JPS601801B2 - electric car control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for an electric vehicle such as a battery forklift, and more particularly to a device for controlling plugging, that is, reverse braking of an electric motor.

In order to perform a special operation in which the battery forklift frequently switches between forward and backward travel, an electric brake is applied when the forward/reverse switching contactor is switched while the vehicle is moving, and after the vehicle has stopped, the vehicle is controlled to continue powering in the opposite direction. I am doing it.

This is called plugging, and it involves connecting the coil or armature of the series-wound motor in the opposite direction while the vehicle is running, applying voltage, and using the resulting reverse torque as braking force. If a thyristor chopper is used to control the motor, it is easy to control the motor current so that the reverse torque is at an appropriate value.

If it is necessary to change the motor current value during power running and during plugging in order to set the brake torque at an appropriate value during plugging, it is necessary to distinguish between the power running state and the plugging state and change the Chobba control command. . For this reason, the slave has been detecting the plugging state using a method as shown in FIG. 1, for example.

In other words, when moving forward, the forward/backward switching contactors SW and SW
2 and put them in the positions shown respectively.

Here, when the conduction rate Q of the chopper CH is increased, the current from the battery D changes from the contact A of the contactor SW, to the field F,
It flows through contact B of contactor SW2 → armature M → shunt SH → chopper CH, the motor rotates, and the battery forklift moves forward. freewheel diode FD
This is for circulating the motor current during the off period.

The conduction rate Q of the chopper CH is the command current l given from the accelerator circuit AC by pressing the accelerator pedal AP.
s and the feedback current lf obtained from the shunt SH
This is determined by the gate control circuit G so that there is no difference between the two. In other words, the motor current is constant current controlled to a value determined by the command current ls. Next, when both the forward/reverse switching contactors SW, SW2 are switched to the side opposite to that shown in the drawing during forward power running, a plugging state is entered.

At this time, the current from battery ○ will pass through contact A of contactor SW2 → field F → contact B of contactor SW → armature M → shunt SH → chopper CH, but it will flow through field F. Since the direction of the current is opposite to that during forward power running, the torque generated in the motor is in the opposite direction. However, since the motor continues to rotate in the forward direction, this reverse torque acts as a braking force. Also, although the direction of rotation of the motor remains the same, only the direction of the field current has reversed, so the electromotive force that was previously generated in the armature M is reduced to the point indicated by the arrow P.
The direction was the opposite arrow Q in the plugged state.
direction. Therefore, since the motor is in a state where it is very easy for current to flow, when constant current control is performed, the conduction rate is automatically controlled to a small value. When measured in an actual battery forklift, the conduction rate was about a few percent, but during power running, even when the motor is locked, the conduction rate reaches a value of 20% or more at the same command current ls. When the chopper is turned off, due to the starting force generated in the armature M in the direction of arrow Q, the following changes occur: armature M → shunt SH → freewheel diode FD → contact A of contactor SW2 →
A current flows in the path from the field F to the contact B of the contactor SW, and this serves as an exciting current for the field F to maintain the electromotive force of the armature M, so that the outside of the motor operates as a generator. On the other hand, due to the electromotive force generated in armature M in the direction of arrow Q, armature M → shunt S
A current also flows through the path of the H→plugging state diode PD, and energy is consumed as heat due to the resistance of this circuit. That is, while the chopper is off, this circuit operates as a power generation control circuit. In this way, while the chopper is being guided, the brake is applied by reverse torque, and while the chopper is off, the brake is applied by dynamic braking, and both actions are collectively referred to as plugging. Now, it can be seen that in order to adjust the braking force in the plugging state, the motor current value can be controlled at a constant current to a different value.

In other words, if the command current ls is reduced to control the motor current to a small value, the reverse torque when the chopper is activated becomes smaller, and the firing fin control current flow and its time when the chopper is turned off are also reduced, which reduces the braking force. becomes smaller. Conversely, if the motor current is controlled at a constant current to a large value, the braking force will increase. Generally, if the motor current setting value during plugging is set to the same value as during power running, the braking force will be too strong, so reducing the motor current setting value by decreasing the command current ls only during plugging will result in a moderate ride comfort. braking force can be obtained.

Therefore, the command current ls is reduced by detecting the plugging state. There are various ways to detect the plugging state, including detecting the direction of the electromotive force generated by the armature, detecting the current flowing through the plugging diode PD, and chopper flow during power running and plugging. A common method is to take advantage of the fact that there is a large difference in flow rates. Here, as an example, the plugging state is detected by the conduction rate.
The method shown in No. 0-186616 will be explained.

As mentioned above, during power running, the conduction rate is at least 20% to overcome the running resistance, but during plugging, even if the set value of the motor current is increased to strengthen the braking force, the direction of the electromotive force will change. Since it is in the direction of arrow Q, the thin flow rate is only about 5% at most.

