JP2016092534A - Ignitor, vehicle, and control method for ignition coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignitor which is improved in durability to surge or a noise.SOLUTION: A determination comparator 302 is configured to compare a voltage Vof an input line 301 with a reference voltage V, and to generate a determination signal S. A drive stage 300B is configured to control ON/OFF of a switch element 202 in accordance with the determination signal S. A noise detection circuit 340 is configured to, when detecting a noise causing a voltage Vof the control terminal of the switch element 202 to change in a negative direction on the basis of a first signal S11 having a voltage level corresponding to the voltage Vof the input line 301 or corresponding to the determination signal S, asset a noise detection signal S21. A gate voltage correction circuit 342 is configured to, when the noise detection signal S21 is asserted, supply currents Ito the control terminal of the switch element 202.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an igniter that controls an ignition coil connected to an ignition plug of an engine.

  FIG. 1 is a perspective view of an engine room 101 of a gasoline engine vehicle (hereinafter also simply referred to as a vehicle) 100. The engine room 101 accommodates an engine 110, an intake manifold 112, an air cleaner 113, a radiator 114, a battery 102, and the like. FIG. 1 shows a four-cylinder engine.

  The engine 110 is provided with a plug hole (not shown) for each cylinder, and a spark plug (not shown) is inserted into the plug hole. Each cylinder of the engine 110 is supplied with a mixed gas of air that passes through the air cleaner 113 and the intake manifold 112 and fuel from a fuel tank (not shown). The engine is started and rotated by igniting (sparking) the spark plug at an appropriate timing.

FIG. 2 is a block diagram of a part of the electric system of the vehicle 100r. The electric system of the vehicle 100r includes a battery 102, an ignition coil 104, a spark plug 106, an ECU 108, and an igniter 200r. ECU 108 periodically generates an ignition signal IGT instructing the ignition timing of ignition plug 106 in synchronization with the rotation of engine 110. The secondary coil L2 of the ignition coil 104 is connected to the spark plug 106. The igniter 200r controls the current of the primary coil L1 of the ignition coil 104 in accordance with the ignition signal IGT, thereby generating a high voltage (secondary voltage V _S ) as high as several tens of kV in the secondary coil L2. 106 is discharged, and the air-fuel mixture in the engine 110 is exploded.

The igniter 200r includes a switch element 202 and a switch control device 300r. Switch element 202 is, for example, an IGBT (Insulated Gate Bipolar Transistor), the collector of which is connected to primary coil L1, and the emitter of which is grounded. The switch control device 300r controls the voltage of the control terminal (gate) of the switch element 202 according to the ignition signal IGT, and controls the on / off of the switch element 202. Specifically, the switch control device 300r turns on the switch element 202 while the ignition signal IGT is at a high level. When switch element 202 is turned on, battery voltage _VBAT is applied across both ends of primary coil L1, and the current flowing through primary coil L1 increases with time. When the ignition signal IGT is changed to a low level, the switch control unit 300r is turning off the switch element 202 instantaneously interrupts the current _{I L1} of the primary coil L1. At this time, a primary voltage V _L1 (= L · dI _L1 / dt) of several hundred volts proportional to the time differentiation of the current I _L1 is generated in the primary coil L1. At this time, a secondary voltage V _{S of} several tens of kV obtained by multiplying the primary voltage V _L1 by the winding ratio is generated in the secondary coil L2.

The switch control device 300r includes a preceding determination stage 300A and a subsequent drive stage 300B. The determination stage 300A receives the ignition signal IGT from the ECU 108, and determines its level (high / low). Here, the igniter 200 is used in an engine room and exposed to various surge noises and high frequency noises. In order to prevent malfunction of the igniter 200 due to high frequency noise, the determination stage 300A is provided with a high frequency filter 303 that removes high frequency noise superimposed on the ignition signal IGT. The determination comparator 302 compares the voltage level V _FIL of the ignition signal IGT that has passed through the high frequency filter 303 with a predetermined reference voltage (threshold value) V _REF to generate a high / low binary determination signal _SDET .

Driving stage 300B in response to the determination signal _{S DET,} it switches on the switching element 202, and off. The delay circuit 304 gives a predetermined delay to the determination signal _SDET . This delay amount is set so that the time difference (delay) between the transition of the ignition signal IGT and the discharge time of the spark plug becomes a predetermined value. The pre-driver 306 and the gate driver 308 control the gate voltage of the switch element 202 according to the output of the delay circuit 304.

JP 2011-185165 A JP 2014-051904 A

  Here, the igniter 200r is used in the engine room and is exposed to various surges and noises (hereinafter also simply referred to as noise). Surge or surge noise and ESD noise incident on the igniter 200r in the engine room have a steep rise (<1 ns) and a very high peak voltage (peak current) of several tens of volts. In order to test the noise resistance of the igniter 200, various test items are defined (see Patent Document 1). For example, tests using BCI (Bulk Current Injection) and GTEM (Giga-herz Transverse Electro Magnetic) cells are known.

FIG. 3 is a circuit diagram illustrating a configuration example of the output stage of the switch control device 300r. The gate driver 308 has a push-pull type including a high side transistor MH and a low side transistor ML. When the determination signal _SDET is at a high level, the pre-driver 306 turns on the high-side transistor MH and turns off the low-side transistor ML, and generates a gate voltage V _G higher than the threshold voltage of the IGBT at the gate of the switch element 202. The switch element 202 is turned on. Predriver 306 Conversely, when the determination signal S _DET is low, the high-side transistor MH is turned off, the low-side transistor ML, to the gate of the switching element 202, to generate a gate voltage V _G in the vicinity of the ground voltage, The switch element 202 is turned off.

The igniter 200 r, overcurrent protection for clamping the collector current (that is the coil current flowing through the primary coil L1) _{I C} of the switch element 202 at a predetermined current limit _{I CL} (OCP) circuit 330 is provided. OCP circuit 330, the coil current _{I C} is to adjust the gate voltage _{V G} of the switching element 202 so as not to exceed the current limit _{I CL.} Current sense resistor _{R CS} is inserted in the path of the collector current _{I C.} The current sense resistor _RCS may be a chip component, a resistance component of a bonding wire, or a resistor integrated in an IC of the switch control device.

Overcurrent Protection (OCP) This comparator 332, the detection voltage _{V CS} is the voltage drop of the current sense resistor _{R CS,} as compared to the threshold voltage _{V CL} which corresponds to the current limit when it comes _to V _{CS> V CL} transistor 334 Is turned on, the charge of the gate capacitance of the switch element 202 is discharged, and the gate voltage V _G is lowered.

4A and 4B are operation waveform diagrams of the igniter 200r. FIG. 4A shows an operation when no surge (or surge noise) is input. When the ignition signal IGT transits to a high level at time t0, the switch element 202 is turned on. Thus the coil current (collector current) I _C increases with time. The OCP circuit 330, the collector current _{I C} is clamped so as not to exceed a predetermined threshold value (current _{limit) I CL.}

Thereafter, when the ignition signal IGT transits to a low level at time t1, the switch element 202 is turned off. As a result, a large secondary voltage V _S is generated in the secondary coil L2, and the spark plug 106 sparks.

FIG. 4B shows the operation when a surge is input. At time t2, a negative surge S10 is input to the input line 301. Thereby, the determination signal S2 transits to a low level for a moment. When the determination signal S2 transitions to the low level, the low-side transistor ML of the gate driver 308 is turned on, so that the gate voltage V _G of the switch element 202 decreases. The collector current _{I C} of the IGBT to operate in the active _{region, (V G -V} ^TH) is proportional to ^2, _{V G} is the collector current _{I C} is also reduced when lowered. This causes a problem that a large secondary voltage V _S is generated in the secondary coil L2, and the spark plug 106 is erroneously ignited.

  The present invention has been made in view of such a problem, and one of the exemplary purposes of an aspect thereof is to provide an igniter with improved resistance to surge and noise.

  One embodiment of the present invention relates to an igniter. The igniter includes a switch element connected to the primary coil of the ignition coil, and a switch control device that controls the switch element in accordance with an ignition signal from an ECU (Engine Control Unit). The switch control device includes an input line to which an ignition signal is input, a determination comparator that compares a voltage of the input line with a reference voltage and generates a determination signal, and a drive that controls on / off of the switch element in accordance with the determination signal When noise that changes the voltage of the control terminal of the switch element in the negative direction is detected based on the stage and the first signal having a voltage level according to the voltage of the input line or according to the determination signal, the noise detection signal is asserted. And a gate voltage correction circuit for supplying a current to the control terminal of the switch element when the noise detection signal is asserted.

When negative direction noise is input and the determination signal transitions to an off level corresponding to the off state of the switch element, the drive stage attempts to lower the gate voltage. At this time, by supplying a current to the control terminal of the switch element by the gate voltage correction circuit, it is possible to cancel the decrease in the gate voltage due to the drive stage. Thereby, the fluctuation | variation of the gate voltage of a switch element and by extension, the fluctuation | variation of a coil current can be suppressed, and a false ignition can be prevented.
The “noise” includes a surge accompanied by a steep voltage change or current change, or a noise similar to this (referred to as surge noise).

  The impedance of the gate voltage correction circuit may be lower than the impedance of the gate driver provided in the final stage of the drive stage. As a result, when the judgment signal transitions to the off level due to noise, the operation of the gate voltage correction circuit maintaining the gate voltage at the original level is greater than the operation of the drive stage reducing the gate voltage. The coil current can be prevented from decreasing.

The gate voltage correction circuit may include a first transistor provided between a power supply line to which a stabilized power supply voltage is supplied and a control terminal of the switch element, and receiving a noise detection signal at the control terminal.
According to this configuration, when the noise detection signal is asserted, the current can be supplied to the control terminal of the switch element by turning on the first transistor.

The first transistor may be a P-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor), its source connected to the power supply line, and its drain connected to the control terminal of the switch element. The gate voltage correction circuit may further include a first resistor provided between the gate and source of the first transistor.
By asserting the low level of the noise detection signal and negating the high impedance state, the first transistor can be appropriately turned on and off, and the first transistor can be normally off.

