X-ray imaging device, power supply device therefor, and associated method

Abstract

The present invention relates to a power supply device for a medical X-ray imaging device, the power supply device having: a mains connection mechanism for connecting to a mains grid, the mains grid having at least one fuse device that does not trigger below a safety current; an actively controllable converter device for converting an input alternating voltage into an output direct voltage as a supply voltage for the X-ray imaging device; an electrical energy storage device and a control device for controlling the converter device to limit the power consumption in the mains grid according to the safety current and to provide the missing required power for the X-ray imaging device from the energy storage device, the control device being configured to control the converter device to perform a time-related limitation of the power consumption in the mains grid according to a current-time curve, wherein the current-time curve is derived from the time-triggering curve of the fuse device, and the time-triggering curve takes into account a thermal fuse that triggers in the case of continuous overload.

Description

Technical Field

[0001] The invention relates to a power supply device for a medical X-ray imaging device in particular, wherein the power supply device has:

[0002] - a mains connection mechanism for connecting to a mains supply providing an input alternating voltage, the mains having at least one fuse device that does not trigger at currents below a safety current,

[0003] - an actively controllable converter device, which in particular includes a rectifier and a boost converter, for converting the input alternating voltage into an output direct voltage as supply voltage for the X-ray imaging device,

[0004] - an electrical energy storage device, and

[0005] - a control device for controlling the converter device to limit the power consumption in the mains according to the safety current and for providing the missing required power from the energy storage device for the X-ray imaging device.

[0006] Furthermore, the invention relates to an X-ray imaging device and a method for operating a power supply device. Background Art

[0007] X-ray imaging is a long-established modality, especially in medical technology. X-ray imaging devices (X-ray equipment) are characterized by strong load fluctuations in the electrical power consumption. For example, an X-ray imaging device consumes only a relatively small and substantially constant base load in the mains in standby mode. However, if an X-ray recording is performed, very high peak loads are generated within a very short period of time, and these peak loads must also be provided by the mains. These peak loads occur in order to generate X-ray pulses for image recording, in particular by means of an X-ray tube or other X-ray radiator components of the X-ray imaging device.

[0008] These requirements are met in the prior art by providing suitable supply terminals for the mains. However, for this purpose, the mains usually has to be adjusted at the planned installation location of the X-ray imaging device, for example in terms of enhanced safety measures and increased line cross-sections. This incurs additional costs. It causes interruptions to the work process and thus additional costs. Therefore, this can be an obstacle in the case where medical devices, such as hospitals or doctor's surgeries, wish to switch to a higher-power X-ray device.

[0009] Since in X-ray radiators where a small peak power is sufficient, such as mammography equipment, common, commercially available fuse sockets are no longer sufficient to operate the X-ray imaging device, and changes have to be made in terms of the mains-side installation.

[0010] To solve the above problems, it has been proposed in the prior art to use an X-ray imaging device with energy storage function, which buffers the required peak energy. Here, an additional electrical energy storage is provided in the X-ray device, and when the required power demanded by the remaining components of the X-ray imaging device exceeds the grid power that can be provided by the grid, it is always partially satisfied by the energy storage and partially by the grid with the help of a control device. Here, the maximum grid power that can be extracted from the grid is usually limited by the control device so that protective measures set on the grid side, such as a fuse device including at least one fuse, are not triggered. Regarding such a fuse device, it is known to indicate the associated safety current, which is also called the rated current or guaranteed minimum holding current. In the case of this safety current, it is ensured that the fuse device does not trigger and does not cut off the current supply. To limit the power consumption in the grid to a specific grid power in this way, for example, it is known to control a controllable converter device for the corresponding power supply device of the X-ray imaging device so that the current in the grid does not exceed the safety current. For example, the intervention can be implemented as part of the regulation of the converter device, which is also used for power factor correction (Power factor correction–PFC). For example, a series of bridge rectifiers and boost converters can be used for such a converter device, or a flyback converter can also be used for such a converter device. Here, it is important that there is a controllable converter topology. In other solutions, it has also been proposed in the prior art to provide an additional external uninterruptible current supply between the X-ray imaging device and the grid.

[0011] DE 10 2010 042 565 A1 exemplarily discloses a device for supplying electrical energy to an imaging medical device, wherein the device is designed such that the imaging medical device can operate only with the operating DC voltage provided by a charging device, with the operating DC voltage provided by the charging device and an energy storage, or only with the grid-related operating DC voltage provided by the energy storage. A lithium-ion battery is used as the energy storage, and the device there allows the X-ray device to operate at the normal supply terminals of the grid without overloading the grid. In particular, the X-ray device can operate at a normal three-phase 16-ampere power supply connection, where 16 A represents an exemplary safety current.

