System for optimizing voltage distribution along high voltage doubler rings.

Abstract

A high voltage power supply is disclosed. The high voltage power supply includes a primary winding and one or more secondary windings. In one embodiment, a single secondary winding is used and the high voltage doubler circuit includes a capacitor string and a diode string. In another embodiment, multiple secondary windings are used and the high voltage doubler circuit includes multiple low voltage doubler circuits arranged in series. One or more shields are arranged on the printed circuit board to provide a more even distribution of voltage across the capacitors in the high voltage doubler circuit. In a particular embodiment, a high voltage shield is arranged at the high voltage output and a low voltage shield is arranged at the lower voltage end of the high voltage doubler circuit. One or more intermediate shields may be arranged in the high voltage doubler circuit.

Description

[Technical field]

[0001] This application claims priority to U.S. Patent Application No. 17 / 159,658, filed January 27, 2021, the entire disclosure of which is incorporated by reference herein.

[0002] SUMMARY OF THE DISCLOSURE Embodiments of the present disclosure are directed to a system for evenly distributing voltage along a high voltage doubler ring in a secondary winding of a printed circuit board. [Background technology]

[0003] An insulated core transformer (ICT) high voltage power supply is a common method of producing a high voltage DC output from an AC voltage. The input AC voltage is coupled to a primary winding.

[0004] In a particular embodiment, there is a single secondary winding. This secondary winding multiplies the input voltage by a factor equal to the ratio of the number of turns of the secondary winding to the number of turns of the primary winding. The rectification and doubling of the voltage is accomplished using a voltage doubler circuit with diodes and capacitors. Typically, a voltage doubler has two capacitors that store the voltage, and two diodes, each of which only allows current to pass in one direction. The capacitors are placed in series, resulting in doubling of the voltage. Due to cost and high voltage ratings, many diodes and capacitors with lower voltage ratings may be placed in series, rather than using two diodes and two capacitors. For example, 20 capacitors rated at 100V may be placed in series, rather than using two capacitors rated at 1000V. Diodes may be configured similarly.

[0005] In other embodiments, there are multiple secondary windings, each with its own dedicated voltage doubler circuit, which are placed in series to generate the desired higher DC voltage.

[0006] In each embodiment, ideally, the same voltage is stored by each capacitor in the system. That is, if the desired output voltage is 2000V and there are 20 capacitors, ideally, each of these capacitors would have a potential of 100V. However, in reality, stray capacitance affects each capacitor, forcing some capacitors to store a lower voltage than the ideal voltage and other capacitors to store a higher voltage than the ideal voltage. Similarly, the voltage across some diodes may be greater than the voltage across other diodes.

[0007] This uneven voltage distribution across the capacitors and diodes can result in voltage stresses on these components, potentially resulting in premature failure of the components.

[0008] It would therefore be advantageous to have a system and method for improving voltage uniformity between these components. Moreover, it would be beneficial if this approach were low cost and easy to implement. Summary of the Invention

[0009] A high voltage power supply is disclosed. The high voltage power supply includes a primary winding and one or more secondary windings. In one embodiment, a single secondary winding is used and the high voltage doubler circuit includes a capacitor string and a diode string. In another embodiment, multiple secondary windings are used and the high voltage doubler circuit includes multiple low voltage doubler circuits arranged in series. One or more shields are arranged on the printed circuit board to provide a more even distribution of voltage across the capacitors in the high voltage doubler circuit. In a particular embodiment, a high voltage shield is arranged at the high voltage output and a low voltage shield is arranged at the lower voltage end of the high voltage doubler circuit. One or more intermediate shields may be arranged in the high voltage doubler circuit.

[0010] According to one embodiment, a high voltage power supply is disclosed. The high voltage power supply includes a primary winding, a secondary winding having a first end and a second end, and a printed circuit board, the printed circuit board includes a capacitor string with a plurality of capacitors arranged in series, where a negative end of a first capacitor in the capacitor string is at a lower voltage and a positive end of a last capacitor in the capacitor string is at a high voltage output, a diode string with a plurality of diodes arranged in series, where an anode of a first diode in the diode string is connected to a lower voltage and a cathode of a last diode in the diode string is connected to a high voltage output, a first end is electrically connected to a midpoint of the capacitor string, and a second end is electrically connected to the midpoint of the diode string, and a high voltage shield disposed at the positive end of the last capacitor and electrically connected to the high voltage output, the shield including a wide trace disposed on one or more layers of the printed circuit board. In a particular embodiment, the high voltage power supply includes a low voltage shield disposed at the negative end of the first capacitor and electrically connected to the lower voltage. In a particular embodiment, the high voltage shield and the low voltage shield each comprise a signal trace having a length between 40 mm and 100 mm and a width between 3 mm and 10 mm. In a particular embodiment, the high voltage shield and the low voltage shield are disposed on the same side of the printed circuit board as the capacitor string. In a particular embodiment, the high voltage shield and the low voltage shield are disposed on opposite sides of the printed circuit board as the capacitor string. In a particular embodiment, the high voltage power supply comprises a mid-shield disposed between two adjacent capacitors in the capacitor string and electrically connected to a trace connecting the two adjacent capacitors. In a particular embodiment, the mid-shield is disposed at a midpoint of the capacitor string. In a particular embodiment, the high voltage power supply comprises a second mid-shield disposed between two different adjacent capacitors in the capacitor string. In a particular embodiment, the voltage across the first capacitor is within 10% of the voltage across the last capacitor.

[0011] According to another embodiment, a high voltage power supply is disclosed. The high voltage power supply includes a primary winding, a plurality of secondary windings, each secondary winding having a first end and a second end, and The device includes a printed circuit board, the printed circuit board including a plurality of low voltage doubler circuits arranged in series to form a high voltage doubler circuit having a lower voltage at a first end and a high voltage output at a second end, each low voltage doubler circuit having a positive end and a negative end, the low voltage doubler circuit including a first capacitor and a second capacitor arranged in series, and a first diode and a second diode arranged in series, the positive end of the first capacitor being electrically connected to the cathode of the first diode and the negative end of the second capacitor being electrically connected to the cathode of the first diode and the positive end of the low voltage doubler circuit. The present invention also includes a plurality of low-voltage doubler circuits, each of which is electrically connected to the anode of the diode and includes a negative end of a low-voltage doubler circuit, a first end of each secondary winding being electrically connected to a trace connecting the first capacitor and the second capacitor, and a second end of each secondary winding being electrically connected to a trace connecting the first diode and the second diode, and a high-voltage shield disposed at a second end of the high-voltage doubler circuit and electrically connected to a high-voltage output, the shield including a wide trace disposed on one or more layers of a printed circuit board. In a particular embodiment, the high-voltage power supply includes a low-voltage shield disposed at a first end of the high-voltage doubler circuit and electrically connected to a lower voltage. In some embodiments, the high-voltage shield and the low-voltage shield each include a signal trace having a length between 40 mm and 100 mm and a width between 3 mm and 10 mm. In a particular embodiment, the high-voltage shield and the low-voltage shield are disposed on the same side of the printed circuit board in the high-voltage doubler circuit. In a particular embodiment, the high-voltage shield and the low-voltage shield are disposed on opposite sides of the printed circuit board in the high-voltage doubler circuit. In certain embodiments, the high voltage power supply further comprises a mid-shield disposed between two adjacent low voltage doubler circuits. In certain embodiments, the mid-shield is disposed at a midpoint of the high voltage doubler circuits. In certain embodiments, the high voltage power supply comprises a second mid-shield disposed between two different adjacent low voltage doubler circuits. In certain embodiments, the voltage across the first low voltage doubler circuit disposed closest to the first end is within 10% of the voltage across the last low voltage doubler circuit disposed closest to the second end.

