Systems and methods for controlling electric motors

An electronic control module is provided. The electronic control module includes an input device, and a processor coupled to the input device. The processor is configured to generate a command signal in response to an input supplied by the input device, and transmit the command signal to a plurality of motors, wherein the command signal controls an operating point of each of the plurality of motors.

BACKGROUND OF THE DISCLOSURE

The field of the invention relates generally to electric motors, and more specifically, to controlling a plurality of electric motors using an electronic control module.

Electric motors are used in a variety of systems operating in a variety of industries. For example, electric motors are used to power products such as fans used in heating, ventilation and air conditioning systems (HVAC). At least some known systems include a plurality of motors each operating at a respective operating point.

In at least some known systems including a plurality of motors, each motor includes its own onboard controller. That is, each motor is controlled independent of other motors in the system. Accordingly, to change the operating point of multiple motors in at least some known systems, each motor must be separately reprogrammed. Further, with each motor controlled independently, it may be relatively difficult to operate each motor at the same operating point. Moreover, motors with sophisticated onboard controllers may be relatively expensive, and systems including multiple motors may require different models of motors for separate applications, further increasing costs associated with such systems.

BRIEF DESCRIPTION

In one aspect, an electronic control module is provided. The electronic control module includes an input device, and a processor coupled to the input device. The processor is configured to generate a command signal in response to an input supplied by the input device, and transmit the command signal to a plurality of motors, wherein the command signal controls an operating point of each of the plurality of motors.

In another aspect, a motor control system is provided. The motor control system includes a plurality of motors, and an electronic control module coupled to the plurality of motors, the electronic control module including an input device, and a processor coupled to the input device. The processor is configured to generate a command signal in response to an input supplied by said input device, and transmit the command signal to the plurality of motors, wherein the command signal controls an operating point of each of the plurality of motors.

In yet another aspect, a method for controlling a plurality of motors is provided. The method includes receiving an input at an electronic control module, generating, using the electronic control module, a command signal in response to the input, and transmitting the command signal to a plurality of motors coupled to the electronic control module. The method further includes determining, from the command signal, a corresponding operating point for each motor, and operating each of the plurality of motors at the respective operating point.

DETAILED DESCRIPTION

The methods and systems described herein facilitate controlling a plurality of motors using an electronic control module. As described herein, the electronic control module transmits a command signal to each of a plurality of motors, and the command signal controls an operating point of each motor. Accordingly, by adjusting the command signal, the operating points for each of the plurality of motors can be adjusted simultaneously.

Technical effects of the methods and systems described herein include at least one of: (a) receiving an input; (b) generating a command signal in response to the input; (c) transmitting the command signal to a plurality of motors; (d) determining, from the command signal, a corresponding operating point for each motor; and (e) operating each of the plurality of motors at the respective operating point.

FIG. 1is an exploded view of an exemplary motor10. Motor10includes control system11, a stationary assembly12including a stator or core14, and a rotatable assembly16including a permanent magnet rotor18and a shaft20. In the exemplary embodiment, motor10is used in a heating, ventilating and air conditioning system (not shown), and control system11is integrated with motor10. Alternatively, motor10may be external to and/or separate from control system11.

Rotor18is mounted on and keyed to shaft20journaled for rotation in conventional bearings22. Bearings22are mounted in bearing supports24integral with a first end member26and a second end member28. End members26and28have inner facing sides30and32between which stationary assembly12and rotatable assembly16are located. Each end member26and28has an outer side34and36opposite its inner side30and32. Additionally, second end member28has an aperture38for shaft20to extend through outer side34.

Rotor18comprises a ferromagnetic core40and is rotatable within stator14. Segments42of permanent magnet material, each providing a relatively constant flux field, are secured, for example, by adhesive bonding to rotor core40. Segments42are magnetized to be polarized radially in relation to rotor core40with adjacent segments42being alternately polarized as indicated. While magnets on rotor18are illustrated for purposes of disclosure, it is contemplated that other rotors having different constructions and other magnets different in both number, construction, and flux fields may be utilized with such other rotors within the scope of the invention.

Stationary assembly12comprises a plurality of winding stages44adapted to be electrically energized to generate an electromagnetic field. Stages44are coils of wire wound around teeth46of laminated stator core14. Winding terminal leads48are brought out through an aperture50in first end member26terminating in a connector52. While stationary assembly12is illustrated for purposes of disclosure, it is contemplated that other stationary assemblies of various other constructions having different shapes and with different number of teeth may be utilized within the scope of the invention.

Motor10further includes an enclosure54which mounts on the rear portion of motor10. Control system11includes a plurality of electronic components58and a connector (not shown inFIG. 1) mounted on a component board60, such as a printed circuit board. Control system11is connected to winding stages44by interconnecting connector52. Control system11applies a voltage to one or more of winding stages44at a time for commutating winding stages44in a preselected sequence to rotate rotatable assembly16about an axis of rotation.

