JP6186180B2 - Battery charging device and battery charging control method - Google Patents

Description

  The present invention relates to a battery charging device and a battery charging control method.

  A battery charging device including a reverse connection prevention circuit for preventing overcurrent due to reverse connection of a battery is known (Patent Document 1). The reverse connection of the battery refers to a state where the negative electrode of the battery is connected to the high voltage terminal of the battery charging device and the positive electrode of the battery is connected to the low voltage terminal of the battery charging device.

  In FIG. 5, the structural example of the battery charging device by a prior art is shown. The battery charging device shown in the figure is for charging a battery B by generating a desired DC voltage from the AC output voltage of the AC generator G. The rectifying unit 2, the voltage adjusting unit 3, the control unit 4, and the reverse connection prevention A circuit 5 is provided. The rectification unit 2 is for rectifying the AC output voltage of the AC generator G, and is composed of a full bridge circuit. The high voltage output node of the full bridge circuit is connected to the high voltage terminal T1 via the high voltage line HL, and the low voltage output node is connected to the low voltage terminal T2 via the low voltage line LL. The positive electrode of the battery B is connected to the high voltage terminal T1, and the negative electrode of the battery B is connected to the low voltage terminal T2. The example of FIG. 5 shows a state in which the battery B is normally connected to the battery charging device.

The voltage adjusting unit 3 is for adjusting the AC output voltage generated by the AC generator G, and is connected between the input node of the full bridge circuit constituting the rectifying unit 2 and the low voltage line LL. It has a thyristor.
The control unit 4 adjusts the voltage so that the voltage between the high voltage output node and the low voltage output node of the full bridge circuit constituting the rectification unit 2 (that is, the output voltage of the rectification unit 2) becomes a desired voltage. This is for controlling the conduction of the thyristor constituting the part 3.

  The reverse connection prevention circuit 5 is for preventing an overcurrent due to the reverse connection of the battery B, and includes an n-channel field effect transistor M1 and resistors R1 and R2. A body diode D1 is formed between the source and drain of the field effect transistor M1. The current path of the field effect transistor M1 is inserted on the low voltage line LL. That is, the source of the field effect transistor M1 is connected to the low voltage output node of the rectifying unit 2, and the drain thereof is connected to the low voltage terminal T2. The resistors R1 and R2 are for biasing the gate of the field effect transistor M1, and are connected in series between the high voltage terminal T1 and the source of the field effect transistor M1. A gate of the field effect transistor M1 is connected to a connection point between the resistor R1 and the resistor R2.

  According to the above battery charger, the AC output voltage of the AC generator G is adjusted by the voltage adjustment unit 3 and rectified by the rectification unit 2 under the control of the control unit 4. As a result, a DC voltage is generated between the high voltage line HL and the low voltage line LL, and the voltage of the high voltage line HL becomes higher than the low voltage line LL. Here, when the battery B is normally connected to the battery charging device, the voltage of the gate of the field effect transistor M1 connected to the connection point between the resistor R1 and the resistor R2 is higher than the voltage of the source. Thus, the field effect transistor M1 is turned on. Thereby, the low voltage output node of the rectifier 2 is electrically connected to the low voltage terminal T2 via the field effect transistor M1. Therefore, in this case, the DC voltage generated between the high voltage line HL and the low voltage line by the rectifier 2 is supplied to the battery B via the high voltage terminal T1 and the low voltage terminal T2, thereby Charging is performed.

  On the other hand, when the battery B is reversely connected, that is, when the negative electrode of the battery B is connected to the high voltage terminal T1 and the positive electrode of the battery B is connected to the low voltage terminal T2, the low voltage line LL is connected. On the other hand, the voltage of the high voltage line HL is lowered. As a result, the voltage of the gate of the field effect transistor M1 connected to the connection point between the resistor R1 and the resistor R2 becomes lower than the voltage of the source, and the field effect transistor M1 is turned off. Therefore, in this case, the low voltage terminal T2 to which the positive electrode of the battery B is connected is electrically disconnected from the low voltage node of the rectifying unit 2, thereby preventing overcurrent due to the reverse connection of the battery B. Here, if the reverse connection prevention circuit 5 is not provided, each diode of the full bridge circuit constituting the rectifying unit 2 is forward-biased by the battery B, so that an overcurrent is generated. May affect charger.

