An ignition device for igniting an air/fuel mixture in a combustion chamber, in particular of an internal combustion engine, having a spark plug which has a first electrode and a second electrode, having a high voltage source for generating an electrical high voltage pulse at an output of the high voltage source, and having a high frequency voltage source for generating an electrical high frequency alternating voltage at an output of the high frequency voltage source, wherein the output of the high voltage source is connected electrically to the first electrode of the spark plug via a first electrical conduction path in such a way that the high voltage pulse is present at the first electrode, wherein the output of the high frequency voltage source is connected electrically to the second electrode via a second electrical conduction path in such a way that the high frequency alternating voltage is present at the second electrode.

An ignition coil control device includes: an energization control unit that controls to energize an ignition coil by first energization control and second energization control shorter in energization time than the first energization control; a cruise area determination unit that determines that a driving area of a vehicle is located in a cruise area on the basis of a throttle opening and an engine speed; and an integration counter that is incremented every predetermined time when the first energization control is being executed in the cruise area and is decremented every predetermined time in other cases. When a counter value of the integration counter reaches an upper limit value, a cooling process of switching from the first energization control to the second energization control is executed. Such ignition coil control device can appropriately switch energization time while preventing excessive heating of an ignition coil without using a current sensor.

An ignition coil control device includes: an energization control unit that controls to energize an ignition coil by first energization control and second energization control shorter in energization time than the first energization control; a cruise area determination unit that determines that a driving area of a vehicle is located in a cruise area on the basis of a throttle opening and an engine speed; and an integration counter that is incremented every predetermined time when the first energization control is being executed in the cruise area and is decremented every predetermined time in other cases. When a counter value of the integration counter reaches an upper limit value, a cooling process of switching from the first energization control to the second energization control is executed. Such ignition coil control device can appropriately switch energization time while preventing excessive heating of an ignition coil without using a current sensor.

A semiconductor device includes a power semiconductor switching element including a characteristic test terminal, and a control circuit configured to control an operation of the power semiconductor switching element. The power semiconductor switching element and the control circuit are formed in a same chip. The control circuit includes a gate voltage generation circuit configured to generate a current limit gate voltage for restricting an overcurrent flowing in the power semiconductor switching element in a desired range when an abnormality occurs, based on a characteristic of the power semiconductor switching element which is measured in advance by applying a voltage to the characteristic test terminal.

Circuits and methods to control a current in a coil are disclosed. The circuit and methods provide over-dwell protection and soft shut-down functionality to safely discharge the coil. The safe discharge of the coil is facilitated by a soft-start ramp signal that reduces the coil current gradually by controlling a switching device according. A profile of the soft-start ramp signal over time determines the gradual reduction. The profile of the soft-start ramp signal can be adjusted to set (i) an over-dwell period of the coil current, after which the coil current is shut down, and (ii) a soft shut-down period, over which the coil current is gradually reduced.

Circuits and methods to control a current in a coil are disclosed. The circuit and methods provide over-dwell protection and soft shut-down functionality to safely discharge the coil. The safe discharge of the coil is facilitated by a soft-start ramp signal that reduces the coil current gradually by controlling a switching device according. A profile of the soft-start ramp signal over time determines the gradual reduction. The profile of the soft-start ramp signal can be adjusted to set (i) an over-dwell period of the coil current, after which the coil current is shut down, and (ii) a soft shut-down period, over which the coil current is gradually reduced.

A current control circuit for an ignition system (i.e., igniter current limiter) is disclosed. The current control circuit can reduce a coil current over a soft shut down (SSD) period using an insulated gate bipolar transistor (IGBT) that is controlled by a negative feedback loop, which controls the current limit of the IGBT according to a SSD profile. In order to prevent an unwanted current rise during the soft shut down period, the current control circuit compares a gate voltage of the IGBT to a reference signal and based on the comparison can enable the SSD profile to include a fast ramp. The fast ramp quickly lowers the current limit of the IGBT so that the coil current equals the current limit and can be controlled by the negative feedback loop.

A circuit configured to control a switching device to reduce a current in a charged coil is disclosed. The circuit is configured to monitor a kickback voltage generated by the decreasing current in the coil. The circuit is further configured to adjust a rate at which the current is reduced in order to limit the kickback voltage. Limiting the kickback voltage during shutdown can prevent a spark at a spark gap that is inductively coupled to the coil and can allow for greater flexibility in the time taken to shut down the coil without overheating components or generating an unwanted spark. Additional, limiting the kickback voltage during shutdown can allow for a pseudo ramp wave to control the circuit during the shutdown because voltage spikes cause by abrupt changes in the pseudo ramp wave are limited.

In an implementation, a method of operating an ignition circuit can include enabling a charge path control circuit and a switch circuit to charge a primary winding of an ignition coil of the ignition circuit until a threshold current is reached in the primary winding. After reaching the threshold current in the primary winding, the method can include maintaining a current in the primary winding of the ignition coil in correspondence with a current limit by alternatively activating and deactivating the charge path control circuit complementary to alternative activation and deactivation of a circulating-current path control circuit. During the maintaining the current in the primary winding, the method can include initiating a spark in a spark plug included in the ignition circuit, the initiating the spark including controlling an amount of energy delivered from the primary winding to a secondary winding of the ignition coil.

An ignition system for an internal combustion engine includes an ignition coil forming a part of a primary circuit and a secondary circuit, a power source to supply power to the ignition coil, and a controller to determine whether the ignition coil is a recognized ignition coil based on a measured risetime and a measured current level in the primary circuit, the measured current level being lower than that required to create a breakdown voltage of the ignition coil.