Charger with nanocrystalline ferrite choke

Abstract

The battery pack charging system includes a battery pack interface configured to receive the battery pack, a charging circuit coupled to the battery pack interface and providing a charging current to the battery pack interface, and a controller coupled to the charging circuit and configured to control the provision of the charging current to the battery interface. The battery pack charging system further includes a power supply circuit coupled to the charging circuit, a filter circuit coupled to the power supply circuit and including a nanocrystalline ferrite common mode choke, and an AC plug configured to connect the filter circuit to an AC power source.

Description

[Technical field]

[0001] Related Applications This application claims the benefit of U.S. Provisional Patent Application No. 62 / 939,747, filed November 25, 2019, the entire contents of which are incorporated herein by reference.

[0002] FIELD OF THE DISCLOSURE This application relates to battery chargers, and more particularly to power tool battery chargers that include a filter element. Summary of the Invention [Means for solving the problem]

[0003] One embodiment of the present invention provides a battery pack charging system. The battery pack charging system includes a battery interface configured to receive a battery pack, and a charging circuit coupled to the battery interface and configured to provide a charging current to the battery interface. The battery pack charging system further includes a controller coupled to the charging circuit and configured to control the provision of the charging current to the battery interface, and a power supply circuit coupled to the charging circuit. The battery pack charging system further includes a filter circuit coupled to the power supply circuit and including a nanocrystalline ferrite common mode choke, and an AC plug configured to connect the filter circuit to an AC power source.

[0004] In some embodiments, the filter circuit further comprises at least one differential mode choke. In some embodiments, the filter circuit further comprises a ferrite bead. In some embodiments, the system further comprises a second nanocrystalline ferrite common mode choke. In some embodiments, the second nanocrystalline ferrite common mode choke is in series with the nanocrystalline ferrite common mode choke. In some embodiments, the nanocrystalline ferrite common mode choke is outside the charger housing and the second nanocrystalline ferrite common mode choke is inside the charger housing. In some embodiments, the nanocrystalline ferrite common mode choke and the second nanocrystalline ferrite common mode choke are within the charger housing. In some embodiments, the nanocrystalline ferrite common mode choke is toroidal shaped. In some embodiments, the system further comprises a housing that houses the charging circuit, the controller, the power circuit, and the nanocrystalline ferrite common mode choke.

[0005] In some embodiments, the system further comprises a charger housing housing the charging circuit, the controller, and the power circuit. The system further comprises a filter block housing housing the nanocrystalline ferrite common mode choke. The system further comprises a power cable connecting the charger housing and the filter block housing. In some embodiments, the system further comprises a differential mode choke pair including first and second differential mode chokes, the differential mode choke pair being part of the filter circuit. In some embodiments, the system further comprises a circuit board within the filter block housing, the differential mode choke pair and the nanocrystalline ferrite common mode choke being disposed on the circuit board.

[0006] Another embodiment of the present invention provides a battery pack charging system including a battery pack interface configured to receive a battery pack and a charging circuit coupled to the battery pack interface and configured to provide a charging current to the battery pack interface. The battery pack charging system further includes a controller coupled to the charging circuit and configured to control the provision of the charging current to the battery pack interface. The battery pack charging system further includes a power supply circuit coupled to the charging circuit and a charger housing containing the charging circuit, the controller, and the power supply circuit. The battery pack charging system further includes an AC plug configured to connect to an AC power source and a filter circuit external to the charger housing and including a nanocrystalline ferrite filter element, the filter circuit configured to connect the power supply circuit to the AC plug to provide AC power to the power supply circuit.

[0007] In some embodiments, the system further comprises a second nanocrystalline ferrite filter element in the charger housing. In some embodiments, the second nanocrystalline ferrite filter element is in series with the nanocrystalline ferrite filter element. In some embodiments, the filter circuit further comprises a differential mode choke pair including first and second differential mode chokes, and a ferrite bead. In some embodiments, the system further comprises a circuit board in the filter block housing, and the differential mode choke pair and the nanocrystalline ferrite common mode choke are disposed on the circuit board. In some embodiments, the system further comprises a ferrite bead disposed along the first power cable between the filter block housing and the charger housing. In some embodiments, the nanocrystalline ferrite filter element is a nanocrystalline ferrite common mode choke having a toroidal shape. In some embodiments, the system further comprises a second nanocrystalline ferrite filter element disposed in the charger housing.

[0008] In some embodiments, the system further comprises a filter block housing that houses the filter circuit, a first power cable connecting the charger housing and the filter block housing, and a second power cable connecting the filter block housing to an AC plug. In some embodiments, the nanocrystalline ferrite filter element is a nanocrystalline ferrite common mode choke. In some embodiments, the filter circuit further comprises a differential mode choke pair including first and second differential mode chokes, the differential mode choke pair being part of the filter circuit.

[0009] Another embodiment of the present invention provides a method for charging a battery pack. The method includes receiving a battery pack via a battery pack interface of a battery pack charger and receiving AC power at a power supply of the battery pack charger via a power cable. The method further includes converting the AC power to DC power by the power supply. The method further includes controlling, by an electronic controller, a supply of charging current to the battery pack interface to charge the battery pack. The method further includes receiving an extraneous signal on the power cable and filtering, by a nanocrystalline ferrite toroidal choke, the extraneous signal on the power cable.

[0010] In some embodiments, the nanocrystalline ferrite toroidal choke is a common mode choke. In some embodiments, the method further includes filtering extraneous signals on the power cable with the at least one differential mode choke. In some embodiments, the method further includes housing the nanocrystalline ferrite toroidal choke and the at least one differential mode choke with a filter block housing.

[0011] In some embodiments, filtering extraneous signals on the power cable further includes filtering extraneous signals on the power cable through a first nanocrystalline ferrite toroidal choke configured to filter signals at a first frequency, and filtering extraneous signals on the power cable through a second nanocrystalline toroidal choke configured to filter signals at a second frequency. In some embodiments, receiving AC power at the battery pack charger power source includes receiving AC power at an AC plug, and providing AC power from the AC plug to the power source through the nanocrystalline ferrite toroidal choke and the at least one differential mode choke.

[0012] Before any embodiments of the invention are described in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings, as the invention is capable of other embodiments and of being practiced or carried out in various ways.

[0013] As used herein, the use of "including" and "comprising" and variations thereof is meant to include the items listed before it and equivalents thereof as well as additional items. As used herein, the use of "consisting of" and variations thereof is meant to include only the items listed before it and equivalents thereof.

[0014] Also, functionality described herein as being performed by one component may be performed by multiple components in a distributed manner. Similarly, functionality performed by multiple components may be integrated and performed by a single component. Similarly, components described as performing a particular function may also perform additional functions not described herein. For example, a device or structure that is "configured" in a particular way is configured in at least that way, but may also be configured in a way not described.

[0015] Additionally, some embodiments described herein may include one or more electronic processors configured to perform the described functions by executing instructions stored on a non-transitory computer-readable medium. Similarly, embodiments described herein may be implemented as a non-transitory computer-readable medium that stores instructions executable by one or more electronic processors to perform the described functions. As used in this application, "non-transitory computer-readable medium" includes all computer-readable media, but does not consist of a transitory propagating signal. Thus, a non-transitory computer-readable medium may include, for example, a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a ROM (read-only memory), a RAM (random access memory), a register memory, a processor cache, or any combination thereof.

[0016] Many of the described modules and logical structures may be implemented in software executed by a microprocessor or similar device, or in hardware using various components such as application specific integrated circuits ("ASICs"). Terms such as "controller" and "module" may include or refer to both hardware and / or software. Capitalized terms conform to common practice and help associate the description with coding examples, equations, and / or figures. However, no particular meaning should be implied or inferred merely because of the use of capital letters. Thus, the claims should not be limited to any particular embodiment or term, or to any particular hardware or software implementation, or combination of software or hardware.

[0017] Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. [Brief description of the drawings]

[0018] [Figure 1]1 illustrates one embodiment of a battery pack charging system. [Diagram 2] 2 is a perspective view of a battery pack charger of the battery pack charging system shown in FIG. 1. [Figure 3A] FIG. 2 is a top view of the filtering block of the battery pack charging system shown in FIG. 1 with the upper housing portion removed. [Figure 3B] FIG. 3B is a side view of the filtering block shown in FIG. 3A. [Figure 3C] FIG. 3B is a top perspective view of the filtering block shown in FIG. 3A with the upper housing portion removed. [Figure 4] 2 is a block diagram of the battery pack charging system shown in FIG. 1. [Diagram 5] FIG. 2 is a circuit diagram of the filtering block shown in FIG. 1. [Figure 6] Figure 6A is a side view of a ferrite bead of the battery pack charging system shown in Figure 1. Figure 6B is a perspective view of the ferrite bead shown in Figure 6A with an overmold on a phantom. Figure 6C is a side cross-sectional view of the ferrite bead shown in Figure 6A. Figure 6D is a front cross-sectional view of the ferrite bead shown in Figure 6A. [Figure 7] 2 illustrates a second embodiment of a battery pack charger of the battery pack charging system shown in FIG. 1. [Figure 8] FIG. 8 is a block diagram of the battery pack charging system shown in FIG. 7. [Figure 9] 8 is a flowchart of a method that may be implemented by the battery pack charging system of FIG. 1 or FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] FIG. 1 illustrates a battery pack charging system 100. The battery pack charging system 100 includes a battery pack charger 101, a filtering circuit 102, an alternating current (AC) power cable 108 including a first power cable portion 108a and a second power cable portion 108b, and an AC plug 110. Although illustrated as a two-wire cord having a power line and a neutral wire (see FIG. 4), in some embodiments, the AC power cable 108 is a three-wire cord having a power line, a neutral wire, and a ground. The battery pack charger 101 includes a battery pack charger housing 118 including an upper housing portion 118a and a lower housing portion 118b. The battery pack charger 101 is configured to receive AC power from an AC power source (e.g., a grid-connected wall outlet or an AC generator) via the filtering circuit 102 and the AC plug 110 to charge a battery pack 112. The battery charger 101 includes a physical battery pack interface 116 configured to receive and hold the power tool battery pack 112 (e.g., via rails 113 that slidingly engage corresponding rails on the battery pack 112) and an electrical battery pack interface 114 (e.g., terminals) configured to engage corresponding electrical contacts 115 on the battery pack 112. In some embodiments, the battery charger 101 includes additional interfaces 114 and 116 such that it is configured to receive and charge multiple battery packs (e.g., receive and charge two battery packs simultaneously).

[0020] The battery pack 112 is configured to engage and power one or more power tools, such as a variety of electric power tools (e.g., cut-off saws, miter saws, table saws, core drills, augers, breakers, demolition hammers, compactors, vibrators, compressors, drain cleaners, welders, cable tuggers, pumps, etc.), outdoor tools (e.g., chainsaws, string trimmers, hedge trimmers, blowers, lawnmowers, etc.), other motorized equipment (e.g., vehicles, utility carts, material handling carts, etc.), and other non-motorized electrical equipment (e.g., power supplies, lights, AC / DC adapters, generators, etc.). In some embodiments, the battery pack 112 is a high-power battery pack (e.g., having a nominal voltage of at least 80 volts [V]). In some embodiments, the battery pack 112 has a lower or higher nominal voltage (e.g., 12 volts, 18 volts, 28 volts, between 10-14 volts, between 16-24 volts, etc.).

[0021] The filtering circuit 102 further includes a ferrite bead 104 and a filtering block 106 coupled between the battery charger 101 and the AC plug 110 by an AC power cable 108. As shown, a second power cable portion 108b couples the filtering block 106 to the battery pack charger 101, and a first power cable portion 108a couples the filtering block 106 to the AC plug 110. In addition, the ferrite bead 104 is disposed along the second power cable portion 108b. In some embodiments, the ferrite bead 104 is disposed along the first power cable portion 108a between the filtering block 106 and the AC plug 110. The filtering block 106 includes a filter block housing 120, also referred to as a block housing 120, which includes an upper block housing portion 120a and a lower block housing portion 120b (see FIGS. 3A-B).

[0022] FIG. 2 shows a perspective view of the battery pack charger 101 with the top housing portion 118a removed. The battery pack charger 101 includes a printed circuit board ("PCB") 200 within the battery pack charger housing 118. The PCB 200 includes various charger circuit elements mounted thereon and provides connections between these circuit elements. For example, the PCB 200 includes a controller, an AC / DC power converter, power switching elements, among other circuit elements mounted thereon, which are described in more detail with respect to FIG. 4. Also provided within the battery pack charger housing 118 are a fan 205 and a heat sink 210 that provide cooling airflow for cooling the circuit elements. In other configurations, the PCB 200 may include additional electrical circuits and / or components, such as, for example, additional microprocessors, transistors, diodes, current limiting components, capacitors, and the like. In some embodiments, the PCB 200 may include an internal choke 215, which may be a toroidal choke as shown and may include a nanocrystalline core. In some embodiments, the core of the internal choke 215 is constructed from a different material, and in some embodiments, the internal choke 215 has a different shape (eg, has a rectangular cross-section rather than a circular one).