[0012] For a better understanding of the present disclosure, reference is made to the accompanying drawings, which are incorporated herein by reference. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a representative schematic diagram illustrating a high voltage power supply with voltage non-uniformity compensation according to one embodiment. [Diagram 2] 2 illustrates a layout of the high voltage power supply of FIG. 1 according to one embodiment. [Diagram 3] FIG. 2 is a representative schematic diagram illustrating a high voltage power supply with voltage non-uniformity compensation according to one embodiment. [Figure 4] 4 illustrates a layout of the high voltage power supply of FIG. 3 according to one embodiment. [Diagram 5] 1 illustrates a process for determining shield placement, size, and number, according to one embodiment. [Figure 6] 4 shows the voltage distribution of an element in a high voltage power supply compared to the prior art. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] This disclosure describes systems and methods for creating a more uniform voltage distribution across multiple capacitors and diodes in an ICT high voltage DC power source.

[0015] FIG. 1 shows a first embodiment of a voltage doubler circuit 1, with an external power supply 10, a primary winding 20, and a single secondary winding 30. The components of the voltage doubler circuit 1 are disposed on a printed circuit board. The printed circuit board may be a conventional printed circuit board with multiple layers, with conductive layers separated from each other by insulating material such as FR4. In certain embodiments, the printed circuit board may include two conductive layers, a top side and a bottom side. Electrical traces may be disposed on these layers of the printed circuit board. Vias may be used to connect the traces on the top side with the traces on the bottom side. These electrical traces are used to electrically connect the various components disposed on the printed circuit board. In other embodiments, there may be more than two conductive layers.

[0016] The voltage doubler circuit 1 further comprises a capacitor string. The string comprises a number of capacitors 100, such as capacitors 100a, 100b, 100c, 100d, arranged in series. The capacitors may each have the same capacitance and voltage rating. A first end of the capacitor string is connected to a lower voltage, which may be ground, and a second end of the capacitor string is a high voltage output 150. The voltage doubler circuit 1 further comprises a string of diodes. The diode string further comprises a number of diodes 110, such as diodes 110a, 110b, 110c, 110d, arranged in series. A first end of the diode string is connected to a lower voltage, and a second end of the diode string is a high voltage output 150. The cathode of a diode is connected to the anode of an adjacent diode in the diode string. Thus, the anode of the first diode is connected to the lower voltage, and the cathode of the last diode in the diode string is connected to the high voltage output 150. During the positive portion of the AC cycle, diodes 110a, 110b conduct and charge capacitors 100a, 100b, which are located between the midpoint and the high voltage output 150. During the negative portion of the AC cycle, diodes 110c, 110d conduct and charge capacitors 100c, 100d, which are located between the midpoint and the low voltage. Thus, the cathode of each diode is at a higher voltage than that diode's anode. Furthermore, diode 110a is at a higher voltage than diode 110b. Similarly, diode 110c is at a higher voltage than diode 110d.

[0017] In certain embodiments, the number of diodes 110 and capacitors 100 are equal. In other embodiments, the number of diodes 110 and capacitors 100 may be different. The number of capacitors 100 and diodes 110 may be even, such that there are an equal number of diodes and capacitors on either side of the midpoint. A first end of the secondary winding 30 is electrically connected to the midpoint of the capacitor string. A second end of the secondary winding 30 is electrically connected to the midpoint of the diode string. The midpoint indicates that there are as many capacitors 100 (and diodes 110) disposed between the first end and the midpoint as there are between the midpoint and the second end.

[0018] 1 shows four capacitors 100a, 100b, 100c, and 100d and four diodes 110a, 110b, 110c, and 110d, the present disclosure is not limited to this embodiment. Rather, the number of capacitors 100 and diodes 110 is not limited by the present disclosure. Furthermore, the number of capacitors 100 and diodes 110 need not be the same.

[0019] Because the voltage doubler circuit 1 is disposed on a printed circuit board, there may be an inherent capacitance between each trace of the voltage doubler circuit 1 and other traces of different voltages. These stray capacitances are illustrated in FIG. 1 as stray capacitors 120a, 120b, and 120c. Note that these stray capacitors 120a, 120b, and 120c are not physical components. Rather, FIG. 1 depicts the stray capacitances as actual components to better explain the subject matter. Although not shown, each diode 110 has an associated stray capacitance.

[0020] In reality, the floating capacitors 120a, 120b, and 120c affect the voltage stored in each of the capacitors 100a, 100b, 100c, and 100d. In reality, when current flows through the capacitor string, a small amount of current is shunted from each trace and passes through the corresponding floating capacitor. Thus, the capacitor 100a may have slightly more current flowing through it than the current flowing through the capacitor 100b. Thus, more voltage may be stored on the capacitor 100a than on the capacitor 100b. Similarly, more current may flow through the capacitor 100b than through the capacitor 100c.

[0021] To compensate for this stray capacitance, current systems utilize one or more shields 130. The shields 130 are wide traces deposited on one or more layers of a printed circuit board. The shields may have a width and / or length larger than a typical trace. For example, the shields may be rectangular traces connected to a voltage. For example, in certain embodiments, the shields 130 may be located on the top or bottom side of the printed circuit board. In certain embodiments, the shields 130 may be located on both the top and bottom sides. The shields 130 are electrically connected to a voltage. For example, in FIG. 1, there are three shields 130. The high voltage shield 130a is located on the top of the capacitor string and is electrically connected to the high voltage output 150.

[0022] Due to the size of the high voltage shield 130a, there is capacitive coupling with other traces in the voltage doubler circuit 1. For example, there is capacitive coupling between the high voltage shield 130a and the lower voltage end of the capacitor 100a. This capacitance is represented as shield capacitor 140a. Similar capacitive coupling exists between the high voltage shield 130a and some of the other traces in the capacitor string. One such coupling is represented as shield capacitor 140b. Note that these shield capacitors 140a, 140b, 140c are not physical components. Rather, FIG. 1 depicts the shield capacitance as an actual component to better explain the subject matter.

[0023] A shield capacitor functions to source current to a trace that is at a lower potential than the voltage of its shield. Thus, a stray capacitor tends to divert current away from the capacitor string, while a shield capacitor tends to inject current into the capacitor string.

[0024] FIG. 1 shows a high voltage shield 130a located at the high voltage output 150. However, other shields may be present. For example, in this figure, a low voltage shield 130b is located at a lower voltage, which may be ground. In other embodiments, multiple printed circuit boards may be connected in series, and the lower voltage may be the output of the previous printed circuit board in the series, and thus the input voltage of the next stage. In both cases, the low voltage shield 130b serves to reduce the effect of stray capacitance. A mid-shield 130c is located at the midpoint of the capacitor string. Capacitive coupling may exist between the mid-shield 130c and some of the other traces in the voltage doubler circuit 1. For example, one such capacitive coupling is represented as shield capacitor 140c.

[0025] For example, assume a capacitor string includes 20 capacitors, numbered sequentially from lower voltage to higher voltage output, in one embodiment, a mid-shield 130c may be placed at the positive end of the 10th capacitor (i.e., the midpoint).

[0026] Of course, other embodiments are possible. For example, the mid shields 130c may be more closely spaced if desired. The mid shields 130c may be located at the positive ends of the 5th, 10th, and 15th capacitors. Alternatively, the mid shields 130c may be located at the positive ends of the 4th, 8th, 12th, and 16th capacitors. In certain embodiments, the mid shields 130c are equally spaced, but in other embodiments, the mid shields 130c may not be equally spaced. Thus, the mid shields 130c may be located between any two adjacent capacitors in a capacitor string. In other embodiments, the mid shields 130c may be omitted.

[0027] The selection of the number of shields 130 and their locations may be based on a number of factors. The size of the shields 130 may be based on the amount of voltage compensation desired. Additionally, the amount of stray capacitance may be a function of the geometry and material properties of the PCB and the placement of the signal traces on the PCB. Thus, the size and number of shields 130 may be based on the geometry and material properties of the PCB and the desired voltage uniformity along the capacitor string.

[0028] FIG. 2 shows a representative layout of the voltage doubler circuit 1 arranged on a printed circuit board 2. In this embodiment, there are 12 stages 200 in the capacitor string and the diode string. Each stage 200 includes a diode 110 and a capacitor 100. Shields 130a, 130b, 130c are arranged along the capacitor string. A high voltage shield 130 may be arranged at the positive end of the twelfth capacitor, which is electrically connected to the high voltage output. A low voltage shield 130b may be arranged at the negative side of the first capacitor, which is at a lower voltage, and may be grounded. Furthermore, a low voltage shield 130b is electrically connected to the negative side of the first capacitor. A middle shield 130c may be arranged at the midpoint of the capacitor string and electrically connected to the first end of the secondary winding 30. Thus, the voltage of the middle shield 130c may be the average value of the low voltage output and the high voltage output.

[0029] In this embodiment, the shield 130 is shown as a thick trace having a width and a length. The length of the shield may be longer than the space occupied by the stage 200. For example, in one embodiment, the shield 130 may have a length between 40 mm and 100 mm, a width between 3 mm and 10 mm, and a thickness between 75 μm and 150 μm. In one particular embodiment, the shield 130 may have a length of 60 mm, a width of 5 mm, and a thickness of 110 μm. In this manner, the mid shield 130c effectively isolates the two stages 200 on either side of it. The widths of the high voltage shield 130a, the low voltage shield 130b, and the mid shield 130c may vary. Additionally, there may be spacing guidelines based on the voltage of each trace that limit the width of the shield. Additionally, as discussed above, the shield dimensions may depend on the desired voltage compensation and the geometry and material properties of the printed circuit board.

[0030] Thus, in this embodiment, the high voltage power supply comprises a single secondary winding 30, two ends of which are in communication with a voltage doubler circuit 1. The voltage doubler circuit 1 is disposed on a printed circuit board 2. The voltage doubler circuit 1 comprises a capacitor string with a number of capacitors arranged in series. A first end of the capacitor string is connected to a lower voltage, which may be grounded, and a second end of the capacitor string is a high voltage output. The voltage doubler circuit 1 further comprises a diode string with a number of diodes arranged in series. A first end of the diode string is connected to a lower voltage, which may be grounded, and a second end of the diode string is connected to a high voltage output. A first end of the secondary winding 30 is connected to a midpoint of the capacitor string, and a second end of the secondary winding is connected to a midpoint of the diode string. One or more shields 130 are disposed along the capacitor string. In a particular embodiment, there is a high voltage shield 130a connected to the positive end of the last capacitor in the capacitor string connected to the high voltage output, and a low voltage shield 130b connected to the negative end of the first capacitor in the capacitor string connected to a lower voltage, which may be grounded. One or more additional mid shields 130c may be disposed along the capacitor string between the high voltage shield 130a and the low voltage shield 130b. These additional mid shields 130c are connected to traces connecting the positive end of one capacitor to the negative end of an adjacent capacitor along the capacitor string and are biased at a voltage between ground and the high voltage output. Thus, the mid shields 130c are disposed along the capacitor string, disposed between two adjacent capacitors, and electrically connected to the traces connecting the two adjacent capacitors.

[0031] In certain embodiments, the additional mid-shields 130c are equally spaced such that the voltages between adjacent mid-shields are equal or nearly equal, or stated another way, a fixed number of capacitors may be placed between any two adjacent shields.

[0032] The shield may be located on the same side of the PCB as the traces and components. In other embodiments, the shield may be located on both sides of the PCB, or on the opposite side of the PCB from the traces and components. The location of the shield 130 is selected to compensate for stray capacitance and allow connection to the desired voltage.

[0033] FIG. 3 illustrates a second embodiment. In this embodiment, there is an external power source 310, a primary winding 320, and a number of secondary windings 330. Each secondary winding 330 is in communication with an associated low-voltage doubler circuit 350. Each low-voltage doubler circuit 350 includes two capacitors 360a, 360b arranged in series and two diodes 370a, 370b arranged in series. A first end of the secondary winding 330 is in electrical contact with a trace connecting the two capacitors 360a, 360b. A second end of the secondary winding 330 is in electrical contact with a trace connecting the anode of the diode 370a and the cathode of the diode 370b. The positive end of the capacitor 360a is electrically connected to the cathode of the diode 370a. The negative end of the capacitor 360b is electrically connected to the anode of the diode 370b.

