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The voltage utilization in the PMSM control can be improved through the voltage angle control (VAC) method, thereby enhancing the control efficiency and output power capability. However, the traditional VAC method can only be applied to a high-speed region, and it is still necessary to switch to another control mode in the low-speed region, resulting in a significant torque jitter during the switching process. Meanwhile, the deviation between the actual current operating point and the optimal one is caused by the dead-time effect in the traditional VAC method, causing more energy loss. To solve these problems, a global-speed-region VAC method considering dead-time effect compensation is proposed in this article. Firstly, the application area of the proposed method is extended to both the high-speed and low-speed region on the basis of analyzing the variation function of the modulation index (MI), achieving global non-mode-switching control and eliminating the torque jitter. Additionally, the relationship between the dead time and MI is quantitatively analyzed, and a global-speed-region VAC method is proposed to compensate the dead-time effect and reduce the energy loss. Finally, the effectiveness of the proposed method is verified in PMSM bench experiments. [ABSTRACT FROM AUTHOR]

The voltage utilization in the PMSM control can be improved through the voltage angle control (VAC) method, thereby enhancing the control efficiency and output power capability. However, the traditional VAC method can only be applied to a high-speed region, and it is still necessary to switch to another control mode in the low-speed region, resulting in a significant torque jitter during the switching process. Meanwhile, the deviation between the actual current operating point and the optimal one is caused by the dead-time effect in the traditional VAC method, causing more energy loss. To solve these problems, a global-speed-region VAC method considering dead-time effect compensation is proposed in this article. Firstly, the application area of the proposed method is extended to both the high-speed and low-speed region on the basis of analyzing the variation function of the modulation index (MI), achieving global non-mode-switching control and eliminating the torque jitter. Additionally, the relationship between the dead time and MI is quantitatively analyzed, and a global-speed-region VAC method is proposed to compensate the dead-time effect and reduce the energy loss. Finally, the effectiveness of the proposed method is verified in PMSM bench experiments.

Dead time is necessary for the coupled power switches to prevent shoot-through, especially in the modular multilevel converters (MMCs) with a large number of power switches. This paper proposes a dead-time effect suppression strategy for MMCs with nearest level modulation. The operational principles of MMCs are first analyzed. According to the operational features of MMCs, the method that removes a switching signal from the coupled switches and the reduced switching frequency voltage balancing algorithms (RSFVBAs) are mixed in the proposed method. In the intervals that are furthest away from the zero-crossing points (ZCP) of arm currents, the single switching signal method can completely eliminate the dead-time effect (DTE). Alternatively, the DTE is suppressed by the RSFVBA in intervals that are close to the ZCP. By the combination of the two methods, the dependence of the DTE suppression method on currents is reduced and the influences of ZCP are also released without degrading the normal operation performance of MMCs. Moreover, the output performance of MMCs is improved and the voltage stress on the arm inductor dramatically decreases. Finally, the validation of the method is verified by the simulation results with the professional tool Matlab/Simulink.

Active front-end (AFE) rectifiers have become widely employed in power systems to achieve unity power factor and harmonic mitigations. The typical modeling approaches applied for AFE rectifiers in the literature mostly relied on two baselines: the detailed model and the time-average model. The former approach deals with the switching element model (SEM), which leads to significant harmonics in currents with distorted waveforms. The latter approach uses the average-value model (AVM) to overcome the currents' harmonics as well as provide fast responses. However, even the AVM baseline has shown problems during the starting stage (lack of control signals) and over the dead-time periods, which causes serious issues in the implementation process. This paper presents an improved dynamic AVM for AFE rectifiers by precisely considering the issues mentioned above, along with the practical starting procedure and desirable initialization. The studied AFE rectifier is developed using the voltage-oriented control (VOC) technique based on the different modeling methodologies, including SEM, Conventional AVM, and the proposed AVM. The performance of all models is analyzed and compared using simulation results with MATLAB/Simulink R2023a Function blocks for all the algorithm parts and SimScape elements for the electrical circuit model. The simulation results illustrate that the performance of the proposed AVM approach can closely resemble the behavior of the SEM baseline with low harmonic distortion. To evaluate the performance of the proposed model, several case studies are investigated to verify the AFE rectifier operation, regarding mostly the total harmonic distortion (THD) wherein the THD percentages are improved to 4.78 and 2.5 from 5.14 and 2.78 for low- and high-power loads, respectively. [ABSTRACT FROM AUTHOR]

