Dead-time Compensation Research Articles

A dead-time compensation method for motor drive inverters based on nonlinear observer

Silicon carbide (SiC) inverters and interior permanent magnet synchronous motors (IPMSMs) are widely employed in electric vehicles (EVs) due to their superior efficiency and high power density. However, the harmonics generated by the high switching frequency and the dead-time effect in SiC inverters present a significant challenge. The time-varying nature of on–off delays and conduction voltage drops in power devices makes it difficult to establish a precise nonlinear model for inverters, thus limiting the effectiveness of traditional dead-time compensation methods. This paper introduces a dead-time compensation approach for voltage source inverters (VSIs) that leverages a nonlinear observer, thereby circumventing the need for a complex inverter model while enhancing compensation accuracy. The method determines the three-phase stator current polarity of the IPMSM by deriving the relationship between the current vector angle and the rotor position angle. Along with duty cycle variations computed by the PI controller, the inverter’s nonlinearity is adaptively compensated. Simulation and experimental results indicate that the proposed method outperforms the traditional method based on the error voltage model, effectively reducing the total harmonic distortion (THD) of the phase current.

Dead-Time Free Modulation Scheme for IM Drive System Fed by Voltage Source Inverter

During the modulation process of the VSI motor drive system, the nonlinear errors caused by the dead-time and conduction voltage drop will increase the phase current harmonic distortion and the torque ripple. To solve this problem, a novel dead-time free modulation scheme is proposed in this paper. In the non-zero crossing region of the phase current, the switching tube, whose body diode can provide a continuation path, is set as off-state, the driving signal is only implemented on another switching tube with the same bridge arm, and the errors caused by the conduction voltage drop and switching delay are compensated to the pulse duration. At the same time, to suppress the zero current clamp effect that exists near the zero crossing point of the phase current, another modulation scheme for the phase current crossing zero in advance is proposed, which avoids the complicated determination and calculation of the current polarity near the zero crossing point of the current. Both of the above modulation schemes eliminate the dead-time, and the switching principle is presented. In addition, to suppress the impact of the current ripple and high-frequency noise on the accuracy of the phase current detection, a second-order resonance digital filter without phase shift is introduced. Finally, compared to two deadtime compensation methods, the effectiveness and superiority of the proposed dead-time free modulation scheme are verified by the experimental results.

Dead-Time Compensation Based on Current Phase Estimation for High-Frequency Cascaded Transformer Multilevel Inverter

Dead-Time Compensation Based on Current Phase Estimation for High-Frequency Cascaded Transformer Multilevel Inverter

Dead-Time Compensation Using ADALINE for Reduced-Order Observer-Based Sensorless SynRM Drives

The inverter dead time effect is non-negligible for the control performance of sensorless synchronous reluctance motor (SynRM) drives at low speeds. In this paper, a reduced-order observer-based sensorless control method for SynRM drives combined with the adaptive linear neurons (ADALINE)-based dead-time compensation is proposed. The reduced-order observer-based sensorless control method is presented, for which is parameter tuning is easy. On this basis, the dead-time compensation strategy using ADALINE filters is proposed to reduce the voltage harmonics effect on the estimation performance of the reduced-order observer. With ADALINE filters, the sixth current harmonic can be successfully filtered out by compensating the voltage directly or fitting the current to compensate the voltage. In this way, the low-speed estimation performance of the reduced-order observer is improved. The effectiveness of the proposed method is verified on a 3 kW SynRM experimental platform.

A Inverter Dead-time Compensation Method Based on Phase current Polarity Determination and Voltage Partitioning

The introduction of the dead time of the inverter solves the straight-arm conduction problem of the upper and lower power devices of the inverter, but also leads to the deviation of the actual output voltage of the inverter from the given voltage. Dead time increases the harmonic components of phase voltage and phase current, which is also an important factor leading to motor torque ripple. In this paper, the mechanism of the deviation of phase voltage and phase current caused by the dead time of voltage space vector modulation is analyzed, and the effect of dead time on phase voltage and phase current harmonic components is studied. A simple and effective dead time compensation method based on phase voltage division and phase current polarity determination is proposed to directly compensate the dead time. This method can suppress the current harmonic and torque ripple in the running state of the motor, and can greatly simplify the calculation process of the traditional dead time compensation method. Through the system modeling and simulation, it is verified that the method can significantly improve the current waveform distortion, and has good practical value.

