An electric illuminator integrated with a battery and connected to an AC source and a control method

Abstract

An electric lighting fixture receives an AC source and an auxiliary power source. A power converter converts the AC power to power the lighting element. A power factor associated with the AC source is used as a control input to select the amount of power to be supplied from the two sources. This enables control of the overall power factor to avoid, for example, financial losses associated with using an AC source having a low power factor.

Description

Technical Field

[0001] The present invention relates to electrical appliances powered by AC, and more particularly to the problem of maintaining a high power factor. Background Art

[0002] Many devices driven by an AC input, such as a mains input, are provided with a power converter for AC-to-DC conversion.

[0003] One function implemented in a power converter powered by mains (or other AC) power is power factor correction (PFC). The power factor of an AC electrical power system is defined as the ratio of the active power flowing to the load to the apparent power flowing to the load. Apparent power is the vector combination of the active power and the reactive power components.

[0004] A power factor less than one means that the voltage and current waveforms are out of phase or distorted, thus reducing the instantaneous product of the two waveforms. Active power is the ability of a circuit to perform work at a specific time. Apparent power is the product of the current and voltage of a circuit. Mathematically, the power factor includes information related to both the harmonic power factor, which depends on harmonics, and the displacement power factor, which depends on phase displacement.

[0005] Due to the energy stored in the load and returned to the source, or due to non-linear loads that distort the waveform of the current drawn from the source, the apparent power will be greater than the active power.

[0006] If the power source operates at a low power factor, then for the same amount of useful power transferred, the load will draw more current compared to a higher power factor.

[0007] Using power factor correction can increase the power factor. For linear loads, this may involve using a network of passive capacitors or inductors. Non-linear loads typically require active power factor correction to counteract the distortion and increase the power factor. (Passive) power factor correction makes the power factor of the AC power circuit closer to unity by supplying reactive power of the opposite sign and adding capacitors or inductors that act to cancel the inductive or capacitive effects of the load.

[0008] Active PFC uses power electronics to change the waveform of the current drawn by the load to improve the power factor. An active PFC circuit can be based on, for example, buck, boost, or buck-boost switching mode converter topologies. Active power factor correction can be single-stage or multi-stage.

[0009] For high-power lighting above 25 W, the power factor is typically required to be greater than 0.9. For professional lighting applications, even for input powers below 25 W, the power factor is typically required to be equal to or greater than 0.9.

[0010] Many utility companies charge commercial and industrial customers a penalty for having a low power factor. Demand charges are billed in kVA, which corresponds to apparent power. Thus, any drop in the power factor below 1 results in additional demand bill units compared to the useful power actually consumed.

[0011] For example, one charging scheme involves charging the customer the greater of its active power demand in kW or 90% of its apparent (kVA) demand. Through this mechanism, there is an additional demand charge for all customers with a power factor less than 0.9. For example, a customer with a power factor of 0.85 and a peak demand of 850 kW (active) and thus 1000 kVA (apparent) will pay a demand of 900 kVA, or 50 additional demand units compared to a customer with a power factor of 0.9 or higher and the same active demand of 850 kW.

[0012] For customers in areas with high demand charges, the additional bill demand units can result in significant costs.

[0013] Thus, there are many reasons to avoid low power factor operation in power converters, such as to avoid consuming additional billable apparent power rather than active watt power.

[0014] US20110248567A1 discloses a power factor correction system with a battery charging system that is also configured to deliver input current to the power grid to regulate the power factor.

[0015] US20130107598A1 discloses a method of adding locally generated active and reactive power to a distribution grid. Summary of the Invention

[0016] The concept of the present invention is to use an auxiliary source to take over the supply from the main AC source (e.g., the utility company's mains supply). More specifically, the auxiliary source and the main AC source are selected based on the power factor of the system in order to prevent a low power factor condition of the system from being presented to the utility company, or in order to ensure that a high power factor continues to be presented to the utility company. In this way, a higher overall power factor can be achieved. More specifically, the concept is implemented in a luminaire and according to the output illumination level of the lighting element, which is inherently related to the power factor.

[0017] The present invention is defined by the claims.

[0018] According to an example of one aspect of the present invention, there is provided an electric luminaire comprising:

[0019] a lighting element having different output illumination levels;

[0020] A first input terminal, adapted to be connected to an AC source;

[0021] A second input terminal, adapted to be connected to an auxiliary power source;

[0022] A power converter, connected to the first input terminal and adapted to convert AC power from the AC source to power a lighting element;

[0023] An interface, adapted to receive a control signal identifying a power factor associated with the AC source, wherein the control signal is associated with the lighting element and depends on different output lighting levels; and

[0024] A controller, adapted to:

[0025] Select, based on the control signal, an amount of power to be supplied from the first input terminal to the lighting element and an amount of power to be supplied from the second input terminal to the lighting element.

