WO2019187454A1

WO2019187454A1 - Electric vehicle drive system, semiconductor current reducer, and failure detection method therefor

Info

Publication number: WO2019187454A1
Application number: PCT/JP2018/048453
Authority: WO
Inventors: 航成木; 正登安東
Original assignee: 株式会社日立製作所
Priority date: 2018-03-27
Filing date: 2018-12-28
Publication date: 2019-10-03
Also published as: JPWO2019187454A1; JP7016949B2

Abstract

A control device for an electric vehicle drive system, configured so as to: commutate an overcurrent to at least one resistance in a resistance section, by switching off a semiconductor switch element (connected in series to a circuit breaker and an inverter), if an overcurrent is detected; and to cut off the commuted and reduced current by turning off the circuit breaker. The electric vehicle drive system has: a first current detector for detecting overcurrent; and a second current detector for detecting the value of a current that flows through either a semiconductor switch element or the resistance section in a semiconductor current reducer. The control device detects that the semiconductor switch element has failed if a prescribed condition is satisfied that has been applied to a current value, said current value: being the current value obtained by at least the second current detector; and being for the current flowing through the resistance section.

Description

Electric vehicle drive system, semiconductor current reducer, and failure detection method thereof

The present invention generally relates to a semiconductor current reducer for a drive system for an electric vehicle (railway vehicle).

A drive circuit for an electric vehicle is generally provided with a current breaker. As an example of a current breaker, for example, current breakers disclosed in

Patent Documents

1 and 2 are known.

JP 2004-096877 A JP 2006-067732 JP

The inventor of the present application diligently studied the practical application of a drive system for an electric vehicle in which a semiconductor current reducer was adopted as a current breaker and the filter reactor was miniaturized. As a result, the following knowledge was obtained.

A drive system for an electric vehicle generally has a filter reactor. The filter reactor plays a role of reducing pulsation of current and voltage generated during traveling and suppressing a large short-circuit current from flowing from the overhead line when a high potential and a low potential are short-circuited in the main circuit. The inductance value necessary for such a role is generally 8 mH to 12 mH, and therefore the volume and mass of the filter reactor are large. For example, the volume and mass of the filter reactor occupy about 1/2 to 1/3 of the entire drive system except for the motor.

Therefore, if the filter reactor can be downsized, it contributes to downsizing of the entire drive system.

In order to reduce the size of the filter reactor, it is necessary to set the inductance value small. However, if the inductance of the filter reactor is reduced, the rate of increase in the accident current when a ground fault or the like occurs increases, and if the current breaker is a general mechanical high-speed breaker, Will become bigger. This can make the operation of the substation unstable, such as a tripping breaker in the substation.

The current breaker installed in the drive system for electric vehicles is required to have high reliability and safety.

Patent Documents

1 and 2 disclose a configuration in which a semiconductor current reducer is applied to a drive system for an electric vehicle.

However,

Patent Documents

1 and 2 disclose that the size of the filter reactor and the inflow of a large current are suppressed in the practical application of the electric vehicle drive system in which the semiconductor current reducer is adopted as a current breaker and the filter reactor is miniaturized. There is no disclosure or suggestion of a technology that achieves both.

Patent Documents

1 and 2 neither disclose nor suggest a technique for maintaining the reliability and safety of a semiconductor current reducer employed as a current breaker.

Therefore, an object of the present invention is to maintain the reliability and safety of the semiconductor current reducer while simultaneously reducing the size of the filter reactor and suppressing the inflow of a large current.

When the control device of the electric vehicle drive system detects an overcurrent, the semiconductor switch element in the semiconductor current reducer (semiconductor switch element connected in series with the current breaker and the inverter) is turned off to turn off the overcurrent. The current is commutated to at least one resistance in the resistance section, and the current that has been commutated and reduced by the at least one resistance is cut off by turning off the current breaker. In addition to the first current detector for overcurrent detection, the electric vehicle drive system includes a second current for detecting a current value flowing through one of the semiconductor switch element and the resistor in the semiconductor current reducer. A detector is provided. If the predetermined value provided for the current value of the current flowing through the resistance portion is satisfied, at least if the current value obtained on the basis of the second current detector is satisfied, the control device breaks down the semiconductor switch element. It is detected that

According to the present invention, it is possible to maintain the reliability and safety of the semiconductor current reducer while simultaneously reducing the size of the filter reactor and suppressing the inflow of a large current.

