58 results about "Flyback topology" patented technology

The invention relates to a control method for a control circuit of a light emitting diode (LED) driver. The LED driver has a flyback topological structure; the control circuit is positioned on a primary side of a transformer and comprises a sampling circuit, a conduction time detection circuit of an output diode on a secondary side of the transformer, a regulation signal generation circuit and a pulse width modulation (PWM) control circuit, wherein the sampling circuit is used for acquiring a sampling signal for representing an output signal of the LED driver on the primary side of the transformer; the conduction time detection circuit is used for detecting conduction time of the diode; the regulation signal generation circuit is used for regulating conduction time of the sampling signal,a reference source and the output diode on the secondary side of the transformer and generating a regulation signal; and the PWM control circuit is used for receiving the regulation signal and generating a control signal to control the turning on and turning off of a switching device in the LED driver, so stable output of the LED driver is retained.

The invention relates to a high-power factor LED (light-emitting diode) driving circuit supporting silicon controlled rectifier dimming. A replacement type low-power LED driver implemented by the invention is an electrical isolation type circuit, the circuit adopts a flyback conversion topological structure, an isolation type transformer is used for performing energy storage and transmission, and an external three-end silicon controlled rectifier dimmer is used for dimming. In order to realize a dimming function, the use of a switching power supply management chip NXPSSL2101T integrating an MOSFET (metal oxide semiconductor field-effect transistor), the use of a three-end silicon controlled rectifier dimming switch for producing input signals, the use of a resistor voltage division way for producing brightness control signals and the like are considered. In order to realize a high power factor, the use of a valley-fill PFC (power factor correction) circuit is considered, and the valley-fill PFC circuit comprises three capacitors and two diodes. Under low-power limitation, the flyback conversion topological structure is adopted for realizing higher efficiency. The high-power factor LED driving circuit disclosed by the invention improves the circuit integration level, the power factor and the circuit conversion efficiency.

The invention provides a primary side regulation control system and primary side regulation control method of an active clamp flyback converter and belongs to the technical field of primary side regulation control. The system comprises an inductive current sampling circuit, a drain-source voltage sampling circuit, an auxiliary winding voltage sampling circuit, a gate driver, a control circuit witha controller as a core, and a differentiator. The control circuit with the controller as the core comprises a voltage operation module, a current operation module and a constant-voltage constant-current function module. The active clamp flyback converter can accurately predict and calculate the primary sides of output voltage and output current while the working efficiency of the system is ensured, so the accurate primary side constant-voltage constant-current adjustment of the active clamp flyback topology is realized. By adopting the control system, the use of optical couplers and other isolation elements is reduced, the integration level of the system is improved, and very high output voltage precision can be obtained. In addition, the control system can be applied to a primary side resonance active clamping flyback topology and a secondary side resonance active clamping flyback topology.

A high efficiency switching power converter has a flyback converter and a scavenger circuit to recycle the unavailable magnetic energy stored in the converter wiring and core leakage flux. Recycling this energy, which is normally dissipated in snubber networks, improves efficiency and considerably extends the feasible power levels of the flyback topology enabling high power output, low cost offline converters with low line current harmonics and active PFC.

The invention provides a resonant converter. By virtue of the resonant converter, some problems existing in the prior art can be solved; an asymmetrical half-bridge flyback topology and other resonant topologies can realize a peak value current control mode without being limited by power level; and improvement of voltage adjustment rate, load adjustment rate, dynamic response and other performance can be realized. Compared with the prior art, the resonant converter can achieve the beneficial effects as follows: the peak value current control mode can be realized on the asymmetrical half-bridge flyback topology and similar topologies; low-loss peak current sampling is realized and power supply efficiency is improved; leading edge blanking is not required, noise interference can be eliminated, and real-time property of a control strategy can be improved; and by adoption of the peak value current control mode, bandwidth can be improved, and dynamic performance can be enhanced.

The invention relates to a ZVS control method for active clamp flyback topology self-adaptive dead time, and the method comprises the following steps: setting a control circuit for a switching power supply circuit, detecting current flowing through a primary coil inductor of a transformer and zero-crossing voltage, and further regulating and controlling the conduction duration of a clamp switchingtube and the switching-on time interval of a main switching tube; and realizing the zero-voltage switching-on of the main switching tube. According to the method, the turn-on time interval of the main switching tube can be dynamically adjusted in real time according to different input voltages, output voltages and application parameters, and the interval can reach the optimal value capable of realizing zero-voltage turn-on.

The method includes steps: voltage-testing circuit (VTC) detects voltage value at two ends of self-powered winding of transformer; VTC determines detected voltage value and prearranged voltage value; if detected voltage value is larger than prearranged voltage value, VTC outputs voltage signal to PWM control circuit; after receiving signal of over voltage, PWM control circuit stops outputting PWM control signal to primary side of transformer; thus, primary side of transformer protects primary side and secondary side. The circuit includes primary side circuit of transformer, transformer composed of primary and secondary windings and self-powered winding, PWM control circuit, and voltage detection circuit. The invention raises reliability of over temperature protection for transformer.

A single-stage AC-DC power converter for powering a load at a substantially constant current, and related methods and systems. The AC-DC power converter includes a high power factor correction (PFC) circuit configured in a flyback topology and operating in transition mode. The flyback PFC circuit has a PFC controller and is configured to draw an input AC current from an AC power supply. The input AC current has a first total harmonic distortion (THD). The flyback PFC circuit outputs a DC current to the load. The PFC controller is configured to sense a rectified input voltage. By multiplying the rectified input voltage sensed by the PFC controller, the input AC current drawn by the flyback PFC circuit has a second, much improved THD, which is achievable without the need of an expensive PFC controller. The rectified input voltage sensed by the PFC controller is multiplied using a Zener diode ladder.

The invention discloses a flyback LED drive circuit based on a BP neural network PI control method. The flyback LED drive circuit comprises an EMI filtering module, a full bridge rectification module, a switch conversion circuit module, a sampling module, a PWM driving module, a processor module and an LED load module, wherein the switch conversion circuit module adopts a flyback topological structure. An embedded processor is utilized to realize the BP neural network PI control method, and the method serves as a flyback LED drive circuit closed-loop control method to realize a network compensation function; and the method has the advantages of fast response speed, high adaptivity, stable closed-loop system, good control effect and low development cost.

A single-stage AC-DC power converter for powering a load at a substantially constant current, and related methods and systems. The AC-DC power converter includes a high power factor correction (PFC) circuit configured in a flyback topology and operating in transition mode. The flyback PFC circuit outputs a direct current (DC) voltage and a DC current. The PFC circuit further includes a flyback transformer and a switch circuit that selectably toggles the substantially constant output current provided to the load between a first and a second, preset constant current. The secondary windings of the flyback transformer are split into two sections, and the switch circuit toggles the two sections of the secondary windings between a series and a parallel configuration to provide the first and second, preset constant currents. The switch circuit includes a switch and three, fast Schottky diodes.

The invention discloses a PWM (pulse-width modulation) module which is applied to a flyback type switching power supply topology, can cause reverse voltage of D-S two ends of the topology to be lower and can always alternatively generate an interruption mode and a critical mode. The PWM module comprises a PWM control circuit and a sawtooth generator, and further comprises a zero current detection and start synchronizing circuit and a load weight sawtooth wave frequency conversion circuit, wherein the PWM control circuit is used for switching off fixed clock start peak current; the zero current detection and start synchronizing circuit can generate phase coherent waves; after the coherent waves and sawtooth waves are iterated, the PWM control circuit can start another alternative PWM signal output; and when a flyback circuit works in a current continuous mode, the sawtooth waves work under different frequencies by the load weight sawtooth wave frequency conversion circuit. According to the PWM module disclosed by the invention, the flyback circuit always works in a current interruption mode and critical mode alternatively generating state; the reverse voltage generated by the D-S two ends of a switching tube is reduced to 1.2-1.5 times of power source voltage; and the PWM module has a simple structure, the controlled flyback topology switching on-off loss is small, the service life is long and a few of ultraharmonics are generated.

The invention discloses a constant current driving device of a light-emitting diode (LED) backlight module. The constant current driving device of the LED backlight module comprises a voltage conversion module, a voltage feedback module, a backlight adjustment module and a constant current control module, wherein the voltage conversion module generates direct current voltage through a flyback topology framework, the direct current voltage is used for lightening LED lamp strips of the LED backlight drive, the constant current control module controls currents which flow through the LED lamp strips of the LED backlight drive by means of control of on and off of a metal oxide semiconductor (MOS) tube, and therefore the currents are enabled not to exceed the largest currents which the LED can bear. The voltage feedback module achieves control of output voltage of the voltage conversion module through negative feedback so that the purpose that the output voltage can be stabilized in a suitable range can be achieved. The backlight adjustment module controls the voltage conversion module through enable signals and intensity control signals. In the process of utilization, a constant current drive circuit of the LED backlight module can directly generate the direct current voltage which drives the LED lamp strips through rectification filtering. Therefore, the constant current driving device of the LED backlight module has the advantages of being simple in circuit, high-efficient, low in cost, and capable of accurately and flexibly adjusting the backlight currents.

