43results about How to "Control duty cycle" patented technology

The invention provides a rotating speed control method and device of a brushless DC fan, the brushless DC fan and a refrigerator. The rotating speed control method of the brushless DC fan comprises the following steps: detecting the real-time rotating speed of the brushless DC fan; comparing the real-time rotating speed with a target rotating speed; adjusting the current duty ratio of the driving voltage of the brushless DC fan according to the comparison result, so as to adjust the real-time rotating speed to be matched with the target rotating speed. According to the technical scheme, the rotating speed control method of the brushless DC fan has the advantages that the duty ratio of the driving voltage of the fan can be accurately controlled, thus the output voltage of the fan can be accurately controlled, and as a result, the accurate control of the rotating sped of the fan is realized, and the noise of the refrigerator is minimized.

A tunable, low power clock generator employs a voltage regulator, one or current generators and a variable resistor bank that, together, produce a control voltage for trimming a VCO. The control voltage is arranged to also compensate, at least, for the variables of temperature, supply voltage and fabrication processes as they affect the VCO output frequency. The current generator is well characterized over the variables discussed and the resistor bank is a flexible series/parallel array of resistors made from differing materials exhibiting different temperature coefficients. The resistor bank provides for various overlapping resistance values simultaneously with various overlapping temperature coefficients wherein the temperature coefficient profile of the clock generator over frequency and temperature is controlled.

The invention belongs to the field of LED (Light Emitting Diode) drive circuits and discloses an LED constant-current drive circuit and an LED lamp using the same. The LED constant-current drive circuit comprises a power supply, a filtering unit, a constant-current unit and a PWM (Pulse Width Modulation) unit, wherein the filtering unit is electrically connected between the power supply and the constant-current unit, the constant-current unit supplies a constant current to an LED, the PWM unit is electrically connected with the constant-current unit, and the PWM unit controls the constant-current unit through outputting a variable PWM pulse duty factor. The design of the circuit is simple and reliable, and the stepless dimming of the LED can be realized through only changing the variable PWM pulse duty factor output by the PWM unit, so that the circuit has the advantages of simplicity, convenience, stability and reliability.

The embodiment of the invention provides a soft start power supply circuit and a control method thereof, as well as a display device, relates to the technical field of display drivers, and aims to solve the problem of overshooting of power supply voltage output at the moment of starting. The soft start power supply circuit comprises a soft start module for pulling up the potential at a feedback voltage end to a potential at an input voltage end, or pulling down the potential at the feedback voltage end to a potential at a grounding end, a feedback operation module for controlling on and off of the driving module according to the voltage of the feedback voltage end, a driving module for outputting a signal of the input voltage end to a rectification and filtration module in a start state, the rectification and filtration module for rectifying and filtering the signal output by the rectification and filtration module and outputting the signal to an output voltage end, and a sampling module for sampling the signal of the output voltage end and outputting the signal to the feedback voltage end. The soft start power supply circuit is used for realizing soft start in a power supply voltage outputting process.

The invention discloses an FPGA zero-dynamic power consumption design method. A system clock tree and local clock trees are established. Clock management logic is established according to a state machine method and is established through the steps that functional logic or clock signal work of a clock drive source is identified as a work state, the function logic or the stagnation of the clock drive source is identified as a stop state, a hanging state used for judging the control method of a clock is established, and information interaction used for switching working modes and multiple systems or multiple clock domains is established. By setting the clock management logic based on state detection and clock drive control, the clock drive source for the corresponding functional logic is powered off, and the power consumption lowering design method for the 0Hz clock is achieved. Thus, the duty ratio of reactive power in the device is controlled, and the maximum efficiency for use of dynamic power consumption resources is achieved.

The invention discloses a series direct-current motor four-switch topological device and a control method thereof, and relates to the technical field of brushed direct-current motors. The series direct-current motor four-switch topological device comprises a full-bridge circuit, a center signal processing unit, a gate drive circuit and a flyback diode, wherein the full-bridge circuit comprises semiconductor switch elements. The full-bridge circuit which is composed of the semiconductor switch elements is utilized to control one of windings of the series direct-current motor, then the other winding is in series connection between the full-bridge circuit and bus directly, and the flyback diode is in parallel connection with the winding reversely. Since one of two power supply switches of the full-bridge circuit can be selected to control current direction of the windings connected to the full-bridge circuit, reversing of electromagnetic torque of the motor is realized.

