JP3475799B2 - Electric vehicle traveling control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an electric vehicle traveling control device for controlling a DC motor at a constant speed to drive a vehicle body at a low speed.

[0002]

2. Description of the Related Art Recently, electric vehicles have been widely used as wheelchairs for the elderly and disabled people. In this type of electric vehicle, a DC motor is used as a drive source.
Since the vehicle runs at a constant speed, it has a feedback control system for the DC motor, and this feedback control system is configured to calculate the control amount by an integral operation in order to further smooth the driving feeling. For this reason, it is customary to increase the voltage or current applied to the electric motor as the load increases so as to maintain a constant speed. However, in Japanese Patent Laid-Open No. 8-107602, the current is increased due to overload or the like. When the current exceeds the specified value, the power supply is stopped, and when the current reaches the specified value, the power is supplied again to prevent the DC motor from being overloaded.

[0003]

However, in an electric vehicle using such a DC motor, the overload is suddenly released in a state where the current exceeds a specified value due to the overload and the energization is stopped. In this case, an excessive current or voltage is applied, and the number of rotations of the DC motor that generates a large torque sharply increases, so that the electric vehicle may move unexpectedly depending on conditions.

The present invention has been made to solve the above problems, and an object thereof is to provide a feedback control system for a DC motor with a current even if the current of the motor increases due to overload or the like. To provide an electric vehicle that can be safely driven without using an external device such as a braking device, because the DC motor can be limited to a specified value and the DC motor does not suddenly rotate even when the load is suddenly released. It is in.

[0005]

The present invention proposed to achieve the above object has the following constitution. That is, in claim 1, in the electric vehicle traveling control device having the feedback control system for controlling the rotation of the DC motor by starting or braking the DC motor according to the accelerator operation, the speed detecting means for detecting the rotation speed of the DC motor. When,
A command speed generation means for outputting a command speed according to an accelerator operation, and an integrated calculation value obtained by integrating the deviation between the detected speed by the speed detection means and the command speed as a control amount, and a command calculated based on the control amount The speed control means for outputting the voltage to the electric motor control system, the current detection means for detecting the armature current of the DC motor, and the current determination means,
The current determination means is a detection speed detected by the speed detection means,
In response to the armature current detected by the current detection means, the operating state of the electric motor is determined. When the armature current exceeds a predetermined level, the speed control means stops the integral operation, and the control amount at that time is further reduced. In addition to increasing, decreasing or fixing, the command speed generated by the command speed generating means is also increased, decreased or fixed.

According to a second aspect of the present invention, in the first aspect, the current determining means stops the integrating operation by the speed control means when the armature current exceeds a predetermined level when the DC motor is in a starting state, The amount of control at that time is reduced,
In addition, the command speed output from the speed command means is also reduced. According to claim 3, in claim 1, when the DC motor is in a braking state, when the armature current exceeds a predetermined level, the current determination means stops the integrating operation by the speed control means, and The control amount at this time is fixed or increased, and the command speed output from the command speed means is also fixed or increased.

According to claim 4, in any one of claims 1 to 3, when the armature current exceeds a predetermined level,
Both the control amount that is reduced or increased by the speed control means and the control amount of the command speed that is reduced or increased by the command speed generation means change according to the level of the armature current. Further, according to claim 5, in claims 1 to 4, the current determination means compares the armature current with the first reference value and the second reference value to determine whether they are large or small. In accordance with the discrimination results by the first and second comparators and the detected speed detected by the speed detecting means, a predetermined logical judgment is made, and the result is used as an overcurrent control signal, and the speed controlling means is provided. And the output to the command speed generation means.

[0008]

In the electric vehicle using the DC motor as the drive source, when a large load is suddenly applied during constant speed running, the feedback control system of the DC motor increases the armature current to increase the torque. If the load is suddenly removed with, the rotation speed of the DC motor will be abnormally increased, resulting in a rapid increase in speed.

