JPH0721117Y2 - Dynamic braking control circuit for electric vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of the Invention The present invention relates to a dynamic braking control circuit for starting braking in an electric vehicle using a DC series-wound motor under conditions suitable for the running state of the vehicle.

2. Description of the Related Art An electric vehicle uses a direct-current motor driven by an on-board battery as a drive source to perform forward / reverse switching and speed control necessary for driving the vehicle. Therefore, its drive circuit (1) is generally shown in FIG. It has the configuration as shown.

In FIG. 5, (2) is a vehicle-mounted battery, (3) is a DC series-wound motor including an armature coil (3a) and a field coil (3b), and (4) is resistors r ₁ , r ₂ , r. ₃ a series connection, the contact m _1, m _2, m ₃ to conduct in the forward in conjunction with the depression of the accelerator pedal, not shown, for speed control so as to short-circuit the respective resistors r _1, r _2, r ₃ The variable resistance circuit (5) is a normally open contact (5a) that connects one end of the field coil (3b) to one end of the variable resistance circuit (4) when the speed control means such as the accelerator pedal is operated in the forward mode. And a forward switch (6) comprising a normally closed contact (5b) connecting one end of the field coil (3b) to the armature coil (3a) when the speed control means is not operated and not in the forward mode. When the speed control means is operated in the reverse drive mode, the other end of the field coil (3b) is connected to the variable resistance circuit (4). A normally open contact (6a) connected to the end,
A reverse switch consisting of a normally closed contact (6b) connecting the other end of the field coil (3b) to the armature coil (3a) when the speed control means is not operated and in a mode other than the reverse mode, and (7) is a fuse Is.

When the drive circuit (1) of the DC series-wound motor (3) is in the neutral mode state as shown in FIG. 5, the forward switch (5) causes the normally open contact (5a) to conduct when the accelerator pedal is depressed a little. The drive circuit (1) is switched to the forward mode and the motor (3) starts rotating in the forward direction. After this, by further depressing the accelerator pedal,
The contacts interlocking with this are closed in the order of m ₁ → m ₂ → m ₃ , and the voltage applied to both ends of the armature coil (3a) rises, so that the rotation speed of the motor (3) rises. Since the both ends of the variable resistance circuit (4) are short-circuited, the maximum speed is obtained when the contact m ₃ is conductive. After that, by changing the depressing state of the accelerator pedal to bring one of the contacts m ₁ , m ₂ , and m ₃ into conduction, the rotation speed of the motor (3) can be controlled to a desired magnitude.

When moving backward, release the accelerator pedal, switch the forward switch (5) to the normally closed contact (5b), and then press the reverse switch (6) with the mode selection switch (not shown).
When the normally open contact (6a) of the motor is turned on, the drive circuit (1) of FIG. 5 is switched to the reverse drive mode, and the direction of the current flowing through the field coil (3b) is reversed. 3) rotates in the reverse direction. Even in this case, the speed can be controlled by depressing the accelerator pedal.

Problems to be Solved by the Invention Generally, mechanical braking is used for braking the electric vehicle. However, since an electric vehicle does not have the equivalent of engine braking in a normal vehicle, when a large braking force is required, the braking force may be insufficient when traveling on a downhill, for example.

Therefore, the present invention uses the drive circuit itself of the DC series-wound motor, hardly increases the number of parts, and starts the braking only when the traveling of the vehicle becomes the predetermined condition that the above mechanical brake needs assistance. An object of the present invention is to provide a dynamic braking type brake.