1 is a configuration diagram of an electric vehicle drive system according to Embodiment 1. FIG. It is a waveform chart which shows the switching operation in the drive system for electric vehicles described in FIG. It is a waveform chart which shows the switching operation in the drive system for electric vehicles described in FIG. It is a waveform chart which shows the switching operation in the drive system for electric vehicles described in FIG. It is a waveform chart which shows the switching operation in the drive system for electric vehicles described in FIG. It is a waveform chart which shows the switching operation in the drive system for electric vehicles described in FIG. FIG. 6 is a configuration diagram of an electric vehicle drive system according to a second embodiment. FIG. 6 is a configuration diagram of an electric vehicle drive system according to a third embodiment. FIG. 10 is a diagram illustrating an arrangement example of a second current detector in the electric vehicle drive system according to the fourth embodiment. It is a figure which shows the example of arrangement | positioning of the structure of the semiconductor current reducer in the drive system for electric vehicles which concerns on Example 5, and a 2nd current detector. It is a figure which shows the example of arrangement | positioning of the structure of the semiconductor current reducer in the drive system for electric vehicles which concerns on Example 6, and a 2nd current detector.

In the following description, when it is necessary for the sake of convenience, the description will be divided into a plurality of sections or examples, but they are not irrelevant unless otherwise specified, and one is part of the other. Alternatively, all the modifications, details, supplementary explanations, and the like are related. Further, in the following description, when referring to the number of elements (including the number, numerical value, quantity, range, etc.), unless otherwise specified, or in principle limited to a specific number in principle, It is not limited to the specific number, and may be more or less than the number of characteristics.

Furthermore, in the following description, it is needless to say that its constituent elements (including element steps and the like) are not necessarily essential unless otherwise specified or apparently essential in principle. . Similarly, in the following description, when referring to the shape and positional relationship of components, etc., the shape or the like of the component is substantially changed unless otherwise specified or apparently not in principle. Approximate or similar. The same applies to the above numerical values and ranges.

FIG. 1 is a configuration diagram of an electric vehicle drive system according to the first embodiment.

1, an electric vehicle drive system 100 is connected to a pantograph 1 that takes electric power from a DC overhead line to an electric vehicle and an electric motor 11 that drives the electric vehicle. The electric vehicle drive system 100 includes a

current breaker

2, 3 and 4 (an example of one or more current breakers), a charging resistor 5 (an example of a first resistor), and a current reducing resistor 6 (a second resistor). An example), a power module 7 (a parallel body of a semiconductor switch element and a diode connected in parallel in the direction of flowing regenerative power), an inverter 10, and a pulsation of a voltage generated when the inverter 10 is operated. The filter reactor 8 and the filter capacitor 9 to be suppressed, the semiconductor switch control device (hereinafter referred to as a control device) 12, the first current detector 21 for detecting overcurrent that detects a direct current, and the current flowing through the current reducing resistor 6 And a second current detector 22 for detection. In the current breaker 2, a parallel body of the current reducing resistor 6 and the power module 7 is a semiconductor current reducer 110. The current values detected by the first current detector 21 and the second current detector 22 are respectively input to the control device 12. The control device 12 controls on and off of the semiconductor switch element in the power module 7. In the present embodiment, the control device 12 can also control ON (closed) and OFF (open) of the current breakers 2 to 4.

The

current breakers

2 and 3 are connected in series. By connecting a plurality of circuit breakers in series, the breaking current capacity can be increased as compared with the case where one circuit breaker is used alone.

The series body of the current breaker 4 and the charging resistor 5 is connected in parallel with the current breaker 3. By adopting this configuration, for example, the following two effects can be obtained.

The first effect is that the resistance values of the charging resistor 5 and the current reducing resistor 6 can be selected to optimum values. During the current reducing operation, the current flowing through the power module 7 is commutated to the current reducing resistor 6. Therefore, the product of the magnitude of the commutated current and the resistance value of the current reducing resistor 6 is a voltage applied to both ends of the power module 7. As the value of the current reducing resistor 6 is larger, it is necessary to increase the element withstand voltage of the power module 7, leading to an increase in cost and size of the element. Therefore, it is desirable that the value of the current reducing resistor 6 is small as long as it does not cause a problem in the current reducing operation. On the other hand, the charging resistor 5 that limits the charging current when charging the filter capacitor 9 has a concern that if the resistance value is small, the charging current rises sharply at the start of charging and becomes a noise source that affects signal devices and the like. . This tendency is particularly strong when the capacity of the filter reactor 8 is small. Therefore, it is desirable to set a sufficiently large resistance value so that the value of the charging resistor 5 does not become a noise source. From the above, in one comparative example that does not have the current breaker 4 and the charging resistor 5 and also uses the current reducing resistor as the charging resistor, the optimum resistance values of the current reducing resistor and the charging resistor are different. The value cannot be optimized. In the present embodiment, since the circuit breaker 4 and the charging resistor 5 are provided, a series body of the charging resistor 5 and the current reducing resistor 6 is used as the charging resistor of the filter capacitor 9. Thereby, the resistance value of the current reducing resistor 6 and the resistance value of the charging resistor 5 of the filter capacitor 9 can be determined individually. Therefore, it is possible to achieve both suppression of an increase in element breakdown voltage required for the power module 7 and suppression of noise generation due to a steep current change when the filter capacitor 9 is charged. Note that the semiconductor switch element may be turned on by the control device 12 when the filter capacitor 9 is charged, and the charging current may flow through the charging resistor 5 and not through the current reducing resistor 6.

