JP4000938B2 - Control method of electric vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for controlling an electric vehicle. For example, it is applied to an electric vehicle, a forklift and the like.
[0002]
[Prior art]
When driving an electric vehicle, generally, an output voltage, current, or direction is calculated by a combination of external input signals such as an accelerator or a direction (DS), and is driven and controlled by outputting them.
[0003]
When either one of the external input signals is OFF, for example, when the direction is neutral or when the accelerator is released, the output is turned OFF, and in general, it is in a free run (non-control state).
[0004]
Depending on the system, an electric brake (such as regenerative control or plugging) may be generated by detecting the traveling speed when the external signal is OFF.
As a special use example of the electric vehicle, there is a case of towing other vehicles, loading carts, etc. (towed object).
[0005]
[Problems to be solved by the invention]
When towing a towed object with an electric vehicle, the towed object and the electric wheel are fixed with a rope chain.
If the vehicle starts slowly and accelerates from a fully stretched rope chain, there is no problem, but the towed object is heavy enough that it cannot be pulled at the maximum torque that the vehicle can generate (motor stall), and the rope・ When the chain is slack, that is, when the electric vehicle is accelerated from the no load state to the maximum, the vehicle stops immediately after the rope chain is stretched.
[0006]
Immediately after the rope chain is stretched, a sudden load torque is applied to the vehicle, so the vehicle speed changes instantaneously.
The speed calculation (speed calculation cycle: 2 msec, vehicle speed detection pulse number: 82 pulses / motor rotation) is delayed with respect to the change in the vehicle speed, so that the actual speed and the control calculation speed are deviated. Maximum torque cannot be generated due to mismatch of “slip frequency”.
[0007]
The following phenomenon occurs at the moment when the maximum torque cannot be generated.
1. The vehicle is greatly bounced back to the towed object, and the rope chain is slackened again.
2. Since the vehicle is in an unloaded state, it tries to tow again.
The above steps 1 and 2 are repeated, and the vehicle vibrates greatly.
Since the number of detected vehicle speed pulses is as small as 32 pulses / motor rotation, there is no pulse input at low speeds, and the speed calculation becomes unstable, which is also a factor of the above phenomenon.
[0008]
[Means for Solving the Problems]
Control method for an electric vehicle according to claim 1 of the present invention for solving the above described problems is the control method of an electric vehicle for towing a towed object, when the rapid speed change of the vehicle in the deceleration direction is detect the output torque , The torque characteristics are mapped so that the output torque becomes smaller than the previous time, and the towed object is pulled again.
[0009]
The method for controlling an electric vehicle according to a second aspect of the present invention for solving the above-described problem is the method for controlling an electric vehicle according to the first aspect, wherein the sudden speed change is detected when the maximum torque of the motor is output in a state where the vehicle is floating It is a time when a change in speed exceeding the maximum acceleration is detected.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.
FIG. 1 shows a method for controlling an electric vehicle according to an embodiment of the present invention.
In the present embodiment, the following improvements are added so that the vibration of the vehicle can be suppressed when the towed object is pulled by a rope chain with an electric vehicle.
[0011]
First, the vehicle is driven, and an abrupt change (mainly in the deceleration direction) of the vehicle speed when the vehicle is bounced back is detected (step S1).
Next, when an abrupt speed change is detected, it is determined that a sufficiently heavy towed object is to be pulled (step S2), and the output torque is decreased once (step S3).
Then, the time from when the vehicle is bounced to when it is pulled again is measured, and the torque characteristics are mapped so that the output torque when the vehicle bounced back again is smaller than the previous time (step S4).
[0012]
For example, as shown in FIG. 2, the output torque is set to 100% until a sudden speed change is detected, and after the rapid speed change is detected, the output torque is temporarily reduced to 50%.
Then, the output torque is maintained at 50% for a certain time (= Ta).
After a certain time elapses, the output torque is gradually increased, and when the certain time (= Tb) elapses, the output torque is set to 100%.
That is, the predetermined time (= Ta, Tb) is determined so as to be pulled again until the output torque increases from 50% to 100%.
[0013]
In this way, when the rope chain is tensioned again, the output torque is smaller than the previous time, so that the amount of rebound is small.
At this time, since an abrupt change in vehicle speed has already been detected, the output torque is output again according to the mapping.
[0014]
As described above, in this embodiment, the vehicle bouncing rebound vibration during towing is large at the first time but converges at the second to third times and can be stably towed.
That is, in the prior art, even when towing again after being bounced back to the towed object side, it was towed at the maximum torque, and thus repeated large vibrations. Since the towing is performed with a smaller torque, the vibration gradually converges and can be stably pulled.
In the present embodiment, and when detecting a rapid speed change is when it detects a maximum acceleration or speed change at the time of maximum motor torque output in vehicle floated state with saying Umono.
[0015]
【The invention's effect】
As described above based on the embodiments, according to the present invention, in the electric vehicle that pulls the towed object, when the load is suddenly changed, that is, when the object is towed again after being rebounded to the towed object side. Therefore, the vibration is converged and stable traction operation is possible.
[Brief description of the drawings]
FIG. 1 is a flowchart showing a method for controlling an electric vehicle according to an embodiment of the present invention.
FIG. 2 is a graph showing torque characteristic mapping.
[Explanation of symbols]
Ta, Tb fixed time

Claims (2)

The control method of an electric vehicle for towing a towed object, when the rapid speed change of the vehicle in the deceleration direction is detect once lowers the output torque, to map the torque characteristics so that the output torque becomes smaller than the previous And then towing the towed object again. 2. The electric vehicle according to claim 1, wherein the time when the abrupt speed change is detected is a time when a speed change equal to or greater than a maximum acceleration at the time of motor maximum torque output in a state where the vehicle is floated is detected. Control method.

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