CN106469980B - DC-DC converter - Google Patents
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- CN106469980B CN106469980B CN201610538671.2A CN201610538671A CN106469980B CN 106469980 B CN106469980 B CN 106469980B CN 201610538671 A CN201610538671 A CN 201610538671A CN 106469980 B CN106469980 B CN 106469980B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
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Abstract
The invention provides a DC-DC conversion device, which can restrain the continuous rise of the capacitor voltage when the short-circuit fault occurs in the switching element, and can safely use the switching element or the capacitor with low voltage resistance. The method comprises the following steps: a series circuit of switching elements (5, 6); a series circuit of capacitors (8, 10); diodes (7, 9) connected between respective ends of the two series circuits; a series circuit composed of a DC power supply (1), a circuit breaker (2) and reactors (3, 4); and a control circuit (20) that boosts the voltage of the DC power supply (1) by a chopping operation and outputs the boosted voltage from both ends of the capacitor series circuit, wherein the control circuit (20) turns on the switching element (5) before the circuit breaker (2) is turned off when it is estimated that the switching element (6) has a short-circuit fault, and turns on the switching element (6) before the circuit breaker (2) is turned off when it is estimated that the switching element (5) has a short-circuit fault, thereby suppressing an overvoltage due to the short-circuit fault.
Description
Technical Field
The present invention relates to a dc-dc converter having a boost chopper circuit, and more particularly, to a dc-dc converter having a protection function when a short-circuit fault occurs in a semiconductor switching element.
Background
Fig. 17 shows a boost chopper circuit described in patent document 1.
IN fig. 17, IN1 and IN2 are positive and negative input terminals to which a dc power supply (not shown) is connected, OUT1 and OUT2 are positive and negative output terminals, L1 is a reactor, Q1 and Q2 are transistors, D1 and D2 are diodes, and C1 and C2 are capacitors. IN addition to the reactor L1, another reactor may be inserted between the negative-side input terminal IN2 and the emitter of the transistor Q2.
Next, an outline of the operation of the conventional technique will be described.
When both the transistors Q1 and Q2 are turned on, a current flows from the dc power supply along a path of the input terminal IN1 → the reactor L1 → the transistors Q1 and Q2 → the input terminal IN2, and energy is stored IN the reactor L1. Next, by turning off the transistor Q2 IN a state where the transistor Q1 is turned on, the dc power supply and the stored energy of the reactor L1 are supplied along a path of the transistor Q1 → the capacitor C2 → the diode D2 → the input terminal IN2, and the capacitor C2 is charged.
Next, when the transistor Q1 is turned off and the transistor Q2 is turned on, a current flows along a path of the input terminal IN1 → the reactor L1 → the diode D1 → the capacitor C1 → the transistor Q2 → the input terminal IN2, and the capacitor C1 is charged. When the transistor Q2 is turned off in this state, the dc power supply and the stored energy of the reactor L1 are supplied along the path of the diode D1 → the capacitor C1 → the capacitor C2 → the diode D2, and the capacitors C1 and C2 are charged.
By repeating the above operations, the voltage between the output terminals OUT1 and OUT2 is boosted to a voltage higher than the dc power supply voltage. The output voltage of the boost chopper circuit can obtain three levels, which are the sum of the voltage of the capacitor C1, the voltage of the capacitor C2, and the voltages of the capacitors C1 and C2, and is therefore also referred to as a three-level boost chopper circuit.
When the dc-dc converter is configured using this boost chopper circuit, although not shown in the drawing, a circuit breaker for disconnecting the dc power supply when a circuit failure occurs, a control circuit for controlling the transistors Q1 and Q2 and the circuit breaker, and the like are usually separately provided.
Documents of the prior art
Patent document
Patent document 1: japanese patent laid-open publication Nos. 2013-38921 (paragraphs [0021] to [0028], FIGS. 1 and 3, etc.)
Disclosure of Invention
Technical problem to be solved
In the three-level boost chopper circuit shown in fig. 17, when a short-circuit failure occurs in one of the transistors Q1 and Q2, the circuit configuration in which the capacitors C1 and C2 should be alternately boosted originally has a circuit configuration in which only one capacitor is boosted. Therefore, a capacitor may be boosted excessively, and its voltage may exceed a rated value.
In a power conversion device such as a dc-dc converter, when the occurrence of an abnormal voltage is detected, all semiconductor switching elements (hereinafter, also simply referred to as switching elements) are turned off to stop a power conversion operation. Meanwhile, the input power is generally separated from the device for protection using a circuit breaker.
However, in the failure mode in which one of the transistors Q1 and Q2 is short-circuited in fig. 17, even if one transistor is turned off, the other transistor is in a short-circuited state. Therefore, a path for charging any one of the capacitors with the energy stored in the reactor L1 remains during the period until the device is actually disconnected from the dc power supply by the breaker. Thus, the capacitor voltage further rises.
In the three-level boost chopper circuit, the output voltage is shared by the 2 capacitors C1 and C2 connected in series, and only about half the output voltage is applied to one capacitor. Therefore, low-voltage devices are generally used as switching devices such as the transistors Q1 and Q2. In addition, the capacitors C1 and C2 are generally low-withstand-voltage products.
However, when the short-circuit failure mode described above occurs, the rise in the capacitor voltage may cause the switching element of low withstand voltage or the capacitor of low withstand voltage to be damaged.
Therefore, an object of the present invention is to provide a dc-dc power conversion device that can suppress an increase in capacitor voltage when a short-circuit failure occurs in a switching element, and can safely use a low-withstand-voltage switching element or a low-withstand-voltage capacitor.
Technical solution for solving technical problem
In order to solve the above problem, the invention according to claim 1 includes: a switching element series circuit in which a first switching element and a second switching element are connected in series and connected to both ends of a direct current power supply; a reactor connected between the dc power supply and the switching element series circuit; a capacitor series circuit in which first and second capacitors are connected in series; first and second diodes connected between both ends of the switching element series circuit and both ends of the capacitor series circuit, respectively; and
a control circuit for controlling on/off of the first and second switching elements,
the connection point of the first and second switching elements is connected to the connection point of the first and second capacitors,
a step-up circuit for stepping up a voltage of the DC power supply and outputting the voltage from both ends of the capacitor series circuit by performing an on/off chopping operation of the first and second switching elements,
the control circuit issues a conduction command to the other switching element or both switching elements when it is inferred that at least one of the first and second switching elements has a short-circuit fault.
The invention according to claim 2 is a dc-dc conversion apparatus according to claim 1, wherein,
a circuit breaker is further included between the direct-current power supply and the switching element series circuit,
the control circuit sends a conduction instruction to the switch element and sends a brake-off instruction to the circuit breaker, and the circuit breaker is switched off after the switch element is conducted.