The second effect is that the safety of the drive system 100 when the filter capacitor 9 is charged can be improved. In the charging sequence of the filter capacitor 9, the breaker 2 and the breaker 4 can be turned on with the breaker 3 turned off. In the charging sequence, the charging current always passes through the charging resistor 5, so even if the power module 7 has a short-circuit mode failure, a large inrush current does not occur. Adverse effects such as occurrence are suppressed.

The positions of the current breaker 4 and the charging resistor 5 may be interchanged. The semiconductor switch element constituting the power module 7 is, for example, an IGBT (Insulated Gate Bipolar Transistor), but may be another power device such as a MOSFET (Metal Oxide Semiconductor Semiconductor Field Field Effect Transistor). When a power device having a body diode such as a MOSFET is used, the diode may be omitted.

The second current detector 22 that detects the value of the current flowing through the current reducing resistor 6 may be present on either of the two paths connecting the current reducing resistor 6 and the power module 7.

A filter circuit composed of a filter reactor 8 and a filter capacitor 9 is connected to the parallel body of the current reducing resistor 6 and the power module 7, and one end of the filter capacitor 9 is connected to the overhead line return path. Usually the overhead line voltage is charged. An inverter 10 and an electric motor 11 are connected to the filter capacitor 9.

The inverter 10 may be a well-known inverter that constitutes a two-level or three-level circuit with semiconductor elements such as IGBT and MOSFET, and converts DC power into a three-phase variable frequency and variable voltage. An electric motor 11 serving as a load of the inverter 10 may also be known. The motor 11 may be a synchronous motor.

The inductance of the filter reactor 8 may be a low inductance, for example, about 1/2 to 1/8 of a general inductance value (8 mH to 12 mH), specifically, 1 mH to 4 mH. Thereby, the filter reactor 8 can be reduced in size. Even if the filter reactor 8 does not have a low inductance (for example, the inductance value is general), the failure detection described later, that is, the semiconductor switch element has failed based on the current value of the current flowing through the current reducing resistor 6. Can be detected.

Next, the operation sequence of the drive system 100 will be described with reference to FIGS. In the following description, “charging” of the filter capacitor 9 is any time from the start of charging to the end of charging (thus, “charging” means “at the start of charging”). May be) Similarly, “in operation” of the inverter 10 is any time from the start of operation to the end of operation (thus, “in operation” may be “at the start of operation”).

In the following, the symbols “H” and “L” in the figure indicate the state of the operation command to the

circuit breakers

2, 3, 4 and the operation command transmitted from the control device 12 to the gate of the semiconductor switch element constituting the power module 7. Indicates. “H” represents on and “L” represents off. In other words, the control device 12 turning on the semiconductor switch element means that the power module 7 of the semiconductor current reducer 110 receives an on-command for the semiconductor switch element. The fact that the control device 12 turns off the semiconductor switch element means that the power module 7 of the semiconductor current reducer 110 receives an off command for the semiconductor switch element. Ecf in the figure represents the voltage of the filter capacitor 9. I ₀ represents the current flowing through the first current detector 21 or its current value. I ₁ represents the current flowing through the second current detector 22 or its current value. T represents time.

First, a control sequence in the system 100 when the power module 7 is in a normal state will be described. After starting the electric car and passing through the initial sequence necessary for starting the inverter 10, a sequence until a ground fault occurs during the operation of the inverter 10 and the fault current is interrupted by the semiconductor current reducer 110, This will be described with reference to FIG.

In starting the inverter 10 of the electric vehicle, it is necessary to charge the filter capacitor 9 first. The control device 12 turns on the circuit breaker 4 after turning on the circuit breaker 2 in the state where the circuit breaker 3 and the power module 7 are off (t ₂₁ ). The filter capacitor 9 is charged from the pantograph 1 through the path of the current breaker 2, current breaker 4, charging resistor 5, current reducing resistor 6, and filter reactor 8 (t ₂₁ to t ₂₂ ). After the charging of the filter capacitor 9 is completed, the control device 12 turns off the circuit breaker 4 (t ₂₂ ), then turns on the circuit breaker 3 and then turns on the power module 7 (t ₂₃ ). Thereby, the direct current path from the pantograph 1 to the inverter 10 becomes conductive. When the inverter 10 operates (t ₂₄ ), the electric motor 11 operates and the electric vehicle travels.

