KR20190034579A - Corona igniter with self-tuning power amplifier - Google Patents

Abstract

A power amplifier circuit for a corona ignition system is provided. This circuit includes an inductor and a capacitor connected to one end of the secondary winding of the RF transformer. The other end of the secondary winding is connected to a current sensor connected to ground. The transformer also includes a primary winding, one end of which is connected to the voltage supply and the other end of which is connected to a pair of switches. The windings are wound around the core and the current creates a magnetic flux from the DC voltage supply to the switch-to-plug core. The voltage is generated on the secondary winding by the current flowing through the igniter. This voltage controls the timing and off timing that is fed back to the switch. The voltage is either provided to the corona igniter or drawn out of the igniter when the current to move to or from the igniter is zero.

Description

Corona igniter with self-tuning power amplifier

This application claims the benefit of United States Patent Application Serial No. 15 / 230,927, filed August 8, 2016, the full disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION The present invention relates generally to igniters used to ignite air / fuel mixtures in automotive applications, and more particularly to self-tuning power amplifiers for use in corona ignition systems.

U.S. Patent No. 6,883,507 discloses an igniter for use in a corona discharge air / fuel ignition system. According to an exemplary method used to ignite the combustion, the electrode is charged with a high RF voltage potential to create a strong RF electric field in the combustion chamber. The strong electric field then allows a portion of the fuel-air mixture in the combustion chamber to be ionized. The process of ionizing the fuel air gas may initiate dielectric breakdown. However, the electric field is dynamically controlled such that dielectric breakdown does not progress to the level of an electron avalanche which forms a plasma and which is struck from the electrode to the grounded cylinder wall or piston. The electric field is maintained at a level where only a fraction of the fuel-air gas is ionized, which is insufficient to generate an electron avalanche chain reaction resulting in plasma as previously described. However, since the electric field is kept strong enough, a corona discharge is generated. In the corona discharge, some of the charges on the electrodes are carried away as a small current through the gas to the ground and destroyed, or they disappear through electrons emitted from the ionized fuel-air mixture or electrons absorbed into the electrode from the ionized fuel-air mixture, Is very small and the voltage potential at the electrode is kept very high compared to the arc discharge. A sufficiently strong electric field ionizes a portion of the fuel-air mixture to promote the combustion reaction. The ionized fuel-air mixture forms the flame front, which is self-sustaining and burns the remaining fuel-air mixture.

Figure 1 shows a capacitively coupled RF corona discharge ignition system. This system is referred to as " capacitively coupled "because electrode 40 does not extend beyond the dielectric material surrounding the feedthru insulator 71b that is directly exposed to the fuel-air mixture. Rather, the electrode 40 is covered by the feedthrough insulator 71b and relies on the electric field of the electrode passing through a portion of the feedthrough insulator to create an electric field in the combustion chamber 50. [

2 is a functional block diagram of a control electronics and primary coil unit 60 in accordance with an exemplary embodiment of the present invention. 2, the control electronics and primary coil unit 60 include a center tapped primary RF transformer 20 that receives, for example, a voltage of 150 volts from a DC source through line 62 . The high power switch 72 is provided for switching the power applied to the transformer 20 between the two phases of phase A and phase B at a desired frequency, for example, the resonant frequency of the high voltage circuit 30 (see FIG. 1) . The 150 volt DC source is also connected to the control electronics and the power supply 74 for the control circuitry in the primary coil unit 60. The control circuit power supply 74 typically drops the 150 volts DC source to an acceptable level for the control electronics, such as 5-12 volts. The output from the transformer 20 indicated by "A" in FIGS. 1 and 2 is used to supply power to the high voltage circuit 30 contained in the secondary coil unit, according to an exemplary embodiment of the present invention.

The current and voltage output from the transformer 20 are detected at point A and conventional signal conditioning is performed at 73 and 75, respectively, for example to remove noise from the signal. This signal conditioning may include active, passive or digital, low pass and band pass filters. The current and voltage signals are full-wave rectified and averaged at 77 and 79, respectively. The averaging of voltage and current to remove signal noise can be performed with conventional analog or digital circuits. The averaged and rectified current and voltage signals are sent to a divider 80 that divides the voltage by the current and calculates the actual impedance. The current and voltage signals are also sent to a phase detector and phase locked loop (PLL) 78, which outputs a frequency that is a resonant frequency for the high voltage circuit 30. The PLL determines the resonant frequency by adjusting the output frequency so that the voltage and current are in phase. In the case of a series resonant circuit, the voltage and current become in phase when excited by resonance.

The calculated impedance and resonant frequency are transmitted to a pulse width modulator 82 that outputs two pulse signals, i.e., phase A and phase B, each having a calculated duty cycle, to drive the transformer 20. The frequency of the pulse signal is based on the resonant frequency received from the PLL 78. The duty cycle is based on the impedance received from the divider 80 and the impedance setpoint received from the system controller 84. The pulse width modulator 82 adjusts the duty cycle of the two pulse signals so that the measured impedance from the splitter 80 matches the impedance set point received from the system controller 84. [

The system controller 84 transmits a trigger signal pulse to the pulse width modulator 82 in addition to outputting the impedance set point. This trigger signal pulse controls the activation timing of the transformer 20 controlling the activation of the high voltage circuit 30 and electrodes (not shown) as shown in FIG. The trigger signal pulse is based on the timing signal 61 received from the master engine controller 86 which is not shown. The timing signal 61 determines when to start the ignition sequence. The system controller 84 receives this timing signal 61 and then transmits the trigger pulse and the impedance set point in the proper sequence to the pulse width modulator 82. This information tells the pulse width modulator when to ignite, how much time to ignite, how long to ignite, and the set point of the impedance. The desired corona characteristics (e.g., ignition sequence and impedance set point) may be hard coded in system controller 84 or transmitted to system controller 84 via signal 63 from master engine controller 86 do. The system controller 84 may send diagnostic information to the master engine controller 86, as is common in modern engine control and ignition systems. Examples of diagnostic information include ignition failure information determined from voltage / overvoltage supplies, current and voltage signals, and the like.