The invention according to claim 3 is a direct current-direct current conversion apparatus according to claim 1, wherein,
includes first and second voltage detectors for detecting voltages of the first and second capacitors, respectively,
the control circuit infers that a short-circuit fault has occurred in the second switching element when it is determined that an overvoltage is applied to the first capacitor, and infers that a short-circuit fault has occurred in the first switching element when it is determined that an overvoltage is applied to the second capacitor.
The invention according to claim 4 is the dc-dc conversion apparatus according to claim 1, wherein,
includes first and second voltage detectors for detecting voltages of the first and second capacitors, respectively,
the control circuit estimates that a short-circuit failure has occurred in the second switching element when it is determined that the voltage of the first capacitor is higher than the voltage of the second capacitor and that a deviation between the voltage values of the two capacitors is equal to or greater than a predetermined value, and estimates that a short-circuit failure has occurred in the first switching element when it is determined that the voltage of the second capacitor is higher than the voltage of the first capacitor and that a deviation between the voltage values of the two capacitors is equal to or greater than a predetermined value.
The invention according to claim 5 is the dc-dc conversion apparatus according to claim 1, wherein,
includes first and second current detectors for detecting currents of the first and second switching elements, respectively,
the control circuit estimates that a short-circuit fault has occurred in the first switching element when it is determined that an overcurrent flows in the first switching element, and estimates that a short-circuit fault has occurred in the second switching element when it is determined that an overcurrent flows in the second switching element.
The invention according to claim 6 is a dc-dc conversion apparatus according to claim 1, wherein,
includes first and second voltage detectors for detecting voltages of the first and second switching elements, respectively,
the control circuit estimates that a short-circuit failure has occurred in the first switching element when it is determined that a voltage across the first switching element is equal to or higher than a predetermined value or equal to or lower than a predetermined value during a period in which an on command is issued to the first switching element, and estimates that a short-circuit failure has occurred in the second switching element when it is determined that a voltage across the second switching element is equal to or higher than a predetermined value or equal to or lower than a predetermined value during a period in which an on command is issued to the second switching element.
The invention according to claim 7 is a dc-dc conversion apparatus according to claim 1, wherein,
includes first and second voltage detectors for detecting voltages of the first and second switching elements, respectively,
the control circuit estimates that a short-circuit failure has occurred in the first switching element when it is determined that a voltage across the first switching element is equal to or lower than a predetermined value during a period in which an off command is issued to the first switching element, and estimates that a short-circuit failure has occurred in the second switching element when it is determined that a voltage across the second switching element is equal to or lower than a predetermined value during a period in which an off command is issued to the second switching element.
The invention according to claim 8 is a dc-dc conversion apparatus according to claim 1, wherein,
comprises a first current detector and a second current detector, which respectively detect the current of the first diode and the second diode,
the control circuit estimates that a short-circuit fault has occurred in the second switching element when it is determined that an overcurrent flows in the first diode, and estimates that a short-circuit fault has occurred in the first switching element when it is determined that an overcurrent flows in the second diode.
The invention according to claim 9 is a dc-dc conversion apparatus according to claim 1, wherein,
comprises a first and a second voltage detector for detecting the voltage of the first and the second diodes respectively,
the control circuit estimates that a short-circuit failure has occurred in the second switching element when the voltage across the first diode is determined to be equal to or greater than a predetermined value during a period in which an off command is issued to the first switching element, and estimates that a short-circuit failure has occurred in the first switching element when the voltage across the second diode is determined to be equal to or greater than a predetermined value during a period in which an off command is issued to the second switching element.
The invention according to claim 10 is a dc-dc conversion apparatus according to claim 1, wherein,
includes a current detector that detects a current of the reactor,
the control circuit infers that at least one of the first and second switching elements has a short-circuit fault when it is determined that an overcurrent flows through the reactor.
The invention according to claim 11 is a dc-dc conversion apparatus according to claim 1, wherein,
includes a voltage detector that detects a voltage of the reactor,
the control circuit estimates that at least one of the first and second switching elements has a short-circuit fault when it is determined that the voltage across the reactor is equal to or higher than a predetermined value.
The invention according to claim 12 is a dc-dc conversion apparatus according to claim 1, wherein,
a current detector for detecting a current of a wiring connecting a connection point between the first and second switching elements and a connection point between the first and second capacitors,
the control circuit infers that at least one of the first and second switching elements has a short-circuit failure when it is determined that an overcurrent flows through the wiring.
The invention according to claim 13 is a dc-dc conversion apparatus according to claim 1, wherein,
the control circuit estimates that a short-circuit failure has occurred in the first switching element when it is determined that the control electrode of the first switching element is always short-circuited or the potential of the control electrode is always high, and estimates that a short-circuit failure has occurred in the second switching element when it is determined that the control electrode of the second switching element is always short-circuited or the potential of the control electrode is always high.
The invention according to claim 14 is a dc-dc conversion apparatus according to claim 1, wherein,
the control circuit estimates that a short-circuit failure has occurred in the first switching element when it is determined that the current flowing through the control electrode of the first switching element is an overcurrent or always flows, and estimates that a short-circuit failure has occurred in the second switching element when it is determined that the current flowing through the control electrode of the second switching element is an overcurrent or always flows.
The invention according to claim 15 is a dc-dc conversion apparatus according to claim 1, wherein,
comprises a first current detector and a second current detector, which respectively detect the current of the first capacitor and the second capacitor,
the control circuit estimates that a short-circuit fault has occurred in the second switching element when it is determined that an overcurrent flows in the first capacitor, and estimates that a short-circuit fault has occurred in the first switching element when it is determined that an overcurrent flows in the second capacitor.
The invention according to claim 16 is a dc-dc conversion apparatus according to claim 1, wherein,
the control circuit generates an alarm when it is inferred that the first or second switching element has a short-circuit fault.
Effects of the invention
In the invention, when one switching element has a short-circuit fault, the other switching element can be fixed in a conducting state before the breaker is opened, and a current path flowing in the capacitor is eliminated. Thus, the continuous rise of the capacitor voltage can be suppressed, and even when a low-withstand-voltage switching element or a low-withstand-voltage capacitor is used, the breakdown of the switching element or the capacitor can be prevented.
Drawings
Fig. 1 is a diagram illustrating a first embodiment of the present invention.
Fig. 2 is an explanatory diagram of the operation in the first mode of the first embodiment of the present invention.
Fig. 3 is an explanatory diagram of an operation in a second mode of the first embodiment of the present invention.
Fig. 4 is an explanatory diagram of an operation in a third mode of the first embodiment of the present invention.
Fig. 5 is an explanatory diagram of the operation in the fourth mode of the first embodiment of the present invention.
Fig. 6 is an explanatory diagram of an operation when a short-circuit fault occurs according to the first embodiment of the present invention.
Fig. 7 is a diagram illustrating a second embodiment of the present invention.
Fig. 8 is a diagram illustrating a third embodiment of the present invention.
Fig. 9 is a diagram illustrating a fourth embodiment of the present invention.
Fig. 10 is a diagram illustrating a fifth embodiment of the present invention.
