JPH0819116A - Driver for motor driven vehicle - Google Patents

Abstract

PURPOSE:To improve traveling performance such as a traveling distance, accelerability, gradability, etc., by providing the merits of both a battery having a large output density and a battery having large energy density. CONSTITUTION:A driver 10 comprises a lead oxide battery 12 as a battery having a large output density, a sodium-sulfur battery 14 as a battery having large energy density, a motor 18 for rotating drive wheels 16, and an encoder 20 as motor speed detecting means for detecting the number of revolutions N of the motor 18. The driver further comprises a controller 22 for supplying power from the battery 12 to the motor 18 when the number of revolutions N is higher than that detected by the encoder 20 is high and power from the battery 14 to the motor 18 when the number of revolutions N is lower.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive system for an electric vehicle that runs on battery power.

[0002]

2. Description of the Related Art Conventional batteries used in drive devices for electric vehicles include those having a large output density and those having a large energy density. The high output density means that the output current per unit weight is high. As a battery having a high output density, for example, a lead oxide battery is known. Further, a high energy density means that a large amount of electricity is stored per unit weight. As a battery having a high energy density, for example, a sodium-sulfur battery is known.

[0003]

However, a battery having a high output density such as a lead oxide battery has a drawback that the energy density is low. Therefore, the electric vehicle loaded with the lead oxide battery has a problem that the traveling distance is short.

On the other hand, a battery having a high energy density such as a sodium-sulfur battery has a drawback that the output density is low. Therefore, there is a problem that the electric vehicle loaded with the sodium-sulfur battery is inferior in acceleration, climbing, and the like.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a drive device for an electric vehicle which has the advantages of a battery having a high output density and a battery having a high energy density, and which can improve the traveling performance such as traveling distance, acceleration, and climbing. To provide.

[0006]

A drive device for an electric vehicle according to the present invention is made to achieve the above-mentioned object, and includes a first battery having a large output density and a second battery having a large energy density. The battery, the motor for rotating the drive wheel, the motor rotation speed detection means for detecting the rotation speed of the motor, and the first rotation speed when the rotation speed is high based on the rotation speed detected by the motor rotation speed detection means. And a controller that supplies electric power from the battery to the motor and supplies electric power from the second battery to the motor when the rotation speed is low.

Further, an engine generator which uses the engine as a power source to generate electric power, and a storage amount detection means for detecting the storage amount of the first and second batteries are additionally provided, and the storage amount is detected. The control unit may be provided with a function of charging the first or second battery having the smaller stored amount based on the stored amount detected by the means from the engine generator.

[0008]

The operation of the drive device according to claim 1 is as follows. The control unit supplies electric power of the first and second batteries to rotate the motor, and the motor rotates the drive wheels.
The rotation speed of the motor is output to the control unit by the motor rotation speed detection means. The control unit supplies power from the first battery when the rotation speed of the motor is high. Since the first battery has a large output density, a large current can be obtained, and as a result, it is possible to travel with excellent acceleration, climbing, and the like. Further, the control unit supplies power from the second battery when the rotation speed of the motor is low. Since the second battery has a high energy density, it can travel a long distance as a result of obtaining a constant current for a long time.

The operation of the drive device according to claim 2 is as follows. The engine generator uses the engine as a power source to generate electric power. The control unit uses this electric power to charge the first or second battery. At this time, the control unit selects and charges one of the first and second batteries having the smaller amount of stored electricity. Therefore, one of the first and second batteries will not be discharged first.

[0010]

1 is a block diagram showing an embodiment of a drive system for an electric vehicle according to the present invention. Hereinafter, description will be given with reference to this drawing.

The drive unit 10 includes a lead oxide battery 12 as a battery having a high output density, a sodium-sulfur battery 14 as a battery having a high energy density, and drive wheels 16.
And a motor 18 for rotating the motor 18, and an encoder 20 as a motor rotation speed detecting means for detecting the rotation speed N of the motor 18.
And when the rotation speed N is high based on the rotation speed N detected by the encoder 20, the lead oxide battery 12 moves to the motor 18
And a control unit 22 that supplies electric power from the sodium-sulfur battery 14 to the motor 18 when the rotational speed N is low.

Further, the engine generator 30 which uses the engine 30a as a power source to generate electric power, and the current sensor 34p as a storage amount detecting means for detecting the storage amounts Cp and Cn of the lead oxide battery 12 and the sodium-sulfur battery 14. , 34n are provided. Furthermore, based on the charged amounts Cp, Cn detected by the current sensors 34p, 34n, the charged amount Cp,
The controller 22a has a function of charging the lead oxide battery 12 or the sodium-sulfur battery 14 having a smaller Cn from the engine generator 30.

The control unit 22 comprises a controller 22a, a changeover switch 22b and a motor driver 22c. The controller 22a is, for example, a CP
It is composed of a U, a ROM, a RAM, an input / output interface circuit and the like, and various functions are realized by a computer program. In addition, the controller 22a is
An accelerator signal, a brake signal, a shift position signal (forward / reverse switching signal), etc. are input from a speed control system (not shown) to calculate a rotation direction of the motor 18, a torque command value, etc.
The result is output to the motor driver 22c as a control signal. The changeover switch 22b includes a relay contact 221 that connects the lead oxide battery 12 and the motor driver 22c, a relay contact 222 that connects the sodium-sulfur battery 14 and the motor driver 22c, the engine generator 30, and the lead oxide battery 12 or sodium. It is composed of a relay contact 223 connecting to the sulfur battery 14. Motor driver 22c
Is composed of, for example, a switching transistor circuit that selects energization for the winding U-phase, V-phase, and W-phase, and a PWM circuit that controls the energization amount with a pulse width.

The motor 18 is a DC three-phase brushless motor. The encoder 20 is a so-called rotary encoder that mechanically controls the rotation of the drive shaft of the motor 18.
It is detected electrically, magnetically or optically and converted into an electrical signal corresponding to the rotation speed.

The current sensors 34p and 34n are composed of, for example, a current detection coil and a microcomputer, and calculate the stored amounts Cp and Cn by integrating the current values.

The engine generator 30 comprises an engine 30a that uses gasoline as fuel, an AC generator 30b that generates AC power by the rotation of the engine 30a, and an AC / DC converter 30c that converts AC power to DC power. Has been done. Further, on the input side of the AC / DC converter 30c, a changeover switch 30e for switching the connection to the AC generator 30b or the commercial power source plug 30d is attached. Since the commercial power supply may be AC 100V, it can be easily charged at home without the need for a charging device.

As described above, the present embodiment is a drive device for an engine-battery hybrid electric vehicle.

FIG. 2 is a flow chart showing the operation of the drive unit 10. The required current Ireq in this drawing is
It is calculated as follows.

The voltage of the lead oxide battery 12 or the sodium sulfur battery 14 connected thereto is V, the current flowing to the motor driver 22c is I, the rotation speed of the motor 18 is N, and the motor 18 is
Of the motor driver 22c by η
When (N, T), the energy flow is as follows.
The rotation torque T is obtained from the rotation speed N and the current I.

[Battery power consumption P = V × I] → [Loss η (N, T) in the motor driver 22c] → [Motor 18
Loss k ₁ ] → [shaft output k ₂ × N × T]. As a result, the following equation is obtained.

K ₂ · N · T = k ₁ · η (N, T) · V · I

When K = k ₂ / k ₁ and the equation is arranged with respect to I,

I = (K · N · T) / (η (N, T) · V)

It becomes In addition to driving the motor 18, the current required for auxiliary devices (air conditioner, wiper, light, etc.) is Iac
Then, the required current Ireq is

Ireq = (K · N · T) / (η (N, T) · V) + Iacc

[0026] Here, when the torque command becomes a negative value during regenerative braking and the regenerative current exceeds Iacc,
Ireq has a negative value.

The control operation of the controller 22a will be described below with reference to FIGS.

First, the charged amounts Cn and Cp are calculated by the current sensors 34p and 34n (step 101). Then, the required current Ireq of the motor driver 22c is calculated (step 102). Then, it is judged whether Ireq ≧ 0 (step 103). If Ireq ≧ 0,
It is determined whether Ireq ≧ Inmax (step 10).
4). Inmax is the maximum output current of the sodium-sulfur battery 14. If Ireq ≧ Inmax, control is performed in the acceleration / high-speed traveling mode. That is, the relay contact 222 is opened to connect the sodium-sulfur battery 14 to the motor driver 22c.
(Step 105), the relay contact 221 is closed, and the lead oxide battery 12 is connected to the motor driver 22c (step 106). Then, it is determined whether or not Cn> Cp (step 107). If Cn> Cp, the relay contact 223 is closed to the lead oxide battery 12 side,
Connect the engine generator 30 to the lead oxide battery 12 (step 1
08), and returns to step 101. On the other hand, if Cn> Cp is not satisfied, the relay contact 223 is closed to the sodium-sulfur battery 14 side and the engine generator 30 is closed.
(Step 109) and the process returns to step 101.

In step 104, Ireq ≧ Inmax
If not, control is performed in the stop and low speed steady running mode. That is, the relay contact 222 is closed to connect the sodium-sulfur battery 14 to the motor driver 22c (step 110), and the relay contact 221 is opened to open the lead oxide battery 1
2 is disconnected from the motor driver 22c (step 11
1) The process proceeds to step 107.

If Ireq ≧ 0 is not satisfied in step 103, the regenerative braking mode is controlled. That is, the relay contact 223 is opened to disconnect the engine generator 30 (step 112), and it is determined whether or not Cn> Cp (step 113). If Cn> Cp, the relay contact 222 is opened to disconnect the sodium-sulfur battery 14 from the motor driver 22c (step 114), and the relay contact 221 is closed to connect the lead oxide battery 12 to the motor driver 22c (step 115). ). As a result, the regenerative energy is charged into the lead oxide battery 12, and step 10
Return to 1.

If Cn> Cp is not satisfied in step 113, it is determined whether or not Cn = 100% (step 116). If Cn = 100%, relay contact 22
2 is opened to disconnect the sodium-sulfur battery 14 from the motor driver 22c (step 117), and the relay contact 2
21 to open the lead oxide battery 12 to the motor driver 22c
(Step 118). As a result, the regenerative energy is released as heat energy by the motor driver 22c (step 119), and the process returns to step 101.

If Cn = 100% in step 116, the relay contact 222 is closed to connect the sodium-sulfur battery 14 to the motor driver 22c (step 1
20), the relay contact 221 is opened to disconnect the lead oxide battery 12 from the motor driver 22c (step 12).
1). Thereby, the sodium-sulfur battery 14 is charged with the regenerative energy, and the process returns to step 101.

The above is the control operation of the controller 22a, which will be described in more detail.

For example, on a road with many uphill slopes or a road with many starts and stops, Ireq ≧ Inmax (step 104), and the time for connecting the lead oxide battery 12 to the motor driver 22c (step 106) increases. . Therefore,
If left as it is, the stored amount Cp of the lead oxide battery 12 will be exhausted first even though the stored amount Cn of the sodium-sulfur battery 14 is sufficient. In such a case, the required output current cannot be obtained, which makes traveling difficult. Therefore, it is always determined whether or not Cn> Cp (steps 107 and 113), and the battery with the smaller stored amount is preferentially charged (steps 108 and 109).

Further, the regenerative energy is charged in the lead oxide battery 12 or the sodium-sulfur battery 14 to effectively use the energy (steps 115, 12).
0).

Next, an example of a method for determining the total weight (total capacity) of the lead oxide battery 12 and the sodium-sulfur battery 14 will be described with reference to FIGS. 1 and 2.

First, the respective target values of the power performance such as acceleration and climbing ability and the traveling distance by one charge are set. Then, the characteristic of the motor 18 is determined from the target value of the power performance, and the maximum current for driving the motor 18 is determined. On the other hand, the amount of electricity stored to satisfy the target value of the traveling distance is determined. The total weight of each of the lead oxide battery 12 and the sodium-sulfur battery 14 is determined so as to satisfy both of the maximum current and the charged amount.

[0038]

The drive device for an electric vehicle according to the first and second aspects has the following effects. By driving the motor with the first battery, which has a high output density when the rotation speed of the motor is high, it is possible to drive with excellent acceleration, climbing, etc., and when the rotation speed of the motor is low, the energy density is high. By driving the motor with a large second battery, it is possible to travel a long distance. Therefore, it is possible to provide a drive device for an electric vehicle having both unprecedented excellent power performance and long mileage.

The drive device for an electric vehicle according to claim 2 has the following effects. By selecting and charging the one with the smaller amount of electricity stored in the first or second battery, it is possible to prevent the amount of electricity stored in either the first or second battery from running out first. You can maximize the power performance and long mileage.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a drive device for an electric vehicle according to the present invention.

FIG. 2 is a flowchart showing the operation of an embodiment of the drive device for an electric vehicle according to the present invention.

[Explanation of symbols]

 10 Drive Device 12 Lead Oxide Battery (First Battery) 14 Sodium Sulfur Battery (Second Battery) 16 Drive Wheel 18 Motor 20 Encoder (Motor Rotation Speed Detection Means) 22 Control Unit 22a Controller 22b Changeover Switch 22c Motor Driver 30 Actuation Generator 30a Engine 34p, 34n Current sensor (storage amount detection means) Cp Storage amount of lead oxide battery Cn Storage amount of sodium-sulfur battery N Number of rotations of motor

Claims (2)

[Claims] 1. A first battery having a high output density, a second battery having a high energy density, a motor for rotating a drive wheel, a motor rotation speed detecting means for detecting the rotation speed of the motor, and the motor. When the rotation speed is high based on the rotation speed detected by the rotation speed detection means, power is supplied from the first battery to the motor, and when the rotation speed is low, power is supplied from the second battery to the motor. A drive unit for an electric vehicle, comprising: 2. An engine generator for generating electric power by using an engine as a power source, and a storage amount detecting means for detecting the storage amount of the first and second batteries, and the storage amount detection. The control unit is provided with a function of charging the first or second battery having the smaller amount of stored electricity from the engine generator based on the amount of stored electricity detected by the means. Item 2. A drive device for an electric vehicle according to Item 1.