44results about How to "Realize constant current output" patented technology

The present invention discloses a constant-current source control circuit which comprises a main circuit, a reference condenser circuit, a voltage control current source circuit and a switch tube control circuit. The invention is characterized in that the main circuit is a power conversion circuit which comprises an inductor L1, an inductive current detecting resistor SR1 and a first switch tube SQ1. The reference capacitor circuit comprises a reference capacitor SC3 and a second switch tube SQ3. The voltage control current source circuit is used for charging the reference capacitor SC3 and has a current magnitude which is proportional with the output voltage U0. The switch tube control module synchronously controls the switching of the first switch tube SQ1 and the second switch tube SQ3, and controls the product of output voltage U0 and the switching time toff of switch tube to a constant number. The constant-current source control circuit of the invention has the advantages of simple structure, low cost, high efficiency, etc.

The invention belongs to the field of switching power supply driving circuits, and provides a switching power supply driving chip and a switching power supply driving circuit, wherein the chip is controlled by quasi-resonance and the valley bottom under the quasi-resonance state is detected by a valley bottom detecting circuit after the transformer is demagnetized, a power supply circuit judges whether to supply power to a power supply pin through a power tube drain electrode of the chip according to the detected valley bottom and the current voltage value of the power supply pin of the chip, and at the same time, a pulse frequency modulation control circuit adjusts the switching frequency of a power tube in the chip according to the value of a feedback pin and a current detection pin of the chip to achieve the constant voltage or constant current output of the switching power supply drive circuit. The switching power supply drive circuit of the chip is adopted, and an auxiliary winding is not required, so that the number of the peripheral circuit devices of the switching power supply drive chip decreases, the cost of the switching power supply drive circuit is lowered, the integration is improved, the board area is reduced, the system operation reliability is improved, and the electricity taking dynamic adjustment is achieved.

The invention relates to a light-emitting diode (LED) dimming driving system with a silicon controlled bypass dimming circuit. The LED dimming driving system with the silicon controlled bypass dimming circuit comprises an alternating current/direct current (AC/DC) LED constant current actuator and a LED light string, wherein the input end of the AC/DC LED constant current actuator is electrically connected with an alternating current electric supply, the output end of the AC/DC LED constant current actuator is connected with the LED light string, the silicon controlled bypass dimming circuit is arranged, the input end of the silicon controlled bypass dimming circuit is connected with the alternating current (AC) electric supply, and the output end of the silicon controlled bypass dimming circuit is connected with a dimming interface of the AC/DC LED constant current actuator. The AC/DC LED constant current actuator obtains energy from the AC electric supply, and outputs a constant current value to drive the LED light string. The AC/DC LED constant current actuator is provided with an analog dimming interface which is used for adjusting an output current value according to an analog voltage amplitude value of an input dimming signal so as to change luminance of the LED light string. According to the silicon controlled bypass dimming circuit, the input end of the silicon controlled bypass dimming circuit is connected with the AC electric supply, and the output end of the silicon controlled bypass dimming circuit generates a smooth direct current analog voltage signal to serve as a dimming signal which is input into the analog dimming interface of the AC/DC LED constant current actuator. The value of amplitude of the dimming signal output by the silicon controlled bypass dimming circuit can be adjusted by adjusting an adjustable knob of the silicon controlled bypass dimming circuit, and thus a current value and the luminance of the LED light string can be adjusted.

The invention relates to an intelligent constant-current driver realized by an embedded chip and a control method of the intelligent constant-current driver. The intelligent constant-current driver realized by the embedded chip is characterized by comprising a rectifying filter module, a null-point detecting module, a DC (direct current)-DC conversion module, an overcurrent protection module, a double-limit-current control module, an MOS (metal oxide semiconductor) tube driving module, an embedded intelligent control module and a function extension module based on the embedded chip. The constant-current driver is large in input range, high in efficiency, upgradable, simple in circuit structure, adjustable in output current and rich in extended functions, and is an intelligent constant-current control system. Meanwhile, when the load is an LED array, light dimming, color changing and flickering control and the like can be realized by the system. Therefore, the intelligent constant-current driver can be used for realizing devices for LED lighting, LED alarm lamps and LED displaying and the like.