Means for Solving Problems The present invention has been made in view of the above problems, and a technical means for solving the above problems is a field coil (10) of a direct current series motor, which is a prime mover of an automobile.
First series circuit (9) connecting b) and DC power supply (11)
And a second series circuit (12) in which the armature coil (10a) of the DC series-wound motor and the variable resistance circuit (13) for speed control are connected, and three states of forward, neutral and reverse, and forward, A changeover switch which switches the polarity of the second series circuit (12) between time and reverse and connects to the first series circuit (9), and returns to the neutral state when the speed control means such as the accelerator pedal is not operated. A drive circuit (8) for a DC series-wound motor of an electric vehicle comprising a circuit (14), a connection point P between the DC power supply (11) and the field coil (10b) of the first series circuit (9), Variable resistance circuit for speed control (1
A shunt circuit (26) incorporating a power generation control switch circuit (18) for connecting a predetermined connection point Q away from the end of 3).
And the above-mentioned power generation on the condition that the output a of the down-slope sensor for detecting that the vehicle is traveling on a downhill with an inclination of a predetermined angle or more and the accelerator OFF output b with the speed control means open are simultaneously established. A control condition determination circuit (19) for conducting the control switch circuit (18), and the power generation control switch circuit (18) is conducted by the output c of the control condition determination circuit (19) to generate a second series Circuit (1
A shunt circuit (T) including a closed loop circuit (S) whose both ends are closed by a changeover switch circuit (14) and a field coil (10b) connected in parallel with a resistor in the closed loop circuit (S). And the braking force proportional to the inertial traveling speed is generated in the armature coil (10a).

Action The basic operation (forward / reverse rotation and speed control) of the above means is performed as follows.

That is, the changeover switch circuit (14) switches and connects the both side terminals of the first series circuit (9) and the second series circuit (12) in opposite directions during forward movement and backward movement. by this,
A field coil in a drive circuit (8) for a direct current winding motor in which the field coil (10b), armature coil (10a), DC power supply (11), and variable resistance circuit for speed control (13) are connected in series. The currents flowing through (10b) and the armature coil (10a) have relatively opposite polarities, and normal rotation (forward movement) and reverse rotation (reverse movement) are switched. In addition, the speed control variable resistance circuit according to the amount of depression of the accelerator pedal (1
Speed control is performed by changing the motor current by changing the resistance value in 3).

The dynamic braking is performed when the braking condition judging circuit (19), which is a feature of the present invention, detects that the braking start condition is satisfied. The braking start condition is to release the foot from the accelerator pedal, which is the speed control means, at least when the vehicle is traveling downhill with an inclination of a predetermined angle or more.

When this condition is satisfied, the changeover switch circuit (14) which has been neutralized in response to the accelerator OFF output disconnects the DC power supply (11) and short-circuits / connects both terminals of the second series circuit (12). Then, the current of the armature coil (10a) generated by the inertial running of the vehicle is changed to the variable resistance circuit for speed control (1
It makes it possible to generate dynamic braking by consuming the inertial force of the vehicle as heat energy. If the dynamic braking switch circuit (18) is not turned on at this time, the electromotive force generated in the armature coil (10a) is only due to the residual magnetism of the field coil (10b), which is too small for dynamic braking. Not valid. However, in the present invention, at this time, the braking condition determination circuit (19) makes the dynamic braking switch circuit (18) conductive. A predetermined connection in the speed control variable resistance circuit (13) in which a part of the speed control variable resistance circuit (13) (the dynamic braking switch circuit (18) is connected to the field coil (10b) The resistance between the point b and the speed control variable resistance circuit (13) side terminal of the second series circuit (12) is connected, and the voltage generated by dividing the armature coil (10a) is ,
It is applied to both ends of the field coil (10b) with the same polarity as in normal rotation (forward movement). As a result, a predetermined current is passed through the field coil, and the field magnetic flux required for dynamic braking exceeding the residual magnetism is secured. As a result, the inertial force of the vehicle is consumed as heat energy in the variable resistance circuit for speed control, and dynamic braking is performed.

Embodiment An embodiment of the present invention will be described with reference to a drive circuit (8) for a DC series motor shown in FIG.

In FIG. 1, (9) is a first series circuit in which a field coil (10b) of a DC series-wound motor and a DC power source (11) such as a vehicle battery are connected in series, and (12) is an armature coil of the motor. A second series circuit in which (10a) and a variable resistance circuit (13) for speed control are connected in series, (14) is a speed when moving forward between both ends of the first and second series circuits (9) and (12). By operating the control means, the connection is made in the forward direction, and by operating the speed control means in the reverse direction, the connection is made in the reverse direction. In the neutral state where the speed control means is not operated, as shown in FIG. A changeover switch circuit which is connected to one end of the field coil (10b) in a state where both ends of the series circuit (12) are short-circuited,
(15) is a manual forward / reverse selection switch (16) and accelerator OFF contact (M
Over switch control circuit for controlling switching the switch circuit (14) by _0), (18) during dynamic braking, the DC power source of the first series circuit (9) (11) and the field coil (10b)
, And a predetermined connection point Q distant from the end of the speed control variable resistance circuit (13), the switch circuit for dynamic braking comprising switch elements such as thyristors (18a) having both ends connected, ) Indicates that both the output a of the downward gradient sensor (not shown) mounted on the vehicle body of the vehicle and the accelerator OFF main force b of the accelerator control mechanism (not shown) are generated.
Detected by the gate (19a), the thyristor (18a)
Is a braking condition determination circuit that applies a braking condition determination output c to the gate of to make it conductive.

In the drive circuit (8), the variable resistor circuit (13) for speed control is constituted by connecting resistors R ₁ , R ₂ and R ₃ in series, and is a contact which is sequentially conducted in conjunction with an accelerator pedal (not shown).
The resistors R ₁ , R ₂ , R ₃ are selectively short-circuited by M ₁ , M ₂ , M ₃ .

The changeover switch circuit (14) is configured by combining a forward switch (20) and a reverse switch (21).

The forward switch (20) has a normally open contact (20) at the end of the second series circuit (12) on the armature coil (10a) side when a speed control means such as an accelerator pedal is operated in the forward mode.
a) to the end of the first series circuit (9) on the DC power supply (11) side, and the normally closed contact (20b) to the first series circuit (20b) when the speed control means is not operated or in the forward mode. Connect to the end of 9) on the side of the field coil (10b). In addition, each contact (20a) (20b) of this forward switch (20)
It is opened and closed by the electromagnet (20c) in the changeover switch control circuit (15).

The reverse switch (21) uses the normally open contact (21a) at the end of the second series circuit (12) on the speed control variable resistance circuit (13) side when the speed control means is operated in the reverse mode. At the end of the first series circuit (9) on the DC power supply (11) side,
Further, when the speed control means is not operated or in the reverse mode, the normally closed contact (21b) is bonded to the end of the first series circuit (9) on the side of the field coil (10b). The contacts (21a) (21b) of the reverse switch (21) are opened and closed by an electromagnet (21c) in the changeover switch control circuit (15).

Further, the dynamic braking switch circuit (18) includes a vehicle-mounted battery (11) and a field coil (10b) in the first series circuit (9).
A switching element, for example, a thyristor (18a), between the connection point P of P and the connection point Q of the resistors R ₁ and R _{2 in} the speed control variable resistance circuit (13), and the cathode side of the first series circuit ( 12)
It is configured to be connected to.

Next, the operation of the drive circuit (8) will be described.

To move the vehicle forward, the forward / reverse selection switch (16) is manually connected to the forward side in the neutral mode state of FIG. 1 in which the motor is not rotating. When you depress the accelerator pedal, the accelerator OFF contact (M ₀ ) is first
And the normally open contact (20a) of the forward switch (20) is closed by energizing the electromagnet (20c), and the forward mode state of FIG. 2 is entered. Then, current flows through the drive circuit (8) as shown by the arrow in FIG. This causes the motor to start rotating in the forward direction. After that, by further pressing an accelerator pedal (not shown), the contacts are closed in the order of M ₁ → M ₂ → M ₃ , first resistor R ₁ , then resistors R ₁ and R ₂ , and finally resistor R ₁ . ₁ , R ₂ and R ₃ are short-circuited. As a result, the voltage drop in the speed control variable resistance circuit (13) is reduced, the voltage applied to the armature coil (10a) is increased, and the rotation speed of the motor is increased. After that, when it is desired to decelerate, the closed state of the contacts M ₁ , M ₂ , M ₃ may be changed by operating the accelerator pedal.

When you want to rotate the motor in the reverse direction to move the vehicle backward, return the accelerator pedal, connect the forward / reverse selection switch (16) to the reverse side by manual operation, and step on the accelerator pedal to move the electromagnet (21c). The energization closes the normally open contact (21a) of the reverse switch (21), and the reverse mode state of FIG. 3 is entered. At this time, the electromagnet (20c) is not energized, and the forward switch (20) is in the state where the normally closed contact (20b) is closed, so that as shown in FIG.
The direction of the current in b) does not change, and the armature coil (10a)
Since the direction of the electric current is changed to energize, the motor rotates in the reverse direction. Even during this reverse movement, speed control is performed in the same manner as above by the contacts M ₁ , M ₂ , M _{3 which} are opened and closed in conjunction with the accelerator pedal.

Next, the operation of dynamic braking will be described.

When the vehicle is traveling forward on a downhill, the downhill gradient sensor produces an output "a" of "H" level. In this state, when the foot is released from the accelerator pedal which is the speed control means, all the contacts M ₀ , M ₁ , M ₂ and M ₃ are opened. Accelerator OFF contact
Since the electromagnets (20c) and (21c) are not energized when M ₀ is opened, as shown in FIG. 4, the changeover switch circuit (14)
Is switched to a neutral mode state (the forward switch (20) and the reverse switch (21) both have normally open contacts (20a) (21a) open and normally closed contacts (20b) (21b) closed). At the same time, since the "H" level accelerator OFF output b is generated, the braking condition range circuit (19) that has detected the coincidence with the already generated "H" level downward gradient sensor output a is changed to the thyristor ( 18a) is applied with a braking condition determination output c to bring it into a conductive state. Then, because the armature coil (10a) is rotating in the same direction as before due to inertia, the field coil (10a)
An electromotive force is generated by the residual magnetism in b), and a current flows as indicated by an arrow in FIG. The current path at this time is the closed loop circuit S in which both ends of the second series circuit (12) are closed by the changeover switch circuit (14) and the resistor in the closed loop circuit by the dynamic braking switch circuit (18). It is a shunt circuit T composed of a field coil (10b) connected in parallel with R ₁ . In this dynamic braking state, the voltage corresponding to the voltage drop of the resistor R ₁ is applied to the field coil (10b). Field magnetic flux is generated. The armature coil (10a) generates an electromotive force proportional to the speed of inertial running of the automobile, and a variable resistance circuit for speed control (13) composed of resistors R ₁ , R ₂ and R ₃ connected in series. An electric current is applied to the car to consume the inertial force of the car as Joule heat. Observing this from the vehicle body side, the armature coil (10a) performs a braking action with a braking force proportional to its inertial traveling speed.

Note that the above-described dynamic braking is actually used together as an auxiliary to a mechanical brake.

In the drive circuit (8), the changeover switch circuit (14) is set to the neutral state, and the dynamic braking switch circuit (18)
Immediately after the electric field is turned on, no electric current is applied to the field coil (10b), so that the dynamic braking is started by the residual magnetism of the field coil (10b), which may cause unstable operation. Therefore, in order to ensure the starting operation, as shown by the dotted line in FIG. 1, a braking start power source (24) including a small capacity storage battery (22) and a current limiting resistor (23) The two series circuits (12) are inserted and connected between the armature coil (10a) side end and the field coil (10b) side terminal of the vehicle battery (11). This insertion circuit energizes the field coil (10b) only immediately after the start of the dynamic braking by the braking start power source (24) charged during the forward running, and the field magnetic flux is sufficiently large from the start of the dynamic braking. Generate.

Further, the thyristor (18a) as a switch element constituting the switch circuit (18) for dynamic braking is replaced by another switch, for example, a magnet switch (25) which is closed by a braking condition determination output c shown by a dotted line in FIG. You can also

Further, the present invention is not limited to the circuit configuration of the above embodiment, and the changeover switch circuit (14) may be designed so as to have the same function as described above, and may be configured by combining different kinds of parts. it can. Also, the variable resistor circuit for speed control (13) can be changed in design, for example, by increasing the number of resistors in series, and the connection of the switch circuit for dynamic braking (18) to the variable resistor circuit is suitable for dynamic braking. It may be selected at a position where a high voltage is obtained.

EFFECTS OF THE INVENTION According to the present invention, it is possible to perform dynamic braking in a DC series-wound motor having a variable resistance circuit for speed control, which consumes no electric power at the time of braking and does not burden a vehicle battery.
Further, for example, only by adding a switch circuit for dynamic braking consisting of only one thyristor and a braking condition determination circuit for controlling this, dynamic braking adapted to the running condition becomes possible. Therefore, it is possible to obtain the strong braking force required for traveling on a slope without increasing the size and complexity of the device, minimizing the cost increase and improving the performance. It is performed only when driving on a slope that requires assistance, so that it is of high practical value especially in an electric vehicle with a limited battery capacity that avoids unnecessary consumption of running energy.

[Brief description of drawings]

1 to 4 show an embodiment of a dynamic braking control circuit for a DC series-wound motor according to the present invention. FIG. 1 is a stopped state, FIG. 2 is a forward state, FIG. 3 is a reverse state, and FIG. FIG. 4 shows the dynamic braking states, respectively. FIG. 5 is a circuit diagram showing an example of a drive circuit of a conventional DC series-wound motor. (8) ... DC series-wound motor drive circuit (electric vehicle dynamic braking control circuit) (9) ... 1st series circuit (10a) ... DC series-wound motor armature coil (10b) ... DC series Winding motor field coil (11) ... DC power supply (vehicle battery) (12) ... second series circuit (13) ... speed control variable resistance circuit (14) ... changeover switch circuit (18) ... … Dynamic braking switch circuit (18a) …… Switch element (19) …… Braking condition judgment circuit (20) …… Forward switch (21) …… Reverse switch (20a), (21a) …… Normally open contact (20b) ), (21b) …… Normally closed contact a …… Down slope sensor output b …… Accelerator OFF output c …… Brake condition judgment output

Claims (1)

[Scope of utility model registration request] 1. A first series circuit (9) connecting a field coil (10b) of a DC series-wound motor, which is a motor of an automobile, and a DC power supply (11), and an armature coil () of the DC series-wound motor. 10a) and a second series circuit (12) in which a speed control variable resistance circuit (13) is connected to the second series circuit (12), which is switched between three states of forward, neutral and reverse, and the second series circuit (forward and backward) ( DC switch of an electric vehicle comprising a changeover switch circuit (14) which switches the polarity of 12) and is connected to the first series circuit (9) and returns to a neutral state when speed control means such as an accelerator pedal is not operated. In the winding motor drive circuit (8), the connection point P between the DC power supply (11) and the field coil (10b) of the first series circuit (9), and the speed control variable resistance circuit (1
A shunt circuit (26) incorporating a power generation control switch circuit (18) for connecting a predetermined connection point Q away from the end of 3).
And the above-mentioned power generation on the condition that the output a of the down-gradient sensor for detecting that the vehicle is traveling on a downhill with an inclination of a predetermined angle or more and the accelerator OFF output b for releasing the speed control means are simultaneously established. A control condition judging circuit (19) for making the control switch circuit (18) conductive, and the power generation control switch circuit (18) is made conductive by the output c of the control condition judging circuit (19) so that the second series Both ends of the circuit (12) are changeover switch circuits (14)
And a field coil (10) connected in parallel with the resistor in the closed loop circuit (S).
and a shunt circuit (T) including b), and the armature coil (1
0a), a dynamic braking control circuit characterized in that a braking force proportional to the inertial traveling speed is generated.