555 results about "Buck converter" patented technology

The invention relates to the technical field of active damping control, and discloses a bidirectional DC-DC power supply active damping control system and method, and the system comprises a front-end AC input rectification module, an LLC resonant circuit, and a Buck converter module: the front-end AC input rectification module is used for converting an AC input voltage into a DC voltage; the LLC resonance circuit is used for inverting the rectified direct current voltage into alternating current with a set frequency and transmitting the alternating current to a secondary side through a transformer; and the Buck converter module is used for rectifying an alternating current signal and adjusting the alternating current signal into a required direct current output voltage, and further comprises an LC filter and an active damping control module. By adopting the active damping control method, the resonance peak caused by the LC filter can be effectively suppressed without additionally adding a physical resistor, so that the fluctuation of the output voltage is limited. According to the control strategy, the problems of power loss and heating caused by a traditional passive damping method are avoided, and the energy efficiency of the system is remarkably improved.

The invention discloses a low-output-ripple automatic-current-sharing interleaving buck converter and a control method thereof.The converter comprises a main power circuit and an auxiliary compensation circuit, and the main power circuit adopts two interleaving main branches to achieve voltage conversion and energy transmission; automatic current sharing of the circuit is realized through the integrated network switch module and PWM signal control; the auxiliary compensation circuit adopts a current mirror image compensation principle, and adjusts the magnitude of the compensation current by comparing the difference between the output current of the main power circuit and the reference current, so as to effectively suppress the output current ripple; the control method comprises the steps of output voltage monitoring, PI adjustment, duty ratio modulation and a complementary control mechanism, current ripple phase offset is ensured, and the system stability and efficiency are improved. Compared with the prior art, the method has the advantages that the complexity of a control system is reduced, the working efficiency is improved, the current ripples are effectively eliminated, and the method has relatively high practical value and popularization prospect.

The invention discloses an asymmetric non-isolated buck converter, a single-phase to two-phase converter and a single-phase to three-phase converter, and belongs to the technical field of converters, the asymmetric non-isolated buck converter comprises a cascaded buck unit and a non-isolated unit, the buck unit comprises one or more cascaded buck modules, each buck module comprises a first rectifier, and the output end of the first rectifier is vacant; the non-isolation unit comprises one or more cascaded non-isolation conversion modules. According to the invention, a traditional transformer structure with large volume and heavy weight is completely cancelled, and the number of devices is reduced while the power density of the converter is improved; and voltage reduction is carried out through the no-load voltage reduction unit, so that the voltage reduction capability is higher, and the input and output phase shift angle range can be expanded to a certain extent.

Systems and methods are described for managing charging and discharging of battery packs. In one or more aspects, a system and method are provided to minimize overcharging of battery cells of specific battery chemistries while still enabling fast charging cycles. In other aspects, a buck converter may be used to reduce a voltage of power used to charge the cells. In further aspects, a fast overcurrent protection circuit is described to address situations involving internal short circuits of a battery cell or battery pack. In yet further aspects, a bypass circuit is provided in series-connected battery packs to improve the charging of undercharged battery packs while also increasing the efficiency of the overall charging process. In other aspects, a circuit is provided that permits a controller to determine a configuration of battery packs. In yet further aspects, a system may determine a discharge current for a collection of battery packs based on each battery pack's state of health (SOH) and forward that determination to an external device.

A buck converter including a high-side switch, a low-side switch and a bootstrap (BOOT), under-voltage lockout (UVLO) circuit. The BOOT UVLO circuit includes a BOOT UVLO detection element configured to compare a BOOT voltage with a switch node (SW) voltage to determine an occurrence of a BOOT UVLO event. The BOOT UVLO detection element is configured to output an UVLO signal (UVLO_Z), in case of the BOOT UVLO event. The BOOT UVLO circuit further includes a logic gate configured to receive the UVLO_Z and a high-side ON, (HSON) signal, the HSON signal is for controlling a switching of the high-side switch. The logic gate is configured to negate the HSON signal when receiving the UVLO_Z while the HSON signal is ON, to thereby immediately switch OFF the high-side switch when the HSON signal is ON.

