JPH04210701A - Short circuit detecting method of field weakening contactor for battery drive vehicle - Google Patents

Abstract

PURPOSE:To prevent a regenerative brake system from entering into uncontrollable state by turning an auxiliary exciting transistor ON under a state where each contactor and a regenerative contactor are turned OFF and measuring a voltage to be applied on a chopper driving means at that time. CONSTITUTION:Upon turning a travel lever to a neutral position under halting state of vehicle, a drive contactor 3, a reverse contactor 4, a regenerative contactor 7 and a field weakening contactor 13 are held in OFF state. Subsequently, an auxiliary exciting transistor 9 is turned ON and a sensor 20 detects a voltage Vo to be applied on the transistor 9 under that state. When the field weakening contactor 13 is in short-circuited state due to fusion, for example, the applying voltage is considerably higher than 0 volt. Consequently, a controller 17 decides that the field weakening contactor 13 is short-circuited if the applying voltage Vo, detected through the sensor 20, is not 0 volt but higher than a predetermined level and then prohibits travel control thus maintaining the vehicle in halting state.

Description

[Detailed description of the invention]

[00017

[Industrial Field of Application] The present invention relates to a method for detecting a short circuit in a field-weakening contactor of a battery vehicle that employs field-weakening control to control a driving motor. [0002] Conventionally, a driving motor used in a battery-powered vehicle, such as a DC motor, is rotationally driven by chopper control (for example, as disclosed in Japanese Patent Application Laid-Open No. 2-2'3740).
Publication No. 2). In addition, a field weakening contactor is provided to change the motor characteristics to a low torque, high rotation type, and field weakening control is adopted to change the driving motor to a field weakening state during high speed operation to ensure maximum speed. Furthermore, in battery vehicles, in order to extend the time for battery replacement or charging,
When braking is performed while the vehicle is traveling at a predetermined speed or higher, regenerative braking is performed, and the electric power generated by the travel motor is regenerated to the battery. [0003] FIG. 3 shows a control circuit for a driving motor of a battery vehicle that performs the above-mentioned control. In this circuit, a DC traveling motor M connected to a battery 1 is composed of an armature 2 and a field coil 5 connected between a forward contactor 3 and a reverse contactor 4.
It is operatively connected to driving drive wheels (not shown). The armature 2 is connected to the positive terminal of the battery l via a current sensor 6 and a regeneration contactor 7. Further, a parallel circuit consisting of a bypass contactor 8 and a transistor 9 serving as chopper driving means is connected to the forward contactor 3 and the reverse contactor 4. [0004] A connection point P1 between the regeneration contactor 7 and the positive terminal of the battery 1 and a connection point P2 between the forward contactor 3 and reverse contactor 4 and the armature 2
A series circuit of a pre-excitation transistor 10 and a pre-excitation resistor 11, and an armature diode 12 are connected in parallel between them. Further, a series circuit of a field weakening contactor 13 and a field weakening resistor 14 is connected in parallel with the forward contactor 3 and the backward contactor 4. Furthermore, a regeneration diode 15 is connected between the connection point P3 between the forward contactor 3 and the reverse contactor 4 and the transistor 9 and the positive terminal of the battery 1; A regenerative diode 16 is connected between the connection point P4 and the negative terminal of the battery 1.
are connected to each other. [0005] When traveling forward, as shown in FIG. 3, the forward contactor 3 is turned ON and the regeneration contactor 7 is also turned OFF according to the forward operation of the traveling lever (not shown).
In this state, the transistor 9 is chopper-controlled at a predetermined duty ratio corresponding to the target speed, and the rotation of the traveling motor M is controlled. (When traveling in reverse, the reverse contactor 4 is turned on.) When traveling at high speed, the bypass contactor 8 is kept in the ON state, the full voltage of the battery 1 is applied to the traveling motor M, and the transistor 9 is turned off.
state. When the field weakening contactor 13 is turned on during high rotation of the traveling motor M, a part of the field current supplied to the field coil 5 is transferred to the field weakening resistor 14.
The running motor M is placed in a field weakening state. In this state, the characteristics of the traveling motor M are of a low torque, high rotation type, and the motor M is rotated stably at the maximum speed. [0006] When a braking operation is performed while the vehicle is running at a speed higher than that at which regeneration is possible, regenerative braking is forcibly performed. During regenerative braking, as shown in FIG. 4, the regenerative contactor 7 is turned off, the forward contactor 3 is turned off, and the reverse contactor 4 is turned on, and first, the pre-excitation transistor 10 is held in the ON state for a certain period of time. Pre-excitation is performed. In this state, as shown by the arrow (solid line) in FIG. 4, a pre-excitation current flows through the field coil 5 via the pre-excitation resistor 11, and an electromotive force V is generated in the armature 2 in the direction of the arrow. When the electromotive force ■ exceeds a certain value, a preliminary excitation current I2 (indicated by a chain line) begins to flow through the regeneration diode 16 in addition to the preliminary excitation current 11. The pre-excitation current ■2 gradually increases. When the pre-excitation current I2 reaches a certain value, the pre-excitation transistor 10 is turned off and no current flows from the battery 1, but as shown in FIG. 5, the pre-excitation current I2 tends to continue flowing. [0007] When the transistor 9 is turned off in the above state, the regenerative current I3 flows toward the positive side of the battery 1 via the regenerative diode 16.about.15 as shown by the arrow in FIG. In this state, the electric power generated by the driving motor M is regenerated to the battery l, and the driving motor M is braked by the amount of current. Then, when the speed of the vehicle becomes smaller than the regeneration possible speed, the regeneration contactor 7 closes, and the braking shifts to plugging braking. [0008]