JP 2009-118607 A

  According to the above-described prior art, when the rotation of the alternator G stops and the battery B is no longer charged, it passes through the current path formed by the resistor R1, the resistor R2, and the body diode D1 of the field effect transistor M1. Discharge current Id flows from the positive electrode of battery B toward the negative electrode. For this reason, the battery B may be discharged, and the battery voltage may decrease.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a battery charging device and a battery charging control method capable of suppressing a discharging current of a battery when a generator is stopped.

A battery charging device according to an aspect of the present invention is a battery charging device that is connected between a generator and a battery, rectifies an output voltage of the generator to generate a DC voltage, and charges the battery with the DC voltage. And detecting a rotation stop of the generator, and when the detection unit detects a stop of the rotation of the generator, the discharge path of the battery formed inside the battery charging device is cut off. A shut-off unit comprising a transistor that is a first switch element having a current path inserted in a discharge path of the battery, and the detection unit outputs an output voltage of the generator There a second switching element for driving the first switching element to the off state when the voltage after being rectified is below a predetermined value, the second switch element, to the oFF state Ri blocking a portion of the discharge path of the battery, with the configuration of the battery charging device characterized by blocking the remaining portion of the discharge path of the battery by the first switching element to off state.

A battery charging control method according to an aspect of the present invention is a battery charging device that is connected between a generator and a battery, rectifies an output voltage of the generator to generate a DC voltage, and charges the battery with the DC voltage. A battery charging control method, wherein the battery charging device includes: a detecting unit that detects stop of rotation of the generator; and when the detecting unit detects stop of rotation of the generator, A blocking unit configured to block a discharge path of the battery formed in the battery, and including a transistor that is a first switch element having a current path interposed in the discharge path of the battery. the detection unit includes a second switch element which voltage after the output voltage of the generator is rectified to drive the first switching element to off state when below a certain value Wherein the detection unit, and detecting the stop of rotation of the generator, when said second switching element, stops the rotation of the generator is detected, the battery by turned off And cutting off the remaining part of the discharge path of the battery by turning off the first switch element and turning off the first switch element .

  According to one embodiment of the present invention, the discharge current of the battery when the generator is stopped can be suppressed.

It is a figure which shows the structural example of the battery charging device by 1st Embodiment of this invention. It is a figure which shows the structural example of the battery charging device by the modification of 1st Embodiment of this invention. It is a figure which shows the structural example of the battery charging device by 2nd Embodiment of this invention. It is a figure which shows the structural example of the battery charging device by the modification of 2nd Embodiment of this invention. It is a figure which shows the structural example of the battery charging device by a prior art.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First embodiment]
(Description of configuration)
In FIG. 1, the structural example of the battery charging device 100 by 1st Embodiment of this invention is shown.
Schematically, the battery charging device 100 rectifies the AC output voltage of each phase (U phase, V phase, W phase) of the AC generator G to generate a DC voltage, and charges the battery B with this DC voltage. The rectifier 110, the controller 120, the detector 130, the blocking unit 140, and the reverse connection prevention circuit 150 are provided. The AC generator G generates, for example, a three-phase AC voltage using the rotation of a vehicle engine or the like, but is not limited to this example. Moreover, although the battery B is used as a power supply of the various electrical equipment of a vehicle, for example, it is not limited to this example.

