JPH0884439A - Output power control device for vehicle alternator - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a highly reliable output power control device for a vehicle alternator, which can achieve both low withstand voltage design of a regulator and improvement of exciting current. [Structure and effect] Since the switching transistor 201 for controlling the field current of the regulator (the output power control device for the vehicle alternator) is composed of a high-side switch, the field coil is excellent in reliability and the high-side switch. Since 201 is directly fed with power from the AC generator 1, the generated voltage can be applied to the field coil without a voltage drop due to wiring resistance, and the output can be increased by increasing the field current. Since the control circuit section 7 of the regulator is supplied with power from the battery 6 through the ignition switch 4 and the power supply terminal IG, when a load dump occurs, the high voltage applied to the control circuit section 7 becomes small. Control circuit section 7
Since the transistor 203 in the front circuit stage that transmits the control signal output from the high side switch 201 is fed from the AC generator 1, the high side switch 201 can be stably driven.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an output power control device for a vehicle alternator.

[0002]

2. Description of the Related Art A high-side regulator using a high-side switch made up of a PNP transistor has been proposed as a switching transistor for connecting and disconnecting a field current. For example, Japanese Patent Laid-Open No. 55-10831 and Japanese Utility Model Laid-Open No. 54-178041 disclose a power supply method in which a power supply terminal of an output power control device (hereinafter, also referred to as a regulator) feeds an ignition switch from a battery (hereinafter, referred to as a power supply system).
In the regulator of the IG excitation type), it is disclosed that the switching transistor is composed of a high side switch composed of a PNP bipolar transistor.

FIG. 3 shows a PNP bipolar transistor 8
An example of the IG excitation high side switch type regulator 8 using 01 as a switching transistor is shown. On the other hand, Japanese Patent Publication No. 39-1626 and Japanese Utility Model Publication No. 54-124.
139 and JP-A-57-145541,
In the regulator of the power feeding system (hereinafter, referred to as B direct excitation system) in which the power supply terminal of the regulator is fed from the DC output terminal of the AC generator, the switching transistor is set to P
Disclosed is a high-side switch including an NP bipolar transistor.

FIG. 4 shows a PNP bipolar transistor 9
An example of the B direct excitation high side switch type regulator 9 using 01 as a switching transistor is shown.
The high-side switch using the PNP bipolar transistor has an excellent reliability because one end of the exciting coil can be grounded and the other end can be cut off from the power supply line by this high-side switch.

The above-mentioned IG excitation high-side switch type regulator has a vehicle electric load even when an accident (hereinafter referred to as a load dump) occurs in which the battery is disconnected from the power supply line and the generated energy is released from the stator coil to the power supply line. Since the (electrical load that is normally used in the vehicle such as an ignition load) absorbs the generated energy released to the power supply line, the voltage of the power supply line does not become a high voltage such as a no-load saturation voltage. It has the advantage that it does not need to be designed to have such a high breakdown voltage.

Compared to the IG excitation high side switch type regulator, the B direct excitation high side switch type regulator has a power generation voltage of the AC generator as a power source voltage of the regulator (usually arranged in the vicinity of the AC generator). Since the voltage is directly used, the voltage increases, and at the same time, the voltage drop due to the wiring resistance can be reduced, and the field current can be enhanced.

[0007]

However, in the above-mentioned IG excitation high side switch type regulator, B
Contrary to the direct excitation method, there is a drawback in that the power supply voltage supplied to the regulator is reduced due to various losses, and the excitation current and thus the generated current are reduced accordingly.

On the contrary, in the B direct excitation high side switch type regulator, the regulator is directly fed with power from the generator, which is contrary to the IG excitation system, so that the power feed line is disconnected from the DC output end of the AC generator and the load is applied. When a dump occurs, there is a problem that a no-load saturation voltage is applied to the regulator, and therefore, there is a problem that the entire regulator must be designed to have a high breakdown voltage.

The present invention has been made in view of the above problems, and provides a highly reliable output power control device for an alternator for a vehicle, which can achieve both a low withstand voltage design of a regulator and an improvement in exciting current. The purpose is to do.

