Patent Description:
Motion control systems utilizing movers and linear motors can be used in a wide variety of processes (e.g. packaging, manufacturing, and machining) and can provide an advantage over conventional conveyor belt systems with enhanced flexibility, extremely high speed movement, and mechanical simplicity. The motion control system includes a set of independently controlled "movers" each supported on a track for motion along the track. The track is made up of a number of track segments, and a linear drive system controls operation of the movers, causing the movers to travel along the track. Sensors may be spaced at fixed positions along the track and/or on the movers to provide information about the position and speed of the movers.

Each of the movers may be independently moved and positioned along the track in response to an electromagnetic field generated by the linear drive system. In a typical system, the track forms a closed path over which each mover repeatedly travels. At certain positions along the track other actuators may interact with each mover. For example, the mover may be stopped at a loading station at which a first actuator places a product on the mover. The mover may then be moved along a process segment of the track where various other actuators may fill, machine, position, or otherwise interact with the product on the mover. The mover may be programmed to stop at various locations or to move at a controlled speed past each of the other actuators. After the various processes are performed, the mover may pass or stop at an unloading station at which the product is removed from the mover. The mover then completes a cycle along the closed path by returning to the loading station to receive another unit of the product.

In certain applications, it may be desirable to provide an actuator or a sensor on the mover to interact with the product on the mover. For example, a clamp may actuate to secure the product to the mover or a sensor may detect the presence of the product on the mover. However, the actuator or sensor requires an energy source to operate. For electric actuators or sensors, the energy source may be a battery. For a hydraulic or pneumatic actuator, the energy source may be a pressurized tank. The energy source adds weight and takes up space on the mover. Further, the energy source needs to be periodically recharged.

One solution for providing energy to a mover is to provide a dedicated location along the track at which the energy is supplied. The mover stops at the dedicated location where a temporary connection to an energy source may be established. A first actuator external to the mover may engage the mover and establish an electrical, pneumatic, or hydraulic connection to the mover. A second actuator on the mover may perform the desired task, and the first actuator supplying power may subsequently disengage from the mover. This process, however, requires the mover to come to a stop at the dedicated location, wait for power to be connected, perform the desired action, and wait for the power to be disconnected before resuming motion. The additional steps required to supply power reduce the throughput of the system and the dedicated locations limit the ability of actuators or sensors present on a mover to operate.

Thus, it would be desirable to provide an improved system for supplying power to independent movers on a track in a motion control system.

Another solution for providing energy to a mover is to provide a fixed connection to the mover. The fixed connection may be, for example, an electrical conductor or a hydraulic or pneumatic hose. A fixed connection, however, is not without certain drawbacks. The motion of the mover is typically restricted to limit the required length of the electrical conductor or hose. The number of movers must be limited and/or the motion of the mover is limited to a reciprocal motion to avoid tangling the conductors or hoses between movers.

Thus, it would be desirable to provide a method and apparatus for wirelessly transmitting power between a track and independent movers in a motion control system to eliminate a fixed connection between the mover and a power source.

Historically, the linear drive system has included multiple coils spaced along the track and magnets mounted to each of the movers. The magnets on the movers may include multiple magnet segments with alternating north and south poles oriented to face the track. Each pair of north and south poles corresponds to a pole pair in the linear drive system. The coils along the track are sequentially energized with an alternating current which establishes an electromagnetic field around the coil. The electromagnetic field interacts with the magnetic field generated by the pole pairs on the movers and is controlled to drive the movers along the track. This arrangement, however, requires power converters corresponding to the coils spaced along the track to control the current through each coil. The linear drive system may require twice as many power converters as movers present on the track and include a significant portion of idle time while no mover is present over a coil controlled by the power converter.

Thus, it would be desirable to provide a system for wirelessly providing sufficient power to each mover to supply power to coils on the mover which, in turn, interact with magnets mounted along the track to control operation of each mover.

<CIT> relates to a conveyor system that includes a track section including a control system, a drive system that is controlled by the control system and that is configured to provide power through a first electromagnetic field and through an alternating second electromagnetic field, a plurality of moving elements that are driven by the drive system and that are configured to receive power through the first electromagnetic field, where at least one of the plurality of moving elements includes a pick-up unit configured to receive power through the alternating second electromagnetic field, a pallet support apparatus, and a plurality of pallets that are configured to engage with the plurality of moving elements and move on the pallet support apparatus.

<CIT> relates to an arrangement for providing a vehicle, in particular a track bound vehicle, with electric energy, wherein the arrangement comprises a receiving device adapted to receive an alternating electromagnetic field and to produce an alternating electric current by electromagnetic induction. The receiving device composes a plurality of windings and/or of electrically conducting material, wherein each winding or coil is adapted to produce a separate phase of the alternating electric current.

<CIT> relates to a method and apparatus for supplying contactless power. Electrical power is transferred from a power source to a load through a primary energy converter that can be connected to the power source, through a primary inductive loop connected to the magnetically coupled to the primary inductive loop, and then to a secondary energy converter. The power factor for the transfer of electrical energy is one. Multiple loads can receive power from the power source end, where the loads are located in zones, collisions between the loads can be prevented.

