JPH04248335A - Voltage controller of ac generator for vehicle - Google Patents

Abstract

PURPOSE:To provide an inexpensive voltage controller of AC generator for vehicle having charging current detecting function. CONSTITUTION:The voltage controller comprises a drive circuit 5 for feeding a predetermined (700mA) exciting current to a charging line 27 when power generation is stopped prior to engine start, for example, and a circuit 8 for detecting the differential voltage between the terminal voltage 21 of a battery 2 and the output voltage 61 of a three-phase AC generator 6 and the magnitude of current 23 flowing through the charging line, during power generation, is detected based on a first differential voltage detected through the differential voltage detector 8 during operation of the drive circuit 5, the resistance of the charging line 22 which can be obtained based on the exciting current, and a second differential voltage detected through the differential voltage detecting circuit 8 during power generation after engine start, for example. According to the invention, a small and inexpensive voltage controller can be obtained and it can be installed at any position in the AC generator of vehicle because it is not subjected to magnetism.

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 an alternator for a vehicle.

0002

[Prior Art] In order to improve fuel efficiency and stabilize engine rotation during idling, there is a known technology that uses a Hall element to determine the current flowing through a charging line that connects the output terminal of a vehicle alternator and a battery. There is.

0003

[Problem to be Solved by the Invention] However, when trying to determine the charging current using a Hall element, the Hall element uses a special core, which results in high manufacturing costs, and it is easily influenced by magnetism, which limits the installation position. There was an issue of

[0004] The present invention has a charging current detection function.
The purpose of the present invention is to provide an inexpensive voltage control device for a vehicle alternator.

[0005]

[Means for solving the problem] In order to solve the above problem,
The present invention charges an output terminal of a vehicle alternator that is equipped with an armature winding, an excitation winding, and a rectifier and that is driven by a vehicle engine to generate electricity, and a vehicle-mounted battery that supplies power to the vehicle's electrical load. In a voltage control device for a vehicle alternator, which is electrically connected to the battery through a wire, detects the terminal voltage of the battery, and controls the excitation current flowing through the excitation winding so that the terminal voltage becomes the regulated voltage, when power generation is stopped. energizing means for causing a set amount of excitation current to flow through the charging line; and differential voltage detecting means for detecting a voltage difference between the terminal voltage of the battery and the output terminal voltage of the vehicle alternator; A resistance value of a charging line resistance that can be determined from a first differential voltage detected by the differential voltage detection means during operation and the set amount of excitation current, and a second differential voltage detected by the differential voltage energization means during power generation. Based on this, we adopted a configuration that detects the current value of the charging line current during power generation.

[0006]

[Operation] When power generation is stopped, when a set amount of excitation current is passed through the charging line by the energizing means, a first differential voltage is generated between the battery and the output terminal of the vehicle alternator due to the presence of minute charging line resistance. . Here, since the value of the excitation current flowing through the charging line is known, the charging line resistance of the charging line can be determined from the first differential voltage and this excitation current value. Since the resistance value of the charging line resistance does not change even during power generation, the charging current value of the charging current during power generation can be detected based on this resistance value and the second differential voltage detected by the voltage energizing means.

[0007]

[Effects of the Invention] Since the charging current flowing through the charging wire is determined without using a Hall element, a core or the like is not required, and the device can be manufactured at low cost and in a small size. Furthermore, since it is not affected by magnetism, the voltage control means can be placed at any location within the vehicle alternator.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a configuration diagram of a vehicle power supply system employing a voltage control device for a vehicle alternator according to the present invention, and FIGS. 2 and 3 are output waveform diagrams of each part of the vehicle power supply system.

As shown in FIG. 1, a voltage control device 1 adopted in a vehicle power supply system controls a terminal voltage 2 of a battery 2.
1 and a power MOS FE.
A drive circuit 5 that drives T4, a power generation detection circuit 7 that detects power generation of the three-phase alternator 6, and a differential voltage detection circuit that detects the difference between the terminal voltage 21 of the battery 2 and the output voltage 61 of the three-phase alternator 6. By including the circuit 8 and the comparator input circuit 9, charging current detection means is configured. Further, this voltage control device 1 is arranged in a housing (not shown) of a three-phase alternator, and includes a B terminal 11, an F terminal 12, and an E terminal 13, which also serve as output terminals of the vehicle alternator 6. , an IG terminal 14, an S terminal 15, a power generation output terminal 16, and a power generation detection terminal 17.

