.. _control-modes: Control Modes ------------- The |product_full| automatically selects the appropriate :ref:`regulation state ` depending on the selected control mode, programmed set-points and the voltage and current being driven by the connected DC source. The |product_type| preferences regulation states depending on the selected Control Mode: :ref:`mode-voltage`, :ref:`mode-current`, :ref:`mode-power`, or :ref:`mode-resistance`. Control Modes can be selected from the :ref:`front panel menu system ` or by :ref:`computer command `. Changing the Control Mode while the DC input is enabled will cause the |product_type| to stop processing power and enter :ref:`Disabled ` status. .. _mode-voltage: Voltage Mode ^^^^^^^^^^^^ When Voltage Mode is selected, the |product_type| will auto-crossover between voltage and power regulation, but will preference :ref:`constant voltage regulation ` over all other states. In Voltage Mode, the |product_type| will try to sink enough current to maintain the voltage set point in a constant voltage regulation state. The operating region for Voltage Mode is further described by :numref:`fig-control-mode-voltage`. Programming a resistance set-point and current set-point is disabled in Voltage Mode as the two regulation states conflict with the voltage regulation state. :ref:`Trip-point settings ` for voltage and power can also be used to shutdown the |product_type| when a programmed threshold is crossed. .. caution:: Configuring the |product_type| for Voltage Mode while the connected DC source is also trying to regulate voltage will produce regulation instabilities. Instead, an alternative control mode should be selected. .. _fig-control-mode-voltage: .. figure:: /_common-magnaload/_images/control-mode-voltage.* :width: 320pt :align: center Simplified Voltage Mode Operation Diagram. Refer to :numref:`fig-operating-profile` for operating profile constraints. .. _mode-current: Current Mode ^^^^^^^^^^^^ When Current Mode is selected, the |product_type| will auto-crossover between current and power regulation, but will preference :ref:`constant current regulation ` over all other states. In Current Mode, the |product_type| will allow the input voltage fluctuate while trying to maintain the current set-point in a constant current regulation state. The operating region for Current Mode is further described by :numref:`fig-control-mode-current`. Programming a resistance set-point and voltage set-point is disabled in Current Mode as the two regulation states conflict with the current regulation state. :ref:`Trip-point settings ` for current and power can also be used to shutdown the |product_type| when a programmed threshold is crossed. .. caution:: Configuring the |product_type| for Current Mode while the connected DC source is also trying to regulate current will produce regulation instabilities. Instead, an alternative control mode should be selected. .. _fig-control-mode-current: .. figure:: /_common-magnaload/_images/control-mode-current.* :width: 320pt :align: center Simplified Current Mode Operation Diagram. Refer to :numref:`fig-operating-profile` for operating profile constraints. .. _mode-power: Power Mode ^^^^^^^^^^ When Power Mode is selected, the |product_type| will auto-crossover between current and power regulation, but will preference :ref:`constant power regulation ` over all other states. In Power Mode, the |product_type| will allow the input voltage and current fluctuate while trying to maintain the power set-point in a constant power regulation state. The operating region for Power Mode is further described by :numref:`fig-control-mode-power`. Programming a resistance set-point and voltage set-point is disabled in Current Mode as the two regulation states conflict with the current regulation state. :ref:`Trip-point settings ` for current and power can also be used to shutdown the |product_type| when a programmed threshold is crossed. .. caution:: Configuring the |product_type| for Power Mode while the connected DC source is also trying to regulate power will produce regulation instabilities. Instead, an alternative control mode should be selected. .. _fig-control-mode-power: .. figure:: /_common-magnaload/_images/control-mode-power.* :width: 320pt :align: center Simplified Power Mode Operation Diagram. Refer to :numref:`fig-operating-profile` for operating profile constraints. .. _mode-resistance: Resistance Mode ^^^^^^^^^^^^^^^ When Resistance Mode is selected, the |product_type| will preference :ref:`constant-resistance` regulation state over all other regulation states. The |product_type| will operate in constant resistance regulation within the set-point boundaries indicated in grey in :numref:`fig-control-mode-resistance`. If the connected DC source drives the DC bus to one of the bounding set-point limits, the |product_type| will auto-crossover to the appropriate regulation state. To avoid auto-crossover, the bounding set-point limits should be set sufficiently high to increase the constant resistance operating range. Programming a current set-point and voltage set-point is disabled in Resistance Mode as the two regulation states conflict with the resistance regulation state. :ref:`trip-point-settings` for voltage, current, and power can also be used to shutdown the |product_type| when a maximum desired limit is reached. .. _fig-control-mode-resistance: .. figure:: /_common-magnaload/_images/control-mode-resistance.* :width: 320pt :align: center Simplified Resistance Mode Operation Diagram. Refer to :numref:`fig-operating-profile` for operating profile constraints. .. index:: single: shunt regulator .. _mode-shuntreg: Shunt Regulator Mode ^^^^^^^^^^^^^^^^^^^^ Shunt Regulator Mode is designed to regulate the DC bus voltage to ensure the voltage remains below a programmed limit. Shunt Regulator Mode can be used as a replacement for a braking resistor in a DC motor drive application, or as a protection device to prevent rising DC bus voltage from damaging other electronic devices. When Shunt Regulator Mode is selected, the |product_type| will only dissipate energy when the voltage passes a user-defined voltage threshold. The |product_type| will remain idle at the DC bus voltage defined by the source until that DC bus voltage rises above a programmed voltage threshold. When DC bus voltage passes this voltage threshold, the |product_type| will begin to process power, with the current rising rapidly to the current set point. .. index:: single: voltage threshold single: voltage set point The voltage threshold is the programmed voltage set point plus 1% of the unit's full scale voltage rating. For example, if an ARx6.75-1000-14 (6.75 kW, 0-1000 Vdc, 0-14 Adc) |product_type| was programmed to 500 Vdc in Shunt Regulator Mode, the |product_type| would begin dissipating energy at the voltage threshold: 500 Vdc + (1% of 1000 Vdc) = 510 Vdc. The |product_type| would continue dissipating energy until the DC bus voltage drops below 500 Vdc. When the product is dissipating energy in Shunt Regulator Mode, the current is regulated to the |product_type|'s user-defined current set point. .. note:: If the |product_type| is not sized properly for the amount of current fed back onto the DC bus, the voltage on the DC bus may continue to rise beyond the |product_type|'s voltage threshold. :numref:`fig-control-mode-shunt-regulator` shows the voltage and current over time in Shunt Regulator Mode, as the DC bus voltage rises below the voltage threshold and the |product_type| begins dissipating energy. :ref:`trip-point-settings` for voltage, current, and power can also be used to shutdown the |product_type| when a maximum desired limit is reached. .. _fig-control-mode-shunt-regulator: .. figure:: /_common-magnaload/_images/control-mode-shunt-regulator.* :width: 420pt :align: center Simplified Shunt Regulator Mode Operation Diagram. Refer to :numref:`fig-operating-profile` for operating profile constraints.