3641 results about "Over current protection" patented technology

The present invention discloses a primary-side feedback switching power supply that uses a sample-and-hold circuit to obtain a corner voltage of a harmonic wave voltage while the primary-side auxiliary winding is operating at a discontinuous mode as a feedback control, and provides both voltage regulation and current limit functions. A stable voltage output is provided within the nominal input voltage and nominal output load, such that when the output reaches a current limit, the output voltage drops but the output current is controlled to remain unchanged, so as to provide an over-current protection.

A protection circuit for a boost power converter provides input under-voltage protection and output over-voltage and over-current protection. The protection circuit includes a control power MOSFET connected in series between the ground of the boost power converter and the ground of the load. The arrangement of the circuit makes it easy to drive the gate of an N-channel power MOSFET and is ideal for current-limiting control, which utilizes the Rds-on of the MOSFET as a current sensing element. Neither a specific gate-driver nor a current sensing resistor is required, and thus high efficiency can be achieved. Furthermore, the slow slew-rate at the gate of the MOSFET provides a soft-start to the load. The protection circuit includes a temperature compensation circuitry to offset the variation of the Rds-on. A time delay circuit prevents the switching elements and protection elements from overload damage.

A microprocessor based overcurrent trip unit which generates trip signals as an adjustable function of current and time, has a visual representation of the trip function on a front panel with 2-color LEDs associated with the trip function serving as indicators of trip conditions when red, and of a selected programmable parameter when green. The green LEDs flash to indicate parameter selected for modification in a program mode and illuminate steady in a view mode.

A resonant switched power converter having switching frequency controlled in response to an output voltage thereof achieves over-current protection such as at start-up or under short circuit conditions using a resonant tank circuit which provides a notch filter in addition to a band pass filter. A additional band pass filter provided in the resonant tank circuit achieves increased power transfer to a load and reduced circulating resonant currents and conduction losses. The inductances of the preferred LCLCL tank circuit or other tank circuit with two pass band filters and a notch filter may be integrated into a single electrical component.

System and method for protecting a power converter. The system includes a duty-cycle detection component configured to receive a modulation signal, determine a first duty cycle corresponding to a first period of the modulation signal, compare the first duty cycle with a threshold duty cycle, and generate a duty-cycle comparison signal. Additionally, the system includes a threshold generator configured to receive the duty-cycle comparison signal and generate a threshold signal corresponding to a second period of the modulation signal, the second period being after the first period, and a comparator configured to receive the threshold signal and a first signal and to generate a first comparison signal. The first signal is associated with an input current for a power converter. Moreover, the system includes a pulse-width-modulation component configured to receive the first comparison signal and generate the modulation signal for adjusting the input current for the power converter.

Disclosed is an adjustable over current protection circuit which advances the timing of enabling an over current protection mechanism according to an input voltage, therefore the delay problem resulting from the non-instant response of the over current protection circuit is compensated with a low power loss. The over current protection circuit includes a voltage divider, a voltage-to-current converting circuit, an adjusting circuit and a comparing circuit. The voltage divider divides an input voltage to generate an adjusted input voltage, and the adjusted input voltage is converted into an adjusted input current by the voltage-to-current converting circuit. The adjusting circuit then adjusts a current sensing voltage according to the adjusted input current to generate an adjusted current sensing voltage. Finally, the comparing circuit compares the adjusted current sensing voltage with a predetermined over current protection reference voltage to selectively enable the over current protection mechanism according to a comparison result.

In a method and apparatus for controlling power factor correction in mixed operation modes, a frequency of the input voltage is obtained by detecting the zero crossing points of the input voltage. A peak of the input voltage is obtained by detecting input voltage with 90 degree phase. Thus, the present invention predicts the input voltage by its frequency and peak and the characteristic of the sine wave. A digital signal processor computes the duty and frequency of a boost switch, switching the operation mode of the boost converter among continuous mode, critical mode and discontinuous mode according to input voltage or the load. According to another aspect, the operation is switched to critical mode from the average current mode when a zero current is detected before the charging and recharging cycle of the boost switch is finished. Overcurrent protection may be achieved by controlling current in response to detected voltage to provide a substantially constant power level. The overcurrent protection may be adaptive in nature.