[0023] 3A, 3B and 3C show the filtering block 106 with the upper block housing portion 120a removed. The filtering block 106 includes filtering elements configured to filter extraneous AC signals (e.g., noise) from the battery pack charging system 100. The filter block housing 120 houses a differential mode choke pair 302, a nanocrystalline ferrite choke 304, and a second PCB 306, also referred to as a filter PCB 306. The differential mode choke pair 302 includes a first differential mode choke 302a and a second differential mode choke 302b. Each of the first differential mode choke 302a, the second differential mode choke 302b, and the nanocrystalline ferrite choke 304 are mounted on the second PCB 306. Conductive traces on the second PCB 306 couple the differential mode choke pair 302, the nanocrystalline ferrite choke 304, and the terminals 310a-d with specific connections therebetween, which are shown in more detail in FIG. 4.

[0024] The differential mode chokes 302a and 302b are similarly sized, shaped, and constructed relative to one another. Each of the differential mode chokes 302a and 302b includes a respective coil 312 of insulated wire wound around a toroidal magnetic core 314. One of the differential mode chokes 302a and 302b is coupled to the power line of the power cable 108, and the other differential mode choke 302a and 302b is coupled to the neutral line of the power cable 108. The overall shape of the magnetic core 314, and therefore the differential mode chokes 302a and 302b, is toroidal as shown. The differential mode chokes 302a and 302b are disposed adjacent to one another and coaxially with respect to an axis 316 that passes through the center of the toroidal magnetic core 314 and is parallel to the surface of the second PCB 306 on which the differential mode chokes 302a and 302b are mounted. The gap along axis 316 between differential mode chokes 302a and 302b is smaller than the width of differential mode chokes 302a and 302b taken individually. Differential mode chokes 302a and 302b generally pass common mode currents while blocking (equal but opposite) differential currents. In some embodiments, magnetic cores 314 of differential mode chokes 302a and 302b may also be constructed from nanocrystalline ferrite material.

[0025] The nanocrystalline ferrite choke 304 is a common mode choke with two insulated wires wound around a toroidal magnetic core, with the first winding connected to the power line of the power cable 108 and the second winding connected to the neutral line of the power cable 108. The first winding (power line) and the second winding (neutral line) are wound so that the current present in both lines flows in the same direction. The first and second windings, and the nanocrystalline ferrite choke 304 itself, are secured to the choke support plate 318 by a clamp 308. The clamp 308 encases the nanocrystalline ferrite choke 304 wiring and limits the movement of the wiring. The choke support plate 318 is attached to the second PCB 306. In the nanocrystalline ferrite choke 304, the magnetic field generated by the wiring resists the increase in current generated by extraneous signals (e.g., noise) on the line. The nanocrystalline ferrite choke 304 generally passes differential currents (equal but opposite) while blocking common mode currents.

[0026] The nanocrystalline ferrite choke 304 is constructed of a nanocrystalline ferrite material. For example, the magnetic core is constructed of a nanocrystalline soft magnetic alloy material, such as FeCuNbSiB. The grain size of the ferrite crystallites may be less than 100 nm. This material provides high permeability and saturation magnetization due to its small size and high damping. Additionally, the nanocrystalline ferrite material provides a wider operating temperature and a flatter temperature characteristic. For example, the nanocrystalline ferrite choke 304 may have a substantially constant permeability, damping, and magnetic induction, regardless of temperature. Chokes including nanocrystalline ferrite material may be significantly smaller in size and weight when compared to their non-nanocrystalline ferrite counterparts. Additionally, fewer turns are required due to lower copper losses, and higher permeability and saturation provide improved operating margins and more effective performance.

[0027] The particular arrangement of the differential mode chokes 302a-b and the nanocrystalline choke 304 on the second PCB 306, together with their particular dimensions, allows the filtering block 106 to be compact. The differential mode chokes 302a and 302b are vertically coupled to the second PCB 306 such that an axis 316 extending through the center of the chokes 302a and 302b is parallel to the second PCB 306. The nanocrystalline ferrite choke 304 is horizontally coupled to the second PCB 306 such that an axis 320 extending through the center of the choke 304 is perpendicular to the second PCB 306. Although the differential mode chokes 302a and 302b and the nanocrystalline ferrite choke 304 are shown to be toroidal in shape, they are not limited to such. The differential mode chokes 302a and 302b and the nanocrystalline ferrite choke 304 may also be formed in other shapes, for example, a flattened rectangle.

