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 method and a system of parallel emission of multichannel carrier light signals. The system drives a direct numerical frequency synthesizer chip to generate a square signal through intellectualized control of a control terminal, wherein frequency and phase positions of the square signal are continuous and controllable, and the system outputs the square signal to control a light emitting diode (LED) to flicker in fixed frequency. During the working process of the LED, an LED drive module and an optical feedback module act together and enable the LED to output carrier light signals which are stable in power in long power mode, the optical feedback module feeds received LED power instability fluctuation back by using a photovoltaic conversion diode and restrains power fluctuation by being combined with the LED drive module, and furthermore the multichannel carrier light signals which are controllable in frequency and phase position are generated by arranging a multichannel square signal generator and an LED module in parallel. The whole system is intelligent and controllable, high in integration level, low in power consumption, stable and reliable in work, and wide in application scope, can be extended in multiple channels, and is an integrated carrier light generating system.

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.

The invention discloses a feedback circuit and electronic equipment for class D power amplifiers, relates to the technical field of power amplifiers and is used to solve the problems of complex design and high cost of the feedback circuit of the existing class D power amplifiers. Wherein, the feedback circuit includes a sampling circuit; the input end of the sampling circuit is connected to the power supply, the output end is connected to the input end of the waveform generator, the output end of the waveform generator is connected to the first input end of the comparator, and the signal generator is connected to the comparator The second input terminal of the comparator is connected, the output terminal of the comparator is connected with the input terminal of the power amplifier circuit, and the output terminal of the power amplifier circuit is used for outputting signals; wherein, the sampling circuit is used for filtering and dividing the voltage output by the power supply , the filtered and divided voltage adjusts the amplitude of the waveform generated by the waveform generator. The circuit provided by the invention can be used in electronic equipment using class D power amplifiers.

The invention provides a variable speed control device of a variable speed case, which can lead the variation ratio to stably return to a low ratio side even in a hybrid vehicle that an engine is stopped when in deceleration. The variable speed control device comprises a control unit (7); wherein, according to detecting signals from a variation ratio sensor (38) and a belt pulley revolution transmitter at a driving side (37), a control chart logged in a controlling chart registration part (7c) ensures the starting running speed of a belt pulley at the driving side after being returned and thedutyfactor of an actuator, and a control instruction is sent to the actuator (77) which changes the variation ratio through changing the groove width of the belt pulley at the driving side. The control instruction is set to be sent after an engine stopping instruction from a driving control part, the closer to a high ratio side the variation ratio is drew, the higher the starting running speed ofthe actuator is. Based on the control, the variation ratio is closer to the high ratio side, and the rotary speed change rate of the belt pulley at the driving side is higher, thus a big dutyfactor isprovided until the rotation of the belt pulley at the driving side stops, to lead the variation ratio to return to the low ratio side.

The invention discloses a clock generation circuit used in an analog-to-digital converter (ADC) with a high speed and high precision. The clock generation circuit comprises: a low noise amplification and shaping circuit, a pulse width controller, a DLL with pulse width calibration, a biphase non-overlapping clock generation circuit and a clock buffer. A voltage-controlled delay line (VCDL) with pulse width adjustment is designed in the DLL with the pulse width calibration. The VCDL can realize clock signal time delay and pulse width control based on a cascade group comprising same M improvement delay units. The DLL with the pulse width calibration and the biphase non-overlapping clock generation circuit together form a time-delay control and pulse width adjustment loop. Therefore, working sequences of an ADC sampling circuit and a quantizer can be synchronized and stable processing to an input clock duty ratio can be realized. By using the technical scheme of the invention, a bandwidth requirement to an ADC driving circuit can be reduced; difficulty for designing the system and power consumption can be reduced; realization precision of the ADC quantizer can be improved.

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 discloses a clock circuit with stable duty cycle and low jitter. The whole clock circuit is composed of a clock driving amplifier module, a charge pump module, an output clock falling edge trigger circuit module, an output clock rising edge trigger circuit module, an output clock waveform stabilization circuit module and a charge pump phase-locked loop module. The clock waveform stabilization circuit generates a complete output clock according to the edge control pulse generated by the rising edge and falling edge control circuit; the falling edge trigger circuit keeps the falling edge of the output clock consistent with the falling edge of the input clock; the rising edge trigger circuit can be based on the input clock. The duty cycle detection result is based on the falling edge of the output clock, and the position of the rising edge of the output clock is adjusted so that the duty cycle of the output clock is finally stabilized to 50%; the charge pump phase-locked loop receives the output clock of the output clock waveform stabilization circuit module, Generates high-speed low-jitter clock signals. The clock circuit can meet the stringent requirements for clock signals in high-frequency applications.

The invention discloses a digital control single-stage multi-clock phase interpolator with a stable duty cycle. The phase interpolator has input clock signals CKI and CKQ, comprises a digital controlselection unit, a digital phase interpolation unit and a data selector, and is mainly used in various high-speed clock data recovery acquisition systems to provide an accurate multi-phase clock in thesystems for the systems to select the optimal sampling clock phase. The digital control single-stage multi-clock phase interpolator with a stable duty cycle has a simple requirement for input, requires only two digital input high-low level signals with a phase difference, has a simple internal sequential control logic circuit, and can output a high-precision multi-phase clock with a constant dutycycle.

The invention discloses a control system for the stepless current limiting of a switch power supply. The system comprises a current limiting voltage control unit, a voltage loop controller, a current limiting current control unit, a current loop controller and a pulse width modulation unit; the output end of the pulse width modulation unit is connected with a DC (direct current) / DC main circuit of the switch power supply. The system also comprises a voltage sampling unit, a first filter, a current sampling circuit and a second filter. The control method for the stepless current limiting of the switch power supply is used for performing dual-closed loop control, namely voltage loop control on the outer loop and current loop control on the inner loop, on the DC-DC main circuit of the switch power supply, so the current limiting function of software is realized. Driving oscillation of a power switch caused by the current limiting is avoided, and the system has the characteristics of precise current limiting, capability of setting a current limiting point, reduction of output ripple wave voltage (peak-peak value noise voltage) under the current limiting condition, small system noise, high reliability and the like.

The invention relates to a high-saturation magnetic flux, high-direct current superposition and low-loss soft magnetic material and a preparation method thereof. The soft magnetic material comprises the following main components: 53.5 to 55 molar percent of Fe2O3, 4 to 9.5 molar percent of ZnO, and the balance of MnO; and based on the total weight of the main components, the soft magnetic material comprises the following auxiliary components: 0.01 to 0.05 weight percent of WO3, 0.005 to 0.03 weight percent of NiO, and 0.02 to 0.06 weight percent of ZrO2. The soft magnetic material has higher saturation magnetic flux density Bs in a wide temperature range and a larger difference between the saturation magnetic flux density Bs of the soft magnetic material and residual magnetic flux densityBr exists, power consumption is greatly reduced in the wide temperature range particularly, the superposition performance is high, and Curie temperature is relatively high, so that a plurality of electromagnetic parameters are matched more optimally, and the soft magnetic material is particularly suitable for realizing the higher and more stable electrical inductance function on various occasionswith large direct current superposition.