30results about How to "Stable duty cycle" patented technology

The invention discloses a numeric control method for a liquid level control (LLC) resonant conversion circuit. The method comprises the following steps of: sampling an LLC series resonant conversion circuit and an inverter electrically connected with the LLC series resonant conversion circuit respectively by adopting a single voltage loop numeric control structure; after calculation, outputting to a numeric controller; calculating the input quantity by using the numeric controller and outputting a driving pulse; controlling the LLC series resonant conversion circuit by using the driving pulse through a driving circuit; during light load or no load, adopting a mode of combining a pulse width modulation (PWM) control strategy and a pulse frequency modulation (PFM) control strategy; and during heavy load, adopting the PFM control. By the method, load states can be judged quickly; adverse influence on system load judgment due to different loading time is screened; a dynamic working point is selected reasonably according to the judged load state and current is controlled, so that the voltage stress of the LLC series resonant conversion circuit is eliminated; the control method provided by the invention is simple; and error and instability can be effectively reduced.

The invention discloses a phase type laser distance measuring system. The system comprises a laser for generating laser signals; an emission signal unit for generating emission signals and sending the emission signals to the laser after amplitude adjustment and power amplification are successively performed on the emission signals; a returning light receiving unit for receiving reflection signals of laser signals; a bias driving unit for providing offset voltages for driving the laser to emit the laser signals; and a controller for outputting PWM pulse voltage signals with an adjustable duty ratio to the bias driving unit to form the offset voltages and receive the emission signals. When the controller receives that the emission signals involves weak reflection, the controller reduces the duty ratio of the PWM pulse voltage signals and improves the amplitude of the emission signals in a linkage mode; and when the controller receives that the emission signals involves strong reflection, the controller increases the duty ratio of the PWM pulse voltage signals and reduces the amplitude of the emission signals in a linkage mode. The system provided by the invention has the advantages of simple system, high anti-interference capability and high distance measuring accuracy.

A method for measuring the threshold value of human nerve includes opening human skull, applying electric stimualting signal to the nerve to be measured, measuring the electromyographic signal of the muscle controlled by said nerve, and finding out the threshold value and relative parameters. Its system is composed of a nerve threshold stimulator, a digital electromyograph and a computer.

The invention provides a current sharing control method and device for an interleaved parallel PFC circuit and an air conditioner. The interleaved parallel PFC circuit comprises two symmetrically arranged PFC branches. The method comprises the following steps: acquiring the actual bus voltage, the target bus voltage and the total current of the interleaved parallel PFC circuit and the branch current of any PFC branch; obtaining the initial PWM signal having an initial duty cycle according to the actual bus voltage, the target bus voltage and the total current; and obtaining the current sharingPWM signal for driving the switching tubes of the two PFC branches according to the initial PWM signal and the branch current. The technical scheme can simply and effectively solve the problem of uneven current of the branches of the interleaved parallel PFC circuit and ensure that electrical appliances such as the air conditioner are in a reliable operation state.

The invention discloses a clock generation circuit for an analog-to-digital circuit, which comprises a clock stabilizing circuit and a two-phase non-overlapping clock generation circuit. The clock stabilizing circuit comprises a clock stabilizing loop and a feedback signal generation circuit. In the feedback signal generation circuit, a control signal is generated by an active low-pass filter to control an N tube current modulation inverter, the clock stabilizing loop is used for generating a stable clock signal, and by a filtering technology and a current modulation technology, accurate modulation on a feedback signal is implemented. In the clock stabilizing loop, by a loop structure, a duty ratio of an output clock can be reduced; under the regulation of the feedback signal, by pulling up a PMOS tube MP1, the duty ratio of the output clock is increased, and finally, the duty ratio of 50% of the output clock is achieved; and the clock is stabilized and vibration is reduced. According to the clock generation circuit disclosed by the invention, the clock stabilizing circuit can be integrated into an ADC circuit; and by adopting the structure disclosed by the invention, clock signal quality can be obviously improved, the strict requirement of an ADC for clock quality is reduced, and a signal-to-noise ratio of the ADC is improved.

The invention provides a method for modifying indium tin oxide electrochemiluminescence reaction electrodes. An ink spot-spray protective coating process is adopted as a film coating mode for the method which includes (1), covering the surface of each indium tin electrode with a discontinuous spot ink protective layer in an inkjet mode; (2), coating metal films on the surfaces, uncovered by the ink protective layer, of the indium tin oxide electrodes; (3), removing ink on the surfaces of the electrodes by the aid of a physical stripping process or a chemical stripping process, and covering the surface of each treated electrode with a latticed gold-plated layer jto enable the indium tin oxide electrodes to be high in surface adhesion property and electroconductivity; (4), fixing capture probe molecules to the surfaces of the modified electrodes in a physical adsorption manner or chemical coupling manner. The method has the advantages that the bonding strength of the electrodes and the probe molecules can be improved while the transparency and the electroconductivity of the indium tin oxide electrodes are guaranteed, surface hydrolysis of the electrodes can be resisted, and the stability of the electrodes can be improved.

The invention discloses a feedback circuit for a D type power amplifier and electronic equipment and relates to the technical field of power amplifiers. The problem that a feedback circuit of an existing D type power amplifier is complex in design and high in cost is solved. The feedback circuit comprises a sampling circuit. The input end of the sampling circuit is connected with a power supply. The output end of the sampling circuit is connected with the input end of a waveform generator. The output end of the waveform generator is connected with a first input end of a comparer. A signal generator is connected with a second input end of the comparer. The output end of the comparer is connected with the input end of a power amplifying circuit. The output end of the power amplifying circuit is used for outputting signals. The sampling circuit is used for carrying out smoothing and voltage dividing on voltage output by the power supply. The voltage obtained after smoothing and voltage dividing adjusts the range generated by the waveform generator. The circuit can be used in the electronic equipment of the D type power amplifier.

The invention provides an improved push-pull converter based on sliding mode control. The push-pull converter is improved on the basis of an original push-pull circuit. DC input voltage is directly imported to the midpoint of the secondary side of a transformer and is used to increase the secondary voltage of the transformer. Thus, the product output voltage is the sum of the input voltage and theconversion voltage of a power conversion circuit. The power conversion circuit only provides the difference between the input voltage and the output voltage. Such topology can significantly improve the efficiency of a product. In addition, the system uses voltage-current double loop control based on a sliding mode control algorithm, and designs a sliding mode surface according to desired dynamiccharacteristics. By designing a sliding mode control law, a controlled system converges along the sliding mode surface. Thus, good robustness, stability and dynamic quality of the system are guaranteed.