JP2693819B2 - Electric car protector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a chopper control type electric vehicle having an overcurrent protection function, and more particularly to a protection device suitable for an electric vehicle such as a battery forklift.

[Conventional technology]

Some vehicles such as automobiles are manufactured and used as electric vehicles using a battery as a power source.
In particular, as a forklift, an electric vehicle known as a so-called battery forklift is practically used.

By the way, in an electric vehicle such as a battery forklift truck, chopper control using a semiconductor switching element is often applied to control the electric motor for propulsion. In this case, the semiconductor used in the chopper control is further used. The application of an overcurrent protection device for protecting an element is common, and an example thereof can be found in Japanese Patent Laid-Open No. 56-59829.

[Problems to be solved by the invention]

The above-mentioned conventional technology does not consider the possibility of malfunction due to noise of the overcurrent protection function, and there is a high possibility that unnecessary operation stop will occur due to malfunction of the protection function during vehicle operation, which is complicated. There were problems such as frequent restart operations and a drop in operating rate.

That is, since such an overcurrent protection function is intended for a semiconductor element, its response time must be set to a considerably short value, for example, about 200 μS, while such a vehicle is used. In such an environment, the noise level of such a pulse width is often high in charge, and as a result, malfunctions due to noise or the like are likely to occur during vehicle operation, resulting in unnecessary operation stop.

The object of the present invention is to ensure that the overcurrent protection function is always activated, on the other hand, the malfunction of the overcurrent protection function due to noise or the like is sufficiently suppressed, and the operation rate of the vehicle is sufficiently increased. It is to provide a protection device for an electric vehicle.

[Means for solving the problem]

In order to achieve the above object, the present invention is such that when the key switch is turned on to start the operation of the vehicle,
The process for detecting a predetermined abnormality is executed a plurality of times in advance at a predetermined time point, and the operation of the vehicle is started after confirming that there is no abnormality in the semiconductor element.

[Action]

It has been confirmed in multiple tests that no abnormalities causing overcurrent have occurred at a given point in time.Therefore, until the test process is executed again, the normal protection function response Sufficient protection is possible without increasing the speed so much, and malfunction of the protection function can be eliminated.

In other words, in this way, if you confirm that there is no abnormality in advance and then start the operation of the vehicle, sufficient protection is possible even if the response speed of the subsequent protection function is slightly low, and as a result, during operation It is possible to sufficiently suppress the malfunction of the protection function due to noise or the like, and it is possible to achieve the purpose.

〔Example〕

Hereinafter, a protection device for an electric vehicle according to the present invention will be described in detail with reference to the illustrated embodiments.

FIG. 1 shows an embodiment of the present invention, for example, an example in which the present invention is applied to a battery forklift or the like, in which 1 is a battery for a power source, 2 is a DC motor for vehicle propulsion, 3 is a current detector, 4 is a forward contactor (electromagnetic contactor), 5 is a reverse contactor,
6 is a plugging diode, 7 is a freewheel diode, 8 is a chopper transistor, 9 is a field coil of the DC motor 2, 10 is a closing detection circuit, 11 is an amplification circuit, 12
Is a control microcomputer (microcomputer computer), 13 is a ROM for storing programs, 14 is a forward detection circuit, 15 is a reverse detection circuit, 16 is a forward switch, 17 is a reverse switch, 18 is a key switch, 19 is a power circuit Is.

As the DC motor 2, for example, one having a capacity of several kilowatts to tens of kilowatts is used, and accordingly, as the battery 1 for power supply, a battery having a capacity of tens of volts and hundreds of ampere hours is used.

The current detector 3 is provided at the time of control of the hopper and at the time of abnormality detection processing.
It functions to detect the current of the DC motor 3 and input it to the microcomputer 12.

The two contactors 4 and 5 each have an a contact (normally open contact) and a b contact (normally closed contact), and in the steady state,
Only one of them is always operated by the microcomputer 12. Therefore, when the forward contactor 4 is operated by the microcomputer 12, the contact is switched to the a contact side as shown in the figure to be in the forward state. On the other hand, when the reverse contactor 5 is operated, the contact is not shown. On the contrary, the contact is closed to the a-contact side, and the direction of the current flowing through the field coil 9 is reversed, and the vehicle is in the reverse drive state.

The plaking diode 6 is provided for forming a current path when the DC motor 2 is plugged, and is connected in parallel with the DC motor 2 in reverse polarity.