Copyright of Electric Power Automation Equipment / Dianli Zidonghua Shebei is the property of Electric Power Automation Equipment Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The traditional direct torque control (DTC) of two-level voltage source inverter-fed motor system can achieve evident reduction of common-mode voltage (CMV) if zero vectors are not used, as the amplitude of the CMV of the zero vector is much larger than that of the active vector. However, due to the influence of dead-time effect, zero vectors can still be generated during inverter commutation, resulting in CMV spikes. To eliminate the CMV spikes caused by dead-time effect, a novel DTC strategy is proposed in this article. Through the analysis of the voltage vector during the dead-time of the commutation process, the process of looking up the DTC switching table is modified, and a transient vector is inserted when necessary, so that no zero vector is generated during commutation. The proposed DTC strategy eliminates CMV spikes in a look-up table way, so that the simple control structure of traditional DTC is maintained, while neither modification of hardware circuit nor detection of current polarity are required. Experiments verified the effectiveness of the proposed strategy. [ABSTRACT FROM AUTHOR]

The nonlinearity of the voltage source inverter (VSI) leads to the error between output voltage and reference voltage, and causes the phase current harmonics. It is necessary to compensate its influence in the fields such as parameter identification, sensorless control, and servo drives. In this article, an industrial solution for VSI nonlinear compensation method based on lookup table (LUT) is introduced. The characteristics of semiconductor devices, equivalent dead-time and influence of parasitic capacitance effects are calculated quantitatively though injecting increase and decrease current during self-commissioning process. The critical current value for parasitic capacitor and the variation of equivalent dead time are verified through different distorted voltage curves. Considering dc-link voltage variation is irresistible for industrial products, 3-D linear interpolation is adopted to compensate the variation of VSI nonlinearity under different voltage conditions. Proposed LUT method does not require VSI datasheet and complicated calculation formula during implementation. Experiments are carried out on a commercial permanent magnet synchronous motor drive system to verify the proposed LUT method. [ABSTRACT FROM AUTHOR]

No dead-time is contained in the existing dead-time elimination pulsewidth modulation (PWM) for three-phase three-level T-type converters, where complementary drive pulses are allocated alternatively according to polarities of output currents. Consequently, the dead-time effect can be inherently avoided. However, the dependency on current polarities seriously limits its widespread application. Wrong current polarities, e.g., in a dynamic process, will lead to the output-voltage disappearance, thus aggravating the possible “algebraic loop” issue and impairing the stability of the system. In this article, in order to reduce the dependency on current polarities while retaining the characteristic of dead-time-effect elimination, a double-modulation-wave PWM is proposed by modifying the dead-time elimination PWM. Two modulation waves with a magnitude difference are adopted for generating underlap periods between complementary drive pulses, which can avoid the shoot-through failure and no dead-time effect will be generated. And to further simplify the implementation process, the two modulation waves are decomposed by introducing a magnitude-adjustment factor related to the current polarity. Whereas it is also due to the employment of two modulation waves, extra issues of overmodulation, single drive pulses, and a shorter underlap period may occur, which are analyzed in detail and the negative effect can be avoided. Finally, the proposed PWM is experimentally verified, showing the effectiveness on harmonic suppression and the reduced dependency on current polarities. [ABSTRACT FROM AUTHOR]

High-power isolated bidirectional dc–dc converters with wide voltage range are attracting increasing attention in many applications. The bidirectional three-phase current-fed dc–dc converters are known to be suitable for wide voltage range applications compared to dual active bridge based converters, having advantages of reduced device current ratings and prevention of transformer saturation due to high impedance nature. However, when the duty cycle becomes lower than 0.33 or higher than 0.66, power transfer capability is limited, and the efficiency is significantly reduced due to increased circulating current, which has rarely been discussed so far. In this article, a hybrid dual-asymmetrical pulsewidth modulation (DAPWM) and pulsewidth modulation plus phase-shift (PPS) switching method is proposed for efficiency improvement of the bidirectional three-phase push–pull converter with very wide voltage range. A seamless mode change method between PPS and DAPWM is also proposed for minimizing the transient state. Further, through current waveform and power flow analysis, the leakage inductance along with transformer turn ratio are designed to minimize the root mean square (rms) current of devices, while having the capability of transferring the desired power and limiting the slew rate of transformer winding current under wide voltage range operation. Experimental results from a 22-kW prototype are provided to validate the proposed concept. [ABSTRACT FROM AUTHOR]