The invention provides a synchronous zero voltage modulation system and method of a cascade system, a medium and equipment wherein the synchronous zero voltage modulation system of the cascade system comprises a power circuit module and a modulation system; the power circuit module comprises a front-stage four-switch buck-boost converter and a rear-stage LCC-LCC compensated bidirectional wireless charging system; the modulation system comprises a voltage compensation module, a current compensation module, a current comparison module, a synchronization module and a switch driving signal generation module, the output end of the voltage compensation module is connected with the input end of the synchronization module, and the output end of the current compensation module is connected with the input end of the synchronization module. The output end of the current comparison module is connected with the input end of the synchronization module, and the output end of the synchronization module is connected with the driving signal generation module. According to the invention, a plurality of time scales are adopted, the implementation condition of synchronous zero-voltage switch modulation is accurately calculated, the calculation speed is high, the memory occupation amount is small, and the zero-voltage switch synchronous modulation of the cascade system is realized.

A multiphase buck converter that includes smart two-phase power stages for reducing switching losses. Each of the smart power stages includes a first high side switch, a second high side switch, a first low side switch, a second low side switch, a switching capacitor, a first inductor, and a second inductor. The exemplary multiphase buck converter includes two such smart power stages and a multiphase controller for generating PWM signals for driving the two smart power stages synchronously.

The invention discloses a transient enhancement circuit applied to a COT mode buck converter in the technical field of integrated circuits, and the transient enhancement circuit comprises an output voltage sampling circuit and a fully differential transconductance amplifier GM. The input end of the output voltage sampling circuit is connected with the output end of the COT mode buck converter; the output voltage sampling circuit is used for sampling an output voltage signal of the COT mode buck converter and sending the sampled voltage signal to the input end of the fully differential transconductance amplifier GM. According to the invention, the transient enhancement circuit applied to the COT mode buck converter is introduced, so that the effective improvement on the up-down rush and the recovery time in the load switching process of the buck converter is realized, and the system is continuous and the system response is optimized by dynamically changing the conduction time.

The invention relates to a transient enhanced multi-phase Buck converter and a control method thereof, and the method comprises the steps: continuously monitoring and outputting a voltage reduction signal through a capacitance current sampling module, calculating a to-be-judged voltage signal, and outputting a high-level judgment signal when the to-be-judged voltage signal is greater than a reference voltage VTH1; after receiving the signal, the phase control module forcibly outputs logic control signals which are all high levels to the self-adaptive conduction time generation module; the multi-phase current conversion module synchronously conducts all single-phase Buck conversion circuits in the multi-phase current conversion module accordingly, so that the single-phase Buck conversion circuits simultaneously work to output the maximum current, and severe fluctuation of the output voltage is rapidly inhibited; and when the full-phase forced working mode is maintained until the voltage signal to be judged corresponding to the new voltage reduction signal is smaller than the reference voltage VTH2 again, the transient is relieved, and the system is automatically switched back to the conventional minimum current phase interleaving control mode. According to the scheme, the problem of response lag of a traditional multi-phase Buck under extreme load transient can be effectively solved.

The invention belongs to the field of integrated circuit design, and comprises a switch module and a co-frequency control module, the switch module comprises a power switch tube, and the co-frequency control module comprises a turn-on time control circuit, a turn-off time control circuit, a logic circuit and a driving circuit; the turn-on time control circuit generates a first control signal for controlling the turn-on time of the power switch tube; the turn-off time control circuit generates a second control signal for controlling the turn-off time of the power switch tube; the logic circuit performs logic operation on the first control signal and the second control signal to generate a third control signal; the driving circuit generates a driving signal based on the third control signal; the switch module controls the power switch tube to be switched on and switched off periodically according to the corresponding switching frequency based on the driving signal so as to convert the input voltage of the input power supply into the output voltage. According to the BUCK converter, the same-frequency control circuit is introduced, so that the fluctuation of the switching frequency of the BUCK converter controlled by the self-adaptive conduction time when the load changes can be effectively reduced.

The invention provides a DC Buck converter voltage and current sensor fault-tolerant control system, which comprises the following steps: establishing a time-varying state space model of a DC Buck converter, and dynamically reconstructing a parameter matrix by the time-varying state space model according to the real-time change of a duty ratio; the time-varying augmentation fault estimator is used for monitoring faults of a voltage sensor and a current sensor in real time, the fault estimator is implemented through a model reference adaptive filter, a Buck converter is adopted to construct a reference model in a healthy state, and efficient real-time diagnosis and correction can be achieved through the faults of the voltage sensor and the current sensor of the Buck converter. And various types of sensor faults such as a jump fault, an offset fault, a stuck fault, a high-frequency fault and a gap fault can be effectively estimated. For measurement distortion of the voltage sensor and the current sensor, the fault estimator can provide comprehensive evaluation information of fault types and fault severity.

