Igniter circuit with adjustable over-dwell time

Abstract

The invention relates to an igniter circuit with adjustable over-dwell time. An ignition system is provided that may include an igniter circuit that controls current in a coil powered by a battery based on an input signal from an engine control unit. To prevent overheating, the igniter circuit may be configured to turn off current in the coil when the input signal remains at a high level for an over-dwell period. The disclosed igniter circuit is configured with circuitry that automatically adjusts the over-dwell period used based on the state of the battery to prevent overheating without premature turn-off. The automatic regulation includes indirectly monitoring a battery state based on a current or voltage of a switching device coupled to the coil.

Description

Technical Field

[0001] The present disclosure relates to power electronics for switches, and more particularly to igniter circuits for automotive applications. Background Art

[0002] An automotive ignition system may include a battery, an induction coil, and an igniter circuit. The igniter circuit may include a switching device connected in series with the battery and the induction coil. When the switching device is short-circuited, current may flow from the battery through the induction coil. After a charging cycle, the switching device may be disconnected so that the current in the induction coil is abruptly terminated. The abrupt termination of the current may result in a large voltage across the coil, which may be used to generate a spark for ignition. The igniter circuit may monitor the charging cycle so that it does not exceed a maximum limit (i.e., an over-dwelling time) that may cause overheating and / or damage to the ignition system. Summary of the invention

[0003] After an over-dwell time (i.e., an over-dwell period), the current conducted by the coil in the ignition system can be gradually reduced through the igniter circuit to prevent damage (e.g., overheating). The present disclosure describes an ignition system and method for sensing the voltage of a battery and automatically adjusting the duration of the over-dwell time.

[0004] In some aspects, the technology described herein relates to a method for shutting off current in an ignition system, the method comprising: receiving an input signal to configure a switching device to be in an on state, the switching device being coupled in series with a coil; starting a timer; after the switching device is configured to be in the on state, sensing the current in the coil; based on the timer, measuring a rise time corresponding to the time when the current meets a standard; calculating a soft shut-off delay based on the rise time; waiting for the soft shut-off delay; and initiating a soft shut-off after the soft shut-off delay to reduce (i.e., shut off) the current in the coil.

[0005] In some aspects, the technology described herein relates to an ignition system comprising: a coil coupled to a battery on a first side; and an igniter circuit comprising: a switching device coupled to a second side of the coil; a current controller configured to control a current state of the switching device; and an over-dwell circuit configured to: measure a rise time of a current conducted by the switching device after being configured to be in an on state; and trigger the current controller to initiate a soft shut-down of the current after a soft shut-off delay, the soft shut-off delay being based on the rise time of the current.

[0006] In some aspects, the technology described herein relates to a method for shutting off current in an ignition system, the method comprising: receiving an input signal to configure a switching device to be in an on state, the switching device being coupled in series with a coil; delaying the input signal by a delay period to keep the switching device in an off state during the delay period before configuring the switching device to be in the on state; sensing a voltage of the switching device during the delay period; calculating an over-dwelling time based on the voltage of the switching device; waiting for the over-dwelling time; and initiating a soft shut-off after the over-dwelling time based on the voltage of the switching device to shut off the current.

[0007] In some aspects, the technology described herein relates to an ignition system comprising: a coil coupled to a battery on a first side; and an igniter circuit comprising: a switching device coupled to a second side of the coil; a current controller configured to control a current state of the switching device; and an over-dwelling circuit configured to: delay an input signal coupled to a control terminal of the switching device so that the current state of the switching device remains in an off state for a delay period before being configured to be in an on state; sense a voltage of the switching device during the delay period; and trigger the current controller to initiate a soft shutdown of the current state after an over-dwelling time, the over-dwelling time being based on the voltage of the switching device during the delay period.

[0008] The foregoing illustrative summary, as well as other exemplary objects and / or advantages of the present disclosure, and implementations are further explained in the following detailed description and its accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 Included are graphs illustrating power consumed by a switching device in an ignition system for a battery in a high voltage state and a low voltage state according to a possible implementation of the present disclosure.

