JP3344011B2 - Drive control device for DC motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control device for a DC motor, and more particularly to a drive control device for a DC motor that uses both regenerative braking and plugging braking.

[0002]

2. Description of the Related Art In general, regenerative braking is employed in DC motors used in battery-powered electric vehicles such as battery forklifts in order to save power. However, regenerative braking alone does not provide sufficient braking torque at low speeds of the motor, so plugging (reverse phase) braking is also used.

FIG. 3 shows a general drive control circuit of a DC motor used for driving driving wheels of a battery-powered electric vehicle. A regenerative contactor 2 and an armature 3 of a DC series motor 3 are connected between positive and negative terminals of the battery 1.
a, the forward contactor 4, the reverse contactor 5, the field coil 3b of the DC series motor 3, and the main transistor 6 are connected in series. The flywheel diodes 7 and 8 are connected between the forward and backward contactors 4 and 5 and the positive terminal of the battery 1. The negative terminal of the battery 1 is grounded, and a regenerative diode 9 is connected between the negative terminal and the regenerative contactor 2. Further, a regeneration transistor 10 and a regeneration register 11 are connected in series between the positive terminal of the battery 1 and the forward and reverse contactors 4 and 5.

The regenerative contactor 2 is composed of an exciting coil 2a and a contact 2b, and is turned on (solid line in the figure) and dropped (dashed line in the figure) by the control circuit 12 to control the exciting coil 2a.
This is done by controlling the power supply to the power supply.

The bases of the transistors 6 and 10 are connected to drive circuits 12a and 12b provided in the control circuit 12. The respective drive circuits 12a, 12b
Are controlled by a CPU 12 c provided in the control circuit 12. That is, on / off of the transistors 6 and 10 is controlled by the control circuit 12 (more specifically, by the drive circuits 12a and 12b controlled by the CPU 12c).

[0006] The electric motor 3 drives driving wheels (not shown) of the electric vehicle. Then, the direction of the field current flowing through the field coil 3b is changed based on the complementary switching operation of the forward and reverse contactors 4 and 5, and the electric motor moves forward and backward, so that the electric vehicle moves forward and backward. It has become. The forward and reverse contactors 4 and 5 are turned on and off by the control circuit 12 controlling the power supply to the exciting coils (not shown) of the contactors 4 and 5.

The control of the speed of the electric vehicle is performed by chopper control of the main transistor 6. That is, the ON / OFF of the main transistor 6 is controlled by the control circuit 12, and the current is supplied from the battery 1 to the electric motor 3 in accordance with the switching operation of the main transistor 6, so that the rotation speed of the electric motor 3, that is, the vehicle speed of the electric vehicle is reduced. Controlled.

Now, it is assumed that the forward and reverse contactors 4 and 5 are switched from the forward position (shown by broken lines) to the reverse position (shown by solid lines) by switching back. (1) At this time, the control circuit 12 checks whether regenerative braking is possible, and if it is determined that regenerative braking is possible, controls the energization of the exciting coil 2a to drop the regenerative contactor 2 (dashed line in the figure). ) And turn on each transistor 6, 10.

Then, from the plus terminal of the battery 1, through the regeneration transistor 10, the regeneration register 11, the reverse contactor 5, the field coil 3 b, the forward contactor 4 and the main transistor 6, the negative terminal of the battery 1 The pre-excitation current I1 flows to When the pre-excitation current I1 flows through the field coil 3b, an electromotive force VA is generated in the armature 3a in the direction indicated by the arrow VA.

(2) When the electromotive force VA generated in the armature 3a exceeds a certain value, the pre-excitation current I
2 begins to flow. This pre-excitation current I2 increases the field current (sum of the pre-excitation currents I1 and I2) flowing through the field coil 3b, and the electromotive force VA increases. Then, as the electromotive force VA increases, the pre-excitation current I2 further increases.

(3) This is repeated, and the pre-excitation current I
When 2 becomes larger than a certain level, the control circuit 12 turns off the regenerating transistor 10. Then, the pre-excitation current I1 stops flowing, but the pre-excitation current I2 tries to keep flowing.

(4) In this state, the control circuit 12 turns off the main transistor 6. Then, the pre-excitation current I2 flowing from the field coil 3b to the collector of the main transistor 6 flows to the flywheel diode 8. That is, the electromotive force VA of the armature 3a and the magnetic energy stored by the inductance of the field coil 3b cause the forward and backward contactors 4 of the armature 3a to move.
A regenerative current flows from the side 5 to the regenerative contactor 2 side of the armature 3a via the reverse contactor 5, the field coil 3b, the forward contactor 4, the flywheel diode 8, the battery 1, and the regenerative diode 9. . Therefore, since the electric power generated by the electric motor 3 is regenerated to the battery 1, the battery is charged, and the electric motor 3 is subjected to braking corresponding to the electric power (ie, regenerative braking).

