A method of estimating the remaining life span of a driver for driving a load, as well as a corresponding driver system

Abstract

A method of estimating a remaining life span of a driver for driving a load, wherein said driver comprises a power stage arranged for receiving an input voltage and for providing an output to said load, wherein said method comprises the steps of receiving, by a state observer model, a temperature value related to said driver, and receiving a loss value related to a power loss of said driver, determining, by said state observer model, estimated internal states representing component temperature dynamics based on said received temperature value and said received loss value making use of an observer model for mimicking a thermal behavior of said driver, providing, by said state observer model, estimated temperatures of a plurality of electrical components in said driver based on said estimated internal states representing component temperature dynamics using a component matrix, and estimating, by a life span model, said remaining life span of said driver based on said estimated temperatures.

Description

[0001] A method of estimating the remaining life span of a driver for driving a load, as well as a corresponding driver system

[0002] FIELD OF THE INVENTION

[0003] The present disclosure generally relates to the field of lighting and, more specifically, to a method of estimating the lifetime of driver.

[0004] BACKGROUND OF THE INVENTION

[0005] In the context of lighting technology, the estimation of an Light Emitting Diode, LED, driver's lifespan plays an important role in ensuring the reliability and longevity of luminaires. LED drivers serve as the critical components responsible for regulating voltage and current to the LED array, thereby influencing the overall performance and durability of the lighting system. While improvements in LED technology have advancements the lighting industry by offering higher energy efficiency and increased longevity compared to traditional lighting sources, accurately predicting the lifespan of LED drivers remains a highly desirable feature.

[0006] Traditionally, the estimation of an LED driver's lifespan has primarily relied upon monitoring the case temperature of the driver. Luminaire manufacturers may measure the case temperature of their designs during the developmental and verification phases, but also during runtime, , and may utilize this data for determining the anticipated lifespan of the LED driver. This approach is based on the understanding that temperature exerts an important influence on the operational integrity and longevity of electronic components, including LED drivers.

[0007] Central to such an estimation process is the utilization of specialized tools that may leverage comprehensive data on the voltage, current, and temperature characteristics of the LED driver's internal components. These tools may serve as instruments for conducting detailed analyses and simulations, enabling manufacturers to make informed decisions regarding the expected lifespan of the LED driver under varying operating conditions. However, it is important to note that the temperature data utilized in these estimations often pertains to steady-state values, with a predominant focus on worst-case scenarios under fullload conditions. The reliance on case temperature as a primary determinant of LED driver lifespan underscores the significance of thermal management in lighting design. Heat dissipation mechanisms, such as heat sinks and thermal interface materials, are integrated into luminaire designs to mitigate the effects of excessive temperature on LED driver performance. Moreover, advancements in thermal management technologies continue to play a role in enhancing the reliability and longevity of LED drivers, thereby improving the overall lifespan of luminaires.

[0008] Despite the efficacy of current methodologies in estimating LED driver lifespan based on case temperature, there exist inherent limitations and challenges that need further investigation.

[0009] The straightforward temperature case based lifetime estimation, as explained above, may be too simplistic. LED driver failure correlates closely with the temperatures endured by each component throughout its operational lifespan. Assuming a constant case temperature for the entire lifetime lacks accuracy and representation.

[0010] As components switch on and off, they undergo temperature fluctuations over time, potentially causing mechanical stress within the components or around the PCB. Operating at varying dimming levels also impacts actual component temperatures.

[0011] SUMMARY OF THE INVENTION

[0012] It would be advantageous to achieve a method of estimating a remaining life span of a driver for driving a load which is more accurate than traditional approaches. It would further be advantageous to achieve a corresponding driver system.

[0013] In a first aspect of the present disclosure, there is provided a method of estimating a remaining life span of a driver for driving a load, wherein said driver comprises a power stage arranged for receiving an input voltage and for providing an output to said load.

[0014] The method comprises the step of receiving, by a state observer model, a temperature value related to said driver, and receiving a loss value related to a power loss of said driver.

[0015] A further step comprises determining, by said state observer model, estimated internal states representing component temperature dynamics based on said received temperature value and said received loss value making use of a further observer model for mimicking a thermal behavior of said driver. Another step comprises providing, by said state observer model, estimated temperatures of a plurality of electrical components in said driver based on said estimated internal states representing component temperature dynamics using a component matrix.

[0016] Yet another step comprises estimating, by a life span model, said remaining life span of said driver based on said estimated temperatures.

[0017] The inventors have found that it may be beneficial to estimate internal states representing component temperature dynamics of said driver, wherein such an estimation is taken into account when estimating the remaining life span of the driver. This is explained in more detail hereinafter.

[0018] The present disclosure is directed to the concept that lifetime prediction is realized by estimating the component temperatures, for example including temperature change rate, in real-time without actually measuring all the temperatures of these components. This is achieved by measuring a single component, for example the temperature of the casing of the driver, and extrapolating, or estimating, the remainder using a state observer model.

[0019] A state observer model is used to determine the internal states, i.e. directly related to the temperature of the components, without directly measuring all of the internal states. Instead, only one, or a couple of the outputs are actually measured.

[0020] The basic idea behind a state observer model is to use these measured outputs along with knowledge of the system's thermal dynamics to estimate what the internal states of the system are. These internal states are variables that resemble the component temperature dynamics.

[0021] The state observer typically works by using a mathematical model of the driver, preferably a low order system, to predict how the driver’s internal states should change over time based on its inputs. Then, it compares these predictions to the actual measurements and adjusts its estimates of the internal states accordingly.

[0022] The internal states may then be multiplied by a component matrix to obtain the estimated temperatures of the plurality of electrical components in the driver. This may be accomplished by, for example, a linear combination of the state variable with the component matrix.

[0023] A remaining life span of the driver may then be estimated using a life span model and the estimated temperatures of the plurality of electrical components. The inventors have found that the driver may be considered broken if one of its components is defect. As such, using the estimation of the temperatures of a plurality of electrical components, a more accurate estimation can be made of which component in the driver is critical for the life span, and thus determines the remaining life span. This is accomplished by using a life span model. The life span model may thus encompass information, i.e. datasheet information, with respect to allowable temperature range(s) and cycles of each of the plurality of electrical components and degradation models therein of each component.

[0024] Each component may be associated with a particular lifetime model, which lifetime model may encompass parameters like temperature, voltage stresses, power cycles, and the like.

[0025] In the context of the above described method, the "loss value" may refer to the power loss experienced by the driver. Power loss in electrical components typically occurs due to factors such as resistance in conductors, switching losses, aging, and other inefficiencies in the power conversion process.

[0026] For example, in a power stage, losses can occur in the form of heat dissipation due to the resistance of the conductive materials used in the components, as well as losses incurred during switching operations, e.g., in transistors or diodes, or losses due to aging of the components. These losses result in a portion of the input electrical power being converted into heat rather than being delivered to the load.

[0027] The loss value would represent the magnitude of these losses, which is information for estimating the internal temperature dynamics of the components within the driver. By incorporating the loss value into the state observer model, along with temperature measurements, the method aims to estimate the internal states representing component temperature dynamics accurately. This information is then used to predict the remaining lifespan of the driver, taking into account factors such as thermal stress on the components due to these losses.

[0028] The method may be executed, i.e. performed, by a controller present in the driver, for example a microcontroller or anything alike. In another example, only a part of the method is performed at the driver side, and the remainder of the method is performed in the cloud or in a server. In the latter cases, a data communication is to be established between the driver and the cloud or the server.

[0029] It is noted that the presented method is applicable to any driver but, especially, to Light Emitting Diode, LED based drivers, wherein the LED drivers are arranged to operate one or more LEDs.

[0030] In an example, the power stage comprises a temperature sensor, preferably a temperature-dependent resistor, and wherein said step of receiving comprises: receiving, by said state observer model, said internal temperature values related to said driver utilizing only said temperature-dependent resistor.

[0031] The inventors have found that it may be beneficial to measure multiple temperatures of electrical components inside the driver. One such way to do so involves multiple temperature dependent resistors, wherein their resistance value depends on the temperature of strategically chosen locations inside the driver case.

[0032] In a further example, the loss value related to said power loss of said driver is based on at least one of: said input voltage; an output voltage that is provided to said load; an output current that is provided to said load; a dimming level for Light Emitting Diode, LED, based loads.

[0033] In a further example, a plurality of temperature values related to said driver are received, and wherein said plurality of temperature values are provided to said state observer model, such that said state observer model determines an estimated temperature for a range of critical components.