[0010] Figure 2 is a schematic block diagram of an ignition system according to a possible implementation of the present disclosure.

[0011] Figure 3 A method for shutting off current in an ignition system according to a first possible implementation of the present disclosure is provided.

[0012] Figure 4 Included is configured to perform Figure 3 Graph of possible signals in an ignition system of the method.

[0013] Figure 5 is a schematic block diagram of an ignition system according to a first possible implementation of the present disclosure.

[0014] Figure 6 A method for shutting off current in an ignition system according to a second possible implementation of the present disclosure is provided.

[0015] Figure 7 Included is configured to perform Figure 6 Graph of possible signals in an ignition system of the method.

[0016] Figure 8 is a schematic block diagram of an ignition system according to a second possible implementation of the present disclosure.

[0017] The components in the drawings are not necessarily drawn to scale relative to each other. Like reference numerals indicate corresponding parts throughout the several views of the drawings. DETAILED DESCRIPTION

[0018] The igniter circuit of the automotive system can monitor the charging cycle of the induction coil so that it does not exceed a maximum limit (i.e., over-dwell time) that may cause overheating and / or damage to the ignition system. For example, if the switching device is controlled by the input signal to conduct current at the end of the over-dwell period, the igniter circuit can be configured to initiate a soft shutdown to reduce the current.

[0019] A soft shutdown (i.e., SSD) may include controlling a switch device in series with the battery and the coil to gradually increase its resistance from a short circuit state (i.e., an on state) to an open circuit state (i.e., an off state) during the SSD period to reduce the current in the induction coil. The gradual reduction of the coil current may limit the voltage across the induction coil caused by the back electromotive force (EMF), and limiting the voltage may prevent undesired sparks in the ignition system. A technical problem with this fixed over-dwelling time approach is that the battery voltage may vary over a wide range, so that an over-dwelling period suitable for a lower battery voltage may be too long for a higher battery voltage, and vice versa.

[0020] Figure 1 Included are graphs showing the power consumed by switching devices in the ignition system, such as insulated gate bipolar transistors (IGBTs). These graphs show the differences that exist between battery states.

[0021] Figure 1 The first graph 110 shows an input (IN) signal of a switch device controlling an ignition system. A first level (e.g., a low level) of the input signal may correspond to a current state in which the switch device is disconnected (i.e., not conducting), and a second level (e.g., a high level) of the input signal may correspond to a current state in which the switch device is connected (i.e., conducting). As shown, at the end of the over-dwelling time (i.e., the over-dwelling period 111), the input signal is at a high level. Therefore, the current controller may intervene to discharge the coil.

[0022] The coil is connected in series with the switching device so that the collector current of the switching device corresponds to the current in the coil. Specifically, the coil can be coupled between the battery and the terminals of the switching device. For example, a first side (i.e., a first terminal) of the coil can be coupled to the battery, and a second side (i.e., a second terminal) of the coil can be coupled to the collector terminal of the IGBT. The battery can have a battery voltage that can charge (i.e., increase) the coil current when the IGBT is turned on, and the coil current can increase until it reaches a current limit (ICL), which corresponds to the conductivity of the switching device.

[0023] Figure 1 A second graph 120 showing the current conducted by the switching device is included. As shown, at the first time 101 when the input signal configures the switching device to conduct, the collector current (i.e., the current in the coil) begins to increase as the coil is charged by the battery. As shown, the rate at which the collector current (i.e., the coil current) increases depends on the voltage state of the battery. The battery voltage corresponding to the high voltage state is higher than the battery voltage corresponding to the low voltage state. In the high voltage state 121, the current increases to its maximum value (i.e., the current limit (ICL)) faster than in the low voltage state 122.

[0024] If the input signal (IN) is still high at the end of the over-dwell time (i.e., the over-dwell period 111), the soft shutdown can reduce the current. Figure 1 As shown, at the second time 102, the collector current (i.e., the current in the coil) decreases from its maximum value according to the soft-off curve. In implementation, the current controller triggered for soft-off can, for example, linearly reduce the current limit of the switching device within the soft-off period 103 until the collector current is approximately zero.