(5) Thereafter, the control circuit 12 controls the main transistor 6 by chopper. Then, the above operations (3) and (4) are repeated by the switching operation of the main transistor 6, and a desired regenerative braking is applied to the electric motor 3, so that the rotation speed is reduced.

When the rotation speed of the motor 3 decreases, the armature 3
Since the electromotive force VA of a decreases and the regenerative current (regenerative power) to the battery 1 decreases, the braking torque of the regenerative braking extremely decreases. When the electromotive force VA of the armature 3a becomes lower than the voltage VB of the battery 1, no regenerative current flows and regenerative braking is not applied. That is, when the rotation speed of the electric motor 3 decreases, sufficient braking torque cannot be obtained only by regenerative braking. Therefore, when the rotation speed of the electric motor 3 has decreased to a certain degree, the regenerative braking is shifted to the plugging braking so that a sufficient braking torque can be obtained. Actually, not the rotation speed of the electric motor 3 but the duty ratio of the main transistor 6 is detected, and when the duty ratio reaches a set value (generally 70 to 100%), the control circuit 12 performs the regenerative braking. When it is determined that a sufficient braking torque cannot be obtained, switching from regenerative braking to plugging braking is performed.

That is, after turning off the main transistor 6, the control circuit 12 controls the energization of the exciting coil 2a to turn on the regenerative contactor 2 (solid line in the drawing) (the regenerative transistor 10 is continuously turned off). ).

(6) Then, by the electromotive force VA of the armature 3a, the forward and backward contactors 4 and 5 of the armature 3a pass through the flywheel diode 7 and the regenerative contactor 2 to form the armature 3a. A current flows to the regenerative contactor 2 side.

(7) In this state, the control circuit 12 turns on the main transistor 6. Then, the contactor for regeneration 2, the armature 3a, the contactor for reverse movement 5, the field coil 3b, the contactor for forward movement 4,
A current flows to the negative terminal of the battery 1 via the main transistor 6. That is, since a field current in the direction of reversing the electric motor 3 flows through the field coil 3b, the electric motor 3 tries to reverse, and the electric motor 3 is accordingly braked (ie, plugging braking).

Thereafter, the control circuit 12 controls the main transistor 6 by chopper. Then, by the switching operation of the main transistor 6, the above operation (6) is performed when the main transistor 6 is off, and the above operation (7) is performed when the main transistor 6 is on. Therefore, the desired plugging braking is applied to the electric motor 3, and the rotation speed is reduced. Then, since the electric motor 3 stops once and then reverses, the electric vehicle switches back.

[0019]

It should be noted that when performing plugging braking, it is necessary to turn on the main transistor 6 after the regeneration contactor 2 is completely turned on. This is because, when the regeneration contactor 2 is turned on after the main transistor 6 is turned on, a large inrush current flows, and the regeneration contactor 2
Is damaged. Also, the inrush current causes the braking torque of the plugging braking to increase sharply,
This is because a braking shock occurs in the electric vehicle.

However, the turning on of the regenerative contactor 2 depends on the temperature of the exciting coil 2a, and after the control circuit 12 controls the energization of the exciting coil 2a, the contact 2
The time until b is completely closed (hereinafter referred to as injection time)
Has a variation of several tens of msec.

Therefore, when the main transistor 6 is turned on, it is necessary to take into account the variation in the turn-on time. Therefore, conventionally, first, the longest value of the injection time is obtained by an experiment, and a time obtained by multiplying the maximum value by a predetermined safety factor (hereinafter, referred to as a set time) is calculated. I had memorized. Then, the control circuit 12 waits until the set time elapses after controlling the energization of the exciting coil 2a, and turns on the main transistor 6 when the set time elapses to perform the chopper control.

However, since the set time is set to be longer to avoid the above-mentioned problems (damage of the contact 2b, braking shock of the electric vehicle), the remaining time of the set time after the regenerative contactor 2 is completely turned on is set. Only time was wasted. That is, neither the regenerative braking nor the plugging braking is performed in the remaining time of the set time, so that the longer the remaining time (ie, the shorter the closing time), the longer the time in which braking is not applied, The braking feeling will be degraded.

As described above, conventionally, when shifting from the regenerative braking to the plugging braking, the main transistor 6 is chopper-controlled after waiting for a set time. Therefore, a time lag occurs in the shifting of the braking operation, and the braking feeling is reduced. There was a problem of getting worse.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide a good braking feeling without a time lag in the transition from regenerative braking to plugging braking. An object of the present invention is to provide a drive control device for a DC motor with a simple configuration.