It is an object of the present invention to provide a corona igniter having a self-tuning power amplifier.

A power amplifier circuit is provided in which an inductor and a capacitor are connected to one end of the secondary winding of the RF transformer. The other end of the secondary winding is connected to a resistor connected to ground. The transformer also has a primary winding, one end of which is connected to a power supply. The other end of the primary winding is connected to the switch. The windings are wound around the magnetic core. The primary winding is arranged such that the current flowing from the power supply to the switch causes a magnetic flux in the core in the opposite direction. To start oscillating the circuit, one of the switches is momentarily turned on to ring the inductor and capacitor. As a result, the voltage is generated by the secondary winding and the current sensor, and is fed into the circuit that filters out all noise leaving only the voltage at the inherent frequency of the inductor and capacitor. The current sensor includes at least one of a resistor, a diode, an inductor, and a capacitor. This voltage is fed back to a switch that controls on-timing and off-timing. In this way, the need to measure and record the natural frequency is eliminated.

In one embodiment of the present invention, a power amplifier circuit for a corona ignition system is provided, comprising: an RF transformer having a primary winding and a secondary winding wound around a core; An inductor and a capacitor connected to one end of the secondary winding; And a current sensor connected to the other end of the secondary winding, wherein the current induced in the secondary winding generates a magnetic flux in the opposite direction in the core.

In one aspect of the present invention, the primary winding has one end connected to the variable power supply and the other end attached to the first and second switches, so that the on and off timings of the first and second switches are controlled.

In another aspect of the invention, the secondary winding provides an output signal to the corona igniter.

In another aspect of the invention, the ends of the secondary winding are each connected to two switches that drive the circuit to operate the corona igniter system, so that the corona igniter is ignited.

Another aspect of the present invention provides an internal combustion engine comprising a cylinder head having an igniter opening extending to a combustion chamber accommodating a corona igniter at an upper surface thereof. The engine also includes a control circuit configured to receive a signal from the engine computer; And a power amplifier that generates ac and voltage signals to drive the igniter assembly at its resonant frequency. The igniter assembly includes an inductor, a capacitor, and a current sensor that form an LCR circuit, and one end of the inductor is connected to the electrode crown in the combustion chamber of the combustion engine via the ignition end assembly.

In one aspect of the invention, the power amplifier circuit comprises an RF transformer having a primary winding and a secondary winding, each wound around a core; An inductor and a capacitor connected to one end of the secondary winding; And a current sensor coupled to the other end of the secondary winding, wherein the current induced in the secondary winding creates a magnetic flux in the opposite direction in the core.

In another aspect of the invention, the control circuit determines the voltage to apply to the power amplifier circuit, the power amplifier circuit drives the current through the windings and provides a feedback signal of the resonant frequency of the igniter assembly, Resonance at a certain frequency when the capacitance of the inductor, the resistance in the current sensor, and the inductance in the inductor are combined.

In another aspect of the present invention, the primary winding has one end connected to the power supply and the other end attached to the first and second switches, and the on and off timings of the first switch and the second switch are controlled.

In another aspect of the invention, the secondary winding provides an output signal to the corona igniter.

The foregoing and other features of the present invention may be more clearly understood by those skilled in the art through a detailed description of exemplary embodiments.

According to the present invention, the above-described object can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows an exemplary corona discharge ignition system in the prior art.
2 is a functional block diagram of a control electronics and a primary coil unit according to the prior art system.
Figure 3 shows a self-tuning circuit according to the invention.
4 is a block diagram illustrating an implementation of the circuit of FIG. 3 in a corona ignition system in accordance with an exemplary embodiment.
5 is a block diagram illustrating an implementation of the circuit of FIG. 3 in a corona ignition system in accordance with another exemplary embodiment.

The power amplifier circuit includes an inductor and a capacitor connected to one end of the output winding of the RF transformer. The other end of the output winding is connected to the current sensor and consequently to ground. The current sensor includes at least one of a resistance diode, an inductor and a capacitor. The transformer has two primary windings. One end of the two primary windings is connected to a variable DC voltage supply. The other end of each primary winding is connected to a MOSFET. All three windings are wound around the ferrite core. The two primary windings are arranged such that the current flowing from the DC voltage supply to the MOSFET generates magnetic flux in opposite directions in the ferrite core. To begin oscillating the circuit, one of the MOSFETs is turned on momentarily to ring the inductor and capacitor. As a result, a voltage is generated on the secondary winding circuit sensor and fed to the circuit, which filters out all the noise leaving a voltage at the inherent frequency of the inductor capacitor. This voltage controls the on and off timing that is fed back to the MOSFET. The need to measure and record natural frequencies in this way is eliminated.

The circuit shown in Fig. 3 includes a transformer, a MOSFET for driving the transformer, and a feedback circuit for tuning the operating frequency of the transformer. The transformer comprises, for example, a ferrite core having four sets of windings around the core. Inductors L1 and L2 are primary windings and are coupled together at the point connected to the DC voltage supply. The circuit may be designed to operate in a voltage supply voltage range, and in this embodiment the voltage will be set to 60VDC. The other ends of the inductors L1 and L2 are respectively connected to switches indicated by MOSFETs. Other types of switches may be used, as will be readily appreciated by those skilled in the art. Each switch may be referred to as an oscillator.

Inductor L3 is the secondary or output inductor of the transformer. One end of L3 is connected through a low value resistor. The other end is connected to the inductor of the corona igniter. The fourth inductor L6 is a sense inductor that provides a feedback signal to compensate for the varying capacitance of the attachment cables of various lengths.

The ignition system consists of three subassemblies: a control circuit, a power amplifier and an igniter assembly.

Control circuit: This circuit receives a signal from the engine computer (ECU) that signals the system when starting and ending the corona in the cylinder. This circuit determines the voltage to be applied to the power amplifier transformer. A portion of this circuit produces a DC voltage that is applied to the power amplifier transformer.

Power Amplifier Circuit: This circuit generates ac and voltage signals to drive the igniter assembly to a resonant frequency. This circuit receives commands from the control circuit to start and terminate the oscillation. The power amplifier circuit includes a circuit for driving the current through the transformer and a circuit for feeding back the resonant frequency of the igniter assembly. This feedback signal includes a signal associated with the inductor resonance, a signal associated with the primary winding voltage, and a feedback signal associated with the secondary winding voltage.

Igniter Assembly: The igniter assembly is attached to the cylinder head in a manner similar to a spark plug. The assembly includes an inductor and a firing end subassembly including an electrode inside the combustion chamber. The igniter assembly includes inductors, capacitors and current sensors wired together as an LCR assembly. When a voltage is applied to one end of the inductor, the LCR assembly resonates. The inductor is part of the igniter. The second end of the inductor is connected to the electrode crown in the combustion chamber through the ignition end assembly. The ignition end assembly and the combustion chamber form a resonant capacitance and resistance at a particular frequency when combined with the inductance.

In operation, a device such as an engine computer (ECU) sends a signal to the control circuit. This signal tells the control circuit to start and end the corona at each igniter. The control circuit normally sends a high signal to the power amplifier that is low to initiate a corona event. As long as the corona is required, the signal is held low and returned high to terminate the corona event. This signal is applied to node A, which is the emitter of Q13. A change in voltage at A changes node N from high to low. Node N is then transferred to the two locations.

One destination is the collector of Q12 and the base of Q12 and Q7. Due to the voltage drop of N, Q12 and Q7 turn on and current flows to node Z. The second destination is C3, which sends a short voltage drop through R13 and diode 1 to the R node, which is the base of Q9. Which in turn causes the voltage at node T to drop short. This dipping at the base turns Q5 on, pulling current out of node Z, and raising node B from negative to positive. This turns on Q11 and turns off Q17, which turns on Q1 and turns off Q2. This raises the emitter connected to node C, which is the gate of M1, through R16 and diode 2. Node C moves from negative to positive to turn on M1. The drain of M1 is connected to L2 and its source is connected to ground. When M1 is turned on, current flows through L2 and then flux, which flows through the ferrite inside the transformer.

Since M1 remains on, the current is conducted through L2 until the voltage at node T returns to a value blocking Q5. This causes the current flowing through node Z to be transferred from R11 to R18 and to raise the node H from negative to positive. This turns Q8 on and Q20 off so that Q4 is turned on and Q3 is turned off. This raises their emitter connected to the gate of node F, M4 through R17 and diode 3. The node F moves from negative to positive and turns on M4. The turn on of M4 causes a current to flow through L1 and then the ferrite inside the transformer induces the magnetic flux to flow in the opposite direction to the flux caused by L2.

The transformer ferrite flux creates a current through the transformer secondary winding L3, which generates a voltage across it. One end of L3 is connected to R14 connected to ground. The other end of L3 is connected to the inductor of the igniter assembly. The abrupt change in voltage applied to the igniter LCR assembly induces its resonance. When current flows through R14, the voltage of node L rises. This voltage is supplied to node A2 via R15. The current from node A2 passes through L5 connected to C5 and R19. These devices form a low-pass filter and provide a phase shift at less than 180 ° of current, eliminating frequencies outside the specified range. This signal is clipped by D7 and D8, and then through C7 to drive Q10. When Q10 is turned on, current flows through R18 and stops through R11. This switches M1 off, M4 on, or vice versa.

4 illustrates an implementation of the circuit of FIG. 3 in a corona ignition system in accordance with one embodiment. The system of Figure 4 includes a pulse generator A, a comparator block B, switches C and D, a transformer E, a current sensor F, a low pass filter G and a clamp H . A corona igniter (not shown) is connected to the transformer E.

The operation of the system is initiated by a command signal or "enable signal" 1 issued by an external source such as an engine control unit. The "enable signal" 1 corresponds to point A in the circuit of Fig. The "start" pulse generator A receives the enable signal 1 and transmits a non-inverting output 2 which, in response to the enable signal 1, initiates oscillation of the current flowing through the system and the corona igniter. The pulse generator A corresponds to the components C3, R13, R12 and D1 of the circuit of Fig.

The comparator block B receives the enable signal 1 as well as the noninverting input 2 from the pulse generator A and the inverting input 3 from the lowpass filter G and clamp H. [ The signal received by the inverting input 3 of comparator block B represents the phase of the current in the corona igniter. The non-inverting input 2 corresponds to Q9 and the inverting input 3 corresponds to Q10 in Fig. The comparator block B generates control signals for the switches C and D. The control signal provided by comparator block B is based on the information in enable signal 1, non-inverting input 2 and inverting input 3. The inverting input 3 is also referred to as a feedback signal from the low pass filter (G) and clamp (H). The comparator block B provides control signals to the switches C and D as normal output 4 and inverted output 5. The normal output 4 corresponds to point H and the inverted output 5 corresponds to point G in Fig. Outputs 5 and 4 of comparator block B also correspond to Q5 and Q6 in Fig.

Switches C and D receive normal output 4 and inverted output 5. The first switch (C) receives the normal thrust (4) and the second switch (D) receives the inverted output (5). The first switch C corresponds to Q3, Q4, Q9, Q22 and Q101 in Fig. 3, and the second switch D corresponds to Q1, Q2, Q11, Q17 and Q102. In response to outputs 4 and 5, switches C and D apply a voltage through signals 6 and 7, respectively, to a transformer E connected to the corona igniter via output 9, causing current oscillation in the corona igniter.

Transformer E receives the voltage from switches C and D and transformer E increases the drive voltage of the corona igniter in addition to causing oscillation of the corona igniter. When the circuit is turned on, voltage is always applied to the corona igniter from the transformer (E). The positive voltage is applied whenever a current flows through the corona igniter, and a negative voltage is applied whenever the current is drawn out of the corona igniter. Switching from positive to negative or vice versa should occur as close to zero current as possible. In one possible way, the transformer E has three windings wound around the magnetic core 12 corresponding to L1, L2 and L3 in Fig. One end of each of the primary windings L1 and L2 is attached to the power supply and the other end thereof is attached to one of the switches C and D. The end of the secondary winding L3 is attached to the corona igniter The end portion is attached to the current sensor F. L1 and L2 are arranged with switches C and D such that they produce an opposing magnetic field in magnetic core 12 when they are energized. The voltage output produced by the transformer E is a balanced square wave output that is symmetrical with respect to zero.

The current sensor F of the system receives the current at the output of the transformer E via signal 10 and measures the current at the output of the transformer E which is the current of the corona igniter. The current sensor F includes at least one of a resistor, a diode, an inductor and a capacitor. The current sensor F of Fig. 3 is a resistor located at R14. The current measurement obtained by the current sensor F is essentially used to control the voltage of the secondary winding L3 such that the voltage of the secondary winding is "in phase" with the current of the corona igniter. The term "in-phase" refers to simultaneous voltage peaks and current peaks, which means that the corona ignition device operates at the resonant frequency. More specifically, the block comparator B uses the information obtained by the current sensor F to command the switches C and D to apply a voltage to the primary winding of the transformer E at a predetermined time. The voltage applied to the primary windings L1 and L2 is timed so that the secondary winding L3 has a voltage on the same level as the current of the corona igniter.

More specifically, when current is transferred from the transformer E to the corona igniter, the current delivered to the corona igniter is sensed by the current sensor F. Thus, the current sensor F ultimately transfers the signal to the second switch D, applying a positive voltage, and thus pushing more current from the transformer E to the corona igniter. The signal from the current sensor F to the switch D indicates the time that the current delivered to the igniter passes through zero. The switch D is turned on so that when the current to the corona igniter is zero or nearly zero, the transformer E provides a positive voltage to provide more current to the corona igniter. Switching from positive voltage to negative voltage or vice versa should occur as close to zero current as possible.

Likewise, when current flows from the corona igniter through the transformer E to ground, the current from the corona igniter is also sensed by the current sensor F. [ Accordingly, the current sensor F ultimately transmits the signal to the first switch C, closing the switch and applying a negative voltage to draw more current from the corona igniter. The signal from the current sensor F to the switch C represents the time that the current out of the igniter passes through zero. The switch C is then closed, causing the transformer E to apply a negative voltage, so that more current is drawn from the corona igniter when the current from the corona igniter is exactly zero or nearly zero.

Switching between delivering current to the corona igniter and withdrawing current from the corona igniter when the current is nominally zero allows the system to operate at the resonant frequency. In the example of Figures 3 and 4, when the current travels to the corona igniter, the voltage at the current sensor is negative and the voltage at the current sensor is positive when the current moves out of the corona igniter. Also, R1, L6 and C6 in Fig. 3 compensate for the cable length between the circuit and the corona igniter.

The low-pass filter (G) of the system receives the voltage signal representative of the current from the transformer (E) and removes or filters undesired frequencies or frequencies outside the range of interest. The low pass filter (G) also generates a phase shift at a current of at least 120 degrees and less than 180 degrees. As described above, the low-pass filter G also provides a feedback signal to the comparator block B, which in turn includes a phase of the current of the corona igniter indicating whether the current is positive, negative or zero. The low-pass filter G corresponds to L5, C5, R9 and R10 in Fig.

The clamp H receives the feedback signal from the low-pass filter G and truncates the signal before sending the feedback signal, i. E. Inverting input 3, to the comparator block B. The feedback signal provided in comparator block B provides only zero crossing current detection. In Fig. 3, the clamp H is located at D7 and D8.

The operations of the system and the signals transmitted between the components of the system are described in detail. Initially, before the operation of the system is initiated by enable signal 1 sent to comparator block B, comparator block B is disabled, and normal output 4 and inverse output 5 are off. At this point the HV power supply 8 is enabled and ready to supply power to the transformer E. The HV power supply 8 is external to the system. In Figure 3, the HV power supply is connected to COM +. However, no current flows into the transformer E before the system operation starts.

As described above, the operation of the system is initiated by enable signal 1, which powers comparator block B. The enable signal 1 also causes the pulse generator A to generate a non-inverting input 2 comprising a short pulse that forces the block B to lose balance. This causes the normal output 4 to temporarily enable the first switch C so that current flows from the HV power supply 8 to the signal 7 through the primary winding of the transformer E. [ The output 9 of the transformer E is negatively driven and current continues to flow through the transformer E and current sensor F to ground.

The current flowing to ground through the transformer E and current sensor F raises the voltage at signal 10, which reflects the current flow in the corona igniter. However, the voltage at signal 10 includes a high frequency component due to the charging and discharging of the parasitic capacitance of the system, especially at the connecting cable. The filter block G removes this undesired frequency and provides a phase shift. The phase shift is at least 120 °, preferably close to 180 ° but less than 180 °. Thus, the low-pass filter G provides a clean sinusoidal current signal 11 that is reflected in a phase substantially opposite to the current of the corona igniter. A 180 DEG phase shift is additionally provided using the inverting input 3 of the comparator block (B). A delay that can not be avoided in comparator block (B) and switches (C, D) results in a total 360 ° phase shift. This is a necessary condition for stable oscillation.

The clamp H clips the magnitude of the current signal 11 and converts the signal 11 into a square wave. This square wave is supplied to the inverting input 3, that is, the feedback signal, and the comparator block (B). The phase shift causes the inverting input 3 provided in the negative input of comparator block B to be a positive feedback around the entire loop. Positive feedback is a necessary condition for oscillation of the system and the corona igniter.

At this point, due to the resonant LC action of the corona igniter attached to the transformer E via signal 9, the current flowing through the signal 9 to the peak of the corona igniter falls to zero and then passes through zero. This causes the voltage at the signal 10 from the transformer E to the current sensor F to be inverted in sign. The inverted signal causes the comparator block B to change the state of the normal output 4 and the inverted output 5 and to swap the conductance from the first switch C to the second switch D, It reverses the current flowing through the system. The current travels the other way and produces a negative half-wave in signal 10. This process continues until "enable" signal 1 is removed.

After the first cycle, a steady state operation is achieved, a short pulse from the pulse generator A provided at non-inverting input 2 is terminated, and the voltage at non-inverting input 2 is quiescent. The voltage at the inverting input 3 is a square wave of small amplitude around the stop level and the square wave of small amplitude is anti-phase to the current of the corona igniter.

Paging of the current through the switches (C, D) and the transformer (E) and the applied voltage forces the current and voltage of the corona igniter in phase. This provides the necessary conditions for resonance of a series LC circuit, such as a corona igniter, which is a series LC circuit. Thus, the implementation of the circuit of FIG. 3 in accordance with the system of FIG. 4 forces the operation of the corona igniter at the resonant frequency and forces the corona ignition system to operate at the resonant frequency of the corona igniter.

Figure 5 shows an implementation of the circuit of Figure 3 in a corona ignition system according to yet another embodiment. The system of FIG. 5 is referred to as an analog implementation and a full bridge. 5, the system of FIG. 5 also includes a pulse generator A, a comparator block B, switches C1, C2, D1 and D2, a transformer E, a current sensor F, (G) and a clamp (H). A corona igniter (not shown) is connected to the transformer E.

In the system of Fig. 5, the switches C1, C2, D1, and D2 are pairs of diagonally opposed pairs of FETs that are activated to sequentially connect both ends of one primary winding L1 to Vin and ground. For example, the upper right / lower left pair of switches causes current to flow from the top to the bottom of the primary winding L1; The lower right / upper left pair of switches causes the current to flow in the opposite direction. Also in this system, the capacitor C of the primary winding L1 is optional. The advantage of the system of Figure 5 is that it includes a simpler transformer E due to better use of the core 12. [ In addition, since only Vin is present at both ends of the FET, a better and less expensive FET can be used. Also, a single FET fault does not lead to a short circuit. And the energy trapped in the leakage inductance can be safely guided to the primary winding L1.

The operation of the system is initiated by an instruction signal or "enable signal" 1 provided by an external source, such as an engine control unit. The "enable signal" 1 referred to as the command signal corresponds to point A of the circuit of Fig. The "start" pulse generator A is used to start the oscillation where the enable signal 1 will be asserted. The "start" pulse generator A receives the enable signal 1 and transmits a non-inverting output 2 which, in response to the enable signal 1, initiates oscillation of the current flowing through the system and the corona igniter. The pulse generator A corresponds to C3, R13, R12, and D1 of the circuit of Fig.

Comparator block B receives enable signal 1 and provides a complimentary complimentary corresponding to Q12, Q7, QS, Q6, Q9 and Q10 of FIG. The comparator block B generates a control signal for switching based on the enable signal 1 and the feedback signal. More specifically, the comparator block B receives the enable signal 1 as well as the non-inverting input 2 from the pulse generator A and the inverting input 3 from the lowpass filter G and clamp H. [ The signal received by the inverting input 3 of the comparator block (B) represents the phase of the current in the corona igniter. The non-inverting input 2 corresponds to the input of 09 (Q9b) of Fig. 3 and the inverting input 3 corresponds to the input of Q10. The comparator block B then generates control signals for the switches C1, C2, D1 and D2. The control signal provided by comparator block B is based on the information of enable signal 1, non-inverting input 2 and inverting input 3. The inverting input 3 is also referred to as a feedback signal from the low-pass filter (G) and the clamp (H). The comparator block B provides control signals to the switches C1, C2, D1, D2 as normal output 4 and inverted output 5. The normal output 4 corresponds to point H in Fig. 3 and the inverted output 5 corresponds to point B in Fig. Outputs 5 and 4 of comparator block B also correspond to QS and Q6 in FIG. The enable signal 1 also corresponds to G in Fig.

The system of Figure 5 includes two pairs of switches including a first switch (C1, C2) and a second switch (D1, D2) for applying a voltage to the transformer (E) to produce oscillation of the corona igniter. The first switches Cl and C2 are turned on as a pair, the second switches D1 and D2 are turned off, and vice versa. For example, switch C1 receives normal output 4 and switch D1 receives inverted output 5. Alternatively, switch C2 receives the normal output 4 and switch D2 receives the inverted output 5. In response to outputs 4 and 5, switches C1 and D1 or C2 and D2 each apply a voltage via signals 6 and 7 to a transformer E connected to the corona igniter via output 9 and thus cause oscillation of the current in the corona igniter .

The transformer E increases the drive voltage and produces a balanced square wave output that is symmetric with respect to zero. The transformer E also includes a single primary winding corresponding to L1 in Fig. 5 and a single secondary winding corresponding to L3 in Fig. 5 for an available compensation. The transformer E with the single primary winding L1 of Figure 5 is different from the transformer E of Figure 4 comprising two primary windings L1 and L2 and one secondary winding L3. More specifically, in addition to receiving the voltage from switches C1, C2, D1, D2 and causing oscillation of the corona igniter, the transformer E of Figure 5 increases the drive voltage of the corona igniter . When the circuit is on, the voltage is always applied from the transformer E to the corona igniter. The positive voltage is applied whenever a current flows into the corona igniter, and the negative voltage is applied each time the current flows out of the corona igniter. Switching from positive to negative or vice versa should occur at as close to zero current as possible. In this example, the transformer E has one primary winding L1 wound around the magnetic core 12. The primary winding L1 has one end alternately attached to the power supply or ground via the switches D1 and C2 and has the other end alternately attached to the power supply or ground via the switches Cl and D2. One secondary winding L3 has one end attached to the corona igniter and the other end attached to the current sensor F. As described above, the voltage output generated by the transformer E is at zero Balanced < / RTI > square wave output.

The current sensor F of the system of Figure 5 measures the output of the transformer E and the current of the corona igniter. The current sensor F also controls switching for resonant operation. More specifically, the current sensor F receives the current at the output of the transformer E via the signal 10 and measures the current at the output of the transformer E, which is also the current of the corona igniter. The current sensor F includes at least one of a resistor, a diode, an inductor and a capacitor. The current sensor F of Fig. 3 is a resistor located at R14. The current measurement obtained by the current sensor F is ultimately used to control the voltage of the secondary winding L3 such that the voltage of the secondary winding is "in phase" with the current of the corona igniter. The term "in-phase" means that the voltage peak and the current peak are at the same time, which means that the corona igniter operates at the resonant frequency. More specifically, the block comparator B instructs the switches C1, C2, D1, and D2 using the information obtained by the current sensor F to output a command to the primary winding L1 of the transformer E at a predetermined time Voltage is applied. The voltage applied to the primary winding L1 is timed so that the secondary winding L3 has the same phase voltage as the current of the corona igniter.

More specifically, when a current is transferred from the transformer E to the corona igniter, the current transmitted to the corona igniter is sensed by the current sensor F. In response, the current sensor F ultimately transmits a signal through the second switch Di or D2 and applies a positive voltage to push more current from the transformer E to the corona igniter. The signal from the current sensor F to the switch D1 or D2 indicates the time that the current delivered to the igniter passes through zero. When the switch D1 or D2 is turned on and the current flowing to the corona igniter is zero or nearly zero, the transformer E causes the positive voltage to bump, which causes more current to be provided to the corona igniter. Switching from a positive voltage to a negative voltage or vice versa should occur as close to zero current as possible.

Likewise, when a current exits the corona igniter and travels through the transformer E to ground, the current traveling from the corona igniter is also sensed by the current sensor F. In response, the current sensor F ultimately transmits a signal to the first switch C1 or C2, causing the switch to close and apply a negative voltage, thus drawing more current out of the corona igniter. The signal from the current sensor F to the switch C1 or C2 represents the time that the current traveling out of the igniter passes through zero. Closing the switch C1 or C2 causes the transformer E to apply a negative voltage so that more current is drawn from the corona igniter when the current from the corona igniter is exactly zero or nearly zero.

Simultaneous switching between the transfer current to the corona igniter and the current draw from the corona igniter allows the system to operate at the resonant frequency when the current passes nominalally zero. In the example of Figures 3 and 5, when the current moves to the corona igniter, the voltage at the current sensor F is negative, and when the current moves out of the corona igniter, the voltage at the current sensor F is positive . Also, R1, L6 and C6 in Fig. 3 compensate for the cable length between the circuit and the corona ignition device.

The low pass filter (G) of the system of Figure 5 removes frequencies outside the range of interest and produces a phase shift in the feedback signal. More specifically, the low-pass filter G receives a voltage signal representative of the current from the transformer E and removes or filters out frequencies or unwanted frequencies outside the range of interest. The low-pass filter (G) also produces a phase shift at a current greater than 120 ° and less than 180 °. As mentioned above, the low-pass filter G also provides a feedback signal to the comparator block B, which in turn includes a phase of the current of the corona igniter, wherein the current represents a positive value, a negative value or zero acknowledgment. The low-pass filter G corresponds to L5, C5, R10 and R9 in Fig.

The clamp (H) of the system of FIG. 5 reduces the amplitude of the feedback signal for zero crossing detection only. The first comparator block B is disabled, and the normal output 4 and the inverted output 5 are turned off. The HV supply 8 is already enabled, and no current flows through the transformer E. In operation, the clamp H receives the feedback signal from the low-pass filter G and truncates the signal before sending the feedback signal, i. E. Inverting input 3, to the comparator block B. The feedback signal provided in comparator block B is provided for zero crossing current detection only. In Figure 3, the clamp H of this system is located close to nodes J and C7.

The operation of the system and the signals transmitted between the components of the system are described in more detail below. First, comparator block B is disabled and normal output 4 and inverted output 5 are off before the operation of the system is initiated by enable signal 1 sent to comparator block B. At this point the HV power supply 8 is enabled and ready to supply power to the transformer E. The HV power supply 8 is external to the system. In Figure 3, the HV power supply is connected to COM +. However, no current flows into the transformer E before the system operation starts.

As described above, the operation of the system is initiated by enable signal 1, which powers comparator block B. Enable signal 1 also causes pulse generator A to generate non-inverting input 2, which includes a short pulse that causes comparator block B to lose balance. This causes the normal output 4 to be temporarily enabled to enable the first switch C1 or C2 to be switched from the HV power supply 8 to the signals 6 and 7 via the primary winding L1 of the transformer E Current flows. Output 9 of transformer E is driven negative and current continues to flow from output 9 to ground through transformer E and current sensor F. [

Current flowing to ground through the transformer E and current sensor F reflects the current flow in the corona igniter and raises the voltage at signal 10. However, the voltage at signal 10 includes a high frequency component due to the charging and discharging of the parasitic capacitance of the system, especially at the connecting cable. The filter block G removes this undesired frequency and provides a phase shift. The phase shift is at least 120 °, preferably close to but less than 180 °. Thus, the low-pass filter G provides a clean sinusoidal current signal at signal 11, but is almost opposite in phase to the current of the corona igniter. An additional 180 [deg.] Phase shift is provided using the inverting input 3 of the comparator block (B). The inevitable delay in comparator block B and switches C1, C2, D1, D2 results in a full phase shift of 360 degrees. This is a condition for stable oscillation.

The clamp H clips the magnitude of the current signal 11 and converts the signal 11 into a square wave. This square wave is supplied to the inverting input 3, that is, the feedback signal and the comparator block (B). Due to the 180 [deg.] Phase shift, the inverting input 3 provided to the negative input of the comparator block (B) is the positive feedback through the whole loop. Positive feedback is a necessary condition for corona gauging and system oscillation.

At this time, due to the resonant LC action of the corona igniter attached to the transformer E via the signal 9, the current flowing through the signal 9 to the peak of the corona igniter falls to zero and then passes through zero. This causes the voltage of the signal 10 from the transformer E to the current sensor F to reverse its sign. The inverted signal causes comparator block B to change the state of normal output 4 and inverted output 5, swapping the conductance from the first switch C1 or C2 to the second switch D1 or D2, and inverting the entire process , Current flows from HV power supply 8 to signal 7 and signal 6. The current is driven in a different way to produce a negative half-wave in signal 10. This process continues until "enable" signal 1 is removed.

After the first cycle, a steady state operation is achieved, a short pulse from the pulse generator A provided at the non-inverting input 2 is terminated, and the voltage at the non-inverting input 2 is at the stop level. The voltage at the inverting input 3 describes a square wave of small amplitude around the stop level and a square wave of small amplitude is in phase with the current of the corona igniter.

The phasing of the current through the switches C1, C2, D1 and D2 and the transformer E and the applied voltage means looking at the corona igniter at output 9 and the current and voltage of the corona igniter And is forced in phase. This provides the necessary conditions for resonance of a series LC circuit such as a corona igniter. Thus, an implementation of the circuit of FIG. 3 in accordance with the system of FIG. 5 enforces operation of the corona igniter at a resonant frequency and allows the corona ignition system to operate at the resonant frequency of the corona igniter.

