JPS6333397B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a chopper control device that can minimize damage to a main motor and main circuit equipment even in the event of a grounding accident.

When a DC motor flashes over and causes a grounding accident, if protection is relied solely on the high-speed shatter-breaker, the mechanical delay in operation of the high-speed shatter-breaker will cause damage. Depending on the impedance conditions on the power supply side, the rise of the fault current is steep, and the peak value can reach an extremely large current value of 20,000A to 30,000A, causing significant damage to the DC motor and main circuit equipment. Sometimes.

Ground fault detectors and chopper controllers provide protection against fault currents much more quickly than high-speed shingle disconnects because they are electronic circuits. However, in the conventional method, the ground fault detector detects that the output level of the DC current transformer has reached the detection sensitivity level ΔI, and turns off the chopper at the same time as outputting the output signal. The situation in this case is shown in FIG. Figure 5a shows the grounding fault current, where the grounding fault current occurs at time _t1 ,
This shows that the current is interrupted by the chopper at time _t2 . Further, FIG. 5b shows the output of the ground fault detector, and FIG. 5c shows the chopper conduction rate, indicating that the chopper gate is turned off at time _t2 .

In addition, Figure 5d shows the filter capacitor voltage, and _Vs in the figure is approximately equal to the overhead wire voltage,
Vpeak indicates the peak value of the filter capacitor voltage, and indicates that the high speed circuit breaker opens at time _t3 . Furthermore, FIG. 5e shows the filter current, which shows that after time _t3, the current due to the high speed shunt breaker is cut off, and this current is attenuated.

As shown in FIG. 5, a resonance phenomenon occurs between the filter reactor and the filter capacitor, and the peak value Vpeak of the filter capacitor voltage becomes excessive, and there is a risk that the chopper portion CH or the capacitor itself may be damaged by overvoltage. For this reason, conventionally, the overvoltage of the filter capacitor has been suppressed by connecting a thyristor switch and a series resistor in parallel to the filter capacitor (not shown in the drawings).

However, adding an overvoltage suppression device for the filter capacitor increases the complexity of the structure and increases costs.

This invention was made in consideration of the above points, and provides sufficient protection for the main circuit and main motor against grounding accidents without adding an overvoltage suppression device for filter capacitors, and also simplifies the device and reduces costs. It is an object of the present invention to provide a chopper control device that is expected to achieve the following.

Embodiments of the chopper control device of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing the main circuit of an electric vehicle to which one embodiment of the present invention is applied. In this Figure 1, by collecting current from the pantograph PT, the current flows from the overhead line AE at high speed and passes through the disconnector HB, and then passes through a filter and chopper device consisting of a smoothing reactor LF and a smoothing capacitor FC.
CH, main smoothing reactor MSL, main motor armature
Current flows through the main circuit to ground via A ₁ , A ₂ and the main motor field windings F ₁ , F ₂ .

Furthermore, a freewheeling diode FD is connected in parallel to the series circuit of the main smoothing reactor MSL, the main motor armatures A ₁ , A ₂ , and the main motor field windings F ₁ , F ₂ . Furthermore, a DC current transformer DCCT ₁ is provided between _the high-speed shield breaker HB and the smoothing reactor LF.
The difference with the current value flowing through LF is detected, and the detected output is sent to the ground fault detector DFD.

Furthermore, a DC current transformer DCCT ₂ is provided between the output side of the chopper device CH and the main smoothing reactor MSL. This mainstream current transformer DCCT ₂ detects the output current of the chopper device CH, and the detected value is sent to the chopper gate control section 1, and the chopper conduction rate of the chopper device CH is determined from the chopper gate control section 1 accordingly. It's starting to be controlled.

The main controller 2 is configured to send a motor current command value Ip to the chopper gate control unit 1, and a control response time constant switching command is also sent from the ground fault detector DFD. The chopper gate control section 1 is configured to perform chopper current control on the chopper device CH based on the motor current value command Ip and the control response time constant switching command. And ground fault detector DFD
is designed to send an opening command to the high-speed disconnector HB.

FIG. 6 shows waveforms at various parts of the circuit shown in FIG. 1 during protection against a grounding fault. Fig. 6a shows the ground fault current detected by the DC current transformer DCCT ₂ , Fig. 6b shows the output of the ground fault detector DFD, and Fig. 6c shows the chopper conductivity of the chopper device CH, Figure 6d shows the voltage of the filter capacitor FC,
FIG. 6e shows the filter reactor current.

Now, in FIG. 1, when the main controller 2 sends a motor current value command and a control response time constant switching command from the ground fault detector DFD to the chopper gate control unit 1, based on that, the chopper gate control unit 1 switches the chopper. The chopper conduction rate is controlled in the device CH, and the output current of the chopper device CH is the current Ip shown in FIG. 6a.

In this state, when a ground fault occurs at time t ₁ , a ground current value flows from the main motor armature A ₁ to the ground, the fault current is detected by the DC current transformer DCCT ₂ , and the DC current transformer DCCT ₁ This detects the difference between the current value returning to the DC power supply side (that is, the overhead wire side) and the current value returning to the ground side of the DC power supply, and sends an output to the ground fault detector DFD.

Then, at time t ₂ , the DC current transformer DCCT ₂
When detects the ground fault current ΔIe, the chopper gate control unit 1 narrows down the chopper conduction rate as shown in FIG. 6c, and as a result, as shown in the period from time t ₂ to t ₃ in FIG. , Chiyotsupa device CH
The fault current is suppressed by And time t ₂
As the fault current ΔI _E flows, the voltage across the filter capacitor FC drops from the voltage Vs, which is approximately equal to the overhead wire voltage, as shown in Fig. 6d, and at the same time, the filter reactor current flowing through the filter reactor FL becomes It increases as shown in Figure 6e.

Then, at time t ₃ , the ground fault detector DFD
gives an opening command to the high-speed shatter-breaker HB, which opens the high-speed shatter-breaker HB and cuts off the current to the main circuit. This allows the filter reactor to
As shown in FIG. 6e, the FL current rapidly decreases, and as shown in FIG. 6a, the ground fault current also decreases. Thus, protection against grounding faults of the main circuit and the main motor is provided.

FIG. 2 shows a chopper gate control section 1 in a chopper control device of the present invention that performs the above-mentioned operation.
FIG. 2 is a block diagram showing the configuration of the device and its surroundings.
In FIG. 2, the same parts as in FIG. 1 will be described with the same reference numerals. In FIG. 2, a main circuit current I _M is detected by a DC transformer DCCT ₂ , and compared with a command current value Ip from a main controller 2 by a comparison amplifier circuit 3. The comparison amplifier circuit 3 has a control response time constant switching circuit, and is configured to switch the control response time constant based on a response time constant switching command from the ground fault detector DFD.

The comparison amplifier circuit 3 compares the current command value Ip from the master controller 2 with the detected value of the main circuit current I _M by the DC current transformer DCCT ₂ , amplifies the comparison result, and sends it to the phase shift circuit 4. Send. The phase shift circuit 4 changes the firing phase of the chopper device CH according to the output of the comparison amplifier circuit 3.The output of this phase shift circuit 4 is amplified by the chopper gate amplifier circuit 5, and then the chopper device Controls the firing phase of the CH thyristor and changes the conduction rate of the chopper device CH. In this way, the main circuit current I _M is controlled toward the current value command Ip from the master controller 2. _iM in Fig. 2 indicates the main circuit current.

On the other hand, if a ground fault occurs, the ground fault detector DFD detects the fault current. That is, the DC current transformer DCCT ₁ transforms the main circuit current and
The difference between the current value and the current value that returns to the ground side of the DC power supply through the main circuit is detected, and the detected output is sent to the ground fault detector DFD. As a result, the ground fault detector DFD issues a control response time constant switching command to the comparison amplifier circuit 3, and simultaneously issues an opening command to the high speed switch HB. When the response time constant switching command is sent to the comparison amplifier circuit 3, the control response time constant switching circuit in the comparison amplifier circuit 3 is switched, and a predetermined control response time constant is switched to a predetermined value.

Under normal conditions, the time constant of the comparison amplifier circuit is long to achieve stable main circuit current control, but
When a response time constant switching command is issued from the DFD, this response time constant switching command is sent to the relay AR shown in Figure 3 (described later).
It is now possible to switch to an operation that is very short. As a result, the chopper current flow rate of the chopper device CH is controlled extremely quickly, the increase in fault current is suppressed, the main circuit current I _M is controlled toward the current command value Ip, and the fault current is suppressed and interrupted. is several tens of meters
A high-speed circuit HB that opens after a delay of s is performed.

In this way, the filter reactor LF,
And if resonance does not occur in the filter capacitor FC, or even if it does occur, if the quick control response time constant after switching is set to an appropriate value, the peak value of the voltage Vc of the filter capacitor FC will be very small. The main circuit can be safely protected.

In addition, high-speed breakage of fault current
Even if the fault current value is suppressed by the chopper device CH, damage to the main motor and main circuit equipment can be kept to a minimum even if the fault current value is suppressed by the chopper device CH even if it takes a long time of several tens of milliseconds to rely on the forced trip.

FIG. 3 is a circuit diagram showing a detailed configuration of the comparison amplification circuit 3 of FIG. 2. In FIG. 3, the main motor current command value Ip from the main controller 2 and the detected current I _M from the DC current transformer DCCT ₂ are supplied to the operational amplifier OPA ₁ through the resistor R, respectively. A parallel circuit of a resistor R and a diode D is connected between the input and output terminals of the operational amplifier OPA ₁ , and the output of the operational amplifier OPA ₁ is supplied to the operational amplifier OPA ₂ through the resistor R.

A parallel circuit of a resistor R and a diode D is connected between the input and output terminals of the operational amplifier OPA ₂ .
The output of OPA ₂ is sent to phase shift circuit 4 in FIG.

Input of operational amplifier OPA ₁ and operational amplifier OPA ₂
Resistors R and R ₁ are connected in series between the output terminals of , and the connection point of both resistors R and R ₁ is a capacitor C ₁
A series circuit of capacitor C ₂ and relay AR contact AR ₁ (normally closed) is connected in parallel to _capacitor C 1 .

Further, the output of the ground fault detector DFD is connected to the base of a transistor TR via a resistor R, the emitter of this transistor TR is grounded, and a +24V voltage is applied to its collector via a relay AR. Diode D is connected in parallel to relay AR.

The transistor TR is a switching transistor, and the operational amplifiers OPA ₁ and OPA ₂ are the main components of the comparison amplifier circuit, and the control response time constant of the comparison amplifier circuit 3 is determined by the capacitors C ₁ and C ₂ and the resistor R ₁ . It is decided.

In the comparison amplifier circuit 3 of FIG. 3, under normal conditions, the relay AR is demagnetized and its contact AR ₁ is closed, so that the capacitors C ₁ and C ₂
are connected in parallel, and the control response time constant is
It is determined by R ₁ × (C ₁ + C ₂ ).

Next, a grounding accident occurs and the grounding accident detector
When an input signal is applied from the DFD, transistor TR is turned on, relay AR is energized, and its contact AR ₁ is opened. This disconnects capacitor C ₂ from capacitor C ₁ . As a result, the control response time constant is determined by (R ₁ × C ₁ ), and if the capacitance of each capacitor C ₁ and C ₂ is given so that C ₂ ≫ C ₁ , the excitation of relay AR The time constant of the later comparison amplifier circuit 3 becomes extremely short,
This allows for quick response control.

If a mercury relay is used, the operation time of the relay AR is extremely fast, about 1 ms, which is sufficient to satisfy the prompt operation required in the embodiment of the present invention described above.