The invention relates to a CLC constant-current network-type LED self-current-sharing circuit and a control method therefor, and the circuit and method are suitable for an illumination occasion where an LED light source serves as a load. The self-current-sharing circuit comprises a full-bridge inverter circuit, a CLC constant current network, and an LED output module, wherein the CLC constant current network consists of an LC resonance branch circuit which presents capacitive impedance at a resonant frequency point, a high-frequency transformer, and a current-sharing capacitor unit. A switching device of the full-bridge inverter circuit works at a CLC resonant frequency position, can achieve a constant output current and the purification of an input impedance, guarantees that a primary-side output current of the transformer is independent of the characteristics of a load, avoids a reactive loop current, reduces the device stress, and improves the voltage utilization rate and the efficiency of the transformer. Seeing that the self-current-sharing circuit works at the resonant frequency position, the impact from LED non-linear impedance characteristic on an output current is avoided, and a method of fixed frequency control is proposes for achieving the constant-current output of the circuit.

The invention relates to an inverter for cold cathode fluorescent lamps, which comprises a filter circuit and a rectifier circuit connected with the filter circuit, wherein the rectifier circuit is connected with a control and half-bridge integrated circuit; and a half-bridge driving chip is connected with a boosted circuit. In the inverter for cold cathode fluorescent lamps, the circuit adopts integrated intelligent IC management, a high performance transformer and other solutions so as to realize quick preheating, triggering and operation; the circuit also comprises an EMI filter and a rectifier stage. The circuit half-bridge driving chip adopts IMP3521, IMP3522 or IMP3523. The preheating time is adjustable, and the operating frequency can be set to change the lamp power, thereby avoiding the soft startup of lamp flickering at high starting frequency, protecting the circuit in case of open circuit of filament and trigger failure; and the inverter can automatically restart after the low line voltage input protection and voltage rise. By optimally matching high performance CCFL lamp tube design, the power supply has the advantages of high efficiency, long service life, intelligent adjustment, abnormity protection, low electromagnetic interference and the like; and the circuit is simple and compact, and has high cost performance.

A digital dimming control system for a light-emitting diode (LED) comprises a main power circuit and an LED load, is provided with an external control input module and comprises a control module, a pulse width modulation (PWM) driving module, a digital to analog (D/A) conversion module, a feedback circuit and a comparator, wherein the control module comprises decoding unit, a driving control unit, a time keeping unit and a timing unit. The control module adjusts switching time of PWM driving waveforms by controlling the PWM driving module according to the requirements of the external control input module; on one hand, the driving control unit changes a voltage reference value Vref of the input end of the comparator through the D/A conversion module, and on the other hand, the driving control unit controls connection of PWM signals. The time keeping unit is used for calculating connection time of the PWM during every period, the timing unit is used for determining the switching time of the PWM, the driving control unit guarantees constancy of a switching period of the PWM driving module through the timing unit, and by comparing time Treal obtained by the time keeping unit and storage time Tstatic inside the driving control unit, the driving control unit adjusts the connection time of the PWM and achieves corresponding protection.

The invention provides a primary constant current circuit of an inverter welding machine. The primary constant current circuit comprises a major loop and a control loop; the major loop comprises a double-pipe single-end forward circuit mainly comprising power switches Q3 and Q5, clamping diodes D3 and D4, a high-frequency isolation transformator T1, a sampling transformer T2, commutation diodes D10 and D11, free-wheeling diodes D12, D13 and D15 and an inductor L2; the control loop comprises two circuits, one circuit is a welding machine output short-circuit protection circuit, and in the other circuit, through regulation of a PI regulating circuit, a pulse signal output through a control signal can constantly regulate the pulse duty cycle, so that a welding machine can output constant current. According to the primary constant current circuit, the primary circuit is additionally arranged at the inverter welding machine, so that the constant current output characteristic of the welding machine is realized.

The invention relates to a wireless power transmission device with a constant current output feature. A self-excitation inverter circuit is adopted for designing an inverter power supply. According tothe design scheme of the self-excitation inverter circuit, self-driving of a switching tube can be achieved, and extra PWM generators and driving circuits are omitted. The wireless power transmissiondevice is simple in structure, and can also automatically achieve the resonant frequency trace function; moreover, the switching tube works in the zero-voltage switching-on and switching-off state, the loss is small, and the complexity of the inverter circuit is lowered greatly. An electromagnetic resonance system with the constant current output feature is adopted; single-capacitance parallel compensation topology is adopted for the transmitting end of the electromagnetic resonance system, dual-capacitance serial and parallel compensation topology is adopted for the receiving end of the electromagnetic resonance system, constant current output of the wireless power transmission device can be basically achieved under different load conditions simply through three compensation capacitanceelements, and the addition of a rear-level DC/DC converter is omitted.