Note that this plugging control is so-called anti-phase braking control, and when the vehicle is braked or when the vehicle is braked and stopped, the DC motor 2 has a rotation direction opposite to that direction. It is the control to generate the torque in the direction.

The freewheel diode 7 functions to form a current path when the DC motor 2 is controlled in conduction ratio by the transistor 8.

The transistor 8 operates as a switching element for so-called chopper control, and is on / off controlled from the microcomputer 12 via the amplifier circuit 11. As described above, it functions to change the conduction ratio of the DC motor 2 and control the speed. To do.

The closing detection circuit 10 has a voltage detection function, and detects the application of the power supply voltage by the operation of any of the contactors 4 and 5 and inputs it to the microcomputer 12.

Although not shown, the forward switch 16 and the reverse switch 17 are both operated by the operation of the control operation handle of the vehicle, and when a forward operation command and a reverse operation command of the electric vehicle are respectively issued, the forward movement detection circuit 14 is operated. And reverse detection circuit
It functions to input to the microcomputer 12 via 15.

The key switch 18 is the same as that in a well-known automobile, and operates by operating a predetermined key, and a power supply voltage is applied to a predetermined portion including the microcomputer 12 via a power supply circuit 19 so that an electric vehicle To enable the operation of.

Therefore, in the electric vehicle according to this embodiment, control as a normal battery forklift is performed by the microcomputer 12, and according to the operation of the forward switch 16 and the reverse switch 17, the forward contactor 4 and the reverse contactor 5 are respectively operated.
Selection control and subsequent ON / OFF conduction ratio control of the transistor 8 are performed, and forward / reverse switching of the vehicle and traveling speed and braking are controlled.

By the way, in this embodiment, in addition to the programs required for the above control, the ROM 13 is made to execute the processing shown in FIGS. 2, 3, 4 and 5 by the microcomputer 12. A program for doing so is stored, whereby the operation described below is performed. This point will be described in detail below. In this embodiment, the target of the overcurrent protection is the short circuit abnormality of the plugging diode 6 and the freewheel diode 7. Therefore, the following description will be made on the premise of this, but of course, the present invention is not limited to this. It is not something that will be done.

First, in the microcomputer 12, the key switch 18 is turned on,
When the operating voltage Vcc is applied from the power supply circuit 19, this causes the three types of program P as shown in FIG.
1, P2, P3 are executed sequentially.

In this way, when the program P1 is executed now, first, as shown in FIG. 3, the short flag FLAG preset in the process 100 is checked, and the short flag FLAG is checked.
When FLAG is 1, processing 110 and processing 111 are executed, and the forward contactor 4 and the reverse contactor 5 respectively.
After performing the process of releasing (turning off)
Then, after the processing for setting the input flag FLAG which is also separately set to 0 is executed, the processing by the program P1 is ended. Here, the short flag FLAG is set to 1 when it is determined that the above-described short circuit of the diode has been detected in a manner that causes the short circuit, and although not described here, as the initial processing, first, The reset flag FLAG is reset to 0, and the closing flag FLAG is a flag indicating that one of the contactors 4 and 5 is turned on.

On the other hand, in processing 100, at this time, the short flag F is still
When it is determined that the LAG is not standing, thereafter, first, in step 120, it is determined whether or not the forward movement command is issued, based on the signal fetched from the forward movement detection circuit 14, and the forward movement is instructed here. If judged, continue processing
121 and processing 122 are executed, first the forward contactor 4 is turned on (ON), and then the reverse contactor 5 is opened. Then, in the process 120, when it is determined that the forward command has not been issued yet, it is determined whether or not the backward command is subsequently issued in the process 130, and it is determined that it has been performed. At times, processing 131 and processing 132 are further executed, and this time, the opening of the forward contactor 4 and the insertion of the reverse contactor 5 are executed.

On the other hand, when the result of the process 130 is NO, the processes 110 and 111 are executed to open both the forward contactor 4 and the reverse contactor 5.

After the processing 122 and the processing 132, the processing proceeds to the processing 140, in which the signal from the closing detection circuit 10 is checked to determine whether or not the processing is completed, and the processing 150 and the processing 1 are performed according to the determination result.
Execute one of 60 to set the input flag FLAG,
It does a reset.

By executing this program P1, it is possible to obtain a process of waiting for either the forward contactor 4 or the reverse contactor 5 to be operated after the key switch 18 is operated, and the result is the closing flag FLAG. Will be stored by setting and resetting.

Next, proceeding to the processing of the program P2 in FIG. 4, here it is first determined in processing 200 whether or not the above-mentioned closing flag FLAG is set, and the result is NO, that is, the contactor is still being turned on. If not, processing 201 and processing 202 are executed to clear the motor duty (chopper conduction ratio) set, thereby keeping the transistor 8 off, and ending the processing of this program P1.

On the other hand, if it is determined that the result of the process 200 is the closing flag FLAG = 0, then in process 210, the data of the predetermined detection counter, which is also set in advance, is checked, and the numerical value thereof becomes the predetermined value DI. If it is determined that it is over, and it is determined that the determination result is YES here, the process 2
11 is executed, the detection FLAG reset processing is executed here, and then the processing ends. As the predetermined value DI in this process 210, for example, a numerical value of 3 is selected.

Then, when the result is determined to be NO in the above process 210, the processes 212 to 215 are sequentially executed, and the process of setting the detection FLAG and the flow rate to the predetermined value K1, After the ON / OFF operation processing at a predetermined conduction ratio of the transistor 8 and the detection counter increment processing (processing for incrementing the count value by 1) are sequentially executed, the processing by this program ends. In addition,
Since the conduction ratio set in the processing 213 at this time is for making a current flow through the DC motor 2 on a trial basis to determine whether or not there is an abnormality, even when the above-mentioned diode short circuit occurs. However, it may be set to a value such that the current is as small as possible within the range in which it can be reliably detected. For example, the conduction ratio = K1 = 30%.

Therefore, when this program P2 is executed, there are a waiting state for processing due to the insertion flag not being set yet, and a state in which the detection flag is reset when the count value of the detection counter is 3 or less. , And whether to proceed to the process of testing whether there is a diode short circuit abnormality 3
Then, the process is terminated in the seed state, and then the process by the program P3 shown in FIG. 5 is proceeded to.

When the processing by this program is started, it is determined by the processing 300 whether or not the detection flag FLAG is set, and when it is determined that the detection flag = 0, the processing is ended without doing anything here, Program P2 in Figure 3
Return to processing by.

On the other hand, if the determination in process 300 is that the detection flag = 1, then in process 310, the current of the DC motor 2 is checked to determine whether it is equal to or greater than a predetermined value ia.
When it is determined to be S, the process proceeds to process 311, where the process of resetting the short flag FLAG is executed and then the process ends, but the determination in process 310 is NO, that is, at this time, the current detector 3 determines When it is determined that the detected current value of the DC motor 2 has not reached the predetermined value ia,
This time, in process 312, the protection counter is incremented (count value is incremented by 1), and then process 320 is performed.
It is determined whether the data of this protection counter is equal to or greater than a predetermined value (ID-1), and the result is NO, that is, the count value of the protection counter has not reached the predetermined value (ID-1). When it is determined that the short flag FLAG is not reset, the short flag FLAG is reset by executing the process 311. In addition, as the above predetermined value ia,
For example, when the rated current of the DC motor 2 is IL, ia =
It should be selected to be about IL × 0.3.

Then, in the above process 320, the result is YES, that is, the data of the protection counter has already reached the predetermined value (ID-1) at this time.
When it is determined that the flag has reached the value, first, the detection flag FLAG is reset in the process 321, and subsequently, the short flag FLAG is set in the process 322 and the process ends.

Next, the operation obtained by executing the processing by these programs will be described in more detail.

As a result of the processing by the program P1, when either the forward contactor 4 or the backward contactor 5 is closed by operating the forward switch 16 or the reverse switch 17, the processing proceeds to the program P2, and the predetermined operation of the transistor 8 is performed. On / off control is performed based on the conduction ratio, and as a result, a current having a predetermined value is passed through the DC motor 2.

At this time, if there is no abnormality in the plugging diode 6 or the freewheel diode 7, the DC motor 2
A current having a predetermined value due to the above-mentioned predetermined flow rate flows through the device, and as a result, the current value becomes at least the above-mentioned predetermined value ia, and as a result, the short flag is not set.

Now, assuming that a short circuit abnormality has occurred in any of the diodes, when the transistor 8 is on / off controlled by the above-mentioned predetermined conduction ratio, a part of the current flowing in the DC motor 2 or Since all of them are shunted to the short-circuited diode, the current value detected by the current detection circuit 3 does not reach the above-mentioned predetermined value ia, and as a result, the determination result in the process 310 is N.
It becomes O, which is continuously repeated at least three times by the processing using the detection counter and the protection counter, whereby the processing 322 is first executed here and the short flag is set.

Thus, when the short flag is set, the abnormality is displayed by another process (not shown), and the process based on the determination result of the process 100 of the program P1 is performed by the process 110,
In the direction to proceed to the process 111, as a result, both the forward contactor 4 and the reverse contactor 5 are opened. Therefore, according to this embodiment, when there is a fear of overcurrent, an abnormality is caused. Not only is it displayed, but the vehicle is stopped, so a protective operation can be reliably obtained.

In the example of the abnormality, the short-circuit abnormality of the plugging diode and the freewheel diode is the target of the protection function activation, but it goes without saying that the present invention is not limited to this and can be implemented, for example, in the program P3. If the determination of the DC motor current is also made with respect to the upper limit thereof, it is possible to detect a short circuit abnormality in the path between the DC motor 2 and the field coil 9, and an overcurrent protection function for this can be provided. Can also be held.

Further, in the above-described embodiment, when the key switch is operated and the vehicle is about to start operating, the processing by the program of FIG. 2 and after is executed, but instead of this, It may be executed at any time, for example, after the vehicle has been stopped for a predetermined time or more and then every time the vehicle starts operating again.

Furthermore, how many times the above-described processing for detecting an abnormality has become abnormal, and whether to finally determine that an abnormality has occurred is not limited to three times as in the above embodiment, It goes without saying that this can also be set arbitrarily.

〔The invention's effect〕

According to the present invention, at a predetermined arbitrary time such as the start of operation of a vehicle, a predetermined predetermined abnormality detection is automatically performed within an extremely short time until the vehicle actually starts traveling. Since it is executed, even if the abnormality detection process for the subsequent protection function is performed with a relatively long response time, it is possible to sufficiently protect the device, so noise such as during vehicle operation It is possible to sufficiently suppress malfunction due to
It is possible to greatly improve the operating rate and operability of electric vehicles such as battery forklifts.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a protection device for an electric vehicle according to the present invention, FIG. 2 is a program configuration diagram for executing a protection operation process, FIG. 3, FIG. 4 and FIG. It is a detailed explanatory view of each processing program. 1 ... Battery, 2 ... DC motor for vehicle propulsion, 3 ...
… Current detector, 4 …… Forward contactor, 5 …… Reverse contactor, 6 …… Plugging diode, 7 …… Freewheel diode, 8 …… Chopper transistor, 9 …… Field coil, 10 …… Closed Detection circuit, 11 ... Amplification circuit, 12 ... Control microcomputer, 14 ... Forward detection circuit, 15 ... Reverse detection circuit, 16 ... Forward switch, 17 ...
… Reverse switch, 18 …… Key switch, 19 …… Power supply circuit.

Claims (4)

(57) [Claims] 1. An electric vehicle having a chopper control circuit using a semiconductor switching element and an overcurrent protection function, wherein the electric current of a propulsion electric motor is controlled by the chopper control circuit, wherein the propulsion is performed via the chopper control circuit. Flow control means for passing a current of a predetermined value for testing through the electric motor, abnormality detection means for detecting an abnormality based on the current flow state by the flow control means, and these flow control means and abnormality An operation control unit that sequentially operates the detection unit at least twice in a predetermined cycle, and a determination processing unit that sets the abnormality detection result to true on the condition that the detection result by the abnormality detection unit indicates an abnormality at least twice in succession. And a test start processing means for activating the operation control means at a predetermined time, and activating the overcurrent protection function according to the judgment result of the judgment processing means. Electric train protection device, characterized in that the sea urchin configuration. 2. The electric vehicle protection device according to claim 1, wherein the predetermined time point is a predetermined processing operation time for enabling the vehicle to run. 3. The protection device for an electric vehicle according to claim 1, wherein the overcurrent protection function is configured so as to give a stoppage of all operations of the vehicle as a result of its operation. 4. The electric vehicle according to claim 1, comprising a vehicle braking system based on reverse torque control of a propulsion electric motor, and the overcurrent protection function prevents overcurrent due to a short circuit of a plugging diode for the reverse torque control. A protection device for an electric vehicle, which is configured to operate as an object.