The basic function of the comparison amplifier circuit 3 is to amplify the difference between the current pattern from the main controller 2, that is, the motor current value command Ip, and the main circuit current detected value I _M by the DC current transformer DCCT ₂ . , it goes without saying that the output thereof is given to the phase shift circuit 4 as a conduction ratio command signal.

FIG. 4 is a circuit diagram showing the detailed structure of the ground fault detector in the chopper apparatus of the present invention shown in FIGS. 1 and 2. FIG. In this Figure 4,
The output of the DC current transformer DCCT ₁ is applied to the inverting input terminal of the operational amplifier OPA 3 through a resistor R, and the auxiliary contact circuit of _the high-speed shatter breaker HB is applied through the resistor R to the non-inverting input terminal of the operational amplifier OPA ₃ . 6 output (off signal of high-speed disconnector HB) is supplied.

A resistor R is connected between the output terminal and the inverting input terminal of the operational amplifier OPA ₃ , and
The output end of OPA ₃ is grounded via two resistors R. Connection point of two resistors R and operational amplifier
A resistor R is also connected between the non-inverting input terminals of OPA ₃ . The output terminal of the operational amplifier OPA ₃ is connected via a resistor R to the base of the transistor TR ₁ .

The emitter of transistor _TR1 is grounded, and +24V voltage is applied to the collector via relay HBR. A diode D is connected in parallel to the relay HBR. The normally open contact HBR of the relay HBR is connected between the +24V power supply and the output terminal, and when contact HBR ₁ is closed, a high-speed disconnection occurs.
A trip command, that is, a contact opening command is now given to the HB. In addition, the above operational amplifier
An output is sent from the output end of OPA ₃ to comparison amplifier circuit 3 through diode D.

Next, the ground fault detector DFD shown in Fig. 4
The operation will be explained. As already mentioned, the DC current transformer DCCT ₁ is used in DC power supply circuits (overhead line AE)
The output is proportional to the difference between the current value flowing into the main circuit and the current value returning to this DC power supply through the normal circuit (i.e., the magnitude of the ground fault current value) with virtually no response delay. It occurs with such a fast response speed that it can be said that

When the output I _E of the DC current transformer DCCT ₁ exceeds the sensitivity level ΔI of the ground fault detection circuit DFD, the output of the operational amplifier OPA ₃ is reversed from negative to positive, and the positive potential of the operational amplifier OPA ₃ is reversed. The output is given to the comparison amplifier 3 mentioned above through diode D.

At the same time, the output of operational amplifier OPA ₃ turns on transistor TR ₁ , which turns on the relay.
HBR is energized and its contact HBR ₁ is closed,
An opening command is given to the high-speed disconnector HB. This operational amplifier OPA ₃ is activated when the main circuit contact of the high speed circuit breaker HB opens and the auxiliary contact (not shown) of the high speed circuit breaker HB operates.
A reset signal is applied from the auxiliary contact circuit 6 of the HB to restore the original state (normal state).

In addition, the operation delay time until the high-speed shatter-breaker HB opens due to the forced opening command varies depending on the mechanism of the high-speed shatter-breaker HB, and can be as fast as approximately 20 minutes.
ms, which is slow and approximately 100 ms.

