JP2002135993A - Battery charger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid abrupt input torque change when changing the voltage boosting depending on the revolutions of a generator and prevent generator noise and vibration caused by the input torque fluctuations when changing its output power distribution to a high voltage battery or a low voltage battery. SOLUTION: When charging a low voltage battery BL, field-effect transistors Q1-Q3 are turned on to supply the output power of the generator ACG to the battery BL through rectifiers D1-D3. When charging a high voltage battery BH, the field-effect transistors Q1-Q3 are turned off to supply the output power of the generator ACG to the battery BH through rectifiers D4-D6. By switching the field-effect transistors Q4-Q6, the output of the generator ACG is turned on and off to control the duty ratio of the output of the generator so as to suppress the input torque fluctuation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a battery charger for charging a high-voltage battery and a low-voltage battery mounted on, for example, a hybrid vehicle.

[0002]

2. Description of the Related Art In recent years, hybrid vehicles equipped with a power system combining an engine and an electric motor have attracted attention from the viewpoints of environmental protection and energy saving. In this hybrid vehicle, various controls are performed, such as assisting the output of the engine by an electric motor during acceleration and charging the battery or the like by deceleration during deceleration, thereby efficiently assisting the engine output. ing. This hybrid vehicle has a high-voltage system (for example, 36 V) for supplying electric energy to an electric motor for traveling.
V) and a low-voltage (for example, 12 V) battery for supplying power to various auxiliary devices, and a battery charger for charging both batteries having different voltage specifications is required. It has been.

[0003] Hereinafter, this kind of conventional battery charger will be described with reference to FIG. 1 described later. The field-effect transistors Q4 to Q6 shown in FIG. 1 form part of the features of the battery charger according to the present invention described later, and correspond to the field-effect transistors in the conventional device described below. A rectifier (diode) is used, and the rectifier includes rectifiers D1 to D1.
3 or rectifiers D4 to D6 to form a full-wave rectifier.

In FIG. 1, an input shaft of a generator ACG is connected to an output shaft of an engine, and the input shaft of the generator ACG is rotated by an output of the engine to generate an AC output. This AC output is distributed to a low-voltage battery BL via a system (open regulator) including rectifiers D1 to D3 and field-effect transistors Q1 to Q3, and is also distributed to a high-voltage battery BH via rectifiers D4 to D6. It is distributed to. The distribution of the AC output of the generator ACG is based on the AC output of the generator ACG (U-phase, V-phase,
This is performed by controlling the conduction of the field-effect transistors Q1 to Q3 provided in the low-voltage side system in synchronization with the respective phases (W phase).

That is, as shown in FIG. 4, for example, in a period P1 in which the voltage of the U-phase generated by the generator ACG is high, the field-effect transistor Q1 is turned on and becomes conductive, and the rectifier D1 and the field-effect transistor Q1 are turned on. , The output of the U-phase is supplied to the low-voltage system battery BL.
At this time, the U-phase voltage is reduced by being pulled by the terminal voltage of the battery BL of the low-voltage system, but the rectifier D4 provided on the high-voltage system side is in a reverse-biased state, so that the output voltage of the generator is Does not discharge the high voltage battery BH. Thereafter, when the phase of the U phase is inverted and the output voltage is reduced in the period P2, the rectifier D1 enters a reverse bias state. At this time, in the conventional device, the battery BL is connected via a rectifier (not shown) corresponding to the field-effect transistor Q4.
Is charged.

Further, thereafter, in a period P3 in which the voltage of the U-phase becomes high, the field-effect transistor Q1 is turned off and becomes non-conductive. Thereby, the low-voltage battery B
The supply of power to L is cut off, and the U-phase voltage output from generator ACG increases. As a result, the rectifier D4
Are forward-biased, and the output power of the generator is supplied to the high-voltage battery BH via the rectifier D4.
Similarly, for the other V-phase and W-phase, rectifiers D2 and D2
D3 and the field effect transistors Q2, Q3 charge the low-voltage battery BL, and the rectifiers D5, D5
6, the battery BH of the high voltage system is charged.

As described above, by controlling the field effect transistors Q1 to Q3 on the low voltage side, the low voltage system and the high voltage system are charged complementarily, and both batteries are charged using one generator. It is possible to charge. In addition,
Which phase of the output of the generator is to be distributed to which of the low-voltage system and the high-voltage system is appropriately determined according to the state of charge of these batteries.

[0008]

When the engine speed is low and the output voltage of the generator is not sufficient, the output of the generator is boosted to secure the voltage required for charging, and the engine speed is reduced. There is a charging method in which the boosting is stopped and the battery is directly charged when the voltage rises. However,
As described below, according to the battery charger employing this type of charging method, when switching the presence or absence of boosting,
There is a problem that the torque required for rotationally driving the input shaft of the generator (hereinafter, referred to as “input torque”) rapidly changes, and abnormal noise is generated due to the torque fluctuation.

Hereinafter, the mechanism of occurrence of this kind of torque fluctuation will be described. FIG. 6 shows characteristics of the input torque and the output current (charging current) of the generator with respect to the rotation speed of the input shaft of the generator. The rotation speed of the generator changes according to the rotation speed of the engine. As shown in the drawing, when charging is performed by boosting the output of the generator (at the time of boosting charging), the voltage required for charging the battery in the low rotation speed region is ensured, so that the output current of the generator is reduced. It is consumed as charging current and generates input torque in the generator. As the rotational speed increases, the output current of the generator tends to increase, thereby increasing the input torque. However, an increase in output current is suppressed due to switching loss for boosting.

On the other hand, when charging is performed directly without increasing the output of the generator (at the time of direct charging), in the low rotation speed range,
Because the voltage needed to charge the battery is not available,
The battery is not charged and the output current does not appear as a charging current. Therefore, as the input torque of the generator, torque due to factors other than charging, such as mechanical friction and armature inertia, appears. When the engine speed increases and the output voltage reaches a chargeable voltage, the output current appears as a charging current. When the engine speed further increases, the output current increases and exceeds the output current at the point B during the boost charging. With the increase in the output current, the input torque also increases, and exceeds the input torque at the time of point C at the time of boost charging.
It should be noted that whether or not boosting is performed, that is, switching between boosting charging and direct charging can be performed by switching the switching duty for boosting.

Here, due to the difference in the control state between the boost charging and the direct charging, the rotation speed at the intersection B of the output current does not always match the rotation speed at the intersection C of the input torque. Therefore, for example, from the viewpoint of the voltage stability of the battery, if the rotation speed R (B) at the point B where the output current of the generator matches is selected as the rotation speed at which the switching between the presence and absence of boosting is performed, the difference Td of the input torque becomes As a result, the input torque of the generator rapidly changes, resulting in generation of abnormal noise. That is, in FIG.
The rotation speed starts increasing at time t1, and the rotation speed R at time t2.
When (B) is reached, the switching duty DR for boost switching is switched. As a result, the input torque T fluctuates rapidly due to the torque difference Td described above. Similarly, when the rotation speed drops, the time t6
, The input torque T fluctuates abruptly when exceeding the rotation speed R (B). As described above, when switching between the presence and absence of the boost, the input torque fluctuates rapidly, and abnormal noise occurs.

In addition to the above-described problem, as described below, when the output of the generator is divided between the low-voltage battery and the high-voltage battery, the input torque of the generator fluctuates. There is a problem that noise and vibration occur. That is, the input torque is determined by the output voltage and the output current of the generator, and there is a correlation between the input torque of the generator and the power consumed for charging. That is, if the output voltage of the generator is constant, the larger the charging current, the larger the input torque of the generator. If the output current of the generator is constant, the larger the charging voltage, the larger the input torque of the generator. growing. By applying a rotational force (for example, the rotational output of the engine) that can withstand the input torque to the input shaft of the generator from the outside, electric power as electric energy is generated.
Therefore, ideally, if the rotational force applied to the input shaft of the generator is constant, the output voltage and the output current should be determined so that the output power is constant.

However, in reality, even if the rotational force applied to the generator is constant, if the output voltage changes due to a change in load, the output current is controlled so that the output power is constant due to the characteristics of the generator. There is no response and the output power also tends to change. For this reason, as shown in FIG. 4, the magnitude of the input torque T is different between the period P1 during which the low-voltage battery is being charged and the period P3 during which the high-voltage battery is being charged. When the output is distributed to each battery, the input torque T fluctuates. For this reason, noise and vibration of the generator are generated, and silence and durability are impaired.

The present invention has been made in view of the above circumstances, and does not cause a sudden change in the input torque when switching the boosting according to the rotation speed of the input shaft of the generator. A first object is to provide a battery charging device capable of suppressing sound and vibration. Further, the present invention can effectively suppress the fluctuation of the input torque of the generator caused by distributing the output of the generator to each of the high-voltage system and the low-voltage system batteries. It is a second object of the present invention to provide a battery charger capable of preventing generation of noise and vibration.

[0015]

In order to solve the above-mentioned problems, the present invention has the following arrangement. That is, the battery charging device according to the present invention includes a generator that generates AC power (for example, a component corresponding to a generator ACG described later).
Allocating the output of the generator to the first battery of the low-voltage system at a timing synchronized with the output of the generator,
Charging system (for example, rectifiers D1 to D3 and field effect transistors Q1 to Q3 to be described later)
And the output of the generator is distributed to the second battery of the high voltage system at a timing synchronized with the output of the generator and different from the timing of charging the first battery. A second charging system (for example, rectifiers D4 to D
6), and when the number of revolutions of the input shaft of the generator is lower than the number of revolutions that determines whether to increase the output voltage of the generator, The output of the generator is intermittently boosted so as to suppress a change in the output power of the generator between the time of charging and the time of charging the second battery, and the rotation speed of the input shaft of the generator is reduced. A switch system (for example, a component corresponding to field-effect transistors Q4 to Q6 described later) that switches the duty while suppressing a change in the duty of the output of the generator when the rotation exceeds the rotation speed giving the boundary; It is characterized by having.

According to this configuration, when the rotation speed of the input shaft of the generator changes beyond the rotation speed giving the boundary,
The switch system switches the duty while suppressing a change in the duty of the generator output. For example, when the rotation speed of the input shaft of the generator increases and becomes a value larger than the rotation speed that gives the boundary, the switch system gradually changes the duty of the output of the generator.
The output power of the generator also gradually changes in accordance with the change in the duty, and becomes a value corresponding to the duty switched by the switch means. Therefore, since the output power does not change rapidly, the fluctuation of the input torque is also reduced, and as a result, generation of abnormal noise is prevented. If the rotation speed increases, the output of the generator increases, and the output power changes.In this case, the change in the output power is in accordance with the rotation speed.
It does not cause fluctuation of the input torque.

When the rotation speed of the input shaft of the generator is lower than the rotation speed giving the boundary (ie, when the rotation speed is low), the output of the generator is intermittently operated by the switch system, By controlling the duty, the output power of the generator is adjusted and the input torque of the generator is controlled while maintaining the output voltage of the generator at a voltage at which the second battery of the high voltage system can be charged. Therefore, if the output duty of the generator is set appropriately, the input torque when charging the battery on the low voltage side is equal to the input torque when charging the battery on the high voltage side. Become. Therefore, the fluctuation of the input torque generated when the output of the generator is divided between the high-voltage battery and the low-voltage battery is effectively suppressed, and the generation of noise and vibration due to the fluctuation of the input torque is prevented. It is possible to do. The output of the generator may be boosted by the switching operation of the switch system.

In the battery charger, the first charging system may include a first charging system in which an anode is connected to an output terminal of the generator and a cathode is connected to an electrode of the first battery. A rectifier (for example, a component corresponding to rectifiers D1 to D3 to be described later) and a rectifier are provided between a cathode of the first rectifier and an electrode of the first battery, at a timing at which the first battery is to be charged. A first field-effect transistor (for example, a field-effect transistor Q1 to be described later) that is turned on and turned off at the timing when the second battery is to be charged.
A second charging system, wherein an anode is connected to an output terminal side of the generator and a cathode is connected to an electrode side of the second battery. Rectifier (for example, rectifiers D4 to D6 described later)
And the switch system includes:
A second field effect transistor (eg, field effect transistors Q4 to Q4 to be described later) which is provided between an output terminal of the generator and ground and switches on and off the output of the generator based on the clock signal having the duty.
6).

According to this configuration, when the first field-effect transistor is turned on and becomes conductive, the first rectifier is in a forward-biased state, and the output of the generator is reduced to a low voltage via the first rectifier. The battery is distributed to the first battery of the system, and the first battery is charged. On the other hand, when the first field-effect transistor is turned off and becomes non-conductive, the output voltage of the generator rises, and as a result, the second rectifier is brought into a forward-biased state, and power is generated via the second rectifier. The output of the machine is distributed to the second battery of the high-voltage system, and the second battery is charged.

At this time, when the rotation speed of the input shaft of the generator changes beyond the rotation speed giving the boundary, the second field-effect transistor switches based on the clock signal and supplies the second battery to the second battery. The duty of the output of the generator to be switched is changed gradually. Thereby, the output power of the generator also changes gradually. Therefore, even if the duty of the output of the generator is switched according to the change in the number of revolutions, the output power of the generator changes slowly,
The input torque does not change abruptly, and noise and vibration due to the change in the input torque are prevented.

Further, in the battery charger,
The conduction of the second field-effect transistor is controlled according to a change in the output phase of the generator when the first battery is charged, and the conduction is controlled based on the clock signal when the second battery is charged. (For example, an element corresponding to the function of the control unit CTL described later). According to this configuration, when the first battery is charged, the first rectifier and the second field-effect transistor form a full-wave rectifier, and the output of the generator is full-wave rectified and supplied to the first battery. I do. When charging the second battery, the second rectifier and the second field-effect transistor form a full-wave rectifier, and the second field-effect transistor causes the output current of the generator to approximate a sine wave. Function as a switch system. As a result, the output of the generator can be allocated to the low-voltage battery and the high-voltage battery while suppressing the fluctuation of the input torque of the generator.

Further, in the battery charger, the generator may be a multi-phase alternating current (for example, a U-phase or V-phase
, And W-phase three-phase alternating current), the first and second rectifiers and the first and second rectifiers.
The field effect transistor is provided for each phase of the polyphase alternating current. According to this configuration, each phase of the output of the generator is supplied to the battery via the independent charging path. Therefore, it is possible to suppress the interference in the charging path and the current density of each charging path, and to stabilize the charging operation.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. The battery charger according to the present embodiment charges both a high-voltage system battery and a low-voltage system battery mounted on a hybrid vehicle, and boosts the output of a generator according to the engine speed. It has a function of charging a high-voltage battery while switching between presence and absence. FIG. 1 shows a configuration of a battery charging device according to an embodiment of the present invention. In the figure, ACG is 3
It is a generator that generates phase alternating current (U phase, V phase, W phase).
An input shaft of the generator ACG is connected to an output shaft of the engine, and a torque is applied from the engine. L
F is a field coil of the generator, and CNV is a low voltage system (for example, 12
[V]) of the battery BL and the high-voltage system (for example, 42
[V]) is a converter for distributing to the battery BH.

In the converter CNV, D1
D3 is a rectifier for rectifying the AC output of the generator ACG and supplying the rectified output to the battery BL on the low voltage side, and Q1 to Q3 are field effect transistors (n-type) for controlling the output destination of the output of the generator ACG. The rectifiers D1 to D3 and the field effect transistors Q1 to Q3 constitute a first charging system for charging the low-voltage battery BL. D4 ~
D6 is a rectifier for rectifying the AC output of the generator ACG and supplying the rectified output to the battery BH on the high voltage side, and constitutes a second charging system for charging the battery BH on the high voltage system. Q
Reference numerals 4 to Q6 denote field effect transistors (n-type) for boosting the output voltage of the generator ACG, and constitute a switch system for intermittently chopping the output voltage of the generator. These field effect transistors Q4 to Q6
Forms a full-wave rectifier together with the rectifiers D1 to D3 on the low voltage side or the rectifiers D4 to D6 on the high voltage side.

CTL is composed of field effect transistors Q1 to Q
6 is a control unit for controlling the conduction of 6. This control unit CTL
Determines the necessity of boosting the output of the generator ACG according to the engine speed when controlling the conduction of the field effect transistors Q1 to Q6, and switches the field effect transistors Q1 to Q6 when the boosting is required. Let it work. D7 is a diode, and Q7 is a field-effect transistor, which adjusts the amount of current flowing through the field coil LF under the control of the control unit CTL. Thus, each rectifier and each field-effect transistor forming a charging path are provided for each of the U-phase, V-phase, and W-phase generated by the generator ACG.

In this embodiment, the control unit CTL
Controls the presence / absence of boosting at a rotational speed Rt where the output current during direct charging exceeds the output current during boosting charging, as shown in FIG. 6 described above. Specifically, the control unit CTL
In the region below the rotation speed Rt, the field-effect transistors Q4 to Q6 are switched to boost the output of the generator, and in the region above the rotation speed Rt, the switching operation is stopped. This rotation speed Rt is appropriately set based on the characteristics shown in FIG. 6 as a boundary for determining whether to increase the output voltage of the generator ACG. From the viewpoint of battery voltage stability, the rotation speed Rt is preferably near the intersection B, but is higher than the rotation speed R (B) because the output current characteristic during direct charging is not stable. Set to rotation side.

Next, the connection relationship between the components will be specifically described. The anodes of the rectifiers D1 to D3 are connected to the generator ACG
Output terminal. Field effect transistors Q1
Q3 is provided between the cathodes of the rectifiers D1 to D3 and the positive electrode of the battery BL, and is turned on at the timing to charge the battery BL and is turned off at the timing to charge the battery BH. Rectifiers D4 to D
6 is connected to the output terminal of the generator ACG,
Its cathode is connected to the positive electrode of battery BH.

The field effect transistors Q4 to Q6 are provided between the output terminal of the generator ACG and the ground. The field effect transistors Q4 to Q6 switch based on the clock signal CLK from the control unit CTL to switch the generator A
It functions as an intermittent CG output. The duty of the clock signal CLK is set so as to suppress fluctuations in output power when the output of the generator ACG is distributed to each battery. However, as described later, when switching the duty of the clock signal CLK, the control unit CTL switches gently while suppressing the change of the duty when controlling the presence or absence of the boost. In addition,
In this embodiment, the duty of the clock signal CLK means that in one cycle of the clock signal CLK,
It means the ratio occupied by the pulse width for turning off the field effect transistor Q4 (Q5, Q6). Therefore, the clock signal CLK is supplied to the boosted generator AC
The duty of the G output pulse is given. In this embodiment, the duty of clock signal CLK and generator ACG
The output duty is a synonym. However, the duty of the clock signal CLK and the generator ACG
Does not have to be the same as the output duty, and it is sufficient if there is a certain relationship between these duties.

Hereinafter, the operation of the battery charger according to this embodiment will be described. In this embodiment, it is assumed that the generator ACG can generate a voltage that can charge the low-voltage battery BL without boosting. Also,
The operation of the battery charging apparatus according to the present embodiment is the same for each of the U-phase to W-phase, and therefore the description will be made focusing on the U-phase. Further, for the sake of convenience of explanation, the region below the above-mentioned rotation speed Rt is referred to as “low rotation region”, and the region above this rotation speed Rt is referred to as “high rotation region”. Furthermore, the rotation speed of the engine and the rotation speed of the input shaft of the generator are treated as synonyms.

(1) Operation in the Low Rotation Range When the rotation speed of the engine (the rotation speed of the input shaft of the generator) is equal to or lower than the rotation speed Rt, the battery is not boosted when charging a low-voltage battery. The output of the generator ACG is boosted only when charging the high-voltage battery BH. FIG. 2 shows the output waveforms (U-phase, V-phase, W-phase) of the generator and the waveform of the input torque T in the low rotation range. First, the low-voltage battery BL
Will be described. The control unit CTL includes the generator A
Each phase of the CG U-phase to W-phase is detected, and the field-effect transistor Q1
To Q3. Specifically, the control unit CTL turns on the field-effect transistor Q1 at the start point of the period P1 during which the U-phase voltage increases. When the field effect transistor Q1 is turned on, the generator AC is connected via the rectifier D1.
The output of the U phase of G is supplied to the positive electrode of the low-voltage battery BL. As a result, the output of the generator ACG is changed to the low-voltage battery B at the timing synchronized with the output of the generator ACG.
L and the battery is charged.

Thereafter, in the period P2, when the phase of the U-phase of the generator is switched and the voltage drops, the control unit CTL
Turns on the field effect transistor Q4. here,
Since the negative electrode of the battery BL and the source of the field effect transistor Q4 are both connected via the ground, the generator ACG charges the battery BL via the field effect transistor Q4 forming a full-wave rectifier. Thus, a full-wave rectifier is formed using the field effect transistor Q4,
By controlling the conduction of this transistor in accordance with the phase change of the output of the generator, the field-effect transistor Q4 is compared with a conventional full-wave rectifier comprising only a rectifier.
The charging efficiency is improved by the small voltage drop in the. As described above, the conduction of the field effect transistor Q4 is controlled according to the change in the output phase of the generator ACG when the low-voltage battery BL is charged, and the switching operation by the clock signal is not performed.

Next, the operation for charging the high voltage battery BH will be described. The control unit CTL includes a generator ACG
The field effect transistor Q1 is turned off at the start point of the period P3 during which the voltage of the U-phase becomes high, and a clock signal CLK having a predetermined duty, which will be described later, is applied to the gate of the field effect transistor Q4 to switch the field effect transistor Q4. Let it work. Thereby, the generator A
The output voltage of the CG is boosted and supplied to a high-voltage battery BH, which is charged.

That is, while the field effect transistor Q4 is on, a current flows through the armature coil of the generator ACG, and electric energy is stored in the armature coil. The electric energy stored during this period is discharged while being superimposed on electric energy newly generated by the generator ACG while the field effect transistor Q4 is off, and the output voltage of the generator ACG is boosted. As a result, the rectifier D4 is brought into a forward bias state, and the U-phase output of the generator ACG is supplied to the positive electrode of the high-voltage battery BH via the rectifier D4.
In this manner, the output of the generator ACG is allocated to the charging of the battery BH at a timing synchronized with the output of the generator ACG and at a timing different from the timing of charging the low-voltage battery BL described above.

When the field effect transistor Q4 switches based on the switching control clock signal CLK, the output voltage of the generator ACG is interrupted, so-called chopping is performed. By adjusting the duty of the clock signal CLK, as described later, the output power of the generator ACG is adjusted and the generator ACG is adjusted.
Of the input torque T can be kept small. As described above, when the high-voltage system battery BH is charged, the conduction of the field-effect transistor Q4 is controlled based on the clock signal CLK from the control unit CTL, so that the output voltage of the generator ACG is increased and the input of the generator ACG is increased. It functions to suppress fluctuations in torque.

Referring to FIG. 3, the generator AC is changed according to the duty of the switching control clock signal CLK.
The principle of suppressing the change in the input torque of G will be described. As described above, the input torque of the generator ACG is
It depends on the power required to charge L and BH. Conversely,
If the change in the output power (charging power) of the generator ACG can be kept small on condition that the voltages required for charging the high-voltage system and the low-voltage system are secured, respectively, The fluctuation of the input torque can be reduced, and moreover, both batteries can be charged.

Here, as shown in FIG. 3, when the high-voltage battery BH is being charged, the input torque T is such that the duty DR of the clock signal CLK for controlling the switching of the field-effect transistor Q4 is large. It shows a tendency to increase with the increase. On the other hand, when the battery BL of the low voltage system is being charged, the switching of the field effect transistor Q4 by the clock signal CLK is not performed, and the input torque T at this time is the clock signal CL.
It is constant without depending on the duty DR of K. Therefore,
There is an intersection A between the characteristic line at the time of charging the high-voltage system and the characteristic line at the time of charging the low-voltage system. At this intersection A, the input torque T between the high-voltage system charging and the low-voltage system charging is determined. Are equal.

Therefore, the duty DR (A) at the intersection A is set as the duty DR of the clock signal CLK, and in this state, the field effect transistor Q4 performs a switching operation to interrupt the output voltage of the generator ACG. For example, when charging the high voltage system and charging the low voltage system, the generator A
The output power of the CG becomes substantially equal, and therefore, the difference d of the input torque T becomes smaller. Therefore, the fluctuation of the input torque T generated when the output of the generator ACG is divided between the low-voltage battery BL and the high-voltage battery BH is suppressed,
The generation of vibration and noise of the generator due to the fluctuation of the input torque T is prevented. As described above, the field effect transistor Q4 interrupts the output of the generator ACG to be distributed to the battery BH so as to suppress the fluctuation of the output power of the generator ACG (that is, the input torque of the generator).

As in the above-described U-phase, each battery is charged by the V-phase and the W-phase. In this case, the rectifier D
2 and D3 function similarly to the above-described rectifier D1, and the field-effect transistors Q2 and Q3 function similarly to the above-described field-effect transistor Q1. The rectifiers D5 and D6 function in the same manner as the rectifier D4 described above,
5, Q6 function similarly to the above-mentioned field effect transistor Q4.

(2) Operation in High Speed Range When the engine speed exceeds the above speed Rt, the switching control of the field effect transistors Q4 to Q6 is not performed, and either the high voltage system battery or the low voltage system battery is operated. When charging, as described above, the operation is the same as when charging the low-voltage battery in the low rotation range. This allows
As shown in FIG. 4, for example, in the charging period P1, the low-voltage battery is charged in the U phase of the generator ACG, and in the charging period P3, the high-voltage battery is similarly charged. At this time, the voltage waveform of the U phase has a peak corresponding to the terminal voltage of each battery.

In this embodiment, the boosting is stopped in the high rotation region, for the following reason. a. When the rotation speed increases, the output voltage of the generator required for charging can be obtained without boosting. b. Loss current is generated by the switching operation of the field effect transistors Q4 to Q6, and the charging efficiency is reduced. c. When the engine speed increases, the noise and vibration of the engine and the like increase, so that the merit of suppressing the noise and vibration generated by the generator decreases.

(3) Operation when shifting from low rotation range to high rotation range Next, with reference to FIG. 5, an operation when the engine speed changes beyond the above-mentioned speed Rt will be described. . In this case, as described below, the field effect transistor Q4
When charging a high-voltage battery under the control of the control unit CTL, Q6 to Q6 switch the output duty of the generator ACG while suppressing a change in the output duty. The following description focuses on high-voltage batteries.

In FIG. 5, before time t1, the rotational speed R is in a low rotational speed range below the rotational speed Rt, and as shown in FIG. Battery BH is charged. At this time, the field effect transistor Q4 has a duty D set to suppress the fluctuation of the input torque when distributing the output of the generator.
Switching is performed based on the clock signal CLK of R (A) to interrupt the output of the generator ACG, and control the output power of the generator ACG so as to suppress the fluctuation of the input torque T.
Subsequently, when the rotation speed of the engine starts increasing at time t1, the output power (not shown) of the generator ACG also starts increasing, and the input torque T increases in accordance with the increase in the output power.

Subsequently, at time t2, the rotational speed R becomes equal to the rotational speed Rt.
The control unit CTL changes the duty DR of the clock signal CLK from the duty DR (A) to the duty D.
Gradually decrease toward R (0). Here, the duty DR (0) is a value to be set in a high rotation range, and is set to zero in this embodiment. When the duty DR gradually decreases, the duty of the output of the generator gradually decreases. In other words, according to the change in the duty of the clock signal CLK, the change in the duty of the output of the generator is reduced while being suppressed. As a result, the output power of the generator gradually increases, and the input torque T gradually increases. That is, the fluctuation of the input torque T is suppressed to be small.

Subsequently, when the rotation speed R is stabilized in the high rotation range at the time t3, the output power does not increase with the increase in the rotation speed, so that the input torque T continues to increase as the duty DR of the clock signal CLK decreases. . Subsequently, at time t
When the duty DR reaches the duty DR (0) at 4, the clock signal CLK is fixed at a low level. For this reason, the field effect transistor Q4 is not in the switching state and is stabilized in the off state. Therefore, as shown in FIG. 4, even when charging the battery on the high voltage side, the boosting of the output of the generator ACG is stopped, and this output is distributed to the high voltage system battery BH via the rectifier D4.

Subsequently, when the rotation speed R starts decreasing at time t5, the output power of the generator ACG decreases, and the input torque T starts to decrease gradually. Subsequently, at time t6, the rotational speed R
Reaches the rotation speed Rt, the control unit CTL gradually increases the duty DR of the clock signal CLK from the duty DR (0) to the duty DR (A). At this time, the output power of the generator tends to further decrease because the duty DR decreases in addition to the decrease in the rotation speed R described above. However, since the change in the duty DR is gradual, the output power sharply increases. It does not change, so the input torque T continues to decrease slowly. Subsequently, when the rotation speed R is stabilized in the low rotation range at time t7, the input torque T becomes the duty D
Continue to decrease with increasing R. Then, when the duty DR reaches the duty DR (A) at time t8, the input torque T stabilizes to a constant.

As described above, under the control of the control unit CTL,
When the rotation speed R of the input shaft of the generator ACG is lower than the rotation speed Rt that determines whether or not to boost the output voltage of the generator, the field-effect transistor Q4 detects the low-voltage battery BL. The output of the generator ACG is intermittently boosted so as to suppress a change in the output power of the generator between the time of charging and the time of charging of the high-voltage battery BH. And generator A
When the rotation speed R of the input shaft of the CG changes beyond the rotation speed Rt, the clock signal CLK for controlling the switching operation of the field effect transistor Q4 is controlled so that the change in the duty of the output of the generator ACG is suppressed. Duty D
Switch R. As a result, the change in the input torque when switching between the presence and absence of the boost according to the rotation speed becomes gentle,
The fluctuation of the input torque is suppressed to a small level. Therefore, generation of abnormal noise due to this kind of torque fluctuation is prevented.

As described above, the output of the generator ACG is distributed to the low-voltage system battery BL and the high-voltage system battery BH while suppressing the fluctuation of the input torque of the generator ACG. Is controlled by the field current flowing through the field coil LF in accordance with the state of charge of each battery. That is, if the battery to be charged is in a fully charged state, no charging power is required, and thus the control unit CTL controls the switching of the field effect transistor Q7 to reduce the field current and suppress the power generation. Conversely, if the battery is not charged, the control unit CTL increases the field current to increase the amount of power generation. As described above, according to the battery charger according to the present embodiment, the amount of power generated by generator ACG is appropriately controlled in accordance with the state of charge of each battery while suppressing fluctuations in input torque. Therefore, it is possible to efficiently charge each battery while suppressing the generation of vibration and noise due to the fluctuation of the input torque.

Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and the present invention is applicable to any design change or the like without departing from the gist of the present invention. included. For example, in the above-described embodiment, when charging a low-voltage battery, the output of the generator is not boosted, and when charging a high-voltage battery, the presence or absence of the boost is determined according to the rotation speed. Although switching is performed, the present invention is not limited to this. For example, a low-voltage battery may be charged by switching between the presence and absence of boosting according to the number of revolutions.

In the above embodiment, the generator AC
The output of G is divided into a low-voltage battery BL and a high-voltage battery BH to charge both batteries. However, the present invention is not limited to this. Alternatively, only the high-voltage battery may be charged while switching, or similarly, only the low-voltage battery may be charged.

The boosting field effect transistor Q4
To Q6, the generator ACG
However, if it is not necessary to increase the output voltage of the generator ACG, the rectifiers D4 to D6 are connected between the output terminal of the generator ACG and the electrode of the high-voltage battery BH. The field effect transistors Q4 to Q6 may be connected in series. In this case, by switching the transistors Q4 to Q6, the charging power supplied to the battery is intermittently suppressed, and the input torque of the generator ACG is adjusted.

In the above-described embodiment, the field effect transistors Q1 to Q3 are provided. However, the present invention is not limited to this, and the cathodes of the rectifiers D1 to D3 are commonly connected.
One field effect transistor corresponding to the field effect transistors Q1 to Q3 may be provided between the commonly connected cathode and the battery BL. Furthermore, in the above-described embodiment, the output of the generator ACG is supplied to the high-voltage battery BH via the rectifiers D4 to D6. However, the present invention is not limited to this.
Instead of 4-D6, a field-effect transistor whose conduction is complementarily controlled with respect to the field-effect transistors Q1-Q3 may be employed. Furthermore, in the above embodiment,
Although n-type field-effect transistors are used as the field-effect transistors Q1 to Q6, the present invention is not limited to this.
It is also possible to use a field effect transistor. In the present invention, which cycle of the output of the generator ACG is allocated to which of the low-voltage system and the high-voltage system is not particularly limited, and a system to which the battery charger is applied is not limited. May be negotiated as appropriate.

[0052]

As described above, according to the present invention, the following effects can be obtained. That is, since the duty is switched while suppressing the change in the duty of the output of the generator, the input torque does not fluctuate rapidly when the boost is switched according to the rotation speed of the input shaft of the generator. Abnormal noise caused by torque fluctuation can be suppressed, and a change in the output power of the generator between the time of charging the first battery of the high voltage system and the time of charging of the second battery of the low voltage system can be suppressed. Therefore, fluctuations in the input torque of the generator due to distribution of the output of the generator between the high-voltage system and the low-voltage system batteries can be effectively suppressed. Therefore, abnormal noise caused by the fluctuation of the input torque,
Generation of noise, vibration, and the like can be prevented, and the quietness and durability of the generator are improved.

In the battery charger, the first charging system may include a first rectifier connected between an output terminal of the generator and an electrode of the first battery, and a first rectifier. A first field-effect transistor provided between a cathode of the first battery and an electrode of the first battery,
As the second charging system, a second rectifier connected between the output terminal side of the generator and the electrode side of the second battery is provided. As the switch system, the output terminal of the generator is connected to ground. The second field-effect transistor provided between the second battery and the switching device, so that the output of the generator supplied to the second battery is interrupted, and the fluctuation of the output duty and input torque of this generator is suppressed. Thus, the output power can be adjusted.

Further, in the battery charger,
The second field effect transistor conducts according to the phase change of the output of the generator when charging the first battery, and conducts based on the clock signal when charging the second battery. It is possible to distribute the output of the generator to the low-voltage battery and the high-voltage battery while suppressing the fluctuation of the power.

Further, in the battery charger, the generator may be a multi-phase alternating current (for example, a U-phase or V-phase
, And W-phase three-phase alternating current), the first and second rectifiers and the first and second rectifiers.
Is provided for each phase of the polyphase alternating current, so that each phase of the output of the generator can be supplied to the battery via an independent charging path. Therefore, it is possible to suppress the interference in the charging path and the current density in each charging path, and to stabilize the charging operation.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a battery charging device according to an embodiment of the present invention.

FIG. 2 is a waveform chart for explaining an operation (during low rotation) of the battery charger according to the embodiment of the present invention;

FIG. 3 is a characteristic diagram for explaining the operation principle of the battery charging device according to the embodiment of the present invention.

FIG. 4 is a waveform diagram for explaining an operation (at a high rotation speed) of the battery charger according to the embodiment of the present invention;

FIG. 5 is a waveform diagram for explaining the operation (at the time of change in rotation speed) of the battery charger according to the embodiment of the present invention;

FIG. 6 is a diagram for explaining the mechanism of torque fluctuation that occurs when switching between the presence and absence of boosting according to the number of revolutions.

FIG. 7 is a waveform diagram for explaining the operation (at the time of change in rotation speed) of the battery charging device according to the related art.

[Explanation of symbols]

 ACG: Generator BH: High-voltage battery BL: Low-voltage battery CTL: Control unit CNV: Converter D1-D7: Rectifier LF: Field coil Q1-Q7: Field effect transistor (n-type)

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02J 7/02 H02J 7/02 J H02P 9/30 ZHV H02P 9/30 ZHVD (72) Inventor Masaharu Kaneko Saitama (13) Inventor Kazuyuki Kubo 1-4-1 Chuo, Wako-shi, Saitama Pref.Honda R & D Co., Ltd. (72) Inventor Tadashi Fujiwara 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (reference) 5G003 AA07 BA04 FA06 GB02 5G060 AA04 BA06 BA08 CA13 DA01 5H030 AS08 AS20 BB01 BB10 BB21 5H115 PA05 PC06 PG04 PI14 PI16 PI24 PI29 PI30 PO02 PO06 PO17 PU10 PU24 PU25 PV03 PV07 PV09 PV24 QE02 QE03 QE08 QE10 QI04 RB22 SE04 SE05 TB01 TE02 TI02 TO13 TO30 5H590 AA06 AA15 CA07 CA23 CC01 CC18 CC24 CD01 CE05 DD25 DD64 DD72 EA07 EB12 EB14 EB21 FA06 FB01 FB03 FC14 GA02 HA02 HA10 HA27 JB14

Claims (4)

[Claims] A generator for generating alternating-current power; and a generator for charging the first battery by distributing an output of the generator to a first battery of a low-voltage system at a timing synchronized with an output of the generator. And the output of the generator is distributed to the second battery of the high voltage system at a timing synchronized with the output of the generator and at a timing different from the timing of charging the first battery. A second charging system for charging a second battery, wherein the rotation speed of the input shaft of the generator is lower than the rotation speed that gives a boundary as to whether or not to boost the output voltage of the generator; The output of the generator is intermittently boosted so as to suppress a change in the output power of the generator between the time of charging the first battery and the time of charging the second battery. The number of revolutions of the And a switch system for switching the duty while suppressing a change in the output duty of the generator when the number of rotations exceeds the number of turns. 2. A first rectifier having an anode connected to an output terminal side of the generator and a cathode connected to an electrode side of the first battery, wherein the first charging system includes: Is provided between the cathode of the rectifier and the electrode of the first battery, and is turned on at the timing to charge the first battery and is turned off at the timing to charge the second battery. A first field-effect transistor, wherein the second charging system has an anode connected to the output terminal side of the generator and a cathode connected to the electrode side of the second battery. 2 rectifier, provided as the switch system, between the output terminal of the generator and ground, and switching based on a clock signal having the duty to output the output of the generator. By battery charging apparatus according to claim 1, further comprising a second field effect transistor in which chopped. 3. The conduction control of the second field-effect transistor according to a change in the output phase of the generator when the first battery is charged, and the conduction control based on the clock signal when the second battery is charged. The battery charging device according to claim 2, wherein the charging is performed. 4. The generator according to claim 1, wherein the generator generates a polyphase alternating current, and the first and second rectifiers and the first and second field effect transistors are provided for each phase of the polyphase alternating current. The battery charger according to claim 2, wherein the battery charger is provided.