[0010]

The first configuration of the output power control apparatus for a vehicle AC generator of the present invention is a PNP bipolar transistor or PMOS whose high end is connected to the DC output terminal of the vehicle AC generator. A switching transistor, which is composed of a high-side switch composed of a transistor and intermittently controls a current passing through a field winding of the AC generator, and a switching transistor which is supplied with power from a DC output end of the vehicle AC generator. And a voltage control circuit section that is supplied with power through an ignition switch to intermittently control a transistor of the front circuit stage.

According to a second structure of the present invention, in addition to the first structure, the withstand voltage of each transistor constituting the voltage control circuit section is smaller than the withstand voltage of the high side switch and the transistor of the front circuit stage. It is characterized by being set. A third configuration of the present invention is further characterized in that, in the first configuration, the breakdown voltage of the transistor of the front circuit stage is set to be equal to or larger than the breakdown voltage of the switching transistor.

[0012]

According to the first structure of the present invention,
Regulator (output power control device for vehicle alternator)
Since the switching transistor for controlling the field current of is composed of a high-side switch, the field coil has excellent reliability, and this high-side switch is directly connected from the alternator.
Since power is supplied, the generated voltage can be applied to the field coil without a voltage drop due to wiring resistance, and the output can be increased by increasing the field current. On the other hand, the voltage control circuit part of the regulator that creates the control signal that connects and disconnects the high side switch is powered through the ignition switch that is far from the DC output end of the AC generator, so by any chance the battery may be disconnected from the power supply line and loaded. High voltage applied to this voltage control circuit when a dump occurs (hereinafter,
Since the load dump voltage) is small and each element of the voltage control circuit unit can be designed to have a low withstand voltage, high integration can be achieved and the circuit cost can be reduced.

Further, the front circuit stage for transmitting the control signal output from the voltage control circuit section to the high side switch (switching transistor) is fed from the AC generator like the high side switch, so that the emitter is grounded. P
NP bipolar transistor or source grounded PMOS
A switching transistor including a transistor can be stably driven. That is, when power is supplied to the front circuit stage through the ignition switch, if the power supply voltage of the front circuit stage is lower than the power generation voltage applied to the emitter or source of the high side switch by the power supply through the ignition switch, There is a possibility that the base or gate becomes sufficiently lower than the emitter or source, and the high side switch is constantly turned on.

Therefore, according to the first configuration, although the most of the regulator can be designed with high reliability and low withstand voltage, the excellent output of the generator can be realized. Can be played.
According to the second configuration of the present invention, since each transistor of the voltage control circuit unit is set to be smaller than the withstand voltage of the high side switch and the transistor of the front circuit stage, the control circuit unit can be easily manufactured, and high integration and Cost reduction can be realized.

According to the third configuration of the present invention, in the above first configuration, the breakdown voltage of the transistor in the front circuit stage is set to be equal to or larger than the breakdown voltage of the switching transistor. Can be prevented from being destroyed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the output power control apparatus for a vehicle AC generator according to the present invention will be described below with reference to FIG. 1 is
The vehicle AC generator includes armature windings 101 to 103, a field winding 104, and diodes 105 to 110 for full-wave rectifying an AC output to convert it into a DC output.
Reference numeral 2 is a voltage control device for controlling the output voltage of the vehicle alternator to a predetermined voltage. 3 is a charging line, 4 is an ignition switch, 51 and 52 are fuses, and 6 is a battery. B is a generator output terminal, F is a field terminal, E is a ground terminal, and IG is a power terminal.

The charging line 3 is a generator output terminal B and a battery 6
In order to supply a battery charging current and a load current to a vehicle electric load (not shown), a wire having a relatively large current capacity (for example, 5 mm ² ) is used. The ignition switch 4 and the fuse 51 are connected in series and connect between the battery 6 and the power supply terminal IG.
One end of the field winding 104 of the vehicle alternator 1 is connected to the field terminal F, the other end is connected to the ground terminal E, and the ignition switch 4 is OFF and the voltage control device 2 is not operating. , The field winding 104 is at ground potential, that is, 0V
It is configured to be

The following are components of the voltage control device 2.
Reference numeral 201 denotes a field current control transistor (a switching transistor in the present invention), which is the vehicle AC generator 1
Is connected between the generator output terminal B and the field terminal F, and the generator output voltage is maintained at a predetermined value by intermittently controlling the field current flowing through the field winding 104. The field current control transistor 201 is a PNP type transistor or a P channel type field effect transistor. 20
A field current return diode 2 is connected in parallel to the field winding 104.