Fig. 11 is a diagram illustrating a sixth embodiment of the present invention.
Fig. 12 is a diagram illustrating a seventh embodiment of the present invention.
Fig. 13 is a diagram illustrating an eighth embodiment of the present invention.
Fig. 14 is a diagram illustrating a ninth embodiment of the present invention.
Fig. 15 is a diagram illustrating a tenth embodiment of the present invention.
Fig. 16 is a diagram illustrating an eleventh embodiment of the present invention.
Fig. 17 is a circuit diagram of the conventional technique described in patent document 1.
Detailed Description
The first embodiment of the present invention will be explained below with reference to the drawings.
Fig. 1 is a structural diagram of a dc-dc converter according to a first embodiment, and corresponds to claims 1 to 4. IN fig. 1, the positive electrode of the dc power supply 1 is connected to one end of the breaker 2 via an input terminal IN1, and the other end of the breaker 2 is connected to one end of the reactor 3. The other end of the reactor 3 is connected to a connection point of the switching element 5 and the diode 7.
On the other hand, the negative electrode of the dc power supply 1 is connected to one end of the reactor 4 through the input terminal IN2, and the other end of the reactor 4 is connected to a connection point between the switching element 6 and the diode 9.
The switching elements 5 and 6 are connected in series, a capacitor 8 is connected between the series connection point and the cathode of the diode 7, and a capacitor 10 is connected between the series connection point and the anode of the diode 9. That is, the capacitors 8 and 10 are also connected in series, and both ends of the capacitor series circuit are connected to the positive and negative output terminals OUT1 and OUT2, respectively.
Further, voltage detectors 11 and 12 are connected to both ends of the capacitors 8 and 10, respectively, and output signals (voltage detection values) thereof are input to the control circuit 20. The control circuit 20 has the following structure: on/off signals to the switching elements 5, 6 are generated based on the voltage detection values of the capacitors 8, 10, and opening/closing commands (opening (closing) commands/closing commands) to the circuit breaker 2 are generated.
In the above configuration, the switching elements 5 and 6 correspond to the first and second switching elements of the claims, the diodes 7 and 9 correspond to the first and second diodes, the capacitors 8 and 10 correspond to the first and second capacitors, and the voltage detectors 11 and 12 correspond to the first and second voltage detectors, respectively.
In fig. 1, IGBTs are used as the switching elements 5 and 6, but power transistors or FETs may be used as well. In particular, elements using a wide bandgap semiconductor such as SiC (silicon carbide) and GaN (gallium nitride) can be used, and it is expected that a small three-level boost chopper circuit can be configured with higher efficiency by using these elements. At least one of the reactors 3 and 4 may be provided.
Further, when the breaker 2, the voltage detectors 11 and 12, the control circuit 20, and the like are removed from the circuit of fig. 1, a circuit substantially similar to the three-level boost chopper circuit of fig. 17 is configured.
The operation of this embodiment will be described below with reference to fig. 2 to 6.
In the dc-dc converter of fig. 1, the control circuit 20 controls the on/off of the switching elements 5 and 6, and the same operation modes (first to fourth modes described below) as those of fig. 17 of the related art are sequentially executed, thereby boosting the voltages of the capacitors 8 and 10.
(1) First mode (fig. 2)
This is a state in which both the switching elements 5 and 6 are turned on. In this state, the current flows along the path of the dc power supply 1 → the circuit breaker 2 → the reactor 3 → the switching element 5 → the switching element 6 → the reactor 4 → the dc power supply 1, and the energy is stored in the reactors 3 and 4.
(2) Second mode (fig. 3)
This is a state in which the switching element 5 is continuously turned on and the switching element 6 is turned off. In this state, a current flows along a path of the dc power supply 1 → the circuit breaker 2 → the reactor 3 → the switching element 5 → the capacitor 10 → the diode 9 → the reactor 4 → the dc power supply 1, and the capacitor 10 is charged with energy stored in the reactors 3 and 4.
(3) Third mode (fig. 4)
This is a state where the switching element 5 is turned off and the switching element 6 is turned on, contrary to the second mode. In this state, a current flows along a path of the dc power supply 1 → the circuit breaker 2 → the reactor 3 → the diode 7 → the capacitor 8 → the switching element 6 → the reactor 4 → the dc power supply 1, and the capacitor 8 is charged with energy stored in the reactors 3 and 4.
(4) Fourth mode (fig. 5)
This is a state in which both the switching elements 5 and 6 are turned off. In this state, the current flows along the path of the dc power supply 1 → the circuit breaker 2 → the reactor 3 → the diode 7 → the capacitor 8 → the capacitor 10 → the diode 9 → the reactor 4 → the dc power supply 1, and the capacitors 8 and 10 are charged with the energy stored in the dc power supply 1 and the reactors 3 and 4.
In this way, capacitors 8 and 10 are boosted while being repeatedly charged, and are kept stable at a fixed voltage in accordance with the on/off ratio of switching elements 5 and 6.
Next, an operation when a short-circuit fault occurs in any one of the switching elements 5 and 6 (here, the switching element 6 is taken as an example) will be described.
When the switching element 6 has a short-circuit failure and the other switching element 5 is intact, the switching element 5 is turned on/off to alternately repeat the current flowing operation along the paths shown in fig. 6(a) and (b).
That is, in fig. 6(a) in which the switching element 5 is in the on state, the current flows along the path of the dc power supply 1 → the circuit breaker 2 → the reactor 3 → the switching element 5 → the switching element 6 (short-circuited state) → the reactor 4 → the dc power supply 1, and the energy is stored in the reactors 3 and 4.
In fig. 6(b) in which the switching element 5 is in the off state, the stored energy of the reactors 3 and 4 and the electric power of the dc power supply 1 cause the current to flow along a path of the dc power supply 1 → the circuit breaker 2 → the reactor 3 → the diode 7 → the capacitor 8 → the switching element 6 (short-circuited state) → the reactor 4 → the dc power supply 1.
When the operations of fig. 6(a) and (b) are repeated, only the step-up chopper operation for the capacitor 8 is performed. Therefore, when the switching elements 5, 6 are intact, the energy of the reactors 3, 4 shared by the two capacitors 8, 10 by the normal operation in the first to fourth modes is all supplied to one capacitor 8. As a result, the voltage of the capacitor 8 rises to a value higher than that in the normal state.
Since the voltage of the capacitor 8 is detected by the voltage detector 11 and the voltage detection value is input to the control circuit 20, the control circuit 20 determines that an overvoltage is applied to the capacitor 8.
The voltages of the capacitors 8 and 10 are detected by voltage detectors 11 and 12, and the detected values of these voltages are input to a control circuit 20. The control circuit 20 determines that the voltage of the capacitor 8 is higher than the voltage of the capacitor 10 and that a deviation of the voltage values of the two capacitors is greater than or equal to a predetermined value.
