Patent Description:
Conveyance systems, such as elevator systems, use machines to impart force to a car carrying passengers. The machines employed may need to provide varying power levels depending on the application. When an elevator requires a large elevator duty or load, a drive needs be provided to power the elevator machine. Often, a high power drive may not exist, which results in high design costs and lengthy development time to manufacture a suitable drive. Even if a single, large drive exists in the marketplace, costs associated with a single, large drive may be excessive due to specialty components, component availability, etc..

<CIT> discloses the preamble of claim <NUM> and shows a converter rectifying <NUM>-phase AC supplied from a power source unit. An inverter converts DC rectified from the converter into AC. A filter unit filters power converted by the inverter and supplies the filtered power to a nine-phase motor. Three three-phase electric motor drives provide current to the nine-phase motor.

Disclosed is an elevator drive system as defined in claim <NUM>, including a permanent magnet (PM) synchronous electric motor including a plurality of phases, and a plurality of motor drives electrically connected to the PM synchronous electric motor. Each of the plurality of motor drives is operatively connected to a corresponding one of the plurality of phases. The plurality of motor drives is configured and disposed to deliver a torque current divided equally between each of the plurality of phases and independently deliver flux current to the corresponding one of the plurality of phases. A controller is operatively connected to each of the plurality of motor drives to selectively control the PM synchronous electric motor, and a rescue module operatively connected to the controller. The rescue module is configured and disposed to determine a failure of one of the plurality of motor drives and control the PM synchronous electric motor in a reduced operation profile employing remaining ones of the plurality of motor drives.

One of the plurality of motor drives is a primary motor drive and remaining ones of the plurality of motor drives are secondary motor drives The primary motor drive is configured to communicate with each secondary motor drive to establish a desired field orientation angle for each secondary motor drive as well as to provide a desired torque current command; and the primary motor drive is configured to communicate velocity commands; prepare to run commands; as well as any synchronization logic.

Further embodiments could include wherein the rescue module designates one of the secondary motor drives as a temporary primary motor drive in the event of a failure of the primary motor drive.

Further embodiments could include wherein upon determining a failure of one of the plurality of motor drives, the rescue module is configured and disposed to signal remaining ones of the plurality of motor drives to deliver a torque current divided equally between each of the plurality of phases associated with the remaining ones of the plurality of motor drives.

Further embodiments could include wherein the rescue module is configured and disposed to signal the remaining ones of the plurality of motor drives to adjust flux current to account for the failure of the one of the plurality of motor drives.

Also disclosed is an elevator system as defined in claim <NUM>, including a hoistway, a car movably arranged with the hoistway, and an elevator drive system as described above, operatively connected to the car.

Further disclosed is a method of operating such an elevator system, as defined in claim <NUM>. The method includes identifying one of the plurality of motor drives as a faulty drive, initiating a reduced operation profile for remaining ones of the plurality of motor drives, determining whether continued reduced operation profile operation is indicated, and moving an elevator car to a rescue floor if continued reduced profile operation is contraindicated.

Further embodiments could include wherein identifying one of the plurality of motor drives as a faulty motor drive includes identifying whether the faulty motor drive is one of a primary motor drive and a secondary motor drive.

Further embodiments could include designating a secondary motor drive as a temporary primary motor drive if the faulty motor drive is the primary motor drive.

Further embodiments could include distributing torque current substantially equally to the associated ones of the plurality of phases through the remaining ones of the plurality of motor drives.

Further embodiments could include signaling the remaining ones of the plurality of motor drives to adjust flux current to account for the failure of the one of the plurality of motor drives.

Further embodiments could include wherein moving the elevator car to a rescue floor includes moving the elevator car along a hoistway to a next adjacent floor.

Further embodiments could include determining a load in the elevator car relative to a weight of a counterweight of the elevator system.

Further embodiments could include shifting the elevator car upward to the next adjacent floor if the load in the elevator car is less than the weight of the counterweight.

Further embodiments could include shifting the elevator car downward to the next adjacent floor if the load in the elevator car is greater than the weight of the counterweight.

Further embodiments could include wherein determining whether continued reduced operation profile operation is indicated includes determining one of a number of motor drive failures, a type of motor drive failure and a designation of each failed motor drive.

A traction elevator system, in accordance with an exemplary embodiment, is illustrated generally at <NUM>, in <FIG>. Features of elevator system <NUM> that are not required for an understanding of the present disclosure (such as the guide rails, safeties, etc.) are not discussed herein. Elevator system <NUM> includes an elevator car <NUM> operatively suspended or supported in a hoistway <NUM> with a belt or rope <NUM>. It should be understood that the number and/or arrangement of belts <NUM> could vary. Belt <NUM> interacts with one or more sheaves <NUM> to be routed around various components of the elevator system <NUM>. Belts <NUM> could also be connected to a counterweight <NUM>, which is used to help balance the elevator system <NUM> and reduce differences in belt <NUM> tension during operation.

Sheaves <NUM> each have a diameter <NUM>, which may be the same or different than the diameters of the other sheaves <NUM> in the elevator system <NUM>. At least one of sheaves <NUM> could be a traction sheave <NUM>. Traction sheave <NUM> is driven by a machine system <NUM>. Movement of traction sheave <NUM> by machine system <NUM> drives, moves and/or propels (through traction) belt <NUM>. <FIG> depicts a <NUM>:<NUM> roping arrangement. However, it should be understood that elevator system <NUM> may include various different roping arrangements including <NUM>:<NUM> roping arrangements. Exemplary embodiments may also employ a cantilevered type elevator car.

In accordance with an aspect of an exemplary embodiment illustrated in <FIG>, machine system <NUM> includes an electric motor <NUM>. Electric motor <NUM> takes the form of a permanent magnet (PM) synchronous electric motor including a brake <NUM> and an encoder <NUM>. PM synchronous electric motor <NUM> is operatively coupled to an elevator drive system <NUM> having a controller <NUM> and a plurality of motor drives <NUM>. Motor drives <NUM> include a primary motor drive <NUM> and one or more secondary motor drives <NUM>. Controller <NUM> delivers signals to primary motor drive <NUM> which, in turn, may deliver signals to secondary motor drives <NUM> as will be detailed more fully below.

In accordance with an aspect of an exemplary embodiment, elevator drive system <NUM> includes a three-phase or line voltage input <NUM>. Primary motor drive <NUM> includes a three-phase output <NUM> and each secondary motor drive <NUM> includes a corresponding three-phase output <NUM> and <NUM>. Additionally, primary motor drive <NUM> and each secondary motor drive <NUM> include a dedicated, independent, e.g., not shared, ground <NUM>. In further accordance with an aspect of an exemplary embodiment, each three-phase output <NUM>, <NUM> and <NUM> is independent of others of three-phase outputs <NUM>, <NUM> and <NUM> and connects to a separate independent winding (not separately labeled) of PM synchronous electric motor <NUM>. Further, it should be understood that the number of motor drives and corresponding independent three-phase outputs passing to PM synchronous electric motor <NUM> could vary. For example, PM synchronous electric motor <NUM> could be powered solely by primary motor drive <NUM> and secondary motor drive <NUM> representing a six-phase motor. In other embodiments, three-phase output <NUM> may establish a nine-phase configuration, or a twelve-phase configuration.

In further accordance with an aspect of an exemplary embodiment, primary motor drive <NUM> is operatively connected to each secondary motor drive <NUM> through a corresponding first control line <NUM>. Primary motor drive <NUM> is also connected to brake <NUM> through a second control line <NUM> and to an encoder <NUM> through a third control line <NUM>. With this arrangement, primary motor drive <NUM> communicates with controller <NUM> and provides converter control for PM synchronous electric motor <NUM> as well as inverter control. Primary motor drive <NUM> also interacts with PM synchronous electric motor <NUM> to regulate current, and voltage as well as provide velocity control, brake control, and a locked rotor test (LRT) for PM synchronous electric motor <NUM>.

Primary motor drive <NUM> communicates with each secondary motor drive <NUM> to establish/set a desired field orientation angle for each secondary motor drive <NUM> as well as to provide a desired torque current command. Primary motor drive <NUM> also communicates velocity commands; prepare to run commands; as well as any synchronization logic. In this manner, torque current (Q-Axis) to PM synchronous electric motor <NUM> may be divided substantially equally between each secondary motor drive <NUM> and flux current (D-Axis) may be independently controlled by each secondary motor drive <NUM>.

In accordance with an aspect of an exemplary embodiment, controller <NUM> includes a rescue module <NUM> that monitors operation of primary motor drive <NUM> and each secondary motor drive <NUM>. Rescue module <NUM> may form part of controller <NUM> or may represent a separate element operatively connected to controller <NUM>. As will be detailed more fully below, rescue module <NUM> may activate a rescue operation for elevator car <NUM> in the event of an operational error in primary motor drive <NUM> and/or one or more of secondary motor drives <NUM>. For example, in the event that primary motor drive <NUM> experiences an operational error, rescue module <NUM> may re-designate one of secondary motor drives <NUM> as a temporary primary motor drive in order to operate at a reduced profile. Temporary primary motor drive will operate as the primary motor drive and operations may be spread through remaining ones of secondary motor drives <NUM>. Likewise, in the event of a failure of one of secondary motor drives <NUM>, operations may be re-distributed to remaining ones of secondary motor drives <NUM> and/or primary motor drive <NUM>.

Reference will now follow to <FIG> in describing a method <NUM> of rescuing an elevator car in accordance with an exemplary embodiment. A drive failure may be detected in block <NUM>. The drive failure may be detected by controller <NUM> and/or rescue module <NUM>. In block <NUM> the drive failure is identified as being associated with primary motor drive <NUM> and/or any one of secondary motor drives <NUM>. In block <NUM>, rescue module <NUM> may identify a failure type and in block <NUM> a reduced operation profile is initiated.

In further accordance with an exemplary embodiment, a determination is made, in block <NUM>, whether continued reduced profile operation is indicated, or whether the elevator car <NUM> should be brought to a rescue floor and further operation suspended. The determination of whether continued or prolonged reduced profile operation may be appropriate may take into account failure type, number and type, e.g., designation as primary or secondary, of a failed drive or drives, etc. If continued reduced profile operation is indicated in block <NUM>, controller <NUM> will continue to shift elevator car <NUM> in response to call button inputs in a reduced operation mode in block <NUM> until any necessary repairs are made and reduced profile operation ends in block <NUM>.

If continued reduced profile operation is contraindicated in block <NUM>, rescue module <NUM> may determine a load value in elevator car <NUM> in block <NUM>. After determining a load value, rescue module <NUM> may control machine system <NUM> in the reduced profile operation for the purpose of shifting elevator car <NUM> to a rescue floor in block <NUM>. A rescue floor may be a next adjacent floor. If for example elevator car <NUM> is light, e.g., the load value of elevator car <NUM> is less than a weight of counterweight <NUM>, rescue module <NUM> may direct elevator car <NUM> upward to the next adjacent floor. Conversely, if the load value of elevator car <NUM> is greater than that of counterweight <NUM>, rescue module <NUM> may direct elevator car <NUM> downward to the next adjacent floor. After being directed to the rescue floor, elevator car <NUM> may be taken out of service until any necessary repairs can be made and rescue operations ended in block <NUM>.

At this point, it should be understood that exemplary embodiments describe a multi-drive control for a PM synchronous electric motor. The multi-drive control includes a number of secondary motor drives communicating with a single primary motor drive. Further, each motor drive includes an independent, multi-phase output to a separate independent winding of the PM synchronous electric motor. Further, the multi-drive system maintains no common neutrals between motor drives. Thus, in the event of a failure of one of the motor drives, the primary motor drive may maintain control of the PM synchronous electric motor, re-divide the torque current through any remaining secondary motor drives and associated phases, and establish a new flux current angle to allow continued operation. If a failure occurs in the primary motor drive, one of the secondary motor drives may be re-designated as a primary motor drive to provide continued control. When employed in an elevator system, the exemplary embodiments provide control over movement of the elevator car in the event of a failure of one or more of the motor drives. In this manner, the elevator car may be operated at reduced capacity and/or moved to a floor and parked until repairs may be completed.

Claim 1:
An elevator drive system (<NUM>) comprising:
a permanent magnet synchronous electric motor (<NUM>) including a plurality of phases;
a plurality of motor drives (<NUM>) electrically connected to the permanent magnet synchronous electric motor (<NUM>), each of the plurality of motor drives (<NUM>) being operatively connected to a corresponding one of the plurality of phases, the plurality of motor drives (<NUM>) being configured and disposed to deliver a torque current divided equally between each of the plurality of phases and independently deliver flux current to the corresponding one of the plurality of phases;
a controller (<NUM>) operatively connected to each of the plurality of motor drives (<NUM>) to selectively control the permanent magnet synchronous electric motor (<NUM>); and
a rescue module (<NUM>) operatively connected to the controller (<NUM>), the rescue module (<NUM>) being configured and disposed to determine a failure of one of the plurality of motor drives (<NUM>) and control the permanent magnet synchronous electric motor (<NUM>) in a reduced operation profile employing remaining ones of the plurality of motor drives (<NUM>);
characterized in that
one of the plurality of motor drives (<NUM>) is a primary motor drive (<NUM>) and remaining ones of the plurality of motor drives (<NUM>) are secondary motor drives (<NUM>);
the primary motor drive (<NUM>) is configured to communicate with each secondary motor drive (<NUM>) to establish a desired field orientation angle for each secondary motor drive (<NUM>) as well as to provide a desired torque current command; and
the primary motor drive (<NUM>) is configured to communicate velocity commands; prepare to run commands; as well as any synchronization logic.