<CIT> relates to a linear-motion contactless power supply device for supplying electrical power from a stationary unit to a movable unit without direct contact; the stationary unit being a cylindrical primary conductor to which a high-frequency alternating current is supplied; the movable unit being provided with a secondary conductor which is isolated from the primary conductor and which is arranged coaxially with the primary conductor so as to be slidable in the longitudinal direction of and with respect to the primary conductor and also provided with a high-frequency toroidal core which is arranged so as to cover the secondary conductor from the outside.

<CIT> relates to a transport system comprising linear motor modules utilizing both straight and curved track modules, with movers displaced on the track modules by control of power applied to coils of the modules. Curved track modules have modified spline geometries to provide desired acceleration and jerk characteristics. The modified spline geometries may be defined by more than one generators, such as an equation generator and a spline fit between the equation-generated segment and one or more constrained points or locations. The curved track modules may be divided into <NUM> degree modules, or may be reduced to <NUM> degree, <NUM> degree or other fractional arcs to provide for modular assembly, mirror-image geometries and motion profiles, and the like. The system may be adapted to provide improved motion characteristics based on modification of a conventional spline geometry.

<CIT> relates to the contactless power supply for a looped track segment. The looped track segment includes a first primary coil and a second primary coil. The first and second primary coils are spaced-apart and are electrically connected to a driving circuit <NUM>. The driving circuit simultaneously drives the first primary coil with current in a first direction and the second primary coil with current in a second direction different from the first direction. The contactless power supply provides a source of wireless power for a portable device moving on the looped track. The portable device includes a secondary coil. The first and second primary coils of the track cooperate to induce a cumulative current in the secondary coil of the portable device. The secondary coil then provides power to an energy storage device, such as a battery or a capacitor, which in turn provides power to a load. It is important to note that the secondary coil of the portable device is generally orthogonal to the first and second primary coils of the looped track.

It is the object of the present invention to optimize energy provision for a mover in a linear drive system.

Various exemplary embodiments of the subject-matter disclosed herein are illustrated in the accompanying drawings in which like reference numerals represent like parts throughout, and in which:.

Tuming initially to <FIG>, an exemplary transport system for moving articles or products includes a track <NUM> made up of multiple segments <NUM>, <NUM>. According to the illustrated embodiment, the segments define a generally closed loop supporting a set of movers <NUM> movable along the track <NUM>. The track <NUM> is oriented in a horizontal plane and supported above the ground by a base <NUM> extending vertically downward from the track <NUM>. According to the illustrated embodiment, the base <NUM> includes a pair of generally planar support plates <NUM>, located on opposite sides of the track <NUM>, with mounting feet <NUM> on each support plate <NUM> to secure the track <NUM> to a surface. The illustrated track <NUM> includes four straight segments <NUM>, with two straight segments <NUM> located along each side of the track and spaced apart from the other pair. The track <NUM> also includes four curved segments <NUM> where a pair of curved segments <NUM> is located at each end of the track <NUM> to connect the pairs of straight segments <NUM>. The four straight segments <NUM> and the four curved segments <NUM> form a generally oval track and define a closed surface over which each of the movers <NUM> may travel. It is understood that track segments of various sizes, lengths, and shapes may be connected together to form a track <NUM> without deviating from the scope of the invention.

For convenience, the horizontal orientation of the track <NUM> shown in <FIG> will be discussed herein. Terms such as upper, lower, inner, and outer will be used with respect to the illustrated track orientation. These terms are relational with respect to the illustrated track and are not intended to be limiting. It is understood that the track may be installed in different orientations, such as sloped or vertical, and include different shaped segments including, but not limited to, straight segments, inward bends, outward bends, up slopes, down slopes and various combinations thereof. Further, each track segment <NUM>, <NUM> is shown in a generally horizontal orientation. The track segments <NUM>, <NUM> may also be oriented in a generally vertical orientation and the width of the track <NUM> may be greater in either the horizontal or vertical direction according to application requirements. The movers <NUM> will travel along the track and take various orientations according to the configuration of the track <NUM> and the relationships discussed herein may vary accordingly.

Each track segment <NUM>, <NUM> includes a number of independently attached rails <NUM> on which each mover <NUM> runs. According to the illustrated embodiment, rails <NUM> extend generally along the outer periphery of the track <NUM>. A first rail <NUM> extends along an upper surface <NUM> of each segment and a second rail <NUM> extends along a lower surface <NUM> of each segment. It is contemplated that each rail <NUM> may be a singular, molded or extruded member or formed from multiple members. It is also contemplated that the cross section of the rails <NUM> may be circular, square, rectangular, or any other desired cross-sectional shape without deviating from the scope of the invention. The rails <NUM> generally conform to the curvature of the track <NUM> thus extending in a straight path along the straight track segments <NUM> and in a curved path along the curved track segments <NUM>. The rails <NUM> may be thin with respect to the width of the track <NUM> and span only a partial width of the surface of the track <NUM> on which it is attached. According to the illustrated embodiment, each rail <NUM> includes a base portion <NUM> mounted to the track segment and a track portion <NUM> along which the mover <NUM> runs. Each mover <NUM> includes complementary rollers <NUM> to engage the track portion <NUM> of the rail <NUM> for movement along the track <NUM>.

