Energy can be recycled between channels above the system's nominal power. For example a 4 channel 500kW system can sink up to 1MW from a source, such as a battery pack, from channel four and use the energy directly across the other three channels. The unit's remaining capability can still be used across the other 3 channels to and from the grid. This feature is particularly useful for sites which have a limited incoming grid infrastructure.

While each individual channel is only able to sink or source its nominal current/voltage, higher currents can be achieved when operating channels in parallel configuration. For example a four channel 500kW/1000A system can sink or source currents up to 2000A when operating two channels in parallel and 4000A when combining four channels. Please note that the system's internal DC link is limited to 2MW.

The LAB-MOBI is an incredibly flexible power system which can be configured in a number of ways.

Possible Two Channel Configurations

• CH1 and CH2 in single operation
• CH1 and CH2 in parallel operation

Possible Four Channel Configurations

• CH1, CH2, CH3 and CH4 in single operation
• CH1, CH2, CH3 and CH4 in parallel operation
• CH1 and CH2 in parallel operation; CH3 and CH4 in parallel operation
• CH1 and CH2 in parallel operation; CH3 and CH4 in single operation

Fast Dynamics and High Stability

The LAB-MOBI provides a highly stable output of ≤0.1% rms F.S. for both current and voltage, ideal or powering sensitive DUTs. 

The high dynamics of the system allows users to switch quickly between quadrants. This is particularly useful when performing tests on bidirectional devices with fast current step changes such as super capacitors and electric motors. A typical time for a 10% to 90% load step in CC mode is less than 1ms assuming an ohmic load. Example scope shots of a previous test are provided below:

Seamless Source/Sink Transition

When switching between sinking and sourcing current, the LAB-MOBI provides a seamless transition. This means that during the quadrant change there is zero deadband time and no unwanted/disruptive behaviour is introduced to the power system's output characteristics. This feature is particularly useful for when users need to switch between charging and discharging a battery at a constant current rate, or simulate fast dynamics.

Sense Compensation

Sense terminals are built into the LAB-MOBI for the connection of sense wire which compensates for voltage drops in the load lines. Up to 5% of the system's nominal voltage value can be compensated for. This is particularly useful for applications with long cables which have unwanted voltage drops.

Internal Resistance Range

Each LAB-MOBI is built with a user programmable internal resistance range as standard. This makes the power systems ideal for simulating the output of energy storage devices such as an ageing battery pack, fuel cell stacks and super capacitors. The exact range varies by model, for model specific details please contact ETPS.

Power Recycling

When functioning as a load, the LAB-MOBI has an inbuilt monitoring system that synchronises with grid conditions. This recycles DC sink energy back to the grid, with typical losses of only 5-10%. 

Switchable Output Capacitors

Output capacitance is provided to improve stability when operating in constant voltage mode. This is particularly useful to assist the fast current demands when testing drives. Some electric drives require a very stable voltage during a step change. If the voltage drop is too low it could damage the drive.

When choosing the /SIM and /SIM-TEST options an extra level of capacitance is provided. Additional capacitance from an external box is also available, which can be switched between 3 different levels depending on the requirements of the test application.

Second Current Range (Option /SCR)

A second current range can be built into systems to give better accuracy and resolution for low current applications. This is particularly useful when testing high voltage equipment, such as electric vehicle battery packs, which typically produce low currents. The lower current range is not operable for a configuration of 2 or more LAB-MOBI channels operating in parallel.

Power Distribution Units

A PDU is used to connect a LAB-MOBI channel to a DUT, when the power system is located in a different place. Both wall mounted and free standing cabinets are available. A voltmeter is included, as is an indicator light which shows the status of the insolation monitoring (turned off or active). A short-circuit switch for safe connection of a DUT when operating in quadrant 4 is available for certain models (battery simulator mode only).

Power Distribution Switch Boards

PDSB control cabinets can be provided for remotely switching the output of a single LAB-MOBI channel between separate test cells, or for connecting the two separate LAB-MOBI channels in parallel to a nominated test cell. Up to four discharge units can also be installed in the cabinet on request.

Each LAB-MOBI features constant power, constant current, constant power and internal resistance operation. As standard the power system operates in battery testing mode. This is ideal for testing battery power components and provides users with the benefits of:

• High dynamics during current changes
• Output filter with lower capacitance
• Control mode: current (CC)
• Fast current rise time
• Current ripple <0.1% f.s. rms at VDC>10VDC

Battery Simulation (Option /SIM)

When testing battery powered devices, the LAB-MOBI can also be installed with a battery simulation mode (/SIM) instead of the standard battery tester mode. Where you require to both test and emulate batteries, the system can be installed with both operating modes (/SIM-TEST), which are user switchable between the two. The battery simulation mode provides users with the benefits of:

• Low voltage dip during current transients
• Output filter with higher capacitance
• Control mode: voltage (CV)

LAB-MOBI systems have Active Power Factor Correction (PFC) circuit integrated into the input stage as standard. This enhances the overall efficiency of the systems across the output power range when compared to a unit that does not have active PFC. In practice, this means a significant lower peak current value, a decrease of RMS value of the phase current and less perturbations of other equipment running on the same grid.

TFT Touchscreen

The LAB-MOBI comes with a simple and intuitive TFT touchscreen with a menu driven interface which allows measuring and setting of V, I, P and Ri values among others. The interface provides users with the convenience of remote access when setting test values. Up to 4 output channels can be controlled through the same user interface, providing users with a central point of programming.

Current and voltage ramps are programmable should you need to replicate a defined output for a specific research application. An event log is also provided which provides details of user actions, warnings and faults. Up to 10 named users can be specified to operate the interface with varying levels of permission, each with their own password.

Remote Control Interfaces

A CAN 2.0 interface with dbc file is provided as standard. This operates at 100Hz. The fast sampling frequency allows users to record quickly changing data, so that they can identify what’s happening at a particular point in time. A MODBUS is also provided along with VNC over Ethernet.

The VNC over Ethernet interfaces allows the touchscreen to be controlled via a PC. This feature is particulary useful for remote operation where the system may be operating in a potentially hazardous environment, or isolated from the device under test. 

Other interfaces are optionally available including PROFIBUS, PROFINET and a high speed 0-10V analogue interface which operates at 250Hz.

Soft tools for LabVIEW integration are optionally available (/LABVIEW).

Stop Button

Each channel of the LAB-MOBI is built with a black stop button as standard. This only shuts down a particular channel. For a complete system shutdown of all channels, an emergency stop circuit is provided which meets performance level d according to EN ISO 13849-1. A red emergency stop button is optionally available (option /E-STOP).

OVP, UVP, OCP & OTP Protection

Over voltage and over current protection limits can be adjusted to help safeguard sensitive loads. An under voltage limit can be also be user set to prevent a deep discharge which could potentially damage a battery pack.

Blocking Diode (Option /DIODE-1000)

A blocking diode is available to provide protection for the device under test against any back EMF. This is particularly useful to prevent damage to unidirectional power sources such as fuel cells. The blocking diode can be built into the existing cabinet(s) of the LAB-MOBI system (adding 200mm to cabinet width), or in its own external cabinet.

Discharge Unit (Option /DCU-2-500)

Discharge units are available as an additional safety feature. When the DC output is turned off, energy from the device under test will be discharged into a resistor at up to 500kW. This ensures that there is no residual energy on the DC link when disconnecting a device under test. This feature also works when the emergency stop button is pressed.

DC Disconnectors (Option /DC-1000A-1000V)

DC contactors are available that are linked to the safety system as standard. If the emergency stop is triggered the contactors open. They are designed to be operated under load and have an expected lifetime of 10,000 switch cycles under load.

Each LAB-MOBI system is built for longevity. The lowest life components being the fans rated at 67,000h and electrolytic capacitors rated at 130,000h/15 years. This ensures that the systems are suitable for constant operation in long term projects.

As standard, each LAB-MOBI cabinet is rated to IP20. The base of each cabinet has slots in it so it can be easily moved around via pump trucks or forklifts. Cable entry is also provided via the bottom of the cabinet. The standard front to top airflow cooling system means that no distance between the wall and rear of the cabinet is required.

Cabinets builds up to IP54 are possible. On request, all cabinets can be painted in your chosen RAL colour e.g. Signal White (RAL 9003).

If your test requirement is short term, we have bidirectional DC systems in our rental range up to 216kW/2000V/2704A.

One of the most common uses of the LAB-MOBI is the production testing of electric drives. The bidirectional nature of each system allows it actively decelerate the drive at the end of testing. This increases efficiency as you don't have to wait for a motor to freely spin and stop before you can test the next one. 

Another popular application is powering two dynamometers operating back to back, as it can feed DC energy into the circuit to compensate for any losses. The system's fast response time allows it to react to any sudden motor step changes during testing. 

When functioning as a load, selected models will operate from 1200V all the way down to 10V without current derating. This allows the same system to test 48V mild hybrids and high voltage pure electric vehicles. Other common applications include fuel cell loading, testing flywheels, battery cycling, component lifetime testing, as well as the testing of inverters and DC-DC converters.