In view of the low voltage and high current working condition in the voltage source inverter of low-voltage electric vehicle， by considering the nonlinear factors such as the dead-time and the turn-on / off delay of power device， especially， the voltage drop across the power device was taken into consideration． After that， the inverter output characteristic equation was established． Based on the output characteristic equation and the reference voltage， the error could be derived， thus it will accurately be compensated under the low voltage and high current working condition． At the same time， accurate current polarity is essential during the nonlinear characteristic compensation． However， the current ripple and the zero current clamp effect exist near the zero of phase current， which will result in inaccurate current polarity detection． So a method of reverse compensation was proposed to make the current pass zero in advance， which avoids the complicated determination and calculation of current polarity near the zero of current，in the meantime，the nonlinear characteristic of VSI was compensated effectively，too． Finally，the accuracy and feasibility of the proposed inverter output characteristic equation and compensation method are proved by simulation and experimental results． [ABSTRACT FROM AUTHOR]

In this article, the resonant switched-capacitor converter (RSCC) is applied to the auxiliary power system of electric locomotive to improve its efficiency and power density. Phase shift control is generally applied to the RSCC for voltage regulation. But the dead time and parasitic parameters impose the negative effects on the switching transit, the resulted hard-switching process may cause extra switching loss. An optimized soft- switching realized method is proposed under phase shift control. First, transient analysis of resonance is carried out by state trajectory, and steady-state characteristics are discussed. Then, the influence of parasitic parameters on resonant current and output power is discussed. Moreover, the dead-time effect and soft-switching condition are analyzed; therefore, a high-efficiency control strategy with zero-voltage switching is proposed. Experimental results show that the proposed optimization control strategy can improve the efficiency up to 99.4%. [ABSTRACT FROM AUTHOR]

Dead-time causes distorted output current in current-controlled three-phase PWM inverters. Instead of using a real inductor, a virtual inductor is proposed in this paper to minimize the dead-time effects. Virtual inductor is an additional controller block that changes the system behavior so that it is similar as if there is a real inductor in the system. As it is virtual inductor, we have no problems of cost and losses. How to design a virtual inductor for dead-time effect minimization is presented in this paper. The effect of low-pass filter (LPF) which is mandatory in virtual inductor application is also presented in this paper. Simulation and experimental results are included to show the effectiveness of proposed virtual inductor. [ABSTRACT FROM AUTHOR]

The extra-LC auxiliary-resonant-snubber-based converter (ELCARSC), as a soft-switching converter, has the advantages of low switching loss, low electromagnetic interference noise, and low-output distortion caused by the dead-time effect. However, the dead-time effect is still the main problem in a high-precision application. Besides, the traditional control and compensation methods rely on the accuracy of the circuit parameters, especially the junction capacitance, thus resulting in compensation error. Therefore, this paper proposed a novel high-precision control method through modulating the initial resonant current to eliminate the dead-time effect of ELCARSC. The method does not need complicated online calculation and reduces the dependence on the accuracy of the circuit parameters, especially the influence of the junction capacitances of the switches. In this paper, the dead-time effect of the ELCARSC is analyzed. The output voltage error with the conventional variable-timing control method is analyzed. Subsequently, the proposed modulated initial resonant current control is introduced. Finally, a prototype was developed that verified the effectiveness of the control method. The quality of the output current and voltage is improved by utilizing the proposed control method. However, the peak current of the auxiliary switch is increased. [ABSTRACT FROM AUTHOR]

In this paper, a new zero-sequence current suppression control strategy for the five-phase open-winding fault-tolerant fractional-slot concentrated-winding interior-permanent-magnet (FTFSCW-IPM) motor drive system with a common dc bus is proposed. By unequal distribution of the zero voltage vector, the proposed method can well suppress the zero-sequence current caused by the dead-time effect that the conventional eliminating method cannot be achieved. First, the dead-time effect to the zero-sequence current is discussed. Then the zero-axis controller is designed to obtain the reference common-mode voltage. Last, according to the principle of the unequal zero voltage vector distribution, the switching sequence of the two inverters can be calculated, and the maximum modulation index is also first deduced in detail. The proposed method is proved by the simulation and experimental results. [ABSTRACT FROM AUTHOR]

Research on applying selective harmonic elimination pulse width modulation (SHE-PWM) to high power converters has drawn tremendous interest, due to the advantages of low switching frequency and high output harmonic performance. In the fields of high power converters such as variable speed traction motor drives and static synchronous compensators (STATCOM), the adoption of high voltage but slow speed semiconductor devices, i.e., IGBT/IGCT, results in a longer dead time of several microseconds, which leads to a motor vibration in the former case or the distortion of grid current in the latter case. This paper analyzes in detail the mechanism of the dead-time effect on 3-level SHE-PWM with different operating conditions considered. For the first time, a general mathematical model describing the relationship between the dead time and harmonic distribution of SHE-PWM wave is established. Based on which an open-loop compensation method by inserting a margin time into the effective switching angles is proposed. Furthermore, a closed-loop controller that implements online adaptive adjustment of the margin time is designed in case of a variable frequency application. The effectiveness of the proposed method in different scenarios is verified through simulation results.

Square-wave voltage injection is an effective sensorless control method for permanent magnet synchronous motor drives to achieve zero- or low-speed operation. However, it faces great challenge in the case of rail transit application where the switching frequency is less than or equal to 500 Hz, which results in rich low-order harmonics. In order to improve the performance of high-frequency square-wave voltage-injection method over low switching frequency application, an asymmetric space vector modulation (ASVM) method is proposed, and it makes comparisons between carrier and modulation wave in the 1/4 and 3/4 point of each switching cycle. Compared with space vector modulation, ASVM can significantly reduce the low-order sideband and baseband harmonics in the bandpass filter bandwidth. As a result, the position estimation, which is calculated by the filtered current signal, is improved. Moreover, the inverter dead-time effect has been compensated as well. With these improvements, the rotor position can be estimated without using low-pass filters and its dynamic performance can be enhanced. The experimental results proved the effectiveness of the analysis. [ABSTRACT FROM AUTHOR]

This paper proposes a scheme that can compensate for the nonlinear characteristics of voltage source inverters (VSIs) for low-voltage delta-connected induction motors (IMs). Due to the nonlinearity introduced by the dead-time, the on/off delay, and the voltage drop across the power device, the output voltage of VSIs is seriously distorted, causing distortion in the phase current of the IM, which will lead to output torque ripple. However, the existing compensation methods for three-phase VSIs are derived from star-connected loads, or ignore the conducting properties of power devices. Moreover, the current polarity detection near the current zero is quite complex. In this paper, by taking such nonlinear characteristics into consideration, especially the conducting property of metal-oxide-semiconductor field effect transistors (MOSFETs), an output voltage model of VSIs for low-voltage delta-connected induction motors is presented. After that, in view of the difficulty in detecting the line current polarity near the current zero which might lead to the wrong compensation, an advancing current crossing zero (ACCZ) compensation is proposed. Subsequently, a compensation scheme which combines the compensation based on the VSI output voltage model and ACCZ compensation is proposed. Finally, the proposed compensation scheme is implemented based on a digital signal processor (DSP) drive system. The experimental results show that the proposed scheme has better performance than the common method in terms of suppressing the effect of the nonlinear characteristics of VSI, which demonstrates that the proposed compensation scheme is feasible and effective for the compensation of the nonlinear characteristics of VSI for low-voltage delta-connected IMs.

Dead-time effect has become an apparent issue in high-switching-frequency high-power dual active bridge (DAB) DC-DC converter. This paper gives a detailed analysis of phase-shift errors effect caused by dead time, including output voltage offset, soft-switching failure, optimal scheme failure, etc. Phase-shift errors effect will invalidate traditional analyses of optimal control and mislead the design of DAB converter. To overcome these drawbacks, various operating modes and an accurate transmission power model incorporating dead time under triple-phase-shift (TPS) control are developed. On this basis, an optimal TPS incorporating dead time (TPSiDT) scheme is further proposed to minimize the current stress, while guaranteeing soft-switching operation by using Lagrange multiplier method (LMM) and Genetic Algorithm (GA). The novel transmission power model can provide accurate power flow computation to avoid phase-shift errors. Therefore, in practical applications, the minimum current stress and soft-switching operation can be guaranteed, and the efficiency of DAB converter can be improved. Finally, the experimental results verify the feasibility of the proposed TPSiDT scheme.

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The disturbance voltage of voltage-source inverter operation exerts significant influences on the accuracy of motor parameter identification. In this paper, an accurate model is established for estimating the disturbance voltage that includes current harmonics and their derivative. The conclusion is drawn that the derivative of the d -axis current harmonics plays a major role in causing estimation error of the disturbance voltage. Based on this, two methods are proposed to reduce the estimation error of the disturbance voltage. One employs an iterative learning controller in the d-axis current control loop to suppress the harmonics of d-axis current, thus reducing their influence on the estimation of the disturbance voltage. The second estimates the disturbance voltage on the basis of the average value of the variables in q-axis equation of the motor, so that the estimation result is immune to current harmonics. Motor parameter identification accuracy is consequently improved by both. [ABSTRACT FROM AUTHOR]

The paper analyzed dead-time effect and working principle of diode-clamped three-level inverter, proposed a dead-time compensation method which is suitable for diode-clamped three-level inverter based on double carrier modulation. By adjusting dead-time of trigger pulse on different current flow paths, the method realizes level conversion unaffected by dead-time, which means avoiding or reducing dead-time effect. The simulation result shows that the method reduces the 5th and 7th harmonic contents and total harmonic distortion, increases effective current value and has better compensation effect compared with normal dead-time compensation method.

Dead time between the complementary driving signals is needed to avoid short circuit in voltage source inverters (VSIs), however, this raises issues such as voltage distortion and harmonic generation. In wireless power transfer (WPT) systems, the ratio of dead time versus operating period becomes more problematic due to the high frequency, where the dead time can cause serious concerns regarding the phase errors and control performance deterioration. Therefore, this paper presents a comprehensive analysis of the dead-time effect for WPT systems based on a series–series (SS) topology. Firstly, it is found that voltage distortion appears in two regions in comparison with the three in one active bridge WPT system, and seven regions, as compared to the eight in dual active bridge (DAB) WPT system. Afterwards, a novel pulse width modulation (PWM) method is proposed, where the driving signals of the same phase leg are no longer complementary to each other. By employing the proposed method, the dead-time effect can be addressed up to a certain extent, and the desired voltage can be obtained in all the regions. In addition, the proposed method is not influenced by the system parameters, and can be easily applied to other high-frequency resonant converters. Simulated and experimental results are added to verify the feasibility and efficacy of the proposed control scheme.

The dead-time effect, as an intrinsic problem of the converters based on the half-bridge unit, leads to distortions in the converter output. Although several dead-time effect compensation or elimination methods have been proposed, they cannot fully remove the dead-time effect of blanking delay error, because the output current polarity is difficult detect accurately. This paper utilizes the zero-voltage-switching (ZVT) technique to eliminate the blanking delay error, which is the main drawback of the hard-switching inverter, although the technique initially aims to improve the efficiency. A typical ZVT inverter-the auxiliary resonant snubber inverter (ARSI) is analyzed. The blanking delay error is completely eliminated in the ARSI. Another error source caused by the finite rise- and fall-times of the voltage is analyzed, which was not considered in the hard-switching inverter. A compensation method based on the voltage error estimation is proposed to compensate the rise- and fall-error. A prototype was developed to verify the effectiveness of the proposed control. Both the simulation and experimental results demonstrate that the qualities of the output current and voltage in the ARSI are better than that in the hard-switching inverter due to the elimination of the blanking delay error. The total harmonic distortion (THD) of the output is further reduced by using the proposed compensation method in the ARSI. [ABSTRACT FROM AUTHOR]

Dead-time effect often causes the output voltage and current of the power converter to generate a large number of harmonics，which is especially serious at low speed. The present situation of dead-time effect compensation techniques are summarized and reviewed. Some popular compensation methods are introduced before the analyses of their advantage，disadvantage and scope. The future direction of development and research is pointed out. It provides references for the choice of dead-time compensation and the more thorough research. [ABSTRACT FROM AUTHOR]

