JP2000324605A - Brake control device for dc electric motor vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a brake off feeling when a transfer is made from a regenerating brake to a plugging brake or power running control. SOLUTION: This device, comprising a DC motor 7 for running a vehicle, forward/reverse contactors 8, 9 switching a direction of the field current of the DC motor 7 to a forward or reverse direction, chopper element 11 chopper controlling the current of a field coil 7b and an armature 7a of the DC motor 7, and a regenerating contactor contact 5 connected between a DC power source and the armature 7a, is constituted to perform a regenerating brake or a plugging brake. Here, a control part 3, turning on the regenerating contactor contact 5 in a condition chopper operating or turning on the chopper element 11 in a transfer from the regenerating brake to the plugging brake or power running control to perform the plugging brake or the power running control by chopper control of the chopper element 11 after turning of the regenerating contactor contact 5, is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking control device for a DC electric vehicle driven by a DC electric motor, and more particularly to a braking control device capable of performing regenerative control.

[0002]

2. Description of the Related Art In general, a braking control device for a DC electric vehicle such as a battery forklift using regenerative braking is widely used. A battery, a contact of a regenerative contactor, and a switching element (usually a transistor) are connected in series to a DC motor used in a DC electric vehicle. During forward or reverse power running, the regenerative contactor is closed (hereinafter referred to as ON), and the switching element is switched at a predetermined duty (chopper ratio) to control the vehicle drive current of the DC motor. When the forward / reverse direction is switched during power running, when the rotation speed or current value of the DC motor is equal to or higher than a predetermined value, regenerative braking is performed, and the braking energy of the DC electric vehicle is converted into generated power and recovered as battery charging energy. I do. That is, the regenerative contactor is opened (hereinafter, referred to as “off”), and the direction of the field current of the DC motor is switched to the direction opposite to the direction in which the DC motor acts as a motor, so that the DC motor acts as a generator. Recovery of energy (regenerative energy) causes regenerative braking.

When the speed of the DC electric vehicle decreases and the rotational speed or current value of the DC motor decreases below a predetermined value, the regenerative current of the DC motor cannot be maintained, and the regenerative braking force decreases. Therefore, the regeneration is usually terminated at this point, and the mode is switched to the plugging braking. That is, at the same time as turning on the contact of the regenerative contactor, the switching of the switching element is stopped.After that, it is confirmed that the contact of the regenerative contactor is securely turned on, or after waiting for a sufficient time to elapse, The chopper operation is started to shift to plugging braking. The reason for controlling the start timing of the chopper operation of the switching element when switching to the plugging braking in this way is that if the contact of the regenerative contactor is turned on while the switching element is on, a large inrush current flows, and the contact of the regenerative contactor is welded. Problem of dripping and wearing,
This is to avoid the problem that the braking torque of the plugging braking suddenly increases due to the inrush current and a braking shock occurs in the DC electric vehicle.

However, since the switching element is turned off during the time until the contact of the regenerative contactor is securely turned on, during this time, the DC electric vehicle loses braking force, and a so-called braking loss feeling is generated. A problem that the ring deteriorates occurs. Conventionally, many techniques have been proposed in order to solve the problem of the deterioration of the braking feeling when shifting from regenerative braking to plugging braking.

As the prior art, for example, Japanese Patent Laid-Open No.
An electric motor control device disclosed in Japanese Patent Application Laid-Open No. 82368 is known, and FIG. 11 is a circuit diagram of the control device described in the same application. In the figure, an electric motor DM has an armature DMa and a field winding DMf, and is driven using a battery B as a power supply. The control unit 51 controls the conduction of the chopper transistor TM and the regeneration transistor TG,
The operation of the respective contacts mf, mr, mg is controlled via the coils MF, MR, MG of the electromagnetic switch. Further, the control unit 51 controls the voltage applied to the motor DM by controlling the conduction period of the transistor TM to control the voltage applied to the motor DM.
During the regenerative braking, the transistor TG is turned on to supply an exciting current through the resistor RG to pre-excit the field winding DMf. Also, the motor D
In the forward mode of M, the coils MF and MG are energized and the coil MR is deenergized. In the reverse mode, the coils MR and MG are energized and the coil MF is deenergized. , The coil MF or the coil MR is energized and the coil MG is deenergized. Coil MF, MR
When the coil MG is energized, the contacts mf and mr operate in the opposite direction to the state shown in FIG.
g is turned on. The primary side of the contact mg (battery B
Side) and a secondary side (opposite side of the battery B) are connected to an operation detection unit 52, respectively. The operation detection unit 52 is configured to detect a voltage difference between the primary side and the secondary side due to opening and closing of the contact mg. , And outputs a detection signal of the ON or OFF state of the contact mg to the control unit 51 based on the voltage difference. Further, a current detector CS is connected between the armature DMa and the contact mg,
The armature current of the motor DM is detected and input to the control unit 51. Furthermore, flywheel diodes DF1, D
F2 is connected between the battery B and both ends of the field winding DMf, and the regenerative diode DG is connected to the contact m
g and the emitter terminal of the transistor TM.

