JP3454382B2 - Output power control device for vehicle alternator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an output power control device for an automotive alternator. 2. Description of the Related Art A high-side regulator using a high-side switch composed of a PNP transistor has been proposed as a switching transistor for interrupting a field current. For example, JP-A-55-10831 and JP-A-54-178041 disclose a power supply system (hereinafter, referred to as a regulator) in which a power supply terminal of an output power control device (hereinafter also referred to as a regulator) is supplied with an ignition switch from a battery.
In a regulator of the IG excitation type, the switching transistor is constituted by a high side switch composed of a PNP bipolar transistor. FIG. 3 shows a PNP bipolar transistor 8.
An example of an 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 a regulator of a power supply system (hereinafter referred to as a B direct excitation system) in which a power terminal of the regulator is supplied from a DC output terminal of an AC generator, a switching transistor is connected to
It discloses that it is constituted by a high-side switch composed of an NP bipolar transistor. FIG. 4 shows a PNP bipolar transistor 9.
An example of a 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 advantage of high 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 the high-side switch. The IG-excited high-side switch-type regulator is capable of controlling the vehicle electric load even when an accident (hereinafter referred to as 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. (Electrical load for vehicle use such as ignition load) absorbs the generated energy released to the power supply line, so that the voltage of the power supply line does not become a high voltage like no-load saturation voltage. There is an advantage that it is not necessary to design so high withstand voltage. The B-direct-excitation high-side switch type regulator is different from the IG-excitation high-side switch type regulator in that the power supply voltage of the AC generator (generally arranged near the AC generator) Is directly used, the voltage is increased, and at the same time, the voltage drop due to the wiring resistance can be reduced, and the field current can be enhanced. However, in the above-mentioned IG excitation high-side switch type regulator, B
Contrary to the direct excitation method, there is a disadvantage that the power supply voltage supplied to the regulator is reduced due to various losses, and the excitation current and, consequently, the generated current are reduced accordingly. Conversely, in the B-direct-excitation high-side switch type regulator, contrary to the IG excitation method, the regulator is directly supplied with power from the generator. 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 withstand voltage. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a highly reliable output power control device for an automotive alternator that can achieve both low voltage design of a regulator and improvement of an exciting current. Its purpose is to do. [0010] Means for Solving the Problems] output power control equipment for a vehicle alternator of the present invention, PNP bipolar transistor or a PMOS transistor high end connected to DC output ends of the vehicle AC generator A switching transistor configured to intermittently control a current flowing through a field winding of the AC generator, and a switching transistor that is supplied with power from a DC output terminal of the vehicle AC generator and controls the switching transistor. Pre-stage and battery
Output power control apparatus smell of the automotive alternator and a voltage control circuit for intermittently controlling the transistors of the front end circuit stages are powered more through the ignition switch
The voltage control circuit (7) operates as an emitter follower.
To drive and control the transistors in the preceding circuit stage.
Transistor (205) and the transistor (205).
The transistor (205) breaks the collector potential
Clamp that clamps at a lower voltage than the voltage that goes down
And a circuit (220), and constitutes the voltage control circuit section.
The breakdown voltage of each transistor (eg, 205)
Switching transistor (201) and said pre-circuit stage
Is set smaller than the withstand voltage of the transistor (203),
The breakdown voltage (203) of the transistor in the preceding circuit stage is
Is it equivalent to the withstand voltage of the switching transistor (201)?
It is characterized in that it is set larger . [0011] According to the present onset light Effect of the action and the present invention, field the regulator switching transistor for field current control (output power control apparatus for a vehicle alternator) consists of high-side switch In addition to the high reliability of the magnetic coil, this high-side switch is fed directly from the AC generator, so that the generated voltage can be applied to the field coil without voltage drop due to wiring resistance, and the output is increased by increasing the field current Can be increased. On the other hand, the voltage control circuit section of the regulator that creates a control signal for intermittently turning on the high-side switch is:
Since the power is supplied through an ignition switch remote from the DC output terminal of the AC generator, a high voltage (hereinafter referred to as a load dump) applied to the voltage control circuit unit should the battery fall out of the power supply line and a load dump should occur. Voltage), and each element of the voltage control circuit can be designed to have a low withstand voltage, so that high integration can be achieved and circuit cost can be reduced. Further, since the preceding circuit stage for transmitting the control signal output from the voltage control circuit section to the high-side switch (switching transistor) is supplied with power from the AC generator in the same manner as the high-side switch, the emitter is grounded. P
NP bipolar transistor or grounded source PMOS
The switching transistor including the transistor can be driven stably. 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, the high side switch of the high side switch is turned off. The base or gate becomes sufficiently lower than the emitter or source, and there is a possibility that the high side switch is always turned on. Therefore, according to the present invention , there is an excellent effect that the output of the generator can be improved despite the fact that most of the regulator can be designed with high reliability and low withstand voltage. Can be. In addition , since each transistor of the voltage control circuit is set to be smaller than the withstand voltage of the high-side switch and the transistor in the preceding circuit stage, manufacture of the control circuit is easy, and high integration and low cost are achieved. Can be realized. Further , since the withstand voltage of the transistor in the preceding circuit stage is set to be equal to or larger than the withstand voltage of the switching transistor, it is possible to prevent the switching transistor from being destroyed when a load dump is applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an output power control apparatus for a vehicle AC generator according to the present invention will be described below with reference to FIG. 1 is
It is an AC generator for vehicles, and comprises armature windings 101 to 103, field windings 104, and diodes 105 to 110 for full-wave rectification of AC output and conversion to DC output.
Reference numeral 2 denotes a voltage control device for controlling the output voltage of the vehicle alternator to a predetermined voltage. Reference numeral 3 denotes a charging line, 4 denotes an ignition switch, 51 and 52 denote fuses, and 6 denotes a battery. B is a generator output terminal, F is a field terminal, E is a ground terminal, and IG is a power supply terminal. The charging line 3 is connected to the generator output terminal B and the 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 turned off and the voltage control device 2 is not operated. , The field winding 104 is at ground potential,
It is configured so that The components of the voltage control device 2 are as follows.
201 is a field current control transistor (switching transistor in the present invention),
Is connected between the generator output terminal B and the field terminal F, and the field current flowing through the field winding 104 is intermittently controlled to maintain the generator output voltage at a predetermined value. Note that the field current control transistor 201 is a PNP transistor or a P-channel field effect transistor. 20
Reference numeral 2 denotes a field current return diode which is connected in parallel to the field winding 104. Reference numeral 203 denotes a field current control transistor 201
A base driving transistor for intermittently controlling the base current of the present invention, and together with the resistors 210 and 204, constitutes a pre-circuit stage in the present invention. In addition, a withstand voltage of the base driving transistor 203 is selected to be equal to or higher than a withstand voltage of the field current control transistor 201. A base resistor 204 is connected between the base of the field current control transistor 201 and the collector of the base drive transistor 203. Since the intermittent control of the field current is performed in the above-described two-stage amplification configuration, the field current control transistor 20
Reference numeral 1 does not need to be a Darlington-connected transistor, and the use of a single transistor can reduce the ON voltage, and has the effect of increasing the field current flowing through the field winding 104, that is, the advantage of high excitation magnetization. That is, in the present embodiment, the control of the field current control transistor 201 composed of a common-emitter PNP bipolar transistor is controlled by a front circuit stage of an inverter circuit configuration having a single, high-withstand-voltage, common-emitter NPN bipolar transistor. With such a configuration, the transistor 201 does not need to be a Darlington connection type. 205 and 206 are transistors, 210 to
216 is a resistor, 220 to 223 are Zener diodes, 2
Reference numeral 30 denotes a comparator. Reference numeral 7 denotes a voltage control circuit, which 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,
Transistor 20 having a relatively low breakdown voltage as compared with the field current control transistor 201.
5 and 206. The Zener diodes (accurately, constant voltage diodes) 220 to 223 are short-circuited between the collector and the base of the transistor. The Zener voltage is usually about 5 to 7V. Zener diode 220 ~
222 is a collector of the transistor 205 and the ground terminal E.
