Vehicle battery, BMS and charging electronics with comemso integration test systems

Applications / EVCC + BMS + OBC integration testing

EVCC, BMS and OBC Integration Testing

The EV communication controller (EVCC) negotiates charging, the battery management system (BMS) sets battery limits, and the onboard charger (OBC) converts AC power for the battery. Test whether their messages and electrical responses agree.

Configure the integrated EV test Review AC and DC test paths

Vehicle scopeEVCC, BMS, OBC, VCU, contactors and charging interface

AC and DCOBC path for AC; direct battery path for DC charging

One time baseProtocol, CAN, signals, voltage, current and controller states

Repeatable evidenceKeep configuration, condition, reaction and result linked

Test scenario: Follow one condition through the controllers

Illustrative test: the BMS detects a temperature that requires a lower charging current. The EVCC must communicate the changed limit. During AC charging, the OBC must adjust its operation accordingly; during DC charging, the external charger supplies the battery-side power. Compare the limit message and measured current on the same timeline.

One charging decision across EVCC, BMS and OBC.

Test how charging negotiation, battery permission and the physical response agree on an ECU bench, a vehicle subsystem or a complete EV. Set the battery state and charging counterpart, then verify the controller decisions and measured consequence on one timeline.

The AC path includes the OBC; direct DC CCS, CHAdeMO and GB/T DC charging bypasses it. Cell-level BMS validation and pack-level power remain distinct parts of the configured test environment.

One vehicle state across every controller

A valid charging message can still represent an invalid vehicle decision.

The EVCC may request a formally valid voltage and current while the BMS has already reduced the permitted power, detected an isolation problem or requested a stop. The individual controllers can appear correct on separate benches while their combined decision is inconsistent.

One electric-vehicle decision chain

A valid message is not enough.

Every controller must describe the same vehicle state.

EVCA

Represents the EVSE
- Charging protocol
- Low-level states
- Power and fault context
- Controlled counterpart
EVCC

Negotiates charging
- Voltage and current request
- Service and protocol state
- Certificates and timing
- Stop and error messages
BMS

Permits battery use
- SOC and power limits
- Temperature and isolation
- Contactor permission
- Fault and recovery state
Vehicle controls

Coordinate the action
- VCU and thermal control
- Pre-charge and contactors
- OBC enable and derating
- Safe-state coordination
Physical response

Executes the decision
- OBC or direct DC path
- Voltage and current
- Safe stop and recovery
Synchronised evidence in comframe
- EVCC messages
- BMS and vehicle CAN
- OBC and contactors
- Voltage and current
- Expected relation

Limit mismatch

The EVCC requests more voltage, current or power than the BMS currently permits.

State mismatch

Charging readiness, contactors, isolation and protocol state no longer describe the same vehicle condition.

Delayed consequence

A battery or thermal event reaches the charging communication or power interface too late.

Unattributed stop

The session ends correctly at the final layer, but the initiating cross-system deviation remains hidden.

Integrated AC charging and EV OBC testing

Test the onboard charger together with the controllers that enable, limit and stop it.

During AC charging, the OBC is part of the vehicle energy path. A complete EV OBC test therefore combines the AC charging interface, EVCC negotiation, BMS permission, VCU coordination, contactor logic, thermal limits, OBC conversion behaviour and the battery-side condition.

Charging negotiation

Does the requested AC operating point match the battery state?

Correlate the EVCC request with BMS voltage, current, SOC, temperature and safety limits before the OBC is enabled.

OBC execution

Does the converter follow the permitted command?

Verify enable, power factor, efficiency, derating, diagnostics, current response and controlled shutdown in the configured test depth.

Vehicle coordination

Do VCU, thermal control and contactors agree?

Test pre-charge, high-voltage enable, thermal reduction, fault propagation and recovery as one vehicle sequence.

AC path. Grid and EVSE counterpart → vehicle inlet and OBC → high-voltage bus and battery environment. EVCC, BMS and vehicle controls remain part of every decision.

Illustration of an AC onboard charger test: grid and EVSE conditions, vehicle control, OBC and battery emulation in one synchronized view — AC power passes through the OBC before reaching the HV battery path. BCS supplies cell and sensor signals to the BMS. A separate power source/load or battery emulator handles the HV power path; the BCS does not provide pack-level charging power. Conceptual illustration.

Direct DC charging integration

For DC CCS, CHAdeMO and GB/T DC, the OBC is bypassed. The control problem remains.

During direct DC charging, the charging station supplies the high-voltage battery path through the vehicle inlet and contactors. The EVCC, BMS, VCU, isolation monitoring, thermal control and switching sequence must still agree on the permitted operating point and the correct response to a changing limit or fault.

DC CCS

PLC charging communication

Coordinate DIN 70121 or ISO 15118 communication with Control Pilot (CP) and Proximity Pilot (PP) state, requested limits, contactors, isolation, voltage and current.

CHAdeMO

CAN-based charging communication

Relate CHAdeMO messages and timing to battery permission, charging state, physical output and safe stopping behaviour.

DC China / GB/T DC

GB/T 27930 and vehicle state

Correlate GB/T communication, interface conditions, BMS limits, contactor sequence and the measured DC response.

Exact protocols, editions, low-level interfaces, power ranges and fault functions depend on the selected EVCA, BCS, comframe and external power configuration. The Supported Standards and product pages remain authoritative for released scope.

Illustration of DC charging integration testing: EVSE simulation, EVCC, BMS and VCU, the battery path bypassing the OBC, and BCS with hardware-in-the-loop signals — DC charging reaches the HV battery path through the inlet and contactors; the OBC is bypassed. BCS supplies cell and sensor signals to the BMS. A separate power source/load or battery emulator handles the HV power path; the BCS does not provide pack-level charging power. Conceptual illustration.

From nominal charging to coordinated fault response

Challenge how battery limits become charging behaviour.

Change one controlled condition at a time. Preserve the charging request, battery state, controller reactions and physical result so the pass criterion includes both the correct state and the correct timing.

Charging start

Validate wake-up, readiness, pre-charge, contactors, negotiated limits and the transition into energy transfer.

Dynamic power limits

Change the BMS-permitted voltage, current or power and verify how quickly the EVCC and physical path follow.

Thermal derating

Apply cell, pack, OBC or cooling limits and confirm coordinated reduction instead of unstable control behaviour.

Isolation or HVIL event

Verify detection, communication, switching sequence, safe state and recovery after a defined safety condition.

OBC fault or derating

Check whether converter diagnostics and available power are reflected consistently in BMS, EVCC and VCU states.

Contactor or pre-charge mismatch

Challenge the relationship between protocol readiness, physical switching and measured high-voltage behaviour.

Communication mismatch

Inject delayed, missing or inconsistent vehicle-network and charging information where the configuration supports it.

Controlled stop and recovery

Confirm stop reason, message sequence, current ramp, contactor opening, residual states and restart behaviour.

Cross-system correlation

Find the first inconsistency, not only the final charging error.

comframe can place charging communication, vehicle-network states, BMS limits, OBC or direct-DC behaviour and electrical measurements on a shared time base. The engineer can then review whether every system reacted to the same condition within the required time.

Illustrative synchronized comparison of EVCC communication, BMS limits, vehicle network, power-path response, voltage and current — Illustrative comparison, not a measured trace or software screenshot. A common timeline helps compare a changed battery limit with communication and electrical responses. Investigate the first relevant inconsistency using the recorded values and applicable test criteria.

Integration validation matrix

Connect each changed condition to the expected vehicle consequence.

On smaller screens, scroll the table horizontally to see every column.

System or signal	Nominal relation	Changed condition	Expected consequence	Required evidence
EVCC request	Request remains inside current BMS permission	Voltage or current demand exceeds a new limit	Request is reduced or charging stops within the defined timing	Message, timestamp, active limit and physical response
BMS permission	SOC, temperature, isolation and cell states permit charging	Thermal, cell or safety boundary is reached	Permitted power changes and the responsible controllers react coherently	BMS state, CAN signal, diagnostic reason and release condition
OBC or direct DC path	Power conversion or direct battery path follows the permitted operating point	Converter derating, DC limit or power-stage fault	Actual voltage and current remain consistent with the communicated state	Command, converter or power-path state, measured voltage and current
Contactors and pre-charge	Switching state matches charging readiness and high-voltage conditions	Pre-charge timeout, contactor mismatch or unexpected opening	Energy transfer is inhibited or stopped without an invalid intermediate state	Contactor command, feedback, HV bus and protocol transition
Isolation and HVIL	Safety conditions permit the selected charging phase	Isolation or interlock state becomes invalid	Fault is propagated and the system reaches the defined safe state	Measured condition, diagnostic path, stop reason and recovery sequence
Vehicle network	EVCC, BMS, VCU, OBC and thermal controller share consistent information	Message loss, latency or conflicting state	Timeout, fallback or safe stop follows the approved strategy	CAN or Ethernet timing, controller state and resulting charging behaviour

Physical systems and software form one integrated EV test environment.

EVCA + Battery Cell Simulator + comframe

EVCA controls the charging-station counterpart. The Battery Cell Simulator controls the battery signals seen by the BMS. comframe connects configuration, synchronised measurement, automation and evidence. The customer environment supplies the real EV controllers and the authoritative vehicle safety concept.

System illustration connecting EVSE simulation, EVCC, OBC, BMS, vehicle control and Battery Cell Simulation through synchronized comframe evidence — Conceptual system illustration; not a screenshot of the released comframe user interface. The selected configuration defines interfaces and supported scope.

EVCA

Charging-station counterpart

EVSE (electric vehicle supply equipment, or charging station) simulation, communication, low-level states, charging measurements, configurable behaviour and applicable faults.

Explore the EVCA platform

Battery Cell Simulator

Controlled battery state

Virtual cells, temperature sensors, balancing, isolation, current-related conditions and electrical fault states.

Explore the BMS tester

comframe

Configuration and evidence

Time-correlated charging and vehicle data, automation, expected relationships, results and integration interfaces.

Explore comframe

External power equipment

Project-specific energy path

Grid emulation, battery emulation, source, sink, power measurement, cooling and safety are selected for the AC or DC test objective.

Complete vehicle charging test in a comemso laboratory — Complete-vehicle test with a real EV and charging-station simulation.

Illustration of an integrated BCS and EVCA test system with charging emulation, cell simulation, EVCC, BMS, measurement and control — Illustrative integrated BCS and EVCA setup: charging emulation, cell simulation and correlated measurement and control. Open the full-size system illustration

The joint comemso and Cinergia architecture in the supplied reference brochure demonstrates one integration path for grid and battery emulation around EVCA. The final external power hardware is project-specific and is not limited to one supplier.

Prepare, execute and retain one integration test.

Define the real and simulated controllers, vehicle networks and power path. Configure battery state, charging counterpart and the nominal, boundary or fault condition within the approved power, cooling and safety setup.

During execution, correlate charging messages, BMS and vehicle-network states, OBC or direct-DC behaviour, contactors and electrical measurements. Retain the DUT versions, configuration, deviations and results for regression.

Explore the related test scope.

Continue to EV Testing for the vehicle lifecycle, BMS Testing for cell-level validation, or the EVCA and BCS product pages for system selection.

Supported Standards and the released Test Libraries define the relevant verification scope.

For teams responsible for the combined vehicle response.

Vehicle OEMs coordinate charging release across controllers. EVCC and BMS suppliers verify their interface responsibilities, while OBC teams relate converter diagnostics and derating to permitted battery limits. Laboratories can repeat the same scenarios across hardware and software variants.

Customer references

Vehicle-side charging validation in practice.

The following customer experiences relate to testing with our EVCA systems.

Digital laboratory

Customer outcomeThe team describes EVCA as its most complete vehicle simulation, sniffer and man-in-the-middle system.

Charging laboratory

Customer outcomeA long-running collaboration continues with another comemso hardware upgrade for the EFECT laboratory.

Free BMS testing whitepaper

Planning BMS temperature tests?

Explore the practical questions behind cold starts, heat exposure, climate-chamber wiring and reliable cell and sensor simulation.

Illustration of an engineer planning BMS thermal validation with cell simulation and a climate chamber

Explore the BMS testing whitepaper

Frequently asked questions

EVCC, BMS and OBC integration testing

Why should EVCC and BMS be tested together?

The EVCC negotiates charging while the BMS determines the battery limits and safety-related permission. Requested voltage and current, SOC, temperature, isolation, contactors and faults must remain consistent. Separate ECU tests cannot prove that the vehicle reaches the correct combined state.

Why is the OBC part of this integration test?

During AC charging, the onboard charger converts grid-side AC power into DC power for the high-voltage battery. Its enable, current demand, derating, diagnostics and stop behaviour are commanded or constrained by EVCC, BMS, VCU, thermal control and contactor states. Testing the OBC alone does not prove that the complete EV charging system behaves correctly.

What changes during direct DC charging?

For DC CCS, CHAdeMO and GB/T DC, the external charging station supplies the high-voltage battery path through the inlet and contactors. The OBC is bypassed in the energy path, but EVCC, BMS, VCU, isolation monitoring, contactors and thermal control still coordinate the request, permission and safe physical response.

Can the integration be tested before a complete vehicle exists?

Yes. EVCA can provide the charging-station counterpart while the Battery Cell Simulator supplies controlled cell, sensor, balancing, isolation and fault conditions to the BMS. Customer vehicle networks, controllers and HiL components can then form a subsystem bench before the complete vehicle or traction battery is available.

Which charging technologies are relevant to EVCC–BMS integration testing?

The current application scope covers AC charging with the OBC and direct DC vehicle charging for DC CCS, CHAdeMO and DC China / GB/T DC. Exact standards, versions, connector hardware and available functions depend on the selected system release and configuration.

Which variables should be correlated?

Typical variables include requested and permitted voltage and current, SOC, cell and pack temperatures, isolation, contactor and pre-charge states, OBC commands and diagnostics, charging readiness, protocol messages, vehicle-network data, physical voltage and current, stop reasons and recovery timing.

Vehicle-side test planning

Define the charging behaviour your vehicle must prove.

Specify the real vehicle-side DUT, simulated charging-station role, interfaces and required evidence.

Configure your test system Contact application engineering