Permanent electromagnet array

Abstract

To provide an apparatus and a method for attracting ferrous objects with a programmable permanent electromagnet array.SOLUTION: A permanent electromagnet array 300 includes one or more of a plurality of parallel-arranged permanent electromagnets 140A, 140B having a common length and a planar pole piece 234 coupled to a first end of the plurality of permanent electromagnets, each of which includes a first end and a second end opposite the first end.SELECTED DRAWING: Figure 3A

Description

[Technical field]

[0001] This application claims priority from U.S. Provisional Patent Application No. 62 / 849,204, entitled "Permanent Electromagnet," filed May 17, 2019 (Docket No. ASP0011PV), which is incorporated by reference herein for all purposes.

[0002] This application is directed to apparatus and methods relating to permanent electromagnets. In particular, this application is directed to an apparatus and method for attracting ferrous objects using a programmable permanent electromagnet array. [Background technology]

[0003] A magnet is a material or object that generates a magnetic field. This field is invisible, but it is responsible for a magnet's most notable property: its ability to attract other ferromagnetic materials, such as iron. A permanent magnet is an object made of a magnetically hard material that can be magnetized to generate its own persistent magnetic field. Materials that can be magnetized are also materials that are strongly attracted to magnets and are called ferromagnetic. These include the elements iron, nickel, and cobalt, some alloys of rare earth metals, and some natural minerals, such as lodestone. Ferromagnetic materials are the only materials that are strongly attracted to magnets to be generally considered magnetic, while all other substances respond weakly to magnetic fields by one of several other types of magnetism.

[0004] Ferromagnetic materials can be divided into magnetically "soft" materials, such as annealed iron, which can be magnetized but do not tend to remain magnetized, and magnetically "hard" materials, which tend to remain magnetized. Permanent magnets are made from "hard" ferromagnetic materials, such as alnico, aluminum, nickel, and cobalt alloys, alloys of neodymium and other rare earth materials, and ferrites, which undergo special treatment with strong magnetic fields during manufacture to align their internal microcrystalline structure and make them very difficult to demagnetize. To demagnetize a saturated magnet, a certain magnetic field must be applied. This threshold depends on the coercivity of the respective material. "Hard" materials have high coercivity, and "soft" materials have low coercivity. The overall strength of a magnet is measured by its BH product. The strength of local magnetization of a material is measured by its magnetizability.

[0005] An electromagnet consists of a coil of wire that acts as a magnet when electric current passes through it and ceases to be a magnet when the current stops. The coil is often wound around a core of a "soft" ferromagnetic material, such as mild steel, which greatly enhances the magnetic field it generates. Summary of the Invention [Means for solving the problem]

[0006] The present application aims to solve the disadvantages of the prior art. According to an embodiment of the present application, a permanent electromagnet array can be provided. The permanent electromagnet array includes a plurality of permanent electromagnets of a common length arranged in parallel and a planar pole piece coupled to a first end of the plurality of permanent electromagnets. Each permanent electromagnet includes a first end and a second end opposite the first end.

[0007] According to another embodiment of the present application, a permanent electromagnet array may be provided, the permanent electromagnet array including a plurality of pole pieces and a plurality of permanent electromagnets of a common length, each permanent electromagnet including a first and second end, the permanent electromagnets being linearly disposed end to end between and coupled to a pair of pole pieces.

[0008] According to yet another embodiment of the present application, an apparatus may be provided. The apparatus includes one or more of an electric permanent coil configured to provide a current pulse, an energy storage device, an H-bridge driver circuit coupled to the electric permanent coil and the energy storage device, and a control circuit coupled to a switching element. The H-bridge driver circuit includes a switching element including an insulated gate thyristor configured to receive the current pulse from the energy storage device and selectively drive the current pulse in a first direction or a second direction opposite the first direction relative to the electric permanent coil. The control circuit is configured to select the first and second directions. A gate drive voltage of each switching element is optically isolated between the control circuit and the switching element. [Brief description of the drawings]

[0009] [Figure 1A] FIG. 1 illustrates a hard magnetic core according to the prior art. [Figure 1B] FIG. 1 is a diagram showing a current-carrying coil winding according to the prior art. [Figure 1C] FIG. 1 shows a permanent electromagnet charged by a unipolar current pulse passing through a coil according to the prior art. [Figure 1D] FIG. 1 shows a permanent electromagnet demagnetized by an AC pulse passing through the coil according to the prior art. [Figure 1E] FIG. 1 illustrates magnetic flux neutralized by a current in a coil according to the prior art. [Figure 1F] FIG. 1 illustrates the net flux reduction according to the prior art. [Figure 1G] FIG. 2 illustrates a permanent electromagnet that has been demagnetized in accordance with an embodiment of the present application. [Figure 2A] FIG. 1 shows a simple electromagnet according to the prior art. [Figure 2B] FIG. 1 illustrates a simple current-carrying electromagnet according to the prior art. [Figure 2C] FIG. 1 illustrates a zero current biased electromagnet according to the prior art. [Figure 2D] FIG. 1 illustrates a biased electromagnet with magnetic flux cancellation according to the prior art. [Figure 2E] FIG. 1 shows a hard magnet and a semi-hard magnet with aligned poles according to the prior art. [Figure 2F] FIG. 1 shows a hard magnet and a semi-hard magnet with opposite poles according to the prior art. [Figure 2G] FIG. 1 shows a permanent electromagnet charged by a current pulse according to the prior art. [Figure 2H] FIG. 1 shows a permanent electromagnet demagnetized by alternating pulses according to the prior art. [Figure 3A] FIG. 1 illustrates an array of side-by-side permanent electromagnets with alternating polarity for short-range attractive forces, according to an embodiment of the present application. [Figure 3B] FIG. 1 illustrates an array of side-by-side permanent electromagnets with matching polarity for longer range attractive forces, according to an embodiment of the present application. [Figure 3C] FIG. 2 illustrates a demagnetized aligned permanent electromagnet array according to an embodiment of the present application. [Figure 3D] FIG. 1 is a magnetic flux diagram of short-range attractive forces according to an embodiment of the present application. [Figure 3E] FIG. 13 is a magnetic flux diagram for a longer range attractive force according to an embodiment of the present application. [Figure 4A] FIG. 1 illustrates an end-on-end permanent electromagnet array for short-range attractive forces, according to an embodiment of the present application. [Figure 4B] FIG. 1 illustrates an end-on-end permanent electromagnet array for longer range attraction, according to an embodiment of the present application. [Figure 4C] FIG. 2 illustrates a demagnetized end-on-end permanent electromagnet array according to an embodiment of the present application. [Figure 4D] FIG. 1 is a magnetic flux diagram of short-range attractive forces according to an embodiment of the present application. [Figure 4E] FIG. 13 is a magnetic flux diagram for a longer range attractive force according to an embodiment of the present application. [Figure 5A] FIG. 2 is a block diagram of a current pulse driver according to an embodiment of the present application. [Figure 5B] FIG. 2 is a block diagram illustrating a current pulse driver charging stage according to an embodiment of the present application. [Figure 5C] FIG. 13 is a block diagram illustrating discharging a capacitor of a permanent electromagnet array in a forward direction through a coil according to an embodiment of the present application. [Figure 5D] FIG. 13 is a block diagram illustrating discharging a capacitor of a permanent electromagnet array in a reverse direction through a coil according to an embodiment of the present application. [Figure 5E] FIG. 1 is a first block diagram of a permanent electromagnet array current pulse driver with multiple coils according to an embodiment of the present application. [Figure 5F] FIG. 13 is a second block diagram of a permanent electromagnet array current pulse driver with multiple coils according to an embodiment of the present application. [Figure 6A] FIG. 2 is a magnetization diagram using repeated current pulses according to an embodiment of the present application. [Figure 6B] FIG. 13 is a demagnetization diagram using alternating single current pulses according to an embodiment of the present application. [Figure 6C] FIG. 2 illustrates an exemplary magnetization timing diagram according to an embodiment of the present application. [Figure 6D] 1A-1C are magnetization diagrams showing both hard and semi-hard magnetic materials according to examples of the present application. [Figure 6E] FIG. 2 is a magnetization diagram of a soft magnetic material according to an embodiment of the present application. [Figure 7A] FIG. 1 illustrates a permanent electromagnet array with serpentine layered coils according to an embodiment of the present application. [Figure 7B] FIG. 2 illustrates a detail of a uniform meandering coil layer according to an embodiment of the present application. [Figure 7C] FIG. 2 illustrates a detail of an odd meander coil layer according to an embodiment of the present application. [Figure 7D] FIG. 13 illustrates details of a spiral coil layer interconnection according to an embodiment of the present application. [Figure 7E] FIG. 2 is a diagram showing details of a spiral coil layer according to an embodiment of the present application. [Figure 7F] FIG. 1 illustrates a top view of a permanent electromagnet array for high force and short range attractive force, according to an embodiment of the present application. [Figure 7G]FIG. 1 illustrates a top view of a permanent electromagnet array for lower force and longer range attractive force according to an embodiment of the present application. [Figure 7H] FIG. 2 illustrates a top view of a demagnetized permanent electromagnet array, according to an embodiment of the present application. [Figure 8A] FIG. 1 illustrates an end-on-end two-dimensional permanent electromagnet array polarized for short-range attractive forces, according to an embodiment of the present application. [Figure 8B] FIG. 2 illustrates a side view of an end-on-end permanent electromagnet array and magnetic flux lines according to an embodiment of the present application. [Figure 8C] FIG. 1 illustrates an end-on-end two-dimensional permanent electromagnet array polarized for longer range attractive forces, according to an embodiment of the present application. [Figure 8D] FIG. 1 illustrates a side view of an end-on-end permanent electromagnet array programmed for longer range attractive forces and magnetic flux lines, according to an embodiment of the present application. [Figure 9A] 1 is a flow chart illustrating a first coil magnetization process according to an embodiment of the present application. [Figure 9B] 11 is a flow chart illustrating a second coil magnetization process according to an embodiment of the present application. [Figure 10] 1 is a flow chart illustrating a coil demagnetization process according to an embodiment of the present application. [Figure 11A] FIG. 1 illustrates a side view of a magnetometer installation for a side-by-side array, according to an embodiment of the present application. [Figure 11B] FIG. 2 illustrates a bottom view of a magnetometer installation according to an embodiment of the present application. [Figure 11C] FIG. 2 illustrates a side view of a thickness mode magnetic flux sensor for an end-to-end array according to an embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The permanent electromagnet array of the present application, described in detail below, can be used in three distinct states.

