5. Features and Functions¶
5.1. Set-Points¶
Set-points are user reference values that describe the desired steady-state operation of the DBx Module Add-On. In combination with the feedback Regulation States, the difference between the set-point and corresponding measurements are driven to zero over time. Some set-points will be disabled in menus or have no effect on the operation. For example, in Constant Current Mode, voltage feedback is disabled, and the voltage set-point has no impact on the operation of the DBx Module Add-On.
5.2. Commands¶
The DBx Module features a variety of commands, which can all be accessed from the front panel, external user I/O, and computer interface.
5.2.1. Start¶
The Start command engages the DBx Module Add-On’s DC input to allow the product to begin dissipating power, transitioning the status from Disabled to Enabled. The Start command switches the dissipative elements into of the DC circuit using a high-speed switching device.
5.2.2. Stop¶
The Stop command disengages the DBx Module Add-On’s DC input to stop the product from dissipating power, transitioning the status from Enabled to Disabled. The Stop command switches the dissipative elements out of the DC bus using a high speed switching device.
Warning
Even when the Stop command is issued and the DBx Module Add-On’s status is Disabled, there could still be hazardous voltages on the DC input from an externally connected DC source. Ensure that all instrument connections, load wiring, and load connections are either insulated or covered so that no accidental contact with lethal output voltages can occur. Always use a voltmeter to test the DC bus before making any connections.
5.2.3. Clear¶
The Clear command unlatches all soft-faults conditions and returns the DBx Module Add-On to standby, allowing the user to resume normal operation of the product. All soft-fault conditions must be resolved before clearing the latch. Once the fault has been cleared, the input can be re-enabled with the Start command.
5.2.4. Lock¶
The Lock command secures settings by locking the DBx Module Add-On, preventing changes to set-points and configuration settings through the front panel. When the DBx Module Add-On is locked, the front panel Lock button is back-lit red. In addition, the Lock status can be configured as one of the external user I/O digital outputs or queried by computer interface.
5.3. Function Generator¶
The function generator makes the DBx Module sink current according to an internally generated waveform. This feature simplifies dynamic-load test setups since the generation is self contained and conveniently customized through the front panel menu system. Each of the function types available have a different signal-processing algorithm for accepting input parameters and outputting a periodic signal.
The function generator is enabled by choosing it as a Setpoint Source through menus System Settings - Setpoint Source - Function Generator. Once enabled, all set point changes from other sources are ignored. The generator algorithm, selected through menus Function Generator - Function Type, is subject to limitations of the sample rate and look-up table size. The algorithm can update at a rate of 0.5 ms. As such, the period is limited such that 4 samples are output per period (2 ms). The maximum period is restricted to 65000 ms. Set point related parameters (Amplitude, LoLevel, Offset, etc.) are limited to the product’s rated current.
5.3.1. Sinusoid¶
The sinusoid function produces its waveform using the direct digital synthesis (DDS) method. Set points are loaded from a 1024 point sinusoid lookup table and scaled at fixed-sample intervals. The function is selected through menus Function Generator - Function Type - Sinusoid. The amplitude is set through menus Function Generator - Function Type - Sinusoid Parameters - Amplitude(Adc). From the same parent menu, offset and period are set in menus Offset(Adc) and Period(ms), respectively. These parameters and their effect on the waveform are illustrated in fig-function-sinusoid.
5.3.2. Square¶
The square function produces its waveform by logically changing set points after a programmed period of time. The function is selected through menus Function Generator - Function Type - Square. The low-level set point is programmed through menus Function Generator - Function Type - Square Parameters - LoLevel(Adc). From in the same parent menu, offset and period, in menus Offset(Adc) and LoPeriod(ms), respectively, are programmed. These parameters and their effect on the waveform are illustrated in fig-function-square.
5.3.3. Step¶
The step function behaves similarly to the Square Function, but step points cycle manually by pressing the start button. The first time the start button is pressed, the DBx Module Add-On is enabled, and regulates to the parameter saved in LoLevel(Adc). Pressing the start button again changes the set point to HiLevel(Adc). Pressing the button a third time cycles back to LoLevel(Adc). The parameter effects on the waveform are illustrated in fig-function-step.
5.3.4. Ramp¶
The ramp function produces its waveform by logically changing set points after a programmed period of time, while maintaining specified rise and and fall time. The function is selected through menus Function Generator - Function Type - Ramp The low level set point is programmed through menus Function Generator - Function Type - Ramp Parameters - LoLevel(Adc). From the same parent menu, the high level and rise and fall periods, HiLevel(Adc), RiseTime(ms) and FallTime(ms), are set respectively. These parameters and their effect on the waveform are illustrated in fig-function-ramp.