[0028] The nanocrystalline ferrite choke 304 is generally larger than each of the individual differential mode chokes 302a and 302b. For example, the radius (from the center point to the outer periphery) of the nanocrystalline ferrite choke 304 is larger than the radius of each of the individual differential mode chokes 302a and 302b. In addition, the combined width of the differential mode choke pair 302 along the axis 316, including the gap between them, is smaller than the diameter of the nanocrystalline ferrite choke 304. The thickness of the nanocrystalline ferrite choke 304 measured along the axis 320 is smaller than the height of each of the individual differential mode chokes 302a and 302b measured in a direction parallel to the axis 320 (i.e., the height of the differential mode chokes 302a and 302b above the second PCB 306). The nanocrystalline ferrite choke 304 may also differ in winding structure. For example, the nanocrystalline ferrite choke 304 may be configured with a bifilar wiring configuration, while the differential mode chokes 302a and 302b may be configured with cross-sectional wiring. Nanocrystalline ferrite choke 304 may also be constructed with a different type of wiring than differential mode chokes 302a and 302b. For example, nanocrystalline ferrite choke 304 may have wire wrappings constructed with magnet wire, while differential mode chokes 302a and 302b may have wire wrappings constructed with triple insulated wire. Nanocrystalline ferrite choke 304 and differential mode chokes 302a and 302b are not limited to these configurations and may have other combinations of these properties.

[0029] As mentioned above, the filtering block 106 further includes four terminals 310a, 310b, 310c, and 310d. The terminals 310a and 310b couple the filtering block 106 to the AC plug 110 via the power line 402a and the neutral line 402b of the first power cable portion 108a, as shown in Figures 3C and 4. The terminals 310c and 310d couple the filtering block 106 to the ferrite bead 104 via the power line 403a and the neutral line 403b of the second power cable portion 108b, as shown in Figures 3C and 4.

[0030] FIG. 4 is a block diagram of a battery pack charging system 100. An AC plug 110 is coupled to a filtering circuit 102 by a first power cable section 108a including a power line 402a and a neutral line 402b. The power line 402a is coupled to a terminal 310a, and the neutral line 402b is coupled to a terminal 310b. Through the first power cable section 108a, the AC plug 110 provides AC power to a filtering circuit 102 including a nanocrystalline ferrite choke 304, differential mode chokes 302a and 302b, and a ferrite bead 104. The filter elements of the filtering circuit 102 block extraneous signals and signals of unwanted frequencies. Within the filtering circuit 102, the nanocrystalline ferrite choke 304 and the differential mode chokes 302a and 302b form a secondary filtering circuit 404. The secondary filtering circuit 404 is housed within a filter block housing 120 as described above with respect to FIGS. 3A-B. In an alternative embodiment, the secondary filtering circuit 404 may be located within the battery charger housing 118, described in more detail below. The secondary filtering circuit 404 is also shown in the circuit diagram of FIG.

[0031] As described above with respect to Figures 3A-B, in the secondary filtering circuit 404, the power conductor 402a is coupled to the first differential mode choke 302a, and the neutral conductor 402b is coupled to the second differential mode choke 302b. As described above with respect to Figures 3A-B, the nanocrystalline ferrite choke 304 includes two windings. The output of the first differential mode choke 302a is coupled to the first winding of the nanocrystalline ferrite choke 304, and the output of the second differential mode choke 302b is coupled to the second winding of the nanocrystalline ferrite choke 304. The first and second winding wires are then coupled to terminals 310c and 310d, respectively. These connections are also shown in the circuit diagram of Figure 5.

[0032] The filtering circuit 102 is connected to the battery charger 101 by a second power cable section 108b. More specifically, the second power cable section 108b includes a power line 403a and a neutral line 403b that are coupled to terminals 310c and 310d at one end and to an AC / DC converter 406 of the battery charger 101 at the opposite end. In addition, as described above, the ferrite bead 104 is disposed along the second power cable section 108b. The AC / DC converter 406, also referred to as a power circuit, converts the filtered AC power provided through the ferrite bead 104 into DC power used to charge a battery pack (e.g., battery pack 112) connected to the battery pack interface 114. The AC / DC converter 406 is, for example, a rectifier or a switched mode power supply. The AC / DC converter 406 also provides power to the electronic controller 412, although the circuit connections are not shown to simplify the diagram.

[0033] DC power is provided from the AC / DC converter 406 to the charging circuit 408. The charging circuit 408 is coupled to the battery pack interface 114 and configured to provide a charging current to the battery pack interface 114. The charging current is controlled by the electronic controller 412. For example, the charging circuit 408 may include one or more power switching elements (BJTs, MOSFETs, etc.) selectively controlled by the electronic controller 412 to provide a charging current to the battery pack interface 114 and inhibit charging current from flowing to the battery pack interface 114 (e.g., when the battery pack 112 is fully charged or when a battery pack is not present on the battery charger 101). The charging circuit 408 is also configured to provide battery status information regarding the battery pack 112 to the electronic controller 412, which in turn controls the charging circuit 408 based thereon. For example, the electronic controller 412 is configured to control the charging circuitry 408 to provide a charging current to the battery pack interface 114 (and thus the battery pack 112) until the electronic controller 412 determines that the battery pack 112 is fully charged (e.g., has a voltage level above a threshold stored in the electronic controller 412) or has reached a fault condition (e.g., an overheat signal is received from the battery pack 112 or the battery pack interface 114). In some embodiments, the charging circuitry 408 includes sensors (e.g., current sensors, voltage sensors, temperature sensors, etc.) that provide battery status information to the electronic controller 412. In some embodiments, in addition to or instead of one or more sensors in the charging circuitry 408, the battery pack 112 includes such sensors and a battery pack electronic controller that senses and communicates battery status information to the electronic controller 412 via the battery pack interface 114.

[0034] The electronic controller 412 determines the battery pack charging state and other battery status information of the battery pack 112 from the sensors or from communications. Additionally, the electronic controller 412 determines the status information of the battery charger 101 (e.g., charging, not charging, fault). The indicator 414 can be, for example, a light emitting diode ("LED") display. The indicator 414 is disposed on the battery charger housing 118 to provide visual feedback to the user. For example, the electronic controller 412 is configured to drive the indicator 414 to indicate a determined status of the battery pack 112, the battery charger 101, or a combination thereof.

[0035] In some embodiments, electronic controller 412 includes a memory that stores instructions and an electronic processor coupled to the memory and configured to retrieve and execute the instructions to implement the functions of electronic controller 412 described herein.

[0036] In some embodiments, the battery pack charger 101 may include an internal choke 215 configured to receive the second power cable portion 108b. The internal choke 215 is coupled to the power line 403a and neutral line 403b on the input side of the choke 215 and to the AC / DC converter 406 on the output side of the choke 215. The internal choke 215 may be a ferrite core, a nanocrystalline core, or a common mode toroidal choke of another structure. The internal choke 215 may be configured to filter noise at a different frequency than the nanocrystalline ferrite choke 304 (e.g., based on a different core size, core material, number of turns, or winding type). In some embodiments, the internal choke 215 is not present and the power line 403a and neutral line 403b from the ferrite bead 104 are coupled to the AC / DC converter 406 without the intervening internal choke 215.

[0037] Figure 5 shows a circuit diagram of filtering block 106 and secondary filtering circuit 404 of Figure 4. Included in this diagram are terminals 310a-d, differential mode chokes 302a and 302b, as previously described, and nanocrystalline ferrite choke 304. Also shown are the first winding (winding 500) and second winding (winding 502) of nanocrystalline ferrite choke 304, as previously described with respect to Figures 3A-B and 4.

[0038] 6A-6D show various views of the ferrite bead 104. The ferrite bead 104 suppresses high frequency noise by dissipating high frequency currents experienced by the AC power cable 108. The ferrite bead 104 is a hollow cylinder with an input end 104a and an output end 104b. The ferrite bead 104 is disposed around the AC power cable 108 such that the AC power cable 108 extends from the input end 104a to the output end 104b through an internal passage of the ferrite bead 104. A second power cable portion 108b couples the ferrite bead 104 to the strain relief segments 502a and 502b. The strain relief segment 502a may be fixed and connected to the battery pack charger 101. The strain relief segment 502b may be fixed and connected to the filtering block 106. In some embodiments, the strain relief segment 502b may also be fixed and connected to the AC plug 110. In one embodiment, the ferrite beads 104 are constructed from a nanocrystalline ferrite material.

[0039] FIG. 6B shows an isometric view of the ferrite bead 104. The AC power cable 108 enters the input end 104a of the ferrite bead 104, exits the output end 104b of the ferrite bead 104, wraps around the outer edge, and re-enters the input end 104a to form one complete loop around the surface of the ferrite bead 104. This arrangement is further shown in FIG. 6C, which provides a top view of the ferrite bead 104, and FIG. 6D, which provides a side view of the ferrite bead 104. The AC power cable 108 and ferrite bead 104 are encased in a polymer overmold 602, such as polyvinyl chloride (PVC). Additionally, the overmold 602 includes bead strain reliefs 606a and 606b.