In such a control device, the control unit 51 determines whether or not regenerative braking is possible based on the current value detected by the current detector CS during regenerative braking. In order to shift to braking, the coil MG is energized, and at the same time, a built-in timer is started and waits until a predetermined time has elapsed. During this time, the transistor TM is kept on in order to continue the regeneration chopper. Then, when a certain time has elapsed, the transistor TM is turned off. Thereafter, the detection signal of the operation detecting section 52 is monitored to wait for the contact mg to be turned on. When the contact mg is turned on, the chopper operation by the transistor TM is performed. To start plugging braking. Thereby, a certain period of time (the minimum value of the delay time required from the time when the coil MG is energized to the time when the contact mg is actually turned on after the coil MG is energized until the contact mg is turned on). (Set in consideration of the minimum closing delay time), the chopper operation by the transistor TM is continued. Then, immediately after the contact mg is turned on, the chopper operation by the transistor TM is resumed and the operation shifts to the plugging braking. Therefore, compared to the conventional chopper operation control, the transistor during the transition from the regenerative braking to the plugging braking is changed. The stop time of the chopper operation by the TM is reduced. Therefore, the period during which the braking torque becomes zero can be shortened, and the braking shock when switching to plugging braking can be reduced accordingly.

Another prior art is disclosed in Japanese Unexamined Patent Publication No.
No. 46707 discloses a switching element that is turned on only for a short time when shifting from regenerative braking to plugging braking.
The terminal voltage on the DC motor side of the regenerative contactor (corresponding to the contact mg) is detected, and it is determined whether or not the regenerative contact is completely turned on based on the terminal voltage. A drive control device for a DC motor in which chopper control of a switching element is started to apply plugging braking to the DC motor is disclosed.

[0008]

However, the above-described conventional techniques have the following problems. In the prior art disclosed in Japanese Patent Application Laid-Open No. 8-182368, a switching element (transistor T
Although the stop time of the chopper operation due to M) is shortened, the chopper stop time is still between the time when the coil MG is energized and the chopper operation is stopped after the minimum closing delay time and the contact mg is turned on. Existing. Also,
In the prior art disclosed in Japanese Patent Application Laid-Open No. 7-46707, the point in time when the contacts of the regenerative contacts are completely turned on can be detected without a time lag. The chopper control stop time of the switching element still exists. Therefore, in the above-described conventional technology, a feeling of missing braking still remains,
There is a problem that the braking feeling is not good. In addition, this problem occurs not only when shifting from regenerative braking to plugging braking but also when shifting to power running control.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a DC electric vehicle capable of improving a braking feeling by eliminating a feeling of braking loss when shifting from regenerative braking to plugging braking or power running control. It is intended to provide a braking control device.

[0010]

In order to achieve the above object, a first invention of a braking control apparatus for a DC electric vehicle according to the present invention comprises a DC motor for driving the vehicle, A forward contactor and a reverse contactor for switching the direction of the field current of the motor to the forward or reverse direction, a chopper element for chopper controlling the motor current flowing through the field coil and the armature of the DC motor, and a DC power supply and the armature. A regenerative contactor contact connected thereto, switching between a forward contactor or a reverse contactor, controlling ON / OFF of a regenerative contactor contact, and performing chopper control of a chopper element to perform regenerative braking or plugging braking by a DC motor. When switching from regenerative braking to plugging braking or powering control in an electric vehicle braking control device, The path element to turn on the regeneration contactor contacts while being chopper operation or on, has a configuration provided with a control unit for plugging braking or motoring control by chopper control of the chopper element after regeneration contactor contacts is turned on.