[0012] DE 103 55 424 A1 describes an X-ray device having a mechanism for storing energy, which mechanism includes a supercapacitor to compensate for the deficiency in the energy that can be extracted from the power supply grid.

[0013] DE 10 2009 010 219 A1 relates to a tomographic imaging device which uses an energy storage device to enable the operation of the tomographic device using a normal power supply connection at the customer's site without special measures. Thus, the power grid at the customer's site no longer has to be adapted to the maximum power required during high-performance operation by laying more highly protected lines.

[0014] Precisely in the field of X-ray imaging devices where peak power has to be called upon only briefly, capacitors are suitable as energy storage devices after they can be charged and discharged quickly. In particular, supercapacitors (English: Supercaps) are also suitable. However, it is desirable to design the capacitors to be small for reasons of cost, installation space and effort. Other storage technologies that can be charged and discharged quickly, such as accumulators, are also expensive and complex to implement. Summary of the Invention

[0015] Therefore, the object on which the present invention is based is to enable improved utilization of the power grid in an X-ray imaging device and / or to allow an energy storage device to be implemented advantageously.

[0016] To achieve the object, according to the present invention, a power supply device, an X-ray imaging device and a method for operating the power supply device according to embodiments are proposed. Advantageous design options result from the embodiments.

[0017] In a power supply device of the type initially mentioned, according to the present invention, a control device is configured to control a converter device for time-related limitation of power consumption in the power grid according to a current-time curve, in particular a current-time curve of the current in the power grid, wherein the current-time curve is derived from a time-triggering curve of a fuse device, which time-triggering curve takes into account in particular a thermal fuse triggered in the case of continuous overload.

[0018] Based on a conventional power supply device, the actively controllable converter device of the power supply device can in particular not only be used to rectify the input alternating voltage from the power grid at least temporarily in order to provide an output direct voltage as the supply voltage, but also for power factor correction (PFC). Correspondingly, the control device is particularly advantageously configured to control the converter device for power factor correction and / or to adjust the converter device with respect to a preset voltage for the output direct voltage. Superimposed on this basic regulation, a current-time curve that can be stored in the control device or implemented by components is now used, which ultimately describes the limiting current that can be drawn from the power grid as a function of time. This means that instead of using the safety current, i.e., the guaranteed minimum holding current, that can be drawn from the power grid at any time without the fuse device being triggered, a time-varying limiting current derived from the trigger curve of the fuse device is used instead. Here, within the scope of the present invention, two insights are ultimately combined. On the one hand, a common fuse device, for example, with a power protection switch as the fuse, has different mechanisms, which, viewed in overview, define a time trigger curve for the average current (especially the RMS current) in the power grid through the fuse device. Such a first mechanism can be a magnetic fuse mechanism that triggers when a specific fixed trigger current that is usually significantly higher than the safety current is exceeded. The second mechanism can be a thermal mechanism that is supposed to prevent overheating and the current through the fuse device required for triggering this mechanism decreases over time and especially approaches the safety current, possibly approaching the safety current taking into account a safety margin. It should be noted here that the trigger characteristics of the different mechanisms are of course usually determined by a tolerance range, where, for safety, the lower limit of the tolerance range, i.e., the possible lowest trigger current, can be regarded as the trigger curve. Thus, when observed over time, as the trigger curve for the fuse device, the following possibility results: for a specific period of time, for example, several seconds, the grid current drawn from the power grid can be significantly higher than the current that could be drawn according to the safety current, which is the rated current. For common, known fuse devices in Germany, the safety current in a single-phase power grid is usually 16 A, as also shown in the cited prior art. However, through the analysis of the fuse device, it is, for example, completely feasible that during the first five seconds of a strong load on the power grid, especially a strong load exceeding a threshold, several times, for example, up to five times the safety current can be drawn from the power grid without the fuse device being triggered. The second insight of the present invention is that in an X-ray imaging device, peak power is usually only required for a relatively short period of time, especially when an X-ray pulse is to be output.

[0019] Therefore, if the actual time trigger curve of the fuse device is considered in combination with the short peak power time scale in the X-ray imaging device, the described time window in which a higher grid current can be extracted from the grid without the fuse device triggering can be used to increase the overall energy that can be extracted from the grid. In other words, the current-time curve can describe a limit current that exceeds the safety current, especially at least twice the safety current, for low time values, and / or for higher time values, the current-time curve can at least approach the limit current described by the safety current. Here, of course, it is conceivable that depending on how the trigger curve is observed, the trigger curve is utilized as fully as possible. However, it is also conceivable that the current-time curve describes a grid current with a safety margin that is particularly lower by a percentage than the trigger current of the trigger curve at each moment and / or each time interval. Therefore, generally speaking, the current-time curve basically provides limit current values for different moments / time intervals, which allow the safety current to be temporarily exceeded by the fuse device and thus allow a greater power and thus a greater energy to be extracted from the grid within a shorter time period. Therefore, the extreme utilization of the trigger characteristics of the fuse device provides an energy increase value, which mainly affects the sizing of the energy storage device in a cost-effective, weight-effective, and space-effective manner, especially with regard to the use of capacitor energy storage devices (electrolytic capacitors or supercapacitors). This means that within the scope of the present invention, it is particularly advantageous for the energy storage device to be a capacitor because it is particularly worthwhile to briefly obtain energy from the grid here and is perceptible in the design, especially being able to cause significant savings in sizing (capacitance, structural dimensions...). Here, the capacitor on the output side of the converter device is particularly advantageously used as the energy storage device.

[0020] In other words, the present invention proposes to adjust the converter device according to a presettable current-time characteristic (current-time curve) in order to avoid the triggering of the grid-side fuse device in an extreme manner, which allows for the smallest sizing of the capacitor energy storage device. In particular, it is particularly advantageously feasible to use only the capacitor on the output side of the converter device as the energy storage device.

[0021] Here, it should be noted at this point that the power supply device according to the present invention can also be used for other applications, namely consumer devices, in which a relatively short peak power appears as the required power compared to the relatively low basic power compared to the required power. As an example of this, a welding device is mentioned.

[0022] For an X-ray imaging device, the present invention can be understood as an improved design solution that allows the X-ray imaging device to operate even with a normal power supply connection. Since after chocking the current or power absorbed from the power grid through a special adjustment method so that it remains below the triggering characteristics of the fuse device installed in the building installation, this is of course also feasible without problems within the scope of the present invention. This means that the power grid terminals used by the power supply device's power grid connection mechanism are not electrically overloaded and there is no need to adjust the power grid terminals on the power grid side. It should be emphasized here that in a particularly advantageous design solution of the present invention, the current-time curve can be adjusted on the user side on different triggering curves, so that finally the current-time curve can be appropriately selected according to the planned installation location for the X-ray imaging device. In other words, any arbitrary current-time curve can be set as desired.

[0023] In the present invention, the power or energy required for X-ray recording is usually only partially absorbed from the power grid during the recording process. The difference is provided from the energy storage device, and with the present invention, due to better utilization of the power grid, the size of the installed energy storage device with its energy storage characteristics can be designed to be smaller. Regarding the energy storage device, it should also be noted that the correlation between the X-ray imaging device and the internal resistance and quality of the power grid is also reduced because the required energy can be obtained from the internal energy storage device during X-ray recording.

[0024] Regarding the converter device, according to the present invention, although it is preferred to use a rectifier, especially a bridge rectifier, with a boost converter (boost chopper) connected downstream, basically, in the power supply device, there is a topology in which the current consumption and thus the power consumption can be actively limited or influenced by means of active switching elements.

[0025] Here, it should also be noted at this point that at least one additional converter device can also be connected downstream of the converter device according to the present invention. The at least one additional converter device can, for example, convert the output DC voltage that may be in the range of 380V to 750V into an operating AC voltage for the X-ray radiator and possibly other components of the X-ray imaging device, such as an operating AC voltage in the range of 40kW to 140kW.

[0026] In a specific design of the present invention, it can be proposed that the control device has: an adjustment unit for providing a control variable to the converter device according to at least one first measurement variable, in particular for manipulating the duty cycle of pulse width modulation of a switching element, the at least one first measurement variable in particular including the output DC voltage of a voltage converter; and an adjustment unit for pre-adjusting at least one of the at least one first measurement variables for achieving a current-time curve. Such an adjustment unit can also be understood as a shaping unit, because the adjustment unit ultimately adjusts the first measurement variable or the process of the first measurement variables in a suitable manner, such that a desired current limit for the grid current occurs through the adjustment in the adjustment unit. Therefore, it is proposed to adjust the first measurement variable representing the input value of the adjustment, such that other adjustment strategies of the adjustment unit and also specific design solutions can remain completely unchanged. This is particularly advantageous in the case of an analog design of the adjustment unit, because the adjustment unit can then remain completely unchanged and the control device can still overall achieve the desired limit of the power consumption from the grid. However, even in the case of digital adjustment implemented, for example, via an adjustment algorithm, if only an algorithm section for implementing the adjustment unit is added, the hitherto components of the adjustment algorithm can ultimately remain unchanged, the algorithm section pre-adjusting the value of the first measurement variable according to the current-time curve. Here, the adjustment unit can be connected, for example, between a measuring device of the first measurement variable, such as a tapping point, and the adjustment unit.

[0027] The improvement in the context proposed that the power supply device has a measuring device, which is used to record at least one second measured variable, especially the grid current flowing in the converter device and / or the measured current describing the grid current. The second measured variable describes the current power consumption from the grid. The adjustment unit is configured to evaluate the second measured variable to adjust at least one of the at least one first measured variable to achieve a current-time curve. Therefore, for example, it can be envisaged to measure the grid current in the converter device or the measured current describing the grid current, compare it with the current-time curve in an analog and / or digital manner, and make corresponding modifications to the first measured variable so as to specifically achieve the current-time curve in the adjustment unit. Here, the current is particularly suitable as one of the at least one second measured variables. In addition to especially the grid current and / or the measured current, the voltage related to the grid current or the measured current, such as the input DC voltage in a boost converter, can also be particularly advantageously measured as another second measured variable. If a boost converter is used in a specific embodiment, the boost converter usually has an inductor, especially a coil. The grid current flowing in the inductor mainly describes the power consumption from the grid, especially jointly with the corresponding input DC voltage for the boost converter, that is, the rectified input AC voltage, to describe the power consumption from the grid. However, preferably here, the current measurement is carried out downstream of the controllable switching element of the boost converter. The switching element is usually controlled based on pulse width modulation with a high frequency, so that there is a sufficiently close relationship between the measured current there in the inductor and the grid current, especially in terms of the change curve from which the RMS value similar to the limit current of the grid current in the current-time curve can be derived. However, of course, other measurement locations can also be envisaged. In an embodiment, it is also feasible to directly measure the power as the second measured variable.

[0028] The destination-compliant can use at least one second measurement variable, which would otherwise also be included in the regulation as another first measurement variable among the first measurement variables. In other words, it can be proposed that the regulation unit is also configured to consider the second measurement variable as another first measurement variable not adjusted by the adjustment unit when determining the control variable. This is particularly applicable to the input DC voltage for the boost converter generated after the rectifier and the measured current after the actively controllable switching element when performing power factor correction and regulating to a preset voltage as the output DC voltage, where the duty cycle for pulse width modulation is typically derived by multiplying the deviation of the input DC voltage for the boost converter from the preset voltage to obtain the control variable, and instantaneous current regulation can preferably be based on the measured current through the switching element. Thus, in this case, the second measurement variable is also used as another first measurement variable and is likewise included in the regulation.

[0029] Relatively generally speaking with respect to this design, it is particularly advantageous that the first measurement variable adjustable by the adjustment unit is the output DC voltage, and at least one second measurement variable considered for adjustment describes the grid current and / or the input AC voltage (and thus optionally also describes the input DC voltage after the rectifier). If the output DC voltage as the first measurement variable is modified to appear lower, the power consumption from the grid will increase through regulation. Conversely, increasing the output DC voltage as the first measurement variable enables the power consumption from the grid to be influenced particularly simply, especially by performing addition processes and / or subtraction processes. Here, at least one second measurement variable advantageously describes the power extracted from the grid and thus also describes the current flowing there, especially in the fuse device, which can be compared, for example, with the limit current in the current-time curve. Here, especially with regard to analog implementation, the "shaping" of the output DC voltage as the first measurement variable can be achieved in a particularly uncomplicated manner because addition or subtraction operations can be implemented less complexly. Although in principle it is also conceivable to modify other first measurement variables, such as the input AC voltage or the input DC voltage, this has proven to be more complex because multiplication operations, as will be necessary subsequently, are more difficult to implement and moreover represent non-linear interventions.

[0030] As already indicated, it is particularly advantageous if, in the case of a regulating unit configured in an analog manner, an adjustment unit external to the regulating unit, in particular implemented in an analog manner, is connected upstream of the regulating unit, in particular with respect to a first measured variable adjustable by the adjustment unit. In this way, the regulating unit does not have to be changed and can be used directly as known for the regulating unit from the prior art. Exactly in a single-phase power grid, the use of analog regulating units is still common due to their simple and advantageous implementation, such that another distinct advantage is achieved here by the present invention. Here, the adjustment unit itself can be implemented in an analog manner, for example, using coupling elements and / or comparators and / or operational amplifiers and / or resistors and / or capacitors. For example, if a current-time curve is to be implemented in which a first limit current, for example, two to five times the safety current, is to be permitted for a first time interval up to four seconds, and the safety current is to be determined as the limit current for the remaining time interval after four seconds, it is conceivable to use two comparators with different time constants / timing elements. Then, in the case of the second comparator, a time delay can be provided that ensures that the second comparator only becomes active after the first time interval, i.e., in particular, after four seconds. The two comparators can be set separately to allow adjustment to the corresponding triggering curve of the fuse device to be used, and thus the actually used current-time curve can be derived from the triggering curve. In addition to this simple embodiment, multi-stage analog implementation schemes for more complex current-time curves are of course also feasible.

[0031] However, within the scope of the present invention, it is also conceivable that not only the regulating unit but also the adjustment unit is implemented digitally, for example, in the form of at least one chip or IC. In this case, the regulation algorithm is ultimately implemented by the regulating unit and also by the adjustment unit. Such a digital regulation topology is often used in the prior art for higher powers and / or three-phase power grids and is generally useful as well.

[0032] In addition to the power supply device, the present invention also relates to an X-ray imaging device having a power supply device according to the present invention. All embodiments regarding the power supply device according to the present invention can be similarly transferred to the X-ray imaging device according to the present invention, such that the advantages already mentioned can also be obtained by means of the X-ray imaging device.

[0033] In particular, as already mentioned, it can be proposed that the X-ray imaging device has another converter device operated by an output DC voltage, in particular an inverter for generating the operating voltage of the X-ray tube of the X-ray imaging device. Here, it is conceivable not only to ultimately generate the operating voltage for all components of the X-ray device but also to provide different operating voltages for different components.

[0034] Finally, the invention also relates to a method for operating a power supply device for a medical X-ray imaging device in particular, wherein the power supply device has:

[0035] - a mains connection mechanism for connecting to a mains power supply providing an input alternating voltage, the mains power supply having at least one fuse device that does not trigger below a safety current,

[0036] - an actively controllable converter device, which in particular includes a rectifier and a boost converter, for converting the input alternating voltage into an output direct voltage as a supply voltage for the X-ray imaging device,

[0037] - an electrical energy storage device, and

[0038] - a control device for controlling the converter device to limit the power consumption from the mains power supply according to a safety current and to provide the missing required power for the X-ray imaging device from the energy storage device,

[0039] The method is characterized in that the control device controls the converter device to perform a time-dependent limitation of the power consumption from the mains power supply according to a current-time curve, in particular a current-time curve regarding the current from the mains power supply, wherein the current-time curve is derived from the time-triggering curve of the fuse device, which in particular takes into account a thermal fuse that triggers in the case of continuous overload.

[0040] All embodiments regarding the power supply device according to the invention and the X-ray imaging device according to the invention also correspondingly continue to apply to the method according to the invention. Description of the Drawings

[0041] Other advantages and details of the invention result from the embodiments described below and with reference to the drawings. Shown here are:

[0042] Figure 1 Functional components of the X-ray imaging device according to the invention are shown,

[0043] Figure 2 The triggering characteristics of the fuse device together with the current-time curve derivable therefrom are shown,

[0044] Figure 3 A first specific design of the power supply device according to the invention is shown, and

[0045] Figure 4 A second specific design of the power supply device according to the invention is shown. Detailed Description of the Invention

[0046] Figure 1A schematic principle sketch of the functional components of an X-ray imaging device 1 according to the invention is shown. The X-ray imaging device has a power supply device 2 according to the invention, via which the X-ray imaging device 1 can be connected to a grid terminal of a grid 4, which is only shown here, via a grid connection mechanism 3 of the power supply device. In this case, a fuse 5 is associated with the grid terminal on the grid side. For the fuse, on the one hand, a minimum holding current as a guarantee of a safety current / rated current is known, and then for this minimum holding current, the fuse 5 will not trigger even if the safety current is maintained for a longer time. In addition, a triggering characteristic in the form of a triggering curve is known with respect to the fuse 5, which shows after which time and under which triggering currents a triggering occurs.

[0047] This triggering feature Figure 2 The safety current I N The multiples of the safety current are plotted downwards, the time in seconds / minutes is plotted in the horizontal line, and the triggering time is thus plotted with respect to the illustrated triggering characteristic, after which the safety device 5 triggers at a specific multiple of the safety current.

[0048] At least one fuse of the fuse arrangement 5 is currently based on two triggering mechanisms, namely a magnetic triggering mechanism, the triggering characteristics of which are indicated by a tolerance range 6, and a thermal triggering mechanism, the triggering characteristics of which are indicated by a tolerance range 7. The lower limit of the tolerance ranges 6, 7 with respect to the current, i.e. Figure 2 The limit shown at the top in FIG. 8 forms a trigger curve 8 which represents the minimum possible trigger current.

[0049] Back to Figure 1 In addition to the power supply device 2, the X-ray device 1 also includes other components, of which a recording device 9 with an X-ray radiator 10 and an X-ray detector 11 is shown by way of example. In order for the X-ray radiator 10 to be able to irradiate an object for X-ray recording, the X-ray radiator must generate X-ray radiation in a short time at a very high power requirement. This is achieved, for example, with the aid of an X-ray tube. In order to be able to provide an operating voltage for the X-ray radiator 10, the power supply device 2 first has a converter device 12, which provides an output DC voltage, for example, in the range of 380V to 750V, which is transmitted to another converter device 13, which provides an operating AC voltage, for example, in the range of 40kW to 140kW, for the X-ray radiator 10 (and optionally other components of the X-ray imaging device 1).

[0050] The converter device 12 has an active converter topology 14, which is only labeled here, and the active converter topology has at least one switching element that can be controlled to adjust the converter device 12. In addition, the converter device 12 currently includes a capacitor 15, such as an electrolytic capacitor or a supercapacitor, which, as will be further explained, also serves as the energy storage 16 of the power supply device 2.

[0051] The operation of the power supply device 2 is controlled by a control device 17, which currently primarily includes an adjustment unit 18. The adjustment unit 18 adjusts the converter device 12 for power factor correction and regulates the output DC voltage to a preset voltage. However, the control device 17 also has an adaptation unit 19. The adaptation unit 19 ensures a time limit for the power that can be drawn from the electrical network 4 based on the current-time curve, which ensures that the protection device 5 is not triggered, but still at least temporarily allows the safety current to be exceeded and thus at least temporarily allows a greater power extraction and thus energy extraction from the electrical network 4.

[0052] For example, if during an X-ray recording, the required power of the X-ray imaging device 1 is greater than the grid power that can currently be drawn from the electrical network 4, the remaining difference is provided from the energy storage 16.

[0053] Here, the current-time curve is derived from the triggering curve 8, as also shown in Figure 2 Exemplarily, two current-time curves 20, 21 are schematically shown there. The current-time curve 20 relates to a simple, analogously not overly complexly implementable triggering curve, which, as will be further explained, allows approximately 2.8 times the safety current for a first time interval up to about four seconds. However, in the time interval after four seconds, only the safety current is allowed. However, the current-time curve 21 more precisely follows the triggering curve 8 within the safety margin. The current-time curve can, for example, be advantageously used in digital regulation.

[0054] In any case, a current higher than the safety current can be temporarily drawn from the electrical network 4, such that more grid power and thus also more energy can be obtained there temporarily, so that the capacitor 15 can be dimensioned smaller. It should be noted here that in the X-ray imaging device 1, the time during which this peak power is required as the demanded power is usually also quite small, for example, within the shown time interval up to four seconds, such that a practically relevant energy increase is obtained.

[0055] Therefore, according to Figure 1The generally described control device 17 in [the text] allows analog or digital PFC and preset voltage regulation while taking into account a presettable current-time characteristic for avoiding the triggering of the fuse device 5 in an extreme manner, which allows for the smallest possible dimensioning of the capacitors 15 / general energy storage device 16 used.

[0056] Figure 3 and Figure 4 shows specific embodiments of the power supply devices 2a, 2b according to the invention. In Figure 3 this case, an analog implementation is provided not only for the regulating unit 18 but also for the adjusting unit 19.