The three-phase AC generator 6 includes a bridge diode 62 which is a rectifier whose rectified output side is connected to the B terminal 11 and the E terminal 13, and an armature winding 63 connected to the AC input side of the bridge diode 62. , an excitation winding 64 connected to the F terminal 12 and the E terminal 13, and is driven by an on-vehicle engine (not shown).

The battery 2 is a 12V lead-acid battery mounted on the vehicle, and is electrically connected to an electric load 25 via a load switch 24 and connected to an IG via an ignition switch 26.
It is electrically connected to the terminal 14. Further, it is electrically connected to the B terminal 11 via a charging line 27.

In the voltage detection circuit 3, a constant voltage circuit 31
is electrically connected to the IG terminal 14 and generates a constant voltage (for example, DC5V) at the constant voltage terminal 32. The above constant voltage is applied to the negative input of the comparator 33 by a voltage dividing resistor 34,
A voltage obtained by dividing the terminal voltage 21 of the battery 2 applied to the S terminal 15 by voltage dividing resistors 36 and 37 is input to the positive input of the comparator 33.

[0013] Power MOS FET4 is a small MO
It is composed of tens of thousands of S FETs connected in parallel, with the drain connected to the B terminal 11 and the source connected to the F terminal 12. Note that power M is connected between the source and E terminal 13.
A flywheel diode 42 for preventing destruction of the OS FET 4 is connected.

In the drive circuit 5, a two-input OR circuit 51
The output of the comparator 33 is input as the output signal of the voltage detection circuit 3 to one input terminal of the 2-input OR circuit 5.
The output of No. 1 is input to the base of a transistor 52 that drives the power MOS FET 4 via a base resistor. The collector of the transistor 52 is connected to the output side of the booster circuit 50 connected to the IG terminal 14, and
Connected to the gate of power MOSFET4. The drains of several MOS FETs are connected to the detection terminal 41, and the detection terminal 41 is connected to resistors 53, 54 and an operational amplifier 5.
5, a detection current proportional to the excitation current (=drain current) is taken out, and this detection terminal 41 is connected to the excitation current detection circuit composed of resistors 53, 54,
It is connected to an excitation current detection circuit constituted by an operational amplifier 55. The negative input of the operational amplifier 55 has
A voltage obtained by dividing a constant voltage stabilized by a constant voltage circuit 31 using two resistors is input. The output terminal of the operational amplifier 55 is connected to the negative input terminal of the comparator 56,
A sawtooth wave generating circuit 57 is connected to the positive input terminal of the comparator 56. The output terminal of the comparator 56 is connected to another input terminal of the two-input OR circuit 51. Note that the collector of the transistor 58 is connected to the detection terminal 4.
1, and when the power generation detection circuit 7 detects the power generation of the three-phase alternating current generator 6, it is turned on (conducted) and the detection terminal 41 is grounded.

In the power generation detection circuit 7, the armature winding 63
The terminal voltage of one phase is divided by voltage dividing resistors 71 and 72,
The divided voltage is supplied to the positive input of a comparator 76 via a peak hold circuit including a diode 73, a capacitor 74, and a resistor 75. A voltage obtained by dividing the constant voltage supplied from the constant voltage terminal 32 by resistors 77 and 78 is input to the negative input of the comparator 76 . The output of the comparator 76 is input to the resistor 59 of the drive circuit 5 as a power generation detection signal.

In the differential voltage detection circuit 8, the resistors 81, 8
2, 83, 84, and an operational amplifier 85, each input terminal 86, 87 is connected to the S terminal 15 and the B terminal 11. Further, resistors 88 and 89 are voltage dividing resistors. The output of the operational amplifier 85 is input to a positive input of an A-D converter 91 of a comparator input circuit 9 and a power generation amount detection comparator 90, which will be described later.

In the comparator input circuit 9, 91 is a digital value obtained by converting the difference voltage between the output voltage 61 of the three-phase alternator 6 and the terminal voltage 21 of the battery 2 at a charging line current value of 700 mA into a charging line current value of 20A. Convert A-
A D converter 92 is a latch circuit that latches this digital value, 93 is a D-A converter that converts the output of the latch circuit 92 into an analog signal, and the converted analog signal is sent to the negative side of the power generation amount detection comparator 90. It has been entered. The inverter 94 has a power generation detection circuit 7
The output of the inverter 94 is input to the AND circuit 96 via a delay circuit 95 or directly. The output of the AND circuit 96 is input to a trigger pulse generation circuit 97, and the trigger pulse is input to the latch circuit 92 as a latch signal. Furthermore, 9
Reference numeral 8 denotes an engine control device for controlling the engine, into which various state signals of the vehicle including a power generation amount signal 99 are input.