[0025] Figure 1 A third graph 130 is included corresponding to the power consumed in a switching device (e.g., an IGBT) in a high voltage state 131 (i.e., a relatively high battery voltage) and in a low voltage state 132 (i.e., a relatively low battery voltage). The power consumed by the switching device in the high voltage state is higher than the power consumed by the switching device in the low voltage state because the current through the switching device reaches its current limit (ICL) faster in the high voltage state than in the low voltage state. Therefore, the high voltage condition 131 may require a shorter over-dwelling time (i.e., over-dwelling period 111) to prevent overheating due to the higher power consumption.

[0026] Using a fixed (shorter) over-dwell time to trigger the SSD in both the high and low voltage states may be problematic because it may be too short for the low voltage state. In the low voltage state, the current through the switching device takes longer to reach its limit. Therefore, the soft shutdown may be triggered prematurely. Therefore, it may be desirable to control the over-dwell time (i.e., the over-dwell period) based on the voltage of the battery (i.e., the battery voltage). Specifically, a relatively high battery voltage may correspond to a shorter over-dwell period than a relatively low battery voltage.

[0027] Controlling the over-dwell time based on the battery voltage can be problematic when the size and complexity of the igniter circuit are constrained. The battery voltage may be in a higher voltage domain than the voltage domain used by the igniter circuit. Therefore, coupling the battery to the igniter circuit may require additional circuitry necessary to receive the higher voltage domain and convert it to the voltage domain used by the igniter circuit. In addition, the timing circuitry necessary to handle typical over-dwell periods (e.g., milliseconds) may require a device (or devices) that is too large for the size-constrained igniter circuit. For example, the timing circuitry may require capacitors in the order of microfarads (e.g., C=0.1 μF), which is too large for some implementations.

[0028] The present disclosure describes an igniter circuit to solve at least the above technical problems. The igniter circuit has an over-dwelling time based on the voltage control of the battery without directly connecting to the battery (i.e., without requiring terminals for the battery). The disclosed igniter circuit includes an adjustable over-dwelling time feature, and its circuit size is small and the complexity is low, so that the igniter circuit can be manufactured (e.g., as an integrated circuit) smaller and more cost-effective than other over-dwelling time methods.

[0029] Figure 2 2 is a schematic block diagram of an ignition system 200 according to a possible implementation of the present disclosure. As shown, a coil 201 is coupled (eg, directly connected) between terminals of a battery and an igniter circuit 210.

[0030] The igniter circuit 210 may be implemented as an integrated circuit having at least an input terminal (IN), a collector terminal (COLLECTOR), and a ground terminal (GND). The igniter circuit 210 may not require a battery terminal or other circuit for directly monitoring the battery voltage (VB) of the battery 220. The igniter circuit 210 may include a switching device 211 (e.g., an IGBT) coupled between the coil 201 and the ground 202. For example, the switching device may be an IGBT coupled to the coil 201 at the collector terminal, coupled to the current sensing resistor 212 at the emitter terminal, and coupled to the input via a gate resistor 215 at the gate terminal. The input signal 231 of the igniter circuit 210 may come from an engine control unit 230 (ECU). The ignition system 200 may also include an ignition coil 240 magnetically coupled to the coil 201 in the transformer, which may increase the voltage of the coil 201 to a voltage sufficient to generate a spark at the gap 250.

[0031] The igniter circuit 210 may include a current controller 213 configured to control the current state of the switching device 211 during soft shutdown. For example, when triggered, the current controller 213 may be configured to output an SSD signal to gradually reduce the current limit of the switching device 211 so that it gradually changes from an on state to an off state. In other words, the current controller 213 may be configured to output a voltage that decreases linearly at an SSD rate during an SSD period. The SSD rate and SSD period (i.e., an SSD curve) may be preset to prevent a voltage sufficient to generate a spark from being induced in the coil 201 during shutdown.

[0032] The igniter circuit 210 also includes an over-dwelling circuit 214. The over-dwelling circuit 214 can be configured to time how long the input signal (IN) remains at an on level (e.g., a high level). If the input signal is still in the on state after the over-dwelling time (i.e., the over-dwelling period) has expired, the over-dwelling circuit 214 can trigger the current controller 213 to start soft shutdown.

[0033] The igniter circuit 210 can adjust the over-dwell time (i.e., over-dwell period 111) based on sensing (i.e., measuring) the signal of the switching device 211 instead of directly sensing the voltage of the battery 220 itself. In a first specific implementation, the sensed signal is the current of the switching device 211, and in a second specific implementation, the sensed signal is the voltage of the switching device 211.

[0034] Figure 3The method 300 is a method for shutting off current in an ignition system according to a first possible embodiment of the present disclosure. The method 300 includes receiving 310 an input signal (i.e., at an igniter circuit) to configure a switching device (e.g., an IGBT) to enter an on state. The switching device is coupled in series with a coil (e.g., a primary coil) such that in the on state, the current in the switching device can be equal to the current in the coil.

[0035] The method 300 also includes starting 320 a timer. For example, the timer can be started while the input signal transitions to a level (e.g., a high level) for turning on the switching device. The method 300 also includes sensing 330 a current of the switching device after the switching device is configured to be in the on state. For example, when the IGBT is turned on (e.g., in the on state), the collector current of the IGBT in series with the coil can be sensed as the current in the coil. The method 300 also includes measuring 340 a rise time corresponding to the time required for the current to meet the standard. For example, starting from the initial time (T0) when the IGBT is turned on, the collector current can be sensed and compared to a threshold current (i.e., ICT). Then, when the collector current becomes greater than or equal to the threshold, the rise time can be determined based on the time (T1) of the (running) timer.

[0036] The method 300 also includes calculating 350 a soft shutdown delay (i.e., SSD delay) based on the rise time (e.g., T1-T0). The SSD delay can be the amount of time to wait before triggering (if necessary) a soft shutdown. Therefore, the method 300 also includes waiting 360 (e.g., based on a timer) for the SSD delay.

[0037] After waiting for the SSD delay, the method 300 may include determining 365 whether a soft shut-off is required. For example, if the input signal (IN) is at an on level (e.g., a high level), a soft shut-off of the current may be required. In this case (i.e., yes), the method 300 includes initiating 370 a soft shut-off to shut off the current in the ignition system (i.e., the coil and the switching device). Otherwise, the method 300 may reset 375 until another input signal to turn on the switching device occurs, at which time the method 300 may be repeated.

[0038] Figure 4 Included is configured to perform Figure 3Graphs of possible signals in an ignition system of a method of . A first graph 410 shows an input signal (e.g., at the gate of a switching device) that is turned on (i.e., high level) at an initial time (T0). At this level, the input signal can configure the switching device to be in an on state. A second graph 420 shows the current (i.e., collector current) of the switching device. As shown, when the on state begins at the initial time (T0), the current begins to increase. At the first time (T1), the current reaches a threshold level (ICT). Rise time 411 can be determined as the difference between the first time and the initial time (i.e., rise time = T1-T0). A soft shutdown delay (SSD delay 412) can be calculated based on rise time 411. For example, SSD delay 412 can be rise time 411 multiplied by a fixed value (i.e., SSD delay = (rise time) · (A)). Therefore, a relatively short rise time can produce a shorter SSD delay (i.e., short rise time < long rise time) compared to a longer SSD delay of a relatively long rise time. Shorter SSD latency may reduce the power consumed during the over-dwell period 413 .

[0039] like Figure 4 As shown, the over-dwell period 413 may be the sum of the rise time 411 and the SSD delay 412. At a second time (T2) after the SSD delay 412, a soft turn-off 415 occurs to reduce the current in the switching device (i.e., the current in the coil). The soft turn-off 415 may be triggered by an input signal (IN) that is in an on state (i.e., a high level) at the end of the SSD delay 412 (i.e., at the end of the over-dwell period 413).

