JPH0584121B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a regenerative braking device for a DC motor using a semiconductor chopper, and particularly to a regenerative braking control device with improved control characteristics when regenerative braking is released.

[Background of the invention]

With the advancement and improvement of semiconductor switching devices such as thyristors and GTOs, various chopper devices have come to be widely used to control DC motors.

An example of a regenerative braking control system for an electric vehicle using such a chopper device is shown in FIG.

This figure 1 shows the main circuit connection and the flow of control signals at this time when the traction motor is controlled to a regenerative braking state. In this figure, 1 is the armature of the traction motor, 2 is the main The field winding of the electric motor, 3 is a smoothing reactor, 4 is a diode, 5 and 6 are switches, 7 is a pantograph, 8 is a chopper, 9 is a switching element such as a thyristor or GTO used in the chopper 8. A gate control section 10 controls the gate, and a brake command control section 10 generates a brake on/off signal for instructing the activation and release of the brake in response to a brake operation. In addition,
is the brake command output signal output from the brake command control unit 10, is the operation confirmation signal output from the switch 5 and confirms the operation of the switch 5, and is the operation confirmation signal of the switch 6, respectively. where IA represents the armature current under regenerative braking.

Next, the operation of this device will be explained.

Now, when the brake handle is operated and a brake operation is commanded, a signal is inputted to the brake command control unit 10, and a brake command output signal is output from the command unit 10.

As a result, the control proceeds in the order of signal → ON operation of switch 5 → signal → ON operation of switch 6 → signal → start of gate control signal generation operation of gate control section 9 → start of operation of chopper 8, and the main motor is in a regenerative braking state and generates brake torque.

The operation in the regenerative braking state is as follows.

When a brake operation is commanded, the main motor is forcibly rotated from the load side, and the armature 1 generates an electromotive force due to residual magnetism present in the magnetic circuit.

Therefore, if the chopper 8 is now in the on period, the armature 1 → field winding 2 → reactor 3
A short circuit consisting of → chopper 8 → switch 5 → armature 1 is formed, and armature current IA flows due to the self-excited power generation characteristics of the main motor.

Next, the chopper 8 is controlled to be turned off when the armature current IA reaches a predetermined value. Then, a back electromotive force is generated in the reactor 3 due to the armature current IA flowing during the ON period of the chopper 8, and the sum of the back electromotive force of the reactor 3 and the generated voltage of the armature 1 is the sum of the back electromotive force of the reactor 3 and the generated voltage of the armature 1. Since it is higher than the voltage (overhead line voltage), earth → switch 5 → armature 1 → field winding 2 → reactor 3 → diode 4
→ Switch 6 → Pantograph 7 → Armature current IA flows through the overhead wire path, and regenerative power is sent to the power supply side, allowing the main motor to obtain regenerative braking torque. On the other hand, when the chopper 8 enters a regenerative state during the off period, the back electromotive force of the reactor 3 decreases for a while, and when the sum of the back electromotive force of the reactor 3 and the generated voltage of the armature 1 becomes less than the overhead line voltage, regeneration begins. Current stops flowing and regenerative braking torque also becomes zero.

Therefore, by turning on the chopper 8 again, the armature current IA increases, and then by turning off the chopper 8, regenerative braking can be performed again.

Therefore, by turning on and off the chopper 8 at a predetermined period, it is possible to perform almost continuous regenerative braking operation, and the magnitude of the regenerative braking torque at this time is determined by the difference between the on period and the off period of the chopper 8. It can be controlled arbitrarily by controlling the ratio, that is, the distribution rate.

Note that the on/off period of the chopper 8 at this time can be made considerably short (in terms of frequency, it is several times shorter) by using GTO as a switching element.
In this case, even if reactor 3 is not provided as a separate device, sufficient regenerative voltage can be obtained from the inductance existing in the short circuit including armature 1 _. ,
The reactor 3 can be made unnecessary.

