CN201206526Y - Ignition coil driving circuit - Google Patents

Abstract

The utility model provides a driving circuit for an ignition coil. The driving circuit for the ignition coil comprises an insulated gate bipolar transistor (P1) and a protective circuit, wherein, the protective circuit comprises a triode (T1) and a voltage-regulating resistor (VR1), the voltage-regulating resistor (VR1) is connected in parallel between the base electrode and the emitting electrode of the triode (T1), the emitting electrode of the triode (T1) is grounded, and the collecting electrode and the base electrode of the triode (T1) are respectively connected with the grid electrode and the source electrode of the insulated gate bipolar transistor (P1). By adopting the protective circuit, the current flowing in the insulated gate bipolar transistor IGBT can be limited, and the secondary ignition coil can be prevented from being burnt out due to excessively high current in the primary ignition coil.

Description

An ignition coil drive circuit

technical field

The utility model relates to an ignition coil driving circuit.

Background technique

The engine is the core power part of the whole car, and the failure of the ignition coil in the electronic ignition internal combustion engine will directly cause the whole car to break down. Therefore, in order to improve the performance of the vehicle, improving the safety protection measures of the ignition coil has become an urgent problem to be solved. In the electronic ignition type internal combustion engine, the ignition method adopts the rapid charging and discharging of the high inductance coil to generate a high instantaneous voltage, and then generates a higher voltage through the voltage transformation of the secondary coil, thereby generating sparks through the discharge of the spark plug to ignite the fuel. . If the control conduction time of the engine electronic management system is too long, it will cause the ignition coil to be magnetized and saturated, and the current will increase instantaneously, thus burning the secondary ignition coil.

Figure 1 is an existing ignition coil drive circuit, which includes a primary ignition coil 1, a secondary ignition coil 2, a spark plug 3, an insulated gate bipolar transistor (IGBT) P1 and a resistor R11, the connection relationship is shown in Figure 1, The end of the resistor R11 that is not connected to the gate of the IGBT P1 is used as the ignition signal input terminal 5, the source of the IGBT1 is used as the ignition ground 6 and grounded, and the end of the primary ignition coil 1 that is not connected to the drain of the IGBT P1 is used as the ignition power terminal 7. When the ignition signal input by the ignition signal input terminal 5 is at a high level, the IGBT P1 is turned on, and the primary ignition coil 1 connected to it generates an instantaneous current. Since the primary ignition coil 1 has the function of suppressing the current, the current will increase slowly until the current reaches the maximum value after the coil is magnetized and saturated. When the magnetization is saturated for a certain period of time, the ignition signal changes from high level to low level, so that the IGBT P1 is cut off, so that the current of the primary ignition coil 1 is cut off instantaneously, and a large induction is generated in the primary ignition coil 1 Voltage. Since the number of turns of the secondary ignition coil 2 is much larger than the number of turns of the primary ignition coil 1, the induced voltage generated on the secondary ignition coil 2 is also much larger than the induced voltage generated on the primary ignition coil 1, thus obtaining a high induction Voltage, the high voltage generates a spark through the discharge of the spark plug 3, thereby completing the ignition.

The existing ignition coil drive circuit is controlled by an insulated gate bipolar transistor (IGBT). However, the current IGBT is often used as a common type, which does not have a current limiting function. After the current increases, the ignition coil is in a magnetized state for a long time and is easily damaged. Ignition coils. At present, there are also some smart IGBTs. Compared with ordinary IGBTs, it has the function of avoiding the damage of the ignition coil due to the excessive loading time of the ignition signal. However, because the price of the smart IGBT is too expensive, its application is limited. .

Utility model content

The purpose of the utility model is to provide an ignition coil drive circuit which is not easy to cause damage to the ignition coil in view of the disadvantage that the existing ignition coil drive circuit makes the ignition coil in a magnetized state for a long time and easily causes damage to the ignition coil.

