Curtis inverters

Using a Curtis inverter with a Lithiumate Pro BMS.

The Lithiumate Pro may control a Curtis 123x motor inverter either though wire control or through CAN messages.

WARNING: SHOCK DANGER

The Curtis motor controllers do not provide isolation between the high voltage battery and the low voltage circuits.

This poses a significant risk of shock and of likely damage to the low power electronics by way of a single unintentional short circuit.

This proposed ciruit adds isolation to the Curtis motor controller to improve safety.

The system has a traction pack and an auxiliary 12 V battery.

The ignition switch is on the 12 V battery, not the traction pack.

When the ignition is on, and if discharging is OK, the Lithiumate Pro master turns on K1, which powers the Curtis inverter, from the traction pack to the KSI input.

The Lithiumate Pro master limits the discharge current through its DCL analog output, by reducing the range available to the throttle.

It limits the regen current through its CCL analog output, by reducing the range available to the brake.

Isolation is achieved by:

• The DC-DC converter is isolated
• Optoisolators H1 and H2 isolate the CCL and DCL outputs from the high voltage on the Curtis Inverter
• Relay K1 isolates Key input of the Curtis

High Performance Electric Vehicles (HPEVS) offers a complete solution that includes a Curtis inverter and an Elithion Lithiumate Pro BMS, with the VCL programming already done for you.

The Curtis 123x inverter motor drivers are normally controlled through the CAN bus.

Therefore, they require a VCU (Vehicle Control Unit) ECU (Electronic Control Unit), which provides the interface between the inverter and the remainder of the system (including a BMS). The VCU must be programmed to work with all the components in the system, including the Brusa Inverter and the BMS (such as the Elithion Lithiumate).

Unlike other motor drivers, these inverters do include VCU hardware. The user needs to program these motor inverters to work with the remainder of the system, through Curtis' "VCL" programming language.

In 2011, Elithion and Curtis actively worked together to develop a solution to enable direct interface between our two products. Unfortunately, Curtis never followed through with its part of the collaboration.

Isolating a Curtis 123x motor inverter when a CAN bus is used can be done externally, but is quite involved; instructions on how to do so are beyond the scope of this application note.