Topic
Constant current
About: Constant current is a research topic. Over the lifetime, 23244 publications have been published within this topic receiving 158637 citations.
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TL;DR: In this article, the effect of the charging protocol on the cycle life of a commercial 18650 Li-ion cell was studied using three methods: (1) constant current charging, (2) constant power (CP) charging, and (3) multistage constant current (MCC).
504 citations
Patent•
22 Dec 1976
TL;DR: In this paper, a current sensing circuit arrangement for controlling the response of a circuit electrically isolated from the circuit in which sensed current is flowing is disclosed, where the input portion of the circuit arrangement provides paths for D.C. input current, one through a current sensor element and another through a light emitting diode circuit.
Abstract: A current sensing circuit arrangement for controlling the response of a circuit electrically isolated from the circuit in which sensed current is flowing is disclosed. The input portion of the circuit arrangement provides paths for D.C. input current, one through a current sensing element and another through a light emitting diode circuit. The current-to-voltage characteristic of the current sensing element is such that changes in voltage across the element are substantially less than proportional to changes in current through the element. The light emitting diode circuit is connected in parallel with the current sensing element and produces light energy dependent on the voltage across the element. Light energy so produced is received by an electrically isolated light sensitive semiconductor device which device is for controlling the response of an output control circuit.
380 citations
04 Mar 2012
TL;DR: In this article, a multi-temperature LiNi-CoMnO 2 cathode and graphite-based anode was used to simulate thermal buildup for a constant current discharge scenario, and the model was validated for a lithium cell with an independent drive cycle showing voltage accuracy within 2%.
Abstract: The growing need for accurate simulation of advanced lithium cells for powertrain electrification demands fast and accurate modeling schemes. Additionally, battery models must account for thermal effects because of the paramount importance of temperature in kinetic and transport phenomena of electrochemical systems. This paper presents an effective method for developing a multi-temperature lithium cell simulation model with thermal dependence. An equivalent circuit model with one voltage source, one series resistor, and a single RC block was able to account for the discharge dynamics observed in the experiment. A parameter estimation numerical scheme using pulse current discharge tests on high power lithium (LiNi-CoMnO 2 cathode and graphite-based anode) cells under different operating conditions revealed dependences of the equivalent circuit elements on state of charge, average current, and temperature. The process is useful for creating a high fidelity model capable of predicting electrical current/voltage performance and estimating run-time state of charge. The model was validated for a lithium cell with an independent drive cycle showing voltage accuracy within 2%. The model was also used to simulate thermal buildup for a constant current discharge scenario.
360 citations
07 May 2007
TL;DR: In this article, different DC-DC converter topologies are discussed which can be adapted to feed a constant current into a LED load, and the features of different pulsating current waves are investigated concerning their peak, RMS and high frequency content.
Abstract: This paper deals with power electronic drivers for LED strings. Due to the enormous progress recently achieved in the technology of light emitting diodes (LEDs) it can be expected that LEDs lighting will replace incandescent and halogen bulbs in general illumination in the near future. A LED light source typically consists of a series connection of single LED cells. It shows a similar behaviour like a zener diode. For efficiency reasons LED strings can not be supplied via series resistors but need switched mode power drivers with current control. Different standard DC-DC converter topologies are discussed which can be adapted to feed a constant current into a LED load. For future LED driver developments it has to be considered that LEDs can also efficiently be supplied by pulsating currents. This simplifies the converter and control design and reduces the number of components. Hence, different converter topologies are studied which are able to stabilise the average value of a pulsating output current. This also includes topologies with galvanic isolation. Resonant operating LED drivers seem to be specially suited for this task. Hence, a series resonant galvanic isolating LED driver is studied in detail. Under certain conditions this converter does not need a current sensor to stabilise the average current in the LED load. Finally, the features of different pulsating current waves are investigated concerning their peak, RMS and high frequency content.
359 citations
Patent•
16 May 2016
TL;DR: In this article, a ballast circuit is disclosed for inductively providing power to a load, which includes an oscillator, a driver, a switching circuit, a resonant tank circuit and a current sensing circuit.
Abstract: A ballast circuit is disclosed for inductively providing power to a load. The ballast circuit includes an oscillator, a driver, a switching circuit, a resonant tank circuit and a current sensing circuit. The current sensing circuit provides a current feedback signal to the oscillator that is representative of the current in the resonant tank circuit. The current feedback signal drives the frequency of the ballast circuit causing the ballast circuit to seek resonance. The ballast circuit preferably includes a current limit circuit that is inductively coupled to the resonant tank circuit. The current limit circuit disables the ballast circuit when the current in the ballast circuit exceeds a predetermined threshold or falls outside a predetermined range.
347 citations