[Problem to be Solved by the Invention] When preliminary excitation for regenerative braking is performed with the field weakening contactor 13 provided in the control circuit short-circuited due to welding or the like, the field coil A part of the field current that should be supplied to the field weakening contactor 5 is shunted to the field weakening contactor 13. Therefore, sufficient electromotive force is not generated in the armature 2, making it impossible to shift to regeneration. Regeneration is the main braking function of electric vehicles, and if it is not possible to shift to regeneration, smooth braking will not be possible, which is dangerous. Conventionally, no method has been devised to easily detect a short circuit in the field weakening contactor before the vehicle starts running, and if the vehicle starts driving without knowing that the field weakening contactor is short-circuited, regeneration occurs during braking. There is a risk that the brakes may become ineffective. [00091] The present invention has been made in view of the above-mentioned problems, and its purpose is to easily detect a short circuit in a field weakening contactor and to start running without knowing that the field weakening contactor is in a short circuit state. It is an object of the present invention to provide a method for detecting a short circuit in a field weakening contactor of a battery-powered vehicle, which can prevent a state in which regenerative braking is impossible by doing so. [0010]

[Means for Solving the Problem] In order to achieve the above object, the present invention performs regenerative braking when braking is performed while traveling at a speed higher than a predetermined speed, and also connects forward and reverse contactors of the traveling motor. A field weakening contactor is connected in parallel, a pre-excitation transistor is connected to the forward and reverse contactors in parallel with the armature of the travel motor, and the forward and reverse contactors are pre-excited. In a battery vehicle equipped with a control circuit connected to a side opposite to the transistor, a chopper drive means for intermittently applying a battery power supply voltage to a running motor to drive the motor to rotate, each of the contactors and the regeneration contactor is connected to the control circuit. Turn on the pre-excitation transistor in the OFF state, measure the voltage applied to the chopper drive means at that time, and determine that the field weakening contactor is short-circuited if the applied voltage is equal to or higher than a predetermined voltage. I did it like that. [00111

