This paper proposes a new concept of synthesized voltage vector to address dead-time effect issue for Finite Control Set Model Predictive Control(FCS-MPC)technique.For a voltage source inverter(VSI),dead-time is inevi...This paper proposes a new concept of synthesized voltage vector to address dead-time effect issue for Finite Control Set Model Predictive Control(FCS-MPC)technique.For a voltage source inverter(VSI),dead-time is inevitably inserted between the turn off and turn on instants of power devices to avoid short circuit phenomenon.The influence of dead-time leads to output voltage vector error of three-phase inverters.Furthermore,it will result in computing deviation in cost function,and will deteriorate the performance of the system if not properly dealt with.In this paper,the problem is clearly analyzed,and the solution to this issue is proposed by introducing a synthesized voltage vector.The proposed solution is verified by Hardware-in-the-loop(HiL)test in real time,and results validate the effectiveness of the proposed solution.展开更多
The key of speed sensorless vector control system lies in the accurate orientation of magnetic field. In some field-oriented algorithms, the integrator of observers and the dead-time effect bring in system errors duri...The key of speed sensorless vector control system lies in the accurate orientation of magnetic field. In some field-oriented algorithms, the integrator of observers and the dead-time effect bring in system errors during the estimation of field position. In this paper, a saturated feedback integrator is used, and the dead-time effect is compen- sated by current positive feedback. Experiments were carried out on the hardware platform of MCK2407, with chip TMS320LF2407 from TI Company. The results show that the prooosed method is simole and effective, and the accuracy of field position is improved.展开更多
In the inverter circuit,there exists a specific on-off time in each power transistor.As such,to prevent a short circuit of the two switch devices on the upper and lower bridge arms,a specific dead time must be set in ...In the inverter circuit,there exists a specific on-off time in each power transistor.As such,to prevent a short circuit of the two switch devices on the upper and lower bridge arms,a specific dead time must be set in the pulse width modulation(PWM)and the sinusoidal pulse width modulation(SPWM)signals.In this paper,an intellectual property(IP)core that can introduce a high-precision dead time of arbitrary length into PWM or SPWM signals of the inverter is designed to increase the precision,convenience and generalization of dead time control,resulting in a boosted control accuracy of up to 10 ns.Moreover,the added Avalon bus enables IP cores to be accessed by the field programmable gate array(FPGA)processor in a standard manner and multiple IP cores of the same class can be easily incorporated.In addition,an application for setting and compensating for dead time in a three-phase inverter based on system on programmable chip(SOPC)technology is presented.With the Nios II CPU as its core,the system adopts the mean voltage compensation method to calculate the compensation voltage,and performs dead-time compensation in a feed-forward manner.The three dead-time IP cores are controlled by Avalon bus.These allow the dead time of three groups of power transistors to be accurately controlled and flexibly adjusted.The system also features the master computer communication function while boasting the advantages of flexible control,high precision and low cost.展开更多
Subsynchronous resonance(SSR)and high-frequency resonance(HFR)are two phenomena that exist in a doubly fed induction generator(DFIG)system operated in a weak grid.Besides the aforementioned resonance,dead-time in the ...Subsynchronous resonance(SSR)and high-frequency resonance(HFR)are two phenomena that exist in a doubly fed induction generator(DFIG)system operated in a weak grid.Besides the aforementioned resonance,dead-time in the converter(rotor side converter(RSC)and grid side converter(GSC))of the DFIG system can cause resonance at middle frequencies.The aforementioned resonance at middle frequencies can greatly degrade dynamic performance and cause instabilities in the DFIG system.Nevertheless,there is not enough research available in existing literature on resonance in the DFIG system,considering dead-time impact.This paper proposes a new method of resonance analysis in a DFIG system,taking dead-time effect into consideration and utilizing small-signal impedance modeling.Dead-time of the RSC and GSC will introduce distorted voltage into the rotor-and stator-side of the DFIG.Then,rotor-side