In this paper,a novel pulse density modulation(PDM)with semi-bridgeless active rectifier(S-BAR)in inductive power transfer(IPT)system for rail vehicle is proposed.It is to reduce switching losses of the active rectifi...In this paper,a novel pulse density modulation(PDM)with semi-bridgeless active rectifier(S-BAR)in inductive power transfer(IPT)system for rail vehicle is proposed.It is to reduce switching losses of the active rectifier in pickups.In the control method,the insulated-gate bipolar transistors(IGBTs)in the S-BAR are controlled by synchronous PDM signals,so that zero-voltage switching(ZVS)and zero-current switching(ZCS)can be achieved in the whole output power range.The output power is regulated by changing the pulse density(PD)of the S-BAR since the it is almost linear proportional with the PD in high quality factor of pickup side.The communication device between the primary side and pickup side is not necessary anymore.The detailed theoretical analyses of the PDM method are provided,and its advantages are shown in a 7.5kW IPT prototype for rail vehicle.The experimental results are presented to verify the analysis and demonstrate the performance.The overall efficiency of the system by PDM control is 74.2%which is improved by 4%compared with phase shift(PS)control at light load.展开更多
The paper analyzes power spectral density (PSD) of orthogonal pulse-based signals for time hopping ultra wideband (TH-UWB) systems. Our extensive studies show that the PSD of these signals not only depends on the time...The paper analyzes power spectral density (PSD) of orthogonal pulse-based signals for time hopping ultra wideband (TH-UWB) systems. Our extensive studies show that the PSD of these signals not only depends on the time dithering code and the modulation schemes, but also on the energy spectral density (ESD) of orthogonal pulses. The different order orthogonal pulses provide different ESD which changes the shape of continuous spectral component with symbols. We show that orthogonal pulse-based signals reduce the dynamic range of amplitude of discrete spectral components. Further, we reduce the dynamic range by adopting longer TH code over orthogonal pulse-based signals. As a result, UWB system performance improves with average transmitted power. The theoretical analysis of PSD of orthogonal pulse-based TH-UWB signal is provided in details and verified through simulation results.展开更多
介绍了脉冲密度调功(Pulse Density Modulation,简称PDM)的原理,由于PDM在品质因数较小时,负载电流波动很大,因此采用均匀PDM方法进行改进,推导出品质因数与谐振周期数的关系。通过给定品质因数,可以很方便地计算出一个工作周期内的最...介绍了脉冲密度调功(Pulse Density Modulation,简称PDM)的原理,由于PDM在品质因数较小时,负载电流波动很大,因此采用均匀PDM方法进行改进,推导出品质因数与谐振周期数的关系。通过给定品质因数,可以很方便地计算出一个工作周期内的最小脉冲密度,从而避免过小的电流流过负载,使负载电流连续,保证对负载谐振频率进行可靠跟踪。经过仿真和试验验证了该分析的正确性。展开更多
研究了基于脉冲密度调制(Pulse Density Modulation)控制策略的串联谐振逆变电晕处理电源。PDM的基本思想是在一定的调功周期内使交流输出端产生方波电压或者是零电平电压,这样即使电晕放电负载具有很强的非线性也可以宽范围内控制功率...研究了基于脉冲密度调制(Pulse Density Modulation)控制策略的串联谐振逆变电晕处理电源。PDM的基本思想是在一定的调功周期内使交流输出端产生方波电压或者是零电平电压,这样即使电晕放电负载具有很强的非线性也可以宽范围内控制功率输出。对于该电晕处理电源进行了仿真与实验,所得结果验证了理论分析。展开更多
文摘In this paper,a novel pulse density modulation(PDM)with semi-bridgeless active rectifier(S-BAR)in inductive power transfer(IPT)system for rail vehicle is proposed.It is to reduce switching losses of the active rectifier in pickups.In the control method,the insulated-gate bipolar transistors(IGBTs)in the S-BAR are controlled by synchronous PDM signals,so that zero-voltage switching(ZVS)and zero-current switching(ZCS)can be achieved in the whole output power range.The output power is regulated by changing the pulse density(PD)of the S-BAR since the it is almost linear proportional with the PD in high quality factor of pickup side.The communication device between the primary side and pickup side is not necessary anymore.The detailed theoretical analyses of the PDM method are provided,and its advantages are shown in a 7.5kW IPT prototype for rail vehicle.The experimental results are presented to verify the analysis and demonstrate the performance.The overall efficiency of the system by PDM control is 74.2%which is improved by 4%compared with phase shift(PS)control at light load.
文摘The paper analyzes power spectral density (PSD) of orthogonal pulse-based signals for time hopping ultra wideband (TH-UWB) systems. Our extensive studies show that the PSD of these signals not only depends on the time dithering code and the modulation schemes, but also on the energy spectral density (ESD) of orthogonal pulses. The different order orthogonal pulses provide different ESD which changes the shape of continuous spectral component with symbols. We show that orthogonal pulse-based signals reduce the dynamic range of amplitude of discrete spectral components. Further, we reduce the dynamic range by adopting longer TH code over orthogonal pulse-based signals. As a result, UWB system performance improves with average transmitted power. The theoretical analysis of PSD of orthogonal pulse-based TH-UWB signal is provided in details and verified through simulation results.
文摘介绍了脉冲密度调功(Pulse Density Modulation,简称PDM)的原理,由于PDM在品质因数较小时,负载电流波动很大,因此采用均匀PDM方法进行改进,推导出品质因数与谐振周期数的关系。通过给定品质因数,可以很方便地计算出一个工作周期内的最小脉冲密度,从而避免过小的电流流过负载,使负载电流连续,保证对负载谐振频率进行可靠跟踪。经过仿真和试验验证了该分析的正确性。
文摘研究了基于脉冲密度调制(Pulse Density Modulation)控制策略的串联谐振逆变电晕处理电源。PDM的基本思想是在一定的调功周期内使交流输出端产生方波电压或者是零电平电压,这样即使电晕放电负载具有很强的非线性也可以宽范围内控制功率输出。对于该电晕处理电源进行了仿真与实验,所得结果验证了理论分析。