Modifications and modifications to the disclosed embodiments will be readily apparent to those skilled in the art and are included within the scope of the present invention. Accordingly, the scope of protection of the present invention can be determined by studying the following claims. It is contemplated that all such claims and all features of all embodiments are capable of being combined with one another, unless such combinations are contradictory.

Claims (17)

In a power amplifier circuit for a corona igniter,
An RF transformer comprising a primary winding and a secondary winding, the primary winding and the secondary winding comprising: an RF transformer wound around a magnetic core;
An inductor and a capacitor connected to one end of the secondary winding; And
And a current sensor connected to the other end of the secondary winding,
Wherein the current through the secondary winding produces a magnetic flux in opposing eaves within the magnetic core.
The method according to claim 1,
The primary winding has a general part connected to the power supply and a first switch and a second end attached to the second switch. The first switch and the second switch are connected to a power amplifier whose on timing and off timing are controlled Circuit.
3. The method of claim 2,
The secondary winding is a power amplifier circuit that provides an output signal to the coil or igniter.
The method according to claim 1,
Wherein the current sensor is at least one of a resistor, a diode, an inductor, and a capacitor.
The method according to claim 1,
Pass filter comprises a corona igniter having a resonant frequency, an oscillator, and a low-pass filter, the low-pass filter providing a phase shift greater than 120 ° and less than 180 ° from the current, filtering unwanted frequencies, And provides a filtered feedback signal to operate at a resonant frequency of the power amplifier circuit.
In a corona igniter system,
A primary winding having an end for receiving power from the power supply;
A pair of switches respectively connected to the other end of the primary winding for applying a voltage to the primary winding;
A secondary winding disposed around the magnetic core in a direction opposite to the primary winding and having one end connected to the corona igniter;
The current sensor-current sensor connected to the other end of the secondary winding and ultimately connected to the switches acquires the current of the secondary winding and instructs the switch to apply voltage to the primary winding using the current of the secondary winding And at the same time inducing the voltage of the secondary winding to be in phase with the current of the corona igniter
Corona igniter system.
The method according to claim 6,
A comparator block which receives a signal representative of the current obtained from the sensor and instructs the switch to apply a voltage to the primary winding while simultaneously causing the voltage of the secondary winding to be in phase with the current of the corona igniter Including a corona igniter system.
8. The method of claim 7,
Comprising a low pass filter that receives a signal representative of the current from the current sensor and removes unwanted frequencies from the current and generates a phase shift of greater than 120 degrees and less than 180 degrees to the current prior to sending the signal to the comparator block Igniter system.
9. The method of claim 8,
And a clamp that receives the signal representative of the current from the low pass filter and truncates the signal prior to transmitting the signal to the comparator block.
A method of operating a corona igniter at a resonant frequency,
Obtaining a current from a secondary winding connected to the corona igniter, the current of the secondary winding indicating the current of the corona igniter, and the secondary winding being connected to the primary winding;
And instructing the switch to apply a voltage to the primary winding to cause the voltage of the secondary winding to be in phase with the current of the corona igniter
A method of operating a corona igniter at a resonant frequency.
11. The method of claim 10,
The method comprising: transmitting a signal indicative of a current in a comparator block, wherein the comparator block commands the switch to apply a voltage to the primary winding at a resonant frequency.
12. The method of claim 11,
And removing the undesired frequency from the signal indicative of the current and generating a phase shift greater than 120 ° and less than 180 ° in the current prior to transmitting the signal to the comparator block .
13. The method of claim 12,
And cutting the signal indicative of the current prior to transmitting the signal to the comparator block.
11. The method of claim 10,
Obtaining the current from the secondary winding includes detecting a current traveling to the corona igniter; And applying a positive voltage to the corona igniter when the current to the corona igniter is nominally zero.
11. The method of claim 10,
Obtaining the current from the secondary winding includes detecting a current traveling out of the corona igniter; And applying a negative voltage to the corona igniter when the current traveling out of the corona igniter is nominally zero.
In a power amplifier circuit,
An RF transformer comprising a primary winding and a secondary winding, the primary winding and the secondary winding comprising: an RF transformer wound around a core;
A primary winding having one end coupled to the power supply and the other end attached to the switches, the current flowing from the DC voltage supply to the switch;
An inductor and a capacitor connected to one end of the secondary winding of the RF transformer; And
A resistor connected to the other end of the secondary winding and connected to ground,
The current flowing from the DC voltage supply to the switch causes a magnetic flux in the core and causes a voltage to be generated in the resistance of the secondary winding, which is fed back to the switch to control the on and off timings of the switch
Power amplifier circuit.
A method of operating a power amplifier circuit,
Providing a RF transformer having a primary winding and a secondary winding wound around the core, the secondary winding comprising a resistor, the primary winding having one end connected to the power supply and the other end attached to the switches And current flows from the DC voltage supply to the switch;
Providing an inductor and a capacitor connected to one end of the secondary winding of the RF transformer;
Providing a resistor connected to the other end of the secondary winding and ground;
Transferring current from the DC voltage supply to the switches to induce magnetic flux in the core and cause voltage generation in the resistance of the secondary winding; And
And feeding back the voltage generated in the resistance of the secondary winding to the switch so as to control the on-timing and the off-timing of the switch
A method of operating a global amplifier circuit.

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