[0034] The advantage of this example is that the estimation of the plurality of temperature values becomes more accurate when multiple temperature values are input to the further observer model.

[0035] In a further example, the further observer model is arranged to minimize an error between an output of said further observer model and said thermal model, wherein said further observer model comprises any of: a proportional component arranged for producing an output proportional to a current state of said error; an integral component arranged for producing an output taking into account cumulative effect of past errors; a derivative component arranged for producing an output taking into account a rate of change of said error over time.

[0036] In the context of control theory, a state observer or estimator is typically a mechanism designed to approximate the internal state of a real-world system, in this case a driver. This approximation is derived from measurements taken of the driver’s inputs and outputs (temperatures). In practical scenarios, directly observing the physical state of the driver, i.e. the temperature of a component, is unfeasible or at least undesired. Instead, it is relied on indirect indicators derived from the driver outputs (temperatures).

[0037] In a further example, component matrix comprises a multiplication of said estimated internal states with a unique value or a set of values like a vector for each of said plurality of electrical components.

[0038] In yet another example, method is being performed by a controller comprised by said driver.

[0039] In another example, the component matrix comprises a multiplication of said estimated internal states with a unique value for each of said plurality of electrical components.

[0040] In yet another example, the method is being performed by a controller comprised by said driver.

[0041] In a second aspect of the present disclosure, there is provided a driver system comprising a driver having a power stage arranged for receiving an input voltage and for providing an output to said load, wherein said driver system comprises: receive equipment arranged for receiving, by a state observer model, a temperature value related to said driver, and receiving a loss value related to a power loss of said driver; process equipment arranged for determining, by said state observer model, estimated internal states representing component temperature dynamics (preferably a low order system, such as second order) based on said received temperature value and said received loss value making use of a further observer model for mimicking a thermal behavior of said driver; provide equipment arranged for providing, by said state observer model, estimated temperatures of a plurality of electrical components in said driver based on said estimated temperature using a component matrix, estimate equipment arranged for estimating, by a life span model, said remaining life span of said driver based on said estimated temperatures.

[0042] It is noted that the advantages as explained with reference to the first aspect of the present disclosure, being the method of estimating a remaining life span of the driver for driving the load, are also applicable to the second aspect of the present disclosure, being the driver system. In an example, the power stage comprises a temperature-dependent resistor, and wherein said receive equipment is further arranged for receiving, by said state observer model, said estimated component temperate value related to said driver.

[0043] In an example, the loss value related to said power loss of said driver is based on at least one of: said input voltage; an output voltage that is provided to said load; an output current that is provided to said load; a dimming level for Light Emitting Diode, LED, based loads.

[0044] In a further example, a plurality of temperature values relates to said driver are received, and wherein said plurality of temperature values are provided to said state observer model, such that said state observer model determines estimated component temperature values based on said plurality of actually measured temperature values.

[0045] In another example, the said observer model is arranged to minimize an error between an output of said observer model and said thermal model, wherein said observer model comprises any of: a proportional component arranged for producing an output proportional to a current state of said error; an integral component arranged for producing an output taking into account cumulative effect of past errors; a derivative component arranged for producing an output taking into account a rate of change of said error over time.

[0046] In an example, the component matrix comprises a multiplication of said estimated internal states with a unique value for each of said plurality of electrical components.

[0047] In yet another example, the receive equipment, process equipment, provide equipment and estimate equipment are implemented in said driver.

[0048] In a third aspect of the present disclosure, there is provided a computer program product comprising a computer readable medium having instructions stored thereon which, when executed by a driver system, cause said driver system to implement a method in accordance with any of the previous examples.

[0049] In the appended figures, similar components and / or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.

[0050] The above and other aspects of the disclosure will be apparent from and elucidated with reference to the examples described hereinafter.

[0051] BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Fig. 1 discloses the temperature of the casing and lifetime relationship of existing LED driver;

[0053] Fig. 2 discloses a LED driver with integrated state observer model;

[0054] Fig. 3 discloses the state observer model in accordance with an example of the present disclosure;

[0055] Fig. 4 discloses the architecture in accordance with the present disclosure, including the output matrix;

[0056] Fig. 5 discloses a flow chart running on a controller to predict the remaining lifespan of a driver.