203 is a field current control transistor 201.
Is a base driving transistor for intermittently controlling the base current of, and constitutes the pre-circuit stage in the present invention together with the resistors 210 and 204. The breakdown voltage of the base drive transistor 203 is equal to or higher than the breakdown voltage of the field current control transistor 201. Reference numeral 204 denotes a base resistor, which is connected between the base of the field current control transistor 201 and the collector of the base drive transistor 203. Since the field current is intermittently controlled by the two-stage amplification configuration as described above, the field current control transistor 20
No. 1 does not have to be a Darlington connection transistor, and using a single transistor has the effect of reducing the ON voltage and the effect of increasing the field current flowing in the field winding 104, that is, the advantage of highly excited magnetization.

That is, in this embodiment, the field current control transistor 201 composed of the grounded emitter PNP bipolar transistor is controlled by the front circuit stage of the inverter circuit configuration having a single and high breakdown voltage grounded NPN bipolar transistor. Since it is configured, the transistor 201 need not be of the Darlington connection type.

Reference numerals 205 and 206 denote transistors 210 to 210.
216 is a resistor, 220 to 223 are Zener diodes, 2
30 is a comparator. Reference numeral 7 denotes a voltage control circuit unit, which is included in the voltage control device 2 and includes a field current control transistor 201, a field current return diode 202, a base drive transistor 203, a base resistor 204, and resistors 210, 212, and 2.
A transistor 20 including elements other than 16 and having a relatively low breakdown voltage as compared with the field current control transistor 201.
It is composed of an integrated circuit including 5, 206.

Zener diodes (to be exact, constant voltage diodes) 220 to 223 are short-circuited between the collector and base of the transistor, and the zener voltage is usually about 5 to 7V. Zener diode 220-
222 is the collector of the transistor 205 and the ground terminal E
And a zener diode 223 connected in series between
Is connected between the internal power supply line HL supplied from the power supply terminal IG through the resistor 216 and the ground terminal E to make the internal power supply line HL a constant voltage. The comparator 230 has a non-inverting input (+) terminal, an inverting input (-) terminal, a + power supply terminal,
It has a power supply terminal and an output terminal, and outputs a Hi signal from the output terminal when the non-inverting input (+) terminal exceeds the inverting input (-) terminal. The + power supply terminal is connected to a constant voltage internal power supply line HL, and the − power supply terminal is connected to a ground terminal E. The resistors 210 and 211 are leak compensation resistors connected between the base and emitter of the field current control transistor 201 and the base drive transistor 203, respectively. The resistor 212 is the base resistor of the base driving transistor 203, the resistor 213 is the base resistor of the transistor 205, and the resistors 214 and 215 divide the voltage of the generator output terminal B and input it to the non-inverting input (+) terminal of the comparator 230. And a resistor 216 is a voltage dividing resistor for the internal power supply line H clamped by the Zener diode 221.
It is a load resistance connected between L and the power supply terminal IG.

The operation of the voltage controller having the above structure will be described below. Hereinafter, it is assumed that the charging line 3 is disconnected while the vehicle alternator 1 generates power to charge the battery 6 and supplies current to the vehicle electric load (not shown).
At this time, if the position where the charging line 3 is deviated is the generator output terminal B, the current supplied to the battery 6 and the electric load of the vehicle until just before deviating is 0 A, while flowing in the field winding 104. The field current does not immediately become 0 A, and a transient high voltage, a no-load saturation voltage, is generated at the generator output terminal B due to the power generation mechanism.

As shown in FIG. 2, the output voltage control device 2 controls the field current control transistor 2 by the Hi level output operation of the comparator 230 as the voltage at the generator output terminal B rapidly increases.
Since it operates so as to shut off 01,
1 turns off at the same time when the above no-load saturation voltage occurs,
The field current is gradually attenuated while flowing through the field current return diode, so that the no-load saturation voltage is also gradually reduced to a peak V _BP immediately after the charging line 3 is disconnected.