[0026] The lighting fixture takes into account the power factor associated with the AC source, which depends on the lighting element, such as the type and size being driven, its operating mode, etc., in order to determine whether to use the AC power source or switch to an auxiliary power source. The auxiliary source is, for example, a DC source. Using an AC source with a low power factor may result in an economic loss, and this loss can be avoided by switching to the auxiliary source to avoid using the AC power with a low power factor. Alternatively, if using the AC source can improve the overall power factor of the system, then it is also feasible to switch from the auxiliary source to AC power in cases where a high overall power factor is required.

[0027] By identifying the power factor, the actual cost loss (based on determining the total apparent kVA power) can be determined, enabling control measures to be taken to minimize the energy usage cost.

[0028] It is known to switch between sources, for example, to reduce energy costs by charging a battery during off-peak hours and discharging the battery during peak hours. In US2009 / 290387A1, it is also known to switch between sources to reduce power losses, such as switching to a battery when the lighting element is in a light load condition to prevent high power losses in an AC / DC converter. The present invention provides an alternative or additional control method by which the power factor (rather than power loss) is taken into account, such that the actual energy cost can be monitored and used to determine how to allocate the alternative sources (AC and auxiliary sources) to the lighting element.

[0029] The power converter includes, for example, power factor correction, and in this case, the hardware and software required to determine the power factor associated with the AC source and the lighting element already exist. For example, this involves measuring the active power (using the monitored current and voltage values) and measuring the apparent power (based on the RMS voltage and current values at the AC source).

[0030] The control signal for identifying the power factor can be the actual power factor value, but it can equally be the apparent power and active power values (thus enabling the power factor to be determined individually).

[0031] The controller is, for example, adapted to further select the amount of power to be supplied to the lighting element from the first input and the amount of power to be supplied to the lighting element from the second input according to the total main (apparent) power in kVA and the active energy tariff.

[0032] For example, when based on the total apparent power (rather than the power demand), the total energy cost includes losses related to the main power factor. Therefore, the total energy cost can be managed (i.e., minimized) by an appropriate time shift between the two sources.

[0033] For example, the energy tariff can be based on 90% of the apparent power demand or 100% of the active power demand, whichever is greater. Alternatively, it can simply be based on the apparent power consumption. In this case, when there is a low power factor, it may be economically worthwhile to increase the consumption of the lighting fixtures operating at a higher power factor to improve the total power factor. This will depend on the energy tariff at that time and on whether such a time shift is possible for the customer.

[0034] For example, when the lighting element operates at a low power factor, a battery is used to power the lighting element. For example, this can be caused by the settings of the lighting fixture. In addition, preferably, the power source is managed such that battery charging occurs during off-peak hours, while battery use occurs during peak hours. The controller will preferably also consider the charge state of the battery when determining the source to be used for the lighting element and thus includes a charge management system.

[0035] The auxiliary source includes, for example, a battery. The battery as an auxiliary source is, for example, part of the lighting fixture.

[0036] Therefore, the lighting fixture has an integrated battery for power factor management of the present invention, but it can also be used for demand management, such as implementing battery charging during off-peak hours of the AC source and providing a source during peak hours. The auxiliary source can also serve as an emergency backup power source.

[0037] The controller is for example adapted to select the power from only one of the first input and the second input according to the control signal, and wherein the controller is preferably adapted to isolate the power converter from the AC source when selecting the power from the second input.

[0038] In this way, a simple control scheme is possible, whereby one or the other power source is selected to deliver power to the lighting element. More complex power sharing mechanisms are of course possible. The preferred isolation of the power source ensures that when the auxiliary source is used, the power converter no longer draws power from the AC source.

[0039] The controller is for example adapted to select the second input in response to a control signal indicating that the power factor of the luminaire itself is below a first threshold, and / or to select the first input in response to a control signal indicating that the power factor of the luminaire itself is above a second threshold.

[0040] Thus, when the second input (auxiliary source) is used, the power factor is improved. For example, a power factor target of 0.9 can be had. Then, when the power factor is below 0.9, it may be desirable to avoid powering the luminaire from the AC source, or equivalently, when a power factor greater than 0.9 can be achieved, use the AC source.

[0041] The interface (receiving the control signal identifying the power factor) can include:

[0042] a detector for detecting the power factor of the power converter; or

[0043] a communication module for receiving a control signal from a remote device, the remote device being coupled to a group of electrical luminaires including the present electrical luminaire.

[0044] Thus, power factor determination can be performed locally at each luminaire (e.g., using the existing hardware of the power factor correction unit), or can be performed remotely for a group of luminaires. The penalty associated with operation at a low power factor is applied to the total source, so if there are multiple luminaires powered by the AC source, it is desirable to perform an overall assessment of the main power factor. In this case, there can be a global power factor assessment as well as local power factor detection, such that local luminaires that can contribute to global power factor improvement can be identified.

[0045] For example, if the lighting element is operating at a setting corresponding to the peak or intermediate value of its rated power, the converter for that lighting element can have a high power factor, so the luminaire can be connected to the AC; the low power mode of the luminaire typically results in a lower power factor, so in terms of the power factor, it is preferred to connect the luminaire to the auxiliary source.

