Converter Control Mode Attributes

The attribute table contains attributes that govern the overall control behavior of a converter in the Motion Control Axis.

Converter Configuration

* The default value can specified by the specific drive profile (AOP).

The Converter Configuration attribute determines the general control behavior of the regenerative or low harmonic AC/DC converter axis instance. This attribute is used by the controller to set the Converter Control Mode attribute that is sent to the drive during initial configuration. When the Converter Configuration is configured in

Logix Designer

application, the Converter Control Mode is also updated.

This table provides descriptions of the Converter Configuration enumerations.

When modified programmatically, via SSV, the Converter Control Mode value cannot be set to an enumeration that the current Converter Configuration cannot support. For example, if the Converter Configuration is set for Active Current Control, the Converter Control Mode cannot be changed to Bus Voltage Control since bus voltage loop attributes have not been configured. Refer to the following table for a list of valid Converter Control Modes for a Converter Configuration:

Converter Control Mode

The Converter Control Mode attribute determines the basic mode of operation for the regenerative converter.

When Bus Voltage Control is selected, the converter controls the DC bus voltage output of the converter. The output of the DC bus control loop drives an inner Active AC Line current control loop to maintain the commanded DC bus voltage level established by the Bus Voltage Reference. The Bus Voltage Reference Source determines which source is used to establish the Bus Voltage Reference.

When Active Current Control is selected, the converter disables DC bus voltage regulation and directly controls the Active AC Line current component based on the Active Current Command. During initial configuration, the controller derives this value from the Converter Configuration attribute value.

Converter Disable Delay

When disabling the converter, the Converter Disable Delay value determines the amount of time the converter power structure shall remain enabled in the Running state after the inverter Power Structure Enabled status has transitioned to false on all inverters connected to the DC Bus.

This only applies when the Converter Startup Method is set to Follow Inverter Enabled.

Reactive Power Control

When Reactive Power Control attribute is enabled, the regenerative converter works solely as a reactive power compensation device by injecting reactive power to the grid. This is typically done to improve the power factor on the plant floor or to stabilize AC line voltage. In this mode, the converter does not transfer active power to associated drives on the DC Bus. Instead all of the converter’s rating capacity is dedicated to reactive power correction to the grid. The Reactive Power Control operates by manipulating the Motoring Power Limit and the Regenerative Power Limit in the converter current loop. When enabled, the Reactive Power Control function is effective regardless of the configured Converter Control Mode.

Converter Startup Method

The Converter Startup Method attribute specifies the method to use to initiate transition of the regenerative converter axis from the Stopped state to the Starting state.

If Enable Request is selected, assuming a successful Pre-charge and transition to the Stopped state, the converter stays in the Stopped state until it receives an Enable Request from the controller. After the converter receives Enable Request, it transitions to Starting state and checks for proper AC line synchronization. Once ready for regenerative control, the converter transitions to the Running state with all configured control loops operational.

If Enable Input is selected, assuming a successful Pre-charge and transition to the Stopped state, the converter checks the status of the Enable Input. If the Enable Input is active, the converter axis transitions from the Stopped state to the Starting state and checks for proper AC line synchronization. Once ready for regenerative control, the converter then transitions to the Running state with all configured control loops operational. If the Enable Input is not active, then the converter axis transitions from the Stopped state to Start Inhibited state. The converter axis remains in the Start Inhibited state until such time as the Enable Input is activated. Once activated, the axis state transitions from Start Inhibited to the Stopped state and then, without receiving any Enable Request from the controller, automatically transitions to the Starting state. Once ready for regenerative control, the converter then transitions to the Running state with all configured control loops operational. If the Enable Input is either not supported by the converter or the Enable Input Checking attribute is set to Disabled, the Enable Input is effectively inactive and the converter axis remains in the Start Inhibited state indefinitely. While waiting for Enable Input activation in the Start Inhibited state, the converter can optionally set the DC Bus Unload bit in Axis Status that is sent to the controller. Setting the DC Bus Unload bit causes the controller to set the Converter Bus Unload bit that is sent to all drives that can draw power from the converter’s DC bus. In this way, the converter can prevent DC bus power draw while the converter axis is in the Start Inhibited state.

If Automatic is selected, assuming a successful Pre-charge and transition to the Stopped state, the converter automatically transitions to Starting state and checks for proper AC line synchronization. Once ready for regenerative control, the converter transitions to the Running state with all configured control loops operational.

If Follow Inverter Enabled is selected, assuming a successful Pre-Charge and transition to the Stopped state, the converter shall monitor the Power Structure Enabled status of all inverters connected to the DC bus. When any inverter Power Structure Enabled transitions to true, (inverter enters the Starting state), the converter shall transition to the Starting state and check for proper AC line synchronization. Once ready for regenerative control, the converter transitions to the Running state with all configured control loops operational. In the Running state, the converter shall monitor the Power Structure Enabled status of all inverters connected to the DC bus. After waiting for the Converter Disable Delay time from the time when all inverter Power Structure Enabled statuses are false, (all inverters have entered the Stopping state), the converter shall transition to the Stopping state.

This version of the object does not support passing Power Structure Enabled status information from inverters to converters through the CIP Motion Connection data structure. Therefore, use of this enumerated value is limited to a device that includes an Active AC/DC converter (G) and an inverter (FPVT). The Power Structure Enabled status is passed between the converter and inverter internally. This enumerated value may also be used in a system where the converter and inverter modules on the DC bus can communicate Power Structure Enabled status through some intermodule communications mechanism.

Axis Test Mode

Axes with the Test Mode attribute set to Enabled and that are configured for Controller Loop Back read the Converter startup method attribute and simulate converter behavior by supporting these axis states.