Showing papers on "Rectifier published in 2009"

An efficient piezoelectric energy-harvesting interface circuit using a bias-flip rectifier and shared inductor

Abstract: Energy harvesting is an emerging technology with applications to handheld, portable and implantable electronics. Harvesting ambient vibration energy through piezoelectric (PE) means is a popular energy harvesting technique that can potentially supply 10 to 100's of µW of available power [1]. One of the limitations of existing PE harvesters is in their interface circuitry. Commonly used full-bridge rectifiers and voltage doublers [2] severely limit the electrical power extractable from a PE harvesting element. Further, the power consumed in the control circuits of these harvesters reduces the amount of usable electrical power. In this paper, a bias-flip rectifier that can improve upon the power extraction capability of existing full-bridge rectifiers by up to 4.2× is presented. An efficient control circuit with embedded DC-DC converters that can share their filter inductor with the bias-flip rectifier thereby reducing the volume and component count of the overall solution is demonstrated.

Control and Resonance Damping of Voltage-Source and Current-Source Converters With $LC$ Filters

Abstract: In this paper, the closed-loop control of both voltage-source converter (VSC) and current-source converter (CSC) systems with LC filters is investigated, with a focus being put on the damping of LC resonance. First, both single-loop and multiloop control schemes for a voltage-source inverter (VSI) with output LC filter are analyzed, where the design and tuning procedure can also be applied to a current-source inverter (CSI) with output CL filter. It is shown that both VSI and CSI systems are subject to LC resonance, even with multiloop control, while the CSI system is also subject to LC resonant frequency variations. On the other hand, the LC resonant frequencies in both current-source rectifier (CSR) and voltage-source rectifier (VSR) systems with input LC filter circuits are relatively fixed due to the small variation range of source impedance. To further dampen the LC resonance in these converter systems, active damping techniques such as virtual harmonic damper and control-signal-shaping methods are investigated, and their implementation into the converter systems is discussed in detail. Experimental results from both a VSC system and a CSC system are obtained.

A Bridgeless PFC Boost Rectifier With Optimized Magnetic Utilization

Abstract: The implementation of a bridgeless power factor correction (PFC) boost rectifier with low common-mode noise is presented in this paper. The proposed implementation employs a unique multiple-winding, multicore inductor to increase the utilization of the magnetic material. The operation and performance of the circuit were verified on a 750-W, universal-line experimental prototype operating at 110 kHz.

An oxide thermal rectifier

Abstract: We have experimentally demonstrated thermal rectification as bulk effect. According to a theoretical design of a thermal rectifier, we have prepared an oxide thermal rectifier made of two cobalt oxides with different thermal conductivities, and have made an experimental system to detect the thermal rectification. The rectifying coefficient of the device is found to be 1.43, which is in good agreement with the numerical calculation.

Passive receivers for wireless power transmission

Abstract: Exemplary embodiments are directed to wireless power transfer. A wireless power transmission receiver includes a receive antenna including a parallel resonator configured to resonate in response to a magnetic near-field and couple wireless power therefrom. The receiver further includes a passive rectifier circuit coupled to the parallel resonator. The passive rectifier circuit is configured to transform a load impedance to the parallel resonator.

An oxide thermal rectifier

Abstract: We have experimentally demonstrated thermal rectification as bulk effect. According to a theoretical design of a thermal rectifier, we have prepared an oxide thermal rectifier made of two cobalt oxides with different thermal conductivities, and have made an experimental system to detect the thermal rectification. The rectifying coefficient of the device is found to be 1.43, which is in good agreement with the numerical calculation.

An Efficiency-Enhanced CMOS Rectifier With Unbalanced-Biased Comparators for Transcutaneous-Powered High-Current Implants

Abstract: This paper presents an efficiency-enhanced integrated full-wave CMOS rectifier for the transcutaneous power transmission in high-current biomedical implants. The comparator-controlled switches are developed to minimize the voltage drop along the conducting path while achieving the unidirectional current flow. The proposed unbalanced-biasing scheme also minimizes the reverse leakage current of the rectifier under different input amplitudes, thereby optimizing the rectifier power efficiency. Moreover, the proposed rectifier is able to self start and operates at low input amplitudes. Implemented in a standard 0.35 mum CMOS process with maximum threshold voltages of |Vthp| = 0.82 V and Vthn = 0.69 V, the rectifier can source a maximum output current of 20 mA and operate properly with inputs of different amplitudes and frequencies. With a 1.5 MHz input of 1.2 V amplitude, the proposed rectifier can achieve the peak voltage conversion ratio of 95% and the power efficiency of at least 82%.

