JP4192876B2 - Battery charger - Google Patents

Description

  The present invention relates to a battery charging device that charges a battery with a rectified output of an AC generator driven by an engine.

  A battery charging device mounted on a vehicle driven by an engine includes an input terminal to which an output of an AC generator driven by the engine is input, positive and negative output terminals, and an alternating current applied to the input terminal. A rectifying power supply circuit having a voltage adjusting function for outputting a DC voltage adjusted so as not to exceed a set value by rectifying the voltage between the positive output terminal and the negative output terminal; The battery is charged with the output voltage.

  In recent engine-driven vehicles, since the electrical component load driven by the battery is increased, a sub-battery can be provided outside the main battery that drives the motor for starting the engine to cope with the increase in the electrical component load. I am doing so. A battery charging device mounted on this type of vehicle is required to charge both the main battery and the sub-battery.

As a battery charger capable of charging the main battery and the sub battery, those shown in Patent Document 1 and Patent Document 2 are known. In the battery chargers shown in these patent documents, the cathode is directed to the battery side between the positive terminal of the main battery and the output terminal of the generator and between the positive terminal of the sub battery and the output terminal of the generator. A separate diode was connected to separate the main battery and the sub battery.
JP-A-2-276428 Japanese Unexamined Patent Publication No. 9-46919

  In a conventional battery charger, a main battery including an engine starting motor as a load and a sub battery that drives another load are completely separated by a diode, and the engine starting motor is driven by the main battery. Therefore, when the main battery is exhausted, there is a problem that the engine cannot be started even if the sub battery is normal.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a battery charging device that can prevent an engine from being started or a main battery load cannot be driven due to consumption of a main battery. It is in.

  The present invention rectifies the AC voltage applied to the input terminal to which the output of the AC generator driven by the engine is input, the positive and negative output terminals, and the input terminal so as not to exceed the set value. A rectified power supply circuit with a voltage adjustment function having a circuit that outputs the DC voltage that is generated between the positive output terminal and the negative output terminal, and the main battery and the sub battery are connected with the output of the rectified power supply circuit. It is applied to a battery charger for charging.

In the present invention, the drain is connected to the auxiliary output terminal and the positive output terminal of the rectifying power supply circuit, the source is connected to the auxiliary output terminal, and the N-channel MOSFET is connected between the gate and the drain of the MOSFET. The first resistor, the FET driving switch connected through the second resistor between the gate of the MOSFET and the negative output terminal of the rectifier power supply circuit, and when the AC generator generates an output There is provided an FET drive switch drive circuit that applies a drive signal to the FET drive switch to turn on the FET drive switch. The main battery is a battery that drives the engine starter motor. The main battery is connected between the positive output terminal and the negative output terminal of the rectified power supply circuit, and the auxiliary output terminal and the negative output terminal of the rectified power supply circuit A sub-battery is connected between.

With the above configuration, when the AC generator is generating output, the sub battery can be charged from the rectified power supply circuit through the MOSFET at the same time as charging the main battery with the output of the rectified power supply circuit. In addition, when the main battery is exhausted, the main battery can be recovered from the sub-battery through the MOSFET's parasitic diode to recover the main battery, thus preventing the engine from starting due to exhaustion of the main battery. Can do. Furthermore, when the engine is stopped and the alternator stops outputting, the MOSFET is turned off, and the parasitic diode of the MOSFET prevents the main battery from discharging to the sub-battery side. It is possible to prevent the battery from being consumed.

As described above , when an N-channel MOSFET having a drain connected to the positive output terminal of the rectifying power supply circuit and a source connected to the auxiliary output terminal is provided between the positive output terminal and the auxiliary terminal, the MOSFET Since the parasitic diode formed between the drain and source can be used as the isolator configuration diode, the configuration can be simplified.

As described above, according to the present invention, when the main battery is exhausted, the main battery can be recovered from the sub-battery through the MOSFET's parasitic diode, so that the main battery can be recovered. It is possible to prevent a situation in which the engine cannot be started.

In addition, when the main battery is normal, the parasitic diode of the MOSFET can prevent the main battery from discharging through the circuit on the sub battery side, thus preventing the main battery from being consumed when the engine is stopped. it can.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a preferred configuration example of a battery charging apparatus according to the present invention. In FIG. 1, 1 is a magnet type AC generator driven by an engine (not shown), and 2 is an output of the AC generator 1. A DC voltage adjusted so as not to exceed a set value by rectifying the AC voltage applied to the input terminals 2u, 2v and 2w, the positive and negative output terminals 2a and 2b, and the input terminals 2u to 2w. A rectifying power supply circuit with a voltage adjustment function having a circuit that outputs between the positive output terminal 2a and the negative output terminal 2b, 3 is a main battery, and 4 is a sub-battery. A main load 6 is connected to the main battery 3 through a power switch 5, and a sub load 8 is connected to the sub battery 4 through a power switch 7. The main load 6 includes an engine such as an engine starting motor, an ignition device that ignites the engine, a fuel injection device that supplies fuel to the engine, and an electronic control unit (ECU) that controls the ignition device and the fuel injection device. It includes electrical component loads that must be driven for operation. The sub load 8 includes an appropriate load, for example, various loads that are optionally attached to the vehicle.

  The rectifying power supply circuit 2 includes diodes Du, Dv, and Dw having cathodes connected in common, and diodes Dx, Dy, and Dz having cathodes connected to the anodes of the diodes Du, Dv, and Dw and anodes connected in common. The diode bridge full-wave rectifier circuit 2A, the output short-circuit thyristors Th1, Th2, and Th3 connected in reverse parallel to the diodes Dx, Dy, and Dz constituting the lower side of the rectifier circuit, and the thyristors Th1 to Th3 are controlled. It consists of a control circuit 2B. The input terminals 2u, 2v, and 2w of the rectifier power supply circuit 2 are drawn from the connection points between the anodes of the diodes Du, Dv, and Dw constituting the rectifier circuit 2A and the cathodes of the diodes Dx, Dy, and Dz, and the diode Du. , Dv and Dw, a positive output terminal 2a and a negative output terminal 2b of the rectified power supply circuit 2 are drawn out from a common connection point of cathodes of Dv and Dw and a common connection point of anodes of diodes Dx, Dy and Dz, respectively. The input terminals 2u, 2v, and 2w are connected to the non-neutral point terminals of the three-phase armature coils Lu, Lv, and Lw that are provided in the magnet type AC generator 1 and are star-connected.

  The control circuit 2B is a circuit for controlling the thyristors Th1 to Th3 so that the voltage between the output terminals 2a and 2b does not exceed the set value. The illustrated control circuit 2B has an emitter connected to the positive output terminal 2a and a collector connected to the positive output terminal 2a. PNP transistor TR1 connected to the gates of thyristors Th1 to Th3 through resistors R1 to R3, resistors R4 to R6 respectively connected in parallel between the gate cathodes of thyristors Th1 to Th3, and the emitter base of transistor TR1. The resistor R7 is connected, the Zener diode ZD1 whose cathode is connected to the base of the transistor TR1, and the resistor R8 connected between the anode of the Zener diode ZD1 and the negative output terminal 2b.

In the rectified power supply circuit 2 shown in the figure, an output short-circuit regulator is constituted by the output short-circuit thyristors Th1 to Th3 and the control circuit 2B. The operation of the rectified power supply circuit 2 is as follows.
The rectifier circuit 2A composed of the diodes Du to Dw and Dx to Dz converts the AC voltage output from the generator 1 into a DC voltage and outputs it from between the output terminals 2a and 2b. When the voltage between the output terminals 2a and 2b exceeds the set value, the Zener diode ZD1 is turned on, so that a base current flows through the transistor TR1 and the transistor TR1 is turned on. When the transistor TR1 is turned on, a trigger signal is given from the output terminal 2a side to the gates of the thyristors Th1 to Th3 through the transistor TR1 and the resistors R1 to R3. Among these thyristors, the anode potential is higher than the cathode potential. The higher one is turned on, and the output of the generator 1 is short-circuited through the thyristor in the on state and one of the diodes Dx to Dz constituting the lower side of the bridge of the rectifier circuit. Thereby, the output voltage of the generator 1 is lowered, and the voltage between the output terminals 2a and 2b is lowered. When the voltage between the output terminals 2a and 2b becomes lower than the set voltage, the transistor TR1 is turned off, and the supply of the trigger signal to the thyristors Th1 to Th3 is stopped. The thyristors Th1 to Th3 are turned off when the respective anode currents become less than the holding current, and the output short circuit of the generator 1 is released. As a result, the output voltage of the generator 1 rises and the voltage between the output terminals 2a and 2b rises. By repeating these operations, the voltage between the output terminals 2a and 2b is controlled so as not to exceed the set value. When the output voltage of the generator 1 exceeds the set value, the voltage between the output terminals 2a and 2b is controlled. Is kept near the set value.

  In the present invention, the auxiliary output terminal 2c for connecting the sub-battery is provided, and the charge control switch 10 is connected between the auxiliary output terminal and the positive output terminal 2a of the rectifying power supply circuit. In the example shown in the figure, an N-channel MOSFET (MOS field effect transistor) F1 constitutes the charge control switch 10, and the drain of the MOSFET is connected to the positive output terminal 2a and the source is connected to the auxiliary output terminal 2c. It is connected. In this example, the parasitic diode Dp formed between the drain and source of the MOSFET F1 is used as an isolator configuration diode provided in parallel to the charge control switch 10 with the anode directed to the auxiliary output terminal 2c. It has been.

  The first resistor R9 is connected between the gate and drain of the MOSFET F1, and the FET driving switch 11 is passed through the second resistor R10 between the gate of the MOSFET and the negative output terminal of the rectifying power supply circuit. Is connected. The illustrated FET drive switch 11 comprises an NPN transistor TR2 having a base terminal derived through a resistor rb and a resistor rbe connected between the base and emitter, and the collector of the transistor TR2 is connected to the MOSFET through a second resistor R10. The emitter is connected to the negative output terminal 2b of the rectifier power supply circuit. The cathodes of the diodes D1 to D3 are commonly connected to the base terminal of the transistor TR2, and the anodes of the diodes D1 to D3 are respectively connected to the input terminals 2u to 2w of the rectifying power supply circuit. A smoothing capacitor C1 is connected between the base terminal of the transistor TR2 and the negative output terminal 2b.

  In this example, the diodes D1 to D3 and the capacitor C1 are used to drive the FET, which gives a drive signal to the FET drive switch 11 when the AC generator is generating an output to turn on the FET drive switch. A switch drive circuit is configured, and when the FET drive switch drive circuit and the FET drive switch 11 provide an AC voltage between the input terminals 2u to 2w of the rectified power supply circuit 2, the charge control switch 10 A charge control switch drive circuit is provided for supplying a drive signal to the switch to turn on the charge control switch. The charge control switch drive circuit and the charge control switch 10 constitute a battery isolator circuit 12, and the battery isolator circuit 12 and the rectified power supply circuit 2 constitute a battery charging device.

  In the present invention, the main battery 3 is connected between the positive output terminal 2a and the negative output terminal 2b of the rectifying power supply circuit 2, and the sub battery 4 is connected between the auxiliary output terminal 2c and the negative output terminal 2b. Connected.

  In the above battery charger, when the alternator 1 is not generating output, no base current is applied to the transistor TR2, so that the transistor TR2 is in an off state and the MOSFET F1 is in an off state. In this state, since the isolator configuration diode Dp exists between the main battery 3 and the sub-battery 4, no current flows from the main battery 3 to the sub-battery 4 side, but the main battery 3 is consumed. When the voltage at both ends of the main battery 3 is lower than the voltage at both ends of the sub battery 4, a charging current flows from the sub battery 4 to the main battery 3 through the diode Dp, and the main battery 3 is charged. Therefore, when the main battery 3 is exhausted when the engine is stopped, or when the main battery 3 is exhausted when the main load 6 is applied while the engine is stopped, the main battery 3 is prepared for the next engine start. The voltage of the battery 3 can be recovered.

  When the engine is running and the alternator 1 generates an output, a base current flows through the transistor TR2 to turn on the transistor, whereby a drive signal is applied to the MOSFE F1 and the MOSFET ( Since the charging control switch 10) is turned on, the main battery 3 is charged by the output of the rectifying power supply circuit 2 and the sub battery 4 is charged.

  As described above, in the present invention, the auxiliary output terminal for connecting the sub-battery is provided, and the generator generates an output between the auxiliary output terminal and the positive output terminal of the rectifying power supply circuit. A charging switch that turns on when the main battery is connected, and an isolator configuration diode with the anode facing the auxiliary output terminal is provided in parallel to the charging control switch, and the main battery is connected between the output terminals of the rectifier power supply circuit. Since the sub battery is connected between the auxiliary output terminal and the negative output terminal of the rectifier power supply circuit, the main battery is charged from the sub battery through the isolator configuration diode when the main battery is depleted. The main battery can be recovered. Therefore, it is possible to prevent a situation in which the engine cannot be started due to exhaustion of the main battery.

  In the above embodiment, the charge control switch 10 is configured by a MOSFET, but the charge control switch can also be configured by other switch elements capable of on / off control such as transistors and relays. When the charge control switch is configured by a switch element other than the MOSFET (a switch element having no parasitic diode), an isolator configuration diode having an anode directed toward the auxiliary output terminal 2c is provided in parallel with the switch element. Connecting.

  The configuration of the charge control switch drive circuit that applies a drive signal to the charge control switch and turns on the charge control switch when an AC voltage is applied between the input terminals of the rectifying power supply circuit is the above example. It is not restricted to what was shown in (2), A suitable structure can be taken according to the switch element which comprises the switch 10 for charge control.

  In the above embodiment, the rectified power supply circuit 2 is provided with an output short-circuit regulator, but the rectified power supply circuit is provided with a regulator function for controlling the output voltage so as not to exceed the set value. There is no limitation to the above. For example, a rectifying power source provided with a control rectifier circuit comprising a mixed bridge circuit of a diode and a thyristor and controlling the output voltage so as not to exceed a set value by controlling the conduction angle of the thyristor of the control rectifier circuit A circuit can also be used. In addition, when an excitation-type synchronous generator is used as the AC generator 1, the rectifier circuit that rectifies the output of the generator and the excitation current of the generator are controlled so that the output of the rectifier circuit does not exceed the set value. A rectified power supply circuit can be configured with the circuit to be operated.

  In the above embodiment, only one sub-battery 4 is provided, but the present invention can also be applied to a case where a plurality of sub-batteries are provided. When multiple sub-batteries are provided, auxiliary output terminals are provided as many as the number of sub-batteries, and the generator generates output between each auxiliary output terminal and the positive output terminal of the rectifying power supply circuit. In addition, an on-state charging switch is provided, and an isolator configuration diode with the anode facing each auxiliary output terminal is connected in parallel to each charging control switch, and each auxiliary output terminal and the negative electrode of the rectifying power supply circuit Each sub-battery is connected to the side output terminal. In this case, the charge control switch drive circuit may be provided in common for the plurality of charge control switches, or may be provided individually for the plurality of charge control switches.

It is a circuit diagram showing an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC generator 2 Rectification power supply circuit 3 Main battery 4 Sub battery 6 Main load 8 Sub load 10 Charge control switch 11 FET drive switch F1 MOSFET
Dp Parasitic diode (isolator configuration diode)

Claims (1)

Direct current adjusted so as not to exceed the set value by rectifying the AC voltage applied to the input terminal to which the output of the AC generator driven by the engine is input, the positive and negative output terminals, and the input terminal. A rectifying power supply circuit having a voltage adjustment function having a circuit for outputting a voltage between the positive output terminal and the negative output terminal, and charging the main battery and the sub battery with the output of the rectifying power supply circuit; In the battery charger,
A drain is connected to the auxiliary output terminal and a positive output terminal of the rectified power supply circuit, and a source is connected between the N-channel type MOSFET connected to the auxiliary output terminal and the gate and drain of the MOSFET. When a first resistor, an FET drive switch connected through a second resistor between the gate of the MOSFET and the negative output terminal of the rectified power supply circuit, and the AC generator generates an output A FET drive switch drive circuit for providing a drive signal to the FET drive switch to turn on the FET drive switch,
The main battery is a battery that drives a motor for starting the engine,
The main battery is connected between a positive output terminal and a negative output terminal of the rectified power supply circuit, and the sub-battery is connected between the auxiliary output terminal and a negative output terminal of the rectified power supply circuit. thing,
A battery charger characterized by.

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