828 results about "Sawtooth wave" patented technology

An LED driving device comprises a PWM IC including an RT/CT terminal operated by a power voltage and generating and outputting a sawtooth wave voltage of a predetermined frequency, a COMP terminal to which a comparison voltage compared with the sawtooth wave voltage is inputted, and an output terminal generating and outputting a pulse signal turned off in a section in which a level of the sawtooth wave voltage is higher than a level of the comparison voltage and turned on in a section in which the level of the sawtooth voltage is lower than the level of the comparison voltage. The LED driving device sets up the comparison voltage inputted to the COMP terminal of the PWM IC to be 0 when an error voltage corresponding to a difference between a both end voltage of an LED array and a predetermined reference voltage is less than a predetermined level.

The invention discloses a method for controlling brittleness Laves phases in the laser additive manufacturing process of a nickel-based high-temperature alloy. Firstly, laser additive manufacturing technological parameters are initially optimized, and a cooling medium is adopted for cooling the bottom of a base material; then a laser modulation technology is used for modulating a laser source, and superior laser modulation parameters are obtained, wherein the peak power of square waves ranges from 600 W to 1000 W, the pulse frequency of the square waves ranges from 10 HZ to 100 HZ, and the duty ratio of the square waves ranges from 0.3 to 0.6; the wave peak power of sawtooth waves ranges from 600 W to 1200 W, the wave trough power of the sawtooth waves is 0 W, and the pulse frequency of the sawtooth waves ranges from 10 HZ to 100 HZ; and according to the parameters of sine waves, the wave peak power ranges from 600 W to 1000 W, the wave trough is 0 W, and the pulse frequency ranges from 10 HZ to 100 HZ; and finally, laser additive manufacturing and forming of the nickel-based high-temperature alloy are conducted according to the above parameters, and a formed part with all small equiaxial dendritic structures and small discrete Laves phases is obtained. By means of the laser modulation method, the precipitation behavior of the Laves phases in the laser additive manufacturing process of the nickel-based high-temperature alloy can be effectively controlled, the cracking sensibility of parts obtained through laser additive manufacturing is reduced, and the microstructure is improved.

The invention relates to a control method for sharing voltage when inputting full load of an input-series-output-parallel combined converter. A sinusoidal modulation signal with a phase difference of Pi/n is increased on basis of the output signal vo_EA of a sharing output voltage regulator and the output signal vcd_EAi of each module input voltage-sharing regulator included in the drive signals of each input-series-output-parallel topology module control terminal. The increased sinusoidal modulation signal together with the signals vo_EA and vcd_EAi as a new error signal of each circuit is intersected with sawtooth waves VRAMPi inside a control chip to obtain a drive signal of each topology module switching tube, thereby controlling the ordered turn on and off of each topology module switching tube. The introduction of sinusoid with certain amplitude phase difference can obviously improve the problems that the duty cycle regulation space of some converter is lost and the problems caused by thereof when no-load or light-load. The control method of the invention has reasonable design, realizes the purposes of voltage-sharing and current-sharing under full load condition and is a control method with good stability and high reliability.

The invention discloses an onboard automatic speed measuring and height measuring radar system and a speed measuring and height measuring method. The system comprises an antenna, a transmitter, a superhet receiver, a broadband digital intermediate-frequency receiver, a center computer and a power module. The transmitter generates four sawtooth wave linear frequency modulation radio-frequency signals and achieves space symmetric configuration through the antenna; the superhet receiver and the broadband digital intermediate-frequency receiver complete echo signal digital demodulation together and calculate the frequency, amplitude, phase and signal-to-noise ratio information of echo signals; the center computer separates the speed information and the height information of the same echo beam by applying Doppler principle directivity based on the space symmetry and the timing sequence relevance of four beams, and the information is used for calculating the flight speed value and the flight height value of an aircraft. According to the onboard automatic speed measuring and height measuring radar system and the speed measuring and height measuring method, the same radar can be used for automatically measuring the speed and the height, the structure of an aircraft avionics system is simplified, the measuring precision is high, and the onboard automatic speed measuring and height measuring radar system and the speed measuring and height measuring method can be used for measuring carrier aircraft flight parameters.

The invention belongs to the technical field of power sources and relates to a self-adaptation voltage regulator circuit. The self-adaptation voltage regulator circuit comprises a power tube MP, a power tube MN, an inductor L, a capacitor C, a first resistor RF1, a second resistor RF2, a simulation phase lead compensation module, a delay phase lag compensation module, a critical path duplication module, a sawtooth wave generating module, a comparator and a power tube driver. The output voltage Vout is partitioned by the first resistor RF1 and the second resistor RF2. Simulation phase lead compensation is achieved through an operational amplifier, the resistor R1, the resistor R2 and the capacitor C. A load of an operational transconductance amplifier GM is RGM1 and provides the loop gain of APD compensation. The delay of the duplication of the critical path is compared with a system clock CLK through phase detection. Then, delay error signals are integrated through a charge pump. The output voltage VPD of the charge pump is connected to the positive going input end of the operational transconductance amplifier GM. PWM waveforms can be obtained by comparing the sawtooth wave current generated by an oscillator OSC and the output current of the GM. By means of the self-adaptation voltage regulator circuit, the power loss of a digital circuit is greatly reduced.