[0057] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0058] It is noted that in the description of the figures, same reference numerals refer to the same of similar components performing a same of essentially similar function.

[0059] A more detailed description is made with reference to particular examples, some of which are illustrated in the appended drawings, such that the features of the present disclosure may be understood in more detail. It is noted that the drawings only illustrate typical examples and are therefore not to be considered to limit the scope of the subject matter of the claims. The drawings are incorporated for facilitating an understanding of the disclosure and are thus not necessarily drawn to scale. Advantages of the subject matter as claimed will become apparent to those skilled in the art upon reading the description in conjunction with the accompanying drawings.

[0060] The ensuing description above provides preferred exemplary embodiment(s) only, and is not intended to limit the scope, applicability, or configuration of the disclosure. Rather, the ensuing description of the preferred exemplary embodiment(s) will provide those skilled in the art with an enabling description for implementing a preferred exemplary embodiment of the disclosure, it being understood that various changes may be made in the function and arrangement of elements, including combinations of features from different embodiments, without departing from the scope of the disclosure.

[0061] Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise," "comprising," and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to." As used herein, the terms "connected," "coupled," or any variant thereof means any connection or coupling, either direct or indirect, between two or more elements; the coupling or connection between the elements can be physical, logical, electromagnetic, or a combination thereof. Additionally, the words "herein," "above," "below," and words of similar import, when used in this application, refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the Detailed Description using the singular or plural number may also include the plural or singular number respectively. The word "or" in reference to a list of two or more items, covers all the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.

[0062] These and other changes can be made to the technology considering the following detailed description. While the description describes certain examples of the technology, and describes the best mode contemplated, no matter how detailed the description appears, the technology can be practiced in many ways. Details of the system may vary considerably in its specific implementation, while still being encompassed by the technology disclosed herein. As noted above, particular terminology used when describing certain features or aspects of the technology should not be taken to imply that the terminology is being redefined herein to be restricted to any specific characteristics, features, or aspects of the technology with which that terminology is associated. In general, the terms used in the following claims should not be construed to limit the technology to the specific examples disclosed in the specification, unless the Detailed Description section explicitly defines such terms. Accordingly, the actual scope of the technology encompasses not only the disclosed examples, but also all equivalent ways of practicing or implementing the technology under the claims.

[0063] Currently, in the prior art, only the case temperature, Tc, is utilized for estimating the lifetime of an Light Emitting Diode, LED, driver. Luminaire manufacturers gauge Tc during the development and verification phases of their luminaire design. Subsequently, the lifetime is determined based on the actual Tc observed in application, as depicted in Figure 1. This estimation relies on a tool, which utilizes voltage, current, and temperature, VIT, data from internal components of the driver. However, the temperature data is restricted to steady-state values, often observed under the full-load worst-case condition.

[0064] The simplistic lifetime prediction based solely on case temperature, Tc, is conservative. The inventors have found that the failure of a driver, for example an LED driver, is linked to the temperatures experienced by each electrical component throughout its entire service life.

[0065] Assuming a constant Tc for the entire lifetime is neither accurate nor representative. During on / off switching cycles, components undergo temperature fluctuations over time, which can induce mechanical stress within the components and / or around the PCB.

[0066] Operating at different dimming levels, in case of LED drivers, also affects the actual component temperature. By acquiring real-time component temperatures, a significantly more precise lifetime prediction can be attained. The objective of this initiative is to devise a method for obtaining real-time internal component temperatures of the driver throughout its lifetime at a low cost. This objective is accomplished through the implementation of a state observer thermal model.

[0067] Reference is made to figure 2. Here, an LED driver is disclosed that is equipped with an integrated, accurate remaining life prediction capability. This prediction is achieved by estimating component temperatures, for example including temperature change rates, in real-time without the need to measure all temperatures individually. At a minimum, only one component temperature, Tmeas, is directly measured, while the others are estimated through a state observer model running within the LED driver's microcontroller unit, MCU, in real-time. If multiple temperatures are measured, the observer can operate with greater accuracy. Optionally, the case temperature, Tc, can also be measured by the MCU to serve as a reference point for assessing the driver's cooling condition. Further, optionally, the ambient temperature, Ta, can be measured or provided via communication interface to the state observer as additional input information.