A Small-Sized High-Precision Digital Closed-Loop Modulation Method for Dead-Time Compensation for Flying Capacitor Three-Level Inverters

A Small-Sized High-Precision Digital Closed-Loop Modulation Method for Dead-Time Compensation for Flying Capacitor Three-Level Inverters

Dead-time compensation and single-loop control strategy for ground power unit

Instead of the auxiliary power system, the ground power unit supplies to airplanes during stopovers in airports, which is an important means of reducing carbon emissions of airport. However, under the restraint of switching frequency and high dynamic response speed, a single control loop is usually implemented in 400 Hz voltage-source inverter, the sampling and control of the inductor current in the LC filter are avoided, result in the design of the control system being more difficult, and the direction of the dead-time compensation can not be obtained due to the lack of the current polarity. In view of the above problem, this paper firstly analyzes the influence on the output voltage of inverter due to the dead-time, including the errors of fundamental amplitude and phase, and the low-order harmonic distortion. Then, according to the state equation of the inductor current, a current observation model without zero drift is proposed to obtain the polarity of the inductor current. On this basis, feedforward compensation is carried out for the voltage error generated by the dead-time. Combined with the amplitude-frequency characteristic curve, the parameter optimization design method of the single closed-loop proportional-resonant controller is presented. Finally, a simulation model and an experimental platform are established to verify the feasibility and effectiveness of the current observation model, dead-time compensation method and controller parameter optimization design method proposed in this paper.

Optimal fractional-order series cascade controller design: A refined Bode’s ideal transfer function perspective

In process industries, cascade control is comprehensively used for disturbance attenuation. This manuscript presents the control of the non-minimum phase (NMP) system with dead time via a series cascade scheme. An improved fractional-filter-based control scheme encompassing inverse and dead time compensators with analytical tuning is proposed. The design hinges on an enhanced Bode’s ideal transfer function, which incorporates delay and NMP zero to deal with the system’s NMP and dead time. Particle swarm optimization (PSO) is utilized to obtain the optimal assessment of fractional filter-based controller settings by minimizing an objective function. Two benchmark problems are presented to test the efficacy of the recommended controller. The Riemann surface and sensitivity examination are used to realize the stability and robustness of the feedback design. Numerical simulations exhibit the superiority of the suggested controller for closed-loop results.

Fractional Order Predictive Proportional Integral Control of pH in Effluents of Industrial Plants

Abstract Aim: A robust and advanced controller for pH monitoring and control is necessary in industrial processes inorder to treat the effluents to protect the flora and fauna in the environment. Advanced controllers such as fractional controllers could be used for effective control with increased accuracy and reliability. Materials and Methods: This study includes a comparison of conventional controllers with advanced fractional order controllers to improve the performance of pH control in effluents from the industrial plants. Results: A fractional order predictive proportional integral (FOPPI) controller for effective control of pH was designed and simulated. This controller includes the advantages of a smith predictor for dead time compensation and the robustness of a fractional order controller. The presented method shows an improvement in control performance in terms of rise time (32 s), settling time (140 s), lesser oscillations (2%), and lesser integral of the absolute error of 171. Conclusion: FOPPI provides efficient control of pH in all regions of the titration curve and can be used for the control of pH in industrial waste water.

A Novel Virtual Space Vector Modulation With Optimized Neutral-Point Voltage Control Capability for Ten-Switch Three-Phase Three-Level Inverter

Ten-switch three-phase three-level inverter (TP-TLI) is receiving more attentions owing to the reduced system cost compared to traditional TP-TLIs. However, it still faces serious neutral-point voltage (NPV) balance problem. This article proposes a novel virtual space vector modulation (NVSVM) with optimized neutral-point voltage control (NPVC) capability. A set of virtual vectors are selected to generate zero NP current. By analyzing the vector synthesis principle over the full modulation areas, a new control degree, which is utilized to optimize the NPVC capability and reduce line voltage THD, is introduced. Besides, a dead time compensation method based on volt-second balance is also given to reduce the switching loss. The NVSVM not only improves the NPVC capability without dc offset and obvious ac oscillations in NPV under full range of modulation index and power factor (PF) conditions, but also reduces line voltage THD and the switching loss. Theoretical analysis shows that the available NP current for the proposed NVSVM is about 2.75 times greater at most than that for traditional VSVM. Simulation and experimental results are given to validate the effectiveness of the NVSVM and control strategies.

Compensation of Discontinuous Conduction in Three Phase Voltage Source PWM Inverters

Nowadays the increasing utilization of alternative energy sources demand power converters capable of delivering high quality energy to the low voltage grid. Good dead time compensation and linear operation are essential to keep low order harmonics at acceptable levels. High-current operating conditions are well handled by traditional methods, but low current behaviour and waveforms with multiple zero crossings within a switching period are problematic, especially at low load conditions at or below 10% load. Such conditions often occur in the battery chargers of electric cars. Power quality is also essential for sensorless drives, as the accuracy of the output voltage is very important especially at low rotational speeds. This paper describes the identified cases of discontinuous conduction during dead time. Based on the voltage and current waveforms of the three phase inverter, an improved dead time compensation method is shown for symmetric PWM controlled inverters. The compensator uses already available measurement data, and compensates the resulting error voltage at duty cycle level. The described method can be used for any type of three phase modulation. A similar approach can also be used for two phase modulations.