The control circuit 20 determines that an overvoltage is applied to the capacitor 8, or determines that the voltage of the capacitor 8 is higher than the voltage of the capacitor 10 and that the voltage values of the capacitors 8 and 10 deviate by a predetermined value or more, and estimates that a short-circuit failure has occurred in the switching element 6.
When it is estimated that the short-circuit fault has occurred in the switching element 6, the control circuit 20 outputs a signal for opening the circuit breaker 2 as a protection operation. However, there is a slight delay before the circuit breaker 2 actually opens, and the boosting operation of the capacitor 8 may be continued. Therefore, the control circuit 20 turns on the switching element 5 at a time point when it is estimated that the short-circuit failure of the switching element 6 has occurred, in other words, before the circuit breaker 2 is actually opened. In this way, the operation of the device is fixed to the mode of fig. 6(a) until the dc power supply 1 is completely disconnected from the device, and the voltage of the capacitor 8 can be prevented from continuously rising.
In addition, the above example is an example when the short-circuit failure occurs in the switching element 6, and when the short-circuit failure occurs in the switching element 5, the switching element 6 repeats on and off operations, and the capacitor 10 becomes an overvoltage. Further, since the switching element 6 repeats the on/off operation, the voltage of the capacitor 10 becomes higher than the voltage of the capacitor 8, and the voltage values of both capacitors deviate by a predetermined value or more.
Therefore, the control circuit 20 turns on the switching element 6 before the circuit breaker 2 is actually opened, based on the voltage detection values of the voltage detectors 11 and 12, thereby preventing the voltage of the capacitor 10 from continuously rising.
The control circuit 20 may issue a gate-on command to both the switching elements 5 and 6 when it is estimated that a short-circuit failure has occurred in either one of the switching element 5 and the switching element 6, and the same effect can be exhibited even in this case.
According to the first embodiment, when determining that an overvoltage is applied to the capacitor 8, the control circuit 20 estimates that a short-circuit fault has occurred in the switching element 6. Similarly, when determining that an overvoltage is applied to the capacitor 10, the control circuit 20 infers that a short-circuit fault has occurred in the switching element 5.
The control circuit 20 estimates that the switching element 6 has a short-circuit failure when the voltage of the capacitor 8 is higher than the voltage of the capacitor 10 and the voltage values of the capacitors 8 and 10 deviate by a predetermined value or more. Similarly, the control circuit 20 estimates that the short-circuit failure has occurred in the switching element 5 when the voltage of the capacitor 10 is higher than the voltage of the capacitor 8 and the voltage values of the capacitors 8 and 10 deviate by a predetermined value or more.
Therefore, when it is estimated that the short-circuit fault has occurred, it is preferable that the control circuit 20 performs a protection operation of opening the circuit breaker 2 and issues an alarm in an appropriate manner to prompt maintenance and inspection work including replacement of the switching elements.
Next, a second embodiment of the present invention corresponding to claim 5 will be described with reference to fig. 7.
In the second embodiment, current detectors 13 and 14 are connected in series to the switching elements 5 and 6, respectively, and current detection values output from the current detectors 13 and 14 are input to a control circuit 20. The control circuit 20 has the following structure: on/off signals to the switching elements 5, 6 are generated based on the current detection values of the switching elements 5, 6, and an opening/closing command to the circuit breaker 2 is generated.
Here, when a short-circuit failure occurs in any one of the switching elements 5 and 6 (the switching element 6 is taken as an example here), the current flowing operation described with reference to the first embodiment using fig. 6(a) and (b) is repeated. As a result, the current flowing through the switching element 6 gradually increases, and a current larger than that in the normal operation, that is, an overcurrent flows.
In the present embodiment, since the current flowing through the switching element 6 is detected by the current detector 13 and the detected current value is input to the control circuit 20, the control circuit 20 determines that an overcurrent flows through the switching element 6. Therefore, when it is determined that an overcurrent flows through the switching element 6, the control circuit 20 estimates that a short-circuit fault has occurred in the switching element 6.
The control circuit 20, which concludes that the short-circuit fault has occurred in the switching element 6, prevents the voltage of the capacitor 8 from continuously rising by turning on the switching element 5 before the circuit breaker 2 is opened.
The above example is an example when a short-circuit failure occurs in the switching element 6, and when a short-circuit failure occurs in the switching element 5, the switching element 6 repeats on and off operations, and an overcurrent flows through the switching element 5.
Therefore, the control circuit 20 turns on the switching element 6 before the circuit breaker 2 is opened, based on the current detection value of the current detector 14, thereby preventing the voltage of the capacitor 10 from continuously rising.
The control circuit 20 may issue a gate-on command to both the switching elements 5 and 6 when it is estimated that a short-circuit failure has occurred in either one of the switching element 5 and the switching element 6, and the same effect can be exhibited even in this case.
Next, a third embodiment of the present invention corresponding to claims 6 and 7 will be described with reference to fig. 8.
In the third embodiment, voltage detectors 11 and 12 are connected to both ends of switching elements 5 and 6, respectively, and voltage detection values output from these voltage detectors 11 and 12 are input to control circuit 20. The control circuit 20 has the following structure: on/off signals to the switching elements 5, 6 are generated based on the voltage detection values of the switching elements 5, 6, and an opening/closing command to the circuit breaker 2 is generated.
Here, when a short-circuit failure occurs in any one of the switching elements 5 and 6 (here, the switching element 6 is taken as an example), the voltage across the switching element 6 may be excessively smaller than the voltage during the on period in the normal state, as one aspect. This is because the internal resistance of the switching element 6 becomes a very low value compared to the normal state as a result of a short circuit of a channel which becomes a main current path inside the switching element 6.
As another mode, the voltage across the switching element 6 may be excessively larger than the voltage during the on period in a normal state. This is because the gate of the switching element 6 fails, and the switching element 6 cannot be turned off. At this time, the current flowing through the switching element 6 gradually increases because the current flowing through the switching element is repeated as described with reference to fig. 6(a) and (b). As a result, the element voltage becomes excessively higher during the period in which the gate command to the switching element 6 is on than during the current flowing during the on period in the normal operation.
In any of the above-described embodiments, the switching element 6 cannot be shifted to a normally off state while the gate command to the switching element 6 is off. Therefore, even if the gate command is off, the voltage across the switching element 6 is an excessively small voltage compared to the voltage during the off period in the normal state.
Therefore, in the present embodiment, the control circuit 20 estimates that the short-circuit failure has occurred in the switching element 6 when the voltage across the switching element 6 is excessively higher or smaller than the voltage in the on period in the normal state during the period in which the gate command of the switching element 6 is detected to be on.
Alternatively, when it is detected that the voltage across the switching element 6 is excessively lower than the voltage in the off period in the normal state during the period in which the gate command of the switching element 6 is off, it is estimated that the short-circuit failure has occurred in the switching element 6.
Then, the control circuit 20, which has concluded that the short-circuit fault has occurred in the switching element 6, prevents the voltage of the capacitor 8 from continuously rising by turning on the switching element 5 before the circuit breaker 2 is opened.