The operation of this embodiment will be explained below.

When the ignition switch 26 is turned on, a constant voltage (lower than DC 12V) is generated at the constant voltage terminal 32 of the constant voltage circuit 31 of the detection circuit 3.

When the ignition switch 26 is turned on, the rotating shaft of the three-phase alternator 6 is not rotating and no power is being generated, so the terminal voltage 21 is less than the adjustment voltage, and the positive input of the comparator 33 Since the voltage is lower than the voltage of the negative side input, the output of the comparator 33 becomes L (low potential; hereinafter omitted). In addition, since power is not being generated, the phase voltage of the armature winding 63 detected by the detection terminal 17 is approximately zero, so the positive input voltage of the comparator 76 is lower than the negative input voltage, and the comparator 76
The output of is L. Therefore, transistor 58 is turned off. At this time, the power MOS FET 4 is not yet in a conductive state, so no drain current is detected at the detection terminal 41, and the output of the comparator 56 is L. Therefore, since the output of the two-input OR circuit 51 is L and the transistor 52 is off, the boosted voltage (approximately 22 V) is applied to the gate of the power MOS FET 4, and the power MOS FET 4 becomes conductive.

When the drain current of the power MOS FET 4 increases, the detection current detected at the detection terminal 41 also increases proportionally, and the output of the operational amplifier 55 decreases.

When the drain current of the power MOS FET 4 exceeds 700 mA, the output of the comparator 56 becomes a constant frequency pulse, and the duty increases, as shown in FIG. For this reason, power MOS FET4
The voltage applied to the gate also becomes a constant frequency pulse, and the duty decreases. This feedback control maintains the drain current at 700mA.

On the other hand, when the ignition switch 26 is turned on, the output of the inverter 94 of the comparator input circuit 9 is switched from L to H (high potential; hereinafter omitted) as shown in FIG. Therefore, the output of the delay circuit 95 is a signal whose phase is delayed by Td from the signal of the inverter 94 (as shown in FIG. 3), and the output of the AND circuit 96 is also a signal whose phase is delayed by Td from the signal of the inverter 94, as shown in FIG. becomes H after a delay. At the same time, the output of the trigger pulse generation circuit 97 (shown in FIG. 3) becomes H, and the latch circuit 92 becomes A-
The signal of the D converter 91 is latched. At this time, the latched signal is a signal proportional to the voltage drop (first differential voltage) between the S terminal 15 and the B terminal 11 when the excitation current is 700 mA. Here, if the value of the above signal is V1, the resistance value of the charging line resistance 22 is R, and the amplification factor of the differential amplifier circuit of the differential voltage detection circuit 8 is k1, then V1 = 0.7 x R
×k1. Therefore, if the charging line current 23 to be monitored (detected) is I0, the output voltage V2 of the DA converter 93 is given as V2=(I0/0.7)×V1.

Thereafter, the starter operates, the engine completely explodes, the rotation of the three-phase alternating current generator 6 increases, and when power generation begins, a phase voltage is generated in the armature winding 63. When the peak voltage of the phase voltage pulse becomes high and the voltage across the resistor 75 exceeds the voltage obtained by dividing the constant voltage by the resistors 77 and 78, the output of the comparator 76 becomes H. For this reason,
Transistor 58 becomes conductive and the output of comparator 56 becomes L.

Therefore, during power generation by the three-phase alternating current generator 6, drive control of the power MOS FET 4 is performed by the voltage detection circuit 3.
It is determined only by the output of the comparator 33, and when the terminal voltage 21 is below the regulation voltage (for example, 14.5V), the power MOS FET 4 becomes conductive, thereby increasing the exciting current and increasing the output of the three-phase alternator 6. The battery 2 is then charged.

When the terminal voltage 21 of the battery 2 exceeds the adjustment voltage, the output of the comparator 33 of the voltage detection circuit 3 becomes H, and the transistor 52 becomes conductive, so that the power M
OSFET4 is turned off. As a result, the exciting current decreases, and the power generation output of the three-phase alternating current generator 6 decreases. By repeating this, the terminal voltage 21 is maintained at the regulated voltage.

During power generation by the three-phase alternating current generator 6, the charging line current 23 is approximately several A for charging the battery 2 and for a regular load (not shown). When it is desired to monitor the charging line current 23 at, for example, 20 A (I0 = 20 A), in the above state, the output of the comparator 90 is L, and the engine control device 9
8, the power generation amount signal 99 is not sent. In this case, the engine control device 98 reduces the engine speed during idling in order to improve the fuel efficiency of the engine.

When the load switch 24 is closed and the electric loads 25 such as headlights and heaters are connected to the battery 2, the charging line current 23 exceeds 20A, so the output of the comparator 90 becomes H, and the engine control device 98, a power generation amount signal 99 indicating that the charging line current 23 is 20 A or more is sent. In this case, the engine control device 98 increases the engine speed during idling so as to increase the power generation capacity of the three-phase alternating current generator 6, thereby improving the charging balance.

The effects of the voltage control device 1 will be described below.

(A) Before the three-phase alternating current generator 6 starts generating electricity, the voltage control device 1 energizes the excitation winding 64 and determines the charging line resistance 22 from the voltage drop in the charging line 27. Since the charging line current 23 is calculated based on the voltage drop of the line 27 and the charging line resistance 22, it can be manufactured at a lower cost than the one in which the charging current is detected using a Hall element. Although the voltage detection circuit 3, the drive circuit 5, the power generation detection circuit 7, the differential voltage detection circuit 8, and the comparator input circuit 9 are complex in circuit terms, they have a configuration that can be electrically easily integrated into an IC. There is no significant increase in manufacturing costs.

(a) Unlike the voltage control device 1 based on a Hall element, the voltage control device 1 does not require a core to detect the charging line current, so the volume does not become large, and it is not affected by magnetism, so it is easy to use. It can be arranged within the housing of the three-phase alternator 6.

(c) When the charging wire resistor 22 is started (
Since it is detected every time (before the three-phase alternating current generator 6 starts generating electricity), it is not affected by changes in the charging line resistance 22 over time.

Next, a second embodiment of the present invention will be explained based on FIG. 4. FIG. 4 is a configuration diagram of a vehicle power supply system that employs a voltage control device for a vehicle alternator according to the present invention.

The present embodiment differs from the first embodiment in that the output of the comparator 90 is input to the OR circuit 901, which allows the charging line current 23 to reach a predetermined value (for example, 6
0A) or more, the output of the OR circuit 901 becomes H even when starting, turning off the power MOS FET4,
The charging line current 23 is limited so that the three-phase alternating current generator 6 is not overloaded.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a vehicle power supply system that employs a voltage control device for a vehicle alternator according to a first embodiment of the present invention.

FIG. 2 is an output waveform diagram of each part of the vehicle power supply system.

FIG. 3 is an output waveform diagram of each part of the vehicle power supply system.

FIG. 4 is a configuration diagram of a vehicle power supply system that employs a voltage control device for a vehicle alternator according to a second embodiment of the present invention.

[Explanation of symbols] 1 Voltage control device (voltage control device for vehicle alternator) 2 Battery 5 Drive circuit (current supply means) 6 Three-phase alternator (vehicle alternator) 8 Differential voltage detection circuit (differential voltage Detection means) 11 B terminal 21 Terminal voltage 22 Charging wire resistance 23 Charging wire current 25 Electric load 27 Charging wire 61 Output voltage (output terminal voltage) 62 Bridge diode (rectifier) 63 Armature winding 64 Excitation winding

Claims (1)

[Claims] Claim 1: An output terminal of a vehicle alternator that is equipped with an armature winding, an excitation winding, and a rectifier and that is driven by an on-vehicle engine to generate electricity, and an on-vehicle battery that supplies power to an electrical load of the vehicle. In a voltage control device for a vehicle alternator, which is electrically connected to a charging line, detects a terminal voltage of the battery, and controls an excitation current flowing through the excitation winding so that the terminal voltage becomes a regulated voltage. energizing means for causing a set amount of excitation current to flow through the charging line;
a first differential voltage detecting means for detecting a differential voltage between a terminal voltage of the battery and an output terminal voltage of the vehicle alternator, the first differential voltage being detected by the differential voltage detecting means when the energizing means is activated; Detecting the current value of the charging line current during power generation based on the resistance value of the charging line resistance that can be determined from the set amount of excitation current and the second differential voltage detected by the differential voltage energizing means during power generation. A voltage control device for a vehicle alternator, characterized in that: