1973 results about "Inrush current" patented technology

A system and method for supplying power to a load and for controlling the power factor presented to the power line. Output voltage is controlled by a digital, outer, control loop, and inner, analog, control loop causes the input current to be substantially proportional to the input voltage at any particular point in the power line cycle. Thus, the system presents a load to the power line that appears to be purely resistive. The use of an analog multiplier is not required, nor is sampling of input voltage. Limiting of inrush current provides for brown-out protection and soft-start.

A two-wire smart load control device, such as an electronic switch, for controlling the power delivered from a power source to an electrical load comprises a relay for conducting a load current through the load and an in-line power supply coupled in series with the relay for generating a supply voltage across a capacitor when the relay is conductive. The power supply controls when the capacitor charges asynchronously with respect to the frequency of the source. The capacitor conducts the load current for at least a portion of a line cycle of the source when the relay is conductive. The load control device also comprises a bidirectional semiconductor switch, which is controlled to minimize the inrush current conducted through the relay. The bidirectional semiconductor switch is rendered conductive in response to an over-current condition in the capacitor of the power supply, and the relay is rendered non-conductive in response to an over-temperature condition in the power supply.

The present invention is directed to Bidirectional Multimode Power Converter which employs a high frequency dynamically varying amplitude modulation and voltage steering method to convert the source AC or DC voltages to output AC or DC voltages, with programmable output voltage levels, output voltage frequency and duration. The inrush current control, turning off the idle converter, line voltage brown out protection, soft start, high pre-charge voltage generation, soft shut down of converter, dimming operation modes are inherent characteristics of the Bidirectional Multimode power converter. The Bidirectional Multimode Power Converters of the present invention facilitates bidirectional conversion and coupling multiple bidirectional sources and or loads.

The Bidirectional Multimode Power Converter of the present invention supports local and remote control for changing operational characteristics of the converter on demand or on a programmed time of the day for a specified duration of time.

A power converter used in the current control circuit and control method, consisting of a converter, a voltage divider circuit, a current sampling circuit, a first gain circuit, a differential amplifier, a second gain circuit, a multiplier, a saw tooth wave generator, a modulation comparator, and a driver. The invention samples inductor current through the current sampling circuit and generates the current sense signal, then processes again. With the differential amplifier, it compares the feedback voltage from the voltage divider circuit with the reference voltage, and the results along a modulation comparator output a drive signal to control the duty cycle in order to avoid the generation of inrush current. The present invention avoids inrush current caused by the large drive signal and achieves a good response rate and better system stability.

A circuit and corresponding method for controlling inrush current in an AC-DC power converter by providing a relay and a control circuit for limiting inrush current efficiently during cold startup, warm startup, and power line disturbance conditions. The relay is preferably connected in series with a bulk capacitor of the converter and in parallel with a limiting resistor and switch for shunting the resistor and switch so as to improve efficiency during operating conditions, at reduced size and cost. A preferred embodiment includes use of the circuit for AC-DC converters having active power factor correction.

A fault indicator for indicating the occurrence of a fault in an electrical conductor is automatically configured for an overhead application or for an underground application. The fault indicator has a housing, a battery, a display for indicating the occurrence of a fault, a current sensor for sensing the load current in a monitored conductor, and electromagnetic field sensor to sense the electromagnetic field about the conductor, and a microcontroller for determining whether a fault condition occurred, for determining the magnitude of the electromagnetic field, and for configuring the fault indicator in the overhead configuration if the electromagnetic field is above a predetermined magnitude or configuring the fault indicator for the underground mode if the field is below the predetermined magnitude. In the overhead configuration, voltage inrush restraint is enabled, the fault response time is set within a range of 1 to 50 ms, and the display is operated in bright or dims modes depending upon ambient lighting levels. In the underground configuration, inrush current restraint is enabled, the fault response time is set within a range of 1 to 24 ms, and the display is operated in only the dim mode. Related methods are also disclosed.

Apparatus and methods for selective protection of an electrical load from disturbances on an input power line. A power protection circuit includes a selectively variable inrush current limiting circuit and a switch for disconnecting the input power line from the load. A control circuit determines that the electrical load is in a first operational state, such as a standby mode or normal operation, or a second operational state, such as full operation at rated current. The power protection circuit provides variable inrush current limiting to the electrical load in response to a first category of disturbances when the electrical load is in the first operational state. The power protection circuit inhibits disconnecting the electrical load in response to a second category of disturbances when the electrical load is in the second operational state. Species of selectively variable current limiting circuits are also described.

An idle reduction vehicle has a relay in a power supply line from a battery to a starter motor. The relay is driven between a contact-side state, in which contacts short-circuit, and a resistor-side state, in which the contacts are opened and a resistor is serially inserted into the power supply line. At an engine restart from idle reduction, an ECU drives the relay to the resistor-side state and starts energization to the motor, thereby suppressing an inrush current. The ECU detects a contact-side state fixation abnormality of the relay based on a battery voltage at the time when the ECU drives the relay to the resistor-side state and energizes the motor. The ECU detects a resistor-side state fixation abnormality of the relay based on the battery voltage at the time when the ECU drives the relay to the contact-side state and energizes the motor.

In one embodiment, a soft start circuit includes a slew rate controller to limit inrush current to a voltage regulator during start up. The output voltage of the regulator may be compared to a previous sampled value to determine the slew rate of the output voltage. The slew rate of the output voltage may be controlled by adjusting the current limit of the regulator. The current limit of the regulator may be adjusted using digital circuits, such as a counter and a digital to analog converter, or analog circuits using a pulsed current source, for example. The slew rate may be controlled to exceed a target slew rate or to stay within a range of slew rate limits.

The invention provides an identification method for transformer inrush current which belongs to power system main equipment relay protection technology field. The method has characteristics in that the method identifies inrush current and fault current base on waveform correlation degree. By comparison with each sampling point algebraic sum in dynamic differential current short data window, non-saturation region of transformer under inrush current and fault current is searched, two form standard sine waves are constituted of max value and position of sampling data in non-saturation region, then differential current sampling waveform in non-saturation region and two form standard sine waves correlation degrees are calculated respectively, inrush current and fault current are differentiated according with correlation coefficient average. The method can open longitudinal differential protection rapidly when internal fault and no-load closing with fault occur in transformer operation; and can lock longitudinal differential protection reliably when on-load closing occurs inrush current.

A DC high power distribution system provides power to a load in parallel with one or more storage capacitors. The system includes a hot-swap controller and an array of parallel-connected transistors connected in series between a DC source and the capacitors/load. A power contactor is connected in parallel to the transistor array, both of which are connected to control outputs of the controller. The controller monitors various circuit conditions of interest, such as input over-voltage, input under-voltage, and over-current. If the circuit conditions meet designated parameters, the controller activates the transistors for charging the capacitors, for limiting inrush current. After charging, the controller activates the power contactor for shunting the transistors and carrying the 150+ ampere current during ongoing operation. If any of the monitored circuit conditions fail to meet designated parameters, the controller halts operation of the circuit by deactivating the power contactor and/or transistors.

A power circuit for protecting against high pulse load current and inrush current is disclosed. The power circuit comprises a buck-boost module and a PFC controller operatively coupled with the buck-boost module. The PFC controller is configured to receive an input voltage feedback, an output voltage feedback, and a current feedback, and is configured to utilize one of an Integral Gain Compensation (IGC) and an Integral Value Compensation (IVC) to control the high pulse load current and inrush current in the power circuit.

A current limit circuit regulates the current flow through a power switch 90 by measuring the current through the switch 90 and comparing it to a reference voltage V_REF that represents the limit current. When the current through the power switch 90 is greater than the limit current, the current in the power switch 90 is pulled lower by a driver circuit 92 which controls the power switch 90. By using a current limit reference voltage that has two levels, the power switch 90 has two current limit thresholds. Using a comparator 94 to compare the input voltage of the power switch 90 to the output voltage of the power switch 90, an output signal is generated to control the current limit threshold. When the input voltage and output voltage has a large differential voltage, a lower current limit threshold voltage is selected. When the input voltage and output voltage has a small differential voltage, an upper limit threshold voltage is selected.

According to the invention, a charge pump circuit (21) has, as switching means turned on when a capacitor (C1) is charged, transistors (P1 to P3) connected in parallel between one end of the capacitor (C1) and an input terminal (T1). When the capacitor (C1) is charged, a controller (CNT) determines which of the transistors (P1 to P3) to drive based on the results of monitoring of the input and output voltages by first and second detectors (DET1, DET2). Thus, even if the level of the input voltage varies, it is possible to reduce in-rush current at start-up without causing a drop in the output voltage or a loss in efficiency.

A differential protection system for power transformers using Rogowski coils as current sensors can support an inrush current detection method based on sensing lows in the derivative of the sensed current. Effective detection of power transformer inrush conditions can enable blocking of a protection relay during inrush where the differential current may exceed a differential threshold value indicative of a fault without the presence of an actual fault. The outputs of the Rogowski coils, being proportional to the first time derivative of the sensed current, may be useful in the inrush detection method. Also, with reduced saturation concerns, the Rogowski coil protection system may employ a single slope response with increased sensitivity. A discrete time sampling technique for identifying low di/dt portions within the sensed current also may be useful in detecting power transformer inrush conditions.

To suppress the magnetizing inrush current occurring when supplying power of three phases of the transformer are performed simultaneously using three single-phase circuit breakers or a non-phase segregated operation-type circuit breaker, without providing a circuit breaker with a resistor or other equipment. A magnetizing inrush current suppression method for transformer suppresses a magnetizing inrush current occurring at the start of energizing of a three-phase transformer 300, when a three-phase power supply 100 is input to a terminal of each phase by means of a three-phase circuit breaker 200. In the method, by integrating phase voltages or line-to-line voltages on the primary side or the secondary side or the tertiary side when three-phase AC voltages are applied in a steady state to the transformer 300, steady-state magnetic flux 4, 5, 6 for each phase of the transformer is calculated, and the polarity and magnitude of the residual magnetic flux 7, 8, 9 of each phase of the transformer after the circuit breaker 200 shuts off the transformer are calculated, and the three-phase circuit breaker is caused to close simultaneously in a region 13 in which three phases overlap, each of the three phases having the polarity of the steady-state magnetic flux 4, 5, 6 equal to the polarity of the residual magnetic flux 7, 8, 9 for each phase of the transformer.

To provide a magnetizing inrush current suppression device for transformer and control method of same, which accurately calculates the residual magnetic flux when a transformer installed in a non-solidly earthed system, is interrupted by circuit breakers, and which enables suppression of the magnetizing inrush current occurring when three single-phase circuit breakers or single-phase circuit breakers are used for simultaneously supplying power to three phases of the transformer, without providing a circuit breaker with a resistor or other equipment to enlarge the circuit breaker. The device has steady-state magnetic flux calculation means for calculating the line-to-line steady-state magnetic flux of three-phase power supplies, residual magnetic flux calculation means for calculating the primary line-to-line residual magnetic flux of the transformer when the circuit breakers interrupt the transformer, phase detection means for detecting a phase at which the polarity and magnitude of the calculated steady-state magnetic flux and residual magnetic flux coincide for each line-to-line. Closing control means firstly causes only two-phase of the circuit breakers, which are connected with the line-to-line, to close at the detected phase, and then causes the remaining one-phase circuit breaker to close.