[Operation] When the vehicle is stopped, the field weakening contactor, regeneration contactor, forward contactor, and reverse contactor are in the OFF state, so the voltage applied to the chopper drive means connected to the forward and reverse contactors is 0. Becomes Porto. When the pre-excitation transistor is turned on in this state, the voltage applied to the chopper driving means is maintained at O port if the field weakening contactor is normal and open. On the other hand, if the field-weakening contactor is short-circuited due to welding or the like, when the pre-excitation transistor is turned on, a voltage is applied to the chopper driving means via the field-weakening contactor. Then, the voltage applied to the chopper driving means is measured, and if the value is equal to or higher than a predetermined voltage, it is determined that the field weakening contactor is short-circuited. [0012] [Embodiment] An embodiment embodying the present invention will be described below with reference to FIGS. 1 and 2. The control circuit is basically the same as the conventional control circuit, and the same parts are given the same reference numerals and detailed explanation will be omitted. The control device 17 is connected to the battery 1 via a constant voltage power supply circuit 18 and a key switch 19. The control device 17 controls each of the contactors 3゜4.
, 7. 8. 13, and ON of the chopper driving transistor 9 and pre-excitation transistor 10.
The OFF control is performed according to a predetermined control program. Further, the control device 17 includes a transistor 9.
A detection signal from a sensor 20 that measures the voltage Vo applied to the sensor 20 is input. [0013] Next, the short circuit detection function of the field weakening contactor will be explained. Detection of a short circuit in the field weakening contactor 13 is performed according to the flowchart of FIG. When the driving lever is operated to the neutral position while the vehicle is stopped, the forward contactor 3, the reverse contactor 4, the regenerative contactor 7, and the field weakening contactor 13 are each held in the OFF state, as shown in FIG. . Next, the pre-excitation transistor 9 is turned on, and in this state, the sensor 20 detects the voltage Vo applied to the transistor 9. If the field weakening contactor 13 is normal, the voltage Vo applied to the transistor 9 will be O volts even if the pre-excitation transistor 9 is in the ON state. Therefore, if the applied voltage Vo is 0 port or almost 0 port as a result of detection by the sensor 20, the control device 17 determines that the field weakening contactor 13 is normal, and shifts to a state where traveling control is possible. On the other hand, if the field weakening contactor 13 is short-circuited due to welding or the like, when the pre-excitation transistor 9 is turned on, the voltage of the battery 1 is applied to the transistor 9 via the field weakening contactor 13, and the applied voltage Vo is 0. Much larger than Porto. Therefore, if the detection result by the sensor 20 is that the applied voltage Vo is not 0 port but more than a predetermined voltage value, the control device 17 determines that the field weakening contactor 13 is short-circuited, prohibits travel control, and shuts down the vehicle. Hold in a stopped state. [0014] Note that the present invention is not limited to the above embodiments, and for example, when it is determined that the field weakening contactor 13 is short-circuited based on the detection result by the sensor 20,
Travel control may be prohibited and an alarm device such as a warning light or buzzer may be activated. Furthermore, in the embodiment described above, the driving lever is not necessarily operated to the neutral position before the vehicle starts driving, but the key switch is only operated when the driving lever is placed in the neutral position when the vehicle starts driving. 19 may be turned on, and the short circuit detection operation of the field weakening contactor 13 may be performed whenever the vehicle starts driving. [0015]

As described in detail above, according to the present invention, a short circuit in the field weakening contactor can be easily detected when the vehicle is stopped, so that the vehicle can be driven without knowing that the field weakening contactor is in a short circuit state. By starting the regenerative braking, it is possible to prevent the regenerative braking from becoming impossible. Further, by using the pre-excitation transistor, it is possible to detect a short circuit state of the field weakening contactor without changing the conventional control circuit configuration.

[Brief explanation of the drawing]

FIG. 1 is a flowchart for detecting a short circuit in a field weakening contactor.

FIG. 2 is a control circuit diagram of the traveling motor showing a state in which each contactor is arranged in a short-circuit detection state of the field weakening contactor.

FIG. 3 is a control circuit diagram of a conventional traveling motor.

FIG. 4 is a circuit diagram showing the open/close states of each contactor and the flow of a pre-excitation current in a pre-excitation state.

FIG. 5 is a circuit diagram showing the open/close states of each contactor and the flow of a pre-excitation current in a pre-excitation state.

FIG. 6 is a circuit diagram showing the open/close states of each contactor and the flow of regenerative current in a regenerative state.

[Explanation of symbols]

1 Battery 2 Armature 3 Forward contactor 4 Reverse contactor 7 Regeneration contactor 9 Transistor IO as chopper driving means Pre-excitation transistor 13 Field weakening contactor M Traveling motor Vo Applied voltage

[Figure 5]

Claims (1)

[Claims] Claim 1: When braking is performed while traveling at a predetermined speed or higher, regenerative braking is performed, and a field-weakening contactor is connected in parallel with the forward and reverse contactors of the traveling motor, and the preliminary excitation transistor is connected to the traveling motor. The drive motor is connected to the forward and reverse contactors in parallel with the armature of the drive motor, and the power supply voltage of the battery is connected to the drive motor on the opposite side of the forward and reverse drive contactors from the pre-excitation transistor. In a battery vehicle equipped with a control circuit connected to a chopper driving means that rotates the motor by applying voltage intermittently, the pre-excitation transistor is turned OFF while each of the contactors and the regeneration contactor are OFF.
Field weakening contactor short-circuit detection of a battery-powered vehicle, in which the voltage applied to the chopper driving means at that time is measured, and it is determined that the field-weakening contactor is short-circuited when the applied voltage is equal to or higher than a predetermined voltage. Method.