[0040] 7-8 illustrate an alternative embodiment including a battery pack charger system 700. The battery pack charging system 700 of FIGS. 7-8 is similar in some respects to the battery pack charging system 100, and therefore like components are indicated with like reference numbers and only the differences between the battery pack charger system 700 and the battery pack charging system 100 are described. In an embodiment, the nanocrystalline ferrite choke 304 and the differential mode choke pair 302 are disposed and housed within the battery pack charger housing 118. For example, as shown in FIG. 7, the nanocrystalline ferrite choke 304 and the differential mode choke pair 302 are mounted to the PCB 200.

[0041] 8 shows a block diagram of an alternative embodiment of a battery pack charging system 700. As previously mentioned, in the battery pack charging system 700, the secondary filtering circuit 404 is within the battery pack charger housing 118. In other words, this embodiment integrates the secondary filtering circuit 404 into the battery pack charger housing 118 and removes the filtering block 106 as a separate component with its own housing. Additionally, as similarly noted with respect to the embodiment shown in FIG. 4, in some embodiments, the internal choke 215 is not included in the battery pack charger system 700.

[0042] 9 illustrates a block diagram of a method 900 performed by the battery pack charging system 100 and the battery pack charging system 700, in some embodiments. In block 902, the battery pack charging system 100 receives the battery pack 112 via the battery pack interface 114. For example, rails of the physical battery pack interface 116 engage corresponding rails 113 of the battery pack 112. In addition, terminals of the electrical battery pack interface 114 couple to corresponding electrical contacts 115 of the battery pack 112 to create an electrical connection.

[0043] At block 904, the battery pack charging system 100 receives AC power via the AC plug 110. The AC power may be provided by a residential electrical socket to which the AC plug 110 is coupled, a portable generator, or the like.

[0044] At block 906, the battery pack charging system 100 converts the received AC power to DC power via the AC / DC converter 406. For example, in some embodiments, the AC / DC converter 406 includes a rectifier that receives and rectifies the AC power to DC power. Additionally, in some embodiments, the AC / DC converter 406 includes a switched mode power supply that receives AC power at an input side and includes power switching elements that are switched on and off via control signals (e.g., from the electronic controller 412) to generate DC power at an output side.

[0045] In block 908, the battery pack charging system 100, via the electronic controller 412, controls the provision of charging current to the electrical battery pack interface 114. The provision of charging current can be based on previous settings stored in the memory of the electronic controller 412 and on sensed battery pack information obtained by the electronic controller 412, as described above.

[0046] At block 910, the battery pack charging system 100 receives an extraneous signal on the AC power cable 108. The extraneous signal may be, for example, electromagnetic interference or noise from internal circuit components (e.g., from the control of power switching elements) or from external sources (e.g., other nearby electronic devices, or other power tools or appliances coupled to the same AC power source) that are present when current returns to the AC power cable 108. At block 912, the battery pack charging system 100 filters the extraneous signal on the power line (such as the AC power cable 108) via the nanocrystalline ferrite choke 304. For example, the wiring of the nanocrystalline ferrite choke 304 forms a common mode configuration. The current flowing through the wiring creates a magnetic field that opposes the changes in the current flowing through the wiring, thus filtering the extraneous signal. The extraneous signal may also be filtered by the differential mode chokes 302a and 302b in combination with the nanocrystalline ferrite choke 304. In another configuration, the ferrite beads 104 also filter the extraneous signal.

[0047] Accordingly, the embodiments provided herein describe, among other things, systems and methods for filtering extraneous signals. Various features and advantages are set forth in the following claims.

Claims

1. a battery pack interface configured to receive the battery pack; a charging circuit coupled to the battery pack interface and configured to provide a charging current to the battery pack interface; a controller coupled to the charging circuit and configured to control a supply of charging current to the battery pack interface; a power supply circuit coupled to the charging circuit; a charger housing that houses the charging circuitry, the controller, and the power supply circuitry; a filter circuit coupled to the power supply circuit, the filter circuit including a nanocrystalline ferrite common mode choke; a filter block housing that houses the nanocrystalline ferrite common mode choke; a power cable connecting the charger housing and the filter block housing; an AC plug configured to connect the filter circuit to an AC power source; Equipped with Battery pack charging system.

2. 2. The battery pack charging system of claim 1, wherein the filter circuit includes at least one differential mode choke.

