Method and system for controlling a synchronous machine using a changeable cycle-conduction angle

摘要

Method and system for controlling a synchronous machine including a polyphase stator are provided. The machine may be used in a piece of equipment respectively as a generator and as a motor for starting an engine in the piece of equipment. The method allows to sense rotor position of the machine using a sensor assembly configured to supply a respective stream of pulses indicative of rotor position relative to each phase of the machine. The method further allows to process each stream of pulses from the sensor assembly to generate a first set of inverter control signals. The first set of inverter control signals is applied to an inverter circuit coupled to energize the phases of the stator to start the machine. The first set of control signals is configured to provide a first cycle-conduction angle relative to the zero-crossings of the respective phase EMF voltages of the machine to produce a sufficiently high level of torque during start of the machine. Upon the rotor reaching a predefined rotor speed value, each stream of pulses from the sensor assembly is processed to generate a second set of inverter control signals. The second set of inverter control signals is applied to the inverter circuit to energize the phases of the stator. The second set of control signals is configured to provide a second cycle-conduction angle relative to the zero-crossings of the respective phase EMF voltages of the machine to enable a sufficiently high rotor speed and thus facilitate the occurrence of a successful cranking event for the engine of the piece of equipment.