Connecting elements62include a plurality of bolts that pass through bolt holes64in second end member28, bolt holes66in core14, bolt holes68in first end member26, and bolt holes70in enclosure44. Connecting elements62are adapted to urge second end member28and enclosure44toward each other thereby supporting first end member26, stationary assembly12, and rotatable assembly16therebetween. Additionally, a housing72is positioned between first end member26and second end member28to facilitate enclosing and protecting stationary assembly12and rotatable assembly16.

Motor10may include any even number of rotor poles and the number of stator poles are a multiple of the number of rotor poles. For example, the number of stator poles may be based on the number of phases. In one embodiment (not shown), a three-phase motor10includes six rotor pole pairs and stator poles.

FIG. 2is a schematic diagram of an exemplary motor control system200that includes an electronic control module202that controls a plurality of motors204, such as motor10(shown inFIG. 1). In the exemplary embodiment, six motors204are controlled by electronic control module202. Alternatively, electronic control module202may control any number of motors204that enables motor control system200to function as described herein.

Each motor204is connected to electronic control module202via a first lead210, a second lead212, and a third lead214in the exemplary embodiment. First and second leads210and212are line voltage inputs, and third lead214is a high-voltage command lead, as described in detail herein. In the exemplary embodiment, motors204are utilized as fan and/or blower motors in a fluid (e.g., water, air, etc.) moving system. For example, motors204may be utilized in a clean room filtering system, a fan filter unit, a variable air volume system, a refrigeration system, a furnace system, an air conditioning system, and/or a residential or commercial heating, ventilation, and air conditioning (HVAC) system. Alternatively, motors204may be implemented in any application that enables electric motor control system200to function as described herein. Motors204may also be used to drive mechanical components other than a fan and/or blower, including mixers, gears, conveyors, and/or treadmills.

Electronic control module202receives a line voltage from first and second line voltage inputs220and222. The line voltage may be, for example, 115 Volts at a frequency of 50 Hz or 60 Hz, or 208-230 Volts at 50 Hz or 60 Hz. The line voltage from first and second line voltage inputs220and222is provided to each motor204through first and second leads210and212.

In the exemplary embodiment, electronic control module202is powered by a 24 Volt direct current input224and a circuit common input226. Alternatively, electronic control module202may operate using the alternating current line voltage supplied by first and second line voltage inputs220and222.

Electronic control module202controls motors204by transmitting a command signal to each motor204through third lead214. The same command signal is provided to each motor204simultaneously by electronic control module202. In the exemplary embodiment, command signal is one or more high-voltage pulses transmitted at the line voltage frequency. Motors204receive the command signal and determine a corresponding operating point, as described in detail herein.

Electronic control module202includes at least one memory device230and a processor232that is communicatively coupled to memory device230for executing instructions. In some embodiments, executable instructions are stored in memory device230. In the exemplary embodiment, electronic control module202performs one or more operations described herein by programming processor232. For example, processor232may be programmed by encoding an operation as one or more executable instructions and by providing the executable instructions in memory device230.

Processor232may include one or more processing units (e.g., in a multi-core configuration). Further, processor232may be implemented using one or more heterogeneous processor systems in which a main processor is present with secondary processors on a single chip. As another illustrative example, processor232may be a symmetric multi-processor system containing multiple processors of the same type. Further, processor232may be implemented using any suitable programmable circuit including one or more systems and microcontrollers, microprocessors, reduced instruction set circuits (RISC), application specific integrated circuits (ASIC), programmable logic circuits, field programmable gate arrays (FPGA), and any other circuit capable of executing the functions described herein. In the exemplary embodiment, processor232controls operation of electronic control module202.

In the exemplary embodiment, memory device230is one or more devices that enable information such as executable instructions and/or other data to be stored and retrieved. Memory device230may include one or more computer readable media, such as, without limitation, dynamic random access memory (DRAM), static random access memory (SRAM), a solid state disk, and/or a hard disk. Memory device230may be configured to store, without limitation, application source code, application object code, source code portions of interest, object code portions of interest, configuration data, execution events and/or any other type of data. In the exemplary embodiment, memory device230includes firmware and/or initial configuration data for electronic control module202.

To control the command signal sent to motors204, electronic control module202includes a switching panel250coupled to processor232that enables a user to select the operating point for motors204. As used herein, an operating point for a motor204includes at least a speed and a rotation direction. In the exemplary embodiment, to specify the operating point, switching panel250includes a range switch252, a speed switch254, and a rotation switch256. Alternatively, switching panel250may include any switches and/or controls that enable motor control system200to function as described herein.

In the exemplary embodiment, range switch252selects a range of speeds, and speed switch254specifies a discrete speed within the selected range. In one example, range switch252selects one of eight 400 revolution per minute (RPM) ranges, and speed switch254selects one of sixteen speeds within the selected 400 RPM range. Table 1 shows the selectable speeds in this example, where range switch252has eight settings and speed switch254has sixteen settings. Alternatively, range switch252and speed switch254may be set to select any ranges and/or speeds that enable motor control system200to function as described herein.