5.4. Control Modes¶
The DBx Module automatically selects the appropriate regulation state based on the programmed set-points and the load impedance, in accordance with its Auto-crossover Control Mode. The DBx Module can operate in constant voltage, constant current, or constant power output regulation. The regulation state is indicated by an illuminated LED next to the respective set point selection button, also via the external user I/O connector or by computer command.
5.4.1. Autocrossover Mode¶
When Autocrossover Mode is selected, the DBx Module Add-On will auto-crossover between voltage, current and power regulation, based on the set points and load impedance. If any set point is set to zero, the other set point controls will have little or no effect, forcing either a zero voltage limit or zero current limit and preventing output.
Trip-point settings for voltage, current and power can also be used to shutdown the DBx Module Add-On when a programmed threshold is crossed.
5.5. Regulation States¶
The DBx Module has four regulation states: Constant Voltage (CV), Constant Current (CC), Constant Power (CP), and Constant Resistance (CR). The active regulation state is indicated by a illuminated circular LED next to the respective voltage, current, or power set-point button. The active regulation state can also be monitored programmatically.
5.5.1. Constant Voltage (CV)¶
When the constant voltage regulation state is indicated, the DBx Module Add-On is maintaining fixed voltage set-point, while the current and power flucuates with the load impedance, as illustrated by Fig. 5.1.
Fig. 5.1 Operating range in constant voltage mode¶
5.5.2. Constant Current (CC)¶
When the constant current regulation state is indicated, the DBx Module Add-On is maintaining a fixed current set-point, while the voltage and power flucuates with the load impedance, as illustrated by Fig. 5.2.
Fig. 5.2 Operating range in constant currnet mode¶
5.5.3. Constant Power (CP)¶
When the constant power regulation state is indicated, the DBx Module Add-On is maintaining a fixed power set-point by varying the current level inversely in response to a change in output voltage, as illustrated by Fig. 5.3.
Fig. 5.3 Operating range in constant power mode¶
5.6. Protection and Diagnostics¶
5.6.1. Over Voltage Trip (OVT)¶
The DBx Module has a programmable Over Voltage Trip setting used to shutdown the product if an undesired maximum voltage value is measured across the DC input. The OVT setting can be adjusted to a maximum of 110% of the specific DBx Module Add-On’s full scale voltage rating. An over-voltage condition must be sustained for multiple samples for the OVT fault to register.
When an OVT fault occurs, the DC input bus is disconnected via an internal switching device, leaving the DBx Module Add-On in an open-circuit faulted condition with an OVT alarm shown on the auxiliary display. To resume operation, the DC input voltage must be drop below the DBx Module Add-On’s OVT setting, the Clear function must be issued, and the input re-energized with the Start function.
The OVT setting can be programmed through the front panel’s auxiliary display, through one of the four analog inputs, or programmatically through software.
The factory default OVT setting is 110% of the specific DBx Module Add-On’s maximum voltage rating.
5.6.2. Under Voltage Trip (UVT)¶
The DBx Module has a programmable Under Voltage Trip setting used to shutdown the product if an undesired minimum voltage threshold is measured across the DC input. The UVT setting can be adjusted to a minimum of 5% of the specific DBx Module Add-On’s full scale voltage rating. An under-voltage condition must be sustained for multiple samples for the UVT fault to register.
The UVT setting was designed to protect DC input sources, such as batteries, from discharging below a minimum desired voltage. If the UVT setting is used, upon first enabling the DC input the DC input voltage must be above the UVT setting or the DBx Module Add-On will trip immediately. Fig. 5.4 shows the operating range with both OVT and UVT enabled.
Fig. 5.4 Operating region without trip when OVT and UVT settings are enabled¶
When an UVT fault occurs, the DC input bus is disconnected via an internal switching device, leaving the DBx Module Add-On in an open-circuit faulted condition with an UVT alarm shown on the auxiliary display. To resume operation, the Clear function must be issued and the input re-energized with the Start function.
The UVT setting can be programmed through the front panel’s auxiliary display, through one of the four analog inputs, or programmatically through software.
The factory default UVT setting is 0 Vdc, which disables the UVT protection.
5.6.3. Over Current Trip (OCT)¶
The DBx Module has a programmable Over Current Trip setting used to shutdown the product if an undesired maximum current value is measured through the DC input. The OCT setting can be adjusted to a maximum of 110% of the specific DBx Module Add-On’s full scale voltage rating. An over current condition must be sustained for multiple samples for the OCT fault to register.
When an OCT fault occurs, the DC input bus is disconnected via an internal switching device, leaving the DBx Module Add-On in an open-circuit faulted condition with an OCT alarm shown on the auxiliary display. To resume operation, the DC input current must be drop below the DBx Module Add-On’s OCT setting, the clear function must be issued, and the input re-energized with the start function.
The OCT setting can be programmed through the front panel’s auxiliary display, through one of the four analog inputs, or programmatically through software.
5.6.4. Over Power Trip (OPT)¶
The DBx Module has a programmable Over Power Trip setting used to shutdown the product if an undesired maximum power value is measured at the DC input. The OPT setting can be adjusted to a maximum of 110% of the specific DBx Module Add-On’s full scale power rating. An over-power condition must be sustained for multiple samples for the OPT fault to register.
When an OPT fault occurs, the DC input bus is disconnected via an internal switching device, leaving the DBx Module Add-On in an open-circuit faulted condition with an OPT alarm shown on the auxiliary display. To resume operation, the DC input voltage must be drop below the DBx Module Add-On’s OPT setting, the Clear function must be issued, and the input re-energized with the Start function.
The OPT setting can be programmed through the front panel’s auxiliary display, through one of the four analog inputs, or programmatically through software.
The factory default OPT setting is 110% of the specific DBx Module Add-On’s maximum power rating.
5.6.5. Thermal Fault¶
The DBx Module has internal thermistors on its various heatsinks to ensure operation at temperatures within the product’s design specifications. A thermal fault typically results from one of the following conditions:
Operating in an environment above the maximum ambient temperature specification.
Operating in an environment below the minimum ambient temperature specification.
Blocking the front panel air intake.
Internal fan or solenoid failure.
Broken electrical contact to thermistors.
Coolant intake temperatures are above those recommended.
When a thermal fault occurs, the DBx Module Add-On enters into a hard-fault condition, where all loads disconnect from the source. The user is prevent from enabling the load through the front panel and external interfaces. Details about the thermal fault are shown on the front display.
To resume operation, the product must be power cycled, by toggling the rocker switch located on the front panel. Allow sufficient time for the DBx Module Add-On to return to safe operating temperatures. Otherwise, the product will enter immediately into a thermal fault after booting.
5.6.6. Interlock¶
The Interlock feature disables the DBx Module Add-On by entering a soft fault state. The safety feature is triggered whenever the +5V signal applied to the interlock pin is broken. By default, interlock is disabled when the DBx Module Add-On ships from the factory. Interlock can be enabled from the front panel, computer interface. Once interlock is assigned to one of the pins listed in external user I/O +5V must be present to operate the product. There are two method to providing +5V to the interlock pin:
Providing a physical short from the provided external user I/O +5V signal (Pin 14) to the interlock digital input.
Using an external user supplied +5V signal with reference to the external user I/O GND signal (Pin 25).
With either method, an external dry contact may be used to trigger the interlock.
When the +5V interlock signal is broken, the dissipative elements are switched out of the DC bus using a high-speed switching device, the DBx Module Add-On is placed in a soft fault state.
To resume normal operation, the +5V signal must first be restored to the interlock input and the Clear command issued.
5.6.7. Lock¶
The lock feature prevents inadvertent changes to DBx Module Add-On operation by disabling front panel button inputs. Lock can be enabled through the front panel using the LOCK button, through the communications interface using SCPI commands, and the rear-external interface using a +5V signal. In all cases, the LOCK button will illuminate to show the DBx Module Add-On is lock. Also, and the stop button always functions normally (for safety). The digital input lock takes highest priority, such that when locked, it can be unlocked only by the digital input. Second priority is SCPI followed by the LOCK button. The table below illustrates unlocking behavior for a locked DBx Module Add-On.
Locked by Front Panel |
Locked by SCPI |
Locked by Digital Input |
|
|---|---|---|---|
Front Panel Unlock |
✓ |
||
SCPI Unlock |
✓ |
✓ |
|
Digital Input Unlock |
✓ |
5.6.8. Out of Regulation¶
Out of Regulation indicates a high error between an internal control value and the value measured at the dbx terminals. This can occur when the controller is forced into a condition that it can not regulate and is failing to reach the desired set point. For |product_type_plural|, this can happen if MOSFETs operate in the linear region, or when the control gains are too aggressive, or the external source is unstable. In Out of Regulation accumulation in the feedback compensator is stopped to prevent integral wind up from over driving the MOSFETs. When terminal measurement return to expect values, the fault clears itself, and the compensator returns to normal operation.
5.6.9. Below Min Operating Voltage¶
The DBx Module Add-On dissipates power by controlling the current entering the product. Controlling the current is only possible when there is sufficient voltage across the input terminals, for putting internal transistors into the saturation region. When voltage drop below 0.25% of the dbx’s voltage rating it enters a Below Min Operating Voltage fault and performs the same actions described in Out of Regulation. When voltage goes above 0.25%, the fault clears itself, and returns to normal operation.
5.7. Statuses¶
The DBx Module Add-On has various statuses corresponding to its present state of operation. These statuses can be viewed on the front panel, programmatically by computer command, or using the 25-pin user I/O connector. The available statuses are as follows:
- Enabled
The DBx Module Add-On’s input is engaged and processing power.
- Disabled
The DBx Module Add-On’s input is disengaged and all systems are normal. The DBx Module Add-On is awaiting a START command to engage its input. When in a Disabled state, there is an electrical disconnect between the product’s dissipative elements and the DC input terminals through a high speed switching device.
- Soft Fault
The DBx Module Add-On’s input is disengaged as a result of a soft fault that occurred. A soft fault occurs when an user-programmed limit is reached, such as a trip setting. A description of the soft fault is displayed on the message line. A soft fault can be cleared with the CLEAR function, placing the DBx Module Add-On into a Disabled status. When in a Soft Fault state, there is an electrical disconnect between the product’s dissipative elements and the DC input terminals through a high speed switching device.
- Hard Fault
The DBx Module Add-On’s input is disengaged as a result of a hard fault that occurred. A hard fault is a system shutdown resulting from an operating condition that has the potential to damage the product, for example, exceeding the products specifications. A description of the hard fault is displayed on the message line. A hard fault fault can only be cleared by power cycling the product. When in a Hard Fault state, there is an electrical disconnect between the product’s dissipative elements and the DC input terminals through a high speed switching device.
Caution
Ignoring hard faults and repeatedly operating the DBx Module Add-On in a manner that triggers a hard fault will eventually result in product damage.
5.8. Status Messages¶
The DBx Module Add-On has various messages, which elaborate on the product’s present status. A message may indicate normal operation, power limiting as a result of the DBx Module Add-On’s operating profile, or steps to resolve a fault.
Messages for Status: Enabled
Systems normal.
Messages for Status: Disabled
System disabled.
Messages for Status: Soft Fault
Voltage trip point setting reached. Issue CLEAR command to resume operation in standby.
Current trip point setting reached. Issue CLEAR command to resume operation in standby.
Power trip point setting reached. Issue CLEAR command to resume operation in standby.
Messages for Status: Hard Fault
Global shutdown occurred. Power cycle to resume operation in Standby.
Excessive communication errors detected. Check cabling and communications grounding. Contact technical support.
Voltage measured that exceeds product’s max rating. Investigate cause and power cycle to resume operation in standby.
Current measured that exceeds product’s max rating. Investigate cause and power cycle to resume operation in standby.
Power measured that exceeds product’s internal resistive elements’ max rating. Investigate cause and power cycle to resume operation in standby.
Linear elements have exceeded their max temperature rating. Verify adequate cooling air flow and ambient temperature is within product specifications. Power cycle to resume operation in Standby.
5.9. Factory Restore¶
The DBx Module contains EEPROM (electrical erasable programmable read-only memory) for retaining settings after loss of AC power. The memory contains the set points, control mode, calibration gains, offsets, product serial numbers, and more. Most the memory positions are visible using MagnaWEB under the “EEPROM Editor” side menu.
Factory Restore overwrites existing EEPROM settings with defaults values so the DBx Module Add-On can return to a known operating state. This should be performed if user experiences unexpected behavior, due to unknown or forgotten configurations. Magna-Power Electronics may request users perform factory restore, as a starting point in most support cases. The memory positions affected by factory restore are listed in the table below.
Factory restore values (defaults) can be stored in Flash or EEPROM memory, as determined by Magna-Power Electronics. The Flash values are used for product-wide settings, such as control mode and slew rates, and mostly affect the products operating state. EEPROM values are reserved for customer and unit-specific settings, such as gains, offsets, and MagnaLINK™ address information, which are set during factory testing.
Product can be restored to a known state, by modifying the EEPROM in bulk, using either Soft Restore or Hard Restore. Soft Restore only effects those EEPROM positions whose default values are stored in Flash, as shown in the table below. Hard Restore overwrites calibrations values, feedback gains, i.e., settings saved in EEPROM at the factory. In most cases, Soft Restore should be used, and Hard Restore used as a last resort, since it overwrites any in-house calibrations with or original (older) factory calibrations.
Factory restore can be initiated using the front panel by navigating to System Settings - Factory Restore in the menu system. After the restore option has been selected, DBx Module Add-On will reboot and start up with the new settings.
Factory Restore Values