The noise detection circuit may include a low-pass filter that has a cutoff frequency lower than a frequency of surge or surge noise and receives a second signal corresponding to the first signal. The noise detection circuit may generate a noise detection signal according to a potential difference between the third signal that has passed through the low-pass filter and the second signal that has not passed through the low-pass filter.
The second signal varies depending on the surge or surge noise, whereas the third signal is constant regardless of the surge or surge noise. Therefore, surge or surge noise can be detected based on the potential difference between the second signal and the third signal.

  The noise detection circuit is a MOSFET or a bipolar transistor, and further includes a second transistor in which the potential difference between the third signal and the second signal is applied between the gate source and the base emitter, and the voltage of the collector / drain of the second transistor Alternatively, a noise detection signal corresponding to the current flowing through the second transistor may be output.

The noise detection circuit may further include an inverter that inverts the determination signal and generates the second signal. The third signal may be input to the gate and base of the second transistor, and the second signal may be input to the source and emitter of the second transistor.
Thereby, it can be detected that the determination signal has transitioned to a low level due to surge or surge noise.

  The low pass filter may be an RC filter including a second resistor and a first capacitor provided in series between a line through which the second signal propagates and a ground line.

The drive stage includes a delay circuit that delays the determination signal, a gate driver that supplies a high-level voltage or a low-level voltage to the control terminal of the switch element, and a pre-driver that controls the driver according to the determination signal that has passed through the delay circuit. , May be included. The first signal may be a determination signal that has passed through a delay circuit.
By detecting noise as close as possible to the control terminal of the switch element, the gate voltage correction circuit can be appropriately controlled.

  The drive stage includes a delay circuit that delays the determination signal, a high-side transistor provided between the power supply line and the control terminal of the switch element, a low-side transistor provided between the control terminal of the switch element and the ground line, And a pre-driver that controls on / off of the high-side transistor and the low-side transistor in accordance with a determination signal that has passed through the delay circuit. The first signal may be a signal at a control terminal of the high side transistor or the low side transistor.

An overcurrent protection circuit for adjusting the voltage of the control terminal of the switch element may be further provided so that the coil current flowing through the switch element does not exceed a predetermined threshold value.
When an overcurrent protection circuit for controlling the gate voltage of the switch element is provided, the gate voltage of the switch element is highly sensitive to noise. By providing a gate voltage correction circuit in such a situation, fluctuations in the gate voltage due to noise can be suppressed.

  The overcurrent protection circuit compares the overcurrent protection transistor provided between the control terminal of the switch element and the ground line with the detection voltage corresponding to the coil current with a predetermined threshold voltage, and the detection voltage is And an overcurrent protection comparator that turns on the overcurrent protection transistor when the voltage is exceeded.

  The first signal may be a signal preceding the determination comparator. The noise detection circuit may include a noise detection comparator that compares the voltage of the line through which the first signal propagates with a negative threshold voltage and generates the noise detection signal indicating the comparison result.

The first signal may be a signal preceding the determination comparator. The noise detection circuit may include a filter that passes a high-frequency component of the voltage of the line through which the first signal propagates, and a noise detection comparator that compares the level of the output signal of the filter with a threshold value.
Surge or surge noise includes a higher frequency component than high frequency noise (periodic noise). Therefore, by extracting these frequency components, it is possible to detect the presence or absence of surge or surge noise.

Another aspect of the present invention also relates to an igniter. The igniter includes a switch element connected to the primary coil of the ignition coil, and a switch control device that controls the switch element in accordance with an ignition signal from an ECU (Engine Control Unit). The switch control device includes an input line to which an ignition signal is input, a determination comparator that compares a voltage of the input line with a reference voltage and generates a determination signal, and a drive that controls on / off of the switch element in accordance with the determination signal When noise is detected by changing the voltage of the stage and the control terminal of the switch element in the negative direction, a noise detection circuit that asserts a noise detection signal, a power supply line to which a stabilized power supply voltage is supplied, and a control terminal of the switch element And a first transistor that is turned on when the noise detection signal is asserted.
When negative direction noise is input and the determination signal transitions to an off level corresponding to the off state of the switch element, the drive stage attempts to lower the gate voltage. At this time, the voltage of the control terminal of the switch element can be pulled up to the high potential side by turning on the first transistor. Thereby, the fluctuation | variation of the gate voltage of a switch element and by extension, the fluctuation | variation of a coil current can be suppressed, and a false ignition can be prevented.

  The on-resistance of the first transistor may be lower than the impedance of the gate driver provided in the final stage of the driving stage.

  The noise detection circuit has a cut-off frequency lower than the frequency of surge or surge noise, and receives a second signal corresponding to the first signal having a voltage level corresponding to the determination signal, and passes through the low-pass filter The potential difference between the third signal and the second signal before passing through the low-pass filter may include a second transistor applied between the gate and source and between the base and emitter. The noise detection circuit may output a noise detection signal corresponding to the collector / source voltage of the second transistor or the current flowing through the second transistor.

