High frequency AC pulse density modulation theory and its application in hybrid electric vehicle drive system

According to HFAC features, a novel HFAC-pulse density modulation (PDM) converter has been proposed to control frequency, amplitude and waveforms of the low output frequency signals synthesized from the fixed frequency input link voltage for the drive system of a hybrid electric vehicle. In order to effectively control the proposed HFAC-PDM converter, the related control technique is also proposed, which is the zero voltage switching (ZVS) integral half cycle pulse integration modulation (IHCPIM) technique. Use of ZVS method prevents high switching losses, excessive device stress during switching and high values of dv/dt in the generated waveforms. From the theory analysis and simulation results, the proposed configuration permits flexibility in the choke of voltage levels in the HEV, freedom from acoustic noise, has high efficiency, faster system response, less the penalty of bulky components and higher energy density.