JPH0223045Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a control device for an electric vehicle, and in particular, the control of an electric vehicle using a chopper circuit in which the conduction rate changes based on a command value corresponding to the amount of accelerator operation and an armature current. Concerning improvements to equipment.

Generally, a resistance switching circuit or a chopper circuit is known as a circuit for controlling the running speed of an electric vehicle. Recently, chopper circuits have been mainly put into practical use because resistance switching circuits have larger losses.

FIG. 1 is a circuit diagram of a conventional electric vehicle control device using a chopper circuit. A conventional control device is configured by connecting a DC motor (hereinafter referred to as a motor) 2 and a chopper circuit 3 in series to a storage battery 1, which is an example of a DC power source. As the chopper circuit 3, for example, a thyristor chopper circuit is used. Then, the accelerator command value circuit 4 generates a speed command signal for controlling the traveling speed of the electric vehicle according to the amount of depression or operation of the accelerator 5, and supplies it to the chopper control circuit 6. Chotsupa control circuit 6
includes, for example, a gate signal generation circuit, and provides the chopper circuit 3 with a pulse signal for changing the conductivity in correlation with the speed command signal. That is, the chopper control circuit 6 controls the chopper circuit 3 so that when the accelerator 5 is depressed lightly, the conduction rate is decreased, and when the accelerator 5 is depressed deeply, the conduction rate is increased.

By the way, the circuit that uses the chopper circuit 3 to control the speed of the motor 2 has a problem in that the closer the conduction rate is to the maximum value, the greater the loss due to heat generation due to voltage drop in the thyristor included in the chopper circuit 3. including.

Therefore, conventionally, in order to reduce the loss when the chopper circuit 3 has a large conduction rate, a bypass circuit 7 and a maximum conduction rate detection circuit 8 for controlling the bypass circuit 7 have been provided. The bypass circuit 7 is configured by connecting a contactor 9a included in the electromagnetic relay 9 to the chopper circuit 3 in parallel. The coil 9y of the electromagnetic relay 9 is energized by the output of the maximum conductivity detection circuit 8. Then, the maximum conduction rate detection circuit 8 detects that the accelerator command value circuit 4 derives a speed command signal for making the chopper circuit 3 reach the maximum conduction rate,
The relay coil 9y is energized to close the contact 9a, thereby bypassing the chopper circuit 3 to the contact 9a. As a result, the motor 2 is connected to the storage battery 1.
The maximum current is supplied from the motor to rotate at maximum speed.

By the way, since the conventional control device shown in FIG. 1 controls the conduction rate of the chopper circuit 3 only according to the amount of depression of the accelerator 5, the accelerator 5 is suddenly depressed when the electric vehicle starts. However, there was a problem in that a sudden armature current was supplied regardless of the acceleration state of the electric vehicle at that time, causing a sudden start and a dangerous situation.

FIG. 2 is a circuit diagram of a control device for an electric vehicle, which was developed to solve the problem shown in FIG. 1 and is the background of this invention. The control device that forms the background of this invention is such that a current detection circuit 10 is provided in the current path supplied to the motor 2, and the chopper control circuit 6a performs a chopper control circuit 6a based on the output of the accelerator command value circuit 4 and the output of the current detection circuit 10. The conduction rate of the circuit 3 is controlled. That is,
The chopper control circuit 6a increases the conduction rate in stages if the armature current is small even if the accelerator 5 is depressed deeply, and increases the conduction rate in stages when the armature current becomes too large regardless of the amount of accelerator depression. Works to limit.

However, although the circuit shown in FIG. 2 has good characteristics when accelerating an electric vehicle, it has the following problems. In other words, when an electric vehicle is running uphill, a large amount of torque is required, so the driver depresses the accelerator deeply, but the current flow rate of the electric vehicle automatically decreases and the current value decreases to the accelerator. It is controlled to a nearly constant value depending on the opening degree. For this reason, even when a large torque is temporarily required when traveling uphill, sufficient torque cannot be obtained.

Therefore, an object of this invention is to provide a control device for an electric vehicle that can prevent sudden starts when the electric vehicle is accelerating and can obtain sufficient torque when traveling uphill.

To summarize, this invention controls the conduction rate of the chopper means based on a command value corresponding to the amount of accelerator operation and an armature current, and when the amount of accelerator depression is equal to or greater than a certain value, When the conductivity of the chopper means is less than or equal to a predetermined first value, it is assumed that the load is greater than a certain value, and the bypass circuit of the chopper means is activated.

Specific embodiments of this invention will be described below with reference to the drawings.

FIG. 3 is a circuit diagram of a control device for an electric vehicle according to an embodiment of this invention. In the configuration, a storage battery (DC power supply) 1 includes a motor 2 and a current detection circuit 1.
0 and chopper circuit 3 are connected in series. A bypass circuit 7 including a contact 9a, which is an example of a switch, is connected in parallel to the chopper circuit 3.

The accelerator command value circuit 4 derives a speed command signal in proportion to the amount of depression of the accelerator 5 (that is, the accelerator opening degree), and supplies it to the chopper control circuit 6a and the accelerator specified value detection circuit 11, which is an example of the first detection means. . The armature current value output from the current detection circuit 10 is input to the chopper control circuit 6a. The chopper control circuit 6a provides a signal for controlling the conduction rate to the chopper circuit 3 and the conduction rate specified value detection circuit 12, which is an example of the second detection means, based on the speed command signal and the armature current. The conduction rate specified value detection circuit 12 includes a D/A converter 12a and a comparator 1.
2b, a comparator 12c, and an OR gate 12d, and when the conduction rate is less than or equal to a predetermined first value, or when the conduction rate is greater than or equal to a second value larger than the first value, the high A level signal is derived and applied to the AND circuit 13. The accelerator specified value detection circuit 11 detects when the speed command signal is deeper than the predetermined value of the accelerator, that is, when the accelerator 5 is depressed to a predetermined depth or more, and outputs a high level signal to the AND circuit 13. give to AND circuit 13 is accelerator specified value detection circuit 1
1 and when there is an output from the conduction rate specified value detection circuit 12, the coil 9y included in the electromagnetic relay 9 is energized to close its contact 9a. That is, the AND circuit 13 calculates the logical product of the output of the accelerator specified value detection circuit 11 and the output of the duty ratio specified value detection circuit 12, and thereby functions as a drive circuit that energizes the relay coil 9y.

FIG. 4 is a diagram schematically showing the relationship between the output of the conduction rate specified value detection circuit 12 and the conduction rate to explain the operation of FIG. 3.

Next, the specific operation of this embodiment will be explained with reference to FIGS. 3 and 4.

First, we will describe the operation when driving on a normal flat road. When accelerating an electric car,
Accelerator 5 is gradually depressed. Accordingly,
The accelerator command value circuit 4 derives a speed command signal proportional to the amount of depression of the accelerator 5 (accelerator opening degree) and supplies it to the chopper control circuit 6a and the accelerator specified value detection circuit 11. Chip control circuit 6a
provides the chopper circuit 3 with a signal that gradually increases the conduction rate based on the output of the current detection circuit 10 and the speed command signal. Therefore, the chopper circuit 3 gradually increases the conduction rate and gradually increases the current supplied to the motor 2. By this,
The electric vehicle accelerates as the rotational speed of the motor 2 increases.

Then, when the electric vehicle enters the constant speed driving range, the chopper control circuit 6a controls the conduction rate of the chopper circuit 3 according to the amount of depression of the accelerator 5.

On the other hand, if you want to drive an electric car at high speed,
The driver depresses the accelerator 5 to its deepest position.
At this time, the accelerator specified value detection circuit 11 detects that the accelerator 5 is depressed to a predetermined depth or more, and provides a high level signal to the AND circuit 13. The chopper control circuit 6a also controls the accelerator 5.
Based on the fact that the armature is depressed to a depth greater than a predetermined value, a control signal is sent to the chopper circuit 3 so that the conductivity becomes a second value x2 (for example, x2 = 80%) in order to flow the corresponding armature current. give. At this time, D/
A converter 12a converts the output pulse of chopper control circuit 6a into an analog signal and supplies it to comparators 12b and 12c. The comparator 12c detects that the conductivity has become equal to or higher than the second value x2, derives a high level signal, and supplies it to the AND circuit 13 via an OR gate. The AND circuit 13 has the output of the accelerator specified value detection circuit 11 and the OR gate 1
In response to the presence of the output 2d, the coil 9y is energized. In response, the contact 9a is closed, so that the chopper circuit 3 is bypassed by the contact 9a. In this state, the maximum current from the storage battery 1 is supplied to the motor 2, so the motor 2 is driven to rotate at a high speed.

In this way, when the conduction rate exceeds a large value, by short-circuiting the chopper circuit 3 at the contact point 9a,
Since the armature current is bypassed to the contact 9a side and the chopper circuit 3 is not activated, there is an advantage that the loss due to the chopper circuit 3 can be reduced when the conduction rate is large.

Next, we will describe the operation during uphill running, which is a feature of this invention. In this case, even though the accelerator 5 is depressed deeply, the electric vehicle is going uphill, so the load increases and the rotational speed of the motor 2 decreases, so the armature current tends to increase. At this time, the chopper control circuit 6a operates to reduce the conduction rate of the chopper circuit 3, and the armature current is kept approximately constant. Normally, the relationship between the amount of accelerator depression and armature current is determined based on flat ground driving. Further, in such a control method, an effect of increasing torque due to an increase in current due to a decrease in speed cannot be expected, so that an electric vehicle tends to run out of torque when traveling uphill. Therefore, comparator 12b
detects that the conductivity has become less than the first value x1 (for example, x1 = 20%), derives a high level signal, and sends it to the AND circuit 13 via the OR gate 12d.
give to At this time, a signal is input to the AND circuit 13 so that the accelerator specified value detection circuit 11 detects that the accelerator 5 is depressed by a predetermined value or more. Therefore, AND circuit 13 energizes relay coil 9y to close contact 9a. In this way, according to this embodiment, the accelerator 5
Even if the pedal stroke is more than a certain level and the conduction rate is the first value (i.e., under heavy load), by activating the bypass circuit 7 and supplying the maximum current to the motor 2, it is possible to climb uphill. Works to obtain the necessary torque.

As described above, according to this invention, when the accelerator is depressed more than a predetermined value and the conduction rate is less than the first value, the circuit for bypassing the chopper circuit is activated, so that the electricity is Sufficient torque can be obtained when the car climbs a slope, and even when driving on a flat road, smooth acceleration can be obtained, and the driving feeling can be improved.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a conventional electric vehicle control device. FIG. 2 is a circuit diagram of a control device that solves the problems shown in FIG. 1 and is the background of this invention. FIG. 3 is a circuit diagram of a control device for an electric vehicle according to an embodiment of this invention. FIG. 4 is a circuit diagram for explaining the operation of FIG. 3. In the figure, 1 is a storage battery, 2 is a motor, 3 is a chopper circuit, 4 is an accelerator command value circuit, 6, 6a
is a chopper control circuit, 7 is a bypass circuit, 9 is an electromagnetic relay, and 11 is an accelerator specified value detection circuit (first
(detection means), 12 is a conduction rate specified value detection circuit (second detection means), and 13 is an AND circuit (driving means).
shows.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A DC power supply, a DC motor for driving an electric vehicle, a chopper means for supplying the DC power supply voltage intermittently to the DC motor, and a DC power source for reducing overflow current of the DC motor. a current detecting means for detecting a current, a speed command signal generating means for generating a speed command signal corresponding to an amount of operation of an accelerator, and an overflow current detected by the current detecting means being small and not generated by the speed command signal generating means. If the detected speed command signal indicates that the amount of depression of the accelerator is large, the conduction rate is increased stepwise, and if the detected overflow current becomes larger than a predetermined value, regardless of the speed command signal. chopper control means that generates a signal for limiting the flow rate and applies it to the chopper means; the speed command signal generating means generates a speed command signal in response to depression of the accelerator deeper than a predetermined value; at least a second detection means for detecting that the conductivity of the chopper means is equal to or lower than a predetermined first value; bypass means including a switch that is turned on or off; and drive means that turns on the switch included in the bypass means in response to the presence of the first detection means output and the second detection means output. , electric vehicle control device. (2) The second detection means includes means for detecting that the conductivity of the chopper means is equal to or higher than a second value, which is larger than the first value. A control device for an electric vehicle as described in Section 1.