A powertrain can be built up in many different configurations. In its simplest form it is just a motor contactor or motor starter and a motor (see Figure 61). Another configuration may be a variable speed drive driving two asynchronous motors simultaneously. The typical servo drive consists of inverter/drive and motor realizing closed loop position control by encoder feedback devices. An even more complex setup is to combine several motors to perform synchronized motion by means of a motion PLC or CNC and a fieldbus.
Figure 6 1 – Powertrain Structure Examples
The scope of this document focuses on the elements of a drive system. This includes drive component related products (e.g., brake resistor, DC bus module, safety module, input/output filter), drive related products (e.g., contactor, motor starter, drive types) and motor/motor component related products (e.g., motor, gearmotor, encoder, sensors). Out of scope are mains and components of the load side.
Figure 6 2 – Scope of the Information Model
Due to the complexity of real-world powertrains the information model must be highly modular. This means that OPC UA objects must be provided which are not too fine granular but enable to represent the majority of existing devices by combining them. The level of granularity was chosen to be on basic component level like motor, encoder and brake. These entities are called assets (PtAssetType) and have one or more components holding their asset attributes (PtAssetAttributesType). Also, it´s possible to model a software asset type e.g. firmware by using the PtAssetType.
The powertrain information model is based on two main object types:
Table 13 – Powertrain Object Types
|
1. |
PtAssetType(powertrain asset type) |
Represents an orderable part of the powertrain. It serves as a container for the asset's attributes. The most common attributes of asset types are added as mandatory components. e. g. motor and encoder for servo motor. |
|
2. |
PtAssetAttributesType(powertrain asset attribute type) |
Asset attributes are split into two categories. Some of the common asset attributes apply to all asset types (e.g., ambient temperature). Specific asset attributes apply only to some subset of asset types, (e.g., MotorPolePairs applies to several motor related asset types). |
Some asset types have a one-to-one relation to an PtAssetAttributesType like PtAssetEncoderType to PtEncoderAttributesType. Others have a one-to-many relation e. g. a gear motor PtAssetGearMotorRoteryType has mandatory properties of type PtGearAttributesType and PtMotorRoteryAttributesType. A complex asset like PtAssetServoDriveType has to be decomposed into the predefined component asset attributes like PtInputConverterAttributesType and PtOutputConverterAttributesType.
Figure 63 shows the powertrain information model basic structure. Subtypes of PtAssetType have attributes which are subtypes of PtAssetAttributesType.
Figure 6 3 – Information Model Overall Structure
Besides the asset attributes which are directly associated to an asset there are also common asset attributes found in a powertrain which may be used in multiple assets. These are defined under PtCommonAssetAttributesType and cover domains like standards, hardware or ambient conditions.
Figure 6 4 – PtCommonAssetAttributesType
Figure 65 shows asset types grouped into drive component related, switchgear related and motor related assets. The swim lanes shall illustrate the energy flow through drive and motor. The frequency converter is shown with an orange frame and is split into assets like control module, input converter, DC bus and output converter. Below the low voltage switchgear related assets include e.g. a contactor that simply switches current on and off to the motor. A more complex setup uses a motor starter.
Figure 6 5 – Example Asset Types of a Powertrain
The following table gives an overview of the available asset types and their asset attributes. The asset terms are described in chapter 6.3.
Motor / Motor Components related AssetTypes
Motor component related asset types contain the motor itself and devices which are mounted near the motor to measure actual data or affect the motion output.
Table 14 – Motor / Motor Components related AssetTypes
|
AssetType |
AssetType Definition in Chapter |
Subtype of |
AttributesTypes |
|
PtAssetMotorType |
PtAssetType |
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|
|
PtAssetMotorRotaryType |
PtAssetMotorType |
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|
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PtAssetMotorLinearType |
PtAssetMotorType |
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|
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PtAssetDriveIntegratedMotorRotaryType |
PtAssetMotorRotaryType |
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PtAssetDriveIntegratedMotorLinearType |
PtAssetMotorLinearType |
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PtAssetGearMotorRotaryType |
PtAssetMotorRotaryType |
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PtAssetGearMotorLinearType |
PtAssetMotorLinearType |
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PtAssetDriveIntegratedGearMotorRotaryType |
PtAssetDriveIntegratedMotorRotaryType |
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PtAssetDriveIntegratedGearMotorLinearType |
PtAssetDriveIntegratedMotorLinearType |
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PtAssetEncoderType |
PtAssetType |
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PtAssetEncoderRotaryType |
PtAssetEncoderType |
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PtAssetEncoderLinearType |
PtAssetEncoderType |
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PtAssetBrakeType |
PtAssetType |
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PtAssetGearType |
PtAssetType |
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PtAssetTemperatureSensorType |
PtAssetType |
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PtAssetVibrationSensorType |
PtAssetType |
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Drive Components related AssetTypes
Drive components related asset types contain building blocks of a drive like input and output converter and control module. These building blocks should be sufficient to compose a drive of any type.
