JPH0427780B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a voltage regulating device for a generator, and in particular to an alternating current generator for a vehicle suitable for use as a charging generator installed in an automobile or the like to charge a storage battery. This invention relates to a voltage regulator.

[Background of the invention]

Conventional voltage regulators, as described in U.S. Pat. No. 3,469,168, adjust the voltage to prevent voltage control from becoming impossible when the voltage detection terminal of a storage battery charged by a generator is disconnected. Two detection circuits were prepared. However, with this method, auxiliary voltage detection takes priority even during normal power generation due to variations in the temperature characteristics of both systems, resulting in the inability to accurately control the voltage of the storage battery.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a voltage regulator for a vehicle alternator whose voltage detection input is not affected by temperature.

[Summary of the invention]

The present invention extracts the maximum value from among a plurality of voltage inputs using a rectifier and uses the maximum value as a control voltage. In particular, in order to compensate for the voltage drop of the rectifier, a second rectifier installed alongside the first rectifier is used. We installed rectifiers and controlled the current value flowing through these rectifiers to offset the imbalance in voltage drop.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. FIG. 1 shows a circuit diagram of a charging system including a generator driven by an engine (not shown).

In Figure 1, 1 is the armature winding of the generator, 2
is a field winding that supplies magnetic flux to the armature winding 1;
3 is a three-phase full-wave rectifier that converts the AC output of the armature winding 1 into DC; 5 is a storage battery that is connected to the three-phase full-wave rectifier 3, is charged, and supplies current to an external load (not shown). It is. 6 is a key switch. 8 is a voltage regulator using a hybrid thick film integrated circuit, which includes a power transistor 9, a control monolithic IC 10, and a flywheel diode 1.
1, resistors 12, 13, voltage dividing resistors 14a, 14
b, 15a, and 15b.

The control monolithic IC 10 includes a constant voltage circuit including a Zener diode 101 and a diode 102, a comparator 103, and voltage dividing resistors 104a and 10.
4b, resistor 105 for constant current generation, NPN
Transistors 106 and 107, NPN transistor 108 forming a first constant current source, PNP transistor 109, PNP forming a second constant current source
It consists of a transistor 110, diodes 111 and 112 that serve as a plurality of first rectifier groups, and a diode 113 that serves as a second rectifier.

In the above configuration, when the key switch 6 is turned on, an initial excitation current flows from the storage battery 5 through the field winding 2 and the power transistor 9. Next, when the generator starts rotating, a voltage is generated in the armature winding 1, and the storage battery 5 is charged via the three-phase full-wave rectifier 3.

When the key switch 6 is turned on, a constant voltage is generated in the constant voltage circuit in the control monolithic IC 10, and the comparator 103 is driven. When the generated voltage is low and at the same time the voltage of the storage battery 5 is low, the voltage dividing resistor 14a, 1 divides the voltage of the storage battery 5.
4b is lower than the voltage at the voltage dividing point of the voltage dividing resistors 104a and 104b that divide the constant voltage, the output of the comparator 103 becomes high level, the power transistor 9 conducts, and the field current decreases. energized. As the field current increases, the generated voltage also increases, and the voltage of the storage battery 5 increases. Then, the voltage at the voltage dividing point of the voltage dividing resistors 14a, 14b becomes higher than the voltage at the voltage dividing point of the voltage dividing resistors 104a, 104b, and the output of the comparator 103 becomes a low level, and the power transistor 9 is cut off. The field current is attenuated through the flywheel diode 11. When the field current decreases, the generator output voltage decreases,
The voltage of the storage battery 5 also becomes low. By repeating the above operations, the voltage of the storage battery 5 is controlled to a constant value.

Here, the voltage at the voltage dividing point of the voltage dividing resistors 14a, 14b is assumed to be V _S ', and the voltage at the voltage dividing point of the voltage dividing resistors 15a, 15b is assumed to be V _B '. When the collector potential of the transistor 108 is _V1 , _V1 is expressed as follows.

V ₁ = max (V _S ′, V _B ′) − V _BE ……(1) Here, V _BE is the voltage between the base and emitter of a transistor or the forward voltage drop of a diode.

However, it is assumed that the transistor 108 is in a conductive state and current is flowing through the diode 111 or the diode 112.

During normal power generation, if the voltage dividing resistance ratio is selected so that V _S ′>V _B ′, then V ₁ = V _S ′−V _BE ……(1′). Furthermore, the anode potential V ₂ of the diode 113 is expressed as V ₂ =V ₁ +V _BE (2) when a forward current flows through the diode 113, so by substituting equation (1), V ₂ = max(V _S ′, V _B ′) ...(3) holds. When (1') holds, equation (3) is rewritten as V ₂ =V _S '(3'), and the voltage at the S terminal is controlled to a constant value. Next, when the S terminal is disconnected, V _S ′ becomes the ground potential, and V _B ′ > V _S ′, so equation (3) becomes V ₂ = V _B ′ ... (3″), and the voltage at the B terminal As described above, according to this embodiment, even if the voltage detection terminal becomes disconnected, the voltage of the generator is controlled to a constant value by performing auxiliary voltage detection.

