JPS6220761B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention provides an electric vehicle that can easily detect plugging braking when plugging braking is used in an electric vehicle, detect a short circuit failure of a plugging diode, and easily protect overcurrent of a chopper, motor, etc. The present invention relates to a vehicle control method and device.

It has been known that when plugging braking is applied to an electric vehicle, it is necessary to detect the state in which plugging is being applied.For example, when plugging starts to act, a signal is given to the chopper control circuit and the signal flows to the chopper. It is necessary to suppress the magnitude of the current flowing through the armature winding of a DC motor, alleviate the braking torque, prevent sudden braking of the electric vehicle, and prevent problems such as load collapse. ing.

A conventional electric vehicle having a plugging function has the following structure. That is, the power supply from the DC power supply to the DC motor for driving the electric vehicle is controlled by adjusting the percentage of time during which the DC motor and the DC power supply are connected. In the control device for this type of electric vehicle, a power control device such as a thyristor circuit consisting of a transistor or a main thyristor and a commutating element, that is, a chopper is employed. Further, the field windings of the DC motor are connected in a bridge shape so that the direction of the field magnetic flux can be reversed.

Also, in order to perform the plagging effect,
It is common to connect a first power diode in parallel with the circuit containing the armature winding, said first power diode being connected with a polarity through which current can flow during plugging braking. Furthermore, a second coil is connected in parallel to the series circuit of the armature winding and field winding of the DC motor.
A power diode is connected to form a circuit in which the motor current continues to flow through the second power diode while the chopper is off. When the DC motor rotates as an electric motor and generates rotational torque, the polarity is such that no current flows into the armature winding via the first power diode due to the field magnetic flux of the DC motor. generates an induced voltage of

When braking torque is required, the direction of the current flowing through the field winding is reversed by switching an electromagnetic contactor, for example, by an operation by the electric vehicle driver. The induced voltage generated in the armature winding due to this reversal of the direction of the field magnetic flux has a polarity that allows current to flow through the first diode. At this time, the DC motor acts as a shunt generator and generates power generation control torque. This generated braking torque can be called a reverse braking torque when the DC motor is considered as an electric motor. The magnitude of the generated braking torque, that is, the plugging braking torque, is adjusted by controlling the conductivity of the chopper.

In conventional electric vehicles, the following method was adopted to detect such a plugging braking state, and when a plugging braking state was detected, the conductivity of the chopper was controlled to an appropriate value.

In other words, in conventional electric vehicles, the plugging braking state is detected by detecting the forward voltage drop that occurs across the first power diode when forward current flows through the first power diode. Ta.

Although this conventional method has been found to be satisfactory in many applications, it has the following drawbacks. First of all, since the dynamic resistance of the first power diode depends on the temperature, the plugging detection signal is affected by the characteristics of the first power diode, and the plugging braking performance of the electric vehicle fluctuates as the temperature changes. There was a drawback that it occurred.

Second, when the DC motor is not in a plugging control state and for some reason enters a low rotation state or lock state, flywheel current flows through the first power diode, so this state becomes a plugging braking state. It had the disadvantage of false positive detection.

Third, the conventional plugging detection method detects the forward voltage drop of the first power diode,
Since a method is used to reduce the conductivity of the chopper to a preset constant conductivity, when plugging braking is performed from high speed, a large plugging current flows through the armature winding of the DC motor, causing damage to the commutator and brushes. This had the disadvantage of damaging the equipment and raising the temperature of the armature extremely.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electric vehicle control device that can eliminate the various drawbacks mentioned above and can accurately detect a plugging braking state.

That is, the present invention supplies power to a DC motor for driving an electric vehicle having a field winding and an armature winding through an intermittent chopper and a main circuit switching switch, and has a plugging function to the armature winding. Equipped with a plugging diode in parallel, and a current detection circuit that detects the difference between the current flowing through the field winding wire and the current flowing through the plugging diode,
The plugging operation is detected from the output of the current detection circuit.