And a zener diode 223
Is connected between the internal power supply line HL fed from the power supply terminal IG through the resistor 216 and the ground terminal E, and makes 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 the constant power supply internal power supply line HL, and the − power supply terminal is connected to the ground terminal E. The resistors 210 and 211 are leak compensation resistors connected between the base and the emitter of the field current control transistor 201 and the base drive transistor 203, respectively. The resistor 212 is a base resistor of the base driving transistor 203, the resistor 213 is a 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. The resistor 216 is connected to the internal power supply line H clamped by the Zener diode 221.
This is a load resistance connected between L and the power supply terminal IG. The operation of the voltage control device having the above configuration 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 supply current to a vehicle electric load (not shown).
At this time, assuming that the position where the charging line 3 is off is the generator output terminal B, the current supplied to the battery 6 and the vehicle electric load until immediately before the charging line 3 is off is 0 A, while flowing to the field winding 104. The field current does not immediately become 0 A, and a no-load saturation voltage that is a transient high voltage is generated at the generator output terminal B by the power generation mechanism. As shown in FIG. 2, the output voltage control device 2 operates in response to a sudden rise in the voltage of the generator output terminal B, and the comparator 230 outputs a Hi-level signal to operate the field current control transistor 2.
01 to shut off the transistor 20
1 turns off at the same time when the no-load saturation voltage is generated,
Field current field current reflux diode - attenuated gradually at reflux de, thereby also no-load saturation voltage decreases gradually peak V _BP immediately after charging line 3 off. The mechanism of the generation of the load dump has been described above. The field current control transistor 201 needs to be in the OFF state during the generation of the load dump, and it is preferable that the breakdown does not occur. When the breakdown occurs, the field current may not be attenuated and may be eventually destroyed by positive feedback. In this embodiment, the withstand voltage of the base drive transistor 203 for driving the base current of the field current control transistor 201 is set as follows. That is, the base driving transistor 20
No. 3 needs to be OFF and not break down in order to turn off the field current control transistor 201. Therefore, while the load dump is occurring, the base driving transistor 203 has a withstand voltage that does not break down at the maximum voltage _VBP . Here, 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 is as follows. First, the breakdown voltage of the field current control transistor 201 is given by: V _BP + V _F (202) <withstand voltage of field current control transistor 201 Here, V _F (202) is the forward voltage of the field current return diode 202. The breakdown voltage of the base driving transistor 203 is expressed as follows: V _BP −V _BE (201) <the breakdown voltage of the base driving transistor 203. Here, V _BE (201) is a base-emitter voltage of the field current control transistor 201. At this time, V _F (202) and V _BE (201) are 1
If the voltage is about V and is sufficiently small with respect to the maximum voltage V _BP, it is neglected because: V _BP <withstand voltage V _BP of the field current control transistor 201 ≦ withstand voltage of the base drive transistor 203. In other words, this is a condition for preventing the field current control transistor 201 from turning on and breaking 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 voltage of the field current control transistor 201 and the withstand voltage of the base drive transistor 203 are set at least equal to each other.
When the field current control transistor 201 breaks down, the field current to be driven is smaller than when the field current control transistor 201 is turned on by the breakdown of 03. Therefore, it is more preferable to set the withstand voltage of the base drive transistor 203 to be 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 withstand voltage of the field current control transistor 201 is 2
It is set to about 00V and the base drive transistor 2
It is preferable that the withstand voltage of the transistor 03 is set to about 200 V, preferably about 250 V. On the other hand, since the current control circuit section 7 is composed of an integrated circuit having a low withstand voltage, it is difficult to configure the base drive transistor 203 described above with an integrated circuit. This is because an integrated circuit usually has a low withstand voltage for the first purpose of high integration, and if the withstand voltage is to be increased, a reduction in the degree of integration and a significant change in the manufacturing process are required. That is, as a whole, it is preferable that the base driving transistor 203 is a single high-voltage transistor and is separated and independent from the integrated device. When the field current control transistor 201 is a single PNP transistor, its base current exceeds 100 mA, which is one of the reasons for using the base drive transistor 203 alone. Next, the operation of the voltage control circuit unit 7 when a load dump occurs will be described. In order to keep the voltage at the generator output terminal B at a predetermined value, the comparator 230 compares the voltage at the generator output terminal B with the potential at the voltage dividing point by the voltage dividing resistors 214 and 215 and the reference voltage Vr.