[0011] Demagnetization - The permanent magnet array can be turned off by demagnetizing the permanent magnets. The result is that there are no magnetic poles at all - no north or south, no attractive or repulsive forces at all.

[0012] Short Distance, High Grip - In this configuration, all of the magnetic flux lines follow a short, concentrated path through the ferromagnetic material of the target to the adjacent pole of opposite polarity. Almost all of the magnetic flux passes through the target material, maximizing grip.

[0013] Longer Distance, Lower Grip Force - An array of similar poles (e.g. North-North-North, etc.) does not create a concentrated "short circuit" for the magnetic field lines to follow, so they take a longer path out and around, as with a conventional bar magnet. Because the field lines are not concentrated in an area, the amount of magnetic flux that can flow through an object at long distances is still a fraction of the total magnetic flux, but it can reach much farther than a short distance configuration, and therefore begin to affect objects at long distances.

[0014] There is a need for permanent electromagnets that can be switched between short-range and long-range attractive modes. Moreover, permanent electromagnet arrays have many advantages over the current state of the art, as described below.

[0015] First, two or more permanent electromagnets can be combined in the volume of a single pole piece and magnet combination. This advantage of double magnetic flux density is maintained as the size of the permanent electromagnet array increases. A permanent electromagnet array provides an increased total attractive force per unit of volume and weight compared to a single permanent electromagnet. The attractive force between a polarized permanent electromagnet and a ferrous surface acts to attract the magnet and ferrous surface together.

[0016] Second, the permanent electromagnet array can be electrically switched to shift between being optimized for short-range attraction and being optimized for long-range attraction by changing the polarity of one or more permanent electromagnets in the array. The polarization of a permanent electromagnet is defined by a north pole and a south pole, with magnetic flux traveling from the south pole to the north pole.

[0017] Third, permanent electromagnet arrays can be fabricated at any scale that allows the total attractive force to be increased linearly.

[0018] Fourth, even when the disclosed permanent electromagnet arrays scale in one or two dimensions, the array assembly does not require additional thickness in the direction of attraction, thus saving weight and size over inferior approaches such as those shown in the following Figures 2A through 2G, which require simultaneous scaling in three dimensions.

[0019] Fifth, permanent electromagnet arrays continue to exhibit the same beneficial properties as individual permanent electromagnets: a) they can be polarized in either of two magnetic configurations, b) they can be completely demagnetized, allowing the attracted iron mass to detach from the permanent electromagnet array and move freely, and c) the polarization state of the permanent electromagnets can be maintained without the need for additional current beyond the initial polarization or demagnetization pulses.

[0020] Further advantages and differentiations are illustrated in the following diagram and accompanying description.

[0021] Referring now to FIG. 1A, a diagram showing a hard magnetic core 100 according to the prior art is shown. FIG. 1A shows a perspective view of a cylindrical magnet core 104 made from a combination of magnetically hard materials including Alnico and rare earths including Neodymium or Samarium Cobalt. The magnet is a magnetically hard magnet core polarized with a magnetic charge. The magnet core 108 does not necessarily have to be cylindrical, but for consistency in this application, it is generally shown as a cylindrical core. For example, the magnetic core 104 can also be many possible prismatic shapes. The magnet core 104 has magnetic properties as shown in FIG. 6D.

[0022] The magnetized magnet core 104 has a north pole 116 and a south pole 120 and has an associated magnetic field. The magnetic field can be visualized using magnetic flux lines 108, also called magnetic field lines. The magnetic flux lines 108 show the path of the magnetic flux. Magnetic flux is the net number of magnetic flux or magnetic field lines 108 passing through a surface, that is, the number passing in one direction minus the number passing in the opposite direction. In the associated figures, only one magnetic flux line 108 is shown for each magnetic field for clarity. It should be understood that any number of magnetic flux lines 108 may actually be present and that a single magnetic flux line 108 may represent any number of magnetic flux lines 108.

[0023] All magnetic flux lines 108 associated with a magnetized magnet core 104 (compared to a demagnetized magnet core 104, which has no magnetic flux lines 108) have a common magnetic flux direction 112. Within the magnet core 104 itself, the magnetic flux directions 112 proceed from the south pole 120 to the north pole 116. Away from the magnet core 104, the same magnetic flux lines 108 proceed in opposite directions (i.e., shown in either a clockwise or counterclockwise direction) such that the magnetic flux directions 112 of the same magnetic flux lines 108 are consistent.

[0024] Referring now to FIG. 1B, a diagram showing an energized coil winding 130 according to the prior art is shown. FIG. 1B shows an electric coil 134 that may be formed from wire (e.g., copper wire), from partial magnetic loops (FIGS. 7A-7C), or from conductive traces on stacked circuit boards or layers with interconnected traces (FIGS. 7D and 7E). The coil 134 is further shown in the process of passing a current in the direction of the arrow 138. According to the right-hand rule known to those skilled in the art, the current shown creates magnetic flux field lines 108 in the direction 112 shown. In further figures, where an arrow indicates the direction of current flow in the coil 134, it should be understood that there is an equal current exiting the other lead of the coil 134, even if not shown in the figure.

[0025] 1C, a diagram is shown illustrating a permanent electromagnet being charged by a unipolar current pulse through a coil 140, in accordance with the prior art. FIG 1C shows a magnetically hard core 104 inserted into an electric coil 144 that is energized by a strong discharge pulse 144 and the resulting magnetic polarization of the magnetic core 104. Furthermore, the resulting polarization lines and magnetic flux lines 108 remain after the electric pulse 144 is completed. The result is a charged permanent electromagnet 140.

[0026] 1D, there is shown a diagram illustrating a permanent electromagnet that has been demagnetized by AC pulses passed through a coil 150, in accordance with the prior art. FIG 1D illustrates a permanent electromagnet that has received a train of demagnetizing AC pulses 154, thereby demagnetizing the magnetic polarity of the core 104 and resulting in no useful magnetic flux lines.

[0027] Referring now to FIG. 1E, a diagram is shown illustrating magnetic flux being neutralized by current in a coil 160, in accordance with the prior art. FIG. 1E shows a permanent magnet core 104 disposed inside a coil 134 carrying a continuous current 164 that creates a coil-induced magnetic flux that is directly opposite the polarity of the permanent magnet, but not strong enough to reverse the polarity of the magnet. The resulting permanent magnet 160 will attract ferrous materials when the current is zero. However, as shown in FIG. IF, a continuous current 164 must be applied to counteract the magnet's magnetic field. Eventually, this reduces the net magnetic flux of the combination until it approaches zero enough to eject ferrous objects.

[0028] 1F, a diagram illustrating the reduction in net magnetic flux 170 according to the prior art is shown. Figure 1F shows how the magnetic flux 174 of the permanent magnet 160 can be gradually neutralized by increasing the coil current 178 until the net magnetic flux 174 of the magnet and coil combination 160 becomes zero.

[0029] Referring now to Figure 1G, a diagram illustrating a demagnetized 180-permanent electromagnet is shown, according to an embodiment of the present application. Figure 1G shows the magnet core 104 and coil 134 in a demagnetized 180-state. Thus, the magnet and coil have no magnetic field 184, and no magnetic flux lines 108 are shown. In this state, the demagnetized permanent electromagnet 180- exerts no magnetic force on other objects.

[0030] Referring now to FIG. 2A, a diagram showing a simple electromagnet 200 according to the prior art is shown. FIGS. 2A-2H show prior art permanent electromagnet configurations that are actually used to attract ferrous objects. However, all of these configurations perform less well than the embodiments disclosed herein. FIG. 2A shows a magnetically soft yoke 208 with one end inserted into the coil 134. This configuration comprises a typical electromagnet. As shown, with no current flowing, this electromagnet produces no magnetic flux and is therefore shown without any attraction to the iron mass or ferromagnetic surface 204. The iron mass or ferromagnetic surface 204 is made from an iron alloy that is attracted to magnets.

[0031] Referring now to Figure 2B, a diagram is shown illustrating a simple energized electromagnet 220 according to the prior art. Figure 2B shows a current 164 passing through a magnetically soft yoke 208 and a ferromagnetic surface 204, which is attracted in a direction that reduces two air gaps 224 (one is shown for clarity) that the magnetic flux lines 108 must cross. The strength of the magnetic attraction increases as the air gap decreases and is greatest when the electromagnet 220 is in direct contact with the ferromagnetic surface 204. During product and industrial use, the electromagnet 220 must remain powered with a constantly flowing current 164 to maintain its magnetic attraction to the ferromagnetic surface 204.

[0032] Referring now to Figure 2C, a diagram showing a prior art electromagnet biased with zero current 230 is shown. Figure 2C shows a magnetically charged permanent electromagnet 230 paired with a soft iron pole piece 234. The ferromagnetic surface 204 is attracted even with zero current 238. The pole piece or yoke is a magnetically soft ferrous material having the magnetic properties illustrated and described with reference to Figure 6E and is attached to one or more poles of the permanent electromagnet to provide a low reluctance path for magnetic flux to flow through the magnetic circuit.

[0033] Referring now to Figure 2D, a diagram is shown illustrating a biased electromagnet with magnetic flux cancellation 240 in accordance with the prior art. Figure 2D shows a permanent electromagnet 240 with a coil current 244 flowing in a direction that creates an opposing magnetic flux direction from the permanent magnet. At a particular level of current 244, shown in Figure 1F, the opposing magnetic flux in the coil 134 neutralizes the magnet's magnetic flux, resulting in no magnetic attraction.