[0034] The low voltage doubler circuits 350 are connected in series to form the high voltage doubler circuit 301. In other words, the cathode of the diode 370a of one low voltage doubler circuit 350 is in electrical contact with the anode of the diode 370b of the adjacent low voltage doubler circuit 350.

[0035] Although not shown in Figure 3, there is stray capacitance in the high voltage doubler circuit 301. As explained in relation to Figure 1, there is capacitive coupling between a trace and a second trace or component at a lower voltage. This stray capacitance tends to divert current away from the capacitors 360a, 360b of each low voltage doubler circuit 350.

[0036] Therefore, as shown in the embodiment of FIG. 1, a shield 380 is added. In FIG. 3, there are multiple shields 380. The high voltage shield 380a is electrically connected to the positive end of the most positive low voltage doubler circuit 350. This high voltage shield 380a can be biased at a high voltage output. The low voltage shield 380b is electrically connected to the negative end of the least positive low voltage doubler circuit 350. This low voltage shield 380b can be biased to a low voltage, such as ground. An additional intermediate shield 380c may be further disposed between the high voltage shield 380a and the low voltage shield 380b. For example, in FIG. 3, there is an even number of low voltage doubler circuits 350. In this embodiment, the intermediate shield 380c is disposed such that there are the same number of low voltage doubler circuits 350 between the intermediate shield 380c and the high voltage shield 380a, and between the intermediate shield 380c and the low voltage shield 380b. Thus, if there were twenty low voltage doubler circuits 350, the middle shield 380c could be placed and connected to a trace connecting the positive end of the tenth low voltage doubler circuit 350 and the negative end of the eleventh low voltage doubler circuit 350.

[0037] However, the present disclosure is not limited to this embodiment. There may be additional middle shields 380c. For example, assuming that there are 20 low-voltage doubler circuits 350, the additional middle shields 380c may be disposed and connected to the positive ends of the 5th, 10th, and 15th low-voltage doubler circuits 350. Alternatively, the additional middle shields 380c may be disposed and connected to the positive ends of the 4th, 8th, 12th, and 16th low-voltage doubler circuits 350.

[0038] In certain embodiments, the additional middle shields 380c may be evenly spaced apart.

[0039] FIG. 4 shows a printed circuit board 402 on which a high-voltage power supply is disposed. The high-voltage power supply includes a number of secondary windings 330 and a corresponding number of low-voltage doubler circuits 350. As described above, each low-voltage doubler circuit 350 includes two capacitors 360a, 360b and two diodes 370a, 370b. Each low-voltage doubler circuit 350 is electrically connected in series with at least one other low-voltage doubler circuit 350 to form a high-voltage doubler circuit 301. A high-voltage shield 380a and a low-voltage shield 380b may be disposed at the ends of the high-voltage doubler circuit 301. An additional intermediate shield 380c may be disposed between adjacent low-voltage doubler circuits 350, for example at a midpoint.

[0040] In this embodiment, the shield 380 is shown as a thick trace having a width and a length. The length of the shield may be longer than the space occupied by the low voltage doubler circuit 350. For example, in one embodiment, the shield 130 may have a length between 40 mm and 100 mm, a width between 3 mm and 10 mm, and a thickness between 75 μm and 150 μm. In one particular embodiment, the shield 130 may have a length of 60 mm, a width of 5 mm, and a thickness of 110 μm. In this manner, the middle shield 380c effectively isolates the two low voltage doubler circuits 350 on either side of it. The widths of the high voltage shield 380a, the low voltage shield 380b, and the middle shield 380c may be determined based on the space available on the printed circuit board. Additionally, there may be spacing guidelines based on the voltage of each trace that limit the width of the shield. Additionally, as discussed above, the shield dimensions may depend on the desired voltage compensation and the geometry and material properties of the printed circuit board.

[0041] Thus, similar to the embodiment of Figures 1-2, this embodiment may include one or more intermediate shields disposed between the elements that combine to form the high voltage doubler circuit 301. In Figures 1-2, these elements are capacitors, whereas in the embodiment of Figures 3-4, these elements are low voltage doubler circuits. Additionally, a high voltage shield may be disposed at the high voltage end of the voltage doubler circuit and a low voltage shield may be disposed at the lower voltage of the doubler circuit.

