JP7226551B2 - DC power supply - Google Patents

Description

TECHNICAL FIELD The present invention relates to a direct current power supply, and more particularly to a direct current power supply having a current interrupting section that interrupts high voltage current at high speed.

A fuse or a mechanical DC circuit breaker is generally used to protect against fault currents at the output of a DC power supply. However, conventional mechanical DC circuit breakers take a long time to break compared to the current withstand capability of power semiconductors such as IGBTs used in DC power supply devices, and the semiconductor elements cannot be protected in time. There is concern that it will spread. As a conventional means for solving this problem, there is known a power supply device including a current interrupting section that rapidly interrupts a high-voltage current. Such a DC power supply device is described, for example, in JP-A-2019-36405.

The above Japanese Patent Application Laid-Open No. 2019-36405 discloses a power supply device including a main circuit switch (thyristor or mechanical switch) provided between a power supply and a load, and a capacitor connected in parallel to the main circuit switch. disclosed. In the power supply device, when an accident current flows to the main circuit switch, a superimposed current flows from the capacitor to the main circuit switch. The superimposed current flows through the main circuit switch in the opposite direction to the fault current. As a result, the accident current is canceled by the superimposed current, so that the main circuit switch can be cut off at high speed. Similarly, when a mechanical switch is used as the main circuit switch, arcing at the main circuit contact is suppressed when the switch is turned off, making it possible to turn off the main circuit switch at high speed. Furthermore, it is possible to suppress the conduction loss from increasing.

JP 2019-36405 A

However, in Japanese Patent Application Laid-Open No. 2019-36405, it is necessary to provide a commutation capacitor in order to allow a superimposed current to flow through the main circuit switch. Here, since the commutation capacitor is a relatively large element, the size of the power supply device may increase. Therefore, there is a demand for a DC power supply device that can cut off the fault current at high speed and that can be downsized.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to be able to cut off fault current at high speed while suppressing an increase in conduction loss. Another object of the present invention is to provide a direct-current power supply capable of being miniaturized.

To achieve the above object, a DC power supply device according to one aspect of the present invention includes a rectifier that converts an AC input voltage supplied from an AC voltage source into a DC voltage, and an electrical connection between the rectifier and a load. and a control unit that controls the rectifier and the current interrupter, and the current interrupter includes a series switching element having a withstand voltage higher than the rated voltage of the DC voltage, and a series switching element. A series circuit connected in series to the load side and having a self-arc-extinguishing conduction switching element whose withstand voltage is lower than the rated voltage, and a series circuit connected in parallel to the series circuit and having a withstand voltage higher than the rated voltage a self-arc-extinguishing semiconductor switching element, wherein each of the series switching element and the conduction switching element has a smaller conduction loss than the semiconductor switching element, and the controller turns off the series switching element and the conduction switching element. Control is performed to turn off the semiconductor switching elements after the control is performed at the same time, or control is performed to turn off the series switching element, the conduction switching element, and the semiconductor switching element in that order, thereby cutting off the current interrupting part. The current interrupting unit includes a diode element connected in parallel to the series circuit and connected in series with the semiconductor switching element, and the sum of the on-voltage of the diode element and the on-voltage of the semiconductor switching element The value is greater than the total value of the ON voltage of the series switching element and the ON voltage of the conduction switching element, so that the current value flowing through the diode element and the semiconductor switching element is equal to the current value flowing through the series switching element and conduction switching element. and further comprising a power storage unit that stores the DC power converted by the rectifier. are turned off at the same time, and then the semiconductor switching elements are turned off. It is configured to perform control to cut off the flowing current by the current cutoff unit . Note that the serial switching element includes not only a semiconductor element but also a mechanical switch.

In the DC power supply device according to one aspect of the present invention, as described above, the semiconductor switching element is turned off after simultaneously performing control to turn off the series switching element and the conduction switching element, or the series switching element, The conduction switching element and the semiconductor switching element are turned off in this order. As a result, the current flowing through the series switching element and the conduction switching element is commutated to the semiconductor switching element, so that the semiconductor switching element can be turned off while all the current is flowing through the semiconductor switching element. Here, since no arc is generated in the semiconductor switching element when it is turned off, there is no need to apply a superimposed current to the semiconductor switching element using the charging energy of the capacitor in order to turn off the semiconductor switching element at high speed. Therefore, by controlling as described above, the accident current can be interrupted at high speed by the semiconductor switching element without using a capacitor. As a result, it is possible to reduce the size of the DC power supply while interrupting the fault current at high speed.
Further, the current interrupting section includes a diode element connected in parallel to the series circuit and connected in series with the semiconductor switching element, and the total value of the on-voltage of the diode element and the on-voltage of the semiconductor switching element is equal to the series switching It is greater than the sum of the on-voltage of the element and the on-voltage of the conduction switching element. With this configuration, the current flowing through the series circuit of the diode element and the semiconductor switching element, which have a relatively large total ON voltage, can be made relatively small. As a result, the amount of heat generated by the diode element and the semiconductor switching element can be made relatively small.