The above example is an example when the short-circuit failure occurs in the switching element 6, and the same estimation is performed also when the short-circuit failure occurs in the switching element 5. Then, the control circuit 20, which has concluded that the short-circuit fault has occurred in the switching element 5, prevents the voltage of the capacitor 10 from continuously rising by turning on the switching element 6 before the circuit breaker 2 is opened.
Further, the control circuit 20 may issue a gate-on command to both the switching elements 5 and 6 when it is estimated that a short-circuit failure has occurred in either one of the switching element 5 and the switching element 6, and the same effect can be exhibited even in this case.
Next, a fourth embodiment of the present invention corresponding to claim 8 will be described with reference to fig. 9.
In the fourth embodiment, current detectors 13 and 14 are connected in series to diodes 7 and 9, respectively, and current detection values output from these current detectors 13 and 14 are input to a control circuit 20. The control circuit 20 has the following structure: on/off signals to the switching elements 5, 6 are generated based on the detected current values of the diodes 7, 9, and an opening/closing command to the circuit breaker 2 is generated.
Here, a case where a short-circuit fault occurs in any one of the switching elements 5 and 6 (here, the switching element 6 is taken as an example) will be described. At this time, the flow operation described with reference to fig. 6(a) and (b) as the first embodiment is repeated. As a result, the current flowing through the diode 7 gradually increases, and a current larger than that in the normal operation, that is, an overcurrent flows.
In the present embodiment, the control circuit 20 determines that an overcurrent flows through the diode 7 based on the detected current value of the diode 7.
When determining that an overcurrent flows through the diode 7, the control circuit 20 infers that a short-circuit fault has occurred in the switching element 6.
The control circuit 20, which concludes that the short-circuit fault has occurred in the switching element 6, prevents the voltage of the capacitor 8 from continuously rising by turning on the switching element 5 before the circuit breaker 2 is opened.
When the switching element 5 has a short-circuit failure, the switching element 6 repeats on and off operations, and an overcurrent flows through the diode 9. The control circuit 20 determines that an overcurrent flows through the diode 9 based on the detected current value of the diode 9.
When determining that an overcurrent flows through the diode 9, the control circuit 20 estimates that a short-circuit fault has occurred in the switching element 5.
The control circuit 20, which concludes that the short-circuit fault has occurred in the switching element 5, prevents the voltage of the capacitor 10 from continuously rising by turning on the switching element 6 before the circuit breaker 2 is opened.
Further, the control circuit 20 may issue a gate-on command to both the switching elements 5 and 6 when it is estimated that a short-circuit failure has occurred in either one of the switching element 5 and the switching element 6, and the same effect can be exhibited even in this case.
Next, a fifth embodiment of the present invention corresponding to claim 9 will be described with reference to fig. 10.
In the fifth embodiment, voltage detectors 11 and 12 are connected to both ends of diodes 7 and 9, respectively, and voltage detection values output from these voltage detectors 11 and 12 are input to control circuit 20. The control circuit 20 has the following structure: on/off signals to the switching elements 5, 6 are generated based on the voltage detection values of the diodes 7, 9, and an opening/closing command to the circuit breaker 2 is generated.
Here, a case where a short-circuit fault occurs in any one of the switching elements 5 and 6 (here, the switching element 6 is taken as an example) will be described. At this time, the flow operation described in the first embodiment with reference to fig. 6(a) and (b) is repeated. As a result, the current flowing through the diode 7 gradually increases, and a current larger than that in the normal operation, that is, an overcurrent flows.
Therefore, the voltage of the diode 7 is excessively larger than the voltage in the diode on period (the period in which the gate command to the switching element 5 is off) in the normal operation. Here, the voltage of the diode 7 depends on the forward current-voltage characteristic.
In the present embodiment, the control circuit 20 determines that an overcurrent flows through the diode 7 when detecting that the voltage across the diode 7 is excessively larger than the voltage in the above-described period in the normal state during the period in which the gate command of the switching element 5 is off.
When determining that an overcurrent flows through the diode 7, the control circuit 20 infers that a short-circuit fault has occurred in the switching element 6.
The control circuit 20, which concludes that the short-circuit fault has occurred in the switching element 6, prevents the voltage of the capacitor 8 from continuously rising by turning on the switching element 5 before the circuit breaker 2 is opened.
When the switching element 5 has a short-circuit failure, the switching element 6 repeats on and off operations, and an overcurrent flows through the diode 9. Then, the voltage of the diode 9 is excessively larger than the voltage in the diode on period (period in which the gate command to the switching element 6 is off) in the normal operation.
When determining that an overcurrent flows through the diode 9, the control circuit 20 estimates that a short-circuit fault has occurred in the switching element 6. The control circuit 20 prevents the voltage of the capacitor 10 from continuously rising by turning on the switching element 6 before the circuit breaker 2 is opened.
Here, the control circuit 20 may issue the on gate command to both the switching elements 5 and 6 when it is estimated that the short-circuit failure has occurred in either one of the switching element 5 and the switching element 6, and the same effect can be exhibited even in this case.
Next, a sixth embodiment of the present invention corresponding to claim 10 will be described with reference to fig. 11.
In the sixth embodiment, a current detector 15 is connected in series to the reactor 3, and a current detection value output from the current detector 15 is input to the control circuit 20. In addition, although the case where the current detector 15 is connected in series to the reactor 3 will be described below, a current detector may be connected to either or both of the reactors 3 and 4, and the current detection value may be input to the control circuit 20.
The control circuit 20 has the following structure: on/off signals to the switching elements 5, 6 are generated based on the current detection value of the reactor 3, and an opening/closing command to the circuit breaker 2 is generated.
Here, a case where a short-circuit fault occurs in any one of the switching elements 5 and 6 (here, the switching element 6 is taken as an example) will be described. At this time, the flow operation described in the first embodiment with reference to fig. 6(a) and (b) is repeated. As a result, the current flowing through the reactor 3 gradually increases, and a current larger than that in the normal operation, that is, an overcurrent flows.
The above example is an example when a short-circuit fault occurs in the switching element 6, but when a short-circuit fault occurs in the switching element 5, the switching element 6 repeats on and off operations, and an overcurrent still flows through the reactor 3.
The control circuit 20 determines that an overcurrent flows through the reactor 3 based on the current detection value of the reactor 3.
When determining that an overcurrent flows through the reactor 3, the control circuit 20 estimates that a short-circuit fault has occurred in any of the switching elements 5 and 6.
The control circuit 20, which concludes that a short-circuit fault has occurred in either of the switching elements 5 or 6, prevents the voltage of the capacitor 8 or 10 from continuously rising by issuing a gate-on command to both of the switching elements 5 and 6 before the circuit breaker 2 is opened.
Next, a seventh embodiment of the present invention corresponding to claim 11 will be described with reference to fig. 12.
In the seventh embodiment, a voltage detector 16 is connected in parallel to the reactor 3, and a voltage detection value output from the voltage detector 16 is input to the control circuit 20. In addition, although the case where the voltage detector 16 is connected in parallel to the reactor 3 will be described below, a voltage detector may be connected to either or both of the reactors 3 and 4, and the voltage detection value may be input to the control circuit 20.
The control circuit 20 has the following structure: on/off signals to the switching elements 5, 6 are generated based on the voltage detection value of the reactor 3, and an opening/closing command to the circuit breaker 2 is generated.
Here, a case where a short-circuit fault occurs in any one of the switching elements 5 and 6 (here, the switching element 6 is taken as an example) will be described. At this time, the flow operation described in the first embodiment with reference to fig. 6(a) and (b) is repeated. As a result, the current flowing through the reactor 3 gradually increases, and a larger current flows than in the normal operation. Then, the voltage across the reactor 3 becomes excessively larger than that in the normal operation. Alternatively, while the gate command to the switching element 5 is on and the gate command to the switching element 6 is off, the voltage that should be originally received by the failed switching element 6 is received by the reactor 3. Therefore, the voltage across the reactor 3 is excessively larger than the value of the period in the normal state.
When the short-circuit failure occurs in the switching element 5, the voltage across the reactor 3 is also excessively larger than the voltage during the normal operation, as described above.
Therefore, the control circuit 20 determines that an overcurrent flows through the reactor 3 based on the voltage detection value at both ends of the reactor 3.
When determining that an overcurrent flows through the reactor 3, the control circuit 20 estimates that a short-circuit fault has occurred in any of the switching elements 5 and 6.
The control circuit 20, which has inferred that a short-circuit fault has occurred in either of the switching elements 5 or 6, can prevent the voltage of the capacitor 8 or 10 from continuously rising by issuing a gate-on command to both of the switching elements 5 and 6 before the circuit breaker 2 is opened.
Next, an eighth embodiment of the present invention corresponding to claim 12 will be described with reference to fig. 13.
In the eighth embodiment, a current detector 17 is connected to a wiring (hereinafter, referred to as an intermediate wiring) connecting a connection point between the switching elements 5 and 6 and a connection point between the capacitors 8 and 10, and a current detection value output from the current detector 17 is input to the control circuit 20. The control circuit 20 has the following structure: on/off signals to the switching elements 5, 6 are generated based on the detected current value of the intermediate wiring, and an opening/closing command to the circuit breaker 2 is generated.
Here, a case where a short-circuit fault occurs in any one of the switching elements 5 and 6 (here, the switching element 6 is taken as an example) will be described. At this time, the flow operation described in the first embodiment with reference to fig. 6(a) and (b) is repeated. As a result, the current flowing through the intermediate wiring gradually increases, and a current larger than that in the normal operation, that is, an overcurrent flows.
The above example is an example when a short-circuit failure occurs in the switching element 6, but when a short-circuit failure occurs in the switching element 5, the switching element 6 repeats on and off operations, and an overcurrent still flows through the intermediate wiring.
The control circuit 20 determines that an overcurrent flows through the intermediate wiring based on the current detection value of the current detector 17.
When it is determined that an overcurrent flows through the intermediate wiring, the control circuit 20 estimates that a short-circuit failure has occurred in any of the switching elements 5 and 6.
The control circuit 20, which concludes that a short-circuit fault has occurred in either of the switching elements 5 or 6, prevents the voltage of the capacitor 8 or 10 from continuously rising by issuing a gate-on command to both of the switching elements 5 and 6 before the circuit breaker 2 is opened.
Next, a ninth embodiment of the present invention corresponding to claim 13 will be described with reference to fig. 14.
In the present embodiment, voltage detectors 11 and 12 are connected between gates (base regions as control electrodes in bipolar transistors) and emitters of the switching elements 5 and 6, respectively, and voltage detection values thereof are input to a control circuit 20. Further, if the gate voltage can be detected smoothly, the voltage detectors 11 and 12 may be connected between the gates and collectors of the switching elements 5 and 6, respectively.
The control circuit 20 has the following structure: on/off signals to the switching elements 5, 6 are generated from voltage detection values of the gates of the switching elements 5, 6, and an opening/closing command to the circuit breaker 2 is generated.
Here, a case where the gate of any one of the switching elements 5 and 6 (here, the switching element 6 is taken as an example) is short-circuited at all times or the gate potential is high at all times will be described. In this case, in the present embodiment, the control circuit 20 determines whether the gate of the switching element 6 is always short-circuited or the gate potential is always high based on the detected value of the gate voltage.
When the control circuit 20 determines that the gate of the switching element 6 is always short-circuited or that the gate potential is always high, it is estimated that a short-circuit failure has occurred in the switching element 6.
The control circuit 20, which concludes that a short-circuit fault has occurred in the switching element 6, prevents the voltage of the capacitor 8 from continuously rising by turning on the switching element 5 before the circuit breaker 2 is opened.
When the control circuit 20 determines that the gate of the switching element 5 is always short-circuited or that the gate potential is always high, it is estimated that a short-circuit failure has occurred in the switching element 5.
The control circuit 20, which concludes that the short-circuit failure has occurred in the switching element 5, prevents the voltage of the capacitor 10 from continuously rising by turning on the switching element 6 before the circuit breaker 2 is opened based on the detected voltage value of the gate.
Further, the control circuit 20 may issue a gate-on command to both the switching elements 5 and 6 when it is estimated that a short-circuit failure has occurred in either one of the switching element 5 and the switching element 6, and the same effect can be exhibited even in this case.
Next, a tenth embodiment of the present invention corresponding to claim 14 will be described with reference to fig. 15.
In the present embodiment, current detectors 13 and 14 are connected to gates (base regions as control electrodes in bipolar transistors) as control electrodes of the switching elements 5 and 6, respectively, and current detection values thereof are input to a control circuit 20.
The control circuit 20 has the following structure: on/off signals to the switching elements 5, 6 are generated from the current detection values of the gates of the switching elements 5, 6, and an opening/closing command to the circuit breaker 2 is generated.
Here, a case where the gate current of any one of the switching elements 5 and 6 (here, the switching element 6 is taken as an example) is an overcurrent or a constant current will be described. In this case, in the present embodiment, the control circuit 20 determines whether the gate current of the switching element 6 is an overcurrent or a constant current based on the detected gate current value.
When determining that the gate current of the switching element 6 is an overcurrent or a constant current, the control circuit 20 estimates that a short-circuit fault has occurred in the switching element 6.
The control circuit 20, which concludes that the short-circuit fault has occurred in the switching element 6, prevents the voltage of the capacitor 8 from continuously rising by turning on the switching element 5 before the circuit breaker 2 is opened.
When the control circuit 20 determines that the gate current of the switching element 5 is an overcurrent or a constant current, it is estimated that a short-circuit fault has occurred in the switching element 5.
The control circuit 20, which concludes that the short-circuit fault has occurred in the switching element 5, prevents the voltage of the capacitor 10 from continuously rising by turning on the switching element 6 before the circuit breaker 2 is opened.
Further, the control circuit 20 may issue a gate-on command to both the switching elements 5 and 6 when it is estimated that a short-circuit failure has occurred in either one of the switching element 5 and the switching element 6, and the same effect can be exhibited even in this case.
Next, an eleventh embodiment of the present invention corresponding to claim 15 will be described with reference to fig. 16.
In the eleventh embodiment, current detectors 13 and 14 are connected in series to capacitors 8 and 10, respectively, and current detection values output from these current detectors 13 and 14 are input to a control circuit 20. The control circuit 20 has the following structure: on/off signals to the switching elements 5, 6 are generated based on the current detection values of the capacitors 8, 10, and an opening/closing command to the circuit breaker 2 is generated.
Here, a case where a short-circuit fault occurs in any one of the switching elements 5 and 6 (here, the switching element 6 is taken as an example) will be described. When the switching element 6 has a short-circuit fault, an excessive current, that is, an overcurrent flows through the capacitor 8 as compared with the normal operation. In particular, an overcurrent flows during a steady state period, that is, a period from when the switching element 6 performs switching through a transition period to when the next switching is started.
The control circuit 20 determines that an overcurrent flows through the capacitor 8 based on the current detection value of the capacitor 8 output from the current detector 13. When determining that an overcurrent flows through the capacitor 8, the control circuit 20 estimates that a short-circuit fault has occurred in the switching element 6.
When it is estimated that the short-circuit failure has occurred in the switching element 6, the control circuit 20 prevents the voltage of the capacitor 8 from continuously rising by turning on the switching element 5 before the circuit breaker 2 is opened.
The above example is an example when a short-circuit fault occurs in the switching element 6, and when a short-circuit fault occurs in the switching element 5, an overcurrent flows through the capacitor 10. When it is determined that an overcurrent flows through the capacitor 10 based on the current detection value of the capacitor 10 output from the current detector 14, the control circuit 20 estimates that a short-circuit fault has occurred in the switching element 5.
The control circuit 20, which estimates that the short-circuit fault has occurred in the switching element 5, can prevent the voltage of the capacitor 10 from continuously rising by turning on the switching element 6 before the circuit breaker 2 is opened.
The control circuit 20 may issue a gate-on command to both the switching elements 5 and 6 when it is estimated that a short-circuit failure has occurred in either one of the switching element 5 and the switching element 6, and the same effect can be exhibited even in this case.
As mentioned in the first embodiment, the delay time from the output of the opening command of the circuit breaker by the control circuit to the actual opening of the circuit breaker is generally longer than the delay time from the output of the on gate command to the switching element to the actual on of the switching element. Therefore, the control circuit of the present invention needs to output a gate-on command regardless of the timing of outputting the opening command of the circuit breaker, so that the predetermined switching element completes the opening operation before the actual opening of the circuit breaker.
Namely, the basic idea of the present invention is: when it is estimated that a short-circuit fault occurs in a switching element, a predetermined switching element is turned on before a breaker opening protection operation is performed, thereby suppressing a voltage rise of a capacitor and preventing a low-withstand-voltage switching element or a low-withstand-voltage capacitor from being damaged.
Description of the reference symbols
1: direct current power supply
2: circuit breaker
3. 4: electric reactor
5. 6: semiconductor switching element
7. 9: diode with a high-voltage source
8. 10: capacitor with a capacitor element
11. 12, 16: voltage detector
13. 14, 15, 17: current detector
20: control circuit
IN1, IN 2: input terminal
OUT1, OUT 2: output terminal
Claims (16)
1. A dc-dc conversion apparatus comprising:
a switching element series circuit in which a first switching element and a second switching element are connected in series and connected to both ends of a direct current power supply;
a reactor connected between the dc power supply and the switching element series circuit;
a circuit breaker between the direct-current power supply and the switching element series circuit;
a capacitor series circuit in which first and second capacitors are connected in series;
first and second diodes connected between both ends of the switching element series circuit and both ends of the capacitor series circuit, respectively; and
a control circuit for controlling on/off of the first and second switching elements,
the connection point of the first and second switching elements is connected to the connection point of the first and second capacitors,
a step-up circuit for stepping up a voltage of the DC power supply and outputting the voltage from both ends of the capacitor series circuit by performing an on/off chopping operation of the first and second switching elements,
when it is estimated that at least one of the first and second switching elements has a short-circuit fault, the control circuit issues a conduction command to the other switching element or both switching elements before opening the circuit breaker.
2. The DC-DC converting apparatus according to claim 1,
the control circuit sends a conduction command to the switching element and a brake-off command to the circuit breaker,
and the breaker is switched off after the switching element is switched on.
3. The DC-DC converting apparatus according to claim 1,
includes first and second voltage detectors for detecting voltages of the first and second capacitors, respectively,
the control circuit infers that a short-circuit fault has occurred in the second switching element when it is determined that an overvoltage is applied to the first capacitor, and infers that a short-circuit fault has occurred in the first switching element when it is determined that an overvoltage is applied to the second capacitor.
4. The DC-DC converting apparatus according to claim 1,
includes first and second voltage detectors for detecting voltages of the first and second capacitors, respectively,
the control circuit estimates that a short-circuit failure has occurred in the second switching element when it is determined that the voltage of the first capacitor is higher than the voltage of the second capacitor and that a deviation between the voltage values of the two capacitors is equal to or greater than a predetermined value, and estimates that a short-circuit failure has occurred in the first switching element when it is determined that the voltage of the second capacitor is higher than the voltage of the first capacitor and that a deviation between the voltage values of the two capacitors is equal to or greater than a predetermined value.
5. The DC-DC converting apparatus according to claim 1,
includes first and second current detectors for detecting currents of the first and second switching elements, respectively,
the control circuit estimates that a short-circuit fault has occurred in the first switching element when it is determined that an overcurrent flows in the first switching element, and estimates that a short-circuit fault has occurred in the second switching element when it is determined that an overcurrent flows in the second switching element.
6. The DC-DC converting apparatus according to claim 1,
includes first and second voltage detectors for detecting voltages of the first and second switching elements, respectively,
the control circuit estimates that a short-circuit failure has occurred in the first switching element when it is determined that a voltage across the first switching element is equal to or higher than a predetermined value or equal to or lower than a predetermined value during a period in which an on command is issued to the first switching element, and estimates that a short-circuit failure has occurred in the second switching element when it is determined that a voltage across the second switching element is equal to or higher than a predetermined value or equal to or lower than a predetermined value during a period in which an on command is issued to the second switching element.
7. The DC-DC converting apparatus according to claim 1,
includes first and second voltage detectors for detecting voltages of the first and second switching elements, respectively,
the control circuit estimates that a short-circuit failure has occurred in the first switching element when it is determined that a voltage across the first switching element is equal to or lower than a predetermined value during a period in which an off command is issued to the first switching element, and estimates that a short-circuit failure has occurred in the second switching element when it is determined that a voltage across the second switching element is equal to or lower than a predetermined value during a period in which an off command is issued to the second switching element.
8. The DC-DC converting apparatus according to claim 1,
comprises a first current detector and a second current detector, which respectively detect the current of the first diode and the second diode,
the control circuit estimates that a short-circuit fault has occurred in the second switching element when it is determined that an overcurrent flows in the first diode, and estimates that a short-circuit fault has occurred in the first switching element when it is determined that an overcurrent flows in the second diode.
9. The DC-DC converting apparatus according to claim 1,
comprises a first and a second voltage detector for detecting the voltage of the first and the second diodes respectively,
the control circuit estimates that a short-circuit failure has occurred in the second switching element when the voltage across the first diode is determined to be equal to or greater than a predetermined value during a period in which an off command is issued to the first switching element, and estimates that a short-circuit failure has occurred in the first switching element when the voltage across the second diode is determined to be equal to or greater than a predetermined value during a period in which an off command is issued to the second switching element.
10. The DC-DC converting apparatus according to claim 1,
includes a current detector that detects a current of the reactor,
the control circuit infers that at least one of the first and second switching elements has a short-circuit fault when it is determined that an overcurrent flows through the reactor.
11. The DC-DC converting apparatus according to claim 1,
includes a voltage detector that detects a voltage of the reactor,
the control circuit estimates that at least one of the first and second switching elements has a short-circuit fault when it is determined that the voltage across the reactor is equal to or higher than a predetermined value.
12. The DC-DC converting apparatus according to claim 1,
a current detector for detecting a current of a wiring connecting a connection point between the first and second switching elements and a connection point between the first and second capacitors,
the control circuit infers that at least one of the first and second switching elements has a short-circuit failure when it is determined that an overcurrent flows through the wiring.
13. The DC-DC converting apparatus according to claim 1,
the control circuit estimates that a short-circuit failure has occurred in the first switching element when it is determined that the control electrode of the first switching element is always short-circuited or the potential of the control electrode is always high, and estimates that a short-circuit failure has occurred in the second switching element when it is determined that the control electrode of the second switching element is always short-circuited or the potential of the control electrode is always high.
14. The DC-DC converting apparatus according to claim 1,
the control circuit estimates that a short-circuit failure has occurred in the first switching element when it is determined that the current flowing through the control electrode of the first switching element is an overcurrent or always flows, and estimates that a short-circuit failure has occurred in the second switching element when it is determined that the current flowing through the control electrode of the second switching element is an overcurrent or always flows.
15. The DC-DC converting apparatus according to claim 1,
comprises a first current detector and a second current detector, which respectively detect the current of the first capacitor and the second capacitor,
the control circuit estimates that a short-circuit fault has occurred in the second switching element when it is determined that an overcurrent flows in the first capacitor, and estimates that a short-circuit fault has occurred in the first switching element when it is determined that an overcurrent flows in the second capacitor.
16. The DC-DC converting apparatus according to claim 1,
the control circuit generates an alarm when it is inferred that the first or second switching element has a short-circuit fault.
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| JP2015161549 | 2015-08-19 | ||
| JP2015-161549 | 2015-08-19 | ||
| JP2015227299A JP6606993B2 (en) | 2015-08-19 | 2015-11-20 | DC-DC converter |
| JP2015-227299 | 2015-11-20 |
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| CN106469980A CN106469980A (en) | 2017-03-01 |
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| CN107070215B (en) * | 2017-04-12 | 2023-05-16 | 特变电工西安电气科技有限公司 | Three-level boost common-ground system and control method thereof |
| JP6956553B2 (en) * | 2017-07-21 | 2021-11-02 | 新電元工業株式会社 | Power supply and control method of power supply |
| JP7000809B2 (en) | 2017-11-14 | 2022-01-19 | 富士電機株式会社 | Step-down chopper circuit |
| KR101961350B1 (en) * | 2018-02-22 | 2019-07-17 | 주식회사 팩테크 | Step-up converter for railyway vehicle |
| CN109917895B (en) * | 2019-03-13 | 2021-01-22 | 浪潮商用机器有限公司 | Control device and control method for voltage regulation module VRM |
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| JP2000166221A (en) * | 1998-11-26 | 2000-06-16 | Mitsubishi Electric Corp | Double chopper |
| JP2008295228A (en) * | 2007-05-25 | 2008-12-04 | Toshiba Mitsubishi-Electric Industrial System Corp | Step-up chopper circuit, step-down chopper circuit, and dc-dc converter circuit using same |
| JP2013038921A (en) * | 2011-08-08 | 2013-02-21 | Tabuchi Electric Co Ltd | Step-up chopper circuit, and power supply device including the same |
| JP2014011897A (en) * | 2012-06-29 | 2014-01-20 | Honda Motor Co Ltd | Electric power conversion system in electric vehicle |
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| CN101630908B (en) * | 2008-07-17 | 2012-12-12 | 华硕电脑股份有限公司 | Power supply device, over voltage protection unit thereof and over voltage protection method thereof |
| CN102237799B (en) * | 2011-07-12 | 2013-04-10 | 珠海泰坦新能源系统有限公司 | Three-level resonant converter clamped by resonant capacitor and transformer primary side |
| JP6040582B2 (en) * | 2012-06-14 | 2016-12-07 | 富士電機株式会社 | Protection control method for multi-level power conversion circuit |
| WO2015063869A1 (en) * | 2013-10-29 | 2015-05-07 | 三菱電機株式会社 | Dc power supply device and refrigeration cycle device |
| JP6072937B2 (en) * | 2013-11-26 | 2017-02-01 | 三菱電機株式会社 | DC power supply device and refrigeration cycle application equipment including the same |
| FR3015805B1 (en) * | 2013-12-20 | 2017-03-10 | Gen Electric | SWEET SWITCHING INTERLETING HOPPER |
| CN106451428B (en) * | 2016-10-18 | 2019-07-23 | 国网浙江省电力公司电力科学研究院 | A kind of mixed type Research on Unified Power Quality Conditioner with short-circuit current-limiting function |
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| JP2000166221A (en) * | 1998-11-26 | 2000-06-16 | Mitsubishi Electric Corp | Double chopper |
| JP2008295228A (en) * | 2007-05-25 | 2008-12-04 | Toshiba Mitsubishi-Electric Industrial System Corp | Step-up chopper circuit, step-down chopper circuit, and dc-dc converter circuit using same |
| JP2013038921A (en) * | 2011-08-08 | 2013-02-21 | Tabuchi Electric Co Ltd | Step-up chopper circuit, and power supply device including the same |
| JP2014011897A (en) * | 2012-06-29 | 2014-01-20 | Honda Motor Co Ltd | Electric power conversion system in electric vehicle |
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| CN106469980A (en) | 2017-03-01 |
| JP6606993B2 (en) | 2019-11-20 |
| JP2017042028A (en) | 2017-02-23 |
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