The invention discloses a monocrystalline silicon surface composite microstructure based on full-band anti-reflection and a preparation method of the monocrystalline silicon surface composite microstructure. The preparation method comprises a part of or all of the following steps (1) - (4), and each step is executed for one or more times: (1) carrying out hydrophilic treatment on a silicon wafer,preparing a polystyrene sphere mixed solution, and paving a mask, polystyrene spheres, on the surface of the silicon wafer; (2) introducing oxygen for etching the wafer, and then introducing sulfur hexafluoride and octafluorocycloalkane for an etching-passivation-etching circulation to obtain monocrystalline silicon with a nano-pillar structure; (3) soaking the monocrystalline silicon with the nano-pillar structure into an acidic etching solution containing silver nitrate for surface corrosion to obtain monocrystalline silicon with a nano pencil-shaped structure; (4) carrying out magnetron sputtering on the monocrystalline silicon with the microstructure for plating an anti-reflection layer on the front surface, or the back surface or both, of the monocrystalline silicon. According to theinvention, the anti-reflection effect on full-band solar energy is effectively improved, so that the conversion efficiency of the solar cell is improved.

The invention discloses a pickup LED color modulation lap. The pickup LED color modulation lap comprises a power supply, a microprocessor, an AD module, a pickup device, a PWM control module and a RGBthree-color LED lamp, wherein the power supply is electrically connected with the microprocessor, the pickup device is in signal connection with the microprocessor by the AD module, and the microprocessor is in electric-control connection with the RGB three-color LED lamp via the PWM control module. The RGB color modulation LED lamp having a pickup function does not need a mobile phone and a network, the pickup device (a microphone) is designed, environmental sound is acquired, sound frequency spectrum is extracted by the processor, frequency spectrum information is used as a control parameter, a PWM duty ratio is controlled, light-emitting control of a RGB LED is achieved, and the purpose of color modulation is achieved. The pickup LED color modulation LED lamp can independently use, isnot dependent on other equipment and is simple to use, and color modulation can be achieved by acquiring the environmental sound (music playing or talking).

The invention provides a capacitor voltage balance control method of a cascade reactive power compensation device, belonging to the technical field of reactive power compensation control, and aiming at solving the problem that the existing method for balancing the capacitor voltage of a power unit is complex in process and unstable in control status. The method comprises the following steps of: firstly, acquiring the alternating current-side voltage u and the alternating current-side voltage i of each power unit in the cascade reactive power compensation device to obtain the instantaneous power polarity of each power unit; sampling the instantaneous capacitor voltage of a power unit by the frequency which is same as that of the carrier of the reactive power compensation device to obtain a voltage adjusting value of the power unit to be taken as a modification value of the carrier; confirming the modification value of the carrier and the overlapping mode of the carrier, and obtaining the adjusted carrier; and comparing the adjusted carrier with the sinusoidal modulation wave to obtain a modulating signal of the power unit, and controlling the power unit of the reactive power compensation device by the modulating signal to realize the capacitor voltage balance control of the compensation device. The capacitor voltage balance control method is used for balancing the capacitor voltage of the reactive compensation device.

The invention relates to an intelligent bathroom heater temperature regulation method. The intelligent bathroom heater temperature regulation method includes the following steps that firstly, a temperature sensor detects the current temperature value T1 of a shower room in real time and sends the detected current temperature value T1 to an MCU; secondly, a judgment module in the MCU compares the current temperature value T1 with the temperature threshold value T; thirdly, if the current temperature value T1 is larger than or equal to the temperature threshold value T, the fourth step is executed, and if the current temperature value T1 is smaller than the temperature threshold value T, the fifth step is executed, wherein the fourth step and the fifth step are in no particular order; fourthly, a first signal is sent to a power chopper circuit, and therefore the power chopper circuit can be controlled and regulated to regulate the duty ratio of PWM waves according to a first empirical formula, and the heating temperature of electric heating wires is regulated; and fifthly, a second signal is sent to the power chopper circuit, and therefore the power chopper circuit can be controlledto regulate the duty ratio of the PWM waves according to a second empirical formula, and the heating temperature of the electric heating wires is regulated.

