JPS63178701A - Ac motor car - Google Patents

Abstract

PURPOSE:To improve reliability of a power-factor compensating circuit by compensating for malfunction of a thyristor performing connection and disconnection of said power-factor compensating circuit. CONSTITUTION:AC power received from a trolley wire via a pantograph 1 is transformed by a transformer via a make and break switch 2 and, after rectification by a rectifier 5, supplied to armatures A1, A2 and fields F1, F2 via a reactor MSL. An electric motor is controlled by a firing angle control of thyristors TH3, TH4 of the rectifier 5. A capacitor C is provided for power- factor improvement, and a primary current of transformer 4 is detected by a current transformer 3 and a primary voltage thereof, by a transformer PT1. If a phase difference between them grows larger, thyristors TH1, TH2 are ignited to conduct a power-factor control. If said thyristors TH1, TH2 are out of order, an electric current flowing through the capacitor C and a firing command for the thyristors TH1, TH2 do not coincide with each other. Therefore, said malfunction is detected by a malfunction detection circuit 11 and the make and break switch 2 is opened.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an electric vehicle driven by AC power, and particularly relates to a fault detection circuit section in a compensation circuit that compensates for the power factor of input power. This relates to an improved AC electric car.

(Prior technology) A system that receives pantograph or bow AC power from a line, converts the voltage with a transformer, then converts the AC to DC with a rectifier, and uses this DC output to drive the DC motor that is the power source for electric vehicles. It becomes. In recent vehicles, voltage control is performed to control the speed of the electric motor, and this often uses a phase control method using a thyristor. Therefore, a phase difference between voltage and current occurs, which is one of the factors that worsens the power factor of AC power.

Such a deterioration in the power factor of AC power not only increases unnecessary heat loss in the power system, but also leads to an increase in the capacity of power plants and substations. Therefore, it is desired to improve the power factor based on the phase difference between voltage and current in AC power when performing phase control using a thyristor.

Therefore, one possible solution is to connect a power factor compensation capacitor in parallel to the secondary winding of the transformer to which the rectifier of the AC electric vehicle is connected.

However, with this method, if the power factor compensation capacitor is always connected to the secondary winding of the transformer, even though the phase-advanced current flowing through this circuit is a constant value, it cannot be used as the drive source of the electric car. The effective power generated changes depending on the operating conditions such as the speed of the electric car, so for example, when the electric car is stopped,
This results in only a phase-advanced current, leading to an unnecessary increase in AC voltage.

For this purpose, a switch can be installed in series with the capacitor to open and close this circuit, and the capacitor circuit can be connected or opened according to the active power used by the electric vehicle, but this switch is made of a semiconductor element such as a thyristor. This method is common.

(Problem to be solved by the invention) In this way, most AC electric cars receive AC power from AC overhead wires, convert the voltage with a transformer, and then convert the AC into DC with a rectifier. It is a system that drives a DC motor, and performs voltage control to control the speed of the motor.

Since this control often uses a phase control method using a thyristor, a phase difference occurs between the voltage and the current, which deteriorates the power factor of the AC power.

Such deterioration of the power factor of AC power increases unnecessary heat loss in the power system and also increases the capacity of power plants and substations. It is necessary to improve the power factor based on the phase difference, and as a measure to do so, a capacitor for power factor compensation is connected in parallel to the secondary winding of the transformer to which the rectifier of the AC electric car is connected. However, with this method, if the power factor compensation capacitor is always connected to the secondary winding of the transformer, even though the phase-advanced current flowing through this capacitor circuit is a constant value, The active power varies depending on operating conditions such as the speed of the electric car. For example, when the electric car is stationary, only phase-advanced current is generated, leading to an unnecessary increase in the AC voltage.

For this purpose, a switch is installed in series with the capacitor to open and close the capacitor circuit, and the capacitor circuit is connected and opened according to the active power used by the electric vehicle.This switch is constructed using semiconductor elements such as thyristors. is taken.