Range switch252is set using a 0-24 VDC analog control input260in the exemplary embodiment. That is, different input voltage ranges correspond to different settings (e.g., 0.0-3.0 Volts is setting “1”, 3.1-6.0 Volts is setting “2”, etc.). In the exemplary embodiment, speed switch254is a sixteen-setting hexadecimal switch, and each setting specifies a discrete speed. Alternatively, range switch252and/or speed switch254may be any switching devices that enable motor control system200to function as described herein.

Rotation switch256selects a rotation direction (i.e., clockwise or counterclockwise) for motors204. In the exemplary embodiment, rotation switch256is a two-setting toggle switch. Alternatively, rotation switch256may be any switching device that enables motor control system200to function as described herein.

In the exemplary embodiment, an operating point is set by the combined settings of range switch252, speed switch254, and rotation switch256. Alternatively, other control schemes may be used. For example, in one embodiment, the operating point may be set solely by analog control input260, where an input voltage range correlates to both a speed and rotation direction. In another embodiment, the operating point may be set solely using a hexadecimal switch, with each setting correlating to both a speed and rotation direction. In yet another embodiment, the operating point may be set in response to a signal received from a sensor device (e.g., a temperature sensor, a pressure sensor, etc.). As will be appreciated by those of skill in the art, a variety of control schemes may be used to select an operating point.

In response to the settings specified on switching panel250, processor232generates and transmits the corresponding command signal to motors204via third leads214. Each motor204receives the command signal and determines the corresponding operating point. In the exemplary embodiment, each motor204includes a look-up table270stored on a memory device similar to memory device230. Look-up table270lists a plurality of predetermined operating points and the number of high-voltage pulses in a predetermined command signal corresponding to each operating point. Accordingly, using a processing device similar to processor232, each motor204receives the command signal, counts the number of high-voltage pulses in the command signal, and determines a corresponding operating point using look-up table270. Using the processing device or another control device, each motor204operates at the determined operating point.

In the exemplary embodiment, each motor204has an identical look-up table270. That is, in response to receiving the command signal, each motor204will operate at the same operating point. Alternatively, different motors204may have look-up tables270with different values. Accordingly, although all motors204receiving the same command signal, the motors204may operate at different operating points. In the exemplary embodiment, look-up tables270also specify a default operating point. More specifically, when no command signal is received from electronic control module202, motors204operate at the default operating point. Motors204may have the same or different default operating points.

Electronic control module202includes an indicator280in the exemplary embodiment. Indicator280indicates whether a command signal is being transmitted to motors204. Indicator280may include any audio and/or visual device that provides an indication, such as, for example, a speaker, a light emitting diode (LED), etc.

FIG. 3is a flow chart of an exemplary method300for controlling a plurality of motors. An input is received302at an electronic control module, such as electronic control module202(shown inFIG. 2). The input may be, for example, a setting from a switch, such as switches252,254, and256(shown inFIG. 2). In response to the input, the electronic control module generates304a command signal. In the exemplary embodiment, the command signal is one or more high-voltage pulses.

The command signal is transmitted306to a plurality of motors coupled to the electronic control module, such as motors204(shown inFIG. 2). Based on the received command signal, each motor determines308a corresponding operating point. The operating point may be determined308using a look-up table, such as look-up tables270(shown inFIG. 2). In the exemplary embodiment, the operating point defines a speed and a direction of rotation for the motor. Using a processor or other control device, each motor is operated310at the respective operating point determined for that motor.

As compared to at least some known electric motor systems, the methods and systems described herein utilize a single electronic control module to simultaneously control a plurality of motors. Accordingly, an operating point of each of the plurality of motors can be adjusted by changing a command signal transmitted from the electronic control module. In contrast, in at least some known electric motor systems, each motor must be independently reprogrammed to adjust its operating point. Moreover, using the methods and systems described herein, the plurality of motors can all be set to operate at the same operating point. Further, as compared to at least some known electric motor systems, the electronic control module provides a configurable interface that facilitates adjustment of the command signal. Finally, if a motor in the systems described herein fails, a replacement motor can be swapped in relatively quickly and easily.

The systems and methods described herein facilitate efficient and economical manufacture and operation of an electric motor system. Exemplary embodiments of methods and systems are described and/or illustrated herein in detail. The methods and systems are not limited to the specific embodiments described herein, but rather, components of each system, as well as steps of each method, may be utilized independently and separately from other components and steps described herein. Each component, and each method step, can also be used in combination with other components and/or method steps.

When introducing elements/components/etc. of the methods and systems described and/or illustrated herein, the articles “a”, “an”, “the”, and “said” are intended to mean that there are one or more of the element(s)/component(s)/etc. The terms “comprising”, “including”, and “having” are intended to be inclusive and mean that there may be additional element(s)/component(s)/etc. other than the listed element(s)/component(s)/etc.