One or more movers <NUM> are mounted to and movable along the rails <NUM> on the track <NUM>. With reference next to <FIG>, an exemplary mover <NUM> is illustrated. Each mover <NUM> includes a side member <NUM>, a top member <NUM>, and a bottom member <NUM>. The side member <NUM> extends for a height at least spanning a distance between the rail <NUM> on the top surface <NUM> of the track <NUM> and the rail <NUM> on the bottom surface <NUM> of the track <NUM> and is oriented generally parallel to a side surface <NUM> when mounted to the track <NUM>. The top member <NUM> extends generally orthogonal to the side member <NUM> at a top end of the side member <NUM> and extends across the rail <NUM> on the top surface <NUM> of the track <NUM>. The top member <NUM> includes a first segment <NUM>, extending orthogonally from the side member <NUM> for the width of the rail <NUM>, which is generally the same width as the side member <NUM>. A set of rollers <NUM> are mounted on the lower side of the first segment <NUM> and are configured to engage the track portion <NUM> of the rail <NUM> mounted to the upper surface <NUM> of the track segment. According to the illustrated embodiment two pairs of rollers <NUM> are mounted to the lower side of the first segment <NUM> with a first pair located along a first edge of the track portion <NUM> of the rail and a second pair located along a second edge of the track portion <NUM> of the rail <NUM>. The first and second edges and, therefore, the first and second pairs of rollers <NUM> are on opposite sides of the rail <NUM> and positively retain the mover <NUM> to the rail <NUM>. The bottom member <NUM> extends generally orthogonal to the side member <NUM> at a bottom end of the side member <NUM> and extends for a distance sufficient to receive a third pair of rollers <NUM> along the bottom of the mover <NUM>. The third pair of rollers <NUM> engage an outer edge of the track portion <NUM> of the rail <NUM> mounted to the lower surface <NUM> of the track segment. Thus, the mover <NUM> rides along the rails <NUM> on the rollers <NUM> mounted to both the top member <NUM> and the bottom member <NUM> of each mover <NUM>. The top member <NUM> also includes a second segment <NUM> which protrudes from the first segment <NUM> an additional distance beyond the rail <NUM> and is configured to hold a position magnet <NUM>. According to the illustrated embodiment, the second segment <NUM> of the top member <NUM> includes a first portion <NUM> extending generally parallel to the rail <NUM> and tapering to a smaller width than the first segment <NUM> of the top member <NUM>. The second segment <NUM> also includes a second portion <NUM> extending downward from and generally orthogonal to the first portion <NUM>. The second portion <NUM> extends downward a distance less than the distance to the upper surface <NUM> of the track segment but of sufficient distance to have the position magnet <NUM> mounted thereto. According to the illustrated embodiment, a position magnet <NUM> is mounted within a recess <NUM> on the second portion <NUM> and is configured to align with a sensor <NUM> mounted with in the top surface <NUM> of the track segment.

A linear drive system is incorporated in part on each mover <NUM> and in part within each track segment <NUM>, <NUM> to control motion of each mover <NUM> along the segment. According to one embodiment of the invention shown in <FIG>, the linear drive system includes drive magnets <NUM> mounted to the side member <NUM>. According to the illustrated embodiment, the drive magnets <NUM> are arranged in a block along an inner surface of the side member <NUM> with separate magnet segments alternately having a north pole, N, and south pole, S, pole facing the track segment <NUM>. The drive magnets <NUM> are typically permanent magnets, and two adjacent magnet segments including a north pole and a south pole may be considered a pole-pair. The drive magnets <NUM> are mounted on the inner surface of the side member <NUM> and when mounted to the track <NUM> are spaced apart from a series of coils <NUM> extending along the track <NUM>. As shown in <FIG>, an air gap <NUM> is provided between each set of drive magnets <NUM> and the coils <NUM> along the track <NUM>. On the track <NUM>, the linear drive system includes a series of parallel coils <NUM> spaced along each track segment <NUM> as shown in <FIG>. According to the illustrated embodiment, each coil <NUM> is placed in a channel <NUM> extending longitudinally along one surface of the track segment <NUM>. The electromagnetic field generated by each coil <NUM> spans the air gap <NUM> and interacts with the drive magnets <NUM> mounted to the mover <NUM> to control operation of the mover <NUM>.

