Pulse-frequency modulation

About: Pulse-frequency modulation is a research topic. Over the lifetime, 4151 publications have been published within this topic receiving 53039 citations. The topic is also known as: PFM.

FPGA-based combined PWM-PFM technique to control DC-DC converters

Abstract: This paper describes a combined Pulse Width Modulation (PWM)-Pulse Frequency Modulation (PFM) technique implemented in a Field Programmable Gate Array (FPGA) to control DC-DC converters. This technique changes the mode of operation from PWM to PFM with the change in the load condition. The efficiency of the proposed technique is determined by implementing a DC-DC converter and calculating the conduction losses, switching losses, and ripple voltages at different load values. Furthermore, the efficiency of the converter based on the proposed technique is compared to the efficiency of processor-based implementation. The results show that the efficiency of the converter with the FPGA-based technique is higher than the efficiency of the converter with processor based technique.

Pulse modulation system of electric communication

Abstract: The present invention relates to pulse modulation systems of electric communication. In communication systems of this type the intelligence to be transmitted is carried by a train of electrical pulses which are, from a broad aspect, time modulated in accordance with the instantaneous amplitudes...

Fixed-frequency control circuit and method for pulse width modulation

Abstract: A fixed-frequency control circuit and method detect the difference between the frequency of a pulse width modulation signal and a target frequency to adjust a current used to determine the on-time or off-time of the pulse width modulation signal, such that the frequency of the pulse width modulation signal is stable at the target frequency.

Phase-locked loop frequency modulation circuit for input modulation signals having low-frequency content

Abstract: A phase-locked loop frequency modulation circuit that compensates for the inability of a phase-locked loop to pass low-frequency content of an input modulation signal, and that may be utilized with existing communication apparatus, such as a cellular telephone voice radio, for accurate data transmission without having to modify such apparatus, includes a compensation circuit (50) for processing an input modulation signal (72) to provide a compensation signal (78) that is added to a loop filter output signal (70) by processing the input modulation signal to provide the same effect as adding the input modulation signal to an integrated input modulation signal (74) that is filtered by a filter (54) having the same transfer function as the loop filter (46) to provide the compensation signal.

Design and implementation of a series resonant solid state transformer

Abstract: The focus of this study is on the design of a full-bridge unidirectional resonant LLC Solid State Transformer. The proposed topology uses a high-frequency transformer to optimize the size and weight of the converter. This converter has the capability of operating at fluctuating load conditions while it keeps the voltage regulated in different operation point. The converter is designed to maintain soft switching by using a resonant circuit in this design to minimize the switching loss of the high frequency converter. ZVS in the leading leg for turn on mode and ZCS commutation in the lagging leg for all of the modes are achieved in the H-bridge through the suggested circuitry which is analyzed mathematically in detail in this study. A combination of Pulse frequency modulation (PFM) and Phase Shifting Modulation (PSM) are utilized to control this resonant converter. The experimental setup for the suggested configuration was implemented and the results of the simulation and calculations have been verified with test results. The hardware set up was tested with two different power levels and the output results confirm that the control method works properly to feed the load and keeps the converter working in the expected frequency range and maintaining the soft switching to decrease switching loss. The results shows conversion efficiency of 97.18% is achieved.