The invention discloses a multi-level pulse compensation type active EMI (Electro-Magnetic Interference) filter suitable for a multi-noise source switching power supply and a control method of the multi-level pulse compensation type active EMI filter. The invention provides a multi-level pulse compensation scheme based on switch behavior modeling, aiming at the problem of common-mode noise of adjacent rising edges and falling edges generated by a high-frequency switch in a multi-noise-source switching power supply. The time sequence delay and the edge slope of the compensation signal are calculated by analyzing the dv / dt characteristics in the switching-on and switching-off processes of the switching device, and accurate matching and offset with a noise source in phase and amplitude are achieved. Compensation control logic is realized by sharing a main control chip with a power circuit, and an additional controller and a high-precision sampling system are not needed; the self-adaptive tracking of the compensation amplitude is realized through the voltage following circuit; a multi-level compensation signal is output through the totem-pole circuit and injected into a common-mode path, and effective suppression of electromagnetic interference is achieved. The converter has the advantages of small size, low cost, simplicity and convenience in installation, high stability and the like, and is suitable for various multi-noise-source power electronic systems including a dual-active bridge converter, a phase-shifted full-bridge converter and an interleaving Buck converter.

The invention discloses a BUCK converter over-current protection circuit based on ripple V2COT control. The BUCK converter over-current protection circuit comprises a current sampling circuit, a comparator and a frequency reduction circuit which are connected in sequence. The current sampling circuit generates a sampling voltage, the current sampling circuit further comprises a reference voltage generating circuit which outputs a reference voltage and inputs the voltage and the reference voltage into a comparator for comparison to obtain an overcurrent signal, and the overcurrent signal is input into the frequency reduction circuit to generate a frequency reduction signal. Through combinational logic of a gate circuit, a frequency reduction signal is output. The ripple injection circuit is connected to the grid electrode of the MOS tube, and the output waveform of the ripple injection circuit is adjusted by controlling the on and off of the MOS tube, so that the working frequency of the system is reduced. The problem that the circuit recovery time is long after the overcurrent is eliminated is solved, the faster the circuit recovery is, the smaller the risk of element damage is, the higher the system reliability is correspondingly, and the development requirements of high reliability and safety of contemporary electronic products are met.

Embodiments of the present disclosure provide an active equalizer circuit, a battery management system, and a power supply system. The active equalizer circuit comprises a plurality of switching transistors, a driving transformer, a multi-port converter, a buck converter, and a microcontroller. Each of the switching transistors is coupled to a battery cell in the series battery pack on a one-to-one basis. The multi-port converter comprises an equalizing transformer and a bridge converter. The microcontroller is configured to output a first control signal to the buck converter, to facilitate the buck converter to transform an output voltage of the series battery pack and output the transformed output voltage to the bridge converter, and output a second control signal to the bridge converter, to control an operation state of the bridge converter.

The invention relates to the technical field of power electronics, and discloses a multi-isolation output expansion circuit of an auto-excitation type Buck converter and the auto-excitation type Buck converter, and the multi-isolation output expansion circuit comprises a first switch tube which is connected in parallel with two ends of a fly-wheel diode; the multi-winding transformer comprises a primary winding, a first secondary winding and a plurality of second secondary windings, the primary winding is configured as an output filter inductor of the self-excited Buck converter, the first secondary winding is configured as a driving winding of the first switching tube, and the second secondary windings are configured as an isolation output end of the self-excited Buck converter; and the first capacitor is configured to form a reverse follow current channel with the first switching tube under the condition that the energy storage of the multi-winding transformer is insufficient, so as to provide energy for the multi-winding transformer. According to the invention, a plurality of isolated output ports are easy to expand, and the voltage of the isolated output ports is stabilized, so that the load regulation rate of the converter is improved.

The invention provides a BUCK converter and a variable gain error amplification circuit, and is applied to the technical field of power supply chips and BUCK converters. An error amplifier is improved into a variable gain error amplifier in the BUCK converter, and error amplification gain switching is carried out on whether load switching (such as overshoot / undershoot conditions) exists at an output end or not through a feedback detection circuit, for example, when it is detected that the output is in a load switching state; the error amplifying circuit rapidly enters an overshoot / undershoot mode, the transient current of the response branch is increased, the response speed is increased, the low transient voltage is achieved, the fast response characteristic is achieved, and the advantage of high efficiency can be continuously kept in the normal working process.

A ripple voltage detector circuit comprises a pulse generator, a direct current-to-direct current (DC-DC) converter coupled to the pulse generator, and a first control loop coupled to the pulse generator and the DC-DC converter. The first control loop is configured to measure an output voltage of the DC-DC converter, determine an output ripple voltage of the output voltage, determine a ripple coefficient based on the output ripple voltage, determine a reference peak inductor current based on the ripple coefficient, and determine a peak value of an inductor current during a switching cycle, and transition a switching state of the DC-DC converter based on the reference peak inductor current and the peak value of the inductor current.

The invention relates to the technical field of power electronics, and discloses a single-stage bidirectional DC / AC converter and a control method thereof. The single-stage bidirectional DC / AC converter comprises a pre-stage circuit and a post-stage circuit which are multiplexed by a switching tube. Wherein the pre-stage circuit is an L-LLC resonant converter or a CLLC resonant converter, and the post-stage circuit is an interleaved Buck converter. And an output inverter bridge at the secondary side of the transformer is replaced by a bridgeless structure. According to the single-stage bidirectional DC / AC converter, the number of switching tubes is reduced through a multiplexing technology, the topological structure can be simplified, the stability is improved by reducing the damage probability, and the cost is reduced; furthermore, by utilizing a soft switching technology of a pre-stage circuit, ZVS of four primary-side switching tubes and half secondary-side switching tubes can be realized, the switching loss is greatly reduced, and the working efficiency is improved; an output inverter bridge is omitted, the number of switching tubes can be further reduced, and the power density and the working efficiency are improved.

The invention discloses a multiphase BUCK converter and a high-dynamic self-adaptive phase cutting method. The multiphase BUCK converter comprises a 16-phase power level, a current sampling module, an MOS driving module, a digital control module, a CMCOT simulation main control loop and a dynamic detection circuit. The MOS driving module controls a switching tube in the 16-phase power level, the current sampling module collects an inductive current signal, the input end of the CMCOT simulation main control loop is connected with the output end of the current sampling module, and a PWM control signal is output to the digital control module; the input end of the dynamic detection circuit is connected with an output signal of a voltage loop gain in the CMCOT analog main control loop, and a mark signal is generated and output to the digital control module; the digital control module generates a phase cutting signal. A phase cutting strategy is correspondingly provided, the number of PWM started by a phase cutting signal is adaptively changed, the transient voltage undershoot is reduced, meanwhile, voltage overregulation is avoided, and the transient performance is remarkably improved.

The invention belongs to the technical field of power electronics, and relates to a high-side-ratio non-isolated hybrid switched capacitor converter which is used for direct 48V-1V power conversion of a data center and comprises switching tubes S1 to S38, flying capacitors C1 to C15, inductors L1 to L8, an input end Vin, an output end Vout and a grounding end. The switch tubes S1-S6 and the flying capacitors C1-C3 form a 4: 1 switched capacitor buck converter part; the switch tubes S7-S38, the flying capacitors C4-C15 and the inductors L1-L8 form a voltage-adjustable multi-channel mixed buck converter; mixing of the pre-buck converter and the voltage-adjustable buck converter is achieved through the exchange bus, the advantages of the pre-buck converter and the voltage-adjustable buck converter can be well fused, the defects of the pre-buck converter and the voltage-adjustable buck converter can be overcome, a bus decoupling capacitor is not needed, and the number of switches can be reduced. According to the multi-channel mixed buck converter, a capacitance channel is added, the conduction loss of an inductance channel is reduced, ripples are reduced, the duty ratio is increased, and the voltage stress of a switching tube is reduced; the hybrid switched capacitor converter has the advantages of being large in transformation ratio, high in power density and small in device stress.

The invention discloses an adaptive mode switching circuit of a BUCK converter for COT control. The adaptive mode switching circuit comprises a conduction time generation circuit, an OR gate, phase inverters INV1, INV2 and INV3, an NAND gate, an AND gate, RS triggers RS1 and RS2, transistors Mon, MN1, MN2 and MN3, a falling edge delay circuit, a rising edge delay circuit and a zero cross detection circuit. According to the invention, a conduction signal and a zero-cross detection signal are fed back to the conduction time generation circuit, the states of two paths of control signals in a DCM mode and a CCM mode are adaptively adjusted, logic operation is carried out on the control signals through an OR gate, and the conduction time of an upper tube is adaptively adjusted. When the DCM mode is switched to the CCM mode, the CCM control signal serves as a conduction time control signal, and the conduction time of an upper tube is increased; and when the CCM mode is switched to the DCM mode, the DCM control signal is used as a conduction time control signal, and the conduction time of the upper tube is reduced.

An automatic current sharing control method for an interleaved BUCK converter belongs to the technical field of power electronics, and comprises the following steps: step S1, obtaining an output voltage and a given output voltage of a load end of the interleaved BUCK converter; obtaining the current of each phase of inductor; s2, obtaining an average value of the inductive current of each phase, and averaging the average value of the inductive current of each phase as a reference value of a current loop; s3, calculating a duty ratio signal through a current loop; s4, calculating a duty ratio signal through a voltage loop; and S5, superposing the duty ratio signal of the current loop operation of each phase with the duty ratio signal of the voltage loop operation. According to the invention, the inductive current of each phase follows the average inductive current of three phases in real time, high-precision current-sharing control is realized, and the control reliability is improved, so that the output current is controlled at an average level.

The invention discloses a buck converter and a driving circuit and a bootstrap power supply circuit thereof, the buck converter comprises a main switch tube connected between an input end and a switch node and a driving unit connected with a control end of the main switch tube, and the bootstrap power supply circuit comprises a bootstrap capacitor. The bootstrap unit is connected between a bootstrap node and the switch node, and the bootstrap node is used for supplying power to the driving unit; the charge pump circuit is connected with the bootstrap node, the charge pump circuit comprises a first pumping unit and a second pumping unit, the first pumping unit comprises a first charge pump capacitor, and the second pumping unit comprises a second charge pump capacitor; and the first pumping unit and the second pumping unit are alternately in a pumping state for charging the bootstrap capacitor and a charging state for charging the charge pump capacitor of the first pumping unit and the second pumping unit, so that the voltage of the bootstrap node is maintained at a preset value, and the light load efficiency of the buck converter is improved.

The invention discloses a gallium nitride hybrid switched capacitor voltage converter with a high step-down ratio, which belongs to the technical field of switching power supplies and comprises an input filtering module, a switched capacitor module group, a half-bridge module group and an output filtering module which are connected in sequence, the switched capacitor module group comprises a plurality of switched capacitor modules which are connected in parallel, the half-bridge module group comprises a plurality of half-bridge modules which are connected in parallel, and the switched capacitor modules and the half-bridge modules are in one-to-one correspondence and work in corresponding preset switching periods; the output filtering module comprises a plurality of output filtering inductors, and the output filtering inductors are correspondingly connected with the half-bridge modules. Through innovation of the topological structure, the buck ratio higher than that of a traditional Buck converter under the same duty ratio is achieved, input current and output voltage ripples are further improved through a multi-phase interleaving parallel control mode, wide bandgap devices are reasonably selected for the innovatively-designed topological structure, and therefore the output current and output voltage ripples are improved. And the circuit is more suitable for kilowatt-level switching power supply equipment.

The invention discloses a multiphase dynamic scheduling adaptive conduction time control Buck converter based on phase interpolation. The converter comprises a self-adaptive turn-on time control module, a phase interpolation control module and a dynamic phase scheduling module, the number of working phases can be dynamically adjusted according to load current changes, a multi-phase clock signal is generated through a phase interpolation method, and high-precision multi-phase current-sharing control is achieved. According to the invention, the output ripple of the system is reduced, the bandwidth and dynamic response performance of the system are improved, the energy efficiency under a light-load working condition is remarkably improved, and the method is suitable for a high-performance chip power supply system.