However, in this case, if the semiconductor element malfunctions,
The power factor compensation capacitor circuit may be connected in parallel to the transformer's secondary winding during periods when it is not needed, causing the AC voltage to rise, or conversely, it may not be connected to the transformer's secondary winding when it is needed, causing a lagging phase. The reactive current may increase and the voltage drop of the AC voltage may become too large.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an AC electric vehicle that can compensate for the malfunction of the thyristor inch that connects and disconnects the power factor compensation circuit, thereby increasing the reliability of the power factor compensation circuit. The aim is to provide electric cars.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention is configured as follows. That is, after AC power received from an AC supply line is transformed by a transformer, the AC power is converted into AC power by a rectifier whose output voltage can be controlled and which is formed by a semiconductor element whose firing angle can be controlled.
This DC output is used to drive the DC motor, which is the power source for the electric car, and is also connected in parallel to the secondary side of the transformer to connect and disconnect the capacitor for power factor compensation. Detecting the capacitor current of the power factor compensation circuit in an AC electric vehicle equipped with a power factor compensation circuit including a semiconductor switch that is connected in series with the capacitor and whose ignition is controlled according to the phase difference between the primary side voltage and current of the transformer. and a determining means for outputting a failure occurrence determination signal when only one of the ignition control signal of the semiconductor switch and the capacitor current detection signal of the detection means is -〇-. and abnormality detection means for generating a cutoff signal for cutting off the power receiving side when the signal is output.

(Function) In such a configuration, after the AC power received from the AC supply line (AC overhead line) is transformed by a transformer, the rectifier means is formed of a semiconductor element that can control the firing angle and is capable of variable output voltage control. converts AC to DC, and this DC output drives the DC motor, which is the power source for the electric car. In addition, the output voltage variable control rectifying means, which is formed by a semiconductor element that can control the firing angle, performs AC-DC conversion in the form of phase control, and controls the voltage of the DC conversion output to control the speed of the motor. Therefore, since the power factor of the AC power deteriorates depending on the operating condition, a capacitor for power factor compensation is connected in parallel to the secondary side of the transformer to compensate for the power factor depending on the operating condition. The connection and disconnection of this capacitor is controlled by a semiconductor switch connected in series with the capacitor and whose ignition is controlled according to the phase difference between the voltage and current on the primary side of the transformer. If this power factor compensation capacitor is always connected to the secondary winding of the transformer, even though the phase-advanced current flowing through this capacitor circuit is a constant value, the active power that serves as the driving source for the electric car is changes depending on the operating conditions such as the speed of the electric car. For example, when the electric car is stationary, there will only be a leading phase current, which will lead to an unnecessary increase in the AC voltage.
Here, a switch is installed in series with capacitor C to open and close this capacitor circuit, and the capacitor circuit is connected and opened according to the active power used by the electric vehicle, so the power factor can be increased without causing such a situation. becomes possible.

However, since this switch is composed of a semiconductor element such as a thyristor, if the semiconductor element malfunctions, the power factor compensation capacitor may be connected in parallel to the secondary winding of the main transformer during an unnecessary period, causing the AC voltage to rise. or conversely, the secondary winding of the main transformer may not be connected when necessary, resulting in an increase in reactive current in the lagging phase and a large voltage drop in the AC voltage.

This device is equipped with abnormality detection means and constantly monitors for such abnormalities. In other words, the state is normal when both the ignition control signal of the semiconductor switch and the capacitor current are present, and the state where there is no ignition control signal and no capacitor current is flowing to the semiconductor switch, and any other state is abnormal. become. Therefore, the capacitor current of the power factor compensation circuit is detected by the detection means, and this and the ignition control signal of the semiconductor switch are monitored by the determination means, and when only one of these signals is present, it is determined that a failure has occurred. Output a signal. Then, when there is a failure occurrence determination signal from the determining means, the above-mentioned cutoff signal for cutting off the power receiving side is generated to cut off the power receiving side. Thereby, in the event of an abnormality in the power factor compensation circuit, the main circuit can be cut off to protect the AC power system.

Therefore, according to the present invention, in an AC electric vehicle that is provided with a power factor compensation circuit to improve the power factor and connects or disconnects the power factor compensation circuit depending on the driving condition, a semiconductor switch that connects or disconnects the power factor compensation circuit is provided. Therefore, it is possible to provide an AC electric vehicle that can compensate for malfunctions of the power factor compensation circuit and dramatically improve the reliability of the power factor compensation circuit.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

The case shown in FIG. 2 can be considered as a malfunction mode of the si-risk switch that connects and disconnects the power factor compensation circuit in an AC electric vehicle. In other words, Fig. 2(a) shows the case where there is a gate signal for the thyrisk switches TH1 and TH2 but no current flows, and Fig. 2(b) shows the case where no current flows even though there is no gate signal for the thyrisk switches TH1 and TH2. ■１
FIG. 2(C) shows a case where an excessive current 2 flows due to the turning on of the thyrisk switches TH1 and TH2.

If you organize these things, you can see that the on haiku name of Cyrisk Switch (
When the capacitor current (gate signal for ignition) and the capacitor current match, and there is no on signal at the si-risk switch, and
A state in which no capacitor current flows is normal, and anything other than this indicates that an abnormality has occurred.

Furthermore, it is clearly abnormal for an overcurrent to flow.

Therefore, in this system, the thyristor switch has a gate signal and there is a capacitor current, or the thyristor switch has no gate signal and there is no capacitor current, which is considered normal, and the thyristor switch has no gate signal. , and when there is a capacitor current, or there is a gate signal on the thyrisk switch, and there is no capacitor current, or there is an abnormally large current in the capacitor, it is judged as abnormal, and the power of the AC electric car is determined. To improve the reliability of a power factor compensation circuit by compensating for malfunction of a si-risk switch that connects and disconnects the power factor compensation circuit.

Figure 3 shows the above expression in a diagram, and shows the capacitor current Ic of the power factor compensation capacitor C and the control circuit CNT.
Exclusive OR (Exclusive OR) of the gate signal G given to the sirisk switch TH1゜TI-(2). Only when there is a discrepancy, a signal (""
In addition, the overcurrent detection circuit D
If any one of the signals is ORed with the signal I, a failure detection signal S is output.

In this way, the capacitor current 1c and the control circuit CN
T to Cyrisk switch THI.

When the exclusive OR of the gate signal G applied to TH2 is established, that is, when both signals match at the logic level ``H'' or 1L L I+, the signal LL H1
1, and by using this signal as the failure detection signal of the SI risk switch and passing the signal of the overcurrent detection circuit DI through an OR gate, it is possible to obtain the failure detection signal S in the abnormal state.

FIG. 1 is a circuit diagram showing an embodiment of the present invention. 1 in the diagram
2 is a pantograph (current collector) of an AC electric vehicle, and 2 is an on/off switch for opening/closing AC power received via the pantograph 1. Reference numeral 3 indicates a current transformer for detecting the AC input current provided on the rear side of the on/off switch 2, and 4 indicates the main transformer of the electric car. Transformed. Pl is the primary winding of the main transformer 4, and sl is the secondary winding of the main transformer 4. 5 is a rectifier for rectifying the output of the secondary winding s1 of the main transformer 4, and includes thyristors TH3 and TH4 and diodes D1. It is configured by connecting D2 in a bridge manner.

The rectified output beam of the rectifier 5 is connected to the armatures AI and A2 of the electric motor for driving the electric vehicle and the electric motor field F1 through the accelerator MSL.
．． Supplied to F2.

In addition, a power factor compensation circuit 6 is connected between the terminals of the secondary winding S1 of the main transformer 4, and is constituted by a series circuit consisting of thyristors THI and TH2 connected in antiparallel, a compensation capacitor C, and a reactor L. has been done. Note that CT is a current transformer that detects the current flowing through the power factor compensation circuit 6.

PTl is the mark -'+ of the secondary winding P1 of the main transformer 3.
3- A transformer connected in parallel to the secondary winding P1 to detect the applied voltage, and the output of this transformer PTI and the output of the current transformer 3 are the voltage and current levels on the primary side. The signal is applied to a phase difference detection circuit 7 that detects a phase difference and outputs a signal with a level corresponding to the phase difference.

8 is a level detection circuit that compares the output level of this phase difference detection circuit 7 with a reference value, and 9 is this level detection circuit 8.
This is a gate signal generation circuit that generates a gate signal for firing a thyristor according to the output of the thyristor. Reference numeral 10 denotes a gate signal generating circuit which amplifies the gate signal outputted from the gate signal generating circuit 9 and applies it to the thyristor TH1.about.7H2 for ignition control.

Reference numeral 11 denotes a thyrisk switch (thyristor TH1, TH2) in the power factor compensation circuit 6 that connects and disconnects the power factor compensation circuit 6.
This is an abnormality detection circuit that detects a malfunction in ), and utilizes the configuration explained in FIG.

That is, it is detected by the current transformer CT, and the rectifier 12
The capacitor current 1c of the power factor compensating capacitor C rectified by
Exclusive OR circuit EX that takes the exclusive OR of
OR, take the OR logic with the signal of the overcurrent detection circuit DI,
It consists of an OR gate OR which outputs a failure detection signal S. The overcurrent detection circuit DI compares the capacitor current Ic of the power factor compensation capacitor C rectified by the rectifier 12 with a set reference value to detect whether or not an overcurrent is flowing. It outputs an overcurrent detection signal when the

Next, the operation of this device having the above configuration will be explained.

AC power received from an overhead wire via the pantograph 1 is transformed by a main transformer 4 via an on/off switch 2. The transformed output of the main transformer 4 is rectified by the rectifier 5, and then passed through the reactor MSL to the armature A1. A2 and motor field F1. Supplied to F2. This rectifier 5, which rectifies the output of the secondary winding S1 of the main transformer 4, is constructed by connecting thyristors TH3 and TH4 and diodes D1 and D2 in a bridge connection. Therefore, by controlling the firing angles of the thyristors TH3 and TH4 of the rectifier 5 with a controller (not shown) linked to a mask controller in the driver's cab, the rectified output voltage can be controlled and the speed of the electric motor can be controlled. ' In this way, an AC electric car receives AC power from an AC overhead wire, converts the voltage with a transformer, and then converts the AC into DC with a rectifier to drive the DC motor that is the power source of the electric car. Then, voltage control is performed to control the speed of the electric motor.

This voltage control uses a phase control method using a thyristor. Therefore, depending on the operating conditions, a phase difference between the voltage and current occurs, which deteriorates the power factor of the AC power.

Therefore, in order to improve the power factor by reducing the phase difference between the voltage and current in AC power when performing phase control using a thyristor, the main transformer 4 to which the rectifier 5 of the AC electric car is connected is adjusted depending on the operating conditions. A power factor compensation capacitor C is connected in parallel to the secondary winding S1. This is done by controlling the ignition of the thyristors TH1 and TH2 of the power factor compensation circuit 6.

Thereby, the power factor of AC power can be improved.

That is, the primary side voltage of the main transformer 4 is detected by the transformer PT1, and the negative side current is detected by the current transformer 3.
These are supplied to a phase difference detection circuit 7, and the phase difference is detected. The level of this phase difference is detected by a level detection circuit 8, and the level detection circuit 8 generates a signal when the phase difference exceeds a certain value, that is, when the phase difference exceeds a certain value. Then, based on this signal, the gate signal generation circuit 9 generates a gate signal for firing the thyristor, which is amplified by the gate signal amplification circuit 10 and then passed through the thyristor switch TH.
1, to TH2 and ignite it. This causes current to flow through the capacitor C and reactor L. As a result, current flows through the capacitor C, and the phase of the AC power on the primary side of the main transformer 4 moves in the advancing direction, resulting in an overall reduction in the phase difference and an improvement in the power factor. Further, the reactor L-17= is provided to determine the resonant frequency of this circuit, and the capacitor C is considerably larger in terms of AC impedance.

Furthermore, if a power factor compensation capacitor is always connected to the secondary winding of the transformer, even though the phase-advanced current flowing through this capacitor circuit is a constant value, it becomes an effective driving source for the electric vehicle. Since electric power changes depending on the operating conditions such as the speed of the electric car, for example, when the electric car is stopped, there will only be phase-advanced current, leading to an unnecessary increase in AC voltage, but with this method, A switch is installed in series with capacitor C to open and close this capacitor circuit, and the capacitor circuit is connected and opened according to the active power used by the electric vehicle, so it is possible to increase the power factor without causing such a situation. It becomes possible.

However, since this switch is composed of a semiconductor element such as a thyristor, if the semiconductor element malfunctions, the power factor compensation capacitor C is connected in parallel to the secondary winding of the main transformer 4 during an unnecessary period. The AC voltage may rise, or conversely, it may not be connected to the secondary winding of the main transformer 4 when necessary, and the reactive current of the lagging phase may increase, resulting in an excessive voltage drop in the AC voltage.

This device is equipped with an abnormality detection circuit 11 that constantly monitors such abnormalities.

As shown in Figure 2, the modes of failure of the thyristor switch in the power factor compensation circuit 6 are (a) when there is a gate signal for the thyristor switches TH1 and Tl-12 but no current flows; (b) when the thyristor switch There are three cases: (C) a case where current (1) flows even though there is no gate signal of TH1, TH2, and (C) a case where an excessive current I2 flows due to turning on of thyristor switches TH1, TH2.

Putting these things in perspective, it is normal when the thyristor switch's on signal matches the capacitor current, there is no on signal (gate signal for ignition) at the thyristor switch, and no capacitor current is flowing. , anything other than this means that an abnormality has occurred. Additionally, it is clearly abnormal that an overcurrent flows.

Therefore, in the abnormality detection circuit 11, the case where the thyrisk switch has a gate signal and there is a capacitor current, or the thyrisk switch has no gate signal and there is no capacitor current is considered normal; An abnormality is determined when there is no gate signal and there is a capacitor current, or there is a gate signal at the thyrisk switch and there is no capacitor current, or there is an abnormally large current in the capacitor.

Therefore, the capacitor current 1 of the power factor compensation capacitor C is
c and the thyrisk switch THI from the gate signal generation circuit 9 on the control circuit side that controls the firing of the thyrisk switches TH1 and TH2.

The exclusive OR circuit EXOR takes the exclusive OR of the gate signal G applied to TH2. When this exclusive OR is established, that is, when both signals match at the logic level 11811 or L'', the logic output ii L'' is normal, and when they do not match, the logic output 11 HT+ is the abnormality of the thyristor switch. This is the detection output.

On the other hand, the capacitor current Ic of the power factor compensation circuit 6 detected and rectified by the current transformer CT is also given to the overcurrent detection circuit DI of the abnormality detection circuit 11, and the overcurrent detection circuit D
I outputs an output when the capacitor current 1c of the power factor compensation circuit 6 shows an abnormal value (this occurs, for example, when the capacitor is short-circuited) by comparing it with a preset reference value.

Since the logical output of EXOR (abnormality detection output) and the output of the overcurrent detection circuit DI are used as the output of the abnormality detection circuit 11, the abnormality detection circuit 11 uses exclusive OR
The output of the circuit EXOR and the signal of the overcurrent detection circuit DI are connected to O.
It is obtained as a failure detection signal S through the R gate.

As a result, the capacitor current IC and the thyrisk switch T
)-11, 7H2 is absent, and when the capacitor current 1c becomes an overcurrent, a failure detection signal can be obtained. and,
Opening/closing switch 2 is opened in response to this failure detection signal (by cutting off from the AC system when an abnormality occurs in power factor compensation circuit 6, such as an abnormality in the sirisk switch or an overcurrent in the capacitor current). It is possible to prevent adverse effects on the AC system, such as abnormal increases or decreases in AC voltage due to failure or abnormal operation of the power factor compensation circuit of the AC electric vehicle.

Here, the operation will be explained using a specific example.

When the power factor compensation circuit 6 is operating normally, the capacitor current IC flows at a normal level or does not flow at all. This is detected by current transformer CT. This detection output is rectified by the rectifier circuit 12, and in the former case it becomes a level "1 HII" signal, and in the latter case it becomes a level "L" signal and is given to the exclusive OR circuit EXOR. In the former case, a gate signal is given to the switches TH1 and TH2, and in the latter case, no gate signal is given, so the inputs of the exclusive OR circuit EXOR are both at the level "'H".
Or the level becomes "L". Since it is normal, there is no output from the overcurrent detection circuit DI, so the OR of these is
There is also no gate OR output.

Next, a case where the power factor compensation circuit 6 becomes abnormal will be explained. Here, the failure mode is the thyrisk switch TH1, T.
Consider an example in which one or both of H2 does not fire.

