JPH04295236A - Voltage controller for ac generator of vehicle - Google Patents

Abstract

PURPOSE:To provide a voltage controller for AC generator of vehicle which can control voltage stably even if the charging line voltage contains a high ripple. CONSTITUTION:The voltage controller has an input section for generating a current corresponding to the difference between a divided charging line voltage Vo and a divided reference voltage Vref and current from each input section is fed to the emitters of PNP transistors 26, 29 having bases connected each other through a ripple smoothing capacitor 36. The voltage controller further comprises a balanced DC amplifier circuit 2 connected, in the form of a current mirror circuit, with the collectors of NPN transistors 27, 28, a power MOS.FET 5 connected in series with a field winding 11, and a threshold judging circuit 6 for turning the power MOS.FET 5 ON in case of Vo>Vref.

Description

[Detailed description of the invention]

0001

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

0002

[Prior Art] As shown in FIGS. 3 and 4,
49920 describes the following technology. A differential amplifier 100 to which a generator voltage 110 and a reference voltage 120 are supplied, a smoothing capacitor 210 that smoothes the DC voltage, and a controllable semiconductor connected in series to at least one generator winding 310. A switch 300 is provided, and when the generator voltage 110 exceeds a fixable threshold, this semiconductor switch 300 opens, and the output side of the differential amplifier 100 is connected to a charging/discharging current source 130 of a smoothing capacitor 210, 140, and the smoothing capacitor 210 is connected to the input side of the threshold voltage 400. In the voltage regulator that adjusts the fluctuating DC voltage of the generator, the charging and discharging process of the smoothing capacitor 210 is connected to the input side of the threshold voltage 400. It can be controlled by the collector current of the transistor 150, 160, and the other two transistors 150, 160
are each connected in the form of a current mirror circuit to each one transistor 170, 180 of both balanced amplifier branches of the differential amplifier 100, which is configured as a balanced DC amplifier with two inputs and two outputs. has been done.

0003

[Problems to be Solved by the Invention] However, the above-mentioned conventional technology has the following problems. In recent years, with the increase in the number of electrical components due to the advancement of vehicles, the capacity of generators has increased, and the ripple in the rectified output of the generator that is supplied to the battery and vehicle load has become extremely large (up to about 40V). It has become. However, in the conventional technology, the capacitance of the smoothing capacitor 210 is small enough to be built into a monolithic IC (3
0 pF order), the charging and discharging process of the smoothing capacitor 210 cannot be greatly controlled by the collector currents of the other two transistors 150 and 160, so the smoothing capacitor 21
The time constant of 0 cannot be made long enough. In other words, the threshold price is 400
detects the ripple peak, resulting in a phenomenon in which the regulated voltage decreases. An object of the present invention is to ensure stable generator voltage control by reliably removing ripples even if high ripples are included in the charging line voltage, without increasing the capacity of the smoothing capacitor. The present invention provides a voltage control device for a vehicle alternator.

0004

[Means for solving the problem] In order to solve the above problem,
The present invention employs the following configuration. (1) A differential amplifier including an armature winding, an excitation winding, and a rectifier, into which a divided voltage of a generated voltage of a vehicle alternator that charges an on-board battery and a divided voltage of a reference voltage are input; A semiconductor switch is connected in series with the excitation winding, and is connected between the semiconductor switch and the differential amplifier, and is configured to turn on/off the semiconductor switch based on the output of the differential amplifier.
In the voltage control device for a vehicle alternator having a threshold value determination circuit for off-control, the differential amplifier is a balanced type having two input sections that generate a current according to a voltage difference between the two inputs. This is a DC amplifier circuit, and the current at each input section is supplied to the emitter of a PNP transistor whose collector is grounded, and the base of the transistor is connected via a ripple smoothing capacitor.
It is connected in the form of a current mirror circuit to the collectors of two NPN transistors whose emitters are grounded and whose bases are commonly connected.

(2) A differential amplifier that includes an armature winding, an excitation winding, and a rectifier, and receives a divided voltage of a voltage generated by a vehicle alternator that charges an on-vehicle battery and a divided voltage of a reference voltage. a semiconductor switch connected in series with the excitation winding; and a semiconductor switch connected between the semiconductor switch and the differential amplifier to control on/off of the semiconductor switch based on the output of the differential amplifier. In the voltage control device for a vehicle alternator having a threshold value discrimination circuit, the differential amplifier is a balanced DC amplifier circuit having two input sections that generate a current according to a voltage difference between the two inputs. The current for each input section is supplied from the emitter of an NPN transistor whose collector is connected to the positive terminal of the power supply.
The base of the transistor is connected via a ripple smoothing capacitor, and at the same time is connected in a current mirror circuit to the collectors of two PNP transistors whose emitters are grounded and whose bases are commonly connected.

[0006]

[Operation] (Regarding claim 1) When the voltage obtained by dividing the generated voltage (hereinafter referred to as the divided voltage generated voltage) is lower than the voltage obtained by dividing the reference voltage (hereinafter referred to as the divided reference voltage), the balanced DC Each input section of the amplifier circuit has a relationship of (current at the input section where the divided voltage generation voltage is input) > (current at the input section where the divided reference voltage is input). voltage reference voltage) -
A current is generated according to the (divided voltage generation voltage). Furthermore, (emitter current of the PNP transistor located on the side to which the divided voltage generation voltage is input)>(emitter current of the PNP transistor located on the side to which the divided reference voltage is input). Then, the ripple smoothing capacitor discharges the short amount to the collector of the NPN transistor located on the side where the divided reference voltage is input, and the output voltage of the balanced DC amplifier circuit decreases. Turn on the semiconductor switch. Therefore, an exciting current flows, the alternator starts generating electricity, and the generated voltage increases. When the divided voltage generation voltage is higher than the divided reference voltage, each input section of the balanced DC amplifier circuit has the following condition: (current at the input section where the divided voltage generation voltage is input) < (divided reference voltage is inputted). A current corresponding to (divided voltage generation voltage) - (divided voltage reference voltage) is generated while maintaining the relationship (current at the input section on the side that receives voltage). Then, the ripple smoothing capacitor is charged from the base of the PNP transistor located on the side where the divided reference voltage is input, and the output voltage of the balanced DC amplifier circuit gradually rises. Turn off. Therefore, the exciting current stops, the alternator stops generating electricity, and the generated voltage drops.

(Regarding Claim 2) When the divided voltage generation voltage is lower than the divided reference voltage, each input section of the balanced DC amplifier circuit has (current at the input section on the side where the divided voltage generation voltage is input)
A current corresponding to (divided reference voltage) - (divided generated voltage) is generated while maintaining the relationship <(current of the input section to which the divided reference voltage is input). Also, (emitter current of the NPN transistor located on the side where the divided voltage generation voltage is input)
<(emitter current of the NPN transistor located on the side to which the divided reference voltage is input). Then, the ripple smoothing capacitor is charged from the base of the PNP transistor located on the side where the divided reference voltage is input, and the output voltage of the balanced DC amplifier circuit gradually decreases. Turn on. Excitation current flows, the alternator starts generating electricity, and the generated voltage increases. When the divided voltage generation voltage is higher than the divided reference voltage, each input section of the balanced DC amplifier circuit has the following relationship: (current at the input section where the divided voltage generation voltage is input) > (divided reference voltage is inputted) Maintaining the relationship (current at the input section on the input side), (divided voltage generation voltage) - (
A current is generated according to the divided reference voltage). Then, the ripple smoothing capacitor discharges the shortfall to the collector of the PNP transistor located on the side where the divided reference voltage is input, and the output voltage of the balanced DC amplifier circuit increases, so the threshold value discrimination circuit Turn off the semiconductor switch. The excitation current stops, the alternator stops generating electricity, and the generated voltage drops.

[0008]

[Effect of the invention] Even if the capacitance is small, the time constant of the smoothing capacitor can be long, and even if the generated voltage contains high ripple, the voltage control device can reliably remove the ripple and maintain stable AC for vehicles. It is possible to control the voltage of the generator.

[0009]

Embodiment A first embodiment of the present invention will be explained based on FIG. As shown in FIG. 1, a voltage control device A for a vehicle alternator has a charging line voltage VB of a three-phase alternator 1, which will be described later.
A balanced DC amplifier circuit 2 receives a divided charging line voltage V0 divided by a resistor 41 and a semi-fixed resistor 42 and a divided reference voltage Vref obtained by dividing a reference voltage VD by resistors 43 and 44, and an excitation circuit. Power M electrically connected in series with winding 11
It has an OS/FET 5 and a threshold value determination circuit 6 into which the output of the balanced DC amplifier circuit 2 is input. Further, 81 is an ignition switch, 82 is a reference voltage source for setting the power generation target voltage, 83 and 84 are resistors and Zener diodes for supplying constant voltage to the balanced DC amplifier circuit 2 and the threshold value determination circuit 6, and 85 , 86 are transistors and reference current sources for obtaining constant current.

The three-phase alternating current generator 1 includes an excitation winding 11, an armature winding 12, a flywheel diode 13, and a rectifier 14, and is driven by an on-vehicle engine (not shown) to generate electricity and supply it to a vehicle load 87. An on-vehicle battery 88 that supplies power is charged via a charging line 89.

The balanced DC amplifier circuit 2 includes resistors 21 and 22.
, transistors 23 to 35, and a ripple smoothing capacitor 36 with a capacitance of several tens of pF. transistor 2
The collector currents of transistors 5 and 30 are supplied to the emitters of PNP transistors 26 and 29, respectively, whose collectors are grounded, and the bases of transistors 26 and 29 are connected via a smoothing capacitor 36, and at the same time, the emitters are grounded. It is connected in the form of a current mirror circuit to the collectors of NPN transistors 27 and 28 whose bases are commonly connected. Note that the resistors 21 and 22 have resistance values R21 and R22.
(R21=R22) resistance, transistors 25, 30,
The transistors 26 and 29 and the transistors 27 and 28 have the same characteristics.

The threshold value determination circuit 6 includes transistors 64 to 69 forming a comparator, transistors 61 to 63 forming a constant current source for the comparator, and resistors 70 to 73 forming a reference voltage source for the comparator. Transistors 74 to 76 and power MOS/FET 5
The drive circuit includes resistors 77, 78 and a transistor 79. The reference voltage of the comparator (base voltage of transistor 69) of this threshold value discrimination circuit 6 is:
When the transistor 76 is conductive (=power MOS/FET5
is Hi (2.5V in this embodiment) when the voltage is on (on), but is changed to Lo (1.5V in this embodiment) when the voltage is not energized. In this threshold value determination circuit 6, when the divided charging line voltage V0 is less than the divided reference voltage Vref, the transistor 79 becomes non-conductive, and the power MOS/FET 5
is turned on.

The operation of this embodiment will be explained below. When the ignition switch 81 is turned on, a reference voltage VD is generated at the output side of the reference voltage source 82, a constant voltage is generated across the Zener diode 84, and the reference current source 86 also operates. In addition, when (charging line voltage VB) = (adjustment voltage),
A constant is set so that V0 = Vref.

[At the initial stage of starting the three-phase alternator 1,
When V0 <Vref] The collector current IC30 of the transistor 30 is zero, the collector current Ic25 of the transistor 25 is approximately, (Vref - V0)/R2
It is 1. Further, if the current amplification factor of the transistors 26 and 29 is hFE0, and the base currents of the transistors 26 and 29 are IB26 and IB29, then IB29 is zero,
IB26 is (1/hFE0)×IC25. Here, since the transistors 26 and 29 are connected to the collectors of the NPN transistors 27 and 28 in the form of a current mirror circuit, the collector currents IC27 and IC28 of the transistors 27 and 28 are approximately equal to each other, and
The base current IB26 of the transistor 26 is also approximately equal, and the base current IB29 of the transistor 29 is zero. Therefore, the amount of charge in the smoothing capacitor 36 that is insufficient is discharged to the collector of the transistor 28, and when the discharge is completed, the voltage VC28 of the transistors 28 and 29
VE29 decreases by 0.7 due to PN junction forward drop.
It will be about V. Therefore, the base voltage of transistor 64 becomes lower than the base voltage (1.5V) of transistor 69, transistor 76 becomes conductive, and transistor 76 becomes conductive.
5 becomes non-conductive, the reference voltage of the comparator (base voltage of transistor 69) becomes Hi (2.5 V), and at the same time, transistor 79 becomes non-conductive, so the power MO
The S-FET 5 is turned on, excitation current flows, the three-phase AC generator 1 generates electricity, and the charging line voltage VB rises.

[As battery charging progresses, V0 <Vre
When transitioning from f state to V0 > Vref] V0
>Vref, the collector current Ic25 of the transistor 25 is zero, and the collector current Ic30 of the transistor 30 is approximately (V0 - Vref)/R2.
It becomes 2. Similarly, the base current IB of transistor 26
26 is zero, the collector currents IC27 and IC28 of transistors 27 and 28 are zero, and the base current IB29 of transistor 29 is (1/hFE0)×IC30
becomes. Therefore, the smoothing capacitor 36 is charged by the base current of the transistor 29, and if the capacitance of the smoothing capacitor 36 is C, the emitter voltage of the transistor 29 is C/IB29 = (C x hFE0)/I
C30 increases at a rate of [μs/V]. and,
When the reference voltage of the comparator (base voltage of transistor 69) of 2.5V is exceeded, the comparator is inverted and transistor 76 becomes non-conductive. As a result, transistors 75 and 79 become conductive, and the reference voltage of the comparator becomes Lo.
(1.5V), the power MOS/FET 5 is turned off, the excitation current is reduced, the three-phase alternating current generator 1 stops generating electricity, and the charging line voltage VB decreases.

[As the battery discharge progresses, V0 > Vre
When transitioning from f state to V0 <Vref] V0
<Vref, the base current IB29 of the transistor 29 is zero, the base current IB26 of the transistor 26 becomes (1/hFE0)×IC25, the smoothing capacitor 36 is discharged by the collector current of the transistor 28, and the transistor 29 The emitter voltage of decreases at the rate of (C×hFE0)/IC25,
When the reference voltage of the comparator becomes less than Lo (1.5V), the comparator is inverted, transistor 76 becomes conductive, transistors 75 and 79 become non-conductive, the reference voltage of the comparator becomes Hi (2.5V), and power MOS/FET5
is turned on, excitation current flows, three-phase AC generator 1 generates electricity, and charging line voltage VB rises. Due to the above operation,
The charging line voltage VB is controlled to be the regulated voltage.

This embodiment has the following effects. 1/h of the current proportional to the difference between the divided charging line voltage V0 and the divided reference voltage Vref, which is input to the balanced DC amplifier circuit 2.
The ripple smoothing capacitor 36 is charged and discharged with a current that is FE0 times higher, and the output of the balanced DC amplifier circuit 2 can be extracted based on the terminal voltage of the capacitor 36. Therefore, the balanced DC amplifier circuit 2 and the threshold value discrimination circuit 6
Even if a capacitor of several tens of pF is used, which can be built into a monolithic IC that incorporates a capacitor, a time constant of several hundred μs can be obtained (several times that of conventional technology), and the ripple in the divided charging line voltage V0 is sufficient. smoothed. Therefore, even if the charging line voltage VB contains a high ripple (about several tens of V), the problem that the threshold value discriminating circuit 6 detects the peak of the ripple and the actual adjustment voltage drops does not occur. , stable voltage control of the generator 1 can be performed.

A voltage control device B for a vehicle AC generator shown in FIG. 2 is a second embodiment of the present invention, and the types of transistors used in the balanced DC amplifier circuit 2 and the threshold value discrimination circuit 6 are exchanged. This embodiment has the same functions and effects as those of the first embodiment.

[Brief explanation of the drawing]

FIG. 1 is an electrical circuit diagram of a voltage control device for a vehicle alternator according to a first embodiment of the present invention.

FIG. 2 is an electric circuit diagram of a voltage control device for a vehicle alternator according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram for explaining a conventional technique.

FIG. 4 is an explanatory diagram for explaining a conventional technique.

[Explanation of symbols]

1 Three-phase AC generator 2 Balanced DC amplifier circuit 5 Power MOS/FET (semiconductor switch) 6
Threshold discrimination circuit 11 Excitation winding 12 Armature winding 14 Rectifiers 26, 29 Transistors (PN with the collector grounded)
P-type transistor, NPN-type transistor whose collector is connected to the positive power supply) 27, 28 Transistor (NPN-type transistor whose base is connected in common, PNP-type transistor whose base is connected in common) 36 Ripple smoothing capacitor 88 Automotive Battery VB Charging line voltage (generated voltage) V0 Partial voltage charging line voltage (divided voltage of generated voltage) VD
Reference voltage

Claims (2)

[Claims] 1. A differential amplifier comprising an armature winding, an excitation winding, and a rectifier, and into which a divided voltage of a generated voltage of a vehicle alternator that charges an on-board battery and a divided voltage of a reference voltage are input. , a semiconductor switch connected in series with the excitation winding, and a threshold connected between the semiconductor switch and the differential amplifier to control on/off of the semiconductor switch based on the output of the differential amplifier. In the voltage control device for a vehicle alternator having a value discrimination circuit, the differential amplifier is a balanced DC amplifier circuit having two input sections that generate a current according to a voltage difference between the two inputs. , the current of each input section is supplied to the emitter of a PNP transistor whose collector is grounded, and the bases of the transistors are connected via a ripple smoothing capacitor, and at the same time, the emitter is grounded and the bases are commonly connected. 1. A voltage control device for a vehicle alternator, characterized in that the voltage control device is connected to the collectors of two NPN transistors in the form of a current mirror circuit. 2. A differential amplifier comprising an armature winding, an excitation winding, and a rectifier, and into which a divided voltage of a generated voltage of a vehicle alternator that charges an on-board battery and a divided voltage of a reference voltage are input. , a semiconductor switch connected in series with the excitation winding, and a threshold connected between the semiconductor switch and the differential amplifier to control on/off of the semiconductor switch based on the output of the differential amplifier. In the voltage control device for a vehicle alternator having a value discrimination circuit, the differential amplifier is a balanced DC amplifier circuit having two input sections that generate a current according to a voltage difference between the two inputs. , the current for each input section is supplied from the emitter of an NPN transistor whose collector is connected to the positive power supply, and the base of the transistor is connected via a ripple smoothing capacitor, and at the same time the emitter is grounded and the base is connected to the positive terminal of the power supply. 1. A voltage control device for a vehicle alternator, characterized in that the voltage control device is connected in the form of a current mirror circuit to the collectors of two commonly connected PNP transistors.