According to the first aspect of the present invention, the control section continues the chopper operation or the on state of the chopper element from the time when the contact point of the regenerative contactor is output until the contact is turned on. Occurs.
Thereby, when shifting from the regenerative braking to the plugging braking or the power running control, the feeling of missing the braking as in the related art is eliminated,
The braking feeling can be improved. Further, after the regenerative contactor contact is turned on, the plugging braking or the powering control is continuously performed, so that there is no braking shock when shifting to the plugging braking or the powering control.

According to a second aspect of the present invention, based on the first aspect, contact-on detecting means for detecting that a regenerative contactor contact has been turned on is provided, and the control unit includes a chopper when the contact-on detecting means detects a contact on. The element is turned off, and thereafter, a transition is made to plugging braking or power running control.

According to the second aspect of the present invention, the chopper element is turned off when the regenerative contactor contact is turned on, so that inrush current can be prevented from flowing through the chopper element, and the chopper element can be protected.

According to a third aspect based on the first aspect, one of a current detector for detecting a current value of an armature of the DC motor and a motor speed detector for detecting a rotation speed of the DC motor is additionally provided. The control unit turns on the regenerative contactor contact in a state where the chopper element is operated by the chopper, when the detected current value of the current detector is equal to or less than a predetermined set value, or when the detected rotation speed of the motor rotation speed detector is The configuration is performed when the value is equal to or less than a predetermined set value.

According to the third invention, when the motor current value is small or the motor speed is small, the regenerative contactor contact is turned on while the chopper operation of the chopper element is continued, so that the rush current when the contact is turned on can be reduced. Welding and damage can be prevented. Furthermore, since the braking torque can be smoothly controlled at the time of transition from regenerative braking to plugging braking or power running control, the braking feeling is very good.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment will be described below in detail with reference to the drawings, taking a DC motor drive control device of a battery forklift as an example.

FIG. 1 is a circuit example of a braking control device for a DC electric vehicle according to the present invention. Here, a DC motor control circuit for traveling of a battery forklift will be described as an example. The positive terminal of the battery 16 is connected to one end of the armature 7a of the DC motor 7 via the regenerative contactor contact 5 and the current detector 6, and the other end of the armature 7a is connected to the forward contactor 8
Parallel circuit with the reverse contactor 9 and the chopper element 1
1 is connected to the negative terminal of the battery 16.
In the parallel circuit of the forward contactor 8 and the reverse contactor 9, output common terminals 8 c and 9 c are connected to both ends of a field coil 7 b of the DC motor 7. Also,
One of the output a-contact (so-called normally-off) terminals 8a and 9a and the output b-contact (so-called normally-on) terminals 8b and 9b of the forward contactor 8 and the reverse contactor 9 is connected to the armature. The other terminal (the same, the b-contact terminal) is connected to the other end of the chopper element 1a.
1 (composed of a large current transistor, FET, etc.)
It is connected to the. In addition, a pre-excitation circuit 4 having a resistor and a transistor and a plugging diode 12 are connected in parallel to a series circuit of the regenerative contactor contact 5, the current detector 6, and the armature 7a. Furthermore, a flywheel diode 1 is included in the series circuit of these parallel circuits and the parallel circuit of the forward contactor 8 and the reverse contactor 9.
3, a regenerative diode 14 is connected in parallel to a series circuit from the current detector 6 to the armature 7a, the forward contactor 8 (or the reverse contactor 9) and the chopper element 11. A motor rotation speed detector 15 for detecting the rotation speed of the DC motor 7 is provided on the rotation shaft of the armature 7a.
Is attached.

The current detection signal of the current detector 6 and the rotation speed signal of the motor rotation speed detector 15 are inputted to the control unit 3, and each control signal from the control unit 3 is supplied to the preliminary excitation circuit 4, the chopper element 11, It is output to the excitation coil 5R of the contactor, the excitation coil 8R of the forward contactor 8, and the excitation coil 9R of the reverse contactor 9, respectively. The accelerator circuit 1 detects the depression amount of the accelerator pedal, that is, the accelerator operation amount by using a potentiometer or the like, and outputs an accelerator operation amount signal to the controller 3. The forward / reverse switch 2 is mounted on an operation lever for switching forward, neutral and reverse of the battery forklift, and outputs a switching signal corresponding to forward, neutral and reverse to the controller 3.

The control unit 3 includes an arithmetic processing unit such as a microcomputer and a numerical processing unit, an input interface circuit for detecting signals from the detectors, and a command signal to the exciting coil and the chopper element 11 of each contactor. It is composed of an output interface circuit. And
The control unit 3 includes a current detector 6 and a motor speed detector 15
Based on the respective detection signals, the switching signal of the forward / reverse switch 2 and the accelerator operation amount signal of the accelerator circuit 1, predetermined processing described later is performed, and the pre-excitation circuit 4, the chopper element 1
1 and the exciting coils 5R, 8 of the contactors 5, 8, 9
By outputting control commands to R and 9R, the currents of the field coil 7b and the armature 7a of the DC motor 7 are controlled. Thus, power running control, plugging braking, and regenerative control during normal running are performed.

At the time of power running control, with the regenerative contactor contact 5 turned on and the excitation command to the pre-excitation circuit 4 turned off,
The forward contactor 8 or the reverse contactor 9 is turned on in response to the switching of the forward / reverse switch 2 between forward and reverse, and the chopper is set so that the current value detected by the current detector 6 becomes the target drive current corresponding to the accelerator operation amount. Element 11
At a predetermined duty ratio. Thereby, the regenerative contactor contact 5, the armature 7a, the forward contactor 8 (or the reverse contactor 9), the field coil 7
b, a drive current of a predetermined magnitude flows through the armature 7a via the reverse contactor 9 (or the forward contactor 8) and the chopper element 11 sequentially.

Next, when the forward / reverse switch 2 is switched from forward to reverse while the DC motor 7 is rotating in the forward direction by the power running control, for example, the control unit 3 turns off the regenerative contactor contact 5 and at the same time, the forward contactor 8 And switch the reverse contactor 9 in the reverse direction. After that, an excitation command is output to the pre-excitation circuit 4 for a predetermined time and turned on, and the chopper element 11 is switched at a predetermined conduction rate. Then, Figure 1
, The battery 16, the pre-excitation circuit 4,
A field current flows through the path of the field coil 7b and the chopper element 11. At this time, since the direction of rotation of the DC motor 7 is opposite to the direction of the field current, the DC motor 7 changes from an electric motor to a generator. When the DC motor 7 is in the power generation state, when the chopper element 11 is off,
As shown by the dashed line in FIG. 1, the generated current flows through the armature 7a, the reverse contactor 9, the field coil 7b, the forward contactor 8, the flywheel diode 13, the battery 16, and the regenerative diode 14, whereby The rotational energy of the DC motor 7 is charged in the battery 16 as a regenerative current. At this time, a braking torque is generated in the DC motor 7, and regenerative braking is applied. When the chopper element 11 is turned on, the armature 7a, the reverse contactor 9, the field coil 7
b, the generated current (regenerative current) circulates in the path of the forward contactor 8, the chopper element 11, and the regenerative diode 14,
Regenerative braking is applied.

Next, the operation at the time of plugging braking will be described. For example, when the forward / reverse switch 2 is switched from forward to reverse while the DC motor 7 is rotating in the forward direction, the control unit 3 turns on the regenerative contactor contact 5. At the same time, the forward contactor 8 and the reverse contactor 9 are switched in the reverse direction. Thereafter, when the chopper element 11 is switched at a predetermined duty ratio, when the chopper element 11 is on, the field current of the field coil 7b in the direction opposite to the rotation direction of the DC motor 7 is supplied from the battery 16 to the regenerative contactor. The current flows through the contact 5, the armature 7a, the reverse contactor 9, the field coil 7b, the forward contactor 8, and the chopper element 11. When the chopper element 11 is off, the field current generated by the armature 7a reverses. Since the current flows through the contactor 9, the field coil 7b, the forward contactor 8, the flywheel diode 13, and the regenerative contactor contact 5, the DC motor 7 changes from an electric motor to a generator. As a result, as shown by the dotted line in FIG.
Since the plugging current flows through the contact 2 and the regenerative contactor contact 5, the DC motor 7 is subjected to plugging braking. At this time, the plugging braking torque is controlled by controlling the switching duty of the chopper element 11 to control the magnitude of the field current.

Further, the control unit 3 performs the following processing when shifting from the regenerative braking to the plugging braking or the power running control. FIG. 3 is an example of a control flowchart illustrating the control method according to the first embodiment, and FIG. 4 is a time chart thereof. In addition, each processing step number is represented by adding S. First, during the regenerative control, the control unit 3 inputs a rotation speed signal from the motor rotation speed detector 15 and a current signal from the current detector 6 (S1). Then, it is determined whether the regenerative control is to be terminated based on the magnitudes of the rotation speed signal and the current signal, and the process is repeated from S1 until it is determined that the regenerative control is terminated (S2). That is, it is checked whether the rotation speed signal is equal to or less than a predetermined value or the current signal is equal to or less than a predetermined value. Next, an ON command for the regenerative contactor contact 5 is output to the exciting coil 5R (S3).
At the same time, the counting of the built-in end timer is started (S4). Next, the chopper element 11 is turned on (S
5) A current value flowing through the DC motor 7 is read by the current detector 6 (S6), and a current change amount for each predetermined time is obtained by a formula "current change amount = current read value-previous read value" (S7). Then, the obtained current change amount is equal to a predetermined set value I.
It is checked whether it is greater than 1 (S8), and the set value I1
In the following cases, it is next checked whether or not the count value of the end timer is larger than a predetermined set value T1 (S9). Set value T1
In the following cases, the flow returns to S5 to repeat the above processing, and when it is larger than the set value T1, the processing shifts to the plugging control processing (S11). If the current change amount is larger than the set value I1 in S8, the chopper element 11 is turned off (S10), and thereafter, the process proceeds to the plugging control process in S11 (S1).
1).

According to the above method, the regenerative contactor contact 5 is turned off during the regenerative control, and the control unit 3 monitors the regenerative current value of the DC motor 7 by gradually increasing the duty ratio of the chopper element 11. . When the motor current value is reduced to a predetermined value or less in a state where the duty ratio is 100%, or when the motor rotation speed is reduced to a predetermined value or less, the duty ratio of the chopper element 11 is changed to 100% in order to shift to plugging control.
That is, in the on state, an on command for the regenerative contactor contact 5 is output, and the system waits for the regenerative contactor contact 5 to turn on. Thereafter, when it is detected that the motor current value increases at a steep rise of a predetermined value or more, the regenerative contactor contact 5
Is determined to be on, the chopper element 11 is turned off for a predetermined time to suppress the inrush current, and thereafter, the operation shifts to the plugging control. Alternatively, before a steep rise of the motor current value, if a predetermined time has elapsed after the ON command of the regenerative contactor contact 5 is output, it is determined that the contact has been turned on even without a sudden increase in the motor current, and the plugging control is performed. Transition. If the motor speed is sufficiently low due to the regenerative braking or the plugging braking at this time, the process shifts to the power running control within a short time thereafter. Therefore, the chopper element 11 is turned on without turning off the regenerative contactor contact 5 from the off state to the fully on state, so that the regenerative current can flow during this period to generate the regenerative braking torque. Therefore, there is no braking loss, and the braking feeling can be improved. Also, after the regenerative contactor contact turns on,
Since the plugging braking or the powering control is performed continuously, there is no braking shock when shifting to the plugging braking or the powering control. In the present embodiment, the current detector 6 is used as an example of the contact-on detecting means for detecting whether the regenerative contactor contact 5 is turned on, but the present invention is not limited to the current detector 6.

Next, another control method according to the first embodiment will be described with reference to FIG. Steps having the same processing contents as those in FIG. 3 are described with the same step numbers. If it is determined in S2 that the regeneration is completed, it is next checked whether the motor speed is equal to or less than a predetermined set value N2 (S21).
If not, the motor current value is further reduced to a predetermined set value I.
It is checked whether it is 2 or less (S22). When the motor speed is equal to or smaller than the set value N2 in S21, or when the motor current is equal to or smaller than the set value I2 in S22, the chopper operation of the chopper element 11 during the regenerative control is continued (S23), and when larger than the set value N2. If it is larger than the set value I2, the chopper operation of the chopper element 11 is stopped (S24). Then, after S23 and S24, an ON command for the regenerative contactor contact 5 is output by the processing of S3 to S10 to wait for the regenerative contactor contact 5 to be turned on. When the contact is turned on, the process shifts to plugging control in S11.

According to this method, when shifting from the regenerative control to the plugging control, the operation of the chopper element 11 is determined based on the motor speed or the magnitude of the motor current value. That is, when the motor speed or the motor current value is small, the inrush current is small even if the regenerative contactor contact 5 is turned on, so that the contact can be protected. When it is large, the inrush current is monitored with the regenerative contactor contact 5 kept on When a sharp current rise is detected, the regenerative contactor contact 5
Is turned off for a predetermined time, so that the contact can be protected. At this time,
Since the transition from the regenerative braking to the plugging braking or the power running control is performed while the chopper control of the chopper element 11 is performed, the braking torque changes smoothly, and the braking shock can be eliminated.

Next, a second embodiment will be described. The basic hardware configuration in the present embodiment is the same as in FIG.
A partial configuration inside the control unit 3 is different as shown in FIG. 6, a current signal from the current detector 6 is input to an arithmetic processing unit (hereinafter, referred to as a CPU 31), and is also input to one input (-terminal in FIG. 6) of the comparison circuit 32. Also, the comparison command value I from the CPU 31
r is input to the other input (also + terminal) of the comparison circuit 32, and the output signal of the comparison circuit 32 is input to the interrupt port of the CPU 31. Also, the CPU 31
As in the first embodiment, the chopper command is transmitted to the chopper element 11.
Output to

The operation in such a configuration will be described with reference to the flow chart shown in FIG. 3 and the time chart of FIG. The CPU 31 determines to shift from the regenerative control to the plugging control (S1, 2), outputs an ON command for the regenerative contactor contact 5 while the chopper element 11 is ON (S3, 5), and outputs the motor from the current detector 6 at a predetermined cycle. The current value is read (S6), and the comparison command value Ir is set to a value larger than the read current value by a predetermined value α.
The set comparison command value Ir is output to the comparison circuit 32. Thereby, the comparison command value Ir changes along the decreasing curve of the motor current value as shown in FIG. Next, when the regenerative contactor contact 5 is turned on and a steep rise of the motor current occurs, the processing time for updating the comparison command value Ir has a slight time delay, so that the motor current value is smaller than the comparison command value Ir. (Corresponding to S8), the output signal of the comparison circuit 32 is inverted, and an interrupt request IN is sent to the CPU 31.
T is input. When receiving the interrupt request INT, the CPU 31 turns off the chopper element 11 for a predetermined time (corresponding to S10), and thereafter shifts to plugging control (S11). At this time, if the motor speed is sufficiently low due to the regenerative braking or the plugging braking, the process shifts to the power running control within a short time thereafter.

According to the present embodiment, when the control unit 3 shifts from regenerative braking to plugging braking or power running control, the control unit 3 outputs a value larger than the read value of the motor current by the predetermined value α to the comparison circuit 32 as the comparison command value Ir. And the comparison circuit 3
It is possible to wait while performing other processing until the interrupt request INT from 2 is input. Thereby, the calculation processing load on the CPU 31 of the control unit 3 is reduced. Then, even when the interrupt request INT is input, the chopper operation of the chopper element 11 can be continued while the regenerative contactor contact 5 is turned from off to on, so that a feeling of braking loss can be eliminated and chopper control of the chopper element 11 is performed. While shifting from regenerative braking to plugging braking or power running control, the braking torque changes smoothly and braking shock can be eliminated. In the present embodiment, as described above, the contact-on detection means includes the current detector 6 and the comparison circuit 32.
And

Next, a third embodiment will be described. Although the basic hardware configuration in the present embodiment is the same as that of FIG. 1, a part of the configuration inside the control unit 3 is different as shown in FIG. 8, the current signal from the current detector 6 is input to the CPU 31 and also to one input (-terminal in FIG. 8) of the comparison circuit 32. Also, C
The comparison command value Ir from the PU 31 is input to the other input (also the + terminal) of the comparison circuit 32, and the output signal of the comparison circuit 32 is output to one selection terminal I of the signal selector 34.
It has been input to N1. The CPU 31 outputs a chopper command CCH to the chopper element 11 to the other selection terminal IN2 of the signal selector 34, and outputs a selection command CSE to the selection command terminal SEL. Output OUT of signal selector 34
Is input to the chopper command terminal of the chopper element 11.

FIG. 9 shows an example of a control flow chart of the control section 3 in the present embodiment, and the operation will be described based on the figure. Steps having the same processing contents as those in FIG. 3 are denoted by the same reference numerals, and description thereof is omitted. If it is determined that the regeneration is completed (S1
To S2), an ON command for the regenerative contactor contact 5 is output (S3), and the end timer is started (S4).
Thereafter, the value of the current flowing through the DC motor 7 is read by the current detector 6 (S31), and the comparison command value Ir is calculated by a formula “comparison command value Ir = current reading value + predetermined value α” (where α> 0) at predetermined time intervals. ) (S32). That is, the comparison command value Ir is set to a value larger than the read current value by the predetermined value α. Next, the selection command C is sent to the signal selector 34.
The SE is output to select an output signal from the comparison circuit 32 and set it as a command signal to the chopper element 11 (S33). At this time, since the motor current value is smaller than the comparison command value Ir while the regenerative contactor contact 5 is not turned on, the comparison circuit 3
2 is high, and the chopper element 11 is turned on. As a result, the braking torque by the regenerative control is continuously generated. Thereafter, it is checked whether the count value of the end timer is equal to or greater than a predetermined set value T1 (S3).
4) If the value is not equal to or greater than the set value T1, the process returns to S31 and repeats the process. If the value is equal to or greater than the set value T1, a command for selecting a chopper command CCH from the CPU 31 to the chopper element 11 is output to the signal selector 34. , This chopper command C
CH is set as a command signal to the chopper element 11 (S35).
The set value T1 is set to the maximum operation time during which the regenerative contactor contact 5 is turned on. If the regenerative contactor contact 5 is turned on during the loop processing between S31 and S34, the motor current value rises rapidly and the comparison circuit 32
, The output of the comparison circuit 32 is inverted to a low level, and this low level signal directly turns off the chopper element 11. This prevents a sudden increase in the motor current value. Then, in the above S35,
The command signal to the chopper element 11 is switched to the chopper command CCH from the CPU 31, and the process shifts to plugging control (S36).

As described above, according to the present embodiment, when the control unit 3 shifts from the regenerative braking to the plugging braking or the power running control, the control unit 3 compares a value larger than the read value of the motor current by the predetermined value α as the comparison command value Ir. The regenerative contactor 5 is output to the circuit 32 and thereafter waits for the operation time during which the regenerative contactor contact 5 is turned on, and performs other processing during this standby time. During this time, since the comparison circuit 32 directly turns off the chopper element 11 when the motor current value becomes larger than the comparison command value Ir, the inrush current is prevented. Thereby, the calculation processing load on the CPU 31 of the control unit 3 is reduced. Then, when the standby time is over, the control unit 3 continuously performs processing for shifting to plugging braking or powering control. Therefore, also in the present embodiment, the chopper operation of the chopper element 11 can be continued while the regenerative contactor contact 5 is turned from off to on, so that the feeling of braking loss can be eliminated, and the regeneration can be performed while performing the chopper control of the chopper element 11. Since the transition from the braking to the plugging braking or the powering control is performed, the braking torque changes smoothly, and the braking shock can be eliminated. In this embodiment, as described above, the contact-on detection means includes the current detector 6, the comparison circuit 32, and the signal selector.

Next, a fourth embodiment will be described. In the present embodiment, a contact voltage detection circuit that detects a change in contact voltage instead of the motor current value is provided as the contact on detection means. The basic hardware configuration here is the same as in FIG. 1, and a contact voltage detection circuit as shown in FIG. 10 is additionally provided. In the figure, a DC motor side terminal of a regenerative contactor contact 5, that is, in this embodiment, a connection point A (see FIG. 1) between the contact and the current detector 6, and a series circuit of resistors R1 and R2 between a circuit ground. Is connected, and one input terminal of the comparison circuit 36 is connected to a connection point between the resistors R1 and R2. The other input terminal of the comparison circuit 36 receives a reference voltage Vrf for determining a voltage level. Further, the output signal of the comparison circuit 36 is input to the control unit 3.

In the above configuration, when the regenerative contactor contact 5 is turned on, the voltage at the connection point A rises from the ground voltage level to the battery voltage level, and this voltage rise is detected by the comparison circuit 36, and the detection signal is sent to the control unit. 3 is input. Therefore, when this control signal is input, the control section 3 turns off the chopper element 11 and then shifts to plugging control. As described above, according to the present embodiment, ON of the regenerative contactor contact 5 is detected based on a change in the contact voltage value,
Since the chopper operation of the chopper element 11 is turned off, the chopper element can be protected. As a result, similarly to the above-described embodiments, it is possible to improve the braking feeling by preventing a feeling of braking loss and prevent a braking shock.

