JP2002010695A - Ac generator for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an AC generator for a vehicle capable of performing a startup of power generation with a simple configuration and with high accuracy in a low-revolution range up to high, and also reducing power consumption of a bypass resistor. SOLUTION: A switching transistor 7 is controlled with an induction voltage that is induced to an exciting coil 13 by a rotation of a rotor core when the switching transistor 7 is off. Thereby, the start of power-generation in the low revolution range up to high is materialized bringing a favorable SN ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle alternator.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 6-276 filed by the present applicant.
Japanese Patent Publication No. 796 discloses a self-excited type in which a one-phase power generation voltage or a neutral point voltage of a vehicle AC generator exceeds a predetermined level, determines that power can be generated, and supplies an exciting current to an exciting coil. Has proposed a vehicle alternator.

Further, in this vehicle AC generator, in order to ensure power generation performance in a low rotation range, the first comparator without rectifying a one-phase power generation voltage which is an AC voltage output from an armature winding. To start the intermittent power generation in comparison with the small first threshold value. Thereafter, when the rotation increases and the power generation voltage increases, the one-phase power generation voltage is rectified and input to the second comparator. It also discloses that the power generation is constantly started in comparison with a second threshold value which is large, thereby improving the power generation performance in a low rotation range.

Further, Japanese Patent Application Laid-Open No. 3-215200 and
No. 503308 discloses a technique capable of detecting a signal even when a leak occurs by utilizing differential amplification of two-phase voltages of armature windings.

[0005]

However, in the above-described self-excited vehicle alternator, when a leakage current flows into the armature winding when the rotation is stopped, the voltage generated in the armature winding is reduced by the generated voltage. Erroneously detected and the excitation current flows,
There is a problem that the battery runs out easily.

The above-mentioned publication further discloses connecting a detection end of the one-phase power generation voltage and a ground end with a bypass resistor to suppress the leakage current from flowing into the armature winding, thereby preventing leakage current flowing into the armature winding. Are also disclosed. However, such additional installation of the bypass resistor has caused problems such as an increase in power loss after the start of power generation and heat generation of the bypass resistor.

Further, in the technique utilizing the differential amplification of the two-phase voltage of the armature winding, the generator structure becomes complicated in order to incorporate the two-phase output voltage signal of the armature into the voltage control device.
There is a concern about an increase in the number of assembly steps and a decrease in reliability due to an increase in the number of connection points.

The present invention has been made in view of the above-mentioned problems, and has a simple circuit configuration and can accurately start power generation from a low rotation speed range, and can also reduce the power consumption of the bypass resistor described above. Its purpose is to provide a machine.

[0009]

According to the present invention, a rotor having a plurality of magnetic poles, a field winding for magnetizing the magnetic poles, and an armature winding coaxially arranged with the rotor are wound. A vehicle comprising: an armature provided with an iron core, a rectifier for rectifying an output voltage of the armature winding and storing the rectified voltage in a vehicle-mounted power storage unit, and a voltage control device for controlling the rectified output voltage. In the alternator for use, the voltage control device includes a switching unit for intermittently exciting an exciting current supplied to the field winding, a unit for controlling the switching unit, and a unit for detecting a voltage across the field winding. The switching means is controlled in accordance with a voltage generated between both ends of the field winding by the rotation of the rotor when the switching means is in a disconnected state. AC voltage Compared with the case of controlling the switching means utilized, it can detect a signal reliably starts rotating even when a leakage current occurs.

[0010] To be further mentioned, the impedance, especially the reactance, of the field winding of a general automotive alternator is:
Since it is designed to be larger than the impedance of the armature winding as described in claim 3, the leakage current is extremely unlikely to flow unless an excessive voltage is applied, so that the signal voltage generated at both ends of the field winding is reduced. This has the effect that the noise voltage can be reliably separated and detected.

According to the second aspect, the voltage generated between both ends of the field winding due to the rotation of the rotor when the switching means is in a disconnected state is caused by the magnetic flux due to the magnetization remaining in the armature core. Since the alternating voltage is induced in the field winding by alternating rotation by the rotation of the rotor, a voltage generated in the field winding can be easily detected without requiring a special structure or circuit. You can do it.

According to a third aspect, the control device includes means for detecting a voltage value or a frequency of the voltage generated between both ends of the field winding, and the voltage value or the frequency is set to a predetermined first value. If the threshold value is exceeded, the excitation of the exciting current to the field winding is started, so that it can be realized by a simple circuit element such as a well-known comparator, and the circuit configuration can be simplified.