Further, when only the semiconductor switching element is provided by connecting the series circuit of the series switching element and the conduction switching element in parallel with the semiconductor switching element, the conduction loss of which is relatively small compared to that of the semiconductor switching element. At least part of the current can also flow through the series circuit side, which has a relatively small conduction loss. As a result, conduction loss (power consumption) can be suppressed as compared with the case where only semiconductor switching elements are provided. As a result, the fault current can be interrupted at high speed while suppressing an increase in conduction loss, and the size of the DC power supply can be reduced.

Further, by commutating the current flowing through the series switching element and the conduction switching element to the semiconductor switching element, the semiconductor switching element can be turned off in a state where no current flows through the series switching element and the conduction switching element. can. As a result, when the semiconductor switching element is turned off, the rated voltage of the DC power supply is applied to the semiconductor switching element and the series switching element, while the series switching element provided in the preceding stage of the conduction switching element is in the off state. The voltage applied to the conduction switching element becomes substantially zero. As a result, it is possible to prevent a voltage (rated voltage) higher than the withstand voltage from being applied to the conduction switching element, so that it is possible to prevent the conduction switching element from being destroyed. Since the breakdown voltage of each of the series switching element and the conduction switching element is equal to or higher than the rated voltage, each of the series switching element and the conduction switching element is not destroyed. Thereby, it is possible to suppress breakage of the element (conduction switching element) of the current interrupting portion.

In the DC power supply device according to the above aspect, preferably, the control unit simultaneously performs control to turn off the series switching element and the conduction switching element, and then performs control to turn off the semiconductor switching element, so that the current interrupting unit is configured to perform control to cut off the Here, if there is a time difference between the control for turning off the series switching element and the control for turning off the conduction switching element, the control for turning off the semiconductor switching element is delayed by the time difference. The time during which the current flows increases. By simultaneously performing control to turn off the series switching element and the conduction switching element, it is possible to suppress a delay in the control to turn off the semiconductor switching element and to prevent an increase in the time during which the current flows through the semiconductor switching element. can be suppressed. Here, the size of the semiconductor switching element depends on the energization time. Therefore, by suppressing an increase in the time during which the current flows through the semiconductor switching element, it is possible to use an element having a relatively short energization time as the semiconductor switching element. As a result, it is possible to suppress an increase in the size of the semiconductor switching element.

In the DC power supply device according to the above aspect, preferably, the control unit performs control to turn off the conduction switching element so that the current flowing through the series circuit of the series switching element and the conduction switching element is directed to the semiconductor switching element. After the current stops flowing through the series switching element due to the commutation, the semiconductor switching element is controlled to turn off, thereby controlling the current interrupting section to cut off. With this configuration, it is possible to prevent the semiconductor switching element from being turned off while current is still flowing through the series circuit of the series switching element and the conduction switching element. As a result, when the semiconductor switching element is turned off, the series switching element can be reliably turned off. As a result, application of a high voltage (rated voltage) to the conduction switching element can be more reliably suppressed.

In this case, the conduction switching element is configured to be capable of switching at a higher speed than the series switching element, and the control unit controls the conduction switching element to be turned off for a period equal to or longer than the turn-off time of the series switching element. After a predetermined period of time, the semiconductor switching element is controlled to be turned off, thereby controlling the current cut-off section to be cut off. With this configuration, the control to turn off the semiconductor switching element can be more reliably performed after the current stops flowing through the series switching element.

In the DC power supply device according to the above aspect, preferably, the control unit performs control to turn on the series switching element and the conduction switching element after performing control to turn on the semiconductor switching element, thereby turning on the current interrupting unit. It is configured to control to conduct. With this configuration, it is possible to prevent the series switching element and the conduction switching element from being turned on while the semiconductor switching element is turned off. voltage) can be suppressed.

In this case, the control unit performs control to turn on the series switching element and the conduction switching element after the output voltage of the current interrupting unit is increased by turning on the semiconductor switching element and the output voltage stops increasing. is configured to perform control to turn on the current interrupter. Here, the voltage applied to the semiconductor switching element decreases as the output voltage of the current interrupter increases. Therefore, by performing control to turn on the series switching element and the conduction switching element after the output voltage of the current interrupter stops increasing, the series switching element and the conduction switching element are turned on after the voltage applied to the semiconductor switching element becomes minimum. The device can be turned on. As a result, the conduction switching element connected in parallel to the semiconductor switching element is also applied with the same voltage as the voltage applied to the semiconductor switching element, so that application of a high voltage to the conduction switching element can be suppressed. can.

In addition, since the conduction loss of each of the series switching element and the conduction switching element is smaller than the conduction loss of the semiconductor switching element, the on-resistance of each of the series switching element and the conduction switching element is lower than the on-resistance of the semiconductor switching element. relatively small. Therefore, the series switching element and the conduction switching element having a relatively small on-resistance are supplied with a relatively larger current than the current flowing through the series circuit of the diode element and the semiconductor switching element. It is possible to suppress the increase in the amount of heat generated by the heat treatment. As a result, it is possible to suppress an increase in the amount of heat generated by the current interrupting portion as a whole.

The DC power supply device according to the above aspect preferably further includes a power storage unit that stores the DC power converted by the rectifier, and the control unit controls, when the DC power in the power storage unit is supplied to the load, By controlling to turn off the switching element and the conduction switching element at the same time and then turning off the semiconductor switching element, or by turning off the series switching element, the conduction switching element, and the semiconductor switching element in this order. , the current interrupting unit is configured to perform control for interrupting the current flowing from the power storage unit to the load. According to this configuration, it is possible to suppress the breakage of the element of the current interrupting portion while suppressing an increase in conduction loss during current conduction.

In the DC power supply device according to the above aspect, the series switching element, conduction switching element, and semiconductor switching element preferably include a thyristor, MOSFET, and IGBT, respectively. With this configuration, since the thyristor has a relatively low on-state voltage, the use of the thyristor as the series switching element effectively suppresses an increase in conduction loss during current conduction (during normal operation of the DC power supply). can be suppressed to In addition, since the IGBT switches at a relatively high speed and has a high withstand voltage, by using the IGBT as the semiconductor switching element, the current can be interrupted at high speed, and a high voltage (rated voltage) is applied to the semiconductor switching element. Even in such a case, destruction of the semiconductor switching element can be suppressed. In addition, since MOSFETs have relatively low conduction loss, by using MOSFETs as conduction switching elements, it is possible to more effectively suppress an increase in conduction loss during current conduction (during normal operation of the DC power supply). can. In addition, since the MOSFET switches at a relatively high speed, it is possible to relatively quickly commutate the current flowing through the DC circuit of the series switching element and the conduction switching element to the semiconductor switching element when the current is cut off. As a result, the time required for the current interrupter to interrupt the current can be shortened.

ADVANTAGE OF THE INVENTION According to this invention, as mentioned above, while suppressing that conduction loss increases, a fault current can be cut off at high speed, and a direct-current power supply device can be reduced in size.

It is a figure which shows the structure of the DC power supply device by one Embodiment. FIG. 4 is a diagram showing gate signals and current values of respective elements of a current interrupter according to one embodiment; FIG. 10 is a diagram showing current flow when the IGBT is turned on and conduction control is started (period A) in the current interrupting unit according to the embodiment; FIG. 10 is a diagram showing the current flow when the thyristor and MOSFET are turned on (period B) in the current blocking section according to one embodiment. FIG. 10 is a diagram showing a current flow when a thyristor and a MOSFET are turned off in the current interrupting unit according to one embodiment and current interrupting control is started (period C); FIG. 10 is a diagram showing the state of the current interrupting unit when the IGBT according to the embodiment is turned off and the current interrupting control is completed (period D);

Embodiments embodying the present invention will be described below with reference to the drawings.

[This embodiment]
The configuration of a DC power supply device 100 according to the present embodiment will be described with reference to FIGS. 1 to 6. FIG.

(Configuration of DC power supply)
As shown in FIG. 1, the DC power supply device 100 includes a rectifier 1, a power storage unit 2, a current sensor 3, a current interrupting unit 4, a control unit 5, a driving unit 6, and a voltage sensor 7. . DC power supply device 100 is used, for example, in a solar power generation system.

The rectifier 1 is configured to convert an AC input voltage input from an external system 101 into a DC voltage. An AC circuit breaker 102 is provided outside the DC power supply 100 to switch between conduction and interruption of current between the system 101 and the DC power supply 100 . The system 101 is an example of an "AC voltage source" in the claims.

Power storage unit 2 is configured to store the DC power converted by rectifier 1 . Power storage unit 2 serves as a power source to supply power to load 103 when power is not supplied from system 101 (during a power outage or the like).

Current sensor 3 is configured to detect the value of current flowing between rectifier 1 (power storage unit 2 ) and current interrupting unit 4 .

Current interrupter 4 is configured to electrically connect and disconnect between rectifier 1 (power storage unit 2 ) and load 103 . Specifically, the current interrupting unit 4 includes a thyristor 40 and a self arc-extinguishing MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) 41 connected in series with the thyristor 40 . The MOSFET 41 is connected in series with the thyristor 40 on the load 103 side of the thyristor 40 . The thyristor 40 and the MOSFET 41 are examples of a "serial switching element" and a "conduction switching element" in the claims, respectively.

Further, the current interrupting portion 4 includes a diode element 42 and a self arc-extinguishing IGBT (Insulated Gate Bipolar Transistor) 43 . The IGBT 43 is connected in series with the diode element 42 on the load 103 side with respect to the diode element 42 . As the IGBT 43, RB (Reverse Blocking)-IGBT and RC (Reverse Conducting)-IGBT may be used. In addition, IGBT43 is an example of the "semiconductor switching element" of a claim.

A series circuit of the thyristor 40 and the MOSFET 41 is connected in parallel with a series circuit of the diode element 42 and the IGBT 43 .

Also, the withstand voltage (for example, 1600 V) of thyristor 40 is higher than the rated voltage (for example, 750 V) of the DC voltage used in DC power supply device 100 . Also, the breakdown voltage (for example, 10 to 20 V) of MOSFET 41 is lower than the rated voltage. Also, the breakdown voltage (for example, 1600 V) of the IGBT 43 is higher than the rated voltage.

Also, the conduction loss of each of thyristor 40 and MOSFET 41 is smaller than the conduction loss of IGBT 43 (when the same magnitude of current is flowing through thyristor 40 and MOSFET 41). Each of MOSFET 41 and IGBT 43 is configured to be capable of switching faster than thyristor 40 . In addition, MOSFET41 is comprised so that switching is possible at higher speed than IGBT43.

In addition, the current interrupting section 4 interrupts the current using a relatively small number of elements (four elements of the thyristor 40, the MOSFET 41, the diode element 42, and the IGBT 43). In contrast, for example, in a configuration in which a discharge current from a capacitor causes a canceling current to flow through a switch, in addition to the switch and capacitor, a relatively large number of elements (parts) such as resistance elements, reactors, thyristors, and diodes are required. is. Therefore, since the current interrupting portion 4 is composed of a relatively small number of elements, it is possible to suppress an increase in the failure rate of the current interrupting portion 4 (suppress a decrease in reliability).

Also, the control unit 5 is configured to control the rectifier 1 and the current interrupting unit 4 . Specifically, the control unit 5 controls the operation of the rectifier 1 by transmitting gate signals to switching elements (not shown) provided in the rectifier 1 . Further, the control unit 5 is configured to transmit a command signal for controlling the current interrupting unit 4 to the driving unit 6 .

Specifically, the drive unit 6 is configured to transmit a gate signal for turning on or off the thyristor 40 , the MOSFET 41 and the IGBT 43 of the current interruption unit 4 based on the command signal from the control unit 5 .

Also, the voltage sensor 7 is configured to detect the output voltage of the current interrupter 4 (the voltage between the current interrupter 4 and the load 103).

(Operation of DC power supply)
Next, the operation of the DC power supply 100 will be described with reference to FIGS. 2 to 6. FIG.

First, a case in which the rectifier 1 is started to supply power to the load 103 when the DC power supply device 100 is started will be described.

As shown in (a) of FIG. 2, the IGBT 43 is turned on by transmitting a gate signal to the IGBT 43 . Then, as shown in FIG. 3, during a period I (see FIG. 2) from the transmission of the gate signal to the IGBT 43 to the transmission of the gate signal to the MOSFET 41 and the thyristor 40, the current from the rectifier 1 (the dashed line in FIG. 3) ) flows to the load 103 side through the diode element 42 and the IGBT 43 . As shown in (d) and (f) of FIG. 2, when the IGBT 43 is turned on, the output current value of the current interrupter 4 (see (d) of FIG. 2) and the current value flowing through the IGBT 43 (see (d) of FIG. 2) 2 (f)) is increased to a predetermined size.

In the present embodiment, as shown in FIGS. 2B and 2C, the control unit 5 turns on the IGBT 43 and then turns on the thyristor 40 and the MOSFET 41 to cut off the current. It is configured to perform control to conduct the section 4 .

Here, the output voltage of the current cutoff unit 4 is increased by turning on the IGBT 43 . In the present embodiment, the control unit 5 is configured to turn on the current interrupting unit 4 by controlling to turn on the thyristor 40 and the MOSFET 41 after the output voltage of the current interrupting unit 4 stops increasing. It is

Specifically, when the voltage value detected by the voltage sensor 7 rises to a predetermined maximum voltage, a signal is transmitted from the voltage sensor 7 to the controller 5 . When the control unit 5 receives the above signal from the voltage sensor 7 , the control unit 5 gives a command signal to the drive unit 6 to transmit a gate signal for turning on the thyristor 40 and the MOSFET 41 . Thereby, the period B of FIG. 2 is started.

Specifically, the thyristor 40 and the MOSFET 41 are turned on by sending a gate signal to the thyristor 40 and the MOSFET 41 . Then, as shown in FIG. 4, in the period B (see FIG. 2), the current from the rectifier 1 (see the broken line in FIG. 4) flows through the series circuit of the diode element 42 and the IGBT 43 and the series circuit of the thyristor 40 and the MOSFET 41. , and flows to the load 103 side.

As shown in (e) of FIG. 2, by turning on the thyristor 40, the current value flowing through the thyristor 40 increases to a predetermined magnitude. Note that the current flowing only to the series circuit side of the diode element 42 and the IGBT 43 in the period I also flows to the series circuit side of the thyristor 40 and the MOSFET 41 in the period B, so the current value flowing through the IGBT 43 in the period B is less than the current value.

Here, in the present embodiment, the total value of the ON voltage (forward voltage) _VF of the diode element 42 and the ON voltage (collector-emitter saturation voltage) Vce of the IGBT 43 is equal to the ON voltage (forward voltage) Vth of the thyristor 40. It is larger than the sum of the ON voltage (drain-source voltage) V _DS of the MOSFET 41 . Specifically, the relationship is (V _F +Vce)>>(Vth+V _DS ). The ratio between the value of current flowing through the series circuit of thyristor 40 and MOSFET 41 and the value of current flowing through the series circuit of diode element 42 and IGBT 43 is determined by the ON voltages of the four elements. Due to the above relationship of the total value of the on-voltages, the value of current flowing through the series circuit of thyristor 40 and MOSFET 41 is greater than the value of current flowing through the series circuit of diode element 42 and IGBT 43 . The value of current flowing through the series circuit of thyristor 40 and MOSFET 41 is, for example, about 20 times the value of current flowing through the series circuit of diode element 42 and IGBT 43 .