  The rectifying unit 110 is for rectifying the AC output voltage of the AC generator G, and includes diodes D111 to D113 and n-channel field effect transistors F111 to F113. Here, the anodes of the diodes D111 to D113 are connected to the U-phase, V-phase, and W-phase outputs of the AC generator G, respectively. The cathodes of the diodes D111 to D113 form a high voltage output node of the rectifying unit 110 and are commonly connected to the output terminal T1 through the high voltage line HL. In a state where the battery B is normally connected to the battery charger 100, the positive electrode of the battery B is connected to the high voltage terminal T1.

  The drains of the field effect transistors F111 to F113 are connected to the U-phase, V-phase, and W-phase outputs of the AC generator G, respectively. The sources of the field effect transistors F111 to F113 form a low voltage output node of the rectifying unit 110 and are commonly connected to the low voltage terminal T2 through the low voltage line LL. On the low voltage line LL, a current path of the field effect transistor M1 constituting the reverse connection prevention circuit 150 is inserted. That is, the source of the field effect transistor M1 is connected to the low voltage output node of the rectifying unit 110, and the drain thereof is connected to the low voltage terminal T2. In a state where the battery B is normally connected to the battery charging device 100, the negative electrode of the battery B is connected to the low voltage terminal T2. The current path of the field effect transistor M1 forms part of the low voltage line LL. A control signal for controlling conduction of these field effect transistors is commonly applied from the control unit 120 to each gate of the field effect transistors F111 to F113.

  In the present embodiment, the field effect transistors F111 to F113 are elements corresponding to the thyristors of the voltage adjusting unit 3 shown in FIG. 5 described above, and are for adjusting the AC output voltage generated by the AC generator G. is there. The diodes D111 to D113, together with the body diodes (not shown) of the field effect transistors F111 to F113, constitute a full bridge circuit corresponding to the rectifying unit 2 shown in FIG.

  The controller 120 controls the field effect transistor F111 of the rectifier 110 so that the voltage between the high voltage output node and the low voltage output node of the rectifier 110, that is, the output voltage of the rectifier 110 becomes a desired voltage. This is for controlling the conduction of F113. In a state where the battery B is normally connected between the high voltage terminal T1 and the low voltage terminal T2, the voltage between the high voltage output node and the low voltage output node is approximately equal to the battery voltage of the battery B. It can be said that the control unit 120 controls conduction of the field effect transistors F111 to F113 so that the voltage of the battery B (battery voltage) becomes a predetermined target value. The control unit 120 is realized by using, for example, a control IC (Integrated Cirecuit). The power supply node of the control IC constituting the control unit 120 is connected to the high voltage terminal T1 through the cutoff unit 140, and the ground node is connected to the low voltage through the current path of the field effect transistor M1 of the reverse connection prevention circuit 150. Connected to terminal T2. In the present embodiment, when the rotation of the AC generator G stops, the control unit 120 and the reverse connection prevention circuit 150 form a discharge path for the battery B inside the battery charging device 100. In other words, the discharge path includes a reverse connection prevention circuit 150 that functions as a protection circuit for preventing an abnormal current that occurs when a battery is reversely connected to the battery charging device 100.

  The detection unit 130 is for detecting the stop of the rotation of the AC generator G, and includes diodes D131 to D133 (rectifier elements), capacitors C131 to C134 (capacitance elements), resistors R131 to R134, and an npn type. Bipolar transistor Q130 (second switch element). Here, the diodes D131 to D133 are for rectifying the AC output voltage of the AC generator G. Capacitors C131 to C133 block the DC component of the pulsating voltage rectified by the diodes D131 to D133. The resistors R131 to R133 are for adjusting the current flowing into the capacitor C134. The capacitor C134 is for holding a voltage applied via the resistors R131 to R133. The resistor R134 is for adjusting the base current of the bipolar transistor Q130. The bipolar transistor 130 drives the bipolar transistor 140 (first switch element) of the cutoff unit 140 to an off state when the voltage held in the capacitor C134 falls below a certain value.

