Differential-Mode Circulating Current Suppression for Paralleled Inverters Fed PMSM Drives Considering Dead Time Compensation

This study presents the development of dead-time compensator with Proportional Integral-Derivative (PID) controller and their implementation in real-time using the Programmable Logic Controller (PLC) on a heater-furnace system that constitute the temperature process. Though PID controller is effective to most of the processes, it has draw backs when used to control the processes with significant dead time. Therefore to eliminate the effects of long dead time, the dead-time compensator combined with PID is proposed. The control equation for the proposed dead time compensator is developed using the mathematical model of heater-furnace system and ladder logic program is created in GE Fanuc Versamax PLC. The PID controller is tuned using process reaction curve method and programmed in PLC. The proposed controller has an outer loop control mechanism with dead time compensator which feeds the inner loop PID controller. The effects of dead time on the performance of PID controller are eliminated through the outer loop control mechanism whose output does not contain modelling errors. The results of the proposed dead-time compensator with PID are compared with the results of the conventional PID controller without dead time compensation for both steady state response and servo-regulatory response. The results of the proposed controller show better improvement in the time domain specifications compared to conventional PID controller.

Unbalanced three-phase currents are drawn using the conventional current controllers in the electric drive system of a permanent magnet synchronous machine (PMSM) with asymmetric phases. Consequently, the negative sequence current appears, which causes the torque ripple in the PMSM. The torque ripple yields the noise and mechanical vibrations in the PMSM drive, reducing the reliability, efficiency, and life span of the machine. The conventional proportional-integral (PI) current controller in a PMSM drive is unable to mitigate the torque ripple for the PMSM with asymmetric phases due to its incapability in dealing with the unbalanced sinusoidal input stator currents. To address this limitation, this manuscript presents an adaptive PI resonant (PIR) current controller, which comprises of a PI controller in conjunction with the resonant controller and harmonic compensation terms in the inner current control loop of an interior PMSM (IPMSM) drive with resistance asymmetry. The harmonic-based resonant controller part of the PIR controller takes care of the harmonic compensation. The saturation of the IPMSM and time harmonics are considered during the simulation studies to mimic the actual behavior of a motor drive system. A significant reduction in torque ripple using the proposed PIR current controller compared to a conventional PI current controller is demonstrated for a 100 kW traction IPMSM with phase asymmetry.

For integrated on-board battery chargers (IOBCs) using permanent magnet synchronous machines (PMSMs), it is not desirable to use the winding inductance measured from the motor in a stationary state to evaluate the equivalent filter inductance during charging operation. This is because the magnetic circuit is coupled when the motor windings are reused as the grid current filters. In addition, the grid current flowing through the parameter-unoptimized PMSM makes it difficult to satisfy the charging standards, which even causes a system crash. The current of the charging system is lower compared with the propulsion mode, which means that the motor usually operates in the linear zone. On this basis, this article proposes a filter inductance model for the dynamic charging process of IOBCs. The method for evaluating the grid current ripple and current symmetry based on the inductance model is given. Then, an iterative design optimization method is used to optimize a PMSM, which enables the PMSM to balance propulsion performance and dynamic charging stability. At last, a control algorithm is proposed based on the inductance model to make the IOBCs further satisfy the charging standard. The theoretical analysis and control algorithm are verified by experiments.

For an inverter drive induction motor control system, a typical problem encountered is the nonlinear voltage gain caused by the non ideal characteristics of the power inverter. The switch dead time will introduce waveform distortion and fundamental voltage drop to the system. If not compensated, such distortions will introduce harmonic components which will cause additional loss in the induction machine. Therefore, the impact of harmonics caused by switching dead time are essential to induction motor drive design, especially when the motor is running at low speed. In this paper, a dead time compensation method is proposed. By adding a 6th order resonant controller to the existing current loop PI controller, the negative sequence 5th order and positive sequence 7th order current harmonics caused by the dead time are eliminated. The overall control scheme is implemented in synchronous rotating d-q reference frame. The controller resonant frequency is 6 times to the synchronous frequency, which is calculated with mechanical speed and slip. Experiment results of steady state and dynamic response studies are presented to validate the effectiveness of the proposed method.

Dead time compensation circuit for radiation detector

Anti-Jerk Control of a Parallel Hybrid Electrified Vehicle with Dead Time

In order to reduce voltage error and stator current distortion caused by dead time in the model predictive control (MPC). Based on the permanent magnet synchronous motor driver and model predictive current control (MPCC), an novel control algorithm is proposed to correct the negative influence caused by dead time to improve its steady-state performance of model predictive control. The correctness of the proposed algorithm is verified by simulation.