On the other hand, when the accelerator is loosened or turned off, the DC motor is braked by dynamic braking, and at this time, the armature current flows in the opposite direction. In the present invention, in view of such characteristics of the DC motor, by determining the level change of the armature current flowing in the DC motor and the direction thereof,
When the DC motor is in the start-up state and is overloaded, not only is damage prevented by overcurrent prevented, but even if the load is suddenly removed, it is possible to suppress a sudden increase in the rotational speed of the DC motor, and to reduce the braking When in the state, it is possible to prevent damage due to a rapid increase in armature current.

Therefore, according to the present invention, when a load is applied while the electric vehicle is running and the armature current increases, the current determining means causes the speed control means and the command speed generating means to operate in accordance with the level of the armature current. A current control signal is output, whereby the speed control means stops the operation of integrating the deviation between the detected speed and the command speed to generate a command voltage based on the reduced control amount, and at the same time. The command speed generation means also reduces the command speed.

Further, when the motor is in a braking state and the armature current increases, an overcurrent control signal according to the level of the armature current is output from the current determination means to the speed control means and the command speed generation means, As a result, the speed control means stops the operation of integrating the deviation between the detected speed and the command speed to fix or increase the control amount, and at the same time, the command speed generating means fixes or increases the command speed.

On the other hand, even if the load fluctuates while the electric vehicle is running, if the change is such that the armature current does not exceed the predetermined level (the overcurrent level in the embodiment described later), the current determination means outputs it. The overcurrent control signal that indicates normal control is given. Therefore, the normal feedback control using the integration amount is performed, and the speed control means generates a command voltage to be applied to the DC motor based on the control amount obtained by integrating the deviation between the detected speed and the command speed, and the command speed generation means , The motor is driven to rotate so that the commanded speed matches the set speed.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram showing the basic configuration of the electric vehicle traveling control device of the present invention. The rotation speed of the DC motor M is detected by the speed detector 7, the detected rotation speed is compared with the command speed by the speed controller 3, and the command voltage is applied to the voltage controller based on the control amount obtained by integrating the deviation. 5 to form a feedback control system for controlling the rotation speed of the DC motor M.

1 is a set speed ω ″ in accordance with the accelerator operation.
Is a speed setter serving as speed setting means for outputting the command speed generator 2 serving as command speed generating means.
U) and memory (ROM, RAM) and the like, which has a storage and calculation function, and has a command speed ω based on a set speed ω ″ and an overcurrent control signal Soc from the current determiner 6 which constitutes the current judging means ′ Is output.

The speed controller 3 constitutes a speed control means and calculates a control amount thereof based on the command speed ω ', the detected speed ω of the DC motor M, and the overcurrent control signal Soc output from the current determiner 6. , Generates a command voltage V'to the DC motor M. The voltage controller 5 forming the voltage control means has a reference voltage Vin.
A voltage Vm corresponding to the command voltage V'is applied to the DC motor M by PWM control, and the speed detector 7 forming speed detecting means is a tacho generator, an encoder and an F / V converter, or the like. It is configured so that the rotation speed ωm of the DC motor M is converted into a detection speed ω and is input to the speed controller 3.

The current detector 4 forming the current detecting means takes out the armature current Im of the DC motor M with the shunt resistor 8, amplifies it to obtain the detected current I, and outputs it to the current determiner 6, The determiner 6 determines the overcurrent control signal Soc based on the determination result of the detection speed ω, the detection current I and the reference current.
Is being output. FIG. 2 shows an example of the current determination means.

The current judging means 6 is a first comparator CO.
MP1 and the second comparator COMP2 are included. The first comparator COMP1 compares the absolute value of the detection current I with the reference current Iref1, and the second comparator COMP2
The absolute value of the detection current I is compared with the reference current Iref2, and the combination of the comparison results S1 and S2 and the positive and negative determination results of the detection speed ω is used as shown in FIG. It is configured to perform the logical determination and output the overcurrent control signal Soc.

Here, the overcurrent control signal Soc is usually
Fixed, decrease (small change rate), and decrease (large change rate) are specified. In the normal case, the command speed generator 2 gradually changes the command speed ω ′ so as to match the set speed ω ″. The speed controller 3 changes the integral calculation value obtained by integrating the deviation between the detected speed ω and the command speed ω ′ (in the case of PI control, the calculated value obtained by multiplying the deviation between the detected speed and the command speed by several times). Is added) and the command voltage V'is based on the control amount.
To occur.

When fixed, the command speed generator 2
Is fixed without changing the command speed ω ′, and the speed controller 3
Stops the operation of integrating the deviation between the detected speed ω and the commanded speed ω ′, and the control amount at that time (in the case of PI control,
The command voltage V'is generated based on the calculated value obtained by multiplying the deviation between the detected speed and the command speed by several times. on the other hand,
In the case of a decrease (small change rate), the command speed generator 2 decreases the command speed ω ′ at a predetermined change rate ωΔ1, and the speed controller 3 determines the deviation between the detected speed ω and the command speed ω ′. The operation of integrating is stopped, and a value further reduced by a predetermined change rate IintΔ1 from the control amount at that time is used as a control amount, and a command voltage V ′ based on the control amount is generated.

In the case of a decrease (large change rate), the command speed generator 2 decreases the command signal ω'at a predetermined change rate ωΔ2 larger than ωΔ1, and the speed controller 3 detects the detected speed. The operation of integrating the deviation between ω and the command speed ω ′ is stopped, and the control amount is a value obtained by further reducing the control amount at that time by a predetermined change rate IintΔ2 larger than the change rate IintΔ1. A command voltage V'based on the above is generated.

In the current judging device 6, when the electric vehicle moves forward and the detected speed ω is positive, the table (a) of FIG. 3 is shown. When the detected speed ω is negative, The logical judgment of Table (b) of 3 is made. That is, depending on whether the armature current I is positive or negative, the operating state of the electric motor M, that is, the determination result of driving or braking and the determination results S1 and S2 of the first and second comparators COMP1 and COMP2 are combined. , The overcurrent control signal Soc is defined.

FIG. 4 is a time chart showing a change in each signal when a load is applied while the electric vehicle is running at a constant speed, and when the armature current I in the table (a) of FIG. 3 is positive. 7 shows an example in which the logical judgment in FIG. (A) is the load,
(B) shows the armature current I, (c) shows the set speed ω ″ and the speed command ω ′, and (d) shows the control amount Iint to be integrated by the speed controller 3 to generate the command voltage V ′. There is.

When a large load is applied to the electric vehicle, the motor is in a starting state at this time, so that the armature current I rapidly increases in the positive direction as shown in FIG. 4 (b). When the armature current I exceeds the overcurrent level Iref1, the current determiner 6 decreases (rate of change: small) overcurrent control signal So.
c is output, and the armature current is further overcurrent danger level Ire
When f2 is exceeded, the current determiner 6 outputs the overcurrent control signal Soc that decreases (change rate: large).

When the speed controller 3 receives a decrease (rate of change: small) overcurrent control signal Soc, the speed controller 3 stops the integration operation, and the control amount at that time is set to a preset IintΔ.
1, the command speed generator 2 decreases the command speed ω ′ at the rate of change ω′Δ1 (see section B in FIG. 4). Also, the command speed generator 2 decreases (rate of change: large)
When the overcurrent control signal Soc that satisfies the above condition is received, the integration operation is stopped, and the integration calculation amount at that time is set to I
The command speed generator 2 decreases the command speed ω ′ at a rate of change ω′Δ2 (see section A in FIG. 4). Here, IintΔ1 <IintΔ2 and ω′Δ1 <ω′Δ2.

The armature current I is the overcurrent level Ire.
During the period of not exceeding f1, the command speed ω ′ is the set speed ω ″.
, The control amount Iint and the command speed ω ′ are also increased ((c) of FIG. 4,
(See arrow in (d)). As a result, in the present invention, when the load is applied and the armature current I increases and exceeds the overcurrent level Iref1 and the overcurrent danger level Iref2, the control amount Iint and the command speed ω ′ are changed respectively. The rates Iint Δ1 and ω′Δ1 or Iin
Since it decreases at tΔ2 and ω′Δ2, both the command speed ω ′ and the command voltage V ′ are suppressed even when the load is rapidly removed. Therefore, it is possible to prevent the situation in which the DC motor M rapidly increases its rotation speed and increases its speed.
It enables safe driving according to the accelerator operation.

FIG. 5 is a time chart showing changes in each signal when the electric vehicle is braked. Table (a) of FIG.
Shows an example in which the logic judgment is executed when the armature current is negative. (A) is the set speed ω ″, (b) is the armature current I, (c) is the set speed ω ″ and the command speed ω ′, and (d) is the integral calculation in the speed controller 3 to calculate the command voltage V ′. The control amount Iint for generating is shown.

When the accelerator is loosened, the set speed ω ″ gradually decreases as shown in (a), and the electric motor M is dynamically braked accordingly. Therefore, the armature current I is as shown in (b). When the armature current I exceeds the overcurrent level Iref1, the current determiner 6 becomes a fixed overcurrent control signal Soc.
When the speed controller 3 receives this fixed overcurrent control signal Soc, the speed controller 3 stops the integration operation and fixes the control amount at that time. Therefore, the speed controller 3 controls at that time. A command voltage V'corresponding to the quantity is generated. At this time, the command speed generator 2 also fixes the command speed ω ′ to the value at that time (see section C in FIG. 5). During the period in which the armature current I does not exceed the overcurrent level Iref1, the command speed ω ′ changes to match the set speed ω ″, the integral operation is started, and the control amount also increases (in FIG. 5). (See arrows in (c) and (d)).

As a result, in the present invention, the electric motor M is in the braking state and the armature current I is overcurrent level Iref1.
When the speed exceeds the limit, further increases in the command speed ω'and the command voltage V'are suppressed, so that damage due to overcurrent is prevented in advance, and the rotation speed of the electric motor M is also suppressed, so that the vehicle travels safely. it can. In this example, the overcurrent danger level Iref2, which is the armature current I higher than the overcurrent level Iref1, is not determined, but as in the case of FIG. 4, the overcurrent danger level Iref2 (indicated by a broken line). May be provided and the determination process may be performed.

FIG. 6 is a time chart showing another control example when the electric vehicle is braked. In the table (a) shown in FIG. 7, there is shown an example in which the logic judgment is executed when the armature current I is negative. The difference from FIG. 4 is that when the armature current exceeds the overcurrent level Iref1, the current determiner 6 outputs an increasing overcurrent control signal Soc, and the speed controller 3
When the increasing overcurrent control signal Soc is received, the integration operation is stopped, and the control amount at that time is further increased by adding a predetermined value. At this time, the command speed generator 2 also
The command speed ω ′ is increased by a predetermined amount (above, FIG.
Section D).

As a result, in the present invention, the electric motor M is in the braking state, and the armature current I is overcurrent level Iref1.
When it exceeds, the command speed ω'and the command voltage V'increase,
Overcurrent during braking is suppressed and damage due to overcurrent is prevented. Note that the armature current is the overcurrent danger level Ir.
ef2 (shown by a broken line) may be provided so that the judgment can be made when the level is exceeded. Further, during a period in which the armature current I does not exceed the overcurrent level Iref1,
The command speed ω ′ changes in a direction to match the set speed ω ″, the integration operation is started, and the control amount Iint also increases (see arrows in (c) and (d) of FIG. 6).

[0031]

The present invention has the following effects. That is, according to claims 1, 2 and 3, when the armature current exceeds a predetermined level when the DC motor is in the activated state, the command speed output from the command speed generating means in response to the operation of the accelerator and the speed control. Since the command voltage output from the means becomes small, the armature current can be suppressed. Further, even when the overload is released, an excessive voltage is not applied to the electric motor, so that the rotational speed of the electric motor is not sharply increased, and the vehicle can travel safely without using braking means.

Further, even when the DC motor is in the braking state and the armature current exceeds a predetermined level, the overcurrent is suppressed, so that damage due to the overcurrent during braking can be prevented. In particular, according to claim 2, when the DC motor is in a starting state and the armature current exceeds a predetermined level, the integral operation by the speed control means is stopped to reduce the control amount at that time, Moreover, since the command speed output from the speed command means is also reduced, damage due to overcurrent can be prevented in advance, and even when the load is suddenly removed, the DC motor can be stabilized without rapidly increasing its rotation speed. Can run.

According to the third aspect, even when the armature current of the DC motor exceeds a predetermined level when the DC motor is in the dynamic braking state, damage due to overcurrent can be prevented. Therefore, the overcurrent when the inertial load is decelerated can be limited to a specified value. According to the fourth aspect, when the armature current exceeds a predetermined level, the command speed increase / decrease amount and the command voltage increase / decrease amount are changed according to the armature current. Therefore, fine control is possible.

According to the present invention, there is provided a current discriminating means having a simple structure capable of outputting the overcurrent control signal by inputting the detected speed of the DC motor and the armature current and making a simple logical decision. it can.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of an electric vehicle traveling control device of the present invention.

FIG. 2 is a diagram showing a schematic configuration of a current determination means.

FIG. 3 is a diagram showing a logic judgment table in a current judgment means.

FIG. 4 is a time chart showing a basic operation when the DC motor is overloaded in a driving state.

FIG. 5 is a time chart showing a basic operation when the DC motor is in a braking state.

FIG. 6 is a time chart showing a basic operation when the DC motor is in a braking state.

FIG. 7 is a diagram showing another logical judgment table in the current judging means.

[Explanation of symbols]

1 Speed setting device (speed setting means) 2 Command speed generator (command speed generating means) 3 Speed controller (speed control means) 4 Current detector (current detection means) 5 Voltage controller (voltage control means) 6 Current judging device (current judging means) 7 Speed detector (speed detection means) ω'command speed ω ″ set speed Soc overcurrent control signal V'command voltage

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-5-30602 (JP, A) JP-A-59-216487 (JP, A) JP-A-2-70205 (JP, A) Actual development Sho-60- 69504 (JP, U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B60L 15/20 H02P 5/06

Claims (5)

(57) [Claims] 1. An electric vehicle traveling control device having a feedback control system for controlling the rotation of a DC motor by starting or braking the DC motor according to an accelerator operation, and speed detection means for detecting a rotation speed of the DC motor. , Including a command speed generating means for outputting a command speed according to the accelerator operation, and an integral calculation value obtained by integrating the deviation between the speed detected by the speed detecting means and the command speed as a control amount, and calculating based on the control amount The speed control means for outputting the command voltage, the current detection means for detecting the armature current of the DC motor, and the current determination means, wherein the current determination means is the detection speed detected by the speed detection means and the current detection means. When the armature current exceeds a predetermined level by receiving the armature current detected by the means, the operating state of the electric motor is determined. Minute operation is stopped, and the control amount at that time is further increased, decreased or fixed, and the command speed output from the command speed generating means is also increased, decreased or fixed. Control device. 2. The current determining means according to claim 1, wherein the current determining means is:
When the armature current exceeds a predetermined level, the integral operation by the speed control means is stopped, the control amount at that time is decreased, and the command speed output from the speed command means is decreased. Travel control device. 3. The current judging means according to claim 1, wherein the current judging means is provided when the DC motor is in a braking state.
When the armature current exceeds a predetermined level, the integral operation by the speed control means is stopped so that the control amount at that time is fixed or increased and the command speed output from the speed command means is fixed or increased. Electric vehicle running control device. 4. The control amount according to any one of claims 1 to 3, when the armature current exceeds a predetermined level, the control amount reduced or increased by the speed control means and the instruction reduced or increased by the speed command means. An electric vehicle traveling control device in which both the speed and the speed are changed according to the level of the armature current. 5. The current judging means according to claim 1, further comprising first and second comparators for comparing the magnitude of the armature current with the first reference value and the second reference value. A predetermined logical judgment is made on the basis of the discrimination results by the first and second comparators and the detected speed detected by the speed detecting means, and the result is used as an overcurrent control signal, the speed controlling means and the command speed. An electric vehicle traveling control device configured to output to a generating means.