JP2001054210A - Power-supply system of electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable operation with higher system efficiency by connecting a bidirectional current type voltage variable accumulator between both output terminals of the output of main accumulator and the input terminal of a power converter, for driving a vehicle connected to the terminals of such main accumulator. SOLUTION: A main accumulator 40 is composed of a capacitor battery 10 and a bidirectional current type voltage variable accumulator 11, and its capacitor battery 10 is formed by connecting a plurality of capacity cells 100, in series or by further connecting such capacitor cells 100 in parallel. An inverter 5 is connected as a power converter for driving a vehicle to the output terminal of the output of such a main accumulator 40 or both output terminals thereof, and the bidirectional current type voltage variable accumulator 11 is connected between the position terminal of the inverter 5 and the positive terminal of the capacitor battery 10. As a result, operation of high system efficiency can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a power supply system for an electric vehicle or a hybrid electric vehicle provided with a main power storage device.

[0002]

2. Description of the Related Art FIG. 11 shows a known power supply system of a hybrid electric vehicle using an electric double layer capacitor battery as a main power storage device. Conventionally, a chemical secondary battery has been used as a power storage device. However, recently, an electric double layer capacitor battery has been applied because a chemical secondary battery has a short charge-discharge cycle life and is inefficient at high output operation. ing. In FIG. 11, reference numeral 1 denotes an engine, 2 denotes a generator, 3 denotes a rectifier, 4 denotes a main power storage device, and 5 denotes an inverter which is a power converter for driving a vehicle drive motor 6, and these elements constitute a power train. Make up.

[0003] 7 is a DC-DC for charging the auxiliary power storage device 8
The converter 9 is an auxiliary machine. Here, the electric motor 6
Illustration of the following drive mechanism is omitted. Main power storage device 4
Are electric double layer capacitor cells 41, 42, 43,...
Are connected in series to form an electric double layer capacitor battery. Although not shown, in order to increase the capacity of the main power storage device 4, a plurality of series circuits of the electric double layer capacitor cells 41, 42, 43,...

FIG. 11 shows a series hybrid electric vehicle, in which a main power storage device 4 is charged by using part or all of the electric power generated by an engine 1 and a generator 2. Then, the vehicle is driven by the electric motor 6 via the inverter 5 using only the power of the generator 2 and the main power storage device 4 or the power of the main power storage device 4. When 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 the electric vehicle that drives the vehicle using only the power of the main power storage device without a generator is the same as the system without the engine 1, the generator 2, and the rectifier 3 in FIG. The description is omitted.

[0005] As described above, the main power storage device 4 repeatedly operates during discharging and braking when the vehicle is accelerating and running at a constant speed, and the number of times reaches several tens of thousands. 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. The main power storage device 4 shown in FIG. 11 also has an electric double layer capacitor cell 41, similar to an assembled battery in which a number of conventional chemical secondary batteries are connected in series.
42, 43,... Are connected in series.
This is a system in which a conventional chemical secondary battery is replaced with an electric double layer capacitor battery.

[0006] The stored energy of the 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. 11, the input voltage of the inverter greatly changes depending on the discharge power.

[0007] Particularly in the case of an electric vehicle, when the voltage is reduced, the vehicle performance in a medium to high speed range is greatly reduced. For this reason,
Actually, as shown in FIG. 12, a chopper 44 is inserted between the main power storage device 4 composed of electric double layer capacitor cells 41, 42, 43,. 5 is used to make the input voltage constant.

FIG. 13 shows an example of a circuit configuration of the chopper 44 of FIG. 12, and is a circuit example of a current bidirectional (two-quadrant current) step-up / step-down chopper. The same components as those in FIGS. 11 and 12 are denoted by the same reference numerals. In FIG. 13, 441, 4
42 is a semiconductor switch composed of a transistor;
444 is a diode connected in anti-parallel to the semiconductor switches 441 and 442, 445 is a current smoothing reactor,
6,447 is a filter capacitor.

When the vehicle is accelerating and traveling 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. 14 is an equivalent circuit of the boost chopper in this case, and has a configuration in which the semiconductor switch 442 and the diode 443 in FIG. 13 are removed.

Next, the operation of regenerative braking will be described. At the time of regenerative braking, since the input voltage of the inverter 5 is higher than that of the main power storage device 4, the chopper 44 is operated as a step-down chopper when viewed from the inverter side. In this case, the semiconductor switch 442
And 441 is turned off. FIG. 15 is an equivalent circuit of the step-down chopper in this case, and has a configuration in which the semiconductor switch 441 and the diode 444 in FIG. 13 are removed.

Next, FIG. 16 is a view for explaining the operation of the chopper 44 of FIG. Mode I is for acceleration, running at constant speed,
Mode II indicates an operation during coasting, and mode III indicates an operation during braking.
During acceleration and 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, the current Ic of the chopper 44 (FIG. 13)
The current of the reactor 445 at the time of increases in the power storage device 4. During regenerative braking (mode III), regenerative power is supplied to the main power storage device 4 and charged by the step-down chopper operation of the chopper 44 (as viewed from the inverter side) while keeping the input voltage of the chopper 44 constant.
During this time, the current Ic of the chopper 44 decreases as the voltage of the main power storage device 4 increases.

[0013]

As described above, an electric double layer capacitor 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. 12, a current bidirectional chopper is connected to the output side of the 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. I have to. 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 apparent from FIG. 16, current Ic flowing through reactor 445 is inversely proportional to voltage Vc of main power storage device 4. Therefore, if voltage Vc of main power storage device 4 is reduced by half, current Ic of reactor 445 also doubles. .

When viewed from the input side of the chopper, the device capacity of the chopper 44 is the product of the maximum input voltage and the maximum current. In the case of FIG. 11, the maximum of the input voltage is equal to the maximum voltage of the main power storage device 4, and the maximum of the input current is when the voltage of the main power storage device 4 is used up to 1/2 of the maximum voltage. Double. In this case, the device capacity of the chopper is twice as large as the inverter capacity. On the other hand, for electric vehicles, on-board equipment is as small and lightweight as possible,
Since high efficiency is strongly required, when an electric double-layer capacitor battery is used as a main power storage device of an electric vehicle, the downsizing, weight reduction, and high efficiency of the chopper have been major issues.

[0015]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has one or both output terminals of an output of a main power storage device and a vehicle drive connected to the output terminals. A bidirectional current variable voltage storage device is connected between the input terminals of the power converter, and the DC voltage of the vehicle drive power converter is held at a constant value or a specified value. Furthermore,
The variable voltage power storage device includes an electric double layer capacitor battery and a current bidirectional buck-boost chopper.

[0016]

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 second embodiments of the present invention. The same components as those in FIG. 11 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 and includes a capacitor battery 10 and a bidirectional current variable voltage power storage device 11. The capacitor battery 10 is configured by connecting a plurality of capacitor cells 100 in series, or by connecting a plurality of these in parallel. A current bidirectional voltage variable power storage device 11 is connected between the positive terminal of the capacitor battery 10 and the positive terminal of the inverter 5.

FIG. 2 shows a second embodiment of the present invention, which corresponds to the first and second embodiments of the present invention. The same components as those in FIG. 1 are denoted by the same reference numerals. In this embodiment, a pair of current bidirectional voltage variable power storage devices 11a, 11a
1b is connected between both terminals of the capacitor battery 10 and both terminals of the inverter 5.

FIG. 3 shows in detail the bidirectional current variable voltage storage device of the embodiment of FIG.
This corresponds to the embodiment of the invention described in 4 or 5. The same components as those in FIG. 1 are denoted by the same reference numerals. In FIG. 3, the current bidirectional voltage variable power storage device 11 includes a current bidirectional buck-boost chopper 110 which is a DC-DC power converter, and an electric double layer capacitor battery 111. In addition, the electric motor 6 shown in FIG.
The illustration of the converter 7 and the auxiliary power storage device 8 is omitted.
Here, although the electric double layer capacitor battery 111 is not shown, it is assumed that a plurality of capacitor cells are connected in series similarly to the capacitor battery 10, or that these are further connected in parallel.

In FIG. 3, the current bidirectional type variable voltage storage device 11 is installed on one side between the positive terminal of the capacitor battery 10 and the positive terminal of the inverter 5, but as in FIG. It can also be installed between the negative terminals of the inverter 5. FIG. 4 is a circuit diagram showing a detailed configuration of the current bidirectional buck-boost chopper 110 in FIG. The same components as those in FIGS. 1 to 3 are given the same numbers.

Referring to FIG. 4, a current bidirectional buck-boost chopper 110 includes single-phase inverters 110a and 110b connected to each other via a voltage smoothing capacitor 110e. The single-phase inverter 110a is connected to a power supply side composed of the capacitor battery 10 and the inverter 5 via a reactor 110c.
Are the electric double layer capacitor 111 side and the reactor 110
d. Single-phase inverter 110a,
The control of 110b is publicly known, and the control of these single-phase inverters 110a and 110b is not a subject here, so that the detailed description is omitted.

FIG. 5 is a diagram for explaining the operation when the vehicle performs a power running operation in FIG. 1, and the same components as those in FIG. 1 are denoted by the same reference numerals. In the figure, Vs denotes a terminal voltage of the capacitor battery 10, Vi denotes a DC input voltage of the inverter 5, and Vc denotes a terminal voltage of the current bidirectional voltage variable power storage device 11, respectively. In the figure, since the capacitor battery 10 performs a discharging operation and the vehicle driving motor (not shown) is driven by the power of the capacitor battery 10 via the inverter 5, the current flows in the direction shown by the arrow, and The capacitor voltage Vs decreases with time.

Here, the input voltage Vi of the inverter 5 is
As the sum of the voltage Vs of the capacitor battery 10 and the terminal voltage Vc of the current bidirectional voltage variable power storage device 11, the fluctuation of the voltage Vs of the capacitor battery 10 is compensated by the terminal voltage Vc of the current bidirectional voltage variable power storage device 11. , The input voltage Vi of the inverter 5 is kept constant. That is, the inverter voltage Vi in which the voltage Vs of the capacitor battery 10 is set.
If higher, the terminal voltage Vc of the current bidirectional voltage variable power storage device 11 is made negative with respect to the polarity of the voltage Vs of the capacitor battery 10. This negative portion corresponds to the operation of the portion A from time T0 to T1 in the figure.

On the other hand, when the voltage Vs becomes lower than the set inverter voltage Vi, the terminal voltage Vc is made positive. This positive portion corresponds to the operation of the portion B from time T1 to T2 in the figure. At time T1, since voltage Vs of capacitor battery 10 becomes equal to the set voltage of DC input voltage Vi of inverter 5, voltage Vc of current bidirectional voltage variable power storage device 11 becomes zero.

FIG. 6 is a diagram for explaining the operation when regenerative braking is performed in FIG. 1, and the same components as those in FIG. 5 are denoted by the same reference numerals. In the figure, the current direction is opposite to that in FIG. In this case as well, the terminal voltage Vc of the bidirectional current variable voltage storage device 11 changes according to the voltage Vs of the capacitor battery 10 in order to keep the DC input voltage Vi of the inverter 5 constant, as in the case of FIG. I do.

FIG. 7 shows, in addition to the operation in FIG. 5, the electric double layer capacitor battery 111 in the voltage variable power storage device 11.
FIG. 4 is an operation explanatory diagram including the above. Hereinafter, description will be made with reference to FIG. 7, the voltages Vs, Vc and Vi are the same as those in FIG. Vcs is the voltage of the electric double layer capacitor battery 111. First, at time T0 at the start of powering, the voltage Vcs is zero. Next, at times T11 and T12, Vcs and Vc match. That is, since Vc> Vcs in the section from time T0 to T11 in mode 1, the chopper 110 performs a charge / step-down operation when viewed from the capacitor battery 10 and the inverter 5 side.

In the interval from time T11 to T1 of mode 2, Vc
Since s> Vc, the chopper 110 similarly performs a charging / boosting operation. At T1, since Vs = Vi, Vc = 0
Becomes In the section from time T1 to T12 in mode 3, the voltage polarity of Vc is inverted, and its value increases with the passage of time. The operation of the chopper 110 during this time is a discharging / boosting operation. In the section from T12 to T2 in mode 4, since Vc> Vcs, the chopper performs a discharge / step-down operation.

FIG. 8 is a diagram for explaining the circuit configuration and operation of the capacitor battery 10 shown in FIG. 1 in the case of a power storage device in which the parallel connection of the capacitor battery cells is switched by a built-in switch. The same components as those in FIG. 5 are denoted by the same reference numerals. In the figure, the case of the power running operation is shown. In the figure, 10a is an electric double layer capacitor battery composed of a plurality of capacitor battery blocks. 1
Reference numeral 0b is a changeover switch circuit that switches the circuit of the capacitor battery block. Here, this capacitor battery 10a
The description of the configuration of the switch circuit 10b is omitted.

In FIG. 8, the mode 1 is the same as the operation from the operation T0 to T2 shown in FIG. At the end of mode 1 (T1), the capacitor battery 10a
When the voltage Vs decreases to the operation lower limit, the changeover switch circuit 10b is operated to switch the circuit of the capacitor battery block, and the voltage Vs is returned to the initial value. Thereafter, the same operation as mode 1 is repeated as mode 2.

Here, when the voltage Vs reaches T2 and the voltage Vs drops again to the lower limit of operation, the changeover switch circuit 10b is operated again to switch the circuit of the capacitor battery block, and the voltage Vs is returned to the initial value. The same operation as in mode 1 is performed. Although FIG. 8 illustrates the powering mode, in the case of regenerative braking, the operation is performed in the reverse direction of FIG. Become.

FIG. 9 shows a third embodiment of the present invention, and corresponds to the sixth embodiment of the present invention. 9 is a circuit configuration in which main power storage devices 40 shown in FIG. 1 are connected in parallel. The same circuit components as those in FIG. 1 are given the same numbers. Reference numerals 40a and 40b are main power storage devices corresponding to the main power storage device 40 in FIG.

FIG. 10 shows a circuit configuration in a case where the present invention is applied to a hybrid electric vehicle using a vehicle-mounted engine generator as a power source. In FIG. 10, an engine 1, a generator 2 and a rectifier 3 are added to the configuration of FIG. 1, and the configuration and operation of each part are common to the description of FIG. 1 and FIG. Omitted.

[0032]

As described above, according to the present invention, the output of a capacitor battery in which electric double layer capacitor cells are connected in series is supplied to the output of a voltage variable type comprising an electric double layer capacitor battery and a current dual type step-up / step-down chopper. Connect the power storage device,
The following effects can be obtained by using the power supply system of an electric vehicle or a hybrid electric vehicle. (1) It is possible to realize a small, lightweight, long-life main power storage device of an electric vehicle using an electric double layer capacitor battery, and a practical electric vehicle and a hybrid vehicle can be realized.

(2) The variable voltage type power storage device allows the inverter input voltage to be variable to enable operation with high system efficiency, thereby improving fuel efficiency. In the above embodiment, the case where the present invention is applied to a series hybrid electric vehicle has been described.
The present invention can be applied to a power supply system of various electric vehicles 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 configuration diagram of a power supply system of an electric vehicle according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a power supply system of an electric vehicle according to a second embodiment of the present invention.

FIG. 3 is a detailed configuration diagram of a power supply system according to the first embodiment of the present invention.

4 is a circuit configuration diagram of the current bidirectional voltage variable power storage device of FIG. 3;

FIG. 5 is an explanatory diagram of the operation of FIG. 1;

FIG. 6 is an explanatory diagram of the operation of FIG. 1;

FIG. 7 is an explanatory diagram of the operation of FIG. 3;

FIG. 8 is an explanatory diagram of another operation of FIG. 3;

FIG. 9 is a diagram showing a third embodiment of the present invention.

FIG. 10 is a configuration example when the embodiment of FIG. 1 is applied to a hybrid electric vehicle.

FIG. 11 is a diagram showing an electric system of a conventional example.

FIG. 12 is a diagram showing another conventional electric system.

FIG. 13 is a detailed explanatory diagram of FIG. 12;

FIG. 14 is an operation explanatory diagram of FIG. 12;

FIG. 15 is an operation explanatory diagram of FIG. 12;

FIG. 16 is a diagram illustrating the operation of FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 engine 2 generator 3 rectifier 4 main power storage device 5 inverter 6 vehicle drive motor 7 DC-DC converter 8 auxiliary power storage device 10, 10a, 111 electric double layer capacitor battery 10b changeover switch circuit 11, 11a, 11b current bidirectional voltage Variable power storage devices 40, 40a, 40b Main power storage device 100 Electric double layer capacitor cell 110 Current bidirectional buck-boost chopper 110a, 110b Single-phase inverter 110c, 110d Reactor 110e Voltage smoothing capacitor

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Jun Yamada 1-1-1, Oaza, Ageo-shi, Saitama F-term in Nissan Diesel Industry Co., Ltd. 5H115 PA12 PA15 PC06 PG04 PI13 PI16 PI22 PI29 PO02 PO06 PO17 PU08 PU24 PU25 PU26 PV02 PV03 PV07 PV09 PV23 QE01 QE03 QE09 QE10 QI04 SE04 SE06 TI05 TO13

Claims (6)

[Claims] 1. A power supply system for an electric vehicle that drives a vehicle drive motor via a power converter using electric power of a vehicle-mounted engine generator and a vehicle-mounted main power storage device or power of the vehicle-mounted main power storage device. A power supply system for an electric vehicle, wherein a voltage variable power storage device is connected between an output terminal of one or both poles of the device and a DC terminal of the power converter. 2. The power supply system for an electric vehicle according to claim 1, wherein said main power storage device is constituted by an electric double layer capacitor battery. 3. The power supply system for an electric vehicle according to claim 1, wherein said variable voltage power storage device comprises a second power storage device and a DC-DC power converter. Power system. 4. The power supply system for an electric vehicle according to claim 3, wherein the second power storage device is constituted by an electric double layer capacitor battery. 5. The power supply system for an electric vehicle according to claim 3, wherein the DC-DC power converter is constituted by a current bidirectional buck-boost chopper. 6. The power supply system for an electric vehicle according to claim 1, wherein a plurality of combinations of the main power storage device and the variable voltage power storage device are provided and connected in parallel with each other. A power supply system for an electric vehicle.