JPH04183206A - Driver for electric automobile - Google Patents

Abstract

PURPOSE:To sustain emergency traveling by driving a traction motor with an AC power produced from an inverter when the battery voltage is higher than a threshold whereas chopping the output of a DC converter and driving a sub-motor when the battery voltage is lower than the thresold. CONSTITUTION:When the voltage V10 of a battery 10 is higher than a threshold, an ECU 32 drives an inverter 12 with the battery voltage V10 to produce three- phase AC power for rotating a traction motor TM 14 and thence rotating right and left wheels 30 through a reduction gear 26 and a differential gear DG 28. When the ECU 32 detects the battery voltage V10 drop below the threshold, operation of the inverter 12 and the TM 14 is stopped. At the same time, low DC voltage of a battery 18 for a DC/DC converter 16 and an auxiliary machine is inverted through a chopper controller 34 into an AC voltage for rotating a sub-motor 36 and thence rotating the right and left wheels 30 through the reduction gear 26 and the DG 28. According to the constitution, residual capacity can be utilized effectively and emergency traveling is sustained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a drive device for an electric vehicle, and particularly to an auxiliary drive means when the battery voltage decreases.

[Prior Art] An electric vehicle employs an induction motor as a motor driven vehicle. :J is equipped with a rechargeable battery, and the DC voltage output from this batch is converted to AC voltage by an inverter, and the motor is driven by this AC voltage.

FIG. 8 shows the configuration of a drive device for an electric vehicle according to a conventional example. The device shown in this figure has a similar configuration to the device disclosed in, for example, Japanese Utility Model Application Publication No. Sho 62-140802.

In this figure, a rechargeable battery 10, for example a zinc bromine battery, is shown connected to a motor 14 via an inverter 12. That is, the DC voltage output from the battery 2o is converted into an AC voltage by the inverter 12 and supplied to the motor 14. The motor 14 is supplied with alternating current voltage and rotates to generate driving force for the electric vehicle.

In addition, in this conventional example, the main battery 1° is DC/
It is connected to an auxiliary battery 18 via a DC converter 16. The auxiliary battery 18 is a battery that supplies power to an electrical auxiliary machine (lamp, wiper, etc.) 20 mounted on the electric vehicle.

The DC/DC converter 16 converts the DC voltage related to the output of the main battery 10 into the charging voltage of the auxiliary battery 18 .

Therefore, in this conventional example, the output voltage of the main battery 10 is converted into a DC voltage of a different value by the DC/DC converter 16, and the auxiliary battery 18 is charged. Further, current is supplied to the electrical auxiliary equipment 20.

A changeover switch 22 is provided between the main battery 10 and the DC/DC converter 16.

One end of the changeover switch 22 is connected to the electrolyte circulation system 24.
It is connected to the. This electrolyte circulation system 24 is a system for circulating the electrolyte in the main battery 10. The main battery 10 is configured as a zinc bromine battery as described above, and it is necessary to circulate the electrolyte in order to drive the main battery 10. The electrolyte circulation system 24 is a system that controls this circulation.

The changeover switch 22 is controlled by an ECU (not shown). For example, if the voltage of the live battery 1° decreases due to discharge and becomes unable to supply sufficient power to drive the motor 14, the ECU will switch the selector switch 2.
2 is switched, and the auxiliary battery 18 is connected to the motor 14 via the DC/DC converter 16, the changeover switch 22, and the inverter 12. In this case, the motor 14 will be driven by the voltage of the auxiliary battery 18.

[Problem 8 to be solved by the invention] In this way, conventionally, when the main battery is discharged and the motor cannot be driven (so-called main battery exhaustion), the motor is powered by the power of the auxiliary battery. It was being driven. However, the energy stored in the auxiliary battery is smaller than the energy stored in the main battery, and the motor cannot be driven for a long time. That is, although it is possible to temporarily drive an electric vehicle by driving a motor using an auxiliary battery, the electric vehicle becomes unable to run in a relatively short period of time.

The present invention was made with the aim of solving these problems, and it is possible to continue driving the motor by effectively utilizing the energy remaining in the main battery when so-called main battery rise occurs. The purpose is to

[Means for Solving the Problems] In order to achieve such an object, the present invention provides a battery having a characteristic that the output DC voltage decreases with discharge, and an AC battery that alternates the DC voltage output from the battery. An inverter that converts the voltage into voltage, a traction motor that is rotationally driven by AC voltage from the inverter and generates the driving force of an electric vehicle, a transmission system that transmits and supplies the driving force of the traction motor to the wheels, and a traction motor and transmission system. A drive device for an electric vehicle comprising: a first connection means for disconnecting the connection of the battery; and a DC/DCC/type converter for converting the DC voltage output from the battery into a DC voltage of a lower value. /DCC/ a sub-motor rotationally driven by a direct current voltage from a motor and connected to a transmission system; a second connection means for disconnecting the sub-motor from the transmission system;
A means for determining whether the DC voltage output from the battery has decreased to at least a threshold voltage sufficient to supply driving power to the traction motor; and and means for controlling the first coupling means and the second coupling means to disconnect the traction motor from the transmission system and to couple the sub-motor to the transmission system when the battery voltage drops below a threshold voltage. In this case, the sub motor is driven by the battery to drive the electric vehicle.

[Function] In the electric vehicle drive device of the present invention, when the battery is outputting sufficient voltage, in step 143, the DC voltage output from the battery is converted to AC voltage by the inverter, and this DC voltage The traction motor is driven.

On the other hand, when the battery discharges and the DC voltage related to the output decreases, at a certain point it becomes impossible to supply the power necessary to drive the traction motor. In this case, that is, when the output voltage of the battery drops below the threshold voltage, the sub-motor is connected to the transmission system. That is, the electric vehicle is driven by a sub-motor instead of a traction motor. In addition, the driving voltage of the sub motor is DC from the battery.
/DC converter.

Therefore, in the present invention, even if the battery output voltage decreases due to discharge, it is possible to effectively utilize the remaining power of the battery to drive the electric vehicle.

[Examples] Hereinafter, preferred embodiments of the present invention will be described based on the drawings. Note that components similar to those of the conventional example shown in FIG. 8 are designated by the same reference numerals, and explanations thereof will be omitted.

FIG. 1 shows the configuration of an electric vehicle drive device according to a first embodiment of the present invention.

In this figure, a main battery 10 that outputs, for example, 200 cm of direct current is connected to a traction motor 14 via an inverter 12. The DC voltage output from the main battery 10 is converted into a three-phase AC voltage by an inverter 12 and supplied to the traction motor 14. The traction motor 14 is rotationally driven by this AC voltage.

The traction motor 14 is connected to wheels 30 via a reduction gear 26 and a differential gear (differential) 28. That is, the rotational driving force of the traction motor 14 is supplied to the wheels 30 via the reduction gear 26 and the differential 28, and becomes the driving force of the electric vehicle.

In addition, in this figure, E, which controls the inverter 12,
CU32 is shown. ECU32 is main battery 1
0 voltage (battery voltage), an accelerator signal, an ignition (IG) signal, and a component abnormality signal, and controls the inverter 12 based on these signals.

On the other hand, the main battery 10 has a DC/DCC/formula-ta 16.
is connected, and an auxiliary battery 18 is connected to the DC/DCC/type controller 16.

The DC/DCC/equation converter 16 converts the output voltage of the main battery 1° into DC voltages of different values and supplies them to the auxiliary battery 18. The auxiliary battery 18 drives an electrical auxiliary machine (not shown).

After the auxiliary battery 18, there is a chopper controller o--7.
34 are provided. A sub motor 36 is further connected to the chopper controller 34. Sub motor 3
Reference numeral 6 denotes a motor driven by an alternating current voltage supplied from the chopper controller 34, and is a motor driven at a voltage lower than that of the traction motor 14, for example, 14V. That is, the voltage output from the DC/DCC motor 16 and the auxiliary battery 18 is chopped by the chopper controller 34 in accordance with commands from the ECU 32, and is supplied to the sub-motor 36 as an alternating current voltage.

The sub motor 36 is connected to the reduction gear 26 like the traction motor 14. FIG. 2 shows the configuration of the reducer 26.

In this figure, the speed reducer 26 includes two one-way clutches 38 and 40. One one-way clutch 38 is provided on a shaft that receives the rotational driving force of the sub-motor 36. Also, the other one-way clutch 4
0 is provided on the shaft that receives the rotational driving force of the traction motor 14. The shaft related to the one-way clutch 38 is connected to the shaft related to the one-way clutch 40 at a predetermined gear ratio (
For example, they are connected in a ratio of 1:3). The one-way clutches 38 and 40 are clutches that transmit rotational driving force to the output side only when the input side rotates, and do not transmit rotational driving force to the input side when the output side rotates. Therefore, when the traction motor 14 is rotating and the sub motor 36 is not rotating, the traction motor 1
4 will be transmitted to the output shaft of the reducer 26, and if the traction motor 14 is not rotating and only the sub-motor 36 is rotating, the rotational driving force of the sub-motor 36 or the one-way clutch will be transmitted to the output shaft of the reducer 26. The signal is transmitted to the output shaft of the speed reducer 26 via 38. These rotational driving forces become driving forces for the wheels 30 via the differential 28 as described above.

Next, the operation of the ECU 32 in this embodiment, particularly the control of transition from the traction motor 14 to the sub-motor 36, will be described. FIG. 3 shows the flow of transition control.

The ECU 32 controls whether the battery voltage or the traction motor 14
If the value is sufficient to drive the normal drive control 10
Execute 0. At this moment, the ECU sends an accelerator signal indicating the accelerator opening degree, an IG signal indicating that the ignition switch is turned on, an abnormal operation of battery 1 and each device installed in the electric vehicle (battery 10 Liquid leakage,
Captures component abnormality signals indicating overheating, etc.).

In other words, when the xcr,, signal is turned on, ECU3
2 sets the rotation speed and current command to the inverter 12 in response to the accelerator signal, and controls the drive of the traction motor 14. Further, when a component abnormality signal is generated, the ECLI 32 controls the inverter 12 to stop driving the traction motor 14.

In this embodiment, it is determined whether the battery voltage is a voltage that can drive the traction motor 14 (102). As shown in FIG. 4, the battery voltage gradually decreases as the discharge progresses. In this example, the battery voltage gradually decreases from the initial voltage of 200 V until it reaches the threshold voltage. Judgment 102
t11 is determined at . However, the threshold voltage is set to a value that is slightly higher than the voltage at which the traction motor 14 cannot be driven. Actually, it may be about 130 to 140V. As a result of this determination, if it is determined that the voltage is 150V or more, the drive control 100 is continued to be executed, but in other cases, the process moves to the following operation.

That is, CA indicating that the voltage of the battery 10 has decreased.
The UTI ON lamp is lit and judgment 103 is made.
is executed. In determination 103, it is determined whether the voltage of battery 10 is a voltage that can drive sub-motor 36. Specifically, the voltage of battery]0 is 100
It is determined whether or not it is equal to or greater than V.

If it is determined in determination 103 that the vehicle can be driven,
The voltage of the battery 10 is 100V or more and less than 150V. That is, the voltage is such that the traction motor 14 cannot be driven or the sub motor 36 can be driven. In this case, decision 104 is subsequently executed.

In determination 104, it is determined whether the DC/DCC/type controller 16 is operating normally.

If the DC/DCC/type motor 16 is not functioning normally, the sub motor 36 shown below cannot be driven normally, so the ECU 32 controls the inverter 12 to stop the electric vehicle from being driven by the traction motor 14. The drive is stopped and the drive by the sub motor 36 is also prevented. In the above-mentioned determination 103, if the battery 10
Similar processing is also executed when it is determined that the voltage is not a voltage that can drive the sub motor 36.

If it is determined that the DC/DCC/equation controller 16 is operating normally, the rotation speed command value N and current command value 1 determined in the drive control 100 are changed (
106). That is, in step 106, IG
A new rotational speed command value N- and current command value I' are determined in response to the accelerator signal only when the double signal is turned on.

The traction motor 14 is a motor that can secure a relatively large output torque T to the sub motor 36 as shown in FIG.

Therefore, when changing the settings in step 106, it is necessary to change the rotation command value and the current command value based on FIG. 5. Specifically, in step 106,
By multiplying the rotational speed command value N obtained in the drive control 100 by the gear ratio of the reducer 26 (gear ratio of the input shaft from the traction motor 14 to the input shaft from the sub-motor 36), the output shaft of the reducer 26 is A new rotational speed command value N- is determined so that the rotational speeds match.

In addition, the torque generated in the traction motor 14 based on the current command value I determined in the drive control 100 and the new current command value
The torque generated in the sub motor 36 based on
A new current command value {circle over (x)} is determined so that the output shafts of the speed reducer 26 are equal or the difference is reduced.

Next, the voltage V- of the sub-motor 36 is determined so as to satisfy the conditions of the rotational speed command value N' and the current command value I- obtained in this way (108).

The ECU 32 controls the chopper controller 34 based on v'' obtained in this way.

Further, the ECU 32 stores the relationship between the voltage V' and the duty ratio as a map. The ECU 32 outputs a voltage V-
The duty ratio is determined by referring to this map, and the chopper frequency is determined (110). The chopper controller 34 controls the sub-motor 36 according to the chopper frequency thus determined (112), and the sub-motor 36 is driven (114). After this, the process returns to determination 103.

Therefore, in this embodiment, even if the battery 10 is discharged to a level insufficient to drive the traction motor 14, the sub motor 36 can be driven using the power remaining in the battery 10. Conventionally, the limit was about -20% of SOC (remaining capacity), but it is now possible to use the battery 10 up to approximately 5OC=0%. As a result, an emergency run of about 3 to 5 minutes is possible. In the conventional method using an auxiliary battery, it took about several tens of seconds.

Further, at this time, switching control is performed from the traction motor 14 to the sub-motor 36 so that the torque output to the wheels 30 matches the rotational speed, so that no shock or the like occurs due to switching of the motor.

Furthermore, when the ECU 32 controls the maximum torque Tmax related to the warning in the drive control 100,
Control related to this warning can also be maintained in drive control of the sub motor 3'6.

Warnings are carried out as shown in FIG. 6 for boat fishing. That is, in a state where the battery voltage ■ continues to decrease and approaches the threshold value related to determination 102, the ECU
32 reduces the maximum torque Tmax to warn the operator. As a result, the electric vehicle is no longer accelerated even though the driver depresses the accelerator, so that the driver can sense a voltage drop in the battery 10.

In this embodiment, this warning is further continued and the amount of warning is gradually increased even when the sub motor 36 is driven, so that it is possible to continue warning the operator. In addition, such control makes it possible to match the accelerator feel when switching from the traction motor 14 to the sub motor 36.

Further, the sub motor 36 is one of the traction motors 14.
The motor has a volume of about 1/20 to 1/20. Thereby, the above effects can be obtained with a compact device configuration.

FIG. 7 shows the configuration of a drive device for an electric vehicle according to a second embodiment of the present invention. As shown in this figure, this embodiment has a configuration in which the sub motor 36 is provided on the output side of the reduction gear 26. Even with such a configuration, the same effects as in the first embodiment described above can be obtained.

[Effects of the Invention] As explained above, according to the present invention, when the output voltage of the battery drops below the threshold voltage, the electric vehicle is driven by the sub motor i instead of the traction motor, and the driving voltage of the sub motor is Since the power is obtained from the battery, the remaining capacity of the battery, which was not used in the past, can be effectively utilized. As a result, it is possible to extend the emergency travel distance when the battery voltage drops.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the drive device of an electric vehicle according to the first embodiment of the present invention, FIG. 2 is a diagram showing the configuration of the reduction gear in this embodiment, and FIG. Figure 4 is a flow chart showing the transition control when switching from traction motor to sub motor, Figure 4 is a diagram showing a battery discharge curve, Figure 5 is a diagram showing changes in torque characteristics accompanying switching from traction motor to sub motor, Figure 6 is a diagram showing the relationship between torque and battery voltage when performing a warning, FIG. 7 is a diagram showing the configuration of an electric vehicle drive device according to a second embodiment of the present invention, and FIG. 1 is a diagram showing a configuration of a drive device for an electric vehicle according to an example. 10...Battery 12...Inverter 14...Traction motor 16...DC/DC converter 26...Reducer 28...Differential gear 30...
Wheel 32...ECU 34...Chopper controller 36...Sub motor 3.8.4.0...One-way clutch■ ・
・・Battery voltage

Claims (1)

[Scope of Claims] A battery having a characteristic that the output DC voltage decreases as it discharges, an inverter that converts the DC voltage output from the battery into an alternating AC voltage, and an electric motor that is rotationally driven by the AC voltage from the inverter. A traction motor that generates the driving force of the vehicle, a transmission system that transmits and supplies the driving force of the traction motor to the wheels, a first connecting means that disconnects the connection between the traction motor and the transmission system, and a power output from the battery. A drive device for an electric vehicle includes a DC/DC converter that converts a DC voltage to a DC voltage of a lower value. a second connection means for disconnecting from the transmission system; and means for determining whether the DC voltage output from the battery has decreased to at least a threshold voltage sufficient to supply driving power to the traction motor. , means for controlling the first connecting means and the second connecting means to disconnect the traction motor from the transmission system and connect the sub-motor to the transmission system when the DC voltage output from the battery drops below a threshold voltage; What is claimed is: 1. A drive device for an electric vehicle, comprising the following: When the voltage of the battery drops below a threshold voltage, the battery drives a sub-motor to drive the electric vehicle.