Adaptive dead time compensation for cross-period single phase shift control of dual active bridge converters

Nowadays, the need for isolated bidirectional DC-to-DC converters is increasing,as electric energyFor high powerstorage is gaining more popularity.applications， the dual active bridge (DAB) DC-toDCVarious control methodsconverters are widely used.were proposed throughout the years, but the conventionalones are not practical to use with low frequency and lowleakage transformers. In this paper an adaptive deadtime compensation method is presented for cross-periodsingle phase shift control, which is specifically designed forthese applications and has outstanding transient responsecharacteristics. The behaviour is analysed and comparedto uncompensated control thorough hardware-in-the-loopsimulation.

ETF dead-time compensation based multiloop control approach for multivariable processes

Due to significant interaction dynamics and time delays in multivariable processes, designing a well-tuned PI controller is always challenging. When tuning multi-loop PI controllers, effective open-loop transfer function should be used instead of the diagonal transfer function element. The complexity of the effective open-loop transfer function (EOTF) increase rapidly for high-dimensional multivariable processes. Therefore, in this manuscript, it is proposed to use equivalent transfer functions (ETFs) under perfect control approximation. Subsequently, a dead-time compensation (DTC) scheme is used for ETFs and PI controllers are tuned. DTC can facilitate eliminating the impact due to time delay from the multivariable process, making the task of tuning PI controllers relatively less complex. The proposed multi-loop control topology minimizes the controller effort, and a good controller design for a multivariable process can be achieved. The PI controller parameters for dead-time compensated ETFs are calculated using simple IMC PI tuning rules, where the filter factor is taken based on the paired element relative gain value. To examine the effectiveness of the proposed controller tuning approach, the proposed control strategy was applied to a wide range of multivariable processes. Compared to state-of-the-art control strategies, the proposed control strategy provides superior closed-loop performance indices, even when there is a significant plant-model mismatch.

A High-Speed Synchronous Rectifier With Improved Dead Time Compensation and Suitable for High-Voltage Applications

A High-Speed Synchronous Rectifier With Improved Dead Time Compensation and Suitable for High-Voltage Applications

A Unified Dual Active Bridge Model Based on Improved Extended Describing Function With Dead Time Compensation for Electric Vehicles

A Unified Dual Active Bridge Model Based on Improved Extended Describing Function With Dead Time Compensation for Electric Vehicles

Dead-Time Compensation Method in Cascaded HBridge Inverter to Mitigate Zero-Crossing Distortion by Reflecting the Ratio of Current Polarity

Dead-Time Compensation Method in Cascaded HBridge Inverter to Mitigate Zero-Crossing Distortion by Reflecting the Ratio of Current Polarity

Decoupled Dead-Time Compensation Method Using Revised-Resonant Control-Based Disturbance Observer in PMSM Drives

Decoupled Dead-Time Compensation Method Using Revised-Resonant Control-Based Disturbance Observer in PMSM Drives

Dead-Time Compensation for Grid-Tied Voltage Source Inverters with SVM $^{2}$ PC

Dead-Time Compensation for Grid-Tied Voltage Source Inverters with SVM $^{2}$ PC

Model Reference Adaptive Observer for Permanent Magnet Synchronous Motors Based on Improved Linear Dead-Time Compensation

Model Reference Adaptive Observer for Permanent Magnet Synchronous Motors Based on Improved Linear Dead-Time Compensation

Dynamic Dead-Time Compensation Method Based on Switching Characteristics of the MOSFET for PMSM Drive System

In order to effectively avoid the shoot-through issue of the semiconductor device (such as the power metal-oxide-semiconductor field-effect transistor (MOSFET)) adopted in the phase leg of the motor drives, a dead-time zone should be inserted. However, the nonlinearity caused by the dead-time effect will bring about voltage/current distortion, as well as high-order harmonics, which largely degrades the performance of motor drives, especially in low-speed operations with slight loads. In this paper, a dead-time compensation method is proposed to suppress such side effects caused by dead-time zones and improve the performance of motor drives. Compared with other existing methods, the proposed method is mainly focused on the switching characteristics of the power MOSFET, which is directly relative to the compensation time in each pulse-width modulation (PWM) period. Firstly, a detailed derivation process is elaborated to reveal the relationship between compensation time and the switching performance of the MOSFET. Meanwhile, the switching process of the MOSFET is also well analyzed, which summarizes the variations in the switching time of the MOSFET with a varied load current. Then, the multipulse test (MPT) is carried out to obtain accurate values of the switching time with the varied load current in a wide range (0–80 A) and form a 2D lookup table. As a result, the compensation method can easily be realized by combining the lookup table and linear interpolation based on the phase current of the motor dynamically. Finally, the effectiveness of the proposed method is verified based on a 12 V permanent magnet synchronous machine (PMSM) drive system. According to the relative experiment results, it can be clearly observed that the time-domain waveform distortion, high-order harmonics, and total harmonic distortion (THD) value are reduced significantly with the proposed dynamic compensation method.