The above is the mechanism for generating the load dump, but the field current control transistor 201 needs to be in the OFF state during the generation of the load dump, and it is desirable not to break down. In the case of breakdown, the field current may not be attenuated but may be eventually destroyed by the positive feedback. In this embodiment, the setting of the withstand voltage of the base drive transistor 203 that drives the base current of the field current control transistor 201 is performed as follows. That is, the base drive transistor 20
In No. 3, in order to turn off the field current control transistor 201, it is necessary to be OFF and not break down. Therefore, the base drive transistor 203 has a withstand voltage that does not break down at the maximum voltage V _BP while the load dump occurs.

Here, regarding the relationship between the transistor breakdown voltage and the load dump peak voltage V _BP so that the transistor does not break down at the maximum voltage V _BP , the breakdown voltage of the field current control transistor 201 is as follows.

[0027]

## EQU1 ## V _BP + V _F (202) <the breakdown voltage of the field current control transistor 201. However, V _F (202) is the forward voltage of the field current return diode 202. Regarding the withstand voltage of the base drive transistor 203,

[0028]

[Formula 2] V _BP −V _BE (201) <the withstand voltage of the base drive transistor 203. However, V _BE (201) is the base-emitter voltage of the field current control transistor 201. At this time, V _F (202) and V _BE (201) are 1
Since it is about V and sufficiently smaller than the maximum voltage V _BP ,

[0029]

## EQU00003 ## V _BP <breakdown voltage of field current control transistor 201 V _BP ≤ breakdown voltage of base drive transistor 203 That is, the condition is that the field current control transistor 201 is neither turned on nor broken down at the maximum voltage V _BP . Next, the magnitude relationship between the breakdown voltage of the field current control transistor 201 and the breakdown voltage of the base drive transistor 203 will be considered. There is no problem if the breakdown voltages of the field current control transistor 201 and the base drive transistor 203 are set to be at least equal, but preferably the base drive transistor 2
The breakdown current of the field current control transistor 201 itself is smaller than that of the field current control transistor 201 which is turned on by the breakdown of 03. Therefore, it is more preferable to set the withstand voltage of the base drive transistor 203 larger than the withstand voltage of the field current control transistor 201. As an example, when the load dump peak voltage V _BP is about 150 V, the breakdown voltage of the field current control transistor 201 is 2 in consideration of manufacturing variations.
Set to about 00V, and further base drive transistor 2
The breakdown voltage of 03 is also set to about 200V, preferably about 250V.

On the other hand, since the current control circuit section 7 is formed of an integrated circuit having a low breakdown voltage, it is difficult to form the above-mentioned base drive transistor 203 by an integrated circuit. This is because an integrated circuit usually has a low breakdown voltage for the purpose of high integration, so if the breakdown voltage is to be increased, it is necessary to reduce the degree of integration and drastically change the manufacturing process. That is, it is preferable as a whole that the base driving transistor 203 is a single high breakdown voltage transistor and is separated and independent from the integrated element.

Further, when the field current control transistor 201 is a PNP type single transistor, the base current thereof exceeds 100 mA, which is one of the reasons why the base drive transistor 203 is made into a single unit. Next, the operation of the voltage control circuit unit 7 when a load dump occurs will be described. In order to keep the voltage of the generator output terminal B at a predetermined value, the comparator 230 that compares the voltage of the generator output terminal B with the potential dividing point by the voltage dividing resistors 214 and 215 and the reference voltage Vr is
It is detected that the potential of the voltage dividing point exceeds the reference voltage Vr due to the generation of the load dump, and the Hi signal is sent to the transistor 206.
Input to the base of and turn it on. This turns off the transistor 205, the base drive transistor 203, and the field current control transistor 201.

The position where the charging line 3 is disconnected is the generator output terminal B.
In the case of, since the load dump voltage is not applied to the power supply terminal IG, when the transistor 205 is turned off, the collector of the transistor 205 from the battery 6 is connected through the IG terminal.
The maximum voltage applied between the emitters is at most 12-15
Since it is V, the base current of the base drive transistor 203 is cut off without breaking down even if a load dump occurs.

