JPH058730Y2 - - Google Patents

Description

[Detailed Description of the Invention] Field of the Invention This invention relates to a control device for an electric vehicle, and more particularly to a braking circuit for an electric vehicle equipped with, for example, a DC shunt motor.

Description of the prior art In conventional electric vehicles, such as golf carts, which are equipped with only a forward/reverse change lever and an accelerator, when climbing a slope, the vehicle is stopped and the forward/reverse change lever is moved in the forward direction. If you drive down a slope by inertia without pressing the accelerator pedal while the vehicle is in the vehicle, no braking will be applied to the electric motor that drives the vehicle, and the backward speed will increase, which is dangerous. For this reason, conventionally it was necessary to operate a mechanical brake to suppress the increase in speed.

Purpose of the invention Therefore, the main purpose of this invention is to provide a braking control device for an electric vehicle that can exert an effective braking function even when the electric vehicle moves in the opposite direction to the direction indicated by the forward/reverse change lever. That's true.

Summary of the invention The braking control device for electric vehicles according to this invention is
variable resistance means connected in series with the armature winding of the DC shunt motor with respect to the DC power supply, and having a resistance value that decreases in accordance with the amount of depression of the accelerator pedal;
It includes a series connection of an armature winding and a variable resistance means and a diode connected in parallel. The diode is connected with a polarity that causes a back electromotive force current generated in the armature winding to flow through the variable resistance means when the shunt motor is rotated in a direction opposite to the direction indicated by the forward/reverse change lever.

In the braking control device for an electric vehicle according to this invention, when the electric vehicle is run in the opposite direction to the direction indicated by the forward/reverse change lever and the shunt motor is rotated in the opposite direction, the diode is connected to the armature winding. A current due to the generated back electromotive force is applied to the variable resistance means. That is, since a closed loop is formed around the armature winding by the diode and the variable resistance means, the back electromotive force can be absorbed by the variable resistance means. Therefore, an effective braking function can be obtained even when the electric vehicle moves in the opposite direction to the direction indicated by the change lever.

The above objects and other objects and features of the present invention will become more apparent from the following detailed description with reference to the drawings.

DESCRIPTION OF EMBODIMENTS The drawing is a circuit diagram showing an embodiment of this invention. In the figure, the positive side of the DC power supply 1 is connected to the negative side of the DC power supply 1 via a fuse 2, a resistance circuit 3, and an armature 4. The resistance circuit 3 is configured so that its resistance value can be changed stepwise by operating an accelerator circuit 14, which will be described later, thereby increasing or decreasing the armature current and increasing or decreasing the rotational speed of the armature 4. In detail, the resistance circuit 3 includes three switches S1 to S3 and two resistors R1 and R2. Switches S1 and S3 are connected in series and inserted between fuse 2 and armature 4. Resistor R1 is connected in parallel to switch S3. Further, switch S2 and resistor R2 are connected in series, and this series circuit is connected in parallel to switch S3. Therefore, by sequentially closing the switches S1, S2, and S3 from the open state, the resistance value of the resistance circuit 3 (that is, the resistance value inserted in series with the armature circuit) is reduced. Note that the diode 17 connected in parallel to the resistance circuit 3 is a diode for regenerating back electromotive force generated in the armature 4 to the DC power supply 1, and a diode that can withstand a large current is used.

One terminal of the switch S1 (the terminal connected to the resistor R1) is connected to a direct current via a diode 5, a shunt field winding (hereinafter simply referred to as field winding) 6, and a field current intermittent circuit 7. Connected to the negative side of power supply 1. Diode 5 is a diode for preventing backflow. The field winding 6 cooperates with the armature 4 to form a so-called DC shunt motor. A freewheel diode 8 is connected in parallel to this field winding. Note that the field winding 6 is configured so that its connection polarity can be switched by switching a forward/reverse change lever (not shown). That is,
By switching the forward/reverse change lever, the direction of the current flowing through the field winding 6 is reversed. This switches the direction of rotation of the electric motor. Field current intermittent circuit 7 includes two Darlington-connected transistors 71 and 72, and a Zener diode 73 connected between the collector and emitter of transistor 71. A pulse signal is applied to the base of the transistor 72 from the input terminal 9. In response to this pulse signal, the field current flowing through the field winding 6 is controlled intermittently, and the rotational speed of the armature 4 is controlled.

Further, the positive side of the DC power supply 1 is connected to one end of the field winding 6 via a fuse 2, a key switch 10, a diode 11, and a resistor 12.
Fuse 2, key switch 10, diode 11
and is connected to the base of the transistor 72 via the resistor 13.

The positive side of DC power supply 1 is connected to 2 and key switch 10.
It is connected to the accelerator circuit 14 via. This accelerator circuit 14 has three microswitches MS1
~Includes MS3. These micro switches MS1
The opening and closing of MS3 is controlled in response to depression of an accelerator pedal (not shown). In other words, when the accelerator pedal is not depressed at all,
All of these microswitches MS1 to MS3 have been developed. As the accelerator pedal is depressed and the amount of depression gradually increases, the microswitches MS1, MS2, and MS3 are sequentially closed. Micro switch MS1~
One terminal of each MS3 is commonly connected to one terminal of the key switch 10. The other terminals of microswitches MS1 to MS3 are connected to the negative side of DC power supply 1 via solenoids SOL1 to SOL3, respectively. These solenoids SOL1~
SOL3 each closes the aforementioned switches S1-S3 when energized. In addition, between the micro switch MS1 and the solenoid SOL1,
A field current detection switch 15 is inserted. The field current detection switch 15 is configured to be closed only when a field current is flowing through the field winding 6. By providing such a switch 15, when no field current is flowing, the switch S1 is not closed and no current flows through the armature 4. Therefore, it is possible to prevent current from flowing through the armature 4 when the field current is zero. Further, a timer 16 is inserted between the micro switch MS3 and the solenoid SOL3. This timer 16 is used to extend the time from when the microswitch MS3 is closed until the solenoid SOL3 is energized. This prevents a large current from flowing through the armature 4. For example, if the accelerator pedal is depressed suddenly, armature 4
All of the microswitches MS1 to MS3 are closed even though the back electromotive force of the microswitch is not sufficiently large, and accordingly, all of the switches S1 to S3 are closed. Therefore, the resistance value of the resistance circuit 3 becomes 0, and a large current flows through the armature 4. However, if the timer 16 extends the time from when the micro switch MS3 is closed until the solenoid SOL3 is energized, the switch S3 can be closed after the back electromotive force of the armature 4 has become sufficiently large. can do. Therefore, large current is prevented from flowing through the armature 4.

The diode 18 is the most distinctive feature of this embodiment. The anode of this diode 18 is connected to one end of the armature 4, that is, to the negative side of the DC power supply 1. Further, its cathode is connected to the connection point between the diode 5 and the switch S1. As will be explained in detail later, the function of this diode 18 is to form a closed loop for braking when the accelerator pedal is released and the vehicle descends a slope.

Next, the operation of the above embodiment will be explained.
First, the key switch 10 is closed for starting. As a result, the diode 11 becomes conductive, and a minute current is supplied to the field winding 6. Subsequently, an accelerator pedal (not shown) is depressed. Depending on the amount of depression of the accelerator pedal, the microswitches MS1, MS2, and MS3 are sequentially closed.
Accordingly, solenoids SOL1, SOL2, and SOL3 are energized in order, and switches S1, S2, and SOL3 are energized in order.
3 are closed in sequence. At the initial stage when the amount of depression of the accelerator pedal is small, only switch S1 is closed. At this time, the resistance value of the resistance circuit 3 is defined by the resistance value of the resistor R1. And the amount of depression of the accelerator pedal increases and the micro switch MS
1 and MS2 are closed, switches S1 and S
2 are closed. At this stage, the resistor R2 is connected in parallel to the resistor R1, and the overall resistance value of the resistor circuit 3 becomes smaller than that at the first stage. Therefore, the armature current flowing through the armature 4 increases, and the rotation speed of the armature 4 increases. Furthermore, the amount of accelerator pedal depression increases, and the switch S
1 to S3 are all closed, the resistance value of the resistance circuit 3 becomes zero. Therefore, the armature current of the armature 4 becomes maximum, and its rotational speed also becomes maximum.
The time from when micro switch MS3 is closed until solenoid SOL3 is energized is:
It is extended by timer 16. This is to prevent the resistance circuit 3 from being short-circuited and a large current flowing through the armature 4 when the accelerator pedal is suddenly depressed at the time of starting as described above. That is, the switch S3 is closed after the armature current becomes sufficiently large and the back electromotive force of the armature 4 reaches a sufficiently large value.

In the above-mentioned powered running state, when the accelerator pedal is released, the resistance circuit 3 is opened, and the supply of power from the DC power source 1 to the armature 4 is cut off. In this case, if the back electromotive force of the armature 4 is greater than the power supply voltage of the DC power source 1, the diode 17 becomes conductive, and the back electromotive force of the armature 4 is
That is, the motor is in a regenerative braking state.

Next, we will explain the operation in a state in which this invention is interesting, that is, when the vehicle is going down a slope due to inertia and the forward/reverse change lever is engaged in the opposite direction to the direction of travel. In this case, a back electromotive force having the polarity shown in the figure is generated in the armature 4. Therefore, the diode 17 is not conductive and this back electromotive force is not regenerated.
However, the diode 18 becomes conductive, and the diode 18, the resistor R1, and the armature 4 form a braking circuit based on the back electromotive force. This provides the electric vehicle with a braking force and prevents it from increasing in speed. Therefore, the driver can back up the electric vehicle along the slope at a safe speed, increasing the safety of the electric vehicle. Furthermore, since the backward speed is limited, the shock caused by a sudden difference in acceleration is reduced when the vehicle attempts to move forward by depressing the accelerator pedal from that state, that is, when attempting to climb a slope.

Effects of the invention As described above, according to this invention, braking is automatically applied when backing up a slope due to inertia, thereby limiting the increase in speed and improving the safety of electric vehicles. can. Also, since the backward speed is limited, the shock caused by the difference in acceleration is minimized when the vehicle attempts to move forward next time.

[Brief explanation of the drawing]

The drawing is a circuit diagram showing an embodiment of this invention. In the figure, 1 is a DC power supply, 3 is a resistance circuit as a variable resistance means, 4 is an armature, 6 is a field winding,
18 indicates a diode.

Claims (1)

[Claims for Utility Model Registration] An electric vehicle brake control device for an electric vehicle driven by a DC shunt motor, wherein the shunt motor has a field winding 6 and an armature winding 4. and a current flowing through the field winding of the shunt motor is reversed by switching a forward/reverse change lever, wherein the armature is connected to a DC power supply. A variable resistance means 3 connected in series with the winding and having a resistance value that decreases depending on the amount of depression of the accelerator pedal; and a diode 18 connected in parallel with the series connection of the armature winding and the variable resistance means. and the diode causes a back electromotive force current generated in the armature winding to flow through the variable resistance means when the shunt motor is rotated in a direction opposite to the direction indicated by the forward/reverse change lever. connected in polarity,
Brake control device for electric vehicles.