To explain in more detail, during power running, the flow rate is more than 20% even when the accelerator pedal AP is depressed and the vehicle is barely moving, but when plugging, even when the accelerator pedal AP is fully depressed, the far flow rate is is less than 5%. If the amount of accelerator depression is reduced during coasting, the flow rate will be 5% or less, but this differs from when plugging in that if the amount of accelerator depression is increased, the flow rate will be increased. Therefore, if a circuit is provided that operates only when the conduction rate is small and the amount of accelerator depression is large, it will be possible to detect the plugging state.

The plugging control circuit based on this principle is composed of a conduction rate detection circuit DD and a command current limiter L.

That is, when the conduction rate Q of the chopper CH is small, the conduction rate detection circuit DD outputs an output, and the command current limiter L limits the command current ls so that it does not exceed a predetermined value. Of course, even when not plugging, the command current limiter L operates if the lean flow rate is small, but in such a case, the accelerator adjacent amount is originally small, so the command current ls is less than the IJ-Mituta limit value. is not affected in any way. During plugging, the command current ls is reduced by the limiting action of the limiter to such an extent that an excessive braking force can be obtained. When the accelerator depression amount is increased during power running, the conduction rate Q increases, so the plugging control circuit does not operate and the command current ls is not lowered. By the way, it has been found that such a plugging detection method has problems in the following cases.

In other words, in the case of a forklift that runs only on a horizontal road surface, there is no problem even if the braking state is detected using the method shown in Figure 1 or the method described above, and the command current ls is adjusted to provide an appropriate braking force. do not have. However, in the case of a forklift that runs on a slope, the following problems occur when starting on a slope. In the middle of a slope, the driver applied the foot-operated brake to stop the vehicle.

The forward/reverse switching contactors SW, SW2 are respectively inserted in the uphill direction.・To start the forklift, the driver releases the foot brake and presses the accelerator pedal A.
P is pressed, but it takes some time to change the foot, and the accelerator circuit AC usually has a time constant for soft start, so the command current ls increases slowly, so the powering torque increases. In front of it, the car body starts to go down the slope due to gravity. The state at this time is the contactors SW,,SW
In case 2, the wheels rotate in the opposite direction even though the vehicle is being turned in the uphill direction, so from an electrical point of view there is no difference from the plugging state. Therefore, in the method shown in FIG. 1 or the various plugging state detection methods described above, it is determined that plugging is occurring and the command current ls is lowered, resulting in a decrease in braking force and the vehicle body moving further down the slope. This method of detecting the plugging state based on the electrical state of the motor circuit operates even when the vehicle is started on a slope, promoting the descent of the vehicle body, which is extremely dangerous in terms of driving operation. SUMMARY OF THE INVENTION An object of the present invention is to provide an electric vehicle control device that eliminates the above-mentioned drawbacks of the prior art and allows a smooth start without weakening the braking force when starting on a slope.

To achieve this objective, the present invention detects the operating order of the front-back switching contactor, and when the operating order is from the forward side to the neutral position and back to the forward side, or from the reverse side to the neutral position and then back to the reverse side. is provided with means for determining the second plugging state when the first plugging state is from the forward side to the reverse side or from the reverse side to the forward side, and the set value of the command current in the first plugging state is set to the second plugging state. The command current is set to be larger than the value set in the plugging state. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 2 is an electric circuit diagram for controlling the plugging operation of a battery forklift according to an embodiment of the present invention. This diagram differs from Figure 1 in that the forward/reverse switching contactor operating order detection device RD and switch element S
has been added, and everything else is the same as in FIG. 1, so the same reference numerals are given. FIG. 8 is a detailed wiring diagram of the operation order detection device RD of the forward and backward sliding sliding contactor.