The invention discloses a fully adjustable electromagnetic field biological effect loading device and an in vivo and in vitro electromagnetic field loading method thereof. The device comprises a driving power supply (1), a driving unit (2), a magnetic field mechanism (3), a control power supply (4), a control unit (5) and a display unit (6), wherein the driving power supply (1) is connected with the driving unit (2) and the magnetic field mechanism (3); the driving unit (2) is directly connected with the magnetic field mechanism (3); the control power supply (4) is connected with the control unit (5) and the display unit (6); and the control unit (5) is connected with the driving unit (2) and the display unit (6).

The invention discloses an input-output common ground based high-voltage adjustable step-down circuit. A high-voltage alternating current or a high-voltage direct current of a high-voltage input end enters a switch integration circuit through bridge rectification and pi filtering; the switch integration circuit is connected with a typical BUCK step-down circuit; a voltage stabilization reference circuit provides a voltage stabilization reference voltage and turns on a photoelectric isolator; the photoelectric isolator provides a feedback voltage; and the photoelectric isolator is used for feedback isolation between a high-voltage input and a low-voltage output, so that the interference of a high-voltage-side signal on a low-voltage-side signal is reduced. The high-voltage direct current or alternating current is converted into a low-voltage direct current; a resistance value of a slide rheostat is changed to obtain different low-voltage direct-current voltages; and the high-voltage adjustable step-down circuit can be widely applied to step-down circuits of high-voltage switches, especially certain instrument devices with requirements of converting commercial power into a direct-current low-voltage adjustable power supply.

The invention discloses a flyback light emitting diode (LED) switching voltage stabilization driving power supply based on a power factor correction circuit. The flyback LED switching voltage stabilization driving power supply is characterized by mainly comprising a control chip U2, a diode rectifier U1, an operational amplifier, a transformer T, a triode VT1, a diode D1, a primary flyback circuit, the power factor correction circuit and a constant current driving circuit, wherein the power factor correction circuit is connected in series between a negative electrode output end of the diode rectifier U1 and an emitter of the triode VT1, and the constant current driving circuit is connected with the transformer T and the primary flyback circuit separately. By the flyback LED switching voltage stabilization driving power supply, a current peak can be controlled to be constant, meanwhile, the switching duty ratio is controlled, the time proportion of the whole switching period is maintained and output constantly, so that constant output current is achieved; and moreover, the flyback LED switching voltage stabilization driving power supply only requires 0.5-microampere starting current, the starting power consumption is reduced, the efficiency of the flyback LED switching voltage stabilization driving power supply is greater than 80%, the no-load power consumption is smaller than 30mW, and thus, the efficiency of the flyback LED switching voltage stabilization driving power supply is improved.

The invention relates to a step-down DC-DC conversion circuit for an electric vehicle. The step-down DC-DC conversion circuit comprises an output voltage value control circuit, the pulse width modulation signal output end of a CPU of the output voltage value control circuit is connected with the input end of an optocoupler, the output end of the optocoupler is connected with the control pulse input end of a drive module, and the drive pulse output end of the drive module is connected with grids of IGBTs. The collector of each IGBT is connected with the positive electrode of the power battery,and the load is connected between the emitter of each IGBT and the negative electrode of the power battery; and a plurality of load fly-wheel diodes which are connected in parallel are connected between the emitting electrode of each IGBT and the negative electrode of the power battery. A +5V power supply is generated by the power battery through the DC-DC converter to be used by the CPU, and a +15V power supply is generated to be used by the driving module. The circuit is further provided with an input voltage value display circuit, an output voltage setting and display circuit and an actualoutput voltage value display circuit. A low-voltage storage battery does not need to be installed, the installation space of the automobile is saved, the purchasing and battery replacing cost is saved, and operation is reliable.

The invention discloses a brushless DC motor current loop control system and a control method, belonging to the field of DC motor drive closed-loop control, including a three-phase drive circuit, a current conditioning circuit and a closed-loop control circuit; The brush DC motor is connected, the current output terminal is connected with the input terminal of the current conditioning circuit, the input terminal of the closed-loop control circuit is connected with the output terminal of the current conditioning circuit, and the output terminal is connected with the input terminal of the three-phase drive circuit. In addition, a control method of a current loop control system of a brushless DC motor is disclosed. The circuit structure of this system is simple and has high scalability.