[0040] Figure 5 is a schematic block diagram of an ignition system according to a first possible implementation of the present disclosure. The ignition system 500 includes a coil 560 coupled to a battery voltage 561 (VB) of a battery on a first side and coupled to a switching device 550 (e.g., an IGBT) of an igniter circuit 530 on a second side. The switching device 550 can receive an input signal at a gate terminal that configures the switching device to be in an on state so that it conducts a current (I) between a collector terminal and an emitter terminal. The current (I) can be sensed based on the battery voltage 561 to adjust the over-dwell period, rather than directly sensing the battery voltage.

[0041] The igniter circuit 530 includes an over-dwelling circuit 531, which is configured to measure the rise time of the current (I) from an initial time (T0) when the current starts to a first time (T1) when the current meets the standard. The over-dwelling circuit 531 is further configured to wait for the soft shutdown delay to expire at a second time (T2) before triggering a soft shutdown of the current. For these time measurements, the over-dwelling circuit 531 includes (i) a first timer implemented using the clock generator 501 and the first counter 511 and (ii) a second timer implemented using the clock generator 501 and the second counter 521. The first counter 511 and the second counter 521 can be initialized (e.g., reset, started) by the enable signal 533 based on the input signal 532. For example, at the initial time (T0), the first counter 511 and the second counter 521 can be set to 0.

[0042] The over-dwelling circuit 531 may further include a current detector 509. In a possible implementation, the current detector 509 may be configured to compare the current (I) with a threshold value (ICT) and output a signal to a first counter 511 when the current is greater than or equal to the threshold value (ICT). The signal from the current detector 509 may trigger the first counter 511 to output a rise time count 510 corresponding to the number of cycles counted when the current is greater than or equal to the threshold value.

[0043] The over-dwell circuit 531 may further include a multiplier 513. The multiplier 513 may be configured to multiply the rise time count 510 by a fixed value (A) to generate a delay count 520 corresponding to the SSD delay. In other words, the delay count 520 may be based on the rise time count. The fixed value (A) may be based on a target over-dwell period (e.g., 10 milliseconds) of the switching device 550. The delay count 520 may be coupled to a second counter 521, and the second counter 521 may be configured to output an SSD trigger signal 522 when the count of the second counter 521 reaches the delay count 520.

[0044] The igniter circuit 530 also includes a current controller 540 coupled to the gate of the switching device to control its current state. The current controller 540 may receive an SSD trigger signal 522 from the second counter 521 at a second time (T2) after the SSD delay. The SSD trigger signal 522 may trigger the current controller 540 to initiate a soft turn-off to reduce the current (I) of the switching device (i.e., the coil).

[0045] Figure 6is a method for shutting off current in an ignition system according to a second possible embodiment of the present disclosure. The method 600 includes receiving 610 an input signal to turn on a switch device of an igniter circuit and starting 620 (e.g., simultaneously starting) a timer. The method 600 also includes delaying 630 the input signal so that the switch device remains disconnected. In other words, the input signal that configures the switch device to be in the on state is delayed by a delay period so that the switch device remains in the off state during the delay period. In other words, the input signal is delayed to keep the switch device in the off state during the delay period before configuring the switch device to be in the on state. When the switch device is in the off state, no current flows, and the voltage at the collector terminal of the switch device may correspond to (e.g., may be equal to) the voltage (VB) of the battery. Therefore, the method 600 includes sensing 640 the collector voltage of the switch device and adjusting the over-dwelling period based on the voltage of the switch device. Specifically, the method 600 includes calculating 650 the over-dwelling period based on the collector voltage. The method 600 also includes waiting 660 for the over-dwelling time before determining 665 whether a soft shutdown is required. For example, if the input signal (IN) is at an on level (e.g., high), a soft shutoff of the current may be required. In this case (i.e., yes), the method 600 includes initiating 670 a soft shutoff to shut off the current in the ignition system (i.e., coil and switch device). Otherwise, the method 600 may reset 675 until another input signal to turn on the switch device occurs, at which time the method 600 may be repeated.

