428 results about "Constant power circuit" patented technology

The invention relates to a high power factor DCM Boost PFC converter comprising a main power circuit and a control circuit. The main power circuit comprises an input voltage source vin, an EMI filter, a diode rectification circuit RB, a Boost inductor Lb, a switch tube Qb, a diode Db, an output capacitor Co and a load RLd. The high power factor DCM Boost PFC converter is characterized in that the control circuit adopts an output signal which adopts duty ratio as changing rule to drive the switch tube Qb. Adopting the varying duty ratio control, the high power factor DCM Boost PFC converter can improve the PF value to about 1 in the AC input voltage range of 90-265 V, increase the inductance capacity, obviously decrease the inductive current ripple, obviously reduce the effective value of the inductive current and correspondingly reduce the effective value of the current of the switch tube, has high input power factor and small output voltage ripple and contains less input current harmonic waves. The conduction loss of the high power factor DCM Boost PFC converter is reduced, and the efficiency is improved.

The invention relates to a diagnosis method for power transistor of doubly salient motor driver, belonging to the fault diagnosis method for power device in motor driving system. In the method three-phase current sensor is set on three-phase bridge arm; while three-phase current is measured the measurement for current signal of current reflowing is added; after current reflowing signal is treated digitally and driving signal of power transistor is combined on-line fault measurement and diagnosis for main power circuit are realized. The invention is provided with simple realization and good rapidity. Not only open fault of power transistor can be diagnosed quickly but also it can play a better protecting effect for bridge-arm direct phenomenon maybe generated by short circuit of power transistor. At the same time it provides a feasible method for fault diagnosis of motor driving system based on full-bridge converter.

The system mainly consists of the solar energy photo-volt battery (PV) and the semi-conductor thermo electric generator module (SG). The hot end insulated heat-lead board of SG contacts with the bottom electrode of PV via the heat-lead silica gel. PV and SG connect to the power supply circuit via a lead. The hot end insulated heat-lead board of SG contacts with the radiator via the heat-lead silica gel. The energy produced by PV and the energy output by SG and boosted by a DC/DC circuit are stored respectively into the different lithium ion batteries. Via control and distribution by the consequent power circuit, these energies are converted into the DC working voltage. The invention utilizes fully the low-level heat energy and solves the problem of PV performance under hi temperature. The invention raises the generating efficiency and extends PV life.

A switching power supply with overvoltage protection includes a soft start circuit, a rectifying circuit, a filter capacitor, a main supply, an auxiliary supply and a monitoring circuit. When the input voltage is higher than the predetermined protection voltage, a first electric control switch is turned off, and the main power circuit of the switching power supply is shut off. At the moment, the actuation and release of the second electric control switch is controlled so as to control the input power supply to intermittently charge the power supply module such that the output voltage downstream of the rectifying circuit inside the power supply is controlled in a safe range. For instance, the second electric control is turned on when the output voltage is lower than a certain value, and is turned off when the output voltage is higher than a certain value. Thus, it is ensured that the bus line voltage inside the power supply is controlled within a safe range, to ensure the safety of the devices inside the power supply; and at the same time to ensure the safety of the inner devices of the switching power supply, such that the auxiliary power supply and the control circuit can work normally.

A two-stage switching power supply includes a first-stage power circuit, a bus capacitor, a second-stage power circuit and a power control unit. The first-stage power circuit is connected to a power bus for receiving an input voltage, and includes a first switching circuit. The input voltage is converted into a bus voltage by alternately conducting and shutting off the first switching circuit. The second-stage power circuit is connected to the power bus for receiving the bus voltage, and includes a second switching circuit. The power control unit is used for controlling operations of the first switching circuit and the second switching circuit. The bus voltage is dynamically adjusted according to electricity consumption amount of the system circuit under control of the power control unit. An operating mode of the second switching circuit of the second-stage power circuit is changed according to the electricity consumption amount of the system circuit.

A DC solid power switch circuit includes a main power circuit, a subsidiary power circuit parallel to the load, an isolated drive protection circuit composed of a drive supply, a drive isolation circuit, a slow turned-on-off control circuit, a discriminating control circuit, a short circuit protection circuit and a push and pull output circuit, a current detection circuit, a voltage detection circuit, a main power valve drive circuit, a light-coupled isolating circuit, an assistant power valve switch-on logic circuit and a power drive output circuit, which can limit the current impulse in the period of switching on capacitive load, and suppress the peak voltage in turning off the inductive load.

The invention relates to a dimmable constant-current drive circuit, belongs to the technical field of current drive circuits, and in particular relates to improvement on a dimmable LED constant-current drive circuit, which comprises a lighting protection and electromagnetic compatible circuit (1), a power factor correction circuit (2), a plurality of constant current power circuits (3,4), a dimmable control power supply circuit (6), a dimmable control circuit (5) with a serial interface, and an alarm detection circuit (7), wherein the alarm detection circuit (7) extracts an alarm signal from the constant current power circuits (3,4), and outputs the signal to the dimmable control circuit (5) after identification processing. The dimmable LED constant-current drive circuit can resist external electromagnetic interference and provide dynamic compensation, and has superior electric energy utilization rate even when load changes dynamically, thereby improving electricity-saving effect, performing programming control or network monitoring on illuminating devices and realizing various required illumination effects.

The invention relates to the field of switching converters, and particularly relates to a flyback active clamp-type switching converter control circuit and a control method thereof. The active clamp flyback circuit of the invention can realize reduced frequency and ZVS, and comprises a main power circuit, a clamp circuit, and an output rectification filter circuit, wherein a transformer and a main switching tube are connected to form the main power circuit; a clamp switching tube and a clamp capacitor and a clamp diode are connected to form the clamp circuit; and an output rectification diode and an output capacitor are connected to form the output rectification filter circuit. In comparison with the prior art, reduced frequency in light load can be realized, and the control scheme is flexible; switching loss in no load and loss of a transformer winding and switching tube inner resistance caused by a current effective value are little, no-load power consumption is greatly reduced, and the light-load efficiency is improved.

The present invention relates to an online uninterruptible power supply topology. A single-phase topology comprises a main circuit and an auxiliary circuit. A power conversion stage of the main power circuit includes first to fourth branches connected in parallel between a positive bus and a negative bus, the first branch consists of a first diode and a second diode connected in series, the second branch consists of a second capacitor and a third capacitor connected in series, and a first switch is connected between the intermediate node of the first branch and the intermediate node of the second branch, the third branch consists of a third switch, a fifth capacitor, a sixth capacitor, a fourth switch connected in series, the intermediate node of the second branch together with a node between the fifth capacitor and the sixth capacitor are connected to ground, the fourth branch consists of a fifth switch and a sixth switch connected in series, the second switch is connected between the intermediate node of the second branch and the intermediate node of the fourth branch, and the third switch and the fourth switch respectively have a third diode and a fourth diode connected in parallel. An input of the charger of the auxiliary circuit is connected to an AC input or positive and negative buses of the uninterruptible power supply, an output of the DC/DC converter is connected to a node between the third switch and the fifth capacitor and a node between the sixth capacitor and the fourth switch.

A converter is provided in which the cost and size of which are reduced by a decrease in current consumption with no need of large elements or radiation fins. The converter has a switching element (Q1) being connected to a DC power source through a primary winding (P) of a transformer (T), a control circuit (4) for turning on/off the switching element (Q1), a diode (D51) and a capacitor (C51) for rectifying/smoothing the voltage induced in the secondary winding (S) of the transformer (T) to extract DC output, and a starting circuit (5) for starting the control circuit (4). The starting circuit (5) operates as a constant current circuit (Q2, R1, R2, ZD1, D1) while starting the control circuit (4), and as a constant voltage circuit (Q2, R1, R2, ZD2, D1) after starting the control circuits (4).

A low-pass filter that filters an input signal input to a filter input terminal to output a filtered output signal to a filter output terminal includes a capacitor, a first field-effect transistor, a first resistor, and a first current source. The capacitor is connected between the filter output terminal and ground. The first field-effect transistor has a gate terminal, a first conduction terminal connected to the filter input terminal, and a second conduction terminal connected to the filter output terminal. The first resistor is connected between the gate and first conduction terminals of the first transistor. The first current source is connected to the first resistor to supply a first current to the first resistor. The first resistor generates a first voltage thereacross based on the supplied first current for electrically biasing the gate terminal of the first transistor.