[0057] Starting from the electrical network 4 (the equivalent circuit diagram of the electrical network also shows the impedance there, in addition to the fuse device 5), the converter device 12 includes a rectifier 22 and a boost converter 23 (English: Boost Converter). In addition to an inductor 24 known in principle, the boost converter 23 also includes a controllable switching element 25, a freewheeling diode 26, and a capacitor 15. The grid current through the inductor 24 and the half-sinusoidal input DC voltage present after the rectifier 22 significantly define the power extraction from the electrical network 4.

[0058] Compared with known devices, the analog circuit of the regulating unit 18 does not change. Here, the output DC voltage (U SENSE,DC ), the input DC voltage (U IN,DC ), and the measured current (I SENSE ) measured via the measuring device 27 are used as the first measurement variables, and regulation is performed based on the first measurement variables, and the control variable forms the duty cycle (PWM) at the switching element 25. Here, the measured current is recorded on the ground side via the measuring device 27 after the switching element 25. However, the RMS value of the grid current through the inductor 24 can be derived from the measured current without problems and with sufficient accuracy.

[0059] It should be understood that the regulating unit 18 described now is purely exemplary. Of course, any regulating topology known in principle from the prior art can be used here.

[0060] In the purely schematically shown regulating topology, first, the deviation between the output DC voltage and the preset voltage (U REF ) is determined by an error amplifier 28, and the deviation can be prefiltered in an optional filter 29 before being multiplied by the input DC voltage in a multiplier 30. Pulse width modulation is performed in block 31, more precisely, currently as an instantaneous current regulation considering the measured current.

[0061] For the current limitation of power extraction according to the current-time curve 20 or 21, the adjustment unit 19 is connected upstream of the regulation unit 18 in the input line path of the output DC voltage as the first measurement variable, where a circuit 32 for implementing the current-time curves 20, 21 is used, and the circuit can also be configured in an analog manner as required. The circuit 32 pre-adjusts the value of the output DC voltage, and in particular, during the regulation of the regulation unit 18, an increase will cause a reduction in the power extraction from the power grid 4. As the input variable here called the second measurement variable, the measured current and the input DC voltage describing the power extraction from the grid are used. For example, to implement the current-time curve 20 in an analog manner, two comparators with different delay elements can be used, such that the second comparator becomes effective only after four seconds (end of the time interval), and different limit currents can be implemented in a simple manner in the two time intervals used. Of course, more complex design solutions are also conceivable, for example, if the current-time curve 21 should be approximated more closely.

[0062] Therefore, after the following situation, the adjustment unit 19 can also be understood as a shaping unit: the first measurement variable of the output DC voltage is pre-adjusted using the second measurement variable, such that through the regulation of the regulation unit 18, the power consumption is compulsorily limited without changing the regulation, taking into account the (time) triggering characteristics 6, 7 of the safety device 5.

[0063] Figure 3 Another design with a digital control device 17 is shown, where for simplicity, only the active converter topology 14 is again schematically shown, also to clarify that different designs of the converter device 12 can be used. The regulation is implemented as a regulation algorithm, and the regulation algorithm is supplemented by steps 33 for implementing the adjustment unit. Without being limited to the specific embodiment, the remaining unchanged regulation algorithm again shows the determination of the deviation between the output DC voltage and the preset voltage in the error calculation step 34, the voltage regulator 35, the current regulator 36, and the pulse width modulation step 37.

[0064] Although the details of the present invention have been described and illustrated in detail by the preferred embodiments, the present invention is not limited by the disclosed examples, and other variants can be derived therefrom by those skilled in the art without departing from the protection scope of the present invention.

Claims

1. A power supply device for an X-ray imaging device, the power supply device having: at least one mains connection mechanism for connecting to a mains power supply providing an input AC voltage, the mains power supply having at least one fuse device that does not trip at currents below a safety current; an actively controllable converter device for converting the input AC voltage into an output DC voltage as the supply voltage for the X-ray imaging device; an electrical energy storage device; and a control device for controlling the converter device to limit the power consumption from the mains power supply according to the safety current and to provide the missing required power for the X-ray imaging device from the energy storage device; the control device is configured to control the converter device to perform a time-dependent limitation of the power consumption from the mains power supply according to a current-time curve derived from the time tripping curve of the fuse device.

2. The power supply device according to claim 1, wherein the current-time curve describes, for at least one of each moment and each time interval, a mains current with a safety margin that is a percentage lower than the tripping current of the time tripping curve at at least one of the moment and the time interval, and the current-time curve describes at least one of the following: for relatively low time values, describes a limit current exceeding the safety current; and for relatively high time values, at least approaches the limit current described by the safety current.

