JP2002369596A - Controller of generator for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a controller and a control method of a generator for vehicle, in which the generation voltage will not exceed the target level at light load, in high-speed rotational region. SOLUTION: The controller of a generator for vehicle comprises a switching element 14 for controlling the field current of a generator 1 for vehicle, a PWM conversion circuit 13 for providing the switching element 14 with a PWM signal generated, based on the comparison results of the generation voltage of the generator 1 for vehicle and a reference voltage, and a duty ratio correcting means 20 for controlling the lowest value of ON-duty of a PWM signal which is generated from the PWM conversion circuit 13 for the switching element 14, where the duty ratio correcting means 20 controls the PWM conversion circuit 13 to vary the lowest value of ON-duty depending on the rotational speed of generator 1 for vehicle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicular generator driven by an internal combustion engine for a vehicle for charging a battery and supplying electric power to various electric loads. The present invention relates to a control device capable of avoiding an overvoltage trouble associated therewith.

[0002]

2. Description of the Related Art FIG. 3 shows a basic circuit of a general vehicle generator and a control device, and FIG. 4 shows a generated voltage characteristic thereof. 3, a vehicle generator 1 includes a three-phase armature coil 2 and a field coil 3, and the output of the armature coil 2 is a three-phase bridge full-wave rectifier circuit including diodes D1 to D6. The battery 4 is charged via the. The field coil 3 receives power supply from the output of the battery 4 and the armature coil 2 to generate a field magnetic flux of the vehicle generator 1, and a field current flowing through the field coil 3 is controlled by a control device 5 described later. The power generation voltage of the vehicle generator 1 is controlled to a predetermined target voltage.

The control device 5 receives voltage generated by the vehicle generator 1 at a terminal B and divides the voltage generated by the voltage generator 6 and 7.
A low-pass filter 8 for removing high-frequency components from the divided voltage;
A power supply circuit 9 for generating the power supply voltage of the power supply circuit, voltage dividing resistors 10 and 11 for dividing the power supply voltage, a comparator 12 for comparing the divided power supply voltage with a voltage generated from the low-pass filter 8, and a comparator 12 PWM by output
A PWM conversion circuit 13 for generating a signal, switching means 14 for controlling the field current of the field coil 3 by turning on and off by the output of the PWM conversion circuit 13, and a field current OF
Flywheel diode 15 that absorbs abnormal voltage at F
And F- for converting the output frequency of the armature coil 2 into a voltage.
It comprises a V conversion circuit 16, a power generation start rotation speed determination means 17 receiving the output of the FV conversion circuit 16, and a gradual excitation control release rotation speed determination means 18.

In the conventional control device for a vehicle generator configured as described above, the voltage generated by the armature coil 2 is input to the B terminal of the control device 5 and divided by the voltage dividing resistors 6 and 7 to provide a low-pass voltage. The high frequency component is removed by the filter 8 and input to the comparator 12. Comparator 12
The voltage of the power supply circuit 9 is divided by the voltage dividing resistors 10 and 11 and inputted as a reference voltage to the (−) terminal of FIG. PWM
The conversion circuit 13 generates a PWM signal having a predetermined frequency, and the duty ratio of the PWM signal is
2 is applied to the switching means 14 and is modulated by the output of the switching means 2 to control the switching means 14 ON-OFF to control the field current, and to control the generated voltage of the armature coil 2 to the target voltage corresponding to the reference voltage.

On the other hand, when the AC voltage of the armature coil 2 is FV
The FV conversion circuit 16 outputs a voltage proportional to the frequency of the armature coil 2, that is, the rotation speed of the vehicular generator 1, and outputs the voltage to the power generation start rotation number determination unit 17.
And the gradual excitation control release rotation speed determination means 18. The power generation start rotation speed determining means 17 detects that the generated voltage of the vehicle generator 1 has reached a rotation speed sufficient to charge the battery 4, and operates the excitation current to gradually increase the output to thereby generate the vehicle power. A sudden change in torque for driving the machine 1 is avoided. The vehicular generator 1 is driven by an internal combustion engine mounted on the vehicle. When the internal combustion engine is started and idling, the battery 4 is sufficiently charged. The power generation start rotation speed determination means 17 is for avoiding troubles such as deterioration of fuel efficiency due to a sudden change in the load of the vehicle generator 1 at the time of starting. Therefore, it is necessary for the FV conversion circuit 16 to operate from an extremely low rotation range.

Further, when a large-capacity load having a large current consumption is connected to the battery 4 in a low-speed rotation range, the voltage of the battery 4 decreases and the output of the vehicle generator 1 increases rapidly.
The driving torque of the vehicle generator 1 rapidly increases and makes the rotation of the internal combustion engine unstable. In the control device for the internal combustion engine, the fuel supply amount is controlled in order to stabilize the rotation of the internal combustion engine. This rapid change in the fuel control amount deteriorates the fuel consumption. In order to avoid the deterioration of the fuel consumption, the control device 5 controls the excitation current to increase the output gradually by operating the excitation current.
This control becomes unnecessary when the rotation speed of the internal combustion engine exceeds a predetermined value, and is released when the rotation speed is higher than the predetermined rotation speed. This release is controlled by the gradual excitation control release rotation speed determination means 1.
8

[0007]

The control device of the conventional vehicle generator has the functions described above, but the control device 5 generally aims at optimal charging of the battery 4, and therefore the control device 5 has a function of It is configured to control the generated voltage of the generator 1 to a predetermined target voltage. In a state where the electric load of the vehicle is extremely low, the output can be controlled to the target voltage by suppressing the output of the generator for the vehicle to an extremely low output. Since the rotation speed needs to be detected in the above, the minimum power generation is necessary, and the duty ratio of the PWM signal is set to the minimum value of the ON duty so that the minimum voltage can be obtained even when the internal combustion engine is in the cranking state. It is determined.

In the characteristic diagram of FIG. 4, a diagram indicated by a minimum DUTY shows an ON duty for obtaining a minimum voltage necessary for detecting a rotation speed in a low speed rotation range. When the minimum value is set in this manner, this value is maintained up to the high-speed rotation range, and even when the ON duty has the same value, the no-load power generation voltage of the vehicle generator 1 increases as the rotation speed increases as shown in the figure. That is, when the rotation speed exceeds the predetermined rotation speed, the generated voltage exceeds the target voltage indicated by the dotted line even at the lowest ON duty. If this state continues, battery 4
Is overcharged, the voltage rises abnormally, an abnormal voltage is applied to the electric load of the vehicle, gas is generated from the battery 4, and the battery life is greatly shortened. In particular, when an abnormal voltage, that is, an overvoltage is applied to an electronic device mounted on a vehicle, an accident that cannot be recovered may occur, and the vehicle may not be able to travel.

In addition, when a large-capacity electric load is interrupted in a high-speed rotation range and the battery 4 shifts to a light load, an abnormal voltage appears remarkably. The duty ratio is high when a large electric load is used, and may be 100% in some cases. In such a state, even when the large-capacity electric load is cut off and the switching means 14 is cut off, it takes time for the field current to attenuate due to the time constant of the circuit formed by the flywheel diode 15 and the field coil 3. As a result, the generated voltage temporarily rises to an abnormal voltage.
Subsequently, even during the continuation of the abnormal voltage, the vehicular generator 1 is operated with the lowest ON duty, so that an increase in the generated voltage leads to an increase in the field current value, thereby extending the duration of the temporary abnormal voltage. In other words, the extension of the overvoltage time leads to an overvoltage accident.

SUMMARY OF THE INVENTION The present invention has been made to address such a problem. In the low-speed rotation range, a sufficient voltage for detecting the rotation speed and the power generation state is obtained. It is an object of the present invention to obtain a control device and a control method for a vehicle generator which does not exceed a target voltage.

[0011]

SUMMARY OF THE INVENTION A control device for a vehicle generator according to the present invention turns on a field current of the vehicle generator.
A switching element for OFF control, and a comparison result between a generated voltage of the vehicle generator and a reference voltage are converted into a PWM signal,
A PWM conversion circuit for driving a switching element and a duty ratio correction means for changing a minimum value of an ON duty of a PWM signal in accordance with a power generation state of a vehicle generator are provided.

Further, the duty ratio correction means reduces the minimum value of the ON duty as the rotational speed of the vehicle generator increases. Further, the duty ratio correction means is controlled by the output of an FV conversion circuit that converts the output frequency of the vehicle generator into a voltage. Furthermore, the generated voltage of the vehicle generator is compared with a second reference voltage higher than the reference voltage, and when the generated voltage is higher than the second reference voltage, the output of the PWM conversion circuit is invalidated. It is.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a circuit diagram showing a control device for a vehicle generator according to a first embodiment of the present invention. FIG. 2 is a characteristic diagram for explaining the generated voltage characteristics. Are given the same reference numerals. In FIG. 1, a vehicular generator 1 driven by an internal combustion engine (not shown) mounted on a vehicle is driven at an increased rotational speed of 1: 2, for example. The vehicle generator 1 includes a three-phase armature coil 2 and a field coil 3, and the output of the armature coil 2 is a diode D1.
, The battery 4 is charged via a full-wave rectifier circuit of a three-phase bridge composed of a power supply from the battery 4 and the armature coil 2, and the field magnetic flux of the vehicle generator 1 And the field current flowing through the field coil 3 is controlled by a control device 5 described later.

The control device 5 has the following configuration. The output voltage of the vehicle generator 1 is supplied from the terminal B to the voltage dividing resistors 6 and 7.
, And is divided, and further passes through a low-pass filter 8 that removes high-frequency components.
Added to terminal. The voltage of the power supply circuit 9 which is supplied with the voltage from the battery 4 and generates the power supply voltage of the control device 5 is applied to a series circuit of the voltage dividing resistors 10, 11 and 19, and the first reference voltage v 1 and the first A second reference voltage v2 having a higher value than the voltage v1 is generated, and the first reference voltage v1 is applied to the (-) terminal of the comparator 12. Comparator 1
2 compares the generated voltage passed through the low-pass filter 8 with the first reference voltage v1 and outputs an output voltage based on the comparison result as P
Output to the WM conversion circuit 13. The PWM conversion circuit 13 generates a PWM signal having a duty ratio corresponding to the output of the comparator 12 and supplies the PWM signal to the switching means 14, and the switching means 14 performs ON-OFF control of the field current based on the duty ratio.

The output voltage of the armature coil 2 is also supplied to an FV conversion circuit 16 for frequency-voltage conversion, and the FV conversion circuit 16 outputs a voltage proportional to the rotation speed of the vehicle generator 1. The power generation start rotation speed determination means 17, the gradual excitation control release rotation speed determination means 18, and the duty ratio correction means 20 for correcting the lowest duty ratio of the PWM conversion circuit 13 according to the power generation state of the vehicle generator 1. Output. Also,
The second reference voltage v2 is applied to the (-) terminal of the comparator 21, the generated voltage via the low-pass filter 8 is applied to the (+) terminal of the comparator 21, and the two are compared. The output voltage of the comparison result is The output of the PWM conversion circuit 13 is supplied to the base of the transistor 22 connected to invalidate the output. A flywheel diode 15 for absorbing an abnormal voltage when the field current is OFF is connected to the circuit of the field coil 3.

In the control device for a vehicle generator according to Embodiment 1 of the present invention, the output waveform of the comparator 12 includes the generated voltage and the first reference voltage v1.
The PWM conversion circuit 13 integrates the rectangular wave, generates a PWM signal having a duty ratio according to the integrated value, and generates a PWM signal having a duty ratio corresponding to the integrated value.
Is turned ON-OFF. Therefore, the generated voltage of the vehicle generator 1 is controlled to the target voltage corresponding to the first reference voltage v1. The PWM signal output from the PWM conversion circuit 13 has a predetermined frequency, and the duty ratio between the ON waveform and the OFF waveform is determined by the integrated value of the output of the comparator 12 as described above. A minimum value is set, and the minimum value is determined so that the next operation can be performed.

The control device 5 detects the power generation state such as the rotation speed at least at the cranking rotation speed of the internal combustion engine.
The minimum value of the ON duty is determined so as to be applied to the V conversion circuit 16. As a result, the FV
The conversion circuit 16 can output a voltage proportional to the rotational speed of the vehicular generator 1, and this voltage is used as the power generation start rotational speed determining means 17 and the gradual excitation control release rotational speed determining means 18.
And duty ratio correction means 20. As described in the above-described conventional example, the power generation start rotational speed determination unit 17 enables the output of the vehicle generator 1 before the internal combustion engine is started and before the idling rotational speed is reached. An operation for preventing a sudden increase is performed.

The duty ratio correction means 20 corrects the minimum value of the ON duty of the PWM conversion circuit 13 in accordance with the power generation state of the vehicle generator 1. The control includes a speed, a generated voltage, and the like. In the following description, control using a rotation speed at which correction control is easy is described. The duty ratio correction means 20 receives the voltage corresponding to the rotation speed from the FV conversion circuit 16 and corrects and controls the minimum value of the ON duty of the PWM conversion circuit 13.

At the cranking rotation speed of the internal combustion engine, since the generated voltage has not reached the target voltage, the duty ratio output from the PWM conversion circuit 13 is the minimum value of the ON duty. In this state, the minimum value of the ON duty is set so that an ON duty large enough to detect the rotation speed is output from the PWM conversion circuit 13. When the rotation speed is detected, the duty ratio correction means 20 starts operation, and controls so that the minimum value of the ON duty is decreased as the rotation speed increases. This control linearly decreases the minimum value of the ON duty as the rotational speed increases, as shown in the minimum duty characteristic diagram in FIG. 2, for example.

As described above, in the cranking rotation range, the ON duty is set to a value larger than the minimum value of the ON duty of the above-described conventional example, and in the high speed rotation range, the generated voltage becomes the target voltage at the normal maximum rotation speed. The ON duty value is set so as not to be reached. In the low-speed rotation range, the power generation state such as the rotation speed can be reliably detected, and in the high-speed rotation range, an overvoltage accident can be reliably prevented. In addition, as a load condition of the vehicle generator 1 in order to make the generated voltage in the high-speed rotation region equal to or lower than the target voltage, as shown in the no-load voltage characteristic of FIG. May be the case, the minimum load required to rotate the internal combustion engine,
For example, an ignition device or a fuel control device may be used as the load.

With this setting, the battery 4 is not overcharged while performing necessary control operations from the start to the normal maximum rotation speed. As described above, when the large-capacity load of the battery 4 is cut off in the high-speed rotation range, the generated voltage may exceed the target voltage. In the present invention, for this purpose, a comparator 21 for comparing the second reference voltage v2 with the generated voltage of the vehicle generator 1 is provided. If the generated voltage becomes equal to or higher than the second reference voltage v2, the comparator 2
The output of 1 becomes high level, the transistor 22 operates, the PWM signal is invalidated, and the switching means 14 is completely turned off.

With this configuration, when a large-capacity load is cut off, a temporary abnormal voltage is generated due to the time constant of the circuit formed by the flywheel diode 15 and the field coil 3, but the PWM signal is invalidated. Since the switching means 14 keeps the OFF state and there is no operation with the ON duty of the minimum value, the abnormal voltage does not continue more than the above time constant. Can be done.

[0023]

As described above, in the control device for a vehicle generator according to the present invention, according to the first aspect of the present invention, the switching element for ON-OFF controlling the field current of the vehicle generator. And a PWM conversion circuit that converts a comparison result between the generated voltage of the vehicle generator and the reference voltage into a PWM signal and drives a switching element, and an ON duty of the PWM signal corresponding to the power generation state of the vehicle generator. The duty ratio correction means for changing the minimum value is provided, so that the ON duty in the low-speed rotation range is set large to ensure the detection of the power generation state, and the ON duty is set in the region where the generation voltage is large. Can be controlled to be small, and an overvoltage accident due to overcharging of the battery can be avoided.

According to the second aspect of the present invention, the duty ratio correcting means decreases the minimum value of the ON duty as the rotational speed of the generator for the vehicle increases, so that the maximum use of the internal combustion engine can be achieved. The generated voltage does not exceed the target voltage up to the rotation speed, and an overvoltage accident due to overcharging of the battery can be reliably prevented. Furthermore, according to the third aspect of the invention, the duty ratio correction means is controlled by the output of the FV conversion circuit that converts the output frequency of the vehicle generator into a voltage, so that the power generation start rotation is controlled. The rotational speed detecting means conventionally used for power generation load control, such as the number determining means, can be used as it is.

Further, according to the present invention, the generated voltage of the vehicle generator is compared with the second reference voltage higher than the reference voltage, and when the generated voltage is higher than the second reference voltage. , The output of the PWM conversion circuit is invalidated, so that even when a large-capacity load is disconnected from the battery in the high-speed rotation range, the overvoltage generated does not continue, preventing overvoltage accidents in electronic devices and the like. Is what you can do.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a control device for a vehicle generator according to Embodiment 1 of the present invention.

FIG. 2 is an explanatory diagram illustrating power generation characteristics of a control device for a vehicle generator according to Embodiment 1 of the present invention.

FIG. 3 is a circuit configuration diagram of a conventional control device for a vehicle generator.

FIG. 4 is an explanatory diagram of a power generation characteristic of a conventional control device for a vehicle generator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Vehicle generator, 2 armature coil, 3 field coil, 4 battery, 5 control device, 6, 7, 10, 1
1, 19 voltage dividing resistor, 8 low-pass filter, 9 power supply circuit, 12, 21 comparator, 13 PWM conversion circuit, 14 switching element, 15 flywheel diode, 16 FV conversion circuit, 17 power generation start rotation number determination means, 18 Gradual excitation control release rotation speed determination means, 20
Duty ratio correction means, 22 transistors.

Continued on front page F term (reference) 5G060 AA04 CA03 DA01 5H590 AA01 AB01 AB04 CA07 CA23 CC01 CC18 CC24 CC28 CD01 CE05 DD25 DD64 EA07 EB02 EB21 FA06 FB01 FB03 FC12 FC17 FC21 GA02 HA02 HB06 JA08 JA13 JA19 JB05 JB06 JB09

Claims (4)

[Claims] 1. A field current of a vehicle generator is turned on and off.
A switching element to be controlled, a comparison result between the generated voltage of the vehicle generator and a reference voltage converted into a PWM signal, a PWM conversion circuit for driving the switching element, and a PWM conversion circuit corresponding to the power generation state of the vehicle generator. A control device for a vehicle generator, comprising: a duty ratio correction unit for changing a minimum value of an ON duty of a PWM signal. 2. The control device according to claim 1, wherein the duty ratio correction unit decreases the minimum value of the ON duty as the rotational speed of the vehicle generator increases. . 3. The apparatus according to claim 2, wherein the duty ratio correction unit is controlled by an output of an FV conversion circuit that converts an output frequency of the vehicle generator into a voltage. Control device for vehicle generator. 4. A power generation voltage of the vehicle generator is compared with a second reference voltage higher than the reference voltage, and when the power generation voltage is higher than the second reference voltage, an output of the PWM conversion circuit is output. The control device for a vehicle generator according to any one of claims 1 to 3, wherein the control device is invalidated.