impedance is modified by adding the effect of transfer function(impedance)from the distorted voltage to rotor current.Likewise,the stator-side impedance is modified by adding the effect of the transfer function(impedance)from distorted voltage to stator current.Thus,overall DFIG system impedance,as seen from the point of common coupling is changed.Finally,resonance is revealed by plotting the DFIG system impedance and weak grid impedance on the Bode plot.Additionally,resonance mitigation is impedance on the Bode plot.Additionally,resonance mitigation is exposed through the dead-time compensation(DTC)technique using an adaptive second-order bandpass filter.With the proposed technique,the resonance at middle frequencies is damped with zero probability of resonance reoccurrence.Finally,the validity and the accuracy of the proposed DTC techniques are validated using mathematical analysis and simulations in Matlab.展开更多
Although the dead-time optimization design of resonant converters has been widely researched,classical design methods focus more on achieving zero-voltage switching(ZVS)operation.The body diode loss is always ignored,...Although the dead-time optimization design of resonant converters has been widely researched,classical design methods focus more on achieving zero-voltage switching(ZVS)operation.The body diode loss is always ignored,which results in low-efficiency of the converter,especially,in energy router(ER).To deal with this problem,this paper proposes an adaptive deadtime modulation scheme for bidirectional LLC resonant converters in ER.First,the power loss of the MOSFET is analyzed based on the dead-time.Then,a novel dead-time optimization modulation principle is proposed.It can eliminate the body diode loss of MOSFET compared with existing literature.Based on the optimization modulation principle,this paper proposes an adaptive dead-time modulation scheme.To this end,the converter adopting the scheme no longer needs to calculate dead-time,which simplifies the parameter design process.Meanwhile,this scheme enables dead-time to dynamically change with working conditions according to the dead-time optimization modulation principle.With these effects,the ZVS operation is achieved,and the body diode loss of MOSFET is also eliminated.Furthermore,a digital implementation method is designed to make the proposed modulation scheme have fast-transient response.Finally,experimental results show that the proposed dead-time modulation scheme enables converters to achieve ZVS operation in all working conditions,and has higher efficiency than classical dead-time design methods.展开更多
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 suppress...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 zerocrossing 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.展开更多
随着双有源桥(Dual active bridge,DAB)变换器工作频率的不断提高,开关损耗对传输效率的影响也在不断增加。DAB变换器通过采用合适的软开关控制策略,来尽可能实现全开关器件的软开关,但轻载工况下的死区重叠现象使软开关条件产生了冲突...随着双有源桥(Dual active bridge,DAB)变换器工作频率的不断提高,开关损耗对传输效率的影响也在不断增加。DAB变换器通过采用合适的软开关控制策略,来尽可能实现全开关器件的软开关,但轻载工况下的死区重叠现象使软开关条件产生了冲突,这种现象在高频轻载条件下尤为突出。为了提高DAB变换器在高频轻载条件下的能量传输效率,对轻载条件下的死区重叠现象进行了分析,结合缓冲电容对死区过程的影响,提出了以电流应力为优化目标的三自由度控制策略。最后,通过试验验证了分析过程的正确性和所提控制策略的有效性。展开更多
为了减少模型预测控制中因死区时间引起的电压和定子电流的误差,在永磁同步电机(permanent magnet synchronous motor,PMSM)模型预测电流控制(model predictive current control,MPCC)基础上采用了一种基于死区电压矢量的优化MPCC方法(d...为了减少模型预测控制中因死区时间引起的电压和定子电流的误差,在永磁同步电机(permanent magnet synchronous motor,PMSM)模型预测电流控制(model predictive current control,MPCC)基础上采用了一种基于死区电压矢量的优化MPCC方法(dead-time voltage vector based MPCC,DTVV-MPCC)。首先介绍了死区时间对MPCC的影响,分析了MPCC中存在的死区电压矢量(dead-time voltage vector,DTVV)的形成过程。其次区分了MPCC性能的有利DTVV和非有利DTVV,并分析了有利DTVV的优势。最后优化了死区作用时间。仿真结果表明该控制方法下的电流稳态控制性能要优于传统的MPCC方法。展开更多
逆变器中死区时间会带来电流谐波和转矩脉动,从而导致感应电机出现明显振动并增加额外损耗。为减少逆变器死区效应带来的不利影响,提出一种基于高阶扩展状态观测器(high-order extended state observer,HO-ESO)的逆变器死区效应在线补...逆变器中死区时间会带来电流谐波和转矩脉动,从而导致感应电机出现明显振动并增加额外损耗。为减少逆变器死区效应带来的不利影响,提出一种基于高阶扩展状态观测器(high-order extended state observer,HO-ESO)的逆变器死区效应在线补偿方法。首先,对逆变器死区效应进行分析,推导出因死区效应而产生的d、q轴误差电压方程。接着,对传统的基于二阶ESO的死区效应补偿方法进行介绍和分析,由分析结果可知,该方法难以准确估计误差电压,从而导致补偿效果欠佳。进一步,设计一种HO-ESO对误差电压进行估计,并将其补偿到感应电机矢量控制系统中。最后,利用仿真和实验测试对所研究的死区效应补偿方法进行验证,并与传统的基于二阶ESO的死区效应补偿法进行对比。测试结果表明,相较于传统基于二阶ESO的死区效应补偿方法,所研究方法表现出更好的死区效应补偿性能。此外,所研究方法无需检测电流极性,易于实施。展开更多
文摘This paper proposes a new concept of synthesized voltage vector to address dead-time effect issue for Finite Control Set Model Predictive Control(FCS-MPC)technique.For a voltage source inverter(VSI),dead-time is inevitably inserted between the turn off and turn on instants of power devices to avoid short circuit phenomenon.The influence of dead-time leads to output voltage vector error of three-phase inverters.Furthermore,it will result in computing deviation in cost function,and will deteriorate the performance of the system if not properly dealt with.In this paper,the problem is clearly analyzed,and the solution to this issue is proposed by introducing a synthesized voltage vector.The proposed solution is verified by Hardware-in-the-loop(HiL)test in real time,and results validate the effectiveness of the proposed solution.
文摘The key of speed sensorless vector control system lies in the accurate orientation of magnetic field. In some field-oriented algorithms, the integrator of observers and the dead-time effect bring in system errors during the estimation of field position. In this paper, a saturated feedback integrator is used, and the dead-time effect is compen- sated by current positive feedback. Experiments were carried out on the hardware platform of MCK2407, with chip TMS320LF2407 from TI Company. The results show that the prooosed method is simole and effective, and the accuracy of field position is improved.
基金Supported by the National Natural Science Foundation of China(61961016)the Natural Science Foundation of Hubei Province(2019CFB593)PhD Research Start-Up Foundation of Hubei Minzu University(MY2018B08)
文摘In the inverter circuit,there exists a specific on-off time in each power transistor.As such,to prevent a short circuit of the two switch devices on the upper and lower bridge arms,a specific dead time must be set in the pulse width modulation(PWM)and the sinusoidal pulse width modulation(SPWM)signals.In this paper,an intellectual property(IP)core that can introduce a high-precision dead time of arbitrary length into PWM or SPWM signals of the inverter is designed to increase the precision,convenience and generalization of dead time control,resulting in a boosted control accuracy of up to 10 ns.Moreover,the added Avalon bus enables IP cores to be accessed by the field programmable gate array(FPGA)processor in a standard manner and multiple IP cores of the same class can be easily incorporated.In addition,an application for setting and compensating for dead time in a three-phase inverter based on system on programmable chip(SOPC)technology is presented.With the Nios II CPU as its core,the system adopts the mean voltage compensation method to calculate the compensation voltage,and performs dead-time compensation in a feed-forward manner.The three dead-time IP cores are controlled by Avalon bus.These allow the dead time of three groups of power transistors to be accurately controlled and flexibly adjusted.The system also features the master computer communication function while boasting the advantages of flexible control,high precision and low cost.
基金supported by the National Natural Science Foundation of China(51577025)the Science and Technology Program of State Grid Corporation of China(5100-201999330A-0-0-00).
文摘Subsynchronous resonance(SSR)and high-frequency resonance(HFR)are two phenomena that exist in a doubly fed induction generator(DFIG)system operated in a weak grid.Besides the aforementioned resonance,dead-time in the converter(rotor side converter(RSC)and grid side converter(GSC))of the DFIG system can cause resonance at middle frequencies.The aforementioned resonance at middle frequencies can greatly degrade dynamic performance and cause instabilities in the DFIG system.Nevertheless,there is not enough research available in existing literature on resonance in the DFIG system,considering dead-time impact.This paper proposes a new method of resonance analysis in a DFIG system,taking dead-time effect into consideration and utilizing small-signal impedance modeling.Dead-time of the RSC and GSC will introduce distorted voltage into the rotor-and stator-side of the DFIG.Then,rotor-side impedance is modified by adding the effect of transfer function(impedance)from the distorted voltage to rotor current.Likewise,the stator-side impedance is modified by adding the effect of the transfer function(impedance)from distorted voltage to stator current.Thus,overall DFIG system impedance,as seen from the point of common coupling is changed.Finally,resonance is revealed by plotting the DFIG system impedance and weak grid impedance on the Bode plot.Additionally,resonance mitigation is impedance on the Bode plot.Additionally,resonance mitigation is exposed through the dead-time compensation(DTC)technique using an adaptive second-order bandpass filter.With the proposed technique,the resonance at middle frequencies is damped with zero probability of resonance reoccurrence.Finally,the validity and the accuracy of the proposed DTC techniques are validated using mathematical analysis and simulations in Matlab.