However, when the position where the charging wire 3 is disconnected is close to the + terminal of the battery 6, that is, the fuse 5
In the case of fusing of 2 or the like, the collector of the transistor 205 is connected through the charging line 3, the fuse 51, the ignition switch 4, the power supply terminal IG, and the resistor 212, while the emitter is connected through the ground terminal E and the resistor 211. A load dump voltage is applied between the emitters. When the applied voltage in this case exceeds the withstand voltage of the transistor 205, breakdown occurs and the base drive transistor 203
Therefore, the zener diodes 220 to 220 having a zener voltage of about 5 to 7 V are connected in series so that the transistor 205 can be clamped at a voltage lower than the breakdown voltage because the base current is supplied to the transistor 205 to turn it on. Connected in parallel between the collector of the transistor 205 and the ground terminal E, and the Zener diode 22 is connected before breakdown.
Causes 0-220 to bypass current.

37 Zener diodes 220 to 22
The voltage that can be clamped at 2 is the normal operating voltage (12-14
Since it is set higher than V), it is not normally broken down. As a result, even if a load dump voltage is applied to the power supply terminal IG, the field current control transistor 201
Can be reliably turned off.

The operational effects of the above embodiment will be summarized and described below. As described above, in the output power control device for the vehicle alternator having the field coil whose one end is grounded, is the withstand voltage of the base drive transistor for driving the base current of the field current control transistor equal to that of the latter stage transistor? By making it more than that, it is possible to realize a high-side switch type regulator capable of withstanding a load dump.

By using a PNP single transistor as the field current control transistor 201,
Since the potential of the field coil 104 when the field current is interrupted is set to the ground potential, its reliability can be confirmed against electrolytic corrosion / corrosion when exposed to water, and the power is directly supplied from the B terminal. The advantage of so-called highly excited magnetization that increases the current can be obtained.

Further, the voltage control circuit section 7 has a lower breakdown voltage than the field current control transistor 201, and even if high integration is achieved, the base drive transistor 20 is generated when a load dump occurs.
3 can be reliably turned off to prevent damage to the load dump. (Other Embodiments) When a P channel type field effect transistor is used as the field current control transistor 201, the same operation and effect as the above embodiment can be obtained. Further, at this time, the base driving transistor 203 and the base resistor 204 require a smaller current than that of the PNP bipolar transistor, so that the current driving capability and the current capacity can be reduced. This also has the advantage that heat generation at the base resistance can be reduced.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an output power control device for an automotive alternator according to the present invention.

FIG. 2 is a timing chart showing changes with time of a generated voltage V _B and a field current when the charging line is disconnected in the output power control device for the vehicle AC generator of FIG.

FIG. 3 is a circuit diagram of a conventional output power control device for a vehicle AC generator.

FIG. 4 is a circuit diagram of a conventional output power control device for a vehicle AC generator.

[Explanation of Codes] 1 is an AC generator for vehicle, 201 is a field current control transistor (switching transistor), resistors 210, 20
4 and transistor 203 are front-end circuit stages, and 7 is a voltage control circuit section.

Claims (3)

[Claims] 1. A PNP bipolar transistor or PMOS whose high end is connected to a direct current output end of an automotive alternator.
A switching transistor configured by a high-side switch made of a transistor to intermittently control a current passing through a field winding of the AC generator, and a switching transistor supplied with power from a DC output end of the vehicle AC generator to control the switching transistor. An output power control device for a vehicular alternator, comprising: a front circuit stage for controlling the voltage of the vehicle; and a voltage control circuit section that is supplied with electric power through an ignition switch to intermittently control a transistor of the front circuit stage. 2. The output power of the vehicle alternator according to claim 1, wherein the breakdown voltage of each transistor constituting the control circuit unit is set to be smaller than the breakdown voltage of the transistors of the high side switch and the front circuit stage. Control device. 3. The breakdown voltage of the transistor of the front circuit stage is
The output power control device for an automotive alternator according to claim 1, wherein the withstand voltage of the switching transistor is set to be equal to or greater than the withstand voltage.