3. 2. The battery pack charging system of claim 1, wherein the filter circuit includes a ferrite bead.

4. 10. The battery pack charging system of claim 1 further comprising a second nanocrystalline ferrite common mode choke in series with the nanocrystalline ferrite common mode choke.

5. 5. The battery pack charging system of claim 4, wherein the nanocrystalline ferrite common mode choke is outside the charger housing and the second nanocrystalline ferrite common mode choke is inside the charger housing.

6. 5. The battery pack charging system of claim 4, wherein the second nanocrystalline ferrite common mode choke is inside the charger housing.

7. 2. The battery pack charging system of claim 1, wherein the nanocrystalline ferrite common mode choke is toroidal in shape.

8. 2. The battery pack charging system of claim 1, further comprising a differential mode choke pair including a first differential mode choke and a second differential mode choke, the differential mode choke pair being part of the filter circuit.

9. 9. The battery pack charging system of claim 8, further comprising a circuit board within the filter block housing, the differential mode choke pair and the nanocrystalline ferrite common mode choke disposed on the circuit board.

10. a battery pack interface configured to receive the battery pack; a charging circuit coupled to the battery pack interface and configured to provide a charging current to the battery pack interface; a controller coupled to the charging circuit and configured to control a supply of charging current to the battery pack interface; a power supply circuit coupled to the charging circuit; a charger housing that houses the charging circuit, the controller, and the power supply circuit; an AC plug configured for connection to an AC power source; a filter circuit external to the charger housing, the filter circuit including a nanocrystalline ferrite filter element, the filter circuit configured to connect the power supply circuit to the AC plug to provide AC power to the power supply circuit; a filter block housing that houses the filter circuit; a first power cable connecting the charger housing and the filter block housing; a second power cable connecting the filter block housing to the AC plug. Battery pack charging system.

11. 11. The battery pack charging system of claim 10 further comprising a second nanocrystalline ferrite filter element within the charger housing.

12. 12. The battery pack charging system of claim 11, wherein the second nanocrystalline ferrite filter element is in series with the nanocrystalline ferrite filter element.

13. a differential mode choke pair including a first differential mode choke and a second differential mode choke; Ferrite beads and The battery pack charging system of claim 10 further comprising:

14. 14. The battery pack charging system of claim 13, further comprising a circuit board within the filter block housing, the pair of differential mode chokes and a nanocrystalline ferrite common mode choke disposed on the circuit board.

15. 11. The battery pack charging system of claim 10, further comprising a ferrite bead disposed along the first power cable between a filter block housing and the charger housing.

16. 11. The battery pack charging system of claim 10, wherein the nanocrystalline ferrite filter element has a toroidal shape.

17. 11. The battery pack charging system of claim 10, further comprising a second nanocrystalline ferrite filter element disposed within the charger housing.

18. 11. The battery pack charging system of claim 10, wherein the nanocrystalline ferrite filter element is a nanocrystalline ferrite common mode choke.

19. 11. The battery pack charging system of claim 10, further comprising a differential mode choke pair including a first differential mode choke and a second differential mode choke, the differential mode choke pair being part of the filter circuit.

20. 1. A method for charging a battery pack, comprising: receiving a battery pack by a battery pack interface of a battery pack charger; receiving AC power at a power source of the battery pack charger via a power cable; converting the AC power to DC power by the power source; controlling, by an electronic controller, a supply of charging current to the battery pack interface for charging the battery pack; receiving an external signal on the power cable; filtering the extraneous signals on the power cable with a nanocrystalline ferrite toroidal choke; and housing the nanocrystalline ferrite toroidal choke and at least one differential mode choke in a filter block housing separate from a charger housing. method.

21. 21. The method of claim 20, wherein the nanocrystalline ferrite toroidal choke is a common mode choke.

22. filtering the extraneous signals on the power cable with at least one differential mode choke; 21. The method of claim 20, further comprising:

23. filtering the extraneous signals on the power cable; filtering the extraneous signals on the power cable through a first nanocrystalline ferrite toroidal choke configured to filter signals at a first frequency; filtering the extraneous signals on the power cable through a second nanocrystal toroidal choke configured to filter signals at a second frequency; and 21. The method of claim 20, comprising:

24. receiving alternating current power at the power source of the battery pack charger; receiving the AC power at an AC plug; supplying the AC power from the AC plug to the power source through a nanocrystalline ferrite toroidal choke and at least one differential mode choke; 21. The method of claim 20, comprising:

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