According to another embodiment of the invention shown in <FIG>, the linear drive system includes drive magnets <NUM> mounted along the track. With reference also to <FIG>, the drive magnets <NUM> may be mounted in the channel <NUM> extending longitudinally along one surface of the track segment <NUM>. A set of drive coils <NUM> is mounted to each mover <NUM>. The drive coils <NUM> are mounted to the side member <NUM> and spaced apart from the drive magnets <NUM> such that an air gap <NUM> is defined between each set of drive coils <NUM> and the drive magnets <NUM> along the track. The drive magnets <NUM> are preferably arranged with consecutive magnet segments alternately having a north pole, N, and south pole, S, pole facing the mover <NUM>. The mover <NUM> further includes a motor drive <NUM> mounted to the side member <NUM> and, as illustrated, is positioned between the side member <NUM> and the drive coils <NUM>. As will be discussed in more detail below, the motor drive <NUM> receives power from the secondary winding of a sliding transformer configured to wirelessly transmit power between the track and each mover and delivers the power to the drive coils <NUM>. The motor drive <NUM> controls the voltage and/or current provided to each drive coil <NUM> such that an electromagnetic field generated by each drive coil <NUM> on the mover <NUM> interacts with the drive magnets <NUM> mounted along the track <NUM> to control motion of the mover <NUM> along the track. Mounting the motor drive <NUM> along the side member <NUM> allows the side member to serve as a heat sink for the motor drive <NUM>. However, it is contemplated that the motor drive <NUM> may be mounted in other locations on the mover <NUM> without deviating from the scope of the invention.

Turning again to <FIG> and <FIG>, a sliding transformer <NUM> provides wireless power transfer between the track <NUM> and a mover <NUM>. According to the illustrated embodiment, a primary winding <NUM> is provided on the track <NUM> and a secondary winding <NUM> is provided on the mover <NUM>. The primary winding <NUM> includes a forward conduction path <NUM> and a reverse conduction path <NUM> extending longitudinally along the track <NUM>. According to one embodiment of the invention, the forward and reverse conduction paths <NUM>, <NUM> may span multiple track segments <NUM>, <NUM>. An electrical connector may be provided between track segments <NUM>, <NUM> to establish a continuous electrical connection between segments <NUM>, <NUM>. In certain applications, such as a short oval, a single primary winding may be provided. One end for each of the forward and reverse conduction paths is connected to a power source and the other end for each of the forward and reverse conduction paths is electrical connected to each other to establish a conductive loop. In other applications, for example, due to an extended track length, it may be desirable to provide multiple primary windings <NUM>, where each primary winding extends for a portion of the length of the track <NUM>. According to one embodiment of the invention, each track segment <NUM>, <NUM> includes a separate primary winding <NUM> extending the length of the track segment.

The forward and reverse conduction paths <NUM>, <NUM> for the primary winding <NUM> may include either a single conductor or multiple conductors. With reference to <FIG>, a first bus bar <NUM> is provided in the forward conduction path <NUM> and a second bus bar <NUM> is provided in the reverse conduction path <NUM>. If a separate primary winding <NUM> is present on each track segment, one end of each bus bar <NUM>, <NUM> is connected to a power source and the other end of each bus bar may include an end cap joining the two bus bars and establishing a conductive loop. If the primary winding <NUM> spans multiple track segments, then an electrical connector may be provided between track segments to join adjacent bus bars. With reference to <FIG>, the primary winding <NUM> may also include multiple conductors in each of the forward and reverse conduction paths <NUM>, <NUM>. According to one embodiment of the invention, a single conductor may be wound along the length of the track segment <NUM> to form a coil. According to another embodiment of the invention, a printed circuit board (PCB) may be mounted along the length of the track segment <NUM> and a number of traces may be defined along the PCB to define the coil. In either embodiment, a first portion of the conductors define the forward conduction path <NUM> and a second portion of the conductors define the reverse conduction path <NUM>.

The secondary winding <NUM> includes a forward conduction path <NUM> and a reverse conduction path <NUM> extending in the direction of motion of the mover <NUM>. It is contemplated that each mover <NUM> will include a single secondary winding <NUM>. However, in some embodiments, multiple secondary windings <NUM> may be mounted on a mover <NUM> with each secondary winding <NUM> receiving power from the primary winding <NUM>. One end for each of the forward and reverse conduction paths is electrically connected to each other to establish a conductive loop and the other end supplies power to an electrical load on the mover <NUM>. It is contemplated that the electrical load may be an electrical device <NUM> such as an actuator or a sensor, which may be energized by either an alternating current (AC) voltage or a direct current (DC) voltage. A power converter <NUM> is provided to regulate the power flow received from the secondary winding <NUM> to the electrical load.

The forward and reverse conduction paths <NUM>, <NUM> for the secondary winding <NUM> may include either a single conductor or multiple conductors. With reference to <FIG>, a first bus bar <NUM> is provided in the forward conduction path <NUM> and a second bus bar <NUM> is provided in the reverse conduction path <NUM>. One end of each bus bar <NUM>, <NUM> is connected to the electrical load on the mover <NUM> and the other end of each bus bar may include an end cap joining the two bus bars and establishing a conductive loop. With reference to <FIG>, the secondary winding <NUM> may also include multiple conductors in each of the forward and reverse conduction paths <NUM>, <NUM>. According to one embodiment of the invention, a single conductor may be wound along the mover <NUM> in the direction of travel of the mover <NUM> to form a coil. According to another embodiment of the invention, a printed circuit board (PCB) may be mounted to the mover <NUM> and a number of traces may be defined along the PCB to define the coil. In either embodiment, a first portion of the conductors define the forward conduction path <NUM> and a second portion of the conductors define the reverse conduction path <NUM>.