The switch control device may be integrated on a single semiconductor substrate.
“Integrated integration” includes the case where all of the circuit components are formed on a semiconductor substrate and the case where the main components of the circuit are integrated. A resistor, a capacitor, or the like may be provided outside the semiconductor substrate.

  Another aspect of the present invention relates to a vehicle. The vehicle includes an ignition coil having a gasoline engine, an ignition plug, a primary coil, and a secondary coil connected to the ignition plug, an ECU that generates an ignition signal instructing ignition of the ignition plug, an ignition signal The above-described igniter that drives the ignition coil according to the above may be provided.

  It should be noted that any combination of the above-described constituent elements, and those in which constituent elements and expressions of the present invention are mutually replaced between methods, apparatuses, systems, and the like are also effective as an aspect of the present invention.

  According to an aspect of the present invention, the resistance of an igniter to surge and noise can be improved.

It is a perspective view of the engine room of a gasoline engine car. It is a block diagram of a part of electric system of vehicles. It is a circuit diagram which shows the structural example of the output stage of a switch control apparatus. 4A and 4B are operation waveform diagrams of the igniter. It is a circuit diagram of the igniter which concerns on embodiment. FIG. 6 is an operation waveform diagram of the igniter of FIG. 5. It is a circuit diagram which shows the structural example of a switch control apparatus. FIGS. 8A to 8D are circuit diagrams illustrating modifications of the noise detection circuit.

  The present invention will be described below based on preferred embodiments with reference to the drawings. The same or equivalent components, members, and processes shown in the drawings are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate. The embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

In this specification, “the state in which the member A and the member B are connected” means that the member A and the member B are physically directly connected, or the member A and the member B are in an electrically connected state. Including the case of being indirectly connected through other members that do not affect the above.
Similarly, “the state in which the member C is provided between the member A and the member B” refers to the case where the member A and the member C or the member B and the member C are directly connected, as well as an electrical condition. It includes the case of being indirectly connected through another member that does not affect the connection state.

FIG. 5 is a circuit diagram of the igniter 200 according to the embodiment. The igniter 200 includes a switch element 202 and a switch control device 300, and is modularized and accommodated in one package.
. The basic configuration of the switch control device 300 is the same as that of FIG. 2, and includes a determination stage 300A, a drive stage 300B, an overcurrent protection (OCP) circuit 330, a gate voltage correction circuit 342, and a noise detection circuit 340. This is a functional IC integrated on a single semiconductor substrate.

  The determination stage 300A includes a high frequency filter 303 and a determination comparator 302. An ignition signal IGT from the ECU 108 is input to the input line 301. The high frequency filter 303 removes high frequency noise from the input line 301.

The determination comparator 302 compares the output voltage V _FIL of the high frequency filter 303 with the reference voltage V _REF and generates a determination signal S _DET . In the present embodiment, the state of V _FIL > V _REF (V _IN > V _REF ) is on for the switch element 202, and the state of V _FIL <V _REF (V _IN <V _REF ) is off for the switch element 202. It is corresponded to. The determination signal S _DET is at a high level (asserted) when V _FIL > V _REF , and is at a low level (negated) when V _FIL <V _REF , and therefore the high level of the determination signal S _DET is 202 is asserted level corresponding to oN, the low level of the determination signal S _DET is a negated level corresponding to the oFF of the switch element 202. Note that the assignment of high level, low level and assert, and negate is a design matter and may be replaced.

Driving stage 300B in response to the determination signal _{S DET} generated by the decision stage 300A, and controls on of the switch element 202, off. The drive stage 300B includes a delay circuit 304, a pre-driver 306, and a gate driver 308. Delay circuit 304, the decision signal _{S DET} gives a predetermined delay Td1. This delay amount Td1 is set so that the time difference (delay) between the transition of the ignition signal IGT and the discharge time of the spark plug becomes a predetermined value. The pre-driver 306 and the gate driver 308 control the voltage V _G of the control terminal (gate) of the switch element 202 according to the output S2 of the delay circuit 304.

The internal regulator 316 generates a power supply voltage V _DD stabilized at a predetermined level and supplies it to the power supply line 314. The gate driver 308 selectively outputs the ground voltage _VSS and the power supply voltage V _DD .

OCP circuit 330 in the on state of the switch element 202, so that the coil current flowing through the switching element 202 (collector current) _{I C} does not exceed the predetermined threshold value (current limit _{I CL),} a control terminal of the switch element 202 Adjust the voltage V _G of. For example, the OCP circuit 330 includes a current sense resistor R _CS , an OCP comparator 332, and an OCP transistor 334. Current sense resistor R _CS is provided in series with the switch element 202 in the path of the coil current I _C, is between its ends, a voltage drop proportional to the coil current I _C (detection voltage V _CS) is generated. The OCP transistor 334 is provided between the control terminal of the switch element 202 and the ground line 312. The OCP comparator 332 compares the detection voltage V _CS with a predetermined threshold voltage V _CL and turns on the OCP transistor 334 when V _CS > V _CL .