Bridgeless SEPIC Rectifier With Unity Power Factor and Reduced Conduction Losses

Abstract: In this paper, a new bridgeless single-phase AC-DC converter with an automatic power factor correction (PFC) is proposed. The proposed rectifier is based on the single-ended primary inductance converter (SEPIC) topology and it utilizes a bidirectional switch and two fast diodes. The absence of an input diode bridge and the presence of only one diode in the flowing-current path during each switching cycle result in less conduction loss and improved thermal management compared to existing PFC rectifiers. Other advantages include simple control circuitry, reduced switch voltage stress, and low electromagnetic-interference noise. Performance comparison between the proposed and the conventional SEPIC PFC rectifier is performed. Simulation and experimental results are presented to demonstrate the feasibility of the proposed technique.

High-Efficiency Fuel Cell Power Conditioning System With Input Current Ripple Reduction

Abstract: A high-efficiency fuel cell power conditioning system with input current ripple reduction is proposed. The proposed system consists of a high-efficiency high-step-up current-fed resonant push-pull converter and a full-bridge inverter. The converter conserves inherent advantages of a conventional current-fed push-pull converter such as low input-current stress and high voltage conversion ratio. Also, a voltage-doubler rectifier is employed in order to remove the reverse-recovery problem of the output rectifying diodes and provide much higher voltage conversion ratio. The current ripple reduction control without an external component is suggested. Therefore, the proposed system operates in a wide input-voltage range with a high efficiency. By using a current-ripple reduction control, the input current ripple is furthermore reduced. A 1.5-kW prototype is implemented with input-voltage range from 30 to 70 V. Experimental results show that minimum efficiency at full load is about 92.5% and that ripple current is less than 2% of the rated input current.

Charging apparatus, portable electronic device using the apparatus, and charging method thereof

Abstract: A charging apparatus includes an antenna, a receiver, and a battery. The battery is charged by a harvester, which converts wireless energy sent by antenna to direct current and charges the battery. The harvester includes a sensor coil, a rectifier and voltage regulating filter. The wireless energy is converted by the sensor coil to alternating current (AC). The rectifier is electrically connected to the sensor coil for converting AC to direct current (DC). The voltage regulating filter is electrically connected to the rectifier to regulate DC. The battery can be charged by the wireless charge apparatus.

Fuzzy-Logic-Based Switching State Selection for Direct Power Control of Three-Phase PWM Rectifier

Abstract: This paper proposes a novel and simple direct power control (DPC) scheme of a three-phase pulsewidth-modulated rectifier without the use of a predefined switching table. The converter switching state selection is based on fuzzy logic rules, using the instantaneous active and reactive power tracking errors as fuzzy logic variables. The basic idea of fuzzy rules synthesis is based on the knowledge of the instantaneous variation of active and reactive power. According to the input fuzzy variables and in a specific moment, the best switching state of the converter is chosen to restrict the instantaneous active and reactive power tracking errors simultaneously, for maintaining the DC-bus voltage close to the reference value and guarantying the unity-power-factor operation. The main advantages of the proposed DPC scheme, compared to the classical one, are that it is not necessary to use hysteresis comparators, and smooth control of active and reactive power is obtained during all sectors. Finally, the developed DPC was tested both in simulations and experimentally, and illustrative results are presented here. Results have proven excellent performance, and verify the validity of the proposed DPC scheme which is much better than the classical DPC.

Effect of Valley Switching and Switching-Frequency Limitation on Line-Current Distortions of DCM/CCM Boundary Boost PFC Converters

Abstract: A systematic analysis of line-current distortions of the discontinuous-conduction-mode and the continuous-conduction-mode boundary boost power factor correction converter due to valley switching (VS) and switching-frequency limitation, where VS is either maintained or lost after the onset of switching-frequency limitation, is provided. Closed-form expressions for the line current are derived. It is shown that if the switching frequency is limited and VS is not maintained, the line current is more distorted with voltage-mode control than with current-mode control. The effects of line-current distortions are demonstrated with both simulation and experimental results.