The connection relationship of each component of the detection part 130 is demonstrated concretely.
The anodes of the diodes D131, D132, and D133 are connected to the U-phase, V-phase, and W-phase outputs of the AC generator G, respectively. Among these, the cathode of the diode D131 is connected to one end of the capacitor C131, and the other end of the capacitor C131 is connected to one end of the resistor R131. The cathode of the diode D132 is connected to one end of the capacitor C132, and the other end of the capacitor C132 is connected to one end of the resistor R132. The cathode of the diode D133 is connected to one end of the capacitor C133, and the other end of the capacitor C133 is connected to one end of the resistor R133.

  The other ends of the resistors R131, R132, and R133 are commonly connected to one end of the resistor R134, and the other end of the resistor R134 is connected to the base of the bipolar transistor Q130. One end of a capacitor C134 is connected to a connection point between each other end of the resistors R131, R132, R133 and one end of the resistor R134, and the other end of the capacitor C134 is connected to the low voltage line LL together with the emitter of the bipolar transistor Q130. The reverse connection prevention circuit 150 is connected to the low voltage terminal T2 through the current path of the field effect transistor M1. The collector of the bipolar transistor Q130 forms the output part of the detection part 130.

  The blocking unit 140 is for blocking the discharge path of the battery B formed inside the battery charging device 100 when the detecting unit 130 detects the stop of the rotation of the AC generator G. It comprises a pnp bipolar transistor Q140 (first switch element) having a current path inserted in the discharge path. The emitter of the bipolar transistor Q140 is connected to the output terminal T1 (high voltage line HL), and its base is connected to the collector of the bipolar transistor Q130 that forms the output part of the detection part 130. The collector of the bipolar transistor Q140 is connected to the power supply node of the control IC constituting the control unit 120, and is connected to one end of a resistor R1 of a reverse connection prevention circuit 150 described later.

  The reverse connection prevention circuit 150 is for preventing an overcurrent (abnormal current) due to reverse connection of the battery B, and has the same configuration as the reverse connection prevention circuit 5 shown in FIG. That is, the reverse connection prevention circuit 150 includes resistors R1 and R2 and an n-channel field effect transistor M1, and a body diode D1 is formed between the source and drain of the field effect transistor M1. Here, the field effect transistor M1 is interposed on the low voltage line LL from the low voltage output node of the rectifier 110 to the low voltage terminal T2. Specifically, the source of the field effect transistor M1 is connected to the low voltage output node of the rectifying unit 110, and the drain thereof is connected to the low voltage terminal T2. Therefore, the current path of the field effect transistor M1 forms part of the low voltage line LL.

  The resistors R1 and R2 are for biasing the gate of the field effect transistor M1, and are connected in series between the collector of the bipolar transistor Q140 of the blocking unit 140 and the source of the field effect transistor M1. Specifically, one end of the resistor R1 is connected to the collector of the bipolar transistor Q140, the other end of the resistor R1 is connected to one end of the resistor R2, and the other end of the resistor R2 is connected to the source of the field effect transistor M1. . The gate of the field effect transistor M1 is connected to the connection point between the resistor R1 and the resistor R2.

In the present embodiment, as can be understood from FIG. 1, the current path of the bipolar transistor Q140 constituting the blocking unit 140 is the current formed by the resistors R1 and R2 between the high voltage line HL and the low voltage line LL. In addition to being connected in series to the path, it is connected in series to a current path formed between the power supply node and the ground node of the control unit 120. Therefore, when the bipolar transistor Q140 is turned off, the blocking unit 140 is configured to block the current paths of both the control unit 120 and the reverse connection prevention circuit 150.
The example of FIG. 1 shows a state where the battery B is normally connected to the battery charging device 100.