Turning next to <FIG>, an exemplary power converter <NUM> for supplying power to the primary winding <NUM> is illustrated. The power converter <NUM> is configured to receive a three-phase AC voltage <NUM> at an input <NUM> of the power converter. The three-phase AC voltage <NUM> is, in turn, provided to a rectifier section <NUM> of the power converter <NUM>. The rectifier section <NUM> may include any electronic device suitable for passive or active rectification as is understood in the art. According to the illustrated embodiment, the rectifier section <NUM> includes a set of diodes <NUM> forming a diode bridge that rectifies the three-phase AC voltage to a DC voltage on the DC bus <NUM>. Optionally, the rectifier section <NUM> may include other solid-state devices including, but not limited to, thyristors, silicon controlled rectifiers (SCRs), or transistors to convert the input voltage <NUM> to a DC voltage for the DC bus <NUM>. The DC voltage is present between a positive rail <NUM> and a negative rail <NUM> of the DC bus <NUM>. A DC bus capacitor <NUM> is connected between the positive and negative rails, <NUM> and <NUM>, to reduce the magnitude of the ripple voltage resulting from converting the AC voltage to a DC voltage. It is understood that the DC bus capacitor <NUM> may be a single capacitor or multiple capacitors connected in parallel, in series, or a combination thereof. The magnitude of the DC voltage between the positive and negative rails, <NUM> and <NUM>, is generally equal to the magnitude of the peak of the AC input voltage.

The DC bus <NUM> is connected in series between the rectifier section <NUM> and an inverter section <NUM>. The inverter section <NUM> consists of a number of switches <NUM>. Each switch <NUM> is preferably a solid-state switching element, such as a transistor, thyristor, or SCR as is known in the art. The switching element may also include a free-wheeling diode connected across the switching element. Each of the switches <NUM> receives a switching signal, sometimes referred to as a gating signal, <NUM> to selectively enable the switch <NUM> and to convert the DC voltage from the DC bus <NUM> into a controlled AC voltage at an output <NUM> of the inverter section <NUM>. When enabled, each switch <NUM> connects the respective rail <NUM>, <NUM> of the DC bus <NUM> to an output terminal. The primary winding <NUM> is connected to the output <NUM> of the inverter section to receive the controlled AC voltage as a power source for transmitting power from the track <NUM> to the movers <NUM>.

One or more modules are used to control operation of the power converter <NUM>. The modules may be stored programs executed on one or more processors, logic circuits, or a combination thereof. According to the illustrated embodiment, the power converter <NUM> includes a controller <NUM> and a memory device <NUM> in communication with the controller <NUM>. The controller <NUM> may be implemented, for example, in a microprocessor, application specific integrated circuit (ASIC), field programmable gate array (FPGA), or other such customizable device. The memory device <NUM> may include transitory memory, non-transitory memory or a combination thereof. The memory device <NUM> may be configured to store data and programs, which include a series of instructions executable by the controller <NUM>. It is contemplated that the memory device <NUM> may be a single device, multiple devices, or incorporated, for example, as a portion of another device such as an application specific integrated circuit (ASIC). The controller <NUM> is in communication with the memory <NUM> to read the instructions and data as required to control operation of the power converter <NUM>.

The controller <NUM> also receives feedback signals indicating the current operation of the power converter <NUM>. The power converter <NUM> may include a voltage sensor <NUM> and/or a current sensor <NUM> on the DC bus <NUM> generating a feedback signal corresponding to the magnitude of voltage and/or current present on the DC bus <NUM>. The power converter <NUM> may also include a voltage sensor <NUM> and/or a current sensor <NUM> generating a feedback signal corresponding to the magnitude of voltage and/or current present at the output <NUM> of the inverter section <NUM>. The controller <NUM> utilizes the feedback signals to generate the switching signals <NUM> to control operation of the inverter section <NUM> and to generate an output voltage having a desired magnitude and frequency for the primary winding <NUM>.

With reference also to <FIG>, the secondary winding <NUM> is spaced apart from the primary winding <NUM> by an air gap <NUM>. The current conducted in the primary winding <NUM> establishes an electromagnetic field along the forward and reverse conduction paths <NUM>, <NUM>. The forward and reverse conduction paths <NUM>, <NUM> of the secondary winding <NUM> are generally aligned with the forward and reverse conduction paths <NUM>, <NUM> of the primary winding <NUM> and separated by the air gap <NUM>. In order for a current to be induced within the secondary winding <NUM> by the electromagnetic field generated by the primary winding <NUM>, the secondary winding <NUM> must be located within the field. Thus, the air gap <NUM> is small and may be, for example, less than <NUM> millimeters wide and, preferably, is less than <NUM> millimeters wide. In one embodiment of the invention, it is contemplated that the air gap <NUM> is about <NUM> millimeters wide.

Referring again to <FIG>, the illustrated mover includes a rectifier section <NUM> with a set of diodes <NUM> to convert the AC voltage induced in the secondary winding <NUM> to a DC voltage present on a DC bus <NUM>. A DC bus capacitor <NUM> is connected between the positive and negative rails, <NUM> and <NUM>, to reduce the magnitude of the ripple voltage resulting from converting the AC voltage to a DC voltage. An electrical load <NUM> may is applied to the DC bus <NUM>. The power converter <NUM> on the track <NUM> is configured to regulate the voltage and/or current supplied to the primary ending <NUM> to, in turn, provide a desired power level to the electrical load <NUM>.

