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Firmware Stable

Wiring

How to wire the SGCU (the starter generator control unit — the siliXcon controller running IGNIS) into the system.

Typical block diagram​

A typical genset built around IGNIS — shown in the high-availability variant with two SGCUs; a single-controller system simply omits the second generator and SGCU:

Solid lines are power, thick lines mechanical, dotted lines control:

  • Mechanical — the internal combustion engine (ICE) and the electrical machines share a common shaft. Each machine works as the starter and the generator at once.
  • Power — each generator connects 3-phase to its SGCU, and both SGCUs share the DC bus with the battery (or supercapacitor) and the host system's load. With the voltage limiter as the primary regulation, this bus behaves as a regulated DC source toward the host.
  • Control — everything meets on the CAN bus: the SGCUs synchronize as a pair and report the system status, the BMS supplies the battery current for the charging limiter, and the ECU managing the engine can follow the reported torque capability with the throttle. Each SGCU additionally drives an ignition relay in the engine kill circuit — see below.

Ignition (engine kill) relay​

Connect a relay to contactor 1. The relay must be wired so that the engine is shut down whenever the contactor is not powered (normally-closed kill circuit, or the ignition supply routed through the relay).

The application drives this output as the ignition: it is closed through the whole starting sequence and generation, and opened on every stop, fault and lockout. Its state is also broadcast on CAN as the ignition application flag — see CAN Messages.

You can configure the voltage used for controlling the relay using /common/contactor1/attack and /common/contactor1/hold. A negative value means a voltage, a positive value a duty cycle.

warning

Do not use the application without the kill relay. In emergency situations the controller must be able to shut down the engine.

Dual-controller kill circuit — safety vs. availability​

In a high-availability pair, each SGCU drives its own ignition relay, and how the two relays are combined decides the character of the system. There are two options:

  • AND — the engine runs only while both controllers allow it. Either controller can kill the engine on its own, with no dependency on the CAN link: the overvoltage kill always physically reaches the engine, even if the pair cannot communicate. The compromise: a dead or unpowered controller stops the engine — the running engine is no longer highly available.
  • OR — the engine runs while either controller allows it. A failed controller cannot stop the engine — the running engine stays highly available. The compromise: a single controller cannot kill the engine on its own. A system-wide kill then relies on both controllers opening their relays — which the overvoltage latch propagation performs over CAN within milliseconds, but not if the CAN link itself is down.

The contact topology follows from your kill scheme: with the ignition supply routed through the relays, AND means the contacts in series and OR in parallel; with a grounding-type (magneto) kill the topology is inverted.

There is no universally right choice — it depends on which failure is catastrophic in your system: an engine that cannot be stopped when it must be (choose AND), or an engine that stops when it must not (choose OR). The firmware behaves identically either way; this is purely an installation decision — make it consciously.

Generator start switch​

To start the generator with a switch, connect it between a GPIO input and +5 V and select the input with IN_gen. Switching it on starts the generator, switching it off stops it.

If you want the generator to start automatically when the controller is powered, set IN_gen to 0.

Which inputs are honored as a start request (the GPIO switch, the CAN control message, or both) is selected by start_sel — see Enabling.

warning

There is no arming interlock: a start request that is already active is honored as soon as nothing blocks it. Powering up the controller with the start switch ON starts the engine, and the engine restarts automatically after a transient fault clears. Design the installation with this in mind.

Dual-controller system​

For multi-master operation, both controllers mount on the same shaft and share:

  • the CAN bus — the pair synchronizes over it, and the host connects to the same bus,
  • the DC bus / battery,
  • the start switch, if GPIO start is used — each controller evaluates its own input, so the switch must be wired to the selected GPIO of both controllers,
  • each controller drives its own ignition relay — wire both into the kill circuit, combined as AND or OR depending on whether safety or availability has the priority in your system (see the kill circuit above).

Both controllers must run the same firmware version.