1544 results about "Voltage ratio" patented technology

A method and apparatus for efficiently charging lead-acid batteries applies small voltage steps to probe the charging efficiency of a battery being charged. The application of a voltage step causes the current to change from a base current to a surge current immediately after the voltage step, and to decay asymptotically to a plateau current after the surge current. A current ratio, defined as the difference between the plateau current and the base current divided by the difference between the surge current and the base current, is used as an indicator of the charging efficiency. The output voltage of the power supply charging the battery is then adjusted according to the measured current ratio. A current-voltage slope, defined as the difference between the plateau current and the base current divided by the magnitude of the voltage step, may also be used as an indicator of the charging efficiency for controlling the charging process. Alternatively, in a current-controlled charging process, small current steps are used to probe the charging efficiency. For a current step, the induced voltage changes are measured, and a transient-plateau voltage ratio is calculated. The charging current is then adjusted according to the calculated voltage ratio.

Methods and systems for transforming electric power between two or more portals. Any or all portals can be DC, single phase AC, or multi-phase AC. Conversion is accomplished by a plurality of bi-directional conducting and blocking semiconductor switches which alternately connect an inductor and parallel capacitor between said portals, such that energy is transferred into the inductor from one or more input portals and / or phases, then the energy is transferred out of the inductor to one or more output portals and / or phases, with said parallel capacitor facilitating “soft” turn-off, and with any excess inductor energy being returned back to the input. Soft turn-on and reverse recovery is also facilitated. Said bi-directional switches allow for two power transfers per inductor / capacitor cycle, thereby maximizing inductor / capacitor utilization as well as providing for optimum converter operation with high input / output voltage ratios. Control means coordinate the switches to accomplish the desired power transfers.

Compensation needed to be made for reduced light efficiency in aged sub-pixels of an active matrix organic light-emitting diode (OLED) display are determined using a current ratio or a voltage ratio pertaining to an aged sub-pixel relative to un-aged, reference sub-pixels. When the current through the sub-pixels or the voltage across the sub-pixels are measured to determine the age of the sub-pixels, correction is made to the measured current or voltage to account for variations in the ambient temperature in which the OLED display is placed.

Compensation needed to be made for reduced light efficiency in aged sub-pixels of an active matrix organic light-emitting diode (OLED) display are determined using a current ratio or a voltage ratio pertaining to an aged sub-pixel relative to un-aged, reference sub-pixels. When the current through the sub-pixels or the voltage across the sub-pixels are measured to determine the age of the sub-pixels, correction is made to the measured current or voltage to account for variations in the ambient temperature in which the OLED display is placed.

A system is provided for monitoring the removal of blister pack contents. An array of spatially-extended, electrically parallel breakable traces made from electrically resistive material is formed behind a corresponding array of blisters of a blister card. Then this array is connected in series with a reference resistor to form a voltage divider. All resistive traces are formed from the same materials in a single operation. Blister breakage is determined using changes in the ratio of the resistances of the array and the divider. A predictive algorithm is used to adjust the threshold resistance ratio change that signals blister breakage and voltage ratios are used to adjust for battery output changes over time. Breakage events and their time of occurrence are recorded in nonvolatile memory for later retrieval. Additional resistors can be used for activating the system and detecting tampering.

The invention provides a monitoring method and a monitoring system for a touch switch. The monitoring method comprises the following steps of: (1) during switching on the touch switch or switching off the touch switch, respectively measuring voltages of two ends of the touch switch relative to the same reference electrical level; (2) comparing the voltages of the two ends of the touch switch relative to the same reference electrical level; and (3) judging whether the touch switch is switched on or switched off normally or not according to a comparison result. By using the method and the device of the monitoring method and the monitoring system of the touch switch, the touch switch can be confirmed whether to be switched on normally or switched off normally through judging the voltages of the two ends of the touch switch relative to the same reference electrical level after the touch switch in a high voltage system of an elective vehicle receives a switching-on command or a switching-off command. The invention provides the effective and reliable monitoring method and the motoring system of the touch switch, thus the touch switch can be correctly judged whether to be switched on normally or switched off normally.

Methods and systems for transforming electric power between two or more portals. Any or all portals can be DC, single phase AC, or multi-phase AC. Conversion is accomplished by a plurality of bi-directional conducting and blocking semiconductor switches which alternately connect an inductor and parallel capacitor between said portals, such that energy is transferred into the inductor from one or more input portals and / or phases, then the energy is transferred out of the inductor to one or more output portals and / or phases, with said parallel capacitor facilitating “soft” turn-off, and with any excess inductor energy being returned back to the input. Soft turn-on and reverse recovery is also facilitated. Said bi-directional switches allow for two power transfers per inductor / capacitor cycle, thereby maximizing inductor / capacitor utilization as well as providing for optimum converter operation with high input / output voltage ratios. Control means coordinate the switches to accomplish the desired power transfers.

An image display device capable of displaying a high-quality image by reducing the occurrence of alignment disorder of a liquid crystal irrespective of details of the image is provided. A liquid crystal display device includes: a liquid crystal display panel including a plurality of pixels for displaying images; and a drive means for driving the liquid crystal display panel while correcting pixel data of each pixel one after another, so that a voltage ratio between a voltage applied to one pixel and a voltage applied to its neighboring pixel is reduced.

A hybrid constant current control system that uses both pulse width modulation (PWM) and pulse frequency modulation (PFM) control. When transitioning from constant voltage mode to constant current mode the present invention can continue to control using PWM. Thereafter, when the voltage has dropped, the present invention smoothly transitions to PFM mode. The point of transition is based upon the switching frequency and the lowest rated voltage of operation. The system and method avoids very short (narrow) Ton times which ensures accurate constant current (CC) control with bipolar junction transistor (BJT) devices. The present invention also avoids acoustic noise because the switching frequency is maintained at a high enough level to avoid such acoustic noise even when the energy transferred through the transformer is still substantial and the output voltage is not too low. In addition the output current limit is insensitive to variation in the inductance-input voltage ratio, and is minimized against leakage inductance.

A symmetrical high-speed current sense amplifier having complementary reference cells and configurable load devices that eliminates architecture-related capacitive mismatch contributions. The current sense amplifier is adapted for use in a symmetric sensing architecture and includes a configurable load device. The current sense amplifier includes a voltage comparator, a first clamping device coupled between a first input of the voltage comparator and a first input signal, the first clamping device being coupled to a reference voltage. A second clamping device is coupled between the second input of the voltage comparator and a second input signal, the second clamping device being coupled to the reference voltage. The load device may comprise a current mirror that is coupled between the first and second input of the voltage comparator. The current mirror may be configurable by select transistors. Alternatively, the load device may be a hard-wired current mirror, and a multiplexer may be used to select whether the first input signal or the second input signal is connected to a first or second side of the current mirror. Configurable dummy loads may be added at appropriate nodes to optimize the capacitive load and increase the speed of the amplifier. Equalization devices may be coupled between the first and second inputs of the voltage comparator, and between the first input signal and the second input signal.

A universal input switching power supply has the rectifier, a signal detecting unit detecting a voltage of an external AC power and outputting a detecting signal, a PFC circuit converts a first DC power from the rectifier to a second DC power with different voltage according to the detecting signal; and a parallel and serial type DC to DC converter converting the second DC power with different voltage to a constant voltage of the third DC power. The parallel and serial type DC to DC converter has a transformer having a primary and secondary coils and physically changes a turn ratio of the primary and secondary coils of a transformer thereof according to a voltage ratio of the second DC power and the third DC power. Accordingly, the universal input switching power supply has good transforming efficiency at different AC power source conditions.

The invention discloses an electronic voltage transformer using data fusion technology and an error calibration method thereof. The error calibration method comprises the following steps of: acquiring a secondary measured voltage by using a capacitive voltage divider and a sampling resistor R, accessing the voltage to a data acquisition processor for sampling, and tracing the frequency of the voltage; accessing a signal of a temperature sensor to the data acquisition processor, and computing the temperatures of measuring points; dynamically computing a divided voltage ratio of the capacitive voltage divider according to the temperature variation of the measuring points by using data acquisition device processing software so as to modify a transformation ratio error of the transformer; dynamically computing phase deviation according to signal frequency variation by using the data acquisition device processing software so as to modify a phase error; and outputting a digital sampling value through an optical fiber interface. The device is simple in structure, safe and practical; errors caused by manufacturing factors, temperature and signal acquisition circuits and the like can be effectively modified and restrained; and the measuring accuracy, temperature stability and transient performance of the electronic voltage transformer according to a capacitive voltage division principle are improved.

The invention proposes a bootstrap voltage refresh control circuit, a voltage converting circuit and a relevant control method. The bootstrap voltage refresh control circuit detects the bootstrap voltage in the voltage converting circuit, provides the enhanced on-off driving signal for a high side switch of the voltage converting circuit based on the bootstrap voltage, and controls the charging of the bootstrap voltage through controlling the on-off switch of the high side switch and a low side switch of the voltage converting circuit based on bootstrap voltage. The bootstrap voltage refresh control circuit can recover the bootstrap voltage in time through adjusting the on-off switch of the high side switch and the low side switch when the bootstrap voltage is insufficient, without increasing more switch devices. The voltage converting circuit comprising the bootstrap voltage refresh control circuit has excellent work stability, and the circuit can work normally when the input voltage and the output voltage are closer, and the circuit has smaller power consumption.

A method and apparatus for controlling power conversion. In one embodiment, the method comprises computing a voltage ratio based on a voltage conversion in a resonant converter; comparing the voltage ratio to a threshold; and controlling, independent of switching frequency of the resonant converter, power output from the resonant converter based on whether the voltage ratio satisfies the threshold.

Power from a high voltage battery (10) (for example 36V) is supplied through an inverter (12) to a motor generator (14). A low voltage battery (20) (for example 12V) is connected through a reactor (18) to the neutral point of the motor generator (14). A voltage ratio of the low voltage battery (20) to the high voltage battery (10) is preferably from 1:2 to 1:4. In order to set the neutral point voltage to a desired charging voltage into the low voltage battery (20), the inverter (12) is controlled so as to follow a current distortion phenomenon. In this way, in a dual-power source system with a voltage ratio of a low voltage battery (20) to a high voltage battery (10) between 1:2 and 1:4, voltage switching means for use in charging a charge voltage of a high voltage side into a low voltage source can be implemented at low cost.

Power from a high voltage battery (10) (for example 36V) is supplied through an inverter (12) to a motor generator (14). A low voltage battery (20) (for example 12V) is connected through a reactor (18) to the neutral point of the motor generator (14). A voltage ratio of the low voltage battery (20) to the high voltage battery (10) is preferably from 1:2 to 1:4. In order to set the neutral point voltage to a desired charging voltage into the low voltage battery (20), the inverter (12) is controlled so as to follow a current distortion phenomenon. In this way, in a dual-power source system with a voltage ratio of a low voltage battery (20) to a high voltage battery (10) between 1:2 and 1:4, voltage switching means for use in charging a charge voltage of a high voltage side into a low voltage source can be implemented at low cost.

Certain aspects of a system for controlling power for a network interface controller device may comprise a precision voltage comparator that may instantaneously detect ramp up of a main voltage corresponding to a main voltage source in order to control the network interface controller device. A power monitor may detect when a threshold voltage of the main voltage is reached during the ramp up. A main voltage source switch and an auxiliary voltage source switch may switch an output from an auxiliary voltage to the main voltage source without the switches being simultaneously on. The power monitor may determine whether the main voltage is ramping up in excess of a determined rate and if so, may decrease a rate at which the main voltage ramps up. A current limiter and / or the power monitor may monitor and limit an inrush current caused during main voltage ramp up.

A liquid crystal display is provided with: a tap adjustment register for adjusting a gray scale level to a gray scale voltage in intermediate portions close to the end portions of the gamma characteristic; and a partial-voltage-ratio adjustment register for adjusting a ratio of a gray scale voltage among a plurality of gray scale levels in the intermediate portions close to the end portions of the gamma characteristic, in addition to an amplitude adjustment register for adjusting an amplitude of a gamma characteristic which determines a relation between gray scale levels and gray scale voltages or brightness levels on a display panel; a gradient adjustment register for adjusting a gradient of intermediate portions of the gamma characteristic while fixing end portions of the gamma characteristic; and a fine adjustment register for finely adjusting the intermediate portions of the gamma characteristic for each gray scale level.

The invention provides a LCD including an insulating substrate; a plurality of first signal lines formed on the insulating substrate; a plurality of second signal lines crossing and insulated from the first signal lines; a plurality of thin film transistors (TFT) coupled with the first and second signal lines; and a plurality of pixels including a plurality of first sub-pixel electrodes coupled with the TFTs and a plurality of second sub-pixel electrodes capacitively coupled with the first sub-pixel electrodes, wherein the pixels include a red (R) pixel, a green (G) pixel, and a blue (B) pixel and a voltage ratio or an area ratio of the second sub-pixel electrode with respect to the first sub-pixel electrode is different among the R, G, and B pixels to improve a brightness ratio of R, G, and B components at a lateral position.