The invention discloses a constant-on-time primary side constant-current control device for an LED driver with a high power factor. The existing constant-current control device is easy to have the problem of optocoupler aging and has more complex circuits. In the invention, the output end of a peak sample and hold circuit is connected with the input end of a secondary side current analog module, the output end of the secondary side current analog module is connected with the input end of an average current loop, the output end of the average current loop is connected with the input end of a comparison module, the other input end of the comparison module is connected with the output end of a sawtooth wave generation module, the output end of the comparison module is connected with the input end of a drive pulse generation module, the other input end of the drive pulse generation module is connected with the output end of an inductive current zero-crossing detection module, and the output end of the drive pulse generation module is connected with a driver module. By means of the device of the invention, the high power factor and output constant current control can be realized.

Provided is a small-sized load drive system which, even with three three-phase inverters, significantly reduces noise regardless of control duty ratio. The load drive system includes three-phase inverters 301 to 303, and first, second, and third control units 401 to 403. The inverters 301 to 303 are connected to loads 211 to 213, respectively. The first control unit 401 generates sawtooth wave voltage and controls the inverter 301 according to the sawtooth wave voltage. The second control unit 402 generates inverse sawtooth wave voltage and controls the inverter 302 according to the inverse sawtooth wave voltage. The third control unit 403 generates triangular wave voltage which has ramps respectively equal to the sawtooth/inverse sawtooth wave voltage and either has a same phase or is out of phase by half a period relative to the sawtooth/inverse sawtooth wave voltage, and also controls the inverter 303 according to the triangular wave voltage.

A stable, high-speed, high-efficiency constant voltage is provided without a complicated, large-scale, high-cost phase compensation circuit over a wide range of operating conditions. This voltage buck-boost switching regulator consists of a pair of voltage reducing transistors, a pair of voltage boosting transistors, inductance coil, output capacitor and controller. The controller has the following parts for performing PWM control of constant voltage for voltage reducing transistors and voltage boosting transistors: an output voltage feedback circuit, an inductor current sense circuit, a variable sawtooth wave signal generator, switching controllers, and a voltage boosting driver.

The invention provides a step-down converter. The converter comprises a power supply module, a switch power tube, a rectifying tube, an error amplifier, a bandgap reference circuit, a first voltage comparator, a sawtooth wave generating circuit and a pulse width modulation control circuit. The rectifying tube is connected in series with the switch power tube and is further connected to the power supply module. An input voltage is input through the switch power tube and the rectifying tube. The power supply module is used to provide power for a load. The pulse width modulation control circuit is connected to an output terminal of the first voltage comparator, the sawtooth wave generating circuit and the bandgap reference circuit so as to receive a first control signal generated by the first voltage comparator, a sawtooth wave signal and a reference voltage, generate a corresponding second control signal and output the second control signal to the switch power tube and the rectifying tube. The pulse width modulation control circuit comprises a soft start circuit so as to generate a soft start control signal so that the step-down converter is in a soft start mode.

The invention relates to an alternating current contactor intelligent control module with a high speed pulse width modulation function. The alternating current contactor intelligent control module comprises an alternating current/direct current (AC/DC) power supply, the AC/DC power supply supplies power for an alternating current contactor coil sequentially through a rectification filter circuit and an electronic power switch, and the alternating current contactor intelligent control module further comprises a voltage sampling circuit, a single chip microcomputer control system, a double-way digital-analog (DA) switching circuit, a sawtooth wave generating circuit, a square wave clock signal, a high speed pulse width modulator, a bootstrap circuit, a compensating circuit, a switching point detection circuit, a hall current sensor, a follow current circuit, a low voltage maintaining loop and an automatic constant voltage/constant current switching circuit. According to the alternating current contactor intelligent control module with the high speed pulse width modulation function, a novel Buck structure is used as a coil power level topology, orders of a power level circuit are lowered, a system is easy to stabilize, the compensating circuit is easy to design, the hall current sensor is used for current sampling, the impedance characteristic of a coil power level circuit is not changed, advantages of high accuracy, isolation characteristics, large bandwidth and the like of a current sensor are fully utilized, and closed-loop control with the isolation characteristics is formed.

The invention discloses a high-precision sectional type linear slope compensation circuit, which comprises a sectional type slope compensation signal generation circuit, a sectional type control signal generation circuit, a sawtooth wave generation circuit and a trigger circuit. Through the sectional type design of the slope compensation signal generation circuit and the control signal generationcircuit, when the working duty ratio of a converter is at any condition, the slope complexity can be flexibly controlled, and the current feedback capability, transient response characteristic and load capacity of the converter are ensured; and through regulating the intrinsic standoff ratio and the width-length ratio of a relative metal oxide semiconductor (MOS) tube, the ideal slope compensation signal waveform can be adjusted, the signal anti-jamming performance is strong, so the high-precision sectional type linear slope compensation circuit can be widely applied in peak current mode control direct current/direct current (DC/DC) converters.

The invention provides an SVPWM modulation method which belongs to three-part modulation methods. The method comprises the steps that in the process of calculating Tk, Tk+1 and T0 of SVPWM modulation waves, the influences of the amplitude and output frequency of an inverter are not considered, only the number n of the SVPWM modulation waves in each section is considered, regular sampling is carried out on modulation signals Pk, Pk+1 and P through unit right-angle sawtooth waves with the period being pi/3n, and a table is made; the angle ratio of a nonzero vector to a zero vector adjacent to the nonzero vector in the modulation wave is obtained by looking up the table, then the angle ratio is multiplied by a modulation period Ts and an amplitude coefficient a, and the obtained result is the Tk, Tk+1 and T0 of the SVPWM modulation period; then, the Tk, Tk+1 and T0 are used as input, Vk, Vk+1 and V0 are used as output, and a driving wave of an SVPWM modulation inverter bridge can be generated through combinational logic. According to the SVPWM modulation method, the problem that a large amount of complex computation exists in a traditional SVPWM modulation process can be solved.

The invention discloses a device and a method for detecting the concentration of human respiration marking gas on line by a laser absorption spectroscopy technology. The device is characterized in that a laser temperature control plate and a laser current control plate are used for controlling a DFB (distributed feedback) laser device; a signal generator is used for generating sawtooth waves and sine waves; laser with the specific absorption wavelength is output by the laser device and collimated by an optical fiber collimator, enters a light-sound gas pool, and is reflected for multiple times by two high-reflectivity concave mirrors to interact with gas to be detected; a light-sound signal detected by a microphone is transmitted to a front amplifier, enters a phase-lock amplifier and is finally acquired and processed by a computer and a data acquisition card. The method is characterized in that a tester blows air into a vapor drying bottle through a respiration air nozzle to remove vapor and the air enters the light-sound gas pool, and an air pressure control pump, a temperature detection meter and a pressure detection meter are used for controlling the pressure in the pool and acquiring the temperature and the pressure for inverse concentration calibration. The device is unique in design and novel in structure; the in-situ online detection is performed, the complexity of other detection technologies is avoided, and the detection precision is improved.

The invention relates to a multicycle random digital impulse width modulation circuit and a method thereof. The multicycle random digital impulse width modulation circuit comprises a multicycle random digital impulse width modulation module, a linear feedback shift register module and a multiplexer module; wherein, the multicycle random digital impulse width modulation module is connected with the linear feedback shift register module which is connected with the multiplexer module. The multicycle random digital impulse width modulation method is split jointed a forward-directional toothed wave and back-directional toothed wave. The technical scheme of the invention can choose one among toothed wave, pyramidal wave and random impulse width modulation according to the requirements, thereby having great flexibility. The realization of the random impulse width modulation can realize frequency spectrum spreading, thereby effectively reducing the EMI conduction and radiation level of DPWM.

The invention relates to a two-sided modulation type pulse width modulation controller performed and a method thereof. The control process of the two-sided modulation type pulse width modulation controller comprises the following steps: a first adder adds a supplement signal and a triangular wave or sawtooth wave signal; a second adder adds a current feedback signal and an offset value; the same-phase end of a comparer receives an output signal of the first adder, and the reverse-phase end of the comparer receives an output signal of the second adder so as to output a pulse width modulation waveform. The control mode of the two-sided modulation type pulse width modulation controller also has the advantages of current control and can also faster respond to transient change.

The present invention relates to a switch control circuit, a switch control method, and a converter using the same. An input voltage of a converter is provided to an inductor, and an output voltage is generated by an inductor current caused by the input voltage. A switch control circuit for controlling a switching operation of a power switch connected to the inductor to control the inductor current senses a drain current flowing to the power switch while the power switch is turned on, and controls a slope of a sawtooth wave signal for determining a turn-off time of the power switch according to the sensed drain current.

The invention discloses a VCSEL (vertical cavity surface emitting laser)-based low-power-consumption gas detection method and device. The method comprises the following steps that: a microprocessor controls a sawtooth wave current driving circuit to drive a VCSEL to generate light with specified wavelength in the first step; the light emitted from the VCSEL reaches an optical fiber sensing probe and a reference air chamber through a light path; and an optical signal with concentration information enters a photoelectric conversion circuit and is converted into a corresponding analog voltage signal by the photoelectric conversion circuit, the analog voltage signal is converted into a digital voltage signal which can be identified by the microprocessor through an analog/digital (A/D) conversion circuit, a temperature measurement circuit transmits a measured environment temperature value to the microprocessor, and thus the microprocessor obtains the wavelength of the light emitted from the VCSEL in case of a given driving current and calculates a field gas concentration signal according to a Beer-Lambert law. The method has the advantage of implementing the gas concentration detection at low power consumption.