When it is detected that the potential at the voltage dividing point has exceeded the reference voltage Vr due to the occurrence of the load dump, the Hi signal is output to the transistor 206.
And turn it on. Thus, the transistor 205, the base driving transistor 203, and the field current control transistor 201 are turned off. The position where the charging line 3 is disconnected is the generator output terminal B
In this case, 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 through the IG terminal is turned off.
The maximum voltage applied between the emitters is at most 12-15
Since the voltage 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 line 3 is disconnected is a position near the + terminal of the battery 6, that is, when the fuse 5
2, the fuse of the transistor 205 is connected to the collector 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 to the collector through the ground terminal E and the resistor 211. A load dump voltage is applied between the emitters. If the applied voltage in this case exceeds the withstand voltage of the transistor 205, a breakdown occurs and the base driving transistor 203
Since a base current is supplied to the transistor 205 and the transistor 205 is turned on, three 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. Connected in parallel between the collector of the transistor 205 and the ground terminal E, and the Zener diode 22
The current is bypassed to 0-220. The 37 zener diodes 220 to 22
The voltage that can be clamped at 2 is the normal operating voltage (12-14
V), so that it is not normally broken down. Thus, 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 operation and effect of the above embodiment will be described below. As described above, in the output power control device of the automotive alternator having the field coil whose one end is grounded, whether the withstand voltage of the base drive transistor for driving the base current of the field current control transistor is equal to that of the subsequent transistor or not. By doing so, a high-side switch-type regulator that can withstand a load dump can be realized. By using a PNP single transistor as the field current control transistor 201,
The electric potential of the field coil 104 at the time of the interruption of the field current can be used as the earth potential to confirm the reliability of the electrolytic corrosion and corrosion at the time of being wetted. The advantage of the so-called high excitation magnetization that increases the current can be obtained. Further, the voltage control circuit section 7 has a lower withstand voltage than the field current control transistor 201, and even if high integration is to be achieved, the base drive transistor 20 is not required 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. 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. Thereby, there is also an advantage that the heat generated by the base resistor can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram of an output power control device for an automotive alternator according to the present invention. 2 is a timing chart showing the output power control device for a vehicle alternator in Figure 1 the time variation of the generated voltage V _B and the field current when the charging line out occurs. FIG. 3 is a circuit diagram of a conventional output power control device for an AC generator for a vehicle. FIG. 4 is a circuit diagram of a conventional output power control device for an AC generator for a vehicle. [Description of Signs] 1 is a vehicle alternator, 201 is a field current control transistor (switching transistor), and resistors 210 and 20
Reference numeral 4 and the transistor 203 indicate a front circuit stage, and reference numeral 7 indicates a voltage control circuit unit.

Continuation of front page (56) References JP-A-63-240336 (JP, A) JP-A-3-239129 (JP, A) JP-A-6-339299 (JP, A) (58) Fields studied (Int .Cl. ⁷ , DB name) H02J ^7/ 14-7/24 H02P 9/30

Claims (1)

(57) Claims 1. A PNP bipolar transistor or PMOS having a high-order terminal connected to a DC output terminal of a vehicle AC generator.
A switching transistor configured by a high-side switch formed of a transistor and intermittently controlling a current supplied to a field winding of the AC generator; and controlling the switching transistor by being supplied with power from a DC output terminal of the vehicle AC generator. end circuit stage and an output power control apparatus smell of the automotive alternator and a voltage control circuit for intermittently controlling the transistors of the front end circuit stages are powered through the ignition switch from the battery before
The voltage control circuit (7) operates as an emitter follower.
A transistor for driving and controlling the transistor of the preceding circuit stage;
Of the transistor (205) and the transistor (205).
The transistor (205) breaks down the
Clamp circuit that clamps at a lower voltage than
(220), and each transistor (for example,
205) is the switching transistor
(201) and the transistor (20
The withstand voltage (203) of the transistor in the preceding circuit stage is set smaller than the withstand voltage of 3).
Is it equivalent to the withstand voltage of the switching transistor (201)?
An output power control device for a vehicle alternator, which is set to be larger .