When the controller 12 detects that the value of the current flowing through the first current detector 21 has exceeded the overcurrent detection threshold Th ₀ due to a ground fault (t ₂₅ ) or the like, that is, the overcurrent is detected by the controller 12. When detected (t ₂₆ ), the control device 12 starts a current path blocking operation. Specifically, the control device 12 commutates current to the current reducing resistor 6 by turning off the power module 7. As a result, the current decreases. When the current is reduced to a level that can be interrupted by the series body of the current breaker 2 and the current breaker 3, the control device 12 turns off the current breaker 2 and the current breaker 3 to change the current path (main current). Shut off (t ₂₇ ).

In a general mechanical high-speed circuit breaker, it takes about 10 ms to cut off the fault current, whereas the power module 7 can be turned off in a short time of several μs and can be shifted to a current reducing operation. For this reason, even if the current increase speed at the time of an accident increases by reducing the inductance of the filter reactor 8, the interruption can be completed with a low current value that does not affect the operation of the substation.

In addition, in one comparative example, the failure detection function of the semiconductor switch element in the semiconductor current reducer is not provided, and when the semiconductor switch element breaks down, there is a risk of causing equipment burnout or the like.

On the other hand, in this embodiment, a failure detection function of the semiconductor switch element is provided. Specifically, a second current detector 22 for detecting a current flowing through the current reducing resistor 6 is provided, and the control device 12 causes the semiconductor switch element to fail based on the current value of the current flowing through the current reducing resistor 6. Is detected, and at least the circuit breaker 2 (an example of a circuit breaker that cuts off the main current) of the circuit breakers 2 to 4 is turned off.

Next, a protection sequence when the power module 7 constituting the semiconductor current reducer 110 fails will be described. The case where the power module 7 has a short-circuit mode failure and an open-mode failure under the respective conditions of charging the filter capacitor 9 and operating the inverter 10 will be described.

First, the case where the power module 7 has a short-circuit mode failure when the filter capacitor 9 is charged will be described with reference to FIG. A short circuit failure of the power module 7 can be detected before the inverter 10 operates. _{Incidentally, t 31} is the start of charging of the filter capacitor _{9, t 32} is the time of shut-off completion.

It can be detected by at least one of the following two methods that the power module 7 is in the short-circuit mode failure when the filter capacitor 9 is charged. When the short circuit mode failure of the power module 7 is detected, the control device 12 cuts off the current by turning off the

current breakers

2 and 4.

The first method uses the first current detector 21 and the second current detector 22. When the power of the filter capacitor 9 is normal, when the power module 7 is normal, no current flows through the power module 7, so that the current passing through the first current detector 21 and the second current detector 22 (mainly The first current value I ₀ , which is the current value of the current, and the second current value I _1, which is the current value of the current flowing through the current reducing resistor 6, are equal. On the other hand, when the power module 7 has failed in the short-circuit mode, the current passing through the power module 7 is the current difference (I ₀ −I ₁₎ between the first current detector 21 and the second current detector 22. ) Is detected. A threshold value of I ₀ -I ₁ (hereinafter referred to as a first threshold value Th ₁ ) is provided. During charging of the filter capacitor 9 (for example, at the start of charging), the control device 12 detects that I ₀ -I ₁ has exceeded Th ₁ as a short-circuit mode failure of the power module 7.

The second method is a method using the second current detector 22 and not using the first current detector 21 (method using I ₁ and not using I ₀ ). When the power module 7 is in short mode failure, even if the charging start the filter capacitor 9, the rise of I ₁ is not detected by the second current detector 22, and, I ₁ is trolley voltage Es and filter capacitor 9 At least one of the current values lower than the normal charging current value _IE estimated from the difference from the voltage Ecf. Therefore, the control device 12 is configured to charge I ₁ less than the second threshold Th ₂ and I _E −I ₁ greater than the third threshold Th ₃ while the filter capacitor 9 is being charged (for example, at the start of charging). It is detected as a short-circuit mode failure of the power module 7 to correspond to at least one of the above.

Next, a case where the power module 7 has an open mode failure while the filter capacitor 9 is being charged will be described with reference to FIG.

At the start of charging the filter capacitor 9 (t ₄₁ ), the power module 7 is in an off state even when it is normal. For this reason, even when the power module 7 is in the open mode failure state, the path of the charging current does not change, and therefore, the open mode failure cannot be detected. However, there is no danger because the charging current flows through the same path as normal, and there is no problem that the open mode failure of the power module 7 cannot be detected at this time.