Table 15 – Drive Components related AssetTypes
|
AssetType |
AssetType Definition in Chapter |
Subtype of |
AttributesTypes |
|
PtAssetEncoderInterfaceType |
PtAssetType |
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|
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PtAssetBleedType |
PtAssetType |
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PtAssetElectricalBrakingModuleType |
PtAssetType |
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PtAssetDcBusModuleType |
PtAssetType |
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PtAssetInputConverterType |
PtAssetType |
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PtAssetOutputConverterType |
PtAssetType |
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PtAssetInputOutputConverterType |
PtAssetType |
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PtAssetInputFilterType |
PtAssetType |
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PtAssetInputReactorType |
PtAssetType |
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PtAssetOutputFilterType |
PtAssetType |
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PtAssetOutputReactorType |
PtAssetType |
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PtAssetCommunicationModuleType |
PtAssetType |
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PtAssetControlModuleType |
PtAssetType |
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PtAssetIoModuleType |
PtAssetType |
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PtAssetSafetyModuleType |
PtAssetType |
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PtAssetCoolingType |
PtAssetType |
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PtPrechargeType |
PtAssetType |
|
Complete Drive Devices related AssetTypes
The PtAssetDriveType serves as a generic container while subtypes PtAssetFrequencyConverterType or PtAssetVariableSpeedDriveType are for the user’s convenience to express a specific class of drives. Another intention is to make some components mandatory as PtAssetMotorRotaryType for PtAssetDriveIntegratedMotorType.
Table 16 – Complete Drive Devices related AssetTypes
|
AssetType |
AssetType Definition in Chapter |
Subtype of |
AttributesTypes |
|
PtAssetDriveType |
PtAssetType |
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|
|
PtAssetFrequencyConverterType |
PtAssetDriveType |
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PtAssetVariableSpeedDriveType |
PtAssetDriveType |
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PtAssetServoDriveType |
PtAssetDriveType |
|
Switchgear related AssetTypes
Switchgear related PtAssetTypes contain devices that can be used to control, protect and monitor an asynchronous motor, and sometimes associated with a variable speed drive described in a separate section.
Table 17 – Switchgear related AssetTypes
|
AssetType |
AssetType Definition in Chapter |
Subtype of |
AttributesType |
|
PtAssetContactorType |
PtAssetType |
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|
|
PtAssetElectricOverloadRelayType |
PtAssetType |
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PtMotorStarterType |
PtAssetType |
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PtSoftStarterType |
PtAssetType |
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|
|
PtMotorManagementDeviceType |
PtAssetType |
|
The modular approach of the information model is shown in an example in Figure 66. A PtAssetMotorRotaryType, representing a servo motor, has properties of PtAssetAttributesType for the rotary motor, rotary encoder and brake. A PtAssetServoDriveType is a subtype of PtAssetDriveType and has additional encoder asset attributes. Motor and servo drives can of course have arbitrary numbers of objects of the PtCommonAssetAttributesType.
Figure 6 6 – Detailed Example of an Information Model Structure
In the Table 18 the properties that are required for identifying assets of a powertrain are described. Since there are already several OPC UA specification existing that are covering similar topics, this specification shall reuse them where possible. The following specifications have been identified as relevant:
- OPC 10000-100 – Device Integration
- OPC 40001-1 – OPC UA for Machinery
- OPC 10000-81 – Information Model and Connecting Devices
The general assumption is that any VDMA Companion Specification shall be in line with the OPC 40001-1. So that this approach is also followed here.
Additionally, this specification shall also be compliant to the OPC 10000-81 (Information Model & Connecting Devices) specification, since the defined PtAssetType shall be usable by the OPC UA FX Motion specification as well.
Objects are compliant to the FxAssetType if they are instances of the type FxAssetType, a subtype of it or if they implement the required interfaces which are IVendorNameplateType, ITagNameplateType of OPC 10000-100 and IAssetRevisionType of OPC 10000-81.
Since this specification shall be usable standalone and independent from OPC 10000-81 it follows the approach of implementing the interfaces to be compliant.
Figure 67 shows the overview of the PtAssetType and its identification concept including all related specifications and type definitions.
The PtAssetType references directly the IDeviceHealthType and the ISupportInfoType from OPC 10000-100.
By that it gets the property DeviceHealth as well as the folders for DeviceTypeImage, ImageSet, Documentation and ProtocolSupport.
It uses the IMachineryItemVendorNameplateType in order to get the InitialOperationDate property.
Further a new interface type called IPtTagNameplateType is defined. This is derived from the IMachineTagNameplateType in order to get the Location property. Further it adds the Comment, ContactInformation and Function properties.
Finally, to ensure the compatibility to OPC 10000-81 it implements the IAssetRevision interface.
The PtAssetType is a component in the sense of the OPC 40001-1 specification and therefore also be compliant to that. To ensure that compatibility the PtAssetType must provide an object called Identification which is an instance of the MachineryComponentIdentificationType or a subtype.
In OPC 10000-81 the identification properties are assembled below the asset whereas the OPC 40001-1 uses an object as and add-in for structuring. This specification shall bring both approaches together to be compatible to them. This concept is exemplary illustrated in Figure 68. Since both, the interfaces of OPC 10000-81 and the Identification add-in, are optional the model can be also used standalone.
Figure 6 8 – Sample Instance which is Compliant to OPC 10000-81 and OPC 40001-1