Here, in order for equation (3) to hold true and for V _BE in equations (1) and (2) to be completely canceled out, the currents flowing through the diode 111 or 112 and the diode 113 must be equal.

Generally, the voltage between the base and emitter of a transistor is expressed by the following formula.

V _BE ≒kT/qlnI _C /A _E・I ₀ ...(4) where k; Boltzmann's constant T; absolute temperature q; charge amount I _C ; collector current A _E ; emitter area I ₀ ; leakage current, The diodes 111, 112, and 113 are used as diodes by short-circuiting their collectors and bases.

In equation (4), since A _E and I ₀ are equal for elements within the same monolithic IC, V _BE is uniquely determined by I _C. In the circuit of FIG.
and 108 act as a constant current source using a current mirror circuit, and the following equation holds.

I ₁ + I ₃ = I ₂ ...(5) However, I ₁ ; Collector current of transistor 110 (≒ current of diode 113) I ₂ ; Collector current of transistor 108 I ₃ ; Current of diode 111 or 112 (S terminal connected When it is, it is a diode 111).

At this time, when the relationship I ₂ >I ₁ holds true, I ₃ >0, and a current flows through the diode 113 in the forward direction.

If we add the condition I ₂ = 2I ₁ here, equation (5) can be rewritten as follows.

I ₁ = I ₃ ...(6) According to equation (6), the diode 111 or 112,
It is proven that the current values flowing through the diode 113 are equal, V _BE of equations (1) and (2) cancel each other out, and equation (3) holds true.

The transistor 106 is connected to the resistor 1 from the constant voltage circuit.
A reference constant current determined by 05 is applied, and this is designated as _I1 . Transistor 107 is transistor 106
Assuming that the emitter area is the same as , a current equal to I ₁ flows. This current is transistor 1
The same current, ie, _I1 , flows through the transistor 110 that drives the transistor 09 and is connected in a current mirror. On the other hand, if the emitter area of transistor 108 is set twice that of transistor 106, the left side of equation (4) is regarded as a constant value, and the current flowing through transistor 108 becomes twice the current flowing through transistor 106. As a result, the condition I ₂ =2I ₁ is satisfied. Therefore, V _S ′ and V _B ′ are always constant regardless of temperature etc.
The higher voltage among them is transmitted to the comparator 103,
This voltage determines the output voltage of the generator.

According to this embodiment, since the voltage of the storage battery 5 can be accurately detected regardless of the temperature, etc., there is an effect that the charging performance is improved.

Another embodiment of the invention is shown in FIG. Comparing FIG. 2 with FIG. 1, we see that an auxiliary rectifier 4 and a charging indicator 7 are added, and a field winding 2, a charging indicator 7, and a voltage dividing resistor 15a are connected to the negative pole of the auxiliary rectifier 4. The only difference is that. In this embodiment, when the key switch 6 is turned on, an initial excitation current flows from the storage battery 5 through the charging indicator 7 and the field winding 2, and when power generation starts, the negative electrode voltage of the auxiliary rectifier 4 increases. The charging indicator light 7 goes out. Further, auxiliary detection when the S terminal is disconnected is performed using the negative electrode voltage of the auxiliary rectifier 4. In this embodiment, in addition to the same effect as the first embodiment, the charging indicator light 7 is turned on and off,
This has the effect of making charging display easier.

〔Effect of the invention〕

According to the present invention, it is possible to have two voltage detection systems with only voltage dividing resistors and one voltage selection system, which has the effect of canceling out the effects of temperature and enabling highly accurate storage battery charging. .

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a charging generator according to one embodiment of the present invention, and FIG. 2 is a circuit diagram of a charging generator according to another embodiment of the present invention. 1...Armature winding, 2...Field winding, 5...Storage battery, 10...Control monolithic IC, 103
...Comparator, 106,107,108...NPN
Transistor, 109, 110...PNP transistor, 111, 112, 113...diode.

Claims (1)

[Scope of Claims] 1. A voltage regulating device for a vehicle alternator, which comprises a generator that is driven according to the rotation of an engine and charges a storage battery, and a voltage regulation circuit that controls the voltage of the storage battery to be constant. A plurality of voltage dividing circuit groups 14a, 14b, 15 that divide the voltage generated by the generator.
a, 15b, and each voltage dividing point V _S ′ of the voltage dividing circuit group,
A plurality of first rectifier groups 11 whose positive electrodes are connected to V _B ′ and whose negative electrodes are commonly connected to a first constant current source 108
1, 112, and a second rectifier 113 whose negative electrode is connected to the first constant current source together with the negative electrode of the plurality of first rectifier groups, and whose positive electrode voltage is controlled to a constant value.
The output terminal is connected to the field winding control power transistor 9 of the generator, the input positive terminal is connected to the constant voltage circuits 101 and 102, and the input negative terminal is connected to the second constant current source 110 and the second 1. A voltage regulator for a vehicle alternator, comprising: a comparator 103 connected to a positive electrode of a rectifier. 2. The alternator for a vehicle according to claim 1, wherein the current value of the first constant current source 108 is set to approximately twice the current value of the second constant current source 110. voltage regulator.