The open mode failure of the power module 7 can be detected during the operation of the inverter 10 (for example, at the start of the operation), which is the next sequence of charging the filter capacitor 9 (t ₄₁ to t ₄₂ ). If the power module 7 is normal, the power module 7 is turned on by the control device 12 before starting the operation of the inverter 10 (t ₄₃ ), and the drive power of the inverter 10 passes through the power module 7. When the power module 7 has an open mode failure, current flows through the current reducing resistor 6. When the power module 7 is normal, no current flows through the current reducing resistor 6. Therefore, a threshold value (hereinafter referred to as a fourth threshold value Th ₄ ) is provided for I ₁ detected by the second current detector 22 at the start of the operation of the inverter 10. The control device 12 detects that I ₁ exceeds Th ₄ during the operation of the inverter 10 (for example, at the start of operation) (t ₄₄ ), and detects that the power module 7 is in the open mode failure. When the open mode failure of the power module 7 is detected, the control device 12 turns off the power module 7 after stopping the operation of the inverter 10 and turns off the

current breakers

2 and 3 to cut off the current (t ₄₅ ).

For example, the failure detection of the power module 7 during the operation of the inverter 10 is as follows.

When the power module 7 has failed in the short circuit mode during power running of the electric vehicle, the following sequence is performed for each resistance value between both ends of the power module 7 after the short circuit mode failure.

FIG. 5 shows a sequence when the resistance value between both ends of the power module 7 after the failure is sufficiently low and the current flowing through the current reducing resistor 6 does not increase greatly. In this _case, to stop the operation of the inverter 10 starts operation on _{_t 51 _(t} _52), turns off the

line breaker

2 and 3 and the power module 7 _{(t 53),} the charging of the filter capacitor 9 rows again Until it is (t ₅₄ ), the controller 12 cannot detect a short-circuit mode failure. However, in the above situation, there is no problem because the path through which the direct current flows does not change before and after the occurrence of the short-circuit mode failure and there is no danger.

The short-circuit mode failure is caused by detecting at least one of I ₀ -I ₁ > Th ₁ , I ₁ <Th ₂ , and I _E -I ₁ > Th ₃ when charging the filter capacitor 9 again. Detected. When this short circuit mode failure is detected, the controller 12 cuts off the current by turning off the circuit breakers 2 and 4 (t ₅₅ ).

On the other hand, the resistance value after the failure between both ends of the power module 7 is high, and the current flowing through the current reducing resistor 6 out of the current supplied to the inverter 10 is a value obtained by dividing the ON voltage of the power module 7 by the current reducing resistor 6. If the power module 7 is sufficiently large, a current flowing through the current reducing resistor 6 is generated. Therefore, it can be detected by the same method as described below when the power module 7 fails in the open mode during power running. When this short circuit mode failure is detected, the control device 12 turns off the power module 7 and turns off the

current breakers

2 and 3 to cut off the current.

The

circuit breakers

2 and 4 are connected in series to the charging resistor 5, and the charging current of the filter capacitor 9 always passes through the charging resistor 5. Thereby, even if the power module 7 (semiconductor switch element) has a short-circuit mode failure, a large current surge at the start of charging of the filter capacitor 9 can be suppressed.

Also, the operation of the inverter 10 is stopped, for example, at the end of business travel. When a charging sequence occurs after the operation of the inverter 10 stops and there is a short circuit mode failure, the short circuit mode failure can be detected during the charging sequence. For this reason, it can be expected to detect a failure of the semiconductor current reducer 110 before starting business travel.

The sequence when the power module 7 fails in the open mode during power running will be described with reference to FIG.

When the power module 7 breaks down in the open mode during the operation of the inverter 10 started at t ₆₁ (t ₆₂ ), a current much larger than the value obtained by dividing the ON voltage of the power module 7 by the current reducing resistor 6 is Two current detectors 22 detect the current. I ₁ detected by the second current detector 22 exceeds the _fourth threshold Th ₄ . When the power module 7 is in the ON state and I ₁ > Th ₄ is detected during the operation of the inverter 10, the control device 12 detects that the power module 7 is in the open mode failure. If the open mode failure of the power module 7 is detected, the control device 12 turns off the power module 7 and turns off the

circuit breakers

2 and 3 to cut off the current (t ₆₃ ).

Example 2 will be described. At that time, differences from the first embodiment will be mainly described, and description of common points with the first embodiment will be omitted or simplified.

FIG. 7 is a configuration diagram of an electric vehicle drive system according to the second embodiment.

In the electric vehicle drive system 700 according to the second embodiment, the difference from the first embodiment is the position of the second current detector 22.

That is, in the first embodiment, the second current detector 22 is connected to the emitter side of the semiconductor switch element (see FIG. 1), but in the second embodiment, the second current detector 22 is a semiconductor switch. It is connected to the collector side of the element (installed on the side close to the overhead line of the current reducing resistor 6). Since the current to be detected is the same between the first and second embodiments, the control sequence does not change.

According to the first and second embodiments, the second current detector 22 can be arranged in consideration of the insulating space or other environmental factors.

Example 3 will be described. At that time, differences from the second embodiment will be mainly described, and description of common points with the second embodiment will be omitted or simplified.

FIG. 8 is a configuration diagram of an electric vehicle drive system according to the third embodiment.