In a preferred embodiment, at this stage, the excitation current is supplied intermittently. In this way, even if the voltage value or frequency of the detected voltage across the field winding is a noise voltage or a false voltage, the excitation current is not interrupted and disappears with the disappearance of the noise voltage or the false voltage. Therefore, a large amount of exciting current does not continue to flow for a long time.

In a preferred embodiment, the intermittent energization of the exciting current is performed using an AC voltage induced in the field winding. In this way, a circuit for realizing intermittent energization can be simplified.

According to a fourth aspect, the control device includes means for detecting an output voltage of the generator, and the voltage value or the frequency of the voltage of the field winding is a predetermined first threshold value. In this case, the operation of controlling the output voltage of the generator to a predetermined value is started, so that the intermittent energization of the exciting current increases the effective magnetic flux linked to the armature winding as much as possible. The establishment of the voltage can be realized early.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the above-described vehicle alternator according to the present invention will be specifically described with reference to the following examples.

[0017]

Embodiment 1 An embodiment of an excitation current control device for a self-excited AC generator according to the present invention will be described with reference to FIG.

The vehicular AC generator 1 is a rundle type alternator driven by a vehicular engine and has an armature winding 11, a rectifier 12, and an exciting coil 13, and as is well known, The child winding 11 is wound around a stator core (not shown), and the exciting coil 13 is wound around a rotor core (not shown).

The power generated by each phase of the star-connected three-phase armature coil 11 is rectified by the three-phase full-wave rectifier 12, and then supplied to the battery 3 through the power line L1.
Reference numeral 13 denotes an excitation coil whose one end is grounded. The excitation coil 13 is supplied with power from the power supply line L1 through the switching transistor 7.

The exciting current control device 2 will be described below. (Function of Comparator 4) A voltage at a connection point between the transistor 7 serving as a high-side switch and the exciting coil 13 (hereinafter, referred to as an exciting coil voltage) is input to a negative input terminal of the comparator 4 through a resistor r0.
This is compared with the reference voltage V1 input to the input terminal. In this embodiment, the reference voltage V1 is 0.7 V or less, here 0.4
V.

3 and 4, the principle of generation of a voltage across the field winding of the present embodiment will be described.

FIG. 3 schematically shows a developed view of the armature and the rotating magnetic pole of the present invention at rest.

A symmetric three-phase winding U-U 'is attached to the armature core 111.
Phase, VV 'phase and WW' phase are wound at a pitch of 120 degrees in electrical angle.

It is assumed that the previous vehicle operation has been completed and the rotor is now stopped in the state shown in the figure. Field winding (not shown)
When the exciting current is flowing through the field pole 12 as shown in FIG.
1 is magnetized. Even if the exciting current is extinguished in this state, it is apparent from the magnetization curve of the soft iron that the field pole 121 and the armature core 111 remain magnetized as shown in the figure.

In this state, when the engine is started again and the rotor rotates, the field pole 121 starts rotating, and moves relative to the residual magnetization of the armature core. FIG. 4 shows a relationship between a change in magnetic flux linked to the field winding at that time and a voltage induced in the field winding due to the change in the magnetic flux.

In the field winding, a combined magnetic flux φf of a DC magnetic flux φdc due to residual magnetization of the field pole and an AC magnetic flux φac due to relative motion between the residual magnetization of the armature core and the armature is linked. The induction of an AC voltage proportional to only the time rate of change of the interlinkage magnetic flux, that is, dφf / dt is to teach electromagnetics. That is, just by rotating the rotor, such an AC voltage is generated in the field winding. As is well known, its frequency is equal to the fundamental frequency of the AC voltage normally induced in the armature winding. Hereinafter, this voltage is referred to as an excitation coil voltage.

The instantaneous value of the exciting coil voltage is +0.4 V
Is exceeded, the comparator 4 is inverted and the diode D
4. A low level is output to the transistor 6 through the resistor r1 to turn it on. Note that the standby current consumption of the comparator 4 is set to a sufficiently small value.
The input stage is pn so that it can operate at a low voltage such as V
A differential input stage consisting of a pair of p transistors is employed.

The turned-on transistor 6 is connected to the power line L
1 to the internal power supply line L2 to increase the potential.
The internal power supply line L2 turns on the pre-transistor 70 through the base current limiting resistor r2,
0 turns on the switching transistor 7. At this point, the transistor 9 is off. r4 is
This is a resistance between the base and the emitter of the transistor 7, and is a resistance for stabilizing the operation of the transistor 7.