For example, if the thyrisk switch TH1 does not fire, only the thyrisk switch TH2 will fire, so the capacitor current 1c flowing through the capacitor C will be in only one direction, and therefore the capacitor C will be charged to the maximum value of the AC voltage. After that, no current will flow.

Furthermore, when both thyrisk switches TH1 and TH2 are in a non-firing state, no current flows, so as a result, the output of the current transformer CT disappears, and the output of the rectifier circuit 12 that rectifies this detection output is at level 11. It becomes a signal of L11 and is applied to the exclusive OR circuit EXOR. On the other hand, since the gate signal is given to the thyrisk switches TH1 and TH2, the exclusive OR circuit EXOR17) input cover L/H/1. z
Therefore, the output of the exclusive OR circuit EXOR becomes the level "Ht+".Therefore, the output of the OR gate OR becomes the level "HI+".
It is output as an abnormality detection signal, and the open/close switch 3 is operated to shut off.

In addition, as another failure mode, thyristor switch TH1
, TH2, or both have a short-circuit failure.

In this case, since current always flows through the capacitor C and the reactor, a current detection output is output from the current transformer CT. Therefore, a rectifier circuit 12 that rectifies this detection output
The output becomes a signal of level it H'' and is applied to the exclusive OR circuit EXOR. On the other hand, depending on the operating conditions, the cyrisk switch TH1, TH2
On the other hand, at the point when the gate signal is no longer applied, the inputs of the exclusive OR circuit EXOR become levels H" and "L", and therefore the output of the exclusive OR circuit EXOR becomes level "H". .

Therefore, the output of the OR gate OR becomes level "H" and is output as an abnormality detection signal, and the open/close switch 3 is cut off.

Furthermore, if the current of the capacitor C shows an abnormal value, the output of the overcurrent detection circuit DI becomes level "H", so an abnormality detection signal is output from the OR gate OR, and the opening/closing switch 3
is shut off.

As a result, the capacitor current IC and the thyrisk switch T
When only one of the gate signals G is applied to H1 and TH2, and when the capacitor current IC becomes an overcurrent, a failure detection signal can be obtained. By opening the on/off switch 2 in response to this failure detection signal, when an abnormality occurs in the power factor compensation circuit 6, such as an abnormality in the silisk switch or an overcurrent in the capacitor current, the AC system can be cut off. It is possible to prevent adverse effects on the AC system, such as abnormal increases or decreases in AC voltage due to failure or abnormal operation of the power factor compensation circuit of the AC electric vehicle.

Therefore, the reliability of the power factor compensation circuit provided in the main circuit of the AC electric vehicle can be improved.

〔Effect of the invention〕

As detailed above, according to the present invention, the reliability of the power factor compensation circuit can be improved by compensating for the malfunction of the si-risk switch that connects and disconnects the power factor compensation circuit of an AC electric vehicle. AC electric vehicles can be provided.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2 is a diagram for explaining an example of abnormal operation of a si-risk switch in a power factor compensation circuit, and Fig. 3 is an abnormality detection for detecting the abnormal operation. FIG. 2 is a block diagram showing an example of the configuration of a circuit. 1... Pantograph (current collector), 2... Open/close switch, 3... Current transformer, 4... Main transformer, 5... Rectifier, 6... Power factor compensation circuit, 7...・・Phase difference detection circuit,
8... Level detection circuit, 9... Gate signal generation circuit, 10... Gate signal generation circuit, 11... Abnormality detection circuit, THL.

Claims (1)

[Claims] AC power received from an AC supply line is transformed by a transformer, and then converted from AC to DC by a rectifier that can control the variable output voltage and is formed by a semiconductor element that can control the firing angle.
This DC output drives the DC motor that is the power source of the electric car, and the capacitor is connected in parallel to the secondary side of the transformer to compensate for the power factor, and the capacitor is connected in series to connect and separate it. Detecting means for detecting a capacitor current of the power factor compensation circuit; and and determining means for outputting a failure occurrence determination signal when only one of the ignition control signal of the semiconductor switch and the capacitor current detection signal of the detection means is present, and the power receiving side An AC electric vehicle characterized in that it is equipped with an abnormality detection means that generates a disconnection signal.