3. The power supply device according to claim 1, wherein the energy storage device is a capacitor of the converter device.

4. The power supply device according to claim 1, wherein the control device has: a regulating unit for providing a control variable to the converter device according to at least one first measurement variable; and an adjusting unit for pre-adjusting at least one of the at least one first measurement variable to achieve the current-time curve.

5. The power supply device according to claim 4, wherein the power supply device has: a measuring device for recording at least one second measurement variable describing the current power consumption from the mains power supply, wherein the adjusting unit is configured to evaluate the at least one second measurement variable to adjust at least one of the at least one first measurement variable to achieve the current-time curve.

6. The power supply device according to claim 5, wherein the regulating unit is configured to consider the at least one second measurement variable as another first measurement variable not adjusted by the adjusting unit when determining the control variable.

7. The power supply device according to claim 5, wherein the at least one first measurement variable adjustable by the adjusting unit is the output DC voltage, and the at least one second measurement variable considered for adjustment describes at least one of the mains current and the input AC voltage.

8. The power supply device according to claim 4, wherein, in the case where the adjustment unit is configured in an analog manner, the adjustment unit external to the adjustment unit is connected upstream of the adjustment unit.

9. The power supply device according to claim 1, wherein the control device is configured to control the converter device for at least one of the following: performing power factor correction and automatically adjusting the converter device with respect to a preset voltage for the output DC voltage.

10. The power supply device according to claim 1, wherein the actively controllable converter device includes a rectifier and a boost converter.

11. The power supply device according to claim 1, wherein the control device is configured to control the converter device to perform a time-related limitation on the power consumption from the power grid according to a current-time curve of the current from the power grid, the current-time curve being derived from a time-triggering curve of the fuse device, and the time-triggering curve taking into account at least one thermal fuse triggered in the case of continuous overload.

12. The power supply device according to claim 11, wherein the current-time curve describes, for at least one of each moment and each time interval, a grid current with a safety margin that is a percentage lower than the triggering current of the time-triggering curve at at least one of the moment and the time interval, and the current-time curve describes at least one of the following: For relatively low time values, describing a limit current exceeding the safety current, and For relatively high time values, at least approaching the limit current described by the safety current.

13. The power supply device according to claim 2, wherein the energy storage device is a capacitor of the converter device.

14. The power supply device according to claim 3, wherein the capacitor is an output-side capacitor.

15. The power supply device according to claim 4, wherein the adjustment unit provides a control variable to the converter device according to the at least one first measurement variable, which is a duty cycle of pulse width modulation for controlling a switching element, and the at least one first measurement variable includes the output DC voltage of the boost converter.

16. The power supply device according to claim 6, wherein the at least one first measurement variable that can be adjusted by the adjustment unit is the output DC voltage, and the at least one second measurement variable for adjustment describes at least one of the grid current and the input AC voltage.

17. The power supply device according to claim 2, wherein the control device is configured to control the converter device for at least one of the following: performing power factor correction and automatically adjusting the converter device with respect to a preset voltage for the output DC voltage.

18. An X-ray imaging device having the power supply device according to claim 1.

19. The X-ray imaging device according to claim 18, wherein the X-ray imaging device has another converter device operated by an output DC voltage for generating an operating voltage of an X-ray tube of the X-ray imaging device.

20. A method for operating a power supply device for a medical X-ray imaging device, the power supply device having: at least one mains connection mechanism for connecting to a mains providing an input AC voltage, the mains having at least one fuse device that does not trigger in the case of a current below a safety current, an actively controllable converter device for converting the input AC voltage into an output DC voltage as a supply voltage for the X-ray imaging device, an electrical energy storage device, and a control device for controlling the converter device to limit the power consumption from the mains according to the safety current and for providing missing demand power for the X-ray imaging device from the energy storage device, controlling the converter device via the control device to perform a time-related limitation of the power consumption in the mains according to a current-time curve derived from a time-triggering curve of the fuse device.

21. The method according to claim 20, wherein the manipulation comprises: Controlling the converter device to perform a time-related limitation of the power consumption in the mains according to a current-time curve regarding the current from the mains, the current-time curve being derived from a time-triggering curve of the fuse device, the time-triggering curve taking into account at least one thermal fuse that triggers in the case of a continuous overload.

22. An X-ray imaging device having the power supply device according to claim 2.

23. The X-ray imaging device according to claim 22, further having: another converter device operated by the output DC voltage for generating an operating voltage of an X-ray tube of the X-ray imaging device.

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