(Description of operation)
Next, the operation of the battery charger 100 according to the first embodiment will be described.
Here, it is assumed that the battery B is normally connected, and the operation of the battery charger 100 will be described focusing on the interruption of the discharge current of the battery B by the detection unit 130 and the interruption unit 140. Other operations, for example, a power conversion operation for generating a desired voltage from the AC generator G, an operation of the reverse connection prevention circuit 150, and the like are the same as those of the conventional device.

A. When the AC generator G is rotating The detection unit 130 detects that the AC generator G is rotating from the increase in the AC output voltage accompanying the rotation of the AC generator G. Specifically, in the detection unit 130, the U-phase AC output voltage of the AC generator G is half-wave rectified by the diode D131 and supplied to the capacitor C131. The capacitor C131 removes a DC component from the pulsating voltage obtained by rectification by the diode D131. The pulsating voltage from which the DC component has been removed is supplied to the capacitor C134 through the resistor R131. Capacitor C134 smoothes and holds the pulsating voltage supplied through resistor R131. Similarly, the V-phase and W-phase AC output voltages of the AC generator G are rectified by the diode D132 and the diode D133, respectively, and supplied to the capacitor C132 and the capacitor C133. Capacitor C132 and capacitor C133 remove a direct current component from the pulsating voltage obtained by rectification by diode D132 and diode D133, respectively. The pulsating voltage from which the DC component is removed is supplied to the capacitor C134 through the resistor R132 and the resistor R133, respectively.

  The voltage held in the capacitor C134 is applied to the base of the bipolar transistor Q130 via the resistor R134. Here, the voltage applied to the base of the bipolar transistor Q130 rises according to the rotation of the AC generator G. When the voltage at the base of the bipolar transistor Q130 rises and the emitter and base are biased in the forward direction, the bipolar transistor Q130 is turned on. When the bipolar transistor Q130 is turned on, the voltage at the base of the bipolar transistor Q140 that constitutes the cutoff unit 140 is lowered, the bias between the emitter and the base is forward-biased, and the bipolar transistor Q140 is turned on. As a result, the operating voltage is supplied from the high voltage line HL to the control unit 120 and the reverse connection prevention circuit 150 via the bipolar transistor Q140 of the blocking unit 140.

  On the other hand, when the bipolar transistor Q140 of the cutoff unit 140 is turned on as described above, the voltage of the gate of the field effect transistor M1 connected to the connection point between the resistor R1 and the resistor R2 increases in the reverse connection prevention circuit 150. Then, the field effect transistor M1 is turned on. Thereby, the ground node of the control IC constituting the control unit 120 and the low voltage terminal T2 are electrically connected via the field effect transistor M1. As a result, the control unit 120 is powered, and the control unit 120 has the field effect transistors F111 to F113 of the rectifying unit 110 so that the voltage of the battery B (battery voltage) becomes a predetermined voltage (target value). To control the conduction. Thereby, the battery B is charged.

B. When the rotation of the alternator G stops When the rotation of the alternator G stops, the detection unit 130 stops the rotation of the alternator G due to a decrease in the AC output voltage accompanying the stoppage of rotation of the alternator G. Detect that Specifically, when the rotation of the AC generator G stops, the U-phase AC output voltage of the AC generator G becomes a constant low voltage (for example, 0 V). In this case, in the detection unit 130, the voltage supplied to the capacitor C134 via the diode D131, the capacitor C131, and the resistor R131 decreases. Similarly, the V-phase and W-phase AC output voltages of the AC generator G are also constant low voltages, and the voltages supplied to the capacitor C134 via the diodes D132 and D133, the capacitors C132 and C133, and the resistors R132 and R133 are also shown. descend. As a result, the voltage held in the capacitor C134 decreases.

  When the voltage held in the capacitor C134 decreases, the voltage applied to the base of the bipolar transistor Q130 via the resistor R134 decreases. Here, when the voltage applied to the base of the bipolar transistor Q130 is reduced and the emitter and base are not biased forward, the bipolar transistor Q130 is turned off. When the bipolar transistor Q130 is turned off, the bipolar transistor Q140 constituting the cutoff unit 140 is not forward biased between the emitter and the base, and the base current disappears, so that the bipolar transistor Q140 is turned off. When bipolar transistor Q140 is turned off, discharge current Id by the current path formed by control unit 120 and the current path formed by reverse connection prevention circuit 150 is cut off. Thereby, the discharge current of battery B by control unit 120 and reverse connection prevention circuit 150 is suppressed.

  In this case, when the bipolar transistor Q140 of the cutoff unit 140 is turned off, the voltage of the gate of the field effect transistor M1 connected to the connection point between the resistor R1 and the resistor R2 in the reverse connection prevention circuit 150 is Since it becomes almost equal to the source voltage through R2, the field effect transistor M1 is turned off. Accordingly, even in this case, overcurrent due to reverse connection of the battery B is prevented.

As described above, according to the first embodiment, when the rotation of the AC generator G is stopped, the current path formed inside the battery charging device 100 is interrupted by the interrupting unit 140, so that the discharge current of the battery B is reduced. It is possible to suppress the decrease in battery voltage.
Moreover, according to 1st Embodiment, since it comprised so that the electric current path which the control part 120 formed by the interruption | blocking part 140 might be interrupted | blocked, when the rotation of the AC generator G has stopped, the battery B is reversely connected. Even in such a case, the control IC constituting the control unit 120 can be protected from overcurrent.
In the first embodiment described above, the current path formed by the reverse connection prevention circuit 150 and the control unit 120 is cut off. However, the AC generator G is stopped regardless of the presence or absence of the reverse connection prevention circuit 150. In addition, an arbitrary current path formed inside the battery charging device 100 can be blocked to suppress the discharge of the battery B.

  In the first embodiment, the detection unit 130 detects the stop of the rotation of the AC generator G. In the present embodiment, the stop of the rotation of the AC generator G means that the battery B is significantly This includes a state in which the rotation of the AC generator G is reduced to the extent that charging is not possible. Therefore, even if the AC generator G is not completely stopped, if the charging of the battery B is not performed, that is, if the charging current of the battery B is lower than the discharging current, the rotation of the AC generator G Is treated as being stopped. Regardless of such a definition, the definition of stopping the rotation of the AC generator G can be arbitrarily determined according to, for example, the characteristics of the charging target.

<Modification of First Embodiment>
Next, a modification of the first embodiment of the present invention will be described.
In FIG. 2, the structural example of the battery charging device 100a by the modification of 1st Embodiment of this invention is shown. A battery charging device 100a according to the modification shown in FIG. 2 includes a rectifying unit 110a instead of the rectifying unit 110 in the configuration of the battery charging device 100 shown in FIG. The rectifying unit 110a includes diodes D114 to D116 and thyristors T111 to T113 in place of the field effect transistors F111 to F113 in the configuration of the rectifying unit 110 of FIG. Other configurations are the same as those of the battery charger 100 shown in FIG.

  In the battery charging device 100a shown in FIG. 2, the cathodes of the diodes D114 to D116 are connected to the anodes of the diodes D111 to D113, respectively. The anodes of the diodes D114 to D116 form a low voltage output node of the rectifying unit 110a and are commonly connected to a low voltage line LL to which the source of the field effect transistor M1 of the reverse connection prevention circuit 150 is connected. The anodes of thyristors T111 to T113 are connected to the cathodes of diodes D114 to D116, respectively, and the cathodes of thyristors T111 to T113 are connected to the anodes of diodes D114 to D116, respectively. A control signal for controlling conduction of these thyristors is commonly applied from the control unit 120 to the control gates of the thyristors T111 to T113.

  In this modification, the diodes D114 to D116 function as body diodes of the field effect transistors F111 to F113 shown in FIG. 1, and the thyristors T111 to T113 function as the field effect transistors F111 to F113 shown in FIG. Therefore, the battery charging device 100a according to the present modification operates in the same manner as the battery charging device 100 shown in FIG. 1, converts the AC output voltage of the AC generator G into a desired voltage, and charges the battery B. The operation when the rotation of the AC generator G stops is the same as that of the battery charger 100 of FIG.

[Second Embodiment]
Next, a second embodiment of the present invention will be described.
FIG. 3 shows a configuration example of the battery charger 200 according to the second embodiment. The battery charging device 200 includes a reverse connection prevention circuit 250 provided on the high voltage line HL side in place of the reverse connection prevention circuit 150 in the configuration of the battery charging device 100 according to the first embodiment shown in FIG. The reverse connection prevention circuit 250 includes resistors R51 and R52, a p-channel field effect transistor M51, and a body diode D51. These include the resistors R1 and R2 included in the reverse connection prevention circuit 150 shown in FIG. It is a component corresponding to the field effect transistor M1 and the body diode D1.

  In the second embodiment, the field effect transistor M51 is interposed on the high voltage line HL from the high voltage output node of the rectifying unit 110 to the high voltage terminal T1. Specifically, the source of the field effect transistor M51 is connected to the high voltage output node of the rectifying unit 110, and the drain thereof is connected to the high voltage terminal T1. The current path of the field effect transistor M51 forms part of the high voltage line HL.

  The resistors R51 and R52 are for biasing the gate of the field effect transistor M51, and are connected in series between the source of the field effect transistor M51 and the collector of the bipolar transistor Q130 of the detection unit 130. Specifically, one end of the resistor R52 is connected to the source of the field effect transistor M51, the other end of the resistor R52 is connected to one end of the resistor R51, and the other end of the resistor R51 is connected to the collector of the bipolar transistor Q130. . The gate of the field effect transistor M51 is connected to the connection point between the resistor R51 and the resistor R52.

  In the second embodiment, as can be understood from FIG. 3, the current path of the bipolar transistor Q140 constituting the cutoff unit 140 is in series with the current path formed between the power supply node and the ground node of the control unit 120. It is connected. The bipolar transistor Q130 constituting the detection unit 130 is connected in series with the current path formed by the resistors R51 and R52 between the source of the field effect transistor M51 and the low voltage terminal T2 (low voltage line LL). ing. Therefore, when the rotation of the AC generator G is stopped, the detection unit 130 turns off the bipolar transistor Q130, and accordingly, the bipolar transistor Q140 of the cutoff unit 140 is turned off, so that the control unit 120 and the reverse connection prevention circuit 150 are turned off. The discharge current flowing through each current path formed by is cut off. In this case, the bipolar transistor Q130 of the detection unit 130 also serves as a part of the function of the bipolar transistor Q140 of the blocking unit 140.

Therefore, according to the second embodiment, similarly to the first embodiment, when the rotation of the AC generator G is stopped, the discharge path formed inside the battery charging device 100a is blocked by the blocking unit 140. Therefore, it is possible to suppress the discharge of the battery B and suppress the decrease in the battery voltage.
In addition, according to the second embodiment, similarly to the first embodiment, since the current path formed by the control unit 120 is also blocked by the blocking unit 140, the rotation of the AC generator G is stopped. Sometimes, when the battery B is reversely connected, the control IC constituting the control unit 120 can be protected from overcurrent.

<Modification of Second Embodiment>
Next, a modification of the second embodiment will be described.
In FIG. 4, the structural example of the battery charging apparatus 200a by the modification of 2nd Embodiment is shown. The battery charging device 200a corresponds to the battery charging device 100a according to the modified example of the first embodiment shown in FIG. 2 described above. In the configuration of the battery charging device 200 shown in FIG. The rectifying unit 110a shown in FIG. Other configurations are the same as those of the battery charger 200 shown in FIG.
The battery charging device 200a shown in FIG. 4 can also charge the battery B by converting the AC output voltage of the AC generator G into a desired voltage, similarly to the battery charging device 200 shown in FIG. Further, the operation when the rotation of the AC generator G is stopped is the same as that of the battery charging device 200 shown in FIG.

  In the first embodiment and the second embodiment described above, the present invention is expressed as a battery charging device, but the present invention can also be expressed as a battery charging control method. In this case, the battery charging control method according to the present invention is a battery charging control method in a battery charging apparatus that rectifies an output voltage of a generator to generate a DC voltage, and charges the battery with the DC voltage. A battery charge control method comprising: detecting a stop of rotation of the generator; and shutting off a discharge path of the battery formed inside the battery charger when the stop of the rotation of the generator is detected. Can be expressed as

As mentioned above, although embodiment and the modification of this invention were demonstrated, various deformation | transformation, substitution, addition, etc. are possible in the range which does not deviate from the summary of this invention.
For example, in each of the above-described embodiments and modifications, the AC output voltage of the U-phase, V-phase, and W-phase of the AC generator G is rectified to detect the stop of the rotation of the AC generator G. Although the detection unit 130 is configured, it is not always necessary to use all three phases, and the stop of rotation of the AC generator G may be detected using only a part of the phases.
Further, for example, in the above-described embodiment, the blocking unit 140 is configured by a bipolar transistor, but other switching elements such as a field effect transistor and a thyristor may be used. Other constituent elements can be replaced with arbitrary elements without departing from the gist of the present invention.

  DESCRIPTION OF SYMBOLS 100,100a, 200,200a ... Battery charging device, 110,110a ... Rectification part, 120 ... Control part, 130 ... Detection part, 140 ... Blocking part, 150,250 ... Reverse connection prevention circuit, B ... Battery, C131-C134 ... Capacitor, D111-D116, D131-D133 ... Diode, F111-F113 ... Field effect transistor, G ... AC generator, Q130, Q140 ... Bipolar transistor, R131-R134 ... Resistance, T1, T2 ... Output terminal, T111-T113 ... Thyristor.

Claims (3)

A battery charging device connected between the generator and the battery, rectifying the output voltage of the generator to generate a DC voltage, and charging the battery with the DC voltage,
A detection unit for detecting a stop of rotation of the generator;
When the detection unit detects the stop of the rotation of the generator, the blocking unit is a blocking unit that blocks the discharge path of the battery formed inside the battery charger, and is inserted in the discharge path of the battery A cut-off portion composed of a transistor which is a first switch element having a current path;
Equipped with a,
The detector is
A second switch element that drives the first switch element to an off state when a voltage after the output voltage of the generator is rectified falls below a certain value;
The second switch element shuts off a part of the discharge path of the battery by being turned off, and shuts off the remaining part of the discharge path of the battery by turning off the first switch element.
A battery charger characterized by that . The discharge path is
The battery charging device according to claim 1, further comprising a protection circuit for preventing an abnormal current generated when the battery is reversely connected to the battery charging device. A battery charging control method in a battery charging device connected between a generator and a battery, rectifying an output voltage of the generator to generate a DC voltage, and charging the battery with the DC voltage,
The battery charger is
A detection unit for detecting a stop of rotation of the generator;
When the detection unit detects the stop of the rotation of the generator, the blocking unit is a blocking unit that blocks the discharge path of the battery formed inside the battery charger, and is inserted in the discharge path of the battery A cut-off portion composed of a transistor which is a first switch element having a current path;
With
The detector is
A second switch element that drives the first switch element to an off state when a voltage after the output voltage of the generator is rectified falls below a certain value;
The detection unit detecting a stop of rotation of the generator;
When the second switch element detects that the rotation of the generator is stopped, the second switch element is turned off to shut off a part of the discharge path of the battery and turn off the first switch element. Cutting off the rest of the battery discharge path by :
Including a battery charge control method.

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