JP5310092B2 - Vehicle power supply - Google Patents

Description

  The present invention relates to a vehicular power supply apparatus that includes two power supplies including a main power supply and a sub power supply, and charges the regenerative energy generated by a generator when the vehicle is decelerated to the sub power supply.

  As a conventional vehicle power supply device, there is one that charges a regenerative energy generated by a generator when a vehicle decelerates to a sub power source and charges a main power source via a DC / DC converter that transforms the voltage of the sub power source. .

  In addition, a switch is provided between the sub power supply and the main power supply, and the voltage difference between the sub power supply and the main power supply is smaller than a predetermined value in order to charge directly from the sub power supply to the main power supply without going through the DC / DC converter. When closing the switch.

  If the switch is closed while the DC / DC converter is performing a transformation operation, a short circuit between the input end and the output end of the DC / DC converter occurs. If the switch is closed after the transformation operation of the DC / DC converter is stopped in order to prevent a short circuit from occurring, the power supply to the main power supply is interrupted.

  For this reason, in the conventional vehicle power supply device, it is necessary to simultaneously perform the stop control of the transformation operation of the DC / DC converter and the control of closing the switch in order to prevent short circuit and power supply interruption.

For example, Patent Document 1 is known as a prior art document.
JP 2004-266888 A

  In the conventional vehicle power supply device, there is a problem that both the control for stopping the transformation operation of the DC / DC converter and the control for closing the switch need to be performed at the same time in order to prevent short circuit and power interruption when closing the switch. there were.

  The present invention has been made to solve the conventional problems, and it is an object of the present invention to provide a vehicular power supply device that can prevent a short circuit and a power interruption from occurring only by a control for closing the switch when the switch is closed. To do.

The vehicle power supply device of the present invention includes two power sources including a generator having a starter function and a power generation function, a sub power source connected to the power generator, and a main power source having a higher rated voltage than the sub power source. A DC / DC converter for stepping down and outputting the voltage of the sub-power supply, a diode for connecting the main power supply and the DC / DC converter, an electrical load connected to the main power supply, the main power supply, and the A switch provided between the auxiliary power supply, a voltage detection sensor that detects an output voltage of the auxiliary power supply, and a control device that controls opening and closing of the switch, and the anode side of the diode is connected to the DC / DC converter. When the cathode is connected to the main power source and the control device is connected to the output terminal and the voltage detected by the voltage detection sensor is smaller than a predetermined voltage when the engine is started And it controls to close the switch while operating the said DC / DC converter.

  In the present invention, when the switch is closed, the input end and the output end of the DC / DC converter are insulated by the diode, so that no short circuit occurs.

  Therefore, according to the present invention, it is not necessary to perform stop control of the step-down operation of the DC / DC converter when the switch is closed, and it is possible to prevent a short circuit and power interruption from occurring only by the control for closing the switch.

  Hereinafter, a vehicle power supply device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a vehicle power supply device according to an embodiment of the present invention.

  As shown in FIG. 1, the vehicle power supply device 1 includes a generator 2 that generates electric power from a motor driven from an engine, and two power sources including a sub power source 3 and a main power source 4. For example, the rated voltage of the sub power supply 3 is about 18V, and the rated voltage of the main power supply 4 is about 14V.

  The sub power supply 3 or the generator 2 and the main power supply 4 that connects the electrical load 5 such as a vehicle acoustic device are electrically connected via a DC / DC converter 6 and a diode 7. The DC / DC converter 6 steps down the voltage of the sub power supply 3 and outputs it. The anode side of the diode 7 is connected to the output terminal of the DC / DC converter 6, and the cathode side is connected to the main power supply 4.

  Further, a switch 8 formed of a mechanical relay is provided between the sub power source 3 or the generator 2 and the main power source 4. The switch 8 is opened and closed by a switch control signal output from the control device 9. The diode 7 described above prevents a short circuit between the input end and the output end of the DC / DC converter 6 that occurs when the switch 8 is closed.

  In addition, the first voltage detection sensor 10 is provided at the output end of the sub power supply 3 described above, and the second voltage detection sensor 11 is provided at the output end of the main power supply 4. Each detects the output voltage of the connected power supply and notifies the control device 9 of the voltage value signal.

  The control device 9 controls opening and closing of the switch 8 based on the voltages detected by the first voltage detection sensor 10 and the second voltage detection sensor 11. While the vehicle is traveling, the control device 9 performs control to open the switch 8.

  As a case where the control device 9 performs control to close the switch 8, for example, there is a case where electric energy is directly supplied from the main power source 4 to the sub power source 3 or the generator 2. This may be when the sub power supply 3 needs to be charged to prevent overdischarge or when the sub power supply 3 cannot supply sufficient electric energy.

  As a case where the sub-power supply 3 cannot sufficiently supply electric energy, the motor of the generator 2 may be used as a starter when starting the engine. When the engine is started, there is a time when the engine is started or when the engine is restarted after the vehicle is idling stopped.

  When the motor of the generator 2 is used as a starter, a large amount of electric energy is instantaneously required. When the output voltage of the sub power supply 3 is smaller than a predetermined voltage value (for example, about 15 V), the sub power supply 3 cannot supply sufficient electric energy to use the motor of the generator 2 as a starter. For this reason, the control device 9 closes the switch 8 and supplies electric energy to the generator 2 directly from the main power supply 4.

  In addition, as a case where the control device 9 performs the control for closing the switch 8, it is also conceivable to supply electric energy directly from the sub power source 3 to the main power source 4.

  The operation | movement is demonstrated about the power supply device 1 for vehicles comprised as mentioned above.

While the vehicle is running, the control device 9 controls to open the switch 8. At this time, the electrical energy generated by the generator 2 is stored in the sub power source 3 and also stored in the main power source 4 via the DC / DC converter 6 and the diode 7. The first voltage detection sensor 10 detects the output voltage of the sub power supply 3, and the second voltage detection sensor 11 detects the output voltage of the main power supply 4.

  When the engine is started again after the engine is stopped, the control device 9 performs control to close the switch 8 when the voltage detected by the first voltage detection sensor 10 is smaller than a predetermined voltage.

  The above operation will be described in detail with reference to the drawings. FIG. 2 is a diagram for explaining the operation of the control device 9 when the switch 8 is closed. FIG. 3 is a diagram for explaining the relationship between the voltage and signal of each part of the power supply device for a vehicle in one embodiment of the present invention and time.

  The voltage (T0 to T1 in FIG. 3) of each part of the vehicle power supply device 1 immediately after the vehicle stops the engine (immediately after the engine stop in FIG. 2) will be described.

  The control device 9 controls the switch control signal so that the switch 8 opens (outputs LOW). The output voltage (Vout) of the DC / DC converter 6 is lower than the output voltage (Vsub) of the sub power supply 3 by the voltage (Vdrop) stepped down by the DC / DC converter 6.

  Vout = Vsub-Vdrop

  At this time, the voltage on the anode side of the diode 7 becomes the same as the output voltage (Vout) of the DC / DC converter 6. The voltage on the cathode side of the diode 7 matches the output voltage (Vmain) of the main power supply 4. For example, Vsub is about 18V and Vout is about 14V.

  The output voltage (Vmain) of the main power supply 4 is lower than the output voltage (Vout) of the DC / DC converter 6 by a voltage drop (Vdi) (about 0.6 V in the case of a silicon diode) when the diode 7 is forward biased. It becomes.

  Vmain = Vout−Vdi

  The output voltage (Vout) of the DC / DC converter 6 is determined in consideration of the voltage drop (Vdi) of the diode 7. That is, Vout is set so that Vmain becomes the rated voltage of the main power supply 4 in consideration of the voltage drop due to Vdi.

  For example, when the rated voltage of the main power supply 4 is 13.4 V and the output voltage (Vsub) of the sub power supply 3 is 18 V, the DC / DC converter 6 has an output voltage (Vout) of 14 V (Vdrop). 4V).

  When the open voltage of the main power supply 4 becomes smaller than the rated voltage (13.4 V), electric energy is supplied from the DC / DC converter 6 to the main power supply 4 and the electrical load 5. If the open voltage of the main power supply 4 is equal to or higher than the rated voltage (13.4 V), no current flows due to the rectifying function of the diode 7.

  Next, the voltage (T1 to T5 in FIG. 3) of each part in the vehicle power supply device from the start to the stop of the engine (steps S01 to S07) will be described.

In step S01, the control device 9 determines whether or not the engine is started. The case where the engine is started includes a case where the driver starts the engine, and there is a case where the engine is started again after idling stop. When the engine is not started (NO in step S01), control device 9 executes step S01 again.

  When the engine is started (YES in step S01), the control device 9 determines that the output voltage (Vsub) of the sub power supply 3 detected by the first voltage detection sensor 10 is smaller than a predetermined voltage value (Vst) ( YES in step S02), the switch 8 is closed (step S03), and then the starter is started (step S04).

  Vst is a value for determining whether or not the voltage is sufficient to cause the generator 2 to perform a starter operation, and is, for example, a voltage of about 15V. When the output voltage of the sub power supply 3 decreases, the starter cannot be started. For this reason, the control device 9 closes the switch 8 so as to supply electric energy directly from the main power supply 4 using a lead battery to the generator 2.

  When the detection voltage of the first voltage detection sensor 10 is equal to or higher than Vst (NO in step S02), the sub power supply 3 can drive the starter of the generator 2. For this reason, the control device 9 starts the starter without closing the switch 8 (step S04). At this time, electric energy is supplied from the sub power supply 3 to the generator 2.

  After starting the starter (step S04), the control device 9 determines whether or not the engine has been started (step S05).

  When the engine is started (YES in step S05), the control device 9 opens the switch 8 (step S06). If the engine has not been started (NO in step S05), control device 9 opens switch 8 and then executes step S02 again to start the starter again.

  The voltage of each part of the vehicle power supply device 1 after the engine is stopped (YES in step S01) until the switch is opened (step S06) will be described with reference to FIG.

  T1 in FIG. 3 is a time when the engine is stopped (immediately after the engine is stopped in FIG. 2). After the engine is stopped, the output voltage (Vsub) of the sub power supply 3 is discharged and the voltage gradually decreases (from T1 to T2 in FIG. 3).

  The control device 9 starts the engine (step S01) at T2 in FIG. At this time, since the output voltage of the sub power supply 3 is smaller than Vst (YES in step S02), the control device 9 closes the switch 8 by setting the switch control signal to HIGH (step S03).

  At this time, the input voltage of the DC / DC converter 6 becomes the same voltage as the output voltage (Vmain) of the main power supply 4, and the output voltage (Vout) of the DC / DC converter 6 is stepped down to a voltage equal to or lower than Vmain. As a result, the voltage on the cathode side of the diode 7 becomes Vmain, and the voltage on the anode side of the diode 7 becomes a voltage lower than Vmain. That is, the diode 7 is reverse-biased, and the current is cut off by its rectifying function.

  The control device 9 starts the starter (step S04) at T3 in FIG. At this time, electric energy is supplied from the sub power source 3 and the main power source 4 to the generator 2.

  After a predetermined time has elapsed from T3 in FIG. 3, the control device 9 confirms engine start (YES in step S05), and opens the switch 8 in T4 in FIG. 3 (step S06).

After the switch 8 is opened (T4 in FIG. 3), the sub power supply 3 is charged with the electric energy generated by the generator 2 until T5 in FIG. The output voltage (Vsub) of the sub power supply 3 becomes the same voltage as T0 in FIG. 3 at T5 in FIG.

  After executing step S06, the control device 9 determines whether or not there is an instruction to stop the engine (step S07). The engine is stopped when the driver stops the engine, or when the vehicle is temporarily stopped at an intersection or the like to stop idling.

  When YES in step S07, control device 9 stops the engine (engine stop in FIG. 2). When the engine is not stopped (NO in step S07), control device 9 executes step S07 again.

  As described above, in the vehicle power supply device according to the embodiment of the present invention, when the switch 8 is closed, the cathode potential of the diode 7 becomes higher than the anode potential (becomes reverse bias). Not flowing. As a result, the output current of the DC / DC converter 6 is interrupted by the diode 7 and the power consumption is significantly reduced, so that it is not necessary to perform stop control of the step-down operation of the DC / DC converter 6.

  As described above, when the switch is closed, it is not necessary to control the DC / DC converter 6 and the switch 8 at the same time, and there is an effect that the short circuit and the power supply interruption can be prevented only by the control for closing the switch 8.

  In addition, the generator 2 in this Embodiment can generate electric power using the kinetic energy at the time of a vehicle decelerating. Specifically, the rotational resistance during power generation is used as a braking force, which is also called regenerative braking. Usually, the kinetic energy can be converted into electric energy and recovered by operating the electric motor used as the driving force as the generator 2.

  The DC / DC converter 6 in the present embodiment steps down the output voltage of the sub power supply 3 and supplies it to the main power supply 4, so that the rated voltage of the main power supply 4 is lower than the rated voltage of the sub power supply 3. Is used.

  When the rated voltage of the sub power source 3 or the main power source 4 is set high, the difference between the rated voltages of the sub power source 3 and the main power source 4 needs to be lower than the absolute value of the breakdown voltage of the diode 7.

  When the difference between the voltage on the cathode side and the anode side of the diode 7 becomes equal to or higher than the breakdown voltage, the diode 7 enters the breakdown region and a current flows rapidly. This current may damage the DC / DC converter 6. Therefore, by doing as described above, the diode 7 does not enter the breakdown region, and the DC / DC converter 6 can be prevented from being damaged.

  The switch 8 in the present embodiment may be a relay using not only a mechanical relay but also a semiconductor. By using a semiconductor relay, noise can be reduced compared to a mechanical relay. Moreover, since the inrush current at the time of opening and closing of the switch 8 can be reduced, the breakage of the switch 8 can be prevented.

  As described above, according to the present invention, it is not necessary to perform control for stopping the DC / DC converter 6, and only the control for closing the switch 8 can prevent a short circuit and a power interruption, and the regeneration generated in the generator when the vehicle is decelerated. It is useful as a vehicle power supply device that charges and uses energy.

The block diagram of the power supply device for vehicles in one embodiment of the present invention Diagram explaining the operation The figure explaining the relationship between voltage and signal of each part and time

DESCRIPTION OF SYMBOLS 1 Power supply device for vehicles 2 Generator 3 Sub power supply 4 Main power supply 5 Electric load 6 DC / DC converter 7 Diode 8 Switch 9 Control apparatus 10 1st voltage detection sensor 11 2nd voltage detection sensor

Claims (2)

A generator having a starter function and a power generation function ;
Two and a power comprising a high mains voltage rating than the sub power source and the auxiliary power source connected to each said generator,
A DC / DC converter and output the step down a voltage of the auxiliary power supply,
A diode connecting the main power source and the DC / DC converter;
An electrical load connected to the main power source;
A switch provided between the main power source and the sub power source;
A voltage detection sensor for detecting an output voltage of the sub power supply;
A control device for controlling opening and closing of the switch,
The anode side of the diode is connected to the output end of the DC / DC converter and the cathode side is connected to the main power source ,
The control device is a vehicle power supply device that controls to close the switch while operating the DC / DC converter when the voltage detected by the voltage detection sensor is smaller than a predetermined voltage when the engine is started . The difference between the rated voltage of the secondary power supply and the mains power supply apparatus for a vehicle according to the low I請 Motomeko 1 than the absolute value of the breakdown voltage of the diode.