JP3484881B2 - Motor control device for electric vehicle - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device for an electric vehicle, and more particularly to a motor control device for driving and controlling a motor of an electric vehicle such as an electric wheelchair.

[0002]

2. Description of the Related Art Conventionally, a motor control device for an electric vehicle, such as an electric wheelchair, which steers by the difference in rotation between left and right driving wheels,
Based on the input of the left access Le and right access Le left axle signal by the operation of the right accelerator signal, and a control unit for individually driving and controlling the left and right motors. The control unit changes the traveling direction of the electric vehicle according to each accelerator signal by causing a rotation difference between the left and right motors.

[0003] In addition, the left motor, attached <br/> is left rotational speed sensor, the right motor, right rotation speed sensor has been kicked <br/> with take. Then, the control unit calculates a left PWM (pulse width modulation) signal and a right PWM signal based on the left motor rotation speed signal and the right motor rotation speed signal. Control unit outputs these signals to the motor drive circuits to drive the left motor and right motor <br/> over data.

FIG. 5 is a flow chart showing an example of the calculation processing of the PWM signal. Taking the motor control on the left side as an example, the control unit first converts the left accelerator signal into the left target rotation speed (step S21). Next, the left motor rotation speed signal is compared with the left target rotation speed, the left target rotation speed is subjected to feedback calculation based on the actual rotation speed of the left motor (step S22), and converted into PWM (step S23). The same applies to the motor control on the right side.

The conversion of the left accelerator signal into the left target rotational speed and the conversion of the right accelerator signal into the right target rotational speed are shown in FIG.
As shown in, the left target rotational speed is simply proportional to the left accelerator signal and the right target rotational speed is simply proportional to the right accelerator signal only by adjusting the ratio to the maximum value.

[0006]

However, in the above-mentioned conventional example, when the load increases due to traveling uphill or the like, the duty of the PWM signal is reduced to 1 by the rotation speed feedback control.
If the load is so heavy that it does not reach the target speed even when it reaches 00% (directly connected to the battery), even if the accelerator signal changes, P
There has been a problem that the duty of the WM signal remains fixed at 100% and steering cannot be performed properly.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a motor control device for an electric vehicle capable of improving the disadvantages of the conventional example, and more particularly, improving the steering feeling while maximizing the performance of the motor. To that end.

[0008]

Therefore, in the present invention, a control unit for controlling the power supply to the left and right motors for driving the electric vehicle by a predetermined control signal, and a left and right motor unit for detecting the number of revolutions of each motor. A means for providing a control signal to each motor based on the target rotation speed according to the left and right accelerator signals and the rotation speed of each motor output from the left and right rotation speed sensors Is equipped with. In addition, the control unit is equipped with left and right motor current detection units that detect the motor current of each motor, and the control unit calculates the maximum rotation speed of each motor based on the current value output from the motor current detection unit. Target rotation speed calculation means for calculating the target rotation speed of each motor according to the left and right accelerator signals based on the maximum rotation speed of the left and right motors calculated by the maximum rotation speed calculation means It is equipped with means.

The target rotation speed calculation means is an accelerator.
One of the left and right target speeds according to the signal is the maximum speed
If it exceeds, set the maximum speed of one to the target speed
The first speed setting function to
A second rotation speed setting that sets the rotation speed according to the ratio of cell signals
It has a fixed function. Or, the target rotation speed calculation means,
Both the left and right target speeds according to the accelerator signal are the highest
When the number of turns is exceeded, it is based on the ratio of the left and right accelerator signals.
And set the maximum speed of one to the target speed of one
Speed setting function and other target speed
With the 4th rotation speed setting function that sets the rotation speed according to the ratio of
Is equipped with.

In the present invention, the maximum rotation speed calculation means calculates the maximum rotation speed according to the load during traveling based on the motor current of each motor, and the target rotation speed calculation means calculates the maximum rotation speed according to this load. Since the target rotation speed of each motor is calculated according to the ratio of the left and right accelerator signals based on the number of rotations, this target rotation speed is a rotation speed that can be reliably driven by the current load. Drive.

The present invention aims to achieve the above-mentioned object by each of these means.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a motor control device for an electric vehicle according to the present invention. The motor control device for an electric vehicle includes left and right motors 5 and 8 for driving the electric vehicle.
Control unit 3 for controlling power supply to the motors by a predetermined control signal, left and right rotation speed sensors 6 and 9 for detecting rotation speeds of the motors 5 and 8, and motor currents of the motors 5 and 8 are detected. The left and right motor current detectors 7 and 10 are provided.

The control unit 3 calculates the maximum rotation speed of each of the motors 5 and 8 based on the current values output from the motor current detection units 7 and 10, and the maximum rotation speed calculation unit 3A. Left and right motors 5 calculated by 3A
The target rotation speed calculation means 3B calculates the target rotation speed for each motor according to the left and right accelerator signals on the basis of the respective maximum rotation speeds of 8.

Further, the control unit 3 is provided with means for outputting a control signal to each motor based on the target rotation speed corresponding to the left and right accelerator signals and the rotation speed of each motor output from the left and right rotation speed sensors. ing.

This will be described in detail.

FIG. 2 is a diagram showing the characteristics when a constant voltage is applied to the DC motor, with the horizontal axis representing torque. The DC motor has a characteristic that the torque and the input current are proportional to each other and the torque and the rotation speed are inversely proportional to each other. The characteristic curve shown in FIG. 2 is called the drooping characteristic of the DC motor.
Since the torque and the input current are linearly proportional, the torque of the motor can be calculated from the current value.

Further, the rotational speed and the torque are in inverse proportion to each other and show a linear drooping characteristic. Therefore, if the battery voltage does not change, the PWM signal duty is 100%.
The maximum rotation speed in the state of (directly connected to the battery) can be estimated from the motor current. Therefore, in this embodiment, the left motor current detection unit 7 and the right motor current detection unit 8 are provided to calculate the left target rotation speed and the right target rotation speed.

First, the left motor current and the right motor current are applied to the characteristics peculiar to the motor, and the left motor maximum rotation speed and the right motor maximum rotation speed are calculated. Then, the maximum rotation speed is compared with the left accelerator signal x A (conventional left target rotation speed) and the right accelerator signal x A (conventional right target rotation speed) to set the target rotation speed with the maximum rotation speed as the upper limit. To do.

Since the maximum rotation speed is calculated based on the motor current, it is possible to determine the maximum capacity of the motor according to the load during traveling, and further, when steering left and right, the maximum rotation speed is set as the upper limit and the left and right targets are set. Since the rotation speed is set, it is possible to reliably maintain the rotation difference between the left and right drive wheels.

[Embodiment] FIG. 3 is a circuit diagram showing a configuration of a motor control device. In the embodiment shown in FIG. 3, a control microcomputer 3 that outputs a motor drive control signal (PWM signal) according to each accelerator signal input from each accelerator 1 and 2, and a PWM output from this control microcomputer 3 The motor drive circuit 4 controls the electric power from the battery 11 supplied to each motor according to the signal.

The motor drive circuit 4 controls the drive voltage by switching the transistor at high speed in accordance with the PWM signal and changing the on / off time ratio of the voltage.
In the example shown in FIG. 3, a field effect transistor (FET) is used.
Is used.

Rotation speed sensors 6 and 9 and current detection circuits 7 and 10 are connected to the motors 5 and 8, respectively.
The rotation speed sensors 6 and 9 input left and right motor rotation signals to the control microcomputer 3 , and the current detection circuits 7 and 10 measure the motor current and output the motor current signal to the control microcomputer 3.
To enter.

FIG. 4 is a flow chart showing an example of processing steps of motor control by the configuration shown in FIG.

The control microcomputer 3 calculates the left motor maximum rotation speed based on the current value detected by the left motor current detection circuit 7 (step S1). Next, the control microcomputer 3 calculates the right motor maximum rotation speed based on the current value detected by the right motor current detection circuit (step S2).

The maximum left motor rotation speed is the left accelerator signal x
If it is larger than A (step S3), the right motor maximum rotation speed is further compared with the left accelerator signal xA (step S4). When each accelerator signal does not reach each maximum rotation speed, the left target rotation speed is set to the left accelerator signal ×
A is set (step S5), and the right target rotation speed is set to right accelerator signal × A (step S6).

In step S4, the right accelerator signal x
When A exceeds the maximum right motor rotation speed, that is, when the value of the right accelerator signal x A exceeds the maximum rotation speed due to the current load, the right target rotation speed is set to the right motor maximum rotation speed. Set (step S9, first rotation speed setting function). Further, the left target rotational speed is set based on the left accelerator signal according to the ratio between the right accelerator signal and the right motor maximum rotational speed (step S10, second rotational speed setting function).

In step S3, the left accelerator signal x
If A exceeds the maximum rotation speed of the left motor, it is confirmed whether the right accelerator signal xA exceeds the maximum rotation speed of the right motor (step S7). When both the left accelerator signal xA and the right accelerator signal xA exceed the respective maximum rotation speeds, one of the maximum rotation speeds is selected according to the ratio of the left and right accelerator signals. In the example shown in FIG. 4, when the maximum rotation speed of the right motor is set to the maximum rotation speed of the right motor, the target rotation speed of the left motor based on the left accelerator signal based on the ratio between the accelerator signal on the right side and the maximum rotation speed. And the actual maximum left motor speed are compared (step S8).

When the left motor maximum rotation speed is higher than the left target rotation speed, the right motor maximum rotation speed is used as a reference, while when the left motor maximum rotation speed is lower than the left target rotation speed, the left motor Based on the maximum rotation speed (step S
9, S11, third speed setting function). This step S
9. One of the maximum rotational speeds, which is the reference in S11, is set as the target rotational speed, and the other rotational speed is set according to the ratio of one accelerator signal to the maximum rotational speed based on the other accelerator signal (step S10). , S12, fourth speed setting function). With the third and fourth rotation speed setting functions, specifically, the maximum rotation speed on the side where the accelerator signal is large is set to the one target rotation speed, and the other rotation speed is set as follows.
The rotation speed is set according to the ratio of the accelerator signal. As a result, it is possible to set the rotational speed according to the left and right accelerator ratios within a rotational speed range that does not exceed the maximum rotational speed.
Further, the target rotation speed may be determined on the basis of one of the maximum rotation speeds having a large accelerator signal.

On the other hand, if the right motor maximum rotation speed is larger than the accelerator signal x A at step S7, the left target rotation speed is set to the left motor maximum rotation speed (step S7).
11. First rotation speed setting function), the right target rotation speed is set according to the input of the right accelerator signal based on the ratio between the left motor maximum rotation speed and the left accelerator signal (step S12, second). Speed setting function).

As a result, the target rotational speed higher than the maximum rotational speed is not calculated, and the ratio of the left and right target rotational speeds is kept the same as the ratio of the left and right accelerator signals.
Even if the load increases, the steering ability will not be lost.
Therefore, the steering ability is not lost even if the load increases due to traveling uphill or the like. Further, the maximum torque can be generated within the range where the steering ability is not lost. Therefore, it is possible to improve the steering feeling while providing the maximum capability.

[0032]

Since the present invention is constructed and functions as described above, according to this, the maximum rotation speed calculation means calculates the maximum rotation speed according to the load during traveling based on the motor current of each motor. Since the target rotation speed calculation means calculates the target rotation speed of each motor according to the ratio of the left and right accelerator signals with reference to the maximum rotation speed according to this load, the control unit sets the target rotation speed to the current value. It is possible to drive the motor according to the accelerator signal because it is a rotation speed that can be reliably driven by the load, and since the maximum rotation speed is the maximum rotation speed under the current load, the motor capacity is maximized. Therefore, it is possible to provide a motor control device for an electrically-powered vehicle, which has not been heretofore excellent, in which the ability of the motor can be maximized and the steering feeling can be dramatically improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a graph showing the characteristics of a DC motor.

FIG. 3 is a circuit diagram showing a configuration of an exemplary embodiment of the present invention.

FIG. 4 is a flowchart showing motor drive control by the configuration shown in FIG.

FIG. 5 is a flowchart showing an example of conventional motor drive control.

6 is a flowchart showing an example of processing for converting the accelerator signal shown in FIG. 5 into a target rotation speed.

[Explanation of symbols]

1 left accelerator 2 right accelerator 3 Control unit (control microcomputer) 4 Motor drive circuit 5 Left motor 6 Left rotation speed sensor 7 Left current detection section (left motor current detection circuit) 8 right motor 9 Right rotation speed sensor 10 Right current detection unit (right motor current detection circuit)

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B60L 15/00-15/38

Claims (2)

(57) [Claims] 1.Electric power is supplied to the left and right motors that drive the electric vehicle.
A control unit for controlling power supply by a predetermined control signal,
The left and right rotation speeds that detect the rotation speed of each motor
In addition to The control unit controls the target speed according to the left and right accelerator signals.
And the rotation of each motor output from the left and right rotation speed sensors.
An electric signal that outputs a control signal to each of the motors based on the number of turns.
In a motor control device for a moving vehicle, The controller detects the motor current of each motor.
Left and right motor current detectors are also installed, The control unit controls the electric current output from the motor current detection unit.
The maximum number of rotations that calculates the maximum rotation speed of each motor based on the flow value
Calculated by the rotation speed calculation means and this maximum rotation speed calculation means
Based on the maximum rotation speed of the left and right motors
Calculate the target speed for each motor according to the accelerator signal of
And a target rotation speed calculation unit that The target rotation speed calculation means is configured to adjust the left and right according to the accelerator signal.
When one of the target speeds exceeds the above maximum speed
First, set the maximum speed of the one to the target speed.
Speed setting function and the other target speed
A second rotation speed setting machine that sets the rotation speed according to the signal ratio
Characterized by having NohRudenMotor control equipment for moving vehicles
Place 2.Electric power is supplied to the left and right motors that drive the electric vehicle.
A control unit for controlling power supply by a predetermined control signal,
The left and right rotation speeds that detect the rotation speed of each motor
In addition to The control unit controls the target speed according to the left and right accelerator signals.
And the rotation of each motor output from the left and right rotation speed sensors.
An electric signal that outputs a control signal to each of the motors based on the number of turns.
In a motor control device for a moving vehicle, The controller detects the motor current of each motor.
Left and right motor current detectors are also installed, The control unit controls the electric current output from the motor current detection unit.
Each mode based on the flow rate Maximum number of rotations
Calculated by the rotation speed calculation means and this maximum rotation speed calculation means
Based on the maximum rotation speed of the left and right motors
Calculate the target speed for each motor according to the accelerator signal of
And a target rotation speed calculation unit that The target rotation speed calculation means is configured to adjust the left and right according to the accelerator signal.
If both of the target speeds of
Based on the ratio of the left and right accelerator signals, determine the maximum speed of one
Third rotation speed setting function for setting one of the target rotation speeds
And the other target speed depending on the ratio of the accelerator signal.
Having a fourth rotation speed setting function for setting the rotation speed
Characterized byRudenMotor control device for moving vehicle.