JP3783913B2 - Electric vehicle power supply device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power supply device for an electric vehicle.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an electric vehicle or the like is mounted with a power supply device called a capacitor (a power source capable of charging / discharging small electric power in a short time by an electrolytic double layer capacitor or the like) in addition to a battery for driving a motor. The power supply device is configured to store energy regenerated by the motor when the vehicle is decelerated, etc., in the capacitor, and to supply power to the motor in an auxiliary manner by discharging this energy during acceleration or the like.
[0003]
As a prior art of this power supply device, Japanese Patent Application No. 10-201091 discloses a method in which a plurality of capacitor cells are connected in series and a resistor is connected in parallel with one capacitor cell via a switch. A configuration for preventing overcharging by connecting a resistor and a cell during charging is described.
[0004]
In Japanese Patent Laid-Open No. 9-322314, a battery and a power capacitor are connected in parallel, and only the capacitor is connected to the load at the time of energy regeneration or at the beginning of discharge. Otherwise, the battery and the capacitor are connected to the load. A connection configuration and a booster circuit for power discharged from the capacitor are described.
[0005]
In addition, JP-A-8-98313 and JP-A-8-98314 have been proposed, and brake regeneration is prohibited during the ABS control (JP-A-11-115743).
[0006]
[Problems to be solved by the invention]
However, when a plurality of capacitor cells are connected in series, the terminal voltage of each cell may vary, or the charge accumulated in a cell having a relatively low terminal voltage may be insufficient and the cell polarity may be reversed. The entire cell may fail.
[0007]
The present invention has been made in view of the above circumstances, and its purpose is to suppress the shortage of electricity stored in a specific cell due to variations in terminal voltage of each cell when a plurality of capacitor cells are connected in series. An object of the present invention is to provide a power supply device for an electric vehicle capable of suppressing a failure.
[0009]
[Means for Solving the Problems]
In order to solve the above problems and achieve the object, a power supply device for an electric vehicle according to the present invention has the following configuration. That is,
A motor for driving the vehicle; regenerative means for regenerating the motor when the vehicle decelerates; regenerative current by the regenerative means; power supply means comprising a plurality of capacitor cells connected in series; and the regenerative current by the regenerative means In a power supply device for an electric vehicle comprising charging means for supplying and charging means, when the terminal voltage of at least one capacitor cell among the plurality of capacitor cells is lower than a terminal voltage of other capacitor cells by a predetermined value or more, An abnormality determination unit that determines that the capacitor cell is abnormal, and at the time of abnormality determination by the abnormality determination unit, at least a part of the charge of another capacitor cell is supplied to the capacitor cell determined to be abnormal and the capacitor cell is restored. Return means.
[0010]
Preferably, the abnormality determination unit detects a terminal voltage of a part of the entire capacitor cell set among the plurality of capacitor cells, and the terminal voltage is equal to or higher than a terminal voltage of other capacitor cell sets. When it is low, the part of the capacitor cell set is determined to be abnormal.
[0012]
【The invention's effect】
According to the first aspect of the present invention, when the terminal voltage of at least one of the plurality of capacitor cells is lower than the terminal voltage of the other capacitor cell by a predetermined value or more, the capacitor cell is determined to be abnormal, and the abnormality determination Sometimes, by supplying at least a part of the charge of another capacitor cell to the capacitor cell determined to be abnormal and returning the capacitor cell, the cell determined to be abnormal cannot be temporarily used due to a short circuit or the like. Can be prevented, and the cell whose terminal voltage has temporarily decreased can be restored.
[0013]
According to the invention of claim 2 , when the terminal voltage of the entire capacitor cell set among the plurality of capacitor cells is detected and the terminal voltage is lower than the terminal voltage of the other capacitor cell set by a predetermined value or more, By determining that some of the capacitor cell sets are abnormal, the configuration can be simplified without monitoring all the cells.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. [Entire configuration of power supply unit]
FIG. 1 is a block diagram showing a power supply device for an electric vehicle according to the present embodiment.
[0015]
As shown in FIG. 1, the electric vehicle according to the present embodiment is an electric vehicle using a motor 1 as a drive source.
[0016]
The power supply apparatus according to the present embodiment includes a motor 1 that drives left and right wheels 7, 8, a main power source 2 that includes a battery and a fuel cell, and an auxiliary power source 3 that includes a plurality of capacitor cells connected in parallel to the main power source 2. And a voltage conversion circuit 4 connected in series to the auxiliary power supply 3, and the main power supply 2 and the auxiliary power supply 3 connected in parallel are connected to the motor 1 via the inverter 5.
[0017]
The voltage conversion circuit 4 is controlled by the controller 10, converts the voltage output from the auxiliary power supply 3 into an appropriate value, and outputs the converted value.
[0018]
The inverter 5 is controlled by the controller 10 to adjust the current value and frequency supplied from the main power source 2 and / or the auxiliary power source 3 to the motor 1, and the electric power regenerated by the motor 1 to the main power source 2 or the auxiliary power source 3. Adjust to charge.
[0019]
A switch 6 is connected between the main power supply 2 and the inverter 5, and on / off of the switch 6 is controlled by the controller 10.
[0020]
The controller 10 includes a CPU, a ROM, a RAM, an interface circuit, and the like. The controller 10 supplies power to the motor 1 from the main power source 2 when the vehicle is running steadily, and the main power source 2 and auxiliary power source when the vehicle is accelerating. Power is supplied to the motor 1 from the motor 3, and the motor 1 is regenerated as a regenerative means at the time of deceleration, and the regenerative current is charged as the charging means to the main power supply 2 and the auxiliary power supply 3, and the voltage conversion circuit 4, the inverter 5 and the switch 6, the output torque of the motor 1, the rotation speed, and the like are controlled.
[Detailed configuration of auxiliary power supply]
<First Embodiment>
FIG. 2 is a circuit diagram showing a detailed configuration of the auxiliary power supply according to the first embodiment.
[0021]
As shown in FIG. 2, the auxiliary power supply 3 is configured such that several hundred capacitor cells C1 to Cn are connected in series, and the controller 10 monitors terminal voltages of the cells C1 to Cn as abnormality determination means. Yes.
[0022]
The emitter and collector portions of the transistor 31 are connected between the terminals of each cell, and the terminals are short-circuited when a base voltage is applied from the controller 10. The terminal voltage is held at a constant voltage (for example, about 2 to 3 V) by the large-capacity Zener diode 32 disposed between the emitter and collector of the transistor 31.
[0023]
When the terminal voltage of at least one capacitor cell is lower than the terminal voltage of another capacitor cell by a predetermined value or more, the controller 10 determines that the capacitor cell is abnormal and applies a voltage to the base portion of the transistor 31 as a short-circuit means. The terminals of the capacitor cells determined to be abnormal are short-circuited.
[0024]
According to the first embodiment, since a plurality of capacitor cells are connected in series, the terminal voltage of each cell varies, and an overvoltage is applied between the terminals, or charges accumulated due to a low voltage are generated. It is possible to prevent the entire cell from failing due to the cell polarity being reversed due to shortage.
[0025]
Further, by making the Zener diode 32 have a large capacity, it is possible to prevent the current discharged from the capacitor cells other than the abnormal cells from bypassing the abnormal cells at the time of discharging and failing to the whole cell.
Second Embodiment
FIG. 3 is a circuit diagram showing a detailed configuration of the auxiliary power supply according to the second embodiment. FIG. 4 is a detailed circuit diagram of the induction circuit of FIG.
[0026]
As shown in FIG. 3, the controller 10 is configured to monitor the terminal voltages of the capacitor cells C1 to Cn as abnormality determination means.
[0027]
A voltage exchange circuit 41 is connected between the terminals of each cell as a return means, and the transformer 42 is configured to make the terminal voltage variation of each cell uniform.
[0028]
The transformer 42 is configured to generate an induced electromotive force in the voltage exchange circuit 41 having a low terminal voltage by the voltage exchange circuit 41 having a high terminal voltage when the terminal voltage of each cell varies.
[0029]
As shown in FIG. 4, in the voltage exchange circuit 41, a transistor 43 and an oscillation circuit 45 are arranged in series on the positive terminal side of the cell, and a transistor 44 and a rectifier circuit 46 are arranged in series with these. The positive side terminal of the capacitor cell is connected between the collector part of the transistor 43 and the emitter part of the transistor 44, and the oscillation circuit 45 and the rectifier circuit 46 are connected to the voltage exchange circuit of another cell. Has been.
[0030]
The bases of the transistors 43 and 44 are insulated by the insulation circuits 48 and 49, and a voltage is applied from the controller 10.
[0031]
When a base voltage is applied from the controller 10 to the transistor 43, the charge of the cell moves, a current flows through the transistor 43 and the oscillation circuit 45, is converted into an alternating current by the oscillation circuit 45, and is output to the voltage exchange circuit of another cell. Is done. Further, when a base voltage is applied from the controller 10 to the transistor 44, a current flows from the oscillation circuit of another voltage exchange circuit to the rectifier circuit 46, and is converted into a direct current by the rectifier circuit 46, and then from the transistor 44 to the positive terminal of the cell. The electric charge of the cell is accumulated.
[0032]
With the above configuration, when there is a cell having a low terminal voltage, an induced electromotive force is generated in a low cell by a cell having a high terminal voltage, so that charges are accumulated in the cell having a low terminal voltage and the terminal voltage can be made uniform.
[0033]
When the terminal voltage of at least one capacitor cell is lower than the terminal voltage of other capacitor cells by a predetermined value or more, the controller 10 determines that the capacitor cell is abnormal and supplies a voltage to the gate portion of the transistor 43 or 44 as a return means. When applied, at least a part of the charge of the other capacitor cell is supplied to the capacitor cell determined to be abnormal and returned.
[0034]
According to the second embodiment, it is possible to prevent a cell determined to be abnormal from being temporarily unavailable due to a short circuit or the like, and to recover a cell whose terminal voltage has temporarily decreased.
<Third Embodiment>
FIG. 5 is a circuit diagram showing a detailed configuration of the auxiliary power supply according to the third embodiment.
[0035]
As shown in FIG. 5, the controller 10 is configured to monitor the terminal voltages of the capacitor cells C1 to Cn as abnormality determination means.
[0036]
A switching circuit 51 is connected between the terminals of each cell as a return means.
[0037]
As shown in FIG. 5, the switching circuit 51 has a source part and a drain part connected between terminals of each cell via a coil 52, and a gate part connected via a series resistor R and a high voltage driver D. MOSFET 53 is provided. The gate voltage is held at a constant voltage by a Zener diode 54 disposed between the source part and the drain part. A diode 55 is disposed between the source part and the drain part.
[0038]
The MOSFET 53 is configured such that when a gate voltage is applied from the controller 10, charges move from a cell having a high terminal voltage to a cell having a low terminal voltage, and the coil 52 performs a switching operation as a constant current source to make the terminal voltage uniform. Yes.
[0039]
With the above configuration, when there is a cell having a low terminal voltage, by applying a rectangular wave gate voltage to the MOSFET 53 of a normal cell, the charge moves from the normal cell and accumulates the charge.
[0040]
When the terminal voltage of at least one capacitor cell is lower than the terminal voltage of the other capacitor cell by a predetermined value or more, the controller 10 determines that the capacitor cell is abnormal and switches the MOSFET 53 with a rectangular wave as a return means to At least a part of the charge of the capacitor cell is supplied to the capacitor cell determined to be abnormal and returned.
[0041]
According to the third embodiment, it is possible to prevent a cell determined to be abnormal from being temporarily unavailable due to a short circuit or the like, and to recover a cell whose terminal voltage has temporarily decreased.
[0042]
In addition, an insulating circuit is not required, it can be driven with high efficiency by switching, and the voltages of all the cells can be made uniform.
<Modification>
In the above embodiment, the terminal voltage is detected for each capacitor cell, but a plurality of aggregates composed of a plurality of capacitor cells are formed, and the terminal voltage of each aggregate is detected and the terminal voltage is detected. Is lower than the terminal voltage of the other aggregate by a predetermined value or more, one of the aggregates is determined to be abnormal, and at least the terminal voltage of the aggregate determined to be abnormal at the time of charging is short-circuited or the charge is moved. It may be restored. Thereby, the configuration of the power supply device can be simplified without monitoring all the cells.
<Other embodiments (1)>
When the main power supply 2 fails or malfunctions, the output characteristics of the auxiliary power supply 3 are constant, so that (i) the acceleration performance deteriorates as the output of the main power supply 2 decreases, (ii) when the output of the main power supply stops There is a problem that the amount of power stored in the auxiliary power supply 3 is also small, and it is impossible to travel immediately.
[0043]
As means for solving the above problems, the following control may be performed. That is,
(I) When the malfunction of the main power supply 2 is detected and there is no fear that the main power supply 2 will stop, the output from the auxiliary power supply 3 is increased from the normal time when the output is reduced.
[0044]
(II) If the malfunction of the main power supply 2 is detected and output is still possible, but it must be stopped after that (for example, after several tens of seconds), the auxiliary power supply 3 is fully charged while suppressing the output. After the vehicle stops, the vehicle is driven by the amount of power stored in the auxiliary power source 3 (to a repair shop or a safe area).
[0045]
(III) When the malfunction of the main power source 2 is detected and the output must be suppressed immediately and stopped quickly, the output is suppressed and the charging and output of the auxiliary power source 3 are stopped to conserve the storage amount. After the main power supply 2 is stopped, the vehicle is driven with the amount of power stored in the auxiliary power supply 3 (to a repair shop or a safe area).
<Other embodiment (2)>
If the auxiliary power supply 3 is fully charged in preparation for acceleration, there is a problem that regenerative power cannot be accepted during downhill driving or sudden braking.
[0046]
As means for solving the above problems, the following control may be performed. That is,
(I) The charge amount of the auxiliary power source is adjusted by predicting the travel path using the map information of the car navigation system.
[0047]
(II) The driving pattern of the driver is learned, and the charging amount optimal for the driving pattern is adjusted.
[0048]
(III) The charge amount of the auxiliary power source can be set by the driver's own judgment.
<Other embodiment (3)>
Since the internal resistances of the main power supply 2 and the auxiliary power supply 3 change due to environmental conditions and the like, (i) the efficiency deteriorates, (ii) when either the main power supply 2 or the auxiliary power supply 3 malfunctions, the output is insufficient. There is a problem of becoming.
[0049]
As means for solving the above problems, the following control may be performed. That is,
(I) The output ratio at which the efficiency is maximized is calculated and controlled from the voltage, temperature, and internal resistance of the main power supply 2 and auxiliary power supply 3. This output ratio may be mapped according to the required output, temperature, voltage, and the like.
[0050]
Note that the present invention can be applied to modifications or variations of the above-described embodiment without departing from the spirit of the present invention.
[0051]
For example, the present invention can be applied to motor control in a hybrid vehicle that travels using both a motor and an engine.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a power supply device for an electric vehicle according to an embodiment.
FIG. 2 is a circuit diagram showing a detailed configuration of an auxiliary power supply according to the first embodiment.
FIG. 3 is a circuit diagram showing a detailed configuration of an auxiliary power supply according to a second embodiment.
4 is a detailed circuit diagram of the induction circuit of FIG. 3;
FIG. 5 is a circuit diagram showing a detailed configuration of an auxiliary power supply according to a third embodiment.
[Explanation of symbols]
1 Motor 2 Main power supply 3 Auxiliary power supply 4 Voltage conversion circuit 5 Inverter 10 Controller

Claims (2)

A motor for driving the vehicle; regenerative means for regenerating the motor when the vehicle decelerates; regenerative current by the regenerative means; power supply means comprising a plurality of capacitor cells connected in series; and the regenerative current by the regenerative means In a power supply device for an electric vehicle comprising charging means for supplying and charging the means,
An abnormality determining means for determining that the capacitor cell is abnormal when a terminal voltage of at least one of the plurality of capacitor cells is lower than a terminal voltage of another capacitor cell by a predetermined value or more;
And a return means for returning at least a part of the charge of the other capacitor cell to the capacitor cell determined to be abnormal when the abnormality is determined by the abnormality determining means. Vehicle power supply. The abnormality determining means detects a terminal voltage of a part of the entire capacitor cell set among the plurality of capacitor cells, and when the terminal voltage is lower than a terminal voltage of another capacitor cell set by a predetermined value or more, The power supply apparatus for an electric vehicle according to claim 1 , wherein the capacitor cell set of the part is determined to be abnormal.

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