[0046] Therefore, the illuminator is a dimmable illuminator. The dimming setting strongly affects the power factor. In particular, a low dimming setting (i.e., low brightness) is associated with a low power factor.

[0047] The above aspects focus on compensating the power factor of the illuminator itself. Alternatively, another aspect of the present invention is to compensate the power factor of other appliances in the system.

[0048] The controller is preferably adapted, for example, during off-peak hours to:

[0049] Determine whether the power factor of the power converter itself is higher than a third threshold, and if so, then:

[0050] Select a first input terminal in response to a control signal indicating that the power factor of the system of other appliances is lower than a fourth threshold; and

[0051] Select a second input terminal in response to a control signal indicating that the power factor of the system of other appliances is higher than a fourth threshold.

[0052] This uses the AC power converter to compensate for the low power factor (i.e., lower than the fourth threshold, where the fourth threshold is, for example, lower than the third threshold) of other appliances when operating at a high power factor (i.e., higher than the third threshold). This is preferably during off-peak hours, when the intentional additional use of the power converter (and thus the additional power demand) is economically preferable to allowing overall operation at a lower power factor. Thus, when the timing of such additional use is flexible, it enables the intentional additional use of the power converter to increase the overall power factor.

[0053] The power factor associated with the AC source includes, for example, a combination (e.g., product) of a harmonic power factor and a displacement power factor. The system can include, for example, some units (such as LED drivers) that mainly generate a harmonic power factor and some units (such as heating, ventilation, and air conditioning systems) that mainly generate a displacement power factor.

[0054] The power factor measured in the system takes into account the overall effects of both distortion and displacement. It is also possible that the system or appliance itself generates only one of the harmonic power factor and the displacement power factor, and the present invention can still be used for compensation.

[0055] There can be a system of multiple illuminators that has global power factor measurement or local power factor measurement or both.

[0056] The present invention also provides a system of appliances connected to a shared AC source, where at least one appliance is an illuminator as defined above, and where the system further includes one or more of the following:

[0057] Heating, ventilation, and air conditioning appliances; and

[0058] IT system appliances.

[0059] Therefore, the present invention can be applied to the installation of multiple appliances of different types. The aim is to achieve power factor optimization and thus optimize the energy cost of the overall installation.

[0060] The present invention also provides a method for controlling an electric lighting fixture having an output lighting element, comprising:

[0061] Providing the lighting fixture with access to an AC source and performing power conversion to convert the AC power from the AC source for supply to the lighting element;

[0062] Providing the lighting fixture with access to an auxiliary power source;

[0063] Receiving or generating a control signal related to the power factor associated with the AC source; and

[0064] Selecting, based on the control signal, the amount of power to be supplied from the AC source to the output lighting element and the amount of power to be supplied from the auxiliary power source to the output lighting element.

[0065] The method takes into account the power factor associated with the AC source and the lighting element of the lighting fixture in order to switch between the AC power source and the auxiliary power source.

[0066] The method may further include selecting, based on the total apparent power in kVA of the main and the energy tariff, the amount of power to be supplied from the first input to the lighting element and the amount of power to be supplied from the second input to the lighting element.

[0067] The output lighting element may have multiple output modes, wherein the power factor associated with the AC source depends on the output mode of the output lighting element. For example, wherein the output lighting element includes a lighting fixture and the output modes include different output lighting levels.

[0068] The step of selection is, for example, to select only the auxiliary power source in response to a control signal indicating that the power factor of the lighting fixture itself is lower than a first threshold, and / or to select only the AC source in response to a control signal indicating that the power factor of the lighting fixture itself is higher than a second threshold. This provides a simple binary control method. Alternatively, a more complex analog load sharing method may be used.

[0069] The present invention can be implemented at least in part in computer software.

[0070] These and other aspects of the present invention will become clear and be elucidated with reference to the embodiments described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Examples of the present invention will now be described in detail with reference to the accompanying drawings, in which:

[0072] Figure 1 A graph showing the relationship between the power factor and the operating voltage of an example of a lighting driver;

[0073] Figure 2 An example of an electrical appliance is shown;

[0074] Figure 3 An appliance system connected to a shared AC source is shown;

[0075] Figure 4 A method of controlling an electrical appliance is shown; and

[0076] Figure 5 An example of a computer 50 for implementing a controller used in an appliance as set forth in Figure 2 is shown. DETAILED DESCRIPTION

[0077] The present invention will be described with reference to the accompanying drawings.

[0078] It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the apparatus, systems, and methods, are intended for illustrative purposes only and are not intended to limit the scope of the invention. These and other features, aspects, and advantages of the apparatus, systems, and methods of the present invention will become better understood from the following description, the appended claims, and the accompanying drawings. It should be understood that these drawings are merely schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the drawings to denote the same or similar parts.