[0034] Referring now to FIG. 2E, a diagram showing hard and semi-hard magnets with aligned poles 250 according to the prior art is shown. FIG. 2E shows a permanent electromagnet configuration 250 which requires magnets of two different material types attached by pole pieces at either end 234A, 234B. Inside the coil 134 is an Alnico magnet 254A, which is less magnetically hard than the neodymium alloy magnet on the left 254B, which may be of rare earth construction. The magnetic properties of the two types of magnets are shown in FIG. 6D. When a pulse of current is generated in the direction 144 shown in FIG. 2E, both magnets 254A, 254B adopt matching polarities and the combined magnetic flux passing through the ferromagnetic surface 204 is correspondingly stronger.

[0035] Referring now to Figure 2F, a diagram is shown illustrating a hard magnet and a semi-hard magnet with poles on opposite sides 260 in accordance with the prior art. Figure 2F shows the same permanent electromagnet assembly as shown in Figure 2E, but with a current pulse 144 initiated in the opposite direction. This reverses the polarity of the permanent electromagnet, effectively shorting out the magnetic flux from the magnetically hard neodymium magnet 254B on the left. With no magnetic flux remaining across the air gap 224, there is no attraction with the ferromagnetic surface 204.

[0036] Referring now to Figure 2G, a diagram is shown showing a permanent electromagnet being charged by a current pulse 270, in accordance with the prior art. Figure 2G shows a magnetically charged permanent electromagnet and pole piece 234 shown to attract a ferromagnetic surface 204. This is considered the state of the art existing immediately prior to Applicant's inventive step beginning with Figure 3.

[0037] Referring now to FIG. 2H, a diagram is shown showing a permanent electromagnet demagnetized by alternating pulses 280 according to the prior art. FIG. 2H shows the same assembly as shown in FIG. 2G, but with alternating demagnetizing pulses 154 applied to the electric permanent coil 134, thus eliminating the attraction to the ferromagnetic surface 204. The disadvantage of FIGS. 2G and 2H is the need to have a long pole piece 234 to efficiently transfer the magnetic flux to and through the ferromagnetic surface 204. The disadvantage of having a long pole piece 234 is that its resistance to the magnetic flux is slight, resulting in a large leakage of the magnetic flux to the pole of the opposing permanent electromagnet, resulting in a lower level of magnetic flux moving through the ferromagnetic surface 204, and therefore a lower level of magnetic attraction to the surface 204. The long pole piece 234, in short, disadvantageously reduces the strength of the magnetic attraction and increases the weight of the permanent electromagnet design.

[0038] Now referring to FIG. 3A, a diagram showing a side-by-side permanent electromagnet array with alternating polarity for short-range attractive force 300 according to an embodiment of the present application is shown. FIGS. 3A-3E show one form of a preferred embodiment of the present application. FIG. 3A shows two side-by-side permanent electromagnets 140A, 140B coupled to a two-piece permanent electromagnet array 300 via a common pole piece 234. Compared to FIG. 2G, since two permanent electromagnets 140A, 140B are used, the density of magnetic flux lines and the attractive force to the ferromagnetic surface 204 is about twice as large as the magnets in FIG. 2G. This alternating magnetic pole configuration is optimized for short-range attractive force. The attachment of the magnet core to the pole piece 234 in all permanent electromagnet arrays can be achieved by a combination or separate attachment mechanism of magnetic attraction, solder bonding, and adhesive bonding.

[0039] Each permanent electromagnet includes a magnetically hard material portion and a conductor helically wound around the hard material portion, the conductor including one and a plurality of stacked layers of wire, each layer including one of a plurality of planar full loops of conductive trace bonded to an insulator film around each hard material portion and a plurality of planar and serpentine half loops of conductive trace bonded to an insulator film around each hard material portion.

[0040] Referring now to FIG. 3B, the figure shows a side-by-side permanent electromagnet array with matching polarity for longer range attractive force 320 according to an embodiment of the present application. FIG. 3B shows the same side-by-side permanent electromagnets as FIG. 3A, but now the permanent electromagnets 140A, 140B are polarized in the same S-N direction by the current pulses 144A, 144B shown. In this magnetic configuration, the magnetic flux lines from the permanent electromagnet array are spread out further, providing better attractive performance at longer ranges than the alternating polarity permanent electromagnet array 300 configuration shown in FIG. 3A. In contrast, at shorter ranges, when the array is polarized as in FIG. 3B, the magnetic flux lines must pass through a larger total air gap 244 around the body of the permanent electromagnets 140A, 140B reducing the short range magnetic flux and attractive force, resulting in a lower attractive force than the configuration of FIG. 3A. Thus, a permanent electromagnet that can be switched between short and long range attractive modes is needed.

[0041] 3C, a diagram illustrating a demagnetized side-by-side permanent electromagnet array 340 is shown, according to an embodiment of the present application. FIG 3C shows both permanent electromagnets 140A, 140B being demagnetized by alternating demagnetizing currents 154A, 154B, thereby rendering the permanent electromagnet array 340 free of magnetic flux lines that engage with, and thereby attract, the ferromagnetic surface 204.

[0042] Referring now to Figure 3D, there is shown a magnetic flux diagram of a short-range attractive force 350 according to an embodiment of the present application. Figure 3D shows a one-dimensional four permanent electromagnet array with alternating north poles 116 and south poles 120 optimized for short-range, high-force attractive forces.

[0043] The short-range attractive force is defined herein as occurring at a distance of the air gap 224 from contact to the maximum separation distance. The nominal attractive force distance D2 358 of the alternately polarized magnets is equal to D1 354, the distance between the centers of the magnets. The maximum separation distance for the short-range attractive force is the distance D2 358, where D2 358 is equal to or less than the distance D1 354 between the central axes of the permanent electromagnets 140. In one embodiment, the short-range attractive force may be up to about 0.4 centimeters from contact. In the illustrated configuration, the permanent electromagnet array 350 exerts a short-range attractive force 304 on the ferromagnetic surface 204. To achieve the short-range object attraction configuration, each permanent electromagnet 140 is oppositely charged relative to its nearest neighboring permanent electromagnet 140. This is also illustrated in FIG. 7F for an exemplary 2×4 magnet configuration of the permanent electromagnet array. Every first, third, fifth, etc. magnet core 104 in the first row and every second, fourth, sixth, etc. magnet core 104 in the second row is charged with a north pole 116 facing the ferrous object surface 204. Every second, fourth, sixth, etc. magnet core 104 in the first row and every first, third, fifth, etc. magnet core 104 in the second row is charged with a south pole 120 facing the ferromagnetic surface 204. This alternating pattern of polarity of the magnet cores 104 provides a maximum number of magnetic flux lines 108 with a correspondingly short return path, thus limiting the range of attraction to the ferromagnetic surface 204. The magnetic flux direction 112 is from the south pole 120 to the north pole 116, and since adjacent magnet cores 104 are oppositely polarized, the magnetic flux return path is very short.

[0044] 3E, there is shown a magnetic flux diagram of a longer range attractive force 360 ​​according to an embodiment of the present application. FIG 3E shows a one-dimensional four permanent electromagnet array, where each of the aligned permanent electromagnets 140 has the same polarization direction, forming an array optimized for longer range attractive force.

[0045] Longer range attractive forces are generally defined herein as short range attractive forces to a maximum separation distance. The nominal attractive force distance D2 368 for the long range attractive force configuration is D3 364, which is equal to the dimension across the permanent electromagnet array 360. The maximum separation distance for longer range attractive forces is distance D2 368, which is equal to or less than distance D3 364, which is equal to the dimension across the permanent electromagnet array 360. In one embodiment, the longer range attractive force can be from about 0.4 centimeters to about 4 centimeters. In the illustrated configuration, the permanent electromagnet array 360 exerts a longer range attractive force 308 on the ferromagnetic surface 204. To achieve the longer range object attractive force configuration, each magnet 104 is charged identically to the magnets 104 immediately adjacent to it. This is also illustrated in FIG. 7G for an exemplary 2×4 permanent electromagnet array 300 configuration. All magnet cores 104 in the first and second rows are charged with the north pole 116 facing the ferromagnetic surface 204. This identical pattern of charge on the magnet cores 104 provides the longest magnetic flux lines 108 from the multiple magnet cores 104 with a correspondingly long return path. Because the magnetic flux direction 112 is from the south pole 120 to the north pole 116 and adjacent magnet cores 104 are similarly polarized, the magnetic flux return path is longer than in the short range attraction configuration of Figures 3A and 3D.

[0046] Referring now to Figure 4A, a diagram is shown illustrating an end-on-end permanent electromagnet array for short-range attraction 400, according to an embodiment of the present application. Figures 4A-4E show another configuration of a preferred embodiment of the present application. Two or more permanent electromagnets 140 are mounted end to end with pole pieces 234 interspersing the permanent electromagnets 140 and covering the ends of each array.

[0047] 4A shows an end-on-end permanent electromagnet array. With alternating magnet polarities as shown, the permanent electromagnet array 400 is optimized for high attractive forces over short distances.

[0048] Referring now to Figure 4B, a diagram showing an end-on-end permanent electromagnet array for longer range attractive forces 420 is shown, according to an embodiment of the present application. Figure 4B shows the same end-on-end arrangement as shown in Figure 4A, but with the polarities of the permanent electromagnets aligned in the same direction. In this arrangement, the longer flux path length of the permanent electromagnet array is optimized for longer range attractive forces.

[0049] 4C, a diagram illustrating a demagnetized end-on-end permanent electromagnet array 440 according to an embodiment of the present application is shown. FIG. 4C shows an end-on-end arrangement of permanent electromagnets in a demagnetized state, where there is no attractive force on the ferromagnetic surface 204.

[0050] Referring now to Figure 4D, a flux diagram of short-range attractive force 450 is shown, according to an embodiment of the present application. Figure 4D shows a four-member permanent electromagnet array with alternating north and south poles optimized for short-range attractive force 304. The embodiment shown in Figure 4D has the same goal of optimized short-range attractive force as the embodiment shown in Figures 3A and 3D, but achieves this with a different permanent electromagnet 140 and pole piece 234 configuration.

[0051] Referring now to Figure 4E, a magnetic flux diagram of a longer range attractive force 460 is shown according to an embodiment of the present application. Figure 4E shows a four-piece permanent electromagnet array with stacked serial magnet polarities as shown. This arrangement is optimized for a longer range attractive force 308.

[0052] Referring now to FIG. 5A, a block diagram of a current pulse driver 500 is shown, according to an embodiment of the present application. FIG. 5A shows an H-bridge current pulse driver circuit in which a current pulse is sent forward or backward through a coil 524 of a permanent electromagnet upon command. An H-bridge configuration of semiconductor switches is the preferred configuration for directing current in either direction through a load by selecting switches that are open or closed. It will be understood that the permanent electromagnet 140 includes a magnetic core 104 and a coil 134, however, the magnetic core 104 is not shown for clarity in order to better illustrate the current pulse generating circuitry, but not the magnetic field and polarity.

[0053] The current pulse driver 500 may include a charger 508, an energy storage device (shown as a capacitor 512), a control circuit 516, and one or more switches (shown as a thyristor H-bridge 504). More thyristor H-bridges 504 may include more coils 524 (each coil 524 may be associated with one permanent electromagnet 140). In other embodiments, the thyristor H-bridge 504 may not be used, and instead, a hardware switch or actuator, a MOSFET, or an IGBT may be used to provide the switching function. Although only one coil 524 is shown in Figures 5A-5F, it should be understood that the permanent electromagnet array of the present application requires at least two permanent electromagnets, and therefore at least two coils 524. A single coil 524 is shown simply to clarify the components required for charging and discharging purposes in Figures 5A-5D, and Figures 5E and 5F represent a more accurate view of the permanent electromagnet array.

[0054] Charger 508 may be a power supply that functions to charge capacitor 512 as directed by a charger enable / disable signal 544 from control circuitry 516. In a preferred embodiment, charger 508 may be a switching DC power supply, such as a buck-boost power supply. In other embodiments, charger 508 may be a different form of power supply, including a linear power supply or a different type of switching power supply.

[0055] The capacitor 512 may be charged to a predetermined voltage by a charger 508. The manner in which it is discharged through the multiple switches or thyristor H-bridge 504 may determine the polarity (or lack of polarity in the case of a demagnetized permanent electromagnet 140, as shown in Figures 3C and 4C) of each permanent electromagnet 140. In a preferred embodiment, the capacitor 512 may be a 50 uF capacitor. Each thyristor H-bridge 504 may include one coil 524 / (and magnet core 104) and four switches 528, 532, 536, 540. To control whether current flows through the coil 524 and the direction of the current, the switches are opened and closed in pairs, which affects the polarity of the permanent electromagnet 140. The switches 528 / 540 may be opened and closed simultaneously, and the switches 532 / 536 may be opened and closed simultaneously. The operation of the switches is described in more detail with respect to Figures 5B-5F.

[0056] The control circuitry 516 receives commands 520 and in response controls charger enable / disable 544 to the charger 508 and control 548 to each of the switches 528, 532, 536, 540. The commands 520 may be hardware switches output from a computer, a computer application, a command from a graphical user application (GUI) associated with the computer and selected by a user, or a control activated by a user. The commands 520 may specify a number of actions to be taken by the current pulse driver 500, including enabling short-range attraction, enabling long-range attraction, and demagnetizing the permanent electromagnet 140. Other commands 520 may be utilized, including, but not limited to, specifying the voltage level to which the charger 508 should charge the capacitor 512, specifying the operation of a particular thyristor H-bridge 504, or specifying the open or closed position of a particular switch 528, 532, 536, 540. The control circuitry 516 can be implemented as any form of known control function including processor / memory, microcontroller, field programmable gate array (FPGA), programmable logic, state machine, pure hardware, or any combination of hardware / software / applications.

[0057] Stated another way, the H-bridge current pulse driver may include an electrically permanent coil configured to provide a current pulse, an energy storage device, an H-bridge drive circuit coupled to the electrically permanent coil and the energy storage device, and a control circuit coupled to the switching elements. The H-bridge driver circuit includes switching elements including insulated gate thyristors configured to receive the current pulse from the energy storage device and selectively drive the current pulse in a first direction or a second direction opposite the first direction relative to the electrically permanent coil. The control circuit is configured to select between the first and second directions. A gate drive voltage for each switching element is optically isolated between the control circuit and the switching element.

[0058] 5B, a block diagram illustrating a current pulse driver charging phase of a permanent electromagnet 550 according to an embodiment of the present application is shown. FIG. 5B illustrates an H-bridge current pulse driver circuit during the charging phase of the storage capacitor 512.

[0059] The charging stage 550 can be used in connection with changing the operating mode of the current pulse driver 500 (e.g., from short-range attraction to long-range attraction, or from long-range attraction to short-range attraction), or as one of many charging steps (FIG. 10) required for the degaussing process.

[0060] For the charging phase 550, the control circuit 516 receives a command 520 specifying a new operating mode or a charge capacitor command 554. In one embodiment, the charge capacitor command 554 may specify a voltage level to charge the capacitor 512. The control circuit 516 then enables the charger 556, and the charger 508 charges the capacitor 558. In one embodiment, the charger enable signal 556 may be timed by the control circuit 516 to charge the capacitor 558 to a desired voltage. In another embodiment, the charger 508 may charge the capacitor 558 to a desired voltage in response to receiving a charger enable 556 indication of any duration. During this phase, all switches 528, 532, 536, 540 of all thyristor H-bridges 504 are in an open state since a closed switch may prevent the capacitor 512 from charging.

[0061] 5C, a block diagram illustrating forward discharging of the permanent magnet capacitor through coil 560 is shown according to an embodiment of the present application. FIG. 5C shows the energy storage capacitor 512 discharging a current pulse through switch 1 and switch 4 in the forward direction of coil 524. The discharge steps of FIG. 5C and FIG. 5D show the steps where the permanent magnet 140 is actually polarized to program the permanent magnet array 300 for short-range attraction, long-range attraction, or demagnetization. The steps shown in FIG. 5C are performed after the steps shown in FIG. 5B.

[0062] The discharge sequence for programming the magnetic state into the permanent electromagnet array has the following important characteristics: It should be readily apparent to one skilled in the art that the magnitudes of the values ​​listed will vary depending on design specific conditions and component selection. The individual discharge of the capacitors is a very fast process (discharge times of 25 to 100 microseconds) Capacitors discharge at very high currents (over 250 amps) Discharging a capacitor from very high voltages (over 250 volts)

[0063] The permanent electromagnet array 300 can utilize one or more thyristor H-bridges 504 to control the direction of current to program the permanent electromagnets 140 to a given state. Depending on which switches 528, 532, 536, and 540 are open and which are closed, current flows in one of two directions through the permanent electromagnet coil windings 524, thus programming the corresponding permanent electromagnets 140 (not shown for clarity) to one of two magnetic states (NS or SN). The thyristors 504 may be chosen for their very high power and energy handling characteristics compared to MOSFETs or IGBTs. Once the thyristors 504 are fired / triggered, they allow the current to continue to flow until the flow drops to nearly zero, meaning that the entire capacitor 512 must discharge for any given command to reprogram the permanent electromagnets 140. Because MOSFETs cannot handle large amounts of power, more MOSFETs may be needed to perform the task. However, MOSFETs are advantageously more efficient and more controllable than thyristors 504 (e.g., the discharge of capacitor 512 can be modulated to provide fine current control). This is not a huge advantage for a permanent electromagnet array 300 attraction device that is only attempting to program a single magnetic state into a given permanent electromagnet 140, but could theoretically be more useful if permanent electromagnet array technology were incorporated into some form of electric motor that is optimized for high torque per unit power and operates at moderate rotational or linear speeds but does not need to be constantly energized to maintain zero speed torque.

[0064] The control circuit 516 receives the enable forward current via a coil command 562. In one embodiment, the command 562 may specify which of the switches 528, 532, 536, 540 to open or close. In another embodiment, the control circuit 516 may determine the switch states 528, 532, 536, 540 after receiving the enable forward current via the coil command 562. In response to receiving the enable forward current via the coil command 562, the control circuit 516 first provides a charger disable 566 to the charger 508, thereby stopping the charger 508 from continuing to charge the capacitor 512. In one embodiment, the charger disable 566 results in the charger 508 being disconnected from an input AC or DC power source (not shown), possibly including one or more batteries.

[0065] After disabling the charging of the capacitor 512, the control circuit 516 instructs the thyristor H-bridge 504 to close switches SI and S4 564 (and to keep switches S2 532 and S3 536 open). The same switch activation / deactivation is provided to any other thyristor H-bridges 504 that may be present in the permanent electromagnet array 300. Closing S1 528 and S4 540 causes the capacitor 512 to discharge through both switches S1 528, S4 540, resulting in a forward current through the coil 524 and a corresponding change in magnetization of the permanent electromagnet 140.

[0066] Now referring to FIG. 5D, a block diagram illustrating discharging the capacitor of the permanent magnet in the reverse direction through the coil 570 is shown according to an embodiment of the present application. FIG. 5D shows the energy storage capacitor 512 discharging a current pulse 578 through switch 2 and switch 3 in the reverse direction of the coil 524. The discharge steps of FIG. 5C and 5D provide the steps where the permanent magnet 140 is actually polarized to program the permanent magnet array 300 for short-range attraction, long-range attraction, or demagnetization. The steps shown in FIG. 5D are performed after the steps shown in FIG. 5B (charging capacitor 512).

[0067] The control circuit 516 receives the enable reverse current via the coil command 572. In one embodiment, the command 572 specifies which of the switches 528, 532, 536, 540 to open or close. In another embodiment, the control circuit 516 determines the switch states 528, 532, 536, 540 after receiving the enable reverse current via the coil command 572. In response to receiving the enable forward current via the coil command 572, the control circuit 516 first provides a charger disable 576 to the charger 508, which stops the charger 508 from continuing to charge the capacitor 512. In one embodiment, the charger disable 576 results in the charger 508 being disconnected from an input AC or DC power source (not shown), possibly including one or more batteries.

[0068] After disabling the charging of the capacitor 512, the control circuit 516 instructs the thyristor H-bridge 504 to close switches S2 and S3 574 (and to keep switches S1 528 and S4 540 open). The same switch activation / deactivation is provided to any other thyristor H-bridges 504 that may be present in the current pulse driver 500. Closing S2 and S3 causes the capacitor 512 to discharge via both switches S2 532, S3 536, resulting in a reverse current through the coil 524 and a corresponding change in magnetization of the permanent electromagnet 140.

[0069] 5E, a first block diagram of a permanent electromagnet current pulse driver with multiple coils 580 is shown, according to an embodiment of the present application. There are multiple thyristor H-bridges 504, identified herein as thyristor H-bridge A 504A through thyristor H-bridge N 504N. Each thyristor H-bridge 504 includes switches S1 528, S2 532, S3 536, and S4 540. Thyristor H-bridge A 504A includes switches S1A 528A, S2A 532A, S3A 536A, and S4A 540A. Thyristor H-bridge N 504N includes switches S1N 528N, S2N 532N, S3N 536N, and S4N 540N. Any number of thyristor H-bridges 504 may be present in the current pulse driver 500, 580 and a separate switch control 548 may be provided for each thyristor H-bridge 504. The control circuit 516 provides switch control A 548A to thyristor H-bridge A 504A and switch control N 548N to thyristor H-bridge N 504N.

[0070] Multiple thyristor H-bridges 504 are present for the current pulse driver 580, but the switch controls 548 may differ depending on the mode of operation. For a short-range attraction configuration, some coils 524 may use forward current to program the north pole 116 in one direction, and other coils 524 may use reverse current to program the north pole 116 in the opposite direction. For a longer-range attraction configuration, all coils 524 may use forward current to program the north pole 116 in the same direction.

[0071] 5F, there is shown a second block diagram of a permanent electromagnet current pulse driver with multiple coils 584, according to an embodiment of the present application. FIG 5F shows an H-bridge circuit in which multiple permanent electromagnet coils 524 can have current pulses directed to the coils 524 in either an electrical series or electrical parallel configuration, or individually.

[0072] FIG. 5F shows a preferred embodiment where multiple thyristor H-bridges are present, however only a complete thyristor H-bridge 504 is required. Additional ½ thyristor H-bridges 586 can be provided for each additional coil 524. For clarity, only the last (Nth) ½ thyristor H-bridge 586 is shown, which includes coil 524N and switches 532N and 540N. Any number of ½ thyristor H-bridges 586 can be present in the current pulse driver 584, and individual switch controls 548 can be provided for each thyristor H-bridge 504 or ½ thyristor H-bridge 586. The control circuit 516 provides switch control A 548A to thyristor H-bridge A 504A and switch control N 548N to ½ thyristor H-bridge N 586. The embodiment shown in FIG. 5F does not require switches 528 and 536 for the 1 / 2 thyristor H-bridge 586, which significantly reduces the number of switches required.

[0073] The permanent electromagnet array includes an energy storage device configured to provide current pulses to the plurality of permanent electromagnets to polarize the permanent electromagnets, and an H-bridge coil drive circuit coupled to the energy storage device and configured to selectively route the current pulses to the permanent electromagnets in one of a first direction and a second direction opposite the first direction. The polarity of the permanent electromagnets is determined by the first direction and the second direction. In one embodiment, the H-bridge coil drive circuit is configured to polarize each permanent electromagnet in an opposite direction to a nearest neighboring permanent electromagnet by the received current pulse. In another embodiment, the H-bridge coil drive circuit is configured to polarize each permanent electromagnet in the same direction as a nearest neighboring permanent electromagnet by the received current pulse. In yet another embodiment, the H-bridge coil drive circuit is configured to depolarize each permanent electromagnet, and in response, the plurality of permanent electromagnets are configured to not provide an attractive force to the ferrous surface.

[0074] Referring now to FIG. 6A, a magnetization diagram using repetitive current pulses 600 is shown according to an embodiment of the present application. Although the present application includes an embodiment in which only a single current pulse 144 is used to magnetize the permanent electromagnets 140, in practice, three or four single polarity current pulses 144 are typically used to fully polarize the permanent electromagnets 140 in an array. FIG. 6A shows an embodiment in which four current pulses 144 are used in sequence using a common magnetization direction 606 or 608. Magnetization direction A 606 produces a coil current in a positive direction 610 relative to the coil 524. In these cases, all four pulses are applied to magnetization direction A 606 for a period of time 604. Each of these current 602 pulses charges to a level 612 and then discharges 616 from the capacitor 512 via the switching network and the coil 524. There is a capacitor charging period 614 between the current pulses 144.

[0075] 6B, a demagnetization diagram using an alternating single current pulse 620 is shown according to an embodiment of the present application. To demagnetize the permanent electromagnets 140, decreasing alternating pulses 144 are used to fully depolarize the permanent electromagnets 140 in the array. Depolarizing means applying an alternating current to the permanent electromagnets to reduce or eliminate their magnetic polarity. The number of pulses to sufficiently depolarize the permanent electromagnets 140 so that the attached iron mass or ferromagnetic surface 204 is released is typically between 10 and 40 alternating pulses 144 of decreasing polarity.

[0076] In the illustrated example, a first current 602 pulse is applied to the permanent electromagnet 140 in a demagnetizing direction A 624, generating a coil current in the one or more coils 524 in a positive direction 610. Then, a second current 602 pulse is applied to the permanent electromagnet 140 in a demagnetizing direction B 628, generating a coil current in the one or more coils 524 in a negative direction 630. Typically, this second current pulse 144 is applied using the same (albeit negative) current 602 value. Then, a third current pulse, of a lower current 602 value than the first current pulse 144, is applied to the permanent electromagnet 140 in a demagnetizing direction A 625, generating a coil current in the one or more coils 524 in the positive direction 610. A fourth current pulse, at a lower current 602 value than the second current pulse 144, is then applied to the permanent electromagnet 140 in a demagnetizing direction B 628, producing a coil current in a negative direction 630 in the coil or coils 524. This sequence of alternating pulses continues to decrease the current 602 level until the coils 524 are demagnetized.

[0077] 6C, a diagram illustrating an exemplary magnetization timing 640 is shown, according to an embodiment of the present application. In a preferred embodiment, each current pulse 144 may have a pulse width 642 of about 50 μs in duration, with about 50 milliseconds between pulses 644. As the amplitude of the current pulses 144 decreases (demagnetization according to FIG. 6B), in some embodiments, the time between pulses 644 used to charge the capacitor 512 may decrease accordingly. It should be understood that the timing between the particular pulses 642 and pulses 644 is highly design dependent and may be a function of circuit values, and may differ from that shown in FIG. 6C.

[0078] Now referring to FIG. 6D, a magnetization diagram showing both hard and semi-hard magnetic materials 650 according to an embodiment of the present application is shown. A magnetically hard material such as Neodymium (NdFeB) is compared to a slightly less hard material such as AlNiCo (Aluminum / Nickel / Cobalt). In FIG. 6D, the vertical axis is the magnetic flux density in Tesla and the horizontal axis is the magnetic field strength in Amperes / meter. The hard magnetic materials are materials such as AlNiCo (Aluminum / Nickel / Cobalt) and Neodymium (NdFeB) and are used to manufacture the magnetic core 104 material. In low reluctance applications such as short-range attraction modes where the elements are already in close physical contact with the low reluctance circuit, there should be negligible difference in the grip strength of AlNiCo and NdFeB. For longer range attraction, the energy density of neodymium magnets may be advantageous.

[0079] In either case, as the applied magnetic strength provided by the current pulse 144 through the permanent electromagnet coil 134, 524 increases in the positive direction, the retained magnetic flux density 654 increases in the positive direction and does not decrease as the current decreases. This remains so until the applied magnetic field from the reverse current pulse 144 becomes sufficiently negative to reverse the retained magnetic field of the magnetic core to negative, where it remains negative until the external magnetic field is again pulsed sufficiently positive. As one skilled in the art will appreciate, in addition to providing a high current pulse 144 to the permanent electromagnet coil 134, 524 to reverse the polarization of the permanent electromagnet 140 to positive or negative, applying a train of decreasing alternating current pulses 144 will reduce the magnetic flux of the permanent electromagnet to zero.

[0080] Referring now to FIG. 6E, a magnetization diagram of a soft magnetic material 670 according to an embodiment of the present application is shown. The soft magnetic material may include iron, cobalt, nickel, and alloys such as hyperco, permalloy, magnetic steel, amorphous metal alloy materials, etc. As described herein, the soft magnetic material is used to fabricate the pole pieces 234. FIG. 6E shows the magnetic flux density 654 of the magnetically soft material as a function of the externally applied magnetic field strength 658 resulting from a current passing through a surrounding coil as shown in FIG. 2B featuring a magnetically soft yoke 208. The magnetically soft material is used for all pole pieces 234 used in the permanent electromagnet array because it does not retain magnetization and therefore can efficiently conduct the magnetic flux from the permanent electromagnets 140 in the array to the air gap 224 and through the ferromagnetic surface 204.

[0081] Referring now to FIG. 7A, a diagram illustrating a permanent electromagnet array 700 according to an embodiment of the present application is shown. FIG. 7A shows an exploded view 700 of a 34-member permanent electromagnet array with windings formed from layered serpentine conductor traces 716 on an insulator film layer 720. The serpentine winding arrangement is designed to generate only alternating polarity patterns of magnetization in the side-by-side permanent electromagnet array used for short-range attraction. The winding design serves the purpose of excellent short-range attraction. The serpentine pattern windings provide exceptional magnetic flux strength in the array because the conductor packing density is higher than can be achieved with round wire windings.

[0082] The serpentine winding can be fabricated from alternating even 704 and odd 708 patterned conductor paths 716 on the insulating film layer 720. In a usage example, current can flow inward from terminal 2 732B through the top pad of the top layer 736 to the even layer 704, then travel the serpentine path of the even layer and then exit from the bottom terminal soldered to the top terminal of the odd layer 708. The pairs and interconnects 728 of the odd 708 and even 704 layers continue to be stacked with their solder pads connected together, forming a continuous current circuit from one layer to the next. Finally, after passing through the stack 724 of layers 704, 708, it reaches the bottom layer 740 where the opposite terminal 1 732A is attached. The bottom layer 740 is routed to terminal 1 732A. Each layer 704, 708 in the stack of layers 724 includes a hole 712 for each of the magnet cores 104 to pass through.

