JPS6129205B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a soft-start control circuit for a chopper-controlled electric vehicle, and more particularly, an object of the present invention is to provide a soft-start control circuit for an electric vehicle that starts the electric motor without a shock at startup.

In general, in chip control electric vehicles such as forklifts and battery carriers, when starting the vehicle, the accelerator pedal is suddenly pressed down. It is common to provide a starting circuit.

In conventional soft start circuits, when the vehicle is started by rapidly stepping on the accelerator, the motor current at the time of startup is detected, the flow rate of the chopper device is reduced, and the flow rate is gradually adjusted to a position proportional to the accelerator angle. The method used was to gradually increase the speed up to 100 degrees to smoothly accelerate the vehicle. According to such a method, the detection circuit and arithmetic circuit become complicated, the control circuit becomes expensive, and maintenance and adjustment are time-consuming. The present invention eliminates these problems and provides a soft start circuit that is simple in structure, operates stably, and is manufactured at low cost.

Next, embodiments of the present invention will be described based on the accompanying drawings.

Fig. 1 is a block diagram showing one embodiment, and to explain the operation in the figure, 1 is the main power supply, 2 is the armature of the electric car, 3 is the series field winding, and 4a and 4b are the forward and backward movement. A switching contactor, 5 is a flywheel diode, and 6 is a chopper device. In this embodiment, a chopper device using a transistor is shown, but a chopper device composed of a thyristor or the like may also be used. Reference numeral 7 denotes an accelerator device that responds to an accelerator pedal (not shown) and generates a voltage according to its resistance value.

Reference numeral 8 denotes a known reference signal oscillator, which is constructed using a single junction transistor, a transistor, or a timer IC, and oscillates a triangular wave having a constant amplitude and a constant frequency.

A speed setting circuit 9 compares the reference signal from the oscillator 8 with the accelerator voltage from the accelerator device 7 to generate a pulse signal.

Reference numeral 10 denotes a drive circuit, which is composed of a known transistor amplifier and amplifies the digital signal from the speed setting circuit 9 to drive the chopper device 6. Reference numeral 11 represents a soft start circuit according to the present invention, which is the output of the speed setting circuit 9. A speed signal is taken out from the motor and inputted to the soft start circuit 11, and the soft start circuit 11 is operated only when the electric vehicle is started, and its output is fed back to the speed setting circuit 9, thereby sending a soft start signal to the drive circuit 10. The chipper device 6 is soft-started.

The specific circuit configuration and operation of the present invention will be explained below with reference to FIG. In the same figure, the first
Items with the same symbols as in the figure indicate the same functions.

When compared with FIG. 1, the speed setting circuit 9 and the soft start circuit 11 are explained in detail.

In FIG. 2, the speed setting circuit 9 has a resistor 21, a semi-fixed resistor 22, an accelerator device 7, a semi-fixed resistor 40, and a photoelectric composite element light receiving side 37b connected in series and parallel to the positive input terminal of a comparator 41 as shown in the figure. , the output of the reference signal oscillator 8 is connected to the negative input terminal via a resistor 20, and the output of the comparator 41 is connected to a pull-up resistor 23.

Next, I will explain the soft start function.
The output of the comparator 41 is connected through a backflow prevention diode 24 to a first-order lag circuit made up of a resistor 25 and a capacitor 26, and then to an inverter made up of a resistor 29 and a transistor 30. 28
is an input protection resistor of the transistor, and 27 is a discharge resistor of the first-order delay circuit, which is set to a value sufficiently larger than that of the resistor 25. 31 is a shot trigger element that gives a sharp rising waveform to the one-shot multivibrator 32, and gives the output time width of the one-shot multivibrator circuit 32 with a time constant determined by the values of a capacitor 33 and a resistor 34.

Although the shot trigger element 31 and the one-shot multivibrator circuit 32 are composed of ICs, they may also be composed of transistors.

38 is one-shot multivibrator circuit 3
2 is a transistor that operates only when it is in operation; 35 is an input protection resistor; 37a is the light emitting side of the photoelectric composite element; it emits light only when the transistor 38 is in operation, changing the resistance value of the photoelectric composite element's light receiving side 37b from a high resistance state to a low resistance state; change the state. 36 is an input protection resistor on the light emitting side 37a of the photoelectric element, and 39 is an auxiliary power supply circuit that supplies a constant voltage of volt E to the circuit.

The circuit configured in this way will be explained using the operating waveforms shown in FIG. Note that R is added before the symbol number to indicate the resistance value.

First, the comparator 4 when the accelerator is suddenly stepped on from the state where the volume resistance value of the accelerator device 7 is zero
For the input voltage V ₂ of 1, the following equation holds true.

V ₂ =R ₇ +R ₂₂ /R ₇ +R ₂₁ +R ₂₂ ×E……(1
) However, the resistance value of the photoelectric composite element light receiving side R _37b is the resistance R ₇ until the photoelectric composite element light emitting side 37a emits light.
Since it shows a high resistance value compared to R ₄₀ + R _37b = ∞Ω, there is no need to consider the effect of parallel resistance due to R _37b and R ₄₀ , and therefore the parallel resistance value R is 1/R = 1/R ₇ +1/R ₄₀ +R _37b , 1/R ₄₀ +R _37b = 0, R = R ₇ From equation (1), at startup, a voltage V ₂ is generated in response to the opening of the accelerator volume R ₇ , and when the accelerator starts to be depressed, T The rise voltage necessary to start the electric car for _one hour is applied to armature 2.

The time _T1 is determined by the time constant determined by the resistor 25 and capacitor 26.

T After _one hour, when the forward voltage between the base and emitter of the transistor 30 (0.6 to 0.8V) is reached, the transistor 30 becomes conductive and the input of the Schmitt trigger element 31 slowly changes from the H level to the L level, and the Schmitt trigger element 31 is activated. The output of the trigger element 31 sharply inverts from L to H. In response to the trigger output of the shot trigger element 31, the one-shot multivibrator circuit 32 outputs a positive pulse signal with a pulse width _T2 hours. During this time, the transistor 38 is conductive, and the light emitting side 37a of the photoelectric composite element emits light only for the time T ₂ , and during this time, the light receiving side 37a of the photoelectric composite element
The resistor _R37b of the resistor 7b has a sufficiently lower value than the resistor _R7 .

Also, during T ₂ hours, the semi-fixed resistance R ₄₀ is sufficiently larger than the resistance R _37b , so the parallel resistance value R is 1/R = 1/R ₇ + 1/R ₄₀ + R _37b However, R ₄₀ + R _37b ≒ R ₄₀ 1/ R=1/ _R7 +1/ _R40 R= _R7 × _R40
/R ₇ +R ₄₀ <R ₇ From this, the following formula holds true.

V ₂ ′=R+R ₂₂ /R+R ₂₁ +R ₂₂ ×E (2) From equations (1) and (2), V ₂ >V ₂ ′, so at what position of the value of the volume resistance R ₇ of the accelerator device 7? However, when the photoelectric composite element is operating, V ₂ >
V ₂ ′, and the comparator positive input level is lowered.
T The output pulse width of the comparator output within ₂ hours becomes narrower, and even though the accelerator volume 7 is depressed and open, the volume is returned to its original state.
Starts smoothly without sudden acceleration.

In addition, the relationship between the time constants of the resistor 25 and capacitor 26 and the discharge resistor 27 is set so that the transistor 30 will not reverse even if the accelerator is returned halfway from the position where it was depressed and then depressed again, so the one-shot multivibrator circuit 32 is restarted. do not. The semi-fixed resistor 22 is provided to set the conduction rate of the output of the comparator 41 when the volume of the accelerator device 7 is opened to the maximum. Further, the semi-fixed resistor 40 is used to make the conduction rate variable within the soft start setting time T ₂ hours to optimally adjust the starting characteristics of the soft start.

As detailed above, according to the present invention, even if the accelerator pedal is suddenly depressed when starting an electric car, the electric car starts using the first-order delay circuit, and then a one-shot multivibrator circuit and a photoelectric composite element perform a soft start. By using semiconductors, the control section can have a completely non-contact structure, making it possible to obtain a circuit that is safe, has a simple structure, and is inexpensive.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a detailed circuit diagram of the soft start circuit shown in FIG. 1, and FIG. 3 is an operating waveform diagram of FIG. 2. 1... Main power supply, 2... Armature, 3... Series field winding, 4a, 4b... Forward/forward switching electromagnetic contactor, 5
... flywheel diode, 6 ... chopper device, 7 ... accelerator device, 8 ... reference signal oscillator, 9 ... speed setting circuit, 10 ... drive circuit, 1
1... Soft start circuit, 25... Resistor (first order delay circuit), 26... Capacitor (first order delay circuit), 29... Resistor (inverter circuit), 30...
transistor (inverter circuit), 31... Schmitt trigger element, 32... one-shot multivibrator circuit, 37a... photoelectric composite element light emitting side, 37b... photoelectric composite element light receiving side.

Claims (1)

[Claims] 1 A chopper control device and electric motor for power control that are supplied with power from a DC power source, a speed setting circuit that converts the signal from the accelerator volume into a pulse signal and outputs it to the drive circuit, and a reference signal that is output to the speed setting circuit. an electric vehicle control device having a reference signal generation circuit that provides a first-order delay to the speed signal from the speed setting circuit; an inverter circuit that inverts the output of the first-order delay circuit; and an inverter circuit output. A shot trigger circuit that inverts the output, a one shot multivibrator circuit that outputs a one shot pulse of a fixed time duration by the output of the shot trigger, and a photoelectric composite element that is operated by the output, the light receiving side of which is placed in parallel with the accelerator volume. A soft start control circuit for an electric vehicle, characterized in that a speed setting circuit generates a soft start signal while a photoelectric composite element is operating.