JP2004324547A - Power supply equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide power supply equipment which have no effect on other systems even in the case of a big power discharge. <P>SOLUTION: In the power supply equipment 100, a voltage dropper 130 is provided for maintaining a specified voltage in both directions respectively between a battery 110 and a capacitor 120. Consequently, when the engine 200 is rotated and power is generated by a M/G 150, the capacitor 120 is charged at higher voltage than that of the battery 110. In startup of the M/G 150, a big power is instantaneously supplied from the capacitor 120 to the M/G 150, but at this time, power-feed from the battery 110 is not effected until the voltage of the capacitor 120 is sufficiently dropped. As a result, the load connected to the battery 110 is unaffected, and power can be fed stably to other electric systems. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
【Technical field】
The present invention relates to a power supply device suitable for being mounted on, for example, an idle stop type automobile.
[0002]
[Background Art]
2. Description of the Related Art Idle stop type vehicles are being used for the purpose of improving fuel efficiency and exhaust performance of the vehicles. The idle stop method is a method in which the engine is automatically stopped (idle stop) when the vehicle temporarily stops at an intersection or the like, and the engine is automatically started by a motor generator when the vehicle starts moving.
In the idle stop system, a large amount of current is required for a short time when the engine is started after the idle stop is released. For this reason, a large current is discharged from the secondary battery (hereinafter, sometimes simply referred to as a battery), and the battery voltage is reduced, so that the desired characteristics may not be sufficiently exhibited when the engine is started. It may also affect the operation of other electrical systems and systems.
[0003]
In order to cope with this, a method has been considered in which a capacitor such as an electric double layer capacitor (EDLC) is connected in parallel with the battery, and a large current at the beginning of engine start is supplied by discharging this capacitor to reduce the load on the battery. I have. However, simply connecting a capacitor in parallel with a battery does not provide efficient discharge from the capacitor, and does not sufficiently reduce the load on the battery.
Therefore, a device in which an inductor is arranged between a capacitor and a battery and further a switch element such as a voltage detection circuit and a relay is provided has been proposed (for example, Patent Document 1). According to this device, when a large current is required at the start of the motor, at the start of the motor start, only the power from the capacitor is supplied to the motor, and thereafter, in addition to the power from the capacitor, the power from the battery is supplied to the motor. I am trying to do it. As a result, the characteristics of the capacitor, in which the discharge current can flow instantaneously but the voltage drops in a short time, are supplemented by the battery, and the load on the battery is reduced.
[0004]
[Patent Document 1]
JP-A-2002-266730
However, such a conventional device has a problem that it is necessary to provide a capacitor having a considerably large capacity. If the capacity of the capacitor is insufficient, the discharge current from the capacitor will decrease rapidly, and it will be necessary to receive a large amount of current from the battery. Become. Further, if the discharge from the capacitor is not sufficient and a large current cannot be instantaneously supplied, the motor cannot be driven with desired characteristics.
Further, in the device in which the above-described inductor is interposed, a configuration including an inductor, a plurality of relays, switches, logic circuits, and the like is required, and there is a problem that the circuit configuration is large and complicated.
That is, even if a conventional device is provided with a battery and a capacitor, a sufficiently effective method for efficiently driving the motor by using the battery and the capacitor has not been realized. It had been.
[0006]
DISCLOSURE OF THE INVENTION
The present invention has been made in view of such a point, and an object of the present invention is to efficiently use the charge of a capacitor even when supplying a large current to a motor at the time of starting an engine, for example. It is an object of the present invention to provide a power supply device capable of suppressing discharge from a secondary battery (battery), preventing an influence on other electric systems, and efficiently driving a motor.
[0007]
In order to solve the above problem, a power supply device according to the present invention includes a secondary battery to which a first load is connected, a capacitor connected in parallel to the secondary battery to which a second load is connected, A voltage adjusting circuit provided between the secondary battery and the capacitor. When charging the secondary battery and the capacitor, the voltage adjusting circuit applies a voltage higher than the voltage applied to the secondary battery by a predetermined first voltage to the capacitor, and the capacitor and the secondary battery are charged. The voltage applied to the secondary battery and the capacitor is adjusted so that the battery is charged. Further, when discharging is performed from the secondary battery and the capacitor, when the voltage across the capacitor becomes less than a voltage lower by a predetermined second voltage than the voltage across the secondary battery, the capacitor is removed from the secondary battery. The voltage across the secondary battery and the capacitor is adjusted so that power is supplied in the direction.
[0008]
According to the power supply device having such a configuration, the capacitor is charged at a voltage higher than the secondary battery by the first voltage, so that a large amount of electric charges can be efficiently accumulated. In addition, when power is supplied to the second load connected to the capacitor, a large amount of electric charge accumulated at a voltage higher than that of the secondary battery can be instantaneously released and supplied. Therefore, for example, if a motor or the like for starting the engine is connected as the second load, it can be driven appropriately.
Further, even when a large amount of power is discharged from the capacitor to the load connected to the capacitor, power is not supplied from the secondary battery until the voltage across the capacitor is sufficiently reduced. Therefore, in the initial stage of power supply to the second load, power is not supplied from the secondary battery, and the first load connected to the secondary battery has an adverse effect such as a fluctuation or decrease in supply voltage. There is nothing.
Further, if sufficient power cannot be supplied from the capacitor to the second load, and the voltage across the capacitor decreases, that is, the voltage across the capacitor becomes a predetermined second voltage higher than the voltage across the secondary battery. If the voltage becomes lower than the voltage lower by the voltage, power is supplied from the secondary battery to the capacitor, that is, from the secondary battery to the second load. Therefore, if the power of the capacitor is slightly insufficient, power can be appropriately supplied to the second load by power supply from the secondary battery.
[0009]
As described above, according to the power supply device of the present invention, even when a large current is supplied to the motor at the time of starting the engine, for example, the discharge of the secondary battery (battery) is achieved by efficiently using the charge of the capacitor. It is possible to provide a power supply device capable of preventing the influence on other electric systems by suppressing the electric power and efficiently driving the motor.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to FIGS.
In the present embodiment, the present invention will be described by exemplifying a motor that is mounted on an idle stop type vehicle and starts an engine after an idle stop, and a power supply device that supplies power to other electric systems.
[0011]
First, the configuration of the power supply device of the present embodiment will be described with reference to FIGS.
FIG. 1 is a circuit diagram showing a configuration of the power supply device of the present embodiment.
As shown in FIG. 1, the power supply device 100 includes a battery 110, a capacitor 120, a voltage dropper 130, an inverter 140, and a motor generator (M / G) 150.
[0012]
The battery 110 supplies electric power to various electric systems of a connected automobile, specifically, for example, various controller parts, body accessories such as an electric pump, and sensors such as an accelerator sensor, a brake sensor, and a vehicle speed sensor. It is a secondary battery. When the engine 200 is rotating, the power generated by the M / G 150 is supplied to the battery 110 via the inverter 140 and the voltage dropper 130. Thereby, battery 110 is charged to a predetermined charging target voltage (rated voltage).
Further, battery 110 assists discharge from capacitor 120 as necessary when engine 200 starts after an idle stop, and supplies power to M / G 150 via inverter 140. If the voltage of capacitor 120 drops below the voltage of battery 110 by a predetermined voltage value or more before engine 200 starts, battery 110 supplies power to inverter 140 and M / G 150 via voltage dropper 130.
The voltage between the terminals of the battery 110 (sometimes simply referred to as the battery voltage) is defined as Vbatt.
[0013]
The capacitor 120 is an electric double layer capacitor for instantaneously supplying a large amount of power to the M / G 150 when starting the engine 200 after the idle stop. Electric power generated by the M / G 150 during the rotation of the engine 200 is supplied to the capacitor 120 via the inverter 140, whereby electric charges are accumulated. That is, it is charged.
When the engine 200 is started by rotating the M / G 150, the capacitor 120 discharges the accumulated electric charge instantaneously and supplies necessary power to the M / G 150 via the inverter 140.
The voltage between terminals of the capacitor 120 (sometimes simply referred to as a capacitor voltage) is defined as Vcon.
[0014]
The voltage dropper 130 is a voltage adjusting means for electrically connecting the battery 110 side (− side) and the capacitor 120 side (+ side) with the characteristics shown in FIG.
When a voltage is applied from the inverter 140 toward the battery 110 (+ direction), the voltage dropper 130 determines the difference between the voltage Vbatt across the battery 110 and the voltage Vcon across the capacitor 120 as a first turn-on voltage (charging). (Turn-on voltage) when Vdrop1 or more. Thus, when battery 110 and capacitor 120 are charged by the power generated in M / G 150, capacitor 120 is charged at a voltage higher than battery 110 by first turn-on voltage Vdrop1.
[0015]
When a voltage is applied from the battery 110 in the direction of the inverter 140 (− direction), the voltage dropper 130 determines that the difference between the voltage Vcon across the capacitor 120 and the voltage Vbatt across the battery 110 is the second turn-on voltage ( When the voltage becomes equal to or higher than the discharge turn-on voltage (Vdrop2), the transistor is turned on. As a result, when driving the M / G 150, when the capacitor voltage Vcon becomes even lower than the voltage value lower than the battery voltage Vbatt by the second turn-on voltage Vdrop2, power is supplied from the battery 110 to the inverter 140.
As shown in FIG. 2, the charge turn-on voltage Vdrop1 is set to be higher than the discharge turn-on voltage Vdrop2.
[0016]
The voltage dropper 130 having such characteristics can be constituted by the circuit shown in FIG.
As shown in FIG. 3, the voltage dropper 130 includes a first circuit (charging circuit) 131 and a second circuit (discharging circuit) between the capacitor 120 (+ side) and the battery 110 (− side). 132 are arranged in parallel. The first circuit 131, for example, five diodes ₁₃₃ -1 to 133 _-5 is a circuit which direction from the capacitor 120 to the battery 110 is arranged such that the forward direction. The second circuit, for example toward one diode 133 _-6 from the battery 110 to the capacitor 120 is a circuit which is arranged such that the forward direction.
In this embodiment, the diodes ₁₃₃ -1 ～123 _-6 are all the same diode forward turn-on voltage 1 [V]. Therefore, the first turn-on voltage of the first circuit is 5 [V], and the second turn-on voltage of the second circuit is 1 [V]. Thereby, the voltage dropper 130 having the characteristics shown in FIG. 2 is configured.
[0017]
Inverter 140 converts the DC power supplied from capacitor 120 or battery 110 into AC power at the time of starting engine 200, supplies the AC power to M / G 150, and causes M / G 150 to run in power. After the engine is started, AC power sent from M / G 150 is converted into DC power and applied to capacitor 120 and battery 110.
The inverter 140 converts the AC power supplied from the M / G 150 into DC power having a voltage higher than the charging voltage Vbatt of the battery 110 by the first turn-on voltage Vdrop1 and applies the DC power to the capacitor 120 and the battery 110.
[0018]
M / G 150 is a motor generator (motor generator) mechanically connected to engine 200. The M / G 150 is driven by AC power from the inverter 140 when the engine is started after an idle stop, and rotates the engine to a ignitable state. After the engine is started, the motor rotates together with the engine, generates AC power by a rotating magnetic field, and sends out the generated power to the inverter 140.
The voltage of the generated power is adjusted by adjusting the strength of the rotating magnetic field in the M / G 150.
[0019]
Next, the operation of the power supply device 100 will be described with reference to FIGS.
First, the operation of power supply device 100 when battery 110 and capacitor 120 are charged when engine 200 rotates will be described with reference to FIG.
FIG. 4 is a diagram illustrating transition states of the capacitor voltage Vcon and the battery voltage Vbatt when the engine 200 is rotating.
When engine 200 is in a rotating state, M / G 150 connected to engine 200 is forcibly rotated, and AC power is generated. That is, power is generated. The AC power generated by M / G 150 is supplied to inverter 140. Inverter 140 converts AC power supplied from M / G 150 to DC power, and outputs the DC power to capacitor 120 and battery 110.
At this time, the output voltage of inverter 140 is adjusted by controlling the strength of the rotating magnetic field in M / G 150. Specifically, the output voltage is adjusted to be equal to the battery voltage Vbatt + the first turn-on voltage Vdrop1 of the voltage dropper 130.
[0020]
The capacitor 120 is charged by the power supplied from the inverter 140, and the voltage Vcon across the capacitor 120 gradually increases as shown in FIG.
Immediately after the charging of the capacitor 120 is started, the voltage Vcon across the capacitor 120 is lower than the battery voltage Vbatt + the first turn-on voltage Vdrop1. Therefore, the voltage between both ends of the voltage dropper 130 is lower than the turn-on voltage Vdrop1 of the first circuit 131, and the first circuit 131 does not become conductive. Therefore, no current flows from the inverter 140 to the battery 110, and the battery 110 is not charged during this period.
[0021]
As the charging of the capacitor 120 proceeds, the voltage Vcon across the capacitor 120 becomes higher than the battery voltage Vbatt + the first turn-on voltage Vdrop1. In this state, the voltage across the voltage dropper 130 is equal to or higher than the turn-on voltage Vdrop1 of the first circuit 131. Therefore, the first circuit 131 of the voltage dropper 130 becomes conductive, a current flows from the inverter 140 to the battery 110 via the voltage dropper 130, and the battery 110 is charged together with the capacitor 120. As a result, as shown in FIG. 4, the voltage Vbatt across the battery 110 and the voltage Vcon across the capacitor 120 gradually rise together while maintaining the difference between the first turn-on voltage Vdrop1.
Eventually, the voltage Vcon across the capacitor 120 becomes equal to the output voltage of the inverter 140, and the voltage Vbatt across the battery 110 becomes a value lower than the voltage Vcon across the capacitor by the first turn-on voltage Vdrop1, and charging is performed. Complete.
[0022]
Next, the operation of the power supply device 100 when the engine 200 is stopped and when the engine 200 is started from the stopped state will be described with reference to FIG.
FIG. 5 is a diagram showing transition states of the capacitor voltage Vcon, the battery voltage Vbatt, and the motoring current Imotor at the time of starting the engine when the engine 200 starts from a stopped state.
[0023]
When the engine is stopped such as at the time of idling stop, there is no charge, and the power stored in the battery 110 is simply supplied to the electric system of the vehicle. Therefore, the voltage Vbatt across the battery 110 is slightly lower than the open voltage of the battery 110. At the same time, the voltage Vcon across the capacitor 120 is slightly lower than that during charging. At this time, the relationship of the capacitor voltage Vcon = the battery voltage Vbatt + the first turn-on voltage Vdrop1 is maintained.
[0024]
Next, for example, when the accelerator is operated from the idle stop state, power is supplied from the condenser 120 to the M / G 150, and the M / G 150 is rotated, whereby the engine is started.
That is, as shown in FIG. 5, the discharge from the capacitor 120 to the inverter 140 is started, and a large amount of the initial engine start current Imotor flows instantaneously. At the beginning of this discharge, the voltage across the voltage dropper 130 is higher on the capacitor 120 side. Therefore, the second circuit 132 of the voltage dropper 130 does not become conductive, and no discharge from the battery 110 to the inverter 140 is performed.
[0025]
When the discharge from the capacitor 120 is continued, the capacitor voltage drops due to the decrease in electric charge at the same time as the voltage drop due to the internal resistance of the capacitor, and the capacitor voltage Vcon gradually decreases. However, while the capacitor voltage Vcon is maintained within a voltage lower than the battery voltage Vbatt by the second turn-on voltage (discharge turn-on voltage) Vdrop2, this state is maintained, and power is supplied from the battery 110 to the inverter 140. There is no. Usually, during this period, the engine 200 is sufficiently rotated by the M / G 150, and the engine 200 is started. When engine 200 is started, power supply from capacitor 120 to M / G 150 becomes unnecessary, and conversely, charging from M / G 150 to power supply device 100 is started.
[0026]
When the state where the engine 200 is not started continues, the voltage Vcon of the capacitor 120 continuously decreases and becomes lower than the battery voltage Vbatt-the second turn-on voltage Vdrop2. That is, the voltage in the forward direction (the direction from the battery 110 side to the capacitor 120 side) of the second circuit 132 of the voltage dropper 130 is equal to or higher than the second turn-on voltage. As a result, the second circuit of voltage dropper 130 is turned on, discharge from battery 110 to inverter 140 is started, and power is supplied to inverter 140 from both battery 110 and capacitor 120. As a result, both the battery voltage Vbatt and the capacitor voltage Vcon gradually decrease while maintaining the difference between the second turn-on voltages Vdrop2, as shown in FIG.
As described above, power is supplied from battery 110 to inverter 140 only when engine 200 has not been started even after considerable discharge from capacitor 120.
[0027]
Based on the operation of the power supply device 100, the first turn-on voltage Vdrop1, the second turn-on voltage Vdrop2, and the capacitance of the capacitor 120 are set as follows. That is, the charge amount obtained by integrating the motoring current Imotor necessary for starting the engine 200 with time is substantially equal to the capacitor discharge charge amount until the capacitor voltage Vcon decreases to the battery voltage Vbatt-the second turn-on voltage Vdrop2. , These voltage values and capacitances are set. By doing so, it becomes possible to start engine 200 only with the electric power of capacitor 120, and it is possible to avoid power supply from battery 110 to inverter 140. Even if some resistance component is generated or unnecessary power consumption is generated, at least a large decrease in the battery voltage Vbatt due to discharge of a large current from the battery 110 can be avoided.
Further, when starting the engine 200, it is assumed that the capacitor 120 is sufficiently charged. By doing so, it is possible to more reliably start engine 200 only by discharging from capacitor 120.
[0028]
As described above, in the power supply device 100 of the present embodiment, when starting the engine after the idle stop, first, the M / G 150 is rotated using the electric power stored in the capacitor 120. Since the capacitor 120 has a higher voltage than the battery 110 and has a sufficient charge for starting the M / G 150, a large current can be instantaneously supplied and the engine 200 can be started properly.
At this time, battery 110 is substantially separated from capacitor 120 and M / G 150, which is a large-capacity load, by voltage dropper 130, and the power of battery 110 is not used. Therefore, battery 110 can stably supply power to other electric systems without being affected by the discharge of capacitor 120 due to the activation of M / G 150.
Also, if the power from the capacitor 120 alone does not lead to the start of the engine 200 and the output voltage of the capacitor 120 decreases, the supply of power from the battery 110 is started. Therefore, engine 200 can be appropriately started by the electric power from battery 110.
[0029]
Embodiment The power supply device 100 that starts the engine 200 only with the electric power stored in the capacitor 120 is specifically configured. FIG. 6 shows the characteristics.
As the capacitor 120, a capacitor having a capacity of 25 [F] and an internal resistance of 10 [mΩ] was used, and as the battery 110, a secondary battery having an open voltage of 12.0 [V] was used. Further, the voltage dropper 130 is configured so that the first turn-on voltage Vdrop1 of the voltage dropper 130 is 5 [V] and the second turn-on voltage Vdrop2 is 1 [V].
FIG. 6 shows transition of the capacitor voltage Vcon, the battery voltage Vbatt, and the input current Imotor to the inverter when the engine 200 is started under this condition.
[0030]
As shown in FIG. 6, the battery voltage Vbatt before the start of the engine is 12.0 [V] and the first turn-on voltage Vdrop1 is 5 [V], so that the capacitor voltage Vcon is 17.0 [V]. Was.
Immediately after the start of the engine 200 (start of the M / G 150), when the starting current Imotor rises to 350 [A], the voltage drop due to the internal resistance of the capacitor 120 and the voltage drop due to the discharge cause the capacitor voltage Vcon to 13 [V]. Dropped.
Also, 0.4 seconds after the engine 200 started, the capacitor voltage Vcon dropped to 11.1 [V].
However, after that, when the voltage rises due to a decrease in the discharge current and the starting current Imotor becomes unnecessary (when the starting current becomes 0 A), that is, when the engine 200 starts stably, the voltage drop of the capacitor 120 becomes 4. The voltage converged to 6 [V], and eventually the capacitor voltage Vcon became 12.4 [V].
[0031]
As described above, the state where the capacitor voltage Vcon is lower than 11 [V], that is, the voltage of the capacitor 120 at both ends of the voltage dropper 130 is lower than the voltage of the battery 110 by 1 [V] or more, and the second voltage of the voltage dropper 130 Is turned on, and the engine 200 is started without a state in which the discharge from the battery 110 is started. That is, no power is taken out of the battery 110, the power running performance is prevented from deteriorating at the time of starting the engine, and other electric systems and other systems are not adversely affected at all. I could start.
[0032]
The embodiments described above are described for facilitating the understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a configuration of a power supply device according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating characteristics of a voltage dropper of the power supply device illustrated in FIG. 1;
FIG. 3 is a circuit diagram illustrating a configuration example of a voltage dropper of the power supply device illustrated in FIG. 1;
FIG. 4 is a diagram showing transition states of a capacitor voltage and a battery voltage of the power supply device shown in FIG. 1 in a state where the connected engine is rotating after starting.
FIG. 5 is a diagram illustrating transition states of a capacitor voltage, a secondary battery voltage, and a motoring current at the time of engine start when the connected engine starts from a stopped state.
FIG. 6 is a diagram for explaining an operation state in a case where the engine is started only by the electric power of the capacitor in the specific configuration example of the power supply device shown in FIG. 1;
[Explanation of symbols]
100 power supply device 110 battery 120 capacitor 130 voltage dropper 131 first circuit 132 second circuit 133 diode 140 inverter 150 motor generator (M / G)
200 ... Engine

Claims (7)

A secondary battery to which the first load is connected;
A capacitor connected in parallel to the secondary battery and connected to a second load;
A voltage adjustment circuit provided between the secondary battery and the capacitor, wherein during charging, a voltage higher by a first voltage than the voltage applied to the secondary battery is applied to the capacitor, and during discharging, When the voltage across the capacitor is lower than a voltage lower by a second voltage than the voltage across the secondary battery by a second voltage, power is supplied from the secondary battery toward the capacitor. A power supply device comprising: a voltage adjusting circuit that adjusts a voltage between both ends of the capacitor. A first circuit between the capacitor and each positive electrode of the secondary battery, wherein the first voltage is a turn-on voltage from the capacitor to the secondary battery, and 2. The power supply device according to claim 1, wherein the power supply device is a circuit in which a second circuit in which the direction of the capacitor is a forward direction from a battery and the second voltage is a turn-on voltage is connected in parallel. The power supply device according to claim 2, wherein the first circuit and the second circuit are circuits each including a diode. The power supply device according to claim 1, wherein the second voltage is lower than the first voltage. The first load that needs to be constantly supplied with power is connected to the secondary battery side of the voltage adjustment circuit, and power is temporarily and intensively supplied to the capacitor side of the voltage adjustment circuit. The power supply device according to any one of claims 1 to 3, wherein the required second load is connected, and supplies power to each of the first load and the second load. The second load is a motor generator driven by the supplied electric power to start the engine, and is driven by the engine when the engine is rotating to generate electric power. 5. The power supply device according to claim 4, wherein power is supplied to the power generator, and the secondary battery and the capacitor are charged by power supplied from the motor generator when the engine is rotating. The power supply device according to claim 5, wherein supply of electric power to the motor generator for starting the engine is performed when a predetermined condition is satisfied.

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