文摘Although the dead-time optimization design of resonant converters has been widely researched,classical design methods focus more on achieving zero-voltage switching(ZVS)operation.The body diode loss is always ignored,which results in low-efficiency of the converter,especially,in energy router(ER).To deal with this problem,this paper proposes an adaptive deadtime modulation scheme for bidirectional LLC resonant converters in ER.First,the power loss of the MOSFET is analyzed based on the dead-time.Then,a novel dead-time optimization modulation principle is proposed.It can eliminate the body diode loss of MOSFET compared with existing literature.Based on the optimization modulation principle,this paper proposes an adaptive dead-time modulation scheme.To this end,the converter adopting the scheme no longer needs to calculate dead-time,which simplifies the parameter design process.Meanwhile,this scheme enables dead-time to dynamically change with working conditions according to the dead-time optimization modulation principle.With these effects,the ZVS operation is achieved,and the body diode loss of MOSFET is also eliminated.Furthermore,a digital implementation method is designed to make the proposed modulation scheme have fast-transient response.Finally,experimental results show that the proposed dead-time modulation scheme enables converters to achieve ZVS operation in all working conditions,and has higher efficiency than classical dead-time design methods.
基金supported by the State Key Laboratory of Advanced Power Transmission Technology(GEIRI-SKL-2020-011)。
文摘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 zerocrossing 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.
文摘随着双有源桥(Dual active bridge,DAB)变换器工作频率的不断提高,开关损耗对传输效率的影响也在不断增加。DAB变换器通过采用合适的软开关控制策略,来尽可能实现全开关器件的软开关,但轻载工况下的死区重叠现象使软开关条件产生了冲突,这种现象在高频轻载条件下尤为突出。为了提高DAB变换器在高频轻载条件下的能量传输效率,对轻载条件下的死区重叠现象进行了分析,结合缓冲电容对死区过程的影响,提出了以电流应力为优化目标的三自由度控制策略。最后,通过试验验证了分析过程的正确性和所提控制策略的有效性。
文摘为了减少模型预测控制中因死区时间引起的电压和定子电流的误差,在永磁同步电机(permanent magnet synchronous motor,PMSM)模型预测电流控制(model predictive current control,MPCC)基础上采用了一种基于死区电压矢量的优化MPCC方法(dead-time voltage vector based MPCC,DTVV-MPCC)。首先介绍了死区时间对MPCC的影响,分析了MPCC中存在的死区电压矢量(dead-time voltage vector,DTVV)的形成过程。其次区分了MPCC性能的有利DTVV和非有利DTVV,并分析了有利DTVV的优势。最后优化了死区作用时间。仿真结果表明该控制方法下的电流稳态控制性能要优于传统的MPCC方法。
文摘逆变器中死区时间会带来电流谐波和转矩脉动,从而导致感应电机出现明显振动并增加额外损耗。为减少逆变器死区效应带来的不利影响,提出一种基于高阶扩展状态观测器(high-order extended state observer,HO-ESO)的逆变器死区效应在线补偿方法。首先,对逆变器死区效应进行分析,推导出因死区效应而产生的d、q轴误差电压方程。接着,对传统的基于二阶ESO的死区效应补偿方法进行介绍和分析,由分析结果可知,该方法难以准确估计误差电压,从而导致补偿效果欠佳。进一步,设计一种HO-ESO对误差电压进行估计,并将其补偿到感应电机矢量控制系统中。最后,利用仿真和实验测试对所研究的死区效应补偿方法进行验证,并与传统的基于二阶ESO的死区效应补偿法进行对比。测试结果表明,相较于传统基于二阶ESO的死区效应补偿方法,所研究方法表现出更好的死区效应补偿性能。此外,所研究方法无需检测电流极性,易于实施。