As a result, a relatively small current flows through diode element 42 and IGBT 43, so that the amount of heat generated by diode element 42 and IGBT 43 can be made relatively small. Further, by arranging an element having a low drain-source resistance as the MOSFET 41, the amount of heat generated by the MOSFET 41 can be reduced. This makes it possible to reduce the amount of heat generated by components other than the thyristor 40 . As a result, a heat sink (not shown) for dissipating heat from the current interrupting section 4 should be designed in consideration of only the amount of heat generated by the thyristor 40 (without considering the amount of heat generated by the MOSFET 41, the IGBT 43, and the diode element 42). becomes possible, and the heat radiator can be miniaturized.

Next, the operation of the DC power supply device 100 when power supply to the load 103 is stopped will be described.

First, when the current value detected by the current sensor 3 exceeds a preset range, a signal is transmitted from the current sensor 3 to the controller 5 . Then, the controller 5 to which the signal has been notified transmits a command signal for interrupting the current interrupter 4 to the drive unit 6 . A specific description will be given below.

In the present embodiment, as shown in (a) to (c) of FIG. 2, the control unit 5 controls to turn off the thyristor 40 and the MOSFET 41 at the same time, and then controls to turn off the IGBT 43. It is configured. Specifically, gate signals for turning off thyristor 40 and MOSFET 41 are sent to thyristor 40 and MOSFET 41 at the same time. Thereby, the period C is started. After that, a gate signal for turning off the IGBT 43 is sent to the IGBT 43, and period C ends.

As a result, as shown in (d) to (f) of FIG. 2, the value of the current flowing through the thyristor 40 during the period C is smaller than the value of the current flowing through the thyristor 40 during the period B (see (e) of FIG. 2). are doing. Further, the value of the current flowing through the IGBT 43 during the period C is greater than the value of the current flowing through the IGBT 43 during the period B (see (f) in FIG. 2). As shown in FIG. 5, when the MOSFET 41 is turned off, no current flows through the series circuit of the thyristor 40 and the MOSFET 41, so that the current flowing through the thyristor 40 and the MOSFET 41 during the period B (see FIG. 4) is reduced to This is due to commutation to the IGBT 43 side during period C. Since the IGBT 43 is in a conducting state when the MOSFET 41 is turned off, the high voltage (rated voltage) is not applied to the MOSFET 41 .

Further, the thyristor 40 has a characteristic that it continues to be on if a current (holding current) flows even if the gate is turned off. As a result, the current flowing through the thyristor 40 becomes zero and the thyristor 40 is turned off. As a result, the thyristor 40 can be turned off without providing a circuit for forcibly turning off the thyristor 40 by supplying a canceling current to the thyristor 40, for example.

Further, in the present embodiment, the control unit 5 performs control to turn off the MOSFET 41, so that the current flowing through the series circuit of the thyristor 40 and the MOSFET 41 is commutated to the IGBT 43 side. Afterwards, the IGBT 43 is controlled to be turned off, thereby controlling the current cut-off section 4 to be cut off. Specifically, the controller 5 is configured to turn off the IGBT 43 after the value of the current flowing through the thyristor 40 becomes zero.

Specifically, as shown in FIG. 2 , the control unit 5 controls to turn off the IGBT 43 after a time t longer than the turn-off time of the thyristor 40 since the control to turn off the MOSFET 41 is performed. It is configured to perform control to shut off the portion 4 . Specifically, the gate-off signal is transmitted to IGBT 43 after time t has passed since the gate-off signal was transmitted to each of MOSFET 41 and thyristor 40 . When the turn-off time of the thyristor 40 is, for example, 0.5 to 1 ms, it is preferable to set the time t to about 1 to 2 ms, which is about twice the turn-off time of the thyristor 40 .

Then, as shown in FIG. 6, no current flows through the IGBT 43 during a period D after the IGBT 43 is turned off. As shown in (d) to (f) of FIG. 2, in the period D, the output current of the current interrupting unit 4 (see (d) of FIG. 2), the current flowing through the thyristor 40 (see (e) of FIG. 2) ), and the current flowing through the IGBT 43 (see (f) in FIG. 2) become zero. As a result, the current interruption control by the current interruption section 4 is completed. When the IGBT 43 is turned off, the rated voltage is applied to each of the IGBT 43 and the thyristor 40, while almost no voltage is applied to the MOSFET 41. FIG.

Further, when power is not supplied from system 101 due to a power outage or the like, DC power of power storage unit 2 is supplied to load 103 . In this case, the control unit 5 is configured to perform control of conducting and interrupting the current flowing from the power storage unit 2 by the current interrupting unit 4 . The control method for conducting and interrupting the current from the power storage unit 2 is the same as the above-described method (see FIG. 2) for conducting and interrupting the current from the rectifier 1, so detailed description will be omitted.