According to another embodiment of the invention, shown in <FIG>, the mover <NUM> may also include a power converter <NUM> to regulate power flow on the mover <NUM>. The power converter <NUM> is configured to receive the AC voltage from the secondary winding <NUM> at an input <NUM> of the power converter. The AC voltage is, in turn, provided to a rectifier section <NUM> of the power converter <NUM>. The rectifier section <NUM> may include any electronic device suitable for passive or active rectification as is understood in the art. According to the illustrated embodiment, the rectifier section <NUM> includes a set of diodes <NUM> forming a diode bridge that rectifies the AC voltage to a DC voltage on the DC bus <NUM>. Optionally, the rectifier section <NUM> may include other solid-state devices including, but not limited to, thyristors, silicon controlled rectifiers (SCRs), or transistors to convert the input voltage to a DC voltage for the DC bus <NUM>. The DC voltage is present between a positive rail <NUM> and a negative rail <NUM> of the DC bus <NUM>. A DC bus capacitor <NUM> is connected between the positive and negative rails, <NUM> and <NUM>, to reduce the magnitude of the ripple voltage resulting from converting the AC voltage to a DC voltage. It is understood that the DC bus capacitor <NUM> may be a single capacitor or multiple capacitors connected in parallel, in series, or a combination thereof. The magnitude of the DC voltage between the positive and negative rails, <NUM> and <NUM>, is generally equal to the magnitude of the peak of the AC input voltage.

The DC bus <NUM> is connected in series between the rectifier section <NUM> and a switching section <NUM>. It is contemplated that the switching section <NUM> may be configured to provide either an AC voltage output or a DC voltage output. The DC voltage output may be at a different voltage potential than the DC voltage potential present on the DC bus <NUM>. According to the illustrated embodiment, the switching section <NUM> is arranged as an inverter to provide an AC voltage output. The switching section <NUM> consists of a number of switches <NUM>. Each switch <NUM> is preferably a solid-state switching element, such as a transistor, thyristor, or SCR as is known in the art. The switching element may also include a free-wheeling diode connected across the switching element. Each of the switches <NUM> receives a switching signal, sometimes referred to as a gating signal, <NUM> to selectively enable the switch <NUM> and to convert the DC voltage from the DC bus <NUM> into a controlled AC voltage at an output <NUM> of the switching section <NUM>. When enabled, each switch <NUM> connects the respective rail <NUM>, <NUM> of the DC bus <NUM> to an output terminal. One or more electrical loads <NUM> are connected to the output <NUM> of the inverter section to receive the controlled AC voltage as a power source to enable operation of the device on the mover <NUM>.

The power converter <NUM> also receives feedback signals indicating the current operation of the power converter <NUM>. The power converter <NUM> may include a voltage sensor <NUM> and/or a current sensor <NUM> on the DC bus <NUM> generating a feedback signal corresponding to the magnitude of voltage and/or current present on the DC bus <NUM>. The power converter <NUM> may also include a voltage sensor <NUM> and/or a current sensor <NUM> generating a feedback signal corresponding to the magnitude of voltage and/or current present at the output <NUM> of the switching section <NUM>. The controller <NUM> utilizes the feedback signals to generate the switching signals <NUM> to control operation of the switching section <NUM> and to generate a desired output voltage for the load <NUM> present on the mover <NUM>.

As previously indicated, one embodiment of the linear drive system includes drive magnets <NUM> arranged along the track <NUM> and drive coils <NUM> mounted to each mover. With reference then to <FIG>, one arrangement of a controller for this embodiment of the linear drive system is illustrated. A sliding transformer is provided between the track <NUM> and each mover <NUM> in the manner discussed above. Each mover <NUM> further includes a motor drive <NUM> configured to receive power from the secondary winding <NUM> on the mover <NUM>.

The motor drive <NUM> is configured to receive an AC voltage from the secondary winding <NUM> at an input <NUM> of the motor drive. The AC voltage is, in turn, provided to a rectifier section <NUM> of the motor drive <NUM>. The rectifier section <NUM> may include any electronic device suitable for passive or active rectification as is understood in the art. According to the illustrated embodiment, the rectifier section <NUM> includes a set of diodes <NUM> forming a diode bridge that rectifies the three-phase AC voltage to a DC voltage on the DC bus <NUM>. Optionally, the rectifier section <NUM> may include other solid-state devices including, but not limited to, thyristors, silicon controlled rectifiers (SCRs), or transistors to convert the input voltage to a DC voltage for the DC bus <NUM>. The DC voltage is present between a positive rail <NUM> and a negative rail <NUM> of the DC bus <NUM>. A DC bus capacitor <NUM> is connected between the positive and negative rails, <NUM> and <NUM>, to reduce the magnitude of the ripple voltage resulting from converting the AC voltage to a DC voltage. It is understood that the DC bus capacitor <NUM> may be a single capacitor or multiple capacitors connected in parallel, in series, or a combination thereof. The magnitude of the DC voltage between the positive and negative rails, <NUM> and <NUM>, is generally equal to the magnitude of the peak of the AC input voltage.

