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.
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.
Set the battery state and charging counterpart on an ECU bench, vehicle subsystem or complete EV. Compare controller decisions and the measured response 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.
An EV OBC test combines the AC charging interface and OBC conversion with EVCC, BMS, VCU, contactor, thermal and battery-side conditions.
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.
Does the converter follow the permitted command?
Verify enable, power factor, efficiency, derating, diagnostics, current response and controlled shutdown in the configured test depth.
Do VCU, thermal control and contactors agree?
Test pre-charge, high-voltage enable, thermal reduction, fault propagation and recovery as one vehicle sequence.
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.
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.
CAN-based charging communication
Relate CHAdeMO messages and timing to battery permission, charging state, physical output and safe stopping behaviour.
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.
From nominal charging to coordinated fault response
Challenge how battery limits become charging behaviour.
Change one controlled condition at a time. For each run, record the charging request, battery state, controller reactions and physical result. Judge both the resulting state and its timing against the pass criterion.
Validate wake-up, readiness, pre-charge, contactors, negotiated limits and the transition into energy transfer.
Change the BMS-permitted voltage, current or power and verify how quickly the EVCC and physical path follow.
Apply cell, pack, OBC or cooling limits and confirm coordinated reduction instead of unstable control behaviour.
Verify detection, communication, switching sequence, safe state and recovery after a defined safety condition.
Check whether converter diagnostics and available power are reflected consistently in BMS, EVCC and VCU states.
Challenge the relationship between protocol readiness, physical switching and measured high-voltage behaviour.
Inject delayed, missing or inconsistent vehicle-network and charging information where the configuration supports it.
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.
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 |
EVCA + Battery Cell Simulator + comframe
Physical systems and software form one integrated EV test environment.
EVCA controls the charging counterpart, the Battery Cell Simulator supplies BMS inputs, and comframe links configuration, synchronised measurement, automation and evidence. The customer environment supplies the real vehicle controllers and the authoritative vehicle safety concept.
System components and integration details
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 platformControlled battery state
Virtual cells, temperature sensors, balancing, isolation, current-related conditions and electrical fault states.
Explore the BMS testerConfiguration and evidence
Time-correlated charging and vehicle data, automation, expected relationships, results and integration interfaces.
Explore comframeProject-specific energy path
Grid emulation, battery emulation, source, sink, power measurement, cooling and safety are selected for the AC or DC test objective.
The joint comemso and Cinergia architecture demonstrates one integration path for grid and battery emulation with EVCA. External power equipment is selected for the project 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 check their interface responsibilities. OBC teams compare converter diagnostics and derating with the permitted battery limits. Laboratories can repeat the same scenarios across hardware and software variants.
Frequently asked questions
EVCC, BMS and OBC: frequently asked questions
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
Plan the EVCC, BMS and OBC integration test.
Trace a changed battery limit through the charging request to the electrical response. Define AC and direct-DC scenarios, controller interfaces and expected timing before configuring the combined test setup.