[0079] The present invention provides an electrical appliance that can access an AC source and an auxiliary power source. A power converter converts AC power to supply power to a load. Such a power converter is typically a PFC AC / DC converter. The appliance may also include a DC / DC converter between the PFC AC / DC converter and the load. The power factor associated with the AC source is used as a control input to select the amount of power to be supplied from each of the two sources. This enables control of the overall power factor, for example, to avoid economic losses associated with using an AC source having a low power factor.

[0080] The present invention is generally interested in AC-driven appliances. A particular application of interest is lighting circuits, and the present invention will be described in conjunction with this example.

[0081] Figure 1 A graph showing the power factor (y-axis) versus operating voltage (x-axis) of an example of a 75 W lighting driver based on a switched-mode power source is shown. This is for a general-purpose driver that is capable of operating at any AC input voltage in the range of RMS 90 V to 265 V.

[0082] For different load states, four curves are shown, presented as percentages. These load states represent the dimming levels of the LED lighting load.

[0083] At 100% load (i.e., operating at full brightness), the driver typically provides a power factor greater than 0.97 for all voltage inputs, while when the load level is 25% (or lower), the power factor drops to 0.85 at 230 V AC. As the dimming level becomes lower, the power factor becomes lower.

[0084] For example, if a 40 W luminaire (i.e., drawing 40 W of active power) provides a power factor of 0.98 under full load conditions, this means the luminaire draws an apparent power of 40 / 0.98 = 40.81 VA. This means that only 0.81 VA of additional VA power may be chargeable (depending on the pricing scheme). The reactive power component is:

[0085] √((40 / 0.98) 2 - 40 2 ) = 8.12 W.

[0086] If the same luminaire operates at 25% load (and thus 10 W of power) and only provides a power factor of 0.85, then the additional apparent power will be (10 / 0.85 - 10) = 1.76 VA. Even if charged based on only 90% of the apparent power, there is still 0.58 VA (11.76 × 0.9 - 10) of chargeable additional power. In this case, the reactive power component is:

[0087] √((10 / 0.85)^2 - 10^2)) = 6.19 W.

[0088] Thus, this example of a 100% dimmable (full brightness mode) luminaire consumes 40 W of active power and only 8.12 W of reactive power, with a power factor of 0.98. When the active power is only 10 W, the same luminaire consumes 6.19 W of reactive power due to the lower power factor of 0.85. Thus, when operating at a low power factor, the luminaire consumes a high proportion of reactive power, and this can lead to the utility provider charging based on the apparent power.

[0089] Accordingly, the present invention is based on transferring the luminaire power to an auxiliary source, such as an internal battery, when the power factor is low. For example, this can be when the input voltage is high (e.g., 230 - 265 V AC RMS) and when the requested dimming is low (such as less than 40%).

[0090] Alternatively, the output illumination level is a color / color temperature level, such as warm, medium, and cold. When the color temperature of the illuminator changes (which is also associated with a change in the power factor of the illuminator driver), the illuminator can switch between the battery and the AC mains power supply. For example, the illuminator / driver has a high power factor when emitting one color / color temperature and a low power factor when emitting another color / color temperature. This may be the result of having different drivers for different colors / color temperatures. When the color / color temperature is associated with a high power factor driver, the AC mains power supply can be used; and when the color / color temperature is associated with a low power factor driver, an auxiliary source such as a battery can be used. This is just another example, and there may be other embodiments covered by the claims of the present invention. In yet another example, the beam angle levels of narrow, medium, and wide illuminators are the output illumination levels, provided that those different beam angle levels are associated with different power factors of the illuminator. The term "output illumination level" is intended to cover any characteristic of the output light that can be measured as a level, as well as combinations of these characteristics.

[0091] Typically, many lighting products are rated for operation at a universal mains voltage, i.e., 90 - 265 V AC, RMS. Thus, when the input voltage is on the higher side but within the operable range (e.g., 260 - 265 V AC), the power factor drops compared to the circuit operation at 90 - 110 VAC RMS under the same load conditions.

[0092] The present invention is based on using the actual power factor at any given time to determine whether to use the main AC source or to switch fully or partially to an auxiliary source.

[0093] Figure 2 An example of an electrical appliance 10 is shown, which includes a first input terminal 12 adapted to be connected to an AC source 14 and a second input terminal 16 adapted to be connected to an auxiliary power source 18.

[0094] In the example shown, the auxiliary power source 18 is external to the appliance, but it can be internal (in which case the second input terminal 16 is within the entire appliance rather than an external input). The auxiliary power source is, for example, a DC battery. It can be used for the described power factor control, but of course it can also perform the conventional functions of providing an emergency backup power source and / or providing load shifting between peak and off-peak times. Other embodiments of the auxiliary power source include renewable power sources such as solar panels or wind / wave turbines.

[0095] The power converter 20 is connected to the first input terminal 12 and is adapted to convert AC power from an AC source to power a load. The power converter is, for example, a switched-mode power source (SMPS). It includes an AC-DC converter, such as a diode bridge rectifier, which then supplies a DC voltage to a switching stage. The switching stage includes an energy commutation element, typically an inductor, and a main control switch that controls the coupling of input energy to the energy commutation element and the coupling of the energy commutation element to the output terminal. The power converter also incorporates power factor correction.

[0096] An example of a suitable power factor correction (PFC) unit for a switched-mode power source is a PFC boost converter, which is inserted, for example, between the bridge rectifier and the mains storage capacitor. The boost converter attempts to maintain a constant DC bus voltage at its output while drawing a current that is in phase with and of the same frequency as the line voltage.

[0097] The PFC unit is independent of another main switched-mode circuit (not shown) of the power converter 20 that generates the desired output voltage or current from the DC bus. The main switched-mode circuit thus acts as a controllable DC / DC converter. There may be current feedback or voltage feedback to provide control of the main switched-mode circuit, thereby delivering the desired output current or voltage to the load.

[0098] The AC / DC PFC unit and the DC / DC switched-mode power source are both conventional and are not altered by the method of the present invention.

[0099] The appliance has a load 21, which in the example shown is an LED arrangement (schematically represented as a single LED). However, the present invention can be applied to other types of lighting loads (such as compact fluorescent lighting) or indeed to other types of loads in general.

[0100] The appliance 10 also includes an interface 22 that receives a control signal that identifies the power factor associated with the AC source 14 (and which also depends on the load being driven).

[0101] The power factor signal can be generated internally or can also be received from an external source. Three alternative sources of the control signal are as Figure 2As shown. The first and second sources are internal, and the third source is external. In the case where the AC / DC PFC power converter has a built-in PF measurement circuit, a first possible internal source is from the output terminal of the power converter 20. Alternatively, a second possible internal source is a separate internal power factor measurement unit 24 placed between the AC source 14 and the AC / DC PFC converter. A third possible source is an external power factor measurement unit 26. The external unit can provide power factor information about a group of appliances, and the appliance shown in the group of appliances forms an element. In this case, the interface 22 includes a communication module for receiving external communication signals in a wired or wireless manner. Different solutions can utilize one or more of the possible power factor information sources.

[0102] The controller 28 is adapted to select, according to the control signal, the amount of power to be supplied from the first input terminal 12 to the load 21 and the amount of power to be supplied from the second input terminal 16 to the load.

[0103] Therefore, the appliance takes into account the power factor associated with the AC source in order to determine whether to use the AC power source or switch to the auxiliary power source. By identifying the power factor, the cost loss can be determined because both the apparent power and the active power can be determined. Therefore, the control can aim to minimize the cost of energy use.

[0104] In a first method, the power converter 20 senses the input utility grid voltage and current, from which the power factor can be estimated. In particular, as described above, the existing monitoring circuit implementing power factor correction provides the information required to determine the power factor.

[0105] When using the internal power factor measurement unit 24, direct power factor sensing is used to provide a direct indication of the power factor.

[0106] In this way, the power factor can be estimated at each luminaire, and can be easily calculated using digital sampling measurements of the voltage and current drawn by the luminaire. The product of the voltage and current is the active power consumption:

[0107]

[0108] As shown in the above formula, the instantaneous voltage is multiplied by the instantaneous current and then integrated over time (such as a full cycle) to calculate the active power.

[0109] The RMS values of the voltage and current are also calculated by taking the square root of the squared voltage and current components over time (again such as a full cycle). The product of these RMS values is the apparent power.

[0110] This RMS measurement method can be applied to any type of waveform (sinusoidal or distorted) with any harmonic content up to the instrument bandwidth.

[0111] The power factor can be calculated based on the ratio between the active power and the apparent power as follows:

[0112]

[0113] That is

[0114]

[0115] The controller 28 can select the amount of power to be supplied to the load from the first input and the amount of power to be supplied to the load from the second input, further considering the energy tariff followed. For example, when based on the total apparent power (instead of the power demand), the total energy cost includes losses related to the main power factor as described above. Therefore, the total energy cost can be managed (i.e., minimized) by an appropriate time shift between the two sources.

[0116] As described above, for a lighting load, the power factor can be the result of the operating settings of the lighting load. The result is that at low dimming levels (i.e., low brightness), the auxiliary source is preferentially used. The battery will need to be charged, and preferably the system is managed such that battery charging occurs during off-peak hours while battery use occurs during peak hours. The controller 28 thus also implements a battery charging algorithm such that the switching action also takes into account the charge state of the battery. There may be conflicting demands for battery charging (when there is a low charge state) and battery use (when there is a low power factor), and the controller implements an algorithm that operates to manage these various demands and the desire to maintain the most efficient energy use (as minimum reactive power consumption and / or minimum cost (considering the pricing tariff)). For example, by operating the system at the rated power of the entire system, battery charging can be achieved during low dimming operation to improve the power factor.

[0117] The choice between the two sources can be binary, i.e., according to the control signal, the power is selected only from one of the first input and the second input. This is shown, for example, in Figure 2 by the switching elements 30a and 30b. They are connected in series between the respective one of the inputs 12, 16 and the load 21. Thus, they can couple or isolate each power source from the load. If they operate in a complementary manner, this binary control is implemented.

[0118] However, more complex power sharing mechanisms are of course possible. These can be based on a power transfer switch that can select the amount of power to be transferred from the input to the output. For example, a very low speed pulse width modulation (PWM) signal (e.g., with a time period between 1 and 200 minutes) can be used for low speed timing operations, or high speed PWM (time period between 1 ms and 1 s) can be used to provide more continuous power sharing between two sources to achieve a desired average power factor.

[0119] When the load is isolated from the power converter 20, when the auxiliary source is in use, the power converter no longer draws power from the AC source. The switch 30a can be set between the first input terminal 12 and the power converter to isolate the input rather than the output of the converter.

[0120] The switching decision can be based on, for example, a threshold of the measured power factor.

[0121] For example, the controller can select the second input terminal 16 in response to the measured power factor at the appliance itself being lower than a first threshold, e.g., 0.9, and / or select the first input terminal 12 in response to a control signal indicating that the measured power factor at the appliance itself is higher than a second threshold. This second threshold can be the same (0.9) or higher, e.g., 0.95. This method is deliberately using the auxiliary source to improve the power factor and / or using the main AC source when the power factor is high. The auxiliary source can be regarded as a backup source. This method involves, for example, the control of the appliance as an independent unit.

[0122] Instead, the appliance can be controlled as part of a group of appliances.

[0123] Then, when the power factor is high, the main AC source can be utilized to compensate for other appliances with a low power factor. This is particularly desirable, for example, when the electricity cost is low.

[0124] If the power factor of the power converter itself is higher than a third threshold (e.g., 0.95), it can be used to compensate for other appliances. In this case, when the power factor of the system of other appliances is lower than a fourth threshold (e.g., 0.85), the first input terminal 12 is selected.

[0125] This uses the AC power converter to compensate for the low power factor (i.e., lower than the fourth threshold, which is, for example, lower than the third threshold) of other appliances when operating at a high power factor (i.e., higher than the third threshold). This is equivalent to deliberately using the power converter additionally. This can be used, for example, for battery charging.

[0126] Alternatively, when the power factor of the system of other appliances is higher than the fourth threshold, the second input terminal 16 is selected. This means that the system power factor is already high and there is no need to use this appliance to pull it higher.

[0127] Figure 3 Shows an appliance system connected to a shared AC source 14. It includes a set of luminaires 32a to 32d, heating, ventilation, and air conditioning appliances 34, and IT system appliances 36 as described above.

[0128] The purpose of the control is to achieve energy cost optimization for the entire system.

[0129] The power factor associated with the total AC source is measured by the unit 26 external to each luminaire, and the internal unit 24 in each of the above-mentioned luminaires is omitted. It measures the combination (e.g., product) of the harmonic power factor (also known as the "distortion power factor") and the displacement power factor. The system can include, for example, some units that generate a low harmonic power factor typically caused by non-linear loads (such as switching elements, such as LED drivers or power sources in IT appliances), and some units that generate a low displacement power factor typically caused by linear loads (such as inductors and capacitors, such as heating, ventilation, and air conditioning systems).

[0130] The power factor measured in this system takes into account the overall impact of both types of power factors.

[0131] The harmonic (distortion) power factor is also particularly related to the total harmonic distortion (THD). Therefore, by transferring the luminaires to internal battery control, the harmonic power factor seen at the total source increases, and thus the total harmonic distortion decreases.

[0132] The power factor is estimated at the system level and provided as an external input, and is provided to each of the luminaires 32a - 32d. Optionally, each luminaire additionally locally measures its own power factor. When a low power factor is detected, the system can instruct the luminaires, preferably those with a low dimming level, to switch to battery operation. Alternatively, it can instruct the luminaires with a locally measured power factor below a threshold to switch to battery supply.

[0133] Typical commercial and industrial buildings consume 25 - 30% of their total electricity for lighting loads and 35 - 40% for their HVAC loads, depending on the geographical location. However, lighting loads can operate at the highest power factor (e.g., up to 0.98), while conventional HVAC loads operate at a power factor of approximately 0.7. HVAC loads typically have motors that operate at a power factor of 0.7 - 0.8 at full load, but at 25% load, the power factor drops below 0.5.

[0134] For example, there may be a lighting load of 1000 VA, which is 25% of the load in the building, and an HVAC load of 1500 VA, which is 37.5% of the load in the building.

[0135] For the lighting load, the active (real) power is 980 W, and for a power factor of 0.98, the apparent power is 1000 VA.

[0136] For the HVAC load, the active (real) power is 1050 W, and for a power factor of 0.7, the apparent power is 1500 VA.

[0137] The total system level power factor will be calculated as follows:

[0138] PF (combined) = total active power / total apparent power = (980 + 1050) / (1000 + 1500) = 0.812.

[0139] Therefore, when there are additional loads with a high power factor, the total power factor increases, and it compensates for the low HVAC load power factor of 0.7. Thus, when the total electricity cost is low, by switching the high power factor load (such as a luminaire) when it is at its highest power factor to compensate for the total power factor, this solution is viable for power factor compensation. This will increase the overall demand, so when the demand can be shifted, this is interesting. The increased overall demand makes this method beneficial for off-peak hours.

[0140] During peak hours, it is of course beneficial to reduce the load rather than operate at a high load with only a slightly better power factor.

[0141] Another method is to switch the luminaires with a low power factor (< 0.7) from the AC mains to the battery so that when the HVAC power factor is better than that of the luminaires, the HVAC power factor is not deteriorated.

[0142] If the IT load 36 does not have power factor correction, or when the laptop is fully charged but connected to the adapter (i.e., in the trickle charging mode (low power mode)), then the IT load 36 is very critical for deteriorating the power factor of the entire system. By sensing the dynamic power factor operation of these IT devices, the system can plan the power operation of the luminaires.

[0143] The present invention is particularly interested in indoor or outdoor lighting applications where deep dimming luminaire operation is expected. However, this is generally of interest for loads with different operating modes that give different power factors.

[0144] Figure 4 A method of controlling an electrical appliance having an output load is shown, including:

[0145] In step 40, access to an AC source is provided to the appliance, and power conversion is performed to convert AC power from the AC source for supply to the load;

[0146] In step 42, access to an auxiliary power source is provided to the appliance;

[0147] In step 44, a control signal related to the power factor associated with the AC source is received or generated; and

[0148] In step 46, based on the control signal, the amount of power to be supplied from the AC source to the output load and the amount of power to be supplied from the auxiliary power source to the output load are selected.

[0149] The above system utilizes a controller or a processor to process data. Figure 5 An example of a computer 50 for implementing the above controller or processor is shown.

[0150] The computer 50 includes, but is not limited to, a PC, a workstation, a laptop computer, a PDA, a handheld device, a server, a memory, etc. Generally, in terms of the hardware architecture, the computer 50 may include one or more processors 51, a memory 52, and one or more I / O devices 53 communicatively coupled via a local interface (not shown). The local interface may be, for example but not limited to, one or more buses or other wired or wireless connections, as known in the art. The local interface may have additional elements (such as controllers, buffers (caches), drivers, repeaters, and receivers) to enable communication. In addition, the local interface may include address, control, and / or data connections to enable proper communication among the foregoing components.

[0151] The processor 51 is a hardware device for executing software that may be stored in the memory 52. The processor 51 may actually be any custom or commercially available processor, a central processing unit (CPU), a digital signal processor (DSP), or an auxiliary processor among several processors associated with the computer 50, and the processor 51 may be a semiconductor-based microprocessor (in the form of a microchip) or a microprocessor.

[0152] Memory 52 may include any one or combination of volatile memory elements (e.g., random access memory (RAM), such as dynamic random access memory (DRAM), static random access memory (SRAM), etc.) and non-volatile memory elements (e.g., ROM, erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), programmable read-only memory (PROM), magnetic tape, compact disc read-only memory (CD-ROM), magnetic disk, floppy disk, cassette tape, cartridge tape, etc.). In addition, memory 52 may contain electronic, magnetic, optical, and / or other types of storage media. Note that memory 52 may have a distributed architecture, where the locations of various components are far from each other, but can be accessed by processor 51.

[0153] The software in memory 52 may include one or more separate programs, each of which includes an ordered list of executable instructions for implementing logical functions. According to an exemplary embodiment, the software in memory 52 includes a suitable operating system (O / S) 54, a compiler 55, source code 56, and one or more application programs 57.

[0154] The application program 57 includes many functional components, such as computing units, logics, functional units, procedures, operations, virtual entities, and / or modules.

[0155] The operating system 54 controls the execution of computer programs and provides scheduling, input / output control, file and data management, memory management, and communication control and related services.

[0156] The application program 57 may be a source program, an executable program (object code), a script, or any other entity including a set of instructions to be executed. When it is a source program, then generally the program is translated by a compiler (such as compiler 55), an assembler, an annotator, etc., which may or may not be included in memory 52, in order to operate correctly in combination with the operating system 54. In addition, the application program 57 may be written in an object-oriented programming language having data and method classes, or a procedural programming language having routines, subroutines, and / or functions, such as but not limited to, C, C++, C#, Pascal, BASIC, API calls, HTML, XHTML, XML, ASP scripts, JavaScript, FORTRAN, COBOL, Perl, Java, ADA,.NET, etc.

[0157] The I / O device 53 may include input devices such as, for example but not limited to, a mouse, a keyboard, a scanner, a microphone, a camera, etc. In addition, the I / O device 53 may further include output devices such as, for example but not limited to, a printer, a display, etc. Finally, the I / O device 53 may further include devices that communicate with both the input and output ends, such as, for example but not limited to, a network interface controller (NIC) or a modem / demodulator (for accessing remote devices, other files, devices, systems, or networks), a radio frequency (RF) or other transceiver, a telephone interface, a bridge, a router, etc. The I / O device 53 also includes components for communicating over various networks such as the Internet or an intranet.