The switch control device 300 further includes a noise detection circuit 340 and a gate voltage correction circuit 342. Noise detection circuit 340, based on the first signal S11, detects the noise changing the voltage V _G of the control terminal of the switch element 202 in the negative direction. When detecting the noise, the noise detection circuit 340 asserts the noise detection signal S21. Noise noise detection circuit 340 as a detection target is in the on state of the switch element 202, a noise that may alter the collector current I _C, for example surge or surge of noise, such as ESD and the like. The first signal S11 to be monitored by the noise detection circuit 340 may be a signal (V _IN , V _FIL ) corresponding to the voltage V _IN of the input line 301, or a voltage level corresponding to the determination signal S _DET ( A signal having a logic level).

The gate voltage correction circuit 342 is connected to the control terminal of the switch element 202, and supplies the current _ICMP to the control terminal of the switch element 202 when the noise detection signal S21 is asserted. The gate voltage correction circuit 342 can be grasped as a current source, or can be grasped as a voltage source that pulls up the control terminal of the switch element 202 in the direction of the power supply voltage V _DD as described later. The output impedance of the gate voltage correction circuit 342 is preferably lower than the output impedance of the gate driver 308 provided in the final stage of the drive stage 300B. Thus, if the judgment signal S _DET transitions to off level due to the influence of noise, than action driving stage 300B lowers the gate voltage V _G, the gate voltage correction circuit 342 to the gate voltage V _G original level It will exceed the effect of maintaining the, possible to suppress the coil current I _C decreases.

  The above is the basic configuration of the igniter 200. Next, the operation will be described. FIG. 6 is an operation waveform diagram of the igniter 200 of FIG. For comparison, FIG. 6 shows the operation of the igniter 200 of FIG. 2 in broken lines. The vertical and horizontal axes of the waveform diagrams and time charts referred to in this specification are enlarged or reduced as appropriate for easy understanding, and the waveforms shown are also simplified for easy understanding. Or is emphasized.

When the ignition signal IGT transits to a high level at time t0, the switch element 202 is turned on. Thus the coil current (collector current) I _C increases with time. The coil current I _CL is clamped by the OCP circuit 330 so as not to exceed the current limit I _CL .

At subsequent time t2, when the ignition signal IGT swings in the negative direction due to the influence of the noise S10, the determination signal _SDET also transitions to a low level. When the determination signal SDET transitions to a low level, the gate driver 308 attempts to lower the voltage V _G of the switch element 202 to the low potential side as indicated by a broken line.

When the noise S10 is detected by the noise detection circuit 340, the noise detection signal S21 is asserted (shown here as a high level). The gate voltage correction circuit 342 supplies the current _ICMP to the gate of the switch element 202 in response to the noise detection signal S21. Thus the voltage level of the gate voltage V _G does not decrease as indicated by the broken line, the original voltage level is maintained, as a result, the variation of the coil current I _C is suppressed, the spark plug 106 to spark time t2 Can be prevented.

The above is the operation of the igniter 200.
In summary, the negative direction of the noise is inputted, the decision signal S _DET transition to the OFF level corresponding to the OFF of the switch element 202, the driving stage 300B is an attempt to lower the gate voltage V _G. At this time, by the gate voltage correction circuit 342 supplies a current _{I CMP} to the control terminal of the switch element 202, it is possible to cancel the decrease of the gate voltage _{V G} according to the driving stage 300B. Thus, variation of the gate voltage V _G of the switching element 202, and thus suppress the fluctuation of the coil current I _C, the erroneous ignition can be prevented.

In particular, when the OCP circuit 330 that controls the gate voltage V _G of the switch element 202 is provided, the gate voltage V _G of the switch element 202 is highly sensitive to noise. By providing the gate voltage correction circuit 342 in such circumstances, the variation of the gate voltage V _G due to noise can be preferably suppressed.

  The present invention is understood as the block diagram of FIG. 5 or extends to various circuits derived from the above description, and is not limited to a specific circuit configuration. An example will be described.

FIG. 7 is a circuit diagram illustrating a configuration example of the switch control device 300.
The gate voltage correction circuit 342 includes a first transistor M1 provided between the power supply line 314 and the control terminal of the switch element 202. The noise detection signal S21 is input to the control terminal of the first transistor M1. In this configuration, the current _ICMP can be supplied to the control terminal of the switch element 202 by turning on the first transistor M1 in response to the assertion of the noise detection signal S21.

From another viewpoint, the voltage V _G at the control terminal of the switch element 202 can be pulled up to the high potential side by turning on the first transistor M1. Thus, variation of the gate voltage V _G of the switching element 202, and thus suppress the fluctuation of the coil current I _C, the erroneous ignition can be prevented.

  The on-resistance of the first transistor M1 is preferably lower than the output impedance of the gate driver 308. More specifically, the on-resistance of the first transistor M1 is designed to be sufficiently lower than the on-resistances of the high-side transistor MH and the low-side transistor ML.

More specifically, the first transistor M1 is a P-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor). The source of the first transistor M1 is connected to the power supply line 314, and the drain thereof is connected to the control terminal of the switch element 202. A first resistor R1 is provided between the gate and source of the first transistor M1. Thus, the first transistor M1 can be appropriately turned on / off by asserting the low level of the noise detection signal S21 and negating the high impedance state. Further, the first transistor M1 can be normally off, and the current _ICMP can be made zero in a state where no noise is detected.

  The first signal S11 to be monitored by the noise detection circuit 340 is preferably a determination signal S2 that has passed through the delay circuit 304. By detecting noise as close as possible to the control terminal of the switch element 202, the gate voltage correction circuit 342 can be appropriately controlled.

  The noise detection circuit 340 includes a low-pass filter 344 having a cutoff frequency lower than the frequency of surge or surge noise and receiving a second signal S12 corresponding to the first signal S11. The noise detection circuit 340 generates a noise detection signal S21 according to the potential difference between the third signal S13 that has passed through the low-pass filter 344 and the second signal S12 that has not passed through the low-pass filter 344.

  The second signal S12 varies according to the surge or surge noise, whereas the third signal S13 is substantially constant regardless of the surge or surge noise. Therefore, surge or surge noise can be detected based on the potential difference between the second signal S12 and the third signal S13. For example, the noise detection circuit 340 includes a second transistor M2. A potential difference between the third signal S13 and the second signal S12 is input between the gate and source of the second transistor M2. The second transistor M2 operates as a comparator that compares the potential difference between the third signal S13 and the second signal S12 with the threshold voltage between the gate and the source. As a result, the noise detection signal S21 corresponding to the collector / drain voltage of the second transistor M2 or the current flowing through the second transistor M2 can be generated. It will be understood by those skilled in the art that a voltage comparator or other voltage comparison means can be used in place of the second transistor M2.

  The noise detection circuit 340 further includes an inverter INV1 that inverts the determination signal S1 that has passed through the delay circuit 304 and generates a second signal S12. The second transistor M2 is a P-channel MOSFET, and the third signal S13 is input to the gate of the second transistor M2, and the second signal S12 is input to the source of the second transistor M2. A bipolar transistor may be used as the second transistor M2. In this case, the gate may be read as the base, the drain as the collector, and the source as the emitter.

When the determination signal S _DET (S1) transitions to a low level due to surge or surge noise, the second signal S12 transitions to a high level. Accordingly, since the source is at a high level while the gate of the second transistor M2 is at a low level, the second transistor M2 is turned on and noise can be detected.

  The low pass filter 344 may be an RC filter including a second resistor R2 and a first capacitor C1 provided in series between the line through which the second signal S12 propagates and the ground line 312.

  The inverter INV2 inverts the output of the inverter INV1 and outputs it to the pre-driver 306. Note that the inverter INV2 may be omitted and the output S1 of the delay circuit 304 may be input to the pre-driver 306.

  The configuration of the output stage of the noise detection circuit 340 is not particularly limited, but may be an open drain (open collector) type, for example. For example, the output stage of the noise detection circuit 340 includes a resistor R3 between the drain of the second transistor M2 and the ground line 312, a transistor M3 having a gate connected to the drain of the second transistor M2, and a source connected to the ground line 312. And including. The drain signal of the transistor M3 is output to the gate voltage correction circuit 342 as the noise detection signal S21.

The configuration example of the igniter 200 has been described above. According to this configuration, noise can be detected, and the gate voltage V _G of the switch element 202 can be corrected in response to the noise.

  The embodiments are exemplifications, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are within the scope of the present invention. . Hereinafter, such modifications will be described.

(First modification)
FIGS. 8A to 8D are circuit diagrams showing modifications of the noise detection circuit 340. FIG.
The first signal S11 monitored noise detection circuit 340 in FIG. 8 (a) is a gate signal _{V GH} of the high-side transistor MH gate driver 308. The noise detection circuit 340 may be configured similarly to the noise detection circuit 340 of FIG.

  In the noise detection circuit 340 of FIG. 8B, the inverter INV1 of FIG. 7 is omitted, the second signal S12 is input to the gate of the second transistor M2, and the third signal S13 that has passed through the low-pass filter 344 is input to the source. When the output S2 of the delay circuit 304 transitions to a low level due to noise, the gate of the second transistor M2 is maintained at a low level and the drain is maintained at a high level, so that the second transistor M2 is turned on. Thereby, noise can be detected.

The first signal S11 to be monitored by the noise detection circuit 340 in FIGS. 8C and 8D is the signal _VIN before the high / low binarization in the previous stage of the determination comparator 302. The noise detection circuit 340 in FIG. 8C compares the voltage of the line through which the first signal S11 propagates with the negative threshold voltage V _THN and generates a noise detection signal S21 indicating the comparison result. Comparator 346 is included. This makes it possible to detect steep noise that swings greatly in the negative direction.

The noise detection circuit 340 in FIG. 8D includes a filter 348 and a noise detection comparator 350 (detection circuit). The filter 348 is a high-pass filter or a band-pass filter, and passes a high-frequency component (noise component) of the voltage of the line through which the first signal S11 propagates. The noise detection comparator 350 compares the level of the output signal of the filter 348 with the threshold value V _TH and determines the presence or absence of noise. Surge or surge noise includes a higher frequency component than high frequency noise (periodic noise). Therefore, by extracting these frequency components, it is possible to detect the presence or absence of surge or surge noise.

The first signal S11 of the noise detection circuit 340 of FIGS. 8C and 8D may be the output voltage V _FIL of the high frequency filter 303.

A person skilled in the art understands that the configuration of the noise detection circuit 340 is not particularly limited, and includes various circuit configurations derived from FIGS. 7 and 8A to 8D. For example noise detection circuit 340 may detect the noise based on the gate signal V _GL of the low-side transistor ML.

(Second modification)
In the embodiment, the igniter 200 including the OCP circuit 330 has been described. However, the configuration of the OCP circuit 330 is not particularly limited. For example, as the means for detecting the coil current I _C, the current flowing through the power transistor 204 is copied by the current mirror circuit, may be detected copied current, by using the on-resistance of the power transistor 204 coil The current may be detected. Alternatively, by adding an auxiliary winding in the ignition coil 104 may estimate the coil current I _C on the basis of the current flowing through the auxiliary winding. The OCP circuit 330 is not essential, and the present invention can be applied to an igniter 200 that does not include the OCP circuit 330.

  Although the present invention has been described based on the embodiments, it should be understood that the embodiments merely illustrate the principles and applications of the present invention, and the embodiments are defined in the claims. It goes without saying that many modifications and changes in arrangement are allowed without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 100 ... Vehicle, 101 ... Engine room, 102 ... Battery, 104 ... Ignition coil, 106 ... Spark plug, L1 ... Primary coil, L2 ... Secondary coil, 108 ... ECU, 110 ... Engine, 112 ... Intake manifold, 113 ... Air cleaner, 114 ... radiator, 200 ... igniter, 202 ... switch element, 300 ... switch control device, 300A ... determination stage, 300B ... drive stage, 301 ... input line, 302 ... determination comparator, 303 ... high frequency filter, 304 ... delay circuit 306: Predriver 308 Gate driver 312 Ground line 314 Power line 316 Internal regulator 320 Protection circuit 330 OCP circuit 332 OCCP comparator 334 OCP transistor 340 Neu Detection circuit, 342: Gate voltage correction circuit, 344: Low pass filter, 346: Noise detection comparator, INV1: Inverter, INV2: Inverter, R1: First resistor, R2: Second resistor, C1: First capacitor, MH ... High side transistor, ML: low side transistor, M1: first transistor, M2: second transistor, S11: first signal, S12: second signal, S13: third signal, S21: noise detection signal.

Claims (22)

A switch element connected to the primary coil of the ignition coil;
A switch control device that controls the switch element in response to an ignition signal from an ECU (Engine Control Unit);
With
The switch control device includes:
An input line to which the ignition signal is input;
A determination comparator that compares the voltage of the input line with a reference voltage and generates a determination signal;
A drive stage for controlling on / off of the switch element in response to the determination signal;
When noise that changes the voltage of the control terminal of the switch element in the negative direction is detected based on a first signal having a voltage level according to the voltage of the input line or according to the determination signal, the noise detection signal is asserted. A noise detection circuit that
When the noise detection signal is asserted, a gate voltage correction circuit that supplies a current to the control terminal of the switch element;
An igniter comprising:   2. The igniter according to claim 1, wherein an impedance of the gate voltage correction circuit is lower than an impedance of a gate driver provided at a final stage of the driving stage.   The gate voltage correction circuit includes a first transistor provided between a power supply line to which a stabilized power supply voltage is supplied and a control terminal of the switch element, and receiving the noise detection signal at the control terminal. The igniter according to claim 1 or 2. The first transistor is a P-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor) having a source connected to the power supply line and a drain connected to a control terminal of the switch element.
4. The igniter according to claim 3, wherein the gate voltage correction circuit further includes a first resistor provided between a gate source and a base emitter of the first transistor. The noise detection circuit includes a low-pass filter having a cutoff frequency lower than a frequency of surge or surge noise and receiving a second signal corresponding to the first signal;
5. The noise detection signal is generated according to a potential difference between a third signal that has passed through the low-pass filter and a second signal that has not yet passed through the low-pass filter. 6. Igniter.   The noise detection circuit further includes a second transistor in which a potential difference between the third signal and the second signal is applied between a gate source and a base emitter, and the voltage of the collector / drain of the second transistor or the second transistor 6. The igniter according to claim 5, wherein the noise detection signal corresponding to a current flowing through two transistors is output. The noise detection circuit further includes an inverter that inverts the determination signal and generates the second signal,
The second transistor is a P-channel MOSFET or a PNP-type bipolar transistor,
The igniter according to claim 6, wherein the third signal is input to a gate and a base of the second transistor, and the second signal is input to a source and an emitter of the second transistor.   8. The RC filter according to claim 5, wherein the low-pass filter is an RC filter including a second resistor and a first capacitor provided in series between a line through which the second signal propagates and a ground line. The igniter described in 1. The drive stage is
A delay circuit for delaying the determination signal;
A gate driver for supplying a high level voltage or a low level voltage to the control terminal of the switch element;
A pre-driver that controls the gate driver according to the determination signal that has passed through the delay circuit;
Including
The igniter according to any one of claims 1 to 8, wherein the first signal is the determination signal that has passed through the delay circuit. The drive stage is
A delay circuit for delaying the determination signal;
A driver including a high-side transistor provided between a power supply line and the control terminal of the switch element; and a low-side transistor provided between the control terminal of the switch element and a ground line;
A pre-driver that controls on / off of the high-side transistor and the low-side transistor according to the determination signal that has passed through the delay circuit;
Including
The igniter according to any one of claims 1 to 8, wherein the first signal is a signal of a control terminal of the high-side transistor or the low-side transistor.   The overcurrent protection circuit for adjusting a voltage of a control terminal of the switch element so as to prevent a coil current flowing through the switch element from exceeding a predetermined threshold value. The igniter described in 1. The overcurrent protection circuit is
An overcurrent protection transistor provided between a control terminal of the switch element and a ground line;
An overcurrent protection comparator that compares a detection voltage according to the coil current with a predetermined threshold voltage, and turns on the overcurrent protection transistor when the detection voltage exceeds the threshold voltage;
The igniter according to claim 11, comprising: The first signal is a signal preceding the determination comparator,
The noise detection circuit includes a noise detection comparator that compares a voltage of a line through which the first signal propagates with a negative threshold voltage and generates the noise detection signal indicating a comparison result. The igniter according to any one of claims 1 to 4. The first signal is a signal preceding the determination comparator,
The noise detection circuit includes a filter that passes a high frequency component of a voltage of a line through which the first signal propagates;
A noise detection comparator that compares the level of the output signal of the filter with a threshold;
The igniter according to claim 1, comprising: A switch element connected to the primary coil of the ignition coil;
A switch control device that controls the switch element in response to an ignition signal from an ECU (Engine Control Unit);
With
The switch control device includes:
An input line to which the ignition signal is input;
A determination comparator that compares the voltage of the input line with a reference voltage and generates a determination signal;
A drive stage for controlling on / off of the switch element in response to the determination signal;
A noise detection circuit that asserts a noise detection signal when detecting noise by changing the voltage of the control terminal of the switch element in the negative direction;
A first transistor which is provided between a power supply line to which a stabilized power supply voltage is supplied and a control terminal of the switch element, and which is turned on when the noise detection signal is asserted;
An igniter comprising:   The igniter according to claim 15, wherein an on-resistance of the first transistor is lower than an impedance of a gate driver provided in a final stage of the driving stage. The noise detection circuit includes:
A low pass filter having a cutoff frequency lower than the frequency of surge or surge noise and receiving a second signal corresponding to the first signal having a voltage level corresponding to the determination signal;
A second transistor in which a potential difference between a third signal that has passed through the low-pass filter and a second signal that has not yet passed through the low-pass filter is applied between a gate source and a base emitter;
The igniter according to claim 15 or 16, wherein the igniter outputs a noise detection signal corresponding to a voltage of a collector / source of the second transistor or a current flowing through the second transistor.   The igniter according to claim 17, wherein the low-pass filter is an RC filter including a second resistor and a first capacitor provided in series between a line through which the determination signal propagates and a ground line.   The igniter according to any one of claims 1 to 18, wherein the switch control device is integrated on a single semiconductor substrate. A gasoline engine,
Spark plugs,
An ignition coil having a primary coil and a secondary coil connected to the spark plug;
An ECU for generating an ignition signal instructing ignition of the spark plug;
The igniter according to any one of claims 1 to 19, which drives the ignition coil in response to the ignition signal;
A vehicle comprising: A method of controlling an ignition coil connected to a spark plug,
An ECU (Engine Control Unit) generating an ignition signal instructing ignition of the ignition plug;
Comparing a voltage of an input line transmitted by the ignition signal with a reference voltage to generate a determination signal;
Controlling on and off of a switch element connected to a primary coil of the ignition coil in response to the determination signal;
Detecting noise that changes the voltage of the control terminal of the switch element in a negative direction;
When the noise is detected, supplying a current to the control terminal of the switch element;
A method comprising the steps of: A method of controlling an ignition coil connected to a spark plug,
An ECU (Engine Control Unit) generating an ignition signal instructing ignition of the ignition plug;
Comparing a voltage of an input line transmitted by the ignition signal with a reference voltage to generate a determination signal;
Controlling on and off of a switch element connected to a primary coil of the ignition coil in response to the determination signal;
Detecting noise that changes the voltage of the control terminal of the switch element in a negative direction;
When the noise is detected, turning on a first transistor provided between a power supply line to which a stabilized power supply voltage is supplied and a control terminal of the switch element;
A method comprising the steps of:

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