HK40096559A - Device and method for providing an electrical current to an electrical load - Google Patents

Description

Apparatus and methods for supplying current to electrical loads

This application is a divisional application of patent application filed on August 10, 2018, with application number 201880044423.X, entitled "Apparatus and Method for Providing Current to an Electrical Load".

Technical Field

This invention relates to an apparatus and method for supplying current to an electrical load. In particular, this invention relates to an apparatus and method for driving an electrical load using a switch-mode power supply (SMPS) configuration.

Background Technology

The following discussion of the background of the invention is intended only to facilitate understanding of the invention. It should be understood that this discussion is not an admission or endorsement that any material cited up to the priority date of this invention has been disclosed, is known, or is part of common general knowledge to those skilled in the art in any jurisdiction.

Existing switch-mode power supply (SMPS) devices typically include many components such as capacitors, inductors, and regulators. These components take up space and introduce potential distortion into electrical components and circuits.

Devices or systems used to drive electrical loads, also known as drivers, typically include digital or analog voltage or current controllers configured, not limited to isolated or non-isolated configurations. Such controllers generally operate to receive electrical inputs, such as alternating current and voltage, to provide a regulated output. State-of-the-art controllers include some form of feedback mechanism/loop to ensure that at least one electrical parameter (e.g., current) remains within an ideal or permissible range while achieving an acceptable power factor level. However, to improve overall performance, conventional controllers often incorporate electrical/electronic components, such as resistors, capacitors, inductors, etc., to compensate for distortion, reduce harmonics, or improve the power factor. Such components increase the overall cost and also increase the form factor.

Furthermore, the feedback requirements of most existing controllers necessitate sensing various electrical parameters at predetermined intervals (one or more). Such sensing can increase the amount of time required to process the electrical inputs in order to produce a regulated output.

Some electrical loads (such as LED units or LED lamp units) are typically sensitive to fluctuations in current and temperature. Therefore, electrical controllers used for LEDs need to take into account temperature and current requirements. Noise generated by electronic devices and electrical components is an important consideration for sensitive electrical loads.

The present invention seeks to provide a system and method that mitigates the above-mentioned disadvantages or at least partially meets the above-mentioned needs.

Summary of the Invention

Throughout the document, unless the context otherwise requires, the word “contains” or variations thereof, such as “includes” or “includes”, should be understood to imply the inclusion of the said integer or group of integers, but not to exclude any other integers or groups of integers.

Furthermore, throughout this specification, unless the context otherwise requires, the word “comprising” or variations thereof, such as “including” or “containing”, should be understood to imply inclusion of the said integer or group of integers, but not to exclude any other integer or group of integers.

This invention attempts to reduce the number of electronic components and improve the power factor by utilizing a storage device for storing one or more ideal voltage waveforms. The input voltage _Vi from the power supply is used as a synchronization reference, and the ideal waveform is used to calculate a reference voltage for current control.

According to one aspect of the invention, an apparatus for supplying current to an electrical load is provided, the apparatus comprising: a memory storage device for storing a plurality of ideal voltage waveforms; an electronic controller configured to data communicate with the memory storage device, the electronic controller being operable to select one of the plurality of ideal voltage waveforms to calculate a reference voltage and a switching period based on predetermined criteria; and an electronic switch configured to receive the switching period as input to switch the electronic switch between an on state and an off state, wherein the current is calculated as a function of the reference voltage and the switching period or frequency of the electronic switch.

In some embodiments, at least one of the plurality of ideal voltage waveforms is an ideal alternating current (AC) waveform.

In other embodiments, at least one of the plurality of ideal voltage waveforms is an ideal direct current (DC) waveform.

In some embodiments, the device further includes sensing circuitry arranged to communicate data with an electronic controller, the sensing circuitry being operable to sense a source input voltage, wherein the source input voltage provides electrical power to the device.

In some embodiments, the sensing circuit includes a potentiometer, a voltage divider, or a feedback resistor.

In some embodiments, the sensed source input voltage is divided by a predetermined number. The predetermined number may be an even number, such as four (4).

In some embodiments, in a transient state prior to selecting one of a plurality of ideal voltage waveforms, the electronic controller is operable to use a source input voltage divided by a predetermined number as a reference voltage for switching the electronic switch.