[0083] Insulating film 720 is provided to prevent shorting between coil layers 724. This can be accomplished using flexible printed circuit fabrication, where conductive traces 716 of copper-plated thin film plastic, such as polyamide, are etched away to leave copper coil layers in the desired winding pattern, intimately bonded to polyamide insulating film 720. In other embodiments, other PCB insulating materials and conductors are possible. Other forms of manufacturing mats are used without departing from the spirit of the disclosed embodiments. In one embodiment, magnet core 104 may be approximately 3.2 mm wide by 6.4 mm long. However, any practical size and shape may be used based on final requirements.

[0084] Referring now to FIG. 7B, a diagram showing details 704 of a uniform serpentine coil layer according to an embodiment of the present application is shown. FIG. 7B shows details of the conductor wiring traces 716 and insulators 720 on the even layers 704 of the coil circuit layer. The current trace starts at the top solder pad 750A and meanders around each successive magnetic core 104, each making a half turn, until it reaches the bottom solder pad 754A. This current flows clockwise and counterclockwise around each AC magnet core 104 in the array. Thus, when conducting, the current pulse 144 subsequently magnetizes each magnetic core 104 with an alternating polarity sequence. The current moving through the layers of the serpentine circuit sequentially adds successive half turns 758 of magnetic flux to each magnetic core 104. For example, a current flowing in a clockwise direction makes a half turn around one of the magnet cores 104 on an even layer 704 and then follows a serpentine path on the next odd layer 708 carrying the same current in a clockwise half turn direction, under the same half turn from the previous layer.

[0085] 7C, a diagram illustrating detail 708 of an odd serpentine coil layer, according to an embodiment of the present application, is shown. Figure 7C shows detail of conductor wiring traces 716 and insulators 720 on an odd layer 708 of the coil circuit layer. The features and operation of odd layer 708 are as described with respect to even coil layer 704 of Figure 7B, but instead includes bottom solder pads 754B and top solder pads 750B.

[0086] Referring now to FIG. 7D, a diagram showing spiral coil layer interconnection details 760 is shown, according to an embodiment of the present application. FIG. 7D shows layers of circular coil links electrically connected from one layer to the next, where the circular links and connections together form a helical current path 768 above and below the magnetic core 104. In fact, using the same printed circuit technology that created the spiral coils 764, certain coils can be connected in series or parallel to operate together at one time. For example, if coils 1, 2, 3, and 4 are connected in series or parallel and pulsed with current 144, they may generate one polarity in magnetic cores 1, 2, 3, and 4. Similarly, if coils 5, 6, 7, and 8 are electrically connected in series or parallel and pulsed with current 144, they may also adopt a common polarity in magnetic cores 5, 6, 7, and 8.

[0087] In effect, if cores 1, 2, 3, and 4 are oppositely magnetically polarized as cores 5, 6, 7, and 8, the resulting permanent electromagnet array is programmed into a short-range attractive mode. This mode is shown in Figure 7F. Furthermore, if cores 1, 2, 3, and 4 are identically magnetically polarized as cores 5, 6, 7, and 8, the permanent electromagnet array is programmed into a longer-range attractive mode. This mode is shown in Figure 7G.

[0088] Thus, the spiral winding method 768 allows one permanent electromagnet array to be programmed for either short-range or long-range attractive forces. Finally, introducing a decreasing chain of AC pulses 144 to each series or parallel connected coil (FIG. 6B) demagnetizes the array and no attractive force is produced. This mode is shown in FIG. 7H.

[0089] 7E, a diagram showing a spiral coil layer detail 770 according to an embodiment of the present application is shown. FIG 7E shows that an etched conductor layer has been interconnected over another conductor layer to provide an interconnected spiral coil with terminal 1 732A and terminal 2 732B.

[0090] Referring now to FIG. 7F, a diagram is shown illustrating a top view of a permanent electromagnet array for high force and short distance attraction 780 according to an embodiment of the present application. FIG. 7F shows a top view of a permanent electromagnet array 784. An exemplary configuration of 2X4 with two rows of four magnet cores 104 each is shown. The high force / short distance attraction configuration utilizes oppositely polarized permanent electromagnets 140 to facilitate a short magnetic flux return path. In the first or top row, the first and third magnet cores 104 have north poles 116 facing the ferrous object surface 204, and the second and fourth magnet cores 104 have south poles 120 facing the ferrous object surface 204. In the second or bottom row, the second and fourth magnet cores 104 have north poles 116 facing the ferrous object surface 204, and the first and third magnet cores 104 have south poles 120 facing the ferrous object surface 204.

[0091] Referring now to FIG. 7G, a diagram is shown illustrating a top view of a permanent electromagnet array for lower force and longer range attraction 786, according to an embodiment of the present application. FIG. 7G shows a top view of a permanent electromagnet array 788. An exemplary configuration of 2X4 with two rows of four magnet cores 104 each is shown. The lower force / longer range attraction configuration utilizes similarly polarized permanent electromagnets 140 to facilitate a long magnetic flux return path. In both rows, all magnet cores 104 have their north poles 116 facing the ferrous object surface 204.

[0092] Referring now to Figure 7H, a diagram is shown illustrating a top view of a demagnetized permanent electromagnet array 790, according to an embodiment of the present application. An exemplary configuration of 2x4 is shown with two rows of four magnet cores 104 each. Unlike the configuration shown in Figures 7F and 7G, all magnet cores 104 in Figure 1C are demagnetized 794 and have no polar orientation (i.e., no north pole 116 or south pole 120).

[0093] Referring now to FIG. 8A, a diagram illustrating a top view of an end-on-end two-dimensional permanent electromagnet array polarized for short-range attractive forces 800 is shown, according to an embodiment of the present application.

[0094] Figure 8A is a top view of an eight-member end-on-end two-dimensional permanent electromagnet array. The array shown is polarized in an alternating north-south pattern as shown, optimizing this configuration for short-range attractive forces. In this example, the short distance is nominally equal to the distance between polarity changes in the length of one permanent electromagnet.

[0095] It should be noted that the end-on-end configuration can be implemented in a variety of ways. It can be implemented as a linear or partially / fully curved array, as shown in Figures 4A / 4B, or as a close-in configuration, as shown in Figure 8A. The closed configuration does not need to have a defined start or end point, as in linear or curved arrays, and can be implemented as a geometric or non-geometric shape. Figure 8A shows a "square" embodiment with a pole piece 234 between a pair of permanent electromagnets 140.

[0096] Referring now to Figure 8B, a diagram showing a side view of an end-on-end two-dimensional permanent electromagnet array and magnetic flux lines 810 according to an embodiment of the present application is shown. Figure 8B depicts a side view of the permanent electromagnet array 800 of Figure 8A. From the side, only three of the nine pole pieces 234 are visible, identified as pole pieces 234A, 234B, and 234C, and the two permanent electromagnets 140 are identified as permanent electromagnet 140A and permanent electromagnet 140B. Each permanent electromagnet 140 has its own magnetic flux direction 112, proceeding from the south pole 120 to the north pole 116.

[0097] Referring now to FIG. 8C, a diagram is shown illustrating a top view of an end-on-end two-dimensional permanent electromagnet array polarized for longer range attractive forces 820, according to an embodiment of the present application. FIG. 8C illustrates an end-on-end permanent electromagnet array 820 in which two strings of four permanent electromagnets 140 are each polarized in the same direction from left to right. Thus, the right-most pole piece 234 is the north pole 116 on the north-most side of the array, and the left-most pole piece 234 is the south pole 120 on the south-most side of the array. FIG. 8C is tilted at 45 degrees to provide the corresponding edge view of FIG. 8D.

[0098] Referring now to Figure 8D, a diagram is shown illustrating a side view of an end-on-end two-dimensional permanent electromagnet array programmed for longer range attractive forces and magnetic flux lines 830, according to an embodiment of the present application. Figure 8D shows an edge view of Figure 8C, illustrating the longer magnetic flux lines that optimize this configuration for long range attractive forces. The long range is nominally defined as the distance between the north pole 116 and south pole 120 of the end-on-end magnet array.

[0099] In practice, half of the permanent magnet coils are electrically connected as one group in series or parallel, and the other half are connected separately in series or parallel. Thus, each group can have its own dedicated H-bridge driver, which is an electronic device as shown and described with reference to Figures 5A-5F. The H-bridge driver provides magnetizing and demagnetizing current pulses as shown and described with reference to Figures 6A-6C. In this case, when the two groups of windings are polarized in opposite directions, the array is optimized for short-range attraction. When the two groups are polarized in the same direction, the array is optimized for long-range attraction. In the edge view 830, five pole pieces 234 are visible, pole pieces 234A, 234B, and 234C. Between each pair of pole pieces 234, four permanent electromagnets 140 are visible.

[0100] Referring now to FIG. 9A, a flow chart illustrating a first coil magnetization process 900 according to an embodiment of the present application is shown. The first embodiment magnetizes a permanent electromagnet array in a single charge cycle and refers to the charge pulse states shown in FIG. 5A-5F. In one embodiment, the permanent electromagnet array includes a plurality of permanent electromagnets of a common length arranged in parallel and a planar pole piece coupled to a first end of the plurality of permanent electromagnets. Each permanent electromagnet includes a first end and a second end opposite the first end. In a second embodiment, the permanent electromagnet array includes a plurality of pole pieces and a plurality of permanent electromagnets of a common length. Each permanent electromagnet includes a first and second end, and the permanent electromagnet is linearly arranged end to end between a pair of pole pieces and coupled to the pair of pole pieces. The flow begins at block 904.

[0101] At block 904, all of the permanent electromagnets 140 are in an existing state. The existing state may include a high force / short attractive force state, a lower force / longer attractive force state, or a demagnetized state. The flow proceeds to block 908.

[0102] At block 908, the control circuit 516 receives a command 520 to generate a (different) desired magnetic state.

[0103] At block 912, the control circuit 516 defines the necessary switch states 528, 532, 536, 540 for all coils 524 and permanent electromagnets 140 from the commands 520. The flow proceeds to block 916.

[0104] In block 916, the control circuit 516 enables the charger 508 to charge the capacitor 512. The flow proceeds to block 920.

[0105] In block 920, the charger 508 charges the capacitor 512. The flow proceeds to decision block 924.