The DC bus <NUM> is connected in series between the rectifier section <NUM> and an inverter section <NUM>. The inverter section <NUM> consists of a number of switches <NUM>. Each switch <NUM> is preferably a solid-state switching element, such as a transistor, thyristor, or SCR as is known in the art. The switching element may also include a free-wheeling diode connected across the switching element. Each of the switches <NUM> receives a switching signal, sometimes referred to as a gating signal, <NUM> to selectively enable the switch <NUM> and to convert the DC voltage from the DC bus <NUM> into a controlled AC voltage at an output <NUM> of the inverter section <NUM>. When enabled, each switch <NUM> connects the respective rail <NUM>, <NUM> of the DC bus <NUM> to an output terminal. The drive windings <NUM> are connected to the output <NUM> of the inverter section to receive the controlled AC voltage to establish an electromagnetic field to interact with the drive magnets <NUM> and control motion of the corresponding mover <NUM>.

One or more modules are used to control operation of the motor drive <NUM>. The modules may be stored programs executed on one or more processors, logic circuits, or a combination thereof. According to the illustrated embodiment, the motor drive <NUM> includes a controller <NUM> and a memory device <NUM> in communication with the controller <NUM>. The controller <NUM> may be implemented, for example, in a microprocessor, application specific integrated circuit (ASIC), field programmable gate array (FPGA), or other such customizable device. The memory device <NUM> may include transitory memory, non-transitory memory or a combination thereof. The memory device <NUM> may be configured to store data and programs, which include a series of instructions executable by the controller <NUM>. It is contemplated that the memory device <NUM> may be a single device, multiple devices, or incorporated, for example, as a portion of another device such as an application specific integrated circuit (ASIC). The controller <NUM> is in communication with the memory <NUM> to read the instructions and data as required to control operation of the motor drive <NUM>.

The motor drive <NUM> also receives feedback signals indicating the current operation of the motor drive <NUM>. The motor drive <NUM> may include a voltage sensor <NUM> and/or a current sensor <NUM> on the DC bus <NUM> generating a feedback signal corresponding to the magnitude of voltage and/or current present on the DC bus <NUM>. The motor drive <NUM> may also include a voltage sensor <NUM> and/or a current sensor <NUM> generating a feedback signal corresponding to the magnitude of voltage and/or current present at the output <NUM> of the inverter section <NUM>. The controller <NUM> utilizes the feedback signals to generate the switching signals <NUM> to control operation of the inverter section <NUM> and to generate a desired output voltage for each drive winding <NUM> present on the mover <NUM>.

It is further contemplated that a mover <NUM> with a motor drive <NUM> may also include one or more electronic devices mounted to the mover <NUM>. As illustrated, a load <NUM> is powered by a power converter <NUM>, separate from the motor drive <NUM>, also mounted to the mover <NUM>. The illustrated power converter <NUM> includes only a switching section <NUM> as described above with respect to <FIG>. The DC bus of the power converter <NUM> illustrated in <FIG> is connected directly to the DC bus <NUM> of the motor drive <NUM>. Optionally, the power converter <NUM> may include an input receiving power from the secondary winding <NUM> in the same manner as the power converter <NUM> of <FIG>. According to still another embodiment, the mover <NUM> may include multiple secondary windings <NUM>, where one secondary winding is connected to an input <NUM> of the motor drive <NUM> and another secondary winding is connected to an input of the power converter <NUM> for the additional load <NUM>.

In operation, the sliding transformer wirelessly provides power from the track <NUM> to each mover <NUM> travelling along the track <NUM>. According to one embodiment of the invention, a utility power supply <NUM> is connected to the primary winding <NUM>, as shown in <FIG>. The utility power supply <NUM> provides power at a fixed voltage and frequency and the power converter <NUM> on each mover <NUM> regulates power drawn from the secondary winding <NUM>. According to another embodiment of the invention, a power converter <NUM> is connected between a utility power supply and the primary winding <NUM>, as shown in <FIG>. The power converter <NUM> may be controlled to provide a voltage to the primary winding <NUM> with a variable voltage and/or a variable frequency. If the primary winding <NUM> spans multiple track segments, a single connection to the power supply is provided for each primary winding and suitable connectors are provided between segments to join the forward and reverse conduction paths. If a separate primary winding <NUM> is provided for each track segment <NUM>, a separate power converter <NUM> may be provided on each track segment to convert power from an input power source to a modulated voltage for the primary winding <NUM>.

At a fixed voltage level, for example, <NUM> VAC, the frequency of the voltage applied to the primary winding <NUM> impacts the amount of power transferred between the primary and secondary windings and also impacts the level of voltage ripple present at the secondary winding. With a utility power supply <NUM>, voltage is provided, for example, at <NUM> VAC and <NUM>. With a power converter <NUM> supplying power to the primary winding <NUM>, the output may be modulated to provide voltage at a higher frequency, ranging, for example, from <NUM>-<NUM>. According to one embodiment of the invention, the voltage is provided with a frequency in a range of <NUM>-<NUM>.