By turning off the IGBT 43, which is a semiconductor switching element, the current flowing through the current interrupting section 4 is interrupted. Therefore, unlike the case where the current is interrupted only by a mechanical switch, arcing does not occur. Therefore, it is possible to interrupt the current at high speed without separately providing a configuration for forcibly extinguishing the arc.

In addition, when a mechanical switch is used, it is generally more difficult to extinguish a direct current arc than it is to extinguish an alternating current arc, so the switches that can be selected are limited. Therefore, by interrupting the current with the IGBT 43, which is a semiconductor switching element, it is possible to eliminate the inconvenience of limiting the options of the element (switch).

In addition, unlike the case where a mechanical switch continues to be conductive for a certain period of time due to arcing, there is no need to provide a fuse element or the like to provide overcurrent protection. As a result, it is possible to omit the trouble of replacing the fuse element or the like, which is performed when the fuse element or the like deteriorates over time.

[Effect of this embodiment]
The following effects can be obtained in this embodiment.

In the present embodiment, as described above, the current interrupting unit 4 is connected in series with the thyristor 40 having a withstand voltage higher than the rated voltage of the DC voltage, and the thyristor 40 on the load 103 side in series, and has a withstand voltage higher than the rated voltage. A series circuit having a small self arc-extinguishing MOSFET 41, and a self arc extinguishing IGBT 43 connected in parallel to the series circuit and having a withstand voltage higher than the rated voltage. Also, each of thyristor 40 and MOSFET 41 has smaller conduction loss than IGBT 43 . Then, the DC power supply device 100 is configured so that the control unit 5 performs control to turn off the IGBT 43 after simultaneously performing control to turn off the thyristor 40 and the MOSFET 41 .

As a result, the current flowing through the thyristor 40 and the MOSFET 41 is commutated to the IGBT 43 , so the IGBT 43 can be turned off while all the current is flowing through the IGBT 43 . Here, since an arc does not occur in the IGBT 43 when it is turned off, there is no need to apply a superimposed current to the IGBT 43 using the charging energy of the capacitor in order to quickly turn off the IGBT 43 . Therefore, by controlling as described above, the fault current can be interrupted at high speed by the IGBT 43 without using a capacitor. As a result, the DC power supply device 100 can be miniaturized while interrupting the fault current at high speed.

In addition, the series circuit of the thyristor 40 and the MOSFET 41, which have a relatively small conduction loss compared to the IGBT 43, is connected in parallel with the IGBT 43, thereby achieving a relatively small conduction loss unlike the case where only the IGBT 43 is provided. At least a portion of the current can also flow on the circuit side. As a result, conduction loss (power consumption) can be suppressed as compared with the case where only the IGBT 43 is provided. As a result, the fault current can be cut off at high speed while suppressing an increase in conduction loss, and the size of the DC power supply device 100 can be reduced.

Further, by commutating the current flowing through the thyristor 40 and the MOSFET 41 to the IGBT 43, the IGBT 43 can be turned off in a state where the current does not flow through the thyristor 40 and the MOSFET 41. FIG. As a result, when the IGBT 43 is turned off, the rated voltage of the DC power supply device 100 is applied to the IGBT 43 and the thyristor 40, while the thyristor 40 provided in the preceding stage of the MOSFET 41 is in the off state, so the voltage applied to the MOSFET 41 becomes substantially zero. . As a result, it is possible to prevent a voltage (rated voltage) higher than the withstand voltage from being applied to the MOSFET 41, so that it is possible to prevent the MOSFET 41 from being destroyed. Since the breakdown voltage of each of thyristor 40 and MOSFET 41 is equal to or higher than the rated voltage, each of thyristor 40 and MOSFET 41 is not destroyed. Thereby, it is possible to suppress the destruction of the element of the current interrupting portion 4 (MOSFET 41).

Here, if there is a time difference between the control to turn off the thyristor 40 and the control to turn off the MOSFET 41, the control to turn off the IGBT 43 is delayed by the time difference, so the time during which the current flows through the IGBT 43 increases. Simultaneously performing the control to turn off the thyristor 40 and the MOSFET 41 can suppress the delay in the control to turn off the IGBT 43 and suppress the increase in the time during which the current flows through the IGBT 43 . Here, the size of the IGBT 43 depends on the energizable time. Therefore, it is possible to suppress the IGBT 43 from increasing in size by suppressing an increase in the time during which the current flows through the IGBT 43 .

Further, in the present embodiment, as described above, the control unit 5 performs control to turn off the MOSFET 41, so that the current flowing through the series circuit of the thyristor 40 and the MOSFET 41 is commutated to the IGBT 43 side. The DC power supply device 100 is configured to perform control to cut off the current cutoff unit 4 by controlling to turn off the IGBT 43 after the current stops flowing. This can prevent the IGBT 43 from being turned off while current is still flowing through the series circuit of the thyristor 40 and the MOSFET 41 . As a result, when the IGBT 43 is turned off, the thyristor 40 can be reliably turned off. As a result, application of a high voltage (rated voltage) to the MOSFET 41 can be more reliably suppressed.

Further, in the present embodiment, as described above, the control unit 5 performs control to turn off the IGBT 43 after a time t longer than the turn-off time of the thyristor 40 since the control to turn off the MOSFET 41 is performed, thereby reducing the current The DC power supply device 100 is configured so as to perform control to cut off the cutoff unit 4 . As a result, the control to turn off the IGBT 43 can be more reliably performed after the current stops flowing through the thyristor 40 .

Further, in the present embodiment, as described above, the control unit 5 performs control to turn on the thyristor 40 and the MOSFET 41 after performing control to turn on the IGBT 43, thereby controlling to turn on the current interrupting unit 4. The DC power supply device 100 is configured as follows. As a result, it is possible to prevent the thyristor 40 and the MOSFET 41 from being turned on while the IGBT 43 is turned off. can be done.

Further, in the present embodiment, as described above, the control unit 5 controls the thyristor 40 and the MOSFET 41 after the output voltage of the current interrupting unit 4 is increased by turning on the IGBT 43 and the output voltage stops increasing. By performing control to turn it on, it is configured to perform control to turn on the current interrupting section 4 . Here, the voltage applied to the IGBT 43 decreases as the output voltage of the current interrupter 4 increases. Therefore, the thyristor 40 and the MOSFET 41 can be turned on after the voltage applied to the IGBT 43 is minimized by performing control to turn on the thyristor 40 and the MOSFET 41 after the output voltage of the current interrupting unit 4 stops increasing. As a result, the same voltage as the voltage applied to the IGBT 43 is applied to the MOSFET 41 connected in parallel with the IGBT 43, so that application of a high voltage to the MOSFET 41 can be suppressed.

Further, in the present embodiment, as described above, the total value of the on-voltage _VF of the diode element 42 and the on-voltage Vce of the IGBT 43 is higher than the total value of the on-voltage Vth of the thyristor 40 and the on-voltage _VDS of the MOSFET 41. The DC power supply device 100 is configured so that .DELTA. As a result, the current flowing through the series circuit of the diode element 42 and the IGBT 43, which have a relatively large total ON voltage, can be made relatively small. As a result, the amount of heat generated by diode element 42 and IGBT 43 can be made relatively small.

Also, since the conduction loss of each of thyristor 40 and MOSFET 41 is smaller than the conduction loss of IGBT 43 , the ON resistance of each of thyristor 40 and MOSFET 41 is relatively smaller than the ON resistance of IGBT 43 . Therefore, by applying a relatively larger current than the current flowing through the series circuit of the diode element 42 and the IGBT 43 to the thyristor 40 and the MOSFET 41, which have relatively low on-resistance, an increase in the amount of heat generated by the thyristor 40 and the MOSFET 41 can be minimized. can be suppressed. As a result, it is possible to suppress an increase in the amount of heat generated by the current interrupting portion 4 as a whole.

Further, in the present embodiment, as described above, when the DC power of the power storage unit 2 is supplied to the load 103, the control unit 5 simultaneously turns off the thyristor 40 and the MOSFET 41, and then turns off the IGBT 43. The DC power supply device 100 is configured to perform control to As a result, it is possible to suppress damage to the elements of the current interrupting section 4 while suppressing an increase in conduction loss during current conduction.

Moreover, in this embodiment, as described above, the DC power supply device 100 is configured such that the elements of the current interrupting section 4 include the thyristor 40, the MOSFET 41, and the IGBT 43. FIG. As a result, since the thyristor has a relatively low on-voltage, the use of the thyristor 40 as the thyristor 40 effectively suppresses an increase in conduction loss during current conduction (during normal operation of the DC power supply 100). can be done. In addition, since the IGBT switches at a relatively high speed and has a high withstand voltage, by using the IGBT 43 as the IGBT 43, the current can be interrupted at high speed, and even when a high voltage (rated voltage) is applied to the IGBT 43, the IGBT 43 can You can prevent it from being destroyed. Also, since MOSFETs have relatively low conduction loss, by using MOSFET 41 as MOSFET 41, it is possible to more effectively suppress an increase in conduction loss during current conduction (during normal operation of the DC power supply). Further, since the MOSFET switches at a relatively high speed, the current flowing through the DC circuit of the thyristor 40 and the MOSFET 41 can be commutated to the IGBT 43 side relatively quickly when the current is interrupted. As a result, the time required for the current interrupter 4 to interrupt the current can be shortened.

[Modification]
It should be noted that the embodiments disclosed this time should be considered as examples and not restrictive in all respects. The scope of the present invention is indicated by the scope of the claims rather than the above description of the embodiments, and includes all modifications (modifications) within the scope and meaning equivalent to the scope of the claims.

For example, in the above-described embodiment, an example is shown in which control is performed to turn off the IGBT 43 (semiconductor switching element) after simultaneously turning off the thyristor 40 (series switching element) and the MOSFET 41 (conduction switching element). The present invention is not limited to this. For example, the control unit 5 may perform control to cut off the current cutoff unit 4 by turning off the thyristor 40, the MOSFET 41, and the IGBT 43 in this order. Also when power is supplied to the load 103 with the electric power of the power storage unit 2, control may be performed to turn off the thyristor 40, the MOSFET 41, and the IGBT 43 in this order.

Moreover, in the above embodiment, an example in which the thyristor 40 is provided as a switching element was shown, but the present invention is not limited to this. For example, a mechanical switch may be provided instead of thyristor 40 . In this case, by commutating the current by turning off the MOSFET 41, the current flowing through the mechanical switch can be easily reduced to zero. can be suppressed. As a result, even if a mechanical switch is used, it is possible to prevent the time required for current interruption from becoming longer. Also, a bipolar transistor may be provided instead of the thyristor 40 . Power consumption can be further reduced by using a mechanical switch instead of the thyristor 40 .

In the above embodiment, the control unit 5 controls to turn on the thyristor 40 (series switching element) and the MOSFET 41 (conduction switching element) after the output voltage of the current interrupting unit 4 stops increasing. However, the present invention is not limited to this. For example, the control unit 5 may perform control to turn on the thyristor 40 and the MOSFET 41 when the output voltage exceeds a predetermined threshold even while the output voltage is increasing.

Moreover, in the above embodiment, an example in which the MOSFET 41 is provided as the conduction switching element was shown, but the present invention is not limited to this. For example, instead of MOSFET 41, a mechanical switch may be provided.

Moreover, although the example which provided IGBT43 as a switching element was shown in the said embodiment, this invention is not limited to this. For example, SiC-MOSFET may be provided instead of IGBT43.

REFERENCE SIGNS LIST 1 rectifier 2 power storage unit 4 current interrupting unit 5 control unit 40 thyristor (series switching element)
41 MOSFET (conduction switching element)
42 diode element 43 IGBT (semiconductor switching element)
100 DC power supply 101 system (AC voltage source)
103 load t time (predetermined time)
Vce ON voltage (ON voltage of semiconductor switching element)
V _DS on-voltage (on-voltage of conduction switching element)
_VF on-voltage (on-voltage of diode element)
Vth ON voltage (ON voltage of switching element)

Claims (7)

a rectifier for converting an AC input voltage supplied from an AC voltage source to a DC voltage;
a current interrupter for electrically connecting and disconnecting between the rectifier and the load;
A control unit that controls the rectifier and the current interrupter,
The current interrupter is
a series switching element having a withstand voltage higher than the rated voltage of the DC voltage; and a self-arc-extinguishing conduction switching element connected in series to the series switching element on the load side and having a withstand voltage lower than the rated voltage. and a series circuit having
a self arc-extinguishing semiconductor switching element connected in parallel to the series circuit and having a withstand voltage higher than the rated voltage;
Each of the series switching element and the conduction switching element has a conduction loss smaller than that of the semiconductor switching element,
The control unit turns off the series switching element and the conduction switching element at the same time, and then turns off the semiconductor switching element. By performing control to turn off the semiconductor switching elements in order, it is configured to perform control to cut off the current cutoff part,
The current interrupting unit includes a diode element connected in parallel to the series circuit and connected in series with the semiconductor switching element,
The total value of the on-voltage of the diode element and the on-voltage of the semiconductor switching element is greater than the total value of the on-voltage of the series switching element and the on-voltage of the conduction switching element. a current value flowing through the semiconductor switching element is smaller than a current value flowing through the series switching element and the conduction switching element;
Further comprising a power storage unit that stores the DC power converted by the rectifier,
The control unit controls to turn off the semiconductor switching element after simultaneously performing control to turn off the series switching element and the conduction switching element when the DC power of the power storage unit is supplied to the load. Alternatively, by performing control to turn off the series switching element, the conduction switching element, and the semiconductor switching element in this order, the current interrupting unit interrupts the current flowing from the power storage unit to the load. A DC power supply configured to : The control section simultaneously performs control to turn off the series switching element and the conduction switching element, and then performs control to turn off the semiconductor switching element, thereby performing control to cut off the current cutoff section. 2. The DC power supply of claim 1, wherein the DC power supply is configured as The control unit performs control to turn off the conduction switching element, thereby commutating the current flowing through the series circuit of the series switching element and the conduction switching element to the semiconductor switching element side. 3. The direct current according to claim 1 or 2, wherein the control is performed to turn off the semiconductor switching element after the current stops flowing through the switching element, thereby controlling the current interrupting section to be cut off. Power supply. The conduction switching element is configured to be capable of switching at a higher speed than the series switching element,
The control unit performs control to turn off the semiconductor switching element after a predetermined time equal to or longer than the turn-off time of the series switching element after the control to turn off the conduction switching element is performed, whereby the current interrupting unit 4. The DC power supply device according to claim 3, configured to perform control to cut off the . The control unit is configured to perform control to turn on the current interrupting unit by performing control to turn on the series switching element and the conduction switching element after performing control to turn on the semiconductor switching element. The DC power supply device according to any one of claims 1 to 4, wherein The control unit controls to turn on the series switching element and the conduction switching element after the output voltage of the current interrupting unit is increased by turning on the semiconductor switching element and after the output voltage stops increasing. 6. The direct-current power supply device according to claim 5, wherein said current interrupting section is controlled to conduct by performing the above. 7. The DC power supply device according to claim 1 , wherein said series switching element, said conduction switching element, and said semiconductor switching element respectively include a thyristor, MOSFET, and IGBT.

Images