In the electric vehicle drive system 800 according to the third embodiment, the difference from the second embodiment is that a parallel body (a parallel body composed of a series body of the current breaker 4 and the charging resistor 5 and the current breaker 3). The position of the semiconductor current reducer 110 (parallel body composed of the current reducing resistor 6 and the power module 7) is switched. By adopting this configuration, the semiconductor current reducer 110 is located closer to the overhead wire side, so that the protection range by the semiconductor current reducer 110 can be expanded compared to the second embodiment (and the first embodiment).

Example 4 will be described. At that time, differences from the first to third embodiments will be mainly described, and description of common points with the first to third embodiments will be omitted or simplified.

FIG. 9 is a diagram illustrating an arrangement example of the second current detector 22 in the electric vehicle drive system according to the fourth embodiment.

The semiconductor current reducer 110 includes a current reducing resistor 6 provided in the first branch path in the parallel circuit, and a power module 7 provided in the second branch path in the parallel circuit. When the power module 7 is on, the current I ₀ entering the parallel circuit constituting the semiconductor current reducer 110 is divided into a current I ₁ flowing through the _first branch path and a current I ₂ flowing through the second branch path. (That is, I ₀ = I ₁ + I ₂ ). According to Examples 1 to 3, I ₀ is the first current value, and I ₁ is the second current value. The second current detector 22 is provided in the first branch path. That is, the second current detector 22 detects the _{I 1.} The second current detector 22 may be disposed at either the emitter-side position 90D of the semiconductor switch element or the collector-side position 90C of the semiconductor switch element. The short circuit mode failure and the open mode failure of the semiconductor switch element are as follows. The semiconductor switch element is turned off to charge the filter capacitor 9 and the semiconductor switch element is turned on to start the operation of the inverter 10. In the fourth embodiment, both the short-circuit mode failure and the open-mode failure are the same as those in the first to third embodiments.

In the fourth embodiment, the second current detector 22 is provided in the first branch path instead of the second branch path. That is, the second current detector 22 detects the _{I 2.} The controller 12, in addition to the _{I 2,} since _{I 0} to the first current detector 21 detects are inputted, the control unit 12 can calculate the _{I 1} by subtracting the _{I 2} from _{I 0} . The controller 12 can detect both the short-circuit mode failure and the open-mode failure based on the calculated I ₁ .

Example 5 will be described. At that time, differences from the first to fourth embodiments will be mainly described, and description of common points with the first to fourth embodiments will be omitted or simplified.

FIG. 10 is a diagram illustrating a configuration of a semiconductor current reducer and an arrangement example of a second current detector in the electric vehicle drive system according to the fifth embodiment.

In the first to fourth embodiments, in the semiconductor current reducer 110, the resistor provided in the first branch path is the current reducing resistor 6. In the semiconductor current reducer 1010 according to the fifth embodiment, the resistor is In addition to the current reducing resistor 6, it has a charging resistor 5 connected in parallel to the current reducing resistor 6 (therefore, the charging resistor 5 may not be provided outside the semiconductor current reducer 1010). Specifically, the resistance unit corresponds to a parallel circuit including a first sub branch path and a second sub branch path. A current reducing resistor 6 is provided in the first sub-branch, and a charging resistor 5 is provided in the second sub-branch. In addition, the resistance unit includes a switch that switches connection and disconnection of the current reducing resistor 6. An example of the switch is a current breaker 107 (connected in series with the current reducing resistor 6) provided in the first sub-branch. The current breaker 107 is turned on by the control device 12 when the charging of the filter capacitor 9 is completed, for example, and as a result, the current reducing resistor 6 is connected. The current breaker 107 is turned off by the control device 12 when the filter capacitor 9 is charged. As a result, the current reducing resistor 6 is disconnected.

In such a semiconductor current reducer 1010, I ₀ is divided into I ₁ and I ₂ , I ₁ is the current I ₃ flowing through the first sub-branch when the current breaker 107 is on, and the second And the current I ₄ flowing through the sub-branch. The second current detector 22 replaces any of the above-described positions 90A to 90D with the position 90E (the semiconductor switch element of the semiconductor switch element) in the second sub-branch without disconnection among the first and second sub-branches. (Position on the collector side) or position 90F (position on the emitter side of the semiconductor switch element).

For each of positions 90A-90E, I ₁ is as follows:

That is, when the second current detector 22 is disposed at a

position

90C or 90D, the controller 12, I ₁ is the current value detected by the second current detector 22.

When the second current detector 22 is arranged at the

position

90A or 90B, I ₀ −I ₂ (current value detected by the second current detector 22) = I ₁ .

If the second current detector 22 is disposed in a

position

90E or 90F, depending on whether breaker 107 is on or off, since the flow ratio is different, the definition of I ₁ is different. When the current breaker 107 is off, I ₄ (current value detected by the second current detector 22) = I ₁ . When the current breaker 107 is on, I ₄ × {(current reducing resistance 6 + charging resistance 5) / current reducing resistance 6} = I ₁ .