[0046] Figure 7 Included is configured to perform Figure 6Graphs of possible signals in an ignition system of a method of the present invention. The first graph 710 shows an input signal (e.g., at the gate terminal of a switching device) that is turned on (i.e., high level) at an initial time (T0). The second graph 720 shows an input signal that is delayed by a delay period 725. The delay period 725 may start at the initial time (T0) and end at the first time (T1). The third graph 730 shows the current (i.e., collector current) of the switching device. As shown, since the switching device is in an off state, the current remains zero during the delay period 725. The fourth graph 740 shows the collector voltage of the switching device. As shown, during the delay period, the collector voltage may be equal to the battery voltage (VB). The battery voltage (VB) may be measured by sensing the collector voltage of the switching device within the delay period 725. This sensing may be enabled by a voltage monitor enable signal (VM_ENABLE), as shown in the fifth graph 750. After sensing the battery voltage, the dwell time 713 may be calculated. For example, a high collector voltage sensed during the delay period may produce a shorter over-dwell time than a longer over-dwell time for a relatively low collector voltage measured during the delay period. A shorter over-dwell time may reduce the power consumed by the higher battery voltage. After waiting for the over-dwell time 713, a soft shutdown may be triggered by an input signal (IN) that is in an on state (i.e., high level) at the end of the over-dwell time 713 (i.e., T2).

[0047] Figure 8 8 is a schematic block diagram of an ignition system according to a second possible specific implementation of the present disclosure. The ignition system 800 includes a coil 860 coupled to a battery voltage 861 (VB) of a battery on a first side and coupled to a switching device 850 (e.g., an IGBT) of an igniter circuit 830 on a second side. The switching device 850 can receive an input signal at a gate terminal that configures the switching device to be in an off state or in an on state. In the on state, the switching device 850 conducts current (I) between a collector terminal and an emitter terminal, and in the off state, the voltage at the collector terminal of the switching device (i.e., the collector voltage) can be equal to the battery voltage 861.

[0048] The igniter circuit 830 includes an over-dwell circuit configured to sense (i.e., measure) the collector voltage when the switching device 850 is in an off state. The over-dwell circuit of the igniter circuit 830 includes a delayer 831 and an inverter 832 to generate a delayed version and an inverted version 834 of an input signal 833. The input signal 833 and the delayed, inverted input signal 834 are input to a logic gate (e.g., an AND gate 835) that is configured to compare these signals to generate a voltage monitor enable signal 836 (i.e., VM_ENABLE). In other words, the igniter circuit 830 includes a logic gate that is configured to compare the delayed input signal with the input signal to create (i.e., generate) an enable signal, thereby configuring the over-dwell circuit to sense the voltage of the switching device. The delayed version of the input signal may also be coupled to a control terminal (e.g., a gate terminal) of the switching device 850 so that the switching device 850 remains in an off state for a delay period corresponding to the delay 831. Therefore, during the delay period, the switching device 850 is in an open state and the voltage monitor enable signal is in an active state (eg, high level).

[0049] The over-dwell circuit also includes a voltage divider 810 configured to reduce a battery voltage 861 measured at the collector terminal when the switching device 850 is in an off state. The voltage divider 810 is coupled to a voltage monitor 811 configured to generate a dwell time voltage 812 corresponding to the battery voltage 861 when the voltage monitor enable signal 836 is in an active state (e.g., a high level). The over-dwell circuit also includes an analog-to-digital converter (i.e., a digital converter 813) configured to convert the dwell time voltage 812 into a dwell time count 820. For example, the voltage of the switching device can be digitized by an analog-to-digital converter (A / D) to obtain (e.g., generate, create) a dwell time count. The dwell time count 820 corresponds to a voltage of the switching device 850 corresponding to a battery voltage (VB) when the switching device 850 is in an off state. For example, a higher battery voltage can produce a smaller dwell time count than a lower battery voltage.

[0050] The over-dwelling circuit is configured to wait for the over-dwelling time first, and then send an SSD trigger signal 822 to the current controller 840 to perform a soft shut-off of the current (I). The waiting can be performed using a timer. Therefore, the over-dwelling circuit of the igniter circuit 830 can include a timer implemented using a clock generator 801 and a counter 821, the clock generator is used to generate a periodic clock signal (CLK), and the counter is configured to count the period of the periodic clock signal. The counter 821 can be triggered to start counting based on the input signal 833 and can count until it reaches the dwell time count 820. When (e.g., in response to) reaching the dwell time count 820, the counter 821 can output the SSD trigger signal 822.