[0106] At decision block 924, the control circuit 516 determines whether the capacitor 512 is fully charged. If the capacitor 512 is fully charged, the flow proceeds to block 928. If the capacitor 512 is not fully charged, the flow proceeds instead to block 920 to continue charging the capacitor 512.

[0107] In block 928, the capacitor 512 is charged and the control circuit 516 disables the charger 508. The flow proceeds to block 932.

[0108] At block 932, the control circuit 516 sets the switch states 528, 532, 536, 540 to the required switch states 528, 532, 536, 540 defined in block 912. The flow proceeds to block 936.

[0109] At block 936, the capacitor 512 discharges through the closed switches that correspond to the required switch states 528, 532, 536, 540. The flow proceeds to block 940.

[0110] The permanent electromagnet array generates the desired magnetic state at block 940. The flow ends at block 940.

[0111] Now referring to FIG. 9B, a flow chart showing a second coil magnetization process 950 according to an embodiment of the present application is shown. The second embodiment magnetizes a permanent electromagnet array in a series of charging cycles. FIG. 9B shows a process for optimizing the magnetization of the permanent electromagnet array through repeated discharge of the storage capacitor 512 into magnetization current pulses 144 that occur until the required magnetic state is created. This state may be when a certain number of magnetization pulses are used, such as the four current pulses 144 shown in FIG. 6A. Otherwise, the current pulses 144 may be continued until the required field strength is achieved, as measured by using the magnetic flux sensor output from the unit as shown in FIG. 11A and FIG. 11C. The flow begins at block 954.

[0112] At block 954, all of the permanent electromagnets 140 are in an existing state. The existing state may include a high force / short range attractive state, a low force / long range attractive state, or a demagnetized state. The flow proceeds to block 958.

[0113] At block 958, the control circuit 516 receives a command 520 to generate a (different) desired magnetic state. The flow proceeds to block 962.

[0114] At block 962, the control circuit 516 defines the required switch states 528, 532, 536, 540 for all coils 524 from the command 520. The flow proceeds to block 966.

[0115] In block 966, the control circuit 516 enables the charger 508 to charge the capacitor 512. The flow proceeds to block 970.

[0116] At block 970, the charger 508 charges the capacitor 512. Each successive charging cycle according to Figures 5B-5C or 5B-5D charges the capacitor 512 to a successively higher level. The charging sequence is repeated until the permanent electromagnet 140 is fully magnetized. In one embodiment, the permanent electromagnet 140 may be fully magnetized when the permanent electromagnet 140 has an attractive force greater than a predetermined level. Flow proceeds to decision block 974.

[0117] At decision block 974, the control circuit 516 determines whether the capacitor 512 is fully charged. If the capacitor 512 is fully charged, the flow proceeds to block 978. If the capacitor 512 is not fully charged, the flow proceeds instead to block 970 to continue charging the capacitor 512.

[0118] In block 978, the capacitor 512 is charged and the control circuit 516 disables the charger 508. The flow proceeds to block 982.

[0119] At block 982, the control circuit 516 sets the switch states 528, 532, 536, 540 to the required switch states 528, 532, 536, 540 defined at block 962. The flow proceeds to block 986.

[0120] At block 986, the capacitor 512 discharges through the closed switches that correspond to the required switch states 528, 532, 536, 540. Flow proceeds to decision block 990.

[0121] At decision block 990, the control circuit 516 determines whether more discharge cycles of the capacitor 512 are needed. More discharge cycles are needed if the permanent electromagnet 140 is not yet fully magnetized or if the predetermined number of magnetization cycles (blocks 966-986) have not yet been completed. If more discharge cycles are needed, flow proceeds to block 966 to again charge the capacitor 512. If more discharge cycles are not needed, flow proceeds instead to block 994.

[0122] The permanent electromagnet array generates the desired magnetic state at block 994. The flow ends at block 994.

[0123] Referring now to FIG. 10, a flow chart illustrating a coil demagnetization process 1000 is shown, according to an embodiment of the present application. The demagnetization process deactivates the permanent electromagnet array in a sequence of successively decreasing charge cycles. FIG. 10 illustrates the process of demagnetizing the permanent electromagnet array. The number of discharge cycles required can be a number such as 10 or 20, or can be based on how many current pulses 144 are needed to reduce the magnetometer reading from FIG. 11A or FIG. 11C to a sufficiently low value. The flow begins at block 1004.

[0124] At block 1004, all of the permanent electromagnetic coils 524 are in an existing state. The existing state may include a high force / short range attractive force state or a low force / long range attractive force state. The flow proceeds to block 1008.

[0125] At block 1008, the control circuit 516 receives a command 520 to demagnetize the permanent electromagnet 140. The flow proceeds to block 1012.

[0126] In block 1012, the control circuit 516 obtains the required capacitor 512 voltages and switch states 528, 532, 536, 540 for all coils 524 from the commands 520. The flow proceeds to block 1016.

[0127] At block 1016, the control circuit 516 enables the charger 508 to charge the capacitor 512. The flow proceeds to block 1020.

[0128] At block 1020, the charger 508 charges the capacitor 512. According to FIG. 6B, the charger 508 charges the capacitor 512 to successively lower voltages. The charging sequence is repeated until the permanent electromagnet 140 is demagnetized. In one embodiment, the permanent electromagnet array may be demagnetized if the permanent electromagnet array has a net zero attractive force. In another embodiment, the permanent electromagnet array may be demagnetized if the permanent electromagnet array is below a predetermined level of attractive force. Flow proceeds to decision block 1024.

[0129] At decision block 1024, control circuit 516 determines whether capacitor 512 has reached the desired voltage. For a degauss operation, capacitor 512 is not fully charged at each step, but is continuously charged to a lower voltage with each or every other charging operation. If capacitor 512 has reached the desired voltage, flow proceeds to block 1028. If capacitor 512 has not reached the desired voltage, flow instead proceeds to block 1020 to continue charging capacitor 512.

[0130] At block 1028, the capacitor 512 is charged to the desired voltage and the control circuit 516 disables the charger 508. The flow proceeds to block 1032.

[0131] At block 1032, the control circuit 516 sets the switch states 528, 532, 536, 540 to the required switch states 528, 532, 536, 540 defined in block 1012. The flow proceeds to block 1036.

[0132] At block 1036, the capacitor 512 discharges through the closed switch that corresponds to the required switch state 528, 532, 536, 540. Flow proceeds to decision block 1040.

[0133] At decision block 1040, the control circuit 516 determines whether more discharge cycles are needed. More discharge cycles are needed if the permanent electromagnet 140 has not yet been demagnetized or if the predetermined number of demagnetization cycles (blocks 1016-1036) have not yet been completed. If more discharge cycles are needed, flow proceeds to block 1016 to recharge the capacitor 512. If more discharge cycles are not needed, flow proceeds instead to block 1044.

[0134] At block 1044, the permanent electromagnet array is demagnetized, completing the demagnetization process.

[0135] 11A, a diagram is shown illustrating a side view of a magnetometer installation 1100, according to an embodiment of the present application. The magnetometer is often based on a Hall effect sensor that measures the magnetic flux flowing through a sensor (magnetometer) 1104. It is attached to the back side of a planar pole piece 234 and is aligned with one or more permanent electromagnets 140 of a permanent electromagnet array.

[0136] 11A shows a magnetometer installation for a side-by-side permanent electromagnet array. In this configuration, a portion of the magnetic flux entering and exiting each individual permanent electromagnet 140 of the array is diverted by a machined circular groove or flux diverting slot 1112 in the pole piece 234, for example, conducting a portion of the magnetic flux from each individual permanent electromagnet 140 back through the magnetometer yoke 1104 to the pole piece 234. By knowing the amount of magnetic flux passing through one of the permanent electromagnets 140, one can estimate the magnetic flux passing through the entire array when the entire array is approximately the same distance from the ferromagnetic surface 204.

[0137] By measuring the magnetic flux flowing through the sensor 1104, the processor or control circuitry 516 can optimize different functions.

[0138] 1. Energize and Discharge - By knowing the state of the permanent electromagnet and by measuring the magnetic flux, the control circuit 516 can select the appropriate charging voltage for the capacitor 512 to achieve the state change command 520. This can help prevent overshooting or undershooting the desired state when performing a degauss cycle. The signal from the sensor 1104 can be an analog voltage output, a radio signal, an optical signal, etc. that is fed to the control circuit 516.

[0139] 2. Object Sensing - An activated permanent electromagnet 140 in strong, intimate contact with a ferrous object surface 204 is likely to have a high total magnetic flux due to the low reluctance of the circuit. If the ferrous object 204 is not in good contact or is not present entirely, the magnetic flux must fight through a high reluctance air or vacuum gap to complete the magnetic circuit, significantly lowering the total magnetic flux. Thus, if the permanent electromagnet 140 is activated and the measured magnetic flux is much lower than expected, it may be an indicator that there is not good contact with the ferromagnetic surface 204. This is particularly useful for automated processes where there may not be a human operator present to visually confirm that contact may not be good.

[0140] In one embodiment, the permanent electromagnet array may include a groove on a back surface of a pole piece opposite the plurality of permanent electromagnets, a magnetic flux sensor attached to the back surface within the enclosed area, and an iron cap attached to the pole piece opposite the magnetic flux sensor and outside the groove. The groove surrounds an area corresponding to the one or more permanent electromagnets. A portion of the magnetic flux flowing through the one or more permanent electromagnets flows through the magnetic flux sensor, and in response, the magnetic flux sensor is configured to provide a proximity indication reflecting a distance between the permanent electromagnet array and the iron surface.

[0141] In another embodiment, the permanent electromagnet array can include a magnetic flux sensor mounted between an end of the permanent electromagnet and a pole piece, the magnetic flux sensor configured to provide a proximity indication reflecting a distance between the permanent electromagnet array and a ferrous surface.

[0142] 11B, a diagram showing a bottom view of a magnetometer mounting 1120 is shown, according to an embodiment of the present application. FIG 11B shows the positional relationship between the magnet 112, the magnetometer 1104, and the flux bypass slots 1112.

