JPS5893403A - Regenerative brake controller - Google Patents

Abstract

PURPOSE:To improve the decelerating performance by shifting a drive motor from a regenerative braking to plugging when the current of the motor at the regeneratively braking time becomes lower than the specified current value corresponding to the opening of an accelerator. CONSTITUTION:When a regenerative brake is operated, a forward drive switch F12 is opened, a reverse drive switch R13 is closed, and an FR contactor 7 is switched to reverse side. At this time, the voltage of a terminal B of a brake discriminator 15 becomes a low level, thereby allowing a transistor TR2 to be interrupted and opening a regenerative contactor 4. Then, a chopper transistor 8 is controlled to perform regenerative brake. When the running speed becomes sufficiently decelerated by the regenerative braking so that the current of the motor becomes lower than the specified current value corresponding to the opening of the accelerator, the voltage of the terminal B becomes high level, and the contactor 4 is thus closed, thereby shifting the motor to plugging.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for electric braking of a battery-powered vehicle,
In particular, the present invention relates to a circuit suitable for determining the transition from regenerative motion to plugging.

Electric braking for battery-powered vehicles such as battery forklifts uses a combination of plugging and regenerative braking. By automatically switching from regenerative braking to plugging, the driver's operation is facilitated. This switching timing is determined based on the speed of the motor, and a tachometer is generally used to detect the speed. ,・ However, if there is no space to install a tachometer, or if a battery forklift that does not have regenerative braking is modified to perform regenerative braking, it may not be possible to install a tachometer.

Therefore, one possible method for determining when to switch the braking method without using a tachometer is to detect the current in the travel motor circuit and switch to plugging when the current during regenerative braking falls below a certain specified current. I'm looking forward to it.

However, when the accelerator opening at the time of transition to plugging is large, the braking force is large, and when the opening is small, the braking force is small. The method of determining when to switch the braking method based only on the current value has the disadvantage that deceleration is not performed at a smooth ratio, resulting in poor running performance.

An object of the present invention is to provide a regenerative braking control device that improves deceleration performance when the braking of a battery-powered vehicle is shifted from regenerative braking to plugging.

° The present invention detects the current in the travel motor circuit during regenerative braking, and when this detected current becomes less than a specified current value determined in accordance with the accelerator opening, the system shifts from regenerative braking to plugging. .

The aim is to smoothly decelerate during this transition to improve running speed.

Hereinafter, the present invention will be explained using illustrated embodiments.

FIG. 1 shows an overall circuit diagram of a battery forklift truck according to an embodiment of the present invention.

As shown in FIG. 1, #2 is connected to the positive electrode of battery 1.
A line 3 is connected to each negative electrode. A ten terminal of an armature 6A of a traveling motor 6 is connected to this line 2 via a regenerative contactor 4 and a current detector 5. One terminal of the armature 6A is connected to the line 3 via a series circuit consisting of an FR contactor 7A, a field coil 6B, an FR contactor 7B, and a chopper transistor 8. Said armature 6A
One terminal of the plugging diode D is connected to the opposite polarity.
2 to the line 2, said FR contactor 7A.

The negative side of 7B is connected to line 2 via a freewheeling diode D, which is connected with opposite polarity.

The negative pole side of the regenerative contactor 4 is connected to the line 3 via a regenerative diode D connected to the opposite polarity. Said FR
The anode of a diode D4 is connected to the negative electrode side of the contactors 7A and 7B, and the cathode of the diode D is connected to the base of a chopper transistor 8 through a series circuit of a resistor R and a transistor/transistor TR. A conduction rate control circuit 9 is connected to the base of the transistor TR. The quad of the diode D4 is also connected to a capacitor C1 and a diode D'60, the capacitor C1 being connected to the cathode of the diode Ds and the anode of the diode p. The cathode of diode D7 is connected to the anode of diode D6 and capacitor C2. the diode D;
The anode of and capacitor C2 are connected to line 3.

Transistor TR3 is connected between line 2 and one terminal of armature 6A, and the base of transistor TR3 is connected to terminal (A) of braking determination circuit 15 via resistor R4. Drive coil RBIO of regenerative contactor 4
are respectively connected to line 2 and to line 3 via transistor Tft2. Drive coil F of FR contactor 7
RIZ is connected to line 2 and line 3 via switch F12, respectively.

Switch R13 connected to line 2 is connected to diode D9
, a resistor R2, a Zener diode ZD, and a resistor R3.

The connection point between the diode D9 and the resistor R2 is connected to the negative electrode side of the switch F12 via the diode D6. The connection point between the Zener diode ZDi and the resistor R3 is connected to the base of the transistor TR20, and is also connected to the protection circuit 14 via the diode Dll, and is connected to the terminal () of the braking determination circuit 15 via the diode I)to.
B).

A detected current signal from the current detector 5 is inputted to a terminal (C') of the brake determination circuit 15, and power is supplied to the brake determination circuit 15 through lines 2 and 3.

A case will be described in which a braking operation including regenerative braking is applied while the battery forklift truck configured as described above is traveling forward.

For forward running, when switch F12 is turned on, drive coil F
RII is excited and the PR contactor 7 is switched to the forward side, and at the same time, the transistor TR4 is turned on and the drive coil RBIO is excited, so the regenerative contactor 4 is closed. As a result, drive current is supplied from battery 1 to travel motor 6 via chopper transistor 8 . The chopper transistor 8 is subjected to chopper control via the transistor R1 based on a control signal outputted from the conduction rate control circuit 14 in accordance with the operation amount of an accelerator (not shown). This chopper control controls the drive current of the travel motor, and the travel speed of the battery forklift is controlled in accordance with the amount of operation of the accelerator.

To activate regenerative braking, forward drive switch F12
and turn on the reverse travel switch R1j. As a result, the FR contactor 7 is switched to the reverse side. Further, at this time, the braking determination circuit 15 is activated (T3) the potential at the terminal becomes low level), and the contactor TR2 is cut off, and the regenerative contactor 4 is opened. Furthermore, the braking determination circuit 1
The potential of the terminal (A) is set to be low for a predetermined time (T,) at the same time as the potential of the terminal (B) is low. Period when terminal (A) is at low level potential (〒1)
) contactor TR is conductive and 1. The field coil 6B is pre-excited with a polarity opposite to that during forward movement.

Note that the operation of the braking determination circuit 15 will be explained in detail later. - Due to the above operation, an induced voltage of the polarity shown in parentheses in FIG. A circulating current is passed through the circuit formed by the diode D, - the current detector 5, and when the chopper transistor 8 is cut off, the field coil 6B-7, the wheeling diode D1, the battery 1, the regenerative diode D3, the current detector 5 Regenerative braking is performed by causing a regenerative current to flow through the circuit formed by the battery and charging the battery.

When the traveling speed is sufficiently reduced by regenerative braking, the braking determination circuit 15 outputs a regeneration end signal.

That is, the potential at the terminal (B) becomes high level again, the regenerative contactor 4 is reclosed and the state shifts to plugging, and then the battery forklift shifts from forward travel to reverse travel.

Next, the above-mentioned braking determination circuit 15 according to the present invention will be explained in detail using the drawings.

A detailed circuit diagram of the braking determination circuit 15 is shown in FIG.

In the figure, the constant voltage circuit 17 is connected to the rock 2 shown in FIG. The accelerator 19 consists of a variable resistor, and a fixed resistor of the variable resistor is connected to the constant voltage circuit and the line 3 shown in FIG. The output terminal of the accelerator 19 is connected to the line 3 through a series circuit of resistors R8 and Ro. The connection point between the resistor R8 and the circle is connected to one input terminal of the operational amplifier OP. Further, the output terminal of the accelerator 19 is connected to the input terminal of the operational amplifier OP2 via a series circuit of resistors R1 and R2. The connected terminal (C) of the current detector 5 is connected to a current detection circuit 20, and the output terminal of the current detection circuit 20 is connected to the input terminal of the operational amplifier OP1 via a resistor R6. has been done. Moreover, the ten input terminals are connected to a resistor R7,
The resistor R1 is connected to a diode D1. Operational amplifier O via ゛
The output terminal of P3 is connected to the output terminal of monostable multi-vibration circuit 22 via diodes D and 7, respectively.

The output terminal of the operational amplifier OP is feedback-connected to one input terminal via a resistor R1o, and is also connected to the cathode of a diode D,2. The anode of the diode DI2 is connected to a connection point (D) where the resistors R8 and R1□ are connected in series. In addition, the regeneration command circuit 21 is connected to the connection point (D) in the opposite direction through a diode I).
+s. A series circuit of resistors R13 and R14 is connected to the constant voltage circuit 17 and line 3, and a connection point between the resistors R73 and R14 is connected to one input terminal of the operational amplifier OP2, and to the operational amplifier OP2. It is connected to the input terminal of device OP3. The output terminal of the operational amplifier OP2 is connected to one input terminal of the operational amplifier OP3 and also to the resistor R1.
7 and a transistor TR via a diode D and 8.

is connected to the base of the operational amplifier OP, and also to the ten input terminals of the operational amplifier OP via a resistor R1. The collector of the transistor TR4 is connected to the terminal (B), and the emitter is connected to the line 3.

The output terminal of the operational amplifier OPs is connected to the monostable multivibrator 2 through a series circuit of capacitor C3 and resistor RI6.
2, and the input terminal is connected to a constant voltage circuit 17 via diodes D and 4. The output terminal of the monostable multivibrator 22 is connected to a resistor R8,
and the transistor T through a series circuit of the diode DI6.
R, is connected to the base of the transistor TR5.
Its collector is connected to the terminal (A), and its emitter is connected to line 3.

The operation of the braking determination circuit configured as described above will be explained.

The constant voltage circuit 17 supplies the required constant voltage control power to each connected circuit.

The current detection circuit 20 amplifies the current signal output from the current detector 5 to a desired level and outputs the amplified current signal.

The regeneration command circuit 21 is a well-known circuit that determines whether regenerative braking is to be performed based on the running state of the battery forklift, etc., and outputs a regeneration command signal.

First, as mentioned above, turn off the forward travel switch E12,
Turn on the drain switch R, 13 to enter the regenerative braking state. At this time, when a regeneration command signal is output from the regeneration command circuit 21, the regeneration command signal is input to the + input terminal of the operational amplifier OP2 via the diode DI3, and the regeneration command signal is input to the + input terminal of the operational amplifier OP2.
The output potential of transistor 2 becomes high level, transistor TR becomes conductive, and a low level signal is output from terminal (B). Further, when the output potential of the above-mentioned OP becomes a high level, the output of the operational amplifier OP becomes a low level and is inputted to the monostable multivibrator 22 through a differentiating circuit consisting of a capacitor C3 and a resistor 6. When the input potential of the monostable multivibrator 22 becomes a low level, a signal is output from the output that becomes a high level for a time corresponding to the metastable time (T1), and the transistor TR becomes conductive and the terminal (A)
A low-level signal is output for time T1. As a result, the regenerative contactor 4 is opened and the field coil 6B is pre-excited as described above, and the regenerative braking operation of the battery forklift is started.

On the other hand, the accelerator 19 is connected to the single power terminal of the operational amplifier OP1.
The specified current value for the end of regeneration is inputted, and the detected current value is inputted to the + input terminal. . This operational amplifier OP compares and calculates the specified current value and the detected current value, and outputs a regeneration end signal when the detected current value becomes less than the specified current value. We are determining when to transition to plugging. At the start of regenerative braking, the potential of the + input terminal of the operational amplifier OP is momentarily raised to the output low level potential of the operational amplifier OP3 through the diode D15 when the regeneration command signal is input. It is pulled up to the output high level potential of the monostable multi-vibrator 22 via D17.

In this way, during the pre-excitation time (T1), the above-mentioned judgment operation is stopped during the pre-excitation time (T1) by maintaining the input potential at a level sufficiently higher than the specified current value for one person. . Therefore, during this time (T1), the output of the operational amplifier OP1 is maintained at a high level as shown in FIG. Since the potential is held at a high level and one output potential of the operational amplifier OP2 is also at a high level, regenerative braking is continued.

After the pre-excitation time (T1) ends, the operational amplifier OP,
starts the determination operation described above. When the detected current value falls below the specified current value, the output potential of the operational amplifier OP becomes a low level; as a result, the potential at point D is lowered, and the output potential of the operational amplifier OP2 becomes a low level. Therefore, the transistor TR4 is cut off, and the potential at the terminal (B) of the braking determination circuit 15 becomes high level. When the potential of the terminal (B) becomes high level, the transistor TR2 becomes conductive, the regenerative contactor 4 is reclosed, and the battery forklift is switched from regenerative braking to plugging as described above.

When shifting to plugging, a current corresponding to the accelerator opening shown in Fig. 3 will be passed through the motor, but as described above, the current will shift from the current corresponding to the accelerator opening. Therefore, it should be done in such a relaxed manner.

Therefore, according to this embodiment, the braking method is switched from regenerative braking to plugging when the current of the travel motor decreases below the specified current value determined by the accelerator opening. Since the deceleration during the transition is performed smoothly, it is possible to achieve extremely high speed performance.

In addition, conventionally forward and reverse contactors were required, but according to this embodiment, there is only one forward and reverse contactor.Moreover, by providing the regenerative contactor with current interrupting ability, forward and reverse Since the contactor only needs to be one that matches the current carrying capacity, it has the effect of being able to be made smaller.

As explained above, according to the present invention, it is possible to smoothly perform deceleration braking when the electric braking of a battery-powered vehicle is transferred from regenerative braking to plugging, and there is an effect that driving performance can be improved. .

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram of an embodiment to which the present invention is applied, FIG. 2 is a partial detailed circuit diagram of the embodiment illustrated in FIG. 1, and FIGS. 3 and 4 are operation explanatory diagrams.

Claims (1)

[Scope of Claims] 1. In a regenerative braking control device that performs switching control between a regenerative braking circuit and a plugging circuit that are switchably connected to a DC motor whose speed is controlled according to the amount of operation of an accelerator, the DC motor A detection circuit that detects the current of and outputs the detected current value, and A above. A circuit that outputs a specified current value determined in accordance with the operation amount of the accelerator, and a circuit that performs a comparison calculation between the specified current value and the detected current value, and outputs a regeneration end signal when the detected current value is less than the specified current value. A regenerative braking control device comprising: and means for switching the regenerative braking circuit to a plugging circuit in response to the regeneration end signal.