The ignition coil drive circuit provided by the utility model includes an insulated gate bipolar transistor (IGBT), wherein the ignition coil drive circuit also includes a protection circuit, and the protection circuit includes a first triode and a voltage regulating resistor. The piezoresistor is connected in parallel between the base and the emitter of the first triode, and the emitter of the first triode is grounded, and the collector and base of the first triode are respectively connected to the IGBT The gate is connected to the source.

The ignition coil drive circuit also includes an ignition coil and a spark plug, the ignition coil includes a primary ignition coil and a secondary ignition coil coupled to each other, the spark plug is electrically connected to the secondary ignition coil, and the primary ignition coil is connected to the drain of the insulated gate bipolar transistor .

When the ignition coil driving circuit provided by the utility model works, the ignition signal is input by the gate of the IGBT. When the ignition signal is at a high level, the IGBT is turned on, so that the primary ignition coil starts to be magnetized, the current in the primary ignition coil begins to increase slowly, and the voltage across the resistor also increases with the increase of the current. When the voltage across the resistor reaches the turn-on voltage of the first transistor in the protection circuit, the first transistor is turned on, so that the voltage at the gate of the IGBT is zero, and the IGBT is turned off, so that the current in the primary ignition coil decreases, the voltage across the resistor also decreases. When the voltage across the resistor decreases to be lower than the conduction voltage of the first triode, the first triode is turned off, the IGBT is turned on, and the current in the primary ignition coil starts to increase slowly again. Therefore, the ignition coil drive circuit of the utility model can limit the current flowing through the primary ignition coil, thereby achieving the purpose of preventing the secondary secondary coil from being burned due to excessive instantaneous current changes in the primary ignition coil, and protecting The circuit is low in cost and easy to be widely used.

Description of drawings

Fig. 1 is the circuit schematic diagram of existing ignition coil driving circuit;

Fig. 2 is a schematic circuit diagram of an ignition coil drive circuit provided by an embodiment of the present invention;

3 is a schematic circuit diagram of an ignition coil drive circuit according to a first preferred embodiment of the present invention;

Fig. 4 is a schematic circuit diagram of an ignition coil driving circuit according to a second preferred embodiment of the present invention.

Detailed ways

Describe the utility model in detail below in conjunction with accompanying drawing.

Fig. 2 is a schematic circuit diagram of an ignition coil driving circuit provided by an embodiment of the present invention. As shown in Figure 2, the ignition coil drive circuit includes IGBT P1, wherein the ignition coil drive circuit also includes a protection circuit, the protection circuit includes a first triode T1 and a resistor VR1, the resistor VR1 is connected in parallel to the Between the base and the emitter of the first triode T1, and the emitter of the first triode T1 is grounded, the collector and the base of the first triode T1 are respectively connected to the gate of the IGBT P1 connected to the source. The ignition coil drive circuit also includes an ignition coil, a spark plug 3, the ignition coil includes a primary ignition coil 1 and a secondary ignition coil 2 coupled to each other, the spark plug is electrically connected to the secondary ignition coil 2, and the primary ignition coil 1 is connected to an insulated grid bipolar The drain connection of transistor P1.

The IGBT P1 and the first triode T1 form a negative feedback circuit, which achieves the purpose of limiting the magnetizing current, and the magnetizing current can be limited within a specified range by changing the resistance value of the resistor VR1.

IGBT P1 can choose BTS2140, MGP15N40CL, NGD15N41CL, etc. The first triode T1 and the resistor VR1 can be any triode and a resistor with a resistance range of 1-10Ω. For example, the first triode T1 can be a 9014 transistor, and the resistor VR1 can be a 10Ω resistor.

As shown in Figure 2, the gate of IGBT P1 is used as the ignition signal input terminal 5 to input the ignition signal. Generally speaking, the ignition signal is a 5V logic gate signal generated by the engine electronic management system (EMS). The collector of the first transistor T1 in the protection circuit is connected to the gate of the IGBT P1 (ie, the ignition signal input terminal 5), and the base of the first transistor T1 is connected to the source of the IGBT P1. In this way, when the ignition signal is at a high level, the IGBT P1 is turned on, so that the primary ignition coil 1 starts to be magnetized, the current in the primary ignition coil 1 begins to increase slowly, and the voltage at both ends of the resistor VR1 also increases with the increase of the current. big. When the voltage across the resistor VR1 reaches the turn-on voltage of the first transistor T1, the first transistor T1 is turned on, so that the voltage at the gate of the IGBT P1 is zero, and the IGBT P1 is turned off, and the primary ignition coil 1 As the current decreases, the voltage across the resistor VR1 also decreases. When the voltage across the resistor VR1 decreases below the conduction voltage of the first transistor T1, the first transistor T1 is cut off, the IGBT P1 is turned on, and the current in the primary ignition coil 1 starts to increase slowly again, and then The above process is repeated to form a cycle, thereby achieving the purpose of limiting the current in the primary ignition coil 1 .

As shown in Figure 3, it is the first preferred embodiment of the utility model, wherein the protection circuit can also include a first resistor R1, a second resistor R2, a field effect transistor M1, a second triode T2 and a working power supply 8 , the drain of the field effect transistor M1 is electrically connected to one end of the first resistor R1 and the base of the second transistor T2 respectively, the source of the field effect transistor M1 is grounded, and the collector of the second transistor T2 is respectively One end of the second resistor R2 is electrically connected to the collector of the first transistor T1, the emitter of the second transistor T2 is grounded, the other end of the first resistor (R1) is connected to the second resistor (R2) The other end is connected and both are connected with the working power supply 8 . Wherein, when working, the gate of the field effect transistor M1 is used as the ignition signal input terminal 5, and the other terminals of the first resistor R1 and the second resistor R2 are both connected to the working power supply 8, such as a 13V car battery.

The first resistor R1, the second resistor R2, the field effect transistor M1 and the second triode T2 can be any device capable of realizing the above functions, and the resistance of the first resistor R1 and the second resistor R2 can be selected as 200Ω To a resistance of 2KΩ, the second triode T2 can be selected from NPN type transistors such as 9014, 803, and the field effect transistor M1 can be selected from 1A/25V. 25V, far exceeding the rated voltage. Since M1 load resistance R1 is the most desirable, the maximum load current is no more than 100 mA, so 1A is selected, which is far greater than the rated current.

According to the first preferred embodiment, its working process is as follows: the ignition signal input from the ignition signal input terminal 5 is isolated and reversed by the field effect transistor M1, and then buffered and reversed by the second triode T2, and then the conduction of the IGBT P1 is controlled. pass and cutoff. For example, when the ignition signal is at a high level, the field effect transistor M1 is turned on, so that the potential at the node B is at a low level, and the second transistor T2 is turned off. At this time, due to the pull-up effect of the second resistor R2, the node C The potential at is high level, thereby controlling the conduction of IGBT P1. And when the ignition signal is at low level, the field effect transistor M1 is cut off. At this time, due to the pull-up effect of the first resistor R1, the potential at node B is at high level, and the second transistor T2 is turned on. The potential of is low, thereby controlling the IGBT P1 to be cut off.

Because when the primary ignition coil 1 is magnetized, the voltage on the primary ignition coil 1 reaches hundreds of volts, while the voltage on the secondary ignition coil 2 reaches several thousand volts, the high-voltage rear-stage circuit may damage the front-stage circuit The ignition signal, so the buffering effect of the FET M1 can protect the ignition signal well.

As shown in Figure 4, it is the second preferred embodiment of the present utility model. Since the voltage at the gate of IGBT P1 may be large enough to damage IGBT P1 when the second triode T2 is in the cut-off state, therefore, preferably, as shown in Figure 4, the ignition coil protection provided by the utility model The circuit further includes a third resistor R3, which is connected in parallel between the collector and the emitter of the first triode T1. The third resistor R3 is a voltage dividing resistor of the gate of the IGBT P1, and its function is to reduce the control voltage at the gate of the first triode T1, so as to prevent the IGBT P1 from being damaged due to excessive voltage.

Since the level of the ignition signal may sometimes be insufficient to turn on the field effect transistor M1, in order to improve the stability of the ignition signal, preferably, the protection circuit further includes a fourth resistor R4, one end of the fourth resistor R4 is connected to the field The gate of the effect transistor M1 is electrically connected. In specific use, the other end of the fourth resistor R4 is electrically connected to the working power source 8, and the function of the fourth resistor R4 is to increase the potential of the ignition signal. When the ignition signal is low level, the fourth resistor R4 is directly connected to the ground, and the potential at the base point A is zero. When the ignition signal is not zero, it may be in an unstable state that is not enough to turn on the field effect transistor M1 , the fourth resistor R4 forms a path with the circuit that generates the ignition signal, so that the fourth resistor R4 ensures that the potential at the base point A is a fixed high level.

By using the ignition coil protection circuit provided by the utility model, the magnetizing current of the primary ignition coil can be well limited, thereby avoiding damage to the secondary ignition coil due to excessive current in the primary ignition coil. Moreover, the components and devices used in the ignition coil protection circuit provided by the utility model are all common devices, which are low in cost and easy to be widely used.

Claims (7)

1, a kind of spark coil drive circuit; this spark coil drive circuit comprises insulated gate bipolar transistor (P1); it is characterized in that; this spark coil drive circuit also comprises protective circuit; described protective circuit comprises first triode (T1) and regulating resistor (VR1); described regulating resistor (VR1) is connected in parallel between the base stage and emitter of described first triode (T1); and the grounded-emitter connection of this first triode (T1), the collector electrode of this first triode (T1) links to each other with source electrode with the grid of described insulated gate bipolar transistor (P1) respectively with base stage.

2; spark coil drive circuit according to claim 1; it is characterized in that; described protective circuit also comprises first resistance (R1); second resistance (R2); field effect transistor (M1) and second triode (T2); the drain electrode of described field effect transistor (M1) is electrically connected with an end of first resistance (R1) and the base stage of second triode (T2) respectively; the source ground of field effect transistor (M1); the collector electrode of second triode (T2) is electrically connected with an end of described second resistance (R2) and the collector electrode of described first triode (T1) respectively; the other end of first resistance (R1) is connected with the other end of second resistance (R2), the grounded-emitter connection of second triode (T2).

3, spark coil drive circuit according to claim 2 is characterized in that, described protective circuit also comprises working power (8), is connected with the other end of first resistance (R1) and the other end of second resistance (R2).

4, spark coil drive circuit according to claim 2 is characterized in that, described protective circuit also comprises the 3rd resistance (R3), and the 3rd resistance (R3) is connected in parallel between the collector and emitter of described first triode (T1).

5, according to the described spark coil drive circuit of each claim among the claim 2-4; it is characterized in that; described protective circuit also comprises the 4th resistance (R4); one end of the 4th resistance (R4) is electrically connected with the grid of field effect transistor (M1), and the other end of the 4th resistance (R4) is connected with the other end of first resistance (R1) with second resistance (R2).

6, spark coil drive circuit according to claim 5, it is characterized in that, this spark coil drive circuit also comprises spark coil, spark plug (3), spark coil comprises that the primary ignition coil (1) of mutual coupling and secondary spark coil (2), spark plug (3) are electrically connected with secondary spark coil (2), and primary ignition coil (1) is connected with the drain electrode of insulated gate bipolar transistor (P1).

7, according to each described spark coil drive circuit among the claim 1-4, it is characterized in that, this spark coil drive circuit also comprises spark coil, spark plug (3), spark coil comprises that the primary ignition coil (1) of mutual coupling and secondary spark coil (2), spark plug (3) are electrically connected with secondary spark coil (2), and primary ignition coil (1) is connected with the drain electrode of insulated gate bipolar transistor (P1).

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