[0143] 11B shows a bottom view of the magnetometer 1104 mounting, showing the coaxial positioning of the permanent electromagnet core, magnetometer 1104, and flux bypass slot 1112. The return path yoke is not shown in this view, but overlaps the diameter of the bypass slot 1112.

[0144] 11C, a diagram showing a side view of a thickness mode magnetic flux sensor of an end-on-end array 1130 is shown according to an embodiment of the present application. FIG. 11C illustrates how a thickness mode magnetic flux sensor 1104 can be attached to measure the magnetic flux flowing through one arm of the end-on-end magnetic array. The magnetic flux sensor 1104 is an electronic device that outputs a voltage signal proportional to the magnetic flux moving through the sensor based on (for example) the Hall effect or the flux gate effect. A thickness mode magnetic flux sensor is a magnetic flux sensor that measures magnetic flux through a thickness. If the permanent electromagnet array is substantially parallel to the ferrous surface 204, the output of one magnetic flux sensor 1104 can indicate the magnetic flux strength and attractive force of the entire array. The magnetic flux moves through the permanent electromagnet array, the pole piece 234, the air gap 224, the ferromagnetic surface 204, and the thickness mode magnetic flux sensor 1104 to form a magnetic circuit.

[0145] In effect, the use of a magnetic flux sensor 1104 with a permanent electromagnet array allows a user to determine whether the array is magnetically attached to a surface (high magnetic flux through the sensor 1104) or whether it is attracted to but not connected to the ferrous surface 204 (medium magnetic flux) or is far away from the ferrous surface 204 (low magnetic flux).

[0146] Finally, those skilled in the art should appreciate that they may readily use the conception and specific examples disclosed as a basis for designing or modifying other structures for carrying out the same purposes of the present application without departing from the spirit and scope of the application as defined by the appended claims.

[0147] It will be readily understood that the components of the present application, as generally described and illustrated in the figures herein, could be arranged and designed in a wide variety of different configurations, and thus, the detailed description of the embodiments is not intended to limit the scope of the application, as claimed, but is merely representative of selected illustrative examples of the application.

[0148] Those skilled in the art will readily appreciate that applications such as those described above may be implemented with steps in a different order and / or with hardware elements in different configurations than those specifically disclosed. Thus, while the application has been described based on these preferred embodiments, it will be apparent to those skilled in the art that certain modifications, variations, and alternative constructions are apparent while remaining within the spirit and scope of the application. Accordingly, reference should be made to the claims to determine the scope and scope of the application.

[0149] While preferred embodiments of the present application have been described, it should be understood that the described embodiments are exemplary only, and that the scope of the application, when taken into consideration with its full range of equivalents and modifications (e.g., protocols, hardware devices, software platforms, etc.), should be defined only by the appended claims.

Claims

1. a plurality of permanent electromagnets arranged in parallel and having a common length, each said permanent electromagnet including a first end and a second end opposite the first end; a planar pole piece coupled to the first ends of the plurality of permanent electromagnets; A permanent electromagnet array comprising:

2. The permanent electromagnet array of claim 1 , wherein the plurality of permanent electromagnets are arranged in a two-dimensional array.

3. Each of the plurality of permanent electromagnets is a magnetically hard material portion; a conductor wound in a spiral shape on the hard material portion; and the conductor comprises: A wire, A plurality of laminate layers, each layer comprising: a plurality of planar complete loops of conductive traces bonded to the dielectric film around each of said rigid material portions; a plurality of planar serpentine half-loops of conductive traces bonded to the dielectric film around each of the rigid material portions; A plurality of laminate layers, including one of: The permanent electromagnet array of claim 1 , comprising one of:

4. 4. The permanent electromagnet array of claim 3, wherein the magnetically hard material portion comprises one of Alnico, Neodymium, and Samarium Cobalt, and the pole pieces comprise one of Hyperco, Permalloy, magnetic steel, and an amorphous metal alloy material.

5. 2. The permanent electromagnet array of claim 1, wherein the plurality of permanent electromagnets are configured to be magnetically polarized in a first direction, magnetically polarized in a second direction opposite the first direction, and magnetically depolarized.

6. an energy storage device configured to provide current pulses to the plurality of permanent electromagnets to polarize the permanent electromagnets; an H-bridge coil drive circuit coupled to the energy storage device and configured to selectively route the current pulses in one of a first direction and a second direction opposite the first direction to the permanent electromagnet, a polarity of the permanent electromagnet being determined by the first and second directions; Further equipped with 2. The permanent electromagnet array of claim 1, wherein the H-bridge coil drive circuit is configured to polarize each permanent electromagnet in an opposite direction to its nearest neighboring permanent electromagnet by a received current pulse.

7. an energy storage device configured to provide current pulses to the plurality of permanent electromagnets to polarize the permanent electromagnets; an H-bridge coil drive circuit coupled to the energy storage device and configured to selectively route the current pulses in one of a first direction and a second direction opposite the first direction to the permanent electromagnet, a polarity of the permanent electromagnet being determined by the first and second directions; Further equipped with 2. The permanent electromagnet array of claim 1, wherein the H-bridge coil drive circuit is configured to polarize each permanent electromagnet in the same direction as its nearest neighboring permanent electromagnet with a received current pulse.

8. an energy storage device configured to provide a series of alternating current pulses of decreasing magnitude to the plurality of permanent electromagnets to depolarize the permanent electromagnets; an H-bridge coil drive circuit coupled to the energy storage device, the H-bridge coil drive circuit configured to alternately route the current pulses to the permanent electromagnet between a first direction and a second direction opposite the first direction; Further equipped with 2. The permanent electromagnet array of claim 1, wherein the H-bridge coil drive circuit is configured to depolarize each permanent electromagnet such that in response, the plurality of permanent electromagnets are configured to not provide an attractive force to a ferrous surface.

9. a groove in a back surface of the pole piece opposite the plurality of permanent electromagnets, the groove surrounding an area corresponding to one or more permanent electromagnets; a magnetic flux sensor attached to the back surface within the enclosed area; an iron cap attached to the flux sensor on the opposite side of the pole piece and to the pole piece outside the groove; Further equipped with 2. The permanent electromagnet array of claim 1, wherein a portion of the magnetic flux flowing through the one or more permanent electromagnets flows through the magnetic flux sensor, and in response, the magnetic flux sensor is configured to provide a proximity indication reflecting a distance between the permanent electromagnet array and a ferrous surface.

10. A plurality of magnetic pole pieces; a plurality of permanent electromagnets of a common length, each including a first and second end, linearly disposed end-to-end between and coupled to a pair of pole pieces; A permanent electromagnet array comprising:

11. 10. The permanent electromagnet array of claim 9, wherein the permanent electromagnet array is arranged in an enclosed configuration comprising an alternating series of permanent electromagnets and pole pieces.

12. Each of the plurality of permanent electromagnets is a magnetically hard material portion; a conductor wound in a spiral shape on the hard material portion; and the conductor comprises: Wire and A plurality of laminate layers, each layer comprising: a plurality of laminate layers including a plurality of planar complete loops of conductive traces bonded to an insulating film around each of said magnetically hard material portions; 10. The permanent electromagnet array of claim 9, comprising one of:

13. 13. The permanent electromagnet array of claim 12, wherein the magnetically hard material portion comprises one of Alnico, Neodymium, and Samarium Cobalt, and the pole pieces comprise one of Hyperco, Permalloy, magnetic steel, and an amorphous metal alloy material.

14. 10. The permanent electromagnet array of claim 9, wherein the plurality of permanent electromagnets are configured to be magnetically polarized in a first direction, magnetically polarized in a second direction opposite the first direction, and magnetically depolarized.

15. an energy storage device configured to provide current pulses to the plurality of permanent electromagnets to polarize the permanent electromagnets; an H-bridge coil drive circuit coupled to the energy storage device and configured to selectively route the current pulses in one of a first direction and a second direction opposite the first direction to the permanent electromagnet, a polarity of the permanent electromagnet being determined by the first and second directions; Further equipped with 10. The permanent electromagnet array of claim 9, wherein the H-bridge coil drive circuit is configured to polarize each permanent electromagnet in an opposite direction to its nearest neighboring permanent electromagnets by a received current pulse.

16. an energy storage device configured to provide current pulses to the plurality of permanent electromagnets to polarize the permanent electromagnets; an H-bridge coil drive circuit coupled to the energy storage device and configured to selectively route the current pulses in one of a first direction and a second direction opposite the first direction to the permanent electromagnet, a polarity of the permanent electromagnet being determined by the first and second directions; Further equipped with 10. The permanent electromagnet array of claim 9, wherein the H-bridge coil drive circuit is configured to polarize each permanent electromagnet in the same direction as its nearest neighboring permanent electromagnet with a received current pulse.

17. an energy storage device configured to provide a series of current pulses of decreasing magnitude to a plurality of permanent electromagnets to depolarize the permanent electromagnets; an H-bridge coil drive circuit coupled to the energy storage device, the H-bridge coil drive circuit configured to alternately route the current pulses to the permanent electromagnet between a first direction and a second direction opposite the first direction; Further equipped with 10. The permanent electromagnet array of claim 9, wherein the H-bridge coil drive circuit is configured to depolarize each permanent electromagnet such that in response, the plurality of permanent electromagnets are configured to not provide an attractive force to a ferrous surface.

18. a magnetic flux sensor mounted between the end of the permanent electromagnet and the pole piece; The permanent electromagnet array of claim 9 , wherein the magnetic flux sensor is configured to provide a proximity indication reflecting a distance between the permanent electromagnet array and a ferrous surface.

19. An electric permanent coil; an energy storage device configured to provide a current pulse; an H-bridge drive circuit coupled to the electrically permanent coil and the energy storage device, the H-bridge drive circuit including a switching element including an insulated gate thyristor configured to receive current pulses from the energy storage device and selectively drive the current pulses relative to the electrically permanent coil in a first direction or a second direction opposite the first direction; a control circuit coupled to the switching elements and configured to select the first and second directions, a gate drive voltage for each switching element being optically isolated between the control circuit and the switching elements; An apparatus comprising:

20. 20. The apparatus of claim 19, wherein the electric permanent coil includes a magnetic core made from one of alnico, neodymium, and samarium cobalt.

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