Next, when the brake handle is returned and brake release is commanded, the brake command control unit 1
A signal to turn off the brake is output from 0,
Signal → OFF operation of switch 5 → Signal → Switch 6
OFF operation → signal → stop of gate control signal generation operation of gate control unit 9 → stop of operation of chopper 8,
The control operation moves in this order, and the regenerative braking operation is stopped.

The operation at this time is shown in a timing chart as shown in Fig. 2. At time t ₀ , brake off is commanded and a signal is output, and thereafter, at time t when the operation delay time τ ₁ of the switch 5 has elapsed. ₁ and switch 5
is off and a signal is generated at the same time. Then, at time t ₂ when the operation delay time τ ₂ of the switch 6 has elapsed, the switch 6 is turned off, a signal is generated, and the chopper 8 stops operating.

Therefore, in the conventional device shown in FIG.
As is clear from the figure, when the brake is off, the armature current is always cut off by the switch 5, and the frequency of breakage and breakage at a current close to the rated current value of the switch 5 is clear. The disadvantages are that the cost is high, maintenance and inspection work increases, and the service life cannot be extended.

[Purpose of the invention]

The purpose of the present invention is to reduce the frequency of current flow and breakage near the rated current of the switch due to regenerative braking operation,
It is an object of the present invention to provide a regenerative braking control device for an electric vehicle that can eliminate the drawbacks of the prior art described above.

[Summary of the invention]

In order to achieve this object, the present invention is characterized in that control when the brake is off starts from the stoppage of the operation of the chopper device.

[Embodiments of the invention]

Embodiments of the regenerative braking control device for electric vehicles according to the present invention will be described below with reference to the drawings.

Here, first, before describing embodiments of the present invention, a prior example devised in the process leading to the present invention will be described with reference to FIG.

This prior example has the same main circuit configuration as the conventional example shown in FIG. is given by a signal, but an OFF input for stopping the operation of the gate control section 9 (that is, keeping the chopper 8 off) is given by a signal.

Next, the operation of this prior example will be explained with reference to the timing chart of FIG. Note that the regenerative braking operation is
Needless to say, the same result can be obtained as in the conventional example shown in the figure.

Now, assume that a brake-off command is issued at time t ₀ and a signal is output from the brake command control section 10 . Then, this signal is given to the switch 5 as in the conventional example shown in FIG. 1, and when the switch 5 is turned off, the signal is supplied to the switch 6. However, at this time, since the switch 6 is turned off, no signal is generated in response to the ON input of the gate control section 9.

On the other hand, in this prior example, when the signal is output at time t ₀ , this signal turns OFF of the gate control section 9.
Therefore, the gate control unit 9 stops operating at time t ₀ , and the chopper 8 starts operating after time t ₀ .
It immediately shifts to the off state, and the short circuit including the armature 1 is turned off.

Therefore, the armature current IA decreases at a predetermined time constant after time _t0 , and when the sum of the back electromotive force of the reactor 8 and the generated voltage of the armature 1 becomes slightly higher than the overhead line voltage, Armature current IA becomes zero.

Therefore, let τ ₀ be the time from when the chopper 8 is turned off until the armature current IA becomes zero, and if this time τ ₀ can be made not to be longer than the operation delay time τ ₁ of the switch 5, then at the time t When the switch 5 is turned off at _{step 1} , the armature current IA has become zero, so the switch 5 completes the off operation without cutting off the current.

Therefore, the decay time τ ₀ of the armature current IA at this time is determined by the characteristics of the main motor, the voltage generated by armature 1 during regenerative braking, the inductance and resistance values of the main circuit, etc. Therefore, it is extremely easy to satisfy the above-mentioned condition, that is, τ ₀ < τ _1. Therefore, according to this precedent, the frequency of current breakage due to the switch 5 during regenerative braking can be reduced. It can be reduced to almost zero.

