Method and device for controlling load and voltage in voice coils

An apparatus comprising:

• an input configured to receive a detected current flowing through a load of a system, where the load comprises an inductive element;
• an output configured to provide a signal configured to excite the load;
• and
• a controller configured to:
• excite the load with a known duty cycle for a time interval following a start time;
• at an end time at an end of the time interval, receive a sensed end current flowing through the load;
• and
• calculate a lumped term based at least in part on the time interval and a change in the load current during the time interval,
• where the lumped term is representative of the supply voltage and at least one electrical characteristic of the load.

A computer-readable medium tangibly encoding a computer program comprising program instructions, execution of the program instructions resulting in operations comprising:

• exciting a load in a system comprising the load and a supply voltage with a known duty cycle for a time interval following a start time, where the load comprises an inductive element;
• at an end of the time interval, sensing, at an end time, an end load current, where a load current flows through the load;
• and
• calculating a lumped term based at least in part on the time interval and a change in the load current during the time interval, where the lumped term is representative of the supply voltage and at least one electrical characteristic of the load.

An apparatus comprising:

• means for exciting a load in a system comprising the load and a supply voltage with a known duty cycle for a time interval following a start time, where the load comprises an inductive element;
• means for sensing, at an end time of the time interval, an end load current, where a load current flows through the load;
• and
• means for calculating a lumped term based at least in part on the time interval and a change in the load current during the time interval,
• where the lumped term is representative of the supply voltage and at least one electrical characteristic of the load.