[0068] Real-time estimation of power losses of driver components may also be carried out based on the dimming level and the driver's input and output operating conditions. These power losses, along with Tc, are utilized as inputs to the further observer model to accurately estimate the component temperatures. This method is lightweight, requires no additional storage, and can be implemented using a low-cost MCU. While implementing these enhancements, additional hardware may be required, such as temperature probes. For broader applicability, pressure, vibration, and orientation sensors can be incorporated. These sensors facilitate easy detection of any anomalies. Furthermore, the MCU can monitor voltage / transient measurements, serving as explicit influencers on reliability.

[0069] Tmeas can also refer to the MCU chip temperature itself, which is readily accessible, eliminating the need for an extra temperature sensor.

[0070] The implementation of this controller may not require any additional storage, and the interface can be user-friendly, such as utilizing a near-field or optical link for user queries to the driver. The method continuously updates the remaining life indicator in realtime based on the temperatures and other stress factors experienced by the components.

[0071] Measurement of Tc can be addressed separately, as predicting Tc from Tmeas and the thermal model may prove challenging due to factors like convection. Therefore, it is disclosed to introduce an extra measurement for Tc.

[0072] By integrating the prediction functionality into the onboard controller, the need to store measured values in the driver and send them to a cloud service for processing is eliminated. This not only reduces costs associated with storage and internet traffic / processing but also enhances system robustness. Additionally, an onboard controller offers a quick and user-friendly interface.

[0073] When an LED driver is installed within a luminaire, the accuracy of the driver's thermal model may be influenced by the actual cooling conditions, such as convection and the heat transfer coefficient of the mounting surface. To mitigate this issue, it is proposed to incorporate the commonly used reference point temperature, Tc, as an input to the model.

[0074] Tc's location, typically defined by the LED driver manufacturer, is usually a physical point on the casing situated directly above the hottest large component, typically the transformer. The measured Tc reflects the external cooling environment surrounding the driver. With knowledge of Tc and heat loss, the internal temperatures of the driver components can be accurately estimated, eliminating concerns about external air convection effects and the driver's orientation within the luminaire.

[0075] A state-space thermal model of the driver can be developed using tools. Such dynamic thermal model may take the form of differential equations, where state space matrices (A, B, C, D) are identified by the tool. A discrete-time form of the model is also utilized, with a sample time (Ts) specified. A state observer, i.e. figure 3, is then developed to estimate the component temperatures based on inputs such as Tc and component power losses, i.e. Ploss. One of the components, for instance, an electrolytic capacitor (or the printed circuit board), i.e. elcap, is directly measured for temperature, Tmeas, and fed into the observer for closed-loop tracking of the actual temperatures. The observer estimates the temperature, Tmeas, and compares it with the measured Tmeas, using the error as feedback to the model.

[0076] The feedback gain, L, may be chosen appropriately to ensure that the observer's dynamic response is several times faster than that of the plant.

[0077] Since the internal state X of the black-box model system identification lacks a direct physical meaning related to component temperatures, an output matrix, C2, may be required to derive the component temperatures, i.e. figure 4. The C2 matrix, containing multiple rows corresponding to the output temperature channels, enables the observer to generate temperatures for all components.

[0078] The method in accordance with the present disclosure may be implemented as software code running in the MCU, Microcontroller Unit), as depicted in Figure 5. Real-time temperature estimation may require knowledge of component losses, Ploss, which are related to parameters such as input voltage, Vmains, LED voltage, VLED, LED current, ILED. A function can be established to quickly estimate the power loss in the circuit based on these parameters.

[0079] Once Ploss is determined, the state observer may generate real-time component temperatures, which are then used in a reliability model to compute the remaining life of the driver. For a cost-effective implementation, the loop can run as a background routine triggered at a low rate, e.g., every second, while the MCU is also utilized for power stage control and DALI communication. No data storage is required in this framework. The method continuously updates the remaining life indicator in real-time based on the temperatures experienced by the components.

[0080] The lifetime indication can be transmitted to any receiving device via a communication interface such as DALI, NFC, WiFi, or Zigbee. Another use case involves a maintenance worker reading out the remaining life via an NFC reader.

[0081] Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. The provided figures and descriptions of the embodiments of the invention are illustrative and explanatory to the heart of the invention and should not be seen as limiting the invention thereto. 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 thereof.

Claims

CLAIMS1. A method of estimating a remaining life span of a driver for driving a load, wherein said driver comprises a power stage arranged for receiving an input voltage and for providing an output to said load, wherein said method comprises the steps of: receiving, by a state observer model, a temperature value related to said driver, and receiving a loss value related to a power loss of said driver; determining, by said state observer model, estimated internal states representing component temperature dynamics based on said received temperature value and said received loss value making use of a further observer model for mimicking a thermal behavior of said driver; providing, by said state observer model, estimated temperatures of a plurality of electrical components in said driver based on said estimated internal states representing component temperature dynamics using a component matrix, estimating, by a life span model, said remaining life span of said driver based on said estimated temperatures.

2. A method in accordance with claim 1, wherein said power stage comprises a temperature sensor, preferably a temperature-dependent resistor, and wherein said step of receiving comprises: receiving, by said state observer model, said temperate value related to said driver utilizing said temperature-dependent resistor.

3. A method in accordance with any of the previous claims, wherein said loss value related to said power loss of said driver is based on at least one of: said input voltage; an output voltage that is provided to said load; an output current that is provided to said load; a dimming level for Light Emitting Diode, LED, based loads.

4. A method in accordance with any of the previous claims, wherein a plurality of temperature values relates to said driver are received, and wherein said plurality of temperature values are provided to said state observer model, such that said state observer model determines an estimated component temperature values based on said plurality of temperature values.

5. A method in accordance with any of the previous claims, wherein said further observer model is arranged to minimize an error between an output of said further observer model and a thermal model, wherein said further observer model comprises any of: a proportional component arranged for producing an output proportional to a current state of said error; an integral component arranged for producing an output taking into account cumulative effect of past errors; a derivative component arranged for producing an output taking into account a rate of change of said error over time.

6. A method in accordance with any of the previous claims, wherein said component matrix comprises a multiplication of said estimated internal states with a unique value for each of said plurality of electrical components.

7. A method in accordance with any of the previous claims, wherein said method is being performed by a controller comprised by said driver.

8. A driver system comprising a driver having a power stage arranged for receiving an input voltage and for providing an output to said load, wherein said driver system comprises: receive equipment arranged for receiving, by a state observer model, a temperature value related to said driver, and receiving a loss value related to a power loss of said driver; process equipment arranged for determining, by said state observer model, an estimated internal states representing component temperature dynamics based on said received temperature value and said received loss value making use of a further observer model for mimicking a thermal behavior of said driver;provide equipment arranged for providing, by said state observer model, estimated temperatures of a plurality of electrical components in said driver based on said estimated temperature using a component matrix, estimate equipment arranged for estimating, by a life span model, said remaining life span of said driver based on said estimated temperatures.

9. A driver system in accordance with claim 8, wherein said power stage comprises a temperature-dependent resistor, and wherein said receive equipment is further arranged for receiving, by said state observer model, said temperate value related to said driver utilizing said temperature-dependent resistor.

10. A driver system in accordance with any of the claims 8 - 9, wherein said loss value related to said power loss of said driver is based on at least one of: said input voltage; an output voltage that is provided to said load; an output current that is provided to said load; a dimming level for Light Emitting Diode, LED, based loads.

11. A driver system in accordance with any of the claims 8 - 10, wherein a plurality of temperature values relates to said driver are received, and wherein said plurality of temperature values are provided to said state observer model, such that said state observer model determines an estimated component temperature values based on said plurality of temperature values.

12. A driver system in accordance with any of the claims 8 - 11, wherein said further observer model is arranged to minimize an error between an output of said further observer model and a thermal model, wherein said further observer model comprises any of: a proportional component arranged for producing an output proportional to a current state of said error; an integral component arranged for producing an output taking into account cumulative effect of past errors; a derivative component arranged for producing an output taking into account a rate of change of said error over time.

13. A driver system in accordance with any of the claims 8 - 12, wherein said component matrix comprises a multiplication of said estimated internal states with a unique value for each of said plurality of electrical components.

14. A driver system in accordance with any of the claims 8 - 13, wherein said receive equipment, process equipment, provide equipment and estimate equipment are implemented in said driver.

15. A computer program product comprising a computer readable medium having instructions stored thereon which, when executed by a driver system, cause said driver system to implement a method in accordance with any of the claims 1 - 7.

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