Figure 5 is a diagram showing Figure 4 in more detail. Before time t ₀ , the regenerative braking state is shown, and the armature current IA periodically rises during the ON period of the chopper 8 and falls during the OFF period. This armature current
The magnitude of IA is controlled by the ratio of the on period and off period of chopper 8. Also, in this state, the regenerative current flowing from the pantograph 7 to the overhead wire through the diode 4 is represented by IB, and this current IB
is played only while Chiyotsupa 8 is off.

In addition, at time t ₀ when the brake off command is issued, the Chiyotsupa 8 stops operating (remains off).
However, after this time t ₀ , the armature currents IA and IB have the same value, have a damping characteristic determined by conditions such as the characteristics of the main motor described above, and become zero after time τ ₀ .

Next, examples of the present invention will be described.

FIG. 6 shows an embodiment of the present invention, which is an improved version of the previous example shown in FIG. 3. The difference from the previous example shown in FIG. 3 is that the brake command control unit 10
The signal output from the switch 5 is not supplied to the switch 5,
The point is that it is supplied directly to the switch 6. Note that the signal when the brake is on is omitted.

Therefore, the operation of this embodiment when the brake is off is as shown in FIG. 7, and since the switch 5 does not turn off when the brake is off, the switch 5 turns off only in cases other than regenerative braking. Therefore, the off-operation frequency can be sufficiently reduced.

Furthermore, as is clear from FIG. 5, in this type of regenerative braking control device for an electric vehicle, the regenerative current IB after the chopper 8 operates becomes equal to the armature current IA.

Therefore, in this embodiment as well, if the attenuation time τ ₀ of the armature current IA after time t ₀ is set to be smaller than the off-operation delay time τ ₂ of the switch 6, the switch 6 will be able to turn off the brake. This can prevent the current from turning on and off at times. In this embodiment, when the switch 6 cuts the current, that is, turns off before the regenerative current IB reaches zero, dI/dt decreases due to the inductance included in the circuit such as the reactor 3. As a result, a high voltage is generated, and an overvoltage is applied to the chopper 8. Therefore, in this embodiment, it is necessary to ensure that the above-described condition τ ₀ <τ ₂ is sufficiently maintained.

Next, FIG. 8 shows an example in which a DC shunt motor is used as the main motor and a field chopper control method is applied. In the figure, 11 is a chopper for field control, 12 is a gate control section for field control, and 13 is This is a diode for circulating current. Note that IF represents the field current, and the other details are the same as the embodiment shown in FIG.

The operation of the embodiment shown in FIG. 8 is as follows.

When the brake is on, the brake command control unit 10
→ Signal → Switch 6 → Signal → Gate control section 9,
Control proceeds in the order of the field control gate control section 12, the chopper 8, and the field control chopper 11, and a regenerative braking operation begins. In this state, Chiyotsupa 8
During the ON period, armature current IA flows in the circuit of armature 1 → reactor 3 → chopper 8 → switch 5 → armature 1, and the current value increases during this period.
During the OFF period of Chiyotupa 8, earth → switch 5 →
A regenerative current is generated in the circuit of armature 1 → reactor 3 → diode 4 → pantograph 6 → overhead wire, and the current value decreases during this period.

In addition, in parallel with this, the chopper 11 for field control
The field current IF also operates on and off at a predetermined period.
control. At this time, during the period when the field control chopper 11 is on, the field current IF is controlled by the circuit of the overhead line → pantograph 7 → switch 6 → field winding 2 → field control chopper 11 → ground. As the value increases, during the period when the field control chopper 11 is off, it is attenuated by the circulation circuit of the field winding 2 → diode 13 → field winding 2.

Therefore, according to this embodiment, by controlling the conductivity of both the chopper 8 and the field control chopper 11, the magnitude of the regenerative braking torque by the main motor can be controlled.

Next, when the brake is off, the brake off command signal generated from the brake command control section 10 is supplied to the gate control sections 9 and 12 and the switch 6, and
As in the case of the illustrated embodiment, as shown in FIG.
After time t ₀ when the brake off command is generated, both the armature current IA and the field current IF are attenuated, and the switch 6 is turned off without any current interruption.
No overvoltage occurs.

Therefore, according to this embodiment as well, the frequency of OFF operation of the switch 5 can be reduced, and the frequency of the current ON/OFF operation of the switch 6 can be reduced.

In the case of the embodiment shown in FIG. 8, the field current
The magnitude of IF is usually much smaller than the magnitude of armature current IA, and for this reason,
If the switch 6 interrupts only the field current IF, there is little risk of overvoltage occurring, and the switch 6
It has little effect on the lifespan of the Therefore, in the case of the field chopper control system as in this embodiment, the field control chopper 11 may be configured so as not to be controlled when the brake is off, and even with this, the object of the present invention can be fully achieved. is possible,
Moreover, the configuration can be simplified.

Here, the armature current IA in the above example is
To give an example of the decay time τ ₀ of When set to 500 [A], this armature current IA
The dI/dt of is approximately 25000 [A/S], and τ ₀ ≒20
[mS]. Also, as explained in Figure 5,
After time _t0 , IA=IB.

Therefore, in the embodiment described above, the effects of the present invention can be sufficiently exerted by using a switch 5 or 6 whose off-operation time is 20 [mS] or more.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to reduce the frequency of opening of the switch during regenerative braking control, thereby eliminating the drawbacks of the prior art.
Regenerative braking does not shorten the service life of the switch or increase maintenance, and the circuit for controlling the switch is simplified, requiring fewer auxiliary devices such as relays, which helps reduce costs and improve reliability. A regenerative braking control device for electric vehicles can be easily provided.

[Brief explanation of the drawing]

Fig. 1 is a main circuit wiring diagram showing a conventional example of a regenerative braking control device, Fig. 2 is a timing chart for explaining its operation, Fig. 3 is a main circuit wiring diagram showing a conventional example of a regenerative braking control device, and Fig. 4 is a main circuit wiring diagram showing a conventional example of a regenerative braking control device. 5 and 5 are timing charts for explaining its operation, FIG. 6 is a main circuit connection diagram showing an embodiment of the present invention, FIG. 7 is a timing chart for explaining its operation, and FIG. 8 is a timing chart for explaining its operation. FIG. 3 is a main circuit wiring diagram showing another embodiment. 1... Armature of the main motor, 2... Field winding of the main motor, 3... Reactor, 4... Diode,
5, 6... Switch, 7... Pantograph, 8...
Chotsupa, 9...Gate control unit, 10...Brake command control unit, 11...Field control choppa, 1
2...Gate control section for field control.

Claims (1)

[Claims] 1. The first switch 6, the diode 4, the reactor 3 or the inductance component, the field winding 2 of the traction motor, the armature 1 of the traction motor, and the second switch 5. is connected in series between the pantograph 7 and the ground, and includes a chopper 8, a gate control section 9, and a brake command control section 10, and a second
The series connection part leading to the switch 5 is periodically short-circuited by the chopper 8, so that the diode 4
This is a regenerative braking control device for an electric vehicle in which electric power is regenerated to the overhead wire via a first switch 6 and a first switch 6, and the first switch 6 is controlled based on a brake-on command from a brake command control unit 10. second to be done
It is controlled to be turned on in response to the turning on of the switch 5, generates an on-operation confirmation signal, and supplies it to the gate control section 9, and is directly controlled to be turned off based on a brake-off command from the brake command control section 10. , the gate control unit 9 is controlled by the on operation confirmation signal from the first switch 6 or the brake off command from the brake command control unit 10 to start or stop on/off control of the chopper 8, When a brake off command is generated, the brake command control unit 10 transmits this brake off command to the first switch 6 and the gate control unit 9, excluding the second switch 5.
When a brake-on command is generated, this brake-on command is supplied only to the second switch 5. Regenerative braking control device for electric vehicles. 2 The field winding 2 of the main motor is connected in series between the first switch 6 and the ground via the field control chopper 11, and the field current is controlled. The regenerative braking control device for electric vehicles according to item 1.