Increasing the frequency of the voltage supplied to the primary winding, impacts voltage coupling between the primary winding <NUM> and the secondary winding <NUM>. As the frequency of the voltage increases, the ripple on the voltage present on the secondary winding <NUM> decreases. As a result, the capacitance value for the DC bus capacitor <NUM> present on the mover <NUM> can be decreased. However, as the frequency increases, the amplitude of the voltage present on the secondary winding decreases and, therefore, the total power transferred similarly decreases. A comparison of the voltages and power present on the secondary winding of an exemplary sliding transformer is presented in Table <NUM> below. The amplitude of input voltage is constant at <NUM> VAC and the number of turns on the secondary winding is constant at sixty turns.

The power transferred between the primary winding <NUM> and the secondary winding <NUM> is further influenced by the number of turns present in the secondary winding. According to one embodiment of the invention, the number of turns present in the primary winding matches the number of turns present in the secondary winding to provide a <NUM>:<NUM> turns ratio. It is contemplated that various other turns ratios may be utilized without deviating from the scope of the invention. As the number of turns in the secondary winding <NUM> increases, the voltage level on the secondary winding decreases. However, as the number of turns in the secondary winding <NUM> increases, the magnitude of voltage ripple also decreases. Thus, to increase the power transferred between the primary and secondary windings, it is preferable to have a lower number of turns on the secondary winding. A comparison of the voltages and power present on the secondary winding of an exemplary sliding transformer as a result of different numbers of turns on the secondary winding is presented in Table <NUM> below. The amplitude of input voltage is constant at <NUM> VAC and the frequency of the input voltage is constant at sixty Hertz.

In addition, the present inventors have identified that the effect of increasing the frequency of the voltage supplied to the primary winding <NUM> has less impact on the voltage drop when the number of turns of the secondary winding <NUM> is decreased. For example, when the number of turns on the secondary winding is twenty turns, the average voltage remains about constant as the frequency of the voltage supplied to the primary winding increases. In fact, the average voltage increases slightly as the voltage ripple decreases providing an improved voltage on the secondary winding. A comparison of the voltages and power present on the secondary winding of another exemplary sliding transformer is presented in Table <NUM> below. The amplitude of input voltage is constant at <NUM> VAC and the number of turns on the secondary winding is constant at twenty turns.

According to one embodiment of the invention, each of the primary and secondary windings have the same number of turns and, therefore, have a <NUM>:<NUM> turns ratio. The primary winding <NUM> includes a first coil extending along the length of each track segment <NUM> and each mover <NUM> includes a secondary winding <NUM> having eighty or fewer turns and, preferably, between twenty and sixty turns. The primary winding is connected to a utility supply and, therefore, receives a fixed sixty hertz input voltage. Connecting the primary winding directly to the utility supply provides a reduced system cost by not requiring a power converter to supply a variable frequency voltage to each primary winding.

In alternate embodiments, however, it is contemplated that a power converter <NUM> is provided to supply a variable frequency voltage to the primary winding <NUM>. When a power converter is provided to supply voltage to the primary winding <NUM>, the frequency of the voltage may be supplied at <NUM> or greater and, preferably at <NUM> or greater. It is further contemplated that the turns ratio between the primary and secondary windings may be varied.

Claim 1:
An apparatus for wireless power transfer in a motion control system, the apparatus comprising:
a plurality of movers (<NUM>);
a plurality of electrical devices (<NUM>), wherein at least one of the electrical devices is mounted to each of the plurality of movers;
a closed track (<NUM>) defining a continuous path along which each of the plurality of movers travels; and
a primary winding (<NUM>) mounted along the closed track including a primary forward conduction path (<NUM>) and a primary reverse conduction path (<NUM>), wherein one end for each of the primary forward and reverse conduction paths is connected to each other to establish a conductive loop, wherein the primary winding is configured to receive power from a power supply (<NUM>),
wherein the primary forward conduction path and the primary reverse conduction path are spaced apart from each other and extend longitudinally in a direction of travel along the continuous path,
wherein the apparatus further comprises a plurality of secondary windings (<NUM>), wherein:
each secondary winding is mounted to one of the plurality of movers,
each secondary winding includes a secondary forward conduction path (<NUM>) and a secondary reverse conduction path (<NUM>), wherein one end for each of the secondary forward and reverse conduction paths is electrically connected to each other to establish a conductive loop,
the secondary forward conduction path and the secondary reverse conduction path are spaced apart from each other and extend along the mover in the direction of travel, and
each of the secondary forward and reverse conduction paths are aligned with the primary forward and reverse conduction paths with an air gap (<NUM>) separating the secondary forward and reverse conduction paths from the primary forward and reverse conduction paths as the mover travels along the closed track; and
a plurality of power converters (<NUM>), wherein each of the plurality of power converters is mounted to one of the plurality of movers and is operative to receive power from the secondary winding mounted to the mover and to supply power to the at least one electrical device mounted on the mover.