The method and apparatus according to the present invention will be described in detail below with reference to examples.

FIG. 1 shows an electric circuit diagram of an electric vehicle control device according to the present invention. In FIG. 1, 1 indicates a chip, in particular a thyristor chip. 2 is a DC motor 3
4 is the armature winding of the DC motor 3. Reference numerals 5 and 6 indicate electromagnetic contactors constituting forward/reverse switching means. Reference numeral 7 denotes a plugging diode constituting a plugging circuit, which is connected to both ends of the armature winding 4. A flywheel diode 8 constitutes a flywheel circuit, and is connected in parallel to the series circuit of the field winding 2 and the armature winding 4. Reference numeral 9 denotes a variable resistor constituting an accelerator means, which is linked to an accelerator pedal or accelerator lever (not shown) whose depression angle is adjusted by the electric vehicle driver's foot or hand.
10 is a chopper control circuit and thyristor chopper 1
The conduction rate of the thyristor chopper 1 is controlled in accordance with the signal from the accelerator means 9.

A current detection means 11 detects the difference between the current I _F flowing through the field winding 2 and the current I _P flowing through the plugging diode 7, and is composed of, for example, a magnetoresistive element or a Hall element. 12 is a differential amplifier that detects the output signal of the current detection means 11 (current value I _F of the field winding 2).
It is proportional to the value obtained by subtracting the current value I _P of the plugging diode 7. ).

13, 14, 15, 16, 17 and 18 are resistors, respectively, and the amplification degree of the differential amplifier 12 is determined by these resistors.

19 is a soft start circuit that provides a delay time to the acceleration command output of the accelerator means 9, and includes a voltage follower 20, resistors 21 and 22, and a diode 23.
and a capacitor 24.

25 is a comparator, which is composed of a diode 28 and a resistor 31, and when the output of the differential amplifier 12 becomes lower than the reference voltage determined by the resistors 26 and 27, the charge of the capacitor 24 of the soft start circuit 19 is reduced. The battery is discharged by a discharge circuit. The lower limit of the discharge amount is determined by the diode 29 and resistors 30 and 31 using the output of the differential amplifier 12 as the power source.

Reference numeral 32 denotes a current limiting circuit, which acts on the chopper control circuit 10 when the output of the differential amplifier 12 reaches the set value a, and supplies an off pulse to the thyristor chopper 1 to prevent overcurrent in the main circuit. be.

33 is a short-circuit failure detection circuit for the plugging diode 7, which opens the electromagnetic contactor 5 or 6 when the output of the differential amplifier 12 becomes less than a set value b.

34 is a starting circuit, and switch 35 is set to A in Fig. 1.
Alternatively, after switching to the B side, the transistor 40 is operated by the drive circuit 43 to excite the excitation coil 36 or 37 of the electromagnetic contactor 5 or 6.
Note that the diodes 38 and 39 are connected to the excitation coils 36 and 37.
41 and 42 are resistors.

The operation of the electric vehicle control device having the above configuration will be described in detail below.

First, the operation of the vehicle when it is running will be explained. Insert the switch 35 into one of the fixed terminals A and B, for example, A.
When the transistor 40 becomes conductive, the excitation coil 36
is energized. Then, one of the electromagnetic contactors 5 or 6, for example 5, is energized and the switching piece 45 comes into contact with the power supply side contact 47. Therefore, when the chopper control circuit 10 receives a command signal from a variable resistor 9 linked to an accelerator (not shown) via the soft start circuit 19 and operates the chopper 1 according to this signal, electric power is supplied to the DC motor 3. , supplied.

FIG. 2 shows waveform diagrams of various parts in the electrical circuit diagram of FIG. 1. That is, the waveform in FIG. 2A shows the voltage applied to the DC motor 3 with respect to time t. The waveforms in FIG. 2B show the field current I _F and plugging diode current I _P during operation of the chopper 1 versus time t. FIG. 2C shows the output of the differential amplifier 12, ie, the voltage at point C in FIG. 1, with respect to time t.