Development of a Compact Switched-Reluctance Motor Drive for EV Propulsion With Voltage-Boosting and PFC Charging Capabilities

Abstract: This paper presents a compact battery-powered switched-reluctance motor (SRM) drive for an electric vehicle with voltage-boosting and on-board power-factor-corrected-charging capabilities. Although the boost-type front-end DC/DC converter is externally equipped, the on-board charger is formed by the embedded components of SRM windings and converter. In the driving mode, the DC/DC boost converter is controlled to establish boostable well-regulated DC-link voltage for the SRM drive from the battery. During demagnetization of each stroke, the winding stored energy is automatically recovered back to the battery. Moreover, the regenerative braking is achieved by properly setting the SRM in the regenerating mode. The controls of two power stages are properly designed and digitally realized using a common digital signal processor. Good winding current and speed dynamic responses of the SRM drive are obtained. In addition, the static operation characteristics are also improved. In the charging mode, the power devices that were embedded in the SRM converter and the three motor-phase windings are used to form a buck-boost switch-mode rectifier to charge the battery from utility with good power quality. All constituted circuit components of the charger are placed on board, and only the insertion of power cords is needed.

Single-Chip Boost Converter Using Monolithically Integrated AlGaN/GaN Lateral Field-Effect Rectifier and Normally Off HEMT

Abstract: We demonstrate a single-chip switch-mode boost converter that features a monolithically integrated lateral field-effect rectifier (L-FER) and a normally off transistor switch. The circuit was fabricated on a standard AlGaN/GaN HEMT epitaxial wafer grown with GaN-on-Si technology. The fabricated rectifier with a drift length of 15 mum exhibits a breakdown voltage of 470 V, a turn-on voltage of 0.58 V, and a specific on-resistance of 2.04 mOmegaldrcm2. The L-FER exhibits no reverse recovery current associated with the turn-off transient because of its unipolar nature. A prototype of GaN-based boost converter that includes monolithically integrated rectifiers and transistors is demonstrated using conventional GaN-on-Si wafers for the first time to prove the feasibility of the GaN-based power IC technology.

Exploring the pareto front of multi-objective single-phase PFC rectifier design optimization - 99.2% efficiency vs. 7kW/din 3 power density

Abstract: Up to now, in the development of power electronics systems, the reduction of the initial costs or the increase of the power density have been of primary concern. However, with increasing energy costs also the power conversion efficiency is gaining higher and higher importance. Accordingly, while maintaining high power density, an efficiency as high as possible must be obtained. In this paper the maximum attainable efficiency and the dependency of the efficiency limit on technological parameters is determined for single-phase PFC boost rectifiers. In a first step basic PFC boost rectifier topologies are briefly compared with regard to high efficiency and a dual-boost PFC rectifier with integral common-mode filtering is selected as basis for the investigations. Next, simple approximations of the technological limits of the system performance are calculated in the efficiencypower density plane. With this, the Feasible Performance Space and the reduction in power density which has to be accepted for increasing the efficiency are clarified, and the trade-off limit curve (Pareto Front) of a multi-objective, i.e. efficiency and power density design optimization is determined. Furthermore, a comprehensive numerical efficiency optimization is carried out which identifies an efficiency limit of 99.2% for a 3.2kW system. The theoretical considerations are verified by experimental results from a laboratory prototype of the ultra-high efficiency system achieving 99.1% efficiency at a power density of 1.1kW/din3, as well as those firom an ultra-compact dual-boost PFC rectifier (95.8%, 5.5kW/dn3) and a very low switching freluency (3kHz) conventional PFC boost rectifier (96.7%, 2kW/din3). Finally, the sensitivity of the efficiency optimum with regard to various technological parameters is analyzed and an outlook on the further course of the research is given.

Mechanical Energy Harvester With Ultralow Threshold Rectification Based on SSHI Nonlinear Technique

Abstract: Harvesting energy from ambient sources has become of great importance these last few years. This can be explained not only by advances in microlectronics and energy harvesting technologies, but also by a growing industrial demand in wireless autonomous devices. In this field, piezoelectric elements offer outstanding performances, thanks to their high power density that makes them suitable for integrated microgenerators. However, such a domain still offers challenges to the research community. Particularly, embedding piezoelectric inserts as MEMS components raises the issue of low voltage output. Classical energy harvesting interfaces that feature bridge rectifier suffer from threshold voltage introduced by such discrete components, therefore compromising their use in real-life applications. In this paper is presented a new energy harvesting circuit that operates with ultralow voltage output, by the use of a magnetic voltage rectifier that does not present significant voltage gap. Experimental measurements performed on a simple transducer confirm theoretical predictions, and show that the proposed architecture operates well even for low-level vibrations, outperforming all known energy interfaces. Particularly, it is theoretically and experimentally shown that such an interface provides a gain greater than 50 compared to classical energy harvesting structures.

An average model of solid state transformer for dynamic system simulation

Abstract: The Solid State Transformer (SST) is one of the key elements proposed in the National Science Foundation (NSF) Generation-III Engineering Research Center (ERC) “Future Renewable Electric Energy Delivery and Management” (FREEDM) Systems Center established in 2008. The SST is used to enable active management of distributed renewable energy resources, energy storage devices and loads. In this paper, a 20kVA solid state transformer based on 6.5kV IGBT is proposed for interface with 12kV distribution system voltage. The average model and control scheme of SST including AC/DC rectifier, Dual Active Bridge (DAB) converter and DC/AC inverter are developed to enable dynamic system level simulation. The developed average model is verified by comparing with the detailed switching model simulation. The dynamic system level SST simulation verifies the proposed controller and the corresponding average model illustrates the functionalities and advantages of the SST in FREEDM system.

Integrated HEMT and Lateral Field-Effect Rectifier Combinations, Methods, and Systems

Abstract: Integrated high efficiency lateral field effect rectifier and HEMT devices of GaN or analogous semiconductor material, methods for manufacturing thereof, and systems which include such integrated devices. The lateral field effect rectifier has an anode containing a shorted ohmic contact and a Schottky contact, and a cathode containing an ohmic contact, while the HEMT preferably has a gate containing a Schottky contact. Two fluorine ion containing regions are formed directly underneath both Schottky contacts in the rectifier and in the HEMT, pinching off the (electron gas) channels in both structures at the hetero-interface between the epitaxial layers.

Power conversion apparatus

Abstract: PROBLEM TO BE SOLVED: To provide a power conversion apparatus capable of supplying power to a standby unit or to a standby battery while a bidirectional converter is stepped up or stepped down, and capable of efficiently discharging electric charges of a smoothing capacitor. SOLUTION: The power conversion apparatus comprises a battery 2, a main contactor 4 for supplying power/interrupting supply of power of the battery 2, a smoothing capacitor C1, a transformer 8, a first switching element Q1, a first diode D1 connected in reverse parallel to the first switching element Q1, a second switching element Q2, a second diode D2 connected in reverse parallel to the second switching element Q2, a smoothing capacitor C2, a rectifier circuit 11, and a smoothing circuit 12 for smoothing an output of the rectifier circuit 11. It also comprises a first discharge control means which turns OFF the main contactor 4 and also turns the first switching element Q1 ON/OFF at a specified duty ratio so that the electric charge of the smoothing capacitor C1 is discharged and a wanted voltage is output from the smoothing circuit 12. COPYRIGHT: (C)2009,JPO&INPIT

Solid state semiconductor LED replacement for fluorescent lamps

Abstract: Various apparatuses and methods for replacing a fluorescent lamp with a non-fluorescent tube are disclosed herein. For example, some embodiments provide an apparatus for replacing a fluorescent lamp, including an electrical connector adapted to electrically connect to a fluorescent lamp fixture, a DC rectifier connected to the electrical connector, a voltage converter connected to the DC rectifier, and a non-fluorescent light source connected to the voltage converter. The DC rectifier, voltage converter and non-fluorescent light source are substantially contained within a housing that is physically configured to replace the fluorescent lamp in a fluorescent lamp fixture.

Outphasing Energy Recovery Amplifier With Resistance Compression for Improved Efficiency

Abstract: We describe a new outphasing energy recovery amplifier (OPERA) which replaces the isolation resistor in the conventional matched combiner with a resistance-compressed rectifier for improved efficiency. The rectifier recovers the power normally wasted in the isolation resistor back to the power supply, while a resistance compression network (RCN) reduces the impedance variation of the rectifier as the output power varies. Because the combiner requires a fixed resistance at the isolation port to ensure matching and isolation between the two outphased power amplifiers (PAs), the RCN serves to maintain high linearity as well as high efficiency in the switching-mode PAs. For demonstration, a prototype OPERA system is designed and implemented with discrete components at an operating frequency of 48 MHz, delivering 20.8 W peak power with 82.9% PAE. The measurement results show an efficiency improvement from 17.9% to 42.0% for a 50-kHz 16-QAM signal with a peak-to-average power ratio of 6.5 dB.