In this figure, T is connected to the positive polarity side of battery D in FIG. 2, and T' is connected to the negative polarity side of battery D, respectively. CFC is the excitation coil of the forward/backward switching contactor SW, C
RC is an excitation coil of the forward/reverse switching contactor SW2. The forward and backward movement cutting bar installed in the driver's seat of a forklift (
(not shown) is connected to the SF side when the forward/reverse switching is performed and the bar is set in the forward direction, and is connected to the SR side when the forward/reverse switching is performed and the bar is set in the reverse direction.
When the bar is not inserted in either direction when moving forward or backward, that is, in the neutral position, it is not connected to either the SF side or the SR side (
connection shown in Figure 3). When the switch SW3 interlocked with the forward/reverse switching lever is connected to the SF side, a voltage is applied to the excitation coil CFC, and the forward/reverse switching rear contactor SW is connected to the A side, resulting in forward power running. When the switch SW3 interlocked with the forward/reverse switching lever is connected to the SR side, a voltage is applied to the excitation coil CRC, and the forward/reverse switching contactor SW2 is connected to the A side, resulting in reverse power running. If the switch SW3 is not connected to the SF side or the SR side, the forward/reverse switching contactors SW and SW2 are both connected to the B side, and the voltage of the battery D is not applied to the motor M and the chopper CH. . Further, FIG. 4 is an explanatory diagram of the operation of FIG. 3. Forward/forward switching lever (not shown)
The signal waveforms are shown when the switch SW3 is operated and the switch SW3 moves in conjunction with the switch SW3, and the signal waveforms correspond to the symbols in FIG. That is, by operating the switch SW3, the voltage applied to the excitation coil CFC for forward power running or the excitation coil CRC for reverse power running is set to T2 or T in FIG.
Case 3 is taken as an example. In addition, when switching between forward power running and reverse power running, the switch SW3 shown in Fig. 3 must pass through the neutral position where it is not connected to either the SF side or the SR side.
During that period, the operation of the chopper CH shown in FIG. 2 is stopped. The period in which both L and T3 in FIG. 4 do not output (the period in which T9 outputs) indicates the neutral position. First, the operation of power running eplugging in substantially flat running will be explained with reference to FIG. 4. Note that before time t,
The switch SW3 is in the neutral position SN, and the power is turned on to the control device to rotate the forklift. At time t, when the switch SW3 is set to the SF side and the forward excitation coil CFC is energized to perform forward power running,
The output T4 of the inverter INF becomes zero, but the output of the inverter INR remains at one.

Note that the inverters INF and INR are used to shape and extract the voltages of the forward and backward excitation coils CFC and CRC. As shown in FIG. 5, the flip-flop FF is of a set-reset type having a set terminal ST and an IJ set terminal RT. From this, even if the output circle becomes zero, the flip-flop FF will maintain its previous state and output t,
There is no change in T'6. At this time, the output T9 of the AND gate AG becomes zero, and the transistor TR becomes non-conductive. When the flip-flop does not operate, no gate signal is applied to the thyristor Th, so it remains non-conductive and the outputs T, . is zero. That is, in power running when plugging is not used, not only the plugging control circuit shown in FIG. 2 does not operate, but also the switch element S does not close, so the command current ls is not lowered. At time t2, the switch SW3 is switched to the SR side by plugging in order to switch to reverse power running.

From time t2 to t3, the circuit is in the neutral position, and even if the inverter INF outputs an output T4 from time t2 to t3, the flip-flop eave F remains in its previous state. AND gate AG outputs output T9 and makes transistor TR conductive (T,. is zero)
However, the output T,. of the operation order detection device RD remains zero. When the backward excitation coil CRC is excited at time t3, the output T5 of the inverter INR becomes zero.
Therefore, flip-flop FF is inverted, T6 becomes zero,
T'6 becomes 1, and at the rising edge, 7 is given to the gate of thyristor Th as a signal differentiated by capacitor C, so thyristor Th becomes conductive.On the other hand, AND gate AG becomes zero, so
The output T9 becomes zero, and the poisoning and killing pseudobuki soso carp is generated, and the outputs T, . issue.

Output T, . Since the switch element S shown in FIG. 2 is closed by this, the command current ls can be lowered depending on the plugging detection device during plugging. When plugging is completed, the plugging control circuit shown in FIG. 2 does not lower the command current ls, so even if the switch element S is closed, the command current for reverse power running is not lowered. Next, switch SW3 is switched to the SF side, and the reverse power running is changed to forward power running by bragging (from time t4 to time t6).

When the voltage of the backward excitation coil CRC becomes zero at time t4,
Flip-flop FF does not operate, but since the output T9 of AND gate AG becomes 1, transistor TR becomes conductive. Therefore, the current that has been flowing through the thyristor Th now flows through the transistor TR, so the current flowing through the thyristor Th
The current becomes zero, and the thyristor Th becomes non-conductive. As a result, in the neutral state, the outputs T, . becomes zero, and the switch element S in FIG. 2 is opened. When the forward excitation coil CFC is excited at time t5, the output T4 of the isoverter F becomes 0, the flip-flop FF is inverted, the output T6 becomes 1, and the output T'6 becomes 0. The rising edge of the output T6 is differentiated by a capacitor C and a gate signal is given to the thyristor Th. Since the output L of the inverter INF is zero, the output T9 of the AND gate AG is zero, and the transistor TR is non-conductive, so the thyristor Th becomes conductive and a voltage drop occurs across the resistor R3. That is, since the operation order detection device RD outputs an output,
The switch element S in FIG. 2 is closed, and during plugging, the command current ls is lowered by the plugging control circuit.
When plugging is completed, even if the switch element S is closed, the plugging control circuit no longer lowers the command current ls, so that the command current ls is applied as is for the next forward power running. As described above, in the circuit shown in FIG. 3, the forward excitation coil CFC is excited, and then the reverse excitation coil CRC is excited.
The operation order detection device RD outputs an output and the switch element S is closed only when the is excited or vice versa. Therefore, if a plugging state occurs at that time, the command current is changed by the plugging control circuit shown in Fig. 2. ls will be lowered.

As shown from time t6 to time t, o, when the same excitation coil (forward excitation coil in the figure) is continuously excited, the thyristor Th does not fire, so the operation order detection device RD does not output an output. . In other words, since the switch element S in FIG.
Even if an operation is performed to lower s, the command current ls cannot be lowered. This is important when starting on a slope, which will be explained next. Next, a description will be given of when the vehicle starts on a slope.

Slope starting generally refers to driving up a slope, stopping once on the way, and then continuing up the slope. Therefore, the switch SW3, which is linked to the forward/reverse steering bar (not shown), is closed on the same side when initially climbing a slope as it is closed when starting from the middle of a slope. That is, the same excitation coil that turns on the forward/reverse switching contactors SW, SW2 is continuously excited. For example, if we take a case in which the vehicle starts climbing a slope by forward power running and then starts midway up the slope by forward power running, the operation in FIG. 3 is in the state tw from time t7 in FIG. 4.
According to this example, starting from the middle of a slope starts at time t9. As is clear from Fig. 4, even if the same excitation coil is continuously excited, the flip-flop FF
remains in its previous state, and no gate signal is given to the thyristor Th, so the outputs of the operation order detection device RD, . remains zero, and the switch element S in FIG. 2 is not closed. Therefore, if we consider the case where a command current is applied after the body of the forklift starts descending the slope due to gravity when starting on a slope, the electric motor will be in the same state as plugging from an electrical point of view. In this state, the plugging control circuit shown in FIG. 2 works to lower the command current ls, but since the switch element S is not closed as described above, the command current ls is not actually lowered. This means that by applying a larger command current ls than during normal plugging operation, the braking force is not reduced, so it is possible to apply a strong braking force to the vehicle body that has begun to descend due to gravity, stopping it from sliding down the slope. It becomes possible to start the vehicle. According to this embodiment, since the command current is not lowered by plugging due to slipping when starting on a slope, a strong plugging braking force can be obtained, and slipping can be quickly stopped and smooth starting on a slope can be performed.

As explained above, according to the present invention, the operating order of the forward/reverse switching contactor is detected, and the operating order is changed from the forward side to the neutral position and then back to the forward side, or from the reverse side to the neutral position and then back to the reverse side. , the first plugging state is determined, and the second plugging state is determined from the forward side to the reverse side or from the reverse side to the forward side. Since the set value of the command current is set higher than that in the plugging state, a strong braking force can be obtained in the first plugging state, and it is possible to quickly stop the vehicle body from sliding down and start smoothly on a slope. can.

[Brief explanation of drawings]

Fig. 1 is an electric circuit diagram for controlling the plugging operation of a conventional battery forklift, and Fig. 2 is an electric circuit diagram for controlling the plugging operation of a battery forklift according to an embodiment of the present invention. Figure 3 is a detailed wiring diagram of the operation order detection device shown in Figure 2,
4 is an explanatory diagram of the operation of FIG. 3, and FIG. 5 is a detailed wiring diagram of the flip-flop shown in FIG. 3. D. ．． ．． ．． ．． ．． Battery, CH...Chiyotsupa, M...
Armature of DC motor, F... Field of DC motor, SW, SW2... Forward and backward sliding contactor, FD
...Freewheel diode, PD...
Plugging diode, G... Gate control device, DD... Conductivity detection circuit, L... Command current limiter, RD... Operation sequence detection device, S...
...Switch element, CFC...Forward contactor excitation coil, CRC...Reverse contactor excitation coil. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Scope of Claims] 1. A DC motor for driving an electric vehicle, a chopper for controlling the current of the DC motor, a forward/reverse switching contactor for rotating the DC motor in forward and reverse directions, and an electric motor for the DC motor. In the electric vehicle control device, the electric vehicle control device includes a plugging diode that is connected in parallel to the output terminal and flows a braking current during plugging, and a gate control device that applies a gate signal to the chopper and controls the current of the DC motor according to a command current. The operating order of the forward switching contact part is detected, and when this operating order is from the forward side to the neutral position and then to the forward side again, or from the reverse side to the neutral position and then to the reverse side again, the first plugging state is established, and from the forward side to reverse. means for determining the second plugging state when the change is from the side or reverse side to the forward side;
An electric vehicle control device characterized in that the command current is set to be larger than the set value in the plugging state. 2. The electric vehicle control device according to claim 1, wherein the operating order of the forward/reverse switching contactor is detected by a voltage applied to an excitation coil of the forward/reverse switching contactor.