A cordless power tool uses a lithium battery as a power source of a motor and is provided with an overcurrent protection circuit. The circuit allows an overcurrent to instantaneously flow at the start-up time of the motor and shuts off an overcurrent which may flow when the motor is brought into a locked state during the use of the power tool.

The embodiment of the invention discloses an over-current protection circuit and an over-current protection method. The over-current protection circuit comprises a power source management chip, a level shifter, a GOA circuit driven by a baseplate array row and a current detection circuit, wherein the current detection circuit comprises a current detection module, a current-to-voltage converter and a voltage comparer, a first control end of the power source management chip is connected to an input end of the level shifter, an output end of the level shifter is connected to an input end of the GOA circuit, an output end of the GOA circuit is connected to a first input end of the current detection module, an output end of the current detection module is connected to an input end of the current-to-voltage converter, an output end of the current-to-voltage converter is connected to an input end of the power source management chip, and a second control end of the power source management chip is connected to a second input end of the current detection module. By implementing the over-current protection circuit and the over-current protection method disclosed by the embodiment of the invention, a panel can be prevented from being burnt.

System controller and method for protecting a power converter. The system controller includes a first controller terminal configured to output a drive signal to a switch to affect a first current flowing through a primary winding of a power converter. The power converter further includes a secondary winding coupled to the primary winding, and the drive signal is associated with one or more switching periods. Additionally, the system controller includes a second controller terminal configured to receive a sensing voltage from a sensing resistor. The sensing voltage represents a magnitude of the first current flowing through the primary winding of the power converter. The system controller is configured to process information associated with the sensing voltage and a reference voltage, and determine whether an average output current of the power converter is larger than a current threshold.

System and method for protecting a power converter. An example system controller for protecting a power converter includes a signal generator, a comparator, and a modulation and drive component. The signal generator is configured to generate a threshold signal. The comparator is configured to receive the threshold signal and a current sensing signal and generate a comparison signal based on at least information associated with the threshold signal and the current sensing signal, the current sensing signal indicating a magnitude of a primary current flowing through a primary winding of a power converter. The modulation and drive component is coupled to the signal generator.

An LED driver circuit is provided for protecting one (or more) LEDs connected in series from over-current damages which may result from a short circuit condition. The driver circuit includes a current control circuit for receiving an input signal from a power source and providing a current output for powering the LED. A voltage sensor detects a voltage across the LED. An LED current restriction circuit such as a switching element restricts a current flow into the LED. A short circuit response circuit controls the LED current restriction circuit dependent on a comparison between the voltage detected by the voltage sensor and a predetermined threshold value. When the detected voltage is less than or equal to the threshold value, the response circuit determines a short circuit, and a signal is sent to the current restriction circuit to restrict current flow into the one or more LEDs.

In a voltage mode buck converter having a pair of switches connected in series by a phase node to be switched by a pair of drive signals generated from a first control signal, a phase resistor is connected between a multifunction pin and the phase node, and a controller generates a second control signal and a third control signal from the second drive signal to sense the voltage on the multifunction pin respectively to generate an over-current signal and a CCM mode switch signal to switch the converter between a CCM mode and a DCM mode.

In a control apparatus for a motor, an over-current protection circuit detects an abnormality in a motor current forcibly turns off a MOSFET. The over-current protection circuit has a timer function and a time switching function. In the timer operation, the over-current protection circuit stops an abnormality detection signal for an ON time period before producing the signal for an OFF time period when a current flowing through the motor exceeds a predetermined threshold value. The time switching function is for controlling to lengthen the OFF time period to a relatively larger value in comparison with the ON time period.

A resonant switched power converter having switching frequency controlled in response to an output voltage thereof achieves over-current protection such as at start-up or under short circuit conditions using a resonant tank circuit which provides a notch filter in addition to a band pass filter. A additional band pass filter provided in the resonant tank circuit achieves increased power transfer to a load and reduced circulating resonant currents and conduction losses. The inductances of the preferred LCLCL tank circuit or other tank circuit with two pass band filters and a notch filter may be integrated into a single electrical component.

In a voltage mode buck converter having a pair of switches connected in series by a phase node to be switched by a pair of drive signals generated from a first control signal, a phase resistor is connected between a multifunction pin and the phase node, and a controller generates a second control signal and a third control signal from the second drive signal to sense the voltage on the multifunction pin respectively to generate an over-current signal and a CCM mode switch signal to switch the converter between a CCM mode and a DCM mode.

In one implementation, a power converter includes an output stage integrated circuit (IC) in a group III-V die including a depletion mode group III-V transistor, and a driver IC in a group IV die. The driver IC is configured to drive the output stage IC. In addition, a group IV control switch in the group IV die is cascoded with the depletion mode group III-V transistor. The power converter further includes an overcurrent protection circuit for the depletion mode group III-V transistor, the overcurrent protection circuit monolithically integrated in the group IV die.

A string includes direct current electrical generating modules electrically connected in series to form a first end and a remote second end. A power line is electrically connected to one DC EGM at the first end. A return line is electrically connected to another DC EGM at the remote second end. A first string protector is in the power line of the string, and a second SP is in the return line of the string at the remote second end. One of the first and second SPs includes a number of an over current protector, an arc fault protector, a reverse current protector and a ground fault protector. The other one of the first and second SPs includes a number of an over current protector, an arc fault protector, a reverse current protector, a ground fault protector, and a remotely controlled switch in series with the power or return lines.

The invention discloses a singlechip-based induction motor variable frequency speed regulation control system. The system comprises a main circuit, an auxiliary power circuit, an inverter circuit, a control part, an over-current protection circuit, a rotation speed detection circuit and other peripheral circuits. A 16-bit high-performance signal controller dsPIC30F4011 which is produced by the Microchip Company is used as a control core by the system to perform speed regulation based on vector control motor excitation. A digital signal controller dsPIC30F4011 of the America Microchip Technology Company is used as a chip special for motor control, a digital signal processor (DSP) inner core is embedded, and the chip has quick data processing capacity and is provided with abundant input and output equipment and interface circuits; an intelligent power module (IPM) IRAMSIOUP 60A of the IR Company is an inverter switching device, so that the variable frequency speed regulation control system of an asynchronous motor is constructed; and the system has the characteristics that the system is simple to drive and easy to realize.

Circuit and method for providing over-current and overloading protection with a single additional pin. A converter controller circuit is provided that includes a voltage controlled oscillator and outputs upper and lower gating signals for driving the upper and lower driving transistors in a voltage converter, for example, in an inductor-inductor capacitor half-bridge circuit topology. A current sense input pin of the circuit receives a voltage corresponding to the current flowing in the half-bridge circuit. A feedback input pin has an external capacitor coupled to it and receives a voltage from an output voltage sensor at the output terminals. Over-current protection is provided by sensing the voltage at the current sense input pin with no external components needed. Overload protection is provided by utilizing the external feedback capacitor and the feedback input pin during overload conditions. Methods for providing over-current and overload protection are disclosed.

In a driving device (20) for driving an IGBT (1), a current measuring portion (22) measures a main current amount flowing through the IGBT (1). When the main current amount measured by the current measuring portion (22) reaches a predetermined reference level, a protection circuit portion (23) limits the main current at the IGBT (1) to protect it. A temperature measuring portion (24) measures the temperature of the IGBT (1). The control portion (25) adjusts the aforementioned reference level based on the temperature of the IGBT (1) measured by the temperature measuring portion (24). A control portion (35) stores setting values of the reference level as data.

A system that includes micro-electromechanical system switching circuitry is provided. The system may include a first over-current protection circuitry connected in a parallel circuit with the micro-electromechanical system switching circuitry for suppressing a voltage level across contacts of the micro-electromechanical system switching circuitry during a first switching event, such as a turn-on event. The system may further include a second over-current protection circuitry connected in a parallel circuit with the micro-electromechanical system switching circuitry for suppressing a current flow through the contacts of the micro-electromechanical system switching circuitry during a second switching event, such as a turn-off event.

An AC-to-DC adapter provides power to information handling systems at different power levels based on the power rating of the information handling system. An adapter manager sets a first lower level at an over current protection circuit unless the information handling system sends identification information that indicates the information handling system is rated to accept a second higher power level, such as by sending a low signal pulse through a serial communication line. While the identification information is present and external power is applied to the adapter, the adapter manager sets a second higher level at an over current protection circuit to allow output of a second higher power level.

The invention provides an intelligent high-voltage management system of an electric car. According to the intelligent high-voltage management system of the electric car, a signal collecting system collects the car operation state, failure detection object state and car posture state in real time; an intelligent high-voltage control unit receives an instruction of a vehicle control unit (VCU) and / or a battery management system (BMS), enables a high-voltage electricity distribution system to normally distribute electricity to vehicle high-voltage equipment and feeds back the execution result to the VCU and / or the BMS; meanwhile, fault diagnosis and detection are carried out on the high-voltage electricity distribution system according to collected data and received vehicle real-time interaction data; the fault type is determined according to a preset fault database, the high-voltage electricity distribution system is made to execute the high-voltage electricity on-off control logic under the preset fault types, and the diagnosis result is stored and sent; the high-voltage electricity distribution system caries out high-voltage electricity distribution, high-voltage electricity on / off control, circuit overcurrent protection and high-voltage pre-charging on all high-voltage devices of the car according to the instruction of the intelligent high-voltage control unit. The intelligent high-voltage management system of the electric car realizes intelligent management of high-voltage electricity of the whole car, and better improves the high-voltage safety of the electric car.

In one embodiment, a method is provided for a power converter system. The method includes: providing a primary current limit for the power converter system, wherein the power converter system has one or more transistors which can be switched on at a primary frequency to cause current to flow through an inductor of the power converter system; and using the primary current limit for over-current protection in the power converter system, wherein over-current protection does not employ any secondary frequency for switching of the one or more transistors and does not employ any secondary current limit.

The invention relates to a current differential protection method for a smart distribution network, which comprises: mounting current transformers and smart distribution terminals at the positions of all switches in the smart distribution network, wherein each smart terminal serves as an agent, the agents are connected with one another through an optical fiber Ethernet, and the positive directions of all currents is the direction from a system power supply to the end of a circuit; automatically detecting the working state of a communication network through the agents, and determining if to perform current differential protection; when the communication network fails to work normally, applying the conventional three-stage current protection; when the communication network works normally, applying current differential protection and using the current differential protection as main protection; and allowing a local agent to compute a differential current and a braking current according to the local switching current detected by the local agent and downstream switching current transmitted by a downstream agent and determine if the protection is actuated. The overcurrent protection is local backup protection, and the protection of an upstream agent is local remote backup protection.

A switching power supply comprises: a primary switching element for controlling an output voltage or an output current by switching the current of an input power supply circuit; a current detection circuit for detecting a current flowing through said primary switching element, based on the potential difference occurring across the ends of said primary switching element; and a switching control circuit for controlling said primary switching element so that the current does not exceed a predetermined value.

A constant-voltage power circuit incorporating an over-current protection circuit having a fold back current limiting capability operative through low input voltages, and being capable of arbitrarily setting current outputs. The constant-voltage power supply circuit is configured so that a voltage output with small amplitude from a differential amplifier circuit is subjected to amplitude expansion to be amplified to range fully from the ground potential approximately to the input voltage by means of an amplitude expansion circuit, which includes an inverter consisting of an NMOS transistor and a resistor, and that the voltage resulting from the amplitude expansion is subsequently input to the gate of a PMOS transistor configured to directly control an output transistor.

The invention discloses an efficient multi-mode DC-DC converter in a wide voltage conversion range. The multi-mode DC-DC converter comprises a Buck-Boost power conversion module, a driving module, a band gap reference module, an IC internal power supply module, a waveform generator module, a working mode selection module, a protection module, a voltage detection module, a current detection module, a soft starting module, a PWM controller module and an LDO controller module. The multi-mode DC-DC converter can realize total integration of a switching tube and a synchronous rectifying tube, and is externally connected with an inductor and an output filter capacitor; the input voltage range is 2.5 to 5.5 volts, the output voltage range of 2.5 to 5.5 volts is adjustable, the maximum output current is 1,000 milliamperes, the maximum working frequency is 1MHz, the precision of the output voltage is less than 5 percent, and a system enters an intermittent working mode during light load to realize the integral system efficiency of more than 80 percent; a control loop adopts double-loop control of voltage and current, realizes the control of a PWM mode and a PFM mode, and can realize LDO control in a specific voltage conversion range; and the over-temperature, over-voltage and over-current protection functions are realized.