JPS6321121Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to an operation abnormality detection circuit for a speed control device for an electric vehicle, and in particular an operation abnormality detection circuit that determines whether a multi-stage switching element for controlling the speed of an electric vehicle is abnormal. Regarding.

FIG. 1 is a circuit diagram of a speed control circuit 10 for an electric vehicle that forms the background of this invention and is applied to this invention. In the figure, a main switch 12, resistors 13 and 14, a switch 15, and a motor 16 are connected in series to a plurality of storage batteries 11. The main switch 12 is linked to a key switch (not shown) of the electric vehicle. The switch 15 closes and supplies power to the motor 16 in response to operation of an accelerator (not shown). A thyristor 17, which is an example of first switching means, is connected in parallel to the resistor 13. The thyristor 17 short-circuits both ends of the resistor 13 by opening it after at least a predetermined time has elapsed since the switch 15 was closed.
In other words, the electric vehicle runs at a low speed even if the accelerator is depressed until at least a certain amount of time has elapsed since the switch 15 was closed. Resistance 13,
A thyristor 18, which is an example of second switching means, is connected in parallel to 14. Similarly, the thyristor 18 shorts out the resistors 13 and 14 by becoming conductive after at least a predetermined time T has elapsed since the thyristor 17 started being conductive. In other words, the electric vehicle runs at medium speed even if the accelerator is depressed until at least the predetermined time T has elapsed since the thyristor 17 started conducting. Thyristor 17, 18
As described above, a gate signal is applied from a gate signal generation circuit (not shown) automatically or in response to an accelerator operation after at least each predetermined time period.

In operation, when the key switch is operated,
Main switch 12 is closed. Subsequently, when the accelerator is depressed, the switch 15 is closed. Accordingly, the voltage of the storage battery 11, which has been stepped down by the resistors 13 and 14, is applied to the motor 16. For this reason, electric vehicles run at low speeds. switch 15
When the accelerator is depressed or is being depressed after a predetermined time has elapsed since the closing of the thyristor 17, the thyristor 17 becomes conductive and short-circuits the resistor 13. 11 voltages are applied. Therefore, electric vehicles run at medium speeds. Subsequently, when the accelerator is further depressed after a predetermined time T has elapsed since the thyristor 17 started conducting, the thyristor 18 becomes conductive and short-circuits the resistors 13 and 14, so that the voltage of the storage battery 11 is directly applied to the motor 16. Ru. Accordingly, the electric vehicle travels at high speed.

However, in the above-described circuit, if the thyristor 17 fails to fire due to breakage, for example, or an abnormality in the gate circuit, the resistors 13 and 14 will be short-circuited at once due to the firing of the thyristor 18. , an excessive current flows through the motor 16, causing heat generation and giving a large shock to the passengers. Therefore, when the above-mentioned phenomenon occurs, it is desirable to detect it and prompt the user to repair the device.

Therefore, the method of detecting whether each switching element is normal is to detect whether the switching element is connected in parallel with both ends of each resistor (in the figure, the connection points A and B, and between A and C, or between B and H). It is conceivable to detect the potential difference between points). That is, in this detection method, when the switch 15 is closed, the potential difference between points A and B or between points A and C on both ends of the resistors 13 and 14 becomes large, and the thyristors 17 and 18
This takes advantage of the fact that when conductive, the potential difference between points A and B or between points A and C becomes smaller.

However, this detection method can detect the operating state of a single stage switching element, but cannot detect the operating state of the first stage switching element when there are two switching elements. The reason for this is that even if thyristor 17 is abnormal, if thyristor 18 becomes conductive, the potential difference between point A and point B also decreases, so it is detected that thyristor 17 is also apparently normal.

Therefore, an object of the present invention is to provide an operation abnormality detection circuit that is inexpensive and has a simple circuit configuration and can easily detect abnormality in each switching element in a plurality of stages in a speed control circuit.

To summarize this invention, first detection means detects the conduction state of the first switching means connected in parallel to at least a first resistor, and at least first and second resistors connected in series are connected in parallel. A second detection means is provided for detecting the conduction state of the second switching means, and the delay means detects the conduction state of the second switching means.
The output of the first switching means is delayed by a predetermined time shorter than the predetermined time, and an abnormality of the first switching means is determined based on the fact that the output of the delay means is input after the output of the second detection means is received. This is what I did.

An embodiment of this invention will be described below with reference to the drawings.

FIG. 2 is a block diagram of an operational abnormality detection circuit 20 according to an embodiment of this invention. In the configuration, the first
The conduction state detection circuit 21, which is an example of the detection means, detects the conduction state of the thyristor 17,
An output signal is given to the delay circuit 23 in response to the potential difference between a point A and a point L at both ends of the resistor 13 connected in parallel with the thyristor 17 becoming zero. Delay circuit 23
is the output signal from the detection circuit 21 to the thyristor 1.
The D-type flip-flop 241, which is an example of the order discriminating circuit 24, delays the output signal from the D-type flip-flop 241, which is an example of the order discriminating circuit 24, by a predetermined time T1 shorter than the minimum predetermined time T from the start of conduction of the thyristor 7 until the thyristor 18 becomes conductive.
to the clock terminal (CL in the illustration).
Continuity state detection circuit 22 as an example of second detection means
is for detecting the conduction state of the thyristor 18, and the resistor 1 connected in parallel with the thyristor 18
In response to the potential difference between points A and C at both ends of 3 and 14 becoming 0, the output signal is sent to the D-type flip-flop 2.
41 data terminal (D in the illustration).

Note that the order determining circuit 24 may use other types of flip-flops or other logic circuits that can determine the order of input signals.

Here, the reason why the abnormality detection circuit 20 is configured as described above will be described. This is because the speed control circuit 10 is designed not to generate the firing signal for the thyristor 18 until at least a predetermined time T has elapsed since the firing signal for the thyristor 17 was generated. That is, thyristor 1
If 7, 18 and the gate signal generation circuit are normal, there will be a lag corresponding to at least time T in the decrease in the potential difference between points A and B and the decrease in the potential difference between points B and C, but if thyristor 17 is abnormal. This is to take advantage of the fact that in this case, there is no time lag in the decrease in the potential difference between points A and B and between points B and C. Another reason is that a normal order determining circuit using a flip-flop cannot determine the order in which the potential differences occur at both ends when the order in which the potential differences occur is the same.

FIG. 3 shows an output waveform diagram of each part of the operational abnormality detection circuit 20 of this embodiment. In particular, the solid line is the output waveform diagram of the thyristors 17 and 18 when the thyristors 17 and 18 are normal, and the dotted line is the output waveform diagram of the thyristor 17 when the thyristor 17 is abnormal. It is.

Next, the operation of this embodiment will be explained with reference to FIGS. 1 to 3. In addition, in the following setup, it is assumed that the accelerator pedal is fully depressed. First, a case where the thyristors 17 and 18 are normal will be described. In this case, main switch 1
2 and switch 15 are closed, motor 1
The voltage of the storage battery 11, which has been stepped down by resistors 13 and 14, is applied to 6. Then, at time t1, when a predetermined period of time has elapsed since the switch 15 was closed, the thyristor 17 becomes conductive. Accordingly, the voltage of the storage battery 11 , which has been stepped down by the resistor 14 , is applied to the motor 16 . At this time, since the potential difference between point A and point L is approximately 0, the detection circuit 21 provides an output signal detecting the conduction state of the thyristor 17 to the delay circuit 23 at time t1. Delay circuit 23
The output signal of the detection circuit 21 is delayed by a predetermined time T1 shorter than the predetermined time T from the time t1 when the thyristor 17 starts conducting to the time t2 when the thyristor 18 becomes conductive, and the output signal is sent to the D-type flip-flop 241. to the CL terminal of. Subsequently, a predetermined time T is elapsed from the firing time t1 of the thyristor 17.
At later time t2, the thyristor 18 becomes conductive. Accordingly, the voltage of the storage battery 11 is applied to the motor 16 . At this time, since the potential difference between point A and point C is almost 0, the detection circuit 22 detects the voltage at time t2.
Then, an output signal that detects the conduction state of the thyristor 18 is applied to the D terminal of the D-type flip-flop 241. Therefore, the D-type flip-flop 241 is
After the output signal of the delay circuit 23 is received, the detection circuit 2
Since the output signal of thyristor 2 is input, thyristor 1
7 and 18 are determined to be normal.

Next, a case where the thyristor 17 is abnormal will be described. In this case, when the main switch 12 and switch 15 are closed, the motor is
3 and 14, the voltage of the storage battery 11 is applied. Then, even at time t1, the thyristor 17 is not conductive because it is abnormal. Accordingly, the voltage of the storage battery 11, which has been stepped down by the resistors 13 and 14, is applied to the motor 16 at time t1 as well, so the potential difference between points A and B does not become zero. Therefore, the detection circuit 21 does not provide the delay circuit 23 with an output signal that detects the conduction state of the thyristor 17 at time t1. Subsequently, at time t2, the thyristor 18
becomes conductive. Accordingly, the voltage of the storage battery 11 is directly applied to the motor 16 . At this time, since the potential difference between point A and point C is almost 0, the detection circuit 2
2 outputs the output signal that detects the conduction state of the thyristor 18 at time t2 to the D flip-flop 241.
Give it to the terminal. Also, since the potential difference between points A and B and the potential difference between points B and C become almost 0 at the same time,
The detection circuit 21 provides an output signal that detects the conduction state of the thyristor 17 to the delay circuit 23 at time t2. The delay circuit 23 delays the detection signal of the detection circuit 21 by a predetermined time T1 from the time t2 when the thyristor 18 starts conducting, and outputs the output signal to D.
It is applied to the CL terminal of the flip-flop 241.
Therefore, since the output signal of the delay circuit 23 is inputted to the D-type flip-flop 241 after the output signal of the detection circuit 22 is received, the D-type flip-flop 241 determines whether there is an abnormality in the thyristor 17 and changes the output to a high level after time T1 from time t2. Derive an abnormal signal.

Incidentally, the abnormality signal derived from the D-type flip-flop 241 may be provided to a display or an alarm to inform the user.

In addition, in the above-mentioned embodiment, the case where only the output signal of the detection circuit 21 was delayed was explained.
The present invention is not limited to this, and the output signal of the detection circuit 22 may be delayed and used. In this case, assuming that the time for delaying the output signal of the detection circuit 22 is T2, the relationship between the delay time T1 and the predetermined time T is selected to be the relationship of the first equation.

T1-T2<T (1) Furthermore, in the above-described embodiment, the case where the number of switching elements in the speed control circuit is two was explained, but the present invention is not limited to this, and the present invention can also be used in a case where three switching elements are used. In this case, the detection signals that detect the conduction states of the switching elements in the first to third stages are a, b, and c, and the delay times of the detection signals a, b, and c are Ta, Tb, Tc, and detection Tab is the time interval between signals a and b, and detection signals b and c are
Let Tbc be the time interval, then the respective time relationships are selected as the relationships of the second to fourth equations.

Ta＜Tb＜Tc …(2) Ta−Tb＜Tab …(3) Tb−Tc＜Tbc …(4) Furthermore, in the above embodiment, the case where the operational abnormality detection circuit is installed in an electric vehicle was explained. However, the present invention is not limited to this, and it may be installed in a maintenance shop or a user's garage, for example, and used during periodic inspections or startup inspections.

As described above, according to this invention, the first detection means detects the conduction state of the first switching means connected in parallel to at least the first resistor, and the at least first and first switching means connected in series, respectively. a second detection means for detecting the conduction state of the second switching means connected in parallel to the second resistor;
The output of the first detection means is delayed by a predetermined time shorter than the predetermined time by the delay means, and after the output of the second detection means is received, the first switching is performed based on the input of the output of the delay means. Since abnormalities in the means are determined, abnormalities in each of the plurality of stages of switching means in speed control can be easily detected with a relatively simple circuit configuration. Furthermore, it can be easily determined whether the firing confirmation signal of the first switching means is generated by the first switching means or the second switching means.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a speed control circuit 10 for an electric vehicle that forms the background of this invention and is applied to this invention. FIG. 2 is a block diagram of an operational abnormality detection circuit 20 according to an embodiment of this invention. FIG. 3 is an output waveform diagram of each part of the abnormal operation detection circuit 20 of this embodiment. In the figure, 13 and 14 are resistors, 16 is a motor, 17 and 18 are thyristors, 21 and 22 are detection circuits, 23 is a delay circuit, and 241 is a D-type flip-flop.

Claims (1)

[Claims for Utility Model Registration] A motor for driving an electric vehicle by its rotational force, at least a first resistor and a second resistor each connected in series between a power source and the motor; a first switching means that is connected in parallel to one of the resistors connected in series, and supplies electric power necessary for running the electric vehicle at a relatively low speed from the power source to the motor by being electrically connected; The first switching means is connected in parallel to the first and second resistors, and is made conductive after a predetermined time has elapsed since the first switching means has been made conductive. a second switching means for supplying electric power to the motor; a first detection means for detecting a conduction state of the first switching means according to a voltage change across the first resistor; and a second resistor. a second detection means for detecting the conduction state of the second switching means in accordance with a voltage change across the second switching means; a delay means for delaying the output of the first detection means by a predetermined time shorter than the predetermined time; and an electric vehicle comprising abnormality determining means for determining that the first switching means is abnormal based on the input of the output of the delay means after the output of the second detection means is received. Abnormal operation detection circuit for speed control equipment.