The invention relates to an LED lamp, more particularly to an LED lamp with intelligent control. The LED lamp comprises a first power circuit, a probe, a photo-induced probe, a control circuit, a first PWM circuit, a second PWM circuit, a second power circuit, a first LED light source, a second LED light source, and a third LED light source. According to the invention, a remote control signal that is emitted by a remote controller is received by the probe; based on that, dimming control and toning control are carried out on the first LED light source and the second LED light source by lightening the third LED light source that is used in the evening; or the photo-induced probe senses the surrounding light intensity and light color, so that the light intensity and the light color of the LED lamp can be adjusted automatically. The LED lamp with intelligent control has advantages of intelligent control, automatic adjustment with humanization, energy conservation, long service life, low use cost, high brightness, and environmental protection and the like. The LED lamp with intelligent control can be used in any illumination space including a family, a school, an office, a retail shop, a warehouse, a workshop, a data center, a station, and a mine.

Provided is a capacitor coupling type power transmission circuit in which a variation in receiving side voltage due to a variation in capacitance is suppressed to prevent an influence on a variation in load current in a display panel. An insulating board of the display panel is sandwiched by capacitive coupling electrodes formed on each of a transmitting side board and a board of the display panel, thereby forming capacitors. A non-contact transmission is performed by the capacitors. An alternating current voltage signal obtained by electrodes on a display panel side is rectified by a rectifier including diodes. A constant voltage circuit which is a shunt regulator including a diode array in which a resistor and a plurality of diodes are connected in series is provided to maintain a stabilized voltage irrespective of a variation in load in the display panel.

A power supply apparatus includes a front-stage power circuit, a bus capacitor, a standby power circuit, a standby power circuit, an auxiliary switching circuit and a controlling unit. The auxiliary switching circuit is electrically connected between the bus capacitor and the standby power circuit. The controlling unit is electrically connected with the auxiliary switching circuit and the front-stage power circuit for controlling operations of the front-stage power circuit and the auxiliary switching circuit. When the input voltage is normal but the front-stage power circuit is disabled, the auxiliary switching circuit is turned off under control of the controlling unit, so that electric energy of the input voltage is transmitted to an input terminal of the standby power circuit through the protecting circuit.

A voltage regulator includes a constant voltage power circuit and an overcurrent protection circuit. The constant voltage power circuit generates an output voltage, an output current and a divided voltage. The overcurrent protection circuit includes a current sensing unit, a first mirroring unit, a voltage to current converting unit, a second mirroring unit, and a pull up unit. The current sensing unit generates a sensing current according to the output current. The first mirroring unit generates a first mirroring current. The first mirroring current is proportional to the output current. The voltage to current converting unit is used for converting the divided voltage into a first current.

The second mirroring unit generates a second mirroring current. The second mirroring current is proportional to the second current. The pull up unit controls the output voltage and the output current according to the first mirroring current and the second mirroring current.

A touch display device can include a panel including touch electrodes; a touch/data driver to drive data lines and the touch electrodes of the panel, read out capacitance variations in the touch electrodes and output sensing data; a gate driver to drive gate lines of the panel; a timing controller to control display operations of the touch/data driver and the gate driver; a microcontroller unit (MCU) to control touch driving and sensing operations of the touch/data driver; a first power circuit to drive the timing controller and the gate driver using a main voltage supplied through a first power line; a multiplexer to output one of a universal serial bus (USB) voltage supplied through a second power line and the main voltage supplied through the first power line; a second power circuit configured to drive the touch/data driver, the gate driver and the MCU based on an output voltage from an output of the multiplexer; and a switch connected between the output of the multiplexer and the second power line, the switch being configured to switch the output of the multiplexer to the second power line.

A two-stage switching power supply includes a first-stage power circuit, a second-stage power circuit, an output detecting circuit and a power control unit. The first-stage power circuit includes a first switching circuit. By conducting or shutting off the first switching circuit, an input voltage is converted into a bus voltage. The second-stage power circuit includes a second switching circuit. By conducting or shutting off the second switching circuit, the bus voltage is converted into an output voltage. The output detecting circuit generates an output detecting signal according to the output voltage. The power control unit controls operations of the first and second switching circuits according to the output detecting signal. A first-stage voltage gain value of the first-stage power circuit and a second-stage voltage gain value of the second-stage power circuit are altered with the output detecting signal, so that the output voltage is maintained at a rated value.