Example 6 will be described. At that time, the differences from the first to fifth embodiments will be mainly described, and the description of the common points with the first to fifth embodiments will be omitted or simplified.

FIG. 11 is a diagram illustrating a configuration of a semiconductor current reducer and an arrangement example of a second current detector in the electric vehicle drive system according to the sixth embodiment.

In the semiconductor current reducer 1110 according to the sixth embodiment, the power module 7 in the first branch path is a power module for current reduction and is in the second branch path (connected in parallel to the power module 7). The resistor includes a current reducing resistor 6 and a parallel body connected in series to the current reducing resistor 6. The parallel body includes a charging resistor 5 and a charging power module 117 connected to the charging resistor 5 in parallel. When an overcurrent is detected, the power module 117 is turned on and the power module 7 is turned off by the control device 12. As a result, the commutated current flows through the current reducing resistor 6. When the filter capacitor 9 is charged, the power module 7 and the power module 117 are turned off by the control device 12, and the charging current passes through the current reducing resistor 6 and the charging resistor 5.

In such a semiconductor down stream 1110 may be based on the value of the current I ₁ flowing through the second branch passage, for detecting a failure of the power module 7.

As described above, in the first to sixth embodiments, the semiconductor current reducer including the parallel body of the resistor (one or more resistors including the current reducing resistor 6) and the power module 7 is more pantograph 1 than the filter reactor 8. It is arranged on the side (the overhead line side). By disposing the semiconductor current reducer at a position close to the pantograph 1, it is possible to widen the possible range of interruption of an accident current due to a ground fault or the like. In other words, according to the first to sixth embodiments, it is possible to cut off an accident current generated on the side of the electric motor 11 with respect to the filter reactor 8, so that the drive system can be highly reliable.

In the first to sixth embodiments, it is desirable that the first current detector 21 for detecting an accident current (overcurrent) is disposed on the pantograph 1 side with respect to the semiconductor current reducer. Since the semiconductor current reducer is disposed on the overhead line side of the filter reactor 8 and the first current detector 21 is disposed on the overhead line side of the semiconductor current reducer, the fault current generation point is higher than that of the semiconductor current reducer. If this occurs on the inverter 10 side, the fault current can be detected. Moreover, since the high speed interruption | blocking by a semiconductor current reducer is possible, an accident electric current can be interrupted at high speed.

As described above, in the drive systems according to the first to sixth embodiments, the reduction in size and weight of the filter reactor 8 and the suppression of the short-circuit current are compatible, and the failure of the semiconductor switch element in the semiconductor current reducer occurs. Can be realized. Therefore, the weight of the vehicle per train can be reduced, contributing to stable energy saving operation of the electric vehicle, and contributing to the reliability and safety of the semiconductor current reducer as a current breaker.

As described above, according to the first to sixth embodiments, the loss of the semiconductor current reducer can be reduced. That is, in the electric vehicle having the filter reactor 8 having a low inductance, it is possible to effectively cut off the short-circuit current that increases when a ground fault occurs, and the influence on the substation can be suppressed with a small additional cost.

As mentioned above, although several examples were described, it cannot be overemphasized that this invention is not limited to these Examples, and can be variously changed in the range which does not deviate from the summary. The above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and the present invention is not necessarily limited to those having all the configurations described. Moreover, it is possible to add at least one of addition, deletion, and replacement of another configuration for a part of the configuration of the embodiment. For example, the present invention can be expected to be applied to all systems (for example, power control systems) including at least one of a reactor (for example, the above-described filter reactor), a capacitor, and a power converter (for example, an inverter). Further, the control device 12 may be included in the semiconductor current reducer of any embodiment.

2, 3, 4 ... Circuit breaker, 5, 6 ... Resistor, 7 ... Power module, 8 ... Filter reactor, 9 ... Filter capacitor, 10 ... Inverter, 12 ... Semiconductor switch controller, 21, 22 ... Current detector , 110, 1010, 1110 ... Semiconductor current reducer