In FIG. 2B, the motor current I _M flowing when the chopper 1 is on is the current I _F ' flowing through the flywheel diode 8 as a flywheel current when the chopper 1 is off, and the current I _P flowing through the plugging diode 7. becomes.

In this case, the current I _P flowing through the plucking diode 7 normally does not flow, and when the motor 3 is in the locked state or the chopper 1 is in the off state, such as at low speeds, the armature 4 has the polarity shown in Fig. 1. It flows when no induced voltage is generated.

At this time, the current detector 11 detects the difference between the current I _F flowing in the field winding 2 and the current I _P flowing in the forward direction of the plugging diode 7. The current detection means 11 used here is composed of a _magnetically sensitive element shown in _{FIG .}
- When a magnetic flux corresponding to I _P is passed through, a potential difference e ₁ is generated at the output, and the output e ₁ increases as the magnetic flux increases.

Next, in FIG. 2C, if the difference between the field current I _F and the forward current I _P of the plugging diode 7 is zero, the output e ₁ of the current detection 11 is zero, and in this case, the resistors 17 and 18 With the bias of , the output of the differential amplifier 12 becomes e ₂ . If the difference between the field current I _F and the forward current I _P of the plugging diode 7 becomes a positive value and increases, the voltage at point C of the differential amplifier 12 will be an amplified value with reference to e ₂ . Occur.

In other words, in the waveform shown in Fig. 2 (c), between time ta and tb with voltage e ₂ as the reference, that is, when chopper 1 is conducting,
It shows a value corresponding to the current value I _C flowing through the chopper 1, and when the chopper 1 is cut off between time tb and tc, the current flowing in the forward direction of the plugging diode 7 from the current value I _F flowing through the field winding 2. The value corresponding to the value after subtracting the value I _P is shown. At this time, comparator 25
If the reference value is the value of the plugging detection level c shown by the dashed-dotted line in FIG. In other words, since plugging braking is not detected, smooth acceleration can be achieved. When the current flowing through the chopper 1 reaches the overcurrent limit set value between times th and ti, that is, the potential at point C reaches the value set in the current limiter circuit 32, that is, the overcurrent limit value in FIG. When reaching (set value a), a command is sent to the chopper control circuit 10 to cut off the chopper 1 and suppress the chopper current _I.sub.C. Next time
When the plugging diode 7 has a short-circuit failure as between tm and tn, all the field current I _F flows to the plugging diode 7, and the forward current I _P of the plugging diode 7 takes a negative value, that is, the 1
Flows in the opposite direction to that shown in the figure. At this time, the output of the current detector 11, that is, the potential at point C, is determined by the setting value of the current limiting circuit 32 (the plugging diode short circuit fault detection value (setting value b) in Fig. 2 c) as shown in Fig. 2 c. It rises to a much higher value.

The plugging diode short-circuit failure detection circuit 33 detects that the potential at point C exceeds the set value b in FIG.
When the switching switch 45 of the electromagnetic contactor 5 switches to the normally closed contact 46
Return to the side, shut down the main circuit, and bring the vehicle to a safe stop.

Next, the operation during braking of the vehicle will be explained.

When the switch 35 is switched from A to B, the excitation of the electromagnetic contactor 5 is cut off, and the switching piece 45 returns from the power supply side contact 47 to the normally closed contact 46 side.
The electromagnetic contactor 6 is excited, and the switching contact piece 48 comes into contact with the power supply side contact 50. That is, the direction of the current flowing through the field winding 2 is switched, the armature 4 generates an induced voltage in the opposite direction to the polarity shown in FIG. 1, and a plugging current flows through the plugging diode 7.

FIG. 3 shows the output of the current detector 11 at this time, that is,
The potential at point C is shown.