As described above, according to the present invention, the chopper operation of the chopper element is continuously performed even during the ON operation time of the regenerative contactor contact, so that the feeling of missing braking when switching from regenerative braking to plugging braking or power running control is eliminated. The braking feeling can be greatly improved. Further, after the regenerative contactor contact is turned on, the chopper operation is continuously controlled to perform plugging braking or power running control. Therefore, a braking control device for a DC electric vehicle that is smooth and has a comfortable ride without braking shock can be obtained.

[Brief description of the drawings]

FIG. 1 is a circuit example of a braking control device for a DC electric vehicle according to the present invention, and is an explanatory diagram of an operation at the time of regenerative braking.

FIG. 2 is a circuit example of a braking control device for a DC electric vehicle according to the present invention, and is an explanatory diagram of an operation at the time of plugging braking.

FIG. 3 is an example of a control flowchart illustrating a control method according to the first embodiment.

FIG. 4 is a time chart illustrating a control method according to the first embodiment.

FIG. 5 is an example of a control flowchart illustrating another control method of the first embodiment.

FIG. 6 is an example of a comparison circuit of the braking control device according to the second embodiment.

FIG. 7 is a time chart illustrating a control method according to a second embodiment.

FIG. 8 is an example of a comparison circuit of the braking control device according to the third embodiment.

FIG. 9 is a control flowchart example illustrating a control method according to a third embodiment.

FIG. 10 is an example of a contact voltage detection circuit (an example of a contact ON detection circuit) of a braking control device according to a fourth embodiment.

FIG. 11 is a circuit diagram according to the related art.

[Explanation of symbols]

1 accelerator circuit, 2 forward / backward switch, 3 control unit,
4 Preliminary excitation circuit, 5 Regenerative contactor contact, 5R Exciting coil, 6 Current detector, 7 DC motor, 7a Armature, 7b Field coil, 8 Forward contactor, 9 Reverse contactor, 11 ... Chopper element, 12 ... Plugging diode, 13 ... Flywheel diode, 14 ...
Regenerative diode, 15: motor speed detector, 16: battery, 31: CPU, 32: comparison circuit, 34: signal selector, 36: comparison circuit.

Claims (3)

[Claims] 1. A DC motor for driving a vehicle.
And a forward contactor (8) and a reverse contactor for switching the direction of the field current of the DC motor (7) to the forward or reverse direction.
(9), DC motor (7) field coil (7b) and armature (7a)
Chopper element (1) that controls the motor current flowing through
1) and a regenerative contactor contact (5) connected between the DC power supply and the armature (7a), and switching between the forward contactor (8) and the reverse contactor (9), and the regenerative contactor contact (5) In a DC electric vehicle braking control device that performs on / off control and chopper control of a chopper element (11) to perform regenerative braking or plugging braking by a DC motor (7), the switching from regenerative braking to plugging braking or power running control is performed. At the time of shifting, the regenerative contactor contact (5) is turned on with the chopper element (11) chopper-operated or turned on, and after the regenerative contactor contact (5) is turned on, the plugging braking or the chopper control of the chopper element (11) is performed. A braking control device for a DC electric vehicle, comprising a control unit (3) for performing power running control. 2. A braking control device for a DC electric vehicle according to claim 1, further comprising contact on detection means (6, 32, 36) for detecting that a regenerative contactor contact (5) is turned on, and 3) The contact-on detecting means (6, 32, 36) turns off the chopper element (11) when the contact-on is detected, and thereafter shifts to plugging braking or powering control. Braking control device. 3. The braking control device for a DC electric vehicle according to claim 1, wherein a current detector (6) for detecting a current value of an armature (7a) of the DC motor (7) and a DC motor (7). Attach one of the motor speed detectors (15) to detect the speed,
The control section (3) turns on the regenerative contactor contact (5) in a state where the chopper element (11) is chopper-operated, when the detected current value of the current detector (6) is equal to or less than a predetermined set value, Alternatively, the braking control device for a DC electric vehicle is performed when the rotation speed detected by the motor rotation speed detector (15) is equal to or less than a predetermined set value.