JP2000295715A - Power source system of electric automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size and weight of a vehicle-mounted apparatus, make the voltage of a main charge storing device changeable, and improve system efficiency, in an electric automobile in which electric double layer capacitor cells are used in the main charge storing device. SOLUTION: This electric automobile drives a vehicle driving motor via a power converter by the electric power of a vehicle-mounted engine generator and a vehicle-mounted main charge storing device 40 or the power of the vehicle-mounted main charge storing device 40. The main charge storing device 40 consists of at least two battery blocks 10, 11 constituted by connecting a plurality of electric double layer capacitor cells in series, and a current bidirectional type stepping-up chopper 12 connected between the battery blocks 10 and 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply system applicable to a hybrid electric vehicle using an electric double layer capacitor battery as a main power storage device, and other electric vehicles having a main power storage device.

[0002]

2. Description of the Related Art FIG. 10 shows a known power supply system of a hybrid electric vehicle using an electric double layer capacitor battery as a main power storage device. In the past, chemical secondary batteries were used as power storage devices.Chemical secondary batteries have a short charge-discharge cycle life and are inefficient at high-power operation. Is coming.

In FIG. 10, 1 is an engine, 2 is a generator, 3 is a rectifier, 4 is a main power storage device, 5 is an inverter as a power converter for driving a vehicle drive motor 6, and these elements are power trains. Is composed. Reference numeral 7 denotes a DC-DC converter for charging the auxiliary power storage device 8, and reference numeral 9 denotes an auxiliary machine. Here, the illustration of the drive mechanism after the electric motor 6 is omitted. The main power storage device 4 is an electric double layer capacitor battery configured by connecting a plurality of electric double layer capacitor cells 41, 42, 43,. Although not shown, in order to increase the capacity of the main power storage device 4, the electric double layer capacitor cells 41, 42, 43,.
May be connected in parallel with each other.

FIG. 10 shows a series hybrid electric vehicle, in which a main power storage device 4 is charged by using part or all of electric power generated by an engine 1 and a generator 2. Then, using the power generated by the engine 1 and the generator 2 and the power of the main power storage device 4,
The vehicle is driven by the electric motor 6 via the inverter 5. Furthermore, using the power of the generator 2 and the main power storage device 4 or only the power of the main power storage device 4,
To drive the vehicle. At the time of braking, the braking power generated from the electric motor 6 is regenerated to the main power storage device 4 via the inverter 5. The electric system of an electric vehicle that drives a vehicle using only the power of the main power storage device without a generator is shown in FIG.
At 0, the configuration is the same as that of the system without the engine 1, the generator 2, and the rectifier 3, and therefore the detailed description is omitted.

[0005] As described above, the main power storage device 4 repeats discharging and charging when the vehicle is accelerating and running at a constant speed, and reaches several tens of thousands of times. The main power storage device for an electric vehicle must be able to withstand this number of charge / discharge cycles. The above-described electric double layer capacitor battery has this performance, and can be said to be an excellent power storage device for electric vehicles. Main power storage device 4 shown in FIG. 10 also has electric double layer capacitor cells 41 and 4 similarly to a battery pack formed by connecting a number of conventional chemical secondary batteries in series.
2, 43,... Are connected in series, and this is a system in which a conventional chemical secondary battery is replaced with an electric double layer capacitor battery.

The energy stored in an electric double layer capacitor cell is proportional to the square of the voltage of the capacitor cell. In other words, when used as a DC power supply, the voltage of the electric double layer capacitor cell decreases as the discharge energy increases. When 75% of the energy is discharged, the voltage becomes 1 /
Drops to 2. In the electric system shown in FIG. 10, the input voltage of the inverter 5 changes greatly depending on the discharge power.
In particular, in the case of an electric vehicle, when the voltage is reduced, the vehicle performance in a middle to high speed region is significantly reduced. Therefore, in practice, FIG.
As shown in FIG. 1, a method is employed in which a chopper 44 is inserted between a main power storage device 4 as an electric double layer capacitor battery and an inverter 5 and the input voltage of the inverter 5 is made constant by the operation of the chopper 44. .

FIG. 12 shows a detailed circuit configuration of the chopper 44 shown in FIG. 11, and shows a bidirectional current type (two current quadrants).
It is a circuit example of a step-up / step-down chopper. In FIG. 12, FIG.
0, the same components as those of FIG. 11 are denoted by the same reference numerals. 12, reference numerals 441 and 442 denote semiconductor switches composed of transistors, and 443 and 444 denote semiconductor switches 44.
Diodes 445 are connected in anti-parallel to each other, 445 is a current smoothing reactor, and 446 and 447 are filter capacitors.

When the vehicle is accelerating and running at a constant speed, the voltage of main power storage device (electric double layer capacitor battery) 4 is lower than the input voltage of inverter 5, so that chopper 44 is boosted when viewed from main power storage device 4 side. Operate as a chopper. In this case, the semiconductor switch 441 is switched and the semiconductor switch 442 is turned off. FIG. 13 shows an equivalent circuit of this boost chopper, and the semiconductor switch 4 shown in FIG.
42 and the diode 443 are removed.

Next, the operation at the time of regenerative braking will be described. At the time of regenerative braking, the input voltage of the inverter 5 is higher than that of the main power storage device 4, so that the chopper 44 is operated as a step-down chopper when viewed from the inverter 5 side. In this case, the semiconductor switch 4
42, and the semiconductor switch 441 is turned off. FIG. 14 is an equivalent circuit of this step-down chopper, and the semiconductor switch 441 and the diode 44 in FIG.
4 is removed.

Next, FIG. 15 is a view for explaining the operation of the chopper 44 of FIG. Mode I is for acceleration and constant speed driving.
Mode II indicates an operation during coasting, and mode III indicates an operation during regenerative braking. During acceleration / constant speed traveling (mode I), the voltage Vc decreases because the main power storage device 4 discharges, but the input voltage Vi of the inverter 5 is increased by the boosting operation of the chopper 44 (as viewed from the main power storage device 4 side). Is kept constant. During this time, current Ic of chopper 44 (current of reactor 445 in FIG. 12) increases as the voltage of main power storage device 4 decreases.

During regenerative braking (mode III), the regenerative power is supplied to the main power storage device 4 by the step-down operation of the chopper 44 (as viewed from the inverter 5 side) while keeping the input voltage of the chopper 44 constant. Charge. During this time, chopper 4
4 decreases as the voltage of the main power storage device 4 increases.

[0012]

As described above, an electric double layer capacitor battery differs from a chemical secondary battery in that the stored energy is proportional to the square of the voltage. That is, the capacitor voltage greatly fluctuates due to the change in the stored energy. For this reason,
In the conventional system shown in FIG. 11, a current bidirectional buck-boost chopper 44 is connected to the output side of a main power storage device 4 composed of an electric double layer capacitor battery so that the voltage of the main power storage device 4 is constant. ing. In the case of such a chopper system, a current smoothing reactor 445 is indispensable for the chopper 44 as shown in FIG. Further, as is clear from FIG. 15, the current Ic flowing through the reactor 445 is
Is inversely proportional to the voltage Vc of the main power storage device 4, so that when the voltage Vc of the main power storage device 4 is reduced by half, the current Ic of the reactor 445 is reduced.
Is doubled.

Since the maximum operating voltage of the chopper 44 is the same as that of the inverter 5 and the maximum operating current is larger than that of the inverter 5, the power conversion capacity of the chopper 44 is larger than that of the inverter 5. On the other hand, in the case of electric vehicles, the on-board equipment is required to be as small, lightweight and highly efficient as possible, so when using an electric double layer capacitor battery as the main power storage device of an electric vehicle, the chopper is small and lightweight. And high efficiency have been major issues.

As described above, the electric double layer capacitor battery differs from the conventional chemical secondary battery in that the battery voltage greatly changes depending on the use condition of the battery. In a discharge state corresponding to the end of discharge in the case of a chemical secondary battery, the voltage of the capacitor battery becomes almost zero. For this reason, when an electric double layer capacitor battery is used, it is desirable that charging (initial charging) from a voltage of almost zero can be easily performed.

In the conventional power supply system shown in FIG.
Charging from a voltage of the main power storage device 4 of approximately zero (initial charging) or charging below a specified value (preliminary charging) cannot be performed by an onboard engine generator. This is because the engine 1 cannot rotate at an idling rotational speed or less, so the minimum value of the output voltage of the rectifier 3 is determined, and charging cannot be performed unless the voltage of the main power storage device 4 is equal to or more than a specified value. Therefore, in this case, charging is performed using an external power supply as shown in FIG. That is, in FIG.
Reference numeral 00 denotes an external charging power supply device connected to the main power storage device 4. The detailed configuration of the charging power supply device 200 is not the gist of the present invention, and thus the description is omitted here. As described above, the conventional power supply system requires an external charging power supply device for initial charging and the like, and has a problem that the charging operation is troublesome.

[0016]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a battery block formed by connecting a plurality of electric double layer capacitor cells in series. The main power storage device is formed by connecting at least two battery blocks by a current bidirectional buck-boost chopper, and the main power storage device is connected to an inverter. And a plurality of such power converters are connected in parallel. Furthermore, as described in claims 4 and 5, the voltage of the main power storage device is controlled to a preset value by the step-up / down control of the chopper according to the magnitude of the load. According to a sixth aspect of the present invention, the battery block of the main power storage device is initially charged with the power of the vehicle-mounted auxiliary power storage device via a connection cable or a chopper.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. First, FIG. 1 shows a first embodiment of the present invention, which corresponds to the first and third embodiments of the present invention. The same components as those in FIG. 10 are denoted by the same reference numerals. In FIG. 1, reference numeral 40 denotes a main power storage device corresponding to the above-described main power storage device 4, which includes electric double-layer capacitor battery blocks 10, 11 and a current bidirectional lifting device connected between these battery blocks 10, 11. And a pressure chopper 12. Each of the battery blocks 10 and 11 is configured by connecting a plurality of electric double layer capacitor cells 100 and 110 in series. Although not shown, each battery block may be configured by connecting a plurality of series circuits of a plurality of electric double layer capacitor cells in parallel. A DC-DC converter 7 is provided at both ends of the battery block 11.
And the inverter 5 are connected in parallel with each other.

The chopper 12 can be stepped up and down between the battery blocks 10 and 11 by a current two-quadrant operation. The configuration and operation of the chopper 12 will be described later.

FIG. 2 shows a second embodiment of the present invention, and corresponds to the second embodiment of the present invention. The same components as those in FIG. 1 are denoted by the same reference numerals. This embodiment is an example in which the main power storage device shown in FIG. 1 is connected in parallel to the inverter 5, and 40a and 40b in FIG. 2 have the same configuration as the main power storage device 40 in FIG.

FIG. 3 shows a third embodiment of the present invention, which corresponds to an embodiment in which the first embodiment of the present invention is applied to the series hybrid type electric vehicle shown in FIG. 3, the same components as those in FIGS. 1 and 10 are denoted by the same reference numerals, and main power storage device 4 in FIG.
Is replaced by a main power storage device 40.

Next, FIG. 4 is a circuit diagram showing a detailed configuration of the chopper 12 in FIGS. In addition, FIG.
The illustration of the DC-DC converter 7 and the auxiliary power storage device 8 shown in FIG. 3 is omitted. The circuit configuration of the chopper 12 shown in FIG. 4 corresponds to the embodiment of the invention described in claim 3, and is a current bidirectional buck-boost chopper.

In FIG. 4, 121 to 124 are semiconductor switch parts, 125 is a current smoothing reactor connected between the interconnection point between the semiconductor switch parts 121 and 122 and the interconnection point between the semiconductor switch parts 123 and 124, 126 ,
127 is a filter capacitor connected in parallel to the battery blocks 10 and 11, respectively. The semiconductor switch units 121 to 124 are composed of semiconductor switches 121a to 124a formed of transistors and diodes 121b to 124b connected in anti-parallel to these switches.

Next, FIG. 5 shows the behavior of the voltage of the main power storage device 40 when the battery block 10 is discharged at a constant power in the circuit configuration of FIG. In FIG. 5, a is the voltage of the main power storage device 40, b is the battery block 10
Is shown. Further, c indicates the voltage of the main power storage device 4 in the conventional system of FIG.

Mode I in FIG. 5 is an operation range in which the chopper 12 is stepped up to supply power from one of the battery blocks 10 and the output voltage of the entire main power storage device 40 is kept constant. Mode II indicates an operation range in which chopper operation is stopped and power is supplied from the other battery block 11.

FIGS. 6A and 6B are diagrams showing an operation corresponding to the operation modes I and II in FIG. 5. FIG. 6A shows the power flow in the mode I in FIG. 5, and FIG. 6B shows the operation in the mode II in FIG. Are indicated by arrows. FIG. 6 corresponding to operation mode I
In (a), the power of the battery block 10 is supplied to the inverter 5 through the chopper 12, and the operation mode II
In FIG. 6B corresponding to FIG. 6, the electric power of the battery block 11 is directly supplied to the inverter 5 side. As shown in FIG. 5, in the operation mode I, the voltage (characteristic b) of the battery block 10 gradually decreases, but the output voltage (characteristic a) of the entire main power storage device 40 becomes constant by the boosting operation of the chopper 12. Is kept. In operation mode II,
As the voltage of the battery block 11 decreases, the output voltage (characteristic a) of the main power storage device 40 also gradually decreases. It is also possible to supply power simultaneously from the battery blocks 10 and 11, and the flow of power in this case is shown in FIG.
Are indicated by arrows.

FIG. 7 is a detailed explanatory diagram of the operation of the chopper 12 shown in FIG. 4, and the same components as those in FIG. 4 are denoted by the same reference numerals. Circuit component numbers are assigned only to FIG. 7A to avoid complication, and FIG.
(C) and (d) are omitted.

FIG. 7 (a) shows a case where the chopper 12 is stepped up to supply power from the battery block 10 to the battery block 11, and the semiconductor switch 121a is turned on.
The semiconductor switches 122a and 123a are turned off, and the semiconductor switch 124a switches. Semiconductor switch 12
The current path when 4a is turned on is shown by a solid line, and the current path when it is turned off is shown by a broken line.

FIG. 7B shows a case where the chopper 12 is operated to lower the voltage to supply electric power from the battery block 11 to the battery block 10 side.
a, 124a are off, and the semiconductor switch 123a switches. The current path when the semiconductor switch 123a is turned on is indicated by a solid line, and the current path when the semiconductor switch 123a is turned off is indicated by a broken line.

FIG. 7C shows a case in which the chopper 12 is operated to lower the voltage to supply electric power from the battery block 10 to the battery block 11, and the semiconductor switches 122a, 123
a, 124a are off, and the semiconductor switch 121a switches. The current path when the semiconductor switch 121a is turned on is indicated by a solid line, and the current path when the semiconductor switch 121a is turned off is indicated by a broken line.

FIG. 7D shows a case where the chopper 12 is operated to boost the voltage to supply electric power from the battery block 11 to the battery block 10, and the semiconductor switch 123a is turned on.
The semiconductor switches 121a and 124a are turned off, and the semiconductor switch 122a switches. Semiconductor switch 12
The current path when 2a is turned on is shown by a solid line, and the current path when it is turned off is shown by a broken line.

Further, in the power supply system shown in FIG. 1, the voltage of main power storage device 40 can be varied by controlling chopper 12. The traveling power when the vehicle travels at a constant speed on a flat road in a city is about 1/10 of the maximum output. In the case of an electric vehicle, it is desired that the efficiency of the power train is high even in such an operating range. As one of effective means for increasing the efficiency in such an operation range, it is conceivable to reduce the input voltage of the inverter.

FIG. 8 shows a fourth embodiment of the present invention focusing on the above points.
FIG. 7 is an operation explanatory diagram showing the embodiment, and corresponds to the embodiment of the invention described in claims 4 and 5. In FIG. 8, the voltage of the battery block 11 is changed by raising and lowering the chopper 12 with respect to the input voltage of the inverter 5 preset according to the magnitude of the load (the magnitude of the traveling power). Keep the input voltage at the set value. For example, when the voltage of the inverter 5 (the voltage of the battery block 11) is kept high as in the case of acceleration, the chopper 12 is stepped up when viewed from the battery block 10 where the voltage gradually decreases from the initial voltage by discharging. The voltage of the battery block 11 is raised to a predetermined value. At the time of regenerative braking, the battery block 10 is charged by stepping down the chopper 12 when viewed from the battery block 11 side.

FIG. 9 is a circuit diagram showing a fifth embodiment of the present invention, and corresponds to the sixth embodiment of the present invention. This embodiment is a configuration for initially charging the battery blocks 10 and 11 by the chopper 12. When the voltage of the battery block 10 is substantially zero, one battery block 10 and the auxiliary power storage device 8 are connected by the connection cable 300. As the connection cable 300, a booster cable used in a conventional engine automobile can be used.

The auxiliary power storage device 8 and the battery block 10 are connected by a connection cable 300, and the battery block 10 is charged to the voltage of the auxiliary power storage device 8. The charging current at this time is
The current is limited by the internal resistance between the battery block 10 and the auxiliary power storage device 8 and the resistance of the connection cable 300, and both the auxiliary power storage device 8 and the battery block 10 have allowable values. When the voltage of the battery block 10 reaches a specified value (a voltage at which the control operation of the chopper 12 can be performed), the chopper 12 is boosted when viewed from the battery block 10 side, and the other battery block 11 is charged by the auxiliary power storage device 8. do it.

[0035]

As described above, according to the present invention, as a main power storage device of a general electric vehicle or a hybrid electric vehicle powered by a main power storage device, a plurality of battery blocks in which electric double layer capacitor cells are connected in series are provided. Since these blocks are connected by a current bidirectional step-up / step-down chopper, and power is transferred between the battery blocks by the operation of the chopper, the following effects are expected.

(1) A small, lightweight and long-life main power storage device using an electric double layer capacitor battery can be realized, and various practical electric vehicles including a hybrid type can be provided. (2) The chopper can be operated at a voltage with high system efficiency by varying the voltage of the main power storage device, so that fuel efficiency can be improved.

In the above embodiment, the case where the present invention is applied to a series hybrid electric vehicle has been described.
INDUSTRIAL APPLICABILITY The present invention is applicable to various electric vehicle power supply systems such as an electric vehicle using only the main power storage device as a power source, a parallel hybrid electric vehicle, and an electric vehicle equipped with a fuel cell in addition to the main power storage device.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a circuit configuration diagram showing a second embodiment of the present invention.

FIG. 3 is a configuration example when the first embodiment of the present invention is applied to a series hybrid electric vehicle.

FIG. 4 is a detailed circuit configuration diagram of the chopper in FIGS. 1 to 3;

FIG. 5 is a diagram showing a behavior of voltages of a main power storage device and a battery block in FIGS. 1 to 4;

FIG. 6 is an operation explanatory diagram according to the operation mode of FIG. 5;

FIG. 7 is a detailed operation explanatory diagram of the chopper shown in FIG. 4;

FIG. 8 is an operation explanatory view showing a fourth embodiment of the present invention.

FIG. 9 is a circuit configuration diagram showing a fifth embodiment of the present invention.

FIG. 10 is a diagram showing a power supply system of a series hybrid electric vehicle as a conventional technique.

FIG. 11 is a diagram showing a power supply system of a series hybrid electric vehicle as a conventional technique.

FIG. 12 is a detailed circuit configuration diagram of the chopper of FIG. 11;

FIG. 13 is an equivalent circuit diagram of FIG.

FIG. 14 is an equivalent circuit diagram of FIG.

FIG. 15 is an operation explanatory view of the chopper of FIG. 11;

FIG. 16 is a configuration diagram of an initial charging system of a series hybrid electric vehicle as a prior art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Engine 2 Generator 3 Rectifier 5 Inverter 6 Vehicle drive motor 7 DC-DC converter 8 Auxiliary power storage device 9 Auxiliary device 10, 11 Electric double layer capacitor battery block 12 Current bidirectional buck-boost chopper 40 Main power storage device 100, 110 Electricity Double layer capacitor cell 121, 122, 123, 124 Semiconductor switch unit 121a, 122a, 123a, 124a Semiconductor switch 121b, 122b, 123b, 124b Diode 125 Current smoothing reactor 126, 127 Filter capacitor 300 Connection cable

Continuation of the front page (72) Inventor Jun Yamada 1-chome, 1-chome, Ageo-shi, Saitama F-term in Nissan Diesel Industry Co., Ltd. (reference) 5H115 PA12 PC06 PG04 PI11 PI16 PI22 PI29 PO02 PU01 PU21 PU26 PV03 PV07 PV09 PV22 QE05 QE08 QE09

Claims (6)

[Claims] 1. An electric vehicle that drives a vehicle drive motor via a power converter using electric power of an onboard engine generator and an onboard main power storage device or power of an onboard main power storage device, wherein the main power storage device is an electric double layer. A power supply system for an electric vehicle, comprising: at least two battery blocks formed by connecting a plurality of capacitor cells in series; and a chopper connected between these battery blocks. 2. The power supply system for an electric vehicle according to claim 1, wherein a plurality of said main power storage devices are connected in parallel to said power converter. 3. The power supply system for an electric vehicle according to claim 1, wherein the chopper is a current bidirectional buck-boost chopper. 4. The power supply system for an electric vehicle according to claim 1, wherein the voltage of the main power storage device is made variable by controlling the chopper. . 5. The power supply system for an electric vehicle according to claim 4, wherein a voltage of said main power storage device is set to a value corresponding to a magnitude of a load. 6. The power supply system for an electric vehicle according to claim 1, wherein the battery block is initially charged with electric power of a vehicle-mounted auxiliary power storage device via a connection cable or the chopper. A power supply system for an electric vehicle.