JP2010068648A - Power system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power system which efficiently supplies power to a load, without changing the load, even when a high-voltage system of power source is used. <P>SOLUTION: In the case of performing the supply and break of power to a load 10 of 14 V in drive voltage from a generator 1, which generates a high voltage 42 V, by performing the ON-OFF control of the switching elements S1-S3 of a power distributer 2, an LC circuit 6 is provided beforehand on this side of a load 10; and ON-OFF control of the switching elements S1-S3 is performed, whereby a voltage from the generator 1 is made pulse-like in shape, prior to supplying it to an LC circuit 6. The LC circuit 6 steps down the voltage, which is pulsated by the ON-OFF of the switching elements S1-S3, by repeating charging and discharging, prior to supplying to the load 10. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a power supply system that supplies electric power to a vehicle-mounted load.

  In recent years, electric loads mounted on vehicles tend to increase. As the load increases, the power supplied from the power supply system to the electrical load increases, and the amount of power supplied from the power supply system to the electrical load decreases. When the amount of power supplied with respect to the electric load is reduced, the electric load has a problem such as an operation stoppage and the driver and other passengers feel uncomfortable.

Patent Document 1 describes a power supply system that can prevent the operation of an electrical load from being stopped even if the amount of power supplied to the electrical load is reduced by reducing the effective power of the electrical load. Yes. For example, in Patent Document 1, when the electric load is subjected to PWM (Pulse Width Modulation) control, when the amount of supplied power decreases, the duty ratio is reduced and the electric load is PWM controlled. Thereby, power consumption can be reduced without stopping the operation of the load, and it is possible to cope with a decrease in power that can be supplied.
JP 2006-205867 A

  However, in the power supply system described in Patent Document 1, even if the power consumption is reduced, the power consumption increases as the number of loads increases. Although it is conceivable to use a high voltage system (42V) power source that changes the power source mounted on the vehicle from the low voltage system (14V) to the high voltage system (42V) in order to secure a sufficient amount of power supply. In this case, it is necessary to change the load used in the conventional low voltage system (14V) to correspond to the high voltage system (42V).

  In addition, when using a high-voltage power supply, it is possible to use a step-down DC / DC converter in order to use a load used for a low-voltage system (14 V). It is necessary to newly provide a space for installing the DC converter. Furthermore, since each load is scattered in various places of the vehicle, in the case of a load having a long distance from the power source in the engine room, there is a possibility that power loss during power transmission from the power source becomes large.

  The present invention has been made in view of such circumstances, and an object thereof is to efficiently supply power to a load without changing the load even when a high-voltage power supply is used. To provide a power supply system.

  A power supply system according to the present invention is a power supply system that performs on / off control of a switching element provided in a power line, and supplies and cuts off power from the power supply to the in-vehicle load via the power line. It is configured to output a voltage higher than the allowable value of the voltage to be applied, and a control means for performing on / off control of the switching element so that the voltage from the power supply is pulsed, and at a position closer to the in-vehicle load than the power supply It is provided with the charging / discharging means provided in the said electric power line, and charging / discharging the voltage which became the pulse form by the said switching element.

  In the present invention, the voltage from the power source that outputs a voltage higher than the allowable value of the voltage applied to the vehicle-mounted load is pulsed by the on / off control of the switching element, and charging / discharging of the voltage is used to obtain the voltage from the power source. Can be stepped down. Thereby, since the high voltage of a power supply can be reduced to the voltage suitable for a vehicle-mounted load, a voltage can be supplied from a power supply to a vehicle-mounted load. In this case, by providing charging / discharging means for charging / discharging the voltage for step-down in the vicinity of the on-vehicle load, it is possible to transmit power at a high voltage from the power source to the front of the on-vehicle load. As a result, power loss from the power source to the on-vehicle load can be reduced, and efficient power transmission becomes possible.

  In addition, when the switching element is provided in a power supply system, for example, in a power supply system, it can be equated with a step-down converter only by newly providing charge / discharge means. Furthermore, by reducing the high voltage of the power supply, it is not necessary to change the load to a load corresponding to the high voltage, and an increase in cost can be suppressed.

  In the power supply system according to the present invention, the power supply is a generator, connected to the generator via the switching element and charging / discharging means, and a battery charged by the power generated by the generator. It is further provided with the feature.

  In the present invention, it is possible to charge a battery with a nominal voltage of a power generation voltage of a generator.

  The power supply system according to the present invention is characterized in that the charging / discharging means includes a coil, a capacitor, and a diode.

  In the present invention, the charging / discharging means is constituted by the coil and the capacitor, so that the downsizing can be realized and it is not necessary to secure a wide installation space.

  According to the present invention, the voltage from the power source that outputs a voltage higher than the allowable value of the voltage applied to the vehicle-mounted load is pulsed by the on / off control of the switching element, and charging / discharging of the voltage is used to Can be stepped down. Thereby, since the high voltage of a power supply can be reduced to the voltage suitable for a vehicle-mounted load, a voltage can be supplied from a power supply to a vehicle-mounted load. In this case, by providing charging / discharging means for charging / discharging the voltage for step-down in the vicinity of the on-vehicle load, it is possible to transmit power at a high voltage from the power source to the front of the on-vehicle load. As a result, power loss from the power source to the on-vehicle load can be reduced, and efficient power transmission becomes possible. In addition, since the switching element is generally provided in, for example, a power distributor in a power supply system, it can be regarded as being provided with a step-down converter only by newly providing charging / discharging means. Furthermore, by reducing the high voltage of the power supply, it is not necessary to change the load to a load corresponding to the high voltage, and an increase in cost can be suppressed.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof.

  FIG. 1 is a block diagram schematically showing the configuration of the power supply system according to the present embodiment. The power supply system according to the present embodiment is a system that supplies power to loads 10 and 11, and includes a generator (power source) 1, a power distributor 2, a lead storage battery (battery) 3, a starter disposed in an engine room. 4 and a control unit 5, and an LC circuit (charging / discharging means) 6 disposed in the vicinity of the load 10 and the lead storage battery 3. The loads 10 and 11 are, for example, an electronic control unit (ECU) that controls audio equipment and a security system mounted on the vehicle, an EPS (Electric Power Stealing), and the like, and are scattered in various parts of the vehicle. ing. The load 10 has a drive voltage of 14V, and the load 11 has a drive voltage of 42V.

  The generator 1 is a three-phase AC generator including a regulator (not shown). The generator 1 rectifies the generated AC power into DC power using a rectifier circuit, adjusts the voltage of the rectified power to a voltage of 42 V using a regulator, and outputs the voltage. The generator 1 has a positive terminal connected to the power distributor 2 and a negative terminal grounded. The generator 1 supplies the generated voltage during engine rotation to the lead storage battery 3 and the loads 10 and 11 via the power distributor 2.

  The power distributor 2 includes a plurality of switching elements (SW) S1 to S4. The switching elements S1 to S4 are, for example, N-channel MOSFETs. When a signal is input to the gate, conduction and interruption between the source and the drain, that is, a switching operation is performed. The switching elements S1 to S4 have a source connected to the ground, a gate connected to the generator 1, and a drain connected to the LC circuit 6. Each of the switching elements S1 to S4 is PWM controlled by the control unit 5 described later. The switching elements S <b> 1 to S <b> 3 are connected to the load 10 via the LC circuit 6, and the switching element S <b> 4 is connected to the lead storage battery 3 via the LC circuit 6. The power distributor 2 connects the generator 1 and the load 11 having a drive voltage of 42V without passing through the switching elements S1 to S4 and the LC circuit 6.

  FIG. 2 is a schematic diagram showing the configuration of the LC circuit 6. The LC circuit 6 includes a coil 61, a capacitor 62, and a diode 63. One end of the coil 61 is connected to the switching elements S <b> 1 to S <b> 4, and the other end is connected to the load 10 or the lead storage battery 3. The anode of the diode 63 whose cathode is grounded is connected to the switching element S1 to S4 side terminal of the coil 61. In addition, a capacitor 62 whose one end is grounded is connected to a connection portion between the coil 61 and the load 10 or the lead storage battery 3. That is, the coil 61 and the capacitor 62 are connected to the generator 1 having an output voltage of 42 V via the switching elements S1 to S4.

  In this LC circuit 6, the output voltage 42V from the generator 1 can be stepped down by switching the switching elements S1 to S4 on and off. When the switching elements S1 to S4 connected to the LC circuit 6 are turned on, current flows through the coil 61 and charges are accumulated, the capacitor 62 is charged, and current is also supplied to the load 10 or the lead storage battery 3. The When the switching elements S1 to S4 are turned off, the supply of current to the coil 61 is stopped, but current is supplied from the charged coil 61 to the capacitor 62 and the load 10 or the lead storage battery 3. The Even if the amount of current supplied from the coil 61 decreases, the charge accumulated in the capacitor 62 is supplied to the load 10 or the lead storage battery 3. That is, the voltage applied to the load 10 or the lead storage battery 3 is controlled by the ratio of the time when the voltage is applied from the generator 1 to the coil 61 and the time when the voltage is not applied, in other words, the duty ratio of the switching elements S1 to S4. be able to. Thereby, the voltage of 42V of the generator 1 can be stepped down to 14V and supplied to the load 10 or the lead storage battery 3.

  The LC circuit 6 is disposed in the vicinity of the load 10 and the lead storage battery 3 as shown in FIG. In particular, since the load 10 is scattered in various parts of the vehicle, there is a distance from the generator 1 and the power distributor 2 in the engine room, and the wire harness connecting the generator 1 and the load 10 is Make it longer. For this reason, the internal resistance of the wire harness between the generator 1 and the load 10 is increased, and the voltage applied to the load 10 is lost due to the internal resistance, and there is a case where a sufficient voltage cannot be supplied to each load 10. Therefore, by arranging the step-down LC circuit 6 in the vicinity of the load 10, power can be transmitted at a high voltage of 42 V before the load 10, and sufficient power can be transmitted to the load 10. In addition, by arranging the LC circuit 6 in the vicinity of the load 10, it is not necessary to secure an installation space for the LC circuit 6 in the engine room, and space efficiency can be improved.

  The nominal voltage of the lead storage battery 3 is 12 V, the negative terminal is grounded, and the positive terminal is connected to the LC circuit 6. The lead storage battery 3 charges the power generation voltage generated by the generator 1 that has been stepped down by the LC circuit 6 and the switching elements S1 to S4 in the same manner as the 14V load 10 during engine rotation. The lead storage battery 3 supplies electric power to a starter 4 and a load having a drive voltage of 12 V when the engine is started.

  The starter 4 is connected to a connection portion between the lead storage battery 3 and the LC circuit 6. The starter 4 is composed of an ignition key cylinder that can be rotated by inserting a predetermined key to start the engine. The load supplied with power from the lead storage battery 3 is, for example, a computer device that controls a light or the like, and power for each device to back up various data is supplied from the lead storage battery 3.

  The control unit 5 is, for example, an ECU (Electronic Control Unit), and performs PWM control of the switching elements S1 to S4 of the power distributor 2 under a predetermined condition. Specifically, when the control unit 5 detects on / off of a power switch (not shown) of the load 10 and detects that the power switch is turned on, the control unit 5 performs PWM control of the corresponding switching elements S1 to S4. Do.

  FIG. 3 is a flowchart showing the operation of the control unit 5.

  The controller 5 determines whether or not the engine is rotating (S1). When the engine is rotating (S1: YES), the control unit 5 performs charge control of the lead storage battery 3 (S2). Specifically, the control unit 5 supplies the lead-acid battery 3 with the generated voltage of the generator 1 that has been stepped down by performing PWM control of the switching element S4. Thereby, the lead storage battery 3 is charged. Next, the control unit 5 determines whether or not the load switch is on (S3). The load switch is a power switch of the load 10 having a drive voltage of 14V. When the load switch is not on (S3: NO), the control unit 5 returns the process to S1. When the load switch is on (S3: YES), the control unit 5 performs PWM control of the switching elements S1 to S3 corresponding to the turned on load 10 to step down the generated voltage of the generator 1 (S4). ). As a result, it is possible to supply the load 10 with the power generation voltage of the generator 1 that generates a voltage exceeding the allowable value of the voltage applied to the load 10, and the load 10 can be driven. Then, the control part 5 complete | finishes this process.

  As described above, in this embodiment, the voltage of 42 V generated by the generator 1 is stepped down to 14 V by the switching elements S1 to S3 and the LC circuit 6. Thereby, it can be set as the voltage suitable for the load 10 whose drive voltage is 14V, and the lead acid battery 3 whose nominal voltage is 12V. In this case, the wire harness connecting the generator 1 and the load 10 is long, but by providing the LC circuit 6 in front of the load 10, the high voltage from the generator 1 to the load 10 can be obtained. Power transmission is possible. As a result, power loss from the generator 1 to the load 10 can be reduced, and efficient power transmission becomes possible.

  In addition, since the power distributor 2 including a switching element is generally provided in a power supply system, it can be regarded as being provided with a step-down converter simply by providing the LC circuit 6 in front of the load 10. . Furthermore, by reducing the power generation voltage of the generator 1, it is not necessary to change the load 10 to a load corresponding to a high voltage, and an increase in cost can be suppressed.

  The preferred embodiments of the present invention have been specifically described above. However, each configuration, each processing operation, and the like can be changed as appropriate, and are not limited to the above-described embodiments. For example, in the present embodiment, the power generation voltage of the generator 1 is 42 V and the drive voltage of the load 10 is 14 V, but the voltage value is appropriately changed. In addition, although the charging and charging means of the present invention provided in front of the load 10 is an LC circuit, it may be configured by a separate circuit.

It is a block diagram which shows typically the structure of the power supply system which concerns on this embodiment. It is the schematic which shows the structure of LC circuit. It is a flowchart which shows operation | movement of a control part.

Explanation of symbols

1 Generator (power supply)
2 Power distributor 3 Lead acid battery (battery)
5 Control unit (control means)
6 LC circuit (charging / discharging means)
10 Load S1-S4 Switching element

Claims (3)

In a power supply system that performs on / off control of a switching element provided in a power line, and supplies and shuts off power from the power source to the vehicle load via the power line.
The power supply is
It is configured to output a higher voltage than the allowable value of the voltage applied to the in-vehicle load,
Control means for performing on / off control of the switching element so that the voltage from the power source is in a pulse form;
A power supply system comprising: charge / discharge means that is provided on the power line at a position closer to the vehicle-mounted load than the power supply and charges and discharges a voltage that is pulsed by the switching element. The power source is a generator,
The power supply system according to claim 1, further comprising: a battery connected to the generator via the switching element and charging / discharging means, and charged by the power generated by the generator. The charge / discharge means includes
The power supply system according to claim 1, comprising a coil, a capacitor, and a diode.

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