577 results about "Pulse-position modulation" patented technology

The problem of charge leakage in the AC compensation filter for the error amplifier of a pulse width modulation (PWM)-based DC—DC converter is effectively obviated by controllably sampling and storing the voltage across the AC compensation filter, in response to a transition of the operation of a DC power supply from run or active mode to quiescent or sleep mode. The sampled voltage is retained as a compensation voltage throughout the quiescent mode, so that it will be immediately available to the PWM circuitry at the termination of the quiescent interval. This serves to ensure a relatively smooth (low noise) power supply switch-over during a subsequent transition from quiescent to active mode.

A method of balancing the voltage of DC links in a cascaded multi-level converter (CMC) semiconductor circuit, including the steps of providing a plurality of H-bridge converters per phase in the CMC circuit and utilizing a three phase duty cycle value from the main controller to determine a normalized duty cycle value, a ceiling duty cycle value and a floor duty cycle value. The normalized duty cycle value and an output current of the CMC is used to determine the direction and polarity of a capacitor current, and utilizing the capacitor current to determine a plurality of output capacitor voltages. A voltage summation result and direction is obtained from a ceiling index pointer and a floor index pointer and the voltage summation result, direction from the ceiling index pointer and a floor index pointer are used to create a combined switching table for the H-bridge converters. A pulse width modulator is utilized to balance the voltage of the DC links and thereby eliminate DC-capacitor voltage imbalance.

The invention discloses a percutaneous closed-loop control charging device for implantation type medical treatment instrument and belongs to the technical field of implantation medical instrument. The percutaneous closed-loop control charging device for implantation type medical treatment instrument comprises an external charger and an internal implantation type medical instrument. An external energy transmitting coil is a large-size flat magnetic core coil, and an internal energy receiving coil is a hollow coil; the external energy transmitting coil transmits electromagnetic energy by adopting a resonance electromagnetic coupling manner with parallel central shafts; and the electrical energy obtained by the internal energy receiving coil charges an internal rechargeable battery through an internal charge control circuit. The closed-loop control charging device communicates in a pulse position modulation manner for closed-loop control to ensure the energy received by the implantation medical instrument in different charging phases to be within the normal range, effectively control the heating and increase the safety; the closed-loop control charging device calculates the efficiency by the internal feedback parameter to realize counterpoint prompt and increase the charging efficiency. The percutaneous wireless charging method can charge the implantation type medical instrument by a titanium casing, is safe and reliable in charging, and can be applied to all types of implantation type medical instruments equivalent to a deep brain stimulator in power level.

Methods and systems for generating a variable spacing pulse position modulated (VSPPM) signal for transmission across an ultra-wideband communications channel. The variable pulse position modulated spread spectrum signal is created by encoding every M input data bits from an input data stream into a symbol consisting of N_c chips. Each chip is divided into 2^M sub-chips and each sub-chip is further divided into N_p time slots. A pulse is transmitted for each chip in the symbol. During each chip period, the pulse is placed in the sub-chip corresponding to the binary M-tuple (or symbol) value. A time hopping code sequence consisting of N_c elements with a one-to-one chip association is then applied to each symbol so that the position of each pulse is shifted to the appropriate time slot that corresponds to the time hopping code value.

A DC (direct current) converter includes a PWM (pulse width modulation) pulse generation unit outputting a PWM pulse signal whose duty ratio is controlled in accordance with an output voltage, a PFM (pulse frequency modulation) pulse generation unit outputting a PFM pulse signal whose pulse output interval is controlled in accordance with an output voltage, a selection circuit selecting and outputting any one of the PWM pulse signal and the PFM pulse signal in response to a selection signal, a drive circuit unit driving a load and generating an output voltage on the basis of a signal outputted from the selection circuit, and a switching control unit outputting the selection signal. When the selection signal is in a second state, the switching control unit detects a fact that the number of pulses of the PFM pulse signal in a measurement period increases to or above a set value of the maximum number of pulses, and switches the selection signal to a first state.

Methods and systems for processing an analog signal that is generated by a high energy photon detector in response to a high energy photon interaction. A digital edge is generated representing the time of the interaction along a first path, and the energy of the interaction is encoded as a delay from the digital edge along a second path. The generated digital edge and the delay encode the time and energy of the analog signal using pulse width modulation.

In a display device capable of low power and multi-color displaying without raising a frame rate due to increase of display gradations in number by combining a gradation representation through a FRC and a gradation representation system using a pulse width modulation or pulse height modulation method, the gradation representation is executed by a method of pulse width or pulse height modulation in one frame using lower significant N bits to a video signal of M bits, and the display of the gradations is performed by the FRC of the present invention using more significant M−N bits and further using 2^M−N−1 frames, and thus the number of the frames required for FRC is reduced to decrease a frame frequency to thereby realize a gradation display with reduction of electric power and suppression of flickers.

A radio-frequency-identification (RFID) system includes an RFID tag and an RFID reader, where the RFID reader is configured to communicate with the RFID tag using time-hopped pulse-position modulation and ultra-wideband modulation. The time-hopped pulse-position modulation includes sending from the RFID tag to the RFID reader a series of pulses in time slots selected by the RFID tag through a cryptographically secure pseudo-random generator.

A method of controlling an output voltage of a pulse width modulation (PWM) converter with a PWM signal driving a power switch of the converter may include using a comparator to compare a reference voltage with a scaled output voltage of the converter, incrementing or decrementing an up/down counter at each pulse of a clock signal applied to the counter depending on a state of the comparator, and controlling the comparator to generate the PWM signal with a control voltage selected from a look-up table using a value of the counter.

A boost DC/DC converter, including a mask circuit, a switched boost circuit, a pulse width modulation (PWM) circuit and an AND gate, is provided. The mask circuit is used to output a mask signal according to a load current. In the present invention, the system can selectively operate in the pulse width modulation mode, the pulse frequency modulation (PFM) mode or the mixed pulse mask mode according to the mask signal corresponding to the load current when the system is under light load, medium load or heavy load respectively, so as to achieve optimal system efficiency.

Pulse width modulation is provided for controlling a resonant power converter, particularly for dimming of light emitting diode arrays without loss of efficiency. Dynamic oscillation due to the beginning of a pulse width modulated pulse burst is limited by shortening of the first and/or last pulse of a pulse bust such that the first pulse of a subsequent pulse burst close to or to connect with a full load steady-state voltage/current trajectory of the power converter. Pulse shortening made be made substantially exact to virtually eliminate dynamic oscillation but substantial reduction in dynamic oscillation is provided if inexact or even performed randomly.

Present invention discloses pulse number modulation based atmospheric pressure glow discharge control method and circuit. Control method adopts pulse density modulation to generate alternate presented square wave pulsing signal to control inversion circuit switch tube on/off in glow discharge main circuit, each working period containing fixed quantitative square wave pulse, through keeping working period unchanged and changing working period square wave pulse number to control inversion circuit feeding energy time to load, realizing atmospheric pressure glow discharge load fixed frequently constant voltage control. The present invention can realize frequency follow-up control and linear power regulation to atmospheric pressure glow discharge type nonlinear variational capacitive loading.

The invention discloses a pulse width modulation (PWM) rectification, variable-voltage and variable-current pulse charging system of an electric vehicle and belongs to a large-size storage battery charging system. The system comprises a rectification module, a charging module and a direct current charging management module; the rectification module is respectively connected with an alternating current power grid and the charging module; the charging module consists of a direct current input module and a direct current output module; the rectification module, the direct current input module, the direct current output module and the direct current charging management module are mutually-independent modules and are contacted together through network buses. The PWM rectification, variable-voltage and variable-current pulse charging system of the electric vehicle has a simple structure, a small size and wide application ranges, can be applied to the charging of all lead-zinc storage batteries, and is applicable for large-scale promotion. Moreover, the charging time of the storage batteries is greatly shortened.

A class D power amplifier includes: a signal input terminal for receiving an analog signal; an analog signal processing unit for amplifying the analog signal; an integrating circuit for integrating the analog signal received from analog signal processing unit; a PWM circuit for providing pulse width modulation to an integration signal received from the integrating circuit, and outputting a resulting pulse width modulation signal having a duty ratio falling within a first duty ratio range; a duty ratio adjusting circuit for adjusting the pulse width modulation signal, received from the PWM circuit, to have a pulse width falling within a second duty ratio range narrower than the first duty ratio range; a first driver and a second driver each for processing the pulse width modulation signal received from the duty ratio adjusting circuit; and power transistors.