As described above, according to the chopper control device of the present invention, the current in the main circuit including the chopper device and the main motor is detected by a DC current transformer, and the current in the main circuit is converted into a motor current value command of the main controller. The chopper gate control section controls the chopper conduction rate of the chopper device so that they are equal, and the difference between the current value of the main circuit and the current value that returns to the ground side of the DC power supply through this main circuit is calculated by another DC transformer. Depending on the presence or absence of the output value of the DC current transformer, the ground fault detector is operated to change the control response time constant of the chopper gate control section and trip the high-speed shatter-breaker to close the main circuit. Since the current is cut off, there is no need to add an overvoltage suppression device for the filter capacitor.
The main circuit and main circuit equipment can be sufficiently protected in the event of a grounding accident.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the chopper control device of the present invention, FIG. 2 is a block diagram showing the configuration of the chopper gate control section and related parts in the chopper control device of FIG. 1, and FIG. The figure is a circuit diagram showing the configuration of the comparison amplifier circuit in Figure 2, Figure 4 is a circuit diagram showing the configuration of the ground fault detection circuit in the chopper control device in Figure 1, and Figures 5a to 5e are respectively FIGS. 6a to 6e are waveform diagrams of various parts of the conventional chopper control device when protecting against a ground accident, and FIGS. 6a to 6e are waveform diagrams of various parts when protecting the chopper control device of the present invention from a ground accident. AE……Overhead line, PT……Pantograph, HB……
High-speed shield disconnector, LF...filter reactor,
FC...Filter capacitor, CH...Chopper device, MSL...Main smoothing reactor, _A1 , _A2 ...Main motor armature, _F1 , _F2 ...Main motor field winding,
DCCT ₁ , DCCT ₂ ...DC current transformer, DFD...Earth fault detector, TR, TR ₁ ...Transistor,
OPA ₁ ~ OPA ₃ ... operational amplifier, R, R ₁ ... resistance,
C ₁ , C ₂ ... Capacitor, AR, HBR ... Relay,
D... Diode, 1... Chopper gate control section, 2... Master controller, 3... Comparison amplifier circuit, 4
...Phase shift circuit. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A chopper device installed between a DC power supply and the main DC motor to supply current from the DC power supply to the main circuit mainly composed of the main DC motor, and a chopper device for detecting the current of the main circuit. 1, a DC current transformer, a master controller that commands the current value to be supplied to the main DC motor, and a high-speed transformer that is installed between the chopper device and the DC power supply and that cuts off when a grounding fault occurs in the main DC motor. A filter installed between the high-speed shield breaker and the chopper device detects the difference between the current flowing in the main circuit and the current value that returns to the ground side of the DC power supply through the main circuit. a second DC current transformer, when the second DC current transformer detects a grounding fault current by detecting the difference in the current values, it opens the high speed shield and sets the control response time constant; A ground fault detector outputs a switching command, and during normal current control of the main circuit, a ground fault detector outputs a switching command to the chopper device based on the output of the first DC current transformer and a motor current value command from the main controller. The conduction rate is controlled so that the current in the circuit becomes the motor current command value, and when a ground fault occurs in the main circuit, the control response time constant is set by receiving the control response time constant switching command from the ground fault detector. A chopper control device comprising a chopper gate control unit that controls the chopper control conductivity to change quickly by instantaneously switching to a short time constant. 2. The ground fault detector includes a first operational amplifier that outputs a control response time constant switching command output by inverting the output from negative to positive when the output of the second DC current transformer exceeds a predetermined value, and this first operational amplifier. A transistor that turns on when the operational amplifier generates a control response time constant switching command output, and a first relay that is energized when the transistor is turned on and outputs an opening command to the high-speed disconnector. The chopper control device according to claim 1, characterized in that: 3 During normal control of the main circuit current, the chopper gate control section compares and outputs the motor current command value from the main controller with the main circuit current value detected by the first DC transformer, and also outputs the result from the above grounding. A comparison amplifier circuit that switches the control response time constant in response to a control response time constant switching command from the ground fault detector when an accident occurs, a phase shift circuit that shifts the phase of the output of this comparison amplifier circuit, and amplifies the output of this phase shift circuit. 3. The chopper control device according to claim 1, further comprising a chopper gate amplifier circuit for amplifying the current in order to control the conduction rate of the chopper device. 4 The comparison amplifier circuit is a second relay that is demagnetized during normal control of the current in the main circuit and is energized by the control response time constant switching command from the above ground fault detection when a ground fault occurs, and has a large time constant during the above normal control. control response time constant switching means that switches to a small time constant by the second relay when a grounding accident occurs; 4. The chopper control device according to claim 3, further comprising a comparison amplifier circuit that compares and outputs the detected value of the main circuit current from the first DC transformer.