This paper presents a modified channel likelihood model for optical communication systems with a photon-counting array receiver where photon-counting events are impaired by undesirable dead time and jitters. After the photon-counting detector detects a photon, the detector will go into a period of dead time under which it cannot detect any incident photons. In this context, the channel will have memory. We derive the channel likelihood in the presence of the detector dead time and the random jitter of the photon arrival. The impact of dead time and jitters on the performance of a pulse-position-modulated (PPM) optical communication system is also investigated. The simulation results indicate that the modified channel likelihood expressions can obtain a more obvious performance gain under the context of a stronger background noise, fewer detection elements, longer dead time and bigger jitter.

In this paper, a new modified Smith predictor using a rapid load estimator scheme is proposed. The advantage of the design is that the load estimator does not involve the solution of a closed-loop equation that contains dead time, and this can achieve a better load disturbance response. This scheme can be easily extended to the case of double integrators. Robust stability of the proposed method is analyzed, and a simple and effective robust controller design rule is derived. It is demonstrated by simulations that the new controller provides a similar or better setpoint response and a faster load disturbance rejection than the dead-time compensator in other papers.

Aiming at deficiencies of output voltage distortion and circulating current generation caused by dead-time effect in the modulation process, a simple and feasible dead time compensation strategy is presented. Firstly, the influence of dead-time effect on the output voltage of bridge is analysed, and a dead time compensation strategy is added between the modulation signal and dead time procession. According to the current direction of the bridge, the rising edge or falling edge of the driving signal is selectively delayed to compensate for dead-time effect. Secondly, an Optimized Triple Phase-shift (OTPS) modulation strategy is adopted with minimizing leakage inductor current Root-Mean-Square (RMS) control, which minimizes current stress, achieves soft-switching operation, avoids phase-shift errors caused by Dead-Time Effect, and optimizes control performance of DC-DC converters. Finally, simulated and experimental results are added to verify the correctness and effectiveness of the proposed method.

Single-photon avalanche diode (SPAD)-based light detection and ranging (LiDAR) introduces significant pileup errors at high echo photon flux due to the SPAD's dead time. To expand the application of single-photon LiDAR in the field of remote sensing, autonomous driving, etc., it is crucial to perform rapid and accurate ranging within an echo photon flux of a wide dynamic range. Emerging SPAD array detectors combined with specific photon detection modes attempt to strike a balance between photon detection efficiency and hardware resources, necessitating the development of appropriate dead time compensation methods. Therefore, we experimentally investigated a synchronous single-photon ranging LiDAR operating in a mode where up to two photons are detected per laser cycle, and proposed dead time compensation methods based on forward modeling of the photon detection process. The results show that, using a wide laser pulse of 3.5 ns, the compensated ranging error is less than 4.2 cm, while the uncompensated ranging error is as max as 17.96 cm. Our method provides a reference for dead time compensation in single-photon LiDAR that requires comprehensive consideration of detection efficiency and hardware resources.

This paper proposes a new dead time compensation method for a PWM inverter. Recently, PWM inverters are widely used for industrial applications, such as ac motor drives, distributed grid-connected systems and a static synchronous compensator (STATCOM). The nonlinear characteristics of the switch and the dead time cause a current distortion and a deterioration of the power quality. The dominant harmonics is the 5th and 7th harmonics in the stationary reference frame, and the 6th harmonics in the synchronously rotating frame. In this paper, a resonant controller which compensates the 6th harmonics in the synchronously rotating frame is proposed. This method does not require any off-line experimental measurements, additional hardware and complicated mathematical calculations. Furthermore it is easy to implement and does not cause any stability problem.

The distillation columns are widely used in various chemical industries. It is basically used for separating the components of a liquid mixture. The More volatile component is vaporized, and the less volatile one is left back in the liquid. The plant of distillation column that is considered in the present work is a SOPDT transfer function model imported from an online source. Due to the impact of present dead time, the stability in the output variable is a challenging task. So, the improved control performance is achieved by the dead time compensation using the Smith predictor. The PI control systems are designed, using MATLAB, for this plant with and without Smith predictor, and their performance is compared.

Robustness properties of sampled-data systems with dead time compensators

A modulated synchronous doubly stochastic flow under conditions of a fixed dead time is considered. After each registered event there is a time of fixed duration T (dead time), during which another flow events are inaccessible for observation. When duration of the dead time period finishes, the first happened event creates the dead time period of duration T again and etc. An explicit form of a probability density function of interval duration between two adjacent events of modulated synchronous doubly stochastic flow under conditions of a fixed dead time is derived. Also an explicit form of a joint probability density function for modulated synchronous flow interval duration is obtained. A recurrent conditions for modulated synchronous flow as well as some probabilistic characteristics of the flow are obtained using the formula for a joint probability density function.