Disclosed is an inventive method for controlling a corona ignition device of an internal combustion engine. A corona discharge, which ignites fuel in a combustion chamber of the engine, is generated by applying a voltage to the corona ignition device. An actual value that is characteristic of the nitrogen oxide concentration of the exhaust gas is compared with a setpoint value, and, if the actual value deviates from the setpoint value by more than a specified threshold value and the actual value is greater than the setpoint value, the voltage is reduced after the comparison.

A plasma ignition device 20 includes a spark plug 100, a DC power supply 210, an AC power supply 220, and a coupling section 300. The coupling section 300 includes a capacitor 320 which electrically connects the AC power supply 220 to the spark plug 100. The coupling section 300 reduces the capacitance of the capacitor 320 in the second ignition mode in which transmission of AC power is halted, as compared with that in the first ignition mode in which AC power is transmitted to the spark plug 100.

A control methodology and apparatus for an engine suitable for use in capacitor discharge ignition systems for internal combustion engines or brushless DC motors is provided, which make use of a simple logic block to determine for instance an ignition timing advance angle or duty cycle signal based on actual engine speed versus engine control parameter data stored in a table, which is a read-only memory, preferably configurable. To minimise memory space, a small number of values of engine control parameter versus engine speed are stored in the table and the logic block determines the required engine control signal for a measured value of engine speed by an interpolation process, preferably linear interpolation.

A control methodology and apparatus for an engine suitable for use in capacitor discharge ignition systems for internal combustion engines or brushless DC motors is provided, which make use of a simple logic block to determine for instance an ignition timing advance angle or duty cycle signal based on actual engine speed versus engine control parameter data stored in a table, which is a read-only memory, preferably configurable. To minimise memory space, a small number of values of engine control parameter versus engine speed are stored in the table and the logic block determines the required engine control signal for a measured value of engine speed by an interpolation process, preferably linear interpolation.

A linear electro-mechanical system comprising: a stator including at least first and second stator electronic circuits or groups of circuits; a free piston mover movable in a reciprocating motion relative to the stator, the free piston including: a piston surface; a translator configured so that an electromagnetic force may be applied on the free piston mover by one or more of the stator electronic circuits or groups of circuits; and one or more translator electronic circuits, the system further comprising a switching device for each of the first and second stator electronic circuits or groups of circuits such that the current in each of the first and second stator electronic circuits or groups of circuits is independently controllable, and wherein at least one of the translator electronic circuits is configured to receive power from at least one of the independently controlled stator electronic circuits or groups of circuits during at least part of the stroke of the free piston mover.