[0158] When the computer 50 is in operation, the processor 51 is configured to execute software stored in the memory 52 to transfer data to and from the memory 52 and generally control the operation of the computer 50 according to the software. The application program 57 and the operating system 54 are read in whole or in part by the processor 51, may be buffered in the processor 51, and then executed.

[0159] When the application program 57 is implemented in software, it should be noted that the application program 57 can actually be stored on any computer-readable medium for use by or in conjunction with any computer-related system or method. In the context of this document, a computer-readable medium can be an electronic, magnetic, optical, or other physical device or apparatus that can contain or store a computer program for use by or in conjunction with a computer-related system or method.

[0160] By studying the drawings, the disclosure, and the appended claims, those skilled in the art can understand and implement other variations of the disclosed embodiments when practicing the claimed invention. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. A lighting device (10), comprising: a lighting element (21) having different output lighting levels; a first input terminal (12) adapted to be connected to an AC source (14); a battery (18) integrated with the lighting device; a second input terminal (16) adapted to be connected to the battery (18), the battery (18) being used to supply power to the lighting element (21); a power converter (20) connected to the first input terminal and adapted to convert AC power from the AC source to supply power to the lighting element (21); an interface (22) adapted to receive a control signal identifying a power factor associated with the AC source, wherein the control signal is associated with the lighting element and depends on the different output lighting levels; and a controller (28) adapted to: select, according to the control signal, an amount of power to be supplied from the first input terminal to the lighting element and an amount of power to be supplied from the second input terminal to the lighting element.

2. The lighting device according to claim 1, wherein the controller (28) is further adapted to select, according to the main total power in kVA and the active power energy price, an amount of power to be supplied from the first input terminal to the lighting element and an amount of power to be supplied from the second input terminal to the lighting element.

3. The lighting device according to any one of the preceding claims, wherein the controller (28) is adapted to select power from only one of the first input terminal (12) and the second input terminal (16) according to the control signal.

4. The lighting device according to claim 1 or 2, wherein the controller is preferably adapted to isolate the power converter from the AC source when selecting power from the second input terminal.

5. The lighting device according to claim 1, wherein the controller (28) is adapted to select the second input terminal in response to a control signal indicating that the power factor of the lighting device itself is lower than a first threshold.

6. The lighting device according to claim 5, wherein the controller (28) is adapted to select the first input terminal in response to a control signal indicating that the power factor of the lighting device itself is higher than a second threshold, the second threshold being the same as or higher than the first threshold.

7. The lighting device according to claim 5 or 6, wherein the interface comprises: a detector (24) for detecting the power factor of the power converter; or a communication module for receiving a control signal from a remote device (26), the remote device (26) being coupled to a group of electrical lighting devices including the present electrical lighting device.

8. The lighting device according to claim 1 or 2, wherein the different output lighting levels at least include any one of the following: different output brightness; different output color / color temperature; and different beam angles.

9. The lighting device according to claim 1 or 2, wherein the controller is preferably adapted, during off-peak hours, to: determine whether the power factor of the power converter itself is higher than a third threshold, and if so, then: Select the first input terminal in response to a control signal indicating that the power factor of the system of other appliances is lower than a fourth threshold, the fourth threshold being lower than the third threshold; and Select the second input terminal in response to a control signal indicating that the power factor of the system of other appliances is higher than the fourth threshold.

10. The illuminator according to claim 1 or 2, wherein the power factor associated with the AC source comprises a combination of a harmonic power factor and a displacement power factor.

11. A system of appliances (32a - 32d, 34, 36) connected to a shared AC source, wherein at least one appliance (32a - 32d) is an illuminator according to any of the preceding claims, and wherein the system further comprises one or more of the following: Heating, ventilation, and air conditioning appliances (34); and IT system appliances (36).

12. A method of controlling an electric illuminator having output lighting elements with different output lighting levels, comprising: (40) Providing access to an AC source to the illuminator and performing power conversion to convert AC power from the AC source for supply to the lighting elements; (42) Providing access to a battery integrated in the illuminator; (44) Receiving or generating a control signal related to the power factor associated with the AC source, wherein the control signal is associated with the lighting elements and depends on the different output lighting levels; and (46) Selecting, based on the control signal, the amount of power to be supplied from the AC source to the output lighting elements and the amount of power to be supplied from the battery to the output lighting elements.

13. The method according to claim 12, wherein the selecting step is for selecting the battery in response to a control signal indicating that the power factor of the illuminator itself is lower than a first threshold, and / or for selecting the AC source in response to a control signal indicating that the power factor of the illuminator itself is higher than a second threshold, the second threshold being the same as or higher than the first threshold.

14. The method according to claim 12, wherein the different output lighting levels comprise any of the following: Different output brightness; Different output color / color temperature; and Different beam angles.

15. A computer program comprising computer program code means adapted to implement the method according to any of claims 12 - 14 when the program is run on a computer.

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