A lamp filament preheating circuit using modified flyback topology which gives pulsating AC in the secondary of the flyback transformer. The circuit may be controller based or implemented by a monoshot and astable multivibrator. A self-oscillation, parallel resonant current fed half bridge inverter circuit may include an arc sensing circuit.

The invention discloses an ultrahigh frequency MHz high power conversion device, which is characterized in that the device carries out combination on a power electronic topological structure, and can acquires new energy through combining N pieces of energy whose frequency is f, wherein the frequency of the new energy is Nf, and the power of the new energy is N times greater. The combination can be a combination of a single tube forward topology, a single tube flyback topology and a full-bridge topology or a half-bridge topology. The energy can adopt single-phase output or multi-phase output. The energy can be current signals or voltage signals. The ultrahigh frequency MHz high power conversion device has the beneficial effects of simple structure, high reliability, ultrahigh output frequency, and ability of being applied to ultrahigh frequency high-power power electronic devices.

The invention discloses a high-stability flyback direct current-direct current (DC-DC) converter. According to the converter, a voltage feedback loop and a current feedback loop are adopted in flyback topology, so that the transient response of a converter device is accelerated. A novel frequency compensation circuit is also adopted. The frequency compensation circuit mainly comprises an error amplifier, a Miller capacitance control unit and a dynamic zero control unit. According to the Miller capacitance control unit, a large compensation capacitor in the traditional dominant pole compensation can be replaced by a small compensation capacitor, so that the area is saved, and the transient response of the system is improved. According to the dynamic zero control unit, the introduced zero point can well offset the first non-dominant pole of the system under the condition that the output has fluctuation, and the stability of the system is guaranteed. According to the DC-DC converter, a compensation resistor and a compensation capacitor can be integrated to a chip, internal compensation is realized, and the area of the chip is saved; meanwhile, the circuit structure is simple, the reliability is high, the phase margin can be 90 degrees, and the stability of the system is high.

The invention provides a circuit achieving multichannel backlight driving through an MCU (Micro Controller Unit) and a driving method thereof. A flyback topology constant pressure output unit and an MUC control unit are used, so that output voltage of the flyback topology constant pressure output unit is lower than driving voltage of LED (Light Emitting Diode) light strings when an MCU chip is not in operation; the MCP chip performs analogue voltage sampling processing on every path of current detection resistance when the MCU chip operates; the MCU chip adjusts a voltage output duty ratio output to the LED string if sampling voltage of one path of the LED string is higher than a preset value; the MCU chip reduces output voltage output to the flyback topology constant pressure output unit according to voltage of the LED light string which requires the highest voltage if the sampling voltage of one path of LED light string is smaller than a preset value. The circuit achieving multichannel backlight driving through the MCU and the driving method thereof have the advantages that the structure is simple, the configuration is flexible, manufacturing costs are low, and the safety is high.

The invention discloses a power device controlled by a single chip. The power device comprises an AC input circuit, a filter network circuit, a rectifier bridge circuit, a flyback topology circuit, a main output circuit, a feedback network circuit, a control IC circuit, a slave output circuit and a compensation network circuit, where the input of the slave output circuit is connected with a central tap of an output winding of a transformer of the flyback topology circuit; and the compensation network circuit is connected between the main output circuit and the slave output circuit. By using the central tap of the output winding of the transformer as the main output, the power device can achieve relatively stable slave output voltage by fully utilizing the stability characteristic of the main output voltage, thereby simplifying the design and the debugging of the entire power device, lowering the cost and improving the circuit stability. With the aid of the compensation network circuit, the power device can still stabilize the slave output voltage in an allowable range under the condition of unloaded main output and loaded slave output.

The invention provides a dual-transistor flyback topology switching power supply circuit driven by transformer leakage inductance, which includes a drive signal input end, an isolation driving chip, afirst capacitor, a second capacitor, a first resistor, a second resistor, a third resistor, a fourth resistor, a first field effect transistor, a second field effect transistor, a first diode, a second diode, a first inductor, a flyback transformer, a third diode, a fifth resistor, a driving supply voltage input terminal, and a switching power supply voltage input terminal. As that circuit of theinvention is simple, the reliability is good, the drive transformer is not need, and the leakage inductance of the flyback transformer is fully utilized, the power density of the switch power supplycan be effectively improved.

A switched mode power supply (400), comprising a transformer (410) having a primary winding (410-1), a transformer core (410-3) configured to store energy transferred thereto from the primary winding (410-1) during operation, and a secondary winding (410-2) having a first terminal (Tl) and a second terminal (T2). The switched mode power supply also has a primary side circuit (Q1, Q2, C1) arranged to generate voltage pulses and thereby to drive the primary winding (410-1) of the transformer (410), and a secondary side circuit comprising a rectification circuit connected to the secondary winding (410-2) at the first and second terminals (Tl, T2). The rectification circuit is arranged such that during a forward phase of operation of the switched mode power supply, in which the primary winding (410-1) is driven by the primary side circuit to magnetise, and store energy in, the transformer core (410-3), a current induced to flow in the secondary winding (410 -2) from the second terminal (T2) to the first terminal (Tl) is output by the rectification circuit. The rectification circuit is further arranged such that during a flyback phase of operation of the switched mode power supply, in which the magnetisation of the transformer core (410-3) is reset, a current induced to flow in the secondary winding from the first terminal (Tl) to the second terminal (T2) of the secondary winding (410 -2) is output by the rectification circuit so that energy stored in the transformer (410) during the forward phase of operation is output by the rectification circuit.

The invention discloses an AC-to-DC isolating switch power supply circuit, which comprises a rectifier circuit, a filter circuit, a first power conversion circuit, a power conversion transformer, a second power conversion circuit, a first group of DC output circuits and a second group of DC output circuits, wherein the two groups of voltages isolated from each other are outputted by adopting a topological structure different from that of a conventional flyback topological power supply. A first power conversion circuit operates on the same principle as a high voltage BUCK circuit, Therefore, the voltage stress of the required power switch transistor is reduced, and a group of power sources isolated from the first group of DC output circuits can be outputted to supply power to the second group of DC output circuits at the back end only by adding a secondary winding to the power conversion transformer. Finally, a low-power switching power supply with the same cost as linear transformer and similar performance to the original flyback topology power supply is realized.

The invention discloses a space high-efficiency semiconductor laser constant-current power supply, which combines a first filter, a Flyback topology circuit, a second filter, a first capacitor, a first resistor, a PI compensation network, a control circuit and other devices to form a space laser load high-efficiency low-ripple driving power supply with high input and constant-current output. The space high-efficiency semiconductor laser constant-current power supply has the advantages that the constant-current power supply adopts a common-ground Flyback topological structure, a soft switchingtechnology can be realized by respectively switching off and switching on the first switching tube at an inductive current peak value and a zero crossing point in a single period, the loss is reducedby a synchronous rectification technology and a quasi-resonance soft switching technology, and the efficiency of the laser constant-current power supply is greatly improved.

The invention relates to the technical field of active clamping flyback control, and discloses a clamping tube light-load conduction control method in active clamping flyback topology, which comprises an active clamping flyback circuit and a light-load conduction control circuit, and is characterized in that the light-load conduction control circuit is connected with the active clamping flyback circuit; the light-load conduction control circuit comprises a detection circuit, a first conduction time control module, a second conduction time control module and a driving unit. The detection circuit and the driving unit are connected with the active clamping flyback circuit. According to the invention, the clamping tube is controlled to be conducted twice in one period, a certain degree of negative current is generated in the two times, and proper conduction time is searched for in the first time, so that the second conduction duration is determined to be relatively accurate, and the problem that the conduction time of the clamping tube is too short or too long is effectively avoided; the circuit is used for accurately realizing zero-voltage conduction under light load, and effectively reducing the conduction loss.

The invention provides a five-path output microcomputer monitoring switching power supply, and solves the problems that the existing power supply is high in power consumption and high in temperature increment and does not have a corresponding failure protective circuit. A power supply control circuit adopts a flyback topological structure and realizes PWM pulse width adjustment through output sampling and a negative feedback loop, so that output stability is achieved. The five paths of output control circuit parts are independent mutually and are not influenced mutually, and the power supply is additionally provided with a PFC power factor correcting circuit and an RCD absorbing circuit, so input overvoltage protection, input undervoltage protection, output overvoltage protection, output shortcircuit protection and output overload protection functions are realized simultaneously, and the usability and the reliability of the power supply are considered fully from heat design, electromagnetic shielding design and safety standard design.