speed SICG. First, the numerical simulation model of multistage SICG is constructed on the premise of idealized assumptions to describe the energy conversion process. Then, the concept of slip is explained and the calculation formulas of slip and turns are derived, respectively. Finally, the operating characteristics of the two matching strategies of slip and turns are analyzed. The conclusions obtained by theoretical derivation and simulation comparison can provide reference for the design of medium-high speed SICG.

Rotor Position Estimation Approaches for Sensorless Control of Permanent Magnet Traction Motor in Electric Vehicles: A Review

Permanent magnet traction motor has the advantages of high efficiency, high power density, high torque density and quick dynamic response, which has been widely used in the traction field of electric vehicle. The high-performance control of permanent magnet traction motor depends on accurate rotor position information, which is usually obtained by using mechanical position sensors such as hall sensor, encoder and rotary transformer. However, the traditional mechanical sensor has the disadvantages of high cost, large volume and poor anti-interference ability, which limits the application of permanent magnet motor. The sensorless control technology is an effective way to solve the above-mentioned problem. Firstly, the sensorless control techniques of permanent magnet motor are classified. The sensorless control techniques of permanent magnet motor for rotor initial position, zero-low speed range, medium-high speed range and full speed range are deeply described and compared. Finally, the development trend of sensorless control technology of permanent magnet traction motor is prospected.

Research on the Influence of Population Structure on Economic Growth: Based on the Provincial Panel Data Model

In recent years, the international environment and conditions of China’s economic development have undergone profound and complex changes, but in the middle and long term, China’s economy has been maintaining a stable medium-high speed development. It is remarkable that population changes bring about changes in economic development; especially the aging of the population has a particularly significant impact on economic growth. Therefore, based on the inter-provincial panel data of 31 provinces and municipalities from 2011 to 2019, this paper mainly studies the impact of population change on economic growth by establishing a solid fixed effect model. The results show that there is a long-term equilibrium relationship between population structure and economic growth, and population structure has a significant positive impact on economic development. In addition, there are regional differences in the positive and significant relationship between the two.

Force modeling of zero/low-velocity fin stabilizer and hydrofoil profile optimization

Fin stabilizers have been widely used to reduce the roll motion of ships at medium-high velocities. However, the anti-rolling efficiency of the traditional fin declines rapidly as the speed of the ship decreases. To enable more efficient use of fin stabilizers across the whole speed range, dynamics of fins at zero-low velocity were derived. Then, the proposed model was verified by experiment and the numerical results were compared with those of previous studies. To obtain a balance between the performance of the hydrofoil profile at zero-low and medium-high speed, we determined desirable ranges for various hydrofoil profile parameters including sweep angle, aspect ratio, and relative position of the shaft for non-retractable fins. Finally, tests were conducted using forced ship roll motion to determine the fin-induced anti-rolling moment and to test the optimized hydrofoil profile under real conditions.

Experimental Investigation on the High-frequency Pressure Oscillation Characteristics of a Combustion Process in a DI Diesel Engine

It is difficult to decompose the in-cylinder pressure of combustion of the direct injection (DI) diesel engine, a transient process associated with complicated oscillation components, because of its steep property. An adaptive cyclic average method based on time varying filter based empirical mode decomposition (TVF-EMD) is proposed to decompose the in-cylinder pressure signal, and the cyclic number is determined adaptively with protruding ratio of high-frequency oscillation. The proposed method is used to compare with the ensemble empirical mode decomposition and original TVF-EMD. The results indicate that the proposed method can overcome the drawbacks of these methods and extract high-frequency oscillations accurately and effectively. Three evaluation indexes, center frequency, normalized energy, and average center frequency are defined to analyze the frequency and energy characteristics of high-frequency oscillation quantitatively. The influence of speed, load, rail pressure, main injection timing, pilot injection interval, and pilot injection quantity are investigated systematically. The energy of high-frequency oscillation reaches the peak at medium-high speed, and increase with engine load and rail pressure. However, the relationship of high-frequency oscillation with fuel injection parameters are non-monotonic.