[0051] Although certain features of the described implementations have been described as described herein, many modifications, alternatives, variations, and equivalents will now occur to those skilled in the art. Therefore, it should be understood that the appended claims are intended to cover all such modifications and variations that fall within the scope of the implementations. It should be understood that these modifications and variations are presented only by way of example and not limitation, and that various changes in form and detail may be made. In addition to mutually exclusive combinations, any portion of the apparatus and / or method described herein may be combined in any combination. The implementations described herein may include various combinations and / or sub-combinations of the functions, components, and / or features of the different implementations described.

[0052] It will be understood that in the foregoing description, when an element is referred to as being on another element, connected to another element, electrically connected to another element, coupled to another element, or electrically coupled to another element, the element may be directly on another element, connected or coupled to another element, or one or more intermediate elements may be present. On the contrary, when an element is referred to as being directly on another element, directly connected to another element, or directly coupled to another element, there is no intermediate element. Although the term directly on, directly connected to, or directly coupled to may not be used throughout the specific embodiments, the element shown as being directly on an element, directly connected, or directly coupled can be mentioned in this manner. The claims of the present application, if present, may be revised to narrate the example relationships described in the specification or shown in the accompanying drawings.

[0053] As used in this specification, singular forms may include plural forms unless the context clearly indicates a particular case. Spatially relative terms (e.g., above, above, above, below, below, below, below, etc.) are intended to cover different orientations of the device in use or operation, in addition to the orientations shown in the drawings. In some implementations, the relative terms above and below may include vertically above and vertically below, respectively. In some implementations, the term adjacent can include lateral adjacent or horizontal adjacent.

[0054] Some implementations may be implemented using various semiconductor processing and / or packaging technologies. Some implementations may be implemented using various types of semiconductor processing technologies associated with semiconductor substrates, including but not limited to, for example, silicon (Si), gallium arsenide (GaAs), gallium nitride (GaN), silicon carbide (SiC), etc.

Claims

1. A method for shutting off current in an ignition system, the method comprising: receiving an input signal to configure a switching device to be in an on state, the switching device being coupled in series with the coil; Start the timer; After the switch device is configured to be in an on state, sensing the current in the coil; Based on the timer, measuring a rise time corresponding to a time when the current meets a standard; calculating a soft turn-off delay based on the rise time; as well as A soft shut-down is initiated after the soft shut-down delay to reduce current in the coil.

2. The method of claim 1 , wherein the timer is a clock generator, and measuring the rise time comprises: Counting the cycles of the clock generator; comparing the current to a threshold value; as well as A rise time count corresponding to the rise time is output, the rise time count being the number of cycles counted when the current is greater than or equal to the threshold value.

3. The method of claim 2, wherein calculating the soft-off delay based on the time that the current meets the criterion comprises: The rise time count is multiplied by a fixed value to generate a delay count.

4. The method according to claim 3, further comprising: The soft shut-off of the current is triggered in response to counting the delay count.

5. The method of claim 1 , wherein the sum of the rise time and the soft turn-off delay corresponds to an overdwell period corresponding to a battery voltage coupled to the coil, such that a relatively higher battery voltage corresponds to a shorter overdwell period than a relatively lower battery voltage.

6. An ignition system comprising: a coil coupled to a battery on a first side; and An igniter circuit, the igniter circuit comprising: a switching device coupled to a second side of the coil; a current controller configured to control a current state of the switching device; and An over-dwell circuit, wherein the over-dwell circuit is configured to: measuring a rise time of a current conducted by the switching device after being configured in an on-state; and The current controller is triggered to initiate a soft shutdown of the current after a soft shutdown delay, the soft shutdown delay being based on the rise time of the current.