The invention discloses a buck-boost converter and a mode switching method and circuit thereof, and the mode switching method comprises the steps: selecting a driving signal from a third driving signal and a first driving signal of a first switching tube according to a boost-buck mode signal and a third driving signal of a third switching tube, filtering the selected driving signal or the voltage division signal of the selected driving signal, comparing the filtered signal with a first reference voltage, and obtaining a closed-loop voltage reduction mode signal according to a comparison result; comparing the output voltage of the buck-boost converter with a second reference voltage, and obtaining an open-loop buck mode signal according to a comparison result; and when both the closed-loop voltage reduction mode signal and the open-loop voltage reduction mode signal are effective, outputting an effective voltage reduction mode signal so as to switch the working mode of the buck-boost converter into the voltage reduction mode in the next switching period, thereby improving the accuracy of judging the working mode of the buck-boost converter and improving the reliability of the buck-boost converter. And smooth switching between the working modes of the buck-boost converter is realized.

The invention discloses a DC-DC converter parameter identification method based on digital twinning, and the method comprises the following steps: firstly building a Buck converter simulation model, collecting needed data from the simulation model, building a mathematical model according to a Buck converter circuit structure, KCL and KVL, and carrying out the calculation of the Buck converter simulation model. And solving a differential equation of the mathematical model by using a Runge-Kutta method to obtain calculation data, substituting the collected simulation data and calculation data into a target function, performing iterative optimization on the target function value by using a Kirchhoff's law optimization algorithm, and outputting an optimal solution of a to-be-identified parameter, namely an identification value of the circuit parameter. According to the method, the parameter identification error of the DC-DC converter can be reduced, and the accuracy is improved.

The invention discloses an MPC predictive control and power purchase cost optimization method for a photovoltaic hydrogen production system, and belongs to the technical field of photovoltaic hydrogen production. After a photovoltaic system in the system passes through a boost converter and a full-bridge circuit, an output direct current passes through a first excitation inductor and is connected with a first winding; after the power grid passes through the rectifier and the full-bridge circuit, output direct current flows through the second excitation inductor and is connected with the second winding; after the fuel cell passes through the boost converter and the full-bridge circuit, the output direct current flows through the third excitation inductor and is connected with the third winding; after the electrolytic tank passes through a buck converter and a full-bridge circuit, the output direct current is connected with a fourth winding through a fourth excitation inductor; the hydrogen storage tank is connected with the electrolytic cell and the fuel cell; based on the system, an MPC predictive control algorithm is added into the electrolytic cell converter, and a Z-score function is carried out when the system purchases electricity from a power grid to calculate the optimal electricity purchase time. According to the invention, the optimization of the hydrogen production efficiency, the hydrogen production amount and the system cost of the system is realized.

The invention discloses a method and a device for improving dynamic characteristics of a two-stage resonant converter based on a virtual resistor, and in the converter, a front-stage Buck converter and a rear-stage LLC resonant converter are connected through a common DC bus; the dynamic characteristic improvement method comprises the following steps: inputting bus capacitor voltage on a common direct current bus into an active damping inner ring controller, and simulating a virtual resistor accessed to a converter through output; the difference value between the output voltage of the resonant converter and the reference voltage is input into a voltage outer loop proportional-integral controller; and subtracting the output signals of the active damping controller and the voltage outer loop controller to obtain an improved duty ratio of the preceding-stage Buck converter for controlling a switching device. By adopting the above technical scheme, through a control mode of combining voltage outer loop control and active damping inner loop control, the double-resonance peak in the voltage loop is suppressed, and the bandwidth of the voltage loop is effectively expanded.

The invention provides a slow power-on circuit for a servo system. The slow power-on circuit comprises a control power supply module, a BUCK converter module, a PWM generator module, a state display module and a totem pole driving module. A BUCK converter is connected in series between main power loops, the magnitude of surge current is determined by the peak value of inductive current, and the increase of voltage on a capacitor is realized by controlling the duty ratio of an MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor). The high-frequency inductor is adopted to suppress surge current, so that space is saved, and the energy utilization rate is increased; the voltage at the two ends of the load capacitor is gradually increased by adopting a method for adjusting the duty ratio to be gradually increased, and universality is achieved; the peak value of the input current is effectively reduced in a duty ratio chopping mode, and the time required by the slow power-on process is shortened; whether a fault occurs in the slow power-on process or not is judged according to the light emitting condition of the light-emitting diode.