Using sensed stator terminal voltages for determining alternator rotor position for cranking an engine

Claim 1

A method for determining rotor position of an n-phase alternator driven by an inverter, the alternator having a stator and a rotor and, in operation, having n stator terminal voltages and a neutral voltage, the inverter being connected between relatively positive and negative power busses, the method comprising the steps of: sensing the stator terminal voltages of the alternator with respect to the negative power bus; calculating the alternator neutral voltage by adding the stator terminal voltages and dividing by n; determining the stator terminal voltages with respect to the alternator neutral voltage by subtracting the alternator neutral voltage from each respective stator terminal voltage; filtering and clamping the stator terminal voltages with respect to the alternator neutral voltage using a predetermined time constant and upper and lower voltage limits; applying a hysteresis loop to the outputs of the filtering and clamping step to provide filtered output states plus hysteresis such that if a respective filtered output state plus hysteresis is greater than zero, then the corresponding stator state is zero, otherwise the corresponding stator state is one; and combining the resulting stator states to provide a simulated rotor position state.

Claim 2

A method for determining rotor position of an n-phase alternator driven by an inverter, the alternator having a stator and a rotor and, in operation, having n stator terminal voltages and a neutral voltage, the inverter being connected between relatively positive and negative power busses, the method comprising the steps of: sensing the stator terminal voltages of the alternator with respect to the negative power bus; calculating the alternator neutral voltage by adding the stator terminal voltages and dividing by n; determining the stator terminal voltages with respect to the alternator neutral voltage by subtracting the alternator neutral voltage from each respective stator terminal voltage; filtering and clamping the stator terminal voltages with respect to the alternator neutral voltage using a predetermined time constant and upper and lower voltage limits; applying a hysteresis loop to the outputs of the filtering and clamping step to provide filtered output states plus hysteresis such that if a respective filtered output state plus hysteresis is greater than zero, then the corresponding stator state is zero, otherwise the corresponding stator state is one; and combining the resulting stator states to provide a simulated rotor position state.

Claim 3

A system for determining rotor position of an n-phase alternator driven by an inverter, the alternator having a stator and a rotor and, in operation, having n stator terminal voltages and a neutral voltage, the inverter being connected between relatively positive and negative power busses, comprising: voltage sensors for sensing the stator terminal voltages of the alternator with respect to the negative power bus; a circuit for calculating the alternator neutral voltage by adding the stator terminal voltages and dividing by n; a comparator for determining the stator terminal voltages with respect to the alternator neutral voltage by subtracting the alternator neutral voltage from each respective stator terminal voltage; a filter/clamp circuit for filtering and clamping the stator terminal voltages with respect to the alternator neutral voltage using a predetermined time constant and upper and lower voltage limits; a hysteresis loop for receiving the outputs of the filter/clamp circuit to provide filtered output states plus hysteresis such that if a respective filtered output state plus hysteresis is greater than zero, then the corresponding stator state is zero; otherwise the corresponding stator state is one; and a combining circuit for combining the resulting stator states to provide a simulated rotor position state.

Claim 4

A system for determining rotor position of an n-phase alternator driven by an inverter, the alternator having a stator and a rotor and, in operation, having n stator terminal voltages and a neutral voltage, the inverter being connected between relatively positive and negative power busses, comprising: voltage sensors for sensing the stator terminal voltages of the alternator with respect to the negative power bus; a circuit for calculating the alternator neutral voltage by adding the stator terminal voltages and dividing by n; a comparator for determining the stator terminal voltages with respect to the alternator neutral voltage by subtracting the alternator neutral voltage from each respective stator terminal voltage; a filter/clamp circuit for filtering and clamping the stator terminal voltages with respect to the alternator neutral voltage using a predetermined time constant and upper and lower voltage limits; a hysteresis loop for receiving the outputs of the filter/clamp circuit to provide filtered output states plus hysteresis such that if a respective filtered output state plus hysteresis is greater than zero, then the corresponding stator state is zero; otherwise the corresponding stator state is one; and a combining circuit for combining the resulting stator states to provide a simulated rotor position state.