When the switching transistor 7 is turned on, an exciting current is supplied from the power supply line L1 to the exciting coil 13, whereby the magnetic field is strengthened and the generated voltage is increased by the rotation of the rotor core. (Function of Comparator 8) When the rotation of the rotor core is low, the internal power supply line L2 supplies the power supply voltage to the comparator 8, and the + input terminal of the comparator 8 is supplied with the reference voltage V2 (here, 6V). . The output terminal of the comparator 8 is grounded via a capacitor C2, and is connected to the base electrode of a transistor 9 via r5 and a diode D1. Therefore, when the comparator 8 is activated by the supply of the power supply voltage to the comparator 8, the one-phase power generation voltage Va of the armature winding 11 is set.
Since c is small, the comparator 8 determines that the capacitor C2
After a predetermined delay time determined by the following equation, the transistor 9 with the common emitter is turned on.

The collector electrode of the transistor 9 is connected to the base electrode of the pre-transistor 70. When the transistor 9 is turned on, the pre-transistor 70 and the switching transistor 7 are turned off. When the exciting current is cut off by turning off the switching transistor 7, the current flows in the same direction through the flywheel FD in order to release the magnetic energy stored in the exciting coil 13,
As a result, the voltage at the negative input terminal of the comparator 4 becomes lower than the reference voltage V1, the comparator 4 outputs a high level, and the transistor 6 is turned off.

When the transistor 6 is turned off, the supply of the power supply voltage from the transistor 6 to the comparator 8 is cut off.
As a result, the transistor 9 is turned off.

Thereafter, when the magnetic energy stored in the exciting coil 13 is completely extinguished, the magnetization remaining in the above-mentioned armature iron core alternately penetrates the field iron core, thereby interlinking with the field winding. The AC voltage of the exciting coil to be applied is applied to the negative input terminal of the comparator 4, and when the instantaneous value of the AC voltage becomes larger than the reference voltage V1, the cycle described above is repeated again. In addition, as appropriate,
An analog delay circuit using a capacitor and a resistor is provided at a necessary place to adjust the frequency and the conductivity of this cycle.

After all, according to the circuit of FIG. 1, when the rotation of the rotor core stops and the generation of the AC voltage of the exciting coil stops, the switching transistor 7 does not turn on and the discharge of the battery can be suppressed. it can.

Next, when the one-phase power generation voltage Vac of the armature winding 11 increases due to an increase in the rotation of the rotor, the one-phase power generation voltage Vac is half-wave rectified by the diode D2 and then connected to the capacitor C1 connected in parallel with each other. And a discharge resistor r7, so that the one-phase power generation voltage V is applied to the capacitor C1.
The rectified voltage Vc of ac is accumulated.

As the rotation increases, the rectified voltage V
When c becomes higher than the reference voltage V2 (6V), the comparator 8 always outputs a low level, and the transistor 6 is turned on via the diode D5 and the transistor 9 is not turned off.

As a result, after the rectified voltage Vc exceeds the reference voltage V2, the transistor 9 is turned off and the switching transistors 7 and 70 are not turned off, and the conduction rate 10
At 0%, an exciting current is supplied to the exciting coil 13.

If the potential of the external power supply line L1 becomes excessive due to an excessive rotation of the rotor, the Zener diode D3 is turned on through the resistor r3, the transistor 9 is turned on, the transistors 7, 70 are turned off, and the exciting current is reduced. It is cut off and the generated voltage is prevented from becoming excessive.

When the rotation of the generator 1 is reduced and the rectified voltage of the one-phase generated voltage Vac falls below the reference voltage V2, after a predetermined time set by the capacitor C1 and the discharge resistor r7, the comparator 8 A high level is output to perform the intermittent control at the predetermined conductivity.

Thereafter, when the stored energy of the capacitor C1 is discharged through the discharge resistor r7 and the rectified voltage Vc becomes lower than the reference voltage V2, the comparator 8 turns on the transistor 9, and the transistor 9 turns off the transistors 7, 70. The exciting current is cut off, and the initial state is restored.

As described above, by supplying the exciting current after the vehicle alternator is stopped, the residual magnetic flux of the magnetic circuit linked to the exciting coil 13 of the vehicle alternator increases. When the rotation of the
Is increased, and the detection sensitivity can be improved.

Further, in this embodiment, the action of cutting off the exciting current and the action of rectifying the one-phase generated voltage Vac are constituted by a capacitor C1, a resistor r7 and a diode D2 which are common smoothing circuits. The circuit configuration can be simplified.

[0042]

Embodiment 2 Another embodiment of the automotive alternator according to the present invention will be described below with reference to FIG.

This embodiment differs from the first embodiment in that the switching transistor 7 and the resistor r4 are omitted, and the exciting coil 13 and the flywheel diode FD are arranged between the collector of the transistor 70 and the external power supply line L1. .

However, in this case, when the generator 1 is stopped, a high-level potential is always applied to the negative input terminal of the comparator 4 through the exciting coil 13, so that the series capacitor C1 is interposed and cut off. Further, in order to prevent the-input terminal potential of the comparator 4 from floating, the-input terminal of the comparator 4 is grounded through a resistor r8.

According to this embodiment, the same functions and effects as those of the first embodiment can be obtained.

In both of the above embodiments, the resistor r10 grounding the point P is used to bypass the leakage current flowing into the line L3 and to prevent the leakage current from flowing into the armature winding 11. Things.

Further, in the above-described embodiment, the example in which the excitation current is started to be supplied based on the voltage value of the AC voltage induced in the exciting coil 13 by the rotation of the rotor through which the residual magnetic flux flows has been described. Obviously, it is possible to process the frequency to start energizing the same exciting current,
Description is omitted. For example, the AC voltage may be subjected to fV conversion, and the obtained frequency proportional voltage value may be compared with a predetermined reference value to determine the power generation start timing. (Modification) A modification is shown in FIG.

In FIG. 2, instead of the capacitor C1, the comparator 4 may be provided with an offset corresponding to the reference voltage V1, and the voltage generated at the exciting coil 13 may be detected by detecting the voltage across the exciting coil 13. .

(Additional Effect) In both of the above embodiments, the power generation voltage of the generator 1 is quickly increased by the initial power supply command of the excitation current by the comparator 4, and based on the increased one-phase power generation voltage Vac, the power supply for constant power supply is provided. Since the determination by the comparator is performed, the determination of the constant energization by the comparator can be accelerated, and the start of power generation can be promoted.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing Embodiment 1 of an automotive alternator according to the present invention.

FIG. 2 is a circuit diagram showing Embodiment 2 of the automotive alternator according to the present invention.

FIG. 3 is a schematic diagram showing a state of magnetization when the rotation of the vehicle alternator is stopped.

FIG. 4 is a schematic diagram showing a state of voltage generation induced in a field winding.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Generator 2 Excitation current control device (control part) 4 Comparator (Initial power generation start command means) 7 Switching transistor 8 Comparator (Full-scale power generation start command means) 11 Armature winding 12 Rectifier 13 Excitation coil

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Makoto Taniguchi 1-1-1 Showa-cho, Kariya-shi, Aichi F-term in DENSO Corporation (reference) 5G060 AA03 CA03 DA01 DB01 DB03 5H590 AA02 AA21 AA22 AA30 CA07 CA23 CC01 CC18 CD01 CE05 DD25 DD64 EA01 EB02 FA06 FA08 FB01 FC12 GA02 GB01 HA02 JB07 JB09

Claims (4)

[Claims] An armature including a rotor having a plurality of magnetic poles, a field winding for magnetizing the magnetic poles, an iron core arranged coaxially with the rotor and having an armature winding wound thereon; A vehicle AC generator including a rectifier that rectifies the output voltage of the slave winding and stores the rectified output voltage in the on-vehicle power storage unit, and a voltage controller that controls the rectified output voltage. A switching means for interrupting an exciting current supplied to the field winding; a means for controlling the switching means; and a means for detecting a voltage across the field winding. Wherein the switching means is controlled in accordance with a voltage generated between both ends of the field winding by rotation of the rotor. 2. A voltage generated between both ends of the field winding due to rotation of the rotor when the switching means is in a disconnected state, is caused by a magnetic flux generated by magnetization remaining in the armature iron core rotating the rotor. 2. The vehicle alternator according to claim 1, wherein the AC voltage is an alternating voltage induced by alternately interlinking the field winding. 3. The control device includes means for detecting a voltage value or a frequency of the voltage generated between both ends of the field winding, wherein the voltage value or the frequency is equal to a predetermined first threshold value. The alternator for a vehicle according to claim 1 or 2, wherein the excitation of the exciting current to the field winding is started in a case where the current is exceeded. 4. The control device further comprises means for detecting an output voltage of the generator, wherein when a voltage value or frequency of the voltage of the field winding exceeds a predetermined first threshold value, The alternator for a vehicle according to claim 5, wherein an operation of controlling the output voltage of the generator to a predetermined value is started.