First, the waveform in FIG. 3A is the voltage applied to the motor 3 with respect to time t. The waveforms in FIG. 3B show the field current I _F and the current I _P of the plugging diode 7 versus time t. The waveform in FIG. 3C shows the output of the differential amplifier 12, ie, the voltage at point C, with respect to time t, and the plugging detection level C of the voltage _e2 is the same as that in FIG. 2C.

In other words, during plugging braking, the difference between the forward current I _P of the field winding I _F and the plugging diode 7 is
indicates a negative value, and the output voltage of the differential amplifier 12 is the third
As shown in Figure C, the value is lower than the plugging detection level c. Thereupon, the comparator 25 detects that plugging braking is occurring, and discharges the charge in the capacitor 24 via the resistor 31.

At this time, the lower limit of discharge of the charge of the capacitor 24 is set by setting the output of the differential amplifier 12 to a value divided by the resistors 30 and 31, so that, for example, the plugging current I _{P is} If it is very large, the potential of the capacitor 24 is further lowered to reduce the conductivity, thereby preventing the difference between the plugging current I _P and the field current I _F from becoming extremely large.

The present invention has an excellent effect in that it is possible to accurately detect whether or not the plugging braking state is in place, with little influence from temperature.

Furthermore, the current flowing through the plugging diode when the motor is locked, etc., and the current flowing through the plugging diode during plugging braking are reliably distinguished.
This has the excellent effect that plugging can be accurately detected only during plugging braking. Furthermore, the second invention has the excellent effect of reliably eliminating shock during plugging.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram of an electric vehicle control device according to the present invention, FIGS. 2 and 3 are waveform diagrams of various parts in the electric circuit diagram of FIG. 1, and FIG. 4 is a current detection means shown in FIG. 1. The electrical equivalent circuit diagram of the magnetically sensitive element constituting the is shown. DESCRIPTION OF SYMBOLS 1... Chopper, 2... Field winding, 3... DC motor, 4... Armature winding, 5, 6... Forward/reverse changeover switch means, 7... Plugging circuit, 8...
...Flywheel circuit, 9...Accelerator means, 1
0... Chopper control circuit, 11... Current detection means, 12... Differential amplifier, 19... Soft start circuit, 25... Comparator, 32... Current limiting circuit, 33... Plugging diode short circuit failure detection circuit.

Claims (1)

[Scope of Claims] 1. Power is supplied to a DC series motor for driving an electric vehicle in which a field winding and an armature winding are connected in series through a chopper that operates intermittently and a main circuit opening/closing switch, and a plugging function is provided. In the electric vehicle control method, the current I _F flowing through the field winding is provided with a plugging diode in parallel with the armature winding.
and a current I _P flowing through the plugging diode, the current detecting circuit detecting a plugging operation when I _P ≧ _IF . car control method. 2. A DC series motor in which an armature and a field winding are connected in series, and a forward/reverse changeover switch that switches the direction of current flowing through the field winding of the DC series motor;
a chopper control device that controls power supplied to the DC series motor based on a command from an accelerator means; a plugging diode connected in parallel to an armature winding of the DC series motor; and a flywheel diode connected in parallel, the current I flowing through the field winding of the DC series motor.
The difference between _F and the current I _P flowing through the plugging diode is detected, and when I _P ≧I _F , plugging is determined, and the conductivity of the chopper control device is determined according to an increase in |I _F −I _P |. An electric vehicle control device characterized by lowering the rate. 3 In claim 2, the difference between the current I _F flowing through the field winding and the current I _P flowing through the plugging diode is detected, and I _F > I _P and |I _F −I An electric vehicle control device characterized in that when _P | becomes larger than a first reference value, an overcurrent is determined and the conductivity of the chopper control device is lowered. 4. In claim 2 or 3, detecting the difference between the current I _F flowing through the field winding and the current I _P flowing through the plugging diode,
When I _F > I _P and |I _F −I _P | becomes larger than the second reference value, it is determined that there is a short-circuit failure in the plugging diode, and the main circuit opening/closing switch is opened. An electric vehicle control device characterized by: