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OpenVVVF Documentation

OpenVVVF is an open-source Variable Voltage Variable Frequency (VVVF) traction inverter platform. A single control module runs the motor-control firmware and talks to one of several power-stage chassis. The same hardware can serve very different applications - motorcycle, passenger car, industrial drive, or rail - by selecting the right power stage and configuring the safety profile.

This site is the single source of truth for OpenVVVF hardware manuals, software documentation, safety analyses, and validation evidence.

System architecture

Major blocks

• Control module / control assembly - The reusable dual-MCU control board that runs OpenVVVF firmware. It handles field-oriented motor control, state estimation, diagnostics, and safety monitoring.
• Power stage - The physical inverter assembly that contains the IGBTs, DC-link capacitors, gate drivers, current sensors, and thermal hardware. Three chassis families are planned:
• C1 - compact, low-power form factor.
• C2 - mid-size, 140 V nominal / up to 450 V class, ~600 A.
• C3 - large, up to 1200 V / 1400 A.
• Main MCU software - The primary microcontroller firmware; runs the real-time motor-control loop, PWM generation, ADC sampling, communication stacks, and application logic.
• Safety coprocessor software - A separate microcontroller that independently monitors safety-critical outputs and can bring the system to a safe state.
• RTE Studio - The host-side Real-Time Examiner and tuning tool. It connects to the inverter over CAN or Ethernet to log variables, adjust parameters, and run calibration routines.
• Codegen tools - Code and parameter generation tools that keep firmware data structures in sync with the hardware model.

Data flow at a glance

RTE Studio / Codegen
       |
       | CAN / parameter files
       v
Control Module (Main MCU + Safety Coprocessor)
       |
       | PWM / gate-drive / sensor signals
       v
    Power Stage
       |
       | Three-phase output
       v
     Motor

Glossary

General terms

• OpenVVVF - Open-source Variable Voltage Variable Frequency traction inverter platform.
• VVVF - Variable Voltage Variable Frequency. A method for controlling AC motors by adjusting voltage and frequency.
• Traction inverter - A power-electronics converter that turns a DC bus into variable-frequency AC to drive a motor.
• Chassis - A mechanical/electrical form-factor family for power stages (C1, C2, C3).

Software terms

• MCU - Microcontroller Unit. The main processor running the motor-control firmware.
• Main MCU - The primary microcontroller on the control module; runs the motor-control loop.
• Safety coprocessor - A separate microcontroller that independently monitors safety-critical outputs.
• RTE - Real-Time Examiner. The host-side tool for logging, tuning, and calibrating the inverter over CAN or Ethernet.
• Codegen - Code/parameter generation tools that keep firmware data structures in sync with the hardware model.
• FOC - Field-Oriented Control. The motor-control algorithm used to drive AC machines.
• PWM - Pulse-Width Modulation. The technique used to synthesize variable voltages from a fixed DC bus.
• VCU - Vehicle Control Unit. A higher-level controller that commands the inverter in a vehicle.

Safety and compliance terms

• HARA - Hazard Analysis and Risk Assessment. A process for identifying hazardous events and assigning safety goals.
• TARA - Threat Analysis and Risk Assessment. The cybersecurity counterpart to HARA.
• FMEA - Failure Mode and Effects Analysis. A bottom-up method for analyzing how component failures affect the system.
• ISO 26262 - Automotive functional-safety standard.
• IEC 61800-5-2 - Industrial-drive safety standard.
• ASIL - Automotive Safety Integrity Level. A risk classification from A (lowest) to D (highest).
• HVIL - High-Voltage Interlock Loop. A safety circuit that detects when HV connectors are unmated.
• Safe state - A defined low-risk state the system enters after a fault.

Electrical / mechanical terms

• DC link - The DC bus capacitors and connections between the battery/supply and the inverter bridge.
• IGBT - Insulated-Gate Bipolar Transistor. The power switch used in the inverter bridge.
• Vdc - DC-link voltage.
• Vll - Line-to-line AC voltage.
• DCR - DC Resistance. The resistance measured at DC, typically used for motor phase resistance.
• LCR meter - Instrument for measuring inductance, capacitance, and resistance.
• Heatsink / baseplate - The metal surface that conducts heat away from the IGBT modules.

Documentation sections

Sponsors

A special thank you to our sponsors for helping make this project possible: