Standard features and capabilities
Intended use of the Dragon8
The Dragon8 motor controller can be used in many applications, such as:
• On-road 4 wheel EV
• Wheel electric motorcycle and scooter
• Off road ATV
• Utility vehicles and burden carriers
• Hybrid vehicle systems
Available accessories
The following accessories are available from Sevcon
• DC-DC converters
• 23 way Ampseal connector kit
• Contactors
• Fuses
• DVT - PC based configuration tool
Principles of operation
Functional description
The main function of Dragon8 is to control the power an electric motor (PMAC (SPM and IPM) and
Induction).
Measured phase currents and current demands are used as part of a closed-loop control system to
calculate the necessary voltage demands for each phase of the motor. Voltage demands are then
converted into PWM demands for each phase.
Dragon8 electrical block diagram
The electrical circuit blocks are present in Dragon8 have the following functions:-
• Inverter power stage – this converts the DC battery supply into AC to power the motor. See the
following section for more details.
• Gate drives – the low power gate control signal from the control logic is isolated and buffered by
these circuits. Output short circuits are also detected by these circuits.
• Current and voltage measurement – these circuits provide an isolated voltage and current
measurement for the control logic. Over-current and over-voltage conditions are also detected.
• Control power supplies – these convert a 12V or 24V nominal supply into the voltage required for the
control logic
• Control logic – software runs on microprocessor circuits with input and output circuits for analogue
and digital inputs, the encoder, CANbus and digital outputs.
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