[0042] FIG. 5 shows an example of a method that may be used to determine the placement, size, and number of shields included in a high voltage power supply. As shown in box 500, first, the stray capacitance is calculated based on the geometry and material properties of the printed circuit board design. This can be done theoretically or using electrostatic simulation tools. As shown in box 510, the calculated stray capacitance is incorporated into the electrical circuit design. Next, as shown in box 520, the voltage across each capacitor of the capacitor string (see FIG. 1-2) or high voltage doubler circuit (see FIG. 3-4) can be calculated using electrical circuit theory or a simulation tool such as PSPICE. Based on this result, one or more shields can be incorporated into the design, as shown in box 530. The stray capacitance and shield capacitance can then be calculated theoretically or using electrostatic simulation tools, as shown in box 540. The calculated stray capacitance and shield capacitance are then added to the electrical circuit design, as shown in box 550. Next, as shown in box 560, the voltage across each capacitor in the capacitor string (see Figures 1-2) or high voltage doubler circuit (see Figures 3-4) can be calculated using electrical circuit theory or a simulation tool such as PSPICE. If the resulting voltage distribution is acceptable, the process is complete. If the voltage distribution is not acceptable, boxes 530-560 are repeated to change the placement, number, or size of the shields until an acceptable distribution is achieved.

[0043] The system described herein has many advantages. A simulation was performed for a high voltage power supply with an output of 6.4 kV using 16 elements. These elements may be capacitors as shown in FIG. 1 or low voltage doubler circuits as shown in FIG. 3. Ideally, the voltage across each element may be 400V. As shown in FIG. 6, line 600, in the prior art, the voltage distribution across the elements of a high voltage doubler circuit is not linear. Rather, the elements closer to the high voltage output store more voltage than the elements closer to the lower voltage. In fact, in this simulation, the voltage of the element closest to the high voltage output was calculated to be 564.8V, while the voltage of the element closest to the lower voltage was calculated to be only 237.2V. If the capacitor is rated at 400V, the voltage stress of the capacitor closest to the high voltage output is 1.412. This can result in increased stress on the elements located closer to the high voltage output. This can lead to increased stress on the components and premature failure. In contrast, line 610 shows the distribution of voltage across the elements of a high voltage power supply with the high voltage shield, low voltage shield, and middle shield positioned at 3.2 kV. In other words, the shields are positioned at the minimum voltage, the maximum voltage, and the middle point. Note that the amount of voltage stored by each element of the high voltage doubler circuit is nearly identical, resulting in a nearly linear graph. In this simulation, the voltage of the capacitor closest to the high voltage output was calculated to be 424.4V, while the voltage of the capacitor closest to the lower voltage was calculated to be 384.8V. In other words, the difference between the highest and lowest capacitor voltages is less than 10%. Furthermore, when the capacitors are rated at 400V, the voltage stress of the capacitor closest to the high voltage output is reduced to 1.061, which is a reduction of nearly 25%. This configuration reduces stress on components near the high voltage output and may extend the life of the high voltage power supply.

[0044] The present disclosure is not limited in scope by the specific embodiments described herein. Indeed, in addition to those described herein, various other embodiments and modifications of the present disclosure will be apparent to those skilled in the art from the above description and the accompanying drawings. Accordingly, such other embodiments and modifications are intended to be included within the scope of the present disclosure. Furthermore, although the present disclosure has been described herein in connection with specific implementations in specific environments for specific purposes, those skilled in the art will recognize that the usefulness of the present disclosure is not limited thereto, and the present disclosure may be beneficially implemented in any number of environments for any number of purposes. Therefore, the claims set forth below should be construed in view of the full scope and spirit of the present disclosure as described herein.