The invention relates to the technology of photovoltaic grid-connected inverter, in particular to an online detection method of insulating resistance to ground of a photovoltaic grid-connected inverter. The method comprises the following steps of: by sampling an output voltage VPV of a photovoltaic cell and enabling a switch S1 in a resistance switch circuit to be in opening or closing state, disconnecting or connecting a resistor R5 from or to an upper bridge arm, and then sampling a voltage signal of a dividing voltage output end of a lower bridge arm to obtain a voltage ratio equation of anode to ground of photovoltaic cell and cathode to ground of the photovoltaic cell, thereby online calculating a insulating resistance R+ of anode to ground of the photovoltaic cell and an insulating resistance R- of cathode to ground of the photovoltaic cell in real-time and accurately. The method has simple calculation process and high detecting precision; by adopting the method, the online and real-time detection of anode-to-ground resistance of the photovoltaic cell and the cathode-to-ground resistance of the photovoltaic cell is achieved, the photovoltaic grid-connected inverter is guaranteed to work safely and reliably.

A segmented slope compensation circuit applicable to a BUCK converter belongs to the technical field of an electronic circuit. An oscillator circuit is used for introducing output voltage informationof the BUCK converter, a negative input end voltage of an operational amplifier is clamped to a positive input end voltage thereof, a first capacitor is charged by a current mirror, the negative inputend voltage, namely a slop voltage signal, of the operational amplifier is obtained, the slop voltage signal is compared with a second reference voltage to obtain a periodic slope voltage signal, a slope current generation circuit is used for generating compensation slopes with different slope rates under different duty ratios, a slope voltage correlated to the duty ratios is generated on a sampling resistor after passing through a slope summing circuit, and a base current compensation circuit is used for stabilizing a system. Compared with a traditional slope compensation circuit, the segmented slope compensation circuit has the advantages that the system stability is improved by employing different slope compensation rates under different duty ratios; and with the adoption of a triode as a buffer, the segmentation accuracy is improved.

The invention discloses an automatic reset detection circuit for power up and power failure. The circuit comprises a power supply detection circuit (1), a band-gap reference circuit (2), a voltage comparator (3), a ring-shaped RC (remote control) oscillator (4) and an M-bit counter (5), wherein the power supply detection circuit (1) is used for detecting change of power supply voltage, when the power supply voltage is higher than preset threshold voltage, the voltage comparator (3) outputs a high voltage level, the ring-shaped RC oscillator (4) and the M-bit counter (5) begin to work, after 2M periods, an output Reset signal is changed to the high voltage level, and the power up reset detection is completed; when the power supply voltage is lower than the preset threshold voltage, the voltage comparator (3) outputs a low voltage level, the ring-shaped RC oscillator (4) and the M-bit counter (5) stop working, the output Reset signal is changed to the low voltage level, and the power failure reset detection is completed. The automatic reset detection circuit is simple in structure and easy to implement, and further has the power up and power failure reset detection functions simultaneously.

The invention discloses a distributed photovoltaic power station monitoring system. The distributed photovoltaic power station monitoring system comprises a photovoltaic array, a data monitoring unit, a data acquisition unit, a data processing unit and a power supply unit; the data monitoring unit comprises a DC monitoring unit and an AC monitoring unit; the DC monitoring unit comprises a hall voltage sensor and a hall current sensor; the AC monitoring unit comprises an AC electrical quantity transducer; the data acquisition unit comprises a CPU, a memory, a plurality of meteorological sensors, a temperature sensor for detecting the working temperature of a battery module, and an analog-digital converter; the data processing unit is in two-way signal connection with the CPU by use of a communication module; the data processing unit is further in wireless connection with the system monitoring terminal. The invention also provides a fault diagnosis method of the distributed photovoltaic power station monitoring system; based on the simulation result of the data processing unit, the photovoltaic array captures losses, the system losses, the current ratio and the voltage ratio to perform fault analysis and diagnosis; the diagnosis method is simple and the diagnosis results are accurate and reliable.

Disclosed is a switched-mode power supply including an inductor which is connected between a voltage input terminal to which a DC voltage is input and an output terminal to which a load is connected, a driver switching element which intermittently feeds a current to the inductor and a control circuit which generates a control pulse according to a feedback voltage from output side and controls on / off of the driver switching element. The control circuit includes a voltage comparison circuit which compares the feedback voltage to a predetermined voltage and a pseudo ripple generator circuit which generates a pseudo ripple voltage having a predetermined amplitude, and the control circuit injects a ripple component in a transmission path of the feedback voltage based on the pseudo ripple voltage generated by the pseudo ripple generator circuit.

The lower power on-chip power supply noise sensor detects high frequency overshoots and undershoots of the power supply voltage. The sensor has two resistor chains that span the full power rail, with a reactive element to form a low pass filter as part of one of the resistor chains. By this expedient the high frequency transient behavior differs between the two chains, while the low frequency behavior is equivalent. This allows a voltage comparison to be made with comparators. The comparator output can be latched or transmitted as a sampling signal.

The invention discloses a three-phase hybrid multilevel inverter circuit, which is formed by cascading a level circuit module and a bridge circuit module. The bridge circuit module is a three-phase bridge circuit module which consists of a direct current supply, a clamp diode and a capacitor; the level circuit module is an asymmetric four-level circuit module which consists of a direct current supply, a clamp diode and an asymmetric four-level converter; and the output of the three-phase hybrid multilevel inverter circuit equals to the superposition sum of the outputs of each cascaded unit. By adopting different modulation methods, a multi-level output can be realized and the number of the output levels can be changed by changing the voltage ratio of the input current. The input direct current supply can be acquired by the solar energy, wind energy, fuel cells, storage batteries or isolated transformer rectifier units. Forming a hybrid cascaded multilevel converter by cascading the symmetric multilevel converter and the three-phase bridge circuit, the three-phase hybrid multilevel inverter circuit has the advantages of improving the output power quality, reducing the output harmonic waves and enhancing the reliability of the system due to the ability for outputting a plurality of levels.

A bandgap reference circuit includes an input circuit having a first FET, a second FET, and a first resistor, wherein a first node is connected to the first FET having a first threshold voltage, the first resistor is connected between a second node and the second FET having a second threshold voltage; a mirroring circuit for controlling two output currents respectively derived from the first and second nodes, and maintaining the two output currents to a specific current ratio; and an operation amplifier connected to the first node, the second node of the input circuit, and the mirroring circuit, for controlling two voltages respectively at the first and second nodes of the input circuit to a specific voltage ratio; wherein the first FET and the second FET are both operating in the subthreshold region, the first threshold voltage is larger than the second threshold voltage, and the two output currents are independent of temperature.

The invention discloses an energy storage system realizing bidirectional electric energy flow and a control method thereof, belonging to the technical fields of electric energy conversion and storage systems and control methods thereof. The invention aims to satisfy efficient energy conversion and storage in the energy storage system realizing bidirectional electric energy flow, combines series-parallel connection switching technology of the super-capacitor and the optically designed bidirectional direct-current power inverter, realizes design of the variable voltage system adopting low voltage grade power source for power supply, reduces the volume of the power supply and saves the cost, and the power supply voltage and the system voltage can change independently, and the bidirectional direct-current power inverter with topological structure being optimally designed solves the problems of big volume of the inductor in the power inverter, high cost and high loss and is especially suitable for the occasions with instantaneous power feedback energy, and the voltage ratio of the power inverter is controlled within 2 by the novel series-parallel connection switching technology of the super-capacitor, thus being conductive to controlling the inverter and improving the efficiency of the inverter.

Disclosed is a memory array in which the lower of two supply voltages from two power supplies is dynamically selected for bitline pre-charge operations. In the memory array, a voltage comparator compares the first supply voltage on a first power supply rail to a second supply voltage on a second power supply rail and outputs a voltage difference signal. If the voltage difference signal has a first value indicating that the first supply voltage is equal to or less than the second supply voltage, than a control circuit ensures that the complementary bitlines connected to a memory cell are pre-charged to the first supply voltage. If the voltage difference signal has a second value indicating that the first supply voltage is greater than the second supply voltage, then the control circuit ensures that the complementary bitlines are pre-charged to the second supply voltage. Also disclosed is an associated method.