In some embodiments, when switching the electronic switch, the time _TX from when the reference voltage is sensed to when the reference voltage is sensed to the next time the reference voltage is sensed to the predetermined voltage is measured.

In some embodiments, one of a plurality of ideal voltage waveforms is selected to calculate the reference voltage when the following conditions are met: i. after a plurality of time periods _TX ; and ii. when the input voltage drops to zero; and wherein the period of the selected ideal voltage waveform corresponds to or is approximately the time period _{TX .}

In some embodiments, the ideal AC waveform includes one or more of the following: a sine waveform, a squared sine waveform, or a polynomial function waveform, such as, but not limited to, a quadratic function.

In some embodiments, if the device is configured in a boost converter configuration, a sine wave is selected.

In some embodiments, if the device is configured in a flyback converter configuration, a sine square waveform or a polynomial function waveform is selected.

In some embodiments, if the input voltage does not drop to zero after multiple time periods _TX , an ideal DC waveform is selected.

In some embodiments, the device further includes an analog-to-digital converter to convert the source input voltage into a digital waveform.

In some embodiments, the device is implemented on the primary side of a flyback switch-mode power converter.

In some embodiments, the device further includes a dimming circuit arranged to provide a dimming signal to an electrical load.

In some embodiments, the electronic controller includes an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA).

In some embodiments, the electronic switch is a MOSFET.

In some embodiments, the current is calculated based on the following mathematical expression:

Where _IOUT is the current supplied to the electrical load; T corresponds to the switching cycle; _TON is the on-time of the electronic switch; _TOFF is the off-time of the electronic switch, which corresponds to the time required for the inductor with inductance L to discharge; and _Vi corresponds to the source input voltage.

In some embodiments, the input voltage _Vi is related to the reference voltage _Vh according to the following mathematical expression:

Where _Vh is the reference voltage applied to the comparator for comparison with the source input voltage _VI , and _Rfb is the resistance value of the feedback element, which is configured to compare _Vh with _Vfb , where _Vfb is the voltage across the feedback element having the resistance value _Rfb .

In some embodiments, the current is calculated based on the following mathematical expression:

In some embodiments, the current is calculated based on the following mathematical expression:

Where _IOUT is the current supplied to the electrical load; T corresponds to the switching cycle T = _TON + _TOFF + _TCALC ; _TOFF is the opening time of the electronic switch, which corresponds to the time required for the inductor with inductance L to discharge; _Vi corresponds to the input voltage; _Vh is the reference voltage that triggers the opening of the electronic switch; _T1 corresponds to the time when the sensed input voltage reaches or is at the predetermined voltage _V1 .

In some embodiments, the memory storage device is ROM, RAM, database, or LUT.

According to another aspect of the present invention, a method for supplying current to an electrical load is provided, the method comprising the steps of: storing a plurality of ideal voltage waveforms in a memory storage device; selecting one of the plurality of ideal voltage waveforms and calculating a reference voltage and a switching period based on a predetermined rule, said selection and calculation steps being performed by an electronic controller; and receiving the switching period as input at an electronic switch to switch the electronic switch between an on state and an off state, wherein the current is calculated based on a function of the reference voltage and the switching period or frequency of the electronic switch.

In some embodiments, at least one of the plurality of ideal voltage waveforms is an ideal alternating current (AC) waveform.

In some embodiments, at least one of the plurality of ideal voltage waveforms is an ideal direct current (DC) voltage waveform.

In some embodiments, the method further includes the step of sensing a source input voltage via a sensing circuit, wherein the source input voltage provides electrical power to the device.

In some embodiments, the sensing circuit includes a potentiometer, a voltage divider, or a feedback resistor.

In some embodiments, the method further includes the step of dividing the sensed source input voltage by a predetermined number. In some embodiments, the predetermined number is 4. In other embodiments, the predetermined number is any even number. In some embodiments, the predetermined number is any odd number.

In some embodiments, the method further includes the step of activating an electronic switch using the sensed input voltage as a reference voltage.

In some embodiments, the method further includes the step of measuring time _T1 , which corresponds to _the time from when the input voltage is sensed at a predetermined voltage to when the input voltage is next sensed at the predetermined voltage. The predetermined criteria may include conditions satisfying: i. after a plurality of time periods _T1 ; and ii. when the input voltage drops to zero; and wherein the period of the selected ideal voltage waveform corresponds to or is approximately the time period _{T1 .}

In some embodiments, the ideal AC waveform includes one or more of the following: a sine waveform, a squared sine waveform, a quadratic function waveform, and a polynomial function waveform.