Analysis and Design of a Modular Three-Phase AC-to-DC Converter Using CUK Rectifier Module With Nearly Unity Power Factor and Fast Dynamic Response

Abstract: In this paper, the analysis and design of a modular three-phase AC-to-DC converter using single-phase isolated Cuk rectifier modules is discussed based on power balance control technique. This paper analyzes the operation of a modular converter as continuous-conduction-mode power factor correction (CCM-PFC). Design equations, as well as an average small-signal model of the proposed system to aid the control loop design are derived. It is used to obtain the inductor current compensator, thus the output impedance and audio susceptibility become zero, and therefore, the output voltage of the converter presented in this paper is independent of the variations of the dc load current and the utility voltage. The control strategy consists of a single output voltage loop and three-inductor current calculator. The main objective of the proposed system is to reduce the number of stages and improve dynamic response of DC bus voltage for distributed power system. The proposed scheme offers simple control strategy, flexibility in three-phase delta or star-connected, simpler design, fast transient response, good inductor current sharing, and power factor closed to unity. Both simulation and experimental results are presented. They are in agreement with the theoretical analysis and experimental work.

AC LED dimmer and dimming method thereby

Abstract: The disclosure relates to an AC LED dimmer and dimming method thereof. The AC LED dimmer includes a rectifier receiving AC voltage from an AC voltage source and full-wave rectifying the AC voltage; a direct current (DC)/DC converter receiving the full-wave rectified voltage from the rectifier, generating a full-wave rectified stepped-up voltage, and generating a pulse enable signal; a pulse width modulation controller receiving the full-wave rectified stepped-up voltage and generating a pulse width modulation signal to dim an AC LED in response to the pulse enable signal; a switch driving the AC LED under control of the pulse width modulation signal, and an electromagnetic interference (EMI) filter to be connected between the AC voltage source and the switch to eliminate electromagnetic interference from the AC voltage source. Accordingly, the dimmer can perform an efficient and linear dimming function and suppress harmonics.

Investigation of Subsynchronous Resonance With VSC-Based HVDC Transmission Systems

Abstract: The HVDC converter control can destabilize torsional modes of nearby turbogenerators. The first experience of HVDC-turbine generator torsional interaction was observed in 1977 during field tests at Square Butte. The development of power semiconductors, specially insulated-gate bipolar transistors and gate turnoff thyristors (GTOs) has led to the small power HVDC transmission based on voltage-source converters (VSCs). The self-commutated VSC-based HVDC installations have several advantages compared to conventional HVDC-based online-commutated current source converter. The main objective of this paper is to investigate and present the detailed analysis of subsynchronous resonance (SSR), arising from a VSC-based HVDC system connected close to generating units. The analysis considers different operating modes of the converters. Based on a case study, it is shown that the dc voltage control mode of VSC operation (rectifier/inverter) close to the generator units can contribute positive damping in the torsional-mode frequency range of interest. The investigations of SSR with VSC-based HVDC is carried out based on linear (damping torque and eigenvalue) analysis and nonlinear transient simulation. While the damping torque, eigenvalue analysis, and controller design are based on the D-Q model, the transient simulation considers the D-Q model and the three-phase detailed model of VSC using switching functions. The influence of the operating modes of the converters and effects of some important parameters, such as effective short circuit ratio and generator rating are investigated.

Optimum Design Consideration and Implementation of a Novel Synchronous Rectified Soft-Switched Phase-Shift Full-Bridge Converter for Low-Output-Voltage High-Output-Current Applications

Abstract: Optimum design consideration and implementation of a novel synchronous rectified soft-switched phase-shift full-bridge dc/dc converter with a primary-side energy storage inductor for server adapter application is presented in this paper. By employing a primary-side energy storage inductor, the main switches can achieve a soft-switching condition, and there is little reverse recovery loss in the body diodes of a secondary-side rectifier due to relatively slow downslope of the triangular current. Since the output capacitive filter reduces the voltage stress across the rectifiers, the synchronous rectifier with a lower breakdown voltage rate can be utilized to improve the conversion efficiency dramatically. Thus, this converter can obtain relatively high conversion efficiency for some medium-power applications with low output voltage and high output current, such as the server adapter. Several key optimum design considerations of this converter are also presented in detail in this paper. Finally, a 100-kHz, 300-W (12 V/25 A) laboratory-made prototype for a given server adapter application is built up based on the proposed optimum design procedure of this converter to verify all the theoretical analysis and evaluations.

Zero-Current-Transition Bridgeless PFC Without Extra Voltage and Current Stress

Abstract: In this paper, a new zero-current-switching high-power-factor (PF) rectifier with pulsewidth-modulation control is introduced. The auxiliary circuit provides soft switching for all semiconductor devices without any extra current and voltage stress on the main switches. The proposed converter is bridgeless, and all semiconductor devices are soft switched. In addition, there is no extra stress on the switches. Thus, the conduction and switching losses are reduced and maximum efficiency is achieved. The converter is designed and simulated, and a prototype is implemented to verify the system performance. The experimental results exhibit high PF and efficiency of the proposed converter.

Three-Mode Dual-Frequency Two-Edge Modulation Scheme for Four-Switch Buck–Boost Converter

Abstract: Four-switch buck-boost (FSBB) converter features low-voltage stress across the power switches and positive output voltage. They have two active power switches and two synchronous rectifiers, so two freedoms, i.e., the duty cycles of the two active switches, are available to regulate the output voltage. This paper proposes a two-edge modulation (TEM), in which the two active switches are trailing-edge and leading-edge modulated, respectively. Thus, the inductor current ripple can be reduced. Furthermore, a 3-mode TEM is derived to reduce the root-mean-square value of the inductor current to reduce the conduction loss. The line range is divided into three regions, and FSBB operates at boost, buck-boost, and buck modes in the lower, medium, and higher input voltage regions, respectively. At buck and boost modes, only two switches are high-frequency switched, so that the total switching loss is reduced. In the buck-boost mode, the inductor current ripple is very low compared with other two modes. Hence, the switching frequency is lowered to reduce the switching loss. The 3-mode TEM can achieve high efficiency over the line range, which is verified by a 48-V (36-75 V) input, 48-V @ 6.25-A output prototype. The measured efficiency is higher than 96.5% over the line range and the efficiency at the nominal input voltage is 97.8%.

High-efficiency module-integrated photovoltaic power conditioning system

Abstract: A module-integrated, photovoltaic (PV) power conditioning system with a high-efficiency, high step-up DC-DC converter is proposed. The step-up DC-DC converter employs an active-clamp circuit for soft switching of the power semiconductor switches. Also, a dual series-resonant rectifier is employed in order to remove the reverse-recovery problem of the output-rectifying diodes and to provide a much higher voltage conversion ratio. The PV current is estimated without using a DC current sensor, and the PV current ripple reduction technique is suggested to reduce the current ripple without an external component. A 1 kW prototype for the PV voltage range of 30-60 V is implemented, and all algorithms and controllers are implemented on a single-chip microcontroller. Experimental results show that the power efficiency is 92.5-94% and the ripple current is 3.5% of the rated input current.

Modeling and Estimating Current Harmonics of Variable Electronic Loads

Abstract: This paper develops a model for relating input current harmonic content to real power consumption for variable electronic loads, specifically for loads' actively controlled inverters energized by an uncontrolled rectification of the utility. This model serves as the basis for a method for estimating and disaggregating the power consumption of variable speed drives (VSDs) and rectifier loads from other constant power loads. This method can be used for nonintrusive power monitoring. The approach described in this paper uses the approximate switching function of the rectifier to derive the best estimating function for the fundamental current harmonic from a finite set of current harmonics uniquely associated with the operation of the drive. Experimental results show that the proposed VSD power and harmonic estimator can track VSD power consumption for monitoring given knowledge or an estimate of the input current harmonic content.

Dimmable LED lamp and dimmable LED lighting apparatus

Abstract: A dimmable light-emitting diode (LED) lamp and a dimmable LED lighting apparatus thereof are provided. The dimmable LED lamp includes a bridge rectifier, a toggle detector, a sustain voltage supply circuit, a counter, an LED light source, and an LED lighting driver. The bridge rectifier receives a source alternating current (AC) voltage through a wall switch and provides a rectified direct current (DC) voltage. The toggle detector monitors a toggle action of the wall switch. The sustain voltage supply circuit provides a sustain voltage. The counter receives the sustain voltage for operation. Moreover, the counter stores and provides an counting value that changes when the toggle detector detects the toggle action. The LED lighting driver converts the rectified DC voltage to a constant current to drive the LED light source. The LED lighting driver also provides multi-level dimming to the LED light source according to the counting value.