Method for sensing and controlling the position of a variable reluctance actuator

A method of operating a variable reluctance actuator of the type comprising a coil, for producing a magnetic field in response to an electrical current therein, and an actuator at least two portions of which comprise magnetic material forming a magnetic circuit with said coil, said two portions of said actuator being mounted for movement relative to each other throughout a range of relative movement, and the reluctance of said magnetic circuit being variable in response to said relative movement, said method comprising:

• (a) within said range of relative movement, changing the magnitude of said electrical current in said coil;
• (b) throughout said range of relative movement, sensing the flux density of said magnetic field at a location in said magnetic circuit and producing a first electrical signal in response to the magnitude of said flux density at said location;
• (c) throughout said range of relative movement, and separately from step (b), sensing the magnitude of said electrical current in said coil and producing a second electrical signal representative of the magnitude of said electrical current and proportional to any change in the magnitude of said electrical current;
• and
• (d) sensing, in response to said first and second electrical signals, the relative position of said two portions of said actuator throughout said range of relative movement.

A method of operating a variable reluctance actuator of the type comprising a coil, for producing a magnetic field in response to an electrical current therein, having a diode connected to said coil for conducting electrical current in said coil generated by any reduction of said magnetic field, and an actuator at least two portions of which comprise magnetic material forming a magnetic circuit with said coil, said two portions of said actuator being mounted for movement relative to each other throughout a range of relative movement, and the reluctance of said magnetic circuit being variable in response to said relative movement, said method comprising:

• (a) within said range of relative movement, changing the magnitude of said electrical current in said coil;
• (b) throughout said range of relative movement, sensing the flux density of said magnetic field at a location in said magnetic circuit and producing a first electrical signal in response to the magnitude of said flux density at said location;
• (c) throughout said range of relative movement, and separately from step (b), sensing the magnitude of said electrical current in said coil and producing a second electrical signal representative of the magnitude of said electrical current, including the electrical current conducted by said diode during any reduction of said magnetic field, and proportional to any change in the magnitude of said electrical current;
• and
• (d) sensing, in response to said first and second electrical signals, the relative position of said two portions of said actuator throughout said range of relative movement.