In some embodiments, if the device is configured in a boost converter configuration, a sine wave is selected.

In some embodiments, if the device is configured in a flyback converter configuration, a sine square waveform is selected.

In some embodiments, a DC waveform is selected if the input voltage does not drop to zero after multiple time periods _T1 .

In some embodiments, the method further includes the step of converting the (source) input voltage to a digital value.

In some embodiments, the device is implemented on the primary side of a flyback switch-mode power converter.

In some embodiments, the method further includes the step of providing a dimming signal to an electrical load.

In some embodiments, the electronic controller includes an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA).

In some embodiments, the electronic switch is a metal-oxide-semiconductor field-effect transistor (MOSFET).

In some embodiments, the current is calculated based on the following mathematical expression.

Where _IOUT is the current supplied to the electrical load; T corresponds to the switching cycle; _TON is the on-time of the electronic switch; _TOFF is the off-time of the electronic switch, which corresponds to the time required for the inductor with inductance L to discharge; and _Vi corresponds to the input voltage.

In some embodiments, the input voltage _Vi is related to the reference voltage _Vh according to the following mathematical expression:

Wherein, _Rfb is the resistance value of the feedback element, which is positioned to compare _Vh with the voltage _Vfb across the feedback element having resistance _Rfb .

In some embodiments, the current is calculated based on the following mathematical expression:

In some embodiments, the current is calculated based on the following mathematical expression.

Where _IOUT is the current supplied to the electrical load; T corresponds to the switching cycle; _TOFF is the opening time of the electronic switch, which corresponds to the time required for the inductor with inductance L to discharge; _Vi corresponds to the input voltage; _Vh is the reference voltage that triggers the opening of the electronic switch; and _T1 corresponds to the time when the sensed input voltage reaches the predetermined voltage _V1 .

Attached Figure Description

The invention will now be described by way of example only with reference to the accompanying drawings, in which:

Figure 1a illustrates a device for supplying current to an electrical load according to some embodiments of the present invention;

Figure 1b illustrates another embodiment of a device for supplying current to an electrical load;

Figure 2 is an example of a lookup table (LUT) for storing ideal voltage waveforms according to some embodiments;

Figure 3 is a flowchart illustrating a method for selecting entries from the LUT in Figure 2 as part of the process of supplying current to an electrical load;

Figure 4a shows a portion of the voltage waveform (y-axis) versus time (x-axis), illustrating the relationship between the reference voltage, a portion of the input voltage, and the transient time before selecting the ideal voltage waveform from the LUT;

Figure 4b illustrates the use of a trigger to synchronize the ideal waveform with the input voltage; and

Figures 5a and 5b are tables showing the results of the efficiency of the apparatus and method in discontinuous and continuous modes in a buck-boost switch-mode power supply (SMPS) configuration.

Other arrangements of the invention are possible, therefore the drawings should not be construed as replacing the generality of the foregoing description of the invention.

Detailed Implementation

Specific embodiments of the invention will now be described with reference to the accompanying drawings. The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the scope of the invention. Furthermore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

Throughout this specification, the term "waveform" is not limited to an actual waveform, but includes data and/or groups of data associated with electrical signals (such as voltage or current supply signals). In particular, a waveform may include one or more groups of data associated with that waveform.

The device is suitable for, but is not limited to, providing at least a relatively "ripple-free" current, defined as less than 5% of the specified rated current. The specified rated current is typically (but not limited to) approximately 350mA to 700mA.

Throughout this specification, unless otherwise stated, references to “current” and “(one or more) connections” refer to current and connections.

Throughout the manual, the input voltage _Vi refers to the source input voltage obtained from the power supply line or source; the reference voltage _Vh refers to the voltage calculated based on the ideal voltage waveform.

According to one aspect of the invention, there is an apparatus for supplying current to an electrical load, the apparatus comprising a memory storage device for storing a plurality of ideal voltage waveforms; an electronic controller arranged to data communicate with the memory storage device, the electronic controller being operable to select one of the plurality of ideal voltage waveforms to calculate a reference voltage based on a predetermined criterion; and an electronic switch configured to receive the reference voltage as input to switch the electronic switch between an on state and an off state, wherein the current is calculated based on the reference voltage and a function of the switching period or frequency of the electronic switch.

Referring to the embodiment shown in FIG1a, device 100 is a switch-mode power supply (SMPS) or driver for supplying current to one or more electrical loads 180. Device 100 draws electrical energy from power source 50, such as an alternating current (AC) power source or a direct current (DC) power source. Examples of power sources include building trunk lines providing AC power or battery packs providing DC power.

Device 100 includes a rectifier module 102 arranged electrically connected to an electronic controller 104, which is arranged or configured to receive one or more inputs associated with an ideal voltage waveform from a storage device 106 to drive an electronic switch 108. The switching of the electronic switch 108 regulates the current supply to an electrical load 180. The electronic switch 108 is arranged electrically connected to an inductor 110, which may be an isolation transformer in a flyback configuration or an inductor in a DC-to-DC non-isolated configuration. The discharge time of the inductor 110 or the isolation transformer is used as one of the inputs to control the switching state of the electronic switch 108. In some embodiments, the voltage across the inductor 110 may be sensed by a feedback module 112, and subsequently, the electronic controller 104 calculates the off-time _TOFF based on the discharge time of the inductor 110.

In some embodiments, a dimmer circuit 114 is included. When the electrical load includes an LED lamp unit, the dimmer circuit 114 may be arranged on the secondary side of the device 100 to adjust the brightness of the LED lamp unit. The dimmer circuit 114 may be arranged to control the current supplied to the electrical load 180 and may receive inputs from motion sensors, potentiometers, etc., as known to those skilled in the art. It should be understood that the logic associated with the dimmer circuit 114 may be implemented as the output voltage of an electronic controller 104 digitized by an analog-to-digital converter (ADC).

In some embodiments, rectifier module 102 includes rectifier bridge elements, current or voltage sensing circuitry, and supply-side capacitors or resistors. In some embodiments, feedback module 112 includes one or more comparators for comparing a reference voltage _Vh with a voltage _Vfb across a feedback element (e.g., a feedback resistor with resistance _Rfb ).

In some embodiments, the electronic controller 104 may be an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other types of programmable or non-programmable integrated circuits (ICs), wherein if the electronic controller 104 is non-programmable, the logic may be hardwired to one or more circuit boards. The electronic controller 104 may be arranged to receive multiple inputs, including but not limited to:

i. Switching cycle T and the corresponding T _ON (on) and T _OFF (off) measurements;

ii. Input voltage or source input voltage digitized from the mains voltage or power _supply ;

iii. It may be the inductance (L) of the predetermined inductor element 110.

Based on the input, the current to be supplied to the load is calculated based on the following mathematical expression in equation (1):

Where _IOUT is the current to be supplied to the electrical load; T corresponds to the switching period (or switching cycle); _TON is the on-time of the electronic switch; _TOFF is the off-time of the electronic switch corresponding to the time taken for the inductor 110 with inductance L to discharge; and _Vi corresponds to the input voltage.

In some embodiments, the switching period T is the sum of the following parameters: T _ON + T _OFF + T _CALC , where T _CALC is the time used to calculate equation (1) after the discharge time of the inductor element.

In some embodiments, the input voltage _Vi is related to the reference voltage _Vh according to the following mathematical expression in equation (2):

Wherein, _Vh is the reference voltage applied to the comparator within the feedback module 112, used for comparison with the voltage across the feedback element having a resistor _Rfb .

In some embodiments, the output current is calculated based on the following mathematical expression using the off-time _TOFF , the reference voltage _Vh , and the switching period T, which is expressed mathematically as equation (3) below:

In some embodiments, the output current is calculated based on the following mathematical expression:

By using equation (4) instead of equation (3), any delays associated with using a comparator can be avoided, because in equation (4), the uncertainty contribution from the comparator is offset by introducing parameters _Vi , _T1 and _V1 .

Where _T1 corresponds to the time it takes for the input voltage _Vi based on the sensing circuit 102 to reach the predetermined voltage _V1 from 0.

Storage device 106 may include random access memory (RAM), read-only memory (ROM), and/or other storage devices capable of storing data associated with multiple ideal voltage waveforms. In some embodiments, storage device 106 may be integrated as part of electronic controller 104. In some embodiments, electronic controller 104 and/or storage device 106 form part of an integrated circuit (IC) chip. In other embodiments, storage device 106 may be an IC chip separate from electronic controller 104. In some embodiments, storage device 106 may be implemented as a lookup table that defines a specific ideal voltage waveform to be selected as input based on a set of operating states. These inputs may be associated with initial operating parameters of device 100 before selecting an ideal voltage waveform to calculate a reference voltage _Vh .

It should be understood that SMPS can be configured as an isolated flyback configuration or a non-isolated configuration (DC power supply).

The ideal waveform stored in storage device 106 can be a digitized ideal waveform, each waveform being defined by at least three parameters (including period or frequency; amplitude; and type).

Figure 1b illustrates another embodiment of a device 200 for providing current _IOUT to drive an electrical load. The device 200 includes an electronic controller 202 arranged to receive multiple inputs to calculate a reference voltage _Vh for turning an electronic switch 204 on and off, as well as electronic signals, to generate the necessary _IOUT . In some embodiments, the electronic switch 204 is a MOSFET.

Multiple inputs include, but are not limited to:

i. Switching cycle T (generated by the internal clock) and the corresponding T _ON and T _OFF measurements;

ii. Input voltage _Vi digitized from the mains voltage or power supply;

iii. The inductance (L) of the inductor element 206 can be predetermined.

Based on the input, the current I _OUT to be supplied to the load is calculated based on equation (1).

In the embodiment shown in FIG1b, the electronic controller 202 may include an analog-to-digital converter ADC 212, a storage unit 214, a digital interface 216, a waveform selector 218, a digital measurement unit 220, a reference voltage generator 222, an internal algorithm unit 224, and a synchronization unit 226.

The ADC 212 is configured to receive electrical energy with voltage _Vi from a mains AC or DC power supply. _Vi is digitized by the ADC along with any currently preset signal DIM. If a high voltage (e.g., above 280V) is detected, this value is divided using a resistor divider. Digitization is used to: 1) synchronize the ideal voltage waveform with the input voltage _Vi ; and 2) calculate the _VOUT value using a mathematical expression.

V _OUT ＝ V _i * T _ON / T _OFF (5)

Storage unit 214 includes storage of ideal voltage waveforms, which may be sinusoidal, triangular, polynomial, or other. These can be embedded during manufacturing or loaded from any external device (not shown).

Storage unit 214 may include configuration registers for allowing users/programmers to preset different operating modes. For example, the DIM value can be adjusted digitally, the waveform shape can be selected, and operating parameters such as internal error conditions and measured values can be checked and/or obtained.

The digital interface 216 provides one or more user interfaces that allow loading ideal voltage waveforms (one or more) from external devices and configuring and checking modes and measurements.

The waveform selector 218 helps select a suitable ideal waveform based on the input voltage _Vi . This selection can be performed using the digital interface 216 or automatically by the synchronization unit 226.

Digital measurement unit 220 is arranged to measure time parameters T, T_{_ON} , and T _{_OFF}. It is electrically connected to a first comparator 203 to receive the outputs of V _{_h} and V _{_fb} as inputs, where V_{_fb} is the voltage across a feedback resistor 207, one end of which is connected to the source of an electronic switch 204, and the other end of the feedback resistor 207 is grounded. The feedback resistor 207 has a resistance value R_{_fb} .

The digital measurement unit 220 is also connected to a second comparator 205. The second comparator 205 is connected to check the discharge time of the inductor 206. One input terminal of the second comparator 205 is arranged to tap the source input voltage _Vi , and the other input terminal is arranged to the voltage at the drain of the tap switch 204. This is used to measure T _OFF .

The reference voltage generator 222 includes a digital-to-analog converter operable to convert an ideal voltage waveform into an analog waveform.

The internal algorithm unit 224 receives parameters from other units and generates calculations based on equations (1) to (5).

Synchronization unit 226 is operable to synchronize an ideal voltage waveform stored in storage unit 214 with an input AC waveform _Vi . It uses a threshold level (e.g., _Vi /4) to trigger the waveform, as shown in Figure 4b. A digital counter counts between the two trigger points. Half of the counter's count will be half of the waveform. The top of the ideal waveform will be synchronized with the top of the input _Vi signal.

Referring to Figure 2, one embodiment of storage devices 106, 214 is in the form of a lookup table (LUT) containing various entries, such as 60Hz; 240V; AC ideal sine wave. Therefore, at least one of the multiple ideal voltage waveforms can be an ideal alternating current (AC) waveform or an ideal direct current (DC) waveform. Storage device 106 can be filled with ideal waveforms based on universally available AC voltages (e.g., but not limited to, 100-120VAC; 220-240VAC, etc.). Once filled, the relevant ideal voltage waveform is selected based on feedback obtained during the first few cycles of operation of device 100 (hereinafter referred to as transients). The term "ideal waveform" can also refer to data associated with the waveform, including digital data.

The method 300 for selecting and synchronizing the applicable ideal waveform from the LUT during operation is described in detail below. It should be understood that the device 100 operates transiently before selecting the ideal waveform from the LUT or storage device 106.

The process begins once the power line (e.g., AC power) is connected (step s302) and current flows to devices 100 and 200. Electricity can pass through rectifier module 102, and the input voltage _Vi can be sensed by a sensing circuit (which may be in the form of a sensing resistor circuit). The sensing circuit may include a potentiometer, a voltage divider, a feedback resistor, or any combination of the aforementioned elements having a resistance _Rfb .

Based on the input voltage range of the ADC, the sensed input voltage _Vi is divided by a predetermined number. In some embodiments, the predetermined number is 4 (step s304). It should be understood that the predetermined number can be any integer, and can preferably be an even number.

Once determined, _Vi /4 will be used as a trigger to synchronize the ideal voltage waveform with _Vi .

The electronic switch is activated (step s306), and preferably an internal oscillator or clock that can be integrated with the electronic controller 104 is used to measure the time taken for the input voltage _Vi to rise from 0 to _V1 (see Figure 4) and for the voltage to fall from _Vi to _V1 . _V1 can be calculated or derived based on the input voltage _Vi divided by a predetermined number (e.g., 8) (step s308).

After obtaining the time _T1 between zero crossing (V _{_i} = 0) and V _₁ (rising) and the time _T2 between V _₁ (falling) and zero crossing (V_{_i} = 0), a predetermined number of cycles (e.g., 4 cycles for T _₁ and T_₂ ) is counted (step s310). At the zero crossing after four (4) cycles, the ideal waveform from the LUT is activated, and the device now uses the selected ideal waveform as V _{_h} to switch to steady state (step s312). The steady-state control algorithm for providing the regulating current based on equations (1) to (4) is activated to control the electronic switch (step s314).

If the voltage _Vi does not drop to zero after multiple cycles, a DC waveform will be selected.

The selected ideal voltage waveform can be digitally multiplied by a constant to adjust the output current _IOUT . It is then converted into an analog signal by the reference voltage generator 222.

The selected ideal AC waveform can include one or more of the following: sine waveform, sine square waveform, and polynomial function waveform. The polynomial function waveform can be a quadratic function waveform.

In some embodiments, if device 100 is configured as a boost converter, a sine wave is selected. If device 100 is configured as a flyback converter, a squared sine wave is selected.

In some embodiments, the electronic controller may include an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA).

In some embodiments, where the electronic switch is a MOSFET, the gate of the MOSFET may be connected to the output of the electronic controller 104 to provide the necessary on-time T_{_ON} to switch the electronic switch 108. The drain of the electronic switch 108 may be connected to the inductor 110, and the source of the electronic switch 108 may be connected to ground via a feedback resistor.

Figures 5a and 5b show a device 100 used in a buck-boost, isolated configuration, operating in discontinuous conduction mode (DCM) as shown in Figure 5a and continuous conduction mode (CCM) as shown in Figure 5b.

Figure 5a shows the operating results of device 100, which has an isolation transformer with an inductance of 390 μH and a sensing feedback resistor _Rfb with a resistance of 10 ohms. Specifically, the output current _IOUT for 28 LED units forming a high-power LED lamp unit as an electrical load is 350 mA and 400 mA, respectively, and the output current _IOUT for 12 LED units forming a high-power LED lamp unit as an electrical load is 430 mA. The input voltage _Vi varies between 90 VAC and 265 VAC. The power factor of device 100 is observed to vary between 0.942 and 0.996 during operation.

Figure 5b shows the operating results of device 100, which has a 10-ohm sensing feedback resistor _Rfb . The output current _IOUT is 350mA for 28 LEDs as an electrical load and 370mA for 12 LEDs as an electrical load. The input voltage _Vi varies between 90VAC and 265VAC. The power factor of device 100 is observed to vary between 0.980 and 0.996 during operation.

It is understood that device 100 or a portion thereof may be implemented as one or more integrated circuit chips (IC chips). In some embodiments, the entire device 100 may be an IC chip.

Those skilled in the art will recognize that variations and combinations of the above features, rather than substitutions or replacements, can be combined to form other embodiments falling within the intended scope of the present invention.

Claims (10)

1. A device for supplying current from a power source to an electrical load, comprising: A memory storage device used to store multiple ideal voltage waveforms; An electronic controller configured to communicate data with the memory storage device, operable to select one of a plurality of ideal voltage waveforms based on the source input voltage of the power supply, to calculate a reference voltage and switching cycle based on predetermined rules; and An electronic switch, configured to receive the switching cycle to switch between an on state and an off state, wherein the current is calculated as a function of a reference voltage and the switching cycle of the electronic switch, and wherein the reference voltage is calculated based on one of a plurality of ideal voltage waveforms, and wherein the current is calculated based on the following mathematical expression. Where _IOUT is the current supplied to the electrical load; T corresponds to the switching cycle; _TON is the on-time of the electronic switch; _TOFF is the off-time of the electronic switch, which corresponds to the time required for the inductor with inductance L to discharge; and Vi corresponds to the source input voltage. 2. The apparatus according to claim 1, wherein the source input voltage _Vi is related to the reference voltage _Vh according to the following mathematical expression: Wherein, _Rfb is the resistance value of the feedback element, which is positioned to compare _Vh with _Vfb , where _Vfb is the voltage across the feedback element having a resistance value _Rfb . 3. The device according to claim 2, characterized in that the current is calculated based on the following mathematical expression: 4. The device according to claim 1, characterized in that the current is calculated based on the following mathematical expression: Where _IOUT is the current supplied to the electrical load; T corresponds to the switching cycle; _TOFF is the opening time of the electronic switch, which corresponds to the time required for the inductor with inductance L to discharge; _Vi corresponds to the source input voltage; _Vh is the reference voltage that triggers the opening of the electronic switch; and _T1 corresponds to the time when the input voltage is at a predetermined voltage _V1 . 5. The apparatus according to claim 1, wherein the memory storage device is ROM, RAM, database, or LUT. 6. The apparatus according to claim 1, wherein the apparatus comprises an integrated circuit chip. 7. A method for supplying current from a power source to an electrical load, comprising: Multiple ideal voltage waveforms are stored in the memory storage device; Based on the source input voltage of the power supply, one of the plurality of ideal voltage waveforms is selected to calculate the reference voltage and switching cycle according to a predetermined rule, and the selection step is performed by an electronic controller; The switching cycle is received as input at the electronic switch to switch the electronic switch between an on state and an off state, wherein the current is calculated as a function of a reference voltage and the switching cycle or frequency of the electronic switch, and wherein the reference voltage is calculated based on one of the plurality of ideal voltage waveforms, and wherein the current is calculated based on the following mathematical expression. Where _IOUT is the current supplied to the electrical load; T corresponds to the switching cycle; _TON is the on-time of the electronic switch; _TOFF is the off-time of the electronic switch, which corresponds to the time required for the inductor with inductance L to discharge; and _Vi corresponds to the input voltage. 8. The method according to claim 7, characterized in that the input voltage _Vi is related to the reference voltage _Vh according to the following mathematical expression: Wherein, _Rfb is the resistance value of the feedback element, which is positioned to compare _Vh with _Vfb , where _Vfb is the voltage across the feedback element with resistance value _Rfb . 9. The method according to claim 8, characterized in that the current is calculated based on the following mathematical expression: 10. The method according to claim 7, characterized in that the current is calculated based on the following mathematical expression. Where _IOUT is the current supplied to the electrical load; T corresponds to the switching cycle; _TOFF is the opening time of the electronic switch, which corresponds to the time required for the inductor with inductance L to discharge; _Vi corresponds to the source input voltage; _Vh is the reference voltage that triggers the opening of the electronic switch; and _T1 corresponds to the time when the sensed input voltage reaches the predetermined voltage _V1 .