7. The ignition system of claim 6, wherein the overdwell circuit comprises: Clock generator; a first counter configured to count cycles of the clock generator; and A current detector is configured to output a signal to the first counter in response to determining that the current conducted by the switching device is greater than or equal to a threshold, the signal triggering the first counter to output a rise time count of the cycle of the clock generator.

8. The ignition system of claim 7, wherein the overdwell circuit further comprises: A multiplier is configured to multiply the rise time count by a fixed value to generate a delay count, the fixed value corresponding to an over-dwell period.

9. The ignition system of claim 8, further comprising: A second counter is configured to receive the delay count from the multiplier and output a soft turn-off trigger signal to the current controller after counting the delay count.

10. The ignition system of claim 6, wherein the sum of the rise time and the soft-off delay corresponds to an overdwell period corresponding to a battery voltage of the battery such that a relatively higher battery voltage corresponds to a shorter overdwell period than a relatively lower battery voltage.

11. A method for shutting off current in an ignition system, the method comprising: receiving an input signal to configure a switching device to be in an on state, the switching device being coupled in series with the coil; delaying the input signal by a delay period to keep the switching device in an OFF state for the delay period before configuring the switching device to be in an ON state; sensing a voltage of the switching device during the delay period; calculating a dwell time based on the voltage of the switching device; as well as A soft shutdown is initiated based on the voltage of the switching device after the over-dwelling time to shut off the current.

12. The method according to claim 11, wherein: The voltage at which the switching device is subjected is the collector voltage of the collector terminal of the switching device; The collector terminal is connected to a first side of the coil; and A battery is connected to the second side of the coil such that when the switching device is in the open state, the voltage at the collector terminal corresponds to a battery voltage of the battery.

13. The method of claim 12, wherein sensing the voltage of the switching device when the switching device is in the off state comprises: generating an enable signal corresponding to the delay period; as well as A voltage monitoring circuit is enabled based on the enable signal, and the voltage monitoring circuit is configured to generate a dwell time voltage based on the collector voltage. 14 . The method of claim 13 , wherein calculating the excess dwell time based on the voltage of the switching device comprises digitizing the dwell time voltage to obtain a dwell time count.

15. The method according to claim 14, further comprising: The counter is configured to output a soft shutdown trigger signal after counting the dwell time count, the dwell time count corresponding to the battery voltage, such that a relatively higher battery voltage corresponds to a shorter dwell time count than a relatively lower battery voltage.

16. An ignition system comprising: a coil coupled to a battery on a first side; and An igniter circuit, the igniter circuit comprising: a switching device coupled to a second side of the coil; a current controller configured to control a current state of the switching device; and An over-dwell circuit, wherein the over-dwell circuit is configured to: delaying an input signal coupled to a control terminal of the switching device such that the current state of the switching device remains in an OFF state for a delay period before being configured in an ON state; sensing a voltage of the switching device during the delay period; and The current controller is triggered to initiate a soft shutdown of the current state after an over-dwelling time based on a voltage of the switching device during the delay period.

17. The ignition system of claim 16, wherein the overdwell circuit comprises: a delayer configured to output a delayed input signal; and A logic gate is configured to compare the delayed input signal with the input signal to create an enable signal to configure the overdwell circuit to sense the voltage of the switching device.

18. The ignition system of claim 16, wherein: The switching device is an insulated gate bipolar transistor coupled at a collector terminal to the second side of the coil, and When the insulated gate bipolar transistor is in an off state, a collector voltage of the insulated gate bipolar transistor corresponds to a battery voltage of the battery.

19. The ignition system of claim 18, wherein the overdwell circuit further comprises: a voltage divider coupled to the collector terminal and configured to generate a dwell time voltage corresponding to the battery voltage; and A digitizer is configured to output a dwell time count based on the dwell time voltage.

20. The ignition system of claim 19, wherein the overdwell circuit comprises: A counter configured to: Counting cycles of a clock generator; receiving the dwell time count from the digitizer; and After the dwell time count is reached, a soft shutdown trigger signal is output to the current controller, where the soft shutdown trigger signal triggers the current controller to start a soft shutdown of the current state.

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