This paper presents a generalized algorithm to eliminate spikes of common-mode voltages (CMV) caused by dead-time effect for common-mode voltage reduction pulse width modulation (CMVRPWM). The characteristics of the CMV spikes for the popular CMVRPWM strategies (AZSPWM1, NSPWM, CRLO-CMVRPWM, and SLO-CMVRPWM) are studied and compared by analyzing the extreme switch pulse patterns. The proposed CMV spikes elimination method directly adjusts the injected zero-sequence voltages instead of the durations of the adopted voltage space vectors to avoid the overlaps of the adjacent dead time periods. The CMV spikes can be eliminated regardless of the output voltages in the dead time periods; thus, the signs of phase currents are not needed to detect and overcome the problem caused by the resolution of the current sensors when the phase currents approach to zero. In addition, an effective method by online selecting low or high active pulses for the three legs is proposed to ensure that at most one leg switches between adjacent carrier periods. The proposed method is generalized and effective for all the CMVRPWM with symmetrical switch pulse patterns and no simultaneous switching problem. The simulation and experimental results validate the effectiveness. [ABSTRACT FROM AUTHOR]

Attributing to the advantages of high efficiency, low electromagnetic interference (EMI) noise and closest to the pulse-width-modulation (PWM) converter counterpart, zero-voltage-transition (ZVT) PWM soft-switching inverters are very suitable for high-performance applications. However, the conventional control algorithms intended for high efficiency generally results in voltage distortion. Thus, this paper, for the first time, proposes a high-precision control method to eliminate the dead-time effect through controlling the auxiliary current in the auxiliary resonant snubber inverter (ARSI), which is a typical ZVT PWM inverter. The dead-time effect of ARSI is analyzed, which is distinguished from hard-switching inverters. The proposed high-precision control is introduced based on the investigation of dead-time effect. A prototype was developed to verify the effectiveness of the proposed control. The experimental results shows that the total harmonic distortion (THD) of the output current of the ARSI can be reduced compared with that of the hard-switching inverter, because the blanking delay error is eliminated. The quality of the output current and voltage can be further improved by utilizing the proposed control method. [ABSTRACT FROM AUTHOR]

This paper proposes a new method of dead-time effect compensation. The proposed solution is based on additional phase current measurements realized by analog-to-digital converters. These measurements are carried out at the time instants specified by a pulsewidth-modulation (PWM) strategy. This makes it possible to estimate inverter currents at the commutation instants and, finally, to estimate the voltage error caused by dead time. This voltage error is compensated during the next switching period by modification of a reference voltage. The proposed solution can be used to compensate the voltage error in multilevel multiphase voltage source inverters. The experimental research studies were carried out on three-phase two-level and three-level neutral-point-clamped inverters supplying 55- and 160-kW motors, respectively. The results of the experimental investigations are presented in this paper. [ABSTRACT FROM PUBLISHER]

This paper presents an extended electromotive-force-based discrete-time sliding-mode observer (DSMO) for rotor position/speed sensorless control of interior permanent-magnet synchronous machines (IPMSMs). Without using voltage sensors to measure IPMSM terminal voltages, the reference voltages generated by the vector control system are used as inputs for the DSMO. However, due to the inverter dead-time effect, the mismatch between the reference voltages and actual terminal voltages will degrade the performance of DSMO. In this paper, the periodically oscillating rotor position estimation error caused by the dead-time is first analyzed. Then, a dead-time compensation scheme is proposed to mitigate this position estimation error. The proposed DSMO with the dead-time compensation scheme is validated on an IPMSM control system used in heavy-duty, off-road, hybrid, and electric vehicles. [ABSTRACT FROM AUTHOR]

The effect of dead-time on the spectrum of pulse-width modulated signals is analyzed in this paper. The study is valid for arbitrary, band-limited modulating signals, extending previous results in the literature. A simple distortion index is developed that can be used at the design stage to select dead-time or switching frequency based on maximum allowed distortion. Experimental results with various band-limited signals reveal a very good agreement between the theoretical results and the experiments. [ABSTRACT FROM AUTHOR]