Claims

A circuit breaker that cuts off DC power from the overhead line, an inverter that converts DC power to AC power, and a voltage pulsation that is generated when the inverter is operated between the circuit breaker and the inverter. In an electric vehicle drive system having a filter reactor and a filter capacitor to be suppressed, and a first current detector that is a current detector for detecting overcurrent and detects a first current value,
A semiconductor current reducer having a semiconductor switch element connected in series to the current breaker and the inverter; and a resistance part connected in parallel to the semiconductor switch element and including one or more resistors;
A second current detector for detecting a current flowing through any of the semiconductor switch element and the resistance unit;
When the overcurrent is detected, the semiconductor switch element is turned off to commutate the overcurrent to at least one resistor in the resistance unit, and the current commutated and reduced by the at least one resistor is The current value obtained based on at least the second current detector of the first current detector and the second current detector is cut off by turning off the current breaker. And a control device that detects that the semiconductor switch element has failed if a predetermined condition provided for a second current value that is a current value of the current flowing through the resistance portion is satisfied. An electric vehicle drive system.
2. The electric vehicle drive system according to claim 1, wherein when the control device detects that the semiconductor switch element has failed, the control device turns off a circuit breaker that cuts off the main current. 3.
The control device turns off the semiconductor switch element during charging of the filter capacitor,
2. The predetermined condition is that the difference between the first current value and the second current value exceeds a first threshold during charging of the filter capacitor. The drive system for electric vehicles as described.
The control device turns off the semiconductor switch element during charging of the filter capacitor,
The predetermined condition is:
During the charging of the filter capacitor, the second current value is lower than a second threshold;
During the charging of the filter capacitor, the difference between the normal charging current value assumed from the difference between the overhead line voltage and the voltage of the filter capacitor and the second current value is greater than a third threshold value. The drive system for an electric vehicle according to claim 1, wherein the drive system is at least one of them.
The control device turns on the semiconductor switch element during the operation of the inverter,
2. The electric vehicle drive system according to claim 1, wherein the predetermined condition is that the second current value is higher than a fourth threshold value during operation of the inverter.
The electric vehicle drive system according to claim 1, wherein the semiconductor current reducer is provided closer to the overhead wire than the filter reactor.
A first resistor provided in a path through which a charging current to the filter capacitor flows;
The resistor in the semiconductor current reducer is
The first resistor;
The electric vehicle drive system according to claim 1, further comprising: a second resistor provided in a path through which the commutated current flows and connected in parallel to the first resistor.
A first resistor provided in a path through which a charging current to the filter capacitor flows, inside or outside the resistor unit;
The said resistance part in the said semiconductor current reducer has the 2nd resistance provided in the path | route through which the said commutated electric current flows, and was connected in series with the said 1st resistance. Electric vehicle drive system.
The control device obtains the current value of the current flowing through the resistance unit including one or more resistors connected in parallel to the semiconductor switch element connected in series with the circuit breaker and the inverter,
The control device detects that the semiconductor switch element is faulty if the acquired current value satisfies a predetermined condition with respect to a current value flowing through the resistance unit. A fault detection method for semiconductor current reducers.
10. The semiconductor current reducer failure detection method according to claim 9, wherein when a failure of the semiconductor switch element is detected, the main current is cut off.
The predetermined condition is that a difference between a current value detected by a current detector for overcurrent detection and a current value flowing through the resistor section during a capacitor charging in which the semiconductor switch element is in an off state is a first threshold value. The fault detection method for a semiconductor current reducer according to claim 9, wherein the fault is exceeded.
The predetermined condition is:
A value of a current flowing through the resistor is lower than a second threshold value during capacitor charging when the semiconductor switch element is in an off state;
During the capacitor charging, at least one of a difference between an assumed normal charging current value and a current value flowing through the resistance unit is greater than a third threshold value. The fault detection method of the semiconductor current reducer according to claim 9.
The predetermined condition is that a value of a current flowing through the resistance unit is higher than a fourth threshold value during operation of a power converter in which the semiconductor switch element is in an on state. Fault detection method for semiconductor current reducer.
In a semiconductor current reducer having a semiconductor switch element connected in series between a current breaker and an inverter, and a resistance part connected in parallel to the semiconductor switch element and including one or more resistors,
A current value of a current flowing through one of the semiconductor switch element and the resistance portion is detected, and the semiconductor switch element is satisfied if a predetermined condition regarding the current value of the current flowing through the resistance portion is satisfied A semiconductor current reducer comprising a current detector capable of outputting the detected current value in a control device that detects that a fault has occurred.
During capacitor charging, the power module receives an off command of the semiconductor switch element,
The predetermined condition is that, during charging of the capacitor, a difference between a current value detected by another current detector that detects an overcurrent and a current value flowing through the resistance unit exceeds a first threshold value. The semiconductor current reducer according to claim 14, wherein the semiconductor current reducer is present.
During capacitor charging, the power module receives an off command of the semiconductor switch element,
The predetermined condition is:
A value of a current flowing through the resistance unit during charging of the capacitor is lower than a second threshold;
The difference between an assumed normal charging current value and a current value flowing through the resistor during charging of the capacitor is at least one of being greater than a third threshold value. Item 15. A semiconductor current reducer according to Item 14.
During operation of the power converter, the power module receives an on command of the semiconductor switch element,
15. The semiconductor current reducer according to claim 14, wherein the predetermined condition is that a value of a current flowing through the resistance unit is higher than a fourth threshold value during the operation of the power converter.