[0025]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a DC motor, switching means for switching the excitation coil wiring of the DC motor to switch its excitation direction, and switching from a DC power supply to a DC motor. A switching element for chopper-controlling the supplied current, and a regenerative contactor connected between a positive terminal of the DC power supply and a field coil of the DC motor are provided, and both regenerative braking and plugging braking are used. In the DC motor drive control device, when switching from regenerative braking to plugging braking, the switching element is turned on for a short time, and at that time, the terminal voltage on the DC motor side of the regenerative contactor is detected. It is determined whether or not the regenerative contactor is fully turned on based on the Start the chopper control element as its gist in that a control means for applying a plugging brake to the DC motor.

[0026]

Therefore, according to the present invention, when switching from regenerative braking to plugging braking, the switching element is turned on for a short period of time, and at that time, the terminal voltage of the regenerative contactor on the DC motor side is detected. At this time, if the regenerative contactor is completely turned on, the terminal voltage becomes the power supply voltage of the DC power supply. If the regenerative contactor is not turned on, the terminal voltage becomes the voltage of the negative terminal of the DC power supply (ground potential if the negative terminal of the DC power supply is grounded). Therefore, it can be determined from the terminal voltage whether the regeneration contactor is completely turned on. When the regenerative contactor is completely turned on, chopper control of the switching element is started to apply plugging braking to the DC motor.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a drive control circuit of the DC motor according to the present embodiment.

The present embodiment differs from the conventional example shown in FIG. 3 only in that the potential of the connection point A between the regenerative contactor 2 and the armature 3a is detected by the control circuit 12. is there. Therefore, in FIG. 1, the same members as those in the conventional example shown in FIG. 3 are denoted by the same reference numerals, and detailed description thereof will be omitted.

The control circuit 12 turns on the main transistor 6 for a very short time (about several μsec) at the time of the transition from the regenerative braking to the plugging braking, and detects the potential of the connection point A when the main transistor 6 is on. Then, the control circuit 12 determines whether or not the regenerative contactor 2 is completely turned on based on the potential of the connection point A. If it is determined that the regenerative contactor 2 is completely turned on, the control circuit 12 starts the chopper control of the main transistor 6 to start the electric motor. 3. Plugging braking is applied to 3.

FIG. 2 shows the potential at the connection point A during the transition from regenerative braking to plugging braking. When the main transistor 6 is turned off during the regenerative braking, as described above, a regenerative current flows due to the electromotive force VA of the armature 3a and the magnetic energy stored by the inductance of the field coil 3b. The path of the regenerative current flows from the forward and reverse contactors 4 and 5 of the armature 3 a to the reverse contactor 5, the field coil 3 b, the forward contactor 4, the flywheel diode 8, the battery 1 and the regenerative diode 9. Via the armature 3a, it reaches the regenerative contactor 2 side (that is, the connection point A). Here, the negative terminal of the battery 1 is grounded. Therefore, when the main transistor 6 is turned off during the regenerative braking, the potential at the connection point A becomes the ground potential (0 V).

On the other hand, during regenerative braking, the main transistor 6
Is turned on, the electromotive force VA of the armature 3a causes the forward and backward contactors 4 and 5 of the armature 3a to pass through the field coil 3b, the main transistor 6, and the regenerative diode 9 to the armature 3a. A current flows to the regenerative contactor 2 side (that is, the connection point A). Therefore, even when the main transistor 6 is turned on during the regenerative braking, the connection point A
Becomes the ground potential.

When the rotation speed of the electric motor 3 decreases, as described above, the electromotive force VA of the armature 3a drops below the voltage VB of the battery 1 so that regenerative current does not flow. Disappears.

At this time, when the main transistor 6 is turned off, the armature 3a does not form a closed circuit, and no current flows through this drive control circuit. However, armature 3
In the case a, the electromotive force VA is generated although it is lower than during regenerative braking. Also, in this drive control circuit,
Since a plurality of members (not shown) such as resistors are connected, the armature 3a and its members may form a closed circuit. For this reason, when the main transistor 6 is turned off when the regeneration is impossible, the potential of the connection point A is not determined.

On the other hand, when the main transistor 6 is turned on, a current flows by the electromotive force VA of the armature 3a as in the case of the regenerative braking, and the potential at the connection point A becomes the ground potential.

On the other hand, since the regenerative contactor 2 is turned on during the plugging braking, the connection point A is connected to the positive terminal of the battery 1 via the regenerative contactor 2. Therefore, the potential at the connection point A becomes equal to the voltage VB of the battery 1 irrespective of whether the main transistor 6 is on or off.

As described above, by detecting the potential of the connection point A when the main transistor 6 is turned on, the operating state at the time of the transition from the regenerative braking to the plugging braking (that is, during the regenerative braking → impossible regeneration → plugging braking) ) Can be detected, and it can be determined whether or not the regeneration contactor 2 has been completely turned on. That is, when the potential at the connection point A when the main transistor 6 is turned on is the ground potential, the regenerative contactor 2 is not turned on, and when the potential is VB, the regenerative contactor 2 is completely turned on.

The main transistor 6 is turned on when the potential of the connection point A is detected. As described above, when the main transistor 6 is turned off when regeneration is impossible, the potential of the connection point A becomes indefinite. (That is, it may be equal to the voltage VB of the battery 1).

However, when the regenerative contactor 2 is turned on after the main transistor 6 is turned on, a large rush current flows, and the above-described problem (pain of the contact 2b, braking shock of the electric car) occurs. Therefore, the time during which the main transistor 6 is kept on must be as short as possible to avoid inrush current. Therefore, the control circuit 12
Is a very short time (several μ) required for detecting the potential of the connection point A.
(approximately sec) for the main transistor 6. More specifically, the control circuit 12 controls the main transistor 6 for an extremely short time (a few seconds) until the voltage VB is detected at the connection point A after controlling the energization of the exciting coil 2a to turn on the regeneration contactor 2. (on the order of μsec) is repeated at intervals of several milliseconds.

As described above, in the present embodiment, when shifting from regenerative braking to plugging braking, it is determined whether or not the regenerative contactor 2 has been completely turned on by detecting the potential of the connection point A. . If it is determined that the regenerative contactor 2 has been completely turned on, the main transistor 6 is chopper-controlled to apply plugging braking to the electric motor 3.

Therefore, in the present embodiment, it is possible to quickly shift to the plugging braking without waiting for the set time when shifting from the regenerative braking to the plugging braking as in the conventional example. Therefore, a time lag does not occur in the transition of the braking operation, and a good braking feeling can be obtained.

In this embodiment, the connection point A of the conventional example shown in FIG. 1 is simply connected to the control circuit 12, and the circuit configuration is almost the same as that of the conventional example. it can. Further, in order to cause the control circuit 12 to perform the above-described detection / judgment operation, it is only necessary to change the program of the CPU 12c. Therefore, the conventional control circuit 12 can be used as it is, and modification of the conventional product can be easily dealt with. can do.

The present invention is not limited to the above embodiment, but may be implemented as follows. 1) The invention is used not only for electric vehicles but also for devices using a DC motor that uses both regenerative braking and plugging braking.

2) The series motor 3 is replaced with a shunt motor or a compound motor. 3) Replace the battery 1 with an appropriate DC power supply. 4) Replace the CPU 12c with a sequencer.

5) Each of the transistors 6, 10 is replaced with another switching element such as a thyristor.

[0045]

As described above in detail, according to the present invention, there is provided a drive control device for a DC motor capable of obtaining a good braking feeling without causing a time lag in a transition from regenerative braking to plugging braking. There is an excellent effect that it can be provided by a simple configuration.

[Brief description of the drawings]

FIG. 1 is a drive control circuit of a DC motor according to one embodiment of the present invention.

FIG. 2 is a chart showing a potential at a connection point A in FIG. 1 at the time of transition from regenerative braking to plugging braking.

FIG. 3 is a drive control circuit of a conventional DC motor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Battery as a DC power supply, 2 ... Regeneration contactor, 3 ... DC motor, 3a ... Field coil, 3b ... Exciting coil, 4 ... Forward contactor as switching means, 5
... reverse contactor as switching means, 6 ... main transistor as switching element, 12 ... control circuit as control means

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60L 7/00 102 B60L 7/12 H02P 3/10

Claims (1)

(57) [Claims] 1. A DC motor, switching means for switching wiring of an excitation coil of the DC motor to switch its excitation direction, a switching element for chopper controlling a current supplied from the DC power supply to the DC motor, A regenerative contactor connected between the positive terminal and the field coil of the DC motor, and a drive control device for the DC motor that uses both regenerative braking and plugging braking. When the switching element is turned on for a short time, the terminal voltage on the DC motor side of the regenerative contactor is detected when the switching element is turned on, and it is determined whether the regenerative contactor is completely turned on based on the terminal voltage. Then, when it is determined that the power is completely turned on, chopper control of the switching element is started and the DC motor is plugged in. Drive control device of the DC motor, characterized in that a control means for applying a ring braking.