The invention relates to a preheating circuit of a magnetron filament. A first rectification filter circuit, an inverter power supply circuit, a transformer T1 and a second rectification filter circuit are arranged between an input end and an output end of a power supply of the preheating circuit in turn; the inverter power supply circuit comprises a capacitor C2, a capacitor C3, a diode V2 and a diode V3; the capacitor C2 and the capacitor C3 are connected with the diode V2 and the diode V3 in a parallel mode respectively after being connected in series; a feedback regulation circuit is arranged between an output end of the second rectification filter circuit and the inverter power supply circuit; the feedback regulation circuit comprises a current sampling resistor, a controller and a first amplifier; the error amplification is performed on the sampling current of the current sampling resistor and a preset benchmark of the power supply through the first amplifier; a frequency modulation signal is given to the V2 and the V3 according to the output of the first amplifier so as to enable the current on a magnetron to be output according to a given preset value. According to the preheating circuit of the magnetron filament, the output current is detected to serve as the input of a feedback regulation power supply so as to enable the output current to be controlled within a range.

The invention discloses a lead-acid battery charger and belongs to that technical field of lead-acid batteries, include a single chip microcomputer control module, power management module, Voltage Sampling Comparison Module, Current Sampling Comparison Module, The battery voltage identification module, the charging current indication module, the saturation display module and the reference voltagesource module. The signal input end of the single-chip microcomputer control module is connected with a time setting unit and a switching unit. The switching unit comprises a manual switch. The invention controls the single-chip microcomputer to output a low-level/high-level signal by turning off/off the manual switch. And then the lead-acid battery to be scrapped is strongly charged and activated, the signal output end of the single chip microcomputer control module is connected with a current sampling and comparing module, The voltage sampling comparison module and the input of the saturation display module regulate the comparison value of the control current sampling comparison module and the comparison point of the voltage sampling comparison module, thereby realizing that the power management module controls the constant voltage or constant current output of the charger, and realizing the purpose of constant voltage or constant current charging.

The invention relates to an AC-DC (alternating direct-direct current) regulator with a high-precision constant current output function. The regulator comprises a transformer and a power tube which is connected at a main winding side of the transformer, wherein the voltage corresponding to main winding current is higher than reference voltage; and a grid of the power tube is controlled to be turned off. The regulator is characterized by comprising a delay locking ring and a reference voltage adjusting circuit, wherein the delay locking ring is used for comparing a first lasting time spent on that the main winding current rises up to a peak value and a second lasting time spent on that the main winding current expectedly rises up to a goal current value; and the reference voltage adjusting circuit is used for adjusting the reference voltage by utilizing the comparing result. According to an AC-DC circuit with high precision, disclosed by the embodiment of the invention, the output current can not be different along with different saturation deterioration times of devices and can not be different along with different stray capacitance values and the like generated by the devices and PCBs (printed circuit boards), so that constant current values of products can be output with the high precision.

The invention discloses a device for detecting a storage battery through timing discharge under PWM (pulse width modulation) control. The device comprises a DSP (digital signal processor), a PWM high-frequency signal circuit, a PWM low-frequency signal circuit, an on-off logic judgment circuit, an electromagnetic isolation circuit, an FET (field effect transistor) discharge circuit, a set current analog output circuit and a discharge current detection feedback circuit. According to the device, the DSP is utilized to emit high-precision PWM signals, meanwhile, fast on-off of multiple groups of FETs are controlled, so that the storage battery realizes output of constant current close to short circuit current instantaneously, and the performance condition of the storage battery is judged through rapid detection for a current peak and attenuation change by the DSP. The device can detect the storage battery at any stage in the life cycle, and with the adoption of the DSP, PWM control signal precision and current detection precision both guarantee accuracy of a detection result and universality of a detection range. Due to extreme short conduction time, little heat is generated, and repeated continuous detection can be realized.

The invention discloses a constant-current power supply and power supply equipment. The constant-current power supply comprises a constant-current power supply body, the outer side of the constant-current power supply body is connected with a connecting wire, and the outer end of the connecting wire is fixedly provided with a butt-joint assembly for preventing reverse connection and poor connection contact. According to the invention, the butt-joint assembly is used to ensure the stability of butt joint between theconstant-current power supply body and an LED light source, through mutual cooperation of a rotating groove and a steering groove, a plug shell can automatically steer when being inserted, the problem of wrong connection of a live wire and a zero wire is avoided, and meanwhile, the situations of misconnection and poor contact after connection are avoided through the clamping piece.