As the development of isolated bidirectional full-bridge dc-dc converter (IBDC), the dead-time effect has become an apparent issue. This paper presents a comprehensive theoretical analysis and experimental verification of dead-time effect in the IBDC. Besides the internal power transfer and phase drift phenomena mentioned in previous works, there are also many other novel phenomena caused by the dead time, such as voltage polarity reversal and voltage sag phenomena, etc. The paper gives a detailed switching characterization of the IBDC with dead-time effect in all operation states. On this basis, the transmission power characterization is analyzed comprehensively. Compared to the traditional theoretical model, the transmission power model with dead-time effect is not a strictly monotone increasing function, the relation curve is not symmetric around the median axis, and the zero point is not achieved at zero phase-shift ratio. In addition, in different operation states, the characterization is also different. Finally, experimental results verify the theoretical analysis. [ABSTRACT FROM AUTHOR]

The five-level active neutral-point-clamped (5L-ANPC) converter has been widely studied for its excellent performance in high-power medium-voltage applications. This paper analyzes the space vector pulse width modulation (SVPWM) strategy of the 5L-ANPC converter in the virtual coordinate, and presents an optimized control strategy which can balance the neutral point (NP) voltage and avoid the dead-time effects for the first time. In this strategy, on one hand, the 125 space vectors are combined by 96 triangles in the seven-segment vector synthesis method, then the triangles are divided into seven categories which have different characteristics of balancing the NP voltage, and every category has its own principles to choose the vector sequence and compute the vector durations. On the other hand, the dead-time effects of the 5L-ANPC converter are studied in detail and the transitions between different switching states are constrained in the optimized control strategy to avoid the dead-time effects that cannot be compensated by traditional pulse-based dead-time compensation methods. Finally, the optimized SVPWM strategy is experimentally verified in this paper. [ABSTRACT FROM AUTHOR]

The mechanism of dead-time effect is illustrated, as well as its influences on fundamental output voltage and harmonic spectrum distribution. Combining the basic analysis and the bandwidth of the system close-loop transfer function, the suppression effect on dead-time and the close relationship between the close-loop bandwidth and the suppression effect are quantitatively analyzed. Taking the single-loop controlled LCL inverter as an example, the suppression effect of the close-loop control bandwidth on dead-time is verified by simulation. Finally, experiments are performed on a 250 kW grid-tied inverter to check the suppression effect on dead-time. Simulation and experimental results agree well with the theoretical analysis. [ABSTRACT FROM AUTHOR]

To decrease the switching loss and the dead-time effect of resonant half-bridge inverter, a novel adaptive dead-time control circuit of resonant half-bridge driver Integrated Circuit (IC) is presented. Without increasing the pin number of IC, this circuit takes a novel strategy to adaptively regulate dead time to a temperate range between high and low thresholds. The high and low thresholds are adaptive to the fall time of output signal in a half-bridge clock cycle. The IC of the designed circuit is suitable for high-voltage applications. The dead-time regulation range of this circuit achieves 0–3.5 µs. The range of temperate dead-time state is 300 ns. The failure signal of this circuit can protect the IC and peripheral power devices by regulating operation in three clock cycles. Both simulation and measurement of the proposed circuit in a half-bridge driver IC with an operating frequency at 50 kHz are presented based on the 0.5 µm 700 V BCD process. The results of simulation and measurement show that the presented circuits’ performance is perfect. [ABSTRACT FROM PUBLISHER]

This paper addresses modeling and analysis of the dead-time effects in parallel pulsewidth-modulated (PWM) twolevel three-phase inverters. The main objective is to gain understanding of how the effects caused by the necessary blanking time, the finite turn-on and turn-off times of the switching devices, and the forward voltage drops of the switching devices and the antiparallel diodes, i.e., the dead-time effects, influence the circulating current generation between the parallel-connected units. To meet this objective, a circulating current model taking these effects into account is developed for the parallel connection of n units. The model, which is an average model by nature, can be used to study the circulating current behavior with different types of PWM methods and to estimate the resulting circulating current values when there are differences in the dead-time effect parameters. In other words, the model provides an analytical way to consider the significance of these effects. To verify the validity of the developed model, the circuit simulation and experimental results are shown and compared with the analytical results. The illustrations show that the results obtained with the developed model are in good agreement with the circuit simulations and the experiments. [ABSTRACT FROM AUTHOR]

In this paper, a new two-phase pulse width modulation (PWM) technique is proposed, in which the reference voltage is constructed by three space vectors. At any speed, the peak-to-peak value of the common-mode voltage (CMV) in one PWM cycle can be reduced to one third of the dc bus voltage, even despite of the dead-time effect. And in the low voltage region, not only the CMV but also the current ripple is restrained effectively. In the entire voltage range, the linear modulation region is not limited and the switching loss is reduced because of fewer switching actions. The validity of the proposed technique is verified through simulation and experimental results. [ABSTRACT FROM AUTHOR]

Research on applying selective harmonic elimination pulse width modulation (SHE-PWM) to high power converters has drawn tremendous interest, due to the advantages of low switching frequency and high output harmonic performance. In the fields of high power converters such as variable speed traction motor drives and static synchronous compensators (STATCOM), the adoption of high voltage but slow speed semiconductor devices, i.e., IGBT/IGCT, results in a longer dead time of several microseconds, which leads to a motor vibration in the former case or the distortion of grid current in the latter case. This paper analyzes in detail the mechanism of the dead-time effect on 3-level SHE-PWM with different operating conditions considered. For the first time, a general mathematical model describing the relationship between the dead time and harmonic distribution of SHE-PWM wave is established. Based on which an open-loop compensation method by inserting a margin time into the effective switching angles is proposed. Furthermore, a closed-loop controller that implements online adaptive adjustment of the margin time is designed in case of a variable frequency application. The effectiveness of the proposed method in different scenarios is verified through simulation results. [ABSTRACT FROM AUTHOR]

This paper proposes a scheme that can compensate for the nonlinear characteristics of voltage source inverters (VSIs) for low-voltage delta-connected induction motors (IMs). Due to the nonlinearity introduced by the dead-time, the on/off delay, and the voltage drop across the power device, the output voltage of VSIs is seriously distorted, causing distortion in the phase current of the IM, which will lead to output torque ripple. However, the existing compensation methods for three-phase VSIs are derived from star-connected loads, or ignore the conducting properties of power devices. Moreover, the current polarity detection near the current zero is quite complex. In this paper, by taking such nonlinear characteristics into consideration, especially the conducting property of metal-oxide-semiconductor field effect transistors (MOSFETs), an output voltage model of VSIs for low-voltage delta-connected induction motors is presented. After that, in view of the difficulty in detecting the line current polarity near the current zero which might lead to the wrong compensation, an advancing current crossing zero (ACCZ) compensation is proposed. Subsequently, a compensation scheme which combines the compensation based on the VSI output voltage model and ACCZ compensation is proposed. Finally, the proposed compensation scheme is implemented based on a digital signal processor (DSP) drive system. The experimental results show that the proposed scheme has better performance than the common method in terms of suppressing the effect of the nonlinear characteristics of VSI, which demonstrates that the proposed compensation scheme is feasible and effective for the compensation of the nonlinear characteristics of VSI for low-voltage delta-connected IMs. [ABSTRACT FROM AUTHOR]

The paper considers the problem of parameter identification of the surface mounted permanent magnet synchronous motor (SPMSM) with pulse width modulated (PWM) inverter in the presence of dead time of power switches and other nonlinear distortions. Parameter identification of the SPMSM is required for the tuning of the torque control loop, because in some cases, the exact values of phase resistances and inductances are not known. In the absence of nonlinear disturbances, the problem of SPMSM parameters estimation is not difficult. The influence of the dead-time effect, back electromotive force and measurements noise introduces distortions in experimental output data sets, which leads to incorrect parameter estimation. Thus, there is a need to develop new designs of identification experiments and methods of processing of the experimental data. A detailed mathematical model of SPMSM with a PWM inverter in the presence of dead-time effect is considered in the paper. The negative influence of the dead-time effect on the results of parameter estimation is shown. A modified technique of parameter identification of SPMSM based on the estimation of frequency response function is proposed. The applied design of identification experiments, the type of excitation input signal, and methods of data processing allow us to minimize the influence of nonlinear disturbances and to reduce the variance of estimation of frequency response function. These features provide a high performance of SPMSM parameters estimation. [ABSTRACT FROM AUTHOR]