Claims

1. 1. A high voltage power supply, Primary winding, a secondary winding having a first end and a second end; and A printed circuit board, a capacitor string comprising a plurality of capacitors arranged in series, the negative end of a first capacitor in the capacitor string being at a lower voltage and the positive end of a last capacitor in the capacitor string being at a high voltage output; a diode string comprising a plurality of diodes arranged in series, the anode of a first diode in the diode string being connected to the lower voltage and the cathode of a last diode in the diode string being connected to the high voltage output, the first end being electrically connected to a midpoint of the capacitor string, and the second end being electrically connected to the midpoint of the diode string; a high voltage shield disposed at the positive end of the last capacitor and electrically connected to the high voltage output; A printed circuit board having wherein the shielding includes wide traces disposed on one or more layers of the printed circuit board.

2. 2. The high voltage power supply of claim 1, further comprising a low voltage shield disposed at the negative end of the first capacitor and electrically connected to the lower voltage.

3. 3. The high voltage power supply of claim 2, wherein the high voltage shield and the low voltage shield each include signal traces having a length between 40 mm and 100 mm and a width between 3 mm and 10 mm.

4. 3. The high voltage power supply of claim 2, wherein the high voltage shield and the low voltage shield are disposed on the same side of the printed circuit board as the capacitor string.

5. 3. The high voltage power supply of claim 2, wherein the high voltage shield and the low voltage shield are disposed on opposite sides of the printed circuit board from the capacitor string.

6. 2. The high voltage power supply of claim 1, further comprising a mid-shield disposed between two adjacent capacitors in the capacitor string and electrically connected to a trace connecting the two adjacent capacitors.

7. The high voltage power supply of claim 6 , wherein the mid-shield is disposed at the mid-point of the capacitor string.

8. 7. The high voltage power supply of claim 6, further comprising a second mid shield disposed between two different adjacent capacitors in the capacitor string.

9. 2. The high voltage power supply of claim 1, wherein the difference between the voltage across the first capacitor and the voltage across the last capacitor is less than 10% of the voltage across the last capacitor.

10. 1. A high voltage power supply, Primary winding, a plurality of secondary windings, each having a first end and a second end; and A printed circuit board, a plurality of low voltage doubler circuits arranged in series to form a high voltage doubler circuit having a lower voltage at a first end and a high voltage output at a second end, each low voltage doubler circuit having a positive end and a negative end and comprising a first capacitor and a second capacitor arranged in series and a first diode and a second diode arranged in series, a positive end of the first capacitor electrically connected to a cathode of the first diode and comprising the positive end of the low voltage doubler circuit, a negative end of the second capacitor electrically connected to an anode of the second diode and comprising the negative end of the low voltage doubler circuit, a first end of each secondary winding electrically connected to a trace connecting the first capacitor and the second capacitor, and a second end of each secondary winding electrically connected to a trace connecting the first diode and the second diode; a high voltage shield disposed at the second end of the high voltage doubler circuit and electrically connected to the high voltage output; A printed circuit board having wherein the shielding includes wide traces disposed on one or more layers of the printed circuit board.

11. 11. The high voltage power supply of claim 10, further comprising a low voltage shield disposed at the first end of the high voltage doubler circuit and electrically connected to the lower voltage.

12. 12. The high voltage power supply of claim 11, wherein the high voltage shield and the low voltage shield each include signal traces having a length between 40 mm and 100 mm and a width between 3 mm and 10 mm.

13. 12. The high voltage power supply of claim 11, wherein the high voltage shield and the low voltage shield are located on the same side of the printed circuit board as the high voltage doubler circuit.

14. 12. The high voltage power supply of claim 11, wherein the high voltage shield and the low voltage shield are disposed on opposite sides of the printed circuit board from the high voltage doubler circuit.

15. The high voltage power supply of claim 10, further comprising a mid-shield disposed between two adjacent low voltage doubler circuits.

16. 16. The high voltage power supply of claim 15, wherein the mid shield is disposed at a midpoint of the high voltage doubler circuit.

17. 16. The high voltage power supply of claim 15, further comprising a second mid shield disposed between two different adjacent low voltage doubler circuits.

18. 11. The high voltage power supply of claim 10, wherein a difference between a voltage across a first low voltage doubler circuit located closest to the first end and a voltage across a last low voltage doubler circuit located closest to the second end is less than 10% of the voltage across the last low voltage doubler circuit located closest to the second end.

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